Sample records for mont ser rat

  1. Mycobacterium tuberculosis Ser/Thr protein kinase B mediates...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Mycobacterium tuberculosis SerThr protein kinase B mediates an oxygen-dependent replication switch. Mycobacterium tuberculosis SerThr protein kinase B mediates an...

  2. Monte Carlo event generators

    SciTech Connect (OSTI)

    Frixione, Stefano [INFN, Sezione di Genova, Via Dodecaneso 33, 16146 Genova (Italy)

    2005-10-06T23:59:59.000Z

    I review recent progress in the physics of parton shower Monte Carlos, emphasizing the ideas which allow the inclusion of higher-order matrix elements into the framework of event generators.

  3. Monte Carlo photon benchmark problems

    SciTech Connect (OSTI)

    Whalen, D.J.; Hollowell, D.E.; Hendricks, J.S.

    1991-01-01T23:59:59.000Z

    Photon benchmark calculations have been performed to validate the MCNP Monte Carlo computer code. These are compared to both the COG Monte Carlo computer code and either experimental or analytic results. The calculated solutions indicate that the Monte Carlo method, and MCNP and COG in particular, can accurately model a wide range of physical problems.

  4. MCMini: Monte Carlo on GPGPU

    SciTech Connect (OSTI)

    Marcus, Ryan C. [Los Alamos National Laboratory

    2012-07-25T23:59:59.000Z

    MCMini is a proof of concept that demonstrates the possibility for Monte Carlo neutron transport using OpenCL with a focus on performance. This implementation, written in C, shows that tracing particles and calculating reactions on a 3D mesh can be done in a highly scalable fashion. These results demonstrate a potential path forward for MCNP or other Monte Carlo codes.

  5. Quantum Gibbs ensemble Monte Carlo

    SciTech Connect (OSTI)

    Fantoni, Riccardo, E-mail: rfantoni@ts.infn.it [Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, Calle Larga S. Marta DD2137, I-30123 Venezia (Italy); Moroni, Saverio, E-mail: moroni@democritos.it [DEMOCRITOS National Simulation Center, Istituto Officina dei Materiali del CNR and SISSA Scuola Internazionale Superiore di Studi Avanzati, Via Bonomea 265, I-34136 Trieste (Italy)

    2014-09-21T23:59:59.000Z

    We present a path integral Monte Carlo method which is the full quantum analogue of the Gibbs ensemble Monte Carlo method of Panagiotopoulos to study the gas-liquid coexistence line of a classical fluid. Unlike previous extensions of Gibbs ensemble Monte Carlo to include quantum effects, our scheme is viable even for systems with strong quantum delocalization in the degenerate regime of temperature. This is demonstrated by an illustrative application to the gas-superfluid transition of {sup 4}He in two dimensions.

  6. MARINE ECOLOGY PROGRESS SERIES Mar Ecol Prog Ser

    E-Print Network [OSTI]

    Pierce, Stephen

    MARINE ECOLOGY PROGRESS SERIES Mar Ecol Prog Ser Vol. 389: 271­294, 2009 doi: 10.3354/meps08153, partly by mining a wealth of in- formation painstakingly accumulated over past decades on species

  7. MARINE ECOLOGY PROGRESS SERIES Mar Ecol Prog Ser

    E-Print Network [OSTI]

    Townsend, David W.

    MARINE ECOLOGY PROGRESS SERIES Mar Ecol Prog Ser Vol. 427: 29­49, 2011 doi: 10.3354/meps09043 Published April 12 INTRODUCTION The Gulf of Maine (GoM) is a semi-enclosed conti- nental shelf system to storm events in fall; (2) gradual chloro- phyll increases in response to seasonal wind- and cooling

  8. MARINE ECOLOGY PROGRESS SERIES Mar Ecol Prog Ser

    E-Print Network [OSTI]

    White, Angelicque

    MARINE ECOLOGY PROGRESS SERIES Mar Ecol Prog Ser Vol. 323: 35­45, 2006 Published October 5 derived from the lit- erature, resultant model solutions allow us to explore the ecological significance, a scenario termed P-mining. Given the temporal phasing of these migrations, our results indicate that while

  9. MARINE ECOLOGY PROGRESS SERIES Mar Ecol Prog Ser

    E-Print Network [OSTI]

    Boyce, C. Kevin

    MARINE ECOLOGY PROGRESS SERIES Mar Ecol Prog Ser Vol. 228: 153­163, 2002 Published March 6 of California, Berkeley, California 94720, USA 2 Ecology, Behavior and Evolution Section, Division of Biology and non-carnivorous species within climatic zones play an important role in deter- mining

  10. MARINE ECOLOGY PROGRESS SERIES Mar Ecol Prog Ser

    E-Print Network [OSTI]

    Maldonado, Manuel

    (Escherichia coli and Vibrio anguillarum), and 1 marine yeast Rhodotorula sp. All 3 microbes were ingestedMARINE ECOLOGY PROGRESS SERIES Mar Ecol Prog Ser Vol. 403: 75­89, 2010 doi: 10.3354/meps08411, Spain 2 Marine Bioproducts Engineering Group, Dalian Institute of Chemical Physics, Chinese Academic

  11. MARINE ECOLOGY PROGRESS SERIES Mar Ecol Prog Ser

    E-Print Network [OSTI]

    MARINE ECOLOGY PROGRESS SERIES Mar Ecol Prog Ser Vol. 340: 259­270, 2007 Published June 18 be several warming and cooling periods, spanning sev- eral decades each. This has been documented, for example, in British waters where a cooling trend was detected up to about 1930, followed by a warming

  12. MARINE ECOLOGY PROGRESS SERIES Mar Ecol Prog Ser

    E-Print Network [OSTI]

    Poulin, Robert

    . An increased impact of parasites on amphipod popula- tions with global warming is predicted and the possibleMARINE ECOLOGY PROGRESS SERIES Mar Ecol Prog Ser Vol. 415: 11­22, 2010 doi: 10.3354/meps08742, particularly global warming, on parasitism should be of major concern. Probably the best-studied marine

  13. CMU-ITC-86_-OI7 de U ser's Guide

    E-Print Network [OSTI]

    CMU-ITC-86_-OI7 de U ser's Guide Come into my parlor ... de by Marc Donner #12;#12;/ A smwey or and holding the left button. The cursor will change to a circle with a crosshair in it, indicating that you

  14. FRZ Section Enrollment Report (SER) -Table of Contents Subject Description

    E-Print Network [OSTI]

    Pittendrigh, Barry

    Science NUCL Nuclear Engineering NUPH Nuclear Pharmacy NUR Nursing OBHR Orgnztnl Bhvr & Humn Resources OLS Enrollment Report (SER) - Table of Contents Subject Description CLPH Clinical Pharmacy CMCI CIC Common Market Organiz Ldrshp And Supervision PES Physical Education Skills PHAD Pharmacy Administration #12;FRZ Section

  15. FRZ Section Enrollment Report (SER) -Table of Contents Subject Description

    E-Print Network [OSTI]

    Pittendrigh, Barry

    Engineering NUPH Nuclear Pharmacy NUR Nursing OBHR Orgnztnl Bhvr & Humn Resources OLS Organiz Ldrshp Enrollment Report (SER) - Table of Contents Subject Description CLPH Clinical Pharmacy CMCI CIC Common Market & Leadership MUS Music History & Theory NS Naval Science NRES Natural Res & Environ Science NUCL Nuclear

  16. Is Monte Carlo embarrassingly parallel?

    SciTech Connect (OSTI)

    Hoogenboom, J. E. [Delft Univ. of Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Delft Nuclear Consultancy, IJsselzoom 2, 2902 LB Capelle aan den IJssel (Netherlands)

    2012-07-01T23:59:59.000Z

    Monte Carlo is often stated as being embarrassingly parallel. However, running a Monte Carlo calculation, especially a reactor criticality calculation, in parallel using tens of processors shows a serious limitation in speedup and the execution time may even increase beyond a certain number of processors. In this paper the main causes of the loss of efficiency when using many processors are analyzed using a simple Monte Carlo program for criticality. The basic mechanism for parallel execution is MPI. One of the bottlenecks turn out to be the rendez-vous points in the parallel calculation used for synchronization and exchange of data between processors. This happens at least at the end of each cycle for fission source generation in order to collect the full fission source distribution for the next cycle and to estimate the effective multiplication factor, which is not only part of the requested results, but also input to the next cycle for population control. Basic improvements to overcome this limitation are suggested and tested. Also other time losses in the parallel calculation are identified. Moreover, the threading mechanism, which allows the parallel execution of tasks based on shared memory using OpenMP, is analyzed in detail. Recommendations are given to get the maximum efficiency out of a parallel Monte Carlo calculation. (authors)

  17. Monte Carlo calculations of nuclei

    SciTech Connect (OSTI)

    Pieper, S.C. [Argonne National Lab., IL (United States). Physics Div.

    1997-10-01T23:59:59.000Z

    Nuclear many-body calculations have the complication of strong spin- and isospin-dependent potentials. In these lectures the author discusses the variational and Green`s function Monte Carlo techniques that have been developed to address this complication, and presents a few results.

  18. PATCHY SILICA-COATED SILVER NANOWIRES AS SERS SUBSTRATES

    SciTech Connect (OSTI)

    Murph, S.; Murphy, C.

    2013-03-29T23:59:59.000Z

    We report a class of core-shell nanomaterials that can be used as efficient surface-enhancement Raman scattering (SERS) substrates. The core consists of silver nanowires, prepared through a chemical reduction process, that are used to capture 4- mercaptobenzoic acid (4-MBA), a model analyte. The shell was prepared through a modified Stöber method and consists of patchy or full silica coats. The formation of silica coats was monitored via transmission electron microscopy, UV-visible spectroscopy and phase-analysis light scattering for measuring effective surface charge. Surprisingly, the patchy silica coated silver nanowires are better SERS substrate than silver nanowires; nanomolar concentration of 4-MBA can be detected. In addition, “nano-matryoshka” configurations were used to quantitate/explore the effect of the electromagnetic field at the tips of the nanowire (“hot spots”) in the Raman scattering experiment.

  19. Shell model Monte Carlo methods

    SciTech Connect (OSTI)

    Koonin, S.E. [California Inst. of Tech., Pasadena, CA (United States). W.K. Kellogg Radiation Lab.; Dean, D.J. [Oak Ridge National Lab., TN (United States)

    1996-10-01T23:59:59.000Z

    We review quantum Monte Carlo methods for dealing with large shell model problems. These methods reduce the imaginary-time many-body evolution operator to a coherent superposition of one-body evolutions in fluctuating one-body fields; resultant path integral is evaluated stochastically. We first discuss the motivation, formalism, and implementation of such Shell Model Monte Carlo methods. There then follows a sampler of results and insights obtained from a number of applications. These include the ground state and thermal properties of pf-shell nuclei, thermal behavior of {gamma}-soft nuclei, and calculation of double beta-decay matrix elements. Finally, prospects for further progress in such calculations are discussed. 87 refs.

  20. Watching individual molecules flex within lipid membranes using SERS

    E-Print Network [OSTI]

    Taylor, Richard W.; Benz, Felix; Sigle, Daniel O.; Bowman, Richard W.; Bao, Peng; Roth, Johannes S.; Heath, George R.; Evans, Stephen D.; Baumberg, Jeremy J.

    2014-08-12T23:59:59.000Z

    calculations for plasmonic coupling across a gap of 5 nm, corresponding to the height of the HBL of 4.4 6 0.6 nm measured by atomic force microscopy (AFM, Fig.S3), with a dielec- tric constant er , 218. The reproducibility of the gap mode is attrib- uted... subnanometer gaps in plasmonic dimers using graphene. Nano Lett. 13, 5033–5038 (2013). 8. Taylor, R. W. et al. In situ SERS monitoring of photochemistry within a nanojunction reactor. Nano Lett. 13, 5985–5990 (2013). 9. Lingwood, D. & Simons, K. Lipid rafts...

  1. Monte Carlo Methods in Quantum Field Theory

    E-Print Network [OSTI]

    I. Montvay

    2007-05-30T23:59:59.000Z

    In these lecture notes some applications of Monte Carlo integration methods in Quantum Field Theory - in particular in Quantum Chromodynamics - are introduced and discussed.

  2. The MC21 Monte Carlo Transport Code

    SciTech Connect (OSTI)

    Sutton TM, Donovan TJ, Trumbull TH, Dobreff PS, Caro E, Griesheimer DP, Tyburski LJ, Carpenter DC, Joo H

    2007-01-09T23:59:59.000Z

    MC21 is a new Monte Carlo neutron and photon transport code currently under joint development at the Knolls Atomic Power Laboratory and the Bettis Atomic Power Laboratory. MC21 is the Monte Carlo transport kernel of the broader Common Monte Carlo Design Tool (CMCDT), which is also currently under development. The vision for CMCDT is to provide an automated, computer-aided modeling and post-processing environment integrated with a Monte Carlo solver that is optimized for reactor analysis. CMCDT represents a strategy to push the Monte Carlo method beyond its traditional role as a benchmarking tool or ''tool of last resort'' and into a dominant design role. This paper describes various aspects of the code, including the neutron physics and nuclear data treatments, the geometry representation, and the tally and depletion capabilities.

  3. Novel Ser/Thr Protein Phosphatase 5 (PP5) Regulated Targets during...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    SerThr Protein Phosphatase 5 (PP5) Regulated Targets during DNA Damage Identified by Proteomics Analysis. Novel SerThr Protein Phosphatase 5 (PP5) Regulated Targets during DNA...

  4. Exponential convergence with adaptive Monte Carlo

    SciTech Connect (OSTI)

    Booth, T.E.

    1997-11-01T23:59:59.000Z

    For over a decade, it has been known that exponential convergence on discrete transport problems was possible using adaptive Monte Carlo techniques. Now, exponential convergence has been empirically demonstrated on a spatially continuous problem.

  5. THE BEGINNING of the MONTE CARLO METHOD

    E-Print Network [OSTI]

    . For a whole host of 125 #12;Monte Carlo reasons, he had become seriously inter- ested in the thermonuclear a preliminary computational model of a thermonuclear reaction for the ENIAC. He felt he could convince

  6. The role of Monte Carlo within a diagonalization/Monte Carlo scheme

    E-Print Network [OSTI]

    Dean Lee

    2000-10-31T23:59:59.000Z

    We review the method of stochastic error correction which eliminates the truncation error associated with any subspace diagonalization. Monte Carlo sampling is used to compute the contribution of the remaining basis vectors not included in the initial diagonalization. The method is part of a new approach to computational quantum physics which combines both diagonalization and Monte Carlo techniques.

  7. Fractured reservoir evaluation using Monte Carlo techniques

    SciTech Connect (OSTI)

    Sears, G.F.; Phillips, N.V.

    1987-01-01T23:59:59.000Z

    Pro forma cash-flow analysis of petroleum ventures usually is considered as a deterministic model. In the last 10 years, Monte Carlo analysis has allowed the introduction of probability distributions of input variables in place of single-valued functions. Reserve determination and rate scheduling in these current Monte Carlo techniques have relied on the volumetric formula, which works well in nonfractured reservoirs. Recent massive drilling in fractured reservoirs has rendered this approach unusable. This paper develops a variation of the Arps rate-cumulative equation as a basic model for the determination of the distribution of original reserves and the decline rates. Continuation of the Monte Carlo technique into net present value analysis and internal rate of return (IRR) is also developed.

  8. Examining metal nanoparticle surface chemistry using hollow-core, photonic-crystal, fiber-assisted SERS

    E-Print Network [OSTI]

    the enhancement of the local electromagnetic field of metal NPs due to excitation of localized surface plasmons [1 to monitor minute amounts of sur- face ligands on gold nanoparticles used as an SERS substrate. The SERS--mercaptopoly(ethylene glycol) on the surface of gold nanorods as an exemplary system, we show the feasibility of using HCPCF

  9. Monte Carlo event reconstruction implemented with artificial neural networks

    E-Print Network [OSTI]

    Tolley, Emma Elizabeth

    2011-01-01T23:59:59.000Z

    I implemented event reconstruction of a Monte Carlo simulation using neural networks. The OLYMPUS Collaboration is using a Monte Carlo simulation of the OLYMPUS particle detector to evaluate systematics and reconstruct ...

  10. anatomy monte carlo: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    22 23 24 25 Next Page Last Page Topic Index 1 Optical Monte Carlo modeling of a true port wine stain anatomy Biology and Medicine Websites Summary: Optical Monte Carlo modeling of...

  11. Monte Carlo Tools for Jet Quenching

    E-Print Network [OSTI]

    Korinna Zapp

    2011-09-07T23:59:59.000Z

    A thorough understanding of jet quenching on the basis of multi-particle final states and jet observables requires new theoretical tools. This talk summarises the status and propects of the theoretical description of jet quenching in terms of Monte Carlo generators.

  12. MONTE CARLO CALCULATIONS OF LR115 DETECTOR RESPONSE TO 222

    E-Print Network [OSTI]

    Yu, K.N.

    (4):414­419; 2000 Key words: Monte Carlo; radon progeny; detector, alpha- track; thoron INTRODUCTION THE LR115

  13. Multiple Overlapping Tiles for Contextual Monte Carlo Tree Search

    E-Print Network [OSTI]

    for linear transforms [4] or active learning [8]. The use of Monte Carlo simulations to evaluate a situation- tions depending on the context. The modification is based on a reward function learned on a tiling of the space of Monte Carlo simulations. The tiling is done by regrouping the Monte Carlo simulations where two

  14. John von Neumann Institute for Computing Monte Carlo Protein Folding

    E-Print Network [OSTI]

    Hsu, Hsiao-Ping

    John von Neumann Institute for Computing Monte Carlo Protein Folding: Simulations of Met://www.fz-juelich.de/nic-series/volume20 #12;#12;Monte Carlo Protein Folding: Simulations of Met-Enkephalin with Solvent-Accessible Area difficulties in applying Monte Carlo methods to protein folding. The solvent-accessible area method, a popular

  15. RATS VERSUS PEOPLE Rats equal twice

    E-Print Network [OSTI]

    , ----= -, - paper car ton s, and wooden containers are easily damaged. #12;By Starting Fires Rats start fires by damaging the insu- lation of electric wiring. A survey of 39 cities showed that 530 fires were started

  16. The use of Surface Enhanced Raman Spectroscopy (SERS) for biomedical applications

    E-Print Network [OSTI]

    Chowdhury, Mustafa Habib

    2007-04-25T23:59:59.000Z

    to poor data reproducibility. The different methods examined to create robust SERS substrates include the creation of thermally evaporated silver island films on microscope glass slides, using the technique of Nanosphere Lithography (NSL) to create...

  17. The use of Surface Enhanced Raman Spectroscopy (SERS) for biomedical applications 

    E-Print Network [OSTI]

    Chowdhury, Mustafa Habib

    2007-04-25T23:59:59.000Z

    Recent advances in nanotechnology and the biotechnology revolution have created an immense opportunity for the use of noble metal nanoparticles as Surface Enhanced Raman Spectroscopy (SERS) substrates for biological sensing and diagnostics...

  18. Random number stride in Monte Carlo calculations

    SciTech Connect (OSTI)

    Hendricks, J.S.

    1990-01-01T23:59:59.000Z

    Monte Carlo radiation transport codes use a sequence of pseudorandom numbers to sample from probability distributions. A common practice is to start each source particle a predetermined number of random numbers up the pseudorandom number sequence. This number of random numbers skipped between each source particles the random number stride, S. Consequently, the jth source particle always starts with the j{center dot}Sth random number providing correlated sampling'' between similar calculations. A new machine-portable random number generator has been written for the Monte Carlo radiation transport code MCNP providing user's control of the random number stride. First the new MCNP random number generator algorithm will be described and then the effects of varying the stride will be presented. 2 refs., 1 fig.

  19. Controlling Rats and Mice

    E-Print Network [OSTI]

    Texas Wildlife Services

    2007-03-13T23:59:59.000Z

    at least 18 inches off the ground. 18? 18? TCE?Wildlife Services P.O. Box 100410 ? San Antonio, Texas 78201-1710 Rat-proofing Whenever it can be accomplished at a rea- sonable cost, rat-proofing is recommended as the most permanent means of control...

  20. Using the sequential regression (SER) algorithm for long-term signal processing. [Intrusion detection

    SciTech Connect (OSTI)

    Soldan, D. L.; Ahmed, N.; Stearns, S. D.

    1980-01-01T23:59:59.000Z

    The use of the sequential regression (SER) algorithm (Electron. Lett., 14, 118(1978); 13, 446(1977)) for long-term processing applications is limited by two problems that can occur when an SER predictor has more weights than required to predict the input signal. First, computational difficulties related to updating the autocorrelation matrix inverse could arise, since no unique least-squares solution exists. Second, the predictor strives to remove very low-level components in the input, and hence could implement a gain function that is essentially zero over the entire passband. The predictor would then tend to become a no-pass filter which is undesirable in certain applications, e.g., intrusion detection (SAND--78-1032). Modifications to the SER algorithm that overcome the above problems are presented, which enable its use for long-term signal processing applications. 3 figures.

  1. Status of Monte-Carlo Event Generators

    SciTech Connect (OSTI)

    Hoeche, Stefan; /SLAC

    2011-08-11T23:59:59.000Z

    Recent progress on general-purpose Monte-Carlo event generators is reviewed with emphasis on the simulation of hard QCD processes and subsequent parton cascades. Describing full final states of high-energy particle collisions in contemporary experiments is an intricate task. Hundreds of particles are typically produced, and the reactions involve both large and small momentum transfer. The high-dimensional phase space makes an exact solution of the problem impossible. Instead, one typically resorts to regarding events as factorized into different steps, ordered descending in the mass scales or invariant momentum transfers which are involved. In this picture, a hard interaction, described through fixed-order perturbation theory, is followed by multiple Bremsstrahlung emissions off initial- and final-state and, finally, by the hadronization process, which binds QCD partons into color-neutral hadrons. Each of these steps can be treated independently, which is the basic concept inherent to general-purpose event generators. Their development is nowadays often focused on an improved description of radiative corrections to hard processes through perturbative QCD. In this context, the concept of jets is introduced, which allows to relate sprays of hadronic particles in detectors to the partons in perturbation theory. In this talk, we briefly review recent progress on perturbative QCD in event generation. The main focus lies on the general-purpose Monte-Carlo programs HERWIG, PYTHIA and SHERPA, which will be the workhorses for LHC phenomenology. A detailed description of the physics models included in these generators can be found in [8]. We also discuss matrix-element generators, which provide the parton-level input for general-purpose Monte Carlo.

  2. aux propositions Monte Verit Le Congressi Stefano Franscini, plate-

    E-Print Network [OSTI]

    Richner, Heinz

    Appel aux propositions Monte Verità Le Congressi Stefano Franscini, plate- forme de congrès de l'Ecole polytechnique fédérale de Zurich, offre la possibilité d'or- ganiser des conférences de recherche au Monte senior et junior, séjournant au Monte Verità pendant toute la durée de la conférence Le formulaire de

  3. Quantum Monte Carlo calculations for light nuclei

    SciTech Connect (OSTI)

    Wiringa, R.B.

    1998-08-01T23:59:59.000Z

    Quantum Monte Carlo calculations of ground and low-lying excited states for nuclei with A {le} 8 are made using a realistic Hamiltonian that fits NN scattering data. Results for more than 30 different (j{sup {prime}}, T) states, plus isobaric analogs, are obtained and the known excitation spectra are reproduced reasonably well. Various density and momentum distributions and electromagnetic form factors and moments have also been computed. These are the first microscopic calculations that directly produce nuclear shell structure from realistic NN interactions.

  4. Monte Carlo simulations on Graphics Processing Units

    E-Print Network [OSTI]

    Vadim Demchik; Alexei Strelchenko

    2009-03-30T23:59:59.000Z

    Implementation of basic local Monte-Carlo algorithms on ATI Graphics Processing Units (GPU) is investigated. The Ising model and pure SU(2) gluodynamics simulations are realized with the Compute Abstraction Layer (CAL) of ATI Stream environment using the Metropolis and the heat-bath algorithms, respectively. We present an analysis of both CAL programming model and the efficiency of the corresponding simulation algorithms on GPU. In particular, the significant performance speed-up of these algorithms in comparison with serial execution is observed.

  5. A Monte Carlo algorithm for degenerate plasmas

    SciTech Connect (OSTI)

    Turrell, A.E., E-mail: a.turrell09@imperial.ac.uk; Sherlock, M.; Rose, S.J.

    2013-09-15T23:59:59.000Z

    A procedure for performing Monte Carlo calculations of plasmas with an arbitrary level of degeneracy is outlined. It has possible applications in inertial confinement fusion and astrophysics. Degenerate particles are initialised according to the Fermi–Dirac distribution function, and scattering is via a Pauli blocked binary collision approximation. The algorithm is tested against degenerate electron–ion equilibration, and the degenerate resistivity transport coefficient from unmagnetised first order transport theory. The code is applied to the cold fuel shell and alpha particle equilibration problem of inertial confinement fusion.

  6. Surface-Enhanced Raman Scattering (SERS) for Detection in Immunoassays: applications, fundamentals, and optimization

    SciTech Connect (OSTI)

    Jeremy Daniel Driskell

    2006-08-09T23:59:59.000Z

    Immunoassays have been utilized for the detection of biological analytes for several decades. Many formats and detection strategies have been explored, each having unique advantages and disadvantages. More recently, surface-enhanced Raman scattering (SERS) has been introduced as a readout method for immunoassays, and has shown great potential to meet many key analytical figures of merit. This technology is in its infancy and this dissertation explores the diversity of this method as well as the mechanism responsible for surface enhancement. Approaches to reduce assay times are also investigated. Implementing the knowledge gained from these studies will lead to a more sensitive immunoassay requiring less time than its predecessors. This dissertation is organized into six sections. The first section includes a literature review of the previous work that led to this dissertation. A general overview of the different approaches to immunoassays is given, outlining the strengths and weaknesses of each. Included is a detailed review of binding kinetics, which is central for decreasing assay times. Next, the theoretical underpinnings of SERS is reviewed at its current level of understanding. Past work has argued that surface plasmon resonance (SPR) of the enhancing substrate influences the SERS signal; therefore, the SPR of the extrinsic Raman labels (ERLs) utilized in our SERS-based immunoassay is discussed. Four original research chapters follow the Introduction, each presented as separate manuscripts. Chapter 2 modifies a SERS-based immunoassay previously developed in our group, extending it to the low-level detection of viral pathogens and demonstrating its versatility in terms of analyte type, Chapter 3 investigates the influence of ERL size, material composition, and separation distance between the ERLs and capture substrate on the SERS signal. This chapter links SPR with SERS enhancement factors and is consistent with many of the results from theoretical treatments of SPR and SERS. Chapter 4 introduces a novel method of reducing sample incubation time via capture substrate rotation. Moreover, this work led to a method of virus quantification without the use of standards. Chapter 5 extends the methodology developed in Chapter 4 to both the antigen and ERL labeling step to perform assays with improved analytical performance in less time than can be accomplished in diffusion controlled assays. This dissertation concludes with a general summary and speculates on the future of this exciting approach to carrying out immunoassays.

  7. Laser Treatment of Ag@ZnO Nanorods as Long Life Span SERS Surfaces

    E-Print Network [OSTI]

    Macias-Montero, Manuel; J. Peláez, Ramón; Rico, Victor J.; Saghi, Zineb; Midgley, Paul; Afonso, Carmen N.; González-Elipe, Agustín R.; Borras, Ana

    2015-01-09T23:59:59.000Z

    on semiconductor nanorods or nanowires of Si, Ge or ZnO, have led to significant enhancements in Raman scattering. 18,19 These evidences have prompted the study of composites or heterostructures formed by semiconductors and noble metals to promote higher SERS... of Surface-Enhanced Raman Scattering in ZnO Nanocrystals. J. Raman Spectrosc., 2009, 40, 1072-1077. 18 Li, X. H.; Chen, G. Y.; Yang, L. B.; Jin Z.; Liu, J. H. Multifunctional Au-Coated TiO2 Nanotube Arrays as Recyclable SERS Substrates for Multifold...

  8. Laser Treatment of Ag@ZnO Nanorods as Long-Life-Span SERS Surfaces

    E-Print Network [OSTI]

    Macias-Montero, Manuel; Peláez, Ramón J.; Rico, Victor J.; Saghi, Zineb; Midgley, Paul; Afonso, Carmen N.; González-Elipe, Agustín R.; Borras, Ana

    2015-01-09T23:59:59.000Z

    on semiconductor nanorods or nanowires of Si, Ge or ZnO, have led to significant enhancements in Raman scattering. 18,19 These evidences have prompted the study of composites or heterostructures formed by semiconductors and noble metals to promote higher SERS... of Surface-Enhanced Raman Scattering in ZnO Nanocrystals. J. Raman Spectrosc., 2009, 40, 1072-1077. 18 Li, X. H.; Chen, G. Y.; Yang, L. B.; Jin Z.; Liu, J. H. Multifunctional Au-Coated TiO2 Nanotube Arrays as Recyclable SERS Substrates for Multifold...

  9. Monte Carlo Simulations of the Corrosion of Aluminoborosilicate...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Corrosion of Aluminoborosilicate Glasses. Monte Carlo Simulations of the Corrosion of Aluminoborosilicate Glasses. Abstract: Aluminum is one of the most common components included...

  10. Quantum Monte Carlo methods for nuclear physics

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Carlson, Joseph A.; Gandolfi, Stefano; Pederiva, Francesco; Pieper, Steven C.; Schiavilla, Rocco; Schmidt, K. E,; Wiringa, Robert B.

    2012-01-01T23:59:59.000Z

    Quantum Monte Carlo methods have proved very valuable to study the structure and reactions of light nuclei and nucleonic matter starting from realistic nuclear interactions and currents. These ab-initio calculations reproduce many low-lying states, moments and transitions in light nuclei, and simultaneously predict many properties of light nuclei and neutron matter over a rather wide range of energy and momenta. We review the nuclear interactions and currents, and describe the continuum Quantum Monte Carlo methods used in nuclear physics. These methods are similar to those used in condensed matter and electronic structure but naturally include spin-isospin, tensor, spin-orbit, and three-bodymore »interactions. We present a variety of results including the low-lying spectra of light nuclei, nuclear form factors, and transition matrix elements. We also describe low-energy scattering techniques, studies of the electroweak response of nuclei relevant in electron and neutrino scattering, and the properties of dense nucleonic matter as found in neutron stars. A coherent picture of nuclear structure and dynamics emerges based upon rather simple but realistic interactions and currents.« less

  11. Quantum Monte Carlo methods for nuclear physics

    E-Print Network [OSTI]

    J. Carlson; S. Gandolfi; F. Pederiva; Steven C. Pieper; R. Schiavilla; K. E. Schmidt; R. B. Wiringa

    2015-04-29T23:59:59.000Z

    Quantum Monte Carlo methods have proved very valuable to study the structure and reactions of light nuclei and nucleonic matter starting from realistic nuclear interactions and currents. These ab-initio calculations reproduce many low-lying states, moments and transitions in light nuclei, and simultaneously predict many properties of light nuclei and neutron matter over a rather wide range of energy and momenta. We review the nuclear interactions and currents, and describe the continuum Quantum Monte Carlo methods used in nuclear physics. These methods are similar to those used in condensed matter and electronic structure but naturally include spin-isospin, tensor, spin-orbit, and three-body interactions. We present a variety of results including the low-lying spectra of light nuclei, nuclear form factors, and transition matrix elements. We also describe low-energy scattering techniques, studies of the electroweak response of nuclei relevant in electron and neutrino scattering, and the properties of dense nucleonic matter as found in neutron stars. A coherent picture of nuclear structure and dynamics emerges based upon rather simple but realistic interactions and currents.

  12. Quantum Monte Carlo methods for nuclear physics

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Carlson, Joseph A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gandolfi, Stefano [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pederiva, Francesco [Univ. of Trento (Italy); Pieper, Steven C. [Argonne National Lab. (ANL), Argonne, IL (United States); Schiavilla, Rocco [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Old Dominion Univ., Norfolk, VA (United States); Schmidt, K. E, [Arizona State Univ., Tempe, AZ (United States); Wiringa, Robert B. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2012-01-01T23:59:59.000Z

    Quantum Monte Carlo methods have proved very valuable to study the structure and reactions of light nuclei and nucleonic matter starting from realistic nuclear interactions and currents. These ab-initio calculations reproduce many low-lying states, moments and transitions in light nuclei, and simultaneously predict many properties of light nuclei and neutron matter over a rather wide range of energy and momenta. We review the nuclear interactions and currents, and describe the continuum Quantum Monte Carlo methods used in nuclear physics. These methods are similar to those used in condensed matter and electronic structure but naturally include spin-isospin, tensor, spin-orbit, and three-body interactions. We present a variety of results including the low-lying spectra of light nuclei, nuclear form factors, and transition matrix elements. We also describe low-energy scattering techniques, studies of the electroweak response of nuclei relevant in electron and neutrino scattering, and the properties of dense nucleonic matter as found in neutron stars. A coherent picture of nuclear structure and dynamics emerges based upon rather simple but realistic interactions and currents.

  13. SERS-Coded Gold Nanorods as a Multifunctional Platform for Densely Multiplexed Near-Infrared

    E-Print Network [OSTI]

    Bhatia, Sangeeta

    photothermal tumor heating to ablative temperatures. In the future, the dense near-infrared spectralSERS-Coded Gold Nanorods as a Multifunctional Platform for Densely Multiplexed Near-Infrared Imaging and Photothermal Heating By Geoffrey von Maltzahn, Andrea Centrone, Ji-Ho Park, Renuka Ramanathan

  14. 2003 SITE ENVIRONMENTAL REPORTv The 2003 Site Environmental Report (SER) was

    E-Print Network [OSTI]

    Homes, Christopher C.

    2003 SITE ENVIRONMENTAL REPORTv The 2003 Site Environmental Report (SER) was prepared to inform's) environmental performance for the calendar year. The report was prepared in accordance with Department of Energy in the areas of environmental management, environ- mental impacts, compliance with applicable regu- lations

  15. Quantitative SERS Using the Sequestration of Small Molecules Inside Precise Plasmonic Nanoconstructs

    E-Print Network [OSTI]

    Steiner, Ullrich

    for monitoring analytes such as polyaromatic hydrocarbons (PAHs). PAHs are a class of pollutants that need of hydrophobic molecules in general has proved difficult.15 SERS analyses of PAHs have been carried out using, especially water-insoluble analytes, in various environmental matrices. Using a host molecule with a specific

  16. Landscape Architecture SER Page 1 9/29/2008 SELF EVALUATION REPORT

    E-Print Network [OSTI]

    Farritor, Shane

    Landscape Architecture SER Page 1 9/29/2008 SELF EVALUATION REPORT For a FIRST-PROFESSIONAL PROGRAM in LANDSCAPE ARCHITECTURE (5-year BLA) in the College of Architecture At The University of Nebraska-Lincoln Submitted to Landscape Architectural Accreditation Board American Society of Landscape Architects 636 Eye

  17. Adjoint electron-photon transport Monte Carlo calculations with ITS

    SciTech Connect (OSTI)

    Lorence, L.J.; Kensek, R.P.; Halbleib, J.A. [Sandia National Labs., Albuquerque, NM (United States); Morel, J.E. [Los Alamos National Lab., NM (United States)

    1995-02-01T23:59:59.000Z

    A general adjoint coupled electron-photon Monte Carlo code for solving the Boltzmann-Fokker-Planck equation has recently been created. It is a modified version of ITS 3.0, a coupled electronphoton Monte Carlo code that has world-wide distribution. The applicability of the new code to radiation-interaction problems of the type found in space environments is demonstrated.

  18. STORM in Monte Carlo reactor physics calculations KAUR TUTTELBERG

    E-Print Network [OSTI]

    Haviland, David

    STORM in Monte Carlo reactor physics calculations KAUR TUTTELBERG Master of Science Thesis Carlo reactor physics criticality calculations. This is achieved by optimising the number of neutron for more efficient Monte Carlo reactor physics calculations, giving results with errors that can

  19. Special Topics Monte Carlo Methods in Science, Engineering and Business

    E-Print Network [OSTI]

    Shepp, Larry

    SYLLABUS Special Topics ­ Monte Carlo Methods in Science, Engineering and Business Fall, 2007 in Probability and Statistics 3. Simple Simulation Methods 4. Sequential Monte Carlo Methods 5. Markov Chain up shortly Prerequisite: First Graduate Level Mathematical Statistics Course It should be emphasized

  20. New Monte Carlo schemes for simulating diffusions in discontinuous media

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    New Monte Carlo schemes for simulating diffusions in discontinuous media Antoine Lejay1,2,3,4,5 Sylvain Maire6,7 April 28, 2012 Abstract We introduce new Monte Carlo simulation schemes for diffusions in a dis- continuous media divided in subdomains with piecewise constant diffusivity. These schemes

  1. New Monte Carlo schemes for simulating diffusions in discontinuous media

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    New Monte Carlo schemes for simulating diffusions in discontinuous media Antoine Lejay1,2,3,4,5 Sylvain Maire6,7 December 13, 2012 Abstract We introduce new Monte Carlo simulation schemes for diffusions in a dis- continuous media divided in subdomains with piecewise constant diffusivity. These schemes

  2. Monte Carlo Evaluation of Resampling-Based Hypothesis Tests

    E-Print Network [OSTI]

    Boos, Dennis

    of rejections. At each alternative this Monte Carlo estimate will be unbiased for the true power function of the function ( ), where (A) = 1 if A is true and = 0 otherwise. The connection to measurement error methods 1998 Abstract Monte Carlo estimation of the power of tests that require resampling can be very com

  3. RADIATIVE HEAT TRANSFER WITH QUASI-MONTE CARLO METHODS

    E-Print Network [OSTI]

    RADIATIVE HEAT TRANSFER WITH QUASI-MONTE CARLO METHODS A. Kersch1 W. Moroko2 A. Schuster1 1Siemens of Quasi-Monte Carlo to this problem. 1.1 Radiative Heat Transfer Reactors In the manufacturing of the problems which can be solved by such a simulation is high accuracy modeling of the radiative heat transfer

  4. Quantum Ice : a quantum Monte Carlo study

    E-Print Network [OSTI]

    Nic Shannon; Olga Sikora; Frank Pollmann; Karlo Penc; Peter Fulde

    2011-12-13T23:59:59.000Z

    Ice states, in which frustrated interactions lead to a macroscopic ground-state degeneracy, occur in water ice, in problems of frustrated charge order on the pyrochlore lattice, and in the family of rare-earth magnets collectively known as spin ice. Of particular interest at the moment are "quantum spin ice" materials, where large quantum fluctuations may permit tunnelling between a macroscopic number of different classical ground states. Here we use zero-temperature quantum Monte Carlo simulations to show how such tunnelling can lift the degeneracy of a spin or charge ice, stabilising a unique "quantum ice" ground state --- a quantum liquid with excitations described by the Maxwell action of 3+1-dimensional quantum electrodynamics. We further identify a competing ordered "squiggle" state, and show how both squiggle and quantum ice states might be distinguished in neutron scattering experiments on a spin ice material.

  5. Correlations in the Monte Carlo Glauber model

    E-Print Network [OSTI]

    Jean-Paul Blaizot; Wojciech Broniowski; Jean-Yves Ollitrault

    2014-09-12T23:59:59.000Z

    Event-by-event fluctuations of observables are often modeled using the Monte Carlo Glauber model, in which the energy is initially deposited in sources associated with wounded nucleons. In this paper, we analyze in detail the correlations between these sources in proton-nucleus and nucleus-nucleus collisions. There are correlations arising from nucleon-nucleon correlations within each nucleus, and correlations due to the collision mechanism, which we dub twin correlations. We investigate this new phenomenon in detail. At the RHIC and LHC energies, correlations are found to have modest effects on size and eccentricity fluctuations, such that the Glauber model produces to a good approximation a collection of independent sources.

  6. Parametric Learning and Monte Carlo Optimization

    E-Print Network [OSTI]

    Wolpert, David H

    2007-01-01T23:59:59.000Z

    This paper uncovers and explores the close relationship between Monte Carlo Optimization of a parametrized integral (MCO), Parametric machine-Learning (PL), and `blackbox' or `oracle'-based optimization (BO). We make four contributions. First, we prove that MCO is mathematically identical to a broad class of PL problems. This identity potentially provides a new application domain for all broadly applicable PL techniques: MCO. Second, we introduce immediate sampling, a new version of the Probability Collectives (PC) algorithm for blackbox optimization. Immediate sampling transforms the original BO problem into an MCO problem. Accordingly, by combining these first two contributions, we can apply all PL techniques to BO. In our third contribution we validate this way of improving BO by demonstrating that cross-validation and bagging improve immediate sampling. Finally, conventional MC and MCO procedures ignore the relationship between the sample point locations and the associated values of the integrand; only th...

  7. A hybrid Monte Carlo and response matrix Monte Carlo method in criticality calculation

    SciTech Connect (OSTI)

    Li, Z.; Wang, K. [Dept. of Engineering Physics, Tsinghua Univ., Beijing, 100084 (China)

    2012-07-01T23:59:59.000Z

    Full core calculations are very useful and important in reactor physics analysis, especially in computing the full core power distributions, optimizing the refueling strategies and analyzing the depletion of fuels. To reduce the computing time and accelerate the convergence, a method named Response Matrix Monte Carlo (RMMC) method based on analog Monte Carlo simulation was used to calculate the fixed source neutron transport problems in repeated structures. To make more accurate calculations, we put forward the RMMC method based on non-analog Monte Carlo simulation and investigate the way to use RMMC method in criticality calculations. Then a new hybrid RMMC and MC (RMMC+MC) method is put forward to solve the criticality problems with combined repeated and flexible geometries. This new RMMC+MC method, having the advantages of both MC method and RMMC method, can not only increase the efficiency of calculations, also simulate more complex geometries rather than repeated structures. Several 1-D numerical problems are constructed to test the new RMMC and RMMC+MC method. The results show that RMMC method and RMMC+MC method can efficiently reduce the computing time and variations in the calculations. Finally, the future research directions are mentioned and discussed at the end of this paper to make RMMC method and RMMC+MC method more powerful. (authors)

  8. Multi-line Doppler imaging of MR Ser in high-state

    E-Print Network [OSTI]

    Marcos Diaz; Deonisio Cieslinski

    2008-11-05T23:59:59.000Z

    Doppler images in Balmer, HeI, HeII and CII lines, and simultaneous I-band photometry of the polar MR Ser are presented and analyzed. The Balmer and Helium Doppler tomograms of this bright polar at high mass transfer state show the emission from the accretion flow and the heated surface of the companion star. As a result of a comparison between the Doppler tomograms the ionization structure of the flow could be constrained. The highest ionization region was found in the vicinity of the magnetospheric radius. Photoionization modeling of the accretion column indicates that the Balmer and Helium emission line production in this system can be explained by the central soft Xray illumination only. The orbital ephemeris of MR Ser has been revised.

  9. Fabrication of Nano-Pattern Libraries and their Applications in Mode-Selective SERS

    E-Print Network [OSTI]

    Zhao, Zhi

    2013-06-21T23:59:59.000Z

    . To the best of our knowledge, this is the first example of a surface morphology dependent Raman selection. In addition, this mode-selective SERS is extremely sensitive to the orientations of molecular vibrations and should be ideal to examine structures... organosulfur solution, an uniform monolayer was spontaneously chemisorbed on the surface of the gold, producing a self-assembled monolayer.85 Such coatings are promising to be used in corrosion inhibition,86 lubrication,87 and organic sensors.88 During...

  10. Iterative acceleration methods for Monte Carlo and deterministic criticality calculations

    SciTech Connect (OSTI)

    Urbatsch, T.J.

    1995-11-01T23:59:59.000Z

    If you have ever given up on a nuclear criticality calculation and terminated it because it took so long to converge, you might find this thesis of interest. The author develops three methods for improving the fission source convergence in nuclear criticality calculations for physical systems with high dominance ratios for which convergence is slow. The Fission Matrix Acceleration Method and the Fission Diffusion Synthetic Acceleration (FDSA) Method are acceleration methods that speed fission source convergence for both Monte Carlo and deterministic methods. The third method is a hybrid Monte Carlo method that also converges for difficult problems where the unaccelerated Monte Carlo method fails. The author tested the feasibility of all three methods in a test bed consisting of idealized problems. He has successfully accelerated fission source convergence in both deterministic and Monte Carlo criticality calculations. By filtering statistical noise, he has incorporated deterministic attributes into the Monte Carlo calculations in order to speed their source convergence. He has used both the fission matrix and a diffusion approximation to perform unbiased accelerations. The Fission Matrix Acceleration method has been implemented in the production code MCNP and successfully applied to a real problem. When the unaccelerated calculations are unable to converge to the correct solution, they cannot be accelerated in an unbiased fashion. A Hybrid Monte Carlo method weds Monte Carlo and a modified diffusion calculation to overcome these deficiencies. The Hybrid method additionally possesses reduced statistical errors.

  11. El ser humano sigue evolucionando Investigadores afirman que, pese a la tecnologa y la monogamia, la seleccin

    E-Print Network [OSTI]

    Lummaa, Virpi

    CIENCIA CIENCIA El ser humano sigue evolucionando Investigadores afirman que, pese a la tecnología/05/2012http://www.abc.es/20120430/ciencia/abci-humano-sigue-evolucionando-2012043019... #12;El aspecto que tendrá el ser humano en el futuro es una de esas preguntas que parecen de ciencia ficción y para la que

  12. Sequential Monte Carlo Methods for Protein Folding

    E-Print Network [OSTI]

    Peter Grassberger

    2004-08-26T23:59:59.000Z

    We describe a class of growth algorithms for finding low energy states of heteropolymers. These polymers form toy models for proteins, and the hope is that similar methods will ultimately be useful for finding native states of real proteins from heuristic or a priori determined force fields. These algorithms share with standard Markov chain Monte Carlo methods that they generate Gibbs-Boltzmann distributions, but they are not based on the strategy that this distribution is obtained as stationary state of a suitably constructed Markov chain. Rather, they are based on growing the polymer by successively adding individual particles, guiding the growth towards configurations with lower energies, and using "population control" to eliminate bad configurations and increase the number of "good ones". This is not done via a breadth-first implementation as in genetic algorithms, but depth-first via recursive backtracking. As seen from various benchmark tests, the resulting algorithms are extremely efficient for lattice models, and are still competitive with other methods for simple off-lattice models.

  13. Super Rat Poison Man

    E-Print Network [OSTI]

    Hacker, Randi; Tsutsui, William

    2007-04-04T23:59:59.000Z

    Bob Square Tie. But Zheng Xiaoyu, the deposed head of China's State Food and Drug Administration begs to be excused. A rat poison manufacturer here in China applied for permission to name some of its products after him, partly because he's corrupt...

  14. Variance Reduction Techniques for Implicit Monte Carlo Simulations

    E-Print Network [OSTI]

    Landman, Jacob Taylor

    2013-09-19T23:59:59.000Z

    The Implicit Monte Carlo (IMC) method is widely used for simulating thermal radiative transfer and solving the radiation transport equation. During an IMC run a grid network is constructed and particles are sourced into the problem to simulate...

  15. An Analysis Tool for Flight Dynamics Monte Carlo Simulations

    E-Print Network [OSTI]

    Restrepo, Carolina 1982-

    2011-05-20T23:59:59.000Z

    and analysis work to understand vehicle operating limits and identify circumstances that lead to mission failure. A Monte Carlo simulation approach that varies a wide range of physical parameters is typically used to generate thousands of test cases...

  16. Enhancements in Continuous-Energy Monte Carlo Capabilities in SCALE

    SciTech Connect (OSTI)

    Bekar, Kursat B [ORNL] [ORNL; Celik, Cihangir [ORNL] [ORNL; Wiarda, Dorothea [ORNL] [ORNL; Peplow, Douglas E. [ORNL] [ORNL; Rearden, Bradley T [ORNL] [ORNL; Dunn, Michael E [ORNL] [ORNL

    2013-01-01T23:59:59.000Z

    Monte Carlo tools in SCALE are commonly used in criticality safety calculations as well as sensitivity and uncertainty analysis, depletion, and criticality alarm system analyses. Recent improvements in the continuous-energy data generated by the AMPX code system and significant advancements in the continuous-energy treatment in the KENO Monte Carlo eigenvalue codes facilitate the use of SCALE Monte Carlo codes to model geometrically complex systems with enhanced solution fidelity. The addition of continuous-energy treatment to the SCALE Monaco code, which can be used with automatic variance reduction in the hybrid MAVRIC sequence, provides significant enhancements, especially for criticality alarm system modeling. This paper describes some of the advancements in continuous-energy Monte Carlo codes within the SCALE code system.

  17. Variance Reduction Techniques for Implicit Monte Carlo Simulations 

    E-Print Network [OSTI]

    Landman, Jacob Taylor

    2013-09-19T23:59:59.000Z

    The Implicit Monte Carlo (IMC) method is widely used for simulating thermal radiative transfer and solving the radiation transport equation. During an IMC run a grid network is constructed and particles are sourced into the problem to simulate...

  18. Shift: A Massively Parallel Monte Carlo Radiation Transport Package

    SciTech Connect (OSTI)

    Pandya, Tara M [ORNL; Johnson, Seth R [ORNL; Davidson, Gregory G [ORNL; Evans, Thomas M [ORNL; Hamilton, Steven P [ORNL

    2015-01-01T23:59:59.000Z

    This paper discusses the massively-parallel Monte Carlo radiation transport package, Shift, de- veloped at Oak Ridge National Laboratory. It reviews the capabilities, implementation, and parallel performance of this code package. Scaling results demonstrate very good strong and weak scaling behavior of the implemented algorithms. Benchmark results from various reactor problems show that Shift results compare well to other contemporary Monte Carlo codes and experimental results.

  19. Monte Carlos of the new generation: status and progress

    SciTech Connect (OSTI)

    Frixione, Stefano [INFN, Sezione di Genova, Via Dodecaneso 33, 16146 Genova (Italy)

    2005-03-22T23:59:59.000Z

    Standard parton shower monte carlos are designed to give reliable descriptions of low-pT physics. In the very high-energy regime of modern colliders, this is may lead to largely incorrect predictions of the basic reaction processes. This motivated the recent theoretical efforts aimed at improving monte carlos through the inclusion of matrix elements computed beyond the leading order in QCD. I briefly review the progress made, and discuss bottom production at the Tevatron.

  20. Implications of Monte Carlo Statistical Errors in Criticality Safety Assessments

    SciTech Connect (OSTI)

    Pevey, Ronald E.

    2005-09-15T23:59:59.000Z

    Most criticality safety calculations are performed using Monte Carlo techniques because of Monte Carlo's ability to handle complex three-dimensional geometries. For Monte Carlo calculations, the more histories sampled, the lower the standard deviation of the resulting estimates. The common intuition is, therefore, that the more histories, the better; as a result, analysts tend to run Monte Carlo analyses as long as possible (or at least to a minimum acceptable uncertainty). For Monte Carlo criticality safety analyses, however, the optimization situation is complicated by the fact that procedures usually require that an extra margin of safety be added because of the statistical uncertainty of the Monte Carlo calculations. This additional safety margin affects the impact of the choice of the calculational standard deviation, both on production and on safety. This paper shows that, under the assumptions of normally distributed benchmarking calculational errors and exact compliance with the upper subcritical limit (USL), the standard deviation that optimizes production is zero, but there is a non-zero value of the calculational standard deviation that minimizes the risk of inadvertently labeling a supercritical configuration as subcritical. Furthermore, this value is shown to be a simple function of the typical benchmarking step outcomes--the bias, the standard deviation of the bias, the upper subcritical limit, and the number of standard deviations added to calculated k-effectives before comparison to the USL.

  1. Neutron beam irradiation study of workload dependence of SER in a microprocessor

    SciTech Connect (OSTI)

    Michalak, Sarah E [Los Alamos National Laboratory; Graves, Todd L [Los Alamos National Laboratory; Hong, Ted [STANFORD; Ackaret, Jerry [IBM; Sonny, Rao [IBM; Subhasish, Mitra [STANFORD; Pia, Sanda [IBM

    2009-01-01T23:59:59.000Z

    It is known that workloads are an important factor in soft error rates (SER), but it is proving difficult to find differentiating workloads for microprocessors. We have performed neutron beam irradiation studies of a commercial microprocessor under a wide variety of workload conditions from idle, performing no operations, to very busy workloads resembling real HPC, graphics, and business applications. There is evidence that the mean times to first indication of failure, MTFIF defined in Section II, may be different for some of the applications.

  2. Lattice Monte Carlo Simulations of Polymer Melts

    E-Print Network [OSTI]

    Hsiao-Ping Hsu

    2015-03-03T23:59:59.000Z

    We use Monte Carlo simulations to study polymer melts consisting of fully flexible and moderately stiff chains in the bond fluctuation model at a volume fraction $0.5$. In order to reduce the local density fluctuations, we test a pre-packing process for the preparation of the initial configurations of the polymer melts, before the excluded volume interaction is switched on completely. This process leads to a significantly faster decrease of the number of overlapping monomers on the lattice. This is useful for simulating very large systems, where the statistical properties of the model with a marginally incomplete elimination of excluded volume violations are the same as those of the model with strictly excluded volume. We find that the internal mean square end-to-end distance for moderately stiff chains in a melt can be very well described by a freely rotating chain model with a precise estimate of the bond-bond orientational correlation between two successive bond vectors in equilibrium. The plot of the probability distributions of the reduced end-to-end distance of chains of different stiffness also shows that the data collapse is excellent and described very well by the Gaussian distribution for ideal chains. However, while our results confirm the systematic deviations between Gaussian statistics for the chain structure factor $S_c(q)$ [minimum in the Kratky-plot] found by Wittmer et al.~\\{EPL {\\bf 77} 56003 (2007).\\} for fully flexible chains in a melt, we show that for the available chain length these deviations are no longer visible, when the chain stiffness is included. The mean square bond length and the compressibility estimated from collective structure factors depend slightly on the stiffness of the chains.

