N. Vonta; G. A. Souliotis; M. Veselsky; A. Bonasera
2015-06-16T23:59:59.000Z
The microscopic description of nuclear fission still remains a topic of intense basic research. Un- derstanding nuclear fission, apart from a theoretical point of view, is of practical importance for energy production and the transmutation of nuclear waste. In nuclear astrophysics, fission sets the upper limit to the nucleosynthesis of heavy elements via the r-process. In this work we initiated a systematic study of intermediate energy proton-induced fission using the Constrained Molecu- lar Dynamics (CoMD) code. The CoMD code implements an effective interaction with a nuclear matter compressibility of K=200 (soft EOS) with several forms of the density dependence of the nucleon-nucleon symmetry potential. Moreover, a constraint is imposed in the phase-space occu- pation for each nucleon restoring the Pauli principle at each time step of the collision. A proper choice of the surface parameter of the effective interaction has been made to describe fission. In this work, we present results of fission calculations for proton-induced reactions on : a) 232 Th at 27 and 63 MeV, b) 235 U at 10, 30, 60 and 100 MeV, and c) 238 U at 100 and 660 MeV. The calculated observables include fission-fragment mass distributions, total fission energies, neutron multiplicities and fission times. These observables are compared to available experimental data. We show that the microscopic CoMD code is able to describe the complicated many-body dynamics of the fission process at intermediate and high energy and give a reasonable estimate of the fission time scale. Sensitivity of the results to the density dependence of the nucleon symmetry potential (and, thus, the nuclear symmetry energy) is found. Further improvements of the code are necessary to achieve a satisfactory description of low energy fission in which shell effects play a dominant role.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Chen, Sow-Hsin; Lagi, Marco; Chu, Xiang-qiang; Zhang, Yang; Kim, Chansoo; Faraone, Antonio; Fratini, Emiliano; Baglioni, Piero
2010-01-01T23:59:59.000Z
This review article describes our neutron scattering experiments made in the past four years for the understanding of the single-particle (hydrogen atom) dynamics of a protein and its hydration water and the strong coupling between them. We found that the key to this strong coupling is the existence of a fragile-to-strong dynamic crossover (FSC) phenomenon occurring at aroundTL= 225±5 K in the hydration water. On lowering of the temperature toward FSC, the structure of hydration water makes a transition from predominantly the high density form (HDL), a more fluid state, to predominantly the low density form (LDL), a less fluidmore »state, derived from the existence of a liquid–liquid critical point at an elevated pressure. We show experimentally that this sudden switch in the mobility of hydration water on Lysozyme, B-DNA and RNA triggers the dynamic transition, at a temperatureTD= 220 K, for these biopolymers. In the glassy state, belowTD, the biopolymers lose their vital conformational flexibility resulting in a substantial diminishing of their biological functions. We also performed molecular dynamics (MD) simulations on a realistic model of hydrated lysozyme powder, which confirms the existence of the FSC and the hydration level dependence of the FSC temperature. Furthermore, we show a striking feature in the short time relaxation (?-relaxation) of protein dynamics, which is the logarithmic decay spanning 3 decades (from ps to ns). The long time?-relaxation shows instead a diffusive behavior, which supports the liquid-like motions of protein constituents. We then discuss our recent high-resolution X-ray inelastic scattering studies of globular proteins, Lysozyme and Bovine Serum Albumin. We were able to measure the dispersion relations of collective, intra-protein phonon-like excitations in these proteins for the first time. We found that the phonon energies show a marked softening and at the same time their population increases substantially in a certain wave vector range when temperature crosses over theTD. Thus the increase of biological activities aboveTDhas positive correlation with activation of slower and large amplitude collective motions of a protein.« less
Fast plane wave density functional theory molecular dynamics calculations on multi-GPU machines
Jia, Weile, E-mail: jiawl@sccas.cn [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China) [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing (China); Fu, Jiyun, E-mail: fujy@sccas.cn [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China) [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing (China); Cao, Zongyan, E-mail: zycao@sccas.cn [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China)] [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China); Wang, Long, E-mail: wangl@sccas.cn [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China)] [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China); Chi, Xuebin, E-mail: chi@sccas.cn [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China)] [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China); Gao, Weiguo, E-mail: wggao@fudan.edu.cn [School of Mathematical Sciences, Fudan University, 220 Handan Road, Shanghai 200433 (China) [School of Mathematical Sciences, Fudan University, 220 Handan Road, Shanghai 200433 (China); MOE Key Laboratory of Computational Physical Sciences, Fudan University, Shanghai (China); Wang, Lin-Wang, E-mail: lwwang@lbl.gov [Material Science Division, Lawrence Berkeley National Laboratory, One Cyclotron Road Mail Stop 50F Berkeley, CA 94720 (United States)] [Material Science Division, Lawrence Berkeley National Laboratory, One Cyclotron Road Mail Stop 50F Berkeley, CA 94720 (United States)
2013-10-15T23:59:59.000Z
Plane wave pseudopotential (PWP) density functional theory (DFT) calculation is the most widely used method for material simulations, but its absolute speed stagnated due to the inability to use large scale CPU based computers. By a drastic redesign of the algorithm, and moving all the major computation parts into GPU, we have reached a speed of 12 s per molecular dynamics (MD) step for a 512 atom system using 256 GPU cards. This is about 20 times faster than the CPU version of the code regardless of the number of CPU cores used. Our tests and analysis on different GPU platforms and configurations shed lights on the optimal GPU deployments for PWP-DFT calculations. An 1800 step MD simulation is used to study the liquid phase properties of GaInP.
Chen, Sow-Hsin
2010-01-01T23:59:59.000Z
This review article describes our neutron scattering experiments made in the past four years for the understanding of the single-particle (hydrogen atom) dynamics of a protein and its hydration water and the strong coupling ...
Dynamic Evolution for Risk-Neutral Densities
2008-10-27T23:59:59.000Z
specifications of the data are as follows: the spot asset price is 590, the risk- free interest rate is ... than 10) the recovered risk-neutral densities exhibit less smoothness than in the cases .... Technical report, Purdue University, 1995. [31] A. M. ...
Cao, Jianshu
. Algorithms for centroid molecular dynamics Jianshu Cao and Gregory A. Voth Department of Chemistry 1994) Numerical algorithms are developed for the centroid molecular dynamics (centroid MD) method to carry out a direct calculation of the force on the centroid variables in the centroid MD algorithm
Hirunsit, Pussana
2009-05-15T23:59:59.000Z
Classical molecular dynamics (MD) simulations are performed to study structural and dynamic properties of water confined within graphite surfaces. The surfaces are separated at distances varying between 7 and 14.5 Å and the water density is held...
Harvesting graphics power for MD simulations
J. A. van Meel; A. Arnold; D. Frenkel; S. F. Portegies Zwart; R. G. Belleman
2007-09-20T23:59:59.000Z
We discuss an implementation of molecular dynamics (MD) simulations on a graphic processing unit (GPU) in the NVIDIA CUDA language. We tested our code on a modern GPU, the NVIDIA GeForce 8800 GTX. Results for two MD algorithms suitable for short-ranged and long-ranged interactions, and a congruential shift random number generator are presented. The performance of the GPU's is compared to their main processor counterpart. We achieve speedups of up to 80, 40 and 150 fold, respectively. With newest generation of GPU's one can run standard MD simulations at 10^7 flops/$.
Effects of Phase Transition induced density fluctuations on pulsar dynamics
Bagchi, Partha; Layek, Biswanath; Srivastava, Ajit M
2015-01-01T23:59:59.000Z
We show that density fluctuations during phase transitions in pulsar cores may have non-trivial effects on pulsar timings, and may also possibly account for glitches and anti-glitches. These density fluctuations invariably lead to non-zero off-diagonal components of the moment of inertia, leading to transient wobbling of star. Thus, accurate measurements of pulsar timing and intensity modulations (from wobbling) may be used to identify the specific pattern of density fluctuations, hence the particular phase transition, occurring inside the pulsar core. Changes in quadrupole moment from rapidly evolving density fluctuations during the transition, with very short time scales, may provide a new source for gravitational waves.
Probing Electron Dynamics with the Laplacian of the Momentum Density
Sukumar, N.; MacDougall, Preston J. [Middle Tennessee State University; Levit, M. Creon [Nasa Ames Research Center
2012-09-24T23:59:59.000Z
This chapter in the above-titled monograph presents topological analysis of the Laplacian of the electron momentum density in organic molecules. It relates topological features in this distribution to chemical and physical properties, particularly aromaticity and electron transport.
Why are MD simulated protein folding times wrong? Dmitry Nerukh
Nerukh, Dmitry
Why are MD simulated protein folding times wrong? Dmitry Nerukh Unilever Centre for Molecular.ac.uk The question of significant deviations of protein folding times simulated using molecular dynamics from
Meng Law, MD Amit M. Saindane, MD
Laidlaw, David
, flow dynamics, 17.12144 Magnetic resonance (MR), perfusion study, 18.12144 Sclerosis, multiple, 18 function CBF cerebral blood flow CBV cerebral blood volume MS multiple sclerosis MTT mean transit time NAWM in Relapsing-Remitting Multiple Sclerosis: Perfusion MR Imaging Findings in Normal-appearing White Matter1
Momentum density of spacetime and the gravitational dynamics
T. Padmanabhan
2015-06-11T23:59:59.000Z
I introduce a covariant four-vector $\\mathcal{G}^a[v]$, which can be interpreted as the momentum density attributed to the spacetime geometry by an observer with velocity $v^a$, and describe its properties: (a) Demanding that the total momentum of matter plus geometry is conserved for all observers, leads to the gravitational field equations. Thus, how matter curves spacetime is entirely determined by this principle of momentum conservation. (b) The $\\mathcal{G}^a[v]$ can be related to the gravitational Lagrangian in a manner similar to the usual definition of Hamiltonian in, say, classical mechanics. (c) Geodesic observers in a spacetime will find that the conserved total momentum vanishes on-shell. (d) The on-shell, conserved, total energy in a region of space, as measured by the comoving observers, will be equal to the total heat energy of the boundary surface. (e) The off-shell gravitational energy in a region will be the sum of the ADM energy in the bulk plus the thermal energy of the boundary. These results suggest that $\\mathcal{G}^a[v]$ can be a useful physical quantity to probe the gravitational theories.
Momentum density of spacetime and the gravitational dynamics
Padmanabhan, T
2015-01-01T23:59:59.000Z
I introduce a covariant four-vector $\\mathcal{G}^a[v]$, which can be interpreted as the momentum density attributed to the spacetime geometry by an observer with velocity $v^a$, and describe its properties: (a) Demanding that the total momentum of matter plus geometry is conserved for all observers, leads to the gravitational field equations. Thus, how matter curves spacetime is entirely determined by this principle of momentum conservation. (b) The $\\mathcal{G}^a[v]$ can be related to the gravitational Lagrangian in a manner similar to the usual definition of Hamiltonian in, say, classical mechanics. (c) Geodesic observers in a spacetime will find that the conserved total momentum vanishes on-shell. (d) The on-shell, conserved, total energy in a region of space, as measured by the comoving observers, will be equal to the total heat energy of the boundary surface. (e) The off-shell gravitational energy in a region will be the sum of the ADM energy in the bulk plus the thermal energy of the boundary. These res...
Bravo de la Parra, Rafael
Effects of density dependent sex allocation on the dynamics of a simultaneous hermaphroditic Available online 22 December 2009 Keywords: Sex-allocation model Sex-structured population dynamics Density model describing the dynamics of a population where sex allocation remains flexible throughout adult
Dynamical friction in constant density cores: a failure of the Chandrasekhar formula
J. I. Read; Tobias Goerdt; Ben Moore; A. P. Pontzen; Joachim Stadel; George Lake
2006-10-04T23:59:59.000Z
Using analytic calculations and N-body simulations we show that in constant density (harmonic) cores, sinking satellites undergo an initial phase of very rapid (super-Chandrasekhar) dynamical friction, after which they experience no dynamical friction at all. For density profiles with a central power law profile of log-slope, $-\\alpha$, the infalling satellite heats the background and causes $\\alpha$ to decrease. For $\\alpha < 0.5$ initially, the satellite generates a small central constant density core and stalls as in the $\\alpha = 0$ case. We discuss some astrophysical applications of our results to decaying satellite orbits, galactic bars and mergers of supermassive black hole binaries. In a companion paper we show that a central constant density core can provide a natural solution to the timing problem for Fornax's globular clusters.
Light-front representation of chiral dynamics in peripheral transverse densities
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Granados, Carlos G.; Weiss, Christian
2015-07-31T23:59:59.000Z
The nucleon's electromagnetic form factors are expressed in terms of the transverse densities of charge and magnetization at fixed light-front time. At peripheral transverse distances b = O(M_pi^{-1}) the densities are governed by chiral dynamics and can be calculated model-independently using chiral effective field theory (EFT). We represent the leading-order chiral EFT results for the peripheral transverse densities as overlap integrals of chiral light-front wave functions, describing the transition of the initial nucleon to soft pion-nucleon intermediate states and back. The new representation (a) explains the parametric order of the peripheral transverse densities; (b) establishes an inequality between the spin-independentmore »and -dependent densities; (c) exposes the role of pion orbital angular momentum in chiral dynamics; (d) reveals a large left-right asymmetry of the current in a transversely polarized nucleon and suggests a simple interpretation. The light-front representation enables a first-quantized, quantum-mechanical view of chiral dynamics that is fully relativistic and exactly equivalent to the second-quantized, field-theoretical formulation. It relates the charge and magnetization densities measured in low-energy elastic scattering to the generalized parton distributions probed in peripheral high-energy scattering processes. The method can be applied to nucleon form factors of other operators, e.g. the energy-momentum tensor.« less
Dynamics and instantaneous normal modes in a liquid with density anomalies
Massimo Pica Ciamarra; Peter Sollich
2015-08-19T23:59:59.000Z
We investigate the relation between the dynamical features of a supercooled liquid and those of its potential energy landscape, focusing on a model liquid with density anomalies. We consider, at fixed temperature, pairs of state points with different density but the same diffusion constant, and find that surprisingly they have identical dynamical features at all length and time scales. This is shown by the collapse of their mean square displacements and of their self--intermediate scattering functions at different wavevectors. We then investigate how the features of the energy landscape change with density, and establish that state points with equal diffusion constant have different landscapes. In particular, we find a correlation between the fraction of instantaneous normal modes connecting different energy minima and the diffusion constant, but unlike in other systems these two quantities are not in one--to--one correspondence with each other, showing that additional landscape features must be relevant in determining the diffusion constant.
Liquids that form due to dynamics of the molecules that depend on the local density
Richard P. Sear
2015-03-26T23:59:59.000Z
RNA molecules in living cells form what look like liquid droplets formed by liquid/liquid phase separation. But unlike the molecules in conventional phase separating mixtures, RNA molecules are transported by molecular motors that consume energy and so are out of equilibrium. Motivated by this we consider what sort of simple rules for the dynamics of model mRNA molecules lead to liquid/liquid phase separation. We find that dynamics that slow as the local density of molecules increases, drive the formation of liquids. We also look at the analogous separation of the two blocks of a block copolymer, in which the monomers of one block have dynamics that depend on the local density of monomers of that block. We find that this block condenses and separates from the monomers of the other block. This is a simple model of the out-of-equilibrium domain formation found in the chromatin in the nucleus of cells.
Dynamical density functional theory for the diffusion of injected Brownian particles
H. Löwen; M. Heinen
2014-09-08T23:59:59.000Z
While the theory of diffusion of a single Brownian particle in confined geometries is well-established by now, we discuss here the theoretical framework necessary to generalize the theory of diffusion to dense suspensions of strongly interacting Brownian particles. Dynamical density functional theory (DDFT) for classical Brownian particles represents an ideal tool for this purpose. After outlining the basic ingredients to DDFT we show that it can be readily applied to flowing suspensions with time-dependent particle sources. Particle interactions lead to considerable layering in the mean density profiles, a feature that is absent in the trivial case of noninteracting, freely diffusing particles. If the particle injection rate varies periodically in time with a suitable frequency, a resonance in the layering of the mean particle density profile is predicted.
Dynamic density functional theory of protein adsorption on polymer-coated nanoparticles
Angioletti-Uberti, Stefano; Dzubiella, Joachim
2014-01-01T23:59:59.000Z
We present a theoretical model for the description of the adsorption kinetics of globular proteins onto charged core-shell microgel particles based on Dynamic Density Functional Theory (DDFT). This model builds on a previous description of protein adsorption thermodynamics [Yigit \\textit{et al}, Langmuir 28 (2012)], shown to well interpret the available calorimetric experimental data of binding isotherms. In practice, a spatially-dependent free-energy functional including the same physical interactions is built, and used to study the kinetics via a generalised diffusion equation. To test this model, we apply it to the case study of Lysozyme adsorption on PNIPAM coated nanoparticles, and show that the dynamics obtained within DDFT is consistent with that extrapolated from experiments. We also perform a systematic study of the effect of various parameters in our model, and investigate the loading dynamics as a function of proteins' valence and hydrophobic adsorption energy, as well as their concentration and th...
The influence of dynamical friction on the collapse of spherical density pertubation
A. Del Popolo; M. Gambera; V. Antonuccio-Delogu
1996-10-24T23:59:59.000Z
We solve numerically the equations of motion for the collapse of a shell of baryonic matter falling into the central regions of a cluster of galaxies, taking into account of the presence of the substructure inducing dynamical friction. The evolution of the expansion parameter a(t) of the perturbation is calculated in spherical systems. The effect of dynamical friction is to reduce the binding radius and the total mass accreted by the central regions. Using a peak density profile given by Bardeen et al. (1986) we show how the binding radius of the perturbation is modified by dinamical friction. We show how dynamical friction modifies the collapse parameter of the perturbation slowing down the collapse.
Design of dynamic Hohlraum opacity samples to increase measured sample density on Z
Nash, T. J.; Rochau, G. A.; Bailey, J. E. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)
2010-10-15T23:59:59.000Z
We are attempting to measure the transmission of iron on Z at plasma temperatures and densities relevant to the solar radiation and convection zone boundary. The opacity data published by us to date has been taken at an electron density about a factor of 10 below the 9x10{sup 22}/cm{sup 3} electron density of this boundary. We present results of two-dimensional (2D) simulations of the heating and expansion of an opacity sample driven by the dynamic Hohlraum radiation source on Z. The aim of the simulations is to design foil samples that provide opacity data at increased density. The inputs or source terms for the simulations are spatially and temporally varying radiation temperatures with a Lambertian angular distribution. These temperature profiles were inferred on Z with on-axis time-resolved pinhole cameras, x-ray diodes, and bolometers. A typical sample is 0.3 {mu}m of magnesium and 0.078 {mu}m of iron sandwiched between 10 {mu}m layers of plastic. The 2D LASNEX simulations indicate that to increase the density of the sample one should increase the thickness of the plastic backing.
Design of dynamic hohlraum opacity samples to increase measured sample density on Z.
Rochau, Gregory Alan; Nash, Thomas J.; Bailey, James E.
2010-03-01T23:59:59.000Z
We are attempting to measure the transmission of iron on Z at plasma temperatures and densities relevant to the solar radiation and convection zone boundary. The opacity data published by us to date has been taken at an electron density about a factor of 10 below the 9 x 10{sup 22}/cm{sup 3} electron density of this boundary. We present results of two-dimensional (2D) simulations of the heating and expansion of an opacity sample driven by the dynamic Hohlraum radiation source on Z. The aim of the simulations is to design foil samples that provide opacity data at increased density. The inputs or source terms for the simulations are spatially and temporally varying radiation temperatures with a Lambertian angular distribution. These temperature profiles were inferred on Z with on-axis time-resolved pinhole cameras, x-ray diodes, and bolometers. A typical sample is 0.3{micro}m of magnesium and 0.078{micro}m of iron sandwiched between 10{micro}m layers of plastic. The 2D LASNEX simulations indicate that to increase the density of the sample one should increase the thickness of the plastic backing.
Kucerka, Norbert [Canadian Neutron Beam Centre and Comelius University (Slovakia); Holland, B [University of Guelph; Gray, C.G [University of Guelph; Tomberli, B [Brandon University; Katsaras, John [ORNL
2012-01-01T23:59:59.000Z
We combine molecular dynamics (MD) simulations and experiment, both small-angle neutron (SANS) and small-angle X-ray scattering (SAXS), to determine the precise structure of bilayers composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylglycerol (POPG), a lipid commonly encountered in bacterial membranes. Experiment and simulation are used to develop a one-dimensional scattering density profile (SDP) model suitable for the analysis of experimental data. The joint refinement of such data (i.e., SANS and SAXS) results in the area per lipid that is then used in the fixed-area simulations. In the final step, the direct comparison of simulated-to-experimental data gives rise to the detailed structure of POPG bilayers. From these studies we conclude that POPG s molecular area is 66.0 +/- 1.3 ^2, its overall bilayer thickness is 36.7 +/- 0.7 , and its hydrocarbon region thickness is 27.9 ( 0.6 , assuming a simulated value of 1203 ^3 for the total lipid volume.
Dynamical and sequential decay effects on isoscaling and density dependence of the symmetry energy
W. D. Tian; Y. G. Ma; X. Z. Cai; D. Q. Fang; W. Guo; C. W. Ma; G. H. Liu; W. Q. Shen; Y. Shi; H. W. Wang; K. Wang; W. Xu; T. Z. Yan
2006-01-25T23:59:59.000Z
The isoscaling properties of the primary and final products are studied via isospin dependent quantum molecular dynamics (IQMD) model and the followed sequential decay model GEMINI, respectively. It is found that the isoscaling parameters $\\alpha$ of both primary and final products keep no significant change for light fragments, but increases with the mass for intermediate and heavy products. The dynamical effects on isoscaling are exhibited by that $\\alpha$ value decreases a little with the evolution time of the system, and opposite trend for the heavy products. The secondary decay effects on isoscaling are reflected in the increasing of the $\\alpha$ value for the final products which experiences secondary decay process. Furthermore the density dependence of the symmetry energy has also been explored, it is observed that in the low densities the symmetry energy coefficient has the form of $C_{sym}(\\rho)\\sim C_{0}(\\rho/\\rho_{0})^{\\gamma}$, where $\\gamma = 0.7 \\sim 1.3$ for both primary and final products, but $C_{0}$ have different values for primary and final products. It is also suggested that it might be more reasonable to describe the density dependence of the symmetry energy coefficient by the $C_{sym}(\\rho/\\rho_{0})\\approx C_{1}(\\rho/\\rho_{0})^{\\gamma_{soft}} + C_{2}(\\rho/\\rho_{0})^{\\gamma_{stiff}}$ with $\\gamma_{soft}\\leq 1$, $\\gamma_{stiff}\\geq 1$ and $C_{1}, C_{2}$ constant parameters.
Dean Steve Nelson, MD Associate Dean for Research Wayne Backes, PhD Associate Dean for Fiscal Gregory, PhD Assistant Dean of VA Affairs Paul Rosenfeld, MD Basic Science Department Heads (6) Clinical, MD Director of Basic Sciences Curriculum Michael Levitzky, PhD Assistant Dean at Children's Hospital
Envelope density pattern around wide binary AGB stars: a dynamical model
J. H. He
2007-03-26T23:59:59.000Z
The goal is to build up a simple dynamical model for the out-flowing circumstellar envelope around AGB stars in a wide binary system to explore the parameter dependence of the geometrical characteristics of column density patterns. An AGB star in a wide binary system is considered as a 3-D piston model that can induce a 3-D quasi-spherical density structure in the circumstellar envelope by orbital motion of the AGB star. The column density pattern only depends on two parameters: eccentricity of the orbit e and the terminal outflow velocity to mean orbital velocity ratio gamma. When viewed perpendicular to the orbital plane, spiral, broken spiral, and incomplete concentric shell patterns can be seen, while when viewed along the orbital plane, alternative concentric half-shell, egg-shell, and half-shell half-gap patterns will develop. Non-zero eccentricity causes asymmetry, while larger gamma makes a weaker pattern and helps bring out asymmetry. A spiral pattern may becomes broken when e > 0.4. The spiral center is always less than 12% of spiral pitch away from the orbit center. One should have more chances (~ 80%) seeing spiral-like patterns than seeing concentric shells (~ 20%) in the circumstellar envelope of wide binary AGB stars.
Dynamic density functional theory of protein adsorption on polymer-coated nanoparticles
Stefano Angioletti-Uberti; Matthias Ballauff; Joachim Dzubiella
2014-07-30T23:59:59.000Z
We present a theoretical model for the description of the adsorption kinetics of globular proteins onto charged core-shell microgel particles based on Dynamic Density Functional Theory (DDFT). This model builds on a previous description of protein adsorption thermodynamics [Yigit \\textit{et al}, Langmuir 28 (2012)], shown to well interpret the available calorimetric experimental data of binding isotherms. In practice, a spatially-dependent free-energy functional including the same physical interactions is built, and used to study the kinetics via a generalised diffusion equation. To test this model, we apply it to the case study of Lysozyme adsorption on PNIPAM coated nanoparticles, and show that the dynamics obtained within DDFT is consistent with that extrapolated from experiments. We also perform a systematic study of the effect of various parameters in our model, and investigate the loading dynamics as a function of proteins' valence and hydrophobic adsorption energy, as well as their concentration and that of the nanoparticles. Although we concentrated here on the case of adsorption for a single protein type, the model's generality allows to study multi-component system, providing a reliable instrument for future studies of competitive and cooperative adsorption effects often encountered in protein adsorption experiments.
K. Nomura; T. Niksic; T. Otsuka; N. Shimizu; D. Vretenar
2011-06-14T23:59:59.000Z
Microscopic energy density functionals (EDF) have become a standard tool for nuclear structure calculations, providing an accurate global description of nuclear ground states and collective excitations. For spectroscopic applications this framework has to be extended to account for collective correlations related to restoration of symmetries broken by the static mean field, and for fluctuations of collective variables. In this work we compare two approaches to five-dimensional quadrupole dynamics: the collective Hamiltonian for quadrupole vibrations and rotations, and the Interacting Boson Model. The two models are compared in a study of the evolution of non-axial shapes in Pt isotopes. Starting from the binding energy surfaces of $^{192,194,196}$Pt, calculated with a microscopic energy density functional, we analyze the resulting low-energy collective spectra obtained from the collective Hamiltonian, and the corresponding IBM-2 Hamiltonian. The calculated excitation spectra and transition probabilities for the ground-state bands and the $\\gamma$-vibration bands are compared to the corresponding sequences of experimental states.
Wopperer, P; Reinhard, P -G; Suraud, E
2014-01-01T23:59:59.000Z
Various ways to analyze the dynamical response of clusters and molecules to electromagnetic perturbations exist. Particularly rich information can be obtained from measuring the properties of electrons emitted in the course of the excitation dynamics. Such an analysis of electron signals covers total ionization, Photo-Electron Spectra, Photoelectron Angular Distributions, and ideally combined PES/PAD, with a long history in molecular physics, also increasingly used in cluster physics. Recent progress in the design of new light sources (high intensity and/or frequency, ultra short pulses) opens new possibilities for measurements and thus has renewed the interest on the analysis of dynamical scenarios through these observables, well beyond a simple access to a density of states. This, in turn, has motivated many theoretical investigations of the dynamics of electronic emission for molecules and clusters. A theoretical tool of choice is here Time-Dependent Density Functional Theory (TDDFT) propagated in real tim...
Wall, Michael E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Van Benschoten, Andrew H. [Univ. of California, San Francisco, CA (United States); Sauter, Nicholas K. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Adams, Paul D. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States); Fraser, James S. [Univ. of California, San Francisco, CA (United States); Terwilliger, Thomas C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2014-12-01T23:59:59.000Z
X-ray diffraction from protein crystals includes both sharply peaked Bragg reflections and diffuse intensity between the peaks. The information in Bragg scattering is limited to what is available in the mean electron density. The diffuse scattering arises from correlations in the electron density variations and therefore contains information about collective motions in proteins. Previous studies using molecular-dynamics (MD) simulations to model diffuse scattering have been hindered by insufficient sampling of the conformational ensemble. To overcome this issue, we have performed a 1.1-?s MD simulation of crystalline staphylococcal nuclease, providing 100-fold more sampling than previous studies. This simulation enables reproducible calculations of the diffuse intensity and predicts functionally important motions, including transitions among at least eight metastable states with different active-site geometries. The total diffuse intensity calculated using the MD model is highly correlated with the experimental data. In particular, there is excellent agreement for the isotropic component of the diffuse intensity, and substantial but weaker agreement for the anisotropic component. The decomposition of the MD model into protein and solvent components indicates that protein–solvent interactions contribute substantially to the overall diffuse intensity. We conclude that diffuse scattering can be used to validate predictions from MD simulations and can provide information to improve MD models of protein motions.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Wall, Michael E.; Van Benschoten, Andrew H.; Sauter, Nicholas K.; Adams, Paul D.; Fraser, James S.; Terwilliger, Thomas C.
2014-12-01T23:59:59.000Z
X-ray diffraction from protein crystals includes both sharply peaked Bragg reflections and diffuse intensity between the peaks. The information in Bragg scattering is limited to what is available in the mean electron density. The diffuse scattering arises from correlations in the electron density variations and therefore contains information about collective motions in proteins. Previous studies using molecular-dynamics (MD) simulations to model diffuse scattering have been hindered by insufficient sampling of the conformational ensemble. To overcome this issue, we have performed a 1.1-?s MD simulation of crystalline staphylococcal nuclease, providing 100-fold more sampling than previous studies. This simulation enables reproducible calculationsmore »of the diffuse intensity and predicts functionally important motions, including transitions among at least eight metastable states with different active-site geometries. The total diffuse intensity calculated using the MD model is highly correlated with the experimental data. In particular, there is excellent agreement for the isotropic component of the diffuse intensity, and substantial but weaker agreement for the anisotropic component. The decomposition of the MD model into protein and solvent components indicates that protein–solvent interactions contribute substantially to the overall diffuse intensity. We conclude that diffuse scattering can be used to validate predictions from MD simulations and can provide information to improve MD models of protein motions.« less
Sealey, Kathleen Sullivan
The influence of habitat selection and density on the population dynamics of stony coral species of Biology, University of Miami, Coral Gables, FL, 33124 USA *Corresponding author: K. Semon Phone: 1-305-284-3013, Fax: 1-305-284-3039, e-mail: ksemon@bio.miami.edu Abstract Although stony corals are most frequently
Topology density correlator on dynamical domain-wall ensembles with nearly frozen topological charge
JLQCD collaboration; H. Fukaya; S. Aoki; G. Cossu; S. Hashimoto; T. Kaneko; J. Noaki
2014-11-13T23:59:59.000Z
Global topological charge decorrelates very slowly or even freezes in fine lattice simulations. On the other hand, its local fluctuations are expected to survive and lead to the correct physical results as long as the volume is large enough. We investigate this issue on recently generated configurations including dynamical domain-wall fermions at lattice spacings a = 0.08 fm and finer. We utilize the Yang-Mills gradient flow to define the topological charge density operator and calculate its long-distance correlation, through which we propose a new method for extracting the topological susceptibility in a sub-volume. This method takes care of the finite volume correction, which reduces the bias caused by the global topological charge. Our lattice data clearly show a shorter auto-correlation time than that of the naive definition using the whole lattice, and are less sensitive to the global topological history. Numerical results show a clear sea-quark mass dependence, which agrees well with the prediction of chiral perturbation theory.
Time-Dynamic Density and Mode Estimation with Application to Fast Mode Tracking
Müller, Hans-Georg
studied in the recursive density estimation framework (see, for example, Wegman and Davies 1995; Hall; Wegman and Marchette 2003). Real-time density estimation has been treated in Hall and Patil (1994), using
Editorial John Hickner, MD, MSc Editor-in-Chief
Alford, Simon
Health Care, Overland Park, Kan kEVin PEtErSon, MD, MPH University of Minnesota, St. Paul goutHAM rAo, MD
Uhm, Z. Lucas; Zhang, Bing, E-mail: uhm@pku.edu.cn, E-mail: zhang@physics.unlv.edu [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)
2014-07-01T23:59:59.000Z
We investigate the dynamics and afterglow light curves of gamma-ray burst blast waves that encounter various density structures (such as bumps, voids, or steps) in the surrounding ambient medium. We present and explain the characteristic response features that each type of density structure in the medium leaves on the forward shock (FS) and reverse shock (RS) dynamics for blast waves with either a long-lived or short-lived RS. We show that when the ambient medium density drops, the blast waves exhibit in some cases a period of an actual acceleration (even during their deceleration stage) due to adiabatic cooling of blast waves. Comparing numerical examples that have different shapes of bumps or voids, we propose a number of consistency tests that must be satisfied by correct modeling of blast waves. Our model results successfully pass these tests. Employing a Lagrangian description of blast waves, we perform a sophisticated calculation of afterglow emission. We show that as a response to density structures in the ambient medium, the RS light curves produce more significant variations than the FS light curves. Some observed features (such as rebrightenings, dips, or slow wiggles) can be more easily explained within the RS model. We also discuss the origin of these different features imprinted on the FS and RS light curves.
Mehdi Farzanehpour; I. V. Tokatly
2015-06-29T23:59:59.000Z
We use analytic (current) density-potential maps of time-dependent (current) density functional theory (TD(C)DFT) to inverse engineer analytically solvable time-dependent quantum problems. In this approach the driving potential (the control signal) and the corresponding solution of the Schr\\"odinger equation are parametrized analytically in terms of the basic TD(C)DFT observables. We describe the general reconstruction strategy and illustrate it with a number of explicit examples. First we consider the real space one-particle dynamics driven by a time-dependent electromagnetic field and recover, from the general TDDFT reconstruction formulas, the known exact solution for a driven oscillator with a time-dependent frequency. Then we use analytic maps of the lattice TD(C)DFT to control quantum dynamics in a discrete space. As a first example we construct a time-dependent potential which generates prescribed dynamics on a tight-binding chain. Then our method is applied to the dynamics of spin-1/2 driven by a time dependent magnetic field. We design an analytic control pulse that transfers the system from the ground to excited state and vice versa. This pulse generates the spin flip thus operating as a quantum NOT gate.
Koga,T.
2004-01-01T23:59:59.000Z
Supercritical carbon dioxide (scCO2) is being used increasingly as a green solvent in polymer processing. The major disadvantage thus far is that only a limited class of polymers, such as fluorinated or silicone-based polymers, can be dissolved in CO2. Here I show that large density fluctuations in scCO2 can significantly enhance the solubility of scCO2 in polymer thin films even when the bulk polymers have very poor miscibility with CO2. By using in situ neutron reflectivity, I found that a wide variety of polymer thin films can swell as much as 30-60% when exposed to scCO2 within a narrow temperature and pressure regime, known as the 'density fluctuation ridge', which defines the maximum density fluctuation amplitude in CO2. Furthermore, the swollen structures induced by the density fluctuation could be frozen by a flash evaporation of CO2 via the vitrification process of the polymer without a formation of void structures. X-ray reflectivity clearly showed that the scCO2 process could be used to produce uniform low-density polymer thin films. I also found that other properties of the vitrified films, such as index of refraction, dielectric constant and glass transition, were correlated with the low-density density profile.
Rowland, Joel C [Los Alamos National Laboratory; Hilley, George E [STANFORD UNIV; Fildani, Andrea [CHEVRON ETC
2009-01-01T23:59:59.000Z
Leveed submarine channels play a critical role in the transfer of sediment from the upper continental slopes to interslope basins and ultimately deepwater settings. Despite a reasonable understanding of how these channels grow once established, how such channels initiate on previously unchannelized portions of the seafloor remains poorly understood. We conducted a series of experiments that elucidate the influence of excess density relative to flow velocity on the dynamics of, and depositional morphologies arising from, density currents undergoing sudden unconfinement across a sloped bed. Experimental currents transported only suspended sediment across a non-erodible substrate. Under flow conditions ranging from supercritical to subcritical (bulk Richardson numbers of 0.02 to 1.2) our experiments failed to produce deposits resembling or exhibiting the potential to evolve into self-formed leveed channels. In the absence of excess density, a submerged sediment-laden flow produced sharp crested lateral deposits bounding the margins of the flow for approximately a distance of two outlet widths down basin. These lateral deposits terminated in a centerline deposit that greatly exceeded marginal deposits in thickness. As excess density increased relative to the outlet velocity, the rate of lateral spreading of the flow increased relative to the downstream propagation of the density current, transitioning from a narrow flow aligned with the channel outlet to a broad radially expanding flow. Coincident with these changes in flow dynamics, the bounding lateral deposits extended for shorter distances, had lower, more poorly defined crests that were increasingly wider in separation than the initial outlet, and progressively became more oblong rather than linear. Based on our results, we conclude that leveed channels cannot initiate from sediment-laden density currents under strictly depositional conditions. Partial confinement of these currents appears to be necessary to establish the hydrodynamic conditions needed for sediment deposition along the margins of a density current which ultimately may evolve into confining levees. We suggest that erosion into a previously unchannelized substrate is the mostly likely source of this partial confinement.
Puliafito, Vito, E-mail: vpuliafito@unime.it; Azzerboni, Bruno; Finocchio, Giovanni [Department of Electronic Engineering, Industrial Chemistry and Engineering, University of Messina, 98166 Messina (Italy); Torres, Luis [Department of Applied Physics, University of Salamanca, 37008 Salamanca (Spain); Ozatay, Ozhan [Department of Physics, Bogazici University, 34342 Bebek/Istanbul (Turkey); Hauet, Thomas [Institut Jean Lamour, Université de Lorraine-CNRS UMR 7198, 54506 Nancy (France)
2014-05-07T23:59:59.000Z
Dynamical bubble-like solitons have been recently investigated in nanocontact-based spin-torque oscillators with a perpendicular free layer. Those magnetic configurations can be excited also in different geometries as long as they consist of perpendicular materials. Thus, in this paper, a systematic study of the influence of both external field and high current on that kind of dynamics is performed for a spin-valve point-contact geometry where both free and fixed layers present strong perpendicular anisotropy. The usage of the topological density tool highlights the excitation of complex bubble/antibubble configurations. In particular, at high currents, a deformation of the soliton and its simultaneous shift from the contact area are observed and can be ascribable to the Oersted field. Results provide further detailed information on the excitation of solitons in perpendicular materials for application in spintronics, magnonics, and domain wall logic.
White, Stephen
or neutron scattering-length density projected along the bilayer normal (5). These profiles represent, California; and z NIST Center for Neutron Research, National Institute of Standards and Technology. INTRODUCTION X-ray and neutron diffraction are commonly used for studying the structure of membrane systems (1
Garfunkel, Eric
Hametz, M.D., Clinical Assistant Professor Stanley N. Katz, M.D., Clinical Assistant Professor Steven. Lathrop, M.D., Clinical Associate Professor Lawrence S. Meyers, M.D., Clinical Associate Professor Sandy S
Loesche, Mathias
Membrane association of the PTEN tumor suppressor: Neutron scattering and MD simulations reveal Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA c NIST Center for Neutron Research Phosphatidylserine Neutron reflection Tethered bilayer lipid membranes Molecular dynamics simulations a b s t r a c
Water adsorption on stepped ZnO surfaces from MD simulation David Raymand a
Goddard III, William A.
Water adsorption on stepped ZnO surfaces from MD simulation David Raymand a , Adri C.T. van Duin b Keywords: Zinc oxide Water Solidgas interfaces Construction and use of effective interatomic interactions force-field for use in molecular dynamics simulations of the ZnO water system. The force
Steady-State and Dynamic Modeling of Commercial Slurry High-Density Polyethylene (HDPE) Processes
Liu, Y. A.
, solvent, and oligomeric species from the polymer. Sol- vent is separated from the oligomer and recycled, Polymers Plus and Aspen Dynamics. The discussion includes thermodynamic properties, phase equilibrium, reaction kinetics, polymer properties, and other modeling issues. We characterize a Ziegler- Natta catalyst
Study of fusion dynamics using Skyrme energy density formalism with different surface corrections
Ishwar Dutt; Narinder K. Dhiman
2010-11-19T23:59:59.000Z
Within the framework of Skyrme energy density formalism, we investigate the role of surface corrections on the fusion of colliding nuclei. For this, the coefficient of surface correction was varied between 1/36 and 4/36, and its impact was studied on about 180 reactions. Our detailed investigations indicate a linear relationship between the fusion barrier heights and strength of the surface corrections. Our analysis of the fusion barriers advocate the strength of surface correction of 1/36.
Birgit Arb, MD Cape Fear Cancer
Olszewski Jr., Edward A.
Birgit Arb, MD Cape Fear Cancer Specialists Women of Hope is a charitable organization dedicated to enhancing the quality of life for the female cancer patient, their families, and friends. They provide through any type of cancer from diagnosis through survivorship. Women of Hope 1642 South 41st Street
Poster Presentations Marcella Alsan, MD, MPH, PhD
Kay, Mark A.
15 Poster Presentations Marcella Alsan, MD, MPH, PhD The direct and indirect effects of mass vaccination: Evidence from the 1985 Turkish campaign Michele Barry, MD; Stephen Luby, MD; Nancy Federspiel, PhD Global Health Fellows and Scholars Consortium Cynthia M. Castro, PhD; Abby C. King, PhD; Marcia Stefanick
Practical Attacks on Digital Signatures Using MD5 Message Digest
Practical Attacks on Digital Signatures Using MD5 Message Digest Ondrej Mikle Department schemes based on MD5 message digest on an example using GPG. Keywords: collision, hash function, MD5 1 used for file integrity checking and as a message digest in digital signature schemes. During CRYPTO
Driven cavity flow: from molecular dynamics to continuum hydrodynamics
Tiezheng Qian; Xiao-Ping Wang
2004-03-06T23:59:59.000Z
Molecular dynamics (MD) simulations have been carried out to investigate the slip of fluid in the lid driven cavity flow where the no-slip boundary condition causes unphysical stress divergence. The MD results not only show the existence of fluid slip but also verify the validity of the Navier slip boundary condition. To better understand the fluid slip in this problem, a continuum hydrodynamic model has been formulated based upon the MD verification of the Navier boundary condition and the Newtonian stress. Our model has no adjustable parameter because all the material parameters (density, viscosity, and slip length) are directly determined from MD simulations. Steady-state velocity fields from continuum calculations are in quantitative agreement with those from MD simulations, from the molecular-scale structure to the global flow. The main discovery is as follows. In the immediate vicinity of the corners where moving and fixed solid surfaces intersect, there is a core partial-slip region where the slippage is large at the moving solid surface and decays away from the intersection quickly. In particular, the structure of this core region is nearly independent of the system size. On the other hand, for sufficiently large system, an additional partial-slip region appears where the slippage varies as $1/r$ with $r$ denoting the distance from the corner along the moving solid surface. The existence of this wide power-law region is in accordance with the asymptotic $1/r$ variation of stress and the Navier boundary condition.
