National Library of Energy BETA

Sample records for dynamics md density

  1. RADIATION PRESSURE DETECTION AND DENSITY ESTIMATE FOR 2011 MD

    SciTech Connect (OSTI)

    Micheli, Marco; Tholen, David J.; Elliott, Garrett T. E-mail: tholen@ifa.hawaii.edu

    2014-06-10

    We present our astrometric observations of the small near-Earth object 2011 MD (H ? 28.0), obtained after its very close fly-by to Earth in 2011 June. Our set of observations extends the observational arc to 73 days, and, together with the published astrometry obtained around the Earth fly-by, allows a direct detection of the effect of radiation pressure on the object, with a confidence of 5?. The detection can be used to put constraints on the density of the object, pointing to either an unexpectedly low value of ?=(640±330)kg m{sup ?3} (68% confidence interval) if we assume a typical probability distribution for the unknown albedo, or to an unusually high reflectivity of its surface. This result may have important implications both in terms of impact hazard from small objects and in light of a possible retrieval of this target.

  2. Microscopic dynamical description of proton-induced fission with the Constrained Molecular Dynamics (CoMD) Model

    E-Print Network [OSTI]

    N. Vonta; G. A. Souliotis; M. Veselsky; A. Bonasera

    2015-06-16

    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.

  3. Microscopic dynamical description of proton-induced fission with the Constrained Molecular Dynamics (CoMD) Model

    E-Print Network [OSTI]

    Vonta, N; Veselsky, M; Bonasera, A

    2015-01-01

    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 calculation...

  4. Dynamics of a globular protein and its hydration water studied by neutron scattering and MD simulations

    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

    2010-01-01

    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

  5. Chiral dynamics and peripheral transverse densities Granados...

    Office of Scientific and Technical Information (OSTI)

    dynamics and peripheral transverse densities Granados, Carlos G. Uppsala University (Sweden); Weiss, Christian JLAB, Newport News, VA (United States) 72 PHYSICS OF ELEMENTARY...

  6. Scaling Dynamical Correlation Energy from Density Functional Theory Correlation Functionals

    E-Print Network [OSTI]

    Ramachandran, Bala (Ramu)

    Scaling Dynamical Correlation Energy from Density Functional Theory Correlation Functionals B for molecules by scaling the electron correlation energy calculated by density functional theory (DFT)1 ReceiVed: February 2, 2005; In Final Form: April 18, 2005 The scaling of dynamical correlation energy

  7. Chiral dynamics and peripheral transverse densities

    SciTech Connect (OSTI)

    Granados, Carlos G.; Weiss, Christian

    2014-01-01

    In the partonic (or light-front) description of relativistic systems the electromagnetic form factors are expressed in terms of frame-independent charge and magnetization densities in transverse space. This formulation allows one to identify the chiral components of nucleon structure as the peripheral densities at transverse distances b = O(M{sub {pi}}{sup -1}) and compute them in a parametrically controlled manner. A dispersion relation connects the large-distance behavior of the transverse charge and magnetization densities to the spectral functions of the Dirac and Pauli form factors near the two--pion threshold at timelike t = 4 M{ sub {pi}}{sup 2}, which can be computed in relativistic chiral effective field theory. Using the leading-order approximation we (a) derive the asymptotic behavior (Yukawa tail) of the isovector transverse densities in the "chiral" region b = O(M{sub {pi}}{sup -1}) and the "molecular" region b = O(M{sub N}{sup 2}/M{sub {pi}}{sup 3}); (b) perform the heavy-baryon expansion of the transverse densities; (c) explain the relative magnitude of the peripheral charge and magnetization densities in a simple mechanical picture; (d) include Delta isobar intermediate states and study the peripheral transverse densities in the large-N{ sub c} limit of QCD; (e) quantify the region of transverse distances where the chiral components of the densities are numerically dominant; (f) calculate the chiral divergences of the b{sup 2}-weighted moments of the isovector transverse densities (charge and anomalous magnetic radii) in the limit M{sub {pi}} -> 0 and determine their spatial support. Our approach provides a concise formulation of the spatial structure of the nucleon's chiral component and offers new insights into basic properties of the chiral expansion. It relates the information extracted from low-t elastic form factors to the generalized parton distributions probed in peripheral high-energy scattering processes.

  8. The formulation of quantum statistical mechanics based on the Feynman path centroid density. IV. Algorithms for centroid molecular dynamics

    E-Print Network [OSTI]

    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

  9. Proceedings of the American Control Conference, Baltimore, MD, 2010 Robustness of Noisy Consensus Dynamics with Directed Communication

    E-Print Network [OSTI]

    Leonard, Naomi

    Proceedings of the American Control Conference, Baltimore, MD, 2010 Robustness of Noisy Consensus be solved by autonomous groups of aerial, ground or underwater vehicles [10]. For the purposes of achieving to several different parameters, including component or individual agent failure, environmental uncertainty

  10. Hybrid Dynamic Density Functional Theory for Polymer Melts and Blends

    E-Print Network [OSTI]

    Takashi Honda; Toshihiro Kawakatsu

    2006-09-05

    We propose a high-speed and accurate hybrid dynamic density functional theory for the computer simulations of the phase separation processes of polymer melts and blends. The proposed theory is a combination of the dynamic self-consistent field (SCF) theory and a time-dependent Ginzburg-Landau type theory with the random phase approximation (GRPA). The SCF theory is known to be accurate in evaluating the free energy of the polymer systems in both weak and strong segregation regions although it has a disadvantage of the requirement of a considerable amount of computational cost. On the other hand, the GRPA theory has an advantage of much smaller amount of required computational cost than the SCF theory while its applicability is limited to the weak segregation region. To make the accuracy of the SCF theory and the high-performance of the GRPA theory compatible, we adjust the chemical potential of the GRPA theory by using the SCF theory every constant time steps in the dynamic simulations. The performance of the GRPA and the hybrid theories is tested by using several systems composed of an A/B homopolymer, an AB diblock copolymer, or an ABC triblock copolymer. Using the hybrid theory, we succeeded in reproducing the metastable complex phase-separated domain structures of an ABC triblock copolymer observed by experiments.

  11. Effects of Phase Transition induced density fluctuations on pulsar dynamics

    E-Print Network [OSTI]

    Bagchi, Partha; Layek, Biswanath; Srivastava, Ajit M

    2015-01-01

    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.

  12. Probing Electron Dynamics with the Laplacian of the Momentum Density

    SciTech Connect (OSTI)

    Sukumar, N.; MacDougall, Preston J.; Levit, M. Creon

    2012-09-24

    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.

  13. Why are MD simulated protein folding times wrong? Dmitry Nerukh

    E-Print Network [OSTI]

    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

  14. TELEPSYCHIATRY Peter Yellowlees MBBS MD

    E-Print Network [OSTI]

    Leistikow, Bruce N.

    TELEPSYCHIATRY Peter Yellowlees MBBS MD Professor of Psychiatry UC Davis, California #12; Providing #12;UC Davis Prima Care Network Woodland Dignity Health Clinic CURRENT CLINICAL TRIAL OF ATP VS. STP-Maria Iosif PhD · Paul Leigh PhD · Bill Brady MD and Auburn Clinic staff ­ UCD PCN · Jeff Yee MD and Woodland

  15. Meng Law, MD Amit M. Saindane, MD

    E-Print Network [OSTI]

    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

  16. Extended Lagrangian Density Functional Tight-Binding Molecular Dynamics for Molecules and Solids

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

    Aradi, Bálint; Niklasson, Anders M. N.; Frauenheim, Thomas

    2015-06-26

    A computationally fast quantum mechanical molecular dynamics scheme using an extended Lagrangian density functional tight-binding formulation has been developed and implemented in the DFTB+ electronic structure program package for simulations of solids and molecular systems. The scheme combines the computational speed of self-consistent density functional tight-binding theory with the efficiency and long-term accuracy of extended Lagrangian Born–Oppenheimer molecular dynamics. Furthermore, for systems without self-consistent charge instabilities, only a single diagonalization or construction of the single-particle density matrix is required in each time step. The molecular dynamics simulation scheme can also be applied to a broad range of problems in materialsmore »science, chemistry, and biology.« less

  17. Effects of density dependent sex allocation on the dynamics of a simultaneous hermaphroditic population: Modelling and analysis

    E-Print Network [OSTI]

    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

  18. 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

    2015-07-31

    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

  19. Light-front representation of chiral dynamics in peripheral transverse densities

    E-Print Network [OSTI]

    C. Granados; C. Weiss

    2015-03-16

    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-independent 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.

  20. Dynamics and instantaneous normal modes in a liquid with density anomalies

    E-Print Network [OSTI]

    Massimo Pica Ciamarra; Peter Sollich

    2015-08-19

    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.

  1. Liquids that form due to dynamics of the molecules that depend on the local density

    E-Print Network [OSTI]

    Richard P. Sear

    2015-03-26

    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.

  2. Charge density wave in hydrogen at high pressure

    E-Print Network [OSTI]

    Magdau, Ioan B

    2015-01-01

    We present extensive molecular dynamics (MD) simulations investigating numerous candidate crystal structures for hydrogen in conditions around the present experimental frontier (400GPa). Spontaneous phase transitions in the simulations reveal a new structure candidate comprising twofold coordinated chains of hydrogen atoms. We explain the electronic structure of this phase in terms of a charge density wave and calculate its experimental signature. In detailed tests of the accuracy of our calculation, we find that k-point sampling is far more important in MD than in static calculations, because of the freedom it give the atoms to rearrange themselves optimally for the given sampling.

  3. Dynamical density functional theory for the diffusion of injected Brownian particles

    E-Print Network [OSTI]

    H. Löwen; M. Heinen

    2014-09-08

    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.

  4. The influence of dynamical friction on the collapse of spherical density pertubation

    E-Print Network [OSTI]

    A. Del Popolo; M. Gambera; V. Antonuccio-Delogu

    1996-10-24

    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.

  5. Rume nach Gebude Gebude MD Hirnbckhalle

    E-Print Network [OSTI]

    Arnold, Anton

    EG 01 Lager 4.1 Lagerräume 222 100 200 28,30 MD EG 02 Wasserbaulabor 3.1 Werkhallen 222 100 200 182,90 MD EG 07 Werkstätte 3.1 Werkhallen 222 100 200 200,36 MD EG 18 Wasserbaulabor 3.1 Werkhallen 222 100 200 1.128,10 MD EG 25 Sozialraum 1.2 Gemeinschaftsräume 222 100 200 17,95 MD EG 25A Dusche, Vorraum 7

  6. Design of dynamic Hohlraum opacity samples to increase measured sample density on Z

    SciTech Connect (OSTI)

    Nash, T. J.; Rochau, G. A.; Bailey, J. E. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    2010-10-15

    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.

  7. Design of dynamic hohlraum opacity samples to increase measured sample density on Z.

    SciTech Connect (OSTI)

    Rochau, Gregory Alan; Nash, Thomas J.; Bailey, James E.

    2010-03-01

    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.

  8. Dynamic density field measurements of an explosively driven ????? phase transition in iron

    SciTech Connect (OSTI)

    Hull, L. M.; Gray, G. T.; Warthen, B. J.

    2014-07-28

    We provide a unique set of observations of the behavior of the ??? phase transition under a complex axially symmetric loading path created by sweeping a detonation wave along the end surface of a cylindrical sample. The primary data sets are the measured mass density distributions acquired at 5 independent times during the sweep of the detonation along the surface. Shocked regions and boundaries are measured, as well as regions and boundaries of elevated density (presumed to be the ??phase iron). The formation and dynamics of these regions were captured and are available for comparisons to material descriptions. We also applied 16 Photon Doppler Velocimetry probes to capture the free surface velocity along a discrete set of radially distributed points in order to compare and correlate the density measurements with previous shock wave studies. The velocimetry data are in nearly exact agreement with previous shock wave studies of the ??? phase transition, the density distributions, while generally in agreement with expectations evolved from the shock wave studies, show that the epsilon phase is generated in regions of high shear stress but at hydrostatic stresses below the typically quoted 13?GPa value. The density field measurements are particularly useful for observing the effects of the forward and reverse transformation kinetics, as well as the reverse transformation hysteresis.

  9. Scattering Density Profile Model of POPG Bilayers as Determined by Molecular Dynamics Simulations and Small-Angle Neutron and X-ray Scattering Experiments

    SciTech Connect (OSTI)

    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

    2012-01-01

    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.

  10. Flow of colloidal solids and fluids through constrictions: dynamical density functional theory versus simulation

    E-Print Network [OSTI]

    Urs Zimmermann; Frank Smallenburg; Hartmut Löwen

    2015-12-02

    Using both dynamical density functional theory and particle-resolved Brownian dynamics simulations, we explore the flow of two-dimensional colloidal solids and fluids driven through a linear channel with a geometric constriction. The flow is generated by a constant external force acting on all colloids. The initial configuration is equilibrated in the absence of flow and then the external force is switched on instantaneously. Upon starting the flow, we observe four different scenarios: a complete blockade, a monotonic decay to a constant particle flux (typical for a fluid), a damped oscillatory behaviour in the particle flux, and a long-lived stop-and-go behaviour in the flow (typical for a solid). The dynamical density functional theory describes all four situations but predicts infinitely long undamped oscillations in the flow which are always damped in the simulations. We attribute the mechanisms of the underlying stop-and-go flow to symmetry conditions on the flowing solid. Our predictions are verifiable in real-space experiments on magnetic colloidal monolayers which are driven through structured microchannels and can be exploited to steer the flow throughput in microfluidics.

  11. Steve Nelson, MD Backes, PhD

    E-Print Network [OSTI]

    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

  12. Quadrupole collective dynamics from energy density functionals: Collective Hamiltonian and the interacting boson model

    SciTech Connect (OSTI)

    Nomura, K.; Vretenar, D.; Niksic, T.; Otsuka, T.; Shimizu, N.

    2011-07-15

    Microscopic energy density functionals 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 paper, we compare two approaches to five-dimensional quadrupole dynamics: the collective Hamiltonian for quadrupole vibrations and rotations and the interacting boson model (IBM). The two models are compared in a study of the evolution of nonaxial shapes in Pt isotopes. Starting from the binding energy surfaces of {sup 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 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.

  13. Electrons as probes of dynamics in molecules and clusters : a contribution from Time Dependent Density Functional Theory

    E-Print Network [OSTI]

    Wopperer, P; Reinhard, P -G; Suraud, E

    2014-01-01

    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...

  14. Conformational dynamics of a crystalline protein from microsecond-scale molecular dynamics simulations and diffuse X-ray scattering

    SciTech Connect (OSTI)

    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)

    2014-12-01

    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.

  15. Conformational dynamics of a crystalline protein from microsecond-scale molecular dynamics simulations and diffuse X-ray scattering

    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.

    2014-12-01

    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. In conclusion, diffuse scattering can be used to validate predictions from MD simulations and can provide information to improve MD models of protein motions.« less

  16. Detonation shock dynamics calibration for pBX 9502 with temperature, density, and material lot variations

    SciTech Connect (OSTI)

    Hill, Larry G; Aslam, Tariq D

    2010-01-01

    We present a methodology for scaling the detonation shock dynamics D{sub n}[{kappa}] calibration function to accommodate variations in the HE starting material. We apply our model to the insensitive TATB-based explosive PBX 9502, for which we have enough front curvature rate stick data to characterize three material attributes: initial temperature T{sub 0}, nominal density {rho}{sub 0}, and manufacturing lot (representing different microstructures). A useful feature of the model is that it returns an absolute estimate for the reaction zone thickness, {delta}. Lacking demonstrated material metrics(s), we express microstructural variation indirectly, in terms of its effect on {delta}. This results in a D{sub n}[{kappa}] function that depends on T{sub 0}, {rho}{sub 0}, and {delta}. After examining the separate effects of each parameter on D{sub n}[{kappa}], we compute an arc geometry as a validation problem. We compare the calculation to a PBX 9502 arc experiment that was pressed from one of the calibrated HE lots. The agreement between the model and experiment is excellent. We compute worst, nominal, and best-performing material parameter combinations to show how much difference accrues throughout the arc.

  17. Ab initio molecular dynamics with nuclear quantum effects at classical cost: ring polymer contraction for density functional theory

    E-Print Network [OSTI]

    Marsalek, Ondrej

    2015-01-01

    Path integral molecular dynamics simulations, combined with an ab initio evaluation of interactions using electronic structure theory, incorporate the quantum mechanical nature of both the electrons and nuclei, which are essential to accurately describe systems containing light nuclei. However, path integral simulations have traditionally required a computational cost around two orders of magnitude greater than treating the nuclei classically, making them prohibitively costly for most applications. Here we show that the cost of path integral simulations can be dramatically reduced by extending our ring polymer contraction approach to ab initio molecular dynamics simulations. By using density functional tight binding as a reference system, we show that our ab initio ring polymer contraction (AI-RPC) scheme gives rapid and systematic convergence to the full path integral density functional theory result. We demonstrate the efficiency of this approach in ab initio simulations of liquid water and the reactive pro...