  3. Minibeam radiation therapy for the management of osteosarcomas: A Monte Carlo study

    SciTech Connect (OSTI)

    Martínez-Rovira, I.; Prezado, Y., E-mail: prezado@gmail.com [Laboratoire d’Imagerie et Modélisation en Neurobiologie et Cancérologie (IMNC), Centre National de la Recherche Scientifique (CNRS), Campus universitaire, Bât. 440, 1er étage, 15 rue Georges Clemenceau, 91406 Orsay cedex (France)

    2014-06-15T23:59:59.000Z

    Purpose: Minibeam radiation therapy (MBRT) exploits the well-established tissue-sparing effect provided by the combination of submillimetric field sizes and a spatial fractionation of the dose. The aim of this work is to evaluate the feasibility and potential therapeutic gain of MBRT, in comparison with conventional radiotherapy, for osteosarcoma treatments. Methods: Monte Carlo simulations (PENELOPE/PENEASY code) were used as a method to study the dose distributions resulting from MBRT irradiations of a rat femur and a realistic human femur phantoms. As a figure of merit, peak and valley doses and peak-to-valley dose ratios (PVDR) were assessed. Conversion of absorbed dose to normalized total dose (NTD) was performed in the human case. Several field sizes and irradiation geometries were evaluated. Results: It is feasible to deliver a uniform dose distribution in the target while the healthy tissue benefits from a spatial fractionation of the dose. Very high PVDR values (?20) were achieved in the entrance beam path in the rat case. PVDR values ranged from 2 to 9 in the human phantom. NTD{sub 2.0} of 87 Gy might be reached in the tumor in the human femur while the healthy tissues might receive valley NTD{sub 2.0} lower than 20 Gy. The doses in the tumor and healthy tissues might be significantly higher and lower than the ones commonly delivered used in conventional radiotherapy. Conclusions: The obtained dose distributions indicate that a gain in normal tissue sparing might be expected. This would allow the use of higher (and potentially curative) doses in the tumor. Biological experiments are warranted.

  4. Esta informacin puede ser usada en parte o en su integridad sin necesidad de citar fuentes 1 Ciencia y Tecnologa

    E-Print Network [OSTI]

    Ministerio de Ciencia y Tecnología Intervención del Sr. Ministro JOSEP PIQUÉ en el acto de apertura de la información puede ser usada en parte o en su integridad sin necesidad de citar fuentes 2 Ministerio de Ciencia

  5. Quantum Monte Carlo Calculations of Light Nuclei Using Chiral Potentials

    E-Print Network [OSTI]

    J. E. Lynn; J. Carlson; E. Epelbaum; S. Gandolfi; A. Gezerlis; A. Schwenk

    2014-11-09T23:59:59.000Z

    We present the first Green's function Monte Carlo calculations of light nuclei with nuclear interactions derived from chiral effective field theory up to next-to-next-to-leading order. Up to this order, the interactions can be constructed in a local form and are therefore amenable to quantum Monte Carlo calculations. We demonstrate a systematic improvement with each order for the binding energies of $A=3$ and $A=4$ systems. We also carry out the first few-body tests to study perturbative expansions of chiral potentials at different orders, finding that higher-order corrections are more perturbative for softer interactions. Our results confirm the necessity of a three-body force for correct reproduction of experimental binding energies and radii, and pave the way for studying few- and many-nucleon systems using quantum Monte Carlo methods with chiral interactions.

  6. A Multivariate Time Series Method for Monte Carlo Reactor Analysis

    SciTech Connect (OSTI)

    Taro Ueki

    2008-08-14T23:59:59.000Z

    A robust multivariate time series method has been established for the Monte Carlo calculation of neutron multiplication problems. The method is termed Coarse Mesh Projection Method (CMPM) and can be implemented using the coarse statistical bins for acquisition of nuclear fission source data. A novel aspect of CMPM is the combination of the general technical principle of projection pursuit in the signal processing discipline and the neutron multiplication eigenvalue problem in the nuclear engineering discipline. CMPM enables reactor physicists to accurately evaluate major eigenvalue separations of nuclear reactors with continuous energy Monte Carlo calculation. CMPM was incorporated in the MCNP Monte Carlo particle transport code of Los Alamos National Laboratory. The great advantage of CMPM over the traditional Fission Matrix method is demonstrated for the three space-dimensional modeling of the initial core of a pressurized water reactor.

  7. The Monte Carlo method in quantum field theory

    E-Print Network [OSTI]

    Colin Morningstar

    2007-02-20T23:59:59.000Z

    This series of six lectures is an introduction to using the Monte Carlo method to carry out nonperturbative studies in quantum field theories. Path integrals in quantum field theory are reviewed, and their evaluation by the Monte Carlo method with Markov-chain based importance sampling is presented. Properties of Markov chains are discussed in detail and several proofs are presented, culminating in the fundamental limit theorem for irreducible Markov chains. The example of a real scalar field theory is used to illustrate the Metropolis-Hastings method and to demonstrate the effectiveness of an action-preserving (microcanonical) local updating algorithm in reducing autocorrelations. The goal of these lectures is to provide the beginner with the basic skills needed to start carrying out Monte Carlo studies in quantum field theories, as well as to present the underlying theoretical foundations of the method.

  8. Application of surface-enhanced Raman scattering (SERS) for the identification of anthraquinone dyes used in works of art

    SciTech Connect (OSTI)

    Chen, Kui [ORNL; Leona, Marco [ORNL; Yan, Fei [ORNL; Wabuyele, Musundi B [ORNL; Vo Dinh, Tuan [ORNL

    2006-04-01T23:59:59.000Z

    Surface-enhanced Raman scattering (SERS) was investigated for applications in the analysis of anthraquinone dyes used in works of art. Two SERS procedures were developed and evaluated with three frequently used anthraquinone dyes, alizarin, carminic acid and lac dye. The first procedure involves coating a layer of silver nanoparticles directly on pieces of filter paper stained with the dyes of interest by thermal evaporation to induce SERS effect. In the second procedure, a SERS-active Ag-Al{sub 2}O{sub 3} substrate was prepared by spin-coating an alumina-nanoparticle layer onto a glass slide to provide the nanostructure of the substrate, followed by thermally evaporating a layer of silver nanoparticles on top of the alumina layer. Aliquots of dye solutions were delivered onto this substrate to be analyzed. Intense SERS spectra characteristic of alizarin, carminic acid and lac dye were obtained using both SERS procedures. The effects of two parameters, the concentration of the alumina suspension and the thickness of the silver nanoparticle layer on the performance of the Ag-Al{sub 2}O{sub 3} substrate were examined with alizarin as the model compound. Comparative studies were conducted between the Ag-Al{sub 2}O{sub 3} substrate and the SERS substrate prepared using Tollens reaction. The Ag-Al{sub 2}O{sub 3} substrate was shown to offer larger enhancement and improved reproducibility than the Tollens substrates. Finally, the potential applicability of the Ag-Al{sub 2}O{sub 3} substrate for the analysis of real artifact objects was illustrated by the identification of alizarin extracted from a small piece of textile dyed using traditional methods and materials. The limit of detection for alizarin was estimated to be 7 x 10{sup -15} g from tests performed on solutions of known concentration.

  9. Application of Dynamic Monte Carlo Technique in Proton Beam Radiotherapy using Geant4 Simulation Toolkit

    E-Print Network [OSTI]

    Guan, Fada 1982-

    2012-04-27T23:59:59.000Z

    Monte Carlo method has been successfully applied in simulating the particles transport problems. Most of the Monte Carlo simulation tools are static and they can only be used to perform the static simulations for the problems with fixed physics...

  10. Parallel algorithms for Monte Carlo particle transport simulation on exascale computing architectures

    E-Print Network [OSTI]

    Romano, Paul K. (Paul Kollath)

    2013-01-01T23:59:59.000Z

    Monte Carlo particle transport methods are being considered as a viable option for high-fidelity simulation of nuclear reactors. While Monte Carlo methods offer several potential advantages over deterministic methods, there ...

  11. Thermoelectric transport perpendicular to thin-film heterostructures calculated using the Monte Carlo technique

    E-Print Network [OSTI]

    Thermoelectric transport perpendicular to thin-film heterostructures calculated using the Monte The Monte Carlo technique is used to calculate electrical as well as thermoelectric transport properties ballistic thermionic transport and fully diffusive thermoelectric transport is also described. DOI: 10

  12. Monte Carlo Filtering on Lie Groups Alessandro Chiuso 1 and Stefano Soatto 2

    E-Print Network [OSTI]

    Soatto, Stefano

    Monte Carlo Filtering on Lie Groups Alessandro Chiuso 1 and Stefano Soatto 2 Abstract We propose to be consistent with the updated conditional distribution. The algorithm proposed, like other Monte Carlo methods

  13. The theoretical development of a new high speed solution for Monte Carlo radiation transport computations 

    E-Print Network [OSTI]

    Pasciak, Alexander Samuel

    2007-04-25T23:59:59.000Z

    Advancements in parallel and cluster computing have made many complex Monte Carlo simulations possible in the past several years. Unfortunately, cluster computers are large, expensive, and still not fast enough to make the Monte Carlo technique...

  14. Application of Dynamic Monte Carlo Technique in Proton Beam Radiotherapy using Geant4 Simulation Toolkit 

    E-Print Network [OSTI]

    Guan, Fada 1982-

    2012-04-27T23:59:59.000Z

    Monte Carlo method has been successfully applied in simulating the particles transport problems. Most of the Monte Carlo simulation tools are static and they can only be used to perform the static simulations for the problems with fixed physics...

  15. Calculating coherent pair production with Monte Carlo methods

    SciTech Connect (OSTI)

    Bottcher, C.; Strayer, M.R.

    1989-01-01T23:59:59.000Z

    We discuss calculations of the coherent electromagnetic pair production in ultra-relativistic hadron collisions. This type of production, in lowest order, is obtained from three diagrams which contain two virtual photons. We discuss simple Monte Carlo methods for evaluating these classes of diagrams without recourse to involved algebraic reduction schemes. 19 refs., 11 figs.

  16. The Rhenish stoneware from the Monte Cristi shipwreck, Dominican Republic

    E-Print Network [OSTI]

    Lessmann, Anne Wood

    1997-01-01T23:59:59.000Z

    Discovered in 1966 off the north coast of the Dominican Republic, the Monte Cristi shipwreck represents the remains of an English-built ship carrying a Dutch cargo that sank in Spanish waters during the mid-17th century. Despite heavy salvage...

  17. Multiple Overlapping Tiles for Contextual Monte Carlo Tree Search

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    generation of libraries for linear transforms [4] or active learning [8]. The use of Monte Carlo simulations is to group simulations where two particular actions have been selected by the same player. Then, we learn simulations in the MCTS algorithm has been proposed. We first present reinforcement learning, the principle

  18. ENVIRONMENTAL MODELING: 1 APPLICATIONS: MONTE CARLO SENSITIVITY SIMULATIONS

    E-Print Network [OSTI]

    Dimov, Ivan

    SIMULATIONS TO THE PROBLEM OF AIR POLLUTION TRANSPORT 3 1.1 The Danish Eulerian Model #12;Chapter 1 APPLICATIONS: MONTE CARLO SENSITIVITY SIMULATIONS TO THE PROBLEM OF AIR POLLUTION of pollutants in a real-live scenario of air-pollution transport over Europe. First, the developed technique

  19. Monte Carlo: in the beginning and some great expectations

    SciTech Connect (OSTI)

    Metropolis, N.

    1985-01-01T23:59:59.000Z

    The central theme will be on the historical setting and origins of the Monte Carlo Method. The scene was post-war Los Alamos Scientific Laboratory. There was an inevitability about the Monte Carlo Event: the ENIAC had recently enjoyed its meteoric rise (on a classified Los Alamos problem); Stan Ulam had returned to Los Alamos; John von Neumann was a frequent visitor. Techniques, algorithms, and applications developed rapidly at Los Alamos. Soon, the fascination of the Method reached wider horizons. The first paper was submitted for publication in the spring of 1949. In the summer of 1949, the first open conference was held at the University of California at Los Angeles. Of some interst perhaps is an account of Fermi's earlier, independent application in neutron moderation studies while at the University of Rome. The quantum leap expected with the advent of massively parallel processors will provide stimuli for very ambitious applications of the Monte Carlo Method in disciplines ranging from field theories to cosmology, including more realistic models in the neurosciences. A structure of multi-instruction sets for parallel processing is ideally suited for the Monte Carlo approach. One may even hope for a modest hardening of the soft sciences.

  20. Nonlocal Monte Carlo algorithms for statistical physics applications

    E-Print Network [OSTI]

    Janke, Wolfhard

    magnets to polymers or proteins, to mention only a few classical problems. Quantum statistical problems different theoretical approaches such as field theory or series expansions, and, of course, with experimentsNonlocal Monte Carlo algorithms for statistical physics applications Wolfhard Janke1 Institut fu

  1. Auxiliary field Monte Carlo for charged particles A. C. Maggs

    E-Print Network [OSTI]

    Maggs, Anthony

    ~ . This is the wrong statistical weight for particles interacting via Coulomb's law. While evaluation of the energy; accepted 20 November 2003 This article describes Monte Carlo algorithms for charged systems using.1063/1.1642587 I. INTRODUCTION Fast methods for calculating Coulomb interactions are of the greatest importance

  2. Selection Criteria Based on Monte Carlo Simulation and Cross Validation

    E-Print Network [OSTI]

    Shang, Junfeng

    Shang Bowling Green State University, USA Abstract In the mixed modeling framework, Monte Carlo State University, Bowling Green, OH 43403. #12;1 Introduction The Akaike (1973, 1974) information-mail: jshang@bgnet.bgsu.edu. Department of Mathematics and Statistics, 450 Math Science Building, Bowling Green

  3. Evolutionary Monte Carlo for protein folding simulations Faming Lianga)

    E-Print Network [OSTI]

    Liang, Faming

    Evolutionary Monte Carlo for protein folding simulations Faming Lianga) Department of Statistics to simulations of protein folding on simple lattice models, and to finding the ground state of a protein. In all structures in protein folding. The numerical results show that it is drastically superior to other methods

  4. Thermal Properties of Supercritical Carbon Dioxide by Monte Carlo Simulations

    E-Print Network [OSTI]

    Lisal, Martin

    Thermal Properties of Supercritical Carbon Dioxide by Monte Carlo Simulations C.M. COLINAa,b, *, C and speed of sound for carbon dioxide (CO2) in the supercritical region, using the fluctuation method based: Fluctuations; Carbon dioxide; 2CLJQ; Joule­Thomson coefficient; Speed of sound INTRODUCTION Simulation methods

  5. Quantum Monte Carlo calculations of symmetric nuclear matter

    E-Print Network [OSTI]

    Stefano Gandolfi; Francesco Pederiva; Stefano Fantoni; Kevin E. Schmidt

    2007-04-13T23:59:59.000Z

    We present an accurate numerical study of the equation of state of nuclear matter based on realistic nucleon--nucleon interactions by means of Auxiliary Field Diffusion Monte Carlo (AFDMC) calculations. The AFDMC method samples the spin and isospin degrees of freedom allowing for quantum simulations of large nucleonic systems and can provide quantitative understanding of problems in nuclear structure and astrophysics.

  6. Hybrid Probabilistic Roadmap and Monte Carlo Methods for Biomolecule Conformational Changes

    E-Print Network [OSTI]

    Han, Li

    1 Hybrid Probabilistic Roadmap and Monte Carlo Methods for Biomolecule Conformational Changes Li Han 1 Keywords: Conformation space, conformational changes, Monte Carlo, probabilistic roadmaps. 1. In this work, we have developed a hybrid Probabilistic Roadmap and Monte Carlo planner for biomolecule

  7. Monte Carlo Methods for Uncertainty Quantification Mathematical Institute, University of Oxford

    E-Print Network [OSTI]

    Giles, Mike

    Lecture 1: Introduction and Monte Carlo basics some model applications random number generation Monte force being outside some specified range Note: if we turn this into a full finite element analysis on the boundary. Mike Giles (Oxford) Monte Carlo methods October 25, 2013 7 / 28 #12;Application 3 In modelling

  8. Welcome to Union County Extension. The ser-vice offered to the citizens of Union County is a

    E-Print Network [OSTI]

    Jawitz, James W.

    Education: Pesticide education continues to be a Tri-County initiative through Bradford, Baker and UnionWelcome to Union County Extension. The ser- vice offered to the citizens of Union County is a partnership between Union County Board of County Commissioners and the University of Florida/IFAS. The mission

  9. Ordered Array of Gold Semishells on TiO2 Spheres: An Ultrasensitive and Recyclable SERS Substrate

    E-Print Network [OSTI]

    Xiong, Qihua

    more semiconductor-noble metal nanocomposites were fabricated, such as TiO2/Ag, ZnO/Ag, ZnO/Au, TiO2/AuOrdered Array of Gold Semishells on TiO2 Spheres: An Ultrasensitive and Recyclable SERS Substrate, 639798, Singapore ABSTRACT: Ordered array of Au semishells on TiO2 spheres with controlled size

  10. Efficient, automated Monte Carlo methods for radiation transport

    SciTech Connect (OSTI)

    Kong Rong; Ambrose, Martin [Claremont Graduate University, 150 E. 10th Street, Claremont, CA 91711 (United States); Spanier, Jerome [Claremont Graduate University, 150 E. 10th Street, Claremont, CA 91711 (United States); Beckman Laser Institute and Medical Clinic, University of California, 1002 Health Science Road E., Irvine, CA 92612 (United States)], E-mail: jspanier@uci.edu

    2008-11-20T23:59:59.000Z

    Monte Carlo simulations provide an indispensible model for solving radiative transport problems, but their slow convergence inhibits their use as an everyday computational tool. In this paper, we present two new ideas for accelerating the convergence of Monte Carlo algorithms based upon an efficient algorithm that couples simulations of forward and adjoint transport equations. Forward random walks are first processed in stages, each using a fixed sample size, and information from stage k is used to alter the sampling and weighting procedure in stage k+1. This produces rapid geometric convergence and accounts for dramatic gains in the efficiency of the forward computation. In case still greater accuracy is required in the forward solution, information from an adjoint simulation can be added to extend the geometric learning of the forward solution. The resulting new approach should find widespread use when fast, accurate simulations of the transport equation are needed.

  11. Fixed-Node Diffusion Monte Carlo of Lithium Systems

    E-Print Network [OSTI]

    Rasch, Kevin

    2015-01-01T23:59:59.000Z

    We study lithium systems over a range of number of atoms, e.g., atomic anion, dimer, metallic cluster, and body-centered cubic crystal by the diffusion Monte Carlo method. The calculations include both core and valence electrons in order to avoid any possible impact by pseudo potentials. The focus of the study is the fixed-node errors, and for that purpose we test several orbital sets in order to provide the most accurate nodal hyper surfaces. We compare our results to other high accuracy calculations wherever available and to experimental results so as to quantify the the fixed-node errors. The results for these Li systems show that fixed-node quantum Monte Carlo achieves remarkably high accuracy total energies and recovers 97-99 % of the correlation energy.

  12. MC++: Parallel, portable, Monte Carlo neutron transport in C++

    SciTech Connect (OSTI)

    Lee, S.R.; Cummings, J.C. [Los Alamos National Lab., NM (United States); Nolen, S.D. [Texas A& M Univ., College Station, TX (United States). Dept. of Nuclear Engineering

    1997-02-01T23:59:59.000Z

    We have developed an implicit Monte Carlo neutron transport code in C++ using the Parallel Object-Oriented Methods and Applications (POOMA) class library. MC++ runs in parallel on and is portable to a wide variety of platforms, including MPPs, clustered SMPs, and individual workstations. It contains appropriate classes and abstractions for particle transport and parallelism. Current capabilities of MC++ are discussed, along with future plans and physics and performance results on many different platforms.

  13. OBJECT KINETIC MONTE CARLO SIMULATIONS OF MICROSTRUCTURE EVOLUTION

    SciTech Connect (OSTI)

    Nandipati, Giridhar; Setyawan, Wahyu; Heinisch, Howard L.; Roche, Kenneth J.; Kurtz, Richard J.; Wirth, Brian D.

    2013-09-30T23:59:59.000Z

    The objective is to report the development of the flexible object kinetic Monte Carlo (OKMC) simulation code KSOME (kinetic simulation of microstructure evolution) which can be used to simulate microstructure evolution of complex systems under irradiation. In this report we briefly describe the capabilities of KSOME and present preliminary results for short term annealing of single cascades in tungsten at various primary-knock-on atom (PKA) energies and temperatures.

  14. Regional Monte Carlo solution of elliptic partial differential equations

    SciTech Connect (OSTI)

    Booth, T.E.

    1981-01-01T23:59:59.000Z

    A continuous random walk procedure for solving some elliptic partial differential equations at a single point is generalized to estimate the solution everywhere. The Monte Carlo method described here is exact (except at the boundary) in the sense that the only error is the statistical sampling error that tends to zero as the sample size increases. A method to estimate the error introduced at the boundary is provided so that the boundary error can always be made less than the statistical error.

  15. The hybrid Monte Carlo Algorithm and the chiral transition

    SciTech Connect (OSTI)

    Gupta, R.

    1987-01-01T23:59:59.000Z

    In this talk the author describes tests of the Hybrid Monte Carlo Algorithm for QCD done in collaboration with Greg Kilcup and Stephen Sharpe. We find that the acceptance in the glubal Metropolis step for Staggered fermions can be tuned and kept large without having to make the step-size prohibitively small. We present results for the finite temperature transition on 4/sup 4/ and 4 x 6/sup 3/ lattices using this algorithm.

  16. Monte Carlo approach to nuclei and nuclear matter

    SciTech Connect (OSTI)

    Fantoni, Stefano [S.I.S.S.A., International School of Advanced Studies, INFN, Sezione di Trieste and INFM, CNR-DEMOCRITOS National Supercomputing Center (Italy); Gandolfi, Stefano; Illarionov, Alexey Yu. [S.I.S.S.A., International School of Advanced Studies, INFN, Sezione di Trieste (Italy); Schmidt, Kevin E. [Department of Physics, Arizona State University (United States); Pederiva, Francesco [Dipartimento di Fisica, University of Trento (Italy); INFM, CNR-DEMOCRITOS National Supercomputing Center (Greece)

    2008-10-13T23:59:59.000Z

    We report on the most recent applications of the Auxiliary Field Diffusion Monte Carlo (AFDMC) method. The equation of state (EOS) for pure neutron matter in both normal and BCS phase and the superfluid gap in the low-density regime are computed, using a realistic Hamiltonian containing the Argonne AV8' plus Urbana IX three-nucleon interaction. Preliminary results for the EOS of isospin-asymmetric nuclear matter are also presented.

  17. Monte Carlo approach to nuclei and nuclear matter

    E-Print Network [OSTI]

    Stefano Fantoni; Stefano Gandolfi; Alexey Yu. Illarionov; Kevin E. Schmidt; Francesco Pederiva

    2008-07-31T23:59:59.000Z

    We report on the most recent applications of the Auxiliary Field Diffusion Monte Carlo (AFDMC) method. The equation of state (EOS) for pure neutron matter in both normal and BCS phase and the superfluid gap in the low--density regime are computed, using a realistic Hamiltonian containing the Argonne AV8' plus Urbana IX three--nucleon interaction. Preliminary results for the EOS of isospin--asymmetric nuclear matter are also presented.

  18. Quantum Monte Carlo Calculations of Symmetric Nuclear Matter

    SciTech Connect (OSTI)

    Gandolfi, Stefano [Dipartimento di Fisica and INFN, University of Trento, via Sommarive 14, I-38050 Povo, Trento (Italy); Pederiva, Francesco [Dipartimento di Fisica and INFN, University of Trento, via Sommarive 14, I-38050 Povo, Trento (Italy); CNR-DEMOCRITOS National Supercomputing Center, Trieste (Italy); Fantoni, Stefano [Scuola Internazionale Superiore di Studi Avanzati and INFN via Beirut 2/4, 34014 Trieste (Italy); CNR-DEMOCRITOS National Supercomputing Center, Trieste (Italy); Schmidt, Kevin E. [Department of Physics, Arizona State University, Tempe, Arizona (United States)

    2007-03-09T23:59:59.000Z

    We present an accurate numerical study of the equation of state of nuclear matter based on realistic nucleon-nucleon interactions by means of auxiliary field diffusion Monte Carlo (AFDMC) calculations. The AFDMC method samples the spin and isospin degrees of freedom allowing for quantum simulations of large nucleonic systems and represents an important step forward towards a quantitative understanding of problems in nuclear structure and astrophysics.

  19. A Wigner Monte Carlo approach to density functional theory

    SciTech Connect (OSTI)

    Sellier, J.M., E-mail: jeanmichel.sellier@gmail.com; Dimov, I.

    2014-08-01T23:59:59.000Z

    In order to simulate quantum N-body systems, stationary and time-dependent density functional theories rely on the capacity of calculating the single-electron wave-functions of a system from which one obtains the total electron density (Kohn–Sham systems). In this paper, we introduce the use of the Wigner Monte Carlo method in ab-initio calculations. This approach allows time-dependent simulations of chemical systems in the presence of reflective and absorbing boundary conditions. It also enables an intuitive comprehension of chemical systems in terms of the Wigner formalism based on the concept of phase-space. Finally, being based on a Monte Carlo method, it scales very well on parallel machines paving the way towards the time-dependent simulation of very complex molecules. A validation is performed by studying the electron distribution of three different systems, a Lithium atom, a Boron atom and a hydrogenic molecule. For the sake of simplicity, we start from initial conditions not too far from equilibrium and show that the systems reach a stationary regime, as expected (despite no restriction is imposed in the choice of the initial conditions). We also show a good agreement with the standard density functional theory for the hydrogenic molecule. These results demonstrate that the combination of the Wigner Monte Carlo method and Kohn–Sham systems provides a reliable computational tool which could, eventually, be applied to more sophisticated problems.

  20. FZ2MC: A Tool for Monte Carlo Transport Code Geometry Manipulation

    SciTech Connect (OSTI)

    Hackel, B M; Nielsen Jr., D E; Procassini, R J

    2009-02-25T23:59:59.000Z

    The process of creating and validating combinatorial geometry representations of complex systems for use in Monte Carlo transport simulations can be both time consuming and error prone. To simplify this process, a tool has been developed which employs extensions of the Form-Z commercial solid modeling tool. The resultant FZ2MC (Form-Z to Monte Carlo) tool permits users to create, modify and validate Monte Carlo geometry and material composition input data. Plugin modules that export this data to an input file, as well as parse data from existing input files, have been developed for several Monte Carlo codes. The FZ2MC tool is envisioned as a 'universal' tool for the manipulation of Monte Carlo geometry and material data. To this end, collaboration on the development of plug-in modules for additional Monte Carlo codes is desired.

  1. Properties of Reactive Oxygen Species by Quantum Monte Carlo

    E-Print Network [OSTI]

    Andrea Zen; Bernhardt L. Trout; Leonardo Guidoni

    2014-06-16T23:59:59.000Z

    The electronic properties of the oxygen molecule, in its singlet and triplet states, and of many small oxygen-containing radicals and anions have important roles in different fields of Chemistry, Biology and Atmospheric Science. Nevertheless, the electronic structure of such species is a challenge for ab-initio computational approaches because of the difficulties to correctly describe the statical and dynamical correlation effects in presence of one or more unpaired electrons. Only the highest-level quantum chemical approaches can yield reliable characterizations of their molecular properties, such as binding energies, equilibrium structures, molecular vibrations, charge distribution and polarizabilities. In this work we use the variational Monte Carlo (VMC) and the lattice regularized Monte Carlo (LRDMC) methods to investigate the equilibrium geometries and molecular properties of oxygen and oxygen reactive species. Quantum Monte Carlo methods are used in combination with the Jastrow Antisymmetrized Geminal Power (JAGP) wave function ansatz, which has been recently shown to effectively describe the statical and dynamical correlation of different molecular systems. In particular we have studied the oxygen molecule, the superoxide anion, the nitric oxide radical and anion, the hydroxyl and hydroperoxyl radicals and their corresponding anions, and the hydrotrioxyl radical. Overall, the methodology was able to correctly describe the geometrical and electronic properties of these systems, through compact but fully-optimised basis sets and with a computational cost which scales as $N^3-N^4$, where $N$ is the number of electrons. This work is therefore opening the way to the accurate study of the energetics and of the reactivity of large and complex oxygen species by first principles.

  2. Monte Carlo tests of Orbital-Free Density Functional Theory

    E-Print Network [OSTI]

    D. I. Palade

    2014-12-12T23:59:59.000Z

    The relationship between the exact kinetic energy density in a quantum system in the frame of Density Functional Theory and the semiclassical functional expression for the same quantity is investigated. The analysis is performed with Monte Carlo simulations of the Kohn-Sham potentials. We find that the semiclassical form represents the statistical expectation value of the quantum nature. Based on the numerical results, we propose an empirical correction to the existing functional and an associated method to improve the Orbital-Free results.

  3. Adaptively Learning an Importance Function Using Transport Constrained Monte Carlo

    SciTech Connect (OSTI)

    Booth, T.E.

    1998-06-22T23:59:59.000Z

    It is well known that a Monte Carlo estimate can be obtained with zero-variance if an exact importance function for the estimate is known. There are many ways that one might iteratively seek to obtain an ever more exact importance function. This paper describes a method that has obtained ever more exact importance functions that empirically produce an error that is dropping exponentially with computer time. The method described herein constrains the importance function to satisfy the (adjoint) Boltzmann transport equation. This constraint is provided by using the known form of the solution, usually referred to as the Case eigenfunction solution.

  4. Bounded limit for the Monte Carlo point-flux-estimator

    SciTech Connect (OSTI)

    Grimesey, R.A.

    1981-01-01T23:59:59.000Z

    In a Monte Carlo random walk the kernel K(R,E) is used as an expected value estimator at every collision for the collided flux phi/sub c/ r vector,E) at the detector point. A limiting value for the kernel is derived from a diffusion approximation for the probability current at a radius R/sub 1/ from the detector point. The variance of the collided flux at the detector point is thus bounded using this asymptotic form for K(R,E). The bounded point flux estimator is derived. (WHK)

  5. Monte Carlo beam capture and charge breeding simulation

    SciTech Connect (OSTI)

    Kim, J.S.; Liu, C.; Edgell, D.H.; Pardo, R. [FAR-TECH, Inc., 10350 Science Center Drive, San Diego, California 92121 (United States); FAR-TECH, Inc., 10350 Science Center Drive, San Diego, California 92121 (United States) and University of Rochester, Rochester, New York (United States); Argonne National Laboratory, Argonne, Illinois (United States)

    2006-03-15T23:59:59.000Z

    A full six-dimensional (6D) phase space Monte Carlo beam capture charge-breeding simulation code examines the beam capture processes of singly charged ion beams injected to an electron cyclotron resonance (ECR) charge breeder from entry to exit. The code traces injected beam ions in an ECR ion source (ECRIS) plasma including Coulomb collisions, ionization, and charge exchange. The background ECRIS plasma is modeled within the current frame work of the generalized ECR ion source model. A simple sample case of an oxygen background plasma with an injected Ar +1 ion beam produces lower charge breeding efficiencies than experimentally obtained. Possible reasons for discrepancies are discussed.

  6. Burnup calculation methodology in the serpent 2 Monte Carlo code

    SciTech Connect (OSTI)

    Leppaenen, J. [VTT Technical Research Centre of Finland, P.O.Box 1000, FI-02044 VTT (Finland); Isotalo, A. [Aalto Univ., Dept. of Applied Physics, P.O.Box 14100, FI-00076 AALTO (Finland)

    2012-07-01T23:59:59.000Z

    This paper presents two topics related to the burnup calculation capabilities in the Serpent 2 Monte Carlo code: advanced time-integration methods and improved memory management, accomplished by the use of different optimization modes. The development of the introduced methods is an important part of re-writing the Serpent source code, carried out for the purpose of extending the burnup calculation capabilities from 2D assembly-level calculations to large 3D reactor-scale problems. The progress is demonstrated by repeating a PWR test case, originally carried out in 2009 for the validation of the newly-implemented burnup calculation routines in Serpent 1. (authors)

  7. Monte Carlo Tools for charged Higgs boson production

    E-Print Network [OSTI]

    K. Kovarik

    2014-12-18T23:59:59.000Z

    In this short review we discuss two implementations of the charged Higgs boson production process in association with a top quark in Monte Carlo event generators at next-to-leading order in QCD. We introduce the MC@NLO and the POWHEG method of matching next-to-leading order matrix elements with parton showers and compare both methods analyzing the charged Higgs boson production process in association with a top quark. We shortly discuss the case of a light charged Higgs boson where the associated charged Higgs production interferes with the charged Higgs production via t tbar-production and subsequent decay of the top quark.

  8. Electron scattering in helium for Monte Carlo simulations

    SciTech Connect (OSTI)

    Khrabrov, Alexander V.; Kaganovich, Igor D. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2012-09-15T23:59:59.000Z

    An analytical approximation for differential cross-section of electron scattering on helium atoms is introduced. It is intended for Monte Carlo simulations, which, instead of angular distributions based on experimental data (or on first-principle calculations), usually rely on approximations that are accurate yet numerically efficient. The approximation is based on the screened-Coulomb differential cross-section with energy-dependent screening. For helium, a two-pole approximation of the screening parameter is found to be highly accurate over a wide range of energies.

  9. Quantitative Monte Carlo-based holmium-166 SPECT reconstruction

    SciTech Connect (OSTI)

    Elschot, Mattijs; Smits, Maarten L. J.; Nijsen, Johannes F. W.; Lam, Marnix G. E. H.; Zonnenberg, Bernard A.; Bosch, Maurice A. A. J. van den; Jong, Hugo W. A. M. de [Department of Radiology and Nuclear Medicine, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht (Netherlands); Viergever, Max A. [Image Sciences Institute, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht (Netherlands)] [Image Sciences Institute, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht (Netherlands)

    2013-11-15T23:59:59.000Z

    Purpose: Quantitative imaging of the radionuclide distribution is of increasing interest for microsphere radioembolization (RE) of liver malignancies, to aid treatment planning and dosimetry. For this purpose, holmium-166 ({sup 166}Ho) microspheres have been developed, which can be visualized with a gamma camera. The objective of this work is to develop and evaluate a new reconstruction method for quantitative {sup 166}Ho SPECT, including Monte Carlo-based modeling of photon contributions from the full energy spectrum.Methods: A fast Monte Carlo (MC) simulator was developed for simulation of {sup 166}Ho projection images and incorporated in a statistical reconstruction algorithm (SPECT-fMC). Photon scatter and attenuation for all photons sampled from the full {sup 166}Ho energy spectrum were modeled during reconstruction by Monte Carlo simulations. The energy- and distance-dependent collimator-detector response was modeled using precalculated convolution kernels. Phantom experiments were performed to quantitatively evaluate image contrast, image noise, count errors, and activity recovery coefficients (ARCs) of SPECT-fMC in comparison with those of an energy window-based method for correction of down-scattered high-energy photons (SPECT-DSW) and a previously presented hybrid method that combines MC simulation of photopeak scatter with energy window-based estimation of down-scattered high-energy contributions (SPECT-ppMC+DSW). Additionally, the impact of SPECT-fMC on whole-body recovered activities (A{sup est}) and estimated radiation absorbed doses was evaluated using clinical SPECT data of six {sup 166}Ho RE patients.Results: At the same noise level, SPECT-fMC images showed substantially higher contrast than SPECT-DSW and SPECT-ppMC+DSW in spheres ?17 mm in diameter. The count error was reduced from 29% (SPECT-DSW) and 25% (SPECT-ppMC+DSW) to 12% (SPECT-fMC). ARCs in five spherical volumes of 1.96–106.21 ml were improved from 32%–63% (SPECT-DSW) and 50%–80% (SPECT-ppMC+DSW) to 76%–103% (SPECT-fMC). Furthermore, SPECT-fMC recovered whole-body activities were most accurate (A{sup est}= 1.06 × A ? 5.90 MBq, R{sup 2}= 0.97) and SPECT-fMC tumor absorbed doses were significantly higher than with SPECT-DSW (p = 0.031) and SPECT-ppMC+DSW (p = 0.031).Conclusions: The quantitative accuracy of {sup 166}Ho SPECT is improved by Monte Carlo-based modeling of the image degrading factors. Consequently, the proposed reconstruction method enables accurate estimation of the radiation absorbed dose in clinical practice.

  10. Global neutrino parameter estimation using Markov Chain Monte Carlo

    E-Print Network [OSTI]

    Steen Hannestad

    2007-10-10T23:59:59.000Z

    We present a Markov Chain Monte Carlo global analysis of neutrino parameters using both cosmological and experimental data. Results are presented for the combination of all presently available data from oscillation experiments, cosmology, and neutrinoless double beta decay. In addition we explicitly study the interplay between cosmological, tritium decay and neutrinoless double beta decay data in determining the neutrino mass parameters. We furthermore discuss how the inference of non-neutrino cosmological parameters can benefit from future neutrino mass experiments such as the KATRIN tritium decay experiment or neutrinoless double beta decay experiments.

  11. Computational radiology and imaging with the MCNP Monte Carlo code

    SciTech Connect (OSTI)

    Estes, G.P.; Taylor, W.M.

    1995-05-01T23:59:59.000Z

    MCNP, a 3D coupled neutron/photon/electron Monte Carlo radiation transport code, is currently used in medical applications such as cancer radiation treatment planning, interpretation of diagnostic radiation images, and treatment beam optimization. This paper will discuss MCNP`s current uses and capabilities, as well as envisioned improvements that would further enhance MCNP role in computational medicine. It will be demonstrated that the methodology exists to simulate medical images (e.g. SPECT). Techniques will be discussed that would enable the construction of 3D computational geometry models of individual patients for use in patient-specific studies that would improve the quality of care for patients.

  12. Continuous-Estimator Representation for Monte Carlo Criticality Diagnostics

    SciTech Connect (OSTI)

    Kiedrowski, Brian C. [Los Alamos National Laboratory; Brown, Forrest B. [Los Alamos National Laboratory

    2012-06-18T23:59:59.000Z

    An alternate means of computing diagnostics for Monte Carlo criticality calculations is proposed. Overlapping spherical regions or estimators are placed covering the fissile material with a minimum center-to-center separation of the 'fission distance', which is defined herein, and a radius that is some multiple thereof. Fission neutron production is recorded based upon a weighted average of proximities to centers for all the spherical estimators. These scores are used to compute the Shannon entropy, and shown to reproduce the value, to within an additive constant, determined from a well-placed mesh by a user. The spherical estimators are also used to assess statistical coverage.

  13. South El Monte, California: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov YouKizildere IRaghuraji Agro Industries Pvt LtdShawangunk, NewSingaporeSonix Japan IncInformation04316°,El Monte,

  14. El Monte, California: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand JumpConceptual Model,DOEHazel Crest, Illinois:Edinburgh UniversityMirage, Arizona: EnergyMonte,

  15. Mont Vernon, New Hampshire: Energy Resources | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov YouKizildere I Geothermal Pwer Plant JumpMarysville,Missoula, Montana:Northeast Asia |New York:NewMonsey, NewMont Vernon,

  16. Four-quark energies in SU(2) lattice Monte Carlo using a tetrahedral geometry

    E-Print Network [OSTI]

    A. M. Green; J. Lukkarinen; P. Pennanen; C. Michael; S. Furui

    1994-12-05T23:59:59.000Z

    This contribution -- a continuation of earlier work -- reports on recent developments in the calculation and understanding of 4-quark energies generated using lattice Monte Carlo techniques.

  17. Evidence for a phosphorylation-independent role for Ser 32 and 36 in proteasome inhibitor-resistant (PIR) InBa degradation in B cells

    E-Print Network [OSTI]

    Miyamoto, Shigeki

    -resistant (PIR) InBa degradation in B cells Shelby O'Connor, Stephanie Markovina, Shigeki MiyamotoT Program is maintained through proteasome inhibitor-resistant (PIR) InBa degradation in a manner that requires Ser 32 whether dual phosphorylation of Ser 32 and 36 was required for PIR degradation. Through mutagenesis

  18. Monte Carlo simulation of quantum Zeno effect in the brain

    E-Print Network [OSTI]

    Danko Georgiev

    2014-12-11T23:59:59.000Z

    Environmental decoherence appears to be the biggest obstacle for successful construction of quantum mind theories. Nevertheless, the quantum physicist Henry Stapp promoted the view that the mind could utilize quantum Zeno effect to influence brain dynamics and that the efficacy of such mental efforts would not be undermined by environmental decoherence of the brain. To address the physical plausibility of Stapp's claim, we modeled the brain using quantum tunneling of an electron in a multiple-well structure such as the voltage sensor in neuronal ion channels and performed Monte Carlo simulations of quantum Zeno effect exerted by the mind upon the brain in the presence or absence of environmental decoherence. The simulations unambiguously showed that the quantum Zeno effect breaks down for timescales greater than the brain decoherence time. To generalize the Monte Carlo simulation results for any n-level quantum system, we further analyzed the change of brain entropy due to the mind probing actions and proved a theorem according to which local projections cannot decrease the von Neumann entropy of the unconditional brain density matrix. The latter theorem establishes that Stapp's model is physically implausible but leaves a door open for future development of quantum mind theories provided the brain has a decoherence-free subspace.

  19. Monte Carlo model for electron degradation in methane

    E-Print Network [OSTI]

    Bhardwaj, Anil

    2015-01-01T23:59:59.000Z

    We present a Monte Carlo model for degradation of 1-10,000 eV electrons in an atmosphere of methane. The electron impact cross sections for CH4 are compiled and analytical representations of these cross sections are used as input to the model.model.Yield spectra, which provides information about the number of inelastic events that have taken place in each energy bin, is used to calculate the yield (or population) of various inelastic processes. The numerical yield spectra, obtained from the Monte Carlo simulations, is represented analytically, thus generating the Analytical Yield Spectra (AYS). AYS is employed to obtain the mean energy per ion pair and efficiencies of various inelastic processes.Mean energy per ion pair for neutral CH4 is found to be 26 (27.8) eV at 10 (0.1) keV. Efficiency calculation showed that ionization is the dominant process at energies >50 eV, for which more than 50% of the incident electron energy is used. Above 25 eV, dissociation has an efficiency of 27%. Below 10 eV, vibrational e...

  20. Genome sequence of the Brown Norway rat yields insights into

    E-Print Network [OSTI]

    Pachter, Lior

    Genome sequence of the Brown Norway rat yields insights into mammalian evolution Rat Genome Norway (BN) rat strain. The sequence represents a high-quality `draft' covering over 90% of the genome

  1. Package for the Interactive Analysis of Line Emission: MarkovChain and Monte Carlo Methods

    E-Print Network [OSTI]

    ­ ods in the Package for Interactive Analysis of Line Emis­ sion (PINTofALE), which is a collection to determine errors in spectral line parameters, and use Markov­Chain Monte Carlo meth­ ods to construct­ ated using a known DEM. Monte Carlo and MCMC meth­ ods have attained increasing popularity in a diverse

  2. On Filtering the Noise from the Random Parameters in Monte Carlo Rendering

    E-Print Network [OSTI]

    Sen, Pradeep

    On Filtering the Noise from the Random Parameters in Monte Carlo Rendering PRADEEP SEN and SOHEIL DARABI UNM Advanced Graphics Lab Monte Carlo (MC) rendering systems can produce spectacular images from a small number of input samples. To do this, we treat the rendering system as a black box

  3. Path Integral Monte Carlo and Density Functional Molecular Dynamics Simulations of Hot, Dense Helium

    E-Print Network [OSTI]

    Militzer, Burkhard

    Path Integral Monte Carlo and Density Functional Molecular Dynamics Simulations of Hot, Dense integral Monte Carlo (PIMC) and density func- tional molecular dynamics (DFT-MD), are applied to study hot excitation mecha- nisms that determine their behavior at high temperature. The helium atom has two ionization

  4. Hybrid Probabilistic RoadMap -Monte Carlo Motion Planning for Closed Chain Systems with

    E-Print Network [OSTI]

    Han, Li

    Hybrid Probabilistic RoadMap - Monte Carlo Motion Planning for Closed Chain Systems with Spherical@clarku.edu Abstract-- In this paper we propose a hybrid Probabilistic RoadMap - Monte Carlo (PRM-MC) motion planner and connect a large number of robot configurations in order to build a roadmap that reflects the properties

  5. Improved quantum Monte Carlo calculation of the ground-state energy of the hydrogen molecule

    E-Print Network [OSTI]

    Anderson, James B.

    variational energies. The accuracy of the new Monte Carlo energy is approximately equal to that of recentImproved quantum Monte Carlo calculation of the ground-state energy of the hydrogen molecule Bin Carlo calculation of the nonrelativistic ground-state energy of the hydrogen molecule, without the use

  6. An Energy Localization Principle and its Application to Fast Kinetic Monte Carlo Simulation of Heteroepitaxial

    E-Print Network [OSTI]

    Schulze, Tim

    An Energy Localization Principle and its Application to Fast Kinetic Monte Carlo Simulation of Michigan, Ann Arbor, MI 48109-1109 Abstract Simulation of heteroepitaxial growth using kinetic Monte Carlo (KMC) is often based on rates determined by differences in elastic energy between two configurations

  7. Tuning Green's Function Monte Carlo for Mira Steven C. Pieper, Physics Division, Argonne National Laboratory

    E-Print Network [OSTI]

    Kemner, Ken

    Tuning Green's Function Monte Carlo for Mira Steven C. Pieper, Physics Division, Argonne National Laboratory Partners in crime Ralph Butler (Middle Tennessee State) Joseph Carlson (Los Alamos) Stefano for comparisons of models to data · Quantum Monte Carlo has made much progress for A 12 · Nuclei go up to A=238

  8. A new quasi-Monte Carlo technique based on nonnegative least squares and

    E-Print Network [OSTI]

    De Marchi, Stefano

    A new quasi-Monte Carlo technique based on nonnegative least squares and approximate Fekete points Claudia Bittantea , Stefano De Marchia, , Alvise Sommarivaa aUniversity of Padova, Department of the quasi-Monte Carlo method. The method, simple in its formulation, be- comes computationally inefficient

  9. BAYESIAN INFERENCE FOR MODELS OF TRANSCRIPTIONAL REGULATION USING MARKOV CHAIN MONTE CARLO SAMPLING

    E-Print Network [OSTI]

    Opper, Manfred

    ]. In this contribution we present a Markov chain Monte Carlo (MCMC) sampler which infers the TF activity based on a modelBAYESIAN INFERENCE FOR MODELS OF TRANSCRIPTIONAL REGULATION USING MARKOV CHAIN MONTE CARLO SAMPLING]. Transcription of genes is controlled by proteins which can bind to particular base-sequences of DNA

  10. Monte Carlo Methods for Uncertainty Quantification Mathematical Institute, University of Oxford

    E-Print Network [OSTI]

    Giles, Mike

    methods October 25, 2013 7 / 28 Application 3 In modelling groundwater flow in nuclear waste repositories: Introduction and Monte Carlo basics some model applications random number generation Monte Carlo estimation specified range Note: if we turn this into a full finite element analysis, then the computational cost

  11. Brachytherapy structural shielding calculations using Monte Carlo generated, monoenergetic data

    SciTech Connect (OSTI)

    Zourari, K.; Peppa, V.; Papagiannis, P., E-mail: ppapagi@phys.uoa.gr [Medical Physics Laboratory, Medical School, University of Athens, 75 Mikras Asias, 11527 Athens (Greece); Ballester, Facundo [Department of Atomic, Molecular and Nuclear Physics, University of Valencia, Burjassot 46100 (Spain)] [Department of Atomic, Molecular and Nuclear Physics, University of Valencia, Burjassot 46100 (Spain); Siebert, Frank-André [Clinic of Radiotherapy, University Hospital of Schleswig-Holstein, Campus Kiel 24105 (Germany)] [Clinic of Radiotherapy, University Hospital of Schleswig-Holstein, Campus Kiel 24105 (Germany)

    2014-04-15T23:59:59.000Z

    Purpose: To provide a method for calculating the transmission of any broad photon beam with a known energy spectrum in the range of 20–1090 keV, through concrete and lead, based on the superposition of corresponding monoenergetic data obtained from Monte Carlo simulation. Methods: MCNP5 was used to calculate broad photon beam transmission data through varying thickness of lead and concrete, for monoenergetic point sources of energy in the range pertinent to brachytherapy (20–1090 keV, in 10 keV intervals). The three parameter empirical model introduced byArcher et al. [“Diagnostic x-ray shielding design based on an empirical model of photon attenuation,” Health Phys. 44, 507–517 (1983)] was used to describe the transmission curve for each of the 216 energy-material combinations. These three parameters, and hence the transmission curve, for any polyenergetic spectrum can then be obtained by superposition along the lines of Kharrati et al. [“Monte Carlo simulation of x-ray buildup factors of lead and its applications in shielding of diagnostic x-ray facilities,” Med. Phys. 34, 1398–1404 (2007)]. A simple program, incorporating a graphical user interface, was developed to facilitate the superposition of monoenergetic data, the graphical and tabular display of broad photon beam transmission curves, and the calculation of material thickness required for a given transmission from these curves. Results: Polyenergetic broad photon beam transmission curves of this work, calculated from the superposition of monoenergetic data, are compared to corresponding results in the literature. A good agreement is observed with results in the literature obtained from Monte Carlo simulations for the photon spectra emitted from bare point sources of various radionuclides. Differences are observed with corresponding results in the literature for x-ray spectra at various tube potentials, mainly due to the different broad beam conditions or x-ray spectra assumed. Conclusions: The data of this work allow for the accurate calculation of structural shielding thickness, taking into account the spectral variation with shield thickness, and broad beam conditions, in a realistic geometry. The simplicity of calculations also obviates the need for the use of crude transmission data estimates such as the half and tenth value layer indices. Although this study was primarily designed for brachytherapy, results might also be useful for radiology and nuclear medicine facility design, provided broad beam conditions apply.

  12. Water Retrieval by Norway Rats: Behavior as Deduction

    E-Print Network [OSTI]

    Wallace, R J

    1998-01-01T23:59:59.000Z

    1948). Burrows and feeding of the Norway a radial Mammalogy,Object retrieval preferences of Norway rats: An evolutionaryinedible objects by Norway rats: Motivational interactions

  13. albino rats rattus: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    most commonly used in research are believed to be domesticated albino strains of the Norway rat rattus nirvegicus. Rats like mice, belong to the order Rodentia Biology and...

  14. albino rat cfn: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    most commonly used in research are believed to be domesticated albino strains of the Norway rat rattus nirvegicus. Rats like mice, belong to the order Rodentia Biology and...

  15. albino wistar rats: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    most commonly used in research are believed to be domesticated albino strains of the Norway rat rattus nirvegicus. Rats like mice, belong to the order Rodentia Biology and...

  16. albino rats exposed: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    most commonly used in research are believed to be domesticated albino strains of the Norway rat rattus nirvegicus. Rats like mice, belong to the order Rodentia Biology and...

  17. albino rat anatomical: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    most commonly used in research are believed to be domesticated albino strains of the Norway rat rattus nirvegicus. Rats like mice, belong to the order Rodentia Biology and...

  18. A New Methodology for Characterization of Environmentally Important Radionuclide Species Via Surface-Enhanced Raman Scattering (SERS)

    SciTech Connect (OSTI)

    Dai, Sheng; Bao, Li-Li; Mahurin, Shannon; Gu, Baohua

    2004-03-31T23:59:59.000Z

    Selective and sensitive detection and characterization of radionuclide contaminants in subsurface environments is essential to safely and to cost-effectively locate, treat, isolate or destroy contaminants encountered in DOE's environmental cleanup activity. Currently, techniques for monitoring and characterizing radionuclides rely primarily on liquid scintillation counting, ICP-MS and some limited use of the spectrofluorimetry based on fluorescence of radionuclide species under laser or UV excitation. These techniques require chemical handling, e.g., the use of complexing media, scintillation cocktails and phosphoric acids, in order to enhance signals. Furthermore, only fluorescent radionuclides (U22O+, Cm(III) and Am(III)) can be detected by the last technique. Many environmentally-important radionuclides such as plutonium, neptunium and technetium species have no strong fluorescence signals and, therefore, can not be characterized via fluorescence spectroscopy. The research presented serves to replace existing radionuclide-detection techniques through the development of a novel surface enhanced Raman scattering (SERS) spectroscopy to selectively and sensitively monitor and characterize the chemical speciation of radionuclides at trace levels. The SERS technique permits both of these measurements to be made simultaneously and results in significant improvement over current methods in reducing time of analysis, cost and sample manipulation.