Free Energy Calculation in MD Simulation
Nielsen, Steven O.
Free Energy Calculation in MD Simulation #12;Basic Thermodynamics Helmoholtz free energy A = U TS + i Ni dA = wrev (reversible, const N V T) eq (22.9) McQuarrie & Simon Gibbs free energy G = U;Implication of Free Energy A B Keq = [A]/[B] Keq = exp (-G0 /RT) G0 = -RT ln Keq G = G0 + RT ln Q G > 0
Morzan, Uriel N.; Ramírez, Francisco F.; Scherlis, Damián A., E-mail: damian@qi.fcen.uba.ar, E-mail: mcgl@qb.ffyb.uba.ar [Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, Buenos Aires (C1428EHA) (Argentina); Oviedo, M. Belén; Sánchez, Cristián G. [Departamento de Matemática y Física, Facultad de Ciencias Químicas, INFIQC, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba (Argentina)] [Departamento de Matemática y Física, Facultad de Ciencias Químicas, INFIQC, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba (Argentina); Lebrero, Mariano C. González, E-mail: damian@qi.fcen.uba.ar, E-mail: mcgl@qb.ffyb.uba.ar [Instituto de Química y Fisicoquímica Biológicas, IQUIFIB, CONICET (Argentina)] [Instituto de Química y Fisicoquímica Biológicas, IQUIFIB, CONICET (Argentina)
2014-04-28T23:59:59.000Z
This article presents a time dependent density functional theory (TDDFT) implementation to propagate the Kohn-Sham equations in real time, including the effects of a molecular environment through a Quantum-Mechanics Molecular-Mechanics (QM-MM) hamiltonian. The code delivers an all-electron description employing Gaussian basis functions, and incorporates the Amber force-field in the QM-MM treatment. The most expensive parts of the computation, comprising the commutators between the hamiltonian and the density matrix—required to propagate the electron dynamics—, and the evaluation of the exchange-correlation energy, were migrated to the CUDA platform to run on graphics processing units, which remarkably accelerates the performance of the code. The method was validated by reproducing linear-response TDDFT results for the absorption spectra of several molecular species. Two different schemes were tested to propagate the quantum dynamics: (i) a leap-frog Verlet algorithm, and (ii) the Magnus expansion to first-order. These two approaches were confronted, to find that the Magnus scheme is more efficient by a factor of six in small molecules. Interestingly, the presence of iron was found to seriously limitate the length of the integration time step, due to the high frequencies associated with the core-electrons. This highlights the importance of pseudopotentials to alleviate the cost of the propagation of the inner states when heavy nuclei are present. Finally, the methodology was applied to investigate the shifts induced by the chemical environment on the most intense UV absorption bands of two model systems of general relevance: the formamide molecule in water solution, and the carboxy-heme group in Flavohemoglobin. In both cases, shifts of several nanometers are observed, consistently with the available experimental data.
Pan, Jianjun [ORNL; Cheng, Xiaolin [ORNL; Heberle, Frederick A [ORNL; Mostofian, Barmak [ORNL; Kucerka, Norbert [Canadian Neutron Beam Centre and Comelius University (Slovakia); Drazba, Paul [ORNL; Katsaras, John [ORNL
2012-01-01T23:59:59.000Z
Cholesterol and ether lipids are ubiquitous in mammalian cell membranes, and their interactions are crucial in ether lipid mediated cholesterol trafficking. We report on cholesterol s molecular interactions with ether lipids as determined using a combination of small-angle neutron and Xray scattering, and all-atom molecular dynamics (MD) simulations. A scattering density profile model for an ether lipid bilayer was developed using MD simulations, which was then used to simultaneously fit the different experimental scattering data. From analysis of the data the various bilayer structural parameters were obtained. Surface area constrained MD simulations were also performed to reproduce the experimental data. This iterative analysis approach resulted in good agreement between the experimental and simulated form factors. The molecular interactions taking place between cholesterol and ether lipids were then determined from the validated MD simulations. We found that in ether membranes cholesterol primarily hydrogen bonds with the lipid headgroup phosphate oxygen, while in their ester membrane counterparts cholesterol hydrogen bonds with the backbone ester carbonyls. This different mode of interaction between ether lipids and cholesterol induces cholesterol to reside closer to the bilayer surface, dehydrating the headgroup s phosphate moiety. Moreover, the three-dimensional lipid chain spatial density distribution around cholesterol indicates anisotropic chain packing, causing cholesterol to tilt. These insights lend a better understanding of ether lipid-mediated cholesterol trafficking and the roles that the different lipid species have in determining the structural and dynamical properties of membrane associated biomolecules.
Ultrafast dynamics of a near-solid-density layer in an intense femtosecond laser-excited plasma
Adak, Amitava; Chatterjee, Gourab; Kumar Singh, Prashant; Lad, Amit D.; Brijesh, P.; Kumar, G. Ravindra, E-mail: grk@tifr.res.in [Tata Institute of Fundamental Research, Dr. Homi Bhabha Road, Colaba, Mumbai 400005 (India); Blackman, David R. [York Plasma Institute, University of York, Heslington, York YO10 5DQ (United Kingdom); Robinson, A. P. L. [Central Laser Facility, Rutherford-Appleton Laboratory, Chilton, Didcot OX10 0QX (United Kingdom); Pasley, John [York Plasma Institute, University of York, Heslington, York YO10 5DQ (United Kingdom); Central Laser Facility, Rutherford-Appleton Laboratory, Chilton, Didcot OX10 0QX (United Kingdom)
2014-06-15T23:59:59.000Z
We report on the picosecond dynamics of a near-solid-density plasma generated by an intense, infrared (??=?800?nm) femtosecond laser using time-resolved pump-probe Doppler spectrometry. An initial red-shift is observed in the reflected third harmonic (??=?266?nm) probe pulse, which gets blue-shifted at longer probe-delays. A combination of particle-in-cell and radiation-hydrodynamics modelling is performed to model the pump laser interaction with the solid target. The results are post-processed to predict the Doppler shift. An excellent agreement is found between the results of such modelling and the experiment. The modelling suggests that the initial inward motion of the critical surface observed in the experiment is due to the passage of a shock-wave-like disturbance, launched by the pump interaction, propagating into the target. Furthermore, in order to achieve the best possible fit to the experimental data, it was necessary to incorporate the effects of bulk ion-acceleration resulting from the electrostatic field set up by the expulsion of electrons from the laser envelope. We also present results of time-resolved pump-probe reflectometry, which are corroborated with the spectrometry results using a 1-D reflectivity model.
Evaluation of Powertrain Options and Component Sizing for MD...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Sizing for MD and HD Applications on Real World Drive Cycles 2011 DOE Hydrogen and Fuel Cells Program, and Vehicle Technologies Program Annual Merit Review and Peer...
Kainulainen, Jouni
2012-01-01T23:59:59.000Z
Measuring the mass distribution of infrared dark clouds (IRDCs) over the wide dynamic range of their column densities is a fundamental obstacle in determining the initial conditions of high-mass star formation and star cluster formation. We present a new technique to derive high-dynamic-range, arcsecond-scale resolution column density data for IRDCs and demonstrate the potential of such data in measuring the density variance - sonic Mach number relation in molecular clouds. We combine near-infrared data from the UKIDSS/Galactic Plane Survey with mid-infrared data from the Spitzer/GLIMPSE survey to derive dust extinction maps for a sample of ten IRDCs. We then examine the linewidths of the IRDCs using 13CO line emission data from the FCRAO/Galactic Ring Survey and derive a column density - sonic Mach number relation for them. For comparison, we also examine the relation in a sample of nearby molecular clouds. The presented column density mapping technique provides a very capable, temperature independent tool f...
Net Zero Residential Test Facility Gaithersburg, MD Solar Photovoltaic Panels
Oak Ridge National Laboratory
1 Net Zero Residential Test Facility Gaithersburg, MD Solar Photovoltaic Panels Solar Thermal;NZERTF Gaithersburg, MD 3 Objectives Demonstrate Net-Zero Energy for a home similar in nature: · Demonstrate Net-Zero Energy Usage · Measure All Building Loads (Sensible and Latent) · Operate Dedicated
John F. Fuini III; Laurence G. Yaffe
2015-03-24T23:59:59.000Z
Using holography, we study the evolution of a spatially homogeneous, far from equilibrium, strongly coupled N=4 supersymmetric Yang-Mills plasma with a non-zero charge density or a background magnetic field. This gauge theory problem corresponds, in the dual gravity description, to an initial value problem in Einstein-Maxwell theory with homogeneous but anisotropic initial conditions. We explore the dependence of the equilibration process on different aspects of the initial departure from equilibrium and, while controlling for these dependencies, examine how the equilibration dynamics are affected by the presence of a non-vanishing charge density or an external magnetic field. The equilibration dynamics are remarkably insensitive to the addition of even large chemical potentials or magnetic fields; the equilibration time is set primarily by the form of the initial departure from equilibrium. For initial deviations from equilibrium which are well localized in scale, we formulate a simple model for equilibration times which agrees quite well with our results.
Chu, Shih-I
and structures PACS 85.65.+h Molecular electronic devices PACS 71.15.Pd Molecular dynamics calculations (Carr for electron transport dynamics in molecular devices Zhongyuan Zhou(a) and Shih-I Chu Department of Chemistry. The electron wave function is calculated by solving this equation in a finite P-space volume. This approach
High Performance Molecular Dynamic Simulation on Single and Multi-GPU Systems
Villa, Oreste; Chen, Long; Krishnamoorthy, Sriram
2010-05-30T23:59:59.000Z
The programming techniques supported and employed on these GPUs and Multi-GPUs systems are not sufficient to address problems exhibiting irregular, and unbalanced workload such as Molecular Dynamic (MD) simulations of systems with non-uniform densities. In this paper, we propose a task-based dynamic load-balancing solution to employ on MD simulations for single- and multi-GPU systems. The solution allows load balancing at a finer granularity than what is supported in existing APIs such as NVIDIA’s CUDA. Experimental results with a single-GPU configuration show that our fine-grained task solution can utilize the hardware more efficiently than the CUDA scheduler. On multi-GPU systems, our solution achieves near-linear speedup, load balance, and significant performance improvement over techniques based on standard CUDA APIs.
Mapping molecular dynamics computations to hypercubes
Lakamsani, Vamsee Krishna
1993-01-01T23:59:59.000Z
This thesis proposes an approach for systematic modeling, mapping and performance analysis of a Grand Challenge application problem in computational biology called Molecular Dynamics Simulation of Proteins. Molecular Dynamics (MD) is an important...
The Centre for Blood Research Jos Lpez, MD
Strynadka, Natalie
The Centre for Blood Research José López, MD Executive Vice-President of Research Puget Sound Blood for Blood Research Von Willebrand factor (VWF) is the largest protein in the blood and involved in both
Single-block collision attack on MD5 Marc Stevens
International Association for Cryptologic Research (IACR)
Single-block collision attack on MD5 Marc Stevens Cryptology Group, CWI P.O. Box 94079, NL-1090 GB Amsterdam, The Netherlands marc@marc-stevens.nl January 29, 2012 Abstract In 2010, Tao Xie and Dengguo Feng
Fujii, K., E-mail: fujii@me.kyoto-u.ac.jp; Atsumi, S.; Watanabe, S.; Shikama, T.; Hasuo, M. [Department of Mechanical Engineering and Science, Graduate School of Engineering, Kyoto University, Kyoto 606-8540 (Japan)] [Department of Mechanical Engineering and Science, Graduate School of Engineering, Kyoto University, Kyoto 606-8540 (Japan); Goto, M.; Morita, S. [National Institute for Fusion Science, Toki 509-5292 (Japan)] [National Institute for Fusion Science, Toki 509-5292 (Japan)
2014-02-15T23:59:59.000Z
We report development of a high dynamic range spectroscopic system comprising a spectrometer with 30% throughput and a camera with a low-noise fast-readout complementary metal-oxide semiconductor sensor. The system achieves a 10{sup 6} dynamic range (?20 bit resolution) and an instrumental function approximated by a Voigt profile with Gauss and Lorentz widths of 31 and 0.31 pm, respectively, for 656 nm light. The application of the system for line profile observations of the Balmer-? emissions from high temperature plasmas generated in the Large Helical Device is also presented. In the observed line profiles, emissions are detected in far wings more than 1.0 nm away from the line center, equivalent to neutral hydrogen atom kinetic energies above 1 keV. We evaluate atom density distributions in the core plasma by analyzing the line profiles.
A molecular dynamics study of polymer/graphene interfacial systems
Rissanou, Anastassia N.; Harmandaris, Vagelis [Department of Mathematics and Applied Mathematics, University of Crete, GR-71409, Heraklion, Crete, Greece and Institute of Applied and Computational Mathematics (IACM), Foundation for Research and Technology Hellas (FORTH), GR-71110, Heraklion, Cret (Greece)
2014-05-15T23:59:59.000Z
Graphene based polymer nanocomposites are hybrid materials with a very broad range of technological applications. In this work, we study three hybrid polymer/graphene interfacial systems (polystyrene/graphene, poly(methyl methacrylate)/graphene and polyethylene/graphene) through detailed atomistic molecular dynamics (MD) simulations. Density profiles, structural characteristics and mobility aspects are being examined at the molecular level for all model systems. In addition, we compare the properties of the hybrid systems to the properties of the corresponding bulk ones, as well as to theoretical predictions.
Southern California, University of
a stage for first-principles molecular dynamics simulation of thermite reaction at an Al/Fe2O3 interface experimental observation in thermite nanowire arrays. © 2009 American Institute of Physics. DOI: 10 to drive nanofluidics.1,2 Most widely used energetic materials for device integration are thermites, which
Wang, Weihuang
2009-05-15T23:59:59.000Z
is required. It pre-analyzes each received data frame to estimate the maximum number of necessary iterations for frame convergence. The results are then used to dynamically adjust decoder frequency and switch between multiple-voltage levels; thereby energy use...
R. Gutierrez; R. Caetano; P. B. Woiczikowski; T. Kubar; M. Elstner; G. Cuniberti
2009-01-22T23:59:59.000Z
We present a hybrid method based on a combination of quantum/classical molecular dynamics (MD) simulations and a mod el Hamiltonian approach to describe charge transport through bio-molecular wires with variable lengths in presence o f a solvent. The core of our approach consists in a mapping of the bio-molecular electronic structure, as obtained f rom density-functional based tight-binding calculations of molecular structures along MD trajectories, onto a low di mensional model Hamiltonian including the coupling to a dissipative bosonic environment. The latter encodes fluctuat ion effects arising from the solvent and from the molecular conformational dynamics. We apply this approach to the c ase of pG-pC and pA-pT DNA oligomers as paradigmatic cases and show that the DNA conformational fluctuations are essential in determining and supporting charge transport.
Hussein, Ibnelwaleed A.
of Branched Polyethylene Chains with Uniform Branch Distribution I. A. HUSSEIN, B. F. ABU-SHARKH* Department-density polyethylene (LLDPE) chains with different levels of branch content (BC), ranging from 10 to 80 branches/1000 C words: MD simulation, Polyethylene, branch content, chain conformation, radius of gyration
Wang, Weihuang
2009-05-15T23:59:59.000Z
Studies of Texas A&M University in partial fulflllment of the requirements for the degree of MASTER OF SCIENCE Approved by: Chair of Committee, Gwan Choi Committee Members, A. L. Narasimha Reddy Jean-Francois Chamberland Duncan M. Walker Head of Department... Chair of Advisory Committee: Dr. Gwan Choi This thesis presents a low-power LDPC decoder design based on speculative schedul- ing of energy necessary to decode dynamically varying data frame in both block-fading channels and general AWGN channels. A...
Einstein M.D. Program 20132014 applicant guide
Emmons, Scott
Einstein M.D. Program 20132014 applicant guide O F Y E S H I V A U N I V E R S I T Y Albert Einstein College of Medicine #12;2 Welcome Explore how Einstein can give you the skills to develop, learning opportunities and experiences that create the unique educational environment at Einstein
Einstein M.D. Program 20112012 applicant guide
Jenny, Andreas
Einstein M.D. Program 20112012 applicant guide O F Y E S H I V A U N I V E R S I T Y Albert Einstein College of Medicine #12;2 Welcome Explore how Einstein can give you the skills to develop, learning opportunities and experiences that create the unique educational environment at Einstein
md Science Service Featuro By Dr. Charles F. Brooks
No. 745 Sept. 30 md Science Service Featuro By Dr. Charles F. Brooks of Clark University. RAIN SKADOWS Mountains cast rain shadoms; often there is the greatest difference in rain- is fall between in me trade wind, laden with water vapor, blows persistently from one direction. is forced to rise
One Physics Ellipse College Park, MD 20740-3844
Nahar, Sultana Nurun
of physics. When we get closer to the April Meeting, APS will provide easy instructions on how to upload yourAmerican Physical Society One Physics Ellipse College Park, MD 20740-3844 Tel: (301) 209-3269 Fax: (301) 209-0867 www.aps.org President Robert L. Byer Stanford University President-Elect Michael S
TSUNAMI INUNDATION MAPPING FOR OCEAN CITY, MD NGDC DEM
Kirby, James T.
TSUNAMI INUNDATION MAPPING FOR OCEAN CITY, MD NGDC DEM BY BABAK TEHRANIRAD, SAEIDEH BANIHASHEMI BY THE NATIONAL TSUNAMI HAZARD MITIGATION PROGRAM NATIONAL WEATHER SERVICE GRANT NA10NWS4670010 CENTER FOR APPLIED COASTAL RESEARCH Ocean Engineering Laboratory University of Delaware Newark, Delaware 19716 #12;Tsunami
Diabetes A Growing Epidemic Michael McKee, MD, MPH
Goldman, Steven A.
Diabetes A Growing Epidemic Michael McKee, MD, MPH March 28, 2013 #12;Goals Diabetes Introduction Types of Diabetes Testing Prevention Treatments #12;In Memory of Benno Houver Bernd "Benno" Houver (1973-2013) #12;Diabetes Info 25.8 million people in the USA (8.3%) have diabetes ~25% of people with diabetes do
Eric G. Neilson, MD DEAN OF FEINBERG SCHOOL OF
Goldman, Robert D.
Eric G. Neilson, MD DEAN OF FEINBERG SCHOOL OF MEDICINE AND VICE PRESIDENT FOR MEDICAL AFFAIRS of Robert R. McCormick School of Engineering and Applied Science Dwight A. McBride, Dean of the Graduate and Vice Dean for Development and Alumni Relations for Feinberg School of Medicine Jaci A. Thiede
FPGA-BASED MULTIGRID COMPUTATION FOR MOLECULAR DYNAMICS SIMULATIONS
Herbordt, Martin
FPGA-BASED MULTIGRID COMPUTATION FOR MOLECULAR DYNAMICS SIMULATIONS Yongfeng Gu Martin C. Herbordt serial code. 1. INTRODUCTION Molecular Dynamics simulations (MD) are a fundamental tool for gaining Computer Architecture and Automated Design Laboratory Department of Electrical and Computer Engineering
Leroy, Frédéric, E-mail: f.leroy@theo.chemie.tu-darmstadt.de; Böhm, Michael C., E-mail: boehm@theo.chemie.tu-darmstadt.de [Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, D-64287 Darmstadt (Germany); Schulte, Joachim [Bruker Biospin GmbH, Silberstreifen, D-76287 Rheinstetten (Germany)] [Bruker Biospin GmbH, Silberstreifen, D-76287 Rheinstetten (Germany); Balasubramanian, Ganesh [Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011 (United States)] [Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011 (United States)
2014-04-14T23:59:59.000Z
We report reverse nonequilibrium molecular dynamics calculations of the thermal conductivity of isotope substituted (10,10) carbon nanotubes (CNTs) at 300 K. {sup 12}C and {sup 14}C isotopes both at 50% content were arranged either randomly, in bands running parallel to the main axis of the CNTs or in bands perpendicular to this axis. It is found that the systems with randomly distributed isotopes yield significantly reduced thermal conductivity. In contrast, the systems where the isotopes are organized in patterns parallel to the CNTs axis feature no reduction in thermal conductivity when compared with the pure {sup 14}C system. Moreover, a reduction of approximately 30% is observed in the system with the bands of isotopes running perpendicular to the CNT axis. The computation of phonon dispersion curves in the local density approximation and classical densities of vibrational states reveal that the phonon structure of carbon nanotubes is conserved in the isotope substituted systems with the ordered patterns, yielding high thermal conductivities in spite of the mass heterogeneity. In order to complement our conclusions on the {sup 12}C-{sup 14}C mixtures, we computed the thermal conductivity of systems where the {sup 14}C isotope was turned into pseudo-atoms of 20 and 40 atomic mass units.
End-to-End Rate-Distortion Optimized MD Mode Selection for Multiple Description Video Coding
Apostolopoulos, John G.
Multiple description (MD) video coding can be used to reduce the detrimental effects caused by transmission over lossy packet networks. A number of approaches have been proposed for MD coding, where each provides a different ...
Asbestos-related diseases in automobile mechanics Jacques Ameille, MD1
Paris-Sud XI, Université de
1 Asbestos-related diseases in automobile mechanics Jacques Ameille, MD1 , Nicole Rosenberg, MD2-related diseases in automobile mechanics Corresponding author Jacques Ameille, MD, Unité de pathologie plaques, automobile mechanics, HRCT inserm-00671970,version1-20Feb2012 Author manuscript, published
Pasta Nucleosynthesis: Molecular dynamics simulations of nuclear statistical equilibrium
M. E. Caplan; A. S. Schneider; C. J. Horowitz; D. K. Berry
2014-12-29T23:59:59.000Z
Background: Exotic non-spherical nuclear pasta shapes are expected in nuclear matter at just below saturation density because of competition between short range nuclear attraction and long range Coulomb repulsion. Purpose: We explore the impact of nuclear pasta on nucleosynthesis, during neutron star mergers, as cold dense nuclear matter is ejected and decompressed. Methods: We perform classical molecular dynamics simulations with 51200 and 409600 nucleons, that are run on GPUs. We expand our simulation region to decompress systems from an initial density of 0.080 fm^{-3} down to 0.00125 fm^{-3}. We study proton fractions of Y_P=0.05, 0.10, 0.20, 0.30, and 0.40 at T =0.5, 0.75, and 1.0 MeV. We calculate the composition of the resulting systems using a cluster algorithm. Results: We find final compositions that are in good agreement with nuclear statistical equilibrium models for temperatures of 0.75 and 1 MeV. However, for proton fractions greater than Y_P=0.2 at a temperature of T = 0.5 MeV, the MD simulations produce non-equilibrium results with large rod-like nuclei. Conclusions: Our MD model is valid at higher densities than simple nuclear statistical equilibrium models and may help determine the initial temperatures and proton fractions of matter ejected in mergers.
Einstein M.D. Program 20142015 APPLICANT GUIDE
Emmons, Scott
Einstein M.D. Program 20142015 APPLICANT GUIDE O F Y E S H I V A U N I V E R S I T Y Albert Einstein College of Medicine #12;2 Welcome Explore how Einstein can give you the skills to develop at Einstein. There are 183 students in the first- year class. 8,193 applicants applied for entrance and 1
Nehorai, Arye
Brain-Computer Interfaces in Medicine Jerry J. Shih, MD; Dean J. Krusienski, PhD; and Jonathan R. Wolpaw, MD Abstract Brain-computer interfaces (BCIs) acquire brain signals, analyze them, and translate, electrocorticographic, and other brain signals for increasingly complex control of cursors, robotic arms, prostheses
Local control theory in trajectory-based nonadiabatic dynamics
Curchod, Basile F. E.; Penfold, Thomas J.; Rothlisberger, Ursula; Tavernelli, Ivano [Laboratory of Computational Chemistry and Biochemistry, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland); Laboratory of Computational Chemistry and Biochemistry, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, Switzerland, (Switzerland); Ecole Polytechnique Federale de Lausanne, Laboratoire de Spectroscopie Ultrarapide, ISIC, FSB-BSP, CH-1015 Lausanne, Switzerland, (Switzerland); SwissFEL, Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Laboratory of Computational Chemistry and Biochemistry, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland)
2011-10-15T23:59:59.000Z
In this paper, we extend the implementation of nonadiabatic molecular dynamics within the framework of time-dependent density-functional theory in an external field described in Tavernelli et al.[Phys. Rev. A 81, 052508 (2010)] by calculating on-the-fly pulses to control the population transfer between electronic states using local control theory. Using Tully's fewest switches trajectory surface hopping method, we perform MD to control the photoexcitation of LiF and compare the results to quantum dynamics (QD) calculations performed within the Heidelberg multiconfiguration time-dependent Hartree package. We show that this approach is able to calculate a field that controls the population transfer between electronic states. The calculated field is in good agreement with that obtained from QD, and the differences that arise are discussed in detail.
Carmichael, Owen
UC Davis-LLNL Scientific Advisory Committee Timothy Albertson, MD, PhD, Vice Chair, Internal Berglund, MD, PhD, CTSC Program Director Stuart Cohen, MD, Head of Infection Control, UCDMC Jeffrey Elias, PhD, Manager, Grant Coordination **Captain** Hernando Garzon, MD, Emergency Medicine, Kaiser Jeffrey
Campbell, Kevin P.
,* Renato Mantegazza, MD,* Carlo Antozzi, MD,* Laura Jarre, MD,$ Antonella Pini, MD,S Giuseppe Gobbi, MD, Mantegazza R, Antozzi C, Jarre L, Pini A, Gobbi G, Bianchi C, Cornelio F, Campbell KP, Mora M. Clinical
Pan, Jianjun [University of South Florida, Tampa (USF)] [University of South Florida, Tampa (USF); Cheng, Xiaolin [ORNL] [ORNL; Monticelli, Luca [Institut National de la Santé et de la Recherche Médicale (INSERM) and INTS, France] [Institut National de la Santé et de la Recherche Médicale (INSERM) and INTS, France; Heberle, Frederick A [ORNL] [ORNL; Kucerka, Norbert [Atomic Energy of Canada Limited (AECL), Canadian Neutron Beam Centre (CNBC) and Comenius University,] [Atomic Energy of Canada Limited (AECL), Canadian Neutron Beam Centre (CNBC) and Comenius University,; Tieleman, D. Peter [University of Calgary, ALberta, Canada] [University of Calgary, ALberta, Canada; Katsaras, John [ORNL] [ORNL
2014-01-01T23:59:59.000Z
Phosphatidylserine (PS) lipids play essential roles in biological processes, including enzyme activation and apoptosis. We report on the molecular structure and atomic scale interactions of a fluid bilayer composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylserine (POPS). A scattering density profile model, aided by molecular dynamics (MD) simulations, was developed to jointly refine different contrast small-angle neutron and X-ray scattering data, which yielded a lipid area of 62.7 A2 at 25 C. MD simulations with POPS lipid area constrained at different values were also performed using all-atom and aliphatic united-atom models. The optimal simulated bilayer was obtained using a model-free comparison approach. Examination of the simulated bilayer, which agrees best with the experimental scattering data, reveals a preferential interaction between Na+ ions and the terminal serine and phosphate moieties. Long-range inter-lipid interactions were identified, primarily between the positively charged ammonium, and the negatively charged carboxylic and phosphate oxygens. The area compressibility modulus KA of the POPS bilayer was derived by quantifying lipid area as a function of surface tension from area-constrained MD simulations. It was found that POPS bilayers possess a much larger KA than that of neutral phosphatidylcholine lipid bilayers. We propose that the unique molecular features of POPS bilayers may play an important role in certain physiological functions.
Lan, Tian [California Institute of Technology, Pasadena] [California Institute of Technology, Pasadena; Li, Chen [ORNL] [ORNL; Niedziela, Jennifer L [ORNL] [ORNL; Smith, Hillary [California Institute of Technology, Pasadena] [California Institute of Technology, Pasadena; Abernathy, Douglas L [ORNL] [ORNL; Rossman, George [California Institute of Technology, Pasadena] [California Institute of Technology, Pasadena; Fultz, B. [California Institute of Technology, Pasadena] [California Institute of Technology, Pasadena
2014-01-01T23:59:59.000Z
Inelastic neutron scattering measurements on silver oxide (Ag2O) with the cuprite structure were performed at temperatures from 40 to 400 K, and Fourier transform far-infrared spectra were measured from 100 to 300 K. The measured phonon densities of states and the infrared spectra showed unusually large energy shifts with temperature, and large linewidth broadenings. First principles molecular dynamics (MD) calculations were performed at various temperatures, successfully accounting for the negative thermal expansion (NTE) and local dynamics. Using the Fourier-transformed velocity autocorrelation method, the MD calculations reproduced the large anharmonic effects of Ag2O, and were in excellent agreement with the neutron scattering data. The quasiharmonic approximation (QHA) was less successful in accounting for much of the phonon behavior. The QHA could account for some of the NTE below 250 K, although not at higher temperatures. Strong anharmonic effects were found for both phonons and for the NTE. The lifetime broadenings of Ag2O were explained by anharmonic perturbation theory, which showed rich interactions between the Ag-dominated modes and the O-dominated modes in both up- and down-conversion processes.
Tanaka, Kouichi [DENSO CORPORATION, Kariya, Aichi 448-8661 (Japan); Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan); Ogata, Shuji; Kobayashi, Ryo; Tamura, Tomoyuki [Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan); Kitsunezuka, Masashi; Shinma, Atsushi [DENSO CORPORATION, Kariya, Aichi 448-8661 (Japan)
2013-11-21T23:59:59.000Z
Developing a composite material of polymers and micrometer-sized fillers with higher heat conductance is crucial to realize modular packaging of electronic components at higher densities. Enhancement mechanisms of the heat conductance of the polymer-filler interfaces by adding the surface-coupling agent in such a polymer composite material are investigated through the non-equilibrium molecular dynamics (MD) simulation. A simulation system is composed of ?-alumina as the filler, bisphenol-A epoxy molecules as the polymers, and model molecules for the surface-coupling agent. The inter-atomic potential between the ?-alumina and surface-coupling molecule, which is essential in the present MD simulation, is constructed to reproduce the calculated energies with the electronic density-functional theory. Through the non-equilibrium MD simulation runs, we find that the thermal resistance at the interface decreases significantly by increasing either number or lengths of the surface-coupling molecules and that the effective thermal conductivity of the system approaches to the theoretical value corresponding to zero thermal-resistance at the interface. Detailed analyses about the atomic configurations and local temperatures around the interface are performed to identify heat-transfer routes through the interface.
Weeks, Eric R.
this behavior. The mode coupling theory [1] describes many aspects of dynamical behavior at high T- stood as a simple activated bondbreaking process. Here, we perform molecular dynamics (MD) simula- tionsSpatially Heterogeneous Dynamics and Dynamic Facilitation in a Model of Viscous Silica Michael
Molecular Dynamics Simulations of Heat Transfer In Nanoscale Liquid Films
Kim, Bo Hung
2010-07-14T23:59:59.000Z
Molecular Dynamics (MD) simulations of nano-scale flows typically utilize fixed lattice crystal interactions between the fluid and stationary wall molecules. This approach cannot properly model thermal interactions at the wall-fluid interface...
Chu, Shih-I
Time-dependent density-functional theory for strong-field multiphoton processes: Application 1997 We present a self-interaction-free time-dependent density-functional theory TDDFT. The theory is based on the extension of the time-dependent Kohn-Sham formalism. The time-dependent exchange
Coupling all-atom molecular dynamics simulations of ions in water with Brownian dynamics
Radek Erban
2015-08-12T23:59:59.000Z
Molecular dynamics (MD) simulations of ions (K$^+$, Na$^+$, Ca$^{2+}$ and Cl$^-$) in aqueous solutions are investigated. Water is described using the SPC/E model. A stochastic coarse-grained description for ion behaviour is presented and parameterized using MD simulations. It is given as a system of coupled stochastic and ordinary differential equations, describing the ion position, velocity and acceleration. The stochastic coarse-grained model provides an intermediate description between all-atom MD simulations and Brownian dynamics (BD) models. It is used to develop a multiscale method which uses all-atom MD simulations in parts of the computational domain and (less detailed) BD simulations in the remainder of the domain.
DFT-MD approach to TiO2/liquid interface systems for photocatalysis and dye-sensitised solar cell
Katsumoto, Shingo
DFT-MD approach to TiO2/liquid interface systems for photocatalysis and dye-sensitised solar cell- namics (MD) analysis of TiO2/solution in- terfaces related to photocatalysis and dye- sensitized solar
Valero-Cuevas, Francisco
@chla.usc.edu (323) 3612265 Alan B. Lewis, M.D. Vice Chair, Committee on Clinical Investigations alewis Deirdre Anglin, MD ViceChair, IRB Email: anglin@usc.edu Phone: (323) 2232340 Robert Larsen, MD Vice
Molecular Dynamics Simulations of Temperature Equilibration in Dense Hydrogen
Glosli, J; Graziani, F; More, R; Murillo, M; Streitz, F; Surh, M; Benedict, L; Hau-Riege, S; Langdon, A; London, R
2008-02-14T23:59:59.000Z
The temperature equilibration rate in dense hydrogen (for both T{sub i} > T{sub e} and T{sub i} < T{sub e}) has been calculated with large-scale molecular dynamics simulations for temperatures between 10 and 300 eV and densities between 10{sup 20}/cc to 10{sup 24}/cc. Careful attention has been devoted to convergence of the simulations, including the role of semiclassical potentials. We find that for Coulomb logarithms L {approx}> 1, Brown-Preston-Singleton [Brown et al., Phys. Rep. 410, 237 (2005)] with the sub-leading corrections and the fit of Gericke-Murillo-Schlanges [Gericke et al., PRE 65, 036418 (2003)] to the T-matrix evaluation of the collision operator, agrees with the MD data to within the error bars of the simulation. For more strongly-coupled plasmas where L {approx}< 1, our numerical results are consistent with the fit of Gericke-Murillo-Schlanges.
A Molecular Dynamics Simulation of the Turbulent Couette Minimal Flow Unit
Smith, E R
2015-01-01T23:59:59.000Z
A molecular dynamics (MD) simulation of planar Couette flow is presented for the minimal channel in which turbulence structures can be sustained. Evolution over a single breakdown and regeneration cycle is compared to computational fluid dynamics (CFD) simulations. Qualitative similar structures are observed and turbulent statistics show excellent quantitative agreement. The molecular scale law of the wall is presented in which stick-slip molecular wall-fluid interactions replace the no-slip conditions. The impact of grid resolution is explored and the observed structures are seen to be dependant on averaging time and length scales. The kinetic energy spectra show a range of scales are present in the molecular system and that spectral content is dependent on the grid resolution employed. The subgrid velocity of the molecules is compared to spatial averaged velocity using joint probability density functions. Molecular trajectories, diffusions and Lagrangian statistics are presented. The importance of sub-grid ...
Molecular Dynamics Simulations on High-Performance Reconfigurable
Herbordt, Martin
23 Molecular Dynamics Simulations on High-Performance Reconfigurable Computing Systems MATT CHIU. 2010. Molecular dynamics simulations on high performance recon- figurable computing systems. ACM Trans://doi.acm.org/10.1145/1862648.1862653. 1. INTRODUCTION Molecular dynamics simulation (MD) is a
Some recent efforts toward high density implosions
McClellan, G.E.
1980-12-04T23:59:59.000Z
Some recent Livermore efforts towards achieving high-density implosions are presented. The implosion dynamics necessary to compress DT fuel to 10 to 100 times liquid density are discussed. Methods of diagnosing the maximum DT density for a specific design are presented along with results to date. The dynamics of the double-shelled target with an exploding outer shell are described, and some preliminary experimental results are presented.
Vehicle Technologies Office Merit Review 2014: Cummins MD & HD Accessory Hybridization CRADA
Broader source: Energy.gov [DOE]
Presentation given by Oak Ridge National Laboratory at 2014 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about Cummins MD &...
Automatic Search of Differential Path in MD4 Pierre-Alain Fouque, Gatan Leurent, Phong Nguyen
International Association for Cryptologic Research (IACR)
Automatic Search of Differential Path in MD4 Pierre-Alain Fouque, Gaëtan Leurent, Phong Nguyen paths were found "by hand". In this paper, we present an algorithm which automatically finds suitable
Vehicle Technologies Office Merit Review 2015: Cummins MD & HD Accessory Hybridization CRADA
Broader source: Energy.gov [DOE]
Presentation given by Oak Ridge National Laboratory at 2015 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about Cummins MD &...
Catharine Whiteside, MD PhD Vice Provost, Relations with Health Care Institutions
Zandstra, Peter W.
Catharine Whiteside, MD PhD Dean Vice Provost, Relations with Health Care Institutions Office. Professor Andrews received her PhD from the University of Toronto and completed further training
Julie Gralow, MD Director Breast Medical Oncology, Seattle Cancer Care Alliance
Brent, Roger
Julie Gralow, MD Director Breast Medical Oncology, Seattle Cancer Care Alliance Founder Care Alliance, as well as a Member of the Clinical Research Division of the Fred Hutchinson Cancer
Mineral density volume gradients in normal and diseased human tissues
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Djomehri, Sabra I.; Candell, Susan; Case, Thomas; Browning, Alyssa; Marshall, Grayson W.; Yun, Wenbing; Lau, S. H.; Webb, Samuel; Ho, Sunita P.; Aikawa, Elena
2015-04-09T23:59:59.000Z
Clinical computed tomography provides a single mineral density (MD) value for heterogeneous calcified tissues containing early and late stage pathologic formations. The novel aspect of this study is that, it extends current quantitative methods of mapping mineral density gradients to three dimensions, discretizes early and late mineralized stages, identifies elemental distribution in discretized volumes, and correlates measured MD with respective calcium (Ca) to phosphorus (P) and Ca to zinc (Zn) elemental ratios. To accomplish this, MD variations identified using polychromatic radiation from a high resolution micro-computed tomography (micro-CT) benchtop unit were correlated with elemental mapping obtained from a microprobe X-raymore »fluorescence (XRF) using synchrotron monochromatic radiation. Digital segmentation of tomograms from normal and diseased tissues (N=5 per group; 40-60 year old males) contained significant mineral density variations (enamel: 2820-3095mg/cc, bone: 570-1415mg/cc, cementum: 1240-1340mg/cc, dentin: 1480-1590mg/cc, cementum affected by periodontitis: 1100-1220mg/cc, hypomineralized carious dentin: 345-1450mg/cc, hypermineralized carious dentin: 1815-2740mg/cc, and dental calculus: 1290-1770mg/cc). A plausible linear correlation between segmented MD volumes and elemental ratios within these volumes was established, and Ca/P ratios for dentin (1.49), hypomineralized dentin (0.32-0.46), cementum (1.51), and bone (1.68) were observed. Furthermore, varying Ca/Zn ratios were distinguished in adapted compared to normal tissues, such as in bone (855-2765) and in cementum (595-990), highlighting Zn as an influential element in prompting observed adaptive properties. Hence, results provide insights on mineral density gradients with elemental concentrations and elemental footprints that in turn could aid in elucidating mechanistic processes for pathologic formations.« less
Spin dynamics simulation of electron spin relaxation in Ni{sup 2+}(aq)
Rantaharju, Jyrki, E-mail: jjrantaharju@gmail.com; Mareš, Ji?í, E-mail: jiri.mares@oulu.fi; Vaara, Juha, E-mail: juha.vaara@iki.fi [NMR Research Group, Department of Physics, University of Oulu, P.O. Box 3000, Oulu, FIN-90014 (Finland)
2014-07-07T23:59:59.000Z
The ability to quantitatively predict and analyze the rate of electron spin relaxation of open-shell systems is important for electron paramagnetic resonance and paramagnetic nuclear magnetic resonance spectroscopies. We present a combined molecular dynamics (MD), quantum chemistry (QC), and spin dynamics simulation method for calculating such spin relaxation rates. The method is based on the sampling of a MD trajectory by QC calculations, to produce instantaneous parameters of the spin Hamiltonian used, in turn, to numerically solve the Liouville-von Neumann equation for the time evolution of the spin density matrix. We demonstrate the approach by simulating the relaxation of electron spin in an aqueous solution of Ni{sup 2+} ion. The spin-lattice (T{sub 1}) and spin-spin (T{sub 2}) relaxation rates are extracted directly from the simulations of the time dependence of the longitudinal and transverse magnetization, respectively. Good agreement with the available, indirectly obtained experimental data is obtained by our method.
Tamio Yamazaki
2012-08-06T23:59:59.000Z
To evaluate shear viscosity of ethylene glycol oligomers (EGO)/water binary mixture by means of coarse-grained molecular dynamics (CG-MD) simulations, we proposed the self-diffusion-coefficient-based parameterization of non-bonded interactions among CG particles. Our parameterization procedure consists of three steps: 1) determination of bonded potentials, 2) scaling for time and solvent diffusivity, and 3) optimization of Lennard-Jones parameters to reproduce experimental self-diffusion coefficient and density data. With the determined parameters and the scaling relations, we evaluated shear viscosities of aqueous solutions of EGOs with various molecular weights and concentrations. Our simulation result are in close agreement with the experimental data. The largest simulation in this article corresponds to a 1.2 microseconds atomistic simulation for 100,000 atoms. Our CG model with the parameterization scheme for CG particles may be useful to study the dynamic properties of a liquid which contains relatively low molecular weight polymers or oligomers.