  18. Nuclear energy density functional from chiral pion-nucleon dynamics revisited

    E-Print Network [OSTI]

    N. Kaiser; W. Weise

    2009-12-16

    We use a recently improved density-matrix expansion to calculate the nuclear energy density functional in the framework of in-medium chiral perturbation theory. Our calculation treats systematically the effects from $1\\pi$-exchange, iterated $1\\pi$-exchange, and irreducible $2\\pi$-exchange with intermediate $\\Delta$-isobar excitations, including Pauli-blocking corrections up to three-loop order. We find that the effective nucleon mass $M^*(\\rho)$ entering the energy density functional is identical to the one of Fermi-liquid theory when employing the improved density-matrix expansion. The strength $F_\

  19. Impact of the pedestal plasma density on dynamics of edge localized mode crashes and energy loss scaling

    SciTech Connect (OSTI)

    Xu, X. Q.; Ma, J. F.; Li, G. Q.

    2014-12-15

    The latest BOUT++ studies show an emerging understanding of dynamics of edge localized mode (ELM) crashes and the consistent collisionality scaling of ELM energy losses with the world multi-tokamak database. A series of BOUT++ simulations are conducted to investigate the scaling characteristics of the ELM energy losses vs collisionality via a density scan. Linear results demonstrate that as the pedestal collisionality decreases, the growth rate of the peeling-ballooning modes decreases for high n but increases for low n (1?density plays a major role in determining the ELM energy loss through its effect on the edge bootstrap current and ion diamagnetic stabilization. The critical trend emerges as a transition (1) linearly from ballooning-dominated states at high collisionality to peeling-dominated states at low collisionality with decreasing density and (2) nonlinearly from turbulence spreading dynamics at high collisionality into avalanche-like dynamics at low collisionality.

  20. Dynamics and afterglow light curves of gamma-ray burst blast waves encountering a density bump or void

    SciTech Connect (OSTI)

    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)

    2014-07-01

    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.

  1. Dynamics of observables and exactly solvable quantum problems: Using time-dependent density functional theory to control quantum systems

    E-Print Network [OSTI]

    Mehdi Farzanehpour; I. V. Tokatly

    2015-06-29

    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.

  2. Novel Structure and Dynamics of Polymer Thin Films in Supercritical Fluids-Effect of Density Fluctuation

    SciTech Connect (OSTI)

    Koga,T.

    2004-01-01

    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.

  3. Out-of-equilibrium liquids that form due to dynamics of the molecules that depend on the local density

    E-Print Network [OSTI]

    Sear, Richard P

    2015-01-01

    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 study models with out-of-equilibrium dynamics that depend on the local density. Our simulations suggest that density-dependent dynamics in which the motion of a molecule slows down in the presence of nearby molecules, tend to cause condensation into an out-of-equilibrium liquid state. This out-of-equilibrium state behaves like a liquid in the sense that it coexists with a much more dilute phase, droplets coalesce, and the state has a well-defined surface tension --- which we calculate. Liquid/liquid separation appears to be a very general phenomenon that occurs in and out of equilibrium. We also look at the analogous separation of the two blocks of a block copolymer, in which the monomers of one block have dynamics t...

  4. An experimental investigation of the dynamics of submarine leveed channel initiation as sediment-laden density currents experience sudden unconfinement

    SciTech Connect (OSTI)

    Rowland, Joel C [Los Alamos National Laboratory; Hilley, George E [STANFORD UNIV; Fildani, Andrea [CHEVRON ETC

    2009-01-01

    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.

  5. Diffraction-Based Density Restraints for Membrane and Membrane-Peptide Molecular Dynamics Simulations

    E-Print Network [OSTI]

    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

  6. Numerical Investigation of Glassy Dynamics in Low-Density Systems Emanuela Zaccarelli,1

    E-Print Network [OSTI]

    Sciortino, Francesco

    be- havior of dilute suspensions of charged colloids. Low- density glasses stabilized by Coulomb received 14 April 2008; published 12 May 2008) Vitrification in colloidal systems typically occurs at high system is the hard-sphere suspension, which has served as the basis for numerous experimental

  7. Micromagnetic analysis of dynamical bubble-like solitons based on the time domain evolution of the topological density

    SciTech Connect (OSTI)

    Puliafito, Vito Azzerboni, Bruno; Finocchio, Giovanni; Torres, Luis; Ozatay, Ozhan

    2014-05-07

    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.

  8. Steady-State and Dynamic Modeling of Commercial Slurry High-Density Polyethylene (HDPE) Processes

    E-Print Network [OSTI]

    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

  9. Study of fusion dynamics using Skyrme energy density formalism with different surface corrections

    E-Print Network [OSTI]

    Ishwar Dutt; Narinder K. Dhiman

    2010-11-19

    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.

  10. Water adsorption on stepped ZnO surfaces from MD simulation David Raymand a

    E-Print Network [OSTI]

    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

  11. Membrane association of the PTEN tumor suppressor: Neutron scattering and MD simulations reveal the structure

    E-Print Network [OSTI]

    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

  12. Modelling of the internal dynamics and density in a tens of joules plasma focus device

    SciTech Connect (OSTI)

    Marquez, Ariel; Gonzalez, Jose; Tarifeno-Saldivia, Ariel; Pavez, Cristian; Soto, Leopoldo; Clausse, Alejandro

    2012-01-15

    Using MHD theory, coupled differential equations were generated using a lumped parameter model to describe the internal behaviour of the pinch compression phase in plasma focus discharges. In order to provide these equations with appropriate initial conditions, the modelling of previous phases was included by describing the plasma sheath as planar shockwaves. The equations were solved numerically, and the results were contrasted against experimental measurements performed on the device PF-50J. The model is able to predict satisfactorily the timing and the radial electron density profile at the maximum compression.

  13. Time-dependent density functional studies of nuclear quantum dynamics in large amplitudes

    E-Print Network [OSTI]

    Wen, Kai; Fang, Ni; Nakatsukasa, Takashi

    2015-01-01

    The time-dependent density functional theory (TDDFT) provides a unified description of the structure and reaction. The linear approximation leads to the random-phase approximation (RPA) which is capable of describing a variety of collective motion in a harmonic regime. Beyond the linear regime, we present applications of the TDDFT to nuclear fusion and fission reaction. In particular, the extraction of the internuclear potential and the inertial mass parameter is performed using two different methods. A fusion hindrance mechanism for heavy systems is investigated from the microscopic point of view. The canonical collective variables are determined by the adiabatic self-consistent collective coordinate method. Preliminary results of the spontaneous fission path, the potential, and the collective mass parameter are shown for 8Be --> alpha+alpha.

  14. Birgit Arb, MD Cape Fear Cancer

    E-Print Network [OSTI]

    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

  15. Strategic Plan Update Lydia Pleotis Howell MD

    E-Print Network [OSTI]

    Leistikow, Bruce N.

    and Laboratory Medicine #12;Present Findings from: Planning Interviews Stakeholder Survey Environmental diagnostic testing that is tailored to the prevention and management of disease. 4. Develop a culture organization Howell, CAOs #12;Increase our diversity efforts Recommendations from David Acosta MD, UCDHS' new

  16. Driven cavity flow: from molecular dynamics to continuum hydrodynamics

    E-Print Network [OSTI]

    Tiezheng Qian; Xiao-Ping Wang

    2004-03-06

    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.

  17. Electron dynamics in complex environments with real-time time dependent density functional theory in a QM-MM framework

    SciTech Connect (OSTI)

    Morzan, Uriel N.; Ramírez, Francisco F.; Scherlis, Damián A. E-mail: mcgl@qb.ffyb.uba.ar; Lebrero, Mariano C. González E-mail: mcgl@qb.ffyb.uba.ar

    2014-04-28

    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.

  18. The density matrix functional approach to electron correlation: Dynamic and nondynamic correlation along the full dissociation coordinate

    SciTech Connect (OSTI)

    Mentel, ?. M.; Meer, R. van; Gritsenko, O. V.; Baerends, E. J.

    2014-06-07

    For chemistry an accurate description of bond weakening and breaking is vital. The great advantage of density matrix functionals, as opposed to density functionals, is their ability to describe such processes since they naturally cover both nondynamical and dynamical correlation. This is obvious in the Löwdin-Shull functional, the exact natural orbital functional for two-electron systems. We present in this paper extensions of this functional for the breaking of a single electron pair bond in N-electron molecules, using LiH, BeH{sup +}, and Li{sub 2} molecules as prototypes. Attention is given to the proper formulation of the functional in terms of not just J and K integrals but also the two-electron L integrals (K integrals with a different distribution of the complex conjugation of the orbitals), which is crucial for the calculation of response functions. Accurate energy curves are obtained with extended Löwdin-Shull functionals along the complete dissociation coordinate using full CI calculations as benchmark.

  19. Practical Attacks on Digital Signatures Using MD5 Message Digest

    E-Print Network [OSTI]

    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

  20. Poster Presentations Marcella Alsan, MD, MPH, PhD

    E-Print Network [OSTI]

    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

  1. Free Energy Calculation in MD Simulation

    E-Print Network [OSTI]

    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

  2. Interactions between Ether Phospholipids and Cholesterol as Determined by Scattering and Molecular Dynamics Simulations

    SciTech Connect (OSTI)

    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

    2012-01-01

    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.

  3. High-dynamic-range extinction mapping of infrared dark clouds: Dependence of density variance with sonic Mach number in molecular clouds

    E-Print Network [OSTI]

    Kainulainen, Jouni

    2012-01-01

    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...

  4. Reactive MD Simulations of Electrochemical Oxide Interfaces at...

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

    National Laboratory Reactive MD Simulations of Electrochemical Oxide Interfaces at Mesoscale PI Name: Subramanian Sankaranarayanan PI Email: skrssank@anl.gov Institution:...

  5. 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...

  6. A time-dependent momentum-space density functional theoretical approach for electron transport dynamics in molecular devices

    E-Print Network [OSTI]

    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

  7. Mapping molecular dynamics computations to hypercubes 

    E-Print Network [OSTI]

    Lakamsani, Vamsee Krishna

    1993-01-01

    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...

  8. High Performance Molecular Dynamic Simulation on Single and Multi-GPU Systems

    SciTech Connect (OSTI)

    Villa, Oreste; Chen, Long; Krishnamoorthy, Sriram

    2010-05-30

    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.

  9. RECOMMENDATION FORM UMBC Office of Financial Aid & Scholarships, 1000 Hilltop Circle, Baltimore, MD 21250

    E-Print Network [OSTI]

    Biswas, Animikh

    RECOMMENDATION FORM UMBC Office of Financial Aid & Scholarships, 1000 Hilltop Circle, Baltimore, MD of Financial Aid & Scholarships 1000 Hilltop Circle Baltimore, MD 21250 Name

  10. Low power low-density parity-checking (ldpc) codes decoder design using dynamic voltage and frequency scaling 

    E-Print Network [OSTI]

    Wang, Weihuang

    2009-05-15

    This thesis presents a low-power LDPC decoder design based on speculative scheduling of energy necessary to decode dynamically varying data frame in both block-fading channels and general AWGN channels. A model of a ...

  11. Single-block collision attack on MD5 Marc Stevens

    E-Print Network [OSTI]

    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

  12. Molly Carnes, MD, MS Professor, Depts of Medicine,

    E-Print Network [OSTI]

    Sheridan, Jennifer

    Molly Carnes, MD, MS Professor, Depts of Medicine, Psychiatry, and Industrial & Systems Engineering University of Wisconsin-Madison Careers in Academic Medicine:Careers in Academic Medicine: Evaluation at

  13. A molecular dynamics study of polymer/graphene interfacial systems

    SciTech Connect (OSTI)

    Rissanou, Anastassia N.; Harmandaris, Vagelis

    2014-05-15

    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.

  14. Enhanced reactivity of nanoenergetic materials: A first-principles molecular dynamics study based on divide-and-conquer density

    E-Print Network [OSTI]

    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

  15. Proton radiography of dynamic electric and magnetic fields in laser-produced high-energy-density plasmasa...

    E-Print Network [OSTI]

    Proton radiography of dynamic electric and magnetic fields in laser-produced high-energy measurements of the electric E and magnetic B fields produced in laser-foil interactions and during, and dissipation of self-generated electric E and magnetic B fields by inter- actions of laser light with matter1

  16. Charge transport through bio-molecular wires in a solvent: Bridging molecular dynamics and model Hamiltonian approaches

    E-Print Network [OSTI]

    R. Gutierrez; R. Caetano; P. B. Woiczikowski; T. Kubar; M. Elstner; G. Cuniberti

    2009-01-22

    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.

  17. Excited-state quantum phase transitions in systems with two degrees of freedom: Level density, level dynamics, thermal properties

    SciTech Connect (OSTI)

    Stránský, Pavel; Macek, Michal; Cejnar, Pavel

    2014-06-15

    Quantum systems with a finite number of freedom degrees f develop robust singularities in the energy spectrum of excited states as the system’s size increases to infinity. We analyze the general form of these singularities for low f, particularly f=2, clarifying the relation to classical stationary points of the corresponding potential. Signatures in the smoothed energy dependence of the quantum state density and in the flow of energy levels with an arbitrary control parameter are described along with the relevant thermodynamical consequences. The general analysis is illustrated with specific examples of excited-state singularities accompanying the first-order quantum phase transition. -- Highlights: •ESQPTs found in infinite-size limit of systems with low numbers of freedom degrees f. •ESQPTs related to non-analytical evolutions of classical phase–space properties. •ESQPT signatures analyzed for general f, particularly f=2, extending known case f=1. •ESQPT signatures identified in smoothened density and flow of energy spectrum. •ESQPTs shown to induce a new type of thermodynamic anomalies.

  18. MD Simulation Study of the Influence of Branch Content on Relaxation and Crystallization of Branched Polyethylene Chains with Uniform Branch Distribution

    E-Print Network [OSTI]

    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

  19. Corey Casper, MD Head, Program in Global Oncology

    E-Print Network [OSTI]

    Brent, Roger

    Corey Casper, MD Head, Program in Global Oncology Member, Vaccine and Infectious Disease and Public of Washington Dr. Casper focuses on infection-related cancers and cancer in low-resource settings. He is the Head of the Program in Global Oncology at the Fred Hutchinson Cancer Research Center, where he is also

  20. Eric G. Neilson, MD DEAN OF FEINBERG SCHOOL OF

    E-Print Network [OSTI]

    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

  1. Cancer Research in Botswana Surbhi Grover, MD MPH

    E-Print Network [OSTI]

    Bushman, Frederic

    Cancer Research in Botswana Surbhi Grover, MD MPH Assistant Professor, Radiation Oncology, UPENN and are developing cancers and other NCDs #12;3 HIV and Cancer wHIV infection increases the risk of cancer wIn the later stages of HIV infection, chronic immunosuppression (& other co-factors) leads to cancer formation

  2. One Physics Ellipse College Park, MD 20740-3844

    E-Print Network [OSTI]

    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

  3. Proportional Contact Representations of Planar Graphs Md. J. Alam1

    E-Print Network [OSTI]

    Kobourov, Stephen G.

    Proportional Contact Representations of Planar Graphs Md. J. Alam1 , T. Biedl2 , S. Felsner3 , M-contact between the corresponding polygons. Specifically, we consider proportional contact representations, where, the cartographic error, and the unused area. We describe construc- tive algorithms for proportional contact

  4. Molly Carnes, MD, MS Professor, Depts of Medicine,

    E-Print Network [OSTI]

    Sheridan, Jennifer

    Molly Carnes, MD, MS Professor, Depts of Medicine, Psychiatry, and Industrial & Systems Engineering University of Wisconsin-Madison Careers in Academic Medicine: Evaluation at Gatekeeping Junctures #12;AAMC (N=0) 0 Dept Medicine Chairs at top 25: #12;What about geriatrics? Year med school graduation 1980

  5. md Science Service Featuro By Dr. Charles F. Brooks

    E-Print Network [OSTI]

    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

  6. TSUNAMI INUNDATION MAPPING FOR OCEAN CITY, MD NGDC DEM

    E-Print Network [OSTI]

    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

  7. A new algorithm for contact angle estimation in molecular dynamics simulations

    E-Print Network [OSTI]

    Sumith YD; Shalabh C. Maroo

    2015-05-22

    It is important to study contact angle of a liquid on a solid surface to understand its wetting properties, capillarity and surface interaction energy. While performing transient molecular dynamics (MD) simulations it requires calculating the time evolution of contact angle. This is a tedious effort to do manually or with image processing algorithms. In this work we propose a new algorithm to estimate contact angle from MD simulations directly and in a computationally efficient way. This algorithm segregates the droplet molecules from the vapor molecules using Mahalanobis distance (MND) technique. Then the density is smeared onto a 2D grid using 4th order B-spline interpolation function. The vapor liquid interface data is estimated from the grid using density filtering. With the interface data a circle is fitted using Landau method. The equation of this circle is solved for obtaining the contact angle. This procedure is repeated by rotating the droplet about the vertical axis. We have applied this algorithm to a number of studies (different potentials and thermostat methods) which involves the MD simulation of water.