  19. SKIRT: the design of a suite of input models for Monte Carlo radiative transfer simulations

    E-Print Network [OSTI]

    Baes, Maarten

    2015-01-01T23:59:59.000Z

    The Monte Carlo method is the most popular technique to perform radiative transfer simulations in a general 3D geometry. The algorithms behind and acceleration techniques for Monte Carlo radiative transfer are discussed extensively in the literature, and many different Monte Carlo codes are publicly available. On the contrary, the design of a suite of components that can be used for the distribution of sources and sinks in radiative transfer codes has received very little attention. The availability of such models, with different degrees of complexity, has many benefits. For example, they can serve as toy models to test new physical ingredients, or as parameterised models for inverse radiative transfer fitting. For 3D Monte Carlo codes, this requires algorithms to efficiently generate random positions from 3D density distributions. We describe the design of a flexible suite of components for the Monte Carlo radiative transfer code SKIRT. The design is based on a combination of basic building blocks (which can...

  20. Monte Carlo Simulation Tool Installation and Operation Guide

    SciTech Connect (OSTI)

    Aguayo Navarrete, Estanislao; Ankney, Austin S.; Berguson, Timothy J.; Kouzes, Richard T.; Orrell, John L.; Troy, Meredith D.; Wiseman, Clinton G.

    2013-09-02T23:59:59.000Z

    This document provides information on software and procedures for Monte Carlo simulations based on the Geant4 toolkit, the ROOT data analysis software and the CRY cosmic ray library. These tools have been chosen for its application to shield design and activation studies as part of the simulation task for the Majorana Collaboration. This document includes instructions for installation, operation and modification of the simulation code in a high cyber-security computing environment, such as the Pacific Northwest National Laboratory network. It is intended as a living document, and will be periodically updated. It is a starting point for information collection by an experimenter, and is not the definitive source. Users should consult with one of the authors for guidance on how to find the most current information for their needs.

  1. Atomistic Kinetic Monte Carlo Simulations of Polycrystalline Copper Electrodeposition

    E-Print Network [OSTI]

    Treeratanaphitak, Tanyakarn; Abukhdeir, Nasser Mohieddin

    2014-01-01T23:59:59.000Z

    A high-fidelity kinetic Monte Carlo (KMC) simulation method (T. Treeratanaphitak, M. Pritzker, N. M. Abukhdeir, Electrochim. Acta 121 (2014) 407--414) using the semi-empirical multi-body embedded-atom method (EAM) potential has been extended to model polycrystalline metal electrodeposition. The presented KMC-EAM method enables true three-dimensional atomistic simulations of electrodeposition over experimentally relevant timescales. Simulations using KMC-EAM are performed over a range of overpotentials to predict the effect on deposit texture evolution. Results show strong agreement with past experimental results both with respect to deposition rates on various copper surfaces and roughness-time power law behaviour. It is found that roughness scales with time $\\propto t^\\beta$ where $\\beta=0.62 \\pm 0.12$, which is in good agreement with past experimental results. Furthermore, the simulations provide insights into sub-surface deposit morphologies which are not directly accessible from experimental measurements.

  2. Peelle's pertinent puzzle using the Monte Carlo technique

    SciTech Connect (OSTI)

    Kawano, Toshihiko [Los Alamos National Laboratory; Talou, Patrick [Los Alamos National Laboratory; Burr, Thomas [Los Alamos National Laboratory; Pan, Feng [Los Alamos National Laboratory

    2009-01-01T23:59:59.000Z

    We try to understand the long-standing problem of the Peelle's Pertinent Puzzle (PPP) using the Monte Carlo technique. We allow the probability density functions to be any kind of form to assume the impact of distribution, and obtain the least-squares solution directly from numerical simulations. We found that the standard least squares method gives the correct answer if a weighting function is properly provided. Results from numerical simulations show that the correct answer of PPP is 1.1 {+-} 0.25 if the common error is multiplicative. The thought-provoking answer of 0.88 is also correct, if the common error is additive, and if the error is proportional to the measured values. The least squares method correctly gives us the most probable case, where the additive component has a negative value. Finally, the standard method fails for PPP due to a distorted (non Gaussian) joint distribution.

  3. The neutron instrument Monte Carlo library MCLIB: Recent developments

    SciTech Connect (OSTI)

    Seeger, P.A.; Daemen, L.L.; Hjelm, R.P. Jr.; Thelliez, T.G.

    1998-12-31T23:59:59.000Z

    A brief review is given of the developments since the ICANS-XIII meeting made in the neutron instrument design codes using the Monte Carlo library MCLIB. Much of the effort has been to assure that the library and the executing code MC{_}RUN connect efficiently with the World Wide Web application MC-WEB as part of the Los Alamos Neutron Instrument Simulation Package (NISP). Since one of the most important features of MCLIB is its open structure and capability to incorporate any possible neutron transport or scattering algorithm, this document describes the current procedure that would be used by an outside user to add a feature to MCLIB. Details of the calling sequence of the core subroutine OPERATE are discussed, and questions of style are considered and additional guidelines given. Suggestions for standardization are solicited, as well as code for new algorithms.

  4. Hybrid Monte Carlo simulation on the graphene hexagonal lattice

    E-Print Network [OSTI]

    Richard Brower; Claudio Rebbi; David Schaich

    2012-04-24T23:59:59.000Z

    One of the many remarkable properties of graphene is that in the low energy limit the dynamics of its electrons can be effectively described by the massless Dirac equation. This has prompted investigations of graphene based on the lattice simulation of a system of 2-dimensional fermions on a square staggered lattice. We demonstrate here how to construct the path integral for graphene working directly on the graphene hexagonal lattice. For the nearest neighbor tight binding model interacting with a long range Coulomb interaction between the electrons, this leads to the hybrid Monte Carlo algorithm with no sign problem. The only approximation is the discretization of the Euclidean time. So as we extrapolate to the time continuum limit, the exact tight binding solution maybe found numerically to arbitrary precession on a finite hexagonal lattice. The potential for this approach is tested on a single hexagonal cell.

  5. RMC - A Monte Carlo code for reactor physics analysis

    SciTech Connect (OSTI)

    Wang, K.; Li, Z.; She, D.; Liang, J.; Xu, Q.; Qiu, A.; Yu, J.; Sun, J.; Fan, X.; Yu, G. [Department of Engineering Physics, Tsinghua University, Liuqing Building, Beijing, 100084 (China)

    2013-07-01T23:59:59.000Z

    A new Monte Carlo neutron transport code RMC has been being developed by Department of Engineering Physics, Tsinghua University, Beijing as a tool for reactor physics analysis on high-performance computing platforms. To meet the requirements of reactor analysis, RMC now has such functions as criticality calculation, fixed-source calculation, burnup calculation and kinetics simulations. Some techniques for geometry treatment, new burnup algorithm, source convergence acceleration, massive tally and parallel calculation, and temperature dependent cross sections processing are researched and implemented in RMC to improve the efficiency. Validation results of criticality calculation, burnup calculation, source convergence acceleration, tallies performance and parallel performance shown in this paper prove the capabilities of RMC in dealing with reactor analysis problems with good performances. (authors)

  6. Monte Carlo reactor calculation with substantially reduced number of cycles

    SciTech Connect (OSTI)

    Lee, M. J.; Joo, H. G. [Seoul National Univ., 599 Gwanak-ro, Gwanak-gu, Seoul, 151-744 (Korea, Republic of); Lee, D. [Ulsan National Inst. of Science and Technology, UNIST-gil 50, Eonyang-eup, Ulju-gun, Ulsan, 689-798 (Korea, Republic of); Smith, K. [Massachusetts Inst. of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307 (United States)

    2012-07-01T23:59:59.000Z

    A new Monte Carlo (MC) eigenvalue calculation scheme that substantially reduces the number of cycles is introduced with the aid of coarse mesh finite difference (CMFD) formulation. First, it is confirmed in terms of pin power errors that using extremely many particles resulting in short active cycles is beneficial even in the conventional MC scheme although wasted operations in inactive cycles cannot be reduced with more particles. A CMFD-assisted MC scheme is introduced as an effort to reduce the number of inactive cycles and the fast convergence behavior and reduced inter-cycle effect of the CMFD assisted MC calculation is investigated in detail. As a practical means of providing a good initial fission source distribution, an assembly based few-group condensation and homogenization scheme is introduced and it is shown that efficient MC eigenvalue calculations with fewer than 20 total cycles (including inactive cycles) are possible for large power reactor problems. (authors)

  7. Velocity renormalization in graphene from lattice Monte Carlo

    E-Print Network [OSTI]

    Joaquín E. Drut; Timo A. Lähde

    2014-03-26T23:59:59.000Z

    We compute the Fermi velocity of the Dirac quasiparticles in clean graphene at the charge neutrality point for strong Coulomb coupling alpha_g. We perform a Lattice Monte Carlo calculation within the low-energy Dirac theory, which includes an instantaneous, long-range Coulomb interaction. We find a renormalized Fermi velocity v_FR > v_F, where v_F = c/300. Our results are consistent with a momentum-independent v_FR which increases approximately linearly with alpha_g, although a logarithmic running with momentum cannot be excluded at present. At the predicted critical coupling alpha_gc for the semimetal-insulator transition due to excitonic pair formation, we find v_FR/v_F = 3.3, which we discuss in light of experimental findings for v_FR/v_F at the charge neutrality point in ultra-clean suspended graphene.

  8. Quality assurance for the ALICE Monte Carlo procedure

    E-Print Network [OSTI]

    M. Ajaz; Seforo Mohlalisi; Peter Hristov; Jean Pierre Revol

    2009-04-10T23:59:59.000Z

    We implement the already existing macro,$ALICE_ROOT/STEER /CheckESD.C that is ran after reconstruction to compute the physics efficiency, as a task that will run on proof framework like CAF. The task was implemented in a C++ class called AliAnalysisTaskCheckESD and it inherits from AliAnalysisTaskSE base class. The function of AliAnalysisTaskCheckESD is to compute the ratio of the number of reconstructed particles to the number of particle generated by the Monte Carlo generator.The class AliAnalysisTaskCheckESD was successfully implemented. It was used during the production for first physics and permitted to discover several problems (missing track in the MUON arm reconstruction, low efficiency in the PHOS detector etc.). The code is committed to the SVN repository and will become standard tool for quality assurance.

  9. Normality of Monte Carlo criticality eigenfunction decomposition coefficients

    SciTech Connect (OSTI)

    Toth, B. E.; Martin, W. R. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States); Griesheimer, D. P. [Bechtel Bettis, Inc., P.O. Box 79, West Mifflin, PA 15122 (United States)

    2013-07-01T23:59:59.000Z

    A proof is presented, which shows that after a single Monte Carlo (MC) neutron transport power method iteration without normalization, the coefficients of an eigenfunction decomposition of the fission source density are normally distributed when using analog or implicit capture MC. Using a Pearson correlation coefficient test, the proof is corroborated by results from a uniform slab reactor problem, and those results also suggest that the coefficients are normally distributed with normalization. The proof and numerical test results support the application of earlier work on the convergence of eigenfunctions under stochastic operators. Knowledge of the Gaussian shape of decomposition coefficients allows researchers to determine an appropriate level of confidence in the distribution of fission sites taken from a MC simulation. This knowledge of the shape of the probability distributions of decomposition coefficients encourages the creation of new predictive convergence diagnostics. (authors)

  10. Single temperature for Monte Carlo optimization on complex landscapes

    E-Print Network [OSTI]

    Tolkunov, Denis

    2012-01-01T23:59:59.000Z

    We propose a new strategy for Monte Carlo (MC) optimization on rugged multidimensional landscapes. The strategy is based on querying the statistical properties of the landscape in order to find the temperature at which the mean first passage time across the current region of the landscape is minimized. Thus, in contrast to other algorithms such as simulated annealing (SA), we explicitly match the temperature schedule to the statistics of landscape irregularities. In cases where this statistics is approximately the same over the entire landscape, or where non-local moves couple distant parts of the landscape, single-temperature MC will outperform any other MC algorithm with the same move set. We also find that in strongly anisotropic Coulomb spin glass and traveling salesman problems, the only relevant statistics (which we use to assign a single MC temperature) is that of irregularities in low-energy funnels. Our results may explain why protein folding in nature is efficient at room temperatures.

  11. Strain in the mesoscale kinetic Monte Carlo model for sintering

    E-Print Network [OSTI]

    Bjørk, R; Tikare, V; Olevsky, E; Pryds, N

    2014-01-01T23:59:59.000Z

    Shrinkage strains measured from microstructural simulations using the mesoscale kinetic Monte Carlo (kMC) model for solid state sintering are discussed. This model represents the microstructure using digitized discrete sites that are either grain or pore sites. The algorithm used to simulate densification by vacancy annihilation removes an isolated pore site at a grain boundary and collapses a column of sites extending from the vacancy to the surface of sintering compact, through the center of mass of the nearest grain. Using this algorithm, the existing published kMC models are shown to produce anisotropic strains for homogeneous powder compacts with aspect ratios different from unity. It is shown that the line direction biases shrinkage strains in proportion the compact dimension aspect ratios. A new algorithm that corrects this bias in strains is proposed; the direction for collapsing the column is determined by choosing a random sample face and subsequently a random point on that face as the end point for...

  12. Monte Carlo solution of a semi-discrete transport equation

    SciTech Connect (OSTI)

    Urbatsch, T.J.; Morel, J.E.; Gulick, J.C.

    1999-09-01T23:59:59.000Z

    The authors present the S{sub {infinity}} method, a hybrid neutron transport method in which Monte Carlo particles traverse discrete space. The goal of any deterministic/stochastic hybrid method is to couple selected characters from each of the methods in hopes of producing a better method. The S{sub {infinity}} method has the features of the lumped, linear-discontinuous (LLD) spatial discretization, yet it has no ray-effects because of the continuous angular variable. They derive the S{sub {infinity}} method for the solid-state, mono-energetic transport equation in one-dimensional slab geometry with isotropic scattering and an isotropic internal source. They demonstrate the viability of the S{sub {infinity}} method by comparing their results favorably to analytic and deterministic results.

  13. Quantum Monte Carlo study of inhomogeneous neutron matter

    E-Print Network [OSTI]

    Stefano Gandolfi

    2012-08-31T23:59:59.000Z

    We present an ab-initio study of neutron drops. We use Quantum Monte Carlo techniques to calculate the energy up to 54 neutrons in different external potentials, and we compare the results with Skyrme forces. We also calculate the rms radii and radial densities, and we find that a re-adjustment of the gradient term in Skyrme is needed in order to reproduce the properties of these systems given by the ab-initio calculation. By using the ab-initio results for neutron drops for close- and open-shell configurations, we suggest how to improve Skyrme forces when dealing with systems with large isospin-asymmetries like neutron-rich nuclei.

  14. Monte Carlo modeling of spallation targets containing uranium and americium

    E-Print Network [OSTI]

    Yury Malyshkin; Igor Pshenichnov; Igor Mishustin; Walter Greiner

    2014-05-02T23:59:59.000Z

    Neutron production and transport in spallation targets made of uranium and americium are studied with a Geant4-based code MCADS (Monte Carlo model for Accelerator Driven Systems). A good agreement of MCADS results with experimental data on neutron- and proton-induced reactions on $^{241}$Am and $^{243}$Am nuclei allows to use this model for simulations with extended Am targets. It was demonstrated that MCADS model can be used for calculating the values of critical mass for $^{233,235}$U, $^{237}$Np, $^{239}$Pu and $^{241}$Am. Several geometry options and material compositions (U, U+Am, Am, Am$_2$O$_3$) are considered for spallation targets to be used in Accelerator Driven Systems. All considered options operate as deep subcritical targets having neutron multiplication factor of $k \\sim 0.5$. It is found that more than 4 kg of Am can be burned in one spallation target during the first year of operation.

  15. Polarized light propagation in highly scattering turbid media with a distribution of the particle size: a Monte Carlo study

    E-Print Network [OSTI]

    Koh, Wonshill

    2013-02-22T23:59:59.000Z

    The light propagation in highly scattering turbid media composed of the particles with different size distribution is studied using a Monte Carlo simulation model implemented in Standard C. Monte Carlo method has been widely utilized to study...

  16. Monte Carlo simulation study of scanning Auger electron images

    SciTech Connect (OSTI)

    Li, Y. G.; Ding, Z. J. [Department of Physics and Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Z. M. [Department of Astronomy and Applied Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2009-07-15T23:59:59.000Z

    Simulation of contrast formation in Auger electron imaging of surfaces is helpful for analyzing scanning Auger microscopy/microanalysis (SAM) images. In this work, we have extended our previous Monte Carlo model and the simulation method for calculation of scanning electron microscopy (SEM) images to SAM images of complex structures. The essentials of the simulation method are as follows. (1) We use a constructive solid geometry modeling for a sample geometry, which is complex in elemental distribution, as well as in topographical configuration and a ray-tracing technique in the calculation procedure of electron flight steps that across the different element zones. The combination of the basic objects filled with elements, alloys, or compounds enables the simulation to a variety of sample geometries. (2) Sampled Auger signal electrons with a characteristic energy are generated in the simulation following an inner-shell ionization event, whose description is based on the Castani's inner-shell ionization cross section. This paper discusses in detail the features of simulated SAM images and of line scans for structured samples, i.e., the objects embedded in a matrix, under various experimental conditions (object size, location depth, beam energy, and the incident angle). Several effects are predicted and explained, such as the contrast reversion for nanoparticles in sizes of 10-60 nm, the contrast enhancement for particles made of different elements and wholly embedded in a matrix, and the artifact contrast due to nearby objects containing different elements. The simulated SAM images are also compared with the simulated SEM images of secondary electrons and of backscattered electrons. The results indicate that the Monte Carlo simulation can play an important role in quantitative SAM mapping.

  17. Ethanol Consumption by Rat Dams During Gestation,

    E-Print Network [OSTI]

    Galef Jr., Bennett G.

    Ethanol Consumption by Rat Dams During Gestation, Lactation and Weaning Increases Ethanol examined effects of ethanol consumption in rat dams during gestation, lactation, and weaning on voluntary ethanol consumption by their adolescent young. We found that exposure to an ethanol-ingesting dam

  18. Enhanced physics design with hexagonal repeated structure tools using Monte Carlo methods

    SciTech Connect (OSTI)

    Carter, L L; Lan, J S; Schwarz, R A

    1991-01-01T23:59:59.000Z

    This report discusses proposed new missions for the Fast Flux Test Facility (FFTF) reactor which involve the use of target assemblies containing local hydrogenous moderation within this otherwise fast reactor. Parametric physics design studies with Monte Carlo methods are routinely utilized to analyze the rapidly changing neutron spectrum. An extensive utilization of the hexagonal lattice within lattice capabilities of the Monte Carlo Neutron Photon (MCNP) continuous energy Monte Carlo computer code is applied here to solving such problems. Simpler examples that use the lattice capability to describe fuel pins within a brute force'' description of the hexagonal assemblies are also given.

  19. Monte Carlo solution for uncertainty propagation in particle transport with a stochastic Galerkin method

    SciTech Connect (OSTI)

    Franke, B. C. [Sandia National Laboratories, Albuquerque, NM 87185 (United States); Prinja, A. K. [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, NM 87131 (United States)

    2013-07-01T23:59:59.000Z

    The stochastic Galerkin method (SGM) is an intrusive technique for propagating data uncertainty in physical models. The method reduces the random model to a system of coupled deterministic equations for the moments of stochastic spectral expansions of result quantities. We investigate solving these equations using the Monte Carlo technique. We compare the efficiency with brute-force Monte Carlo evaluation of uncertainty, the non-intrusive stochastic collocation method (SCM), and an intrusive Monte Carlo implementation of the stochastic collocation method. We also describe the stability limitations of our SGM implementation. (authors)

  20. Coupled Deterministic-Monte Carlo Transport for Radiation Portal Modeling

    SciTech Connect (OSTI)

    Smith, Leon E.; Miller, Erin A.; Wittman, Richard S.; Shaver, Mark W.

    2008-01-14T23:59:59.000Z

    Radiation portal monitors are being deployed, both domestically and internationally, to detect illicit movement of radiological materials concealed in cargo. Evaluation of the current and next generations of these radiation portal monitor (RPM) technologies is an ongoing process. 'Injection studies' that superimpose, computationally, the signature from threat materials onto empirical vehicle profiles collected at ports of entry, are often a component of the RPM evaluation process. However, measurement of realistic threat devices can be both expensive and time-consuming. Radiation transport methods that can predict the response of radiation detection sensors with high fidelity, and do so rapidly enough to allow the modeling of many different threat-source configurations, are a cornerstone of reliable evaluation results. Monte Carlo methods have been the primary tool of the detection community for these kinds of calculations, in no small part because they are particularly effective for calculating pulse-height spectra in gamma-ray spectrometers. However, computational times for problems with a high degree of scattering and absorption can be extremely long. Deterministic codes that discretize the transport in space, angle, and energy offer potential advantages in computational efficiency for these same kinds of problems, but the pulse-height calculations needed to predict gamma-ray spectrometer response are not readily accessible. These complementary strengths for radiation detection scenarios suggest that coupling Monte Carlo and deterministic methods could be beneficial in terms of computational efficiency. Pacific Northwest National Laboratory and its collaborators are developing a RAdiation Detection Scenario Analysis Toolbox (RADSAT) founded on this coupling approach. The deterministic core of RADSAT is Attila, a three-dimensional, tetrahedral-mesh code originally developed by Los Alamos National Laboratory, and since expanded and refined by Transpire, Inc. [1]. MCNP5 is used to calculate sensor pulse-height tallies. RADSAT methods, including adaptive, problem-specific energy-group creation, ray-effect mitigation strategies and the porting of deterministic angular flux to MCNP for individual particle creation are described in [2][3][4]. This paper discusses the application of RADSAT to the modeling of gamma-ray spectrometers in RPMs.

  1. Monte Carlo Monte Carlo

    E-Print Network [OSTI]

    treatment of the ge- ometry, but successive versions added such features as cross-section libraries and green above. As the temperature of the plasma decreases, lattice-like peaks begin to form in the pair

  2. Monte Carlo Sampling of Negative-temperature Plasma States

    SciTech Connect (OSTI)

    John A. Krommes; Sharadini Rath

    2002-07-19T23:59:59.000Z

    A Monte Carlo procedure is used to generate N-particle configurations compatible with two-temperature canonical equilibria in two dimensions, with particular attention to nonlinear plasma gyrokinetics. An unusual feature of the problem is the importance of a nontrivial probability density function R0(PHI), the probability of realizing a set {Phi} of Fourier amplitudes associated with an ensemble of uniformly distributed, independent particles. This quantity arises because the equilibrium distribution is specified in terms of {Phi}, whereas the sampling procedure naturally produces particles states gamma; {Phi} and gamma are related via a gyrokinetic Poisson equation, highly nonlinear in its dependence on gamma. Expansion and asymptotic methods are used to calculate R0(PHI) analytically; excellent agreement is found between the large-N asymptotic result and a direct numerical calculation. The algorithm is tested by successfully generating a variety of states of both positive and negative temperature, including ones in which either the longest- or shortest-wavelength modes are excited to relatively very large amplitudes.

  3. Global variance reduction for Monte Carlo reactor physics calculations

    SciTech Connect (OSTI)

    Zhang, Q.; Abdel-Khalik, H. S. [Department of Nuclear Engineering, North Carolina State University, P.O. Box 7909, Raleigh, NC 27695-7909 (United States)

    2013-07-01T23:59:59.000Z

    Over the past few decades, hybrid Monte-Carlo-Deterministic (MC-DT) techniques have been mostly focusing on the development of techniques primarily with shielding applications in mind, i.e. problems featuring a limited number of responses. This paper focuses on the application of a new hybrid MC-DT technique: the SUBSPACE method, for reactor analysis calculation. The SUBSPACE method is designed to overcome the lack of efficiency that hampers the application of MC methods in routine analysis calculations on the assembly level where typically one needs to execute the flux solver in the order of 10{sup 3}-10{sup 5} times. It places high premium on attaining high computational efficiency for reactor analysis application by identifying and capitalizing on the existing correlations between responses of interest. This paper places particular emphasis on using the SUBSPACE method for preparing homogenized few-group cross section sets on the assembly level for subsequent use in full-core diffusion calculations. A BWR assembly model is employed to calculate homogenized few-group cross sections for different burn-up steps. It is found that using the SUBSPACE method significant speedup can be achieved over the state of the art FW-CADIS method. While the presented speed-up alone is not sufficient to render the MC method competitive with the DT method, we believe this work will become a major step on the way of leveraging the accuracy of MC calculations for assembly calculations. (authors)

  4. Monte Carlo simulations for generic granite repository studies

    SciTech Connect (OSTI)

    Chu, Shaoping [Los Alamos National Laboratory; Lee, Joon H [SNL; Wang, Yifeng [SNL

    2010-12-08T23:59:59.000Z

    In a collaborative study between Los Alamos National Laboratory (LANL) and Sandia National Laboratories (SNL) for the DOE-NE Office of Fuel Cycle Technologies Used Fuel Disposition (UFD) Campaign project, we have conducted preliminary system-level analyses to support the development of a long-term strategy for geologic disposal of high-level radioactive waste. A general modeling framework consisting of a near- and a far-field submodel for a granite GDSE was developed. A representative far-field transport model for a generic granite repository was merged with an integrated systems (GoldSim) near-field model. Integrated Monte Carlo model runs with the combined near- and farfield transport models were performed, and the parameter sensitivities were evaluated for the combined system. In addition, a sub-set of radionuclides that are potentially important to repository performance were identified and evaluated for a series of model runs. The analyses were conducted with different waste inventory scenarios. Analyses were also conducted for different repository radionuelide release scenarios. While the results to date are for a generic granite repository, the work establishes the method to be used in the future to provide guidance on the development of strategy for long-term disposal of high-level radioactive waste in a granite repository.

  5. Ensemble bayesian model averaging using markov chain Monte Carlo sampling

    SciTech Connect (OSTI)

    Vrugt, Jasper A [Los Alamos National Laboratory; Diks, Cees G H [NON LANL; Clark, Martyn P [NON LANL

    2008-01-01T23:59:59.000Z

    Bayesian model averaging (BMA) has recently been proposed as a statistical method to calibrate forecast ensembles from numerical weather models. Successful implementation of BMA however, requires accurate estimates of the weights and variances of the individual competing models in the ensemble. In their seminal paper (Raftery etal. Mon Weather Rev 133: 1155-1174, 2(05)) has recommended the Expectation-Maximization (EM) algorithm for BMA model training, even though global convergence of this algorithm cannot be guaranteed. In this paper, we compare the performance of the EM algorithm and the recently developed Differential Evolution Adaptive Metropolis (DREAM) Markov Chain Monte Carlo (MCMC) algorithm for estimating the BMA weights and variances. Simulation experiments using 48-hour ensemble data of surface temperature and multi-model stream-flow forecasts show that both methods produce similar results, and that their performance is unaffected by the length of the training data set. However, MCMC simulation with DREAM is capable of efficiently handling a wide variety of BMA predictive distributions, and provides useful information about the uncertainty associated with the estimated BMA weights and variances.

  6. Monte Carlo Simulations of Cosmic Rays Hadronic Interactions

    SciTech Connect (OSTI)

    Aguayo Navarrete, Estanislao; Orrell, John L.; Kouzes, Richard T.

    2011-04-01T23:59:59.000Z

    This document describes the construction and results of the MaCoR software tool, developed to model the hadronic interactions of cosmic rays with different geometries of materials. The ubiquity of cosmic radiation in the environment results in the activation of stable isotopes, referred to as cosmogenic activities. The objective is to use this application in conjunction with a model of the MAJORANA DEMONSTRATOR components, from extraction to deployment, to evaluate cosmogenic activation of such components before and after deployment. The cosmic ray showers include several types of particles with a wide range of energy (MeV to GeV). It is infeasible to compute an exact result with a deterministic algorithm for this problem; Monte Carlo simulations are a more suitable approach to model cosmic ray hadronic interactions. In order to validate the results generated by the application, a test comparing experimental muon flux measurements and those predicted by the application is presented. The experimental and simulated results have a deviation of 3%.

  7. A review of Monte Carlo simulations of polymers with PERM

    E-Print Network [OSTI]

    Hsiao-Ping Hsu; Peter Grassberger

    2011-07-06T23:59:59.000Z

    In this review, we describe applications of the pruned-enriched Rosenbluth method (PERM), a sequential Monte Carlo algorithm with resampling, to various problems in polymer physics. PERM produces samples according to any given prescribed weight distribution, by growing configurations step by step with controlled bias, and correcting "bad" configurations by "population control". The latter is implemented, in contrast to other population based algorithms like e.g. genetic algorithms, by depth-first recursion which avoids storing all members of the population at the same time in computer memory. The problems we discuss all concern single polymers (with one exception), but under various conditions: Homopolymers in good solvents and at the $\\Theta$ point, semi-stiff polymers, polymers in confining geometries, stretched polymers undergoing a forced globule-linear transition, star polymers, bottle brushes, lattice animals as a model for randomly branched polymers, DNA melting, and finally -- as the only system at low temperatures, lattice heteropolymers as simple models for protein folding. PERM is for some of these problems the method of choice, but it can also fail. We discuss how to recognize when a result is reliable, and we discuss also some types of bias that can be crucial in guiding the growth into the right directions.

  8. Hyperon Puzzle: Hints from Quantum Monte Carlo Calculations

    E-Print Network [OSTI]

    Diego Lonardoni; Alessandro Lovato; Stefano Gandolfi; Francesco Pederiva

    2015-02-27T23:59:59.000Z

    The onset of hyperons in the core of neutron stars and the consequent softening of the equation of state have been questioned for a long time. Controversial theoretical predictions and recent astrophysical observations of neutron stars are the grounds for the so-called hyperon puzzle. We calculate the equation of state and the neutron star mass-radius relation of an infinite systems of neutrons and $\\Lambda$ particles by using the auxiliary field diffusion Monte Carlo algorithm. We find that the three-body hyperon-nucleon interaction plays a fundamental role in the softening of the equation of state and for the consequent reduction of the predicted maximum mass. We have considered two different models of three-body force that successfully describe the binding energy of medium mass hypernuclei. Our results indicate that they give dramatically different results on the maximum mass of neutron stars, not necessarily incompatible with the recent observation of very massive neutron stars. We conclude that stronger constraints on the hyperon-neutron force are necessary in order to properly assess the role of hyperons in neutron stars.

  9. Monte Carlo simulations of lattice models for single polymer systems

    SciTech Connect (OSTI)

    Hsu, Hsiao-Ping, E-mail: hsu@mpip-mainz.mpg.de [Max-Planck-Institut für Polymerforschung, Ackermannweg 10, D-55128 Mainz (Germany)

    2014-10-28T23:59:59.000Z

    Single linear polymer chains in dilute solutions under good solvent conditions are studied by Monte Carlo simulations with the pruned-enriched Rosenbluth method up to the chain length N?O(10{sup 4}). Based on the standard simple cubic lattice model (SCLM) with fixed bond length and the bond fluctuation model (BFM) with bond lengths in a range between 2 and ?(10), we investigate the conformations of polymer chains described by self-avoiding walks on the simple cubic lattice, and by random walks and non-reversible random walks in the absence of excluded volume interactions. In addition to flexible chains, we also extend our study to semiflexible chains for different stiffness controlled by a bending potential. The persistence lengths of chains extracted from the orientational correlations are estimated for all cases. We show that chains based on the BFM are more flexible than those based on the SCLM for a fixed bending energy. The microscopic differences between these two lattice models are discussed and the theoretical predictions of scaling laws given in the literature are checked and verified. Our simulations clarify that a different mapping ratio between the coarse-grained models and the atomistically realistic description of polymers is required in a coarse-graining approach due to the different crossovers to the asymptotic behavior.

  10. APR1400 LBLOCA uncertainty quantification by Monte Carlo method and comparison with Wilks' formula

    SciTech Connect (OSTI)

    Hwang, M.; Bae, S.; Chung, B. D. [Korea Atomic Energy Research Inst., 150 Dukjin-dong, Yuseong-gu, Daejeon (Korea, Republic of)

    2012-07-01T23:59:59.000Z

    An analysis of the uncertainty quantification for the PWR LBLOCA by the Monte Carlo calculation has been performed and compared with the tolerance level determined by Wilks' formula. The uncertainty range and distribution of each input parameter associated with the LBLOCA accident were determined by the PIRT results from the BEMUSE project. The Monte-Carlo method shows that the 95. percentile PCT value can be obtained reliably with a 95% confidence level using the Wilks' formula. The extra margin by the Wilks' formula over the true 95. percentile PCT by the Monte-Carlo method was rather large. Even using the 3 rd order formula, the calculated value using the Wilks' formula is nearly 100 K over the true value. It is shown that, with the ever increasing computational capability, the Monte-Carlo method is accessible for the nuclear power plant safety analysis within a realistic time frame. (authors)

  11. Adsorption characteristics of alkanes onto carbon nanotube bundles: Grand Canonical Monte Carlo simulation

    E-Print Network [OSTI]

    Maruyama, Shigeo

    Adsorption characteristics of alkanes onto carbon nanotube bundles: Grand Canonical Monte Carlo alkane adsorption and separation. Rather than remaining isolated however, nanotubes tend to bundle together, and the adsorption properties of such bundles and subsequent potential for practical alkane

  12. Annealing contour Monte Carlo algorithm for structure optimization in an off-lattice protein model

    E-Print Network [OSTI]

    Liang, Faming

    . For example, the HP model1 treats each amino acid as a point particle and restricts the model to fold of the energy landscape, so it is an excellent tool for Monte Carlo optimization. The ACMC algorithm is an accel

  13. Duo at Santa Fe's Monte del Sol Charter School takes top award...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    New Mexico Supercomputing Challenge Duo at Santa Fe's Monte del Sol Charter School takes top award in 25th New Mexico Supercomputing Challenge Meghan Hill and Katelynn James took...

  14. ATLAS Monte Carlo production Run-1 experience and readiness for Run-2 challenges

    E-Print Network [OSTI]

    Chapman, John Derek; The ATLAS collaboration; Garcia Navarro, Jose Enrique; Gwenlan, Claire; Mehlhase, Sascha; Tsulaia, Vakhtang; Vaniachine, Alexandre; Zhong, Jiahang; Pacheco Pages, Andres

    2015-01-01T23:59:59.000Z

    In this presentation we will review the ATLAS Monte Carlo production setup including the different production steps involved in full and fast detector simulation. A report on the Monte Carlo production campaigns during Run-I, Long Shutdown 1 (LS1) and status of the production for Run-2 will be presented. The presentation will include the details on various performance aspects. Important improvements in the workflow and software will be highlighted. Besides standard Monte Carlo production for data analyses at 7 and 8 TeV, the production accommodates for various specialised activities. These range from extended Monte Carlo validation, Geant4 validation, pileup simulation using zero bias data and production for various upgrade studies. The challenges of these activities will be discussed.

  15. Physics-based Predictive Time Propagation Method for Monte Carlo Coupled Depletion Simulations 

    E-Print Network [OSTI]

    Johns, Jesse Merlin

    2014-12-18T23:59:59.000Z

    Monte Carlo techniques for numerical simulation has humble beginnings during the Manhattan project. They were developed to rein in intractable problems of nuclear implosion hydrodynamics, thermonuclear reactions, and computing neutron fluxes and core...

  16. Efficient scene simulation for robust monte carlo localization using an RGB-D camera

    E-Print Network [OSTI]

    Fallon, Maurice Francis

    2013-05-14T23:59:59.000Z

    This paper presents Kinect Monte Carlo Localization (KMCL), a new method for localization in three dimensional indoor environments using RGB-D cameras, such as the Microsoft Kinect. The approach makes use of a low fidelity ...

  17. MARKOV CHAIN MONTE CARLO FOR AUTOMATED TRACKING OF GENEALOGY IN MICROSCOPY VIDEOS

    E-Print Network [OSTI]

    MARKOV CHAIN MONTE CARLO FOR AUTOMATED TRACKING OF GENEALOGY IN MICROSCOPY VIDEOS KATHLEEN CHAMPION of the nuclei in the images and their genealogies. Evan Tice '09 has already developed some code that aims

  18. Physics-based Predictive Time Propagation Method for Monte Carlo Coupled Depletion Simulations

    E-Print Network [OSTI]

    Johns, Jesse Merlin

    2014-12-18T23:59:59.000Z

    Monte Carlo techniques for numerical simulation has humble beginnings during the Manhattan project. They were developed to rein in intractable problems of nuclear implosion hydrodynamics, thermonuclear reactions, and computing neutron fluxes and core...

  19. Combining Strategies for Parallel Stochastic Approximation Monte Carlo Algorithm of Big Data

    E-Print Network [OSTI]

    Lin, Fang-Yu

    2014-10-15T23:59:59.000Z

    of iterations and is prone to get trapped into local optima. On the other hand, Stochastic Approximation in Monte Carlo algorithm (SAMC), a very sophisticated algorithm in theory and applications, can avoid getting trapped into local optima and produce more...

  20. Computational methods for efficient nuclear data management in Monte Carlo neutron transport simulations

    E-Print Network [OSTI]

    Walsh, Jonathan A. (Jonathan Alan)

    2014-01-01T23:59:59.000Z

    This thesis presents the development and analysis of computational methods for efficiently accessing and utilizing nuclear data in Monte Carlo neutron transport code simulations. Using the OpenMC code, profiling studies ...

  1. Improvements and applications of the Uniform Fission Site method in Monte Carlo

    E-Print Network [OSTI]

    Hunter, Jessica Lynn

    2014-01-01T23:59:59.000Z

    Monte Carlo methods for reactor analysis have been in development with the eventual goal of full-core analysis. To attain results with reasonable uncertainties, large computational resources are needed. Variance reduction ...

  2. Monte Carlo and thermal hydraulic coupling using low-order nonlinear diffusion acceleration

    E-Print Network [OSTI]

    Herman, Bryan R. (Bryan Robert)

    2014-01-01T23:59:59.000Z

    Monte Carlo (MC) methods for reactor analysis are most often employed as a benchmark tool for other transport and diffusion methods. In this work, we identify and resolve a few of the issues associated with using MC as a ...

  3. Fermion-dimer scattering using an impurity lattice Monte Carlo approach and the adiabatic projection method

    E-Print Network [OSTI]

    Serdar Elhatisari; Dean Lee

    2014-12-01T23:59:59.000Z

    We present lattice Monte Carlo calculations of fermion-dimer scattering in the limit of zero-range interactions using the adiabatic projection method. The adiabatic projection method uses a set of initial cluster states and Euclidean time projection to give a systematically improvable description of the low-lying scattering cluster states in a finite volume. We use L\\"uscher's finite-volume relations to determine the s-wave, p-wave, and d-wave phase shifts. For comparison, we also compute exact lattice results using Lanczos iteration and continuum results using the Skorniakov-Ter-Martirosian equation. For our Monte Carlo calculations we use a new lattice algorithm called impurity lattice Monte Carlo. This algorithm can be viewed as a hybrid technique which incorporates elements of both worldline and auxiliary-field Monte Carlo simulations.

  4. Feasibility and value of fully 3D Monte Carlo reconstruction in Single Photon Emission Computed Tomography

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Emission Computed Tomography (SPECT) images is degraded by physical effects, namely photon attenuation datasets are currently under investigation. Keywords : single photon emission computed tomography; Monte Emission Computed Tomography (SPECT), the qualitative and quantitative accuracy of images is degraded

  5. Protein folding and phylogenetic tree reconstruction using stochastic approximation Monte Carlo

    E-Print Network [OSTI]

    Cheon, Sooyoung

    2007-09-17T23:59:59.000Z

    folding problems. The numerical results indicate that it outperforms simulated annealing and conventional Monte Carlo algorithms as a stochastic optimization algorithm. We also propose one method for the use of secondary structures in protein folding...

  6. Nuclear Structure and Reactions (Quantum Monte Carlo, Lanczos Methods, Density Functional Methods), June 6 10

    E-Print Network [OSTI]

    Washington at Seattle, University of - Department of Physics, Electroweak Interaction Research Group

    Nuclear Structure and Reactions (Quantum Monte Carlo, Lanczos Methods, Density Functional Methods systems: nuclei and the unitary Fermi gas" Thursday, June 9 10:00 am Stefano Gandolfi "Ab

  7. On-the-fly Doppler broadening using multipole representation for Monte Carlo simulations on heterogeneous clusters

    E-Print Network [OSTI]

    Xu, Sheng, S.M. Massachusetts Institute of Technology

    2013-01-01T23:59:59.000Z

    In order to use Monte Carlo methods for reactor simulations beyond benchmark activities, the traditional way of preparing and using nuclear cross sections needs to be changed, since large datasets of cross sections at many ...

  8. Software Process Improvement 98, Monte Carlo, December 1998. 1 Development and Integration Issues about Software Engineering,

    E-Print Network [OSTI]

    Laporte, Claude Y.

    Software Process Improvement 98, Monte Carlo, December 1998. 1 Development and Integration Issues about Software Engineering, Systems Engineering and Project Management Processes Claude Y. Laporte software engineering, systems engineering, supporting processes and project management process over

  9. Semianalytic Monte Carlo calculation of reflected and transmitted radiance in a plane parallel atmosphere

    E-Print Network [OSTI]

    Moffitt, John Russell

    1972-01-01T23:59:59.000Z

    SEMIANALYTIC MONTE CARLO CALCULATION OF REFLECTED AND TRANSMITTED RADIANCE IN A PLANE PARALLEL ATMOSPHERE A Thesis by JOHN RUSSELL MOFFITT Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement... for the degree of MASTER OF SCIENCE August 1972 Major Subject: Physics SEMIANALYTIC MONTE CARLO CALCULATION OF REFLECTED AND TRANSMITTED RADIANCE IN A PLANE PARALLEL ATMOSPHERE A Thesis by JOHN RUSSELL MOFFITT Approved as to style and content by: (Cha...

  10. PyMercury: Interactive Python for the Mercury Monte Carlo Particle Transport Code

    SciTech Connect (OSTI)

    Iandola, F N; O'Brien, M J; Procassini, R J

    2010-11-29T23:59:59.000Z

    Monte Carlo particle transport applications are often written in low-level languages (C/C++) for optimal performance on clusters and supercomputers. However, this development approach often sacrifices straightforward usability and testing in the interest of fast application performance. To improve usability, some high-performance computing applications employ mixed-language programming with high-level and low-level languages. In this study, we consider the benefits of incorporating an interactive Python interface into a Monte Carlo application. With PyMercury, a new Python extension to the Mercury general-purpose Monte Carlo particle transport code, we improve application usability without diminishing performance. In two case studies, we illustrate how PyMercury improves usability and simplifies testing and validation in a Monte Carlo application. In short, PyMercury demonstrates the value of interactive Python for Monte Carlo particle transport applications. In the future, we expect interactive Python to play an increasingly significant role in Monte Carlo usage and testing.

  11. Novel Hybrid Monte Carlo/Deterministic Technique for Shutdown Dose Rate Analyses of Fusion Energy Systems

    SciTech Connect (OSTI)

    Ibrahim, Ahmad M [ORNL] [ORNL; Peplow, Douglas E. [ORNL] [ORNL; Peterson, Joshua L [ORNL] [ORNL; Grove, Robert E [ORNL] [ORNL

    2013-01-01T23:59:59.000Z

    The rigorous 2-step (R2S) method uses three-dimensional Monte Carlo transport simulations to calculate the shutdown dose rate (SDDR) in fusion reactors. Accurate full-scale R2S calculations are impractical in fusion reactors because they require calculating space- and energy-dependent neutron fluxes everywhere inside the reactor. The use of global Monte Carlo variance reduction techniques was suggested for accelerating the neutron transport calculation of the R2S method. The prohibitive computational costs of these approaches, which increase with the problem size and amount of shielding materials, inhibit their use in the accurate full-scale neutronics analyses of fusion reactors. This paper describes a novel hybrid Monte Carlo/deterministic technique that uses the Consistent Adjoint Driven Importance Sampling (CADIS) methodology but focuses on multi-step shielding calculations. The Multi-Step CADIS (MS-CADIS) method speeds up the Monte Carlo neutron calculation of the R2S method using an importance function that represents the importance of the neutrons to the final SDDR. Using a simplified example, preliminarily results showed that the use of MS-CADIS enhanced the efficiency of the neutron Monte Carlo simulation of an SDDR calculation by a factor of 550 compared to standard global variance reduction techniques, and that the increase over analog Monte Carlo is higher than 10,000.

  12. Utility of Monte Carlo Modelling for Holdup Measurements.

    SciTech Connect (OSTI)

    Belian, Anthony P.; Russo, P. A. (Phyllis A.); Weier, Dennis R. (Dennis Ray),

    2005-01-01T23:59:59.000Z

    Non-destructive assay (NDA) measurements performed to locate and quantify holdup in the Oak Ridge K25 enrichment cascade used neutron totals counting and low-resolution gamma-ray spectroscopy. This facility housed the gaseous diffusion process for enrichment of uranium, in the form of UF{sub 6} gas, from {approx} 20% to 93%. Inventory of {sup 235}U inventory in K-25 is all holdup. These buildings have been slated for decontaminatino and decommissioning. The NDA measurements establish the inventory quantities and will be used to assure criticality safety and meet criteria for waste analysis and transportation. The tendency to err on the side of conservatism for the sake of criticality safety in specifying total NDA uncertainty argues, in the interests of safety and costs, for obtaining the best possible value of uncertainty at the conservative confidence level for each item of process equipment. Variable deposit distribution is a complex systematic effect (i.e., determined by multiple independent variables) on the portable NDA results for very large and bulk converters that contributes greatly to total uncertainty for holdup in converters measured by gamma or neutron NDA methods. Because the magnitudes of complex systematic effects are difficult to estimate, computational tools are important for evaluating those that are large. Motivated by very large discrepancies between gamma and neutron measurements of high-mass converters with gamma results tending to dominate, the Monte Carlo code MCNP has been used to determine the systematic effects of deposit distribution on gamma and neutron results for {sup 235}U holdup mass in converters. This paper details the numerical methodology used to evaluate large systematic effects unique to each measurement type, validates the methodology by comparison with measurements, and discusses how modeling tools can supplement the calibration of instruments used for holdup measurements by providing realistic values at well-defined confidence levels for dominating systematic effects.

  13. Review of Monte Carlo simulations for backgrounds from radioactivity

    SciTech Connect (OSTI)

    Selvi, Marco [INFN - Sezione di Bologna (Italy)] [INFN - Sezione di Bologna (Italy)

    2013-08-08T23:59:59.000Z

    For all experiments dealing with the rare event searches (neutrino, dark matter, neutrino-less double-beta decay), the reduction of the radioactive background is one of the most important and difficult tasks. There are basically two types of background, electron recoils and nuclear recoils. The electron recoil background is mostly from the gamma rays through the radioactive decay. The nuclear recoil background is from neutrons from spontaneous fission, (?, n) reactions and muoninduced interactions (spallations, photo-nuclear and hadronic interaction). The external gammas and neutrons from the muons and laboratory environment, can be reduced by operating the detector at deep underground laboratories and by placing active or passive shield materials around the detector. The radioactivity of the detector materials also contributes to the background; in order to reduce it a careful screening campaign is mandatory to select highly radio-pure materials. In this review I present the status of current Monte Carlo simulations aimed to estimate and reproduce the background induced by gamma and neutron radioactivity of the materials and the shield of rare event search experiment. For the electromagnetic background a good level of agreement between the data and the MC simulation has been reached by the XENON100 and EDELWEISS experiments, using the GEANT4 toolkit. For the neutron background, a comparison between the yield of neutrons from spontaneous fission and (?, n) obtained with two dedicated softwares, SOURCES-4A and the one developed by Mei-Zhang-Hime, show a good overall agreement, with total yields within a factor 2 difference. The energy spectra from SOURCES-4A are in general smoother, while those from MZH presents sharp peaks. The neutron propagation through various materials has been studied with two MC codes, GEANT4 and MCNPX, showing a reasonably good agreement, inside 50% discrepancy.

  14. Arginine metabolism in enterocytes of diabetic rats

    E-Print Network [OSTI]

    Morrow, Natalie Anne

    2002-01-01T23:59:59.000Z

    Diabetic rats and patients exhibit decreased plasma arginine concentrations. Arginine is important in numerous cellular pathways, including the synthesis of nitric oxide and the release of insulin from pancreatic ? cells. At present, little...

  15. Purification of sulfide oxidase from rat liver

    E-Print Network [OSTI]

    Pu, Lixia

    1994-01-01T23:59:59.000Z

    The present study represents an initial investigative effort to purify sulfide oxidase from rat liver. Two methods to determine sulfide oxidase activity have been established and both are based on measuring substrate disappearance of sulfide. Both...

  16. THE BEHAVIOR OF THE LABORATORY RAT

    E-Print Network [OSTI]

    Galef Jr., Bennett G.

    , Alaska, at 60 degrees North latitude, where rats feed on human garbage, to South Georgia Island, at 55 members that had survived their ini- tial contact with the poisoned bait and had learned to avoid eating

  17. Final Report: 06-LW-013, Nuclear Physics the Monte Carlo Way

    SciTech Connect (OSTI)

    Ormand, W E

    2009-03-01T23:59:59.000Z

    This is document reports the progress and accomplishments achieved in 2006-2007 with LDRD funding under the proposal 06-LW-013, 'Nuclear Physics the Monte Carlo Way'. The project was a theoretical study to explore a novel approach to dealing with a persistent problem in Monte Carlo approaches to quantum many-body systems. The goal was to implement a solution to the notorious 'sign-problem', which if successful, would permit, for the first time, exact solutions to quantum many-body systems that cannot be addressed with other methods. In this document, we outline the progress and accomplishments achieved during FY2006-2007 with LDRD funding in the proposal 06-LW-013, 'Nuclear Physics the Monte Carlo Way'. This project was funded under the Lab Wide LDRD competition at Lawrence Livermore National Laboratory. The primary objective of this project was to test the feasibility of implementing a novel approach to solving the generic quantum many-body problem, which is one of the most important problems being addressed in theoretical physics today. Instead of traditional methods based matrix diagonalization, this proposal focused a Monte Carlo method. The principal difficulty with Monte Carlo methods, is the so-called 'sign problem'. The sign problem, which will discussed in some detail later, is endemic to Monte Carlo approaches to the quantum many-body problem, and is the principal reason that they have not been completely successful in the past. Here, we outline our research in the 'shifted-contour method' applied the Auxiliary Field Monte Carlo (AFMC) method.

  18. A Fano cavity test for Monte Carlo proton transport algorithms

    SciTech Connect (OSTI)

    Sterpin, Edmond, E-mail: esterpin@yahoo.fr [Université catholique de Louvain, Center of Molecular Imaging, Radiotherapy and Oncology, Institut de Recherche Experimentale et Clinique, Avenue Hippocrate 54, 1200 Brussels (Belgium)] [Université catholique de Louvain, Center of Molecular Imaging, Radiotherapy and Oncology, Institut de Recherche Experimentale et Clinique, Avenue Hippocrate 54, 1200 Brussels (Belgium); Sorriaux, Jefferson; Souris, Kevin [Université catholique de Louvain, Center of Molecular Imaging, Radiotherapy and Oncology, Institut de Recherche Experimentale et Clinique, Avenue Hippocrate 54, 1200 Brussels, Belgium and Université catholique de Louvain, ICTEAM institute, Chemin du cyclotron 6, 1348 Louvain-la-Neuve (Belgium)] [Université catholique de Louvain, Center of Molecular Imaging, Radiotherapy and Oncology, Institut de Recherche Experimentale et Clinique, Avenue Hippocrate 54, 1200 Brussels, Belgium and Université catholique de Louvain, ICTEAM institute, Chemin du cyclotron 6, 1348 Louvain-la-Neuve (Belgium); Vynckier, Stefaan [Université catholique de Louvain, Center of Molecular Imaging, Radiotherapy and Oncology, Institut de Recherche Experimentale et Clinique, Avenue Hippocrate 54, 1200 Brussels, Belgium and Département de Radiothérapie, Cliniques Universitaires Saint-Luc, Avenue Hippocrate 54, 1200 Brussels (Belgium)] [Université catholique de Louvain, Center of Molecular Imaging, Radiotherapy and Oncology, Institut de Recherche Experimentale et Clinique, Avenue Hippocrate 54, 1200 Brussels, Belgium and Département de Radiothérapie, Cliniques Universitaires Saint-Luc, Avenue Hippocrate 54, 1200 Brussels (Belgium); Bouchard, Hugo [Département de radio-oncologie, Centre hospitalier de l’Université de Montréal (CHUM), 1560 Sherbrooke est, Montréal, Québec H2L 4M1 (Canada)] [Département de radio-oncologie, Centre hospitalier de l’Université de Montréal (CHUM), 1560 Sherbrooke est, Montréal, Québec H2L 4M1 (Canada)

    2014-01-15T23:59:59.000Z

    Purpose: In the scope of reference dosimetry of radiotherapy beams, Monte Carlo (MC) simulations are widely used to compute ionization chamber dose response accurately. Uncertainties related to the transport algorithm can be verified performing self-consistency tests, i.e., the so-called “Fano cavity test.” The Fano cavity test is based on the Fano theorem, which states that under charged particle equilibrium conditions, the charged particle fluence is independent of the mass density of the media as long as the cross-sections are uniform. Such tests have not been performed yet for MC codes simulating proton transport. The objectives of this study are to design a new Fano cavity test for proton MC and to implement the methodology in two MC codes: Geant4 and PENELOPE extended to protons (PENH). Methods: The new Fano test is designed to evaluate the accuracy of proton transport. Virtual particles with an energy ofE{sub 0} and a mass macroscopic cross section of (?)/(?) are transported, having the ability to generate protons with kinetic energy E{sub 0} and to be restored after each interaction, thus providing proton equilibrium. To perform the test, the authors use a simplified simulation model and rigorously demonstrate that the computed cavity dose per incident fluence must equal (?E{sub 0})/(?) , as expected in classic Fano tests. The implementation of the test is performed in Geant4 and PENH. The geometry used for testing is a 10 × 10 cm{sup 2} parallel virtual field and a cavity (2 × 2 × 0.2 cm{sup 3} size) in a water phantom with dimensions large enough to ensure proton equilibrium. Results: For conservative user-defined simulation parameters (leading to small step sizes), both Geant4 and PENH pass the Fano cavity test within 0.1%. However, differences of 0.6% and 0.7% were observed for PENH and Geant4, respectively, using larger step sizes. For PENH, the difference is attributed to the random-hinge method that introduces an artificial energy straggling if step size is not small enough. Conclusions: Using conservative user-defined simulation parameters, both PENH and Geant4 pass the Fano cavity test for proton transport. Our methodology is applicable to any kind of charged particle, provided that the considered MC code is able to track the charged particle considered.