Density hysteresis of heavy water confined in a nanoporous silica matrix
Chen, Sow-Hsin
of Technology, Cambridge, MA 02139; b Neutron Scattering Science Division and Joint Institute for Neutron (received for review January 5, 2011) A neutron scattering technique was developed to measure the density and Technology Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD
Krishtal, Alisa; Genova, Alessandro; Pavanello, Michele
2015-01-01T23:59:59.000Z
Subsystem Density-Functional Theory (DFT) is an emerging technique for calculating the electronic structure of complex molecular and condensed phase systems. In this topical review, we focus on some recent advances in this field related to the computation of condensed phase systems, their excited states, and the evaluation of many-body interactions between the subsystems. As subsystem DFT is in principle an exact theory, any advance in this field can have a dual role. One is the possible applicability of a resulting method in practical calculations. The other is the possibility of shedding light on some quantum-mechanical phenomenon which is more easily treated by subdividing a supersystem into subsystems. An example of the latter is many-body interactions. In the discussion, we present some recent work from our research group as well as some new results, casting them in the current state-of-the-art in this review as comprehensively as possible.
Masson, Jean-Baptiste; Salvatico, Charlotte; Renner, Marianne; Specht, Christian G; Triller, Antoine; Dahan, Maxime
2015-01-01T23:59:59.000Z
Protein mobility is conventionally analyzed in terms of an effective diffusion. Yet, this description often fails to properly distinguish and evaluate the physical parameters (such as the membrane friction) and the biochemical interactions governing the motion. Here, we present a method combining high-density single-molecule imaging and statistical inference to separately map the diffusion and energy landscapes of membrane proteins across the cell surface at ~100 nm resolution (with acquisition of a few minutes). When applying these analytical tools to glycine neurotransmitter receptors (GlyRs) at inhibitory synapses, we find that gephyrin scaffolds act as shallow energy traps (~3 kBT) for GlyRs, with a depth modulated by the biochemical properties of the receptor-gephyrin interaction loop. In turn, the inferred maps can be used to simulate the dynamics of proteins in the membrane, from the level of individual receptors to that of the population, and thereby, to model the stochastic fluctuations of physiologi...
Liu Li; Martin, Courtney; Farrar, James M. [Department of Chemistry, University of Rochester, Rochester, New York 14627 (United States)
2006-10-07T23:59:59.000Z
The reactions between OH{sup +}({sup 3}{sigma}{sup -}) and C{sub 2}H{sub 2} have been studied using crossed ion and molecular beams and density functional theory calculations. Both charge transfer and proton transfer channels are observed. Products formed by carbon-carbon bond cleavage analogous to those formed in the isoelectronic O({sup 3}P)+C{sub 2}H{sub 2} reaction, e.g., {sup 3}CH{sub 2}+HCO{sup +}, are not observed. The center of mass flux distributions of both product ions at three different energies are highly asymmetric, with maxima close to the velocity and direction of the precursor acetylene beam, characteristic of direct reactions. The internal energy distributions of the charge transfer products are independent of collision energy and are peaked at the reaction exothermicity, inconsistent with either the existence of favorable Franck-Condon factors or energy resonance. In proton transfer, almost the entire reaction exothermicity is transformed into product internal excitation, consistent with mixed energy release in which the proton is transferred with both the breaking and forming bonds extended. Most of the incremental translational energy in the two higher-energy experiments appears in product translational energy, providing an example of induced repulsive energy release.
Dupont, Pierre
into the left ventricle and passing a balloon through the needle into the aortic valve. The balloon to a restriction in the aortic valve. As depicted in Fig. 1, correcting this defect involves inserting a needle is then inflated, which expands the valve, reducing the pressure in the ventricle and allowing it to develop
R. James Kirkpatrick; Andrey G. Kalinichev
2008-11-25T23:59:59.000Z
Research supported by this grant focuses on molecular scale understanding of central issues related to the structure and dynamics of geochemically important fluids, fluid-mineral interfaces, and confined fluids using computational modeling and experimental methods. Molecular scale knowledge about fluid structure and dynamics, how these are affected by mineral surfaces and molecular-scale (nano-) confinement, and how water molecules and dissolved species interact with surfaces is essential to understanding the fundamental chemistry of a wide range of low-temperature geochemical processes, including sorption and geochemical transport. Our principal efforts are devoted to continued development of relevant computational approaches, application of these approaches to important geochemical questions, relevant NMR and other experimental studies, and application of computational modeling methods to understanding the experimental results. The combination of computational modeling and experimental approaches is proving highly effective in addressing otherwise intractable problems. In 2006-2007 we have significantly advanced in new, highly promising research directions along with completion of on-going projects and final publication of work completed in previous years. New computational directions are focusing on modeling proton exchange reactions in aqueous solutions using ab initio molecular dynamics (AIMD), metadynamics (MTD), and empirical valence bond (EVB) approaches. Proton exchange is critical to understanding the structure, dynamics, and reactivity at mineral-water interfaces and for oxy-ions in solution, but has traditionally been difficult to model with molecular dynamics (MD). Our ultimate objective is to develop this capability, because MD is much less computationally demanding than quantum-chemical approaches. We have also extended our previous MD simulations of metal binding to natural organic matter (NOM) to a much longer time scale (up to 10 ns) for significantly larger systems. These calculations have allowed us, for the first time, to study the effects of metal cations with different charges and charge density on the NOM aggregation in aqueous solutions. Other computational work has looked at the longer-time-scale dynamical behavior of aqueous species at mineral-water interfaces investigated simultaneously by NMR spectroscopy. Our experimental NMR studies have focused on understanding the structure and dynamics of water and dissolved species at mineral-water interfaces and in two-dimensional nano-confinement within clay interlayers. Combined NMR and MD study of H2O, Na+, and Cl- interactions with the surface of quartz has direct implications regarding interpretation of sum frequency vibrational spectroscopic experiments for this phase and will be an important reference for future studies. We also used NMR to examine the behavior of K+ and H2O in the interlayer and at the surfaces of the clay minerals hectorite and illite-rich illite-smectite. This the first time K+ dynamics has been characterized spectroscopically in geochemical systems. Preliminary experiments were also performed to evaluate the potential of 75As NMR as a probe of arsenic geochemical behavior. The 75As NMR study used advanced signal enhancement methods, introduced a new data acquisition approach to minimize the time investment in ultra-wide-line NMR experiments, and provides the first evidence of a strong relationship between the chemical shift and structural parameters for this experimentally challenging nucleus. We have also initiated a series of inelastic and quasi-elastic neutron scattering measurements of water dynamics in the interlayers of clays and layered double hydroxides. The objective of these experiments is to probe the correlations of water molecular motions in confined spaces over the scale of times and distances most directly comparable to our MD simulations and on a time scale different than that probed by NMR. This work is being done in collaboration with Drs. C.-K. Loong, N. de Souza, and A.I. Kolesnikov at the Intense Pulsed
Liu Li; Li Yue; Farrar, James M. [Department of Chemistry, University of Rochester, Rochester, New York 14627 (United States)
2005-09-01T23:59:59.000Z
The reactions between O{sup -} and C{sub 2}H{sub 2} have been studied using the crossed-beam technique and density-functional theory (DFT) calculations in the collision energy range from 0.35 to 1.5 eV (34-145 kJ/mol). Both proton transfer and C-O bond formation are observed. The proton transfer channel forming C{sub 2}H{sup -} is the dominant pathway. The center-of-mass flux distributions of the C{sub 2}H{sup -} product ions are highly asymmetric, with maxima close to the velocity and direction of the precursor acetylene beam, characteristic of direct reactions. The reaction quantitatively transforms the entire reaction exothermicity into internal excitation of the products, consistent with mixed energy release in which the proton is transferred in a configuration in which both the breaking and the forming bonds are extended. The C-O bond formation channel producing HC{sub 2}O{sup -} displays a distinctive kinematic picture in which the product distribution switches from predominantly forward scattering with a weak backward peak to sideways scattering as the collision energy increases. At low collision energies, the reaction occurs through an intermediate that lives a significant fraction of a rotational period. The asymmetry in the distribution leads to a lifetime estimate of 600 fs, in reasonable agreement with DFT calculations showing that hydrogen-atom migration is rate limiting. At higher collision energies, the sideways-scattered products arise from repulsive energy release from a bent transition state.
Towards Production FPGA-Accelerated Molecular Dynamics: Progress and Challenges
Herbordt, Martin
dynamics simulation has shown that including on-the-fly neighbor list calculation (particle filtering for this loss. I. INTRODUCTION Molecular dynamics simulation (MD) is a central method in high performance. Herbordt Computer Architecture and Automated Design Laboratory Department of Electrical and Computer
Fluid transport properties by equilibrium molecular dynamics. II. Multicomponent systems
Dysthe, Dag Kristian
Fluid transport properties by equilibrium molecular dynamics. II. Multicomponent systems D. K than 25 years molecular dynamics has been used to study fluid transport properties. Such MD studies and multicenter molecular models.816 d The study of transport properties of certain fluids and classes of fluids
Baird, Matthew David
2012-01-01T23:59:59.000Z
115 3 Testing the Additive Separability of the Teacher ValueDensities Testing the Additive Separability of the TeacherDensities Testing the Additive Separability of the Teacher
Tuscia, Università Degli Studi Della
Dynamics of Different Hydrogen Classes in -lactoglobulin: A Quasielastic Neutron Scattering investigated by means of quasielastic neutron scattering. To discriminate the possibly different dynamical- thods,11-13 molecular dynamics (MD) simulations,14 X-ray crys- tallography,15 and neutron scattering.6
Molecular Dynamics Simulations of Shock-Induced Thermite Reaction Vikas Tomar1,a
Tomar, Vikas
Molecular Dynamics Simulations of Shock-Induced Thermite Reaction Vikas Tomar1,a and Min Zhou1,b 1 Dynamics, Thermite Mixture Abstract. A computational framework for molecular dynamics (MD) simulations of shock-induced reactions in thermite mixtures is developed. The system under study is an Fe2O3+Al
Oberacker, V E
2015-01-01T23:59:59.000Z
In this manuscript we provide an outline of the numerical methods used in implementing the density constrained time-dependent Hartree-Fock (DC-TDHF) method and provide a few examples of its application to nuclear fusion. In this approach, dynamic microscopic calculations are carried out on a three-dimensional lattice and there are no adjustable parameters, the only input is the Skyrme effective NN interaction. After a review of the DC-TDHF theory and the numerical methods, we present results for heavy-ion potentials $V(R)$, coordinate-dependent mass parameters $M(R)$, and precompound excitation energies $E^{*}(R)$ for a variety of heavy-ion reactions. Using fusion barrier penetrabilities, we calculate total fusion cross sections $\\sigma(E_\\mathrm{c.m.})$ for reactions between both stable and neutron-rich nuclei. We also determine capture cross sections for hot fusion reactions leading to the formation of superheavy elements.
V. E. Oberacker; A. S. Umar
2015-02-13T23:59:59.000Z
In this manuscript we provide an outline of the numerical methods used in implementing the density constrained time-dependent Hartree-Fock (DC-TDHF) method and provide a few examples of its application to nuclear fusion. In this approach, dynamic microscopic calculations are carried out on a three-dimensional lattice and there are no adjustable parameters, the only input is the Skyrme effective NN interaction. After a review of the DC-TDHF theory and the numerical methods, we present results for heavy-ion potentials $V(R)$, coordinate-dependent mass parameters $M(R)$, and precompound excitation energies $E^{*}(R)$ for a variety of heavy-ion reactions. Using fusion barrier penetrabilities, we calculate total fusion cross sections $\\sigma(E_\\mathrm{c.m.})$ for reactions between both stable and neutron-rich nuclei. We also determine capture cross sections for hot fusion reactions leading to the formation of superheavy elements.
Nagle, John F.
HIV-1 Tat membrane interactions probed using X-ray and neutron scattering, CD spectroscopy and MD translocation, were provided by wide-angle X-ray scattering (WAXS) and neutron scattering. CD spectroscopy for Neutron Research, 100 Bureau Drive, Stop 6102, Gaithersburg, MD 20899, United States d CHESS, Cornell
Five-Year MD Enrichment Program Application/Plan University of Connecticut School of Medicine
Oliver, Douglas L.
Five-Year MD Enrichment Program Application/Plan University of Connecticut School of Medicine Full_________________________________ Proposed graduation date_________________________ Outline of enrichment plan: (specify date)____________ Please detail on a month-to- month basis your enrichment program (Be specific): Academic Year
Limbic System Page 1 of 10 Srdjan D. Antic, M.D. Limbic system Emotional Experience
Oliver, Douglas L.
function. NMDA-dependent long-term potentiation is a cellular mechanism responsible for fear conditioning.M. is the most studied patient with Urbach-Wiethe disease. After a battery of tests, which included spiders Srdjan D. Antic, M.D. 3 as well as an appetitive (positive) conditioning. Individuals with larger
The Centre for Blood Research Athan Kuliopulos, MD, PhD
Strynadka, Natalie
The Centre for Blood Research Athan Kuliopulos, MD, PhD Director, Hemostasis & Thrombosis coating blood vessel walls rupture and expose collagen, platelets spring into action to form a blood clot, according to the researchers. Compared to other diseases, blood clotting has been very well understood
Weber, David J.
PRIZE $50,000 grants help further research, bring new discoveries to commercial market BALTIMORE, MD will use the funding to develop technology that will aid in the safer delivery of radiation therapy to continue his research on a safer way to deliver radiation therapy." "This is a fantastic opportunity
HOPKINS, UNIVERSITY OF MD, BALTIMORE FACULTY RESEARCHERS WIN 2014 BIOMARYLAND LIFE PRIZES
Weber, David J.
,000 grants help further research, bring new discoveries to commercial market BALTIMORE, MD (February 19, 2014 for her development of a blood test for the early detection of pancreatic cancer. #12;The LIFE prize the funding to develop technology that will aid in the safer delivery of radiation therapy. Previous winners
Boutaba, Raouf
On Tackling Virtual Data Center Embedding Problem Md Golam Rabbani, Rafael Pereira Esteves, Maxim (POSTECH), Pohang 790-784, Korea Abstract--Virtualizing data center networks has been con- sidered center (VDC) resources to their physical counterparts, also known as virtual data center embedding, can
Paris-Sud XI, Université de
On Tackling Virtual Data Center Embedding Problem Md Golam Rabbani, Rafael Esteves, Maxim Podlesny Telecom Bretagne, Institut Mines Telecom, France Abstract--Virtualizing data center networks has been con of virtual data center (VDC) resources to their physical counterparts, also known as virtual data center
Department of Materials Science and Engineering University of Maryland, College Park, MD
Rubloff, Gary W.
Department of Materials Science and Engineering University of Maryland, College Park, MD ENMA 301) and Callister, William D. Jr., Fundamentals of Materials Science and Engineering: An Integrated Approach 3rd Ed of each module will be to introduce the basic materials science principles necessary to understand
Cost Analysis of NEMO Protocol Entities Md. Shohrab Hossain, Mohammed Atiquzzaman, William Ivancic
Atiquzzaman, Mohammed
Cost Analysis of NEMO Protocol Entities Md. Shohrab Hossain, Mohammed Atiquzzaman, William Ivancic to ensure connectivity of the mobile nodes with the Internet. However, there has been no comprehensive cost analysis of mobility protocol entities that considers all possible costs. In this paper, we have developed
Cost Analysis of Mobility Management Entities of Md. Shohrab Hossain, Mohammed Atiquzzaman
Atiquzzaman, Mohammed
Cost Analysis of Mobility Management Entities of SINEMO Md. Shohrab Hossain, Mohammed Atiquzzaman results in higher level of signalling cost on the mobility agents in a mobility protocol. Previous cost analysis on mobility protocols have not considered all possible costs for mobility management, resulting
Advanced age remains an Achilles heel for liver resections. Laurent Sulpice, MD1,3
Paris-Sud XI, Université de
and Karim Boudjema, MD, PhD1,3 1- Service de Chirurgie Hépatobiliaire et Digestive. Centre Hospitalier, Centre Hospitalier Universitaire, Université de Rennes 1, Rennes, France Email : laurent in surgical techniques, perioperative management and postoperative care, LR has become increasingly common
A survey on vehicular cloud computing Md Whaiduzzaman a,n
Buyya, Rajkumar
A survey on vehicular cloud computing Md Whaiduzzaman a,n , Mehdi Sookhak a , Abdullah Gani a , Rajkumar Buyya b a Mobile Cloud Computing Research Lab, Faculty of Computer Science & Information control Intelligent transportation systems Cloud computing Vehicular cloud computing a b s t r a c
Ira Helfand, MD International Physicians for the Prevention of Nuclear War
Robock, Alan
Ira Helfand, MD International Physicians for the Prevention of Nuclear War Physicians for Social Responsibility NUCLEAR FAMINE: A BILLION PEOPLE AT RISK Global Impacts of Limited Nuclear War on Agriculture of studies have shown that a limited, regional nuclear war between India and Pakistan would cause significant
A coupled RISM/MD or MC simulation methodology for solvation free energies
Truong, Thanh N.
A coupled RISM/MD or MC simulation methodology for solvation free energies Holly Freedman, Thanh N methods for determination of solvation free energies. We employ the RISM formulation of solvation free-netted chain equations. We apply this approach to determining free energies of solvation for several small
A Word from the Director Frank S. Pidcock, MD, Vice President of Rehabilitation at Kennedy Krieger
Pevsner, Jonathan
A Word from the Director Frank S. Pidcock, MD, Vice President of Rehabilitation at Kennedy Krieger Institute, Director of the Pediatric Rehabilitation Division in the Department of Physical Medicine & Rehabilitation, Johns Hopkins Hospital In this issue of Neurorehabilitation Updates, we explore disorders
A Word from the Director Frank S. Pidcock, MD, Vice President of Rehabilitation at Kennedy Krieger
Pevsner, Jonathan
A Word from the Director Frank S. Pidcock, MD, Vice President of Rehabilitation at Kennedy Krieger Institute, Director of the Pediatric Rehabilitation Division in the Department of Physical Medicine & Rehabilitation, Johns Hopkins Hospital Kennedy Krieger Institute provides a wide range of services for patients
Hot Water DJ: Saving Energy by Pre-mixing Hot Water Md Anindya Prodhan
Whitehouse, Kamin
Hot Water DJ: Saving Energy by Pre-mixing Hot Water Md Anindya Prodhan Department of Computer University of Virginia whitehouse@virginia.edu Abstract After space heating and cooling, water heating consumption. Current water heating systems waste up to 20% of their energy due to poor insulation in pipes
Enhancing the MD-Strengthening and Designing Scalable Families of One-Way Hash Algorithms
International Association for Cryptologic Research (IACR)
Enhancing the MD-Strengthening and Designing Scalable Families of One-Way Hash Algorithms Neil Kauer Tony Suarez Yuliang Zheng November 1, 2005 Abstract One-way hash algorithms are an indispensable tool in data security. Over the last decade or so a number of one-way hash algorithms have been
District of Columbia, University of the
in the Anacostia River Watershed (MD). Final Report to the DC Water Resources Research Center Dr. Harriette L hydrocarbons (PAHs), 28 polychlorinated biphenyl congeners (PCBs), 6 Aroclors, 21 pesticides, and five metals (Cd, Cr, Cu, Fe, Pb) plus technical chlordane, percent water and percent lipid. This ABM study
Adaptive Regression Testing Strategy: An Empirical Study Md. Junaid Arafeen and Hyunsook Do
Do, Hyunsook
Adaptive Regression Testing Strategy: An Empirical Study Md. Junaid Arafeen and Hyunsook Do in different versions. These factors can affect the costs and benefits of regression testing techniques in different ways, and thus, there may be no single regression testing technique that is the most cost
Semiclassical analysis of quantum dynamics
Siyang Yang
2011-11-15T23:59:59.000Z
Simulating the molecular dynamics (MD) using classical or semi-classical trajectories provides important details for the understanding of many chemical reactions, protein folding, drug design, and solvation effects. MD simulations using trajectories have achieved great successes in the computer simulations of various systems, but it is difficult to incorporate quantum effects in a robust way. Therefore, improving quantum wavepacket dynamics and incorporating nonadiabatic transitions and quantum effects into classical and semi-classical molecular dynamics is critical as well as challenging. In this paper, we present a MD scheme in which a new set of equations of motion (EOM) are proposed to effectively propagate nuclear trajectories while conserving quantum mechanical energy which is critical for describing quantum effects like tunneling. The new quantum EOM is tested on a one-state one-dimensional and a two-state two-dimensional model nonadiabatic systems. The global quantum force experienced by each trajectory promotes energy redistribution among the bundle of trajectories, and thus helps the individual trajectory tunnel through the potential barrier higher than the energy of the trajectory itself. Construction of the new quantum force and EOM also provides a better way to treat the issue of back-reaction in mixed quantum-classical (MQC) methods, i.e. self-consistency between quantum degrees of freedom (DOF) and classical DOF.
Fayer, Michael D.
dynamics MD simulations and quantum mechanical electronic structure calculations are used to investigate agreement. The electronic structure calculations show that the complex is T shaped. The classical potential of the electronic structure calculations. A variety of other features is extracted from the simulations including
Kim, Chansoo, S.M. Massachusetts Institute of Technology
2008-01-01T23:59:59.000Z
A series of Molecular Dynamics (MD) simulations using the GROMACS® package has been performed in this thesis. It is used to mimic and simulate the hydration water in Lysozyme with three different hydration levels (h = 0.3, ...
Multiscale molecular dynamics using the matched interface and boundary method
Geng Weihua [Department of Mathematics, Michigan State University, East Lansing, MI 48824 (United States); Wei, G.W., E-mail: wei@math.msu.ed [Department of Mathematics, Michigan State University, East Lansing, MI 48824 (United States); Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI 48824 (United States)
2011-01-20T23:59:59.000Z
The Poisson-Boltzmann (PB) equation is an established multiscale model for electrostatic analysis of biomolecules and other dielectric systems. PB based molecular dynamics (MD) approach has a potential to tackle large biological systems. Obstacles that hinder the current development of PB based MD methods are concerns in accuracy, stability, efficiency and reliability. The presence of complex solvent-solute interface, geometric singularities and charge singularities leads to challenges in the numerical solution of the PB equation and electrostatic force evaluation in PB based MD methods. Recently, the matched interface and boundary (MIB) method has been utilized to develop the first second order accurate PB solver that is numerically stable in dealing with discontinuous dielectric coefficients, complex geometric singularities and singular source charges. The present work develops the PB based MD approach using the MIB method. New formulation of electrostatic forces is derived to allow the use of sharp molecular surfaces. Accurate reaction field forces are obtained by directly differentiating the electrostatic potential. Dielectric boundary forces are evaluated at the solvent-solute interface using an accurate Cartesian-grid surface integration method. The electrostatic forces located at reentrant surfaces are appropriately assigned to related atoms. Extensive numerical tests are carried out to validate the accuracy and stability of the present electrostatic force calculation. The new PB based MD method is implemented in conjunction with the AMBER package. MIB based MD simulations of biomolecules are demonstrated via a few example systems.
Laboratory Density Functionals
B. G. Giraud
2007-07-26T23:59:59.000Z
We compare several definitions of the density of a self-bound system, such as a nucleus, in relation with its center-of-mass zero-point motion. A trivial deconvolution relates the internal density to the density defined in the laboratory frame. This result is useful for the practical definition of density functionals.
Control-volume representation of molecular dynamics
E. R. Smith; D. M. Heyes; D. Dini; T. A. Zaki
2012-05-24T23:59:59.000Z
A Molecular Dynamics (MD) parallel to the Control Volume (CV) formulation of fluid mechanics is developed by integrating the formulas of Irving and Kirkwood, J. Chem. Phys. 18, 817 (1950) over a finite cubic volume of molecular dimensions. The Lagrangian molecular system is expressed in terms of an Eulerian CV, which yields an equivalent to Reynolds' Transport Theorem for the discrete system. This approach casts the dynamics of the molecular system into a form that can be readily compared to the continuum equations. The MD equations of motion are reinterpreted in terms of a Lagrangian-to-Control-Volume (\\CV) conversion function $\\vartheta_{i}$, for each molecule $i$. The \\CV function and its spatial derivatives are used to express fluxes and relevant forces across the control surfaces. The relationship between the local pressures computed using the Volume Average (VA, Lutsko, J. Appl. Phys 64, 1152 (1988)) techniques and the Method of Planes (MOP, Todd et al, Phys. Rev. E 52, 1627 (1995)) emerges naturally from the treatment. Numerical experiments using the MD CV method are reported for equilibrium and non-equilibrium (start-up Couette flow) model liquids, which demonstrate the advantages of the formulation. The CV formulation of the MD is shown to be exactly conservative, and is therefore ideally suited to obtain macroscopic properties from a discrete system.
Automatic Search of Di#erential Path in MD4 PierreAlain Fouque, Gatan Leurent, Phong Nguyen
International Association for Cryptologic Research (IACR)
Automatic Search of Di#erential Path in MD4 PierreAlain Fouque, Gaëtan Leurent, Phong Nguyen found ``by hand''. In this paper, we present an algorithm which automatically finds suitable di
National Nuclear Security Administration (NNSA)
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:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5 TablesExports to3,1,50022,3,,0,,6,1,Separation 23Tribal EnergyCatalytic Coby Mods 002, 006, 020, 029, 0049, 0065, 0084, 0091, 0106)LLaboratory6. S
Southern California, University of
films that form on aluminum and aluminum alloys in air protect the surface against further oxidationMolecular dynamics simulations of the nano-scale room-temperature oxidation of aluminum single Abstract The oxidation of aluminum single crystals is studied using molecular dynamics (MD) simulations
EFFICIENT PARTICLE-PAIR FILTERING FOR ACCELERATION OF MOLECULAR DYNAMICS SIMULATION
Herbordt, Martin
EFFICIENT PARTICLE-PAIR FILTERING FOR ACCELERATION OF MOLECULAR DYNAMICS SIMULATION Matt Chiu ABSTRACT The acceleration of molecular dynamics (MD) simulations using high performance reconfigurable: determining the short-range force between particle pairs. In particular, we present the first FPGA study
Kurnikova, Maria
and the metal cation. Conductivity measure- ments and ab initio electronic structure calculations are used structure and the solute dynamics occur for ionic solute molecules. Both experimental4-10 and theoretical11 of experimental studies, ab initio electronic struc- ture, and molecular dynamics (MD) simulation is used
Brenner, Donald W.
binding electronic structure calculations, pertur- bation models, and quantum-classical Hamiltonians [6 depends on the degree of approximation used in solving the electronic structure problem, which can add-scale molecular dynamics (MD) simulation is not to model electron dynamics, but rather to numerically solve
Instabilities in the Nuclear Energy Density Functional
M. Kortelainen; T. Lesinski
2010-02-05T23:59:59.000Z
In the field of Energy Density Functionals (EDF) used in nuclear structure and dynamics, one of the unsolved issues is the stability of the functional. Numerical issues aside, some EDFs are unstable with respect to particular perturbations of the nuclear ground-state density. The aim of this contribution is to raise questions about the origin and nature of these instabilities, the techniques used to diagnose and prevent them, and the domain of density functions in which one should expect a nuclear EDF to be stable.
Herbordt, Martin
2005-01-01T23:59:59.000Z
(2005) 1 ACCELERATING MOLECULAR DYNAMICS SIMULATIONS WITH CONFIGURABLE CIRCUITS Yongfeng Gu Tom Van-space parameter for MD practitioners. 2. MOLECULAR DYNAMICS OVERVIEW Molecular Dynamics simulations generallyCourt Martin C. Herbordt Department of Electrical and Computer Engineering Boston University, Boston, MA 02215
Adding quantum effects to the semi-classical molecular dynamics simulations
Yang, Siyang
2011-01-01T23:59:59.000Z
Simulating the molecular dynamics (MD) using classical or semi-classical trajectories provides important details for the understanding of many chemical reactions, protein folding, drug design, and solvation effects. MD simulations using trajectories have achieved great successes in the computer simulations of various systems, but it is difficult to incorporate quantum effects in a robust way. Therefore, improving quantum wavepacket dynamics and incorporating nonadiabatic transitions and quantum effects into classical and semi-classical molecular dynamics is critical as well as challenging. In this paper, we present a MD scheme in which a new set of equations of motion (EOM) are proposed to effectively propagate nuclear trajectories while conserving quantum mechanical energy which is critical for describing quantum effects like tunneling. The new quantum EOM is tested on a one-state one-dimensional and a two-state two-dimensional model nonadiabatic systems. The global quantum force experienced by each trajecto...
Tong, Xiao-Min; Chu, Shih-I
1998-01-01T23:59:59.000Z
We present a self-interaction-free time-dependent density-functional theory (TDDFT) for nonperturbative treatment of multiphoton processes of many-electron atomic systems in intense laser fields. The theory is based on the ...
Chu, Xi; Chu, Shih-I
2001-11-14T23:59:59.000Z
We present a time-dependent density-functional theory (TDDFT) with proper asymptotic long-range potential for nonperturbative treatment of multiphoton processes of many-electron molecular systems in intense laser fields. ...
Chu, Shih-I; Telnov, Dmitry A.
2009-04-03T23:59:59.000Z
We present a time-dependent density-functional-theory approach for the ab initio study of the effect of correlated multielectron responses on the multiphoton ionization (MPI) of diatomic molecules N2, O2, and F2 in intense ...
Susmita Roy; Subramanian Yashonath; Biman Bagchi
2015-01-08T23:59:59.000Z
A self-consistent mode coupling theory (MCT) with microscopic inputs of equilibrium pair correlation functions is developed to analyze electrolyte dynamics. We apply the theory to calculate concentration dependence of (i) time dependent ion diffusion, (ii) dynamic structure factor of the constituent ions, and (iii) ion solvation dynamics in electrolyte solution. Brownian dynamics (BD) with implicit water molecules and molecular dynamics (MD) method with explicit water are used to check the theoretical predictions. The time dependence of ionic self-diffusion coefficient and the corresponding dynamic structure factor evaluated from our MCT approach show quantitative agreement with early experimental and present Brownian dynamic simulation results. With increasing concentration, the dispersion of electrolyte friction is found to occur at increasingly higher frequency, due to the faster relaxation of the ion atmosphere. The wave number dependence of total dynamic structure factor F(k,t), exhibits markedly different relaxation dynamics at different length scales. At small wave numbers, we find the emergence of a step-like relaxation, indicating the presence of both fast and slow time scales in the system. Such behaviour allows an intriguing analogy with temperature dependent relaxation dynamics of supercooled liquids. We find that solvation dynamics of a tagged ion exhibits a power law decay at long times- the decay can also be fitted to a stretched exponential form. The emergence of the power law in solvation dynamics has been tested by carrying out long Brownian dynamics simulations with varying ionic concentrations. This solvation time correlation and ion-ion dynamic structure factor indeed exhibits highly interesting, non-trivial dynamical behaviour at intermediate to longer times that require further experimental and theoretical studies.
Lula, J.W.
1982-01-01T23:59:59.000Z
A formulation for low density syntactic foam desiccant, using a polyimide resin binder, glass microbubble filler, and molecular sieve desiccant powder has been developed. The formulation may be modified easily to meet specific part requirements such as density and desired moisture pickup. Some parts can be molded to size.
Tyler N. Shendruk; Martin Bertrand; James L. Harden; Gary W. Slater; Hendrick W. de Haan
2014-08-01T23:59:59.000Z
Given the ubiquity of depletion effects in biological and other soft matter systems, it is desirable to have coarse-grained Molecular Dynamics simulation approaches appropriate for the study of complex systems. This paper examines the use of two common truncated Lennard-Jones (WCA) potentials to describe a pair of colloidal particles in a thermal bath of depletants. The shifted-WCA model is the steeper of the two repulsive potentials considered, while the combinatorial-WCA model is the softer. It is found that the depletion-induced well depth for the combinatorial-WCA model is significantly deeper than the shifted-WCA model because the resulting overlap of the colloids yields extra accessible volume for depletants. For both shifted- and combinatorial-WCA simulations, the second virial coefficients and pair potentials between colloids are demonstrated to be well approximated by the Morphometric Thermodynamics (MT) model. This agreement suggests that the presence of depletants can be accurately modelled in MD simulations by implicitly including them through simple, analytical MT forms for depletion-induced interactions. Although both WCA potentials are found to be effective generic coarse-grained simulation approaches for studying depletion effects in complicated soft matter systems, combinatorial-WCA is the more efficient approach as depletion effects are enhanced at lower depletant densities. The findings indicate that for soft matter systems that are better modelled by potentials with some compressibility, predictions from hard-sphere systems could greatly underestimate the magnitude of depletion effects at a given depletant density.
Three-phase permeabilities and other characteristics of 260-mD fired Berea
Maloney, D.; Brinkmeyer, A.
1992-04-01T23:59:59.000Z
A laboratory investigation was conducted to determine relative permeabilities and other characteristics of a 260-mD fired Berea sandstone. The mineralogical and physical characteristics of the sample were characterized by XRD tests, thin section analyses, mercury injection tests, and centrifuge capillary pressure and wettability tests. Two-phase oil/water relative permeabilities were measured under several stress conditions. Resistivity characteristics of the sample were also evaluated during several of the oil/water tests. Oil/gas and gas/water relative permeabilities were measured during steady-state tests. Three-phase steady-state oil/gas/water tests were performed for six DDI saturation trajectories (decreasing brine and oil saturations, increasing gas saturation) in which the sample was not cleaned between saturation trajectories.
Chen, Wei-Ren [ORNL; Do, Changwoo [ORNL; Egami, T [University of Tennessee, Knoxville (UTK); Hong, Kunlun [ORNL; Li, Xin [ORNL; Liu, Emily [Rensselaer Polytechnic Institute (RPI); Liu, Yun [National Institute of Standards and Technology (NIST); Porcar, L. [National Institute of Standards and Technology (NIST); Smith, Gregory Scott [ORNL; Smith, Sean C [ORNL; Wu, Bin [ORNL
2012-01-01T23:59:59.000Z
Atomistic molecular dynamics (MD) simulations and contrast variation small angle neutron scattering (SANS) technique have been used to investigate the generation-5 (G5) polyelectrolyte polyamidoamine (PAMAM) starburst dendrimer with respect to its conformational dependence on counterion behavior at different levels of molecular charge. Satisfactory agreement is seen between the simulated results, such as the excess intra-dendrimer scattering length density (SLD) distribution and hydration level, and their experimental counterparts. The conformational evolution of charged dendrimer appears to be highly dependent on the association behavior of counterion. We explore the nature of the distribution of counterions around charged amines and qualitatively account for its sensitivity to the counterion valency on the difference of excess free energy. Moreover, via extending the concept of electrical double layer for compact charged colloids, we define an effective radius of charged dendrimer based on the spatial distribution of counterions in its vicinity. Within the same framework, the correlation between the strength of intra-dendrimer electrostatic repulsion and counterion valency and dynamics is also addressed.
Recovering position-dependent diffusion from biased molecular dynamics simulations
Ljubeti?, Ajasja; Urban?i?, Iztok; Štrancar, Janez, E-mail: janez.strancar@ijs.si [Laboratory of Biophysics, Condensed Matter Physics Department, “Jožef Stefan” Institute, 1000 Ljubljana (Slovenia)] [Laboratory of Biophysics, Condensed Matter Physics Department, “Jožef Stefan” Institute, 1000 Ljubljana (Slovenia)
2014-02-28T23:59:59.000Z
All atom molecular dynamics (MD) models provide valuable insight into the dynamics of biophysical systems, but are limited in size or length by the high computational demands. The latter can be reduced by simulating long term diffusive dynamics (also known as Langevin dynamics or Brownian motion) of the most interesting and important user-defined parts of the studied system, termed collective variables (colvars). A few hundred nanosecond-long biased MD trajectory can therefore be extended to millisecond lengths in the colvars subspace at a very small additional computational cost. In this work, we develop a method for determining multidimensional anisotropic position- and timescale-dependent diffusion coefficients (D) by analysing the changes of colvars in an existing MD trajectory. As a test case, we obtained D for dihedral angles of the alanine dipeptide. An open source Mathematica{sup ®} package, capable of determining and visualizing D in one or two dimensions, is available at https://github.com/lbf-ijs/DiffusiveDynamics . Given known free energy and D, the package can also generate diffusive trajectories.
Modeling ramp compression experiments using large-scale molecular dynamics simulation.
Mattsson, Thomas Kjell Rene; Desjarlais, Michael Paul; Grest, Gary Stephen; Templeton, Jeremy Alan; Thompson, Aidan Patrick; Jones, Reese E.; Zimmerman, Jonathan A.; Baskes, Michael I. (University of California, San Diego); Winey, J. Michael (Washington State University); Gupta, Yogendra Mohan (Washington State University); Lane, J. Matthew D.; Ditmire, Todd (University of Texas at Austin); Quevedo, Hernan J. (University of Texas at Austin)
2011-10-01T23:59:59.000Z
Molecular dynamics simulation (MD) is an invaluable tool for studying problems sensitive to atomscale physics such as structural transitions, discontinuous interfaces, non-equilibrium dynamics, and elastic-plastic deformation. In order to apply this method to modeling of ramp-compression experiments, several challenges must be overcome: accuracy of interatomic potentials, length- and time-scales, and extraction of continuum quantities. We have completed a 3 year LDRD project with the goal of developing molecular dynamics simulation capabilities for modeling the response of materials to ramp compression. The techniques we have developed fall in to three categories (i) molecular dynamics methods (ii) interatomic potentials (iii) calculation of continuum variables. Highlights include the development of an accurate interatomic potential describing shock-melting of Beryllium, a scaling technique for modeling slow ramp compression experiments using fast ramp MD simulations, and a technique for extracting plastic strain from MD simulations. All of these methods have been implemented in Sandia's LAMMPS MD code, ensuring their widespread availability to dynamic materials research at Sandia and elsewhere.
Cafarella, Michael J.
FRAppE: Detecting Malicious Facebook Applications Md Sazzadur Rahman, Ting-Kai Huang, Harsha V for the popularity and addictiveness of Facebook. Unfortu- nately, hackers have realized the potential of using apps and campaigns. In this paper, we ask the question: given a Facebook application, can we determine
Alamethicin in lipid bilayers: Combined use of X-ray scattering and MD simulations Jianjun Pan a
Nagle, John F.
Alamethicin in lipid bilayers: Combined use of X-ray scattering and MD simulations Jianjun Pan of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA d Canadian Neutron Beam Centre:1PC with varying amounts of alamethicin (Alm). We combine the use of X-ray diffuse scattering
Lung mast cells are a source of secreted phospholipases A2 Massimo Triggiani, MD, PhD,a
Gelb, Michael
Lung mast cells are a source of secreted phospholipases A2 Massimo Triggiani, MD, PhD,a Giorgio and to examine the expression and release of sPLA2s from primary human lung mast cells (HLMCs). Methods: sPLA2 of asthmatic patients. (J Allergy Clin Immunol 2009;124:558-65.) Key words: Lung mast cells, secreted
Elliott, James
to nanotube stability. James A. Elliott,1 Jan K.W. Sandler,1 Alan H. Windle,1 Robert J. Young,2 and Milo S. P. Shaffer3 1 Department of Materials Science and Metallurgy University of Cambridge Pembroke Street
Wucher, Andreas
medium potential A. Wuchera) Fachbereich Physik, University of Kaiserslautern, 67653 Kaiserslautern may eventually form a cluster on their way from a solid to a gas phase environment far away from-body interaction potentials which, for the case of metals, were constructed by the so- called embedded-atom method
J. R. Stone
2013-02-11T23:59:59.000Z
The microscopic composition and properties of matter at super-saturation densities have been the subject of intense investigation for decades. The scarcity of experimental and observational data has lead to the necessary reliance on theoretical models. However, there remains great uncertainty in these models, which, of necessity, have to go beyond the over-simple assumption that high density matter consists only of nucleons and leptons. Heavy strange baryons, mesons and quark matter in different forms and phases have to be included to fulfil basic requirements of fundamental laws of physics. In this review the latest developments in construction of the Equation of State (EoS) of high-density matter at zero and finite temperature assuming different composition of the matter are surveyed. Critical comparison of model EoS with available observational data on neutron stars, including gravitational masses, radii and cooling patterns is presented. The effect of changing rotational frequency on the composition of neutron stars during their lifetime is demonstrated. Compatibility of EoS of high-density, low temperature compact objects and low density, high temperature matter created in heavy-ion collisions is discussed.
Redshift Evolution of Galaxy Cluster Densities
R. G. Carlberg; S. L. Morris; H. K. C. Yee; E. Ellingson
1997-01-20T23:59:59.000Z
The number of rich galaxy clusters per unit volume is a strong function of Omega, the cosmological density parameter, and sigma_8, the linear extrapolation to z=0 of the density contrast in 8/h Mpc spheres. The CNOC cluster redshift survey provides a sample of clusters whose average mass profiles are accurately known, which enables a secure association between cluster numbers and the filtered density perturbation spectrum. We select from the CNOC cluster survey those EMSS clusters with bolometric L_x>=10^45 erg/s and a velocity dispersion exceeding 800 km/s in the redshift ranges 0.18-0.35 and 0.35-0.55. We compare the number density of these subsamples with similar samples at both high and low redshift. Using the Press-Schechter formalism and CDM style structure models, the density data are described with sigma_8=0.75+/-0.1 and Omega=0.4+/-0.2 (90% confidence). The cluster dynamical analysis gives Omega=0.2+/-0.1$ for which sigma_8=0.95+/-0.1 (90% confidence). The predicted cluster density evolution in an \\Omega=1 CDM model exceeds that observed by more than an order of magnitude.
Visualization of electronic density
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Grosso, Bastien; Cooper, Valentino R; Pine, Polina; Hashibon, Adham; Yaish, Yuval; Adler, Joan
2015-01-01T23:59:59.000Z
The spatial volume occupied by an atom depends on its electronic density. Although this density can only be evaluated exactly for hydrogen-like atoms, there are many excellent algorithms and packages to calculate it numerically for other materials. Three-dimensional visualization of charge density is challenging, especially when several molecular/atomic levels are intertwined in space. In this paper, we explore several approaches to this, including the extension of an analglyphic stereo visualization application based on the AViz package for hydrogen atoms and simple molecules to larger structures such as nanotubes. We will describe motivations and potential applications of these tools for answeringmore »interesting physical questions about nanotube properties.« less
Lu, Benzhuo
and Applied Physics, University of Science and Technology of China, Hefei, China 2 Center for Biomedical and compared with those obtained from 500-ps molecu- lar dynamics (MD) simulation with explicit water and a 500 of the BEM with macromol- ecule with "pinched" surface regions that are often found in deep crevices
Molecular dynamics simulations of gold-catalyzed growth of silicon bulk crystals and nanowires
Cai, Wei
ARTICLES Molecular dynamics simulations of gold-catalyzed growth of silicon bulk crystals of the orientation, yield, and quality of the NWs. Much of the studies on the VLS growth mechanism have been focused. In this article, we present the first set of MD simu- lations of NW growth using this AuSi potential model
Grover, William H.