  8. End-to-End Rate-Distortion Optimized MD Mode Selection for Multiple Description Video Coding

    E-Print Network [OSTI]

    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 ...

  9. COPD, INFLAMMATION, AND LUNG CANCER Jerome S Brody, M.D., Professor of Medicine

    E-Print Network [OSTI]

    1 COPD, INFLAMMATION, AND LUNG CANCER Jerome S Brody, M.D., Professor of Medicine and Avrum Spira, M.D., Assistant Professor of Medicine Pulmonary Center and Department of Medicine Boston University School of Medicine Corresponding Author; Jerome S Brody, MD Pulmonary Center Boston University School

  10. Local control theory in trajectory-based nonadiabatic dynamics

    SciTech Connect (OSTI)

    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)

    2011-10-15

    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.

  11. Brain-Computer Interfaces in Medicine Jerry J. Shih, MD; Dean J. Krusienski, PhD; and Jonathan R. Wolpaw, MD

    E-Print Network [OSTI]

    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

  12. UC Davis-LLNL Scientific Advisory Committee Timothy Albertson, MD, PhD, Vice Chair, Internal Medicine

    E-Print Network [OSTI]

    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

  13. C h d Heterogeneity of A d h h Deficiency Lucia Morandi, MD,* Rita Barresi, PhD,* Claudia Di Blasi, PhD,* Daniel Jung, PhD,?

    E-Print Network [OSTI]

    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

  14. Anharmonic lattice dynamics of Ag2O studied by inelastic neutron scattering and first-principles molecular dynamics simulations

    SciTech Connect (OSTI)

    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

    2014-01-01

    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.

  15. Ab initio molecular dynamics simulation of pressure-induced phase transformation of BeO

    SciTech Connect (OSTI)

    Xiao, H. Y.; Duan, G.; Zu, X. T.; Weber, W. J.

    2011-05-05

    Ab initio molecular dynamics (MD) method has been used to study high pressure-induced phase transformation in BeO based on the local density approximation (LDA) and the generalized gradient approximation (GGA). Both methods show that the wurtzite (WZ) and zinc blende (ZB) BeO transforms to the rocksalt (RS) structure smoothly at high pressure. The transition pressures obtained from the LDA method are about 40 GPa larger than the GGA result for both WZ ? RS and ZB ? RS phase transformations, and the phase transformation mechanisms revealed by the LDA and GGA methods are different. For WZ ? RS phase transformations both mechanisms obtained from the LDA and GGA methods are not comparable to the previous ab initio MD simulations of WZ BeO at 700 GPa based on the GGA method. It is suggested that the phase transformation mechanisms of BeO revealed by the ab initio MD simulations are affected remarkably by the exchange–correlation functional employed and the way of applying pressure.

  16. The Molecular Structure of a Phosphatidylserine Bilayer Determined by Scattering and Molecular Dynamics Simulations

    SciTech Connect (OSTI)

    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

    2014-01-01

    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.

  17. Phenol-benzene complexation dynamics: Quantum chemistry calculation, molecular dynamics simulations, and two dimensional IR spectroscopy

    E-Print Network [OSTI]

    Fayer, Michael D.

    Phenol-benzene complexation dynamics: Quantum chemistry calculation, molecular dynamics simulations the nature and dynamics of the phenol-benzene complex in the mixed solvent, benzene/CCl4. Under thermal used for the phenol-benzene interaction in the MD simulations is in good accord with the highest level

  18. Time-dependent density-functional theory for strong-field multiphoton processes: Application to the study of the role of dynamical electron correlation

    E-Print Network [OSTI]

    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

  19. Molecular Dynamics Simulations of Heat Transfer In Nanoscale Liquid Films 

    E-Print Network [OSTI]

    Kim, Bo Hung

    2010-07-14

    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...

  20. Coupling all-atom molecular dynamics simulations of ions in water with Brownian dynamics

    E-Print Network [OSTI]

    Radek Erban

    2015-08-12

    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.

  1. PARALLEL MOLECULAR DYNAMICS WITH THE EMBEDDED ATOM METHOD STEVEN J. PLIMPTON and BRUCE A. HENDRICKSON

    E-Print Network [OSTI]

    Plimpton, Steve

    ,2] is a popular choice for the energy functional in MD simulations. It overcomes the volume­ dependent limitation capabilities for using molecular dynamics (MD) to simulate larger numbers of atoms and longer time scales community for modeling solids and liquids at the atomic level. Each atom in the simulation is treated

  2. A Molecular Dynamics Simulation of the Turbulent Couette Minimal Flow Unit

    E-Print Network [OSTI]

    Smith, E R

    2015-01-01

    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 ...

  3. 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

    2015-04-09

    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

  4. LDRD Final Report (08-ERD-037): Important Modes to Drive Protein MD Simulations to the Next Conformational Level

    SciTech Connect (OSTI)

    Sadigh, B

    2011-04-07

    Every action in biology is performed by dynamic proteins that convert between multiple states in order to engage their functions. Often binding to various ligands is essential for the rates of desired transitions to be enhanced. The goal of computational biology is to study these transitions and discover the different states to fully understand the protein's normal and diseased function, design drugs to target/bias specific states, and understand all of the interactions in between. We have developed a new methodology that is capable of calculating the absolute free energy of proteins while taking into account all the interactions with the solvent molecules. The efficiency of the new scheme is an order of magnitude greater than any existing technique. This method is now implemented in the massively parallel popular MD program package NAMD. This now makes it possible to calculate the relative stability of different conformational states of biological macromolecules as well as their binding free energies to various ligands.

  5. 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 &...

  6. Vehicle Technologies Office Merit Review 2015: Cummins MD & HD Accessory Hybridization CRADA

    Office of Energy Efficiency and Renewable Energy (EERE)

    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 &...

  7. Catharine Whiteside, MD PhD Vice Provost, Relations with Health Care Institutions

    E-Print Network [OSTI]

    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

  8. Julie Gralow, MD Director Breast Medical Oncology, Seattle Cancer Care Alliance

    E-Print Network [OSTI]

    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

  9. Automatic Search of Differential Path in MD4 Pierre-Alain Fouque, Gatan Leurent, Phong Nguyen

    E-Print Network [OSTI]

    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

  10. A career in bioengineering Christopher Chen, MD '99, PhD (MEMP '97) is the Skirkanich

    E-Print Network [OSTI]

    Gabrieli, John

    A career in bioengineering Christopher Chen, MD '99, PhD (MEMP '97) is the Skirkanich Professor of Innovation in Bioengineering at the University of Pennsylvania, where he directs the Tissue Microfabrication

  11. Parametrization of coarse grained force fields for dynamic property of ethylene glycol oligomers/water binary mixtures

    E-Print Network [OSTI]

    Tamio Yamazaki

    2012-08-06

    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.

  12. Phenomenological Relativistic Energy Density Functionals

    SciTech Connect (OSTI)

    Lalazissis, G. A.; Kartzikos, S.; Niksic, T.; Paar, N.; Vretenar, D.; Ring, P.

    2009-08-26

    The framework of relativistic nuclear energy density functionals is applied to the description of a variety of nuclear structure phenomena, not only in spherical and deformed nuclei along the valley of beta-stability, but also in exotic systems with extreme isospin values and close to the particle drip-lines. Dynamical aspects of exotic nuclear structure is explored using the fully consistent quasiparticle random-phase approximation based on the relativistic Hartree-Bogoliubov model. Recent applications of energy density functionals with explicit density dependence of the meson-nucleon couplings are presented.

  13. Subsystem Density-Functional Theory as an Effective Tool for Modeling Ground and Excited States, their Dynamics, and Many-Body Interactions

    E-Print Network [OSTI]

    Krishtal, Alisa; Genova, Alessandro; Pavanello, Michele

    2015-01-01

    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.

  14. Density hysteresis of heavy water confined in a nanoporous silica matrix

    E-Print Network [OSTI]

    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

  15. Form: REG113 2007 University of Maryland, Baltimore County 1000 Hilltop Circle, Baltimore, MD 21250 410-455-2500 Questions? Email: records@umbc.edu

    E-Print Network [OSTI]

    Suri, Manil

    __________________________________________________________________________________________________________________________________ © 2007 University of Maryland, Baltimore County · 1000 Hilltop Circle, Baltimore, MD 21250 · 410

  16. Form: REG112 2007 University of Maryland, Baltimore County 1000 Hilltop Circle, Baltimore, MD 21250 410-455-2500 Questions? Email: records@umbc.edu

    E-Print Network [OSTI]

    Suri, Manil

    __________________________________________________________________________________________________________________________________ © 2007 University of Maryland, Baltimore County · 1000 Hilltop Circle, Baltimore, MD 21250 · 410

  17. Form: REG102 2007 University of Maryland, Baltimore County 1000 Hilltop Circle, Baltimore, MD 21250 410-455-2500 Questions? Email: records@umbc.edu

    E-Print Network [OSTI]

    Suri, Manil

    __________________________________________________________________________________________________________________________________ © 2007 University of Maryland, Baltimore County · 1000 Hilltop Circle, Baltimore, MD 21250 · 410

  18. 2007 University of Maryland, Baltimore County 1000 Hilltop Circle, Baltimore, MD 21250 410-455-2500 Questions? Email: records@umbc.edu OFFICE OF THE REGISTRAR

    E-Print Network [OSTI]

    Suri, Manil

    University of Maryland, Baltimore County 1000 Hilltop Circle, Baltimore, MD 21250 410-455-2500 Questions

  19. Mapping the energy and diffusion landscapes of membrane proteins at the cell surface using high-density single-molecule imaging and Bayesian inference: application to the multi-scale dynamics of glycine receptors in the neuronal membrane

    E-Print Network [OSTI]

    Masson, Jean-Baptiste; Salvatico, Charlotte; Renner, Marianne; Specht, Christian G; Triller, Antoine; Dahan, Maxime

    2015-01-01

    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...

  20. Reaction dynamics of OH{sup +}({sup 3}{sigma}{sup -})+C{sub 2}H{sub 2} studied with crossed beams and density functional theory calculations

    SciTech Connect (OSTI)

    Liu Li; Martin, Courtney; Farrar, James M. [Department of Chemistry, University of Rochester, Rochester, New York 14627 (United States)

    2006-10-07

    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.

  1. Reaction dynamics study of O{sup -}+C{sub 2}H{sub 2} with crossed beams and density-functional theory calculations

    SciTech Connect (OSTI)

    Liu Li; Li Yue; Farrar, James M. [Department of Chemistry, University of Rochester, Rochester, New York 14627 (United States)

    2005-09-01

    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.

  2. Fluid transport properties by equilibrium molecular dynamics. II. Multicomponent systems

    E-Print Network [OSTI]

    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

  3. Trajectory Optimization for Dynamic Needle Insertion* Matt Heverly and Pierre Dupont John Triedman, MD

    E-Print Network [OSTI]

    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

  4. Molecular dynamics simulation of complex molecules at interfaces: dendritic surfactants in clay and amyloid peptides near lipid bilayers 

    E-Print Network [OSTI]

    Han, Kunwoo

    2009-06-02

    We apply a molecular dynamics (MD) simulation technique to complex molecules at interfaces. Partitioning of dendritic surfactants into clay gallery and Ab protein behavior near hydrated lipids are chosen for the purpose. ...

  5. Dynamics of Different Hydrogen Classes in -lactoglobulin: A Quasielastic Neutron Scattering Investigation

    E-Print Network [OSTI]

    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

  6. Molecular Dynamics Simulations of Shock-Induced Thermite Reaction Vikas Tomar1,a

    E-Print Network [OSTI]

    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

  7. Density constrained TDHF

    E-Print Network [OSTI]

    V. E. Oberacker; A. S. Umar

    2015-02-13

    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.

  8. Density constrained TDHF

    E-Print Network [OSTI]

    Oberacker, V E

    2015-01-01

    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.

  9. HIV-1 Tat membrane interactions probed using X-ray and neutron scattering, CD spectroscopy and MD simulations

    E-Print Network [OSTI]

    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

  10. iPad: Semantic Annotation and Markup of Radiological Images Daniel L. Rubin, MS, MD,*1,2

    E-Print Network [OSTI]

    Rubin, Daniel L.

    image content in a standard machine-interpretable format. A tool permitting researchers to describe Rodriguez, MD,1 Priyanka Shah,3 and Chris Beaulieu, MD, PhD2 1 Center for Biomedical Informatics Research, 2 trials. Thus, much critical radiological image information is not directly accessible to machines, unlike

  11. Enhancing the MD-Strengthening and Designing Scalable Families of One-Way Hash Algorithms

    E-Print Network [OSTI]

    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

  12. Noise and Signal for Spectra of Intermittent Noiselike Emission C. R. Gwinn, M.D. Johnson

    E-Print Network [OSTI]

    Gwinn, Carl

    Noise and Signal for Spectra of Intermittent Noiselike Emission C. R. Gwinn, M.D. Johnson, affects the distribution of noise in the observed correlation function. Intermittency also affects correlation of noise among channels of the spectrum, but leaves the average spectrum, average correlation

  13. Ira Helfand, MD International Physicians for the Prevention of Nuclear War

    E-Print Network [OSTI]

    Robock, Alan

    the urgent need to move with all possible speed to the negotiation of a nuclear weapons conventionIra 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

  14. Adaptive Regression Testing Strategy: An Empirical Study Md. Junaid Arafeen and Hyunsook Do

    E-Print Network [OSTI]

    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

  15. CityBizList US Green Building Council -MD Celebrating Move to

    E-Print Network [OSTI]

    design movement. Schilling Green, a 106,208-square-foot, three-story, Class A office building, obtainedCityBizList US Green Building Council - MD Celebrating Move to Hunt Valley Share Email this Article Baltimore County Executive Jim Smith will join the U.S. Green Building Council Maryland to celebrate

  16. Limbic System Page 1 of 10 Srdjan D. Antic, M.D. Limbic system Emotional Experience

    E-Print Network [OSTI]

    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

  17. February 16, 2008 Connecting renewal age processes and M/D/1

    E-Print Network [OSTI]

    a connection between each of these models through the first hitting time of the renewal age process. FurtherFebruary 16, 2008 Connecting renewal age processes and M/D/1 processor sharing queues through stick breaking J.S.H. van Leeuwaarden1 A.H. L¨opker2 A.J.E.M. Janssen3 Abstract: The renewal age process

  18. Hot Water DJ: Saving Energy by Pre-mixing Hot Water Md Anindya Prodhan

    E-Print Network [OSTI]

    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

  19. A survey on vehicular cloud computing Md Whaiduzzaman a,n

    E-Print Network [OSTI]

    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

  20. July 7-10, 2015 National Institute of Standards and Technology Gaithersburg, MD

    E-Print Network [OSTI]

    requirements, which cover cloud security, cloud services, technical language for SLAs, cloud metrics breaches, or to proactively support security and forensics cloud-based applications. In June, 2014 NISTJuly 7-10, 2015 National Institute of Standards and Technology Gaithersburg, MD NIST Cloud

  1. A Word from the Director Frank S. Pidcock, MD, Vice President of Rehabilitation at Kennedy Krieger

    E-Print Network [OSTI]

    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

  2. A Word from the Director Frank S. Pidcock, MD, Vice President of Rehabilitation at Kennedy Krieger

    E-Print Network [OSTI]

    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

  3. Cost Analysis of NEMO Protocol Entities Md. Shohrab Hossain, Mohammed Atiquzzaman, William Ivancic

    E-Print Network [OSTI]

    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

  4. Cost Analysis of Mobility Management Entities of Md. Shohrab Hossain, Mohammed Atiquzzaman

    E-Print Network [OSTI]

    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

  5. On Tackling Virtual Data Center Embedding Md Golam Rabbani, Rafael Pereira Esteves, Maxim Podlesny, Gwendal Simon

    E-Print Network [OSTI]

    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

  6. On Tackling Virtual Data Center Embedding Md Golam Rabbani, Rafael Esteves, Maxim Podlesny, Gwendal Simon

    E-Print Network [OSTI]

    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

  7. Intraoperative Electrochemotherapy of Colorectal Liver Metastases IBRAHIM EDHEMOVIC, MD, MSc,1

    E-Print Network [OSTI]

    Ljubljana, University of

    MALI, PhD,3 TOMAZ JARM, PhD,3 BOR KOS, PhD,3 DENIS PAVLIHA, PhD,3 BILJANA GRCAR KUZMANOV, MD, PhD,1 Ljubljana, Ljubljana, Slovenia 3 Department of Biomedical Engineering, Faculty of Electrical Engineering

  8. Advanced age remains an Achilles heel for liver resections. Laurent Sulpice, MD1,3

    E-Print Network [OSTI]

    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

  9. Body Pose based Pedestrian Tracking in a Particle Filtering Framework Md. Junaedur Rahman1

    E-Print Network [OSTI]

    Nebel, Jean-Christophe

    Body Pose based Pedestrian Tracking in a Particle Filtering Framework Md. Junaedur Rahman1 , Jesus.makris}@kingston.ac.uk ] Abstract A novel body pose based human tracking model is proposed for pedestrian tracking. This work investigates the challenges of reliable pedestrian tracking and pro- poses an improved model under challenging

  10. Faculty of Medicine, Primary Care and Population Sciences PhD/MD students Name Title Email

    E-Print Network [OSTI]

    Molinari, Marc

    Faculty of Medicine, Primary Care and Population Sciences ­ PhD/MD students Name Title Email Primary Supervisor in Faculty of Medicine, PCPS Professor Paul Roderick Sara Afshar Multimorbidities: its14@soton.ac.uk Primary Supervisor in Faculty of Medicine, PCPS Dr Julie Parkes Emma Richards

  11. A coupled RISM/MD or MC simulation methodology for solvation free energies

    E-Print Network [OSTI]

    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

  12. Mar. Drugs 2015, 13, 3154-3181; doi:10.3390/md13053154 marine drugs

    E-Print Network [OSTI]

    Paré, Paul W.