  19. Mthodes de Monte Carlo et processus stochastiques Pierre Del Moral -Stefano De Marco -Massimiliano Gubinelli -Benjamin Jourdain

    E-Print Network [OSTI]

    Del Moral , Pierre

    Méthodes de Monte Carlo et processus stochastiques Pierre Del Moral - Stefano De Marco Monte Carlo et processus stochastiques: du linéaire au non linéaire (E. Gobet). On considère un système Méthodes de Monte Carlo et processus stochastiques: du linéaire au non linéaire (E. Gobet). On considère

  20. Mthodes de Monte Carlo et processus stochastiques Pierre Del Moral -Stefano De Marco -Massimiliano Gubinelli -Benjamin Jourdain

    E-Print Network [OSTI]

    Del Moral , Pierre

    Méthodes de Monte Carlo et processus stochastiques Pierre Del Moral - Stefano De Marco de refaire l'une des expériences de simulation de Monte Carlo les plus anciennes, proposée en 1733 aiguille touche le bord d'une latte. 1. Méthode de Monte Carlo : Vérifier numériquement que la probabilité

  1. timid, or easily manipulated. This is not compassion. A marine drill ser-geant may be demanding and results-driven, but can show compassion

    E-Print Network [OSTI]

    Kim, Duck O.

    are outside of EAP practice. EAPs owning responsibility for such decisions can lower program utilizationtimid, or easily manipulated. This is not compassion. A marine drill ser- geant may be demanding and what they think is best or customary for the work organiza- tion. It is appropriate to discuss general

  2. Fission matrix-based Monte Carlo criticality analysis of fuel storage pools

    SciTech Connect (OSTI)

    Farlotti, M. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Ecole Polytechnique, Palaiseau, F 91128 (France); Larsen, E. W. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States)

    2013-07-01T23:59:59.000Z

    Standard Monte Carlo transport procedures experience difficulties in solving criticality problems in fuel storage pools. Because of the strong neutron absorption between fuel assemblies, source convergence can be very slow, leading to incorrect estimates of the eigenvalue and the eigenfunction. This study examines an alternative fission matrix-based Monte Carlo transport method that takes advantage of the geometry of a storage pool to overcome this difficulty. The method uses Monte Carlo transport to build (essentially) a fission matrix, which is then used to calculate the criticality and the critical flux. This method was tested using a test code on a simple problem containing 8 assemblies in a square pool. The standard Monte Carlo method gave the expected eigenfunction in 5 cases out of 10, while the fission matrix method gave the expected eigenfunction in all 10 cases. In addition, the fission matrix method provides an estimate of the error in the eigenvalue and the eigenfunction, and it allows the user to control this error by running an adequate number of cycles. Because of these advantages, the fission matrix method yields a higher confidence in the results than standard Monte Carlo. We also discuss potential improvements of the method, including the potential for variance reduction techniques. (authors)

  3. General purpose dynamic Monte Carlo with continuous energy for transient analysis

    SciTech Connect (OSTI)

    Sjenitzer, B. L.; Hoogenboom, J. E. [Delft Univ. of Technology, Dept. of Radiation, Radionuclide and Reactors, Mekelweg 15, 2629JB Delft (Netherlands)

    2012-07-01T23:59:59.000Z

    For safety assessments transient analysis is an important tool. It can predict maximum temperatures during regular reactor operation or during an accident scenario. Despite the fact that this kind of analysis is very important, the state of the art still uses rather crude methods, like diffusion theory and point-kinetics. For reference calculations it is preferable to use the Monte Carlo method. In this paper the dynamic Monte Carlo method is implemented in the general purpose Monte Carlo code Tripoli4. Also, the method is extended for use with continuous energy. The first results of Dynamic Tripoli demonstrate that this kind of calculation is indeed accurate and the results are achieved in a reasonable amount of time. With the method implemented in Tripoli it is now possible to do an exact transient calculation in arbitrary geometry. (authors)

  4. Revised methods for few-group cross sections generation in the Serpent Monte Carlo code

    SciTech Connect (OSTI)

    Fridman, E. [Reactor Safety Div., Helmholz-Zentrum Dresden-Rossendorf, POB 51 01 19, Dresden, 01314 (Germany); Leppaenen, J. [VTT Technical Research Centre of Finland, POB 1000, FI-02044 VTT (Finland)

    2012-07-01T23:59:59.000Z

    This paper presents new calculation methods, recently implemented in the Serpent Monte Carlo code, and related to the production of homogenized few-group constants for deterministic 3D core analysis. The new methods fall under three topics: 1) Improved treatment of neutron-multiplying scattering reactions, 2) Group constant generation in reflectors and other non-fissile regions and 3) Homogenization in leakage-corrected criticality spectrum. The methodology is demonstrated by a numerical example, comparing a deterministic nodal diffusion calculation using Serpent-generated cross sections to a reference full-core Monte Carlo simulation. It is concluded that the new methodology improves the results of the deterministic calculation, and paves the way for Monte Carlo based group constant generation. (authors)

  5. A Proposal for a Standard Interface Between Monte Carlo Tools And One-Loop Programs

    SciTech Connect (OSTI)

    Binoth, T.; /Edinburgh U.; Boudjema, F.; /Annecy, LAPP; Dissertori, G.; Lazopoulos, A.; /Zurich, ETH; Denner, A.; /PSI, Villigen; Dittmaier, S.; /Freiburg U.; Frederix, R.; Greiner, N.; Hoeche, Stefan; /Zurich U.; Giele, W.; Skands, P.; Winter, J.; /Fermilab; Gleisberg, T.; /SLAC; Archibald, J.; Heinrich, G.; Krauss, F.; Maitre, D.; /Durham U., IPPP; Huber, M.; /Munich, Max Planck Inst.; Huston, J.; /Michigan State U.; Kauer, N.; /Royal Holloway, U. of London; Maltoni, F.; /Louvain U., CP3 /Milan Bicocca U. /INFN, Turin /Turin U. /Granada U., Theor. Phys. Astrophys. /CERN /NIKHEF, Amsterdam /Heidelberg U. /Oxford U., Theor. Phys.

    2011-11-11T23:59:59.000Z

    Many highly developed Monte Carlo tools for the evaluation of cross sections based on tree matrix elements exist and are used by experimental collaborations in high energy physics. As the evaluation of one-loop matrix elements has recently been undergoing enormous progress, the combination of one-loop matrix elements with existing Monte Carlo tools is on the horizon. This would lead to phenomenological predictions at the next-to-leading order level. This note summarises the discussion of the next-to-leading order multi-leg (NLM) working group on this issue which has been taking place during the workshop on Physics at TeV Colliders at Les Houches, France, in June 2009. The result is a proposal for a standard interface between Monte Carlo tools and one-loop matrix element programs.

  6. Full 3D visualization tool-kit for Monte Carlo and deterministic transport codes

    SciTech Connect (OSTI)

    Frambati, S.; Frignani, M. [Ansaldo Nucleare S.p.A., Corso F.M. Perrone 25, 1616 Genova (Italy)

    2012-07-01T23:59:59.000Z

    We propose a package of tools capable of translating the geometric inputs and outputs of many Monte Carlo and deterministic radiation transport codes into open source file formats. These tools are aimed at bridging the gap between trusted, widely-used radiation analysis codes and very powerful, more recent and commonly used visualization software, thus supporting the design process and helping with shielding optimization. Three main lines of development were followed: mesh-based analysis of Monte Carlo codes, mesh-based analysis of deterministic codes and Monte Carlo surface meshing. The developed kit is considered a powerful and cost-effective tool in the computer-aided design for radiation transport code users of the nuclear world, and in particular in the fields of core design and radiation analysis. (authors)

  7. Data decomposition of Monte Carlo particle transport simulations via tally servers

    SciTech Connect (OSTI)

    Romano, Paul K., E-mail: paul.k.romano@gmail.com [Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 77 Massachusetts Ave., Cambridge, MA 02139 (United States); Siegel, Andrew R., E-mail: siegala@mcs.anl.gov [Argonne National Laboratory, Theory and Computing Sciences, 9700 S Cass Ave., Argonne, IL 60439 (United States); Forget, Benoit, E-mail: bforget@mit.edu [Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 77 Massachusetts Ave., Cambridge, MA 02139 (United States)] [Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 77 Massachusetts Ave., Cambridge, MA 02139 (United States); Smith, Kord, E-mail: kord@mit.edu [Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 77 Massachusetts Ave., Cambridge, MA 02139 (United States)] [Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 77 Massachusetts Ave., Cambridge, MA 02139 (United States)

    2013-11-01T23:59:59.000Z

    An algorithm for decomposing large tally data in Monte Carlo particle transport simulations is developed, analyzed, and implemented in a continuous-energy Monte Carlo code, OpenMC. The algorithm is based on a non-overlapping decomposition of compute nodes into tracking processors and tally servers. The former are used to simulate the movement of particles through the domain while the latter continuously receive and update tally data. A performance model for this approach is developed, suggesting that, for a range of parameters relevant to LWR analysis, the tally server algorithm should perform with minimal overhead on contemporary supercomputers. An implementation of the algorithm in OpenMC is then tested on the Intrepid and Titan supercomputers, supporting the key predictions of the model over a wide range of parameters. We thus conclude that the tally server algorithm is a successful approach to circumventing classical on-node memory constraints en route to unprecedentedly detailed Monte Carlo reactor simulations.

  8. Calculation of radiation therapy dose using all particle Monte Carlo transport

    DOE Patents [OSTI]

    Chandler, William P. (Tracy, CA); Hartmann-Siantar, Christine L. (San Ramon, CA); Rathkopf, James A. (Livermore, CA)

    1999-01-01T23:59:59.000Z

    The actual radiation dose absorbed in the body is calculated using three-dimensional Monte Carlo transport. Neutrons, protons, deuterons, tritons, helium-3, alpha particles, photons, electrons, and positrons are transported in a completely coupled manner, using this Monte Carlo All-Particle Method (MCAPM). The major elements of the invention include: computer hardware, user description of the patient, description of the radiation source, physical databases, Monte Carlo transport, and output of dose distributions. This facilitated the estimation of dose distributions on a Cartesian grid for neutrons, photons, electrons, positrons, and heavy charged-particles incident on any biological target, with resolutions ranging from microns to centimeters. Calculations can be extended to estimate dose distributions on general-geometry (non-Cartesian) grids for biological and/or non-biological media.

  9. Calculation of radiation therapy dose using all particle Monte Carlo transport

    DOE Patents [OSTI]

    Chandler, W.P.; Hartmann-Siantar, C.L.; Rathkopf, J.A.

    1999-02-09T23:59:59.000Z

    The actual radiation dose absorbed in the body is calculated using three-dimensional Monte Carlo transport. Neutrons, protons, deuterons, tritons, helium-3, alpha particles, photons, electrons, and positrons are transported in a completely coupled manner, using this Monte Carlo All-Particle Method (MCAPM). The major elements of the invention include: computer hardware, user description of the patient, description of the radiation source, physical databases, Monte Carlo transport, and output of dose distributions. This facilitated the estimation of dose distributions on a Cartesian grid for neutrons, photons, electrons, positrons, and heavy charged-particles incident on any biological target, with resolutions ranging from microns to centimeters. Calculations can be extended to estimate dose distributions on general-geometry (non-Cartesian) grids for biological and/or non-biological media. 57 figs.

  10. Crossing the mesoscale no-mans land via parallel kinetic Monte Carlo.

    SciTech Connect (OSTI)

    Garcia Cardona, Cristina (San Diego State University); Webb, Edmund Blackburn, III; Wagner, Gregory John; Tikare, Veena; Holm, Elizabeth Ann; Plimpton, Steven James; Thompson, Aidan Patrick; Slepoy, Alexander (U. S. Department of Energy, NNSA); Zhou, Xiao Wang; Battaile, Corbett Chandler; Chandross, Michael Evan

    2009-10-01T23:59:59.000Z

    The kinetic Monte Carlo method and its variants are powerful tools for modeling materials at the mesoscale, meaning at length and time scales in between the atomic and continuum. We have completed a 3 year LDRD project with the goal of developing a parallel kinetic Monte Carlo capability and applying it to materials modeling problems of interest to Sandia. In this report we give an overview of the methods and algorithms developed, and describe our new open-source code called SPPARKS, for Stochastic Parallel PARticle Kinetic Simulator. We also highlight the development of several Monte Carlo models in SPPARKS for specific materials modeling applications, including grain growth, bubble formation, diffusion in nanoporous materials, defect formation in erbium hydrides, and surface growth and evolution.

  11. Cardiopulmonary Function in RatsWith Lung Hemorrhage

    E-Print Network [OSTI]

    Illinois at Urbana-Champaign, University of

    Cardiopulmonary Function in RatsWith Lung Hemorrhage Induced by Pulsed Ultrasound Exposure Jeffery using superthreshold exposure conditions known to produce sig- nificant lung hemorrhage. Methods. In 1 in the left lung of each rat. In a second group of 6 rats, 5 foci of ultrasound-induced hemorrhage were

  12. Advanced Mesh-Enabled Monte carlo capability for Multi-Physics Reactor Analysis

    SciTech Connect (OSTI)

    Wilson, Paul; Evans, Thomas; Tautges, Tim

    2012-12-24T23:59:59.000Z

    This project will accumulate high-precision fluxes throughout reactor geometry on a non- orthogonal grid of cells to support multi-physics coupling, in order to more accurately calculate parameters such as reactivity coefficients and to generate multi-group cross sections. This work will be based upon recent developments to incorporate advanced geometry and mesh capability in a modular Monte Carlo toolkit with computational science technology that is in use in related reactor simulation software development. Coupling this capability with production-scale Monte Carlo radiation transport codes can provide advanced and extensible test-beds for these developments. Continuous energy Monte Carlo methods are generally considered to be the most accurate computational tool for simulating radiation transport in complex geometries, particularly neutron transport in reactors. Nevertheless, there are several limitations for their use in reactor analysis. Most significantly, there is a trade-off between the fidelity of results in phase space, statistical accuracy, and the amount of computer time required for simulation. Consequently, to achieve an acceptable level of statistical convergence in high-fidelity results required for modern coupled multi-physics analysis, the required computer time makes Monte Carlo methods prohibitive for design iterations and detailed whole-core analysis. More subtly, the statistical uncertainty is typically not uniform throughout the domain, and the simulation quality is limited by the regions with the largest statistical uncertainty. In addition, the formulation of neutron scattering laws in continuous energy Monte Carlo methods makes it difficult to calculate adjoint neutron fluxes required to properly determine important reactivity parameters. Finally, most Monte Carlo codes available for reactor analysis have relied on orthogonal hexahedral grids for tallies that do not conform to the geometric boundaries and are thus generally not well-suited to coupling with the unstructured meshes that are used in other physics simulations.

  13. Calculating kinetics parameters and reactivity changes with continuous-energy Monte Carlo

    SciTech Connect (OSTI)

    Kiedrowski, Brian C [Los Alamos National Laboratory; Brown, Forrest B [Los Alamos National Laboratory; Wilson, Paul [UNIV. WISCONSIN

    2009-01-01T23:59:59.000Z

    The iterated fission probability interpretation of the adjoint flux forms the basis for a method to perform adjoint weighting of tally scores in continuous-energy Monte Carlo k-eigenvalue calculations. Applying this approach, adjoint-weighted tallies are developed for two applications: calculating point reactor kinetics parameters and estimating changes in reactivity from perturbations. Calculations are performed in the widely-used production code, MCNP, and the results of both applications are compared with discrete ordinates calculations, experimental measurements, and other Monte Carlo calculations.

  14. FREYA-a new Monte Carlo code for improved modeling of fission chains

    SciTech Connect (OSTI)

    Hagmann, C A; Randrup, J; Vogt, R L

    2012-06-12T23:59:59.000Z

    A new simulation capability for modeling of individual fission events and chains and the transport of fission products in materials is presented. FREYA ( Fission Yield Event Yield Algorithm ) is a Monte Carlo code for generating fission events providing correlated kinematic information for prompt neutrons, gammas, and fragments. As a standalone code, FREYA calculates quantities such as multiplicity-energy, angular, and gamma-neutron energy sharing correlations. To study materials with multiplication, shielding effects, and detectors, we have integrated FREYA into the general purpose Monte Carlo code MCNP. This new tool will allow more accurate modeling of detector responses including correlations and the development of SNM detectors with increased sensitivity.

  15. Pseudo-random number generators for Monte Carlo simulations on Graphics Processing Units

    E-Print Network [OSTI]

    Vadim Demchik

    2010-03-09T23:59:59.000Z

    Basic uniform pseudo-random number generators are implemented on ATI Graphics Processing Units (GPU). The performance results of the realized generators (multiplicative linear congruential (GGL), XOR-shift (XOR128), RANECU, RANMAR, RANLUX and Mersenne Twister (MT19937)) on CPU and GPU are discussed. The obtained speed-up factor is hundreds of times in comparison with CPU. RANLUX generator is found to be the most appropriate for using on GPU in Monte Carlo simulations. The brief review of the pseudo-random number generators used in modern software packages for Monte Carlo simulations in high-energy physics is present.

  16. A Monte Carlo synthetic-acceleration method for solving the thermal radiation diffusion equation

    SciTech Connect (OSTI)

    Evans, Thomas M., E-mail: evanstm@ornl.gov [Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, TN 37831 (United States); Mosher, Scott W., E-mail: moshersw@ornl.gov [Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, TN 37831 (United States); Slattery, Stuart R., E-mail: sslattery@wisc.edu [University of Wisconsin–Madison, 1500 Engineering Dr., Madison, WI 53716 (United States); Hamilton, Steven P., E-mail: hamiltonsp@ornl.gov [Oak Ridge National Laboratory, 1 Bethel Valley Rd., Oak Ridge, TN 37831 (United States)

    2014-02-01T23:59:59.000Z

    We present a novel synthetic-acceleration-based Monte Carlo method for solving the equilibrium thermal radiation diffusion equation in three spatial dimensions. The algorithm performance is compared against traditional solution techniques using a Marshak benchmark problem and a more complex multiple material problem. Our results show that our Monte Carlo method is an effective solver for sparse matrix systems. For solutions converged to the same tolerance, it performs competitively with deterministic methods including preconditioned conjugate gradient and GMRES. We also discuss various aspects of preconditioning the method and its general applicability to broader classes of problems.

  17. A Monte Carlo Synthetic-Acceleration Method for Solving the Thermal Radiation Diffusion Equation

    SciTech Connect (OSTI)

    Evans, Thomas M [ORNL] [ORNL; Mosher, Scott W [ORNL] [ORNL; Slattery, Stuart [University of Wisconsin, Madison] [University of Wisconsin, Madison

    2014-01-01T23:59:59.000Z

    We present a novel synthetic-acceleration based Monte Carlo method for solving the equilibrium thermal radiation diusion equation in three dimensions. The algorithm performance is compared against traditional solution techniques using a Marshak benchmark problem and a more complex multiple material problem. Our results show that not only can our Monte Carlo method be an eective solver for sparse matrix systems, but also that it performs competitively with deterministic methods including preconditioned Conjugate Gradient while producing numerically identical results. We also discuss various aspects of preconditioning the method and its general applicability to broader classes of problems.

  18. Matching NLO QCD with parton shower in Monte Carlo scheme - the KrkNLO method

    E-Print Network [OSTI]

    S. Jadach; W. Placzek; S. Sapeta; A. Siodmok; M. Skrzypek

    2015-05-11T23:59:59.000Z

    A new method of including the complete NLO QCD corrections to hard processes in the LO parton-shower Monte Carlo (PSMC) is presented. This method, called KrkNLO, requires the use of parton distribution functions in a dedicated Monte Carlo factorization scheme, which is also discussed in this paper. In the future, it may simplify introduction of the NNLO corrections to hard processes and the NLO corrections to PSMC. Details of the method and numerical examples of its practical implementation, as well as comparisons with other calculations, such as MCFM, MC@NLO, POWHEG, for single $Z/\\gamma^*$-boson production at the LHC, are presented.

  19. Monte Carlo simulations of the HP model (the "Ising model" of protein folding)

    E-Print Network [OSTI]

    Li, Ying Wai; Landau, David P; 10.1016/j.cpc.2010.12.049

    2011-01-01T23:59:59.000Z

    Using Wang-Landau sampling with suitable Monte Carlo trial moves (pull moves and bond-rebridging moves combined) we have determined the density of states and thermodynamic properties for a short sequence of the HP protein model. For free chains these proteins are known to first undergo a collapse "transition" to a globule state followed by a second "transition" into a native state. When placed in the proximity of an attractive surface, there is a competition between surface adsorption and folding that leads to an intriguing sequence of "transitions". These transitions depend upon the relative interaction strengths and are largely inaccessible to "standard" Monte Carlo methods.

  20. An Advanced Neutronic Analysis Toolkit with Inline Monte Carlo capability for BHTR Analysis

    SciTech Connect (OSTI)

    William R. Martin; John C. Lee

    2009-12-30T23:59:59.000Z

    Monte Carlo capability has been combined with a production LWR lattice physics code to allow analysis of high temperature gas reactor configurations, accounting for the double heterogeneity due to the TRISO fuel. The Monte Carlo code MCNP5 has been used in conjunction with CPM3, which was the testbench lattice physics code for this project. MCNP5 is used to perform two calculations for the geometry of interest, one with homogenized fuel compacts and the other with heterogeneous fuel compacts, where the TRISO fuel kernels are resolved by MCNP5.

  1. Application of collision-based two dimensional Monte Carlo method in a simulated microscale ground water model

    E-Print Network [OSTI]

    Chung, Kiwhan

    1996-01-01T23:59:59.000Z

    While the use of Monte Carlo method has been prevalent in nuclear engineering, it has yet to fully blossom in the study of solute transport in porous media. By using an etched-glass micromodel, an attempt is made to apply Monte Carlo method...

  2. Emplacement in an extensional setting of the Mont LozreBorne granitic complex (SE France) inferred from

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Emplacement in an extensional setting of the Mont Lozère­Borne granitic complex (SE France of the Late Hercynian Mont Lozère­Borne granitic complex (French Massif Central), which consists of several carried out to characterize the internal fabrics of the granitic plutons. Throughout the Pont

  3. Feeding Ecology of 0-Group Sea Bass, Dicentrarchus labrax, in Salt Marshes of Mont Saint Michel Bay (France)

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    bass Dicentrarchus labrax is among the most abundant and exploited fish species of Eu- ropean coastsFeeding Ecology of 0-Group Sea Bass, Dicentrarchus labrax, in Salt Marshes of Mont Saint Michel Bay, France ABSTRACT: 0-group sea bass, Dicentrarchus labrax, colonize intertidal marsh creeks of Mont Saint

  4. Quantum Monte Carlo calculations of the energy-level alignment at hybrid interfaces: Role of many-body effects

    E-Print Network [OSTI]

    Wu, Zhigang

    Quantum Monte Carlo calculations of the energy-level alignment at hybrid interfaces: Role of many; published 29 May 2009 An approach is presented for obtaining a highly accurate description of the energy-level alignment at hybrid interfaces, using quantum Monte Carlo calculations to include many-body effects

  5. Direct Monte Carlo simulation of chemical reaction systems: Internal energy transfer and an energy-dependent unimolecular reaction

    E-Print Network [OSTI]

    Anderson, James B.

    Direct Monte Carlo simulation of chemical reaction systems: Internal energy transfer and an energy a direct Monte Carlo simulation of an energy-dependent t&molecular reaction system of the type A+ B simulation of a unimo- lecular reaction with an energy-dependent rate constant k3 and with explicit treatment

  6. Methodes de Monte Carlo et processus stochastiques. Pierre Del Moral Stefano De Marco Massimiliano Gubinelli Benjamin Jourdain

    E-Print Network [OSTI]

    Del Moral , Pierre

    M´ethodes de Monte Carlo et processus stochastiques. Pierre Del Moral ­ Stefano De Marco la m´ethode de Monte Carlo multi-niveaux. L'´equation diff´erentielle stochastique de Black-Scholes d

  7. Kinetic Monte Carlo Simulation of Surface Heterogeneity in Graphite Anodes for Lithium-Ion Batteries: Passive Layer

    E-Print Network [OSTI]

    Subramanian, Venkat

    Kinetic Monte Carlo Simulation of Surface Heterogeneity in Graphite Anodes for Lithium-Ion Batteries: Passive Layer Formation Ravi N. Methekar,a,* Paul W. C. Northrop,a Kejia Chen,b Richard D. Braatz fade, and cycle life of Li-ion secondary batteries. In this paper, Kinetic Monte Carlo (KMC) simulation

  8. Journal of Statistical Physics, Vol. 89, Nos. 5/6, 1997 Simulated Annealing Using Hybrid Monte Carlo

    E-Print Network [OSTI]

    Toral, Raúl

    of the system. It is known that if a system is heated to a very high temperature T and then it is slowly cooledJournal of Statistical Physics, Vol. 89, Nos. 5/6, 1997 Simulated Annealing Using Hybrid Monte global actualizationsvia the hybrid Monte Carloalgorithmin theirgeneralizedversion for the proposal

  9. Comparison of Monte-Carlo and Einstein methods in the light-gas interactions

    E-Print Network [OSTI]

    Jacques Moret-Bailly

    2010-01-18T23:59:59.000Z

    To study the propagation of light in nebulae, many astrophysicists use a Monte-Carlo computation which does not take interferences into account. Replacing the wrong method by Einstein coefficients theory gives, on an example, a theoretical spectrum much closer to the observed one.

  10. Dose distribution close to metal implants in Gamma Knife Radiosurgery: A Monte Carlo study

    E-Print Network [OSTI]

    Yu, K.N.

    Detachable Coil GDC system was used to localize and obliterate the aneurysm.5 Soft platinum coils were­8 II. METHODOLOGY The Monte Carlo system employed is the PRESTA Pa- rameter Reduced Electron be predicted correctly by the present treatment planning system, GammaPlan,1 be- cause the calculations

  11. SCALE Continuous-Energy Monte Carlo Depletion with Parallel KENO in TRITON

    SciTech Connect (OSTI)

    Goluoglu, Sedat [ORNL] [ORNL; Bekar, Kursat B [ORNL] [ORNL; Wiarda, Dorothea [ORNL] [ORNL

    2012-01-01T23:59:59.000Z

    The TRITON sequence of the SCALE code system is a powerful and robust tool for performing multigroup (MG) reactor physics analysis using either the 2-D deterministic solver NEWT or the 3-D Monte Carlo transport code KENO. However, as with all MG codes, the accuracy of the results depends on the accuracy of the MG cross sections that are generated and/or used. While SCALE resonance self-shielding modules provide rigorous resonance self-shielding, they are based on 1-D models and therefore 2-D or 3-D effects such as heterogeneity of the lattice structures may render final MG cross sections inaccurate. Another potential drawback to MG Monte Carlo depletion is the need to perform resonance self-shielding calculations at each depletion step for each fuel segment that is being depleted. The CPU time and memory required for self-shielding calculations can often eclipse the resources needed for the Monte Carlo transport. This summary presents the results of the new continuous-energy (CE) calculation mode in TRITON. With the new capability, accurate reactor physics analyses can be performed for all types of systems using the SCALE Monte Carlo code KENO as the CE transport solver. In addition, transport calculations can be performed in parallel mode on multiple processors.

  12. Collective enhancement of nuclear state densities by the shell model Monte Carlo approach

    E-Print Network [OSTI]

    C. Özen; Y. Alhassid; H. Nakada

    2015-01-22T23:59:59.000Z

    The shell model Monte Carlo (SMMC) approach allows for the microscopic calculation of statistical and collective properties of heavy nuclei using the framework of the configuration-interaction shell model in very large model spaces. We present recent applications of the SMMC method to the calculation of state densities and their collective enhancement factors in rare-earth nuclei.

  13. Composition of Fish Communities in a European Macrotidal Salt Marsh (the Mont Saint-Michel Bay,

    E-Print Network [OSTI]

    Boyer, Edmond

    Composition of Fish Communities in a European Macrotidal Salt Marsh (the Mont Saint-Michel Bay At least 100 fish species are known to be present in the intertidal areas (estuaries, mudflats and salt, such as estuaries and lagoons, play a nursery role for many fish species. However, in Europe little attention has

  14. MonteCarloType Techniques for Processing Interval Uncertainty, and Their Geophysical and

    E-Print Network [OSTI]

    Ward, Karen

    Monte­Carlo­Type Techniques for Processing Interval Uncertainty, and Their Geophysical contact email vladik@cs.utep.edu Abstract To determine the geophysical structure of a region, we measure are independently normally distributed. Problem: the resulting accuracies are not in line with geophysical intuition

  15. Monte-Carlo-Type Techniques for Processing Interval Uncertainty, and Their Geophysical and

    E-Print Network [OSTI]

    Ward, Karen

    Monte-Carlo-Type Techniques for Processing Interval Uncertainty, and Their Geophysical contact email vladik@cs.utep.edu Abstract To determine the geophysical structure of a region, we measure are independently normally distributed. Problem: the resulting accuracies are not in line with geophysical intuition

  16. The S/sub N//Monte Carlo response matrix hybrid method

    SciTech Connect (OSTI)

    Filippone, W.L.; Alcouffe, R.E.

    1987-01-01T23:59:59.000Z

    A hybrid method has been developed to iteratively couple S/sub N/ and Monte Carlo regions of the same problem. This technique avoids many of the restrictions and limitations of previous attempts to do the coupling and results in a general and relatively efficient method. We demonstrate the method with some simple examples.

  17. Path Integral Monte Carlo Simulation of the Low-Density Hydrogen Plasma B. Militzer y

    E-Print Network [OSTI]

    Militzer, Burkhard

    Path Integral Monte Carlo Simulation of the Low-Density Hydrogen Plasma B. Militzer y Lawrence to calculate the equilibrium properties of hydrogen in the density and temperature range of 9:83 #2; 10 4 #20 surface. We calculate the equation of state and compare with other models for hydrogen valid

  18. Explicit estimation of higher order modes in fission source distribution of Monte-Carlo calculation

    SciTech Connect (OSTI)

    Yamamoto, A.; Sakata, K.; Endo, T. [Nagoya University, Department of Materials, Physics and Energy Engineering, Furo-cho, Chikusa-ku, Nagoya, 464-8603 (Japan)

    2013-07-01T23:59:59.000Z

    Magnitude of higher order modes in fission source distribution of a multi-group Monte-Carlo calculation is estimated using the orthogonal property of forward and adjoint fission source distributions. Calculation capability of the forward and adjoint fission source distributions for fundamental and higher order modes are implemented in the AEGIS code, which is a two-dimensional transport code based on the method of characteristics. With the calculation results of the AEGIS code, magnitudes of the first to fifth higher order modes in fission source distribution obtained by the multi-group Monte-Carlo code GMVP are estimated. There are two contributions in the present study - (1) establishment of a surrogate model, which represents convergence of fission source distribution taking into account the inherent statistical 'noise' of higher order modes of Monte-Carlo calculations and (2) independent confirmation of the estimated dominance ratio in a Monte-Carlo calculation. The surrogate model would contribute to studies of the inter-cycle correlation and estimation of sufficient number of inactive/active cycles. (authors)

  19. Comparison of the Monte Carlo adjoint-weighted and differential operator perturbation methods

    SciTech Connect (OSTI)

    Kiedrowski, Brian C [Los Alamos National Laboratory; Brown, Forrest B [Los Alamos National Laboratory

    2010-01-01T23:59:59.000Z

    Two perturbation theory methodologies are implemented for k-eigenvalue calculations in the continuous-energy Monte Carlo code, MCNP6. A comparison of the accuracy of these techniques, the differential operator and adjoint-weighted methods, is performed numerically and analytically. Typically, the adjoint-weighted method shows better performance over a larger range; however, there are exceptions.

  20. Monte Carlo Simulation of Electrodeposition of Copper: A Multistep Free Energy Calculation

    E-Print Network [OSTI]

    Subramanian, Venkat

    Monte Carlo Simulation of Electrodeposition of Copper: A Multistep Free Energy Calculation S is carried out to evaluate the step wise free energy change in the process of electrochemical copper the number of species (CuCl2 or CuSO4 or Cu as the case may be) and in turn the free energy. The effect

  1. Simulations of polycrystalline CVD diamond film growth using a simplified Monte Carlo model

    E-Print Network [OSTI]

    Bristol, University of

    Simulations of polycrystalline CVD diamond film growth using a simplified Monte Carlo model P online 6 November 2009 Keywords: CVD diamond growth Modelling Nucleation Nanodiamond A simple 1) of a diamond (100) surface. The model considers adsorption, etching/desorption, lattice incorporation

  2. Study of CANDU Thorium-based Fuel Cycles by Deterministic and Monte Carlo Methods

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Study of CANDU Thorium-based Fuel Cycles by Deterministic and Monte Carlo Methods A. Nuttin1 , P, there is a renewal of interest in self-sustainable thorium fuel cycles applied to various concepts such as Molten here, with a shorter term view, to re-evaluate the economic competitiveness of once-through thorium

  3. Sources of Traffic Demand Variability and Use of Monte Carlo for Network Capacity Planning

    E-Print Network [OSTI]

    Cortes, Corinna

    to deal with rightfully angry business and finance teams: physical resources start depreciating the moment the sources of traffic demand variability and dive into Monte-Carlo methodology as an efficient way; throughput; traffic; concurrency; availability; node-and-link model; fast-time simulation; agent

  4. Quantum Monte Carlo calculations of electronic excitation energies: the case of the singlet n

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    ) transition in acrolein Julien Toulouse1 , Michel Caffarel2 , Peter Reinhardt1 , Philip E. Hoggan3 , and C. J-of-the-art quantum Monte Carlo calculations of the singlet n (CO) vertical excitation energy in the acrolein in the acrolein molecule without reoptimization of the determinantal part of the wave function. The acrolein

  5. A Methodological Comparison of Monte Carlo Simulation and Epoch-Era Analysis for

    E-Print Network [OSTI]

    de Weck, Olivier L.

    techniques, morphological analysis, scenario planning · Semi-quantitative methods (can be used to initialize%) ­ Probabilistic risk assessment (PRA), Fault Tree Analysis (FTA), Hazards Analysis (HA), Failure modes and effectsA Methodological Comparison of Monte Carlo Simulation and Epoch-Era Analysis for Tradespace

  6. Instabilities in Molecular Dynamics Integrators used in Hybrid Monte Carlo Simulations

    E-Print Network [OSTI]

    B. Joo; UKQCD Collaboration

    2001-10-11T23:59:59.000Z

    We discuss an instability in the leapfrog integration algorithm, widely used in current Hybrid Monte Carlo (HMC) simulations of lattice QCD. We demonstrate the instability in the simple harmonic oscillator (SHO) system where it is manifest. We demonstrate the instability in HMC simulations of lattic QCD with dynamical Wilson-Clover fermions and discuss implications for future simulations of lattice QCD.

  7. Use of single scatter electron monte carlo transport for medical radiation sciences

    DOE Patents [OSTI]

    Svatos, Michelle M. (Oakland, CA)

    2001-01-01T23:59:59.000Z

    The single scatter Monte Carlo code CREEP models precise microscopic interactions of electrons with matter to enhance physical understanding of radiation sciences. It is designed to simulate electrons in any medium, including materials important for biological studies. It simulates each interaction individually by sampling from a library which contains accurate information over a broad range of energies.

  8. Monte Carlo Posterior Integration in GARCH Peter M uller and Andy Pole

    E-Print Network [OSTI]

    West, Mike

    Monte Carlo Posterior Integration in GARCH Models Peter M¨ uller and Andy Pole Peter M along both lines to apply to the analysis of GARCH (generalized autoregressive conditional­ tion to GARCH models in Bollerslev (1986). There are now over 300 papers in the mainstream statistics

  9. Supertrack Monte Carlo variance reduction experience for non-Boltzmann tallies

    SciTech Connect (OSTI)

    Estes, G.P.; Booth, T.E.

    1995-02-01T23:59:59.000Z

    This paper applies a recently developed variance reduction technique to the first principles calculations of photon detector responses. This technique makes possible the direct comparison of pulse height calculations with measurements without the need for unfolding techniques. Comparisons are made between several experiments and the calculations to demonstrate the utility of the supertrack Monte Carlo technique for reproducing and interpreting experimental count rate spectra.

  10. Elsevier Science 1 Use of the GATE Monte Carlo package for dosimetry

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Elsevier Science 1 Use of the GATE Monte Carlo package for dosimetry applications D. Visvikis, a* M Angeles, USA Abstract One of the roles for MC simulation studies is in the area of dosimetry. A number of different codes dedicated to dosimetry applications are available and widely used today, such as MCNP

  11. Monte Carlo Simulation of Radiation in Gases with a NarrowBand Model

    E-Print Network [OSTI]

    Dufresne, Jean-Louis

    , France (\\Phi) now at the Institute of Energy and Power Plant Technology, TH Darmstadt, 64287 DarmstadtMonte Carlo Simulation of Radiation in Gases with a Narrow­Band Model and a Net is used for simulation of radiative heat transfers in non­gray gases. The proposed procedure is based

  12. Sequential Monte Carlo for Simultaneous Passive Device-Free Tracking and Sensor Localization Using

    E-Print Network [OSTI]

    Rabbat, Michael

    Sequential Monte Carlo for Simultaneous Passive Device-Free Tracking and Sensor Localization Using Men Beijing Univ. Posts & Telecom. Beijing, China menad@bupt.edu.cn ABSTRACT This paper presents and evaluates a method for simulta- neously tracking a target while localizing the sensor nodes of a passive

  13. Green's function Monte Carlo calculation for the ground state of helium trimers

    SciTech Connect (OSTI)

    Cabral, F.; Kalos, M.H.

    1981-02-01T23:59:59.000Z

    The ground state energy of weakly bound boson trimers interacting via Lennard-Jones (12,6) pair potentials is calculated using a Monte Carlo Green's Function Method. Threshold coupling constants for self binding are obtained by extrapolation to zero binding.

  14. Combining Monte Carlo Simulations and Options to Manage the Risk of Real

    E-Print Network [OSTI]

    Boyer, Edmond

    of real estate portfolio valuations can be improved through the simultaneous use of Monte Carlo simulations and options theory. Our method considers the options embedded in Continental European lease are more reliable that those usually computed by the traditional method of discounted cash flow. Moreover

  15. First-row hydrides: Dissociation and ground state energies using quantum Monte Carlo

    E-Print Network [OSTI]

    Anderson, James B.

    First-row hydrides: Dissociation and ground state energies using quantum Monte Carlo Arne Lu, Pennsylvania 16802 Received 20 May 1996; accepted 24 July 1996 Accurate ground state energies comparable FN-DQMC method. The residual energy, the nodal error due to the error in the nodal structure

  16. A Combined Density Functional and Monte Carlo Study of Polycarbonate R. O. Jones and P. Ballone[*

    E-Print Network [OSTI]

    A Combined Density Functional and Monte Carlo Study of Polycarbonate R. O. Jones and P. Ballone and reactivity for organic systems closely related to bisphenol-A-polycarbonate(BPA- PC). The results provide a detailed description of polymers, using bisphenol A polycarbonate (BPA- PC) as an example

  17. K-effective of the world: and other concerns for Monte Carlo Eigenvalue calculations

    SciTech Connect (OSTI)

    Brown, Forrest B [Los Alamos National Laboratory

    2010-01-01T23:59:59.000Z

    Monte Carlo methods have been used to compute k{sub eff} and the fundamental model eigenfunction of critical systems since the 1950s. Despite the sophistication of today's Monte Carlo codes for representing realistic geometry and physics interactions, correct results can be obtained in criticality problems only if users pay attention to source convergence in the Monte Carlo iterations and to running a sufficient number of neutron histories to adequately sample all significant regions of the problem. Recommended best practices for criticality calculations are reviewed and applied to several practical problems for nuclear reactors and criticality safety, including the 'K-effective of the World' problem. Numerical results illustrate the concerns about convergence and bias. The general conclusion is that with today's high-performance computers, improved understanding of the theory, new tools for diagnosing convergence (e.g., Shannon entropy of the fission distribution), and clear practical guidance for performing calculations, practitioners will have a greater degree of confidence than ever of obtaining correct results for Monte Carlo criticality calculations.

  18. Monte Carlo Simulation of Alzheimer's Disease in the United States: 2010-2060

    E-Print Network [OSTI]

    Feres, Renato

    Monte Carlo Simulation of Alzheimer's Disease in the United States: 2010-2060 Michael Blech concerns facing the United States over the next 50 years. This progressive disease is currently the sixth on the United States population, and second, the simulation models both prevalence and mortality. Both

  19. Sequential Monte Carlo in Model Comparison: Example in Cellular Dynamics in Systems Biology

    E-Print Network [OSTI]

    Richardson, David

    : American Statistical Association (2009): 1274-1287. Abstract Sequential Monte Carlo analysis of time series. Mukherjee L. You M. West -- Published in: JSM Proceedings/Bayesian Statistical Science. Alexandria, VA statistical model assessment is really just beginning in this new field. Single cell time series data

  20. A new approach to Monte Carlo simulations in statistical physics: Wang-Landau sampling

    E-Print Network [OSTI]

    Holzwarth, Natalie

    it to models exhibiting first-order or second-order phase transitions. © 2004 American Association of PhysicsA new approach to Monte Carlo simulations in statistical physics: Wang-Landau sampling D. P. Landau for doing simulations in classical statistical physics in a different way. Instead of sampling

  1. Performance Characteristics of Cathode Materials for Lithium-Ion Batteries: A Monte Carlo Strategy

    E-Print Network [OSTI]

    Subramanian, Venkat

    Performance Characteristics of Cathode Materials for Lithium-Ion Batteries: A Monte Carlo Strategy to study the performance of cathode materials in lithium-ion batteries. The methodology takes into account. Published September 26, 2008. Lithium-ion batteries are state-of-the-art power sources1 for por- table

  2. A Scalable Parallel Monte Carlo Method for Free Energy Simulations of Molecular Systems

    E-Print Network [OSTI]

    Chan, Derek Y C

    A Scalable Parallel Monte Carlo Method for Free Energy Simulations of Molecular Systems MALEK O for problems where the energy dominates the entropy. An example is parallel tempering, in which simulations the free energy of the system as a direct output of the simulation. Traditional Metropolis MC samples phase

  3. Optical Monte Carlo modeling of a true port wine stain anatomy

    E-Print Network [OSTI]

    Barton, Jennifer K.

    of accommodating an arbitrarily complex geometry was used to determine the energy deposition in a true port wineOptical Monte Carlo modeling of a true port wine stain anatomy Jennifer Kehlet Barton, T. Joshua nm. At both wavelengths, the greatest energy deposition occurred in the superficial blood vessels

  4. Reconstruction for proton computed tomography by tracing proton trajectories: A Monte Carlo study

    E-Print Network [OSTI]

    Reconstruction for proton computed tomography by tracing proton trajectories: A Monte Carlo study 11 January 2006; published 22 February 2006 Proton computed tomography pCT has been explored computed tomography pCT has several potential ad- vantages in medical applications. Its favorable dose

  5. A Positive-Weight Next-to-Leading-Order Monte Carlo for Heavy Flavour Hadroproduction

    E-Print Network [OSTI]

    Stefano Frixione; Paolo Nason; Giovanni Ridolfi

    2007-09-22T23:59:59.000Z

    We present a next-to-leading order calculation of heavy flavour production in hadronic collisions that can be interfaced to shower Monte Carlo programs. The calculation is performed in the context of the POWHEG method. It is suitable for the computation of charm, bottom and top hadroproduction. In the case of top production, spin correlations in the decay products are taken into account.

  6. Tir--part Les espaces boiss du flanc nord-ouest du mont Royal

    E-Print Network [OSTI]

    milieu de la plaine du Saint-Laurent et d'une ville fortement urbanisée, le mont Royal constitue un'arrondissement historique et naturel. Par cette double désignation, il reconnaît que les qualités natu- relles et

  7. Monte Carlo simulation of electron transport in degenerate and inhomogeneous semiconductors

    E-Print Network [OSTI]

    Monte Carlo simulation of electron transport in degenerate and inhomogeneous semiconductors Mona concentrations up to 1020 cm-3 . De- generate semiconductors are important for thermoelectric and thermionic transport in degenerate semiconductor-based structures. If the electron wavelength is smaller than

  8. Monte Carlo Calculations of the Intrinsic Detector Backgrounds for the Karlsruhe Tritium Neutrino Experiment

    E-Print Network [OSTI]

    Washington at Seattle, University of - Department of Physics, Electroweak Interaction Research Group

    Monte Carlo Calculations of the Intrinsic Detector Backgrounds for the Karlsruhe Tritium Neutrino of the Intrinsic Detector Backgrounds for the Karlsruhe Tritium Neutrino Experiment Michelle L. Leber Chair of the Supervisory Committee: Professor John F. Wilkerson Physics The Karlsruhe Tritium Neutrino Experiment (KATRIN

  9. Monte Carlo simulation methodology of the ghost interface theory for the planar surface tension

    E-Print Network [OSTI]

    Attard, Phil

    Monte Carlo simulation methodology of the ghost interface theory for the planar surface tension October 2003 A novel ``ghost interface'' expression for the surface tension of a planar liquid coexisting phases. Results generated from the ghost interface theory for the surface tension are presented

  10. North western Alps Holocene paleohydrology recorded by flooding activity in Lake Le Bourget, France and its relationship with Mont-Blanc glacier

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    , France and its relationship with Mont-Blanc glacier fluctuations M., Debret1, 2 , E., Chapron3, 2 , M large glaciers from the Mont Blanc Massif, and fluctuations in Rhone River flood supply in Lake Le Bourget is interpreted as resulting essentially from Mont Blanc Glacier activity during the Holocene

  11. Social Influences on Food Choices of Norway Rats and Mate Choices of Japanese Quail

    E-Print Network [OSTI]

    Galef, Jr., Bennett G.

    2001-01-01T23:59:59.000Z

    ecology and sociology of the Norway rat . Bethesda: U.S. De-food stealing by young Norway rats. Journal of Comparativesufficient diet by Norway rats. Journal of Comparative

  12. Demography of auklets Aethia spp. in relation to introduced Norway rats Rattus norvegicus at Kiska

    E-Print Network [OSTI]

    Jones, Ian L.

    Demography of auklets Aethia spp. in relation to introduced Norway rats Rattus norvegicus at Kiska................................................................................................4 Norway Rat Abundance and Distribution .........................................................5................................................................................................6 Norway Rat Abundance and Distribution.........................................................7

  13. The use of spin-pure and non-orthogonal Hilbert spaces in Full Configuration Interaction Quantum Monte-Carlo

    E-Print Network [OSTI]

    Smart, Simon Daniel

    2014-02-04T23:59:59.000Z

    The use of spin-pure and non-orthogonal Hilbert spaces in Full Configuration Interaction Quantum Monte–Carlo Simon Smart Trinity College This dissertation is submitted for the degree of Doctor of Philosophy at the University of Cambridge, December... 2013 For my mother Diana Jean Smart 1956-2013 The use of spin-pure and non-orthogonal Hilbert spaces in Full Configuration Interaction Quantum Monte–Carlo Simon Smart Abstract Full Configuration Interaction Quantum Monte–Carlo (FCIQMC) al- lows...

  14. New variational Monte Carlo method with an energy variance extrapolation for large-scale shell-model calculations

    E-Print Network [OSTI]

    Takahiro Mizusaki; Noritaka Shimizu

    2012-01-27T23:59:59.000Z

    We propose a new variational Monte Carlo (VMC) method with an energy variance extrapolation for large-scale shell-model calculations. This variational Monte Carlo is a stochastic optimization method with a projected correlated condensed pair state as a trial wave function, and is formulated with the M-scheme representation of projection operators, the Pfaffian and the Markov-chain Monte Carlo (MCMC). Using this method, we can stochastically calculate approximated yrast energies and electro-magnetic transition strengths. Furthermore, by combining this VMC method with energy variance extrapolation, we can estimate exact shell-model energies.

  15. Autoradiographic localization of atrial natriuretic peptide receptor subtypes in rat kidney

    SciTech Connect (OSTI)

    Brown, J.; Salas, S.P.; Singleton, A.; Polak, J.M. (Univ. of Cambridge (England))

    1990-07-01T23:59:59.000Z

    The distribution of atrial natriuretic peptide (ANP) clearance receptors in rat kidney was investigated by in vitro autoradiography using des(Gln18,Ser19,Gly20,Leu21,Gly22)-ANP-(4- 23) (C-ANP) and 125I-Tyr0-ANP-(5-25) as relatively specific ligands of this receptor. Alpha-125I-ANP (100 pM) bound reversibly but with high affinity to glomeruli, outer medullary vasa recta bundles, and inner medulla. C-ANP (10 microM) inhibited greater than 60% of this glomerular binding but did not inhibit the binding of alpha-125I-ANP to medullary tissues. Alpha-125I-ANP also bound reversibly to the renal arteries up to the glomerulus. This arterial binding was only partly inhibited by 10 microM C-ANP. In the presence of 10 microM C-ANP, increasing concentrations of alpha-125I-ANP bound to a residue of glomerular sites with apparent dissociation constants of 0.82 +/- 0.16 to 2.73 +/- 1.20 nM at different cortical levels. 125I-Tyr0-ANP-(5-25) bound significantly to glomeruli and intrarenal arteries but not to vasa recta bundles or inner medulla. This glomerular binding also occurred with nanomolar dissociation constants. It was completely inhibited by 1 microM alpha-ANP and 10 microM C-ANP, but not by unrelated peptides such as gastrin. These results suggest that renal ANP clearance receptors are restricted in vivo to the glomeruli and renal arterial system of the rat.

  16. The energy injection and losses in the Monte Carlo simulations of a diffusive shock

    E-Print Network [OSTI]

    Wang, Xin

    2011-01-01T23:59:59.000Z

    Although diffusive shock acceleration (DSA) could be simulated by some well-established models, the assumption of the injection rate from the thermal particles to the superthermal population is still a contentious problem. But in the self-consistent Monte Carlo simulations, because of the prescribed scattering law instead of the assumption of the injected function, hence particle injection rate is intrinsically defined by the prescribed scattering law. We expect to examine the correlation of the energy injection with the prescribed multiple scattering angular distributions. According to the Rankine-Hugoniot conditions, the energy injection and the losses in the simulation system can directly decide the shock energy spectrum slope. By the simulations performed with multiple scattering law in the dynamical Monte Carlo model, the energy injection and energy loss functions are obtained. As results, the case applying anisotropic scattering law produce a small energy injection and large energy losses leading to a s...

  17. Calculating alpha Eigenvalues in a Continuous-Energy Infinite Medium with Monte Carlo

    SciTech Connect (OSTI)

    Betzler, Benjamin R. [Los Alamos National Laboratory; Kiedrowski, Brian C. [Los Alamos National Laboratory; Brown, Forrest B. [Los Alamos National Laboratory; Martin, William R. [Los Alamos National Laboratory

    2012-09-04T23:59:59.000Z

    The {alpha} eigenvalue has implications for time-dependent problems where the system is sub- or supercritical. We present methods and results from calculating the {alpha}-eigenvalue spectrum for a continuous-energy infinite medium with a simplified Monte Carlo transport code. We formulate the {alpha}-eigenvalue problem, detail the Monte Carlo code physics, and provide verification and results. We have a method for calculating the {alpha}-eigenvalue spectrum in a continuous-energy infinite-medium. The continuous-time Markov process described by the transition rate matrix provides a way of obtaining the {alpha}-eigenvalue spectrum and kinetic modes. These are useful for the approximation of the time dependence of the system.

  18. Hard-sphere melting and crystallization with event-chain Monte Carlo

    E-Print Network [OSTI]

    Isobe, Masaharu

    2015-01-01T23:59:59.000Z

    We simulate crystallization and melting with local Monte Carlo (LMC), event-chain Monte Carlo (ECMC), and with event-driven molecular dynamics (EDMD) in systems with up to one million three-dimensional hard spheres. We illustrate that our implementations of the three algorithms rigorously coincide in their equilibrium properties. We then study nucleation in the NVE ensemble from the fcc crystal into the homogeneous liquid phase and from the liquid into the homogeneous crystal. ECMC and EDMD both approach equilibrium orders of magnitude faster than LMC. ECMC is also notably faster than EDMD, especially for the equilibration into a crystal from a disordered initial condition at high density. ECMC can be trivially implemented for hard-sphere and for soft-sphere potentials, and we suggest possible applications of this algorithm for studying jamming and the physics of glasses, as well as disordered systems.