We have used a microfluidic mass sensor to measure the density of single living cells. By weighing each cell in two fluids of different densities, our technique measures the single-cell mass, volume, and density of ...
Multiple density layered insulator
Alger, T.W.
1994-09-06T23:59:59.000Z
A multiple density layered insulator for use with a laser is disclosed which provides at least two different insulation materials for a laser discharge tube, where the two insulation materials have different thermoconductivities. The multiple layer insulation materials provide for improved thermoconductivity capability for improved laser operation. 4 figs.
Vranjes, J
2015-01-01T23:59:59.000Z
Inhomogeneous plasmas and fluids contain energy stored in inhomogeneity and they naturally tend to relax into lower energy states by developing instabilities or by diffusion. But the actual amount of energy in such inhomogeneities has remained unknown. In the present work the amount of energy stored in a density gradient is calculated for several specific density profiles in a cylindric configuration. This is of practical importance for drift wave instability in various plasmas, and in particular in its application in models dealing with the heating of solar corona because the instability is accompanied with stochastic heating, so the energy contained in inhomogeneity is effectively transformed into heat. It is shown that even for a rather moderate increase of the density at the axis in magnetic structures in the corona by a factor 1.5 or 3, the amount of excess energy per unit volume stored in such a density gradient becomes several orders of magnitude greater than the amount of total energy losses per unit ...
Kinetic distance and kinetic maps from molecular dynamics simulation
Noe, Frank
2015-01-01T23:59:59.000Z
Characterizing macromolecular kinetics from molecular dynamics (MD) simulations requires a distance metric that can distinguish slowly-interconverting states. Here we build upon diffusion map theory and define a kinetic distance for irreducible Markov processes that quantifies how slowly molecular conformations interconvert. The kinetic distance can be computed given a model that approximates the eigenvalues and eigenvectors (reaction coordinates) of the MD Markov operator. Here we employ the time-lagged independent component analysis (TICA). The TICA components can be scaled to provide a kinetic map in which the Euclidean distance corresponds to the kinetic distance. As a result, the question of how many TICA dimensions should be kept in a dimensionality reduction approach becomes obsolete, and one parameter less needs to be specified in the kinetic model construction. We demonstrate the approach using TICA and Markov state model (MSM) analyses for illustrative models, protein conformation dynamics in bovine...
Hulet, E.K.; Wild, J.F.; Lougheed, R.W.; Baisden, P.A.; Dougan, R.J.; Mustafa, M.G.
1980-10-01T23:59:59.000Z
The fragment energies of about 725 coincidence events have now been observed in the spontaneous fission (SF) decay of 105-min /sup 259/Md since its discovery in 1977. The fission of /sup 259/Md is characterized by a symmetric mass distribution, similar to those of /sup 258/Fm and /sup 259/Fm, but with a broad total kinetic energy (anti TKE) distribution which peaks at about 195 MeV, in contrast to those of /sup 258/Fm and /sup 259/Fm, for which the anti TKE is about 240 MeV. This kinetic energy deficit, approx. 40 MeV, has been postulated to be due to the emission of hydrogen-like particles by /sup 259/Md at the scission point in a large fraction of the fissions, leaving the residual fissioning nucleus with 100 protons. The residual nucleus would then be able to divide into two ultrastable tin-like fission fragments, but with less kinetic energy than that observed in the SF of /sup 258/Fm and /sup 259/Fm, because of binding-energy losses and a reduction in the Coulomb repulsion of the major fragments. To test this hypothesis, counter-telescope experiments aimed at detecting and identifying these light particles were performed. In 439 SF events 3 + 3 protons of the appropriate energy were observed, too few to account for the kinetic energy deficit in the fission of /sup 259/Md. There seems to be no explanation for this problem within the framework of current fission theory. These results are discussed along with preliminary measurements of light-particle emission in the SF of /sup 256/Fm. 5 figures.
Louis Reese; Anna Melbinger; Erwin Frey
2015-05-05T23:59:59.000Z
Here we study a driven lattice gas model for microtubule depolymerizing molecular motors, where traffic jams of motors induce stochastic switching between microtubule growth and shrinkage. We term this phenomenon \\enquote{traffic dynamic instability} because it is reminiscent of microtubule dynamic instability [T. Mitchison and M. Kirschner, Nature 312, 237 (1984)]. The intermittent dynamics of growth and shrinking emerges from the interplay between the arrival of motors at the microtubule tip, motor induced depolymerization, and motor detachment from the tip. The switching dynamics correlates with low and high motor density on the lattice. This leads to an effectively bistable particle density in the system. A refined domain wall theory predicts this transient appearance of different phases in the system. The theoretical results are supported by stochastic simulations.
Reese, Louis; Frey, Erwin
2015-01-01T23:59:59.000Z
Here we study a driven lattice gas model for microtubule depolymerizing molecular motors, where traffic jams of motors induce stochastic switching between microtubule growth and shrinkage. We term this phenomenon \\enquote{traffic dynamic instability} because it is reminiscent of microtubule dynamic instability [T. Mitchison and M. Kirschner, Nature 312, 237 (1984)]. The intermittent dynamics of growth and shrinking emerges from the interplay between the arrival of motors at the microtubule tip, motor induced depolymerization, and motor detachment from the tip. The switching dynamics correlates with low and high motor density on the lattice. This leads to an effectively bistable particle density in the system. A refined domain wall theory predicts this transient appearance of different phases in the system. The theoretical results are supported by stochastic simulations.
Molecular dynamics simulation of chains mobility in polyethylene crystal
V. I. Sultanov; V. V. Atrazhev; D. V. Dmitriev; S. F. Burlatsky
2014-01-17T23:59:59.000Z
The mobility of polymer chains in perfect polyethylene (PE) crystal was calculated as a function of temperature and chain length through Molecular dynamics (MD) in united atom approximation. The results demonstrate that the chain mobility drastically increases in the vicinity of the phase transition from the orthorhombic to quasi-hexagonal phase. In the quasi-hexagonal phase, the chain mobility is almost independent on temperature and inversely proportional to the chain length.
.Belter@noaa.gov), NOAA Central Library, LAC Group, Silver Spring, MD Dian J. Seidel, NOAA Air Resources Laboratory the publication trends, geo- graphic distribution, intellectual structure, and col- laborative network
On an open question about the complexity of a dynamic spectrum ...
2014-12-02T23:59:59.000Z
the users dynamically adjust their transmit power spectral densities over it. ... the performance of the whole system, a Dynamic Spectrum Management (DSM).
Nuclear Physics A 770 (2006) 131 Relativistic nuclear energy density functional
Weise, Wolfram
2006-01-01T23:59:59.000Z
Nuclear Physics A 770 (2006) 131 Relativistic nuclear energy density functional constrained by low 10 February 2006 Available online 3 March 2006 Abstract A relativistic nuclear energy density Keywords: Relativistic mean field; Density functional theory; Nuclear structure; Chiral dynamics; QCD sum
A NEW RECIPE FOR OBTAINING CENTRAL VOLUME DENSITIES OF PRESTELLAR CORES FROM SIZE MEASUREMENTS
Tassis, Konstantinos; Yorke, Harold W. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
2011-07-10T23:59:59.000Z
We propose a simple analytical method for estimating the central volume density of prestellar molecular cloud cores from their column density profiles. Prestellar cores feature a flat central part of the column density and volume density profiles of the same size indicating the existence of a uniform-density inner region. The size of this region is set by the thermal pressure force which depends only on the central volume density and temperature of the core, and can provide a direct measurement of the central volume density. Thus, a simple length measurement can immediately yield a central density estimate independent of any dynamical model for the core and without the need for fitting. Using the radius at which the column density is 90% of the central value as an estimate of the size of the flat inner part of the column density profile yields an estimate of the central volume density within a factor of two for well-resolved cores.
Liu Li; Li Yue; Farrar, James M. [Department of Chemistry, University of Rochester, Rochester, New York 14627 (United States)
2006-03-28T23:59:59.000Z
The proton transfer reaction between OH{sup -} and C{sub 2}H{sub 2}, the sole reactive process observed over the collision energy range from 0.37 to 1.40 eV, has been studied using the crossed beam technique and density-functional theory (DFT) calculations. The center of mass flux distributions of the product C{sub 2}H{sup -} ions at three different energies are highly asymmetric, characteristic of a direct process occurring on a time scale much less than a rotational period of any transient intermediate. The maxima in the flux distributions correspond to product velocities and directions close to those of the precursor acetylene reactants. The reaction quantitatively transforms the entire exothermicity into internal excitation of the products, consistent with an energy release motif in which the proton is transferred early, in a configuration in which the forming bond is extended. This picture is supported by DFT calculations showing that the first electrostatically bound intermediate on the reaction pathway is the productlike C{sub 2}H{sup -}{center_dot}H{sub 2}O species. Most of the incremental translational energy in the two higher collision energy experiments appears in product translational energy, and provides an example of induced repulsive energy release characteristic of the heavy+light-heavy mass combination.
M. V. Garzelli
2008-10-13T23:59:59.000Z
The overlapping stage of heavy-ion reactions can be simulated by dynamical microscopical models, such as those built on the basis of the Molecular Dynamics (MD) approaches, allowing to study the fragment formation process. The present performances of the Quantum MD (QMD) code developed at the University of Milano are discussed, showing results concerning fragment and particle production at bombarding energies up to $\\lsim$ 700 MeV/A, as well as a preliminary analysis on the isoscaling behaviour of isotopic yield ratios for reactions with isospin composition N/Z in the (1 - 1.2) range, at a 45 MeV/A bombarding energy.
High Energy Density Capacitors
None
2010-07-01T23:59:59.000Z
BEEST Project: Recapping is developing a capacitor that could rival the energy storage potential and price of today’s best EV batteries. When power is needed, the capacitor rapidly releases its stored energy, similar to lightning being discharged from a cloud. Capacitors are an ideal substitute for batteries if their energy storage capacity can be improved. Recapping is addressing storage capacity by experimenting with the material that separates the positive and negative electrodes of its capacitors. These separators could significantly improve the energy density of electrochemical devices.
Simulations of liquid ribidium expanded to the critical density
Ross, M; Yang, L H; Pilgrim, W
2006-05-16T23:59:59.000Z
Quantum molecular dynamic simulations were used to examine the change in atomic and electronic structure in liquid rubidium along its liquid-vapor coexistence curve. Starting from the liquid at the triple point, with increasing expansion we observe a continuous increase in the electron localization leading to ion clustering near the metal-nonmetal transition at about twice the critical density, in agreement with electrical measurements, and to the presence of dimers near and below the critical density.
Holographic energy density in the Brans-Dicke teory
Hungsoo Kim; H. W. Lee; Y. S. Myung
2005-01-15T23:59:59.000Z
We study cosmological applications of the holographic energy density. Considering the holographic energy density as a dynamical cosmological constant, we need the Brans-Dicke theory as a dynamical framework instead of general relativity. In this case we use the Bianchi identity as a consistency relation to obtain physical solutions. It is shown that the future event horizon as the IR cutoff provides the dark energy in the Brans-Dicke theory. Furthermore the role of the Brans-Dicke scalar is clarified in the dark energy-dominated universe by calculating its equation of state.
Low density microcellular foams
LeMay, J.D.
1991-11-19T23:59:59.000Z
Disclosed is a process of producing microcellular foam which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 [mu]m is produced. Also disclosed are the foams produced by the process. 8 figures.
Low density microcellular foams
LeMay, James D. (Castro Valley, CA)
1991-01-01T23:59:59.000Z
Disclosed is a process of producing microcellular foam which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 .mu.m is produced. Also disclosed are the foams produced by the process.
Low density microcellular foams
LeMay, James D. (Castro Valley, CA)
1992-01-01T23:59:59.000Z
Disclosed is a process of producing microcellular from which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 .mu.m is produced. Also disclosed are the foams produced by the process.
Low density microcellular foams
Aubert, James H. (Albuquerque, NM); Clough, Roger L. (Albuquerque, NM); Curro, John G. (Placitas, NM); Quintana, Carlos A. (Albuquerque, NM); Russick, Edward M. (Albuquerque, NM); Shaw, Montgomery T. (Mansfield Center, CT)
1987-01-01T23:59:59.000Z
Low density, microporous polymer foams are provided by a process which comprises forming a solution of polymer and a suitable solvent followed by rapid cooling of the solution to form a phase-separated system and freeze the phase-separated system. The phase-separated system comprises a polymer phase and a solvent phase, each of which is substantially continuous within the other. The morphology of the polymer phase prior to and subsequent to freezing determine the morphology of the resultant foam. Both isotropic and anisotropic foams can be produced. If isotropic foams are produced, the polymer and solvent are tailored such that the solution spontaneously phase-separates prior to the point at which any component freezes. The morphology of the resultant polymer phase determines the morphology of the resultant foam and the morphology of the polymer phase is retained by cooling the system at a rate sufficient to freeze one or both components of the system before a change in morphology can occur. Anisotropic foams are produced by forming a solution of polymer and solvent that will not phase separate prior to freezing of one or both components of the solution. In such a process, the solvent typically freezes before phase separation occurs. The morphology of the resultant frozen two-phase system determines the morphology of the resultant foam. The process involves subjecting the solution to essentially one-dimensional cooling. Means for subjecting such a solvent to one-dimensional cooling are also provided. Foams having a density of less than 0.1 g/cc and a uniform cell size of less than 10 .mu.m and a volume such that the foams have a length greater than 1 cm are provided.
Low density microcellular foams
Aubert, J.H.; Clough, R.L.; Curro, J.G.; Quintana, C.A.; Russick, E.M.; Shaw, M.T.
1985-10-02T23:59:59.000Z
Low density, microporous polymer foams are provided by a process which comprises forming a solution of polymer and a suitable solvent followed by rapid cooling of the solution to form a phase-separated system and freeze the phase-separated system. The phase-separated system comprises a polymer phase and a solvent phase, each of which is substantially continuous within the other. The morphology of the polymer phase prior to and subsequent to freezing determine the morphology of the resultant foam. Both isotropic and anisotropic foams can be produced. If isotropic foams are produced, the polymer and solvent are tailored such that the solution spontaneously phase-separates prior to the point at which any component freezes. The morphology of the resultant polymer phase determines the morphology of the reusltant foam and the morphology of the polymer phase is retained by cooling the system at a rate sufficient to freeze one or both components of the system before a change in morphology can occur. Anisotropic foams are produced by forming a solution of polymer and solvent that will not phase separate prior to freezing of one or both components of the solution. In such a process, the solvent typically freezes before phase separation occurs. The morphology of the resultant frozen two-phase system determines the morphology of the resultant foam. The process involves subjecting the solution to essentially one-dimensional cooling. Foams having a density of less than 0.1 g/cc and a uniform cell size of less than 10 ..mu..m and a volume such that the foams have a length greater than 1 cm are provided.
Kinetics of Surface Enrichment: A Molecular Dynamics Study
Prabhat K. Jaiswal; Sanjay Puri; Subir K. Das
2010-11-29T23:59:59.000Z
We use molecular dynamics (MD) to study the kinetics of surface enrichment (SE) in a stable homogeneous mixture (AB), placed in contact with a surface which preferentially attracts A. The SE profiles show a characteristic double-exponential behavior with two length scales: \\xi_-, which rapidly saturates to its equilibrium value, and \\xi_+, which diverges as a power-law with time (\\xi_+ \\sim t^\\theta). We find that hydrodynamic effects result in a crossover of the growth exponent from \\theta \\simeq 0.5 to \\theta \\simeq 1.0. There is also a corresponding crossover in the growth dynamics of the SE-layer thickness.
Vortex dynamics in 4 Banavara N. Shashikanth
Shashikanth, Banavara N.
Vortex dynamics in 4 Banavara N. Shashikanth Citation: J. Math. Phys. 53, 013103 (2012); doi: 10 OF MATHEMATICAL PHYSICS 53, 013103 (2012) Vortex dynamics in R4 Banavara N. Shashikantha) Mechanical and Aerospace dynamics of Euler's equations for a constant density fluid flow in R4 is studied. Most of the paper focuses
Molecular Dynamics Simulations of Solutions at Constant Chemical Potential
Perego, Claudio; Parrinello, Michele
2015-01-01T23:59:59.000Z
Molecular Dynamics studies of chemical processes in solution are of great value in a wide spectrum of applications, that range from nano-technology to pharmaceutical chemistry. However, these calculations are affected by severe finite-size effects, such as the solution being depleted as the chemical process proceeds, that influence the outcome of the simulations. To overcome these limitations, one must allow the system to exchange molecules with a macroscopic reservoir, thus sampling a Grand-Canonical ensemble. Despite the fact that different remedies have been proposed, this still represents a key challenge in molecular simulations. In the present work we propose the C$\\mu$MD method, which introduces an external force that controls the environment of the chemical process of interest. This external force, drawing molecules from a finite reservoir, maintains the chemical potential constant in the region where the process takes place. We have applied the C$\\mu$MD method to the paradigmatic case of urea crystall...
Model Predictive Control of Variable Density Multiphase Flows Governed by
Hinze, Michael
of model predictive control (MPC) consists in steering or keeping the state of a dynamical systemModel Predictive Control of Variable Density Multiphase Flows Governed by Diffuse Interface Models appearing in the model predictive control strategy. The resulting control concept is known as instantaneous
Energy trapping from Hagedorn densities of states
Connor Behan; Klaus Larjo; Nima Lashkari; Brian Swingle; Mark Van Raamsdonk
2013-04-26T23:59:59.000Z
In this note, we construct simple stochastic toy models for holographic gauge theories in which distributions of energy on a collection of sites evolve by a master equation with some specified transition rates. We build in only energy conservation, locality, and the standard thermodynamic requirement that all states with a given energy are equally likely in equilibrium. In these models, we investigate the qualitative behavior of the dynamics of the energy distributions for different choices of the density of states for the individual sites. For typical field theory densities of states (\\log(\\rho(E)) ~ E^{\\alphaenergy spread out relatively quickly. For large N gauge theories with gravitational duals, the density of states for a finite volume of field theory degrees of freedom typically includes a Hagedorn regime (\\log(\\rho(E)) ~ E). We find that this gives rise to a trapping of energy in subsets of degrees of freedom for parametrically long time scales before the energy leaks away. We speculate that this Hagedorn trapping may be part of a holographic explanation for long-lived gravitational bound states (black holes) in gravitational theories.
Minimization of Fractional Power Densities
Minimization of Fractional Power Densities. Robert Hardt, Rice University. Abstract: A k dimensional rectifiable current is given by an oriented k dimensional
Goddard III, William A.
Early maturation processes in coal. Part 2: Reactive dynamics simulations using the ReaxFF reactive force field on Morwell Brown coal structures Elodie Salmon a , Adri C.T. van Duin b , François Lorant Brown coal using the ReaxFF reactive force field. We find that these reactive MD simulations
Gossip-based density estimation in dynamic heterogeneous sensor networks
Langendoen, Koen
, introduce new challenges. Moreover, churn makes the problem even more complicated. In this paper we networks. The devised method supports node mobility and churn, as well as redeployment of new nodes/exit a cluster and they do not have fixed neighbors. One of the other challenges is churn caused by either nodes
Chiral dynamics and peripheral transverse densities (Journal Article) |
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Chiral dynamics and peripheral transverse densities (Journal Article) |
Office of Scientific and Technical Information (OSTI)
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:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5 TablesExports to3,1,50022,3,,0,,6,1,Separation 23TribalInformationConference: Catalytic Nanomotors andofin(Journal Article) | DOEand theSciTech
SciTech Connect: Chiral dynamics and peripheral transverse densities
Office of Scientific and Technical Information (OSTI)
t 4 M sub pisup 2, which can be computed in relativistic chiral effective field theory. Using the leading-order approximation we (a) derive the asymptotic behavior...
Dynamics of a Submesoscale Surface Ocean Density Front
Abramczyk, Marshall
2012-01-01T23:59:59.000Z
Shchepetkin, A. 2008a. Mesoscale to submesoscale transitionShchepetkin, A. 2008b. Mesoscale to submesoscale transitionShchepetkin, A. 2008c. Mesoscale to submesoscale transition
Dynamics of a Submesoscale Surface Ocean Density Front
Abramczyk, Marshall
2012-01-01T23:59:59.000Z
dominant portion of the ocean energy [Capet et al. , 2008a].are important for the ocean energy budget and biogeochemicalrelevance for the ocean energy budget and nutrient
Chiral dynamics and peripheral transverse densities Granados, Carlos G
Office of Scientific and Technical Information (OSTI)
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:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5 TablesExports to3,1,50022,3,,0,,6,1,Separation 23Tribal EnergyCatalyticPreparation and propertiessystem (Conference) | SciTechU(1) Flavor Models
NUMERICAL PREDICTION OF LOCAL TEMPERATURE AND CURRENT DENSITY IN A PEM FUEL CELL
Van Zee, John W.
University of South Carolina Columbia, SC 29208 ABSTRACT The heat generation inside polymer electrolyte in the membrane µ dynamic viscosity, kg-s m-2 m, dry density of a dry membrane, kg m-3 Submitted to: 2000IMECE
Charge transport, configuration interaction and Rydberg states under density functional theory
Cheng, Chiao-Lun
2008-01-01T23:59:59.000Z
Density functional theory (DFT) is a computationally efficient formalism for studying electronic structure and dynamics. In this work, we develop DFT-based excited-state methods to study electron transport, Rydberg excited ...
MD Simulation for Head-on Collision of Liquid Nanodroplets Obeying Modified L-J Potential
Bell, Alexander J
2015-01-01T23:59:59.000Z
This project models and studies the `head-on' collision of liquid helium nanodroplets within a vacuum, using molecular dynamics simulation techniques. Programs written in MATLAB and C are utilized in tandem to facilitate computer experimentation that achieves this goal. The most expensive computation, that of collision simulation, is handled by a HPC cluster `ALICE' at the University of Leicester. Colliding droplets are modelled as roughly spherical collections of points, cut from a simple cubic lattice, obeying a modified Lennard-Jones potential, with average velocities initialized to ensure a `head-on' collision. These point-sets are then allowed to collide within a cuboid region, designed to take advantage of the observed angular distribution of post-collision fragmentation (favoring a plane orthogonal to `collision axis'). To implement the developed theoretical model, an existing C script by D. C. Rapaport, for modelling a homogeneous liquid state, is edited by the author to fit the given, highly heteroge...
Direct experimental determination of spectral densities of molecular complexes
Pachón, Leonardo A. [Grupo de Física Atómica y Molecular, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Chemical Physics Theory Group, Department of Chemistry and Center for Quantum Information and Quantum Control, University of Toronto, Toronto, Ontario M5S 3H6 (Canada); Brumer, Paul [Chemical Physics Theory Group, Department of Chemistry and Center for Quantum Information and Quantum Control, University of Toronto, Toronto, Ontario M5S 3H6 (Canada)
2014-11-07T23:59:59.000Z
Determining the spectral density of a molecular system immersed in a proteomic scaffold and in contact to a solvent is a fundamental challenge in the coarse-grained description of, e.g., electron and energy transfer dynamics. Once the spectral density is characterized, all the time scales are captured and no artificial separation between fast and slow processes need to be invoked. Based on the fluorescence Stokes shift function, we utilize a simple and robust strategy to extract the spectral density of a number of molecular complexes from available experimental data. Specifically, we show that experimental data for dye molecules in several solvents, amino acid proteins in water, and some photochemical systems (e.g., rhodopsin and green fluorescence proteins), are well described by a three-parameter family of sub-Ohmic spectral densities that are characterized by a fast initial Gaussian-like decay followed by a slow algebraic-like decay rate at long times.
Direct Experimental Determination of Spectral Densities of Molecular Complexes
Leonardo A. Pachon; Paul Brumer
2014-10-15T23:59:59.000Z
Determining the spectral density of a molecular system immersed in a proteomic scaffold and in contact to a solvent is a fundamental challenge in the coarse-grained description of, e.g., electron and energy transfer dynamics. Once the spectral density is characterized, all the time scales are captured and no artificial separation between fast and slow processes need be invoked. Based on the fluorescence Stokes shift function, we utilize a simple and robust strategy to extract the spectral density of a number of molecular complexes from available experimental data. Specifically, we show that experimental data for dye molecules in several solvents, amino acid proteins in water, and some photochemical systems (e.g., rhodopsin and green fluorescence proteins), are well described by a three-parameter family of sub-Ohmic spectral densities that are characterized by a fast initial Gaussian-like decay followed by a slow algebraic-like decay rate at long times.
Observation of the Density Minimum in Deeply Supercooled Confined Water
Dazhi Liu; Yang Zhang; Chia-Cheng Chen; Chung-Yuan Mou; Peter H Poole; Sow-Hsin Chen
2007-04-17T23:59:59.000Z
Small angle neutron scattering (SANS) is used to measure the density of heavy water contained in 1-D cylindrical pores of mesoporous silica material MCM-41-S-15, with pores of diameter of 15+-1 A. In these pores the homogenous nucleation process of bulk water at 235 K does not occur and the liquid can be supercooled down to at least 160 K. The analysis of SANS data allows us to determine the absolute value of the density of D2O as a function of temperature. We observe a density minimum at 210+-5 K with a value of 1.041+-0.003 g/cm3. We show that the results are consistent with the predictions of molecular dynamics simulations of supercooled bulk water. This is the first experimental report of the existence of the density minimum in supercooled water.
Nuclear Energy Density Functionals: What do we really know?
Bulgac, Aurel; Jin, Shi
2015-01-01T23:59:59.000Z
We present the simplest nuclear energy density functional (NEDF) to date, determined by only 4 significant phenomenological parameters, yet capable of fitting measured nuclear masses with better accuracy than the Bethe-Weizs\\"acker mass formula, while also describing density structures (charge radii, neutron skins etc.) and time-dependent phenomena (induced fission, giant resonances, low energy nuclear collisions, etc.). The 4 significant parameters are necessary to describe bulk nuclear properties (binding energies and charge radii); an additional 2 to 3 parameters have little influence on the bulk nuclear properties, but allow independent control of the density dependence of the symmetry energy and isovector excitations, in particular the Thomas-Reiche-Kuhn sum rule. This Hohenberg-Kohn-style of density functional theory successfully realizes Weizs\\"acker's ideas and provides a computationally tractable model for a variety of static nuclear properties and dynamics, from finite nuclei to neutron stars, where...
Chakraborty, Monojit; Bhusan, Richa; DasGupta, Sunando
2015-01-01T23:59:59.000Z
Droplet motion over a surface with wettability gradient has been simulated using molecular dynamics (MD) simulation to highlight the underlying physics. GROMACS and Visual Molecular Dynamics (VMD) were used for simulation and intermittent visualization of the droplet configuration respectively. The simulations mimic experiments in a comprehensive manner wherein micro-sized droplets are propelled by surface wettability gradient against a number of retarding forces. The liquid-wall Lennard-Jones interaction parameter and the substrate temperature were varied to explore their effects on the three-phase contact line friction coefficient. The contact line friction was observed to be a strong function of temperature at atomistic scales, confirming the experimentally observed inverse functionality between the coefficient of contact line friction and increase in temperatures. These MD simulation results were successfully compared with the results from a model for self-propelled droplet motion on gradient surfaces.
Yener, Aylin
Rev 0310 Directions to the River's Edge Catering & Conference Center, Naval Air Station Patuxent. Physical address is 46870 Tate Road Bldg 2815, Patuxent River, MD. 20670. REC&C (301) 342-6210. From River For mapping GPS program reference, Lexington Park, MD is the town just outside the base gates
Dynamic thermal management in chip multiprocessor systems
Liu, Chih-Chun
2009-05-15T23:59:59.000Z
Recently, processor power density has been increasing at an alarming rate result- ing in high on-chip temperature. Higher temperature increases current leakage and causes poor reliability. In our research, we ¯rst propose a Predictive Dynamic Ther...
New Mexico, University of
Day 2014 at The University of New Mexico CHTM and OSE-ECE graduate student, Md. Mottaleb Hossain, won at The University of New Mexico, USA for his poster titled "Low voltage CMOS compatible linear-mode p-n junction
ISDRS 2011, December 7-9, 2011, College Park, MD, USA ISDRS 2011 http://www.ece.umd.edu/ISDRS2011
Rubloff, Gary W.
://www.ece.umd.edu/ISDRS2011 1. Introduction High power LEDs are used in Fiber Optic Communications and Lighting Applications Student Paper Failure Modes and Effects Criticality Analysis and Accelerated Life Testing of LEDs Department, Reliability Engineering Program, College Park MD USA, msawant@umd.edu While use of LEDs in fiber
Sanahuja, Blai
Advances in modeling gradual solar energetic particle events q D. Lario * Applied Physics Laboratory, Johns Hopkins University, 11100 Johns Hopkins Road, Laurel, MD 20723, USA Received 19 October 2002; accepted 8 July 2005 Abstract Solar energetic particles pose one of the most serious hazards
Coarse Grained Quantum Dynamics
Cesar Agon; Vijay Balasubramanian; Skyler Kasko; Albion Lawrence
2014-12-09T23:59:59.000Z
We consider coarse graining a quantum system divided between short distance and long distance degrees of freedom, which are coupled by the Hamiltonian. Observations using purely long distance observables can be described by the reduced density matrix that arises from tracing out the short-distance observables. The dynamics of this density matrix is that of an open quantum system, and is nonlocal in time, on the order of some short time scale. We describe these dynamics in a model system with a simple hierarchy of energy gaps $\\Delta E_{UV} > \\Delta E_{IR}$, in which the coupling between high-and low-energy degrees of freedom is treated to second order in perturbation theory. We then describe the equations of motion under suitable time averaging, reflecting the limited time resolution of actual experiments, and find an expansion of the master equation in powers of $\\Delta E_{IR}/\\Delta E_{UV}$, in which the failure of the system to be Hamiltonian or even Markovian appears at higher orders in this ratio. We compute the evolution of the density matrix in two specific examples -- coupled spins, and linearly coupled simple harmonic oscillators. Finally, we discuss the evolution of the density matrix using the path integral approach, computing the Feynman-Vernon influence functional for the IR degrees of freedom in perturbation theory, and argue that this influence functional is the correct analog of the Wilsonian effective action for this problem.
Peak mass and dynamical friction
A. Del Popolo; M. Gambera
1995-06-09T23:59:59.000Z
We show how the results given by several authors relatively to the mass of a density peak are changed when small scale substructure induced by dynamical friction are taken into account. The peak mass obtained is compared to the result of Peacock \\& Heavens (1990) and to the peak mass when dynamical friction is absent to show how these effects conspire to reduce the mass accreted by the peak.
Low density carbonized composite foams
Kong, Fung-Ming (Pleasanton, CA)
1991-01-01T23:59:59.000Z
A carbonized composite foam having a density less than about 50 mg/cm.sup.3 and individual cell sizes no greater than about 1 .mu.m in diameter is described, and the process of making it.
High Energy Density Laboratory Plasmas
to IFE #12;5 The PorDolio FY 2012 1. High Energy Density (HED) Hydrodynamics (HYDRO SBIR IFE Technology Small-Business JS-1 JS-2 JS-3 Lab-DS ECA's Facili
Enhanced residual entropy in high-density nanoconfined bilayer ice
Fabiano Corsetti; Jon Zubeltzu; Emilio Artacho
2015-06-15T23:59:59.000Z
A novel kind of crystal order in high-density nanoconfined bilayer ice is proposed from molecular dynamics and density-functional theory simulations. A first-order transition is observed between a low-temperature proton-ordered solid and a high-temperature proton-disordered solid. The latter is shown to possess crystalline order for the oxygen positions, arranged on a close-packed triangular lattice with AA stacking. Uniquely amongst the ice phases, the triangular bilayer is characterized by two levels of disorder (for the bonding network and for the protons) which results in a residual entropy twice that of bulk ice.
Temperature Power Law of Equilibrium Heavy Particle Density
Sh. Matsumoto; M. Yoshimura
1999-10-19T23:59:59.000Z
A standard calculation of the energy density of heavy stable particles that may pair-annihilate into light particles making up thermal medium is performed to second order of coupling, using the technique of thermal field theory. At very low temperatures a power law of temperature is derived for the energy density of the heavy particle. This is in sharp contrast to the exponentially suppressed contribution estimated from the ideal gas distribution function. The result supports a previous dynamical calculation based on the Hartree approximation, and implies that the relic abundance of dark matter particles is enhanced compared to that based on the Boltzmann equation.
Low density metal hydride foams
Maienschein, Jon L. (Oakland, CA); Barry, Patrick E. (Pleasant Hill, CA)
1991-01-01T23:59:59.000Z
Disclosed is a low density foam having a porosity of from 0 to 98% and a density less than about 0.67 gm/cc, prepared by heating a mixture of powered lithium hydride and beryllium hydride in an inert atmosphere at a temperature ranging from about 455 to about 490 K for a period of time sufficient to cause foaming of said mixture, and cooling the foam thus produced. Also disclosed is the process of making the foam.
Towards Microsecond Biological Molecular Dynamics Simulations on Hybrid Processors
Hampton, Scott S [ORNL; Agarwal, Pratul K [ORNL
2010-01-01T23:59:59.000Z
Biomolecular simulations continue to become an increasingly important component of molecular biochemistry and biophysics investigations. Performance improvements in the simulations based on molecular dynamics (MD) codes are widely desired. This is particularly driven by the rapid growth of biological data due to improvements in experimental techniques. Unfortunately, the factors, which allowed past performance improvements of MD simulations, particularly the increase in microprocessor clock frequencies, are no longer improving. Hence, novel software and hardware solutions are being explored for accelerating the performance of popular MD codes. In this paper, we describe our efforts to port and optimize LAMMPS, a popular MD framework, on hybrid processors: graphical processing units (GPUs) accelerated multi-core processors. Our implementation is based on porting the computationally expensive, non-bonded interaction terms on the GPUs, and overlapping the computation on the CPU and GPUs. This functionality is built on top of message passing interface (MPI) that allows multi-level parallelism to be extracted even at the workstation level with the multi-core CPUs as well as extend the implementation on GPU clusters. The results from a number of typically sized biomolecular systems are provided and analysis is performed on 3 generations of GPUs from NVIDIA. Our implementation allows up to 30-40 ns/day throughput on a single workstation as well as significant speedup over Cray XT5, a high-end supercomputing platform. Moreover, detailed analysis of the implementation indicates that further code optimization and improvements in GPUs will allow {approx}100 ns/day throughput on workstations and inexpensive GPU clusters, putting the widely-desired microsecond simulation time-scale within reach to a large user community.
MD-Predicted Phase diagrams for Pattern Formation due to Ion Irradiation
Scott A. Norris; Juha Samela; Laura Bukonte; Marie Backman; Djurabekova Flyura; Kai Nordlund; Charbel S. Madi; Michael P. Brenner; Michael J. Aziz
2010-12-23T23:59:59.000Z
Energetic particle irradiation of solids can cause surface ultra-smoothening, self-organized nanoscale pattern formation, or degradation of the structural integrity of nuclear reactor components. Periodic patterns including high-aspect ratio quantum dots, with occasional long-range order and characteristic spacing as small as 7 nm, have stimulated interest in this method as a means of sub-lithographic nanofabrication. Despite intensive research there is little fundamental understanding of the mechanisms governing the selection of smooth or patterned surfaces, and precisely which physical effects cause observed transitions between different regimes has remained a matter of speculation. Here we report the first prediction of the mechanism governing the transition from corrugated surfaces to flatness, using only parameter-free molecular dynamics simulations of single-ion impact induced crater formation as input into a multi-scale analysis, and showing good agreement with experiment. Our results overturn the paradigm attributing these phenomena to the removal of target atoms via sputter erosion. Instead, the mechanism dominating both stability and instability is shown to be the impact-induced redistribution of target atoms that are not sputtered away, with erosive effects being essentially irrelevant. The predictions are relevant in the context of tungsten plasma-facing fusion reactor walls which, despite a sputter erosion rate that is essentially zero, develop, under some conditions, a mysterious nanoscale topography leading to surface degradation. Our results suggest that degradation processes originating in impact-induced target atom redistribution effects may be important, and hence that an extremely low sputter erosion rate is an insufficient design criterion for morphologically stable solid surfaces under energetic particle irradiation.
Maximum-likelihood density modification
Terwilliger, Thomas C., E-mail: terwilliger@lanl.gov [Structural Biology Group, Mail Stop M888, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
2000-08-01T23:59:59.000Z
A likelihood-based density modification approach is developed that can incorporate expected electron-density information from a wide variety of sources. A likelihood-based approach to density modification is developed that can be applied to a wide variety of cases where some information about the electron density at various points in the unit cell is available. The key to the approach consists of developing likelihood functions that represent the probability that a particular value of electron density is consistent with prior expectations for the electron density at that point in the unit cell. These likelihood functions are then combined with likelihood functions based on experimental observations and with others containing any prior knowledge about structure factors to form a combined likelihood function for each structure factor. A simple and general approach to maximizing the combined likelihood function is developed. It is found that this likelihood-based approach yields greater phase improvement in model and real test cases than either conventional solvent flattening and histogram matching or a recent reciprocal-space solvent-flattening procedure [Terwilliger (1999 ?), Acta Cryst. D55, 1863–1871].
Phonons and related crystal properties from density-functional perturbation theory
Wu, Zhigang
-Functional Perturbation Theory 516 A. Lattice dynamics from electronic-structure theory 516 B. Density-functional theory July 2001) This article reviews the current status of lattice-dynamical calculations in crystals, using specialized topics are treated, including the implementation for metals, the calculation of the response
T. Thomas; P. Katgert
2005-10-10T23:59:59.000Z
We study the morphology-radius (MR-) and morphology-density (MD-) relations for a sample of about 850 galaxies (with M = -22), the S0 galaxies and the early spirals have different Sigma1-distributions. The reason for this is that Sigma1 is much less correlated with R than is Sigma10, and thus has much less cross-talk from the (MR-) relation. On average, the 'normal' ellipticals populate environments with higher projected density than do the S0 galaxies while the early spirals populate even less dense environments. The segregation of the brightest ellipticals and the late spirals is driven mostly by global factors, while the segregation between 'normal' ellipticals, S0 galaxies and early spirals is driven primarily by local factors.
Delp, Scott
, Stanford, CA, 3Diagnostic Radiology Center, Veterans Affairs Palo Alto Health Care System, Palo Alto, CA(212) 584-4662. 1089-7860,p;2003,07,04,287,296,ftx,en;smr00305x. Cine Phase-Contrast Magnetic Resonance
Symmetries in open quantum dynamics
Thomas F. Jordan
2014-08-20T23:59:59.000Z
Simple examples are used to introduce and examine a Heisenberg picture of symmetries of open quantum dynamics that can be described by unitary operators. When the symmetries are for Hamiltonian dynamics of an entire system, and the spectrum of the Hamiltonian operator has a lower bound, the symmetry operators commute with the Hamiltonian operator. An example shows that symmetry operators need not commute with the Hamiltonian operator when the spectrum of the Hamiltonian does not have a lower bound. There are many more symmetries that are only for the open dynamics of a subsystem and are described by unitary operators that do not commute with the Hamiltonian for the dynamics of the entire system. Examples show how these symmetries alone can reveal properties of the dynamics and reduce what needs to be done to work out the dynamics. A symmetry of the open dynamics of a subsystem can imply properties of the dynamics for the entire system that are not implied by the symmetries of the dynamics of the entire system. The symmetries are generally not related to constants of the motion for the open dynamics of the subsystem. There are symmetries of the open dynamics of a subsystem that depend only on the dynamics. In the simplest examples, these are also symmetries of the dynamics of the entire system. There are many more symmetries, of a new kind, that also depend on correlations, or absence of correlations, between the subsystem and the rest of the entire system, or on the state of the rest of the entire system. Symmetries that depend on correlations generally cannot be seen in the Schr\\"{o}dinger picture as symmetries of dynamical maps of density matrices for the subsystem.
Frontiers for Discovery in High Energy Density Physics
Davidson, R. C.; Katsouleas, T.; Arons, J.; Baring, M.; Deeney, C.; Di Mauro, L.; Ditmire, T.; Falcone, R.; Hammer, D.; Hill, W.; Jacak, B.; Joshi, C.; Lamb, F.; Lee, R.; Logan, B. G.; Melissinos, A.; Meyerhofer, D.; Mori, W.; Murnane, M.; Remington, B.; Rosner, R.; Schneider, D.; Silvera, I.; Stone, J.; Wilde, B.; Zajc. W.
2004-07-20T23:59:59.000Z
The report is intended to identify the compelling research opportunities of high intellectual value in high energy density physics. The opportunities for discovery include the broad scope of this highly interdisciplinary field that spans a wide range of physics areas including plasma physics, laser and particle beam physics, nuclear physics, astrophysics, atomic and molecular physics, materials science and condensed matter physics, intense radiation-matter interaction physics, fluid dynamics, and magnetohydrodynamics
Dynamics of capillary condensation in aerogels
Nomura, R.; Miyashita, W.; Yoneyama, K.; Okuda, Y. [Department of Condensed Matter Physics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152-8551 (Japan)
2006-03-15T23:59:59.000Z
Dynamics of capillary condensation of liquid {sup 4}He in various density silica aerogels was investigated systematically. Interfaces were clearly visible when bulk liquid was rapidly sucked into the aerogel. Time evolution of the interface positions was consistent with the Washburn model and their effective pore radii were obtained. Condensation was a single step in a dense aerogel and two steps in a low density aerogel. Crossover between the two types of condensation was observed in an intermediate density aerogel. Variety of the dynamics may be the manifestation of the fractal nature of aerogels which had a wide range of distribution of pore radii.