    Mar. Drugs 2015, 13, 3154-3181; doi:10.3390/md13053154 marine drugs ISSN 1660-3397 www.mdpi.com/journal/marinedrugs Review Molecular Architecture and Biomedical Leads of Terpenes from Red Sea Marine Invertebrates Mohamed Costantino Received: 9 April 2015 / Accepted: 7 May 2015 / Published: 20 May 2015 Abstract: Marine

  13. Mar. Drugs 2013, 11, 4370-4389; doi:10.3390/md11114370 marine drugs

    E-Print Network [OSTI]

    Eirin Lopez, Jose Maria

    Mar. Drugs 2013, 11, 4370-4389; doi:10.3390/md11114370 marine drugs ISSN 1660-3397 www.mdpi.com/journal/marinedrugs Review Bivalve Omics: State of the Art and Potential Applications for the Biomonitoring of Harmful Marine of the marine ecosystem, constitute very valuable commercial resources in aquaculture, and have been widely used

  14. Updated February 2015 UMBC 1000 Hilltop Circle, Baltimore, MD 21250 410-455-2729 Questions? Email: arc@umbc.edu Student Information (Please print)

    E-Print Network [OSTI]

    Suri, Manil

    Updated February 2015 UMBC · 1000 Hilltop Circle, Baltimore, MD 21250 · 410-455-2729 Questions IN EXCESS CREDITS #12;Updated February 2015 UMBC · 1000 Hilltop Circle, Baltimore, MD 21250 · 410

  15. To be presented in the 2005 American Society for Photogrammetry & Remote Sensing, (ASPRS) Annual Conference March 7-11, 2005, Baltimore, MD

    E-Print Network [OSTI]

    Plaza, Antonio J.

    Conference March 7-11, 2005, Baltimore, MD 1 DESIGN OF FAST ALGORITHMS FOR PIXEL PURITY INDEX FOR ENDMEMBER Engineering University of Maryland, Baltimore County, Baltimore, MD 21250 2 Computer Science Department

  16. Multiscale molecular dynamics using the matched interface and boundary method

    SciTech Connect (OSTI)

    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)

    2011-01-20

    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.

  17. In Proceedings of the 25th International System Safety Conference, eds. A. G. Boyer and N. J. Gauthier, Baltimore, MD, 2007, System Safety Society, 581-589.

    E-Print Network [OSTI]

    . Gauthier, Baltimore, MD, 2007, System Safety Society, 581-589. A Comparison of Wake-Vortex Models for Use

  18. Density and spin-density excitations in normal-liquid 3 Commissariat a` l'Energie Atomique, Departement de Recherche Fondamentale sur la Matie`re Condensee,

    E-Print Network [OSTI]

    Glyde, Henry R.

    Density and spin-density excitations in normal-liquid 3 He B. Fa°k Commissariat a` l'Energie , the density response is dominated by a single collective zero- sound mode. The mode energy is well described incorporate this central physical feature into the density and spin-density dynamics of normal-liquid 3 He

  19. * Correspondence to: C. H. Morrell, Mathematical Sciences Department, Loyola College, 4501 North Charles Street, Baltimore, MD 21210 U.S.A.

    E-Print Network [OSTI]

    Morrell, Christopher H.

    Charles Street, Baltimore, MD 21210 U.S.A. Contract grant sponsor: National Institute on Deafness North Charles Street, Baltimore, MD 21210 U.S.A. Longitudinal Studies Branch, Gerontology Research Center, National Institute on Aging, Baltimore, MD 21224, U.S.A. Hearing and Speech Sciences, University

  20. Control-volume representation of molecular dynamics

    E-Print Network [OSTI]

    E. R. Smith; D. M. Heyes; D. Dini; T. A. Zaki

    2012-05-24

    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.

  1. Laboratory Density Functionals

    E-Print Network [OSTI]

    B. G. Giraud

    2007-07-26

    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.

  2. Rotational Relaxation of Ionic Molecules in Electrolyte Solutions. Anisotropy Relaxation and Molecular Dynamics Study

    E-Print Network [OSTI]

    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

  3. A continuum-atomistic method for incorporating Joule heating into classical molecular dynamics simulations

    E-Print Network [OSTI]

    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

  4. Automatic Search of Di#erential Path in MD4 PierreAlain Fouque, Gatan Leurent, Phong Nguyen

    E-Print Network [OSTI]

    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

  5. Supplementary Material A Molecular Dynamics Approach to the Structural

    E-Print Network [OSTI]

    Caflisch, Amedeo

    , the self-assembly process of hexamers was considered. Eighteen MD simulations of six peptides wereSupplementary Material A Molecular Dynamics Approach to the Structural Characterization of Amyloid trajectory, underwent a cluster analysis based on structural similarity1 . Single-peptide conformations were

  6. MD 715

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefield Municipal GasAdministration Medal01 Sandia NationalSecurityNuclearH-canyon |I6 Page 2 of 2

  7. Instabilities in the Nuclear Energy Density Functional

    E-Print Network [OSTI]

    M. Kortelainen; T. Lesinski

    2010-02-05

    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.

  8. Dynamics of Early Afterdepolarization (EAD)-mediated Arrhythmias

    E-Print Network [OSTI]

    Chang, Marvin G

    2012-01-01

    Hopkins  University,  Baltimore,  MD   1. Abraham  MR*,  oral  presentation),  Baltimore,  MD,  Sept  2005.   4.  Hopkins  University,  Baltimore,  MD   BS/MSE,  Biomedical  

  9. Time-dependent density-functional theory for strong-field multiphoton processes: Application to the study of the role of dynamical electron correlation in multiple high-order harmonic generation

    E-Print Network [OSTI]

    Tong, Xiao-Min; Chu, Shih-I

    1998-01-01

    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 ...

  10. Time-dependent density-functional theory for molecular processes in strong fields: Study of multiphoton processes and dynamical response of individual valence electrons of N2 in intense laser fields

    E-Print Network [OSTI]

    Chu, Xi; Chu, Shih-I

    2001-11-14

    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. ...

  11. FINDING OF MD SIGNIFICANT IMPACT FORMERLY UTILIZED HED/AEC SITES REMEDIAL ACTION PROGRAM:

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefield Municipal Gas &SCE-SessionsSouth DakotaRobbins and700, 1.Reports1E~ S·D3 WeldonY.B.FINDING OF MD

  12. Mode coupling theory of electrolyte dynamics: Time dependent diffusion, dynamic structure factor and solvation dynamics

    E-Print Network [OSTI]

    Susmita Roy; Subramanian Yashonath; Biman Bagchi

    2015-01-08

    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.

  13. Developing a Dynamic Pharmacophore Model for HIV-1 Integrase

    SciTech Connect (OSTI)

    Carlson, Heather A.; Masukawa, Keven M.; Rubins, Kathleen; Bushman, Frederic; Jorgensen, William L.; Lins, Roberto; Briggs, James; Mccammon, Andy

    2000-05-11

    We present the first receptor-based pharmacophore model for HIV-1 integrase. The development of ''dynamic'' pharmacophore models is a new method that accounts for the inherent flexibility of the active site and aims to reduce the entropic penalties associated with binding a ligand. Furthermore, this new drug discovery method overcomes the limitation of an incomplete crystal structure of the target protein. A molecular dynamics (MD) simulation describes the flexibility of the uncomplexed protein. Many conformational models of the protein are saved from the MD simulations and used in a series of multi-unit search for interacting conformers (MUSIC) simulations. MUSIC is a multiple-copy minimization method, available in the BOSS program; it is used to determine binding regions for probe molecules containing functional groups that complement the active site. All protein conformations from the MD are overlaid, and conserved binding regions for the probe molecules are identified. Those conserved binding regions define the dynamic pharmacophore model. Here, the dynamic model is compared to known inhibitors of the integrase as well as a three-point, ligand-based pharmacophore model from the literature. Also, a ''static'' pharmacophore model was determined in the standard fashion, using a single crystal structure. Inhibitors thought to bind in the active site of HIV-1 integrase fit the dynamic model but not the static model. Finally, we have identified a set of compounds from the Available Chemicals Directory that fit the dynamic pharmacophore model, and experimental testing of the compounds has confirmed several new inhibitors.

  14. 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

    2015-04-22

    An atom’s volume depends on its electronic density. Although this density can only be evaluated exactly for hydrogen-like atoms, there are many excellent numerical algorithms and packages to calculate it for other materials. 3D visualization of charge density is challenging, especially when several molecular/atomic levels are intertwined in space. We explore several approaches to 3D charge density visualization, including the extension of an anaglyphic stereo visualization application based on the AViz package to larger structures such as nanotubes. We will describe motivations and potential applications of these tools for answering interesting questions about nanotube properties.

  15. 11/20/00 1AVS98.Invited.pptAVS National Symposium, Baltimore, MD 11/2-6/98 G. W. Rubloff 1998

    E-Print Network [OSTI]

    Rubloff, Gary W.

    11/20/00 1AVS98.Invited.pptAVS National Symposium, Baltimore, MD 11/2-6/98 G. W. Rubloff ã1998 Engineering #12;11/20/00 2AVS98.Invited.pptAVS National Symposium, Baltimore, MD 11/2-6/98 G. W. Rubloff ã199898.Invited.pptAVS National Symposium, Baltimore, MD 11/2-6/98 G. W. Rubloff ã1998 Manufacturing

  16. Density-dependent covariant energy density functionals

    SciTech Connect (OSTI)

    Lalazissis, G. A.

    2012-10-20

    Relativistic nuclear energy density functionals are applied to the description of a variety of nuclear structure phenomena at and away fromstability line. Isoscalar monopole, isovector dipole and isoscalar quadrupole giant resonances are calculated using fully self-consistent relativistic quasiparticle randomphase approximation, based on the relativistic Hartree-Bogoliubovmodel. The impact of pairing correlations on the fission barriers in heavy and superheavy nuclei is examined. The role of pion in constructing desnity functionals is also investigated.

  17. Low density molded desiccant

    SciTech Connect (OSTI)

    Lula, J.W.

    1982-01-01

    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.

  18. Molecular dynamics and neutron scattering study of the dependence of polyelectrolyte dendrimer conformation on counterion behavior

    SciTech Connect (OSTI)

    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

    2012-01-01

    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.

  19. Predicting Low Energy Dopant Implant Profiles in Semiconductors using Molecular Dynamics

    SciTech Connect (OSTI)

    Beardmore, K.M.; Gronbech-Jensen, N.

    1999-05-02

    The authors present a highly efficient molecular dynamics scheme for calculating dopant density profiles in group-IV alloy, and III-V zinc blende structure materials. Their scheme incorporates several necessary methods for reducing computational overhead, plus a rare event algorithm to give statistical accuracy over several orders of magnitude change in the dopant concentration. The code uses a molecular dynamics (MD) model to describe ion-target interactions. Atomic interactions are described by a combination of 'many-body' and pair specific screened Coulomb potentials. Accumulative damage is accounted for using a Kinchin-Pease type model, inelastic energy loss is represented by a Firsov expression, and electronic stopping is described by a modified Brandt-Kitagawa model which contains a single adjustable ion-target dependent parameter. Thus, the program is easily extensible beyond a given validation range, and is therefore truly predictive over a wide range of implant energies and angles. The scheme is especially suited for calculating profiles due to low energy and to situations where a predictive capability is required with the minimum of experimental validation. They give examples of using the code to calculate concentration profiles and 2D 'point response' profiles of dopants in crystalline silicon and gallium-arsenide. Here they can predict the experimental profile over five orders of magnitude for <100> and <110> channeling and for non-channeling implants at energies up to hundreds of keV.

  20. Recovering position-dependent diffusion from biased molecular dynamics simulations

    SciTech Connect (OSTI)

    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)

    2014-02-28

    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.

  1. Irradiation effects in high-density polyethylene Jussi Polvia

    E-Print Network [OSTI]

    Nordlund, Kai

    Irradiation effects in high-density polyethylene Jussi Polvia , Kai Nordlunda a simulations, we have studied the irradiation effects in high density polyethylene. We determined the threshold for the hydrogen atoms in the polyethylene chain. Keywords: molecular dynamics, irradiation, damage threshold

  2. Accurate neutralino relic density

    E-Print Network [OSTI]

    Paolo Gondolo; Joakim Edsjo

    1998-04-30

    We enlarge our set of supersymmetric models and update accelerator constraints in our precise calculation of the relic density of the lightest neutralino, which includes relativistic Boltzmann averaging, subthreshold and resonant annihilations, and coannihilation processes among charginos and neutralinos.

  3. Three-phase permeabilities and other characteristics of 260-mD fired Berea

    SciTech Connect (OSTI)

    Maloney, D.; Brinkmeyer, A.

    1992-04-01

    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.

  4. Md. Mottaleb Hossain won "People's Choice" award in the student poster competition at CS/ECE Tech Day 2014 at The University of New Mexico

    E-Print Network [OSTI]

    New Mexico, University of

    Md. Mottaleb Hossain won "People's Choice" award in the student poster competition at CS/ECE Tech Day 2014 at The University of New Mexico CHTM and OSE-ECE graduate student, Md. Mottaleb Hossain, won a prestigious "People's Choice" award in the student poster competition at CS/ECE Tech Day 2014

  5. Alamethicin in lipid bilayers: Combined use of X-ray scattering and MD simulations Jianjun Pan a

    E-Print Network [OSTI]

    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

  6. Lung mast cells are a source of secreted phospholipases A2 Massimo Triggiani, MD, PhD,a

    E-Print Network [OSTI]

    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

  7. FRAppE: Detecting Malicious Facebook Applications Md Sazzadur Rahman, Ting-Kai Huang, Harsha V. Madhyastha, and Michalis Faloutsos

    E-Print Network [OSTI]

    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

  8. Redshift Evolution of Galaxy Cluster Densities

    E-Print Network [OSTI]

    R. G. Carlberg; S. L. Morris; H. K. C. Yee; E. Ellingson

    1997-01-20

    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.