  19. Study of nuclear pairing with Configuration-Space Monte-Carlo approach

    E-Print Network [OSTI]

    Lingle, Mark

    2015-01-01T23:59:59.000Z

    Pairing correlations in nuclei play a decisive role in determining nuclear drip-lines, binding energies, and many collective properties. In this work a new Configuration-Space Monte-Carlo (CSMC) method for treating nuclear pairing correlations is developed, implemented, and demonstrated. In CSMC the Hamiltonian matrix is stochastically generated in Krylov subspace, resulting in the Monte-Carlo version of Lanczos-like diagonalization. The advantages of this approach over other techniques are discussed; the absence of the fermionic sign problem, probabilistic interpretation of quantum-mechanical amplitudes, and ability to handle truly large-scale problems with defined precision and error control, are noteworthy merits of CSMC. The features of our CSMC approach are shown using models and realistic examples. Special attention is given to difficult limits: situations with non-constant pairing strengths, cases with nearly degenerate excited states, limits when pairing correlations in finite systems are weak, and pr...

  20. Rao-Blackwellised Interacting Markov Chain Monte Carlo for Electromagnetic Scattering Inversion

    E-Print Network [OSTI]

    Giraud, François

    2012-01-01T23:59:59.000Z

    The following electromagnetism (EM) inverse problem is addressed. It consists in estimating local radioelectric properties of materials recovering an object from the global EM scattering measurement, at various incidences and wave frequencies. This large scale ill-posed inverse problem is explored by an intensive exploitation of an efficient 2D Maxwell solver, distributed on High Performance Computing (HPC) machines. Applied to a large training data set, a statistical analysis reduces the problem to a simpler probabilistic metamodel, on which Bayesian inference can be performed. Considering the radioelectric properties as a dynamic stochastic process, evolving in function of the frequency, it is shown how advanced Markov Chain Monte Carlo methods, called Sequential Monte Carlo (SMC) or interacting particles, can provide estimations of the EM properties of each material, and their associated uncertainties.

  1. MCAMC: An Advanced Algorithm for Kinetic Monte Carlo Simulations: from Magnetization Switching to Protein Folding

    E-Print Network [OSTI]

    M. A. Novotny; Shannon M. Wheeler

    2002-11-02T23:59:59.000Z

    We present the Monte Carlo with Absorbing Markov Chains (MCAMC) method for extremely long kinetic Monte Carlo simulations. The MCAMC algorithm does not modify the system dynamics. It is extremely useful for models with discrete state spaces when low-temperature simulations are desired. To illustrate the strengths and limitations of this algorithm we introduce a simple model involving random walkers on an energy landscape. This simple model has some of the characteristics of protein folding and could also be experimentally realizable in domain motion in nanoscale magnets. We find that even the simplest MCAMC algorithm can speed up calculations by many orders of magnitude. More complicated MCAMC simulations can gain further increases in speed by orders of magnitude.

  2. Monte Carlo simulation to investigate the formation of molecular hydrogen and its deuterated forms

    E-Print Network [OSTI]

    Sahu, DIpen; Majumdar, Liton; Chakrabarti, Sandip K

    2015-01-01T23:59:59.000Z

    $H_2$ is the most abundant interstellar species. Its deuterated forms ($HD$ and $D_2$) are also significantly abundant. Huge abundances of these molecules could be explained by considering the chemistry occurring on the interstellar dust. Because of its simplicity, Rate equation method is widely used to study the formation of grain-surface species. However, since recombination efficiency of formation of any surface species are heavily dependent on various physical and chemical parameters, Monte Carlo method would be best method suited to take care of randomness of the processes. We perform Monte Carlo simulation to study the formation of $H_2$, $HD$ and $D_2$ on interstellar ices. Adsorption energies of surface species are the key inputs for the formation of any species on interstellar dusts but binding energies of deuterated species are yet to known with certainty. A zero point energy correction exists between hydrogenated and deuterated species which should be considered while modeling the chemistry on the ...

  3. A user-friendly, graphical interface for the Monte Carlo neutron optics code MCLIB

    SciTech Connect (OSTI)

    Thelliez, T.; Daemen, L.; Hjelm, R.P. [Los Alamos National Lab., NM (United States); Seeger, P.A. [Seeger (Phil A.), Los Alamos, NM (United States)

    1995-12-01T23:59:59.000Z

    The authors describe a prototype of a new user interface for the Monte Carlo neutron optics simulation program MCLIB. At this point in its development the interface allows the user to define an instrument as a set of predefined instrument elements. The user can specify the intrinsic parameters of each element, its position and orientation. The interface then writes output to the MCLIB package and starts the simulation. The present prototype is an early development stage of a comprehensive Monte Carlo simulations package that will serve as a tool for the design, optimization and assessment of performance of new neutron scattering instruments. It will be an important tool for understanding the efficacy of new source designs in meeting the needs of these instruments.

  4. A Monte Carlo simulation for kinetic chemotaxis models: an application to the traveling population wave

    E-Print Network [OSTI]

    Yasuda, Shugo

    2015-01-01T23:59:59.000Z

    A Monte Carlo simulation for the chemotactic bacteria is developed on the basis of the kinetic modeling, i.e., the Boltzmann transport equation, and applied to the one-dimensional traveling population wave in a micro channel.In this method, the Monte Carlo method, which calculates the run-and-tumble motions of bacteria, is coupled with a finite volume method to solve the macroscopic transport of the chemical cues in the field. The simulation method can successfully reproduce the traveling population wave of bacteria which was observed experimentally. The microscopic dynamics of bacteria, e.g., the velocity autocorrelation function and velocity distribution function of bacteria, are also investigated. It is found that the bacteria which form the traveling population wave create quasi-periodic motions as well as a migratory movement along with the traveling population wave. Simulations are also performed with changing the sensitivity and modulation parameters in the response function of bacteria. It is found th...

  5. MCViNE -- An object oriented Monte Carlo neutron ray tracing simulation package

    E-Print Network [OSTI]

    Lin, Jiao Y Y; Granroth, Garrett E; Abernathy, Douglas L; Lumsden, Mark D; Winn, Barry; Aczel, Adam A; Aivazis, Michael; Fultz, Brent

    2015-01-01T23:59:59.000Z

    MCViNE (Monte-Carlo VIrtual Neutron Experiment) is a versatile Monte Carlo (MC) neutron ray-tracing program that provides researchers with tools for performing computer modeling and simulations that mirror real neutron scattering experiments. By adopting modern software engineering practices such as using composite and visitor design patterns for representing and accessing neutron scatterers, and using recursive algorithms for multiple scattering, MCViNE is flexible enough to handle sophisticated neutron scattering problems including, for example, neutron detection by complex detector systems, and single and multiple scattering events in a variety of samples and sample environments. In addition, MCViNE can take advantage of simulation components in linear-chain-based MC ray tracing packages widely used in instrument design and optimization, as well as NumPy-based components that make prototypes useful and easy to develop. These developments have enabled us to carry out detailed simulations of neutron scatteri...

  6. Monte Carol-Based Dosimetry of Beta-Emitters for Intravascular Brachytherapy

    SciTech Connect (OSTI)

    Choi, C.K.

    2002-06-25T23:59:59.000Z

    Monte Carlo simulations for radiation dosimetry and the experimental verifications of the simulations have been developed for the treatment geometry of intravascular brachytherapy, a form of radionuclide therapy for occluded coronary disease (restenosis). Monte Carlo code, MCNP4C, has been used to calculate the radiation dose from the encapsulated array of B-emitting seeds (Sr/Y-source train). Solid water phantoms have been fabricated to measure the dose on the radiochromic films that were exposed to the beta source train for both linear and curved coronary vessel geometries. While the dose difference for the 5-degree curved vessel at the prescription point of f+2.0 mm is within the 10% guideline set by the AAPM, however, the difference increased dramatically to 16.85% for the 10-degree case which requires additional adjustment for the acceptable dosimetry planning. The experimental dose measurements agree well with the simulation results

  7. Imaging Nicotine in Rat Brain Tissue by Use of Nanospray Desorption...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Nicotine in Rat Brain Tissue by Use of Nanospray Desorption Electrospray Ionization Mass Spectrometry. Imaging Nicotine in Rat Brain Tissue by Use of Nanospray Desorption...

  8. E-Print Network 3.0 - adult rat liver Sample Search Results

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    from normal rat liver and incubated for 3 or 16 hours with increasing doses... of carbon tetrachloride (CCl4). Rat ... Source: Groningen, Rijksuniversiteit - Centre for...

  9. Using Markov chain Monte Carlo methods for estimating parameters with gravitational radiation data

    E-Print Network [OSTI]

    Nelson Christensen; Renate Meyer

    2001-02-05T23:59:59.000Z

    We present a Bayesian approach to the problem of determining parameters for coalescing binary systems observed with laser interferometric detectors. By applying a Markov Chain Monte Carlo (MCMC) algorithm, specifically the Gibbs sampler, we demonstrate the potential that MCMC techniques may hold for the computation of posterior distributions of parameters of the binary system that created the gravity radiation signal. We describe the use of the Gibbs sampler method, and present examples whereby signals are detected and analyzed from within noisy data.

  10. Imaginary time correlations and the phaseless auxiliary field quantum Monte Carlo

    SciTech Connect (OSTI)

    Motta, M.; Galli, D. E.; Vitali, E. [Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano (Italy)] [Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano (Italy); Moroni, S. [IOM-CNR DEMOCRITOS National Simulation Center and SISSA, via Bonomea 265, 34136 Trieste (Italy)] [IOM-CNR DEMOCRITOS National Simulation Center and SISSA, via Bonomea 265, 34136 Trieste (Italy)

    2014-01-14T23:59:59.000Z

    The phaseless Auxiliary Field Quantum Monte Carlo (AFQMC) method provides a well established approximation scheme for accurate calculations of ground state energies of many-fermions systems. Here we address the possibility of calculating imaginary time correlation functions with the phaseless AFQMC. We give a detailed description of the technique and test the quality of the results for static properties and imaginary time correlation functions against exact values for small systems.

  11. The Metropolis Monte Carlo method with CUDA enabled Graphic Processing Units

    SciTech Connect (OSTI)

    Hall, Clifford [Computational Materials Science Center, George Mason University, 4400 University Dr., Fairfax, VA 22030 (United States) [Computational Materials Science Center, George Mason University, 4400 University Dr., Fairfax, VA 22030 (United States); School of Physics, Astronomy, and Computational Sciences, George Mason University, 4400 University Dr., Fairfax, VA 22030 (United States); Ji, Weixiao [Computational Materials Science Center, George Mason University, 4400 University Dr., Fairfax, VA 22030 (United States)] [Computational Materials Science Center, George Mason University, 4400 University Dr., Fairfax, VA 22030 (United States); Blaisten-Barojas, Estela, E-mail: blaisten@gmu.edu [Computational Materials Science Center, George Mason University, 4400 University Dr., Fairfax, VA 22030 (United States) [Computational Materials Science Center, George Mason University, 4400 University Dr., Fairfax, VA 22030 (United States); School of Physics, Astronomy, and Computational Sciences, George Mason University, 4400 University Dr., Fairfax, VA 22030 (United States)

    2014-02-01T23:59:59.000Z

    We present a CPU–GPU system for runtime acceleration of large molecular simulations using GPU computation and memory swaps. The memory architecture of the GPU can be used both as container for simulation data stored on the graphics card and as floating-point code target, providing an effective means for the manipulation of atomistic or molecular data on the GPU. To fully take advantage of this mechanism, efficient GPU realizations of algorithms used to perform atomistic and molecular simulations are essential. Our system implements a versatile molecular engine, including inter-molecule interactions and orientational variables for performing the Metropolis Monte Carlo (MMC) algorithm, which is one type of Markov chain Monte Carlo. By combining memory objects with floating-point code fragments we have implemented an MMC parallel engine that entirely avoids the communication time of molecular data at runtime. Our runtime acceleration system is a forerunner of a new class of CPU–GPU algorithms exploiting memory concepts combined with threading for avoiding bus bandwidth and communication. The testbed molecular system used here is a condensed phase system of oligopyrrole chains. A benchmark shows a size scaling speedup of 60 for systems with 210,000 pyrrole monomers. Our implementation can easily be combined with MPI to connect in parallel several CPU–GPU duets. -- Highlights: •We parallelize the Metropolis Monte Carlo (MMC) algorithm on one CPU—GPU duet. •The Adaptive Tempering Monte Carlo employs MMC and profits from this CPU—GPU implementation. •Our benchmark shows a size scaling-up speedup of 62 for systems with 225,000 particles. •The testbed involves a polymeric system of oligopyrroles in the condensed phase. •The CPU—GPU parallelization includes dipole—dipole and Mie—Jones classic potentials.

  12. Monte Carlo Solutions for Selected Problems in Gamma-Ray Spectrometry and Nuclear Activation Analysis

    SciTech Connect (OSTI)

    Sima, Octavian [Physics Department, University of Bucharest, Bucharest-Magurele, POBoxMG-11 RO-077125 (Romania)

    2008-08-14T23:59:59.000Z

    A comprehensive calibration of gamma-ray spectrometers cannot be obtained purely on experimental basis. Problems like self-attenuation effects, coincidence-summing effects and non-uniform source distribution (resulting e.g. from neutron self-shielding in NAA) can be efficiently solved by Monte Carlo simulation. The application of the GESPECOR code to these problems is presented and the associated uncertainty is discussed.

  13. The role of diagonalization within a diagonalization/Monte Carlo scheme

    E-Print Network [OSTI]

    Dean Lee

    2000-10-31T23:59:59.000Z

    We discuss a method called quasi-sparse eigenvector diagonalization which finds the most important basis vectors of the low energy eigenstates of a quantum Hamiltonian. It can operate using any basis, either orthogonal or non-orthogonal, and any sparse Hamiltonian, either Hermitian, non-Hermitian, finite-dimensional, or infinite-dimensional. The method is part of a new computational approach which combines both diagonalization and Monte Carlo techniques.

  14. Radiative transfer in the earth's atmosphere-ocean system using Monte Carlo techniques

    E-Print Network [OSTI]

    Bradley, Paul Andrew

    1987-01-01T23:59:59.000Z

    TRANSFER PROBLEM MONTE CARLO METHOD Assumptions of the Model Photon Pathlength Emulation Techniques Sampling Scattering Functions: Angles and Probabilities Emulation of an Interface Computing the Radiance by Statistical Estimation Determination... of Direction Cosines After Scattering Flux Estimation into Detectors Determination of a New Scattering Point Photon Trajectories Direct Flux and Radiance From the Ocean Bottonr Accounting for Multiple Orders of Scattering With the Bottom Computation...

  15. Calculation of shielding door thicknesses for radiation therapy facilities using the ITS Monte Carlo program

    SciTech Connect (OSTI)

    Biggs, P.J. (Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston (United States))

    1991-10-01T23:59:59.000Z

    Shielding calculations for door thicknesses for megavoltage radiotherapy facilities with mazes are generally straightforward. To simplify the calculations, the standard formalism adopts several approximations relating to the average beam path, scattering coefficients, and the mean energy of the spectrum of scattered radiation. To test the accuracy of these calculations, the Monte Carlo program, ITS, was applied to this problem by determining the dose and energy spectrum of the radiation at the door for 4- and 10-MV bremsstrahlung beams incident on a phantom at isocenter. This was performed for mazes, one termed 'standard' and the other a shorter maze where the primary beam is incident on the wall adjacent to the door. The peak of the photon-energy spectrum at the door was found to be the same for both types of maze, independent of primary beam energy, and also, in the case of the conventional maze, of the primary beam orientation. The spectrum was harder for the short maze and for 10 MV vs. 4 MV. The thickness of the lead door for a short maze configuration was 1.5 cm for 10 MV and 1.2 cm for 4 MV vs. approximately less than 1 mm for a conventional maze. For the conventional maze, the Monte Carlo calculation predicts the dose at the door to be lower than given by NCRP 49 and NCRP 51 by about a factor of 2 at 4 MV but to be the same at 10 MV. For the short maze, the Monte Carlo predicts the dose to be a factor of 3 lower for 4 MV and about a factor of 1.5 lower for 10 MV. Experimental results support the Monte Carlo findings for the short maze.

  16. Application of diffusion Monte Carlo to materials dominated by van der Waals interactions

    SciTech Connect (OSTI)

    Benali, Anouar [Argonne National Laboratory (ANL); Shulenburger, Luke [Sandia National Laboratory (SNL); Romero, Nichols [Argonne National Laboratory (ANL); Kim, Jeongnim [ORNL; Von Lilienfeld, Anatole [University of Basel

    2014-01-01T23:59:59.000Z

    Van der Waals forces are notoriously difficult to account for from first principles. We perform extensive calculation to assess the usefulness and validity of diffusion quantum Monte Carlo when applied to van der Waals forces. We present results for noble gas solids and clusters - archetypical van der Waals dominated assemblies, as well as a relevant pi-pi stacking supramolecular complex: DNA + intercalating anti-cancer drug Ellipticine.

  17. Monte Carlo Studies of the CALICE AHCAL Tiles Gaps and Non-uniformities

    E-Print Network [OSTI]

    Felix Sefkow; Angela Lucaci-Timoce

    2010-06-18T23:59:59.000Z

    The CALICE analog HCAL is a highly granular calorimeter, proposed for the International Linear Collider. It is based on scintillator tiles, read out by silicon photomultipliers (SiPMs). The effects of gaps between the calorimeter tiles, as well as the non-uniform response of the tiles, in view of the impact on the energy resolution, are studied in Monte Carlo events. It is shown that these type of effects do not have a significant influence on the measurement of hadron showers.

  18. A unified Monte Carlo approach to fast neutron cross section data evaluation.

    SciTech Connect (OSTI)

    Smith, D.; Nuclear Engineering Division

    2008-03-03T23:59:59.000Z

    A unified Monte Carlo (UMC) approach to fast neutron cross section data evaluation that incorporates both model-calculated and experimental information is described. The method is based on applications of Bayes Theorem and the Principle of Maximum Entropy as well as on fundamental definitions from probability theory. This report describes the formalism, discusses various practical considerations, and examines a few numerical examples in some detail.

  19. Hybrid Monte Carlo with Wilson Dirac operator on the Fermi GPU

    E-Print Network [OSTI]

    Chakrabarty, Abhijit

    2012-01-01T23:59:59.000Z

    In this article we present our implementation of a Hybrid Monte Carlo algorithm for Lattice Gauge Theory using two degenerate flavours of Wilson-Dirac fermions on a Fermi GPU. We find that using registers instead of global memory speeds up the code by almost an order of magnitude. To map the array variables to scalars, so that the compiler puts them in the registers, we use code generators. Our final program is more than 10 times faster than a generic single CPU.

  20. Hybrid Monte Carlo with Wilson Dirac operator on the Fermi GPU

    E-Print Network [OSTI]

    Abhijit Chakrabarty; Pushan Majumdar

    2012-07-10T23:59:59.000Z

    In this article we present our implementation of a Hybrid Monte Carlo algorithm for Lattice Gauge Theory using two degenerate flavours of Wilson-Dirac fermions on a Fermi GPU. We find that using registers instead of global memory speeds up the code by almost an order of magnitude. To map the array variables to scalars, so that the compiler puts them in the registers, we use code generators. Our final program is more than 10 times faster than a generic single CPU.

  1. adult rat vestibular: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    stimulate cell proliferation in adult rat vestibular sensory epithelia, as does the infusion of transforming growth factor alpha (TGF ) plus insulin. We sought to determine...

  2. Suppressed serum prolactin in sinoaortic-denervated rats

    SciTech Connect (OSTI)

    Alexander, N.; Melmed, S.; Morris, M.

    1987-02-01T23:59:59.000Z

    The authors investigated the effect of arterial baroreceptor deafferentation on serum and pituitary prolactin (PRL) and on catecholamines in median eminence (ME) and anterior and posterior pituitaries. Male Wistar rats were sinoaortic denervated (SAD) or sham operated (SO). Three days after surgery serum prolactin, measured by radioimmunoassay, was suppressed in SAD rats, and dopamine (DA) and norepinephrine (NE) concentrations, measured by radioenzymatic or high-performance liquid chromatography electron capture methods, were significantly reduced in ME of SAD rats. Simultaneously, anterior pituitary of SAD rats had significant increases in both catecholamines, whereas posterior pituitary showed no changes. Four hours after surgery serum PRL was also reduced in SAD rats, but no changes in ME catecholamines were found. Mean arterial pressure (MAP) and heart rate were measured before and after injection of bromocriptine in SAD and SO rats 3 days after surgery. Bromocriptine markedly suppressed serum PRL in both groups and reduced MAP from 144 +/- 10 to 84 +/- 5 and from 116 +/- 2 to 99 +/- 3 in SAD and SO rats, respectively; heart rate was reduced in SAD rats. They conclude that the SAD rat is a model of hypertension with suppressed serum PRL and that interruption of arterial baroreceptor nerves suppresses PRL secretion probably by modulating tuberoinfundibular turnover of catecholamines.

  3. TXSAMC (transport cross sections from applied Monte Carlo): a new tool for generating shielded multigroup cross sections 

    E-Print Network [OSTI]

    Hiatt, Matthew Torgerson

    2009-06-02T23:59:59.000Z

    This thesis describes a tool called TXSAMC (Transport Cross Sections from Applied Monte Carlo) that produces shielded and homogenized multigroup cross sections for small fast reactor systems. The motivation for this tool comes from a desire...

  4. Liquid-Liquid Phase Transition in Confined Water: A Monte Carlo Study Martin Meyer and H. Eugene Stanley*

    E-Print Network [OSTI]

    Stanley, H. Eugene

    Liquid-Liquid Phase Transition in Confined Water: A Monte Carlo Study Martin Meyer and H. Eugene Stanley* Center for Polymer Studies and Department of Physics, Boston UniVersity, Boston, Massachusetts

  5. Monte Carlo depletion calculations using VESTA 2.1 new features and perspectives

    SciTech Connect (OSTI)

    Haeck, W.; Cochet, B.; Aguiar, L. [Institut de Radioprotection et de Surete Nucleaire IRSN, BP 17, 92262 Fontenay-aux-Roses Cedex (France)

    2012-07-01T23:59:59.000Z

    VESTA is a Monte Carlo depletion interface code that is currently under development at IRSN. With VESTA, the emphasis lies on both accuracy and performance, so that the code will be capable of providing accurate and complete answers in an acceptable amount of time compared to other Monte Carlo depletion codes. From its inception, VESTA is intended to be a generic interface code so that it will ultimately be capable of using any Monte-Carlo code or depletion module and that can be tailored to the users needs. A new version of the code (version 2.1.x) will be released in 2012. The most important additions to the code are a burn up dependent isomeric branching ratio treatment to improve the prediction of metastable nuclides such as {sup 242m}Am and the integration of the PHOENIX point depletion module (also developed at IRSN) to overcome some of the limitations of the ORIGEN 2.2 module. The task of extracting and visualising the basic results and also the calculation of physical quantities or other data that can be derived from the basic output provided by VESTA will be the task of the AURORA depletion analysis tool which will be released at the same time as VESTA 2.1.x. The experimental validation database was also extended for this new version and it now contains a total of 35 samples with chemical assay data and 34 assembly decay heat measurements. (authors)

  6. Nonequilibrium candidate Monte Carlo: A new tool for efficient equilibrium simulation

    SciTech Connect (OSTI)

    Nilmeier, Jerome P.; Crooks, Gavin E.; Minh, David D. L.; Chodera, John D.

    2011-11-08T23:59:59.000Z

    Metropolis Monte Carlo simulation is a powerful tool for studying the equilibrium properties of matter. In complex condensed-phase systems, however, it is difficult to design Monte Carlo moves with high acceptance probabilities that also rapidly sample uncorrelated configurations. Here, we introduce a new class of moves based on nonequilibrium dynamics: candidate configurations are generated through a finite-time process in which a system is actively driven out of equilibrium, and accepted with criteria that preserve the equilibrium distribution. The acceptance rule is similar to the Metropolis acceptance probability, but related to the nonequilibrium work rather than the instantaneous energy difference. Our method is applicable to sampling from both a single thermodynamic state or a mixture of thermodynamic states, and allows both coordinates and thermodynamic parameters to be driven in nonequilibrium proposals. While generating finite-time switching trajectories incurs an additional cost, driving some degrees of freedom while allowing others to evolve naturally can lead to large enhancements in acceptance probabilities, greatly reducing structural correlation times. Using nonequilibrium driven processes vastly expands the repertoire of useful Monte Carlo proposals in simulations of dense solvated systems.

  7. Spatial homogenization of thermal feedback regions in Monte Carlo reactor calculations

    SciTech Connect (OSTI)

    Hanna, B. R.; Gill, D. F.; Griesheimer, D. P. [Bertis Atomic Power Laboratory, Bechtel Marine Propulsion Corporation, P.O. Box 79, West Mifflin, PA 15122 (United States)

    2012-07-01T23:59:59.000Z

    An integrated thermal-hydraulic feedback module has previously been developed for the Monte Carlo transport solver, MC21. The module incorporates a flexible input format that allows the user to describe heat transfer and coolant flow paths within the geometric model at any level of spatial detail desired. The effect that the varying levels of spatial homogenization of thermal regions has on the accuracy of the Monte Carlo simulations is examined in this study. Six thermal feedback mappings are constructed from the same geometric model of the Calvert Cliffs core. The spatial homogenization of the thermal regions is varied, giving each scheme a different level of detail, and the adequacy of the spatial homogenization is determined based on the eigenvalue produced by each Monte Carlo calculation. The purpose of these numerical experiments is to determine the level of detail necessarily to accurately capture the thermal feedback effect on reactivity. Several different core models are considered: axial-flow only, axial and lateral flow, asymmetry due to control rod insertion, and fuel heating (temperature -dependent cross sections). The thermal results generated by the MC21 thermal feedback module are consistent with expectations. Based upon the numerical experiments conducted it is concluded that the amount of spatial detail necessary to accurately capture the feedback effect on reactivity is relatively small. Homogenization at the assembly level for the Calvert Cliffs PWR model results in a similar power defect to that calculated with individual pin-cells modeled as explicit thermal regions. (authors)

  8. Monte Carlo Study of Patchy Nanostructures Self-Assembled from a Single Multiblock Chain

    E-Print Network [OSTI]

    Jakub Krajniak; Michal Banaszak

    2014-10-15T23:59:59.000Z

    We present a lattice Monte Carlo simulation for a multiblock copolymer chain of length N=240 and microarchitecture $(10-10)_{12}$.The simulation was performed using the Monte Carlo method with the Metropolis algorithm. We measured average energy, heat capacity, the mean squared radius of gyration, and the histogram of cluster count distribution. Those quantities were investigated as a function of temperature and incompatibility between segments, quantified by parameter {\\omega}. We determined the temperature of the coil-globule transition and constructed the phase diagram exhibiting a variety of patchy nanostructures. The presented results yield a qualitative agreement with those of the off-lattice Monte Carlo method reported earlier, with a significant exception for small incompatibilities,{\\omega}, and low temperatures, where 3-cluster patchy nanostructures are observed in contrast to the 2-cluster structures observed for the off-lattice $(10-10)_{12}$ chain. We attribute this difference to a considerable stiffness of lattice chains in comparison to that of the off-lattice chains.

  9. Magnetic stratigraphy and biostratigraphy of the Piacenzian (Upper Pliocene) at Monte San Nicola (Sicily)

    SciTech Connect (OSTI)

    Channell, J.E.T.; Sprovieri, R.; Di Stefano, E.

    1985-01-01T23:59:59.000Z

    During the Neogene, the Mediterranean was a rather unique biogeographic province. For this reason, first and last occurrences of Neogene species recorded in the Mediterranean region may not be synchronous with those recorded in the open oceans. This has important implications as most of the Neogene stage boundaries are defined on the basis of Mediterranean type sections. The most direct way to determine the relative timing of Mediterranean and open ocean datums is through correlation with the polarity time scale. Such correlations are not available for the Mediterranean Pliocene. The Trubi pelagic limestones and Monte narbone marls which characterize the SicilianPliocene are not ideal for magnetic stratigraphy due to weak remnant intensities and an ubiquitous normal polarity overprint. However, at Monte San Nicola, a magnetic stratigraphy has been resolved by stepwise demagnetization in small temperature increments. The upper and lower bounds of the Gauss Epoch, and the Mammoth and Kaena polarity events can be correlated to well defined planktonic foraminiferal and calcareous nannofossil datums. Hence the synchronism of these datums between the Mediterranean and the open ocean can be tested. The most notable discrepancy is in the last occurrence of G. margaritae which occurs at the base of the Gauss in most open marine sections, but is found at the top of the Gilbert at Monte San Nicola.

  10. Chemical Renal Denervation in the Rat

    SciTech Connect (OSTI)

    Consigny, Paul M., E-mail: paul.consigny@av.abbott.com; Davalian, Dariush, E-mail: dariush.davalian@av.abbott.com [Abbott Vascular, Innovation Incubator (United States); Donn, Rosy, E-mail: rosy.donn@av.abbott.com; Hu, Jie, E-mail: jie.hu@av.abbott.com [Abbott Vascular, Bioanalytical and Material Characterization (United States); Rieser, Matthew, E-mail: matthew.j.rieser@abbvie.com; Stolarik, DeAnne, E-mail: deanne.f.stolarik@abbvie.com [Abbvie, Analytical Pharmacology (United States)

    2013-12-03T23:59:59.000Z

    Introduction: The recent success of renal denervation in lowering blood pressure in drug-resistant hypertensive patients has stimulated interest in developing novel approaches to renal denervation including local drug/chemical delivery. The purpose of this study was to develop a rat model in which depletion of renal norepinephrine (NE) could be used to determine the efficacy of renal denervation after the delivery of a chemical to the periadventitial space of the renal artery. Methods: Renal denervation was performed on a single renal artery of 90 rats (n = 6 rats/group). The first study determined the time course of renal denervation after surgical stripping of a renal artery plus the topical application of phenol in alcohol. The second study determined the efficacy of periadventitial delivery of hypertonic saline, guanethidine, and salicylic acid. The final study determined the dose–response relationship for paclitaxel. In all studies, renal NE content was determined by liquid chromatography–mass spectrometry. Results: Renal NE was depleted 3 and 7 days after surgical denervation. Renal NE was also depleted by periadventitial delivery of all agents tested (hypertonic saline, salicylic acid, guanethidine, and paclitaxel). A dose response was observed after the application of 150 ?L of 10{sup ?5} M through 10{sup ?2} M paclitaxel. Conclusion: We developed a rat model in which depletion of renal NE was used to determine the efficacy of renal denervation after perivascular renal artery drug/chemical delivery. We validated this model by demonstrating the efficacy of the neurotoxic agents hypertonic saline, salicylic acid, and guanethidine and increasing doses of paclitaxel.

  11. A Monte-Carlo Method without Grid to Compute the Exchange Coefficient in the Double Porosity Model

    E-Print Network [OSTI]

    Boyer, Edmond

    Classification: 76S05 (65C05 76M35) Published in Monte Carlo Methods Appl.. 8:2, 129­147, 2002 Archives, links Methods and Applications 8, 2 (2002) 129-147" #12;F. Campillo and A. Lejay / A Monte Carlo Method witouth consists in transforming (1) into a system: m Pm t = a-Pm - (Pm - Pf), m = Meas(m) Meas() f Pf t = a

  12. Radiation doses in cone-beam breast computed tomography: A Monte Carlo simulation study

    SciTech Connect (OSTI)

    Yi Ying; Lai, Chao-Jen; Han Tao; Zhong Yuncheng; Shen Youtao; Liu Xinming; Ge Shuaiping; You Zhicheng; Wang Tianpeng; Shaw, Chris C. [Department of Imaging Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States)

    2011-02-15T23:59:59.000Z

    Purpose: In this article, we describe a method to estimate the spatial dose variation, average dose and mean glandular dose (MGD) for a real breast using Monte Carlo simulation based on cone beam breast computed tomography (CBBCT) images. We present and discuss the dose estimation results for 19 mastectomy breast specimens, 4 homogeneous breast models, 6 ellipsoidal phantoms, and 6 cylindrical phantoms. Methods: To validate the Monte Carlo method for dose estimation in CBBCT, we compared the Monte Carlo dose estimates with the thermoluminescent dosimeter measurements at various radial positions in two polycarbonate cylinders (11- and 15-cm in diameter). Cone-beam computed tomography (CBCT) images of 19 mastectomy breast specimens, obtained with a bench-top experimental scanner, were segmented and used to construct 19 structured breast models. Monte Carlo simulation of CBBCT with these models was performed and used to estimate the point doses, average doses, and mean glandular doses for unit open air exposure at the iso-center. Mass based glandularity values were computed and used to investigate their effects on the average doses as well as the mean glandular doses. Average doses for 4 homogeneous breast models were estimated and compared to those of the corresponding structured breast models to investigate the effect of tissue structures. Average doses for ellipsoidal and cylindrical digital phantoms of identical diameter and height were also estimated for various glandularity values and compared with those for the structured breast models. Results: The absorbed dose maps for structured breast models show that doses in the glandular tissue were higher than those in the nearby adipose tissue. Estimated average doses for the homogeneous breast models were almost identical to those for the structured breast models (p=1). Normalized average doses estimated for the ellipsoidal phantoms were similar to those for the structured breast models (root mean square (rms) percentage difference=1.7%; p=0.01), whereas those for the cylindrical phantoms were significantly lower (rms percentage difference=7.7%; p<0.01). Normalized MGDs were found to decrease with increasing glandularity. Conclusions: Our results indicate that it is sufficient to use homogeneous breast models derived from CBCT generated structured breast models to estimate the average dose. This investigation also shows that ellipsoidal digital phantoms of similar dimensions (diameter and height) and glandularity to actual breasts may be used to represent a real breast to estimate the average breast dose with Monte Carlo simulation. We have also successfully demonstrated the use of structured breast models to estimate the true MGDs and shown that the normalized MGDs decreased with the glandularity as previously reported by other researchers for CBBCT or mammography.

  13. Isoproterenol effects evaluated in heart slices of human and rat in comparison to rat heart in vivo

    SciTech Connect (OSTI)

    Herrmann, Julia E.; Heale, Jason; Bieraugel, Mike; Ramos, Meg [Drug Safety Evaluation, Allergan Inc., 2525 Dupont Dr, Irvine, CA 92612 (United States); Fisher, Robyn L. [Vitron Inc., Tucson, AZ (United States); Vickers, Alison E.M., E-mail: vickers_alison@allergan.com [Drug Safety Evaluation, Allergan Inc., 2525 Dupont Dr, Irvine, CA 92612 (United States)

    2014-01-15T23:59:59.000Z

    Human response to isoproterenol induced cardiac injury was evaluated by gene and protein pathway changes in human heart slices, and compared to rat heart slices and rat heart in vivo. Isoproterenol (10 and 100 ?M) altered human and rat heart slice markers of oxidative stress (ATP and GSH) at 24 h. In this in vivo rat study (0.5 mg/kg), serum troponin concentrations increased with lesion severity, minimal to mild necrosis at 24 and 48 h. In the rat and the human heart, isoproterenol altered pathways for apoptosis/necrosis, stress/energy, inflammation, and remodeling/fibrosis. The rat and human heart slices were in an apoptotic phase, while the in vivo rat heart exhibited necrosis histologically and further progression of tissue remodeling. In human heart slices genes for several heat shock 70 kD members were altered, indicative of stress to mitigate apoptosis. The stress response included alterations in energy utilization, fatty acid processing, and the up-regulation of inducible nitric oxide synthase, a marker of increased oxidative stress in both species. Inflammation markers linked with remodeling included IL-1?, Il-1?, IL-6 and TNF? in both species. Tissue remodeling changes in both species included increases in the TIMP proteins, inhibitors of matrix degradation, the gene/protein of IL-4 linked with cardiac fibrosis, and the gene Ccl7 a chemokine that induces collagen synthesis, and Reg3b a growth factor for cardiac repair. This study demonstrates that the initial human heart slice response to isoproterenol cardiac injury results in apoptosis, stress/energy status, inflammation and tissue remodeling at concentrations similar to that in rat heart slices. - Highlights: • Human response to isoproterenol induced cardiac injury evaluated in heart slices. • Isoproterenol altered apoptosis, energy, inflammation and remodeling pathways. • Human model verified by comparison to rat heart slices and rat heart in vivo. • Human and rat respond to isoproterenol at similar concentrations in vitro.

  14. Ser un resfro o ser la gripe? Sntomas Resfro Gripe

    E-Print Network [OSTI]

    Bandettini, Peter A.

    Molestia en el pecho, tos De leve a moderada; tos seca Con frecuencia; puede volverse severa Tratamiento

  15. A DELAYED NONLINEAR PBPK MODEL FOR GENISTEIN DOSIMETRY IN RATS

    E-Print Network [OSTI]

    A DELAYED NONLINEAR PBPK MODEL FOR GENISTEIN DOSIMETRY IN RATS #3; MICHAEL G. ZAGER y , HIEN T on laboratory animals and human volunteers [4], and critical literature reviews [32]. Phytoestrogens, a class endocrine-related e#11;ects such as reduced birth weight in rats and humans. In its conjugated form

  16. Measurement of Regional Lung Function in Rats Using Hyperpolarized 3

    E-Print Network [OSTI]

    Measurement of Regional Lung Function in Rats Using Hyperpolarized 3 Helium Dynamic MRI Ben T. Chen,* Anja C.S. Brau, and G. Allan Johnson Dynamic regional lung function was investigated in rats using by a constant flow ventila- tor. Based on regional differences in the behavior of inspired air, the lung

  17. Impacts of the Norway Rat on the auklet breeding colony at Sirius Point, Kiska

    E-Print Network [OSTI]

    Jones, Ian L.

    Impacts of the Norway Rat on the auklet breeding colony at Sirius Point, Kiska Island, Alaska-3239 FAX: (709) 737-3018 e-mail: x19hlm@mun.ca #12;Major and Jones Impacts of the Norway Rat... 2 Fresh rat during World War II (Atkinson, 1985). It is believed that the Norway Rat (Rattus norvegicus

  18. Hubble Space Telescope imaging and ground-based spectroscopy of old nova shells - I. FH Ser, V533 Her, BT Mon, DK Lac, V476 Cyg

    E-Print Network [OSTI]

    C. D. Gill; T. J. O'Brien

    2000-01-06T23:59:59.000Z

    In this paper we report on the first five out of eleven observations in our programme of Hubble Space Telescope (HST) imaging of old nova shells. We present new WFPC2 images of the shells around FH Ser and V533 Her taken in the F656N (Halpha+[NII]) filter. We also show long-slit spectra taken using the William Herschel Telescope (WHT) in La Palma for these objects in the same spectral range. The shell around FH Ser is found to be a prolate ellipsoid of ellipticity 1.3 +/- 0.1 inclined at 62 +/- 4 deg to the line of sight. The shell has an equatorial ring which is found to be due to increased emission in the two [NII] lines rather than Halpha. The expansion velocity, systemic velocity and distance are found to be 490 +/- 20 km/s, -45 km/s and 950 +/- 50 pc. The origin of the [NII] equatorial ring is discussed in the context of a photoionization feature resulting from aspherical illumination by the central source rather than a simple density enhancement. It is possible however that the ring is also in part due to an extremely localised increase in the nitrogen abundance. Similar imaging and spectroscopy of the nova V533 Her reveal a shell of radius 5 +/- 0.7 arcsec with an axial ratio of 1.2 +/- 0.2, expansion velocity of 850 +/- 150 km/s and distance 1250 +/- 300 pc. The shells around BT Mon, DK Lac and V476 Cyg were not detected with HST.

  19. Differential Expression of Cyclic Nucleotide Phosphodiesterases 4 in Developing Rat Lung Running Title: PDE4 in developing rat lung

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 Differential Expression of Cyclic Nucleotide Phosphodiesterases 4 in Developing Rat Lung Running Title: PDE4 in developing rat lung Emmanuel Lopez 1,2,3,4 , Pierre-Henri Jarreau 1,2,3,4 , Elodie Zana 1 Dynamics 239, 9 (2010) 2470-8" DOI : 10.1002/dvdy.22374 #12;2 Abstract During the perinatal period, lungs

  20. Microsoft Word - S07817_SER

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA group currentBradleyTableSelling7 August 2008 Office of LegacyDraft Calendar

  1. Charged-Particle Thermonuclear Reaction Rates: I. Monte Carlo Method and Statistical Distributions

    E-Print Network [OSTI]

    Richard Longland; Christian Iliadis; Art Champagne; Joe Newton; Claudio Ugalde; Alain Coc; Ryan Fitzgerald

    2010-04-23T23:59:59.000Z

    A method based on Monte Carlo techniques is presented for evaluating thermonuclear reaction rates. We begin by reviewing commonly applied procedures and point out that reaction rates that have been reported up to now in the literature have no rigorous statistical meaning. Subsequently, we associate each nuclear physics quantity entering in the calculation of reaction rates with a specific probability density function, including Gaussian, lognormal and chi-squared distributions. Based on these probability density functions the total reaction rate is randomly sampled many times until the required statistical precision is achieved. This procedure results in a median (Monte Carlo) rate which agrees under certain conditions with the commonly reported recommended "classical" rate. In addition, we present at each temperature a low rate and a high rate, corresponding to the 0.16 and 0.84 quantiles of the cumulative reaction rate distribution. These quantities are in general different from the statistically meaningless "minimum" (or "lower limit") and "maximum" (or "upper limit") reaction rates which are commonly reported. Furthermore, we approximate the output reaction rate probability density function by a lognormal distribution and present, at each temperature, the lognormal parameters miu and sigma. The values of these quantities will be crucial for future Monte Carlo nucleosynthesis studies. Our new reaction rates, appropriate for bare nuclei in the laboratory, are tabulated in the second paper of this series (Paper II). The nuclear physics input used to derive our reaction rates is presented in the third paper of this series (Paper III). In the fourth paper of this series (Paper IV) we compare our new reaction rates to previous results.

  2. Monte Carlo calculations of the physical properties of RDX, {beta}-HMX, and TATB

    SciTech Connect (OSTI)

    Sewell, T.D.

    1997-09-01T23:59:59.000Z

    Atomistic Monte Carlo simulations in the NpT ensemble are used to calculate the physical properties of crystalline RDX, {beta}-HMX, and TATB. Among the issues being considered are the effects of various treatments of the intermolecular potential, inclusion of intramolecular flexibility, and simulation size dependence of the results. Calculations of the density, lattice energy, and lattice parameters are made over a wide range of pressures; thereby allowing for predictions of the bulk and linear coefficients of isothermal expansion of the crystals. Comparison with experiment is made where possible.

  3. SIM-RIBRAS: A Monte-Carlo simulation package for RIBRAS system

    SciTech Connect (OSTI)

    Leistenschneider, E.; Lepine-Szily, A.; Lichtenthaeler, R. [Departamento de Fisica Nuclear, Instituto de Fisica, Universidade de Sao Paulo (Brazil)

    2013-05-06T23:59:59.000Z

    SIM-RIBRAS is a Root-based Monte-Carlo simulation tool designed to help RIBRAS users on experience planning and experimental setup enhancing and caracterization. It is divided into two main programs: CineRIBRAS, aiming beam kinematics, and SolFocus, aiming beam optics. SIM-RIBRAS replaces other methods and programs used in the past, providing more complete and accurate results and requiring much less manual labour. Moreover, the user can easily make modifications in the codes, adequating it for specific requirements of an experiment.

  4. Monte-Carlo study of the phase transition in the AA-stacked bilayer graphene

    E-Print Network [OSTI]

    A. A. Nikolaev; M. V. Ulybyshev

    2014-12-04T23:59:59.000Z

    Tight-binding model of the AA-stacked bilayer graphene with screened electron-electron interactions has been studied using the Hybrid Monte Carlo simulations on the original double-layer hexagonal lattice. Instantaneous screened Coulomb potential is taken into account using Hubbard-Stratonovich transformation. G-type antiferromagnetic ordering has been studied and the phase transition with spontaneous generation of the mass gap has been observed. Dependence of the antiferromagnetic condensate on the on-site electron-electron interaction is examined.

  5. Temperature-extrapolation method for Implicit Monte Carlo - Radiation hydrodynamics calculations

    SciTech Connect (OSTI)

    McClarren, R. G. [Department of Nuclear Engineering, Texas A and M University, 3133 TAMU, College Station, TX 77802 (United States); Urbatsch, T. J. [XTD-5: Air Force Systems, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 77845 (United States)

    2013-07-01T23:59:59.000Z

    We present a method for implementing temperature extrapolation in Implicit Monte Carlo solutions to radiation hydrodynamics problems. The method is based on a BDF-2 type integration to estimate a change in material temperature over a time step. We present results for radiation only problems in an infinite medium and for a 2-D Cartesian hohlraum problem. Additionally, radiation hydrodynamics simulations are presented for an RZ hohlraum problem and a related 3D problem. Our results indicate that improvements in noise and general behavior are possible. We present considerations for future investigations and implementations. (authors)

  6. An Efficient Monte Carlo Algorithm for a Restricted Class of Scattering Problems in Radiation Transfer

    E-Print Network [OSTI]

    Alan M. Watson; William J. Henney

    2001-08-30T23:59:59.000Z

    We describe an efficient Monte Carlo algorithm for a restricted class of scattering problems in radiation transfer. This class includes many astrophysically interesting problems, including the scattering of ultraviolet and visible light by grains. The algorithm correctly accounts for multiply-scattered light. We describe the algorithm, present a number of important optimizations, and explicity show how the algorithm can be used to estimate quantities such as the emergent and mean intensity. We present two test cases, examine the importance of the optimizations, and show that this algorithm can be usefully applied to optically-thin problems, a regime sometimes considered limited to explicit single-scattering plus attenuation approximations.

  7. A new approach to hot particle dosimetry using a Monte Carlo transport code

    E-Print Network [OSTI]

    Busche, Donna Marie

    1989-01-01T23:59:59.000Z

    Ci-hrs. This value assumes a threshold dose of 2000 rads to an area of 0. 1 cm&, at a depth of 100 ltm (NCRP 1988). The purpose of this research was evaluate the current methods used in industry to assess the doses from hot particles. A Monte Carlo electron... radioactivity being released from the site. Frisking, portal monitors, and step off pads are important HP areas and should involve overview and supervision. IDENTMCATION To properly assess the dose from these hot particles, the source strength, type...

  8. A VAX version of the coupled Monte Carlo transport codes HETC and MORSE-CGA

    SciTech Connect (OSTI)

    Sanna, R.S.

    1990-12-01T23:59:59.000Z

    The three-dimensional Monte Carlo transport codes, HETC and MORSE-CGA, are distributed by the Radiation Shielding Information Center at Oak Ridge National Laboratory. These codes, written for IBM-3033 computers, have been installed on the Environmental Measurements Laboratory's VAX/11-750 computer for operation in a coupled mode to study the transport of neutrons over the energy range from thermal to several GeV. This report is a guide to their use on the VAX/11-750 computer. 26 refs., 6 figs., 14 tabs.

  9. Replica-exchange Wang Landau sampling: pushing the limits of Monte Carlo simulations in materials sciences

    SciTech Connect (OSTI)

    Perera, Meewanage Dilina N [ORNL; Li, Ying Wai [ORNL; Eisenbach, Markus [ORNL; Vogel, Thomas [Los Alamos National Laboratory (LANL); Landau, David P [University of Georgia, Athens, GA

    2015-01-01T23:59:59.000Z

    We describe the study of thermodynamics of materials using replica-exchange Wang Landau (REWL) sampling, a generic framework for massively parallel implementations of the Wang Landau Monte Carlo method. To evaluate the performance and scalability of the method, we investigate the magnetic phase transition in body-centered cubic (bcc) iron using the classical Heisenberg model parameterized with first principles calculations. We demonstrate that our framework leads to a significant speedup without compromising the accuracy and precision and facilitates the study of much larger systems than is possible with its serial counterpart.

  10. Monte Carlo Generators for Studies of the 3D Structure of the Nucleon

    SciTech Connect (OSTI)

    Avagyan, Harut A. [JLAB

    2015-01-01T23:59:59.000Z

    Extraction of transverse momentum and space distributions of partons from measurements of spin and azimuthal asymmetries requires development of a self consistent analysis framework, accounting for evolution effects, and allowing control of systematic uncertainties due to variations of input parameters and models. Development of realistic Monte-Carlo generators, accounting for TMD evolution effects, spin-orbit and quark-gluon correlations will be crucial for future studies of quark-gluon dynamics in general and 3D structure of the nucleon in particular.

  11. Probability of initiation and extinction in the Mercury Monte Carlo code

    SciTech Connect (OSTI)

    McKinley, M. S.; Brantley, P. S. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94551 (United States)

    2013-07-01T23:59:59.000Z

    A Monte Carlo method for computing the probability of initiation has previously been implemented in Mercury. Recently, a new method based on the probability of extinction has been implemented as well. The methods have similarities from counting progeny to cycling in time, but they also have differences such as population control and statistical uncertainty reporting. The two methods agree very well for several test problems. Since each method has advantages and disadvantages, we currently recommend that both methods are used to compute the probability of criticality. (authors)

  12. Estimation of 6 groups of effective delayed neutron fraction based on continuous energy Monte Carlo method

    SciTech Connect (OSTI)

    Nauchi, Y.; Kameyama, T. [Central Research Inst., Electric Power Industry, 2-11-1 Iwado-Kita, Komae-shi, Tokyo 201-8511 (Japan)

    2006-07-01T23:59:59.000Z

    New method is proposed to estimate effective fraction of delayed neutrons radiated from precursors categorized into 6 groups of decay constant. Instead of adjoint flux {Phi}*, an expected number of fission neutrons in next generations, M, is applied as a weight function [1]. Introduction of M enables us to calculate the fraction based on continuous energy Monte Carlo method. For the calculation of the fraction, an algorithm is established and implemented into the MCNP-5 code. The method is verified using reactor period data obtained in reactivity measurements. (authors)

  13. Finite-temperature quantum Monte Carlo study of the one-dimensional polarized Fermi gas

    SciTech Connect (OSTI)

    Wolak, M. J. [Centre for Quantum Technologies, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Rousseau, V. G. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Miniatura, C. [Centre for Quantum Technologies, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); INLN, Universite de Nice-Sophia Antipolis, CNRS, 1361 route des Lucioles, F-06560 Valbonne (France); Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Gremaud, B. [Centre for Quantum Technologies, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Laboratoire Kastler Brossel, UPMC-Paris 6, ENS, CNRS, 4 Place Jussieu, F-75005 Paris (France); Scalettar, R. T. [Physics Department, University of California, Davis, California 95616 (United States); Batrouni, G. G. [Centre for Quantum Technologies, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); INLN, Universite de Nice-Sophia Antipolis, CNRS, 1361 route des Lucioles, F-06560 Valbonne (France)

    2010-07-15T23:59:59.000Z

    Quantum Monte Carlo (QMC) techniques are used to provide an approximation-free investigation of the phases of the one-dimensional attractive Hubbard Hamiltonian in the presence of population imbalance. The temperature at which the ''Fulde-Ferrell-Larkin-Ovchinnikov'' (FFLO) phase is destroyed by thermal fluctuations is determined as a function of the polarization. It is shown that the presence of a confining potential does not dramatically alter the FFLO regime and that recent experiments on trapped atomic gases likely lie just within the stable temperature range.

  14. Monte-Carlo Simulation of Exclusive Channels in e+e- Annihilation at Low Energy

    E-Print Network [OSTI]

    D. Anipko; S. Eidelman; A. Pak

    2003-12-25T23:59:59.000Z

    Software package for Monte-Carlo simulation of e+e- exclusive annihilation channels written in the C++ language for Linux/Solaris platforms has been developed. It incorporates matrix elements for several mechanisms of multipion production in a model of consequent two and three-body resonance decays. Possible charge states of intermediate and final particles are accounted automatically under the assumption of isospin conservation. Interference effects can be taken into acccount. Package structure allows adding new matrix elements written in a gauge-invariant form.

  15. A Monte Carlo study of the distribution of parameter estimators in a dual exponential decay model

    E-Print Network [OSTI]

    Garcia, Raul

    1969-01-01T23:59:59.000Z

    of an estimate of the reliability of the parameter estimates calculated. In 1965, Bell and Garcia [2] developed a computer program which permits a solution of the parameters without the time-consuming effort of manual calcu- lations. The same year, Rossing [3...A MONTE CARLO STUDY OF THE DISTRIBUTION OF PARAMETER ESTIMATORS IN A DUAL EXPONENTIAL DECAY MODEL A Thesis by SAUL GARCIA Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirements for the degree...

  16. Kinetic lattice Monte Carlo simulations of interdiffusion in strained silicon germanium alloys

    SciTech Connect (OSTI)

    Chen, Renyu; Dunham, Scott T.

    2010-03-03T23:59:59.000Z

    Point-defect-mediated diffusion processes are investigated in strained SiGe alloys using kinetic lattice Monte Carlo *KLMC* simulation technique. The KLMC simulator incorporates an augmented lattice domain and includes defect structures, atomistic hopping mechanisms, and the stress dependence of transition rates obtained from density functional theory calculation results. Vacancy-mediated interdiffusion in strained SiGe alloys is analyzed, and the stress effect caused by the induced strain of germanium is quantified separately from that due to germanium-vacancy binding. The results indicate that both effects have substantial impact on interdiffusion. © 2010 American Vacuum Society.

  17. Thermonuclear reaction rate of $^{18}$Ne($?$,$p$)$^{21}$Na from Monte-Carlo calculations

    E-Print Network [OSTI]

    P. Mohr; R. Longland; C. Iliadis

    2014-12-14T23:59:59.000Z

    The $^{18}$Ne($\\alpha$,$p$)$^{21}$Na reaction impacts the break-out from the hot CNO-cycles to the $rp$-process in type I X-ray bursts. We present a revised thermonuclear reaction rate, which is based on the latest experimental data. The new rate is derived from Monte-Carlo calculations, taking into account the uncertainties of all nuclear physics input quantities. In addition, we present the reaction rate uncertainty and probability density versus temperature. Our results are also consistent with estimates obtained using different indirect approaches.