Density waves in the shearing sheet III. Disc heating
B. Fuchs
2001-04-25T23:59:59.000Z
The problem of dynamical heating of galactic discs by spiral density waves is discussed using the shearing sheet model. The secular evolution of the disc is described quantitatively by a diffusion equation for the distribution function of stars in the space spanned by integrals of motion of the stars, in particular the radial action integral and an integral related to the angular momentum. Specifically, disc heating by a succession of transient, `swing amplified' density waves is studied. It is shown that such density waves lead predominantly to diffusion of stars in radial action space. The stochastical changes of angular momenta of the stars and the corresponding stochastic changes of the guiding centre radii of the stellar orbits induced by this process are much smaller.
Time Dependent Density Functional Theory An introduction
Botti, Silvana
Time Dependent Density Functional Theory An introduction Francesco Sottile LSI, Ecole Polytechnique (ETSF) Time Dependent Density Functional Theory Palaiseau, 7 February 2012 1 / 32 #12;Outline 1 Frontiers 4 Perspectives and Resources Francesco Sottile (ETSF) Time Dependent Density Functional Theory
Statistical density modification using local pattern matching
Terwilliger, Thomas C.
2007-01-23T23:59:59.000Z
A computer implemented method modifies an experimental electron density map. A set of selected known experimental and model electron density maps is provided and standard templates of electron density are created from the selected experimental and model electron density maps by clustering and averaging values of electron density in a spherical region about each point in a grid that defines each selected known experimental and model electron density maps. Histograms are also created from the selected experimental and model electron density maps that relate the value of electron density at the center of each of the spherical regions to a correlation coefficient of a density surrounding each corresponding grid point in each one of the standard templates. The standard templates and the histograms are applied to grid points on the experimental electron density map to form new estimates of electron density at each grid point in the experimental electron density map.
Longitudinal polarized parton densities updated
Leader, Elliot; Sidorov, Aleksander V.; Stamenov, Dimiter B. [Imperial College, Prince Consort Road, London SW7 2BW (United Kingdom); Bogoliubov Theoretical Laboratory Joint Institute for Nuclear Research 141980 Dubna (Russian Federation); Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences Blvd. Tsarigradsko Chaussee 72, Sofia 1784 (Bulgaria)
2006-02-01T23:59:59.000Z
We have reanalyzed the world data on inclusive polarized DIS, in both NLO and LO QCD, including the new HERMES and COMPASS data. The updated NLO polarized densities are given in both the MS and JET schemes. The impact of the new data on the results is discussed.
About density functional theory interpretation
Kirill Koshelev
2015-05-28T23:59:59.000Z
Two forms of relativistic density functional are derived from Dirac equation. Based on their structure analysis model of split electron is proposed. In this model electric charge and mass of electron behave like two point-like particles. It is shown that two electrons obeying this model cannot occupy the same quantum state. Empirical verification of the model is discussed.
Gan Ren; Yanting Wang
2015-05-02T23:59:59.000Z
The behavior of saturated aqueous sodium chloride solutions under a constant external electric field (E) was studied by molecular dynamics (MD) simulation. Our dynamic MD simulations have indicated that the irreversible nucleation process towards crystallization is accelerated by a moderate E, but retarded or even prohibited under a stronger E, which can be understood by the competition between self-diffusion and drift motion. The former increases with E resulting in the acceleration of the nucleation process, and the latter tears oppositely charged ions more apart under a stronger E leading to the deceleration of nucleation. Moreover, our steady-state MD simulations have indicated that a first-order phase transition happens in saturated solutions only when the applied E is below a certain threshold Ec, and the ratio of crystallized ions does not change with the electric field. The magnitude of Ec increases with concentration, because larger clusters are easy to form in a more concentrated solution and require a stronger E to dissociate them.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Welch, David A.; Mehdi, Beata L.; Hatchell, Hanna J.; Faller, Roland; Evans, James E.; Browning, Nigel D.
2015-03-25T23:59:59.000Z
Understanding the fundamental processes taking place at the electrode-electrolyte interface in batteries will play a key role in the development of next generation energy storage technologies. One of the most fundamental aspects of the electrode-electrolyte interface is the electrical double layer (EDL). Given the recent development of high spatial resolution in-situ electrochemical cells for scanning transmission electron microscopy (STEM), there now exists the possibility that we can directly observe the formation and dynamics of the EDL. In this paper we predict electrolyte structure within the EDL using classical models and atomistic Molecular Dynamics (MD) simulations. The MD simulations show thatmore »the classical models fail to accurately reproduce concentration profiles that exist within the electrolyte. It is thus suggested that MD must be used in order to accurately predict STEM images of the electrode-electrolyte interface. Using MD and image simulations together for a high contrast electrolyte (the high atomic number CsCl electrolyte), it is determined that, for a smooth interface, concentration profiles within the EDL should be visible experimentally. When normal experimental parameters such as rough interfaces and low-Z electrolytes (like those used in Li-ion batteries) are considered, observation of the EDL appears to be more difficult.« less
Smolin, Nikolai [ORNL; Biehl, R [Southern Methodist University, Dallas; Kneller, Gerald [University of Orleans; Richter, Dieter O [ORNL; Smith, Jeremy C [ORNL
2011-01-01T23:59:59.000Z
Protein function often requires large-scale domain motion. An exciting new development in the experimental characterization of domain motions in proteins is the application of neutron spin-echo spectroscopy (NSE). NSE directly probes coherent (i.e., pair correlated) scattering on the 1 100 ns timescale. Here, we report on all-atom molecular-dynamics (MD) simulation of a protein, phosphoglycerate kinase, from which we calculate small-angle neutron scattering (SANS) and NSE scattering properties. The simulation-derived and experimental-solution SANS results are in excellent agreement. The contributions of translational and rotational whole-molecule diffusion to the simulation-derived NSE and potential problems in their estimation are examined. Principal component analysis identifies types of domain motion that dominate the internal motion's contribution to the NSE signal, with the largest being classic hinge bending. The associated free-energy profiles are quasiharmonic and the frictional properties correspond to highly overdamped motion. The amplitudes of the motions derived by MD are smaller than those derived from the experimental analysis, and possible reasons for this difference are discussed. The MD results confirm that a significant component of the NSE arises from internal dynamics. They also demonstrate that the combination of NSE with MD is potentially useful for determining the forms, potentials of mean force, and time dependence of functional domain motions in proteins.
Relativistic Nuclear Energy Density Functionals: adjusting parameters to binding energies
T. Niksic; D. Vretenar; P. Ring
2008-09-08T23:59:59.000Z
We study a particular class of relativistic nuclear energy density functionals in which only nucleon degrees of freedom are explicitly used in the construction of effective interaction terms. Short-distance (high-momentum) correlations, as well as intermediate and long-range dynamics, are encoded in the medium (nucleon density) dependence of the strength functionals of an effective interaction Lagrangian. Guided by the density dependence of microscopic nucleon self-energies in nuclear matter, a phenomenological ansatz for the density-dependent coupling functionals is accurately determined in self-consistent mean-field calculations of binding energies of a large set of axially deformed nuclei. The relationship between the nuclear matter volume, surface and symmetry energies, and the corresponding predictions for nuclear masses is analyzed in detail. The resulting best-fit parametrization of the nuclear energy density functional is further tested in calculations of properties of spherical and deformed medium-heavy and heavy nuclei, including binding energies, charge radii, deformation parameters, neutron skin thickness, and excitation energies of giant multipole resonances.
Pion transverse charge density and the edge of hadrons
Carmignotto, Marco [Catholic University of America; Horn, Tanja [Catholic University of America; Miller, Gerald A. [University of Washington
2014-08-01T23:59:59.000Z
We use the world data on the pion form factor for space-like kinematics and a technique used to extract the proton transverse densities, to extract the transverse pion charge density and its uncertainty due to experimental uncertainties and incomplete knowledge of the pion form factor at large values of Q2. The pion charge density at small values of b<0.1 fm is dominated by this incompleteness error while the range between 0.1-0.3 fm is relatively well constrained. A comparison of pion and proton charge densities shows that the pion is denser than the proton for values of b<0.2 fm. The pion and proton distributions seem to be the same for values of b=0.2-0.6 fm. Future data from Jlab 12 GeV and the EIC will increase the dynamic extent of the data to higher values of Q2 and thus reduce the uncertainties in the extracted pion charge density.
A parallel algorithm for step- and chain-growth polymerization in Molecular Dynamics
Pierre de Buyl; Erik Nies
2015-03-03T23:59:59.000Z
Classical Molecular Dynamics (MD) simulations provide insight on the properties of many soft-matter systems. In some situations it is interesting to model the creation of chemical bonds, a process that is not part of the MD framework. In this context, we propose a parallel algorithm for step- and chain-growth polymerization that is based on a generic reaction scheme, works at a given intrinsic rate and produces continuous trajectories. We present an implementation in the ESPResSo++ simulation software and compare it with the corresponding feature in LAMMPS. For chain growth, our results are compared to the existing simulation literature. For step growth, a rate equation is proposed for the evolution of the crosslinker population that compares well to the simulations for low crosslinker functionality or for short times.
Krishna, Rajamani; van Baten, Jasper M
2011-01-01T23:59:59.000Z
Molecular Dynamics (MD) simulations were carried out to determine the self-diffusivitiy, D{sub i,self}, the Maxwell–Stefan diffusivity, Ð{sub i}, and the Fick diffusivity, D{sub i}, for methane (C1), ethane (C2), propane (C3), n-butane (nC4), n-pentane (nC5), n-hexane (nC6), n-heptane (nC7), and cyclohexane (cC6) in cylindrical silica mesopores for a range of pore concentrations. The MD simulations show that zero-loading diffusivity Ð{sub i}(0) is consistently lower, by up to a factor of 20, than the values anticipated by the classical Knudsen formula. The concentration dependence of the Fick diffusivity, D{sub i} is found to be unusually complex, and displays a strong minimum in some cases; this characteristic can be traced to molecular clustering.
Updated Axion CDM energy density
Ji-Haeng Huh
2008-10-08T23:59:59.000Z
We update cosmological bound on axion model. The contribution from the anharmonic effect and the newly introduced initial overshoot correction are considered. We present an explicit formula for the axion relic density in terms of the QCD scale Lambda_{QCD}, the current quark masses m_q's and the Peccei-Quinn scale F_a, including firstly introduced 1.85 factor which is from the initial overshoot.
Polycarbonate Simulations with a Density Functional Based Force Field P. Ballone, B. Montanari properties of molecules related to polycarbonate have been used to optimize the parameters describing dynamics simulations of crystalline, amorphous, and liquid polycarbonate systems. Applications include
Training Session: Frederick, MD
Broader source: Energy.gov [DOE]
This 3.5-hour training provides builders with a comprehensive review of zero net-energy-ready home construction including the business case, detailed specifications, and opportunities to be...
Density functional theory of freezing: Analysis of crystal density
Laird, Brian Bostian; McCoy, John D.; Haymet, A. D. J.
1987-09-01T23:59:59.000Z
the natural variables are temperature, chemical potential, and volume. The pressures are set equal by varying the liquid density until the grand thermodynamic potential, flO = - pV /kT, of the solid phase equals that of the liquid phase. It should... with temperature T, volume V, and chemical potential J.L. The particles interact via a potential energy U(rl, ... ,rn ) and feel an external single particle potential ifJ (r). Defining a dimen sionless single particle effective potential by u (r) = pJ.L - pif...
A Longitudinal Density Monitor for the LHC
Jeff, Adam; Boccardi, Andrea
At the Large Hadron Collider (LHC), the world’s largest and highest energy particle accelerator, ion bunches circulate in two counter-rotating beams and are brought into collision. Each bunch is confined within a bucket by the longitudinal focusing effect of the radio frequency (RF) cavities. The RF period is 2.5 ns, while the minimum bunch spacing is 25 ns. Thus, 9 out of every 10 buckets should be empty, as well as additional gaps to allow for the rise-time of injection and dump kickers. In practice, however, small numbers of particles can occupy these supposedly empty buckets, causing problems for machine protection and for the absolute calibration of the LHC’s luminosity. The Longitudinal Density Monitor (LDM) is a new monitor, designed to measure the longitudinal distribution of particles in the LHC with a sufficiently high dynamic range to quantify the relative particle population in the supposedly empty buckets. A non-interceptive measurement is made possible by the use of synchrotron radiation (SR...
On the Dynamical Origin of Bias in Clusters of Galaxies
S. Colafrancesco; V. Antonuccio-Delogu; A. Del Popolo
1994-10-29T23:59:59.000Z
We study the effect of the dynamical friction induced by the presence of substructure on the statistics of the collapse of density peaks. Applying the results of a former paper we show that within high density environments, like rich clusters of galaxies, the collapse of smaller peaks is strongly delayed until very late epochs. A bias of dynamical nature thus naturally arises because high density peaks preferentially collapse For a standard CDM model we find that this dynamical bias can account for a substantial part of the total bias required by observations on cluster scales.
Biosystem Dynamics & Design | EMSL
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
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Accelerated molecular dynamics methods: introduction and recent developments
Uberuaga, Blas Pedro [Los Alamos National Laboratory; Voter, Arthur F [Los Alamos National Laboratory; Perez, Danny [Los Alamos National Laboratory; Shim, Y [UNIV OF TOLEDO; Amar, J G [UNIV OF TOLEDO
2009-01-01T23:59:59.000Z
A long-standing limitation in the use of molecular dynamics (MD) simulation is that it can only be applied directly to processes that take place on very short timescales: nanoseconds if empirical potentials are employed, or picoseconds if we rely on electronic structure methods. Many processes of interest in chemistry, biochemistry, and materials science require study over microseconds and beyond, due either to the natural timescale for the evolution or to the duration of the experiment of interest. Ignoring the case of liquids xxx, the dynamics on these time scales is typically characterized by infrequent-event transitions, from state to state, usually involving an energy barrier. There is a long and venerable tradition in chemistry of using transition state theory (TST) [10, 19, 23] to directly compute rate constants for these kinds of activated processes. If needed dynamical corrections to the TST rate, and even quantum corrections, can be computed to achieve an accuracy suitable for the problem at hand. These rate constants then allow them to understand the system behavior on longer time scales than we can directly reach with MD. For complex systems with many reaction paths, the TST rates can be fed into a stochastic simulation procedure such as kinetic Monte Carlo xxx, and a direct simulation of the advance of the system through its possible states can be obtained in a probabilistically exact way. A problem that has become more evident in recent years, however, is that for many systems of interest there is a complexity that makes it difficult, if not impossible, to determine all the relevant reaction paths to which TST should be applied. This is a serious issue, as omitted transition pathways can have uncontrollable consequences on the simulated long-time kinetics. Over the last decade or so, we have been developing a new class of methods for treating the long-time dynamics in these complex, infrequent-event systems. Rather than trying to guess in advance what reaction pathways may be important, we return instead to a molecular dynamics treatment, in which the trajectory itself finds an appropriate way to escape from each state of the system. Since a direct integration of the trajectory would be limited to nanoseconds, while we are seeking to follow the system for much longer times, we modify the dynamics in some way to cause the first escape to happen much more quickly, thereby accelerating the dynamics. The key is to design the modified dynamics in a way that does as little damage as possible to the probability for escaping along a given pathway - i.e., we try to preserve the relative rate constants for the different possible escape paths out of the state. We can then use this modified dynamics to follow the system from state to state, reaching much longer times than we could reach with direct MD. The dynamics within any one state may no longer be meaningful, but the state-to-state dynamics, in the best case, as we discuss in the paper, can be exact. We have developed three methods in this accelerated molecular dynamics (AMD) class, in each case appealing to TST, either implicitly or explicitly, to design the modified dynamics. Each of these methods has its own advantages, and we and others have applied these methods to a wide range of problems. The purpose of this article is to give the reader a brief introduction to how these methods work, and discuss some of the recent developments that have been made to improve their power and applicability. Note that this brief review does not claim to be exhaustive: various other methods aiming at similar goals have been proposed in the literature. For the sake of brevity, our focus will exclusively be on the methods developed by the group.
Subsystem real-time Time Dependent Density Functional Theory
Krishtal, Alisa; Pavanello, Michele
2015-01-01T23:59:59.000Z
We present the extension of Frozen Density Embedding (FDE) theory to real-time Time Dependent Density Functional Theory (rt-TDDFT). FDE a is DFT-in-DFT embedding method that allows to partition a larger Kohn-Sham system into a set of smaller, coupled Kohn-Sham systems. Additional to the computational advantage, FDE provides physical insight into the properties of embedded systems and the coupling interactions between them. The extension to rt-TDDFT is done straightforwardly by evolving the Kohn-Sham subsystems in time simultaneously, while updating the embedding potential between the systems at every time step. Two main applications are presented: the explicit excitation energy transfer in real time between subsystems is demonstrated for the case of the Na$_4$ cluster and the effect of the embedding on optical spectra of coupled chromophores. In particular, the importance of including the full dynamic response in the embedding potential is demonstrated.
Density waves in the shearing sheet I. Swing amplification
B. Fuchs
2001-03-02T23:59:59.000Z
The shearing sheet model of a galactic disk is studied anew. The theoretical description of its dynamics is based on three building blocks: Stellar orbits, which are described here in epicyclic approximation, the collisionless Boltzmann equation determining the distribution function of stars in phase space, and the Poisson equation in order to take account of the self-gravity of the disk. Using these tools I develop a new formalism to describe perturbations of the shearing sheet. Applying this to the unbounded shearing sheet model I demonstrate again how the disturbances of the disk evolve always into `swing amplified' density waves, i.e. spiral-arm like, shearing density enhancements, which grow and decay while the wave crests swing by from leading to trailing orientation. Several examples are given how such `swing amplification' events are incited in the shearing sheet.
Relativistic Coulomb excitation within Time Dependent Superfluid Local Density Approximation
I. Stetcu; C. Bertulani; A. Bulgac; P. Magierski; K. J. Roche
2015-01-13T23:59:59.000Z
Within the framework of the unrestricted time-dependent density functional theory, we present for the first time an analysis of the relativistic Coulomb excitation of the heavy deformed open shell nucleus $^{238}$U. The approach is based on Superfluid Local Density Approximation (SLDA) formulated on a spatial lattice that can take into account coupling to the continuum, enabling self-consistent studies of superfluid dynamics of any nuclear shape. We have computed the energy deposited in the target nucleus as a function of the impact parameter, finding it to be significantly larger than the estimate using the Goldhaber-Teller model. The isovector giant dipole resonance, the dipole pygmy resonance and giant quadrupole modes were excited during the process. The one body dissipation of collective dipole modes is shown to lead a damping width $\\Gamma_\\downarrow \\approx 0.4$ MeV and the number of pre-equilibrium neutrons emitted has been quantified.
Lower crustal density estimation using the density-slowness relationship: a preliminary study
Jones, Gary Wayne
1996-01-01T23:59:59.000Z
The density of the Earths crust is an important parameter. Carlson and Raskin [1984] and Carlsan and Herrick (1990] used an empirical approach an the relationship between density and seismic slowness to estimate the density ...
Assumptions that imply quantum dynamics is linear
Thomas F. Jordan
2006-01-26T23:59:59.000Z
A basic linearity of quantum dynamics, that density matrices are mapped linearly to density matrices, is proved very simply for a system that does not interact with anything else. It is assumed that at each time the physical quantities and states are described by the usual linear structures of quantum mechanics. Beyond that, the proof assumes only that the dynamics does not depend on anything outside the system but must allow the system to be described as part of a larger system. The basic linearity is linked with previously established results to complete a simple derivation of the linear Schrodinger equation. For this it is assumed that density matrices are mapped one-to-one onto density matrices. An alternative is to assume that pure states are mapped one-to-one onto pure states and that entropy does not decrease.
DENSITY OF STATES CALCULATIONS FOR CARBON
Adler, Joan
DENSITY OF STATES CALCULATIONS FOR CARBON ALLOTROPES AND MIXTURES EDUARDO WARSZAWSKI #12;#12;DENSITY OF STATES CALCULATIONS FOR CARBON ALLOTROPES AND MIXTURES Research Thesis Submitted in Partial;#12;Contents Abstract xiii 1 Introduction 1 1.1 Carbon allotropes
NONE
1996-08-01T23:59:59.000Z
The decision document presents the selected interim remedial action for Operable Unit 1 (OU1) of the Former Sanitary Landfill site, at the U.S. Naval Air Station Patuxent River, MD. The interim remedy will reduce the potential of human exposure to wastes remaining at the landfill, precipitation filtering through landfill waste, and the potential risk posed by inhalation and ingestion of contaminated surficial soil at the landfill. The interim action will allow for the continued investigation of the landfill while evaluating final remedial options for groundwater, surface water, and sediment at the site.
Oxides having high energy densities
Ceder, Gerbrand; Kang, Kisuk
2013-09-10T23:59:59.000Z
Certain disclosed embodiments generally relate to oxide materials having relatively high energy and/or power densities. Various aspects of the embodiments are directed to oxide materials having a structure B.sub.i(M.sub.jY.sub.k)O.sub.2, for example, a structure Li.sub.j(Ni.sub.jY.sub.k)O.sub.2 such as Li(Ni.sub.0.5Mn.sub.0.5)O.sub.2. In this structure, Y represents one or more atoms, each independently selected from the group consisting of alkaline earth metals, transition metals, Group 14 elements, Group 15, or Group 16 elements. In some embodiments, such an oxide material may have an O3 crystal structure, and/or a layered structure such that the oxide comprises a plurality of first, repeating atomic planes comprising Li, and a plurality of second, repeating atomic planes comprising Ni and/or Y.
Lipoprotein subclass analysis by immunospecific density
Lester, Sandy Marie
2009-05-15T23:59:59.000Z
to obtain a lipoprotein density profile in the absence and presence of apo C-1. Density Lipoprotein Profiling (DLP) gives relevant information of lipoproteins, such as density and subclass characterization, and is a novel approach to purify apo C-1-enriched...
Liquid Walls Innovative High Power Density Concepts
California at Los Angeles, University of
Liquid Walls Innovative High Power Density Concepts (Based on the APEX Study) http better? #12;Primary Goals 1. High Power Density Capability (main driver) Neutron Wall Load > 10 MW/m2\\VLFV UHJLPHV LI OLTXLG PHWDOV DUH XVHG · High Power Density Capability -Eliminate thermal stress and wall
Jacek Dobaczewski Density functional theory and energy
Dobaczewski, Jacek
in Poland per voivodship Energy density functional 245 647 Price voivodship functional 654 763 295 580Jacek Dobaczewski Density functional theory and energy density functionals in nuclear physics Jacek://www.fuw.edu.pl/~dobaczew/Stellenbosch/dobaczewski_lecture.pdf Home page: http://www.fuw.edu.pl/~dobaczew/ #12;Jacek Dobaczewski Nuclear Structure Energy scales
Ultimate Energy Densities for Electromagnetic Pulses
Mankei Tsang
2008-03-06T23:59:59.000Z
The ultimate electric and magnetic energy densities that can be attained by bandlimited electromagnetic pulses in free space are calculated using an ab initio quantized treatment, and the quantum states of electromagnetic fields that achieve the ultimate energy densities are derived. The ultimate energy densities also provide an experimentally accessible metric for the degree of localization of polychromatic photons.
Protein synthesis driven by dynamical stochastic transcription
Guilherme C. P. Innocentini; Michael Forger; Fernando Antoneli
2014-12-23T23:59:59.000Z
In this letter we propose a mathematical framework to couple transcription and translation in which mRNA production is described by a set of master equations while the dynamics of protein density is governed by a random differential equation. The coupling between the two processes is given by a stochastic perturbation whose statistics satisfies the master equations. In this approach, from the knowledge of the analytical time dependent distribution of mRNA number, we are able to calculate the dynamics of the probability density of the protein population.
Molecular dynamics study of salt–solution interface: Solubility and surface charge of salt in water
Kobayashi, Kazuya; Liang, Yunfeng, E-mail: y-liang@earth.kumst.kyoto-u.ac.jp, E-mail: matsuoka@earth.kumst.kyoto-u.ac.jp; Matsuoka, Toshifumi, E-mail: y-liang@earth.kumst.kyoto-u.ac.jp, E-mail: matsuoka@earth.kumst.kyoto-u.ac.jp [Environment and Resource System Engineering, Kyoto University, Kyoto 615-8540 (Japan)] [Environment and Resource System Engineering, Kyoto University, Kyoto 615-8540 (Japan); Sakka, Tetsuo [Department of Energy and Hydrocarbon Chemistry, Kyoto University, Kyoto 615-8510 (Japan)] [Department of Energy and Hydrocarbon Chemistry, Kyoto University, Kyoto 615-8510 (Japan)
2014-04-14T23:59:59.000Z
The NaCl salt–solution interface often serves as an example of an uncharged surface. However, recent laser-Doppler electrophoresis has shown some evidence that the NaCl crystal is positively charged in its saturated solution. Using molecular dynamics (MD) simulations, we have investigated the NaCl salt–solution interface system, and calculated the solubility of the salt using the direct method and free energy calculations, which are kinetic and thermodynamic approaches, respectively. The direct method calculation uses a salt–solution combined system. When the system is equilibrated, the concentration in the solution area is the solubility. In the free energy calculation, we separately calculate the chemical potential of NaCl in two systems, the solid and the solution, using thermodynamic integration with MD simulations. When the chemical potential of NaCl in the solution phase is equal to the chemical potential of the solid phase, the concentration of the solution system is the solubility. The advantage of using two different methods is that the computational methods can be mutually verified. We found that a relatively good estimate of the solubility of the system can be obtained through comparison of the two methods. Furthermore, we found using microsecond time-scale MD simulations that the positively charged NaCl surface was induced by a combination of a sodium-rich surface and the orientation of the interfacial water molecules.
A molecular dynamics study of nuclear quantum effect on the diffusion of hydrogen in condensed phase
Nagashima, Hiroki; Tokumasu, Takashi [Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi (Japan); Tsuda, Shin-ichi [Shinshu University, 77-7 Minamibori, Nagano, Nagano (Japan); Tsuboi, Nobuyuki [Kyushu Institute of Technology, 1-1 Sensui-cho, Tobata-ku, Kitakyushu, Fukuoka (Japan); Koshi, Mitsuo [Yokohama National University, 79-7 Tokiwadai, Hodogaya, Yokohama, Kanagawa (Japan); Hayashie, A. Koichi [AoyamaGakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa (Japan)
2014-10-06T23:59:59.000Z
In this paper, the quantum effect of hydrogen molecule on its diffusivity is analyzed using Molecular Dynamics (MD) method. The path integral centroid MD (CMD) method is applied for the reproduction method of time evolution of the molecules. The diffusion coefficient of liquid hydrogen is calculated using the Green-Kubo method. The simulation is performed at wide temperature region and the temperature dependence of the quantum effect of hydrogen molecule is addressed. The calculation results are compared with those of classical MD results. As a result, it is confirmed that the diffusivity of hydrogen molecule is changed depending on temperature by the quantum effect. It is clarified that this result can be explained that the dominant factor by quantum effect on the diffusivity of hydrogen changes from the swollening the potential to the shallowing the potential well around 30 K. Moreover, it is found that this tendency is related to the temperature dependency of the ratio of the quantum kinetic energy and classical kinetic energy.
Statistical density modification using local pattern matching
Terwilliger, Thomas C., E-mail: terwilliger@lanl.gov [Mail Stop M888, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
2003-10-01T23:59:59.000Z
Statistical density modification can make use of local patterns of density found in protein structures to improve crystallographic phases. A method for improving crystallographic phases is presented that is based on the preferential occurrence of certain local patterns of electron density in macromolecular electron-density maps. The method focuses on the relationship between the value of electron density at a point in the map and the pattern of density surrounding this point. Patterns of density that can be superimposed by rotation about the central point are considered equivalent. Standard templates are created from experimental or model electron-density maps by clustering and averaging local patterns of electron density. The clustering is based on correlation coefficients after rotation to maximize the correlation. Experimental or model maps are also used to create histograms relating the value of electron density at the central point to the correlation coefficient of the density surrounding this point with each member of the set of standard patterns. These histograms are then used to estimate the electron density at each point in a new experimental electron-density map using the pattern of electron density at points surrounding that point and the correlation coefficient of this density to each of the set of standard templates, again after rotation to maximize the correlation. The method is strengthened by excluding any information from the point in question from both the templates and the local pattern of density in the calculation. A function based on the origin of the Patterson function is used to remove information about the electron density at the point in question from nearby electron density. This allows an estimation of the electron density at each point in a map, using only information from other points in the process. The resulting estimates of electron density are shown to have errors that are nearly independent of the errors in the original map using model data and templates calculated at a resolution of 2.6 Å. Owing to this independence of errors, information from the new map can be combined in a simple fashion with information from the original map to create an improved map. An iterative phase-improvement process using this approach and other applications of the image-reconstruction method are described and applied to experimental data at resolutions ranging from 2.4 to 2.8 Å.
Aerodynamic Focusing Of High-Density Aerosols
Ruiz, D. E.; Fisch, Nathaniel
2014-02-24T23:59:59.000Z
High-density micron-sized particle aerosols might form the basis for a number of applications in which a material target with a particular shape might be quickly ionized to form a cylindrical or sheet shaped plasma. A simple experimental device was built in order to study the properties of high-density aerosol focusing for 1#22; m silica spheres. Preliminary results recover previous findings on aerodynamic focusing at low densities. At higher densities, it is demonstrated that the focusing properties change in a way which is consistent with a density dependent Stokes number.
Zeghib, Abdelghani
Introduction Results Linear Dynamics Lorentz Dynamics Actions of discrete groups on stationary Piccione) Geodeycos Meeting, Lyon, 28-30 April 2010 Abdelghani Zeghib Dynamics on Lorentz manifolds #12;Introduction Results Linear Dynamics Lorentz Dynamics Motivations and questions Examples 1 Introduction
Bailey, Nicholas P; Hansen, Jesper Schmidt; Veldhorst, Arno A; Bøhling, Lasse; Lemarchand, Claire A; Olsen, Andreas E; Bacher, Andreas K; Larsen, Heine; Dyre, Jeppe C; Schrøder, Thomas B
2015-01-01T23:59:59.000Z
RUMD is a general purpose, high-performance molecular dynamics (MD) simulation package running on graphical processing units (GPU's). RUMD addresses the challenge of utilizing the many-core nature of modern GPU hardware when simulating small to medium system sizes (roughly from a few thousand up to hundred thousand particles). It has a performance that is comparable to other GPU-MD codes at large system sizes and substantially better at smaller sizes.RUMD is open-source and consists of a library written in C++ and the CUDA extension to C, an easy-to-use Python interface, and a set of tools for set-up and post-simulation data analysis. The paper describes RUMD's main features, optimizations and performance benchmarks.
Pal, Anirban; Raha, Soumyendu; Bhattacharya, Baidurya
2015-01-01T23:59:59.000Z
We discuss the computational bottlenecks in molecular dynamics (MD) and describe the challenges in parallelizing the computation intensive tasks. We present a hybrid algorithm using MPI (Message Passing Interface) with OpenMP threads for parallelizing a generalized MD computation scheme for systems with short range interatomic interactions. The algorithm is discussed in the context of nanoindentation of Chromium films with carbon indenters using the Embedded Atom Method potential for Cr Cr interaction and the Morse potential for Cr C interactions. We study the performance of our algorithm for a range of MPIthread combinations and find the performance to depend strongly on the computational task and load sharing in the multicore processor. The algorithm scaled poorly with MPI and our hybrid schemes were observed to outperform the pure message passing scheme, despite utilizing the same number of processors or cores in the cluster. Speed-up achieved by our algorithm compared favourably with that achieved by stan...
Molecular dynamics simulation: a tool for exploration and discovery using simple models
D. C. Rapaport
2014-11-13T23:59:59.000Z
Emergent phenomena share the fascinating property of not being obvious consequences of the design of the system in which they appear. This characteristic is no less relevant when attempting to simulate such phenomena, given that the outcome is not always a foregone conclusion. The present survey focuses on several simple model systems that exhibit surprisingly rich emergent behavior, all studied by MD simulation. The examples are taken from the disparate fields of fluid dynamics, granular matter and supramolecular self-assembly. In studies of fluids modeled at the detailed microscopic level using discrete particles, the simulations demonstrate that complex hydrodynamic phenomena in rotating and convecting fluids, the Taylor-Couette and Rayleigh-B\\'enard instabilities, can not only be observed within the limited length and time scales accessible to MD, but even quantitative agreement can be achieved. Simulation of highly counterintuitive segregation phenomena in granular mixtures, again using MD methods, but now augmented by forces producing damping and friction, leads to results that resemble experimentally observed axial and radial segregation in the case of a rotating cylinder, and to a novel form of horizontal segregation in a vertically vibrated layer. Finally, when modeling self-assembly processes analogous to the formation of the polyhedral shells that package spherical viruses, simulation of suitably shaped particles reveals the ability to produce complete, error-free assembly, and leads to the important general observation that reversible growth steps contribute to the high yield. While there are limitations to the MD approach, both computational and conceptual, the results offer a tantalizing hint of the kinds of phenomena that can be explored, and what might be discovered when sufficient resources are brought to bear on a problem.
Enhanced molecular dynamics for simulating porous interphase layers in batteries.
Zimmerman, Jonathan A.; Wong, Bryan Matthew; Jones, Reese E.; Templeton, Jeremy Alan; Lee, Jonathan (Rice University, Houston, TX)
2009-10-01T23:59:59.000Z
Understanding charge transport processes at a molecular level using computational techniques is currently hindered by a lack of appropriate models for incorporating anistropic electric fields in molecular dynamics (MD) simulations. An important technological example is ion transport through solid-electrolyte interphase (SEI) layers that form in many common types of batteries. These layers regulate the rate at which electro-chemical reactions occur, affecting power, safety, and reliability. In this work, we develop a model for incorporating electric fields in MD using an atomistic-to-continuum framework. This framework provides the mathematical and algorithmic infrastructure to couple finite element (FE) representations of continuous data with atomic data. In this application, the electric potential is represented on a FE mesh and is calculated from a Poisson equation with source terms determined by the distribution of the atomic charges. Boundary conditions can be imposed naturally using the FE description of the potential, which then propagates to each atom through modified forces. The method is verified using simulations where analytical or theoretical solutions are known. Calculations of salt water solutions in complex domains are performed to understand how ions are attracted to charged surfaces in the presence of electric fields and interfering media.
Potassium permeation through the KcsA channel: a density functional study
Guidoni, Leonardo
; Streptomyces lividans; Ab initio electronic structure calculation; Ionic selectivity; Electronic polarization of the electronic structure for potassium permeation, we have here under- taken a first principles Density-Parrinello Molecular Dynamics [19] and hybrid CPMD/MM calculations [20]. Our investigation is carried out in two steps
A Density Functional Theory Study of Hydrogen Adsorption in MOF-5 Tim Mueller and Gerbrand Ceder*
Ceder, Gerbrand
. The effect of the framework on the physical structure and electronic structure of the organic linker initio molecular dynamics in the generalized gradient approximation to density functional theory, and calculations indicate that the sites with the strongest interaction with hydrogen are located near the Zn4O
Quartz resonator fluid density and viscosity monitor
Martin, Stephen J. (Albuquerque, NM); Wiczer, James J. (Albuquerque, NM); Cernosek, Richard W. (Albuquerque, NM); Frye, Gregory C. (Cedar Crest, NM); Gebert, Charles T. (Albuquerque, NM); Casaus, Leonard (Bernalillo, NM); Mitchell, Mary A. (Tijeras, NM)
1998-01-01T23:59:59.000Z
A pair of thickness-shear mode resonators, one smooth and one with a textured surface, allows fluid density and viscosity to be independently resolved. A textured surface, either randomly rough or regularly patterned, leads to trapping of liquid at the device surface. The synchronous motion of this trapped liquid with the oscillating device surface allows the device to weigh the liquid; this leads to an additional response that depends on liquid density. This additional response enables a pair of devices, one smooth and one textured, to independently resolve liquid density and viscosity; the difference in responses determines the density while the smooth device determines the density-viscosity product, and thus, the pair determines both density and viscosity.
Dynamical clustering of counterions on flexible polyelectrolytes
Tak Shing Lo; Boris Khusid; Joel Koplik
2007-07-31T23:59:59.000Z
Molecular dynamics simulations are used to study the local dynamics of counterion-charged polymer association at charge densities above and below the counterion condensation threshold. Surprisingly, the counterions form weakly-interacting clusters which exhibit short range orientational order, and which decay slowly due to migration of ions across the diffuse double layer. The cluster dynamics are insensitive to an applied electric field, and qualitatively agree with the available experimental data. The results are consistent with predictions of the classical theory only over much longer time scales.
Why quantum dynamics is linear
Thomas F. Jordan
2007-02-16T23:59:59.000Z
Quantum dynamics is linear. How do we know? From theory or experiment? The history of this question is reviewed. Nonlinear generalizations of quantum mechanics have been proposed. They predict small but clear nonlinear effects, which very accurate experiments have not seen. Is there a reason in principle why nonlinearity is not found? Is it impossible? Does quantum dynamics have to be linear? Attempts to prove this have not been decisive, because either their assumptions are not compelling or their arguments are not conclusive. The question has been left unsettled. There is a simple answer, based on a simple assumption. It was found in two steps separated by 44 years. They are steps back to simpler and more compelling assumptions. A proof of the assumptions of the Wigner-Bargmann proof has been known since 1962. It assumes that the maps of density matrices in time are linear. For this step, it is also assumed that density matrices are mapped one-to-one onto density matrices. An alternative is to assume that pure states are mapped one-to-one onto pure states and that entropy does not decrease. In a step taken in 2006, it is proved that the maps of density matrices in time are linear. It is assumed, as in the earlier step, that at each time the physical quantities and states are described by the usual linear structures of quantum mechanics, so the question is only about how things change in time. Beyond that, the proof assumes only that the dynamics does not depend on anything outside the system, but must allow the system to be described as part of a larger system.
Dynamical models with a general anisotropy profile
M. Baes; E. Van Hese
2007-05-28T23:59:59.000Z
Both numerical simulations and observational evidence indicate that the outer regions of galaxies and dark matter haloes are typically mildly to significantly radially anisotropic. The inner regions can be significantly non-isotropic, depending on the dynamical formation and evolution processes. In an attempt to break the lack of simple dynamical models that can reproduce this behaviour, we explore a technique to construct dynamical models with an arbitrary density and an arbitrary anisotropy profile. We outline a general construction method and propose a more practical approach based on a parameterized anisotropy profile. This approach consists of fitting the density of the model with a set of dynamical components, each of which have the same anisotropy profile. Using this approach we avoid the delicate fine-tuning difficulties other fitting techniques typically encounter when constructing radially anisotropic models. We present a model anisotropy profile that generalizes the Osipkov-Merritt profile, and that can represent any smooth monotonic anisotropy profile. Based on this model anisotropy profile, we construct a very general seven-parameter set of dynamical components for which the most important dynamical properties can be calculated analytically. We use the results to look for simple one-component dynamical models that generate simple potential-density pairs while still supporting a flexible anisotropy profile. We present families of Plummer and Hernquist models in which the anisotropy at small and large radii can be chosen as free parameters. We also generalize these two families to a three-parameter family that self-consistently generates the set of Veltmann potential-density pairs. (Abridged...)
Method of synthesizing a low density material
Lorensen, L.E.; Monaco, S.B.
1987-02-27T23:59:59.000Z
A novel method of synthesizing a polymeric material of low density of the order of 50mg/cc or less. Such a low density material has applications in many areas including laser target fabrication. The method comprises preparing a polymer blend of two incompatible polymers as a major and a minor phase by mixing them and extruding the mixture, and then selectively extracting the major component, to yield a fine, low density structure.
Considering Air Density in Wind Power Production
Farkas, Zénó
2011-01-01T23:59:59.000Z
In the wind power production calculations the air density is usually considered as constant in time. Using the CIPM-2007 equation for the density of moist air as a function of air temperature, air pressure and relative humidity, we show that it is worth taking the variation of the air density into account, because higher accuracy can be obtained in the calculation of the power production for little effort.
Considering Air Density in Wind Power Production
Zénó Farkas
2011-03-11T23:59:59.000Z
In the wind power production calculations the air density is usually considered as constant in time. Using the CIPM-2007 equation for the density of moist air as a function of air temperature, air pressure and relative humidity, we show that it is worth taking the variation of the air density into account, because higher accuracy can be obtained in the calculation of the power production for little effort.
Dislocation dynamics: from microscopic models to macroscopic crystal plasticity
Hajj, A El; Monneau, R
2009-01-01T23:59:59.000Z
In this paper we study the connection between four models describing dislocation dynamics: a generalized 2D Frenkel-Kontorova model at the atomic level, the Peierls-Nabarro model, the discrete dislocation dynamics and a macroscopic model with dislocation densities. We show how each model can be deduced from the previous one at a smaller scale.
3-D capacitance density imaging system
Fasching, G.E.
1988-03-18T23:59:59.000Z
A three-dimensional capacitance density imaging of a gasified bed or the like in a containment vessel is achieved using a plurality of electrodes provided circumferentially about the bed in levels and along the bed in channels. The electrodes are individually and selectively excited electrically at each level to produce a plurality of current flux field patterns generated in the bed at each level. The current flux field patterns are suitably sensed and a density pattern of the bed at each level determined. By combining the determined density patterns at each level, a three-dimensional density image of the bed is achieved. 7 figs.
Uncertainty Quantification for Nuclear Density Functional Theory...
Office of Scientific and Technical Information (OSTI)
Uncertainty Quantification for Nuclear Density Functional Theory and Information Content of New Measurements Citation Details In-Document Search This content will become publicly...
Building a Universal Nuclear Energy Density Functional
Bertulani, Carlos A. [Texas A& M Univ., Commerce, TX (United States)
2014-09-10T23:59:59.000Z
This grant had two components: Density functional theory and pairing and Nuclear reactions. This final report summarizes the activities for this SciDAC-2 project.
On the Extensive Air Shower density spectrum
Aleksander Zawadzki; Tadeusz Wibig; Jerzy Gawin
1998-07-29T23:59:59.000Z
In search for new methods of determining the primary energy spectrum of Cosmic Rays, the attention was paid to the density spectrum measurement. New methods available at present warrant an accurateness of conclusions derived from the density spectrum measurements. The general statement about the change of the spectral index of the charged particle density spectrum is confirmed very clearly. Results concerning the shower size and primary energy spectra are also presented and discussed. Interesting future prospects for applications of the density spectrum method are proposed.