  9. Cluster formation in sputtering: A molecular dynamics study using the MD/MC-corrected effective medium potential

    E-Print Network [OSTI]

    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

  10. Elliott et al. Reply: Zhang et al. [1] have carried out classical molecular dynamics (MD) simulations using a

    E-Print Network [OSTI]

    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

  11. Protein Molecular Dynamics With Electrostatic Force Entirely Determined by a Single Poisson-Boltzmann

    E-Print Network [OSTI]

    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

  12. Free energy and molecular dynamics calculations for the cubic-tetragonal phase transition in zirconia

    E-Print Network [OSTI]

    Paxton, Anthony T.

    in zirconia Stefano Fabris,* Anthony T. Paxton, and Michael W. Finnis Atomistic Simulation Group, Department zirconia is studied by molecu- lar dynamics MD simulations and within the framework of the Landau theory solutions of zirconia (ZrO2) with cubic stabilizing oxides like Y2O3, MgO or CeO, and are generally called

  13. X-ray Diffraction and Molecular Dynamics Study of Medium-range Order in Ambient and Hot Water

    E-Print Network [OSTI]

    Congcong Huang; K. T. Wikfeldt; D. Nordlund; U. Bergmann; T. McQueen; J. Sellberg; L. G. M. Pettersson; A. Nilsson

    2011-07-24

    We have developed x-ray diffraction measurements with high energy-resolution and accuracy to study water structure at three different temperatures (7, 25 and 66 C) under normal pressure. Using a spherically curved Ge crystal an energy resolution better than 15 eV has been achieved which eliminates influence from Compton scattering. The high quality of the data allows a precise oxygen-oxygen pair correlation function (PCF) to be directly derived from the Fourier transform of the experimental data resolving shell structure out to ~12 {\\AA}, i.e. 5 hydration shells. Large-scale molecular dynamics (MD) simulations using the TIP4P/2005 force-field reproduce excellently the experimental shell-structure in the range 4-12 {\\AA} although less agreement is seen for the first peak in the PCF. The Local Structure Index [J. Chem. Phys. 104, 7671 (1996)] identifies a tetrahedral minority giving the intermediate-range oscillations in the PCF and a disordered majority providing a more featureless background in this range. The current study supports the proposal that the structure of liquid water, even at high temperatures, can be described in terms of a two-state fluctuation model involving local structures related to the high-density and low-density forms of liquid water postulated in the liquid-liquid phase transition hypothesis.

  14. Measuring single-cell density

    E-Print Network [OSTI]

    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 ...

  15. High Energy Density Laboratory Plasmas

    E-Print Network [OSTI]

    High Energy Density Laboratory Plasmas General Plasma Science Developing founda/ons and advancing fundamental understanding #12;The High Energy Density developing innovative techniques to study the properties of instabilities in magnetized-high-energy-density

  16. Reliable Identification of Compton-thick Quasars at z~2: Spitzer Mid-IR spectroscopy of HDF-oMD49

    E-Print Network [OSTI]

    D. M. Alexander; R. R. Chary; A. Pope; F. E. Bauer; W. N. Brandt; E. Daddi; M. Dickinson; D. Elbaz; N. A. Reddy

    2008-07-15

    Many models that seek to explain the origin of the unresolved X-ray background predict that Compton-thick Active Galactic Nuclei (AGNs) are ubiquitious at high redshift. However, few distant Compton-thick AGNs have been reliably identified to date. Here we present Spitzer-IRS spectroscopy and 3.6-70um photometry of a z=2.2 optically identified AGN (HDF-oMD49) that is formally undetected in the 2Ms Chandra Deep Field-North (CDF-N) survey. The Spitzer-IRS spectrum and spectral energy distribution of this object is AGN dominated, and a comparison of the energetics at X-ray wavelengths to those derived from mid-infrared (mid-IR) and optical spectroscopy shows that the AGN is intrinsically luminous (L_X~3x10^44 erg/s) but heavily absorbed by Compton-thick material (N_H>>10^24 cm^{-2}); i.e., this object is a Compton-thick quasar. Adopting the same approach that we applied to HDF-oMD49, we found a further six objects at z~2-2.5 in the literature that are also X-ray weak/undetected but have evidence for AGN activity from optical and/or mid-IR spectroscopy, and show that all of these sources are also Compton-thick quasars with L_X>10^44 erg/s. On the basis of the definition of Daddi etal. (2007), these Compton-thick quasars would be classified as mid-IR excess galaxies, and our study provides the first spectroscopic confirmation of Compton-thick AGN activity in a subsample of these z~2 mid-IR bright galaxies. Using the four objects that lie in the CDF-N field, we estimate the space-density of Compton-thick quasars [Phi~(0.7-2.5)x10^-5 Mpc^-3 for L_X>10^44 erg/s objects at z~2-2.5] and show that Compton-thick accretion is as ubiquitious as unobscured accretion in the distant Universe.

  17. Multiple density layered insulator

    DOE Patents [OSTI]

    Alger, Terry W. (Tracy, CA)

    1994-01-01

    A multiple density layered insulator for use with a laser is disclosed wh 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.

  18. Kinetic distance and kinetic maps from molecular dynamics simulation

    E-Print Network [OSTI]

    Noe, Frank

    2015-01-01

    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...

  19. Molecular dynamics simulation of chains mobility in polyethylene crystal

    E-Print Network [OSTI]

    V. I. Sultanov; V. V. Atrazhev; D. V. Dmitriev; S. F. Burlatsky

    2014-01-17

    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.

  20. Orbital-optimized density cumulant functional theory

    SciTech Connect (OSTI)

    Sokolov, Alexander Yu. Schaefer, Henry F.

    2013-11-28

    In density cumulant functional theory (DCFT) the electronic energy is evaluated from the one-particle density matrix and two-particle density cumulant, circumventing the computation of the wavefunction. To achieve this, the one-particle density matrix is decomposed exactly into the mean-field (idempotent) and correlation components. While the latter can be entirely derived from the density cumulant, the former must be obtained by choosing a specific set of orbitals. In the original DCFT formulation [W. Kutzelnigg, J. Chem. Phys. 125, 171101 (2006)] the orbitals were determined by diagonalizing the effective Fock operator, which introduces partial orbital relaxation. Here we present a new orbital-optimized formulation of DCFT where the energy is variationally minimized with respect to orbital rotations. This introduces important energy contributions and significantly improves the description of the dynamic correlation. In addition, it greatly simplifies the computation of analytic gradients, for which expressions are also presented. We offer a perturbative analysis of the new orbital stationarity conditions and benchmark their performance for a variety of chemical systems.

  1. Fluid transport properties by equilibrium molecular dynamics. III. Evaluation of united atom interaction potential models for pure alkanes

    E-Print Network [OSTI]

    Dysthe, Dag Kristian

    Received 2 August 1999; accepted 9 February 2000 Results of new simulations for n-butane, n-decane, n and density of transport property studies by MD of n-butane, n-decane, and n-hexadecane using flexible, mul- tisite molecular models. In the case of n-butane there have been performed at least 14 transport

  2. Gedanken densities and exact constraints in density functional theory

    SciTech Connect (OSTI)

    Perdew, John P.; Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122 ; Ruzsinszky, Adrienn; Sun, Jianwei; Burke, Kieron

    2014-05-14

    Approximations to the exact density functional for the exchange-correlation energy of a many-electron ground state can be constructed by satisfying constraints that are universal, i.e., valid for all electron densities. Gedanken densities are designed for the purpose of this construction, but need not be realistic. The uniform electron gas is an old gedanken density. Here, we propose a spherical two-electron gedanken density in which the dimensionless density gradient can be an arbitrary positive constant wherever the density is non-zero. The Lieb-Oxford lower bound on the exchange energy can be satisfied within a generalized gradient approximation (GGA) by bounding its enhancement factor or simplest GGA exchange-energy density. This enhancement-factor bound is well known to be sufficient, but our gedanken density shows that it is also necessary. The conventional exact exchange-energy density satisfies no such local bound, but energy densities are not unique, and the simplest GGA exchange-energy density is not an approximation to it. We further derive a strongly and optimally tightened bound on the exchange enhancement factor of a two-electron density, which is satisfied by the local density approximation but is violated by all published GGA's or meta-GGA’s. Finally, some consequences of the non-uniform density-scaling behavior for the asymptotics of the exchange enhancement factor of a GGA or meta-GGA are given.

  3. Kinetic energy deficit in the symmetric fission of /sup 259/Md. [Light particle emission in /sup 256/Fm fission

    SciTech Connect (OSTI)

    Hulet, E.K.; Wild, J.F.; Lougheed, R.W.; Baisden, P.A.; Dougan, R.J.; Mustafa, M.G.

    1980-10-01

    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.

  4. Nonequilibrium Dynamics in Lattice Systems

    E-Print Network [OSTI]

    Steinhoff, Heinz-Jürgen

    Non­equilibrium Dynamics in Lattice Systems: Epitaxial Growth and Time dependent Density Functional . . . . . . . . . . . . . . . . . . . . . 9 2.3.1 Island densities . . . . . . . . . . . . . . . . . . . . . . . . 9 2.3.2 Island size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3.2 Kinetic Monte Carlo Simulations . . . . . . . . . . . . . . . . . . 15 3.2.1 Multi-island

  5. Dynamics study of the reaction OH{sup -}+C{sub 2}H{sub 2}{yields}C{sub 2}H{sup -}+H{sub 2}O with crossed beams and density-functional theory calculations

    SciTech Connect (OSTI)

    Liu Li; Li Yue; Farrar, James M. [Department of Chemistry, University of Rochester, Rochester, New York 14627 (United States)

    2006-03-28

    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.

  6. A Molecular Dynamics Study of Chemical Reactions of Solid Pentaerythritol Tetranitrate at Extreme Conditions

    SciTech Connect (OSTI)

    Wu, C J; Manaa, M R; Fried, L E

    2006-05-30

    We have carried out density functional based tight binding (DFTB) molecular dynamics (MD) simulation to study energetic reactions of solid Pentaerythritol Tetranitrate (PETN) at conditions approximating the Chapman-Jouguet (CJ) detonation state. We found that the initial decomposition of PETN molecular solid is characterized by uni-molecular dissociation of the NO{sub 2}groups. Interestingly, energy release from this powerful high explosive was found to proceed in several stages. The large portion of early stage energy release was found to be associated with the formation of H{sub 2}O molecules within a few picoseconds of reaction. It took nearly four times as long for majority of CO{sub 2} products to form, accompanied by a slow oscillatory conversion between CO and CO{sub 2}. The production of N{sub 2} starts after NO{sub 2} loses its oxygen atoms to hydrogen or carbon atoms to form H{sub 2}O or CO. We identified many intermediate species that emerge and contribute to reaction kinetics, and compared our simulation with a thermo-chemical equilibrium calculation. In addition, a detailed chemical kinetics of formation of H{sub 2}O, CO, and CO{sub 2} were developed. Rate constants of formations of H{sub 2}O, CO{sub 2} and N{sub 2} were reported.

  7. A NEW RECIPE FOR OBTAINING CENTRAL VOLUME DENSITIES OF PRESTELLAR CORES FROM SIZE MEASUREMENTS

    SciTech Connect (OSTI)

    Tassis, Konstantinos; Yorke, Harold W. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

    2011-07-10

    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.

  8. Nuclear Physics A 770 (2006) 131 Relativistic nuclear energy density functional

    E-Print Network [OSTI]

    Weise, Wolfram

    2006-01-01

    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

  9. Dynamical simulation of heavy-ion collisions in the energy range from a few tens MeV/A to a few hundreds MeV/A

    E-Print Network [OSTI]

    M. V. Garzelli

    2008-10-13

    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.

  10. A BIBLIOMETRIC ANALYSIS OF CLIMATE ENGINEERING RESEARCH Christopher W. Belter (Chris.Belter@noaa.gov), NOAA Central Library, LAC Group, Silver Spring, MD

    E-Print Network [OSTI]

    .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

  11. High Energy Density Capacitors

    SciTech Connect (OSTI)

    2010-07-01

    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.

  12. Simulations of liquid ribidium expanded to the critical density

    SciTech Connect (OSTI)

    Ross, M; Yang, L H; Pilgrim, W

    2006-05-16

    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.

  13. Effect of density dependent symmetry energy on Elliptical flow

    E-Print Network [OSTI]

    Suneel Kumar; Karan Singh Vinayak

    2011-08-30

    The effect of the density dependent symmetry energy on elliptical flow is studied using isospin-dependent quantum molecular dynamics model(IQMD). We have used the reduced isospin-dependent cross-section with soft equation of state to study the sensitivity of elliptical flow towards symmetry energy. Aim of the present study is to pin down the Elliptical flow for the various forms of the density dependent symmetry energy.

  14. Noncanonical Hamiltonian density formulation of hydrodynamics and ideal MHD

    SciTech Connect (OSTI)

    Morrison, P.J.; Greene, J.M.

    1980-04-01

    A new Hamiltonian density formulation of a perfect fluid with or without a magnetic field is presented. Contrary to previous work the dynamical variables are the physical variables, rho, v, B, and s, which form a noncanonical set. A Poisson bracket which satisfies the Jacobi identity is defined. This formulation is transformed to a Hamiltonian system where the dynamical variables are the spatial Fourier coefficients of the fluid variables.

  15. Nuclear Energy Density Optimization

    E-Print Network [OSTI]

    M. Kortelainen; T. Lesinski; J. Moré; W. Nazarewicz; J. Sarich; N. Schunck; M. V. Stoitsov; S. Wild

    2010-05-27

    We carry out state-of-the-art optimization of a nuclear energy density of Skyrme type in the framework of the Hartree-Fock-Bogoliubov (HFB) theory. The particle-hole and particle-particle channels are optimized simultaneously, and the experimental data set includes both spherical and deformed nuclei. The new model-based, derivative-free optimization algorithm used in this work has been found to be significantly better than standard optimization methods in terms of reliability, speed, accuracy, and precision. The resulting parameter set UNEDFpre results in good agreement with experimental masses, radii, and deformations and seems to be free of finite-size instabilities. An estimate of the reliability of the obtained parameterization is given, based on standard statistical methods. We discuss new physics insights offered by the advanced covariance analysis.

  16. Low density microcellular foams

    DOE Patents [OSTI]

    LeMay, James D. (Castro Valley, CA)

    1991-01-01

    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.

  17. Low density microcellular foams

    DOE Patents [OSTI]

    LeMay, James D. (Castro Valley, CA)

    1992-01-01

    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.

  18. Low density microcellular foams

    DOE Patents [OSTI]

    LeMay, J.D.

    1991-11-19

    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.

  19. Low density microcellular foams

    DOE Patents [OSTI]

    Aubert, J.H.; Clough, R.L.; Curro, J.G.; Quintana, C.A.; Russick, E.M.; Shaw, M.T.

    1985-10-02

    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.

  20. Low density microcellular foams

    DOE Patents [OSTI]

    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)

    1987-01-01

    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.

  1. Molecular Dynamics Simulations of Solutions at Constant Chemical Potential

    E-Print Network [OSTI]

    Perego, Claudio; Parrinello, Michele

    2015-01-01

    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...

  2. High Energy Density Microwaves

    SciTech Connect (OSTI)

    Phillips, R.M. [Stanford Linear Accelerator Center, Stanford, CA 94309 (United States)

    1999-04-01

    These proceedings represent papers presented at the RF98 Workshop entitled `High Energy Density Microwaves` held in California in October, 1998. The topics discussed were predominantly accelerator{minus}related. The Workshop dealt, for the most part, with the generation and control of electron beams, the amplification of RF signals, the design of mode converters, and the effect of very high RF field gradients. This Workshop was designed to address the concerns of the microwave tube industry worldwide, the plasma physicists who deal with very high beam currents and gigawatts of RF power, and researchers in accelerator centers around the world. Papers were presented on multibeam klystrons, gyrotron development, plasmas in microwave tubes, RF breakdown, and alternatives to conventional linear coliders at 1 TeV and above. The Workshop was partially sponsored by the US Department of Energy. There were 46 papers presented at the conference,out of which 19 have been abstracted for the Energy,Science and Technology database.(AIP)

  3. ORIGINAL PAPER BambooFiber Filled High Density Polyethylene Composites

    E-Print Network [OSTI]

    strength, bending modulus and strength were improved with the use of MAPE. The use of the clayORIGINAL PAPER Bamboo­Fiber Filled High Density Polyethylene Composites: Effect of Coupling to achieve clay exfoliation. For pure HDPE system, both dynamic and static bending moduli increased, while

  4. Energy trapping from Hagedorn densities of states

    E-Print Network [OSTI]

    Connor Behan; Klaus Larjo; Nima Lashkari; Brian Swingle; Mark Van Raamsdonk

    2013-04-26

    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.

  5. Soil Density/Moisture Gauge

    Broader source: Energy.gov [DOE]

    This scenario provides the planning instructions, guidance, and evaluation forms necessary to conduct an exercise involving a highway shipment of a soil moisture/density gauge (Class 7 -...