  18. Thermonuclear reaction rate of $^{18}$Ne($\\alpha$,$p$)$^{21}$Na from Monte-Carlo calculations

    E-Print Network [OSTI]

    Mohr, P; Iliadis, C

    2014-01-01T23:59:59.000Z

    The $^{18}$Ne($\\alpha$,$p$)$^{21}$Na reaction impacts the break-out from the hot CNO-cycles to the $rp$-process in type I X-ray bursts. We present a revised thermonuclear reaction rate, which is based on the latest experimental data. The new rate is derived from Monte-Carlo calculations, taking into account the uncertainties of all nuclear physics input quantities. In addition, we present the reaction rate uncertainty and probability density versus temperature. Our results are also consistent with estimates obtained using different indirect approaches.

  19. Toxicologic and biochemical effects of extracts from Karwinskia humboldtiana on the albino rat

    E-Print Network [OSTI]

    Wheeler, Michael Hugh

    1970-01-01T23:59:59.000Z

    Oral doses of coyotillo plant extract (Pe-1) given to rats of Group I-A. 12 Weight changes observed in rats following oral administration of coyotillo plant extract (Pe-l). Microscopic lesions observed in rats following oral administration... of coyotillo plant extract (Pe-l). Weight changes observed in rats following chronic oral administration of coyotillo plant extract (Cn-l). 37 Weight changes observed in rats following acute oral administration of coyotillo plant extract (Ch-l). 38...

  20. Post-transcriptional modifications of Ser15 Thr18 Ser20 Ser155

    E-Print Network [OSTI]

    Bedwell, David M.

    used · Dox(doxorubicin): a DNA-damaging agent that is known to stabilize p53 · STZ(streptozotocin): an O-GlacNacase inhibitor. Effiect of Dox/STZ treatment on accumulation and O-GlcNAcylation of p53 #12;3 Effiect of Dox/STZ treatment on accumulation and O-GlcNAcylation of p53 Transcriptional level? O

  1. An Evaluation of Monte Carlo Simulations of Neutron Multiplicity Measurements of Plutonium Metal

    SciTech Connect (OSTI)

    Mattingly, John [North Carolina State University; Miller, Eric [University of Michigan; Solomon, Clell J. Jr. [Los Alamos National Laboratory; Dennis, Ben [University of Michigan; Meldrum, Amy [University of Michigan; Clarke, Shaun [University of Michigan; Pozzi, Sara [University of Michigan

    2012-06-21T23:59:59.000Z

    In January 2009, Sandia National Laboratories conducted neutron multiplicity measurements of a polyethylene-reflected plutonium metal sphere. Over the past 3 years, those experiments have been collaboratively analyzed using Monte Carlo simulations conducted by University of Michigan (UM), Los Alamos National Laboratory (LANL), Sandia National Laboratories (SNL), and North Carolina State University (NCSU). Monte Carlo simulations of the experiments consistently overpredict the mean and variance of the measured neutron multiplicity distribution. This paper presents a sensitivity study conducted to evaluate the potential sources of the observed errors. MCNPX-PoliMi simulations of plutonium neutron multiplicity measurements exhibited systematic over-prediction of the neutron multiplicity distribution. The over-prediction tended to increase with increasing multiplication. MCNPX-PoliMi had previously been validated against only very low multiplication benchmarks. We conducted sensitivity studies to try to identify the cause(s) of the simulation errors; we eliminated the potential causes we identified, except for Pu-239 {bar {nu}}. A very small change (-1.1%) in the Pu-239 {bar {nu}} dramatically improved the accuracy of the MCNPX-PoliMi simulation for all 6 measurements. This observation is consistent with the trend observed in the bias exhibited by the MCNPX-PoliMi simulations: a very small error in {bar {nu}} is 'magnified' by increasing multiplication. We applied a scalar adjustment to Pu-239 {bar {nu}} (independent of neutron energy); an adjustment that depends on energy is probably more appropriate.

  2. A Deterministic-Monte Carlo Hybrid Method for Time-Dependent Neutron Transport Problems

    SciTech Connect (OSTI)

    Justin Pounders; Farzad Rahnema

    2001-10-01T23:59:59.000Z

    A new deterministic-Monte Carlo hybrid solution technique is derived for the time-dependent transport equation. This new approach is based on dividing the time domain into a number of coarse intervals and expanding the transport solution in a series of polynomials within each interval. The solutions within each interval can be represented in terms of arbitrary source terms by using precomputed response functions. In the current work, the time-dependent response function computations are performed using the Monte Carlo method, while the global time-step march is performed deterministically. This work extends previous work by coupling the time-dependent expansions to space- and angle-dependent expansions to fully characterize the 1D transport response/solution. More generally, this approach represents and incremental extension of the steady-state coarse-mesh transport method that is based on global-local decompositions of large neutron transport problems. An example of a homogeneous slab is discussed as an example of the new developments.

  3. The Proton Therapy Nozzles at Samsung Medical Center: A Monte Carlo Simulation Study using TOPAS

    E-Print Network [OSTI]

    Chung, Kwangzoo; Kim, Dae-Hyun; Ahn, Sunghwan; Han, Youngyih

    2015-01-01T23:59:59.000Z

    To expedite the commissioning process of the proton therapy system at Samsung Medical Center (SMC), we have developed a Monte Carlo simulation model of the proton therapy nozzles using TOPAS. At SMC proton therapy center, we have two gantry rooms with different types of nozzles; a multi-purpose nozzle and a dedicated scanning nozzle. Each nozzle has been modeled in detail following the geometry information provided by the manufacturer, Sumitomo Heavy Industries, Ltd. For this purpose, novel features of TOPAS, such as the time feature or the ridge filter class, have been used. And the appropriate physics models for proton nozzle simulation were defined. Dosimetric properties, like percent depth dose curve, spread-out Bragg peak (SOBP), beam spot size, have been simulated and verified against measured beam data. Beyond the Monte Carlo nozzle modeling, we have developed an interface between TOPAS and the treatment planning system (TPS), RayStation. An exported RT plan data from the TPS has been interpreted by th...

  4. Bias-Variance Techniques for Monte Carlo Optimization: Cross-validation for the CE Method

    E-Print Network [OSTI]

    Rajnarayan, Dev

    2008-01-01T23:59:59.000Z

    In this paper, we examine the CE method in the broad context of Monte Carlo Optimization (MCO) and Parametric Learning (PL), a type of machine learning. A well-known overarching principle used to improve the performance of many PL algorithms is the bias-variance tradeoff. This tradeoff has been used to improve PL algorithms ranging from Monte Carlo estimation of integrals, to linear estimation, to general statistical estimation. Moreover, as described by, MCO is very closely related to PL. Owing to this similarity, the bias-variance tradeoff affects MCO performance, just as it does PL performance. In this article, we exploit the bias-variance tradeoff to enhance the performance of MCO algorithms. We use the technique of cross-validation, a technique based on the bias-variance tradeoff, to significantly improve the performance of the Cross Entropy (CE) method, which is an MCO algorithm. In previous work we have confirmed that other PL techniques improve the perfomance of other MCO algorithms. We conclude that ...

  5. Monte Carlo uncertainty reliability and isotope production calculations for a fast reactor

    SciTech Connect (OSTI)

    Miles, T.L.

    1992-01-01T23:59:59.000Z

    Statistical uncertainties in Monte Carlo calculations are typically determined by the first and second moments of the tally. For certain types of calculations, there is concern that the uncertainty estimate is significantly non-conservative. This is typically seen in reactor eigenvalue problems where the uncertainty estimate is aggravated by the generation-to-generation fission source. It has been speculated that optimization of the random walk, through biasing techniques, may increase the non-conservative nature of the uncertainty estimate. A series of calculations are documented here which quantify the reliability of the Monte Carlo Neutron and Photon (MCNP) mean and uncertainty estimates by comparing these estimates to the true mean. These calculations were made with a liquid metal fast reactor model, but every effort was made to isolate the statistical nature of the uncertainty estimates so that the analysis of the reliability of the MCNP estimates should be relevant for small thermal reactors as well. Also, preliminary reactor physics calculations for two different special isotope production test assemblies for irradiation in the Fast Flux Test Facility (FFTF) were performed using MCNP and are documented here. The effect of an yttrium-hydride moderator to tailor the neutron flux incident on the targets to maximize isotope production for different designs in different locations within the reactor is discussed. These calculations also demonstrate the useful application of MCNP in design iterations by utilizing many of the codes features.

  6. Energy density matrix formalism for interacting quantum systems: a quantum Monte Carlo study

    SciTech Connect (OSTI)

    Krogel, Jaron T [ORNL] [ORNL; Kim, Jeongnim [ORNL] [ORNL; Reboredo, Fernando A [ORNL] [ORNL

    2014-01-01T23:59:59.000Z

    We develop an energy density matrix that parallels the one-body reduced density matrix (1RDM) for many-body quantum systems. Just as the density matrix gives access to the number density and occupation numbers, the energy density matrix yields the energy density and orbital occupation energies. The eigenvectors of the matrix provide a natural orbital partitioning of the energy density while the eigenvalues comprise a single particle energy spectrum obeying a total energy sum rule. For mean-field systems the energy density matrix recovers the exact spectrum. When correlation becomes important, the occupation energies resemble quasiparticle energies in some respects. We explore the occupation energy spectrum for the finite 3D homogeneous electron gas in the metallic regime and an isolated oxygen atom with ground state quantum Monte Carlo techniques imple- mented in the QMCPACK simulation code. The occupation energy spectrum for the homogeneous electron gas can be described by an effective mass below the Fermi level. Above the Fermi level evanescent behavior in the occupation energies is observed in similar fashion to the occupation numbers of the 1RDM. A direct comparison with total energy differences demonstrates a quantita- tive connection between the occupation energies and electron addition and removal energies for the electron gas. For the oxygen atom, the association between the ground state occupation energies and particle addition and removal energies becomes only qualitative. The energy density matrix provides a new avenue for describing energetics with quantum Monte Carlo methods which have traditionally been limited to total energies.

  7. Using Monte Carlo analyses in uptake models for evaluating risks to ecological receptors

    SciTech Connect (OSTI)

    Hayse, J.W.; Hlohowskyj, I. [Argonne National Lab., IL (United States). Environmental Assessment Div.

    1995-12-31T23:59:59.000Z

    A deterministic modeling approach was used to evaluate risks to wildlife receptors at a contaminated site in Maryland. Models to predict daily doses of contaminants to ecological receptors used single point estimates for media contaminant concentrations and for ecological exposure factors. Predicted doses exceeding contaminant- and species-specific dose values were considered to be indicative of adverse risk, and the model results are being used to develop and evaluate remedial alternatives for the site. Risk estimates based on the deterministic approach predicted daily contaminant doses exceeding acceptable dose levels for more than half of the modeled receptors. Ecological risks were also evaluated using a stochastic approach. In this approach the input parameters that most greatly affected the deterministic model outcome were identified using sensitivity analyses. Statistical distributions were assigned to these parameters, and Monte Carlo simulations of the models were conducted to generate probability density functions of contaminant doses. The resulting probability density functions were then used to quantify the probability that contaminant uptake would exceed the acceptable dose values. Models using Monte Carlo analyses identified only a low probability of exceeding the acceptable dose level for most of the contaminants and receptors. The differences in the risks predicted using the deterministic and stochastic models would likely result in the selection of different remediation goals and actions for the same area of contamination. Given the different interpretations that could result from these two modeling approaches, the authors recommend that both techniques be considered for estimating risks to ecological receptors.

  8. Massively parallel Monte Carlo for many-particle simulations on GPUs

    SciTech Connect (OSTI)

    Anderson, Joshua A.; Jankowski, Eric [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)] [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Grubb, Thomas L. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)] [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Engel, Michael [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)] [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Glotzer, Sharon C., E-mail: sglotzer@umich.edu [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)

    2013-12-01T23:59:59.000Z

    Current trends in parallel processors call for the design of efficient massively parallel algorithms for scientific computing. Parallel algorithms for Monte Carlo simulations of thermodynamic ensembles of particles have received little attention because of the inherent serial nature of the statistical sampling. In this paper, we present a massively parallel method that obeys detailed balance and implement it for a system of hard disks on the GPU. We reproduce results of serial high-precision Monte Carlo runs to verify the method. This is a good test case because the hard disk equation of state over the range where the liquid transforms into the solid is particularly sensitive to small deviations away from the balance conditions. On a Tesla K20, our GPU implementation executes over one billion trial moves per second, which is 148 times faster than on a single Intel Xeon E5540 CPU core, enables 27 times better performance per dollar, and cuts energy usage by a factor of 13. With this improved performance we are able to calculate the equation of state for systems of up to one million hard disks. These large system sizes are required in order to probe the nature of the melting transition, which has been debated for the last forty years. In this paper we present the details of our computational method, and discuss the thermodynamics of hard disks separately in a companion paper.

  9. Physics and Algorithm Enhancements for a Validated MCNP/X Monte Carlo Simulation Tool, Phase VII

    SciTech Connect (OSTI)

    McKinney, Gregg W [Los Alamos National Laboratory

    2012-07-17T23:59:59.000Z

    Currently the US lacks an end-to-end (i.e., source-to-detector) radiation transport simulation code with predictive capability for the broad range of DHS nuclear material detection applications. For example, gaps in the physics, along with inadequate analysis algorithms, make it difficult for Monte Carlo simulations to provide a comprehensive evaluation, design, and optimization of proposed interrogation systems. With the development and implementation of several key physics and algorithm enhancements, along with needed improvements in evaluated data and benchmark measurements, the MCNP/X Monte Carlo codes will provide designers, operators, and systems analysts with a validated tool for developing state-of-the-art active and passive detection systems. This project is currently in its seventh year (Phase VII). This presentation will review thirty enhancements that have been implemented in MCNPX over the last 3 years and were included in the 2011 release of version 2.7.0. These improvements include 12 physics enhancements, 4 source enhancements, 8 tally enhancements, and 6 other enhancements. Examples and results will be provided for each of these features. The presentation will also discuss the eight enhancements that will be migrated into MCNP6 over the upcoming year.

  10. Monte Carlo methods and their analysis for Coulomb collisions in multicomponent plasmas

    SciTech Connect (OSTI)

    Bobylev, A.V., E-mail: alexander.bobylev@kau.se [Department of Mathematics, Karlstad University, SE-65188 Karlstad (Sweden); Potapenko, I.F., E-mail: firena@yandex.ru [Keldysh Institute for Applied Mathematics, RAS, 125047 Moscow (Russian Federation)

    2013-08-01T23:59:59.000Z

    Highlights: •A general approach to Monte Carlo methods for multicomponent plasmas is proposed. •We show numerical tests for the two-component (electrons and ions) case. •An optimal choice of parameters for speeding up the computations is discussed. •A rigorous estimate of the error of approximation is proved. -- Abstract: A general approach to Monte Carlo methods for Coulomb collisions is proposed. Its key idea is an approximation of Landau–Fokker–Planck equations by Boltzmann equations of quasi-Maxwellian kind. It means that the total collision frequency for the corresponding Boltzmann equation does not depend on the velocities. This allows to make the simulation process very simple since the collision pairs can be chosen arbitrarily, without restriction. It is shown that this approach includes the well-known methods of Takizuka and Abe (1977) [12] and Nanbu (1997) as particular cases, and generalizes the approach of Bobylev and Nanbu (2000). The numerical scheme of this paper is simpler than the schemes by Takizuka and Abe [12] and by Nanbu. We derive it for the general case of multicomponent plasmas and show some numerical tests for the two-component (electrons and ions) case. An optimal choice of parameters for speeding up the computations is also discussed. It is also proved that the order of approximation is not worse than O(?(?)), where ? is a parameter of approximation being equivalent to the time step ?t in earlier methods. A similar estimate is obtained for the methods of Takizuka and Abe and Nanbu.

  11. A Monte Carlo Study of Multiplicity Fluctuations in Pb-Pb Collisions at LHC Energies

    E-Print Network [OSTI]

    Ramni Gupta

    2015-01-15T23:59:59.000Z

    With large volumes of data available from LHC, it has become possible to study the multiplicity distributions for the various possible behaviours of the multiparticle production in collisions of relativistic heavy ion collisions, where a system of dense and hot partons has been created. In this context it is important and interesting as well to check how well the Monte Carlo generators can describe the properties or the behaviour of multiparticle production processes. One such possible behaviour is the self-similarity in the particle production, which can be studied with the intermittency studies and further with chaoticity/erraticity, in the heavy ion collisions. We analyse the behaviour of erraticity index in central Pb-Pb collisions at centre of mass energy of 2.76 TeV per nucleon using the AMPT monte carlo event generator, following the recent proposal by R.C. Hwa and C.B. Yang, concerning the local multiplicity fluctuation study as a signature of critical hadronization in heavy-ion collisions. We report the values of erraticity index for the two versions of the model with default settings and their dependence on the size of the phase space region. Results presented here may serve as a reference sample for the experimental data from heavy ion collisions at these energies.

  12. Acceleration of wound healing in young and aged rats 

    E-Print Network [OSTI]

    Maxwell, Bryan Douglas

    1996-01-01T23:59:59.000Z

    1. The effect of ACM on wound healing in young rats. . Page 15 2. The effect of ACM on wound healing in old, ad-lib rats . . . . . . . 17 3. The effect of ACM on wound healing in old, caloric-restricted rats . . . 4. The effect of old and young... group (AL) had been fed a laboratory diet ad libitum during their lifetime. The other group (CR) had been maintained on a calorie-restricted diet at a level of 60% of the food intake of the ad libitum-fed group. This decrease in caloric intake resulted...

  13. Study on in situ calibration for neutron flux monitor in the Large Helical Device based on Monte Carlo calculations

    SciTech Connect (OSTI)

    Nakano, Y., E-mail: nakano.yuuji@c.mbox.nagoya-u.ac.jp; Yamazaki, A.; Watanabe, K.; Uritani, A. [Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan); Ogawa, K.; Isobe, M. [National Institute for Fusion Science, Toki-city, GIFU 509-5292 (Japan)

    2014-11-15T23:59:59.000Z

    Neutron monitoring is important to manage safety of fusion experiment facilities because neutrons are generated in fusion reactions. Monte Carlo simulations play an important role in evaluating the influence of neutron scattering from various structures and correcting differences between deuterium plasma experiments and in situ calibration experiments. We evaluated these influences based on differences between the both experiments at Large Helical Device using Monte Carlo simulation code MCNP5. A difference between the both experiments in absolute detection efficiency of the fission chamber between O-ports is estimated to be the biggest of all monitors. We additionally evaluated correction coefficients for some neutron monitors.

  14. awake rats achieving: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Studies of Brain Function in Awake Rats CiteSeer Summary: Positron emission tomography (PET) is a non-invasive molecular imaging technique using positron-emitting radioisotopes to...

  15. adult rats rattus: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 IMPACTS OF INTRODUCED NORWAY RATS (RATTUS NORVEGICUS) ON LEAST AUKLETS (AETHIA PUSILLA) BREEDING AT KISKA ISLAND,...

  16. Surface tension of an electrolyteair interface: a Monte Carlo study This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-Print Network [OSTI]

    Levin, Yan

    Surface tension of an electrolyte­air interface: a Monte Carlo study This article has been 24 (2012) 284115 (5pp) doi:10.1088/0953-8984/24/28/284115 Surface tension of an electrolyte for calculating the surface tension of an electrolyte­air interface using Monte Carlo (MC) simulations

  17. Experimental Study and Monte Carlo Modeling of Calcium Borosilicate Glasses Leaching

    SciTech Connect (OSTI)

    Arab, Mehdi; Cailleteau, Celine; Angeli, Frederic [CEA/DTCD/SECM/Laboratoire d'etudes du Comportement a Long Terme, CEA Centre Valrho, BP 17171, Bagnols-sur-ceze, 30207 (France); Devreux, Francois [Laboratoire de Physique de la Matiere Condensee, CNRS and Ecole Polytechnique, Palaiseau Cedex, 91128 (France)

    2007-07-01T23:59:59.000Z

    During aqueous alteration of glass an alteration layer appears on the glass surface. The properties of this alteration layer are of great importance for understanding and predicting the long-term behavior of high-level radioactive waste glasses. Numerical modeling can be very useful for understanding the impact of the glass composition on its aqueous reactivity and long-term properties but it is quite difficult to model these complex glasses. In order to identify the effect of the calcium content on glass alteration, seven oxide glass compositions (57SiO{sub 2} 17B{sub 2}O{sub 3} (22-x)Na{sub 2}O{sub x}CaO 4ZrO{sub 2}; 0 < x < 11) were investigated and a Monte Carlo model was developed to describe their leaching behavior. The specimens were altered at constant temperature (T = 90 deg. C) at a glass-surface-area-to-solution-volume (SA/V) ratio of 15 cm-1 in a buffered solution (pH 9.2). Under these conditions all the variations observed in the leaching behavior are attributable to composition effects. Increasing the calcium content in the glass appears to be responsible for a sharp drop in the final leached boron fraction. In parallel with this experimental work, a Monte Carlo model was developed to investigate the effect of calcium content on the leaching behavior especially on the initial stage of alteration. Monte Carlo simulations performed with this model are in good agreement with the experimental results. The dependence of the alteration rate on the calcium content can be described by a quadratic function: fitting the simulated points gives a minimum alteration rate at about 7.7 mol% calcium. This value is consistent with the figure of 8.2 mol% obtained from the experimental work. The model was also used to investigate the role of calcium in the glass structure and it pointed out that calcium act preferentially as a network modifier rather than a charge compensator in this kind of glasses. (authors)

  18. Organ doses for reference adult male and female undergoing computed tomography estimated by Monte Carlo simulations

    SciTech Connect (OSTI)

    Lee, Choonsik; Kim, Kwang Pyo; Long, Daniel; Fisher, Ryan; Tien, Chris; Simon, Steven L.; Bouville, Andre; Bolch, Wesley E. [Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institute of Health, Bethesda, Maryland 20852 (United States); Department of Nuclear Engineering, Kyung Hee University, Yongin 446-701 (Korea, Republic of); Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, Florida 32611 (United States); Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institute of Health, Bethesda, Maryland 20852 (United States); Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, Florida 32611 (United States)

    2011-03-15T23:59:59.000Z

    Purpose: To develop a computed tomography (CT) organ dose estimation method designed to readily provide organ doses in a reference adult male and female for different scan ranges to investigate the degree to which existing commercial programs can reasonably match organ doses defined in these more anatomically realistic adult hybrid phantomsMethods: The x-ray fan beam in the SOMATOM Sensation 16 multidetector CT scanner was simulated within the Monte Carlo radiation transport code MCNPX2.6. The simulated CT scanner model was validated through comparison with experimentally measured lateral free-in-air dose profiles and computed tomography dose index (CTDI) values. The reference adult male and female hybrid phantoms were coupled with the established CT scanner model following arm removal to simulate clinical head and other body region scans. A set of organ dose matrices were calculated for a series of consecutive axial scans ranging from the top of the head to the bottom of the phantoms with a beam thickness of 10 mm and the tube potentials of 80, 100, and 120 kVp. The organ doses for head, chest, and abdomen/pelvis examinations were calculated based on the organ dose matrices and compared to those obtained from two commercial programs, CT-EXPO and CTDOSIMETRY. Organ dose calculations were repeated for an adult stylized phantom by using the same simulation method used for the adult hybrid phantom. Results: Comparisons of both lateral free-in-air dose profiles and CTDI values through experimental measurement with the Monte Carlo simulations showed good agreement to within 9%. Organ doses for head, chest, and abdomen/pelvis scans reported in the commercial programs exceeded those from the Monte Carlo calculations in both the hybrid and stylized phantoms in this study, sometimes by orders of magnitude. Conclusions: The organ dose estimation method and dose matrices established in this study readily provides organ doses for a reference adult male and female for different CT scan ranges and technical parameters. Organ doses from existing commercial programs do not reasonably match organ doses calculated for the hybrid phantoms due to differences in phantom anatomy, as well as differences in organ dose scaling parameters. The organ dose matrices developed in this study will be extended to cover different technical parameters, CT scanner models, and various age groups.

  19. AMPA-receptor mediated plasticity within the rat spinal cord

    E-Print Network [OSTI]

    Hoy, Kevin Corcoran

    2009-05-15T23:59:59.000Z

    AMPA-RECEPTOR MEDIATED PLASTICITY WITHIN THE RAT SPINAL CORD A Thesis by KEVIN CORCORAN HOY JR. Submited to the Ofice of Graduate Studies of Texas A&M University in partial fulfilment of the requirements... for the degre of MASTER OF SCIENCE August 2008 Major Subject: Psychology AMPA-RECEPTOR MEDIATED PLASTICITY WITHIN THE RAT SPINAL CORD A Thesis by KEVIN CORCORAN HOY JR. Submited to the Ofice of Graduate...

  20. Distribution of ochratoxin A in the pregnant rat

    E-Print Network [OSTI]

    Ballinger, Michael Brent

    1983-01-01T23:59:59.000Z

    . . . APPENDIX 1. SAFETY PROCEDURES. APPENDIX 2. BIOLOGICAL OXIDIZER PROCEDURES. . . APPENDIX 3. LIQUID SCINTILLATION COUNTING. . . . APPENDIX 4. PHARMACOKINETIC CALCULATIONS. . . . . VITA. 1V V1 V11 V111 3 4 12 26 27 27 27 28 29 33 35 54 57... 66 68 71 73 74 LIST OF TABLES Table Page 1 Pharmacokinetic parameters estimated from the serum radioactivity derived from 3H-ochratoxin A in pregnant rats. . 2 Excretion of 3H radioactivity by pregnant rats. . 38 39 3 Distribution...

  1. Arginine and Conjugated Linoleic Acid Reduce Fat Mass in Rats

    E-Print Network [OSTI]

    Nall, Jennifer L.

    2010-10-12T23:59:59.000Z

    ARGININE AND CONJUGATED LINOLEIC ACID REDUCE FAT MASS IN RATS A Thesis by JENNIFER LYNN NALL Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE May 2008 Major Subject: Nutrition ARGININE AND CONJUGATED LINOLEIC ACID REDUCE FAT MASS IN RATS A Thesis by JENNIFER LYNN NALL Submitted to the Office of Graduate Studies Texas A...

  2. Neuroendocrine effects of acute nickel chloride administration in rats

    SciTech Connect (OSTI)

    Clemons, G.K.; Garcia, J.F.

    1981-01-01T23:59:59.000Z

    An sc injection of nickel chloride (20 and 10 mg/kg) led to a profound and consistent increase of circulating prolactin (PRL) levels after 1 day and lasted for 4 days (p < 0.001) in male rats. Increases in insulin levels occurred 1 and 2 days postinjection. The nickel-induced PRL rise could be abolished by a simultaneous administration of 2-bromo-..cap alpha..-ergocryptine (CB 154). In vitro incubation of pituitaries from rats that received 20 mg/kg of nickel chloride 48 hr prior to sacrifice released more PRL into the culture medium, as well as contained more PRL in the final tissue than did the pituitaries from control animals. The hypothalamic extracts (HE) obtained from hypothalami of nickel-injected rats were tested also in vitro on normal rat pituitaries and the results showed that the HE from such rats released more PRL and therefore had less prolactin-inhibiting factor (PIF) than the HE obtained from control rats. The results show that nickel chloride has effects on the endocrine system that (a) last considerably longer than previously reported, (b) are mediated through the neuroendocrine system, and (c) instead of specifically inhibiting PRL secretion from the pituitary promote high circulating PRL levels lasting from 1 to 4 days.

  3. Mergers of galaxies in clusters: Monte Carlo simulation of mass and angular momentum distribution

    E-Print Network [OSTI]

    D. S. Krivitsky; V. M. Kontorovich

    1997-03-04T23:59:59.000Z

    A Monte Carlo simulation of mergers in clusters of galaxies is carried out. An ``explosive'' character of the merging process (an analog of phase transition), suggested earlier by Cavaliere et al. (1991), Kontorovich et al. (1992), is confirmed. In particular, a giant object similar to cD-galaxy is formed in a comparatively short time as a result of mergers. Mass and angular momentum distribution function for galaxies is calculated. An intermediate asymptotics of the mass function is close to a power law with the exponent $\\alpha\\approx2$. It may correspond to recent observational data for steep faint end of the luminosity function. The angular momentum distribution formed by mergers is close to Gaussian, the rms dimensionless angular momentum $S/(GM^3R)^{1/2}$ being approximately independent of mass, which is in accordance with observational data.

  4. A portable, parallel, object-oriented Monte Carlo neutron transport code in C++

    SciTech Connect (OSTI)

    Lee, S.R.; Cummings, J.C. [Los Alamos National Lab., NM (United States); Nolen, S.D. [Texas A and M Univ., College Station, TX (United States)]|[Los Alamos National Lab., NM (United States)

    1997-05-01T23:59:59.000Z

    We have developed a multi-group Monte Carlo neutron transport code using C++ and the Parallel Object-Oriented Methods and Applications (POOMA) class library. This transport code, called MC++, currently computes k and {alpha}-eigenvalues and is portable to and runs parallel on a wide variety of platforms, including MPPs, clustered SMPs, and individual workstations. It contains appropriate classes and abstractions for particle transport and, through the use of POOMA, for portable parallelism. Current capabilities of MC++ are discussed, along with physics and performance results on a variety of hardware, including all Accelerated Strategic Computing Initiative (ASCI) hardware. Current parallel performance indicates the ability to compute {alpha}-eigenvalues in seconds to minutes rather than hours to days. Future plans and the implementation of a general transport physics framework are also discussed.

  5. A Monte-Carlo method for ex-core neutron response

    SciTech Connect (OSTI)

    Gamino, R.G.; Ward, J.T.; Hughes, J.C. [Lockheed Martin Corp., Schenectady, NY (United States)

    1997-10-01T23:59:59.000Z

    A Monte Carlo neutron transport kernel capability primarily for ex-core neutron response is described. The capability consists of the generation of a set of response kernels, which represent the neutron transport from the core to a specific ex-core volume. This is accomplished by tagging individual neutron histories from their initial source sites and tracking them throughout the problem geometry, tallying those that interact in the geometric regions of interest. These transport kernels can subsequently be combined with any number of core power distributions to determine detector response for a variety of reactor Thus, the transport kernels are analogous to an integrated adjoint response. Examples of pressure vessel response and ex-core neutron detector response are provided to illustrate the method.

  6. MC++: A parallel, portable, Monte Carlo neutron transport code in C++

    SciTech Connect (OSTI)

    Lee, S.R.; Cummings, J.C. [Los Alamos National Lab., NM (United States); Nolen, S.D. [Texas A & M Univ., College Station, TX (United States)

    1997-03-01T23:59:59.000Z

    MC++ is an implicit multi-group Monte Carlo neutron transport code written in C++ and based on the Parallel Object-Oriented Methods and Applications (POOMA) class library. MC++ runs in parallel on and is portable to a wide variety of platforms, including MPPs, SMPs, and clusters of UNIX workstations. MC++ is being developed to provide transport capabilities to the Accelerated Strategic Computing Initiative (ASCI). It is also intended to form the basis of the first transport physics framework (TPF), which is a C++ class library containing appropriate abstractions, objects, and methods for the particle transport problem. The transport problem is briefly described, as well as the current status and algorithms in MC++ for solving the transport equation. The alpha version of the POOMA class library is also discussed, along with the implementation of the transport solution algorithms using POOMA. Finally, a simple test problem is defined and performance and physics results from this problem are discussed on a variety of platforms.

  7. Validation of GEANT4 Monte Carlo Models with a Highly Granular Scintillator-Steel Hadron Calorimeter

    E-Print Network [OSTI]

    C. Adloff; J. Blaha; J. -J. Blaising; C. Drancourt; A. Espargilière; R. Gaglione; N. Geffroy; Y. Karyotakis; J. Prast; G. Vouters; K. Francis; J. Repond; J. Schlereth; J. Smith; L. Xia; E. Baldolemar; J. Li; S. T. Park; M. Sosebee; A. P. White; J. Yu; T. Buanes; G. Eigen; Y. Mikami; N. K. Watson; G. Mavromanolakis; M. A. Thomson; D. R. Ward; W. Yan; D. Benchekroun; A. Hoummada; Y. Khoulaki; J. Apostolakis; A. Dotti; G. Folger; V. Ivantchenko; V. Uzhinskiy; M. Benyamna; C. Cârloganu; F. Fehr; P. Gay; S. Manen; L. Royer; G. C. Blazey; A. Dyshkant; J. G. R. Lima; V. Zutshi; J. -Y. Hostachy; L. Morin; U. Cornett; D. David; G. Falley; K. Gadow; P. Göttlicher; C. Günter; B. Hermberg; S. Karstensen; F. Krivan; A. -I. Lucaci-Timoce; S. Lu; B. Lutz; S. Morozov; V. Morgunov; M. Reinecke; F. Sefkow; P. Smirnov; M. Terwort; A. Vargas-Trevino; N. Feege; E. Garutti; I. Marchesinik; M. Ramilli; P. Eckert; T. Harion; A. Kaplan; H. -Ch. Schultz-Coulon; W. Shen; R. Stamen; B. Bilki; E. Norbeck; Y. Onel; G. W. Wilson; K. Kawagoe; P. D. Dauncey; A. -M. Magnan; V. Bartsch; M. Wing; F. Salvatore; E. Calvo Alamillo; M. -C. Fouz; J. Puerta-Pelayo; B. Bobchenko; M. Chadeeva; M. Danilov; A. Epifantsev; O. Markin; R. Mizuk; E. Novikov; V. Popov; V. Rusinov; E. Tarkovsky; N. Kirikova; V. Kozlov; P. Smirnov; Y. Soloviev; P. Buzhan; A. Ilyin; V. Kantserov; V. Kaplin; A. Karakash; E. Popova; V. Tikhomirov; C. Kiesling; K. Seidel; F. Simon; C. Soldner; M. Szalay; M. Tesar; L. Weuste; M. S. Amjad; J. Bonis; S. Callier; S. Conforti di Lorenzo; P. Cornebise; Ph. Doublet; F. Dulucq; J. Fleury; T. Frisson; N. van der Kolk; H. Li; G. Martin-Chassard; F. Richard; Ch. de la Taille; R. Pöschl; L. Raux; J. Rouëné; N. Seguin-Moreau; M. Anduze; V. Boudry; J-C. Brient; D. Jeans; P. Mora de Freitas; G. Musat; M. Reinhard; M. Ruan; H. Videau; B. Bulanek; J. Zacek; J. Cvach; P. Gallus; M. Havranek; M. Janata; J. Kvasnicka; D. Lednicky; M. Marcisovsky; I. Polak; J. Popule; L. Tomasek; M. Tomasek; P. Ruzicka; P. Sicho; J. Smolik; V. Vrba; J. Zalesak; B. Belhorma; H. Ghazlane; T. Takeshita; S. Uozumi; M. Götze; O. Hartbrich; J. Sauer; S. Weber; C. Zeitnitz

    2014-06-15T23:59:59.000Z

    Calorimeters with a high granularity are a fundamental requirement of the Particle Flow paradigm. This paper focuses on the prototype of a hadron calorimeter with analog readout, consisting of thirty-eight scintillator layers alternating with steel absorber planes. The scintillator plates are finely segmented into tiles individually read out via Silicon Photomultipliers. The presented results are based on data collected with pion beams in the energy range from 8GeV to 100GeV. The fine segmentation of the sensitive layers and the high sampling frequency allow for an excellent reconstruction of the spatial development of hadronic showers. A comparison between data and Monte Carlo simulations is presented, concerning both the longitudinal and lateral development of hadronic showers and the global response of the calorimeter. The performance of several GEANT4 physics lists with respect to these observables is evaluated.

  8. Kinetic Monte Carlo Simulation of Electrodeposition using the Embedded-Atom Method

    E-Print Network [OSTI]

    Treeratanaphitak, Tanyakarn; Abukhdeir, Nasser Mohieddin

    2013-01-01T23:59:59.000Z

    A kinetic Monte Carlo (KMC) method is presented to simulate the electrodeposition of a metal on a single crystal surface of the same metal under galvanostatic conditions. This method utilizes the multi-body embedded-atom method (EAM) potential to characterize the interactions of metal atoms and adatoms. The KMC method accounts for deposition and surface diffusion processes including hopping, atom exchange and step-edge atom exchange. Steady-state deposition configurations obtained using the KMC method are validated by comparison with the structures obtained through the use of molecular dynamics (MD) simulations to relax KMC constraints. The results of this work support the use of the proposed KMC method to simulate electrodeposition processes at length (microns) and time (seconds) scales that are not feasible using other methods.

  9. Monte Carlo and Renormalization Group Effective Potentials in Scalar Field Theories

    E-Print Network [OSTI]

    J. R. Shepard; V. Dmitrašinovi?; J. A. McNeil

    1994-12-29T23:59:59.000Z

    We study constraint effective potentials for various strongly interacting $\\phi^4$ theories. Renormalization group (RG) equations for these quantities are discussed and a heuristic development of a commonly used RG approximation is presented which stresses the relationships among the loop expansion, the Schwinger-Dyson method and the renormalization group approach. We extend the standard RG treatment to account explicitly for finite lattice effects. Constraint effective potentials are then evaluated using Monte Carlo (MC) techniques and careful comparisons are made with RG calculations. Explicit treatment of finite lattice effects is found to be essential in achieving quantitative agreement with the MC effective potentials. Excellent agreement is demonstrated for $d=3$ and $d=4$, O(1) and O(2) cases in both symmetric and broken phases.

  10. Monte Carlo Method for Calculating Oxygen Abundances and Their Uncertainties from Strong-Line Flux Measurements

    E-Print Network [OSTI]

    Bianco, Federica B; Oh, Seung Man; Fierroz, David; Liu, Yuqian; Kewley, Lisa; Graur, Or

    2015-01-01T23:59:59.000Z

    We present the open-source Python code pyMCZ that determines oxygen abundance and its distribution from strong emission lines in the standard metallicity scales, based on the original IDL code of Kewley & Dopita (2002) with updates from Kewley & Ellison (2008), and expanded to include more recently developed scales. The standard strong-line diagnostics have been used to estimate the oxygen abundance in the interstellar medium through various emission line ratios in many areas of astrophysics, including galaxy evolution and supernova host galaxy studies. We introduce a Python implementation of these methods that, through Monte Carlo (MC) sampling, better characterizes the statistical reddening-corrected oxygen abundance confidence region. Given line flux measurements and their uncertainties, our code produces synthetic distributions for the oxygen abundance in up to 13 metallicity scales simultaneously, as well as for E(B-V), and estimates their median values and their 66% confidence regions. In additi...

  11. Application analysis of Monte Carlo to estimate the capacity of geothermal resources in Lawu Mount

    SciTech Connect (OSTI)

    Supriyadi, E-mail: supriyadi-uno@yahoo.co.nz [Physics, Faculty of Mathematics and Natural Sciences, University of Jember, Jl. Kalimantan Kampus Bumi Tegal Boto, Jember 68181 (Indonesia); Srigutomo, Wahyu [Complex system and earth physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia); Munandar, Arif [Kelompok Program Penelitian Panas Bumi, PSDG, Badan Geologi, Kementrian ESDM, Jl. Soekarno Hatta No. 444 Bandung 40254 (Indonesia)

    2014-03-24T23:59:59.000Z

    Monte Carlo analysis has been applied in calculation of geothermal resource capacity based on volumetric method issued by Standar Nasional Indonesia (SNI). A deterministic formula is converted into a stochastic formula to take into account the nature of uncertainties in input parameters. The method yields a range of potential power probability stored beneath Lawu Mount geothermal area. For 10,000 iterations, the capacity of geothermal resources is in the range of 139.30-218.24 MWe with the most likely value is 177.77 MWe. The risk of resource capacity above 196.19 MWe is less than 10%. The power density of the prospect area covering 17 km{sup 2} is 9.41 MWe/km{sup 2} with probability 80%.

  12. A new time quantifiable Monte Carlo method in simulating magnetization reversal process

    E-Print Network [OSTI]

    X. Z. Cheng; M. B. A. Jalil; H. K. Lee; Y. Okabe

    2005-04-14T23:59:59.000Z

    We propose a new time quantifiable Monte Carlo (MC) method to simulate the thermally induced magnetization reversal for an isolated single domain particle system. The MC method involves the determination of density of states, and the use of Master equation for time evolution. We derive an analytical factor to convert MC steps into real time intervals. Unlike a previous time quantified MC method, our method is readily scalable to arbitrarily long time scales, and can be repeated for different temperatures with minimal computational effort. Based on the conversion factor, we are able to make a direct comparison between the results obtained from MC and Langevin dynamics methods, and find excellent agreement between them. An analytical formula for the magnetization reversal time is also derived, which agrees very well with both numerical Langevin and time-quantified MC results, over a large temperature range and for parallel and oblique easy axis orientations.

  13. Resonating Valence Bond Quantum Monte Carlo: Application to the ozone molecule

    E-Print Network [OSTI]

    Sam Azadi; Ranber Singh; Thomas D. Kühne

    2015-02-24T23:59:59.000Z

    We study the potential energy surface of the ozone molecule by means of Quantum Monte Carlo simulations based on the resonating valence bond concept. The trial wave function consists of an antisymmetrized geminal power arranged in a single-determinant that is multiplied by a Jastrow correlation factor. Whereas the determinantal part incorporates static correlation effects, the augmented real-space correlation factor accounts for the dynamics electron correlation. The accuracy of this approach is demonstrated by computing the potential energy surface for the ozone molecule in three vibrational states: symmetric, asymmetric and scissoring. We find that the employed wave function provides a detailed description of rather strongly-correlated multi-reference systems, which is in quantitative agreement with experiment.

  14. Monte Carlo procedure for protein folding in lattice model. Conformational rigidity

    E-Print Network [OSTI]

    Olivier Collet

    1999-07-19T23:59:59.000Z

    A rigourous Monte Carlo method for protein folding simulation on lattice model is introduced. We show that a parameter which can be seen as the rigidity of the conformations has to be introduced in order to satisfy the detailed balance condition. Its properties are discussed and its role during the folding process is elucidated. This method is applied on small chains on two-dimensional lattice. A Bortz-Kalos-Lebowitz type algorithm which allows to study the kinetic of the chains at very low temperature is implemented in the presented method. We show that the coefficients of the Arrhenius law are in good agreement with the value of the main potential barrier of the system.

  15. Converting Boundary Representation Solid Models to Half-Space Representation Models for Monte Carlo Analysis

    SciTech Connect (OSTI)

    Davis JE, Eddy MJ, Sutton TM, Altomari TJ

    2007-03-01T23:59:59.000Z

    Solid modeling computer software systems provide for the design of three-dimensional solid models used in the design and analysis of physical components. The current state-of-the-art in solid modeling representation uses a boundary representation format in which geometry and topology are used to form three-dimensional boundaries of the solid. The geometry representation used in these systems is cubic B-spline curves and surfaces--a network of cubic B-spline functions in three-dimensional Cartesian coordinate space. Many Monte Carlo codes, however, use a geometry representation in which geometry units are specified by intersections and unions of half-spaces. This paper describes an algorithm for converting from a boundary representation to a half-space representation.

  16. Resonating Valence Bond Quantum Monte Carlo: Application to the ozone molecule

    E-Print Network [OSTI]

    Azadi, Sam; Kühne, Thomas D

    2015-01-01T23:59:59.000Z

    We study the potential energy surface of the ozone molecule by means of Quantum Monte Carlo simulations based on the resonating valence bond concept. The trial wave function consists of an antisymmetrized geminal power arranged in a single-determinant that is multiplied by a Jastrow correlation factor. Whereas the determinantal part incorporates static correlation effects, the augmented real-space correlation factor accounts for the dynamics electron correlation. The accuracy of this approach is demonstrated by computing the potential energy surface for the ozone molecule in three vibrational states: symmetric, asymmetric and scissoring. We find that the employed wave function provides a detailed description of rather strongly-correlated multi-reference systems, which is in quantitative agreement with experiment.

  17. Quantum Monte Carlo calculation of the equation of state of neutron matter

    SciTech Connect (OSTI)

    Gandolfi, S.; Illarionov, A. Yu.; Schmidt, K. E.; Pederiva, F.; Fantoni, S. [International School for Advanced Studies, SISSA Via Beirut 2/4 I-34014 Trieste (Italy) and INFN, Sezione di Trieste, Trieste (Italy); Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States); Dipartimento di Fisica dell'Universita di Trento, via Sommarive 14, I-38050 Povo, Trento (Italy) and INFN, Gruppo Collegato di Trento, Trento (Italy); International School for Advanced Studies, SISSA Via Beirut 2/4 I-34014 Trieste (Italy); INFN, Sezione di Trieste, Trieste, Italy and INFM DEMOCRITOS National Simulation Center, Via Beirut 2/4 I-34014 Trieste (Italy)

    2009-05-15T23:59:59.000Z

    We calculated the equation of state of neutron matter at zero temperature by means of the auxiliary field diffusion Monte Carlo (AFDMC) method combined with a fixed-phase approximation. The calculation of the energy was carried out by simulating up to 114 neutrons in a periodic box. Special attention was given to reducing finite-size effects at the energy evaluation by adding to the interaction the effect due to the truncation of the simulation box, and by performing several simulations using different numbers of neutrons. The finite-size effects due to kinetic energy were also checked by employing the twist-averaged boundary conditions. We considered a realistic nuclear Hamiltonian containing modern two- and three-body interactions of the Argonne and Urbana family. The equation of state can be used to compare and calibrate other many-body calculations and to predict properties of neutron stars.

  18. MaGe - a Geant4-based Monte Carlo framework for low-background experiments

    E-Print Network [OSTI]

    Yuen-Dat Chan; Jason A. Detwiler; Reyco Henning; Victor M. Gehman; Rob A. Johnson; David V. Jordan; Kareem Kazkaz; Markus Knapp; Kevin Kroninger; Daniel Lenz; Jing Liu; Xiang Liu; Michael G. Marino; Akbar Mokhtarani; Luciano Pandola; Alexis G. Schubert; Claudia Tomei

    2008-02-06T23:59:59.000Z

    A Monte Carlo framework, MaGe, has been developed based on the Geant4 simulation toolkit. Its purpose is to simulate physics processes in low-energy and low-background radiation detectors, specifically for the Majorana and Gerda $^{76}$Ge neutrinoless double-beta decay experiments. This jointly-developed tool is also used to verify the simulation of physics processes relevant to other low-background experiments in Geant4. The MaGe framework contains simulations of prototype experiments and test stands, and is easily extended to incorporate new geometries and configurations while still using the same verified physics processes, tunings, and code framework. This reduces duplication of efforts and improves the robustness of and confidence in the simulation output.

  19. Validation of the Monte Carlo Criticality Program KENO V. a for highly-enriched uranium systems

    SciTech Connect (OSTI)

    Knight, J.R.

    1984-11-01T23:59:59.000Z

    A series of calculations based on critical experiments have been performed using the KENO V.a Monte Carlo Criticality Program for the purpose of validating KENO V.a for use in evaluating Y-12 Plant criticality problems. The experiments were reflected and unreflected systems of single units and arrays containing highly enriched uranium metal or uranium compounds. Various geometrical shapes were used in the experiments. The SCALE control module CSAS25 with the 27-group ENDF/B-4 cross-section library was used to perform the calculations. Some of the experiments were also calculated using the 16-group Hansen-Roach Library. Results are presented in a series of tables and discussed. Results show that the criteria established for the safe application of the KENO IV program may also be used for KENO V.a results.

  20. A bottom collider vertex detector design, Monte-Carlo simulation and analysis package

    SciTech Connect (OSTI)

    Lebrun, P.

    1990-10-01T23:59:59.000Z

    A detailed simulation of the BCD vertex detector is underway. Specifications and global design issues are briefly reviewed. The BCD design based on double sided strip detector is described in more detail. The GEANT3-based Monte-Carlo program and the analysis package used to estimate detector performance are discussed in detail. The current status of the expected resolution and signal to noise ratio for the golden'' CP violating mode B{sub d} {yields} {pi}{sup +}{pi}{sup {minus}} is presented. These calculations have been done at FNAL energy ({radical}s = 2.0 TeV). Emphasis is placed on design issues, analysis techniques and related software rather than physics potentials. 20 refs., 46 figs.

  1. Phase transition in liquid crystal elastomer - a Monte Carlo study employing non-Boltzmann sampling

    E-Print Network [OSTI]

    D. Jayasri; N. Satyavathi; V. S. S. Sastry; K. P. N. Murthy

    2006-11-08T23:59:59.000Z

    We investigate Isotropic - Nematic transition in liquid crystal elastomers employing non-Boltzmann Monte Carlo techniques. We consider a lattice model of a liquid elastomer and Selinger-Jeon-Ratna Hamiltonian which accounts for homogeneous/inhomogeneous interactions among liquid crystalline units, interaction of local nematics with global strain, and with inhomogeneous external fields and stress. We find that when the local director is coupled strongly to the global strain the transition is strongly first order; the transition softens when the coupling becomes weaker. Also the transition temperature decreases with decrease of coupling strength. Besides we find that the nematic order scales nonlinearly with global strain especially for strong coupling and at low temperatures.

  2. Report on International Collaboration Involving the FE Heater and HG-A Tests at Mont Terri

    SciTech Connect (OSTI)

    Houseworth, Jim; Rutqvist, Jonny; Asahina, Daisuke; Chen, Fei; Vilarrasa, Victor; Liu, Hui-Hai; Birkholzer, Jens

    2013-11-06T23:59:59.000Z

    Nuclear waste programs outside of the US have focused on different host rock types for geological disposal of high-level radioactive waste. Several countries, including France, Switzerland, Belgium, and Japan are exploring the possibility of waste disposal in shale and other clay-rich rock that fall within the general classification of argillaceous rock. This rock type is also of interest for the US program because the US has extensive sedimentary basins containing large deposits of argillaceous rock. LBNL, as part of the DOE-NE Used Fuel Disposition Campaign, is collaborating on some of the underground research laboratory (URL) activities at the Mont Terri URL near Saint-Ursanne, Switzerland. The Mont Terri project, which began in 1995, has developed a URL at a depth of about 300 m in a stiff clay formation called the Opalinus Clay. Our current collaboration efforts include two test modeling activities for the FE heater test and the HG-A leak-off test. This report documents results concerning our current modeling of these field tests. The overall objectives of these activities include an improved understanding of and advanced relevant modeling capabilities for EDZ evolution in clay repositories and the associated coupled processes, and to develop a technical basis for the maximum allowable temperature for a clay repository. The R&D activities documented in this report are part of the work package of natural system evaluation and tool development that directly supports the following Used Fuel Disposition Campaign (UFDC) objectives: ? Develop a fundamental understanding of disposal-system performance in a range of environments for potential wastes that could arise from future nuclear-fuel-cycle alternatives through theory, simulation, testing, and experimentation. ? Develop a computational modeling capability for the performance of storage and disposal options for a range of fuel-cycle alternatives, evolving from generic models to more robust models of performance assessment. For the purpose of validating modeling capabilities for thermal-hydro-mechanical (THM) processes, we developed a suite of simulation models for the planned full-scale FE Experiment to be conducted in the Mont Terri URL, including a full three-dimensional model that will be used for direct comparison to experimental data once available. We performed for the first time a THM analysis involving the Barcelona Basic Model (BBM) in a full three-dimensional field setting for modeling the geomechanical behavior of the buffer material and its interaction with the argillaceous host rock. We have simulated a well defined benchmark that will be used for codeto- code verification against modeling results from other international modeling teams. The analysis highlights the complex coupled geomechanical behavior in the buffer and its interaction with the surrounding rock and the importance of a well characterized buffer material in terms of THM properties. A new geomechanical fracture-damage model, TOUGH-RBSN, was applied to investigate damage behavior in the ongoing HG-A test at Mont Terri URL. Two model modifications have been implemented so that the Rigid-Body-Spring-Network (RBSN) model can be used for analysis of fracturing around the HG-A microtunnel. These modifications are (1) a methodology to compute fracture generation under compressive stress conditions and (2) a method to represent anisotropic elastic and strength properties. The method for computing fracture generation under compressive load produces results that roughly follow trends expected for homogeneous and layered systems. Anisotropic properties for the bulk rock were represented in the RBSN model using layered heterogeneity and gave bulk material responses in line with expectations. These model improvements were implemented for an initial model of fracture damage at the HG-A test. While the HG-A test model results show some similarities with the test observations, differences between the model results and observations remain.

  3. Ab-initio molecular dynamics simulation of liquid water by Quantum Monte Carlo

    E-Print Network [OSTI]

    Andrea Zen; Ye Luo; Guglielmo Mazzola; Leonardo Guidoni; Sandro Sorella

    2015-04-21T23:59:59.000Z

    Although liquid water is ubiquitous in chemical reactions at roots of life and climate on the earth, the prediction of its properties by high-level ab initio molecular dynamics simulations still represents a formidable task for quantum chemistry. In this article we present a room temperature simulation of liquid water based on the potential energy surface obtained by a many-body wave function through quantum Monte Carlo (QMC) methods. The simulated properties are in good agreement with recent neutron scattering and X-ray experiments, particularly concerning the position of the oxygen-oxygen peak in the radial distribution function, at variance of previous Density Functional Theory attempts. Given the excellent performances of QMC on large scale supercomputers, this work opens new perspectives for predictive and reliable ab-initio simulations of complex chemical systems.