Level dynamics and the ten-fold way
Alan T. Huckleberry; Marek Kus; Patrick Schuetzdeller
2007-02-25T23:59:59.000Z
We investigate the parameter dynamics of eigenvalues of Hamiltonians ('level dynamics') defined on symmetric spaces relevant for condensed matter and particle physics. In particular we: 1) identify appropriate reduced manifold on which the motion takes place, 2) identify the correct Poisson structure ensuring the Hamiltonian character of the reduced dynamics, 3) determine the canonical measure on the reduced space, 4) calculate the resulting eigenvalue density.
Time Dependent Density Functional Theory An Introduction
Botti, Silvana
Time Dependent Density Functional Theory An Introduction Francesco Sottile Laboratoire des Solides) Belfast, 29 Jun 2007 Time Dependent Density Functional Theory Francesco Sottile #12;Intro Formalism Linear Response Formalism 3 TDDFT in practice: The ALDA: Achievements and Shortcomings 4 Resources Time
Introduction to Dynamic Distributed
Roma "La Sapienza", Università di
Introduction to Dynamic Distributed SystemsSystems #12;Outline Introduction Churn Building Applications in Dynamic Distributed Systems RegistersRegisters Eventual Leader election Connectivity in Dynamic Distributed Systems #12;Dynamic Distributed Systems: Context & Motivations Advent of Complex Distributed
Dependence of polar hole density on magnetic and solar conditions
Hoegy, W.R.; Grebowsky, J.M. (NASA Goddard Space Flight Center, Greenbelt, MD (USA))
1991-04-01T23:59:59.000Z
The dependence of electron density in the polar F region ionization hole on solar activity, universal time (UT), magnetic activity, season, and hemisphere is studied using data from the Langmuir probes on Atmosphere Explorer C and Dynamics Explorer 2. The AE-C data were obtained during solar minimum when the 3-month average 10.7-cm solar flux index varied from 70 to 140; the DE 2 data were obtained near solar maximum when 10.7-cm solar flux index varied from 120 to 220. The polar hole is a region on the nightside of the polar cap where reduced ionization exists because of the long transport time of ionization from the dayside across the polar cap. The behavior of this region as a function of 10.7-cm solar flux (F10.7), UT, and Kp is statistically modeled for equinox, summer, and winter conditions for each hemisphere separately. The strongest dependencies are observed in F10.7 and UT; the Kp dependence is weak because it poorly represents the complexities of convection across the polar cap. A strong hemispherical difference due to the offset of the magnetic poles from the Earth's rotation axis is observed in the UT dependence of the ionization hole: there is a density minimum at about 20.3 hours UT in the south and at about 4.8 hours UT in the north; the minimum to maximum UT density variation is about a factor of 8.9 in the south and about a factor of 2.1 in the north. There is a seasonal variation in the dependence of ion density (N{sub i}) on solar flux (F10.7). Use of the relationship (N{sub i}{approximately}F10.7{sup D}) yields values of D of approximately unity (1.) in the summer polar hole and about 2.1 during equinox. There is an overall asymmetry in the density level between hemispheres; it was found that the winter hole density is about a factor of 10 greater in the north than in the south. The Utah State University time dependent ionosphere model gives similar UT behavior to that found in the AE-C and DE 2 data.
Density functional theory for carbon dioxide crystal
Chang, Yiwen; Mi, Jianguo, E-mail: mijg@mail.buct.edu.cn; Zhong, Chongli [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China)
2014-05-28T23:59:59.000Z
We present a density functional approach to describe the solid?liquid phase transition, interfacial and crystal structure, and properties of polyatomic CO{sub 2}. Unlike previous phase field crystal model or density functional theory, which are derived from the second order direct correlation function, the present density functional approach is based on the fundamental measure theory for hard-sphere repulsion in solid. More importantly, the contributions of enthalpic interactions due to the dispersive attractions and of entropic interactions arising from the molecular architecture are integrated in the density functional model. Using the theoretical model, the predicted liquid and solid densities of CO{sub 2} at equilibrium triple point are in good agreement with the experimental values. Based on the structure of crystal-liquid interfaces in different planes, the corresponding interfacial tensions are predicted. Their respective accuracies need to be tested.
Neutral depletion and the helicon density limit
Magee, R. M.; Galante, M. E.; Carr, J. Jr.; Lusk, G.; McCarren, D. W.; Scime, E. E. [West Virginia University, Morgantown, West Virginia 26506 (United States)] [West Virginia University, Morgantown, West Virginia 26506 (United States)
2013-12-15T23:59:59.000Z
It is straightforward to create fully ionized plasmas with modest rf power in a helicon. It is difficult, however, to create plasmas with density >10{sup 20} m{sup ?3}, because neutral depletion leads to a lack of fuel. In order to address this density limit, we present fast (1 MHz), time-resolved measurements of the neutral density at and downstream from the rf antenna in krypton helicon plasmas. At the start of the discharge, the neutral density underneath the antenna is reduced to 1% of its initial value in 15 ?s. The ionization rate inferred from these data implies that the electron temperature near the antenna is much higher than the electron temperature measured downstream. Neutral density measurements made downstream from the antenna show much slower depletion, requiring 14 ms to decrease by a factor of 1/e. Furthermore, the downstream depletion appears to be due to neutral pumping rather than ionization.
Density waves in the shearing sheet IV. Interaction with a live dark halo
B. Fuchs
2004-03-01T23:59:59.000Z
It is shown that if the self-gravitating shearing sheet, a model of a patch of a galactic disk, is embedded in a live dark halo, this has a strong effect on the dynamics of density waves in the sheet. I describe how the density waves and the halo interact via halo particles either on orbits in resonance with the wave or on non-resonant orbits. Contrary to expectation the presence of the halo leads to a very considerable enhancement of the amplitudes of the density waves in the shearing sheet. This effect appears to be the equivalent of the recently reported enhanced growth of bars in numerically simulated stellar disks embedded in live dark halos. Finally I discuss the transfer of linear momentum from a density wave in the sheet to the halo and show that it is mediated only by halo particles on resonant orbits.
Michael Murray; for the BRAHMS Collaboration
2007-10-24T23:59:59.000Z
The purpose of BRAHMS is to survey the dynamics of relativistic heavy ion (as well as pp and d-A) collisions over a very wide range of rapidity and transverse momentum. The sum of these data may give us a glimpse of the initial state of the system, its transverse and longitudinal evolution and how the nature of the system changes with time. Here I will concentrate on the origin and dynamics of the light flavors, i.e. the creation and transport of the up, down and strange quarks. The results presented here are certainly not the end of the story. It is my hope that in a few years new detectors will reveal the rapidity dependence of the charm and bottom quarks.
Molecular dynamics studies of the primary state of radiation damage
Diaz de la Rubia, T.; Averback, R.S.; Robertson, I.M.; Benedek, R.
1988-12-01T23:59:59.000Z
This paper summarizes recent progress in the understanding of energetic displacement cascades in metals achieved with the molecular-dynamics (MD) simulation technique. Recoil events with primary-knock-on-atom (PKA) energies up to 5 keV were simulated in Cu and Ni. The initial development of displacement cascades was similar in both metals, with replacement collision sequences providing the most efficient mechanism for the separation of interstitials and vacancies. The thermal-spike behavior in these metals, however, is quite different; Cu cascades are characterized by lower defect production and greater atomic disordering than those in Ni. The thermal spike significantly influences various other properties of cascades, such as total defect production and defect clustering. 32 refs., 7 figs., 2 tabs.
Laughlin, Robert B.
Fatal self-poisoning with lithium carbonate M.R. Achong, b sc, mb; P.G. Fernandez, mrcp, frcp[c]; P.J. McLeod, md, frcp[c] Summary: In a fatal case of self- poisoning with lithium carbonate
Antsaklis, Panos
using the L* Algorithm," Technical Report of the ISIS (Interdisciplinary Studies of Intelligent Systems) Group, No. ISIS-94-010, Univ of Notre Dame, September 1994. #12;M.D. Lemmon, Xiaojun Yang and P. J of the ISIS (Interdisciplinary Studies of Intelligent Systems) Group, No. ISIS-94-010, Univ of Notre Dame
Nahar, Sultana Nurun
One Physics Ellipse Â· College Park, MD 20740-3844 USA Â· www.aps.org Direct inquiries to Jennifer participants receive APS News and Physics Today as part of their membership. While no journal publications (e.org/programs/international/programs/journals.cfm. To advance and diffuse the knowledge of physics by providing APS membership to individual physicists
Goldman, Steven A.
Heart DiseaseHeart Disease-- Learn to Love YourLearn to Love Your HeartHeart Michael McKee, M.D.Michael McKee, M.D. March 19, 2010March 19, 2010 #12;GoalsGoals ·· Learn more about heart disease for yourself andLearn more about heart disease for yourself and for your studentsfor your students ·· Learn
Density Prediction of Uranium-6 Niobium Ingots
D.F.Teter; P.K. Tubesing; D.J.Thoma; E.J.Peterson
2003-04-15T23:59:59.000Z
The densities of uranium-6 niobium (U-Nb) alloys have been compiled from a variety of literature sources such as Y-12 and Rocky Flats datasheets. We also took advantage of the 42 well-pedigreed, homogeneous baseline U-Nb alloys produced under the Enhanced Surveillance Program for density measurements. Even though U-Nb alloys undergo two-phase transitions as the Nb content varies from 0 wt. % to 8 wt %, the theoretical and measured densities vary linearly with Nb content. Therefore, the effect of Nb content on the density was modeled with a linear regression. From this linear regression, a homogeneous ingot of U-6 wt.% Nb would have a density of 17.382 {+-} 0.040 g/cc (95% CI). However, ingots produced at Y-12 are not homogeneous with respect to the Nb content. Therefore, using the 95% confidence intervals, the density of a Y-12 produced ingot would vary from 17.310 {+-} 0.043 g/cc at the center to 17.432 {+-} 0.039 g/cc at the edge. Ingots with larger Nb inhomogeneities will also have larger variances in the density.
Nuclear Dynamics at the Balance Energy
Aman D. Sood; Rajeev K. Puri
2003-11-05T23:59:59.000Z
We study the mass dependence of various quantities (like the average and maximum density, collision rate, participant-spectator matter, temperature as well as time zones for higher density) by simulating the reactions at the energy of vanishing flow. This study is carried out within the framework of Quantum Molecular Dynamics model. Our findings clearly indicate an existence of a power law in all the above quantities calculated at the balance energy. The only significant mass dependence was obtained for the temperature reached in the central sphere. All other quantities are rather either insensitive or depend weakly on the system size at balance energy. The time zone for higher density as well as the time of maximal density and collision rate follow a power law inverse to the energy of vanishing flow.
Low density, resorcinol-formaldehyde aerogels
Pekala, R.W.
1988-05-26T23:59:59.000Z
The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer ''clusters''. The covalent crosslinking of these ''clusters'' produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density less than or equal to100 mg/cc; cell size less than or equal to0.1 microns). The aerogels are transparent,dark red in color and consist of interconnected colloidal-like particles with diameters of about 100 A/degree/. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron. 1 fig., 1 tab.
Low density, resorcinol-formaldehyde aerogels
Pekala, Richard W. (Pleasant Hill, CA)
1991-01-01T23:59:59.000Z
The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer "Clusters". The covalent crosslinking of these "clusters" produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density.ltoreq.100 mg/cc; cell size .ltoreq.0.1 microns). The aerogels are transparent, dark red in color and consist of interconnected colloidal-like particles with diameters of about 100.circle.. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron.
Low density, resorcinol-formaldehyde aerogels
Pekala, Richard W. (Pleasant Hill, CA)
1989-01-01T23:59:59.000Z
The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer "clusters". The covalent crosslinking of these "clusters" produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density .ltoreq.100 mg/cc; cell size .ltoreq.0.1 microns). The aerogels are transparent, dark red in color and consist of interconnected colloidal-like particles with diameters of about 100 .ANG.. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron.
Low density, resorcinol-formaldehyde aerogels
Pekala, R.W.
1989-10-10T23:59:59.000Z
The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer clusters. The covalent crosslinking of these clusters produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density [<=]100 mg/cc; cell size [<=]0.1 microns). The aerogels are transparent, dark red in color and consist of interconnected colloidal-like particles with diameters of about 100 [angstrom]. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron.
Black Holes and Nuclear Dynamics
David Merritt
2006-02-17T23:59:59.000Z
Supermassive black holes inhabit galactic nuclei, and their presence influences in crucial ways the evolution of the stellar distribution. The low-density cores observed in bright galaxies are probably a result of black hole infall, while steep density cusps like those at the Galactic center are a result of energy exchange between stars moving in the gravitational field of the single black hole. Loss-cone dynamics are substantially more complex in galactic nuclei than in collisionally-relaxed systems like globular clusters due to the wider variety of possible geometries and orbital populations. The rate of star-black hole interactions has begun to be constrained through observations of energetic events associated with stellar tidal disruptions.
Kinetic Theory for Binary Granular Mixtures at Low-Density
Vicente Garzo
2007-04-10T23:59:59.000Z
Many features of granular media can be modelled as a fluid of hard spheres with {\\em inelastic} collisions. Under rapid flow conditions, the macroscopic behavior of grains can be described through hydrodynamic equations. At low-density, a fundamental basis for the derivation of the hydrodynamic equations and explicit expressions for the transport coefficients appearing in them is provided by the Boltzmann kinetic theory conveniently modified to account for inelastic binary collisions. The goal of this chapter is to give an overview of the recent advances made for binary granular gases by using kinetic theory tools. Some of the results presented here cover aspects such as transport properties, energy nonequipartition, instabilities, segregation or mixing, non-Newtonian behavior, .... In addition, comparison of the analytical results with those obtained from Monte Carlo and molecular dynamics simulations is also carried out, showing the reliability of kinetic theory to describe granular flows even for strong dissipation.
Density controlled carbon nanotube array electrodes
Ren, Zhifeng F. (Newton, MA); Tu, Yi (Belmont, MA)
2008-12-16T23:59:59.000Z
CNT materials comprising aligned carbon nanotubes (CNTs) with pre-determined site densities, catalyst substrate materials for obtaining them and methods for forming aligned CNTs with controllable densities on such catalyst substrate materials are described. The fabrication of films comprising site-density controlled vertically aligned CNT arrays of the invention with variable field emission characteristics, whereby the field emission properties of the films are controlled by independently varying the length of CNTs in the aligned array within the film or by independently varying inter-tubule spacing of the CNTs within the array (site density) are disclosed. The fabrication of microelectrode arrays (MEAs) formed utilizing the carbon nanotube material of the invention is also described.
High density load bearing insulation peg
Nowobilski, J.J.; Owens, W.J.
1985-01-29T23:59:59.000Z
A high density peg is disclosed which can support a large load and exhibits excellent thermal resistance produced by a method wherein the peg is made in compliance with specified conditions of time, temperature and pressure. 4 figs.
Primordial Density Fluctuations in Phase Coupling Gravity
C. E. M. Batista; M. Schiffer
1996-01-10T23:59:59.000Z
In this paper we study the evolution of density perturbations in the framework of Phase Coupling Gravity theory at the very early universe. We show that these perturbation display an exponential-like behaviour.
Density shock waves in confined microswimmers
Tsang, Alan Cheng Hou
2015-01-01T23:59:59.000Z
Motile and driven particles confined in microfluidic channels exhibit interesting emergent behavior from propagating density bands to density shock waves. A deeper understanding of the physical mechanisms responsible for these emergent structures is relevant to a number of physical and biomedical applications. Here, we study the formation of density shock waves in the context of an idealized model of microswimmers confined in a narrow channel and subject to a uniform external flow. Interestingly, these density shock waves exhibit a transition from `subsonic' with compression at the back to `supersonic' with compression at the front of the population as the intensity of the external flow increases. This behavior is the result of a non-trivial interplay between hydrodynamic interactions and geometric confinement, and is confirmed by a novel quasilinear wave model that properly captures the dependence of the shock formation on the external flow. These findings can be used to guide the development of novel mechan...
Magnetic fields and density functional theory
Salsbury Jr., Freddie
1999-02-01T23:59:59.000Z
A major focus of this dissertation is the development of functionals for the magnetic susceptibility and the chemical shielding within the context of magnetic field density functional theory (BDFT). These functionals depend on the electron density in the absence of the field, which is unlike any other treatment of these responses. There have been several advances made within this theory. The first of which is the development of local density functionals for chemical shieldings and magnetic susceptibilities. There are the first such functionals ever proposed. These parameters have been studied by constructing functionals for the current density and then using the Biot-Savart equations to obtain the responses. In order to examine the advantages and disadvantages of the local functionals, they were tested numerically on some small molecules.
Tweedie Family Densities: Methods of Evaluation
Smyth, Gordon K.
of Queensland, St Lucia, Q 4072, Australia. 2 University of Southern Queensland, Toowoomba, Q 4350, Australia. Tweedie family densities are characterised by power variance functions of the form V[µ] = µp , where p
Breast Density and Cancer | GE Global Research
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Breast Cancer Awareness Series: Understanding Breast Density Click to email this to a friend (Opens in new window) Share on Facebook (Opens in new window) Click to share (Opens in...
Spacetime Average Density (SAD) cosmological measures
Page, Don N., E-mail: profdonpage@gmail.com [Department of Physics, 4-183 CCIS, University of Alberta, Edmonton, Alberta, T6G 2E1 Canada (Canada)
2014-11-01T23:59:59.000Z
The measure problem of cosmology is how to obtain normalized probabilities of observations from the quantum state of the universe. This is particularly a problem when eternal inflation leads to a universe of unbounded size so that there are apparently infinitely many realizations or occurrences of observations of each of many different kinds or types, making the ratios ambiguous. There is also the danger of domination by Boltzmann Brains. Here two new Spacetime Average Density (SAD) measures are proposed, Maximal Average Density (MAD) and Biased Average Density (BAD), for getting a finite number of observation occurrences by using properties of the Spacetime Average Density (SAD) of observation occurrences to restrict to finite regions of spacetimes that have a preferred beginning or bounce hypersurface. These measures avoid Boltzmann brain domination and appear to give results consistent with other observations that are problematic for other widely used measures, such as the observation of a positive cosmological constant.
Turbulent density fluctuations in the solar wind
Ingale, Madhusudan
2015-01-01T23:59:59.000Z
Treatments of the radio scattering due to density turbulence in the solar wind typically employ asymptotic approximations to the phase structure function. We use a general structure function (GSF) that straddles the asymptotic limits and quantify the relative error introduced by the approximations. We show that the regimes where GSF predictions are accurate than those of its asymptotic approximations is not only of practical relevance, but are where inner scale effects influence the estimate of the scatter-broadening. Thus we propose that GSF should henceforth be used for scatter broadening calculations and estimates of quantities characterizing density turbulence in the solar corona and solar wind. In the next part of this thesis we use measurements of density turbulence in the solar wind from previously publish observations of radio wave scattering and interplanetary scintillations. Density fluctuations are inferred using the GSF for radio scattering data and existing analysis methods for IPS. Assuming that...
Shock compression of low-density foams
Holmes, N.C.
1993-07-01T23:59:59.000Z
Shock compression of very low density micro-cellular materials allows entirely new regimes of hot fluid states to be investigated experimentally. Using a two-stage light-gas gun to generate strong shocks, temperatures of several eV are readily achieved at densities of roughly 0.5--1 g/cm{sup 3} in large, uniform volumes. The conditions in these hot, expanded fluids are readily found using the Hugoniot jump conditions. We will briefly describe the basic methodology for sample preparation and experimental measurement of shock velocities. We present data for several materials over a range of initial densities. This paper will explore the applications of these methods for investigations of equations of state and phase diagrams, spectroscopy, and plasma physics. Finally, we discus the need for future work on these and related low-density materials.
Spin- and Pair-Density-Wave Glasses
Mross, David F.
Spontaneous breaking of translational symmetry, known as density-wave order, is common in nature. However, such states are strongly sensitive to impurities or other forms of frozen disorder leading to fascinating glassy ...
Alpha track density using a semiconductor detector
Hamilton, Ian Scott
1993-01-01T23:59:59.000Z
Determination of the alpha track density in the cellulose nitrate (CN) dielectric version of solid state nuclear track detectors (SSNTD) has traditionally been tedious work which produced results that relied upon the person counting the film as well...
The Chemistry of Atherogenic High Density Lipoprotein
Moore, D'Vesharronne J.
2012-07-16T23:59:59.000Z
An array of analytical methods including density gradient ultracentrifugation, capillary electrophoresis, and matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), were utilized to analyze serum high ...
LANDAU'S NECESSARY DENSITY CONDITIONS FOR LCA GROUPS
Kutyniok, Gitta
LANDAU'S NECESSARY DENSITY CONDITIONS FOR LCA GROUPS KARLHEINZ GRÂ¨OCHENIG, GITTA KUTYNIOK's conditions to the setting of locally compact abelian (LCA) groups, relying in an analogous way on the basics
Alpha track density using a semiconductor detector
Hamilton, Ian Scott
1993-01-01T23:59:59.000Z
of factors including variation in the initial dielectric thickness, and other undefined parameters. In addition, the resultant radon concentration reading is dependent upon the calibration factor used to interpret the track density reading. Obtaining...
Density Profiles of Liquid/Vapor Interfaces Away from Their Critical Points
Bu, Wei; Kim, Doseok; Vaknin, David
2014-06-12T23:59:59.000Z
We examine the applicability of various model profiles for the liquid/vapor interface by X-ray reflectivities on water and ethanol and their mixtures at room temperature. Analysis of the X-ray reflecivities using various density profiles shows an error-function like profile is the most adequate within experimental error. Our findings, together with recent observations from simulation studies on liquid surfaces, strongly suggest that the capillary-wave dynamics shapes the interfacial density profile in terms of the error function.
Ligand identification using electron-density mapcorrelations
Terwilliger, Thomas C.; Adams, Paul D.; Moriarty, Nigel W.; Cohn,Judith D.
2006-12-01T23:59:59.000Z
A procedure for the identification of ligands bound incrystal structuresof macromolecules is described. Two characteristics ofthe density corresponding to a ligand are used in the identificationprocedure. One is the correlation of the ligand density with each of aset of test ligands after optimization of the fit of that ligand to thedensity. The other is the correlation of a fingerprint of the densitywith the fingerprint of model density for each possible ligand. Thefingerprints consist of an ordered list of correlations of each the testligands with the density. The two characteristics are scored using aZ-score approach in which the correlations are normalized to the mean andstandard deviation of correlations found for a variety of mismatchedligand-density pairs, so that the Z scores are related to the probabilityof observing a particular value of the correlation by chance. Theprocedure was tested with a set of 200 of the most commonly found ligandsin the Protein Data Bank, collectively representing 57 percent of allligands in the Protein Data Bank. Using a combination of these twocharacteristics of ligand density, ranked lists of ligand identificationswere made for representative (F-o-F-c) exp(i phi(c)) difference densityfrom entries in the Protein Data Bank. In 48 percent of the 200 cases,the correct ligand was at the top of the ranked list of ligands. Thisapproach may be useful in identification of unknown ligands in newmacromolecular structures as well as in the identification of whichligands in a mixture have bound to a macromolecule.
STANDING WAVE PROBES FOR DIMENSIONAL METROLOGY OF LOW DENSITY FOAMS
Seugling, R M; Woody, S C; Bauza, M B
2010-03-23T23:59:59.000Z
Typically, parts and geometries of interest to LLNL are made from a combination of complex geometries and a wide array of different materials ranging from metals and ceramics to low density foams and plastic foils. These parts are combined to develop physics experiments for studying material properties, equation of state (EOS) and radiation transport. Understanding the dimensional uncertainty of the parts contained within an experiment is critical to the physical understanding of the phenomena being observed and represents the motivation for developing probe metrology capability that can address LLNL's unique problems. Standing wave probes were developed for measuring high aspect ratio, micrometer scaled features with nanometer resolution. Originally conceived of for the use in the automotive industry for characterizing fuel injector bores and similar geometries, this concept was investigated and improved for use on geometries and materials important to LLNL needs within target fabrication. As part of the original project, detailed understanding of the probe dynamics and interactions with the surface of the sample was investigated. In addition, the upgraded system was utilized for measuring fuel injector bores and micro-lenses as a means of demonstrating capability. This report discusses the use of the standing wave probe for measuring features in low density foams, 55 mg/cc SiO{sub 2} and 982 mg/cc (%6 relative density) copper foam respectively. These two foam materials represent a difficult metrology challenge because of their material properties and surface topography. Traditional non-contact metrology systems such as normal incident interferometry and/or confocal microscopy have difficulty obtaining a signal from the relatively absorptive characteristics of these materials. In addition to the foam samples, a solid copper and plastic (Rexolite{trademark}) sample of similar geometry was measured with the standing wave probe as a reference for both conductive and dielectric materials.
Microscopic Description of Nuclear Fission Dynamics
A. S. Umar; V. E. Oberacker; J. A. Maruhn; P. -G. Reinhard
2010-03-22T23:59:59.000Z
We discuss possible avenues to study fission dynamics starting from a time-dependent mean-field approach. Previous attempts to study fission dynamics using the time-dependent Hartree-Fock (TDHF) theory are analyzed. We argue that different initial conditions may be needed to describe fission dynamics depending on the specifics of the fission phenomenon and propose various approaches towards this goal. In particular, we provide preliminary calculations for studying fission following a heavy-ion reaction using TDHF with a density contraint. Regarding prompt muon-induced fission, we also suggest a new approach for combining the time-evolution of the muonic wave function with a microscopic treatment of fission dynamics via TDHF.
Dynamical Bounds for Sturmian Schrödinger Operators
L. Marin
2009-06-10T23:59:59.000Z
The Fibonacci Hamiltonian, that is a Schr\\"{o}dinger operator associated to a quasiperiodical sturmian potential with respect to the golden mean has been investigated intensively in recent years. Damanik and Tcheremchantsev developed a method and find a non trivial dynamical upper bound for this model. In this paper, we use this method to generalize to a large family of Sturmian operators dynamical upper bounds and show at sufficently large coupling anomalous transport for operators associated to irrational number with a generic diophantine condition. As a counter example, we exhibit a pathological irrational number which do not verify this condition and show its associated dynamic exponent only has ballistic bound. Moreover, we establish a global lower bound for the lower box counting dimension of the spectrum that is used to obtain a dynamical lower bound for bounded density irrational numbers.
Causes and consequences of complex population dynamics in an annual plant, Cardamine pensylvanica
Crone, E.E.
1995-11-08T23:59:59.000Z
The relative importance of density-dependent and density-independent factors in determining the population dynamics of plants has been widely debated with little resolution. In this thesis, the author explores the effects of density-dependent population regulation on population dynamics in Cardamine pensylvanica, an annual plant. In the first chapter, she shows that experimental populations of C. pensylvanica cycled from high to low density in controlled constant-environment conditions. These cycles could not be explained by external environmental changes or simple models of direct density dependence (N{sub t+1} = f[N{sub t}]), but they could be explained by delayed density dependence (N{sub t+1} = f[N{sub t}, N{sub t+1}]). In the second chapter, she shows that the difference in the stability properties of population growth models with and without delayed density dependence is due to the presence of Hopf as well as slip bifurcations from stable to chaotic population dynamics. She also measures delayed density dependence due to effects of parental density on offspring quality in C. pensylvanica and shows that this is large enough to be the cause of the population dynamics observed in C. pensylvanica. In the third chapter, the author extends her analyses of density-dependent population growth models to include interactions between competing species. In the final chapter, she compares the effects of fixed spatial environmental variation and variation in population size on the evolutionary response of C. pensylvanica populations.
Reduced density matrix hybrid approach: Application to electronic energy transfer
Timothy C. Berkelbach; Thomas E. Markland; David R. Reichman
2011-11-21T23:59:59.000Z
Electronic energy transfer in the condensed phase, such as that occurring in photosynthetic complexes, frequently occurs in regimes where the energy scales of the system and environment are similar. This situation provides a challenge to theoretical investigation since most approaches are accurate only when a certain energetic parameter is small compared to others in the problem. Here we show that in these difficult regimes, the Ehrenfest approach provides a good starting point for a dynamical description of the energy transfer process due to its ability to accurately treat coupling to slow environmental modes. To further improve on the accuracy of the Ehrenfest approach, we use our reduced density matrix hybrid framework to treat the faster environmental modes quantum mechanically, at the level of a perturbative master equation. This combined approach is shown to provide an efficient and quantitative description of electronic energy transfer in a model dimer and the Fenna-Matthews-Olson complex and is used to investigate the effect of environmental preparation on the resulting dynamics.
First Results of the LHC Longitudinal Density Monitor
Jeff, A.; /CERN /Liverpool U.; Boccardi, A.; /CERN; Bravin, E.; /CERN; Fisher, A.S.; /SLAC; Lefevre, T.; /CERN; Rabiller, A.; /CERN; Roncarolo, F.; /CERN; Welsch, C.P.; /Liverpool U. /Cockcroft Inst. Accel. Sci. Tech.
2012-04-19T23:59:59.000Z
The Large Hadron Collider (LHC) at CERN is the world's largest particle accelerator. It is designed to accelerate and collide protons or heavy ions up to the center-of-mass energies of 14 TeV. Knowledge of the longitudinal distribution of particles is important for various aspects of accelerator operation, in particular to check the injection quality and to measure the proportion of charge outside the nominally filled bunches during the physics periods. In order to study this so-called ghost charge at levels very much smaller than the main bunches, a longitudinal profile measurement with a very high dynamic range is needed. A new detector, the LHC Longitudinal Density Monitor (LDM) is a single-photon counting system measuring synchrotron light by means of an avalanche photodiode detector. The unprecedented energies reached in the LHC allow synchrotron light diagnostics to be used with both protons and heavy ions. A prototype was installed during the 2010 LHC run and was able to longitudinally profile the whole ring with a resolution close to the target of 50 ps. On-line correction for the effects of the detector deadtime, pile-up and afterpulsing allow a dynamic range of 105 to be achieved. First measurements with the LDM are presented here along with an analysis of its performance and an outlook for future upgrades.
Hyperbolic Dynamics Todd Fisher
Fisher, Todd
Hyperbolic Dynamics Todd Fisher tfisher@math.umd.edu Department of Mathematics University of Maryland, College Park Hyperbolic Dynamics p. 1/3 #12;What is a dynamical system? Phase space X, elements possible states Hyperbolic Dynamics p. 2/3 #12;What is a dynamical system? Phase space X, elements
Dynamics of dendritic polymers in the bulk and under confinement
Chrissopoulou, K. [Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser, P.O. Box 1527, 711 10, Heraklion Crete (Greece); Fotiadou, S. [Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser, P.O. Box 1527, 711 10, Heraklion Crete, Greece and Aristotle University of Thessaloniki, Department of Chemical Engineering, Thessaloniki (Greece); Androulaki, K.; Anastasiadis, S. H. [Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser, P.O. Box 1527, 711 10, Heraklion Crete, Greece and University of Crete, Department of Chemistry, Heraklion Crete (Greece); Tanis, I.; Karatasos, K. [Aristotle University of Thessaloniki, Department of Chemical Engineering, Thessaloniki (Greece); Prevosto, D.; Labardi, M. [CNR-IPCF, Department of Physics, University of Pisa, Pisa (Italy); Frick, B. [ILL-Institut Laue-Langevin, Grenoble (France)
2014-05-15T23:59:59.000Z
The structure and dynamics of a hyperbranched polyesteramide (Hybrane® S 1200) polymer and its nanocomposites with natural montmorillonite (Na{sup +}-MMT) are investigated by XRD, DSC, QENS, DS and Molecular Dynamics (MD) simulation. In bulk, the energy-resolved elastically scattered intensity from the polymer exhibits two relaxation steps, one attributed to sub-T{sub g} motions and one observed at temperatures above the glass transition, T{sub g}. The QENS spectra measured over the complete temperature range are consistent with the elastic measurements and can be correlated to the results emerging from the detailed description afforded by the atomistic simulations, which predict the existence of three relaxation processes. Moreover, dielectric spectroscopy shows the sub- T{sub g} beta process as well as the segmental relaxation. For the nanocomposites, XRD reveals an intercalated structure for all hybrids with distinct interlayer distances due to polymer chains residing within the galleries of the Na{sup +}-MMT. The polymer chains confined within the galleries show similarities in the behavior with that of the polymer in the bulk for temperatures below the bulk polymer T{sub g}, whereas they exhibit frozen dynamics under confinement at temperatures higher than that.
Probability density adjoint for sensitivity analysis of the Mean of Chaos
Blonigan, Patrick J., E-mail: blonigan@mit.edu; Wang, Qiqi, E-mail: qiqi@mit.edu
2014-08-01T23:59:59.000Z
Sensitivity analysis, especially adjoint based sensitivity analysis, is a powerful tool for engineering design which allows for the efficient computation of sensitivities with respect to many parameters. However, these methods break down when used to compute sensitivities of long-time averaged quantities in chaotic dynamical systems. This paper presents a new method for sensitivity analysis of ergodic chaotic dynamical systems, the density adjoint method. The method involves solving the governing equations for the system's invariant measure and its adjoint on the system's attractor manifold rather than in phase-space. This new approach is derived for and demonstrated on one-dimensional chaotic maps and the three-dimensional Lorenz system. It is found that the density adjoint computes very finely detailed adjoint distributions and accurate sensitivities, but suffers from large computational costs.
Precise and Accurate Density Determination of Explosives Using Hydrostatic Weighing
B. Olinger
2005-07-01T23:59:59.000Z
Precise and accurate density determination requires weight measurements in air and water using sufficiently precise analytical balances, knowledge of the densities of air and water, knowledge of thermal expansions, availability of a density standard, and a method to estimate the time to achieve thermal equilibrium with water. Density distributions in pressed explosives are inferred from the densities of elements from a central slice.
The Microscopic Linear Dynamics
Penny, Will
The Microscopic Brain Will Penny Linear Dynamics Exponentials Matrix Exponential Eigendecomposition Dynamical Modes Nodes State Space Saddles Oscillations Spirals Centres Offsets Retinal Circuit Nullclines Stability Spiking Neurons Fitzhugh-Nagumo Nonlinear Dynamics Linearization Nonlinear Oscillation Excitable
Fabrication of low density ceramic material
Meek, T.T.; Blake, R.D.; Sheinberg, H.
1985-01-01T23:59:59.000Z
A precursor mixture and a method of making a low-density ceramic structural material are disclosed. The precursor mixture includes hollow microballoons, typically made of glass, together with a cementing agent capable of being cured by microwave irradiation. A preferred cementing agent is liquid hydrated potassium silicate, which is mixed with the glass microballoons to form a slurry. Upon irradiation the potassium silicate is dehydrated to form a solid porous matrix in which the microballoons are evenly distributed. Ground glass or other filling agents may be included in the slurry to enhance the properties of the final product. Low-density structural ceramics having densities on the order of 0.1 to 0.3 are obtained.
Statistical approach to nuclear level density
Sen'kov, R. A.; Horoi, M. [Department of Physics, Central Michigan University, Mount Pleasant, MI 48859 (United States); Zelevinsky, V. G. [Department of Physics and Astronomy and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824-1321 (United States)
2014-10-15T23:59:59.000Z
We discuss the level density in a finite many-body system with strong interaction between the constituents. Our primary object of applications is the atomic nucleus but the same techniques can be applied to other mesoscopic systems. We calculate and compare nuclear level densities for given quantum numbers obtained by different methods, such as nuclear shell model (the most successful microscopic approach), our main instrument - moments method (statistical approach), and Fermi-gas model; the calculation with the moments method can use any shell-model Hamiltonian excluding the spurious states of the center-of-mass motion. Our goal is to investigate statistical properties of nuclear level density, define its phenomenological parameters, and offer an affordable and reliable way of calculation.
High power density solid oxide fuel cells
Pham, Ai Quoc; Glass, Robert S.
2004-10-12T23:59:59.000Z
A method for producing ultra-high power density solid oxide fuel cells (SOFCs). The method involves the formation of a multilayer structure cells wherein a buffer layer of doped-ceria is deposited intermediate a zirconia electrolyte and a cobalt iron based electrode using a colloidal spray deposition (CSD) technique. For example, a cobalt iron based cathode composed of (La,Sr)(Co,Fe)O (LSCF) may be deposited on a zirconia electrolyte via a buffer layer of doped-ceria deposited by the CSD technique. The thus formed SOFC have a power density of 1400 mW/cm.sup.2 at 600.degree. C. and 900 mW/cm.sup.2 at 700.degree. C. which constitutes a 2-3 times increased in power density over conventionally produced SOFCs.
Density matrix of black hole radiation
Lasma Alberte; Ram Brustein; Andrei Khmelnitsky; A. J. M. Medved
2015-02-09T23:59:59.000Z
Hawking's model of black hole evaporation is not unitary and leads to a mixed density matrix for the emitted radiation, while the Page model describes a unitary evaporation process in which the density matrix evolves from an almost thermal state to a pure state. We compare a recently proposed model of semiclassical black hole evaporation to the two established models. In particular, we study the density matrix of the outgoing radiation and determine how the magnitude of the off-diagonal corrections differs for the three frameworks. For Hawking's model, we find power-law corrections to the two-point functions that induce exponentially suppressed corrections to the off-diagonal elements of the full density matrix. This verifies that the Hawking result is correct to all orders in perturbation theory and also allows one to express the full density matrix in terms of the single-particle density matrix. We then consider the semiclassical theory for which the corrections, being non-perturbative from an effective field-theory perspective, are much less suppressed and grow monotonically in time. In this case, the R\\'enyi entropy for the outgoing radiation is shown to grow linearly at early times; but this growth slows down and the entropy eventually starts to decrease at the Page time. In addition to comparing models, we emphasize the distinction between the state of the radiation emitted from a black hole, which is highly quantum, and that of the radiation emitted from a typical classical black body at the same temperature.
Dynamics of Kr in dense clathrate hydrates.
Klug, D. D.; Tse, J. S.; Zhao, J. Y.; Sturhahn, W.; Alp, E. E.; Tulk, C. A. (X-Ray Science Division); (National Research Council of Canada); (Univ. of Saskatchewan); (ORNL)
2011-01-01T23:59:59.000Z
The dynamics of Kr atoms as guests in dense clathrate hydrate structures are investigated using site specific {sup 83}Kr nuclear resonant inelastic x-ray scattering (NRIXS) spectroscopy in combination with molecular dynamics simulations. The dense structure H hydrate and filled-ice structures are studied at high pressures in a diamond anvil high-pressure cell. The dynamics of Kr in the structure H clathrate hydrate quench recovered at 77 K is also investigated. The Kr phonon density of states obtained from the experimental NRIXS data are compared with molecular dynamics simulations. The temperature and pressure dependence of the phonon spectra provide details of the Kr dynamics in the clathrate hydrate cages. Comparison with the dynamics of Kr atoms in the low-pressure structure II obtained previously was made. The Lamb-Mossbauer factor obtained from NRIXS experiments and molecular dynamics calculations are in excellent agreement and are shown to yield unique information on the strength and temperature dependence of guest-host interactions.
Low density, microcellular foams, preparation, and articles
Young, A.T.
1982-03-03T23:59:59.000Z
A microcellular low-density foam of poly(4-methyl-1-pentene) particularly useful for forming targets for inertial confinement fusion has been developed. Articles made from the foam have been machined to tolerances of 0.0001 inch, although the densities of the fragile foam are low (about 10 to about 100 mg/cc) and the cell sizes are small (about 10 to about 30 ..mu..m). Methods for forming the foam and articles are given. The yield strength of the foam of the invention is higher than was obtained in other structures of this same material.
Density functional theory study of (OCS)2^-
Bilalbegovic, G
2007-01-01T23:59:59.000Z
The structural and electronic properties of the carbonyl sulfide dimer anion are calculated using density functional theory within a pseudopotential method. Three geometries are optimized and investigated: C2v and C2 symmetric, as well as one asymmetric structure. A distribution of an excess charge in three isomers are studied by the Hirshfeld method. In an asymmetric (OCS)2^- isomer the charge is not equally divided between the two moieties, but it is distributed as OCS^{-0.6} OCS^{-0.4}. Low-lying excitation levels of three isomers are compared using the time-dependent density functional theory in the Casida approach.
Low density, microcellular foams, preparation, and articles
Young, Ainslie T. (Los Alamos, NM); Marsters, Robert G. (Jemez Springs, NM); Moreno, Dawn K. (Espanola, NM)
1984-01-01T23:59:59.000Z
A microcellular low density foam of poly(4-methyl-1-pentene) which is particularly useful for forming targets for inertial confinement fusion has been developed. Articles made from the foam have been machined to tolerances of 0.0001 inch, although the densities of the fragile foam are low (about 10 to about 100 mg/cc) and the cell sizes are small (about 10 to about 30 .mu.m). Methods for forming the foam and articles are given; and the yield strength of the foam of the invention is higher than was obtained in other structures of this same material.
Level densities of transitional Sm nuclei
Capote, R.; Ventura, A.; Cannata, F.; Quesada, J.M. [Nuclear Data Section, International Atomic Energy Agency, Vienna (Austria); Ente Nuove Tecnologie, Energia e Ambiente, and Istituto Nazionale di Fisica Nucleare, Bologna (Italy); Dipartimento di Fisica dell Universita and Istituto Nazionale di Fisica Nucleare, Bologna (Italy); Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla (Spain)
2005-06-01T23:59:59.000Z
Experimentally determined level densities of the transitional isotopes {sup 148,149,150,152}Sm at excitation energies below and around the neutron binding energy are compared with microcanonical calculations based on a Monte Carlo approach to noncollective level densities, folded with a collective enhancement estimated in the frame of the interacting boson model (IBM). The IBM parameters are adjusted so as to reproduce the low-lying discrete levels of both parities, with the exception of the odd-mass nucleus, {sup 149}Sm, where complete decoupling of the unpaired neutron from the core is assumed.