  6. A molecular dynamics study of the effect of a substrate on catalytic metal clusters in nucleation process of single-walled carbon nanotubes

    E-Print Network [OSTI]

    Maruyama, Shigeo

    process of single-walled carbon nanotubes Yasushi Shibuta1 *, Shigeo Maruyama2 1 Department of Materials of the substrate on catalytic metal clusters in nucleation process of single-walled carbon nanotubes was studied by classical molecular dynamics (MD) simulation. The melting point of a nickel cluster decreased

  7. Gossip-based density estimation in dynamic heterogeneous sensor networks

    E-Print Network [OSTI]

    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

  8. 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefield MunicipalTechnical Report: Achievements ofCOMPOSITION OF VAPORS FROM BOILINGChemCam on Marsand

  9. 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfate Reducing Bacteria (TechnicalTransmission,TextitSciTechin ComplexChi-NuSciTechand theSciTech

  10. Adiabatic electronic flux density: a Born-Oppenheimer Broken Symmetry ansatz

    E-Print Network [OSTI]

    Pohl, Vincent

    2015-01-01

    The Born-Oppenheimer approximation leads to the counterintuitive result of a vanishing electronic flux density upon vibrational dynamics in the electronic ground state. To circumvent this long known issue, we propose using pairwise anti-symmetrically translated vibronic densities to generate a symmetric electronic density that can be forced to satisfy the continuity equation approximately. The so-called Born-Oppenheimer broken symmetry ansatz yields all components of the flux density simultaneously while requiring only knowledge about the nuclear quantum dynamics on the electronic adiabatic ground state potential energy surface. The underlying minimization procedure is transparent and computationally inexpensive, and the solution can be computed from the standard output of any quantum chemistry program. Taylor series expansion reveals that the implicit electron dynamics originates from non-adiabatic coupling to the explicit Born-Oppenheimer nuclear dynamics. The new approach is applied to the ${\\rm H}_2^+$ mo...

  11. Charge transport, configuration interaction and Rydberg states under density functional theory

    E-Print Network [OSTI]

    Cheng, Chiao-Lun

    2008-01-01

    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 ...

  12. NUMERICAL PREDICTION OF LOCAL TEMPERATURE AND CURRENT DENSITY IN A PEM FUEL CELL

    E-Print Network [OSTI]

    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

  13. Direct Experimental Determination of Spectral Densities of Molecular Complexes

    E-Print Network [OSTI]

    Leonardo A. Pachon; Paul Brumer

    2014-10-15

    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.

  14. Nuclear Energy Density Functionals: What do we really know?

    E-Print Network [OSTI]

    Bulgac, Aurel; Jin, Shi

    2015-01-01

    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...

  15. Observation of the Density Minimum in Deeply Supercooled Confined Water

    E-Print Network [OSTI]

    Dazhi Liu; Yang Zhang; Chia-Cheng Chen; Chung-Yuan Mou; Peter H Poole; Sow-Hsin Chen

    2007-04-17

    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.

  16. Direct experimental determination of spectral densities of molecular complexes

    SciTech Connect (OSTI)

    Pachón, Leonardo A.; Brumer, Paul

    2014-11-07

    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.

  17. Molecular dynamics for 400 million particles with short-range interactions

    SciTech Connect (OSTI)

    Deng, Y.; McCoy, R.A.; Marr, R.B.

    1995-07-01

    We report the design and performance of a computational molecular dynamics (MD) code for 400 million particles interacting through the standard pairwise 6-12 Lennard-Jones potential on a 1024-node Intel Paragon, a distributed-memory MIMD parallel computer. The initially recorded {open_quotes}particle-step time{close_quotes} was .4 microseconds. A new inter-node communication strategy ensures high parallel efficiency for a large number of nodes. Besides the ability to tackle large problems, our implementation incorporates a novel method for dynamic load balancing. Our communication and load balancing enhancements provide increased efficiency and flexibility for our MD code. vet are general enough for use in other parallel algorithms.

  18. Peak mass and dynamical friction

    E-Print Network [OSTI]

    A. Del Popolo; M. Gambera

    1995-06-09

    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.

  19. Neutron diffraction measurements of dislocation density in copper crystals deformed at high strain rate

    SciTech Connect (OSTI)

    Rao, Mala N.; Chaplot, S. L.; Rawat, S.

    2013-02-05

    Neutron diffraction measurements of the rocking curves were carried out for single crystals of copper subjected to dynamic compression at 10{sup 3}/s strain rate. The line broadening is expected to be produced by dislocations, and an analysis of this broadening gives the dislocation density. Dislocation density is found to increase with increase of pressure.

  20. Constraining snowmelt in a temperature-index model using simulated snow densities

    E-Print Network [OSTI]

    Evans, Jason

    Constraining snowmelt in a temperature-index model using simulated snow densities Kathryn J. Georgakakos, Editor-in-Chief Keywords: Snow density Snow modelling Melt factor Degree-day factor Warm maritime snowpack dynamics Snow depth s u m m a r y Current snowmelt parameterisation schemes are largely untested

  1. MD Simulation for Head-on Collision of Liquid Nanodroplets Obeying Modified L-J Potential

    E-Print Network [OSTI]

    Bell, Alexander J

    2015-01-01

    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...

  2. Low density carbonized composite foams

    DOE Patents [OSTI]

    Kong, Fung-Ming (Pleasanton, CA)

    1991-01-01

    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.

  3. Neutralino relic density including coannihilations

    E-Print Network [OSTI]

    Paolo Gondolo; Joakim Edsjo

    1997-11-25

    We give an overview of our precise calculation of the relic density of the lightest neutralino, in which we included relativistic Boltzmann averaging, subthreshold and resonant annihilations, and coannihilation processes with charginos and neutralinos.

  4. Influence of density dependent symmetry energy on Elliptical flow

    E-Print Network [OSTI]

    Karan Singh Vinayak; Suneel Kumar

    2011-09-18

    The effect of density dependent symmetry energy on elliptical flow is studied using isospin-dependent quantum molecular dynamics model(IQMD). We have used the reduced isospin- dependent cross-section with hard(H) equation of state to study the sensitivity of elliptical flow towards symmetry energy in the energy range of 50 - 1000 MeV/nucleon. The elliptical flow becomes zero at a particular energy termed as transition energy. A systematic effort has been made to pin down the transition energy for the density dependent symmetry energy.

  5. Low density metal hydride foams

    DOE Patents [OSTI]

    Maienschein, Jon L. (Oakland, CA); Barry, Patrick E. (Pleasant Hill, CA)

    1991-01-01

    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.

  6. Maximum-likelihood density modification

    SciTech Connect (OSTI)

    Terwilliger, Thomas C., E-mail: terwilliger@lanl.gov [Structural Biology Group, Mail Stop M888, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2000-08-01

    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].

  7. Sandia Energy - Scattering Dynamics

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

    Scattering Dynamics Home Transportation Energy Predictive Simulation of Engines Combustion Chemistry Chemical Dynamics Scattering Dynamics Scattering DynamicsAshley...

  8. Hydrogen Donors in ZnO M.D. McCluskey, S.J. Jokela, and W.M. Hlaing Oo

    E-Print Network [OSTI]

    McCluskey, Matthew

    Hydrogen Donors in ZnO M.D. McCluskey, S.J. Jokela, and W.M. Hlaing Oo Department of Physics first-principles calculations and experimental studies have shown that hydrogen acts as a shallow donor in ZnO, in contrast to hydrogen's usual role as a passivating impurity. Given the omnipresence

  9. UCF COLLEGE OF MEDICINE M.D. EDUCATIONAL PROGRAM Please contact Molly Willis for use of, or corrections to this document.

    E-Print Network [OSTI]

    Wu, Shin-Tson

    UCF COLLEGE OF MEDICINE M.D. EDUCATIONAL PROGRAM Please contact Molly Willis for use of & Medical Humanities Patient SafetyMedical NutritionMedical InformaticsGender Based Medicine Geriatrics and Behavior (7 weeks) Int./Fam. Medicine Neurology March April Pediatrics June Focused Inquiry and Research

  10. Phonons and related crystal properties from density-functional perturbation theory

    E-Print Network [OSTI]

    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

  11. Function and dynamics of aptamers: A case study on the malachite green aptamer

    SciTech Connect (OSTI)

    Wang, Tianjiao

    2008-12-01

    Aptamers are short single-stranded nucleic acids that can bind to their targets with high specificity and high affinity. To study aptamer function and dynamics, the malachite green aptamer was chosen as a model. Malachite green (MG) bleaching, in which an OH- attacks the central carbon (C1) of MG, was inhibited in the presence of the malachite green aptamer (MGA). The inhibition of MG bleaching by MGA could be reversed by an antisense oligonucleotide (AS) complementary to the MGA binding pocket. Computational cavity analysis of the NMR structure of the MGA-MG complex predicted that the OH{sup -} is sterically excluded from the C1 of MG. The prediction was confirmed experimentally using variants of the MGA with changes in the MG binding pocket. This work shows that molecular reactivity can be reversibly regulated by an aptamer-AS pair based on steric hindrance. In addition to demonstrate that aptamers could control molecular reactivity, aptamer dynamics was studied with a strategy combining molecular dynamics (MD) simulation and experimental verification. MD simulation predicted that the MG binding pocket of the MGA is largely pre-organized and that binding of MG involves reorganization of the pocket and a simultaneous twisting of the MGA terminal stems around the pocket. MD simulation also provided a 3D-structure model of unoccupied MGA that has not yet been obtained by biophysical measurements. These predictions were consistent with biochemical and biophysical measurements of the MGA-MG interaction including RNase I footprinting, melting curves, thermodynamic and kinetic constants measurement. This work shows that MD simulation can be used to extend our understanding of the dynamics of aptamer-target interaction which is not evident from static 3D-structures. To conclude, I have developed a novel concept to control molecular reactivity by an aptamer based on steric protection and a strategy to study the dynamics of aptamer-target interaction by combining MD simulation and experimental verification. The former has potential application in controlling metabolic reactions and protein modifications by small reactants and the latter may serve as a general approach to study the dynamics of aptamer-target interaction for new insights into mechanisms of aptamer-target recognition.

  12. Symmetries in open quantum dynamics

    E-Print Network [OSTI]

    Thomas F. Jordan

    2014-08-20

    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.

  13. The ESO Nearby Abell Cluster Survey IX. The morphology-radius and morphology-density relations in rich galaxy clusters

    E-Print Network [OSTI]

    T. Thomas; P. Katgert

    2005-10-10

    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.

  14. Jacek Dobaczewski Density functional theory and energy

    E-Print Network [OSTI]

    Dobaczewski, Jacek

    Jacek Dobaczewski Density functional theory and energy density functionals in nuclear physics Jacek UNEDFCollaboration,http://unedf.org/ Universal Nuclear Energy Density FunctionalUniversal Nuclear Energy Density in Poland per voivodship Energy density functional 245 647 Price voivodship functional 654 763 295 580

  15. MD-Predicted Phase diagrams for Pattern Formation due to Ion Irradiation

    E-Print Network [OSTI]

    Scott A. Norris; Juha Samela; Laura Bukonte; Marie Backman; Djurabekova Flyura; Kai Nordlund; Charbel S. Madi; Michael P. Brenner; Michael J. Aziz

    2010-12-23

    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.

  16. Frontiers for Discovery in High Energy Density Physics

    SciTech Connect (OSTI)

    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.

    2004-07-20

    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

  17. Dynamics of capillary condensation in aerogels

    SciTech Connect (OSTI)

    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)

    2006-03-15

    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.

  18. Color Dynamics On Phase Space

    E-Print Network [OSTI]

    A. Bonasera

    2000-03-09

    We describe the properties of quark matter at zero temperature and finite baryon densities within microscopic Vlasov/molecular dynamics approaches. We use an inter-quark Richardson's potential consistent with the indications of Lattice QCD calculations. The color degrees of freedom are explicitly taken into account. We explicitly demonstrate that the Vlasov approach alone is insufficient in the hadronization region. In order to overcome this problem we prepare the initial condition for many events using molecular dynamics with frictional cooling and a Thomas-Fermi approximation to the Fermi motion. These events are averaged and propagated in time using the Vlasov approach. We find some evidence for a second order phase transition from nuclear to quark matter at high baryon densities. An order parameter suitable to describe the phase transition is discussed. At low densities the quark condensate into approximately color white clusters (nucleon).

  19. High-density fluid compositions

    SciTech Connect (OSTI)

    Sanders, D.C.

    1981-09-29

    Clear, high-density fluids suitable for use as well completion, packing, and perforation media comprise aqueous solutions of zinc bromide and calcium bromide having densities lying in the range of about 14.5 up to about 18.0 pounds per gallon and measured PH's lying in the range of about 3.5 up to about 6.0. Optionally, such fluids may also comprise calcium chloride and/or a soluble film-forming amine-based corrosion inhibitor. Such fluids under conditions of ordinary use exhibit low corrosion rates and have crystallization points lying well below the range of temperatures under which they are used.

  20. Density waves in the shearing sheet III. Disc heating

    E-Print Network [OSTI]

    B. Fuchs

    2001-04-25

    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.

  1. Spiral density wave generation by vortices in Keplerian flows

    E-Print Network [OSTI]

    G. Bodo; G. Chagelishvili; G. Murante; A. Tevzadze; P. Rossi; A. Ferrari

    2005-03-22

    We perform a detailed analytical and numerical study of the dynamics of perturbations (vortex/aperiodic mode, Rossby and spiral-density waves) in 2D compressible disks with a Keplerian law of rotation. We draw attention to the process of spiral-density wave generation from vortices, discussing, in particular, the initial, most peculiar stages of wave emission. We show that the linear phenomenon of wave generation by vortices in smooth (without inflection points) shear flows found by using the so-called non-modal approach, is directly applicable to the present case. After an analytical non-modal description of the physics and characteristics of the spiral-density wave generation/propagation in the local shearing-sheet model, we follow the process of wave generation by small amplitude coherent circular vortex structures, by direct global numerical simulation, describing the main features of the generated waves.

  2. Time Dependent Density Functional Theory An introduction

    E-Print Network [OSTI]

    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

  3. Statistical density modification using local pattern matching

    DOE Patents [OSTI]

    Terwilliger, Thomas C.

    2007-01-23

    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.

  4. The structure and IR signatures of the arginine-glutamate salt bridge. Insights from the classical MD simulations

    SciTech Connect (OSTI)

    Vener, M. V.; Odinokov, A. V.; Wehmeyer, C.; Sebastiani, D.

    2015-06-07

    Salt bridges and ionic interactions play an important role in protein stability, protein-protein interactions, and protein folding. Here, we provide the classical MD simulations of the structure and IR signatures of the arginine (Arg)–glutamate (Glu) salt bridge. The Arg-Glu model is based on the infinite polyalanine antiparallel two-stranded ?-sheet structure. The 1 ?s NPT simulations show that it preferably exists as a salt bridge (a contact ion pair). Bidentate (the end-on and side-on structures) and monodentate (the backside structure) configurations are localized [Donald et al., Proteins 79, 898–915 (2011)]. These structures are stabilized by the short {sup +}N–H?O{sup ?} bonds. Their relative stability depends on a force field used in the MD simulations. The side-on structure is the most stable in terms of the OPLS-AA force field. If AMBER ff99SB-ILDN is used, the backside structure is the most stable. Compared with experimental data, simulations using the OPLS all-atom (OPLS-AA) force field describe the stability of the salt bridge structures quite realistically. It decreases in the following order: side-on > end-on > backside. The most stable side-on structure lives several nanoseconds. The less stable backside structure exists a few tenth of a nanosecond. Several short-living species (solvent shared, completely separately solvated ionic groups ion pairs, etc.) are also localized. Their lifetime is a few tens of picoseconds or less. Conformational flexibility of amino acids forming the salt bridge is investigated. The spectral signature of the Arg-Glu salt bridge is the IR-intensive band around 2200 cm{sup ?1}. It is caused by the asymmetric stretching vibrations of the {sup +}N–H?O{sup ?} fragment. Result of the present paper suggests that infrared spectroscopy in the 2000–2800 frequency region may be a rapid and quantitative method for the study of salt bridges in peptides and ionic interactions between proteins. This region is usually not considered in spectroscopic studies of peptides and proteins.