  4. Monte-Carlo study of quasiparticle dispersion relation in monolayer graphene

    E-Print Network [OSTI]

    P. V. Buividovich

    2013-01-07T23:59:59.000Z

    The density of electronic one-particle states in monolayer graphene is studied by performing the Hybrid Monte-Carlo simulations of the tight-binding model for electrons on the pi orbitals of carbon atoms which make up the graphene lattice. Density of states is approximated as a derivative of the number of particles over the chemical potential at sufficiently small temperature. Simulations are performed in the partially quenched approximation, in which virtual particles and holes have zero chemical potential. It is found that the Van Hove singularity becomes much sharper than in the free tight-binding model. Simulation results also suggest that the Fermi velocity increases with interaction strength up to the transition to the phase with spontaneously broken chiral symmetry.

  5. Introduction to Computational Physics and Monte Carlo Simulations of Matrix Field Theory

    E-Print Network [OSTI]

    Ydri, Badis

    2015-01-01T23:59:59.000Z

    This book is divided into two parts. In the first part we give an elementary introduction to computational physics consisting of 21 simulations which originated from a formal course of lectures and laboratory simulations delivered since 2010 to physics students at Annaba University. The second part is much more advanced and deals with the problem of how to set up working Monte Carlo simulations of matrix field theories which involve finite dimensional matrix regularizations of noncommutative and fuzzy field theories, fuzzy spaces and matrix geometry. The study of matrix field theory in its own right has also become very important to the proper understanding of all noncommutative, fuzzy and matrix phenomena. The second part, which consists of 9 simulations, was delivered informally to doctoral students who are working on various problems in matrix field theory. Sample codes as well as sample key solutions are also provided for convenience and completness. An appendix containing an executive arabic summary of t...

  6. From hypernuclei to the Inner Core of Neutron Stars: A Quantum Monte Carlo Study

    E-Print Network [OSTI]

    Diego Lonardoni; Francesco Pederiva; Stefano Gandolfi

    2014-08-19T23:59:59.000Z

    Auxiliary Field Diffusion Monte Carlo (AFDMC) calculations have been employed to revise the interaction between $\\Lambda$-hyperons and nucleons in hypernuclei. The scheme used to describe the interaction, inspired by the phenomenological Argonne-Urbana forces, is the $\\Lambda N+\\Lambda NN$ potential firstly introduced by Bodmer, Usmani et al.. Within this framework, we performed calculations on light and medium mass hypernuclei in order to assess the extent of the repulsive contribution of the three-body part. By tuning this contribution in order to reproduce the $\\Lambda$ separation energy in $^5_\\Lambda$He and $^{17}_{~\\Lambda}$O, experimental findings are reproduced over a wide range of masses. Calculations have then been extended to $\\Lambda$-neutron matter in order to derive an analogous of the symmetry energy to be used in determining the equation of state of matter in the typical conditions found in the inner core of neutron stars.

  7. The Auxiliary Field Diffusion Monte Carlo Method for Nuclear Physics and Nuclear Astrophysics

    E-Print Network [OSTI]

    Stefano Gandolfi

    2007-12-09T23:59:59.000Z

    In this thesis, I discuss the use of the Auxiliary Field Diffusion Monte Carlo method to compute the ground state of nuclear Hamiltonians, and I show several applications to interesting problems both in nuclear physics and in nuclear astrophysics. In particular, the AFDMC algorithm is applied to the study of several nuclear systems, finite, and infinite matter. Results about the ground state of nuclei ($^4$He, $^8$He, $^{16}$O and $^{40}$Ca), neutron drops (with 8 and 20 neutrons) and neutron rich-nuclei (isotopes of oxygen and calcium) are discussed, and the equation of state of nuclear and neutron matter are calculated and compared with other many-body calculations. The $^1S_0$ superfluid phase of neutron matter in the low-density regime was also studied.

  8. Auxiliary-field quantum Monte Carlo method for strongly paired fermions

    SciTech Connect (OSTI)

    Carlson, J.; Gandolfi, Stefano [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Schmidt, Kevin E. [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States); Zhang, Shiwei [Department of Physics, College of William and Mary, Williamsburg, Virginia 23187 (United States)

    2011-12-15T23:59:59.000Z

    We solve the zero-temperature unitary Fermi gas problem by incorporating a BCS importance function into the auxiliary-field quantum Monte Carlo method. We demonstrate that this method does not suffer from a sign problem and that it increases the efficiency of standard techniques by many orders of magnitude for strongly paired fermions. We calculate the ground-state energies exactly for unpolarized systems with up to 66 particles on lattices of up to 27{sup 3} sites, obtaining an accurate result for the universal parameter {xi}. We also obtain results for interactions with different effective ranges and find that the energy is consistent with a universal linear dependence on the product of the Fermi momentum and the effective range. This method will have many applications in superfluid cold atom systems and in both electronic and nuclear structures where pairing is important.

  9. Ab-initio molecular dynamics simulation of liquid water by Quantum Monte Carlo

    E-Print Network [OSTI]

    Andrea Zen; Ye Luo; Guglielmo Mazzola; Leonardo Guidoni; Sandro Sorella

    2014-12-09T23:59:59.000Z

    Despite liquid water is ubiquitous in chemical reactions at roots of life and climate on earth, the prediction of its properties by high-level ab initio molecular dynamics simulations still represents a formidable task for quantum chemistry. In this article we present a room temperature simulation of liquid water based on the potential energy surface obtained by a many-body wave function through quantum Monte Carlo (QMC) methods. The simulated properties are in excellent agreement with recent neutron scattering and X-ray experiments, particularly concerning the position of the oxygen-oxygen peak in the radial distribution function, at variance of previous Density Functional Theory attempts. Given the excellent performances of QMC on large scale supercomputers, this work opens new perspectives for predictive and reliable ab-initio simulations of complex chemical systems.

  10. Ferroelectric domain formation in discotic liquid crystals : Monte Carlo study on the influence of boundary conditions

    E-Print Network [OSTI]

    Bose, Tushar Kanti

    2015-01-01T23:59:59.000Z

    The realization of a spontaneous macroscopic ferroelectric order in fluids of anisotropic mesogens is a topic of both fundamental and technological interest. Recently, we demonstrated that a system of dipolar achiral disklike ellipsoids can exhibit long-searched ferroelectric liquid crystalline phases of dipolar origin. In the present work, extensive off-lattice Monte Carlo simulations are used to investigate the phase behavior of the system under the influences of the electrostatic boundary conditions that restrict any global polarization. We find that the system develops strongly ferroelectric slablike domains periodically arranged in an antiferroelectric fashion. Exploring the phase behavior at different dipole strengths, we find existence of the ferroelectric nematic and ferroelectric columnar order inside the domains. For higher dipole strengths, a biaxial phase is also obtained with a similar periodic array of ferroelectric slabs of antiparallel polarizations. We have studied the depolarizing effects by...

  11. Finite-Temperature Pairing Gap of a Unitary Fermi Gas by Quantum Monte Carlo Calculations

    SciTech Connect (OSTI)

    Magierski, Piotr; Wlazlowski, Gabriel [Faculty of Physics, Warsaw University of Technology, ulica Koszykowa 75, 00-662 Warsaw (Poland); Bulgac, Aurel; Drut, Joaquin E. [Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States)

    2009-11-20T23:59:59.000Z

    We calculate the one-body temperature Green's (Matsubara) function of the unitary Fermi gas via quantum Monte Carlo, and extract the spectral weight function A(p,omega) using the methods of maximum entropy and singular value decomposition. From A(p,omega) we determine the quasiparticle spectrum, which can be accurately parametrized by three functions of temperature: an effective mass m*, a mean-field potential U, and a gap DELTA. Below the critical temperature T{sub c}=0.15epsilon{sub F} the results for m*, U, and DELTA can be accurately reproduced using an independent quasiparticle model. We find evidence of a pseudogap in the fermionic excitation spectrum for temperatures up to T*{approx_equal}0.20{epsilon}{sub F}>T{sub c}.

  12. Quantum Monte Carlo study of dilute neutron matter at finite temperatures

    SciTech Connect (OSTI)

    Wlazlowski, Gabriel; Magierski, Piotr [Faculty of Physics, Warsaw University of Technology, Ulica Koszykowa 75, PL-00-662 Warsaw (Poland)

    2011-01-15T23:59:59.000Z

    We report results of fully nonperturbative, path integral Monte Carlo calculations for dilute neutron matter. The neutron-neutron interaction in the s channel is parameterized by the scattering length and the effective range. We calculate the energy and the chemical potential as a function of temperature at density {rho}=0.003 fm{sup -3}. The critical temperature T{sub c} for the superfluid-normal phase transition is estimated from the finite size scaling of the condensate fraction. At low temperatures we extract the spectral weight function A(p,{omega}) from the imaginary time propagator using the methods of maximum entropy and singular value decomposition. We determine the quasiparticle spectrum, which can be accurately parameterized by three parameters: an effective mass m{sup *}, a mean-field potential U, and a gap {Delta}. Large values of {Delta}/T{sub c} indicate that the system is not a BCS-type superfluid at low temperatures.

  13. Inclusions fluides et isotopes du soufre du gisement CuAu de Valea Morii (monts Apuseni, Roumanie) : un

    E-Print Network [OSTI]

    Boyer, Edmond

    ore deposit (Apuseni mountains, Romania): telescoping between porphyry and low-sulfidation epithermal Morii Cu­Au ore deposit (Apuseni mountains, Romania) is characterised by a spatial association; Romania; epithermal; porphyry copper; deposit; fluids; telescoping Mots-clé: monts Apuseni; Roumanie

  14. Monte Carlo study of the CO-poisoning dynamics in a model for the catalytic oxidation of CO

    E-Print Network [OSTI]

    Marro, Joaquín

    Monte Carlo study of the CO-poisoning dynamics in a model for the catalytic oxidation of CO The poisoning dynamics of the Ziff­Gulari­Barshad Phys. Rev. Lett. 56, 2553 1986 model, for a monomer absorbing state and close to the coexistence point. Analysis of the average poisoning time ( p) allows us

  15. PHYSICAL REVIEW B 83, 245414 (2011) Monte Carlo study of the honeycomb structure of anthraquinone molecules on Cu(111)

    E-Print Network [OSTI]

    Einstein, Theodore L.

    PHYSICAL REVIEW B 83, 245414 (2011) Monte Carlo study of the honeycomb structure of anthraquinone model, we demonstrate a mechanism for the spontaneous formation of honeycomb structure of anthraquinone­13 Pawin et al.14 observed the spontaneous formation of honeycomb structures of anthraquinone (AQ

  16. Monte Carlo Simulations of Small Sulfuric Acid-Water Clusters S. M. Kathmann,* and B. N. Hale,*

    E-Print Network [OSTI]

    Hale, Barbara N.

    -to-liquid nucleation1-5 to acid rain formation6-8 and ozone depletion mechanisms.9-11 Doyle's early work2 predictedMonte Carlo Simulations of Small Sulfuric Acid-Water Clusters S. M. Kathmann,* and B. N. Hale§,* En Form: August 7, 2001 Effective atom-atom potentials are developed for binary sulfuric acid

  17. Development of a device for the measurement of biological tissue optical properties using the single Monte Carlo method

    E-Print Network [OSTI]

    Bendele, Travis Henry

    2013-02-22T23:59:59.000Z

    A honeycomb probe was designed to measure the optical properties of biological tissues using single Monte Carlo method. The ongoing project is intended to be a multi-wavelength, real time, and in-vivo technique to detect breast cancer. Preliminary...

  18. The influence of fluid flow through granitic crust: a thermo-tectonic study in and on Mont Blanc

    E-Print Network [OSTI]

    Glasgow, University of

    The influence of fluid flow through granitic crust: a thermo-tectonic study in and on Mont Blanc Tim Dempster, Cristina Persano and Zoe Shipton *Tim.Dempster@ges.gla.ac.uk Granitic and gneissose within a evolving mountain zone, the metasomatic influence of fluids in granite gneiss and the resulting

  19. September 1, 2001 / Vol. 26, No. 17 / OPTICS LETTERS 1335 Perturbation Monte Carlo methods to solve inverse photon

    E-Print Network [OSTI]

    Boas, David

    September 1, 2001 / Vol. 26, No. 17 / OPTICS LETTERS 1335 Perturbation Monte Carlo methods to solve with respect to perturbations in background tissue optical properties. We then feed this derivative information to a nonlinear optimization algorithm to determine the optical properties of the tissue heterogeneity under

  20. Nitrate dynamics in the soil and unconfined aquifer in arid groundwater coupled ecosystems of the Monte desert, Argentina

    E-Print Network [OSTI]

    Nacional de San Luis, Universidad

    of the Monte desert, Argentina J. N. Aranibar,1,2 P. E. Villagra,1,3 M. L. Gomez,1 E. Jobbágy,4 M. Quiroga,1 R desert, Argentina, J. Geophys. Res., 116, G04015, doi:10.1029/2010JG001618. 1. Introduction [2] Drylands desert, Argentina, shallow groundwater is exploited by deep rooted trees, increasing primary productivity

  1. Bayes or Bootstrap? A Simulation Study Comparing the Performance of Bayesian Markov Chain Monte Carlo Sampling and Bootstrapping in

    E-Print Network [OSTI]

    Lutzoni, François M.

    Bayes or Bootstrap? A Simulation Study Comparing the Performance of Bayesian Markov Chain Monte Carlo Sampling and Bootstrapping in Assessing Phylogenetic Confidence Michael E. Alfaro,* Stefan Zoller of confidence and the most commonly used confidence measure in phylogenetics, the nonparametric bootstrap

  2. 30TH INTERNATIONAL COSMIC RAY CONFERENCE A Fast and Accurate Monte Carlo EAS Simulation Scheme in the GZK Energy Re-

    E-Print Network [OSTI]

    a full and quasi-full MC simulation with energy threshold of particles of 500 keV for primary energy by the user). Apart from thinning, a number of papers treats about techniques to simulate ultra high energy30TH INTERNATIONAL COSMIC RAY CONFERENCE A Fast and Accurate Monte Carlo EAS Simulation Scheme

  3. Quantum Monte Carlo Study of the Optical and Diffusive Properties of theVacancy Defect in Diamond

    E-Print Network [OSTI]

    Kent, Paul

    associated with radiation damage. It is also very interesting scientifically, with a wide variety of physicalQuantum Monte Carlo Study of the Optical and Diffusive Properties of theVacancy Defect in Diamond]. The best-known optical transition, GR1 at 1.673 eV [5], long associated with the neutral vacancy, cannot

  4. Quantitative study of fluctuation effects by fast lattice Monte Carlo simulations: Compression of grafted homopolymers

    SciTech Connect (OSTI)

    Zhang, Pengfei; Wang, Qiang, E-mail: q.wang@colostate.edu [Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, Colorado 80523-1370 (United States)] [Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, Colorado 80523-1370 (United States)

    2014-01-28T23:59:59.000Z

    Using fast lattice Monte Carlo (FLMC) simulations [Q. Wang, Soft Matter 5, 4564 (2009)] and the corresponding lattice self-consistent field (LSCF) calculations, we studied a model system of grafted homopolymers, in both the brush and mushroom regimes, in an explicit solvent compressed by an impenetrable surface. Direct comparisons between FLMC and LSCF results, both of which are based on the same Hamiltonian (thus without any parameter-fitting between them), unambiguously and quantitatively reveal the fluctuations/correlations neglected by the latter. We studied both the structure (including the canonical-ensemble averages of the height and the mean-square end-to-end distances of grafted polymers) and thermodynamics (including the ensemble-averaged reduced energy density and the related internal energy per chain, the differences in the Helmholtz free energy and entropy per chain from the uncompressed state, and the pressure due to compression) of the system. In particular, we generalized the method for calculating pressure in lattice Monte Carlo simulations proposed by Dickman [J. Chem. Phys. 87, 2246 (1987)], and combined it with the Wang-Landau–Optimized Ensemble sampling [S. Trebst, D. A. Huse, and M. Troyer, Phys. Rev. E 70, 046701 (2004)] to efficiently and accurately calculate the free energy difference and the pressure due to compression. While we mainly examined the effects of the degree of compression, the distance between the nearest-neighbor grafting points, the reduced number of chains grafted at each grafting point, and the system fluctuations/correlations in an athermal solvent, the ?-solvent is also considered in some cases.

  5. Goal-oriented sensitivity analysis for lattice kinetic Monte Carlo simulations

    SciTech Connect (OSTI)

    Arampatzis, Georgios, E-mail: garab@math.uoc.gr [Department of Applied Mathematics, University of Crete (Greece) [Department of Applied Mathematics, University of Crete (Greece); Department of Mathematics and Statistics, University of Massachusetts, Amherst, Massachusetts 01003 (United States); Katsoulakis, Markos A., E-mail: markos@math.umass.edu [Department of Mathematics and Statistics, University of Massachusetts, Amherst, Massachusetts 01003 (United States)

    2014-03-28T23:59:59.000Z

    In this paper we propose a new class of coupling methods for the sensitivity analysis of high dimensional stochastic systems and in particular for lattice Kinetic Monte Carlo (KMC). Sensitivity analysis for stochastic systems is typically based on approximating continuous derivatives with respect to model parameters by the mean value of samples from a finite difference scheme. Instead of using independent samples the proposed algorithm reduces the variance of the estimator by developing a strongly correlated-“coupled”- stochastic process for both the perturbed and unperturbed stochastic processes, defined in a common state space. The novelty of our construction is that the new coupled process depends on the targeted observables, e.g., coverage, Hamiltonian, spatial correlations, surface roughness, etc., hence we refer to the proposed method as goal-oriented sensitivity analysis. In particular, the rates of the coupled Continuous Time Markov Chain are obtained as solutions to a goal-oriented optimization problem, depending on the observable of interest, by considering the minimization functional of the corresponding variance. We show that this functional can be used as a diagnostic tool for the design and evaluation of different classes of couplings. Furthermore, the resulting KMC sensitivity algorithm has an easy implementation that is based on the Bortz–Kalos–Lebowitz algorithm's philosophy, where events are divided in classes depending on level sets of the observable of interest. Finally, we demonstrate in several examples including adsorption, desorption, and diffusion Kinetic Monte Carlo that for the same confidence interval and observable, the proposed goal-oriented algorithm can be two orders of magnitude faster than existing coupling algorithms for spatial KMC such as the Common Random Number approach. We also provide a complete implementation of the proposed sensitivity analysis algorithms, including various spatial KMC examples, in a supplementary MATLAB source code.

  6. Determination of peripheral underdosage at the lung-tumor interface using Monte Carlo radiation transport calculations

    SciTech Connect (OSTI)

    Taylor, Michael, E-mail: michael.taylor@rmit.edu.au [School of Applied Sciences, College of Science, Engineering and Health, RMIT University, Melbourne, Victoria (Australia); Physical Sciences, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Dunn, Leon; Kron, Tomas; Height, Felicity; Franich, Rick [School of Applied Sciences, College of Science, Engineering and Health, RMIT University, Melbourne, Victoria (Australia); Physical Sciences, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia)

    2012-04-01T23:59:59.000Z

    Prediction of dose distributions in close proximity to interfaces is difficult. In the context of radiotherapy of lung tumors, this may affect the minimum dose received by lesions and is particularly important when prescribing dose to covering isodoses. The objective of this work is to quantify underdosage in key regions around a hypothetical target using Monte Carlo dose calculation methods, and to develop a factor for clinical estimation of such underdosage. A systematic set of calculations are undertaken using 2 Monte Carlo radiation transport codes (EGSnrc and GEANT4). Discrepancies in dose are determined for a number of parameters, including beam energy, tumor size, field size, and distance from chest wall. Calculations were performed for 1-mm{sup 3} regions at proximal, distal, and lateral aspects of a spherical tumor, determined for a 6-MV and a 15-MV photon beam. The simulations indicate regions of tumor underdose at the tumor-lung interface. Results are presented as ratios of the dose at key peripheral regions to the dose at the center of the tumor, a point at which the treatment planning system (TPS) predicts the dose more reliably. Comparison with TPS data (pencil-beam convolution) indicates such underdosage would not have been predicted accurately in the clinic. We define a dose reduction factor (DRF) as the average of the dose in the periphery in the 6 cardinal directions divided by the central dose in the target, the mean of which is 0.97 and 0.95 for a 6-MV and 15-MV beam, respectively. The DRF can assist clinicians in the estimation of the magnitude of potential discrepancies between prescribed and delivered dose distributions as a function of tumor size and location. Calculation for a systematic set of 'generic' tumors allows application to many classes of patient case, and is particularly useful for interpreting clinical trial data.

  7. SU-E-T-344: Validation and Clinical Experience of Eclipse Electron Monte Carlo Algorithm (EMC)

    SciTech Connect (OSTI)

    Pokharel, S [21st Century Oncology, Fort Myers, FL (United States); Rana, S [Procure Proton Therapy Center, Oklahoma City, OK (United States)

    2014-06-01T23:59:59.000Z

    Purpose: The purpose of this study is to validate Eclipse Electron Monte Carlo (Algorithm for routine clinical uses. Methods: The PTW inhomogeneity phantom (T40037) with different combination of heterogeneous slabs has been CT-scanned with Philips Brilliance 16 slice scanner. The phantom contains blocks of Rando Alderson materials mimicking lung, Polystyrene (Tissue), PTFE (Bone) and PMAA. The phantom has 30×30×2.5 cm base plate with 2cm recesses to insert inhomogeneity. The detector systems used in this study are diode, tlds and Gafchromic EBT2 films. The diode and tlds were included in CT scans. The CT sets are transferred to Eclipse treatment planning system. Several plans have been created with Eclipse Monte Carlo (EMC) algorithm 11.0.21. Measurements have been carried out in Varian TrueBeam machine for energy from 6–22mev. Results: The measured and calculated doses agreed very well for tissue like media. The agreement was reasonably okay for the presence of lung inhomogeneity. The point dose agreement was within 3.5% and Gamma passing rate at 3%/3mm was greater than 93% except for 6Mev(85%). The disagreement can reach as high as 10% in the presence of bone inhomogeneity. This is due to eclipse reporting dose to the medium as opposed to the dose to the water as in conventional calculation engines. Conclusion: Care must be taken when using Varian Eclipse EMC algorithm for dose calculation for routine clinical uses. The algorithm dose not report dose to water in which most of the clinical experiences are based on rather it just reports dose to medium directly. In the presence of inhomogeneity such as bone, the dose discrepancy can be as high as 10% or even more depending on the location of normalization point or volume. As Radiation oncology as an empirical science, care must be taken before using EMC reported monitor units for clinical uses.

  8. On-the-fly generation of differential resonance scattering probability distribution functions for Monte Carlo codes

    SciTech Connect (OSTI)

    Sunny, E. E.; Martin, W. R. [University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor MI 48109 (United States)

    2013-07-01T23:59:59.000Z

    Current Monte Carlo codes use one of three models to model neutron scattering in the epithermal energy range: (1) the asymptotic scattering model, (2) the free gas scattering model, or (3) the S({alpha},{beta}) model, depending on the neutron energy and the specific Monte Carlo code. The free gas scattering model assumes the scattering cross section is constant over the neutron energy range, which is usually a good approximation for light nuclei, but not for heavy nuclei where the scattering cross section may have several resonances in the epithermal region. Several researchers in the field have shown that using the free gas scattering model in the vicinity of the resonances in the lower epithermal range can under-predict resonance absorption due to the up-scattering phenomenon. Existing methods all involve performing the collision analysis in the center-of-mass frame, followed by a conversion back to the laboratory frame. In this paper, we will present a new sampling methodology that (1) accounts for the energy-dependent scattering cross sections in the collision analysis and (2) acts in the laboratory frame, avoiding the conversion to the center-of-mass frame. The energy dependence of the scattering cross section was modeled with even-ordered polynomials to approximate the scattering cross section in Blackshaw's equations for the moments of the differential scattering PDFs. These moments were used to sample the outgoing neutron speed and angle in the laboratory frame on-the-fly during the random walk of the neutron. Results for criticality studies on fuel pin and fuel assembly calculations using these methods showed very close comparison to results using the reference Doppler-broadened rejection correction (DBRC) scheme. (authors)

  9. Implementation of the probability table method in a continuous-energy Monte Carlo code system

    SciTech Connect (OSTI)

    Sutton, T.M.; Brown, F.B. [Lockheed Martin Corp., Schenectady, NY (United States)

    1998-10-01T23:59:59.000Z

    RACER is a particle-transport Monte Carlo code that utilizes a continuous-energy treatment for neutrons and neutron cross section data. Until recently, neutron cross sections in the unresolved resonance range (URR) have been treated in RACER using smooth, dilute-average representations. This paper describes how RACER has been modified to use probability tables to treat cross sections in the URR, and the computer codes that have been developed to compute the tables from the unresolved resonance parameters contained in ENDF/B data files. A companion paper presents results of Monte Carlo calculations that demonstrate the effect of the use of probability tables versus the use of dilute-average cross sections for the URR. The next section provides a brief review of the probability table method as implemented in the RACER system. The production of the probability tables for use by RACER takes place in two steps. The first step is the generation of probability tables from the nuclear parameters contained in the ENDF/B data files. This step, and the code written to perform it, are described in Section 3. The tables produced are at energy points determined by the ENDF/B parameters and/or accuracy considerations. The tables actually used in the RACER calculations are obtained in the second step from those produced in the first. These tables are generated at energy points specific to the RACER calculation. Section 4 describes this step and the code written to implement it, as well as modifications made to RACER to enable it to use the tables. Finally, some results and conclusions are presented in Section 5.

  10. Aurora A is involved in central spindle assembly through phosphorylation of Ser 19 in P150Glued David Reboutier, Marie-Brengre Troadec, Jean-Yves Cremet, Lucie Chauvin, Vincent Guen, Patrick Salaun, and Claude Prigent

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Aurora A is involved in central spindle assembly through phosphorylation of Ser 19 in P150Glued endogenous Aurora A: the sequence 59-CCTGTCTTACTGT-39, between positions 729 and 741, was replaced with 59 signaling molecules participate in this regulation, and they include the Aurora A kinase. Some

  11. Systemic toxicity of dermally applied crude oils in rats

    SciTech Connect (OSTI)

    Feuston, M.H.; Mackerer, C.R.; Schreiner, C.A.; Hamilton, C.E. [Stonybrook Labs., Inc., Princeton, NJ (United States)] [Stonybrook Labs., Inc., Princeton, NJ (United States)

    1997-12-31T23:59:59.000Z

    Two crude oils, differing in viscosity (V) and nitrogen (N) and sulfur (S) content, were evaluated for systemic toxicity, In the Crude I (low V, low N, low S) study, the material was applied to the clipped backs of rats at dose levels of 0, 30, 125, and 500 mg/kg. In the Crude II (high V, high N, moderate S) study, the oil was applied similarly at the same dose levels. The crude oils were applied for 13 wk, 5 d/wk. Exposure sites were not occluded. Mean body weight gain (wk 1-14) was significantly reduced in male rats exposed to Crude II; body weight gain of all other animals was not adversely affected by treatment. An increase in absolute (A) and relative (R) liver weights and a decrease in A and R thymus weights were observed in male and female rats exposed to Crude II at 500 mg/kg; only liver weights (A and R) were adversely affected in male and female rats exposed to Crude I. In general, there was no consistent pattern of toxicity for serum chemistry endpoints; however, more parameters were adversely affected in Crude II-exposed female rats than in the other exposed groups. A consistent pattern of toxicity for hematology endpoints was observed among male rats exposed to Crude I and male and female rats exposed to Crude II. Parameters affected included: Crudes I and II, red blood cell count, hemoglobin, and hematocrit, Crude II, platelet count. Microscopic evaluation of tissues revealed the following treatment-related findings: Crude I, treated skin, thymus, and thyroid; Crude II, bone marrow, treated skin, thymus, and thyroid. The LOEL (lowest observable effect level) for skin irritation and systemic toxicity (based on marginal effects on the thyroid) for both crude oils was 30 mg/kg; effects were more numerous and more pronounced in animals exposed to Crude II. Systemic effects are probably related to concentrations of polycyclic aromatic compounds (PAC) found in crude oil.

  12. Assessing the effects of Norway rats on auklet breeding success and survival at Sirius Point, Kiska

    E-Print Network [OSTI]

    Jones, Ian L.

    Assessing the effects of Norway rats on auklet breeding success and survival at Sirius Point, Kiska Introduction The presence of introduced Norway rats (Rattus norvegicus) has been implicated as a possible sightings of Norway rats at Sirius Point Colony during the late 1980s and early 1990s. Furthermore

  13. Marine Ornithology 41: 4148 (2013) Bond et al.: Crested Auklet survival with Norway Rats 41

    E-Print Network [OSTI]

    Jones, Ian L.

    Marine Ornithology 41: 41­48 (2013) Bond et al.: Crested Auklet survival with Norway Rats 41 in the Aleutians (Bailey 1993, Ebbert & Byrd 2002). Another introduced predator, the Norway rat Rattus norvegicus AND REPRODUCTIVE SUCCESS OF CRESTED AUKLETS AETHIA CRISTATELLA IN THE PRESENCE OF INTRODUCED NORWAY RATS RATTUS

  14. Variations in the diet of introduced Norway rats (Rattus norvegicus) inferred using stable isotope analysis

    E-Print Network [OSTI]

    Jones, Ian L.

    Variations in the diet of introduced Norway rats (Rattus norvegicus) inferred using stable isotope predators; island ecosystem conservation; stable isotope analysis; Norway rats; diet. Correspondence Heather of introduced Norway rats Rattus norvegicus has raised concerns for the fate of the large least auklet Aethia

  15. Stimulus Control of Maternal Responsiveness to Norway Rat (Rattus norvegicus) Pup Ultrasonic Vocalizations

    E-Print Network [OSTI]

    Stimulus Control of Maternal Responsiveness to Norway Rat (Rattus norvegicus) Pup Ultrasonic be considered a specialization of Norway rats and other small rodents. When removed from the nest and placed in a cool environment, infant Norway rats emit USVs. These vocalizations range from 30 to 50 k

  16. STABLE FREQUENCY RESPONSE TO VARYING STIMULUS INTENSITY IN A MODEL OF THE RAT OLFACTORY BULB

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    STABLE FREQUENCY RESPONSE TO VARYING STIMULUS INTENSITY IN A MODEL OF THE RAT OLFACTORY BULB Thomas Neurosciences et Systèmes sensoriels, CNRS UMR 5020, Lyon, France ABSTRACT In the rat olfactory bulb (OB), fast. Introduction The rat olfactory bulb (OB) is a rich and complex sensory processing system that shows stimulus

  17. Inhalation developmental toxicology studies: Gallium arsenide in mice and rats

    SciTech Connect (OSTI)

    Mast, T.J.; Greenspan, B.J.; Dill, J.A.; Stoney, K.H.; Evanoff, J.J.; Rommereim, R.L.

    1990-12-01T23:59:59.000Z

    Gallium arsenide is a crystalline compound used extensively in the semiconductor industry. Workers preparing solar cells and gallium arsenide ingots and wafers are potentially at risk from the inhalation of gallium arsenide dust. The potential for gallium arsenide to cause developmental toxicity was assessed in Sprague- Dawley rats and CD-1 (Swiss) mice exposed to 0, 10, 37, or 75 mg/m{sup 3} gallium arsenide, 6 h/day, 7 days/week. Each of the four treatment groups consisted of 10 virgin females (for comparison), and {approx}30 positively mated rats or {approx}24 positively mated mice. Mice were exposed on 4--17 days of gestation (dg), and rats on 4--19 dg. The day of plug or sperm detection was designated as 0 dg. Body weights were obtained throughout the study period, and uterine and fetal body weights were obtained at sacrifice (rats, 20 dg; mice, 18 dg). Implants were enumerated and their status recorded. Live fetuses were sexed and examined for gross, visceral, skeletal, and soft-tissue craniofacial defects. Gallium and arsenic concentrations were determined in the maternal blood and uterine contents of the rats (3/group) at 7, 14, and 20 dg. 37 refs., 11 figs., 30 tabs.

  18. Inhalation developmental toxicology studies: Acetonitrile in rats. Final report

    SciTech Connect (OSTI)

    Mast, T.J.; Weigel, R.J.; Westerberg, R.B.; Boyd, P.J.; Hayden, B.K.; Evanoff, J.J.; Rommereim, R.L.

    1994-02-01T23:59:59.000Z

    The potential for acetonitrile to cause developmental toxicity was assessed in Sprague-Dawley rats exposed to 0, 100, 400, or 1200 ppM acetonitrile, 6 hours/day, 7 days/week. Exposure of rats to these concentrations of acetonitrile resulted in mortality in the 1200 ppM group (2/33 pregnant females; 1/10 non-pregnant females). However, there were no treatment-related effects upon body weights or reproduction indices at any exposure level, nor was there a significant increase in the incidence of fetal malformations or variations. The only effect observed in the fetuses was a slight, but not statiscally significant, exposure-correlated increase in the incidence of supernumerary ribs. Determination of acetonitrile and cyanide concentrations in maternal rat blood showed that acetonitrile concentration in the blood increased with exposure concentration for all exposed maternal rats. Detectable amounts of cyanide in the blood were found only in the rats exposed to 1200 ppM acetonitrile ({approximately}2 {mu}g cyanide/g of blood).

  19. A Monte Carlo procedure for the construction of complementary cumulative distribution functions for comparison with the EPA release limits for radioactive waste disposal

    SciTech Connect (OSTI)

    Helton, J.C.; Shiver, A.W.

    1994-10-01T23:59:59.000Z

    A Monte Carlo procedure for the construction of complementary cumulative distribution functions (CCDFs) for comparison with the US Environmental Protection Agency (EPA) release limits for radioactive waste disposal (40 CFR 191, Subpart B) is described and illustrated with results from a recent performance assessment (PA) for the Waste Isolation Pilot Plant (WIPP). The Monte Carlo procedure produces CCDF estimates similar to those obtained with stratified sampling in several recent PAs for the WIPP. The advantages of the Monte Carlo procedure over stratified sampling include increased resolution in the calculation of probabilities for complex scenarios involving drilling intrusions and better use of the necessarily limited number of mechanistic calculations that underlie CCDF construction.

  20. Lipid droplets fusion in adipocyte differentiated 3T3-L1 cells: A Monte Carlo simulation

    SciTech Connect (OSTI)

    Boschi, Federico, E-mail: federico.boschi@univr.it [Department of Neurological and Movement Sciences, University of Verona, Strada Le Grazie 8, 37134 Verona (Italy); Department of Computer Science, University of Verona, Strada Le Grazie 15, 37134 Verona (Italy); Rizzatti, Vanni; Zamboni, Mauro [Department of Medicine, Geriatric Section, University of Verona, Piazzale Stefani 1, 37126 Verona (Italy); Sbarbati, Andrea [Department of Neurological and Movement Sciences, University of Verona, Strada Le Grazie 8, 37134 Verona (Italy)

    2014-02-15T23:59:59.000Z

    Several human worldwide diseases like obesity, type 2 diabetes, hepatic steatosis, atherosclerosis and other metabolic pathologies are related to the excessive accumulation of lipids in cells. Lipids accumulate in spherical cellular inclusions called lipid droplets (LDs) whose sizes range from fraction to one hundred of micrometers in adipocytes. It has been suggested that LDs can grow in size due to a fusion process by which a larger LD is obtained with spherical shape and volume equal to the sum of the progenitors’ ones. In this study, the size distribution of two populations of LDs was analyzed in immature and mature (5-days differentiated) 3T3-L1 adipocytes (first and second populations, respectively) after Oil Red O staining. A Monte Carlo simulation of interaction between LDs has been developed in order to quantify the size distribution and the number of fusion events needed to obtain the distribution of the second population size starting from the first one. Four models are presented here based on different kinds of interaction: a surface weighted interaction (R2 Model), a volume weighted interaction (R3 Model), a random interaction (Random model) and an interaction related to the place where the LDs are born (Nearest Model). The last two models mimic quite well the behavior found in the experimental data. This work represents a first step in developing numerical simulations of the LDs growth process. Due to the complex phenomena involving LDs (absorption, growth through additional neutral lipid deposition in existing droplets, de novo formation and catabolism) the study focuses on the fusion process. The results suggest that, to obtain the observed size distribution, a number of fusion events comparable with the number of LDs themselves is needed. Moreover the MC approach results a powerful tool for investigating the LDs growth process. Highlights: • We evaluated the role of the fusion process in the synthesis of the lipid droplets. • We compared the size distribution of the lipid droplets in immature and mature cells. • We used the Monte Carlo simulation approach, simulating 10 thousand of fusion events. • Four different interaction models between the lipid droplets were tested. • The best model which mimics the experimental measures was selected.

  1. Geometrical splitting technique to improve the computational efficiency in Monte Carlo calculations for proton therapy

    SciTech Connect (OSTI)

    Ramos-Mendez, Jose [Benemerita Universidad Autonoma de Puebla, 18 Sur and San Claudio Avenue, Puebla, Puebla 72750 (Mexico); Perl, Joseph [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Faddegon, Bruce [Department of Radiation Oncology, University of California at San Francisco, California 94143 (United States); Schuemann, Jan; Paganetti, Harald [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 (United States)

    2013-04-15T23:59:59.000Z

    Purpose: To present the implementation and validation of a geometrical based variance reduction technique for the calculation of phase space data for proton therapy dose calculation. Methods: The treatment heads at the Francis H Burr Proton Therapy Center were modeled with a new Monte Carlo tool (TOPAS based on Geant4). For variance reduction purposes, two particle-splitting planes were implemented. First, the particles were split upstream of the second scatterer or at the second ionization chamber. Then, particles reaching another plane immediately upstream of the field specific aperture were split again. In each case, particles were split by a factor of 8. At the second ionization chamber and at the latter plane, the cylindrical symmetry of the proton beam was exploited to position the split particles at randomly spaced locations rotated around the beam axis. Phase space data in IAEA format were recorded at the treatment head exit and the computational efficiency was calculated. Depth-dose curves and beam profiles were analyzed. Dose distributions were compared for a voxelized water phantom for different treatment fields for both the reference and optimized simulations. In addition, dose in two patients was simulated with and without particle splitting to compare the efficiency and accuracy of the technique. Results: A normalized computational efficiency gain of a factor of 10-20.3 was reached for phase space calculations for the different treatment head options simulated. Depth-dose curves and beam profiles were in reasonable agreement with the simulation done without splitting: within 1% for depth-dose with an average difference of (0.2 {+-} 0.4)%, 1 standard deviation, and a 0.3% statistical uncertainty of the simulations in the high dose region; 1.6% for planar fluence with an average difference of (0.4 {+-} 0.5)% and a statistical uncertainty of 0.3% in the high fluence region. The percentage differences between dose distributions in water for simulations done with and without particle splitting were within the accepted clinical tolerance of 2%, with a 0.4% statistical uncertainty. For the two patient geometries considered, head and prostate, the efficiency gain was 20.9 and 14.7, respectively, with the percentages of voxels with gamma indices lower than unity 98.9% and 99.7%, respectively, using 2% and 2 mm criteria. Conclusions: The authors have implemented an efficient variance reduction technique with significant speed improvements for proton Monte Carlo simulations. The method can be transferred to other codes and other treatment heads.

  2. Monte Carlo calculations of the anisotropic engineering moduli for crystalline RDX (0 GPa {le} p {le} 4 GPa)

    SciTech Connect (OSTI)

    Bennett, C.M. [Los Alamos National Lab., NM (United States). Theoretical Div.]|[Oklahoma State Univ., Stillwater, OK (United States). Dept. of Chemistry; Sewell, T.D. [Los Alamos National Lab., NM (United States). Theoretical Div.

    1998-12-31T23:59:59.000Z

    Isothermal-iosbaric Monte Carlo calculations are used in conjunction with an expression that relates the elastic stiffness tensor to the mean-square fluctuations of the strain tensor to obtain first principles predictions of the Young`s moduli, shear moduli, and Poisson`s ratios for room-temperature crystalline RDX. The results are based on numerical data obtained during previously reported calculations of the hydrostatic compression of RDX over the pressure domain 0 GPa {le} p {le} 4 GPa. Although there are no experimental data available for comparison, the predicted values of the engineering coefficients are in accord with general expectations for brittle molecular crystals. The calculations reported here are preliminary: more extensive Monte Carlo realizations are needed to yield well-converged predictions; these are underway for RDX and {beta}-HMX.

  3. Beyond chemical accuracy: The pseudopotential approximation in diffusion Monte Carlo calculations of the HCP to BCC phase transition in beryllium

    E-Print Network [OSTI]

    Shulenburger, Luke; Desjarlais, M P

    2015-01-01T23:59:59.000Z

    Motivated by the disagreement between recent diffusion Monte Carlo calculations and experiments on the phase transition pressure between the ambient and beta-Sn phases of silicon, we present a study of the HCP to BCC phase transition in beryllium. This lighter element provides an oppor- tunity for directly testing many of the approximations required for calculations on silicon and may suggest a path towards increasing the practical accuracy of diffusion Monte Carlo calculations of solids in general. We demonstrate that the single largest approximation in these calculations is the pseudopotential approximation. After removing this we find excellent agreement with experiment for the ambient HCP phase and results similar to careful calculations using density functional theory for the phase transition pressure.

  4. Multilevel Monte Carlo for two phase flow and Buckley–Leverett transport in random heterogeneous porous media

    SciTech Connect (OSTI)

    Müller, Florian, E-mail: florian.mueller@sam.math.ethz.ch; Jenny, Patrick, E-mail: jenny@ifd.mavt.ethz.ch; Meyer, Daniel W., E-mail: meyerda@ethz.ch

    2013-10-01T23:59:59.000Z

    Monte Carlo (MC) is a well known method for quantifying uncertainty arising for example in subsurface flow problems. Although robust and easy to implement, MC suffers from slow convergence. Extending MC by means of multigrid techniques yields the multilevel Monte Carlo (MLMC) method. MLMC has proven to greatly accelerate MC for several applications including stochastic ordinary differential equations in finance, elliptic stochastic partial differential equations and also hyperbolic problems. In this study, MLMC is combined with a streamline-based solver to assess uncertain two phase flow and Buckley–Leverett transport in random heterogeneous porous media. The performance of MLMC is compared to MC for a two dimensional reservoir with a multi-point Gaussian logarithmic permeability field. The influence of the variance and the correlation length of the logarithmic permeability on the MLMC performance is studied.

  5. Energy and contact of one-dimensional fermions in a harmonic trap via non-uniform lattice Monte Carlo

    E-Print Network [OSTI]

    C. E. Berger; E. R. Anderson; J. E. Drut

    2014-10-29T23:59:59.000Z

    We determine the ground-state energy and Tan's contact of attractively interacting few-fermion systems in a one-dimensional harmonic trap, for a range of couplings and particle numbers. To this end, we implement a new lattice Monte Carlo approach based on a non-uniform discretization of space, defined via Gauss-Hermite quadrature points and weights. This particular coordinate basis is natural for systems in harmonic traps, and it yields a position-dependent coupling and a corresponding non-uniform Hubbard-Stratonovich transformation. The resulting path integral is performed with hybrid Monte Carlo as a proof of principle for calculations at finite temperature and in higher dimensions.

  6. Monte Carlo analysis of a monolithic interconnected module with a back surface reflector

    SciTech Connect (OSTI)

    Ballinger, C.T.; Charache, G.W. [Lockheed Martin Corp., Schenectady, NY (United States); Murray, C.S. [Bettis Atomic Power Lab., West Mifflin, PA (United States)

    1998-10-01T23:59:59.000Z

    Recently, the photon Monte Carlo code, RACER-X, was modified to include wave-length dependent absorption coefficients and indices of refraction. This work was done in an effort to increase the code`s capabilities to be more applicable to a wider range of problems. These new features make RACER-X useful for analyzing devices like monolithic interconnected modules (MIMs) which have etched surface features and incorporates a back surface reflector (BSR) for spectral control. A series of calculations were performed on various MIM structures to determine the impact that surface features and component reflectivities have on spectral utilization. The traditional concern of cavity photonics is replaced with intra-cell photonics in the MIM design. Like the cavity photonic problems previously discussed, small changes in optical properties and/or geometry can lead to large changes in spectral utilization. The calculations show that seemingly innocuous surface features (e.g., trenches and grid lines) can significantly reduce the spectral utilization due to the non-normal incident photon flux. Photons that enter the device through a trench edge are refracted onto a trajectory where they will not escape. This leads to a reduction in the number of reflected below bandgap photons that return to the radiator and reduce the spectral utilization. In addition, trenches expose a lateral conduction layer in this particular series of calculations which increase the absorption of above bandgap photons in inactive material.

  7. Evaluation of vectorized Monte Carlo algorithms on GPUs for a neutron Eigenvalue problem

    SciTech Connect (OSTI)

    Du, X.; Liu, T.; Ji, W.; Xu, X. G. [Nuclear Engineering Program, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Brown, F. B. [Monte Carlo Codes Group, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2013-07-01T23:59:59.000Z

    Conventional Monte Carlo (MC) methods for radiation transport computations are 'history-based', which means that one particle history at a time is tracked. Simulations based on such methods suffer from thread divergence on the graphics processing unit (GPU), which severely affects the performance of GPUs. To circumvent this limitation, event-based vectorized MC algorithms can be utilized. A versatile software test-bed, called ARCHER - Accelerated Radiation-transport Computations in Heterogeneous Environments - was used for this study. ARCHER facilitates the development and testing of a MC code based on the vectorized MC algorithm implemented on GPUs by using NVIDIA's Compute Unified Device Architecture (CUDA). The ARCHER{sub GPU} code was designed to solve a neutron eigenvalue problem and was tested on a NVIDIA Tesla M2090 Fermi card. We found that although the vectorized MC method significantly reduces the occurrence of divergent branching and enhances the warp execution efficiency, the overall simulation speed is ten times slower than the conventional history-based MC method on GPUs. By analyzing detailed GPU profiling information from ARCHER, we discovered that the main reason was the large amount of global memory transactions, causing severe memory access latency. Several possible solutions to alleviate the memory latency issue are discussed. (authors)

  8. An Analytic Linear Accelerator Source Model for Monte Carlo Dose Calculations. I. Model Representation and Construction

    E-Print Network [OSTI]

    Tian, Zhen; Folkerts, Michael; Shi, Feng; Jiang, Steve B; Jia, Xun

    2015-01-01T23:59:59.000Z

    Monte Carlo (MC) simulation is considered as the most accurate method for radiation dose calculations. Accuracy of a source model for a linear accelerator is critical for the overall dose calculation accuracy. In this paper, we presented an analytical source model that we recently developed for GPU-based MC dose calculations. A key concept called phase-space-ring (PSR) was proposed. It contained a group of particles that are of the same type and close in energy and radial distance to the center of the phase-space plane. The model parameterized probability densities of particle location, direction and energy for each primary photon PSR, scattered photon PSR and electron PSR. For a primary photon PSRs, the particle direction is assumed to be from the beam spot. A finite spot size is modeled with a 2D Gaussian distribution. For a scattered photon PSR, multiple Gaussian components were used to model the particle direction. The direction distribution of an electron PSRs was also modeled as a 2D Gaussian distributi...

  9. A kinetic Monte Carlo method for the simulation of massive phase transformations

    SciTech Connect (OSTI)

    Bos, C.; Sommer, F.; Mittemeijer, E.J

    2004-07-12T23:59:59.000Z

    A multi-lattice kinetic Monte Carlo method has been developed for the atomistic simulation of massive phase transformations. Beside sites on the crystal lattices of the parent and product phase, randomly placed sites are incorporated as possible positions. These random sites allow the atoms to take favourable intermediate positions, essential for a realistic description of transformation interfaces. The transformation from fcc to bcc starting from a flat interface with the fcc(1 1 1)//bcc(1 1 0) and fcc[1 1 1-bar]//bcc[0 0 1-bar] orientation in a single component system has been simulated. Growth occurs in two different modes depending on the chosen values of the bond energies. For larger fcc-bcc energy differences, continuous growth is observed with a rough transformation front. For smaller energy differences, plane-by-plane growth is observed. In this growth mode two-dimensional nucleation is required in the next fcc plane after completion of the transformation of the previous fcc plane.

  10. Fractal space-times under the microscope: A Renormalization Group view on Monte Carlo data

    E-Print Network [OSTI]

    Martin Reuter; Frank Saueressig

    2011-10-24T23:59:59.000Z

    The emergence of fractal features in the microscopic structure of space-time is a common theme in many approaches to quantum gravity. In this work we carry out a detailed renormalization group study of the spectral dimension $d_s$ and walk dimension $d_w$ associated with the effective space-times of asymptotically safe Quantum Einstein Gravity (QEG). We discover three scaling regimes where these generalized dimensions are approximately constant for an extended range of length scales: a classical regime where $d_s = d, d_w = 2$, a semi-classical regime where $d_s = 2d/(2+d), d_w = 2+d$, and the UV-fixed point regime where $d_s = d/2, d_w = 4$. On the length scales covered by three-dimensional Monte Carlo simulations, the resulting spectral dimension is shown to be in very good agreement with the data. This comparison also provides a natural explanation for the apparent puzzle between the short distance behavior of the spectral dimension reported from Causal Dynamical Triangulations (CDT), Euclidean Dynamical Triangulations (EDT), and Asymptotic Safety.

  11. Predicting image blur in proton radiography: comparisons between measurements and Monte Carlo simulations

    SciTech Connect (OSTI)

    von Wittenau, A; Aufderheide, M B; Henderson, G L

    2010-05-07T23:59:59.000Z

    Given the cost and lead-times involved in high-energy proton radiography, it is prudent to model proposed radiographic experiments to see if the images predicted would return useful information. We recently modified our raytracing transmission radiography modeling code HADES to perform simplified Monte Carlo simulations of the transport of protons in a proton radiography beamline. Beamline objects include the initial diffuser, vacuum magnetic fields, windows, angle-selecting collimators, and objects described as distorted 2D (planar or cylindrical) meshes or as distorted 3D hexahedral meshes. We present an overview of the algorithms used for the modeling and code timings for simulations through typical 2D and 3D meshes. We next calculate expected changes in image blur as scattering materials are placed upstream and downstream of a resolution test object (a 3 mm thick sheet of tantalum, into which 0.4 mm wide slits have been cut), and as the current supplied to the focusing magnets is varied. We compare and contrast the resulting simulations with the results of measurements obtained at the 800 MeV Los Alamos LANSCE Line-C proton radiography facility.

  12. Kinetic Monte Carlo Simulations and Molecular Conductance Measurements of the Bacterial Decaheme Cytochrome MtrF

    SciTech Connect (OSTI)

    Byun, H. S.; Pirbadian, S.; Nakano, Aiichiro; Shi, Liang; El-Naggar, Mohamed Y.

    2014-09-05T23:59:59.000Z

    Microorganisms overcome the considerable hurdle of respiring extracellular solid substrates by deploying large multiheme cytochrome complexes that form 20 nanometer conduits to traffic electrons through the periplasm and across the cellular outer membrane. Here we report the first kinetic Monte Carlo simulations and single-molecule scanning tunneling microscopy (STM) measurements of the Shewanella oneidensis MR-1 outer membrane decaheme cytochrome MtrF, which can perform the final electron transfer step from cells to minerals and microbial fuel cell anodes. We find that the calculated electron transport rate through MtrF is consistent with previously reported in vitro measurements of the Shewanella Mtr complex, as well as in vivo respiration rates on electrode surfaces assuming a reasonable (experimentally verified) coverage of cytochromes on the cell surface. The simulations also reveal a rich phase diagram in the overall electron occupation density of the hemes as a function of electron injection and ejection rates. Single molecule tunneling spectroscopy confirms MtrF's ability to mediate electron transport between an STM tip and an underlying Au(111) surface, but at rates higher than expected from previously calculated heme-heme electron transfer rates for solvated molecules.

  13. Feasibility of a Monte Carlo-deterministic hybrid method for fast reactor analysis

    SciTech Connect (OSTI)

    Heo, W.; Kim, W.; Kim, Y. [Korea Advanced Institute of Science and Technology - KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701 (Korea, Republic of); Yun, S. [Korea Atomic Energy Research Institute - KAERI, 989-111 Daedeok-daero, Yuseong-gu, Daejeon, 305-353 (Korea, Republic of)

    2013-07-01T23:59:59.000Z

    A Monte Carlo and deterministic hybrid method is investigated for the analysis of fast reactors in this paper. Effective multi-group cross sections data are generated using a collision estimator in the MCNP5. A high order Legendre scattering cross section data generation module was added into the MCNP5 code. Both cross section data generated from MCNP5 and TRANSX/TWODANT using the homogeneous core model were compared, and were applied to DIF3D code for fast reactor core analysis of a 300 MWe SFR TRU burner core. For this analysis, 9 groups macroscopic-wise data was used. In this paper, a hybrid calculation MCNP5/DIF3D was used to analyze the core model. The cross section data was generated using MCNP5. The k{sub eff} and core power distribution were calculated using the 54 triangle FDM code DIF3D. A whole core calculation of the heterogeneous core model using the MCNP5 was selected as a reference. In terms of the k{sub eff}, 9-group MCNP5/DIF3D has a discrepancy of -154 pcm from the reference solution, 9-group TRANSX/TWODANT/DIF3D analysis gives -1070 pcm discrepancy. (authors)

  14. Development of Subspace-based Hybrid Monte Carlo-Deterministric Algorithms for Reactor Physics Calculations

    SciTech Connect (OSTI)

    Abdel-Khalik, Hany S.; Gardner, Robin; Mattingly, John; Sood, Avneet

    2014-05-20T23:59:59.000Z

    The development of hybrid Monte-Carlo-Deterministic (MC-DT) approaches, taking place over the past few decades, have primarily focused on shielding and detection applications where the analysis requires a small number of responses, i.e. at the detector locations(s). This work further develops a recently introduced global variance reduction approach, denoted by the SUBSPACE approach is designed to allow the use of MC simulation, currently limited to benchmarking calculations, for routine engineering calulations. By way of demonstration, the SUBSPACE approach is applied to assembly level calculations used to generate the few-group homogenized cross-sections. These models are typically expensive and need to be executed in the order of 10-10 times to properly characterize the few-group cross-sections for deownstream core-wide calculations. Applicability to k-eigenvalue core-wide models is also demonstrated in this work. Given the faborable results obtained in this work, we believe the applicability of the MC method for reactor analysis calculations could be realized in the near future.