Error Analysis in Nuclear Density Functional Theory
Nicolas Schunck; Jordan D. McDonnell; Jason Sarich; Stefan M. Wild; Dave Higdon
2014-07-11T23:59:59.000Z
Nuclear density functional theory (DFT) is the only microscopic, global approach to the structure of atomic nuclei. It is used in numerous applications, from determining the limits of stability to gaining a deep understanding of the formation of elements in the universe or the mechanisms that power stars and reactors. The predictive power of the theory depends on the amount of physics embedded in the energy density functional as well as on efficient ways to determine a small number of free parameters and solve the DFT equations. In this article, we discuss the various sources of uncertainties and errors encountered in DFT and possible methods to quantify these uncertainties in a rigorous manner.
Leonard, T.; Lander, B.; Seifert, U. [II. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart (Germany)] [II. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart (Germany); Speck, T. [Institut für Theoretische Physik II, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf (Germany)] [Institut für Theoretische Physik II, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf (Germany)
2013-11-28T23:59:59.000Z
We discuss the stochastic thermodynamics of systems that are described by a time-dependent density field, for example, simple liquids and colloidal suspensions. For a time-dependent change of external parameters, we show that the Jarzynski relation connecting work with the change of free energy holds if the time evolution of the density follows the Kawasaki-Dean equation. Specifically, we study the work distributions for the compression and expansion of a two-dimensional colloidal model suspension implementing a practical coarse-graining scheme of the microscopic particle positions. We demonstrate that even if coarse-grained dynamics and density functional do not match, the fluctuation relations for the work still hold albeit for a different, apparent, change of free energy.
High power density supercapacitors using locally aligned carbon nanotube electrodes
Du, C S; Yeh, J; Pan, Ning
2005-01-01T23:59:59.000Z
4484/16/4/003 High power density supercapacitors usingproduced very high speci?c power density of about 30 kW kg ?manufacturing of high power density supercapacitors and
High-power-density spot cooling using bulk thermoelectrics
Zhang, Y; Shakouri, A; Zeng, G H
2004-01-01T23:59:59.000Z
model, the cooling power densities of the devices can alsothe cooling power densities 2–24 times. Experimentally, the14 4 OCTOBER 2004 High-power-density spot cooling using bulk
Maps of current density using density-functional methods A. Soncini,1,a
Helgaker, Trygve
, University of Durham, South Road, Durham DH1 3LE, United Kingdom Received 22 May 2008; accepted 17 July 2008 are compared and integration of the current densities to yield shielding constants is performed. In general of induced current density in molecules. © 2008 American Institute of Physics. DOI: 10.1063/1.2969104 I
On the Determination of the Mean Cosmic Matter Density and the Amplitude of Density Fluctuations
Thomas H. Reiprich
2002-07-02T23:59:59.000Z
The cosmological implications from a new estimate of the local X-ray galaxy cluster abundance are summarized. The results are then compared to independent observations. It is suggested that `low' values for the mean cosmic matter density and the amplitude of mass density fluctuations currently do not appear unreasonable observationally.
Sergey Yakovlev
2011-12-22T23:59:59.000Z
In the work's considered density of vacuum energy and dynamic of scalar field in multidimensional theory with cosmological constant. Using method of N.N.Bogolubov coefficients, was gotten expression for influence of anisotropic metric to vacuum energy. Obtained the effective mass of massles scalar field, that depends on cosmological constant, and some general theoretical results concerning arising of particles in the model.
Chu, Shih-I
2013-01-01T23:59:59.000Z
-correlation potential which proved accurate in calculations of unperturbed electronic structure of Ar. Calculations is, not including dynamic response of the electron density) differ significantly from those obtained [24]. Electronic structure of atoms and molecules can be encoded in the HHG signal; the latter may
Mixing Water and Oil Under Static High Pressure H.K. Ploeg1, M.D. McCluskey2,3, G.J. Hanna2,3
Collins, Gary S.
Mixing Water and Oil Under Static High Pressure H.K. Ploeg1, M.D. McCluskey2,3, G.J. Hanna2,3 1The and O. Grasset, Journal of Chemical Physics 127, 124506 (2007) Citations: Water in Oil: Procedure: ·The initial experiment was to see a drop of water freeze to ice VI while surrounded by mineral oil
McCluskey, Matthew
985 PHASE SEPARATION IN InGaN/GaN MULTIPLE QUANTUM WELLS M.D. MCCLUSKEY *, L.T. ROMANO *, B0.27Ga0.73N/GaN multiple quantum wells (MQW's). After annealing for 4 min at a temperature of 1100 o is attributed to the formation of In- rich InGaN phases in the active region. X-ray diffraction measurements
McCluskey, Matthew
DISORDERING OF InGaN/GaN SUPERLATTICES AFTER HIGH-PRESSURE ANNEALING M.D. McCluskey*, L.T. Romano Internet J. Nitride Semicond. Res. 4S1, G3.42 (1999) ABSTRACT Interdiffusion of In and Ga is observed in InGaN of up to 15 kbar were applied during the annealing treatments to prevent decomposition of the InGaN
Energy transport in stochastically perturbed lattice dynamics
Giada Basile; Stefano Olla; Herbert Spohn
2008-09-12T23:59:59.000Z
We consider lattice dynamics with a small stochastic perturbation of order ? and prove that for a space-time scale of order \\varepsilon\\^-1 the local spectral density (Wigner function) evolves according to a linear transport equation describing inelastic collisions. For an energy and momentum conserving chain the transport equation predicts a slow decay, as 1/\\sqrt{t}, for the energy current correlation in equilibrium. This is in agreement with previous studies using a different method.
Theoretical Electron Density Distributions for Fe- and Cu-Sulfide...
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Electron Density Distributions for Fe- and Cu-Sulfide Earth Materials: A Connection between Bond Length, Bond Theoretical Electron Density Distributions for Fe- and Cu-Sulfide...
Effects of Ambient Density and Temperature on Soot Formation...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Density and Temperature on Soot Formation under High-EGR Conditions Effects of Ambient Density and Temperature on Soot Formation under High-EGR Conditions Presentation given at...
Mitigating Breakdown in High Energy Density Perovskite Polymer...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Mitigating Breakdown in High Energy Density Perovskite Polymer Nanocomposite Capacitors Mitigating Breakdown in High Energy Density Perovskite Polymer Nanocomposite Capacitors 2012...
Real-Time Simultaneous Measurements of Size, Density, and Composition...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
of Size, Density, and Composition of Single Ultrafine Diesel Tailpipe Particles Real-Time Simultaneous Measurements of Size, Density, and Composition of Single Ultrafine Diesel...
TEMPO-based Catholyte for High Energy Density Nonaqueous Redox...
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TEMPO-based Catholyte for High Energy Density Nonaqueous Redox Flow Batteries. TEMPO-based Catholyte for High Energy Density Nonaqueous Redox Flow Batteries. Abstract: We will...
BUILDING A UNIVERSAL NUCLEAR ENERGY DENSITY FUNCTIONAL (UNEDF...
Office of Scientific and Technical Information (OSTI)
Technical Report: BUILDING A UNIVERSAL NUCLEAR ENERGY DENSITY FUNCTIONAL (UNEDF) Citation Details In-Document Search Title: BUILDING A UNIVERSAL NUCLEAR ENERGY DENSITY FUNCTIONAL...
Pauling bond strength, bond length and electron density distribution...
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Pauling bond strength, bond length and electron density distribution. Pauling bond strength, bond length and electron density distribution. Abstract: A power law regression...
Density Functional Theory Study of Oxygen Reduction Activity...
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Density Functional Theory Study of Oxygen Reduction Activity on Ultrathin Platinum Nanotubes. Density Functional Theory Study of Oxygen Reduction Activity on Ultrathin Platinum...
A Density Functional Theory Study of Formaldehyde Adsorption...
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Density Functional Theory Study of Formaldehyde Adsorption on Ceria. A Density Functional Theory Study of Formaldehyde Adsorption on Ceria. Abstract: Molecular adsorption of...
Engineering Density of States of Earth Abundant Semiconductors...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Density of States of Earth Abundant Semiconductors for Enhanced Thermoelectric Power Factor Engineering Density of States of Earth Abundant Semiconductors for Enhanced...
Using Radio Waves to Control Fusion Plasma Density
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Using Radio Waves to Control Fusion Plasma Density Using Radio Waves to Control Fusion Plasma Density Simulations Run at NERSC Support Fusion Experiments at MIT, General Atomics...
High Energy Density Laboratory Plasmas Program | National Nuclear...
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Photo Gallery Jobs Apply for Our Jobs Our Jobs Working at NNSA Blog Home High Energy Density Laboratory Plasmas Program High Energy Density Laboratory Plasmas Program...
DIAGNOSTICS FOR ION BEAM DRIVEN HIGH ENERGY DENSITY PHYSICS EXPERIMENTS
Bieniosek, F.M.
2010-01-01T23:59:59.000Z
for high energy density physics and fusion applications,IFSA 2007, Journal of Physics, Conference Series 112 (2008)high energy density physics experiments F. M. Bieniosek, E.
Estimating density of Florida Key deer
Roberts, Clay Walton
2006-08-16T23:59:59.000Z
for this species since 1968; however, a need to evaluate the precision of existing and alternative survey methods (i.e., road counts, mark-recapture, infrared-triggered cameras [ITC]) was desired by USFWS. I evaluated density estimates from unbaited ITCs and road...
Lipoprotein subclass analysis by immunospecific density
Lester, Sandy Marie
2009-05-15T23:59:59.000Z
Separation of Lipoprotein Particles by Single Spin Ultracentrifugation ......................................................................... 27 Layering Ultracentrifugation Tubes ............................................... 28 Digital..., and HDL. (Fig 4) 14 As one moves down the Ultracentrifugation (UC) tube, the density increases and the particle size decreases from chylomicrons to HDL. The lipoprotein fractions also differ in lipid to protein ratios, apolipoprotein...
Effective Field Theory and Finite Density Systems
R. J. Furnstahl; G. Rupak; T. Schaefer
2008-01-04T23:59:59.000Z
This review gives an overview of effective field theory (EFT) as applied at finite density, with a focus on nuclear many-body systems. Uniform systems with short-range interactions illustrate the ingredients and virtues of many-body EFT and then the varied frontiers of EFT for finite nuclei and nuclear matter are surveyed.
Density-Functional Theory for Complex Fluids
Wu, Jianzhong
. This generic methodology is built upon a mathematical theorem that states, for an equilibrium system at a given modeling of the microscopic struc- tures and phase behavior of soft-condensed matter. The methodol- ogy to the one-body density profile Grand potential: the free energy of an open system at fixed volume
Population density of San Joaquin kit fox
McCue, P.; O'Farrell, T.P.; Kato, T.; Evans, B.G.
1982-01-01T23:59:59.000Z
Populations of the endangered San Joaquin kit fox, vulpes macrotis mutica, are known to occur on the Elk Hills Naval Petroleum Reserve No. 1. This study assess the impact of intensified petroleum exploration and production and associated human activities on kit fox population density. (ACR)
ADAPTIVE DENSITY ESTIMATION WITH MASSIVE DATA SETS
Scott, David W.
recognition, density estima tion, and data visualization. However, one already hears stories of logistic the data, and some require the data to be in core. 1.1 Reversing Efficiency Roles What general solution can we propose? It is our po sition that massive data sets reverse our usual focus This research
Photovoltaic retinal prosthesis with high pixel density
Palanker, Daniel
Photovoltaic retinal prosthesis with high pixel density Keith Mathieson1,4 , James Loudin1 to stimulating electrodes via intraocular cables. We present a photovoltaic subretinal prosthesis, in which pixel, demonstrating the possibility of a fully integrated photovoltaic retinal prosthesis with high
Durable high-density data storage
Stutz, R.A.; Lamartine, B.C.
1996-09-01T23:59:59.000Z
This paper will discuss the Focus Ion Beam (FIB) milling process, media life considerations, and methods of reading the micromilled data. The FIB process for data storage provides a new non-magnetic storage method for archiving large amounts of data. The process stores data on robust materials such as steel, silicon, and gold coated silicon. The storage process was developed to provide a method to insure the long term storage life of data. We estimate the useful life of data written on silicon or gold coated silicon to be a few thousand years. The process uses an ion beam to carve material from the surface much like stone cutting. The deeper information is carved into the media the longer the expected life of the information. The process can read information in three formats: (1) binary at densities of 3.5 Gbits/cm{sup 2}, (2) alphanumeric at optical or non-optical density, and (3) graphical at optical and non-optical density. The formats can be mixed on the same media; and thus it is possible to record, in a human readable format, instructions that can be read using an optical microscope. These instructions provide guidance on reading the higher density information.
Density Functional Theory Models for Radiation Damage
Density Functional Theory Models for Radiation Damage S.L. Dudarev EURATOM/CCFE Fusion Association and informative as the most advanced experimental techniques developed for the observation of radiation damage investigation and assessment of radiation damage effects, offering new insight into the origin of temperature
High power density thermophotovoltaic energy conversion
Noreen, D.L. [R& D Technologies, Inc., Hoboken, New Jersey 07030 (United States); Du, H. [Department of Materials Science and Engineering, Stevens Institute of Technology, Hoboken, New Jersey 07030 (United States)
1995-01-05T23:59:59.000Z
R&D Technologies is developing thermophotovoltaic (TPV) technology based on the use of porous/fibrous ceramic broadband-type emitter designs that utilize recuperative or regenerative techniques to improve thermal efficiency and power density. This paper describes preliminary estimates of what will be required to accomplish sufficient power density to develop a practical, commercially-viable TPV generator. It addresses the needs for improved, thermal shock-resistant, long-life porous/fibrous ceramic emitters and provides information on the photocell technology required to achieve acceptable power density in broadband-type (with selective filter) TPV systems. TPV combustors/systems operating at a temperature of 1500 {degree}C with a broadband-type emitter is proposed as a viable starting point for cost-effective TPV conversion. Based on current projections for photocell cost, system power densities of 7.5--10 watts per square centimeter of emitter area will be required for TPV to become a commercially viable technology. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.
Stochastic dynamics of collective modes for Brownian dipoles
Leticia F. Cugliandolo; Pierre-Michel Déjardin; Gustavo S. Lozano; Frédéric van Wijland
2014-12-19T23:59:59.000Z
The individual motion of a colloidal particle is described by an overdamped Langevin equation. When rotational degrees of freedom are relevant, these are described by a corresponding Langevin process. Our purpose is to show that the microscopic local density of colloids, in terms of a space and rotation state, also evolves according to a Langevin equation. The latter can then be used as the starting point of a variety of approaches, ranging from dynamical density functional theory to mode-coupling approximations.
Lapeyre, Guillaume
Dynamics of the Upper Oceanic Layers in Terms of Surface Quasigeostrophy Theory G. LAPEYRE AND P dynamics for nonlinear baroclinically unstable flows is examined using the concepts of potential vorticity density anomalies. Then, using the invertibility of potential vorticity, the dynamics are decomposed
?Linear Gas Jet with Tailored Density Profile"
KRISHNAN, Mahadevan
2012-12-10T23:59:59.000Z
Supersonic, highly collimated gas jets and gas-filled capillary discharge waveguides are two primary targets of choice for Laser Plasma Accelerators (LPA) . Present gas jets have lengths of only 2-4 mm at densities of 1-4E19 cm-3, sufficient for self trapping and electron acceleration to energies up to ~150 MeV. Capillary structures 3 cm long have been used to accelerate beams up to 1 GeV. Capillary discharges used in LPAs serve to guide the pump laser and optimize the energy gain. A wall-stabilized capillary discharge provides a transverse profile across the channel that helps guide the laser and combat diffraction. Gas injection via a fast nozzle at one end provides some longitudinal density control, to improve the coupling. Gas jets with uniform or controlled density profiles may be used to control electron bunch injection and are being integrated into capillary experiments to add tuning of density. The gas jet for electron injection has not yet been optimized. Our Ph-I results have provided the LPA community with an alternative path to realizing a 2-3GeV electron bunch using just a gas jet. For example, our slit/blade combination gives a 15-20mm long acceleration path with tunable density profile, serving as an alternative to a 20-mm long capillary discharge with gas injection at one end. In Ph-II, we will extend these results to longer nozzles, to see whether we can synthesize 30 or 40-mm long plasma channels for LPAs.
Wide range equation of state for fluid hydrogen from density functional theory
Wang, Cong; Zhang, Ping [Institute of Applied Physics and Computational Mathematics, P.O. Box 8009, Beijing 100088 (China) [Institute of Applied Physics and Computational Mathematics, P.O. Box 8009, Beijing 100088 (China); Center for Applied Physics and Technology, Peking University, Beijing 100871 (China)
2013-09-15T23:59:59.000Z
Wide range equation of state (EOS) for liquid hydrogen is ultimately obtained by combining two kinds of density functional theory (DFT) molecular dynamics simulations, namely, first-principles molecular dynamics simulations and orbital-free molecular dynamics simulations. Specially, the present introduction of short cutoff radius pseudopotentials enables the EOS to be available in the range from 9.82 × 10{sup ?4} to 1.347 × 10{sup 3} g/cm{sup 3} and up to 5 × 10{sup 7} K. By comprehensively comparing with various attainable experimental and theoretical data, we derive the conclusion that our DFT-EOS can be readily and reliably applied to hydrodynamic simulations of the inertial confinement fusion.
E-Cloud Effects on Singe-Bunch Dynamics in the Proposed PS2
Venturini, M.
2012-01-01T23:59:59.000Z
E-CLOUD EFFECTS ON SINGLE-BUNCH DYNAMICS IN THE PROPOSEDsynchrotron. Electron cloud effects represent an impor- tantaiming at estimating the e-cloud density thresholds for the
Dynamic First-Principles Molecular-Scale Model for Solid Oxide Fuel Cells V. Hugo Schmidt
Dynamic First-Principles Molecular-Scale Model for Solid Oxide Fuel Cells V. Hugo Schmidt vs. current density i characteristics applies both to the Solid Oxide Fuel Cell (SOFC) and Solid
Mapping molecular dynamics computations to hypercubes
Lakamsani, Vamsee Krishna
1993-01-01T23:59:59.000Z
made at applying these methods to real problems. In this thesis, the missing fink between the mapping research in computer science and application implementation research is provided by adapting MD computations to an efficient mapping algorithm called...
Zeghib, Abdelghani
Dynamics on Lorentz manifolds Abdelghani Zeghib Introduction Motivations and questions Examples Results Results Previous results Linear Dynamics General considerations Furstenberg Lemma Lorentz Dynamics://www.umpa.ens-lyon.fr/~zeghib/ (joint work with Paolo Piccione) #12;Dynamics on Lorentz manifolds Abdelghani Zeghib Introduction
LaCasce, Joseph H.
Introduction Basic dynamics The Gulf Stream The thermohaline circulation Ocean currents: some misconceptions and some dynamics Joe LaCasce Dept. Geosciences October 30, 2012 Joe LaCasce Dept. Geosciences Ocean currents: some misconceptions and some dynamics #12;Introduction Basic dynamics The Gulf Stream
A new Lagrangian dynamic reduction in field theory
François Gay-Balmaz; Tudor S. Ratiu
2014-07-01T23:59:59.000Z
For symmetric classical field theories on principal bundles there are two methods of symmetry reduction: covariant and dynamic. Assume that the classical field theory is given by a symmetric covariant Lagrangian density defined on the first jet bundle of a principal bundle. It is shown that covariant and dynamic reduction lead to equivalent equations of motion. This is achieved by constructing a new Lagrangian defined on an infinite dimensional space which turns out to be gauge group invariant.
Lower crustal density estimation using the density-slowness relationship: a preliminary study
Jones, Gary Wayne
1996-01-01T23:59:59.000Z
, and seismic velocity models were used to estimate the densities of th lower crustal rocks frcm the Wind River Mountains, the Ivrea Zone in Italy, and the average 1~ continental crustal model developed b/ ~istensen and Mconey [1995] . The. densities... by Carlson and Raskin [1984) yields a precision of about 1 percent. 'Ihe objective of this study is to evaluate this approach to estimate the density of the more complex continental crust, which is more variable in composition and affected hy a wider range...
Density equalizing map projections: A new algorithm
Merrill, D.W.; Selvin, S.; Mohr, M.S.
1992-02-01T23:59:59.000Z
In the study of geographic disease clusters, an alternative to traditional methods based on rates is to analyze case locations on a transformed map in which population density is everywhere equal. Although the analyst`s task is thereby simplified, the specification of the density equalizing map projection (DEMP) itself is not simple and continues to be the subject of considerable research. Here a new DEMP algorithm is described, which avoids some of the difficulties of earlier approaches. The new algorithm (a) avoids illegal overlapping of transformed polygons; (b) finds the unique solution that minimizes map distortion; (c) provides constant magnification over each map polygon; (d) defines a continuous transformation over the entire map domain; (e) defines an inverse transformation; (f) can accept optional constraints such as fixed boundaries; and (g) can use commercially supported minimization software. Work is continuing to improve computing efficiency and improve the algorithm.
Density equalizing map projections: A new algorithm
Merrill, D.W.; Selvin, S.; Mohr, M.S.
1992-02-01T23:59:59.000Z
In the study of geographic disease clusters, an alternative to traditional methods based on rates is to analyze case locations on a transformed map in which population density is everywhere equal. Although the analyst's task is thereby simplified, the specification of the density equalizing map projection (DEMP) itself is not simple and continues to be the subject of considerable research. Here a new DEMP algorithm is described, which avoids some of the difficulties of earlier approaches. The new algorithm (a) avoids illegal overlapping of transformed polygons; (b) finds the unique solution that minimizes map distortion; (c) provides constant magnification over each map polygon; (d) defines a continuous transformation over the entire map domain; (e) defines an inverse transformation; (f) can accept optional constraints such as fixed boundaries; and (g) can use commercially supported minimization software. Work is continuing to improve computing efficiency and improve the algorithm.
Ultra-high density diffraction grating
Padmore, Howard A.; Voronov, Dmytro L.; Cambie, Rossana; Yashchuk, Valeriy V.; Gullikson, Eric M.
2012-12-11T23:59:59.000Z
A diffraction grating structure having ultra-high density of grooves comprises an echellette substrate having periodically repeating recessed features, and a multi-layer stack of materials disposed on the echellette substrate. The surface of the diffraction grating is planarized, such that layers of the multi-layer stack form a plurality of lines disposed on the planarized surface of the structure in a periodical fashion, wherein lines having a first property alternate with lines having a dissimilar property on the surface of the substrate. For example, in one embodiment, lines comprising high-Z and low-Z materials alternate on the planarized surface providing a structure that is suitable as a diffraction grating for EUV and soft X-rays. In some embodiments, line density of between about 10,000 lines/mm to about 100,000 lines/mm is provided.
Current density fluctuations and ambipolarity of transport
Shen, W.; Dexter, R.N.; Prager, S.C.
1991-10-01T23:59:59.000Z
The fluctuation in the plasma current density is measured in the MIST reversed field pinch experiment. Such fluctuations, and the measured radial profile of the k spectrum of magnetic fluctuations, supports the view and that low frequency fluctuations (f < 30 kHz) are tearing modes and high frequency fluctuations (30 kHz < f < 250 kHz) are localized turbulence in resonance with the local equilibrium magnetic field (i.e., k {center dot} B = 0). Correlation of current density and magnetic fluctuations (< {tilde j}{parallel}{tilde B}{sub r} >) demonstrates that radial particle transport from particle motion parallel to a fluctuating magnetic field is ambipolar over the full frequency range.
Current density fluctuations and ambipolarity of transport
Shen, W.; Dexter, R.N.; Prager, S.C.
1991-10-01T23:59:59.000Z
The fluctuation in the plasma current density is measured in the MIST reversed field pinch experiment. Such fluctuations, and the measured radial profile of the k spectrum of magnetic fluctuations, supports the view and that low frequency fluctuations (f < 30 kHz) are tearing modes and high frequency fluctuations (30 kHz < f < 250 kHz) are localized turbulence in resonance with the local equilibrium magnetic field (i.e., k {center_dot} B = 0). Correlation of current density and magnetic fluctuations (< {tilde j}{parallel}{tilde B}{sub r} >) demonstrates that radial particle transport from particle motion parallel to a fluctuating magnetic field is ambipolar over the full frequency range.
Ion Density Deviations in Semipermeable Ionic Microcapsules
Qiyun Tang; Alan R. Denton
2015-07-07T23:59:59.000Z
By implementing the nonlinear Poisson-Boltzmann theory in a cell model, we theoretically investigate the influence of polyelectrolye gel permeability on ion densities and pH deviations inside the cavities of ionic microcapsules. Our calculations show that variations in permeability of a charged capsule shell cause a redistribution of ion densities within the capsule, which ultimately affects the pH deviation and Donnan potential induced by the electric field of the shell. We find that semipermeable capsules can induce larger pH deviations inside their cavities that can permeable capsules. Furthermore, with increasing capsule charge, the influence of permeability on pH deviations progressively increases. Our theory, while providing a self-consistent method for modeling the influence of permeability on fundamental properties of ionic microgels, makes predictions of practical significance for the design of microcapsules loaded with fluorescent dyes, which can serve as biosensors for diagnostic purposes.
Transactions Dynamic Article Links
-density solids have been utilized in catalysis,18,19 gas storage,20 and chemical separations,21 where their large
Fiber felts as low density structural materials
Milewski, J.V.; Newfield, S.E.
1981-01-01T23:59:59.000Z
Short fiber felts structures can be made which provide improvements in properties over foams. In applications where resistance to compression set or stress relaxation are important, bonded fiber felts excel due to the flexing of individual fibers within their elastic limit. Felts of stainless steel and polyester fibers were prepared by deposition from liquid slurries. Compressive properties were determined as a function of felt parent material, extent of bonding, felt density, and length-to-diameter (L/D) ratio of starting fibers.
Nuclear fission in covariant density functional theory
A. V. Afanasjev; H. Abusara; P. Ring
2013-09-12T23:59:59.000Z
The current status of the application of covariant density functional theory to microscopic description of nuclear fission with main emphasis on superheavy nuclei (SHN) is reviewed. The softness of SHN in the triaxial plane leads to an emergence of several competing fission pathes in the region of the inner fission barrier in some of these nuclei. The outer fission barriers of SHN are considerably affected both by triaxiality and octupole deformation.
Update of axion CDM energy density
Huh, Ji-Haeng [Department of Physics and Astronomy and Center for Theoretical Physics, Seoul National University, Seoul 151-747 (Korea, Republic of)
2008-11-23T23:59:59.000Z
We update cosmological bound on axion model. The contribution from the anharmonic effect and the newly introduced initial overshoot correction are considered. We present an explicit formula for the axion relic density in terms of the QCD scale {lambda}{sub QCD}, the current quark masses m{sub q}'s and the Peccei-Quinn scale F{sub a}, including firstly introduced 1.85 factor which is from the initial overshoot.
Optimally focused cold atom systems obtained using density-density correlations
Putra, Andika; Campbell, Daniel L.; Price, Ryan M.; Spielman, I. B. [Joint Quantum Institute, University of Maryland and National Institute of Standards and Technology, College Park, Maryland 20742 (United States)] [Joint Quantum Institute, University of Maryland and National Institute of Standards and Technology, College Park, Maryland 20742 (United States); De, Subhadeep [Joint Quantum Institute, University of Maryland and National Institute of Standards and Technology, College Park, Maryland 20742 (United States) [Joint Quantum Institute, University of Maryland and National Institute of Standards and Technology, College Park, Maryland 20742 (United States); CSIR-National Physical Laboratory, New Delhi 110012 (India)
2014-01-15T23:59:59.000Z
Resonant absorption imaging is a common technique for detecting the two-dimensional column density of ultracold atom systems. In many cases, the system's thickness along the imaging direction greatly exceeds the imaging system's depth of field, making the identification of the optimally focused configuration difficult. Here we describe a systematic technique for bringing Bose-Einstein condensates (BEC) and other cold-atom systems into an optimal focus even when the ratio of the thickness to the depth of field is large: a factor of 8 in this demonstration with a BEC. This technique relies on defocus-induced artifacts in the Fourier-transformed density-density correlation function (the power spectral density, PSD). The spatial frequency at which these artifacts first appear in the PSD is maximized on focus; the focusing process therefore both identifies and maximizes the range of spatial frequencies over which the PSD is uncontaminated by finite-thickness effects.
Interfacial Ionic Liquids: Connecting Static and Dynamic Structures
Ahmet Uysal; Hua Zhou; Guang Feng; Sang Soo Lee; Song Li; Peter T. Cummings; Pasquale F. Fulvio; Sheng Dai; John K. McDonough; Yury Gogotsi; Paul Fenter
2014-12-06T23:59:59.000Z
It is well-known that room temperature ionic liquids (RTILs) often adopt a charge-separated layered structure, i.e., with alternating cation- and anion-rich layers, at electrified interfaces. However, the dynamic response of the layered structure to temporal variations in applied potential is not well understood. We used in situ, real-time X-ray reflectivity (XR) to study the potential-dependent electric double layer (EDL) structure of an imidazolium-based RTIL on charged epitaxial graphene during potential cycling as a function of temperature. The results suggest that the graphene-RTIL interfacial structure is bistable in which the EDL structure at any intermediate potential can be described by the combination of two extreme-potential structures whose proportions vary depending on the polarity and magnitude of the applied potential. This picture is supported by the EDL structures obtained by fully atomistic molecular dynamics (MD) simulations at various static potentials. The potential-driven transition between the two structures is characterized by an increasing width but with an approximately fixed hysteresis magnitude as a function of temperature. The results are consistent with the coexistence of distinct anion and cation adsorbed structures separated by an energy barrier (~0.15 eV).
Maruyama, Shigeo
Mode Projection(NMP)(17,18,20,21) Spectral Energy Density (SED)(22) LDeMDu u'MDu' 1 Fig. 1 Flow chart[(8)] 22 0 )( 1 )( f (8) k(22) Fig. 3 Flow chart of the lattice dynamics method. 1 2 3 4 5 6 7 8 9 methods using normal mode projection and spectral energy density. By performing the calculations
Design for a Longitudinal Density Monitor for the LHC
Jeff, Adam; /CERN; Bart Pedersen, Stephane; /CERN; Boccardi, Andrea; /CERN; Bravin, Enrico; /CERN; Lefevre, Thibaut; /CERN; Rabiller, Aurelie; /CERN; Roncarolo, Federico; /CERN; Fisher, Alan; /SLAC; Welsch, Carsten; /Liverpool U.
2012-07-13T23:59:59.000Z
Synchrotron radiation is currently used on the LHC for beam imaging and for monitoring the proton population in the 3 microsecond abort gap. In addition to these existing detectors, a study has been initiated to provide longitudinal density profiles of the LHC beams with a high dynamic range and a 50ps time resolution. This would allow for the precise measurement both of the bunch shape and the number of particles in the bunch tail or drifting into ghost bunches. A solution is proposed based on counting synchrotron light photons with two fast avalanche photo-diodes (APD) operated in Geiger mode. One is free-running but heavily attenuated and can be used to measure the core of the bunch. The other is much more sensitive, for measurement of the bunch tails, but must be gated off during the passage of the bunch to prevent the detector from being swamped. An algorithm is then applied to combine the two measurements and correct for the detector dead-time, afterpulsing and pile-up effects. Initial results from laboratory testing of this system are described here.
Relaxation dynamics in a binary hard-ellipse liquid
Wen-Sheng Xu; Zhao-Yan Sun; Li-Jia An
2014-12-01T23:59:59.000Z
Structural relaxation in binary hard spherical particles has been shown recently to exhibit a wealth of remarkable features when size disparity or mixture's composition is varied. In this paper, we test whether or not similar dynamical phenomena occur in glassy systems composed of binary hard ellipses. We demonstrate via event-driven molecular dynamics simulation that a binary hard-ellipse mixture with an aspect ratio of two and moderate size disparity displays characteristic glassy dynamics upon increasing density in both the translational and the rotational degrees of freedom. The rotational glass transition density is found to be close to the translational one for the binary mixtures investigated. More importantly, we assess the influence of size disparity and mixture's composition on the relaxation dynamics. We find that an increase of size disparity leads, both translationally and rotationally, to a speed up of the long-time dynamics in the supercooled regime so that both the translational and the rotational glass transition shift to higher densities. By increasing the number concentration of the small particles, the time evolution of both translational and rotational relaxation dynamics at high densities displays two qualitatively different scenarios, i.e., both the initial and the final part of the structural relaxation slow down for small size disparity, while the short-time dynamics still slows down but the final decay speeds up in the binary mixture with large size disparity. These findings are reminiscent of those observed in binary hard spherical particles. Therefore, our results suggest a universal mechanism for the influence of size disparity and mixture's composition on the structural relaxation in both isotropic and anisotropic particle systems.
Dynamical Friction on extended perturbers
O. Esquivel; B. Fuchs
2008-04-01T23:59:59.000Z
Following a wave-mechanical treatment we calculate the drag force exerted by an infinite homogeneous background of stars on a perturber as this makes its way through the system. We recover Chandrasekhar's classical dynamical friction (DF) law with a modified Coulomb logarithm. We take into account a range of models that encompasses all plausible density distributions for satellite galaxies by considering the DF exerted on a Plummer sphere and a perturber having a Hernquist profile. It is shown that the shape of the perturber affects only the exact form of the Coulomb logarithm. The latter converges on small scales, because encounters of the test and field stars with impact parameters less than the size of the massive perturber become inefficient. We confirm this way earlier results based on the impulse approximation of small angle scatterings.
Dynamical Friction on extended perturbers
Esquivel, O
2008-01-01T23:59:59.000Z
Following a wave-mechanical treatment we calculate the drag force exerted by an infinite homogeneous background of stars on a perturber as this makes its way through the system. We recover Chandrasekhar's classical dynamical friction (DF) law with a modified Coulomb logarithm. We take into account a range of models that encompasses all plausible density distributions for satellite galaxies by considering the DF exerted on a Plummer sphere and a perturber having a Hernquist profile. It is shown that the shape of the perturber affects only the exact form of the Coulomb logarithm. The latter converges on small scales, because encounters of the test and field stars with impact parameters less than the size of the massive perturber become inefficient. We confirm this way earlier results based on the impulse approximation of small angle scatterings.
Fanarraga, M.L. [Departamentos de Biologia Molecular, Universidad de Cantabria, IFIMAV. Herrera Oria s/n. 39011, Santander (Spain)], E-mail: fanarrag@unican.es; Villegas, J.C. [Anatomia y Biologia Celular, Universidad de Cantabria, IFIMAV. Herrera Oria s/n. 39011, Santander (Spain); Carranza, G.; Castano, R.; Zabala, J.C. [Departamentos de Biologia Molecular, Universidad de Cantabria, IFIMAV. Herrera Oria s/n. 39011, Santander (Spain)
2009-02-01T23:59:59.000Z
Microglia are highly dynamic cells of the CNS that continuously survey the welfare of the neural parenchyma and play key roles modulating neurogenesis and neuronal cell death. In response to injury or pathogen invasion parenchymal microglia transforms into a more active cell that proliferates, migrates and behaves as a macrophage. The acquisition of these extra skills implicates enormous modifications of the microtubule and actin cytoskeletons. Here we show that tubulin cofactor B (TBCB), which has been found to contribute to various aspects of microtubule dynamics in vivo, is also implicated in microglial cytoskeletal changes. We find that TBCB is upregulated in post-lesion reactive parenchymal microglia/macrophages, in interferon treated BV-2 microglial cells, and in neonate amoeboid microglia where the microtubule densities are remarkably low. Our data demonstrate that upon TBCB downregulation both, after microglia differentiation to the ramified phenotype in vivo and in vitro, or after TBCB gene silencing, microtubule densities are restored in these cells. Taken together these observations support the view that TBCB functions as a microtubule density regulator in microglia during activation, and provide an insight into the understanding of the complex mechanisms controlling microtubule reorganization during microglial transition between the amoeboid, ramified, and reactive phenotypes.
Optimizing MLC-based STT-RAM Caches by Dynamic Block Size Reconfiguration
Wong, Weng Fai
Optimizing MLC-based STT-RAM Caches by Dynamic Block Size Reconfiguration Jianxing Wang, Pooja Roy that MLC STT-RAM can achieve 2× the storage density of SLC and thus improves system performance. In this paper, we propose an architectural design to dynamically reconfigure the cache block size for a MLC STT
Iyengar, Srinivasan S.
electronic structure calculations (at the level of density functional theory, Hartree-Fock, post- Hartree approach to treat the simultaneous dynamics of electrons and nuclei. The method is based on a synergy-H-Cl]- and [CH3-H-Cl]- along with simultaneous dynamical treatment of the electrons and classical nuclei, through
A STUDY OF COMPUTATIONAL FLUID DYNAMICS APPLIED TO ROOM AIR FLOW
for supplying me a copy of his three-dimensional, laminar, constant density fluid flow computer program, whichi A STUDY OF COMPUTATIONAL FLUID DYNAMICS APPLIED TO ROOM AIR FLOW By JAMES W. WEATHERS Bachelor of the requirements for the Degree of MASTER OF SCIENCE May, 1992 #12;ii A STUDY OF COMPUTATIONAL FLUID DYNAMICS
Dynamic Positioning Simulator Dynamic Positioning Simulator
Vuik, Kees
to the ocean floor, without using anchors accomplished by two or more propulsive devices controlled by inputs Dynamic Positioning: No tugboats needed; Offshore set-up is quick; Power saving; Precision situations more Simulator 11 / 24 #12;Dynamic Positioning Simulator Hydrodynamics Forces on Ship: Wave Force Fwd = CXwd (wd
Dynamic Particle Coupling for GPU-based Fluid Simulation
Blanz, Volker
-vi ¯j 2 W( Pi -Pj ,h). Here pj = k( ¯j - 0) is the pressure with gas constant k and rest density 0 for modeling dynamic particle coupling solely based on individual particle contributions. This technique does and µ is the fluid viscosity constant. To model the surface tension, M¨uller et.al. [MCG03] use the so
Computational Chemical Dynamics of Complex Systems University of Minnesota
Truhlar, Donald G
Computational Chemical Dynamics of Complex Systems University of Minnesota Accuracy of density functionals for Pd(PH3)2L complexes where L is ethene or a conjugated CnHn+2 system (n = 4, 6, 8, and 10) Pd large when the size of the conjugated system is increased. We carried out accurate benchmark
ARBITRARY LAGRANGIAN-EULERIAN (ALE) METHODS IN COMPRESSIBLE FLUID DYNAMICS
Kurien, Susan
· . Scalar quantities (density , pressure p, specific internal energy and temperature T) are approximated Lagrangian system is numerically treated by compatible method [8, 9] conserving total energy. Several types Lagrangian-Eulerian (ALE [1]) code for simulation of problems in compressible fluid dynamics and plasma
COMPUTATIONAL FLUID DYNAMICS MODELING OF SOLID OXIDE FUEL CELLS
COMPUTATIONAL FLUID DYNAMICS MODELING OF SOLID OXIDE FUEL CELLS Ugur Pasaogullari and Chao-dimensional model has been developed to simulate solid oxide fuel cells (SOFC). The model fully couples current density operation. INTRODUCTION Solid oxide fuel cells (SOFC) are among possible candidates
Nonlinear Dynamics and Structure Formation in Complex Systems
Zonca, Fulvio
Condition · In burning plasmas ignition condition is reached when local power density (self-heating the ignition condition (-particle self-heating) #12;Nonlinear Dynamics and Structure Formation in Complex of charged fusion products · -particle self-heating may be lost due to their transport out of the system
Generalized Holographic Quantum Criticality at Finite Density
B. Goutéraux; E. Kiritsis
2013-01-23T23:59:59.000Z
We show that the near-extremal solutions of Einstein-Maxwell-Dilaton theories, studied in ArXiv:1005.4690, provide IR quantum critical geometries, by embedding classes of them in higher-dimensional AdS and Lifshitz solutions. This explains the scaling of their thermodynamic functions and their IR transport coefficients, the nature of their spectra, the Gubser bound, and regulates their singularities. We propose that these are the most general quantum critical IR asymptotics at finite density of EMD theories.
Method of high-density foil fabrication
Blue, Craig A.; Sikka, Vinod K.; Ohriner, Evan K.
2003-12-16T23:59:59.000Z
A method for preparing flat foils having a high density includes the steps of mixing a powdered material with a binder to form a green sheet. The green sheet is exposed to a high intensity radiative source adapted to emit radiation of wavelengths corresponding to an absorption spectrum of the powdered material. The surface of the green sheet is heated while a lower sub-surface temperature is maintained. An apparatus for preparing a foil from a green sheet using a radiation source is also disclosed.
Wigner density of a rigid rotator
Malta, C.P. [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05315-970 Sao Paulo (Brazil)] [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05315-970 Sao Paulo (Brazil); Marshall, T.S. [Department of Mathematics, University of Manchester, Manchester M139PL (United Kingdom)] [Department of Mathematics, University of Manchester, Manchester M139PL (United Kingdom); Santos, E. [Departamento de Fisica Moderna, Universidad de Cantabria, 39005, Santander (Spain)] [Departamento de Fisica Moderna, Universidad de Cantabria, 39005, Santander (Spain)
1997-03-01T23:59:59.000Z
We show that the Wigner density of the rigid rotator, in an appropriate, i.e., four-dimensional, phase space, is positive. This result holds in the ground state (S state), and also in the thermal mixture state at all finite temperatures. We discuss the implications of our result for the description of angular momentum in quantum mechanics; in particular, we reexamine, in the light of this new evidence, the suggestion made by Einstein and Stern [Ann. Phys. {bold 40}, 551 (1913)] that there is a nontrivial distribution of angular momentum in the S state. {copyright} {ital 1997} {ital The American Physical Society}
Symmetry energy in nuclear density functional theory
W. Nazarewicz; P. -G. Reinhard; W. Satula; D. Vretenar
2013-07-22T23:59:59.000Z
The nuclear symmetry energy represents a response to the neutron-proton asymmetry. In this survey we discuss various aspects of symmetry energy in the framework of nuclear density functional theory, considering both non-relativistic and relativistic self-consistent mean-field realizations side-by-side. Key observables pertaining to bulk nucleonic matter and finite nuclei are reviewed. Constraints on the symmetry energy and correlations between observables and symmetry-energy parameters, using statistical covariance analysis, are investigated. Perspectives for future work are outlined in the context of ongoing experimental efforts.