  5. Communication: Quantum molecular dynamics simulation of liquid para-hydrogen by nuclear and electron wave packet approach

    SciTech Connect (OSTI)

    Hyeon-Deuk, Kim; Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 ; Ando, Koji

    2014-05-07

    Liquid para-hydrogen (p-H{sub 2}) is a typical quantum liquid which exhibits strong nuclear quantum effects (NQEs) and thus anomalous static and dynamic properties. We propose a real-time simulation method of wave packet (WP) molecular dynamics (MD) based on non-empirical intra- and inter-molecular interactions of non-spherical hydrogen molecules, and apply it to condensed-phase p-H{sub 2}. The NQEs, such as WP delocalization and zero-point energy, are taken into account without perturbative expansion of prepared model potential functions but with explicit interactions between nuclear and electron WPs. The developed MD simulation for 100 ps with 1200 hydrogen molecules is realized at feasible computational cost, by which basic experimental properties of p-H{sub 2} liquid such as radial distribution functions, self-diffusion coefficients, and shear viscosities are all well reproduced.

  6. About density functional theory interpretation

    E-Print Network [OSTI]

    Kirill Koshelev

    2015-05-28

    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.

  7. Longitudinal polarized parton densities updated

    SciTech Connect (OSTI)

    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)

    2006-02-01

    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.

  8. Functional Domain Motions in Proteins on the 1 100 ns Timescale: Comparison of Neutron Spin-Echo Spectroscopy of Phosphoglycerate Kinase with Molecular-Dynamics Simulation

    SciTech Connect (OSTI)

    Smolin, Nikolai [ORNL; Biehl, R [Southern Methodist University, Dallas; Kneller, Gerald [University of Orleans; Richter, Dieter O [ORNL; Smith, Jeremy C [ORNL

    2011-01-01

    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.

  9. Using Molecular Dynamics to quantify the electrical double layer and examine the potential for its direct observation in the in-situ TEM

    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.

    2015-03-25

    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

  10. A parallel algorithm for step- and chain-growth polymerization in Molecular Dynamics

    E-Print Network [OSTI]

    Pierre de Buyl; Erik Nies

    2015-03-03

    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.

  11. A molecular dynamics investigation of the unusual concentration dependencies of Fick diffusivities in silica mesopores

    SciTech Connect (OSTI)

    Krishna, Rajamani; van Baten, Jasper M

    2011-01-01

    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.

  12. Adhesion between elastic solids with randomly rough surfaces: comparison of analytical theory with molecular dynamics simulations

    E-Print Network [OSTI]

    N. Mulakaluri; B. N. J. Persson

    2011-12-22

    The adhesive contact between elastic solids with randomly rough, self affine fractal surfaces is studied by molecular dynamics (MD) simulations. The interfacial binding energy obtained from the simulations of nominally flat and curved surfaces is compared with the predictions of the contact mechanics theory by Persson. Theoretical and simulation results agree rather well, and most of the differences observed can be attributed to finite size effects and to the long-range nature of the interaction between the atoms in the block and the substrate in the MD model, as compared to the analytical theory which is for an infinite system with interfacial contact interaction. For curved surfaces (JKR-type of problem) the effective interfacial energy exhibit a weak hysteresis which may be due to the influence of local irreversible detachment processes in the vicinity of the opening crack tip during pull-off.

  13. Pion transverse charge density and the edge of hadrons

    SciTech Connect (OSTI)

    Carmignotto, Marco; Horn, Tanja; Miller, Gerald A.

    2014-08-01

    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.

  14. Relativistic Nuclear Energy Density Functionals: adjusting parameters to binding energies

    E-Print Network [OSTI]

    T. Niksic; D. Vretenar; P. Ring

    2008-09-08

    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.

  15. Density Functional Theory (DFT) Rob Parrish

    E-Print Network [OSTI]

    Sherrill, David

    · References 2 #12;Wavefunction Approach 3 Hydrogen 421 Wavefunction at Density Isosurface. Really hard to find Easy to do this Why? Because of Hermitian Operators: Kinetic Energy Density: #12;Density Functional Approach 4 Hydrogen 421 Density (Why is it grayscale?) A bit less obvious Probably easier to find

  16. Updated Axion CDM energy density

    E-Print Network [OSTI]

    Ji-Haeng Huh

    2008-10-08

    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.

  17. Density variations and anomalies in palladium compacts

    SciTech Connect (OSTI)

    Back, D.; Jones, T.; Ransick, M.; Walburg, T.; Werkmeister, D.

    1992-05-14

    Low-density compacts of palladium powder have relative densities of about 30{plus minus}10% TD. The variations in density are of concern for operations such as chemical/hydrogen pump systems because heat, mass, and momentum transport properties can be affected. Variations in density result from the inherent nature and interacting forces of UASA compaction of powder in cylinders. In addition to these expected variations, discontinuous density anomalies, such as cracks or high density ridges, are also found. An anomaly of particular concern was found to resemble a steer's head.'' it is a symmetrical region of low density located at or near the center of a compact. Typically, this region is surrounded by a band of high density, compacted palladium that sometimes exceeds the density of the surrounding compact matrix by a factor of three. This report examines these density variations and anomalies both theoretically and empirically.

  18. Density variations and anomalies in palladium compacts

    SciTech Connect (OSTI)

    Back, D.; Jones, T.; Ransick, M.; Walburg, T.; Werkmeister, D.

    1992-05-14

    Low-density compacts of palladium powder have relative densities of about 30{plus_minus}10% TD. The variations in density are of concern for operations such as chemical/hydrogen pump systems because heat, mass, and momentum transport properties can be affected. Variations in density result from the inherent nature and interacting forces of UASA compaction of powder in cylinders. In addition to these expected variations, discontinuous density anomalies, such as cracks or high density ridges, are also found. An anomaly of particular concern was found to resemble a ``steer`s head.`` it is a symmetrical region of low density located at or near the center of a compact. Typically, this region is surrounded by a band of high density, compacted palladium that sometimes exceeds the density of the surrounding compact matrix by a factor of three. This report examines these density variations and anomalies both theoretically and empirically.

  19. 2810 IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 39, NO. 11, NOVEMBER 2011 The Effect of Critical Plasma Densities of

    E-Print Network [OSTI]

    Harilal, S. S.

    in hydro- dynamic evolution of the produced plasma sources. Index Terms--CO2 laser, critical density and optimization of radiation sources for the next generation of nanolithography, i.e., the extreme ultravi- olet

  20. Probability distribution of the vacuum energy density

    SciTech Connect (OSTI)

    Duplancic, Goran; Stefancic, Hrvoje; Glavan, Drazen

    2010-12-15

    As the vacuum state of a quantum field is not an eigenstate of the Hamiltonian density, the vacuum energy density can be represented as a random variable. We present an analytical calculation of the probability distribution of the vacuum energy density for real and complex massless scalar fields in Minkowski space. The obtained probability distributions are broad and the vacuum expectation value of the Hamiltonian density is not fully representative of the vacuum energy density.

  1. Density functional theory of freezing: Analysis of crystal density

    E-Print Network [OSTI]

    Laird, Brian Bostian; McCoy, John D.; Haymet, A. D. J.

    1987-09-01

    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...

  2. Time-averaged quantum dynamics and the validity of the effective...

    Office of Scientific and Technical Information (OSTI)

    develop a technique for finding the dynamical evolution in time of an averaged density matrix. The result is an equation of evolution that includes an effective Hamiltonian, as...

  3. Reduction of VOC emissions from metal dip coating applications -- Canam Steel Corporation Point of Rocks, MD case study

    SciTech Connect (OSTI)

    Monfet, J.P.

    1997-12-31

    The reduction of VOC emissions from metal dip coating applications is not an environmental constraint, it is an economic opportunity. This case study shows how the industry can reap economic benefits from VOC reductions while improving air quality. The Canam Steel Corporation plant located in Point of Rocks, MD operates dip tanks for primer application on fabricated steel joists and joist girders. This process is presently subject to a regulation that limits the paint VOC content to 3.5 pounds per gallon of coating less water. As a result of the high paint viscosity associated with that regulation, the paint thickness of the dipped steel is thicker than the customers` specifications. Most of the VOC emissions can therefore be associated with the excess of paint applied to the products rather than to the required thickness of the coating. The higher paint usage rate has more than environmental consequences, it increases the cost of the applied coating. The project is to reduce the paint usage by controlling the viscosity of the coating in the tank. Experimental results as well as actual mass balance calculations show that using a higher VOC content paint would reduce the overall VOC emissions. The author explained the project to the Maryland Department of the Environment (MDE) Air and Radiation Management Administration. First, the MDE agreed to develop a new RACT determination for fabricated steel dipping operations. The new regulation would limit the amount of VOC than can be emitted to dip coat a ton of fabricated steel. Second, the MDE agreed to allow experimentation of the higher VOC content paint as a pilot project for the new regulation. This paper demonstrates the need for a RACT determination specific to fabricated steel dipping operations.

  4. On the Dynamical Origin of Bias in Clusters of Galaxies

    E-Print Network [OSTI]

    S. Colafrancesco; V. Antonuccio-Delogu; A. Del Popolo

    1994-10-29

    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.

  5. A Longitudinal Density Monitor for the LHC

    E-Print Network [OSTI]

    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...

  6. Structure And Dynamics of the Hydrated Palladium(II) Ion in Aqueous Solution a QMCF MD Simulation And EXAFS Spectroscopic Study

    SciTech Connect (OSTI)

    Hofer, T.S.; Randolf, B.R.; Shah, S.Adnan Ali; Rode, B.M.; Persson, I.

    2009-06-01

    The pharmacologically and industrially important palladium(II) ion is usually characterised as square-planar structure in aqueous solution, similar to the platinum(II) ion. Our investigations by means of the most modern experimental and theoretical methods give clear indications, however, that the hydrated palladium(II) ion is hexa-coordinated, with four ligands arranged in a plane at 2.0 {angstrom} plus two additional ligands in axial positions showing an elongated bond distance of 2.7-2.8 A. The second shell consists in average of 8.0 ligands at a mean distance of 4.4 {angstrom}. This structure provides a new basis for the interpretation of the kinetic properties of palladium(II) complexes.

  7. Rock Density | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION JEnvironmental Jump to:EA EIS Report UrlNM-bRenewable Energy|Gas and Electric JumpDensity Jump to:

  8. Accelerated molecular dynamics methods: introduction and recent developments

    SciTech Connect (OSTI)

    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

    2009-01-01

    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.

  9. 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...

  10. MD86.DOC

    E-Print Network [OSTI]

    05DE:C536610A _ LDS SI,[L0A61H] ;Load DS:reg with 32b pointr. 05E2:57 PUSH DI ; .... character is lost) to make room. .... value is correct, then change it here.

  11. Ten themes of viscous liquid dynamics

    E-Print Network [OSTI]

    Jeppe C. Dyre

    2006-12-06

    Ten "themes" of viscous liquid physics are discussed with a focus on how they point to a general description of equilibrium viscous liquid dynamics (i.e., fluctuations) at a given temperature. This description is based on standard time-dependent Ginzburg-Landau equations for the density fields, stress tensor fields, potential energy density field, and fields quantifying molecular orientations. One characteristic aspect of the theory is that density has the appearance of a non-conserved field. Another characteristic feature is long-wavelength dominance of the dynamics, which not only simplifies the theory by allowing for an ultra-local Hamiltonian (free energy), but also explains the observed general independence of chemistry. Whereas there are no long-ranged static (i.e., equal-time) correlations in the model, there are important long-ranged dynamic correlations on the alpha time scale.

  12. Adiabatic electronic flux density: a Born-Oppenheimer Broken Symmetry ansatz

    E-Print Network [OSTI]

    Vincent Pohl; Jean Christophe Tremblay

    2015-10-20

    The Born-Oppenheimer approximation leads to the counterintuitive result of a vanishing electronic flux density upon vibrational dynamics in the electronic ground state. To circumvent this long known issue, we propose using pairwise anti-symmetrically translated vibronic densities to generate a symmetric electronic density that can be forced to satisfy the continuity equation approximately. The so-called Born-Oppenheimer broken symmetry ansatz yields all components of the flux density simultaneously while requiring only knowledge about the nuclear quantum dynamics on the electronic adiabatic ground state potential energy surface. The underlying minimization procedure is transparent and computationally inexpensive, and the solution can be computed from the standard output of any quantum chemistry program. Taylor series expansion reveals that the implicit electron dynamics originates from non-adiabatic coupling to the explicit Born-Oppenheimer nuclear dynamics. The new approach is applied to the ${\\rm H}_2^+$ molecular ion vibrating in its ${}^2\\Sigma^+_g$ ground state. The electronic flux density is found to have the correct nodal structure and symmetry properties at all times.

  13. Assumptions that imply quantum dynamics is linear

    E-Print Network [OSTI]

    Thomas F. Jordan

    2006-01-26

    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.

  14. Ordering and Dynamics of Vibrated Hard Squares

    E-Print Network [OSTI]

    Lee Walsh; Narayanan Menon

    2015-10-02

    We study an experimental system of hard granular squares in two dimensions, energized by vibration. The interplay of order in the orientations and positions of anisotropic particles allows for a rich set of phases. We measure the structure and dynamics of steady states as a function of particle density. This allows us to identify a progression of phases in which a low density isotropic fluid gives way to a phase with tetratic orientational order, short-range translational correlations, and slowed rotational dynamics. In this range of density we also observe a coupling between the orientational order and bond-orientational order. At higher densities, the particles freeze into a translationally and orientationally ordered square crystalline phase in which translational diffusion is suppressed.

  15. Spin projection with double hybrid density functional theory

    SciTech Connect (OSTI)

    Thompson, Lee M.; Hratchian, Hrant P.

    2014-07-21

    A spin projected double-hybrid density functional theory is presented that accounts for different scaling of opposite and same spin terms in the second order correction. This method is applied to three dissociation reactions which in the unprojected formalism exhibit significant spin contamination with higher spin states. This gives rise to a distorted potential surface and can lead to poor geometries and energies. The projected method presented is shown to improve the description of the potential over unprojected double hybrid density functional theory. Comparison is made with the reference states of the two double hybrid functionals considered here (B2PLYP and mPW2PLYP) in which the projected potential surface is degraded by an imbalance in the description of dynamic and static correlation.

  16. Density waves in the shearing sheet I. Swing amplification

    E-Print Network [OSTI]

    B. Fuchs

    2001-03-02

    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.

  17. Dynamic Reconstruction

    E-Print Network [OSTI]

    Horn, Berthold Klaus Paul

    Dynamic reconstruction is a method for generating images or image sequences from data obtained using moving radiation detection systems. While coded apertures are used as examples of the underlying information collection ...

  18. DENSITY OF STATES CALCULATIONS FOR CARBON

    E-Print Network [OSTI]

    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

  19. Low density expansion for Lyapunov exponents

    E-Print Network [OSTI]

    Hermann Schulz-Baldes

    2006-07-12

    In some quasi-one-dimensional weakly disordered media, impurities are large and rare rather than small and dense. For an Anderson model with a low density of strong impurities, a perturbation theory in the impurity density is developed for the Lyapunov exponent and the density of states. The Lyapunov exponent grows linearly with the density. Anomalies of the Kappus-Wegner type appear for all rational quasi-momenta even in lowest order perturbation theory.

  20. Oxides having high energy densities

    DOE Patents [OSTI]

    Ceder, Gerbrand; Kang, Kisuk

    2013-09-10

    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.

  1. Low-Density Attack Revisited Tetsuya Izu

    E-Print Network [OSTI]

    International Association for Cryptologic Research (IACR)

    Low-Density Attack Revisited Tetsuya Izu Jun Kogure Takeshi Koshiba Takeshi Shimoyama Secure The low-density attack proposed by Lagarias and Odlyzko is a powerful algorithm against the subset sum, densities of the subset sum problems should be higher than 0.9408... in order to avoid the low

  2. Ultimate Energy Densities for Electromagnetic Pulses

    E-Print Network [OSTI]

    Mankei Tsang

    2008-03-06

    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.

  3. Electronic Structure, Phonon Dynamical Properties, and CO2 Capture...

    Office of Scientific and Technical Information (OSTI)

    Electronic Structure, Phonon Dynamical Properties, and CO2 Capture Capability of Na2-xMxZrO3 ( MLi ,K): Density-Functional Calculations and Experimental Validations Citation...

  4. Electronic Structure, Phonon Dynamical Properties, and CO2 Capture...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Electronic Structure, Phonon Dynamical Properties, and CO2 Capture Capability of Na2-xMxZrO3 ( MLi ,K): Density-Functional Calculations and Experimental...

  5. INTERMITTENCY OF SOLAR WIND DENSITY FLUCTUATIONS FROM ION TO ELECTRON SCALES

    SciTech Connect (OSTI)

    Chen, C. H. K.; Sorriso-Valvo, L.; Šafránková, J.; N?me?ek, Z.