  15. MONTE CARLO SIMULATIONS OF THE PHOTOSPHERIC EMISSION IN GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Begue, D.; Siutsou, I. A.; Vereshchagin, G. V. [University of Roma ''Sapienza'', I-00185, p.le A. Moro 5, Rome (Italy)

    2013-04-20T23:59:59.000Z

    We studied the decoupling of photons from ultra-relativistic spherically symmetric outflows expanding with constant velocity by means of Monte Carlo simulations. For outflows with finite widths we confirm the existence of two regimes: photon-thick and photon-thin, introduced recently by Ruffini et al. (RSV). The probability density function of the last scattering of photons is shown to be very different in these two cases. We also obtained spectra as well as light curves. In the photon-thick case, the time-integrated spectrum is much broader than the Planck function and its shape is well described by the fuzzy photosphere approximation introduced by RSV. In the photon-thin case, we confirm the crucial role of photon diffusion, hence the probability density of decoupling has a maximum near the diffusion radius well below the photosphere. The time-integrated spectrum of the photon-thin case has a Band shape that is produced when the outflow is optically thick and its peak is formed at the diffusion radius.

  16. MONTE CARLO SIMULATIONS OF NONLINEAR PARTICLE ACCELERATION IN PARALLEL TRANS-RELATIVISTIC SHOCKS

    SciTech Connect (OSTI)

    Ellison, Donald C.; Warren, Donald C. [Physics Department, North Carolina State University, Box 8202, Raleigh, NC 27695 (United States); Bykov, Andrei M., E-mail: don_ellison@ncsu.edu, E-mail: ambykov@yahoo.com [Ioffe Institute for Physics and Technology, 194021 St. Petersburg (Russian Federation)

    2013-10-10T23:59:59.000Z

    We present results from a Monte Carlo simulation of a parallel collisionless shock undergoing particle acceleration. Our simulation, which contains parameterized scattering and a particular thermal leakage injection model, calculates the feedback between accelerated particles ahead of the shock, which influence the shock precursor and 'smooth' the shock, and thermal particle injection. We show that there is a transition between nonrelativistic shocks, where the acceleration efficiency can be extremely high and the nonlinear compression ratio can be substantially greater than the Rankine-Hugoniot value, and fully relativistic shocks, where diffusive shock acceleration is less efficient and the compression ratio remains at the Rankine-Hugoniot value. This transition occurs in the trans-relativistic regime and, for the particular parameters we use, occurs around a shock Lorentz factor ?{sub 0} = 1.5. We also find that nonlinear shock smoothing dramatically reduces the acceleration efficiency presumed to occur with large-angle scattering in ultra-relativistic shocks. Our ability to seamlessly treat the transition from ultra-relativistic to trans-relativistic to nonrelativistic shocks may be important for evolving relativistic systems, such as gamma-ray bursts and Type Ibc supernovae. We expect a substantial evolution of shock accelerated spectra during this transition from soft early on to much harder when the blast-wave shock becomes nonrelativistic.

  17. Intra-Globular Structures in Multiblock Copolymer Chains from a Monte Carlo Simulation

    E-Print Network [OSTI]

    Krzysztof Lewandowski; Michal Banaszak

    2014-10-16T23:59:59.000Z

    Multiblock copolymer chains in implicit nonselective solvents are studied by Monte Carlo method which employs a parallel tempering algorithm. Chains consisting of 120 $A$ and 120 $B$ monomers, arranged in three distinct microarchitectures: $(10-10)_{12}$, $(6-6)_{20}$, and $(3-3)_{40}$, collapse to globular states upon cooling, as expected. By varying both the reduced temperature $T^*$ and compatibility between monomers $\\omega$, numerous intra-globular structures are obtained: diclusters (handshake, spiral, torus with a core, etc.), triclusters, and $n$-clusters with $n>3$ (lamellar and other), which are reminiscent of the block copolymer nanophases for spherically confined geometries. Phase diagrams for various chains in the $(T^*, \\omega)$-space are mapped. The structure factor $S(k)$, for a selected microarchitecture and $\\omega$, is calculated. Since $S(k)$ can be measured in scattering experiments, it can be used to relate simulation results to an experiment. Self-assembly in those systems is interpreted in term of competition between minimization of the interfacial area separating different types of monomers and minimization of contacts between chain and solvent. Finally, the relevance of this model to the protein folding is addressed.

  18. Monte Carlo Protein Folding: Simulations of Met-Enkephalin with Solvent-Accessible Area Parameterizations

    E-Print Network [OSTI]

    Hsiao-Ping Hsu; Bernd A. Berg; Peter Grassberger

    2004-08-26T23:59:59.000Z

    Treating realistically the ambient water is one of the main difficulties in applying Monte Carlo methods to protein folding. The solvent-accessible area method, a popular method for treating water implicitly, is investigated by means of Metropolis simulations of the brain peptide Met-Enkephalin. For the phenomenological energy function ECEPP/2 nine atomic solvation parameter (ASP) sets are studied that had been proposed by previous authors. The simulations are compared with each other, with simulations with a distance dependent electrostatic permittivity $\\epsilon (r)$, and with vacuum simulations ($\\epsilon =2$). Parallel tempering and a recently proposed biased Metropolis technique are employed and their performances are evaluated. The measured observables include energy and dihedral probability densities (pds), integrated autocorrelation times, and acceptance rates. Two of the ASP sets turn out to be unsuitable for these simulations. For all other sets, selected configurations are minimized in search of the global energy minima. Unique minima are found for the vacuum and the $\\epsilon(r)$ system, but for none of the ASP models. Other observables show a remarkable dependence on the ASPs. In particular, autocorrelation times vary dramatically with the ASP parameters. Three ASP sets have much smaller autocorrelations at 300 K than the vacuum simulations, opening the possibility that simulations can be speeded up vastly by judiciously chosing details of the force

  19. Iterative reconstruction using a Monte Carlo based system transfer matrix for dedicated breast positron emission tomography

    SciTech Connect (OSTI)

    Saha, Krishnendu [Ohio Medical Physics Consulting, Dublin, Ohio 43017 (United States); Straus, Kenneth J.; Glick, Stephen J. [Department of Radiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655 (United States); Chen, Yu. [Department of Radiation Oncology, Columbia University, New York, New York 10032 (United States)

    2014-08-28T23:59:59.000Z

    To maximize sensitivity, it is desirable that ring Positron Emission Tomography (PET) systems dedicated for imaging the breast have a small bore. Unfortunately, due to parallax error this causes substantial degradation in spatial resolution for objects near the periphery of the breast. In this work, a framework for computing and incorporating an accurate system matrix into iterative reconstruction is presented in an effort to reduce spatial resolution degradation towards the periphery of the breast. The GATE Monte Carlo Simulation software was utilized to accurately model the system matrix for a breast PET system. A strategy for increasing the count statistics in the system matrix computation and for reducing the system element storage space was used by calculating only a subset of matrix elements and then estimating the rest of the elements by using the geometric symmetry of the cylindrical scanner. To implement this strategy, polar voxel basis functions were used to represent the object, resulting in a block-circulant system matrix. Simulation studies using a breast PET scanner model with ring geometry demonstrated improved contrast at 45% reduced noise level and 1.5 to 3 times resolution performance improvement when compared to MLEM reconstruction using a simple line-integral model. The GATE based system matrix reconstruction technique promises to improve resolution and noise performance and reduce image distortion at FOV periphery compared to line-integral based system matrix reconstruction.

  20. Adjoint Monte Carlo Simulation of Fusion Product Activation Probe Experiment in ASDEX Upgrade tokamak

    E-Print Network [OSTI]

    Äkäslompolo, Simppa; Tardini, Giovanni; Kurki-Suonio, Taina

    2015-01-01T23:59:59.000Z

    The activation probe is a robust tool to measure flux of fusion products from a magnetically confined plasma. A carefully chosen solid sample is exposed to the flux, and the impinging ions transmute the material makig it radioactive. Ultra-low level gamma-ray spectroscopy is used post mortem to measure the activity and, thus, the number of fusion products. This contribution presents the numerical analysis of the first measurement in the ASDEX Upgrade tokamak, which was also the first experiment to measure a single discharge. The ASCOT suite of codes was used to perform adjoint/reverse Monte-Carlo calculations of the fusion products. The analysis facilitated, for the first time, a comparison of numerical and experimental values for absolutely calibrated flux. The results agree to within 40%, which can be considered remarkable considering the fact that all features of the plasma cannot be accounted in the simulations. Also an alternative probe orientation was studied. The results suggest that a better optimized...

  1. ITS Version 6 : the integrated TIGER series of coupled electron/photon Monte Carlo transport codes.

    SciTech Connect (OSTI)

    Franke, Brian Claude; Kensek, Ronald Patrick; Laub, Thomas William

    2008-04-01T23:59:59.000Z

    ITS is a powerful and user-friendly software package permitting state-of-the-art Monte Carlo solution of lineartime-independent coupled electron/photon radiation transport problems, with or without the presence of macroscopic electric and magnetic fields of arbitrary spatial dependence. Our goal has been to simultaneously maximize operational simplicity and physical accuracy. Through a set of preprocessor directives, the user selects one of the many ITS codes. The ease with which the makefile system is applied combines with an input scheme based on order-independent descriptive keywords that makes maximum use of defaults and internal error checking to provide experimentalists and theorists alike with a method for the routine but rigorous solution of sophisticated radiation transport problems. Physical rigor is provided by employing accurate cross sections, sampling distributions, and physical models for describing the production and transport of the electron/photon cascade from 1.0 GeV down to 1.0 keV. The availability of source code permits the more sophisticated user to tailor the codes to specific applications and to extend the capabilities of the codes to more complex applications. Version 6, the latest version of ITS, contains (1) improvements to the ITS 5.0 codes, and (2) conversion to Fortran 90. The general user friendliness of the software has been enhanced through memory allocation to reduce the need for users to modify and recompile the code.

  2. Computation of a Canadian SCWR unit cell with deterministic and Monte Carlo codes

    SciTech Connect (OSTI)

    Harrisson, G.; Marleau, G. [Inst. of Nuclear Engineering, Ecole Polytechnique de Montreal (Canada)

    2012-07-01T23:59:59.000Z

    The Canadian SCWR has the potential to achieve the goals that the generation IV nuclear reactors must meet. As part of the optimization process for this design concept, lattice cell calculations are routinely performed using deterministic codes. In this study, the first step (self-shielding treatment) of the computation scheme developed with the deterministic code DRAGON for the Canadian SCWR has been validated. Some options available in the module responsible for the resonance self-shielding calculation in DRAGON 3.06 and different microscopic cross section libraries based on the ENDF/B-VII.0 evaluated nuclear data file have been tested and compared to a reference calculation performed with the Monte Carlo code SERPENT under the same conditions. Compared to SERPENT, DRAGON underestimates the infinite multiplication factor in all cases. In general, the original Stammler model with the Livolant-Jeanpierre approximations are the most appropriate self-shielding options to use in this case of study. In addition, the 89 groups WIMS-AECL library for slight enriched uranium and the 172 groups WLUP library for a mixture of plutonium and thorium give the most consistent results with those of SERPENT. (authors)

  3. Collapse transitions in thermosensitive multi-block copolymers: A Monte Carlo study

    SciTech Connect (OSTI)

    Rissanou, Anastassia N., E-mail: rissanou@tem.uoc.gr [Department of Mathematics and Applied Mathematics, University of Crete, GR-71003 Heraklion Crete, Greece and Archimedes Center for Analysis, Modeling and Computation, University of Crete, P.O. Box 2208, GR-71003 Heraklion Crete (Greece); Tzeli, Despoina S. [Department of Materials Science and Technology, University of Crete, GR-71003 Heraklion Crete (Greece); Anastasiadis, Spiros H. [Department of Chemistry, University of Crete, P.O. Box 2208, 710 03 Heraklion Crete (Greece); Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, GR-71110 Heraklion Crete (Greece); Bitsanis, Ioannis A. [Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, GR-71110 Heraklion Crete (Greece)

    2014-05-28T23:59:59.000Z

    Monte Carlo simulations are performed on a simple cubic lattice to investigate the behavior of a single linear multiblock copolymer chain of various lengths N. The chain of type (A{sub n}B{sub n}){sub m} consists of alternating A and B blocks, where A are solvophilic and B are solvophobic and N = 2nm. The conformations are classified in five cases of globule formation by the solvophobic blocks of the chain. The dependence of globule characteristics on the molecular weight and on the number of blocks, which participate in their formation, is examined. The focus is on relative high molecular weight blocks (i.e., N in the range of 500–5000 units) and very differing energetic conditions for the two blocks (very good—almost athermal solvent for A and bad solvent for B). A rich phase behavior is observed as a result of the alternating architecture of the multiblock copolymer chain. We trust that thermodynamic equilibrium has been reached for chains of N up to 2000 units; however, for longer chains kinetic entrapments are observed. The comparison among equivalent globules consisting of different number of B-blocks shows that the more the solvophobic blocks constituting the globule the bigger its radius of gyration and the looser its structure. Comparisons between globules formed by the solvophobic blocks of the multiblock copolymer chain and their homopolymer analogs highlight the important role of the solvophilic A-blocks.

  4. Monte Carlo simulation of the data acquisition chain of scintillation detectors

    SciTech Connect (OSTI)

    Binda, F.; Ericsson, G.; Hellesen, C.; Hjalmarsson, A.; Eriksson, J.; Skiba, M.; Conroy, S.; Weiszflog, M. [Uppsala University, Department of Physics and Astronomy, Division of Applied Nuclear Physics, 75120 Uppsala (Sweden)

    2014-08-21T23:59:59.000Z

    The good performance of a detector can be strongly affected by the instrumentation used to acquire the data. The possibility of anticipating how the acquisition chain will affect the signal can help in finding the best solution among different set-ups. In this work we developed a Monte Carlo code that aims to simulate the effect of the various components of a digital Data Acquisition system (DAQ) applied to scintillation detectors. The components included in the model are: the scintillator, the photomultiplier tube (PMT), the signal cable and the digitizer. We benchmarked the code against real data acquired with a NE213 scintillator, comparing simulated and real signal pulses induced by gamma-ray interaction. Then we studied the dependence of the energy resolution of a pulse height spectrum (PHS) on the sampling frequency and the bit resolution of the digitizer. We found that exceeding some values of the sampling frequency and the bit resolution improves only marginally the performance of the system. The method can be applied for the study of various detector systems relevant for nuclear techniques, such as in fusion diagnostics.

  5. Thermodynamics and quark susceptibilities: a Monte-Carlo approach to the PNJL model

    E-Print Network [OSTI]

    M. Cristoforetti; T. Hell; B. Klein; W. Weise

    2010-02-11T23:59:59.000Z

    The Monte-Carlo method is applied to the Polyakov-loop extended Nambu--Jona-Lasinio (PNJL) model. This leads beyond the saddle-point approximation in a mean-field calculation and introduces fluctuations around the mean fields. We study the impact of fluctuations on the thermodynamics of the model, both in the case of pure gauge theory and including two quark flavors. In the two-flavor case, we calculate the second-order Taylor expansion coefficients of the thermodynamic grand canonical partition function with respect to the quark chemical potential and present a comparison with extrapolations from lattice QCD. We show that the introduction of fluctuations produces only small changes in the behavior of the order parameters for chiral symmetry restoration and the deconfinement transition. On the other hand, we find that fluctuations are necessary in order to reproduce lattice data for the flavor non-diagonal quark susceptibilities. Of particular importance are pion fields, the contribution of which is strictly zero in the saddle point approximation.

  6. Monte Carlo and Analytical Calculation of Lateral Deflection of Proton Beams in Homogeneous Targets

    SciTech Connect (OSTI)

    Pazianotto, Mauricio T.; Inocente, Guilherme F.; Silva, Danilo Anacleto A. d; Hormaza, Joel M. [Departamento de Fisica e Biofisica-Instituto de Biociencias, Universidade Estadual Paulista 'Julio de Mesquita Filho'-Botucatu-SP, Brasil and Distrito de Rubiao Junior s/no 18608-000 Botucatu, SP (Brazil)

    2010-05-21T23:59:59.000Z

    Proton radiation therapy is a precise form of radiation therapy, but the avoidance of damage to critical normal tissues and the prevention of geographical tumor misses require accurate knowledge of the dose delivered to the patient and the verification of his position demand a precise imaging technique. In proton therapy facilities, the X-ray Computed Tomography (xCT) is the preferred technique for the planning treatment of patients. This situation has been changing nowadays with the development of proton accelerators for health care and the increase in the number of treated patients. In fact, protons could be more efficient than xCT for this task. One essential difficulty in pCT image reconstruction systems came from the scattering of the protons inside the target due to the numerous small-angle deflections by nuclear Coulomb fields. The purpose of this study is the comparison of an analytical formulation for the determination of beam lateral deflection, based on Moliere's theory and Rutherford scattering with Monte Carlo calculations by SRIM 2008 and MCNPX codes.

  7. Feasibility Study of Neutron Dose for Real Time Image Guided Proton Therapy: A Monte Carlo Study

    E-Print Network [OSTI]

    Kim, Jin Sung; Kim, Daehyun; Shin, EunHyuk; Chung, Kwangzoo; Cho, Sungkoo; Ahn, Sung Hwan; Ju, Sanggyu; Chung, Yoonsun; Jung, Sang Hoon; Han, Youngyih

    2015-01-01T23:59:59.000Z

    Two full rotating gantry with different nozzles (Multipurpose nozzle with MLC, Scanning Dedicated nozzle) with conventional cyclotron system is installed and under commissioning for various proton treatment options at Samsung Medical Center in Korea. The purpose of this study is to investigate neutron dose equivalent per therapeutic dose, H/D, to x-ray imaging equipment under various treatment conditions with monte carlo simulation. At first, we investigated H/D with the various modifications of the beam line devices (Scattering, Scanning, Multi-leaf collimator, Aperture, Compensator) at isocenter, 20, 40, 60 cm distance from isocenter and compared with other research groups. Next, we investigated the neutron dose at x-ray equipments used for real time imaging with various treatment conditions. Our investigation showed the 0.07 ~ 0.19 mSv/Gy at x-ray imaging equipments according to various treatment options and intestingly 50% neutron dose reduction effect of flat panel detector was observed due to multi- lea...

  8. Generating relevant kinetic Monte Carlo catalogs using temperature accelerated dynamics with control over the accuracy

    SciTech Connect (OSTI)

    Chatterjee, Abhijit [Los Alamos National Laboratory; Voter, Arthur [Los Alamos National Laboratory

    2009-01-01T23:59:59.000Z

    We develop a variation of the temperature accelerated dynamics (TAD) method, called the p-TAD method, that efficiently generates an on-the-fly kinetic Monte Carlo (KMC) process catalog with control over the accuracy of the catalog. It is assumed that transition state theory is valid. The p-TAD method guarantees that processes relevant at the timescales of interest to the simulation are present in the catalog with a chosen confidence. A confidence measure associated with the process catalog is derived. The dynamics is then studied using the process catalog with the KMC method. Effective accuracy of a p-TAD calculation is derived when a KMC catalog is reused for conditions different from those the catalog was originally generated for. Different KMC catalog generation strategies that exploit the features of the p-TAD method and ensure higher accuracy and/or computational efficiency are presented. The accuracy and the computational requirements of the p-TAD method are assessed. Comparisons to the original TAD method are made. As an example, we study dynamics in sub-monolayer Ag/Cu(110) at the time scale of seconds using the p-TAD method. It is demonstrated that the p-TAD method overcomes several challenges plaguing the conventional KMC method.

  9. RESPONSE FUNCTION OF THE BGO AND NAI(T1) DETECTORS USING MONTE CARLO SIMULATIONS.

    SciTech Connect (OSTI)

    Orion, I.; Wielopolski, L.

    2001-01-31T23:59:59.000Z

    The high efficiency of the BGO detectors makes them very attractive candidates to replace NaI(T1) detectors, which are widely used in studies of body composition. In this work, the response functions of the BGO and NaI(T1) detectors were determined at 0.662,4.4, and 10.0 MeV using three different Monte Carlo codes: EGS4, MCNP, and PHOTON. These codes differ in their input files and transport calculations, and were used to verify the internal consistency of the setup and of the input data. The energy range of 0.662 to 10 MeV was chosen to cover energies of interest in body composition-studies. The superior efficiency of the BGO-detectors has to be weighed-against their inferior resolution, and their higher price than that of the NaI detectors. Because the price of the BGO detectors strongly depends on the size of the crystal, its optimization is an important component in the design of the entire system.

  10. Full-dispersion Monte Carlo simulation of phonon transport in micron-sized graphene nanoribbons

    SciTech Connect (OSTI)

    Mei, S., E-mail: smei4@wisc.edu; Knezevic, I., E-mail: knezevic@engr.wisc.edu [Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Maurer, L. N. [Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Aksamija, Z. [Department of Electrical and Computer Engineering, University of Massachusetts-Amherst, Amherst, Massachusetts 01003 (United States)

    2014-10-28T23:59:59.000Z

    We simulate phonon transport in suspended graphene nanoribbons (GNRs) with real-space edges and experimentally relevant widths and lengths (from submicron to hundreds of microns). The full-dispersion phonon Monte Carlo simulation technique, which we describe in detail, involves a stochastic solution to the phonon Boltzmann transport equation with the relevant scattering mechanisms (edge, three-phonon, isotope, and grain boundary scattering) while accounting for the dispersion of all three acoustic phonon branches, calculated from the fourth-nearest-neighbor dynamical matrix. We accurately reproduce the results of several experimental measurements on pure and isotopically modified samples [S. Chen et al., ACS Nano 5, 321 (2011);S. Chen et al., Nature Mater. 11, 203 (2012); X. Xu et al., Nat. Commun. 5, 3689 (2014)]. We capture the ballistic-to-diffusive crossover in wide GNRs: room-temperature thermal conductivity increases with increasing length up to roughly 100??m, where it saturates at a value of 5800?W/m K. This finding indicates that most experiments are carried out in the quasiballistic rather than the diffusive regime, and we calculate the diffusive upper-limit thermal conductivities up to 600?K. Furthermore, we demonstrate that calculations with isotropic dispersions overestimate the GNR thermal conductivity. Zigzag GNRs have higher thermal conductivity than same-size armchair GNRs, in agreement with atomistic calculations.

  11. A high-fidelity Monte Carlo evaluation of CANDU-6 safety parameters

    SciTech Connect (OSTI)

    Kim, Y.; Hartanto, D. [Korea Advanced Inst. of Science and Technology KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701 (Korea, Republic of)

    2012-07-01T23:59:59.000Z

    Important safety parameters such as the fuel temperature coefficient (FTC) and the power coefficient of reactivity (PCR) of the CANDU-6 (CANada Deuterium Uranium) reactor have been evaluated by using a modified MCNPX code. For accurate analysis of the parameters, the DBRC (Doppler Broadening Rejection Correction) scheme was implemented in MCNPX in order to account for the thermal motion of the heavy uranium nucleus in the neutron-U scattering reactions. In this work, a standard fuel lattice has been modeled and the fuel is depleted by using the MCNPX and the FTC value is evaluated for several burnup points including the mid-burnup representing a near-equilibrium core. The Doppler effect has been evaluated by using several cross section libraries such as ENDF/B-VI, ENDF/B-VII, JEFF, JENDLE. The PCR value is also evaluated at mid-burnup conditions to characterize safety features of equilibrium CANDU-6 reactor. To improve the reliability of the Monte Carlo calculations, huge number of neutron histories are considered in this work and the standard deviation of the k-inf values is only 0.5{approx}1 pcm. It has been found that the FTC is significantly enhanced by accounting for the Doppler broadening of scattering resonance and the PCR are clearly improved. (authors)

  12. Noncovalent Interactions by Quantum Monte Carlo: A Speedup by a Smart Basis Set Reduction

    E-Print Network [OSTI]

    Dubecký, Matúš

    2015-01-01T23:59:59.000Z

    A fixed-node diffusion Monte Carlo (FN-DMC) method provides a promising alternative to the commonly used coupled-cluster (CC) methods, in the domain of benchmark noncovalent interaction energy calculations. This is mainly true for a low-order polynomial CPU cost scaling of FN-DMC and favorable FN error cancellation leading to benchmark interaction energies accurate to 0.1 kcal/mol. While it is empirically accepted that the FN-DMC results depend weakly on the one-particle basis sets used to expand the guiding functions, limits of this assumption remain elusive. Our recent work indicates that augmented triple zeta basis sets are sufficient to achieve a benchmark level of 0.1 kcal/mol. Here we report on a possibility of significant truncation of the one-particle basis sets without any visible bias on the overall accuracy of the final FN-DMC energy differences. The approach is tested on a set of seven small noncovalent closed-shell complexes including a water dimer. The reported findings enable cheaper high-quali...

  13. Introduction to Computational Physics and Monte Carlo Simulations of Matrix Field Theory

    E-Print Network [OSTI]

    Badis Ydri

    2015-06-05T23:59:59.000Z

    This book is divided into two parts. In the first part we give an elementary introduction to computational physics consisting of 21 simulations which originated from a formal course of lectures and laboratory simulations delivered since 2010 to physics students at Annaba University. The second part is much more advanced and deals with the problem of how to set up working Monte Carlo simulations of matrix field theories which involve finite dimensional matrix regularizations of noncommutative and fuzzy field theories, fuzzy spaces and matrix geometry. The study of matrix field theory in its own right has also become very important to the proper understanding of all noncommutative, fuzzy and matrix phenomena. The second part, which consists of 9 simulations, was delivered informally to doctoral students who are working on various problems in matrix field theory. Sample codes as well as sample key solutions are also provided for convenience and completness. An appendix containing an executive arabic summary of the first part is added at the end of the book.

  14. Ferroelectric domain formation in discotic liquid crystals : Monte Carlo study on the influence of boundary conditions

    E-Print Network [OSTI]

    Tushar Kanti Bose; Jayashree Saha

    2015-03-06T23:59:59.000Z

    The realization of a spontaneous macroscopic ferroelectric order in fluids of anisotropic mesogens is a topic of both fundamental and technological interest. Recently, we demonstrated that a system of dipolar achiral disklike ellipsoids can exhibit long-searched ferroelectric liquid crystalline phases of dipolar origin. In the present work, extensive off-lattice Monte Carlo simulations are used to investigate the phase behavior of the system under the influences of the electrostatic boundary conditions that restrict any global polarization. We find that the system develops strongly ferroelectric slablike domains periodically arranged in an antiferroelectric fashion. Exploring the phase behavior at different dipole strengths, we find existence of the ferroelectric nematic and ferroelectric columnar order inside the domains. For higher dipole strengths, a biaxial phase is also obtained with a similar periodic array of ferroelectric slabs of antiparallel polarizations. We have studied the depolarizing effects by using both the Ewald summation and the spherical cut-off techniques. We present and compare the results of the two different approaches of considering the depolarizing effects in this anisotropic system. It is explicitly shown that the domain size increases with the system size as a result of considering longer range of dipolar interactions. The system exhibits pronounced system size effects for stronger dipolar interactions. The results provide strong evidence to the novel understanding that the dipolar interactions are indeed sufficient to produce long range ferroelectric order in anisotropic fluids.

  15. Reconstruction for proton computed tomography by tracing proton trajectories: A Monte Carlo study

    SciTech Connect (OSTI)

    Li Tianfang; Liang Zhengrong; Singanallur, Jayalakshmi V.; Satogata, Todd J.; Williams, David C.; Schulte, Reinhard W. [Departments of Radiology, Computer Science, and Physics and Astronomy, State University of New York at Stony Brook, Stony Brook, New York 11794 (United States); Department of Physics, Brookhaven National Laboratory, Upton, New York 11973 (United States); Santa Cruz Institute for Particle Physics, University of California at Santa Cruz, Santa Cruz, California 95064 (United States); Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California 92354 (United States)

    2006-03-15T23:59:59.000Z

    Proton computed tomography (pCT) has been explored in the past decades because of its unique imaging characteristics, low radiation dose, and its possible use for treatment planning and on-line target localization in proton therapy. However, reconstruction of pCT images is challenging because the proton path within the object to be imaged is statistically affected by multiple Coulomb scattering. In this paper, we employ GEANT4-based Monte Carlo simulations of the two-dimensional pCT reconstruction of an elliptical phantom to investigate the possible use of the algebraic reconstruction technique (ART) with three different path-estimation methods for pCT reconstruction. The first method assumes a straight-line path (SLP) connecting the proton entry and exit positions, the second method adapts the most-likely path (MLP) theoretically determined for a uniform medium, and the third method employs a cubic spline path (CSP). The ART reconstructions showed progressive improvement of spatial resolution when going from the SLP [2 line pairs (lp) cm{sup -1}] to the curved CSP and MLP path estimates (5 lp cm{sup -1}). The MLP-based ART algorithm had the fastest convergence and smallest residual error of all three estimates. This work demonstrates the advantage of tracking curved proton paths in conjunction with the ART algorithm and curved path estimates.

  16. Evaluation of a new commercial Monte Carlo dose calculation algorithm for electron beams

    SciTech Connect (OSTI)

    Vandervoort, Eric J., E-mail: evandervoort@toh.on.ca; Cygler, Joanna E. [Department of Medical Physics, The Ottawa Hospital Cancer Centre, The University of Ottawa, Ottawa, Ontario K1H 8L6 (Canada) [Department of Medical Physics, The Ottawa Hospital Cancer Centre, The University of Ottawa, Ottawa, Ontario K1H 8L6 (Canada); The Faculty of Medicine, The University of Ottawa, Ottawa, Ontario K1H 8M5 (Canada); Department of Physics, Carleton University, Ottawa, Ontario K1S 5B6 (Canada); Tchistiakova, Ekaterina [Department of Medical Physics, The Ottawa Hospital Cancer Centre, The University of Ottawa, Ottawa, Ontario K1H 8L6 (Canada) [Department of Medical Physics, The Ottawa Hospital Cancer Centre, The University of Ottawa, Ottawa, Ontario K1H 8L6 (Canada); Department of Medical Biophysics, University of Toronto, Ontario M5G 2M9 (Canada); Heart and Stroke Foundation Centre for Stroke Recovery, Sunnybrook Research Institute, University of Toronto, Ontario M4N 3M5 (Canada); La Russa, Daniel J. [Department of Medical Physics, The Ottawa Hospital Cancer Centre, The University of Ottawa, Ottawa, Ontario K1H 8L6 (Canada) and The Faculty of Medicine, The University of Ottawa, Ottawa, Ontario K1H 8M5 (Canada)] [Department of Medical Physics, The Ottawa Hospital Cancer Centre, The University of Ottawa, Ottawa, Ontario K1H 8L6 (Canada) and The Faculty of Medicine, The University of Ottawa, Ottawa, Ontario K1H 8M5 (Canada)

    2014-02-15T23:59:59.000Z

    Purpose: In this report the authors present the validation of a Monte Carlo dose calculation algorithm (XiO EMC from Elekta Software) for electron beams. Methods: Calculated and measured dose distributions were compared for homogeneous water phantoms and for a 3D heterogeneous phantom meant to approximate the geometry of a trachea and spine. Comparisons of measurements and calculated data were performed using 2D and 3D gamma index dose comparison metrics. Results: Measured outputs agree with calculated values within estimated uncertainties for standard and extended SSDs for open applicators, and for cutouts, with the exception of the 17 MeV electron beam at extended SSD for cutout sizes smaller than 5 × 5 cm{sup 2}. Good agreement was obtained between calculated and experimental depth dose curves and dose profiles (minimum number of measurements that pass a 2%/2 mm agreement 2D gamma index criteria for any applicator or energy was 97%). Dose calculations in a heterogeneous phantom agree with radiochromic film measurements (>98% of pixels pass a 3 dimensional 3%/2 mm ?-criteria) provided that the steep dose gradient in the depth direction is considered. Conclusions: Clinically acceptable agreement (at the 2%/2 mm level) between the measurements and calculated data for measurements in water are obtained for this dose calculation algorithm. Radiochromic film is a useful tool to evaluate the accuracy of electron MC treatment planning systems in heterogeneous media.

  17. Lattice Monte Carlo calculations for unitary fermions in a harmonic trap

    E-Print Network [OSTI]

    Michael G. Endres; David B. Kaplan; Jong-Wan Lee; Amy N. Nicholson

    2011-11-03T23:59:59.000Z

    We present a new lattice Monte Carlo approach developed for studying large numbers of strongly interacting nonrelativistic fermions, and apply it to a dilute gas of unitary fermions confined to a harmonic trap. Our lattice action is highly improved, with sources of discretization and finite volume errors systematically removed; we are able to demonstrate the expected volume scaling of energy levels of two and three untrapped fermions, and to reproduce the high precision calculations published previously for the ground state energies for N = 3 unitary fermions in a box (to within our 0.3% uncertainty), and for N = 3, . . ., 6 unitary fermions in a harmonic trap (to within our ~ 1% uncertainty). We use this action to determine the ground state energies of up to 70 unpolarized fermions trapped in a harmonic potential on a lattice as large as 64^3 x 72; our approach avoids the use of importance sampling or calculation of a fermion determinant and employs a novel statistical method for estimating observables, allowing us to generate ensembles as large as 10^8 while requiring only relatively modest computational resources.

  18. Investigating the rotational evolution of young, low mass stars using Monte Carlo simulations

    E-Print Network [OSTI]

    Vasconcelos, M J

    2015-01-01T23:59:59.000Z

    We investigate the rotational evolution of young stars through Monte Carlo simulations. We simulate 280,000 stars, each of which is assigned a mass, a rotational period, and a mass accretion rate. The mass accretion rate depends on mass and time, following power-laws indices 1.4 and -1.5, respectively. A mass-dependent accretion threshold is defined below which a star is considered as diskless, which results in a distribution of disk lifetimes that matches observations. Stars are evolved at constant angular spin rate while accreting and at constant angular momentum when they become diskless. We recover the bimodal period distribution seen in several young clusters. The short period peak consists mostly of diskless stars and the long period one is mainly populated by accreting stars. Both distributions present a long tail towards long periods and a population of slowly rotating diskless stars is observed at all ages. We reproduce the observed correlations between disk fraction and spin rate, as well as between...

  19. A Monte Carlo Analysis of Gas Centrifuge Enrichment Plant Process Load Cell Data

    SciTech Connect (OSTI)

    Garner, James R [ORNL; Whitaker, J Michael [ORNL

    2013-01-01T23:59:59.000Z

    As uranium enrichment plants increase in number, capacity, and types of separative technology deployed (e.g., gas centrifuge, laser, etc.), more automated safeguards measures are needed to enable the IAEA to maintain safeguards effectiveness in a fiscally constrained environment. Monitoring load cell data can significantly increase the IAEA s ability to efficiently achieve the fundamental safeguards objective of confirming operations as declared (i.e., no undeclared activities), but care must be taken to fully protect the operator s proprietary and classified information related to operations. Staff at ORNL, LANL, JRC/ISPRA, and University of Glasgow are investigating monitoring the process load cells at feed and withdrawal (F/W) stations to improve international safeguards at enrichment plants. A key question that must be resolved is what is the necessary frequency of recording data from the process F/W stations? Several studies have analyzed data collected at a fixed frequency. This paper contributes to load cell process monitoring research by presenting an analysis of Monte Carlo simulations to determine the expected errors caused by low frequency sampling and its impact on material balance calculations.

  20. A Monte Carlo approach to modeling lost person behavior in wilderness areas using a geographic information system

    E-Print Network [OSTI]

    Erickson, Lori

    1995-01-01T23:59:59.000Z

    's application of Monte Carlo simulation methods to the spread of geographic phenomena, more specifically, the spread of innovations or ideas from person to person (Pitts 1965; Chorley and Haggett 1967; Marble and Bowlby 1968; Gould 1969; Cliff et al. 1981... are responsible for the safety of these park users, are concerned about several important factors. These include unusually high temperatures, lack of potable water, and other desert hazards such as steep ridges and cliffs, spiny plants, and poisonous animals...

  1. The two-phase issue in the O(n) non-linear $?$-model: A Monte Carlo study

    E-Print Network [OSTI]

    B. Alles; A. Buonanno; G. Cella

    1996-08-01T23:59:59.000Z

    We have performed a high statistics Monte Carlo simulation to investigate whether the two-dimensional O(n) non-linear sigma models are asymptotically free or they show a Kosterlitz- Thouless-like phase transition. We have calculated the mass gap and the magnetic susceptibility in the O(8) model with standard action and the O(3) model with Symanzik action. Our results for O(8) support the asymptotic freedom scenario.

  2. Experimental validation and evaluation of uncertainty in the monte carlo modeling of electron irradiation of complex objects

    E-Print Network [OSTI]

    Tutt, Teresa Elizabeth

    2009-05-15T23:59:59.000Z

    MEDIA?????????? 123 APPENDIX B: REPEATABLE GEOMETRY FOR TARGET IRRADIATION????????????????????. 128 APPENDIX C: VARIATION OF MONTE-CARLO PARAMETERS FOR 5.5 MM PHANTOM????????????????. 131 VITA???????????????????????????????? 137 ix LIST... errors in simple structure??... 10 2.5 Two dimensional illustration of coarse element errors in cilantro leaf????. 10 2.6 Coarse element error produced by averaging the densities in voxel?????. 11 2.7 Electron step-size artifact for 20 mm cylinder...

  3. The effect of fear on gregariousness and exploration in rats

    E-Print Network [OSTI]

    Anderson, Bergie Wayne

    1973-01-01T23:59:59.000Z

    ' "ms of the behavior occurring in the open field. Rats display three major behaviors in the open field; these are fear, exploration, and gregariousness. Research has shown that when a pMr of rats are placed into an open field, they display signs... them. The two variables were found to be positively correlated and significant at the 0. 05 level of con- fidence (r = . 16; df = 230). The analysis of variance of the combined fear scores, indicated a significant difference. between methods (F = 4...

  4. Theoretical study of the ammonia nitridation rate on an Fe (100) surface: A combined density functional theory and kinetic Monte Carlo study

    E-Print Network [OSTI]

    Yeo, Sang Chul

    Ammonia (NH[subscript 3]) nitridation on an Fe surface was studied by combining density functional theory (DFT) and kinetic Monte Carlo (kMC) calculations. A DFT calculation was performed to obtain the energy barriers ...

  5. Formation of Y[subscript 2]O[subscript 3] nanoclusters in nanostructured ferritic alloys during isothermal and anisothermal heat treatment: A kinetic Monte Carlo study

    E-Print Network [OSTI]

    Hin, Celine Nathalie

    Kinetic Monte Carlo simulations, based on parameters obtained with density-functional theory in the local-density approximation and experimental data, are used to study bulk precipitation of Y[subscript 2]O[subscript 3] ...

  6. A deviational Monte Carlo formulation of ab initio phonon transport and its application to the study of kinetic effects in graphene ribbons

    E-Print Network [OSTI]

    Landon, Colin Donald

    2014-01-01T23:59:59.000Z

    We present a deviational Monte Carlo method for solving the Boltzmann equation for phonon transport subject to the linearized ab initio 3-phonon scattering operator. Phonon dispersion relations and transition rates are ...

  7. Quantum Monte Carlo calculations of electronic excitation energies: the case of the singlet $n \\to \\pi^*$ (CO) transition in acrolein

    E-Print Network [OSTI]

    Toulouse, Julien; Reinhardt, Peter; Hoggan, Philip E; Umrigar, C J

    2010-01-01T23:59:59.000Z

    We report state-of-the-art quantum Monte Carlo calculations of the singlet $n \\to \\pi^*$ (CO) vertical excitation energy in the acrolein molecule, extending the recent study of Bouab\\c{c}a {\\it et al.} [J. Chem. Phys. {\\bf 130}, 114107 (2009)]. We investigate the effect of using a Slater basis set instead of a Gaussian basis set, and of using state-average versus state-specific complete-active-space (CAS) wave functions, with or without reoptimization of the coefficients of the configuration state functions (CSFs) and of the orbitals in variational Monte Carlo (VMC). It is found that, with the Slater basis set used here, both state-average and state-specific CAS(6,5) wave functions give an accurate excitation energy in diffusion Monte Carlo (DMC), with or without reoptimization of the CSF and orbital coefficients in the presence of the Jastrow factor. In contrast, the CAS(2,2) wave functions require reoptimization of the CSF and orbital coefficients to give a good DMC excitation energy. Our best estimates of ...

  8. Monte Carlo calculations and experimental measurements of dosimetric parameters of the IRA-{sup 103}Pd brachytherapy source

    SciTech Connect (OSTI)

    Sadeghi, Mahdi; Raisali, Gholamreza; Hosseini, S. Hamed; Shavar, Arzhang [Nuclear Medicine Research Group, Agricultural, Medical and Industrial Research School, P.O. Box 31485-498, Karaj (Iran, Islamic Republic of) and Engineering Faculty, Science and Research Campus, Islamic Azad University, P.O. Box 14515-775, Tehran (Iran, Islamic Republic of); Radiation Applications Research School, Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of); Engineering Faculty, Science and Research Campus, Islamic Azad University, P.O. Box 14515-775, Tehran (Iran, Islamic Republic of); SSDL Group, Agricultural, Medical and Industrial Research School, Karaj (Iran, Islamic Republic of)

    2008-04-15T23:59:59.000Z

    This article presents a brachytherapy source having {sup 103}Pd adsorbed onto a cylindrical silver rod that has been developed by the Agricultural, Medical, and Industrial Research School for permanent implant applications. Dosimetric characteristics (radial dose function, anisotropy function, and anisotropy factor) of this source were experimentally and theoretically determined in terms of the updated AAPM Task group 43 (TG-43U1) recommendations. Monte Carlo simulations were used to calculate the dose rate constant. Measurements were performed using TLD-GR200A circular chip dosimeters using standard methods employing thermoluminescent dosimeters in a Perspex phantom. Precision machined bores in the phantom located the dosimeters and the source in a reproducible fixed geometry, providing for transverse-axis and angular dose profiles over a range of distances from 0.5 to 5 cm. The Monte Carlo N-particle (MCNP) code, version 4C simulation techniques have been used to evaluate the dose-rate distributions around this model {sup 103}Pd source in water and Perspex phantoms. The Monte Carlo calculated dose rate constant of the IRA-{sup 103}Pd source in water was found to be 0.678 cGy h{sup -1} U{sup -1} with an approximate uncertainty of {+-}0.1%. The anisotropy function, F(r,{theta}), and the radial dose function, g(r), of the IRA-{sup 103}Pd source were also measured in a Perspex phantom and calculated in both Perspex and liquid water phantoms.

  9. Monte Carlo modelling of a-Si EPID response: The effect of spectral variations with field size and position

    SciTech Connect (OSTI)

    Parent, Laure; Seco, Joao; Evans, Phil M.; Fielding, Andrew; Dance, David R. [Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Downs Road, Sutton, SM2 5PT (United Kingdom); School of Physical and Chemical Sciences, Queensland University of Technology, Q337 Gardens Point Campus, Brisbane, Queensland 4001 (Australia); Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Fulham Road, London, SW3 6JJ (United Kingdom)

    2006-12-15T23:59:59.000Z

    This study focused on predicting the electronic portal imaging device (EPID) image of intensity modulated radiation treatment (IMRT) fields in the absence of attenuation material in the beam with Monte Carlo methods. As IMRT treatments consist of a series of segments of various sizes that are not always delivered on the central axis, large spectral variations may be observed between the segments. The effect of these spectral variations on the EPID response was studied with fields of various sizes and off-axis positions. A detailed description of the EPID was implemented in a Monte Carlo model. The EPID model was validated by comparing the EPID output factors for field sizes between 1x1 and 26x26 cm{sup 2} at the isocenter. The Monte Carlo simulations agreed with the measurements to within 1.5%. The Monte Carlo model succeeded in predicting the EPID response at the center of the fields of various sizes and offsets to within 1% of the measurements. Large variations (up to 29%) of the EPID response were observed between the various offsets. The EPID response increased with field size and with field offset for most cases. The Monte Carlo model was then used to predict the image of a simple test IMRT field delivered on the beam axis and with an offset. A variation of EPID response up to 28% was found between the on- and off-axis delivery. Finally, two clinical IMRT fields were simulated and compared to the measurements. For all IMRT fields, simulations and measurements agreed within 3%--0.2 cm for 98% of the pixels. The spectral variations were quantified by extracting from the spectra at the center of the fields the total photon yield (Y{sub total}), the photon yield below 1 MeV (Y{sub low}), and the percentage of photons below 1 MeV (P{sub low}). For the studied cases, a correlation was shown between the EPID response variation and Y{sub total}, Y{sub low}, and P{sub low}.

  10. The laboratory rat strains most commonly used in research are believed to be domesticated albino strains of the Norway rat rattus nirvegicus. Rats like mice, belong to the order Rodentia

    E-Print Network [OSTI]

    Shihadeh, Alan

    and the nude rat. Uses Despite the fear that rats invoke in people they actually make quiet, gentle pets rate 70-115 Food consumption 5-6g/100g/d Water consumption 10-12ml/100g/d Breeding onset Male 65-110d

  11. Forward treatment planning for modulated electron radiotherapy (MERT) employing Monte Carlo methods

    SciTech Connect (OSTI)

    Henzen, D., E-mail: henzen@ams.unibe.ch; Manser, P.; Frei, D.; Volken, W.; Born, E. J.; Lössl, K.; Aebersold, D. M.; Fix, M. K. [Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010 Berne (Switzerland)] [Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, CH-3010 Berne (Switzerland); Neuenschwander, H. [Clinic for Radiation-Oncology, Lindenhofspital Bern, CH-3012 Berne (Switzerland)] [Clinic for Radiation-Oncology, Lindenhofspital Bern, CH-3012 Berne (Switzerland); Stampanoni, M. F. M. [Institute for Biomedical Engineering, ETH Zürich and Paul Scherrer Institut, CH-5234 Villigen (Switzerland)] [Institute for Biomedical Engineering, ETH Zürich and Paul Scherrer Institut, CH-5234 Villigen (Switzerland)

    2014-03-15T23:59:59.000Z

    Purpose: This paper describes the development of a forward planning process for modulated electron radiotherapy (MERT). The approach is based on a previously developed electron beam model used to calculate dose distributions of electron beams shaped by a photon multi leaf collimator (pMLC). Methods: As the electron beam model has already been implemented into the Swiss Monte Carlo Plan environment, the Eclipse treatment planning system (Varian Medical Systems, Palo Alto, CA) can be included in the planning process for MERT. In a first step, CT data are imported into Eclipse and a pMLC shaped electron beam is set up. This initial electron beam is then divided into segments, with the electron energy in each segment chosen according to the distal depth of the planning target volume (PTV) in beam direction. In order to improve the homogeneity of the dose distribution in the PTV, a feathering process (Gaussian edge feathering) is launched, which results in a number of feathered segments. For each of these segments a dose calculation is performed employing the in-house developed electron beam model along with the macro Monte Carlo dose calculation algorithm. Finally, an automated weight optimization of all segments is carried out and the total dose distribution is read back into Eclipse for display and evaluation. One academic and two clinical situations are investigated for possible benefits of MERT treatment compared to standard treatments performed in our clinics and treatment with a bolus electron conformal (BolusECT) method. Results: The MERT treatment plan of the academic case was superior to the standard single segment electron treatment plan in terms of organs at risk (OAR) sparing. Further, a comparison between an unfeathered and a feathered MERT plan showed better PTV coverage and homogeneity for the feathered plan, with V{sub 95%} increased from 90% to 96% and V{sub 107%} decreased from 8% to nearly 0%. For a clinical breast boost irradiation, the MERT plan led to a similar homogeneity in the PTV compared to the standard treatment plan while the mean body dose was lower for the MERT plan. Regarding the second clinical case, a whole breast treatment, MERT resulted in a reduction of the lung volume receiving more than 45% of the prescribed dose when compared to the standard plan. On the other hand, the MERT plan leads to a larger low-dose lung volume and a degraded dose homogeneity in the PTV. For the clinical cases evaluated in this work, treatment plans using the BolusECT technique resulted in a more homogenous PTV and CTV coverage but higher doses to the OARs than the MERT plans. Conclusions: MERT treatments were successfully planned for phantom and clinical cases, applying a newly developed intuitive and efficient forward planning strategy that employs a MC based electron beam model for pMLC shaped electron beams. It is shown that MERT can lead to a dose reduction in OARs compared to other methods. The process of feathering MERT segments results in an improvement of the dose homogeneity in the PTV.

  12. Original article Digestion and fermentation of proteins in rats fed

    E-Print Network [OSTI]

    Boyer, Edmond

    Original article Digestion and fermentation of proteins in rats fed keratin, albumin, cooked casein the hypothesis that cooking reduces the digestibility of casein, and increases the yield of bacterial me transfer and fermentation in the caecum. The caecal digestion of casein (cooked or not), ker- atin

  13. Facial Wiping in the Rat Fetus: Variation of Chemosensory

    E-Print Network [OSTI]

    Robinson, Scott R.

    how variation in stimulus parameters of lemon odor infusion (concentration, volume, and infusion time) affected the wiping response of E20 rat fetuses. Infusions of higher concentration or greater volume of stimulation. Intraoral infusion of chemosensory fluids with strong olfactory components, such as lemon extract

  14. Aardvark hunt in Kenya Gaten B. Rat}rUin

    E-Print Network [OSTI]

    I I i Aardvark hunt in Kenya Gaten B. Rat}rUin Dept of Omittrologr & Mamrnalogr, Catifomia Academy eactrirg science as a Peace Corps Volunteer at Mirogi $conOary Scnou in Sou*r Nyanza District or Kenya of Kenya in Nairobi. 14 #12;

  15. Effects of Methanol on the Retinal Function of Juvenile Rats

    E-Print Network [OSTI]

    Casanova, Christian

    Effects of Methanol on the Retinal Function of Juvenile Rats C. Plaziac1 , P. Lachapelle2 , C Received 18 April 2002; accepted 22 July 2002 Abstract We have investigated the effect of methanol exposure recorded prior to and up to 72 h after the administration of methanol. Data were compared to a control

  16. PROTECTIVE EFFECTS OF VERAPAMIL AGAINST HEXACHLOROBUTADIENE NEPHROTOXICITY IN RATS

    E-Print Network [OSTI]

    E. Moghtadai Khorasgani; K. Manochehri; M. Hosseini

    In order to evaluate the protective effect of verapamil against hexachlorobutadiene (HCBD) nephrotoxicity, 30 adult Wistar albino rats were divided into five equal groups, A, B, C, D and E and were given intra-peritonially corn oil (I ml/kg; control), HCBD (50 mg/kg), verapamil (50 µg/kg) with HCBD

  17. Inconclusive Experiment with Rats By Bill Menke, December 1, 2013

    E-Print Network [OSTI]

    Menke, William

    of genetically-modified corn. The Times article says: The editor of the journal, Food and Chemical Toxicology the paper's main result, that rats fed genetically-modified, herbicide-resistant corn have a higher incident was a bit disingenuous of him. I do find delicious the irony that Séralini's paper is critiquing genetically-modified

  18. Single Glucose Biofuel Cells Implanted in Rats Power Electronic Devices

    E-Print Network [OSTI]

    Boyer, Edmond

    Single Glucose Biofuel Cells Implanted in Rats Power Electronic Devices A. Zebda1,2 , S. Cosnier1 the first implanted glucose biofuel cell (GBFC) that is capable of generating sufficient power from a mammal further developments. Following recent developments in nano- and biotechnology, state-of-the-art biofuel

  19. Nitrogen sparing by 2-ketoisocaproate in parenterally fed rats

    SciTech Connect (OSTI)

    Yagi, M.; Matthews, D.E.; Walser, M. (Johns Hopkins Univ. School of Medicine, Baltimore, MD (USA))

    1990-11-01T23:59:59.000Z

    In rats receiving total parenteral nutrition with or without sodium 2-ketoisocaproate (KIC; 2.48 g.kg-1.day-1), L-(1-{sup 13}C)leucine and (1-{sup 14}C)KIC were constantly infused for 6 h. CO{sub 2} production, {sup 14}CO{sub 2} production, {sup 13}CO{sub 2} enrichment, urinary urea nitrogen (N) plus ammonia N and total urinary N were measured. Whole body protein synthesis (S) was calculated in non-KIC-infused rats and also in unfed rats infused with (1-{sup 14}C)leucine from fractional oxidation of labeled leucine (1-F), where F is fractional utilization for protein synthesis, and urea N plus ammonia N excretion (C) as S = C x F/(1-F). Addition of KIC caused a significant reduction in N excretion and a significant improvement in N balance. Fractional oxidation of labeled KIC increased, whereas fractional utilization of labeled KIC for protein synthesis decreased, but the extent of incorporation of infused KIC into newly synthesized protein (as leucine) amounted to at least 40% of the total rate of leucine incorporation into newly synthesized whole body protein. We conclude that addition of KIC spares N in parenterally fed rats and becomes a major source of leucine for protein synthesis.

  20. adult rat brain: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    rat brain First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 Thyroid hormone regulates hippocampal...