Nuclear Energy Density Optimization: UNEDF2
M. Kortelainen; J. McDonnell; W. Nazarewicz; E. Olsen; P. -G. Reinhard; J. Sarich; N. Schunck; S. M. Wild; D. Davesne; J. Erler; A. Pastore
2014-10-30T23:59:59.000Z
The parameters of the UNEDF2 nuclear energy density functional (EDF) model were obtained in an optimization to experimental data consisting of nuclear binding energies, proton radii, odd-even mass staggering data, fission-isomer excitation energies, and single particle energies. In addition to parameter optimization, sensitivity analysis was done to obtain parameter uncertainties and correlations. The resulting UNEDF2 is an all-around EDF. However, the sensitivity analysis also demonstrated that the limits of current Skyrme-like EDFs have been reached and that novel approaches are called for.
Particle transport inferences from density sawteeth
Chen, J.; Li, Q.; Zhuang, G. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Liao, K.; Gentle, K. W., E-mail: k.gentle@mail.utexas.edu [Institute for Fusion Studies, University of Texas, Austin, Texas 78712 (United States)
2014-05-15T23:59:59.000Z
Sawtooth oscillations in tokamaks are defined by their effect on electron temperature: a rapid flattening of the core profile followed by an outward heat pulse and a slow core recovery caused by central heating. Recent high-resolution, multi-chord interferometer measurements on JTEXT extend these studies to particle transport. Sawteeth only partially flatten the core density profile, but enhanced particle diffusion on the time scale of the thermal crash occurs over much of the profile, relevant for impurities. Recovery between crashes implies an inward pinch velocity extending to the center.
Landau's necessary density conditions for LCA groups
Gröchenig, K; Seip, K
2008-01-01T23:59:59.000Z
H. Landau's necessary density conditions for sampling and interpolation may be viewed as a general principle resting on a basic fact of Fourier analysis: The complex exponentials $e^{i kx}$ ($k$ in $\\mathbb{Z}$) constitute an orthogonal basis for $L^2([-\\pi,\\pi])$. The present paper extends Landau's conditions to the setting of locally compact abelian (LCA) groups, relying in an analogous way on the basics of Fourier analysis. The technicalities--in either case of an operator theoretic nature--are however quite different. We will base our proofs on the comparison principle of J. Ramanathan and T. Steger.
R. Gutierrez; R. Caetano; P. B. Woiczikowski; T. Kubar; M. Elstner; G. Cuniberti
2009-10-02T23:59:59.000Z
Charge transport through a short DNA oligomer (Dickerson dodecamer) in presence of structural fluctuations is investigated using a hybrid computational methodology based on a combination of quantum mechanical electronic structure calculations and classical molecular dynamics simulations with a model Hamiltonian approach. Based on a fragment orbital description, the DNA electronic structure can be coarse-grained in a very efficient way. The influence of dynamical fluctuations arising either from the solvent fluctuations or from base-pair vibrational modes can be taken into account in a straightforward way through time series of the effective DNA electronic parameters, evaluated at snapshots along the MD trajectory. We show that charge transport can be promoted through the coupling to solvent fluctuations, which gate the onsite energies along the DNA wire.
The density of states approach for the simulation of finite density quantum field theories
K. Langfeld; B. Lucini; A. Rago; R. Pellegrini; L. Bongiovanni
2015-03-02T23:59:59.000Z
Finite density quantum field theories have evaded first principle Monte-Carlo simulations due to the notorious sign-problem. The partition function of such theories appears as the Fourier transform of the generalised density-of-states, which is the probability distribution of the imaginary part of the action. With the advent of Wang-Landau type simulation techniques and recent advances, the density-of-states can be calculated over many hundreds of orders of magnitude. Current research addresses the question whether the achieved precision is high enough to reliably extract the finite density partition function, which is exponentially suppressed with the volume. In my talk, I review the state-of-play for the high precision calculations of the density-of-states as well as the recent progress for obtaining reliable results from highly oscillating integrals. I will review recent progress for the $Z_3$ quantum field theory for which results can be obtained from the simulation of the dual theory, which appears to free of a sign problem.
The density of states approach for the simulation of finite density quantum field theories
Langfeld, K; Rago, A; Pellegrini, R; Bongiovanni, L
2015-01-01T23:59:59.000Z
Finite density quantum field theories have evaded first principle Monte-Carlo simulations due to the notorious sign-problem. The partition function of such theories appears as the Fourier transform of the generalised density-of-states, which is the probability distribution of the imaginary part of the action. With the advent of Wang-Landau type simulation techniques and recent advances, the density-of-states can be calculated over many hundreds of orders of magnitude. Current research addresses the question whether the achieved precision is high enough to reliably extract the finite density partition function, which is exponentially suppressed with the volume. In my talk, I review the state-of-play for the high precision calculations of the density-of-states as well as the recent progress for obtaining reliable results from highly oscillating integrals. I will review recent progress for the $Z_3$ quantum field theory for which results can be obtained from the simulation of the dual theory, which appears to fr...
Dynamics of structural priming
Malhotra, Gaurav
2009-01-01T23:59:59.000Z
for understanding various aspects of syntactic priming. Cognitive processes are modelled as dynamical systems that can change their behaviour when they process information. We use these dynamical systems to investigate how each episode of language comprehension...
First principles molecular dynamics without self-consistent field optimization
Souvatzis, Petros
2013-01-01T23:59:59.000Z
We present a first principles molecular dynamics approach that is based on time-reversible ex- tended Lagrangian Born-Oppenheimer molecular dynamics [Phys. Rev. Lett. 100, 123004 (2008)] in the limit of vanishing self-consistent field optimization. The optimization-free dynamics keeps the computational cost to a minimum and typically provides molecular trajectories that closely follow the exact Born-Oppenheimer potential energy surface. Only one single diagonalization and Hamiltonian (or Fockian) costruction are required in each integration time step. The proposed dy- namics is derived for a general free-energy potential surface valid at finite electronic temperatures within hybrid density functional theory. Even in the event of irregular functional behavior that may cause a dynamical instability, the optimization-free limit represents an ideal starting guess for force calculations that may require a more elaborate iterative electronic ground state optimization. Our optimization-free dynamics thus represents ...
Optimized Dynamical Decoupling in ?-Type n-Level Quantum Systems
Linping Chan; Shuang Cong
2014-04-28T23:59:59.000Z
In this paper, we first design a type of Bang-Bang (BB) operation group to reduce the phase decoherence in a {\\Xi}-type n-level quantum system based on the dynamical decoupling mechanism. Then, we derive two kinds of dynamical decoupling schemes: periodic dynamical decoupling (PDD) and Uhrig dynamical decoupling (UDD). We select the non-diagonal element of density matrix as a reference index, and investigate the behavior of quantum coherence of the {\\Xi}-type n-level atom under these two dynamical decoupling schemes proposed. At last, we choose a {\\Xi}-type six-level atom as a system controlled, and use the decoupling schemes proposed to suppress the phase decoherence. The simulation experiments and the comparison results are given.
Categorical Introduction to Dynamical Systems Symbolic Dynamical Systems
Kahng, Byung-Jay
Categorical Introduction to Dynamical Systems Symbolic Dynamical Systems Symbolic Embedding Examples Results Embeddings in Symbolic Dynamical Systems Jonathan Jaquette Swarthmore College July 22, 2009 Jonathan Jaquette Embeddings in Symbolic Dynamical Systems #12;Categorical Introduction
Cybersecurity Dynamics Shouhuai Xu
Xu, Shouhuai
Antonio ABSTRACT We explore the emerging field of Cybersecurity Dynamics, a candidate foundation been driving the study of security for decades -- the idea of cybersecurity dynamics emergedCybersecurity Dynamics Shouhuai Xu Department of Computer Science, University of Texas at San
17. METAPOPULATION DYNAMICS OF
17. METAPOPULATION DYNAMICS OF INFECTIOUS DISEASES Matt J. Keeling, Ottar N. Bjørnstad, and Bryan T resonances for the dynamics of parasites. This is particularly true for microparasitic infections" growth of the parasite population. Thus, at the scale of the host popu- lation, infectious dynamics bears
Barrett, Jeffrey A.
Social Dynamics Introduction Part I: Correlation and the Social Contract Introduction to part I 1: University of Utah Press. 47-69. Part II: Importance of Dynamics Introduction to part II 1. Trust, Risk Significance of Some Simple Evolutionary Models (2000) Philosophy of Science 67: 94-113. 4. Dynamics
Atmospheric Dynamics II Instructor
AT602 Atmospheric Dynamics II 2 credits Instructor: David W. J. Thompson davet: An Introduction to Dynamic Meteorology, 5th Edition, Academic Press (recommended) · Marshall, J., and Plumb, R. A., 2008: Atmosphere, Ocean, and Climate Dynamics: An Introductory Text, Academic Press. · Vallis, G. K
Dynamics of Anisotropic Universes
Jerome Perez
2006-03-30T23:59:59.000Z
We present a general study of the dynamical properties of Anisotropic Bianchi Universes in the context of Einstein General Relativity. Integrability results using Kovalevskaya exponents are reported and connected to general knowledge about Bianchi dynamics. Finally, dynamics toward singularity in Bianchi type VIII and IX universes are showed to be equivalent in some precise sence.
Intramolecular and nonlinear dynamics
Davis, M.J. [Argonne National Laboratory, IL (United States)
1993-12-01T23:59:59.000Z
Research in this program focuses on three interconnected areas. The first involves the study of intramolecular dynamics, particularly of highly excited systems. The second area involves the use of nonlinear dynamics as a tool for the study of molecular dynamics and complex kinetics. The third area is the study of the classical/quantum correspondence for highly excited systems, particularly systems exhibiting classical chaos.
Shock waves in a Z-pinch and the formation of high energy density plasma
Rahman, H. U. [Magneto-Inertial Fusion Technologies Inc. (MIFTI), Irvine, California 92612 (United States) and Department of Physics, University of California Irvine, Irvine, California 92697 (United States); Wessel, F. J. [Department of Physics, University of California Irvine, Irvine California 92697 (United States); Ney, P. [Mount San Jacinto College, Menifee, California 92584 (United States); Presura, R. [University of Nevada, Reno, 1664 N. Virginia St., Reno, Nevada 89557-0208 (United States); Ellahi, Rahmat [Department of Mathematics and Statistics, FBAS, IIU, Islamabad (Pakistan) and Department of Mechanical Engineering, University of California Riverside, Riverside, California 92521 (United States); Shukla, P. K. [Department of Mechanical and Aerospace Engineering and Center for Energy Research, University of California San Diego, La Jolla, California 92093 (United States)
2012-12-15T23:59:59.000Z
A Z-pinch liner, imploding onto a target plasma, evolves in a step-wise manner, producing a stable, magneto-inertial, high-energy-density plasma compression. The typical configuration is a cylindrical, high-atomic-number liner imploding onto a low-atomic-number target. The parameters for a terawatt-class machine (e.g., Zebra at the University of Nevada, Reno, Nevada Terawatt Facility) have been simulated. The 2-1/2 D MHD code, MACH2, was used to study this configuration. The requirements are for an initial radius of a few mm for stable implosion; the material densities properly distributed, so that the target is effectively heated initially by shock heating and finally by adiabatic compression; and the liner's thickness adjusted to promote radial current transport and subsequent current amplification in the target. Since the shock velocity is smaller in the liner, than in the target, a stable-shock forms at the interface, allowing the central load to accelerate magnetically and inertially, producing a magneto-inertial implosion and high-energy density plasma. Comparing the implosion dynamics of a low-Z target with those of a high-Z target demonstrates the role of shock waves in terms of compression and heating. In the case of a high-Z target, the shock wave does not play a significant heating role. The shock waves carry current and transport the magnetic field, producing a high density on-axis, at relatively low temperature. Whereas, in the case of a low-Z target, the fast moving shock wave preheats the target during the initial implosion phase, and the later adiabatic compression further heats the target to very high energy density. As a result, the compression ratio required for heating the low-Z plasma to very high energy densities is greatly reduced.
Dynamic behavior of interfacila water at the silica surface
Argyris, Dr. Dimitrios [University of Oklahoma; Cole, David R [ORNL; Striolo, Alberto [Oklahoma University
2009-01-01T23:59:59.000Z
Molecular dynamics simulations were employed to study the dynamics properties of water at the silica-liquid interface at ambient temperature. Three different degrees of hydroxylation of a crystalline silica surface were used. To assess the water dynamic properties we calculated the residence probability and in-plane mean square displacement as a function of distance from the surface. The data indicate that water molecules at the fully hydroxylated surface remain longer, on average, in the interfacial region than in the other cases. By assessing the dynamics of molecular dipole moment and hydrogen-hydrogen vector an anisotropic reorientation was discovered for interfacial water in contact with any of the surfaces considered. However, the features of the anisotropic reorientation observed for water molecules depend strongly on the relative orientation of interfacial water molecules and their interactions with surface hydroxyl groups. On the partially hydroxylated surface, where water molecules with hydrogen-down and hydrogen-up orientation are both found, those water molecules associated with surface hydroxyl groups remain at the adsorbed locations longer and reorient slower than the other water molecules. A number of equilibrium properties, including density profiles, hydrogen bond networks, charge densities, and dipole moment densities are also reported to explain the dynamics results.
Dynamics of Charge-Transfer Processes with Time-Dependent Density Functional Theory
(organic, inorganic, and hybrids), photocatalysis, biomolecules in solvents, reactions at the interface
Dipietro, Laura
The ability to control online motor corrections is key to dealing with unexpected changes arising in the environment with which we interact. How the CNS controls online motor corrections is poorly understood, but evidence ...
Density-Dependent Carrier Dynamics in a Quantum Dots-in-a-Well
Office of Scientific and Technical Information (OSTI)
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:1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:5 TablesExports to3,1,50022,3,,0,,6,1,Separation 23TribalInformationConference:(JournalTowards a Climate-Specific
Dynamics of coastal cod populations: intra-and intercohort density dependence
-temporal patterns in the abundance of cod along the Norwegian Skagerrak coast and demonstrated signi¢cant cyclicity populations (Gadus morhua L.) on the basis of the long-term monitoring data from the Norwegian Skagerrak coast
Radiation in molecular dynamic simulations
Glosli, J; Graziani, F; More, R; Murillo, M; Streitz, F; Surh, M
2008-10-13T23:59:59.000Z
Hot dense radiative (HDR) plasmas common to Inertial Confinement Fusion (ICF) and stellar interiors have high temperature (a few hundred eV to tens of keV), high density (tens to hundreds of g/cc) and high pressure (hundreds of Megabars to thousands of Gigabars). Typically, such plasmas undergo collisional, radiative, atomic and possibly thermonuclear processes. In order to describe HDR plasmas, computational physicists in ICF and astrophysics use atomic-scale microphysical models implemented in various simulation codes. Experimental validation of the models used to describe HDR plasmas are difficult to perform. Direct Numerical Simulation (DNS) of the many-body interactions of plasmas is a promising approach to model validation but, previous work either relies on the collisionless approximation or ignores radiation. We present a new numerical simulation technique to address a currently unsolved problem: the extension of molecular dynamics to collisional plasmas including emission and absorption of radiation. The new technique passes a key test: it relaxes to a blackbody spectrum for a plasma in local thermodynamic equilibrium. This new tool also provides a method for assessing the accuracy of energy and momentum exchange models in hot dense plasmas. As an example, we simulate the evolution of non-equilibrium electron, ion, and radiation temperatures for a hydrogen plasma using the new molecular dynamics simulation capability.
Measuring the entanglement of analogue Hawking radiation by the density-density correlation function
Steinhauer, Jeff
2015-01-01T23:59:59.000Z
We theoretically study the entanglement of Hawking radiation emitted by an analogue black hole. We find that this entanglement can be measured by the experimentally accessible density-density correlation function, which only requires standard imaging techniques. It is seen that the high energy tail of the distribution of Hawking radiation should be entangled, whereas the low energy part is not. This confirms a previous numerical study. The full Peres-Horodecki criterion is considered, but a significant simplification is found in the stationary, homogeneous case. Our method applies to systems which are sufficiently cold that the thermal phonons can be neglected.
Slow dynamics and anomalous nonlinear fast dynamics in diverse solids
Slow dynamics and anomalous nonlinear fast dynamics in diverse solids Paul Johnsona) Geophysics study of anomalous nonlinear fast dynamics and slow dynamics in a number of solids. Observations are presented from seven diverse materials showing that anomalous nonlinear fast dynamics ANFD and slow dynamics
Interaction of a Polyelectrolyte Solution with an Attractive Surface Kate Barteau
Shell, M. Scott
studied a simplified system of a semi-dilute polymer electrolyte solution and its behavior near an oppositely charged surface using molecular dynamics (MD) simulations. Polymers were simulated as 6-12 Lennard with an attractive wall has been carried out through molecular dynamics simulations. Total charge density along
Molecular dynamics studies of interfacial water at the alumina surface.
Argyris, Dr. Dimitrios [University of Oklahoma; Ho, Thomas [ORNL; Cole, David [Ohio State University
2011-01-01T23:59:59.000Z
Interfacial water properties at the alumina surface were investigated via all-atom equilibrium molecular dynamics simulations at ambient temperature. Al-terminated and OH-terminated alumina surfaces were considered to assess the structural and dynamic behavior of the first few hydration layers in contact with the substrates. Density profiles suggest water layering up to {approx}10 {angstrom} from the solid substrate. Planar density distribution data indicate that water molecules in the first interfacial layer are organized in well-defined patterns dictated by the atomic terminations of the alumina surface. Interfacial water exhibits preferential orientation and delayed dynamics compared to bulk water. Water exhibits bulk-like behavior at distances greater than {approx}10 {angstrom} from the substrate. The formation of an extended hydrogen bond network within the first few hydration layers illustrates the significance of water?water interactions on the structural properties at the interface.
Satellite number density profiles of primary galaxies in the 2dFGRS
Laura Sales; Diego G. Lambas
2004-10-21T23:59:59.000Z
We analyse the projected radial distribution of satellites around bright primary galaxies in the 2dFGRS. We have considered several primary-satellite subsamples to search for dependences of the satellite number density profile, \\rho(r_p), on properties of satellites and primaries. We find significant differences of the behaviour of \\rho(r_p) depending on primary characteristics. In star-forming primaries, the satellite number density profile is consistent with power laws within projected distance 20100 kpc), the density profiles of all primaries is well described by power laws, although we notice that for red, early spectral type primaries, the outer slope obtained is steeper than that corresponding to blue, late spectral type ones. We have tested our results by control samples of galaxies identical to the samples of satellites in apparent magnitude and projected distance to the primary, but with a large relative velocity. This sample of unphysical primary-galaxy pairs shows a flat radial density beyond r_p=20 kpc indicating that our results are not biased toward a decrease of the true number of objects due to catalogue selection effects. Our results can be understood in terms of dynamical friction and tidal stripping on satellites in the primary haloes. These processes can effectively transfer energy to the dark matter, flattening the central steep profiles of the satellite distribution in evolved systems.
Cosmological and astrophysical aspects of finite-density QCD
Dominik J. Schwarz
1998-07-23T23:59:59.000Z
The different phases of QCD at finite temperature and density lead to interesting effects in cosmology and astrophysics. In this work I review some aspects of the cosmological QCD transition and of astrophysics at high baryon density.
Noisy Independent Factor Analysis Model for Density Estimation and Classification
Amato, U.
2009-06-09T23:59:59.000Z
We consider the problem of multivariate density estimation when the unknown density is assumed to follow a particular form of dimensionality reduction, a noisy independent factor analysis (IFA) model. In this model the ...
Observable to explore high density behaviour of symmetry energy
Aman D. Sood
2011-09-28T23:59:59.000Z
We aim to see the sensitivity of collective transverse in-plane flow to symmetry energy at low as well as high densities and also to see the effect of different density dependencies of symmetry energy on the same.
Innovative fuel designs for high power density pressurized water reactor
Feng, Dandong, Ph. D. Massachusetts Institute of Technology
2006-01-01T23:59:59.000Z
One of the ways to lower the cost of nuclear energy is to increase the power density of the reactor core. Features of fuel design that enhance the potential for high power density are derived based on characteristics of ...
Constrained Density-Functional Theory--Configuration Interaction
Kaduk, Benjamin James
2012-01-01T23:59:59.000Z
In this thesis, I implemented a method for performing electronic structure calculations, "Constrained Density Functional Theory-- Configuration Interaction" (CDFT-CI), which builds upon the computational strengths of Density ...
Nonparametric Comparison of Densities Based on Statistical Bootstrap
Nonparametric Comparison of Densities Based on Statistical Bootstrap De Brabanter, K.1 , Sahhaf, S. Keywords: Statistical Bootstrap, Variance Stabilization, Least Squares Support Vector Machines, Hypothesis on statistical bootstrap with variance stabilization and a nonparametric kernel density estimator, assisting
Molecular dynamics simulations of grain boundary thermal resistance in UO2
Tianyi Chen; Di Chen; Bulent H. Sencer; Lin Shao
2014-09-01T23:59:59.000Z
By means of molecular dynamics (MD) simulations, we have calculated Kaptiza resistance of UO2 with or without radiation damage. For coincident site lattice boundaries of different configurations, the boundary thermal resistance of unirradiated UO2 can be well described by a parameter-reduced formula by using boundary energies as variables. We extended the study to defect-loaded UO2 by introducing damage cascades in close vicinity to the boundaries. Following cascade annealing and defect migrations towards grain boundaries, the boundary energy increases and so does Kaptiza resistance. The correlations between these two still follow the same formula extracted from the unirradiated UO2. The finding will benefit multi-scale modeling of UO2 thermal properties under extreme radiation conditions by combining effects from boundary configurations and damage levels.
Wang, Jinyang; Zhong, Haimin; Qiu, Wenda; Chen, Liuping, E-mail: cesclp@mail.sysu.edu.cn [KLGHEI of Environment and Energy Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China)] [KLGHEI of Environment and Energy Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Feng, Huajie [School of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 (China)] [School of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 (China)
2014-03-14T23:59:59.000Z
The binary infinite dilute diffusion coefficients, D{sub 12}{sup ?}, of some alkylbenzenes (Ph-C{sub n}, from Ph-H to Ph-C{sub 12}) from 313 K to 333 K at 15 MPa in supercritical carbon dioxide (scCO{sub 2}) have been studied by molecular dynamics (MD) simulation. The MD values agree well with the experimental ones, which indicate MD simulation technique is a powerful way to predict and obtain diffusion coefficients of solutes in supercritical fluids. Besides, the local structures of Ph-C{sub n}/CO{sub 2} fluids are further investigated by calculating radial distribution functions and coordination numbers. It qualitatively convinces that the first solvation shell of Ph-C{sub n} in scCO{sub 2} is significantly influenced by the structure of Ph-C{sub n} solute. Meanwhile, the mean end-to-end distance, the mean radius of gyration and dihedral angle distribution are calculated to gain an insight into the structural properties of Ph-C{sub n} in scCO{sub 2}. The abnormal trends of radial distribution functions and coordination numbers can be reasonably explained in term of molecular flexibility. Moreover, the computed results of dihedral angle clarify that flexibility of long-chain Ph-C{sub n} is the result of internal rotation of C-C single bond (?{sub c-c}) in alkyl chain. It is interesting that compared with n-alkane, because of the existence of benzene ring, the flexibility of alkyl chain in Ph-C{sub n} with same carbon atom number is significantly reduced, as a result, the carbon chain dependence of diffusion behaviors for long-chain n-alkane (n ? 5) and long-chain Ph-C{sub n} (n ? 4) in scCO{sub 2} are different.
Gray squirrel density, habitat suitability, and behavior in urban parks
Gompper, Matthew E.
densities. We used linear regression (SAS Institute, SAS/STAT user's guide. SAS Institute, Cary, NC, 2005
Tunable Laser Plasma Accelerator based on Longitudinal Density Tailoring
Gonsalves, Anthony
2012-01-01T23:59:59.000Z
38 fs. Laser and electron beam diagnostics Laser radiationdiagnostic provided charge density images of the electron beam
A. S. Umar; V. E. Oberacker
2007-09-25T23:59:59.000Z
We study fusion reactions of the $^{64}$Ni+$^{64}$Ni system using the density-constrained time-dependent Hartree-Fock (TDHF) formalism. In this formalism the fusion barriers are directly obtained from TDHF dynamics. In addition, we incorporate the entrance channel alignments of the slightly deformed (oblate) $^{64}$Ni nuclei due to dynamical Coulomb excitation. We show that alignment leads to a fusion barrier distribution and alters the naive picture for defining which energies are actually sub-barrier. We also show that core polarization effects could play a significant role in fusion cross section calculations.
Competition between superconductivity and spin density wave
Tian De Cao
2012-08-25T23:59:59.000Z
The Hubbard model has been investigated widely by many authors, while this work may be new in two aspects. One, we focus on the possible effects of the positions of the gaps associated with the pairing and the spin density wave. Two, we suggest that the models with different parameters are appropriate for different materials (or a material in different doped regions). This will lead to some new insights into the high temperature superconductors. It is shown that the SDW can appear at some temperature region when the on-site Coulomb interaction is larger, while the SC requires a decreased U at a lower temperature. This can qualitatively explain the relationship between superconducting and pseudogap states of Cu-based superconductors in underdoped and optimally doped regions. The superinsulator is also discussed.
Band terminations in density functional theory
A. V. Afanasjev
2009-02-01T23:59:59.000Z
The analysis of the terminating bands has been performed in the relativistic mean field framework. It was shown that nuclear magnetism provides an additional binding to the energies of the specific configuration and this additional binding increases with spin and has its {\\it maximum} exactly at the terminating state. This suggests that the terminating states can be an interesting probe of the time-odd mean fields {\\it provided that other effects can be reliably isolated.} Unfortunately, a reliable isolation of these effects is not that simple: many terms of the density functional theories contribute into the energies of the terminating states and the deficiencies in the description of those terms affect the result. The recent suggestion \\cite{ZSW.05} that the relative energies of the terminating states in the $N \
High energy density redox flow device
Chiang, Yet-Ming; Carter, W. Craig; Ho, Bryan Y; Duduta, Mihai; Limthongkul, Pimpa
2014-05-13T23:59:59.000Z
Redox flow devices are described in which at least one of the positive electrode or negative electrode-active materials is a semi-solid or is a condensed ion-storing electroactive material, and in which at least one of the electrode-active materials is transported to and from an assembly at which the electrochemical reaction occurs, producing electrical energy. The electronic conductivity of the semi-solid is increased by the addition of conductive particles to suspensions and/or via the surface modification of the solid in semi-solids (e.g., by coating the solid with a more electron conductive coating material to increase the power of the device). High energy density and high power redox flow devices are disclosed. The redox flow devices described herein can also include one or more inventive design features. In addition, inventive chemistries for use in redox flow devices are also described.
Marking Streets to Improve Parking Density
Xu, Chao
2015-01-01T23:59:59.000Z
Street parking spots for automobiles are a scarce commodity in most urban environments. The heterogeneity of car sizes makes it inefficient to rigidly define fixed-sized spots. Instead, unmarked streets in cities like New York leave placement decisions to individual drivers, who have no direct incentive to maximize street utilization. In this paper, we explore the effectiveness of two different behavioral interventions designed to encourage better parking, namely (1) educational campaigns to encourage parkers to "kiss the bumper" and reduce the distance between themselves and their neighbors, or (2) painting appropriately-spaced markings on the street and urging drivers to "hit the line". Through analysis and simulation, we establish that the greatest densities are achieved when lines are painted to create spots roughly twice the length of average-sized cars. Kiss-the-bumper campaigns are in principle more effective than hit-the-line for equal degrees of compliance, although we believe that the visual cues of...
Material dynamics under extreme conditions of pressure and strain rate
Remington, B A; Allen, P; Bringa, E; Hawreliak, J; Ho, D; Lorenz, K T; Lorenzana, H; Meyers, M A; Pollaine, S W; Rosolankova, K; Sadik, B; Schneider, M S; Swift, D; Wark, J; Yaakobi, B
2005-09-06T23:59:59.000Z
Solid state experiments at extreme pressures (10-100 GPa) and strain rates ({approx}10{sup 6}-10{sup 8}s{sup -1}) are being developed on high-energy laser facilities, and offer the possibility for exploring new regimes of materials science. These extreme solid-state conditions can be accessed with either shock loading or with a quasi-isentropic ramped pressure drive. Velocity interferometer measurements establish the high pressure conditions. Constitutive models for solid-state strength under these conditions are tested by comparing 2D continuum simulations with experiments measuring perturbation growth due to the Rayleigh-Taylor instability in solid-state samples. Lattice compression, phase, and temperature are deduced from extended x-ray absorption fine structure (EXAFS) measurements, from which the shock-induced {alpha}-{omega} phase transition in Ti and the {alpha}-{var_epsilon} phase transition in Fe are inferred to occur on sub-nanosec time scales. Time resolved lattice response and phase can also be measured with dynamic x-ray diffraction measurements, where the elastic-plastic (1D-3D) lattice relaxation in shocked Cu is shown to occur promptly (< 1 ns). Subsequent large-scale molecular dynamics (MD) simulations elucidate the microscopic dynamics that underlie the 3D lattice relaxation. Deformation mechanisms are identified by examining the residual microstructure in recovered samples. The slip-twinning threshold in single-crystal Cu shocked along the [001] direction is shown to occur at shock strengths of {approx}20 GPa, whereas the corresponding transition for Cu shocked along the [134] direction occurs at higher shock strengths. This slip-twinning threshold also depends on the stacking fault energy (SFE), being lower for low SFE materials. Designs have been developed for achieving much higher pressures, P > 1000 GPa, in the solid state on the National Ignition Facility (NIF) laser.
Laser scattering by density fluctuations of ultra-cold atoms in a magneto-optical trap
J. T. Mendonça; H. Terças
2011-04-06T23:59:59.000Z
We study the spectrum of density fluctuations in the ultra-cold gas of neutral atoms, confined in a magneto-optical trap. We determine the corresponding amplitude and spectra of laser light scattered by this medium. We derive an expression for the dynamical structure function, by using a test particle method. We propose to use the collective laser scattering as a diagnostic method for the microscopic properties of the ultra-cold matter. This will also allow us to check on the atomic correlations which are mediated by the collective mean field inside the gas.
Tuning Range-Separated Density Functional Theory for Photocatalytic Water Splitting Systems
Bokareva, Olga S; Bokarev, Sergey I; Kühn, Oliver
2015-01-01T23:59:59.000Z
We discuss the applicability of long-range separated density functional theory (DFT) to the prediction of electronic transitions of a particular photocatalytic system based on an Ir(III) photosensitizer (IrPS). Special attention is paid to the charge-transfer properties which are of key importance for the photoexcitation dynamics, but and cannot be correctly described by means of conventional DFT. The optimization of the range-separation parameter is discussed for IrPS including its complexes with electron donors and acceptors used in photocatalysis. Particular attention is paid to the problems arising for a description of medium effects by a polarizable continuum model.
Dynamical friction in modified Newtonian dynamics
C. Nipoti; L. Ciotti; J. Binney; P. Londrillo
2008-03-31T23:59:59.000Z
We have tested a previous analytical estimate of the dynamical friction timescale in Modified Newtonian Dynamics (MOND) with fully non-linear N-body simulations. The simulations confirm that the dynamical friction timescale is significantly shorter in MOND than in equivalent Newtonian systems, i.e. systems with the same phase-space distribution of baryons and additional dark matter. An apparent conflict between this result and the long timescales determined for bars to slow and mergers to be completed in previous N-body simulations of MOND systems is explained. The confirmation of the short dynamical-friction timescale in MOND underlines the challenge that the Fornax dwarf spheroidal poses to the viability of MOND.
Density regulation in annual plant communities under variable resource levels
Novoplansky, Ariel
Density regulation in annual plant communities under variable resource levels Hagit Shilo. E. and Turkington, R. 2005. Density regulation in annual plant communities under variable resource levels. Á/ Oikos 108: 241Á/252. Density regulation is assumed to be common, but is very rarely tested
Contributed Paper Wood Density as a Conservation Tool: Quantification
Contributed Paper Wood Density as a Conservation Tool: Quantification of Disturbance to easily identify areas of old-growth forest. The average density of the wood of a tree species is closely wood density can be used to quantify forest disturbance and conservation importance. The average
Gyrokinetic simulations of electron density fluctuations and comparisons with measurements
Budny, Robert
density fluctuations, APS, Orlando, FL, Nov, 2007PRINCETON PLASMA PHYSICS LABORATORY PPPL 1 #12, Gyrokinetic simulations of electron density fluctuations, APS, Orlando, FL, Nov, 2007PRINCETON PLASMA PHYSICS simulations of electron density fluctuations, APS, Orlando, FL, Nov, 2007PRINCETON PLASMA PHYSICS LABORATORY
Microwave Interferometer Density Diagnostic for the Levitated Dipole Experiment
Microwave Interferometer Density Diagnostic for the Levitated Dipole Experiment A. Boxer, J. Kesner the density profile of the plasma in LDX, we are constructing a multi-channel microwave interferometer be inverted to reconstruct a radially symmetric density profile. The microwave interferometer of LDX
PROFILE SHAPE PARAMETERIZATION OF JET ELECTRON TEMPERATURE AND DENSITY PROFILES
PROFILE SHAPE PARAMETERIZATION OF JET ELECTRON TEMPERATURE AND DENSITY PROFILES Beatrix Schunke JET Mercer St., New York NY 10012-1185 The temperature and density profiles of the Joint European Torus to determine which terms in the log-linear model to include. The density and temperature profiles
PROFILE SHAPE PARAMETERIZATION OF JET ELECTRON TEMPERATURE AND DENSITY PROFILES
PROFILE SHAPE PARAMETERIZATION OF JET ELECTRON TEMPERATURE AND DENSITY PROFILES Beatrix Schunke JET Mercer St., New York NY 100121185 Abstract The temperature and density profiles of the Joint European are used to determine which terms in the loglinear model to include. The density and temperature profiles
Quantum coherent switch utilizing commensurate nanoelectrode and charge density periodicities
Harrison, Neil (Santa Fe, NM); Singleton, John (Los Alamos, NM); Migliori, Albert (Santa Fe, NM)
2008-08-05T23:59:59.000Z
A quantum coherent switch having a substrate formed from a density wave (DW) material capable of having a periodic electron density modulation or spin density modulation, a dielectric layer formed onto a surface of the substrate that is orthogonal to an intrinsic wave vector of the DW material; and structure for applying an external spatially periodic electrostatic potential over the dielectric layer.
Vaidyanathan, Vidya
2009-05-15T23:59:59.000Z
Predominance of small dense Low Density Lipoprotein (LDL) is associated with a two to threefold increase in risk for Coronary Heart Disease (CVD). Small, dense HDL (High Density Lipoprotein) particles protect small dense LDL from oxidative stress...
Conformal Higgs model: predicted dark energy density
R. K. Nesbet
2014-11-03T23:59:59.000Z
Postulated universal Weyl conformal scaling symmetry provides an alternative to the $\\Lambda$CDM paradigm for cosmology. Recent applications to galactic rotation velocities, Hubble expansion, and a model of dark galactic halos explain qualitative phenomena and fit observed data without invoking dark matter. Significant revision of theory relevant to galactic collisions and clusters is implied, but not yet tested. Dark energy is found to be a consequence of conformal symmetry for the Higgs scalar field of electroweak physics. The present paper tests this implication. The conformal Higgs model acquires a gravitational effect described by a modified Friedmann cosmic evolution equation, shown to fit cosmological data going back to the cosmic microwave background epoch. The tachyonic mass parameter of the Higgs model becomes dark energy in the Friedmann equation. A dynamical model of this parameter, analogous to the Higgs mechanism for gauge boson mass, is derived and tested here. An approximate calculation yields a result consistent with the empirical magnitude inferred from Hubble expansion.
State densities and spectrum fluctuations: Information propagation in complex nuclei
French, J.B.; Kota, V.K.B.
1988-01-01T23:59:59.000Z
At excitation energies in nuclei where the state density is unambiguously defined there is a sharp separation between the smoothed spectrum (which defines the density) and fluctuations about it which have recently been studied with a view to understanding some aspects of quantum chaos. We briefly review these two complementary subjects, paying special attention to: the role of the effective interaction in determining the density; the calculation of interacting-particle state and level densities, and of expectation values of interesting operators; the information about the effective nucleon-nucleon interaction which is carried both by the density and the fluctuations. 28 refs., 1 fig.
Statistical density modification with non-crystallographic symmetry
Terwilliger, Thomas C., E-mail: terwilliger@lanl.gov [Mail Stop M888, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
2002-12-01T23:59:59.000Z
Statistical density modification can make use of NCS in a crystal and can include estimates of the deviations from perfect NCS. Statistical density modification is a technique for phase improvement through a calculation of the posterior probability of the phases, given experimental phase information and expectations about features of the electron-density map. The technique can take advantage of both estimates of electron density in the map and uncertainties or probability distributions for those estimates. For crystals with non-crystallographic symmetry (NCS), this allows the use of the expected similarity of electron density at NCS-related points without requiring an implicit assumption that these regions are identical.
Brane World Dynamics and Adiabatic Matter creation
P. Gopakumar; G. V. Vijayagovindan
2006-04-10T23:59:59.000Z
We have treated the adiabatic matter creation process in various three-brane models by applying thermodynamics of open systems. The matter creation rate is found to affect the evolution of scale factor and energy density of the universe. We find modification at early stages of cosmic dynamics. In GB and RS brane worlds, by chosing appropriate parameters we obtain standard scenario, while the warped DGP model has different Friedmann equations. During later stages, since the matter creation is negligible the evolution reduces to FRW expansion, in RS and GB models.
Dynamics of sliding drops on superhydrophobic surfaces
A. Dupuis; J. M. Yeomans
2006-05-10T23:59:59.000Z
We use a free energy lattice Boltzmann approach to investigate numerically the dynamics of drops moving across superhydrophobic surfaces. The surfaces comprise a regular array of posts small compared to the drop size. For drops suspended on the posts the velocity increases as the number of posts decreases. We show that this is because the velocity is primarily determined by the contact angle which, in turn, depends on the area covered by posts. Collapsed drops, which fill the interstices between the posts, behave in a very different way. The posts now impede the drop behaviour and the velocity falls as their density increases.
DYNAMICAL MODEL OF AN EXPANDING SHELL
Pe'er, Asaf [Harvard-Smithsonian Center for Astrophysics, MS-51, 60 Garden Street, Cambridge, MA 02138 (United States)
2012-06-10T23:59:59.000Z
Expanding blast waves are ubiquitous in many astronomical sources, such as supernova remnants, X-ray emitting binaries, and gamma-ray bursts. I consider here the dynamics of such an expanding blast wave, both in the adiabatic and the radiative regimes. As the blast wave collects material from its surroundings, it decelerates. A full description of the temporal evolution of the blast wave requires consideration of both the energy density and the pressure of the shocked material. The obtained equation is different from earlier works in which only the energy was considered. The solution converges to the familiar results in both the ultrarelativistic and the sub-relativistic (Newtonian) regimes.
Anti-hierarchical evolution of the active galactic nucleus space density in a hierarchical universe
Enoki, Motohiro [Faculty of Business Administration, Tokyo Keizai University, Kokubunji, Tokyo 185-8502 (Japan); Ishiyama, Tomoaki [Center for Computational Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); Kobayashi, Masakazu A. R. [Research Center for Space and Cosmic Evolution, Ehime University, Matsuyama, Ehime 790-8577 (Japan); Nagashima, Masahiro, E-mail: enokimt@tku.ac.jp [Faculty of Education, Nagasaki University, Nagasaki, Nagasaki 852-8521 (Japan)
2014-10-10T23:59:59.000Z
Recent observations show that the space density of luminous active galactic nuclei (AGNs) peaks at higher redshifts than that of faint AGNs. This downsizing trend in the AGN evolution seems to be contradictory to the hierarchical structure formation scenario. In this study, we present the AGN space density evolution predicted by a semi-analytic model of galaxy and AGN formation based on the hierarchical structure formation scenario. We demonstrate that our model can reproduce the downsizing trend of the AGN space density evolution. The reason for the downsizing trend in our model is a combination of the cold gas depletion as a consequence of star formation, the gas cooling suppression in massive halos, and the AGN lifetime scaling with the dynamical timescale. We assume that a major merger of galaxies causes a starburst, spheroid formation, and cold gas accretion onto a supermassive black hole (SMBH). We also assume that this cold gas accretion triggers AGN activity. Since the cold gas is mainly depleted by star formation and gas cooling is suppressed in massive dark halos, the amount of cold gas accreted onto SMBHs decreases with cosmic time. Moreover, AGN lifetime increases with cosmic time. Thus, at low redshifts, major mergers do not always lead to luminous AGNs. Because the luminosity of AGNs is correlated with the mass of accreted gas onto SMBHs, the space density of luminous AGNs decreases more quickly than that of faint AGNs. We conclude that the anti-hierarchical evolution of the AGN space density is not contradictory to the hierarchical structure formation scenario.
Building a Universal Nuclear Energy Density Functional
Carlson, Joe A. [Michigan State University; Furnstahl, Dick; Horoi, Mihai; Lust, Rusty; Nazaewicc, Witek; Ng, Esmond; Thompson, Ian; Vary, James
2012-12-30T23:59:59.000Z
During the period of Dec. 1 2006 – Jun. 30, 2012, the UNEDF collaboration carried out a comprehensive study of all nuclei, based on the most accurate knowledge of the strong nuclear interaction, the most reliable theoretical approaches, the most advanced algorithms, and extensive computational resources, with a view towards scaling to the petaflop platforms and beyond. The long-term vision initiated with UNEDF is to arrive at a comprehensive, quantitative, and unified description of nuclei and their reactions, grounded in the fundamental interactions between the constituent nucleons. We seek to replace current phenomenological models of nuclear structure and reactions with a well-founded microscopic theory that delivers maximum predictive power with well-quantified uncertainties. Specifically, the mission of this project has been three-fold: ? First, to find an optimal energy density functional (EDF) using all our knowledge of the nucleonic Hamiltonian and basic nuclear properties; ? Second, to apply the EDF theory and its extensions to validate the functional using all the available relevant nuclear structure and reaction data; ? Third, to apply the validated theory to properties of interest that cannot be measured, in particular the properties needed for reaction theory.