    2014-07-01

    The intermittency of density fluctuations in the solar wind at kinetic scales has been examined using high time resolution Faraday cup measurements from the Spektr-R spacecraft. It was found that the probability density functions (PDFs) of the fluctuations are highly non-Gaussian over this range, but do not show large changes in shape with scale. These properties are statistically similar to those of the magnetic fluctuations and are important to understanding the dynamics of small scale turbulence in the solar wind. Possible explanations for the behavior of the density and magnetic fluctuations are discussed.

  6. Initial energy density and gluon distribution from the Glasma in heavy-ion collisions

    E-Print Network [OSTI]

    Hirotsugu Fujii; Kenji Fukushima; Yoshimasa Hidaka

    2008-11-04

    We estimate the energy density and the gluon distribution associated with the classical fields describing the early-time dynamics of the heavy-ion collisions. We first decompose the energy density into the momentum components exactly in the McLerran-Venugopalan model, with the use of the Wilson line correlators. Then we evolve the energy density with the free-field equation, which is justified by the dominance of the ultraviolet modes near the collision point. We also discuss the improvement with inclusion of nonlinear terms into the time evolution. Our numerical results at RHIC energy are fairly consistent with the empirical values.

  7. Molecular dynamics study of salt–solution interface: Solubility and surface charge of salt in water

    SciTech Connect (OSTI)

    Kobayashi, Kazuya; Liang, Yunfeng E-mail: matsuoka@earth.kumst.kyoto-u.ac.jp; Matsuoka, Toshifumi E-mail: matsuoka@earth.kumst.kyoto-u.ac.jp; Sakka, Tetsuo

    2014-04-14

    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.

  8. A molecular dynamics study of nuclear quantum effect on the diffusion of hydrogen in condensed phase

    SciTech Connect (OSTI)

    Nagashima, Hiroki; Tokumasu, Takashi; Tsuda, Shin-ichi; Tsuboi, Nobuyuki; Koshi, Mitsuo; Hayashie, A. Koichi

    2014-10-06

    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.

  9. Branch xylem density variations across the Amazon Basin

    E-Print Network [OSTI]

    2009-01-01

    increase wood density in Eucalyptus grandis seedlings? ,Changes in wood density of Eucalyptus camaldulensis due to

  10. Ratcheting of driven attracting colloidal particles: Temporal density oscillations and current multiplicity

    E-Print Network [OSTI]

    Andrey Pototsky; Andrew J. Archer; Sergey E. Savel'ev; Uwe Thiele; Fabio Marchesoni

    2011-03-15

    We consider the unidirectional particle transport in a suspension of colloidal particles which interact with each other via a pair potential having a hard-core repulsion plus an attractive tail. The colloids are confined within a long narrow channel and are driven along by a DC or an AC external potential. In addition, the walls of the channel interact with the particles via a ratchet-like periodic potential. We use dynamical density functional theory to compute the average particle current. In the case of DC drive, we show that as the attraction strength between the colloids is increased beyond a critical value, the stationary density distribution of the particles loses its stability leading to depinning and a time dependent density profile. Attraction induced symmetry breaking gives rise to the coexistence of stable stationary density profiles with different spatial periods and time-periodic density profiles, each characterized by different values for the particle current.

  11. Unequal density effect on static structure factor of coupled electron layers

    SciTech Connect (OSTI)

    Saini, L. K. Nayak, Mukesh G.

    2014-04-24

    In order to understand the ordered phase, if any, in a real coupled electron layers (CEL), there is a need to take into account the effect of unequal layer density. Such phase is confirmed by a strong peak in a static structure factor. With the aid of quantum/dynamical version of Singwi, Tosi, Land and Sjölander (so-called qSTLS) approximation, we have calculated the intra- and interlayer static structure factors, S{sub ll}(q) and S{sub 12}(q), over a wide range of density parameter r{sub sl} and interlayer spacing d. In our present study, the sharp peak in S{sub 22}(q) has been found at critical density with sufficiently lower interlayer spacing. Further, to find the resultant effect of unequal density on intra- and interlayer static structure factors, we have compared our results with that of the recent CEL system with equal layer density and isolated single electron layer.

  12. Statistical density modification using local pattern matching

    SciTech Connect (OSTI)

    Terwilliger, Thomas C., E-mail: terwilliger@lanl.gov [Mail Stop M888, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2003-10-01

    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.

  13. Aerodynamic Focusing Of High-Density Aerosols

    SciTech Connect (OSTI)

    Ruiz, D. E.; Fisch, Nathaniel

    2014-02-24

    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.

  14. Energy density bounds for black strings

    E-Print Network [OSTI]

    Shinya Tomizawa

    2005-06-07

    The conserved charge called Y-ADM mass density associated with asymptotically translational Killing-Yano tensor gives us an appropriate physical meaning about the energy density of $p$ brane spacetimes or black strings. We investigated the positivity of energy density in black string spacetimes, using the spinorial technique introduced by Witten. Recently, the positivity of Y-ADM mass density in p brane spacetimes was discussed. In this paper, we will extend this discussion to the transversely asymptotically flat black string spacetimes containing an apparent horizon. We will give the sufficient conditions for the Y-ADM mass density to become positive in such spacetimes.

  15. RUMD: A general purpose molecular dynamics package optimized to utilize GPU hardware down to a few thousand particles

    E-Print Network [OSTI]

    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

    2015-01-01

    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.

  16. Performance metrics in a hybrid MPI-OpenMP based molecular dynamics simulation with short-range interactions

    E-Print Network [OSTI]

    Pal, Anirban; Raha, Soumyendu; Bhattacharya, Baidurya

    2015-01-01

    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...

  17. Molecular dynamics simulation: a tool for exploration and discovery using simple models

    E-Print Network [OSTI]

    D. C. Rapaport

    2014-11-13

    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.

  18. iMu arrayS:The biOMechanicS Of baSeball piTching eric berKSOn Md, ryan aylWard MS, JaMeS zachazeWSKi dpT,aTc, JOSeph paradiSO phd,ThOMaS J. gill Md

    E-Print Network [OSTI]

    0 iMu arrayS:The biOMechanicS Of baSeball piTching eric berKSOn Md, ryan aylWard MS, JaMeS zachaze biomechanical studies have attempted to quan- tify the mechanics of throwing and to measure the forces sustained in the upper extremity during high-velocity pitching. Biomechanical testing of pitchers in its current state

  19. Enhanced molecular dynamics for simulating porous interphase layers in batteries.

    SciTech Connect (OSTI)

    Zimmerman, Jonathan A.; Wong, Bryan Matthew; Jones, Reese E.; Templeton, Jeremy Alan; Lee, Jonathan

    2009-10-01

    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.

  20. Constraining mantle density structure using geological evidence of surface uplift rates

    E-Print Network [OSTI]

    Ritsema, Jeroen

    Constraining mantle density structure using geological evidence of surface uplift rates: The case is actively being uplifted by a large-scale, positively buoyant structure within the mid-lower mantle. Using a new formulation in which dynamic topography and uplift rate are jointly used, we place constraints

  1. Potassium permeation through the KcsA channel: a density functional study

    E-Print Network [OSTI]

    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

  2. A Density Functional Theory Study of Hydrogen Adsorption in MOF-5 Tim Mueller and Gerbrand Ceder*

    E-Print Network [OSTI]

    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

  3. Decay to equilibrium of the filament end density along the leading edge of the lamellipodium

    E-Print Network [OSTI]

    Schmeiser, Christian

    Decay to equilibrium of the filament end density along the leading edge of the lamellipodium for the dynamics of actin filament ends along the leading edge of the lamellipodium is analyzed. It contains-dimensional meshwork of protein filaments, created by polymerization of actin [6]. In steadily protruding lamellipodia

  4. Spitzer Mid-Infrared Spectroscopy of HDF-oMD49: Reliable Identification of Compton-thick Quasars at z~2

    E-Print Network [OSTI]

    Alexander, D M; Pope, A; Bauer, F E; Brandt, W N; Daddi, E; Dickinson, M; Elbaz, D; Reddy, N A

    2008-01-01

    Many models that seek to explain the origin of the unresolved X-ray background predict that Compton-thick Active Galactic Nuclei (AGNs) are ubiquitious at high redshift. However, few distant Compton-thick AGNs have been reliably identified to date. Here we present Spitzer-IRS spectroscopy and 3.6-70um photometry of a z=2.2 optically identified AGN (HDF-oMD49) that is formally undetected in the 2Ms Chandra Deep Field-North (CDF-N) survey. The Spitzer-IRS spectrum and spectral energy distribution of this object is AGN dominated, and a comparison of the energetics at X-ray wavelengths to those derived from mid-infrared (mid-IR) and optical spectroscopy shows that the AGN is intrinsically luminous (L_X~3x10^44 erg/s) but heavily absorbed by Compton-thick material (N_H>>10^24 cm^{-2}); i.e., this object is a Compton-thick quasar. Adopting the same approach that we applied to HDF-oMD49, we searched the literature and found a further six objects at z~2-2.5 that are also X-ray weak/undetected but have evidence for AG...

  5. Why quantum dynamics is linear

    E-Print Network [OSTI]

    Thomas F. Jordan

    2007-02-16

    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.

  6. The Quantum Energy Density: Improved E

    SciTech Connect (OSTI)

    Krogel, Jaron; Yu, Min; Kim, Jeongnim; Ceperley, David M.

    2013-01-01

    We establish a physically meaningful representation of a quantum energy density for use in Quantum Monte Carlo calculations. The energy density operator, dened in terms of Hamiltonian components and density operators, returns the correct Hamiltonian when integrated over a volume containing a cluster of particles. This property is demonstrated for a helium-neon \\gas," showing that atomic energies obtained from the energy density correspond to eigenvalues of isolated systems. The formation energies of defects or interfaces are typically calculated as total energy dierences. Using a model of delta-doped silicon (where dopant atoms form a thin plane) we show how interfacial energies can be calculated more eciently with the energy density, since the region of interest is small. We also demonstrate how the energy density correctly transitions to the bulk limit away from the interface where the correct energy is obtainable from a separate total energy calculation.

  7. Dislocation dynamics: from microscopic models to macroscopic crystal plasticity

    E-Print Network [OSTI]

    Hajj, A El; Monneau, R

    2009-01-01

    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.

  8. Sheath dynamics induced by ion-acoustic rarefaction wave

    SciTech Connect (OSTI)

    Murakami, M. ); Nishihara, K. )

    1993-09-01

    A simple analytical model is presented to describe the sheath dynamics, when a stationary slab plasma with a uniform density [ital n][sub 0] faces a negatively biased wall with a voltage [phi][sub 0]. The dynamics strongly depends on the sheath thickness [ital s]. If [ital s] is less than a well-defined distance [ital s][sub [ital e

  9. Considering Air Density in Wind Power Production

    E-Print Network [OSTI]

    Zénó Farkas

    2011-03-11

    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.

  10. Method of synthesizing a low density material

    DOE Patents [OSTI]

    Lorensen, L.E.; Monaco, S.B.

    1987-02-27

    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.

  11. Considering Air Density in Wind Power Production

    E-Print Network [OSTI]

    Farkas, Zénó

    2011-01-01

    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.

  12. Vortex dynamics in 4 Banavara N. Shashikanth

    E-Print Network [OSTI]

    Shashikanth, Banavara N.

    of oblique vortex shedding behind a heated circular cylinder in laminar wake regime Phys. Fluids 24, 011701 dynamics of Euler's equations for a constant density fluid flow in R4 is studied. Most of the paper focuses of such work are in Refs. 31, 24, 12, 14, and 11. It is fair to say that, in general, classical fluid flows

  13. 3-D capacitance density imaging system

    DOE Patents [OSTI]

    Fasching, G.E.

    1988-03-18

    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.

  14. Mini-review of Electron Density Visualization

    SciTech Connect (OSTI)

    Adler, Joan; Adler, Omri; Kreif, Meytal; Cohen, Or; Grosso, Bastien; Hashibon, Adham; Cooper, Valentino R

    2015-01-01

    We describe both educational and research oriented examples of electronic density visualization with AViz. Several detailed cases are presented and the procedures for their preparation are described.

  15. 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 Title: Uncertainty Quantification...

  16. 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...

  17. Building a Universal Nuclear Energy Density Functional

    SciTech Connect (OSTI)

    Bertulani, Carlos A.

    2014-09-10

    This grant had two components: Density functional theory and pairing and Nuclear reactions. This final report summarizes the activities for this SciDAC-2 project.

  18. Dynamical equilibration in strongly-interacting parton-hadron matter

    E-Print Network [OSTI]

    Vitalii Ozvenchuk; Elena Bratkovskaya; Olena Linnyk; Mark Gorenstein; Wolfgang Cassing

    2010-12-31

    We study the kinetic and chemical equilibration in 'infinite' parton-hadron matter within the Parton-Hadron-String Dynamics transport approach, which is based on a dynamical quasiparticle model for partons matched to reproduce lattice-QCD results - including the partonic equation of state - in thermodynamic equilibrium. The 'infinite' matter is simulated within a cubic box with periodic boundary conditions initialized at different baryon density (or chemical potential) and energy density. The transition from initially pure partonic matter to hadronic degrees of freedom (or vice versa) occurs dynamically by interactions. Different thermodynamical distributions of the strongly-interacting quark-gluon plasma (sQGP) are addressed and discussed.

  19. Effective run-and-tumble dynamics of bacteria baths

    E-Print Network [OSTI]

    M. Paoluzzi; R. Di Leonardo; L. Angelani

    2013-07-30

    {\\it E. coli} bacteria swim in straight runs interrupted by sudden reorientation events called tumbles. The resulting random walks give rise to density fluctuations that can be derived analytically in the limit of non interacting particles or equivalently of very low concentrations. However, in situations of practical interest, the concentration of bacteria is always large enough to make interactions an important factor. Using molecular dynamics simulations, we study the dynamic structure factor of a model bacterial bath for increasing values of densities. We show that it is possible to reproduce the dynamics of density fluctuations in the system using a free run-and-tumble model with effective fitting parameters. We discuss the dependence of these parameters, e.g., the tumbling rate, tumbling time and self-propulsion velocity, on the density of the bath.

  20. Time Dependent Density Functional Theory An Introduction

    E-Print Network [OSTI]

    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

  1. Enhancing critical current density of cuprate superconductors

    DOE Patents [OSTI]

    Chaudhari, Praveen

    2015-06-16

    The present invention concerns the enhancement of critical current densities in cuprate superconductors. Such enhancement of critical current densities include using wave function symmetry and restricting movement of Abrikosov (A) vortices, Josephson (J) vortices, or Abrikosov-Josephson (A-J) vortices by using the half integer vortices associated with d-wave symmetry present in the grain boundary.

  2. Neutral depletion and the helicon density limit

    SciTech Connect (OSTI)

    Magee, R. M.; Galante, M. E.; Carr, J. Jr.; Lusk, G.; McCarren, D. W.; Scime, E. E.

    2013-12-15

    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.

  3. Density functional theory for carbon dioxide crystal

    SciTech Connect (OSTI)

    Chang, Yiwen; Mi, Jianguo Zhong, Chongli

    2014-05-28

    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.

  4. Dependence of polar hole density on magnetic and solar conditions

    SciTech Connect (OSTI)

    Hoegy, W.R.; Grebowsky, J.M. (NASA Goddard Space Flight Center, Greenbelt, MD (USA))

    1991-04-01

    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.

  5. Density waves in the shearing sheet IV. Interaction with a live dark halo

    E-Print Network [OSTI]

    B. Fuchs

    2004-03-01

    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.

  6. Hierarchical Dynamic Models

    E-Print Network [OSTI]

    Penny, Will

    Hierarchical Dynamic Models Will Penny OU Processes Embedding OU(2) process Dynamic Models Hierarchical Dynamic Models Will Penny 26th May 2011 #12;Hierarchical Dynamic Models Will Penny OU Processes Dynamic Models Will Penny OU Processes Embedding OU(2) process Dynamic Models Generalised coordinates

  7. Ions in solution: Density corrected density functional theory (DC-DFT)

    SciTech Connect (OSTI)

    Kim, Min-Cheol; Sim, Eunji; Burke, Kieron

    2014-05-14

    Standard density functional approximations often give questionable results for odd-electron radical complexes, with the error typically attributed to self-interaction. In density corrected density functional theory (DC-DFT), certain classes of density functional theory calculations are significantly improved by using densities more accurate than the self-consistent densities. We discuss how to identify such cases, and how DC-DFT applies more generally. To illustrate, we calculate potential energy surfaces of HO·Cl{sup ?} and HO·H{sub 2}O complexes using various common approximate functionals, with and without this density correction. Commonly used approximations yield wrongly shaped surfaces and/or incorrect minima when calculated self consistently, while yielding almost identical shapes and minima when density corrected. This improvement is retained even in the presence of implicit solvent.

  8. Black Holes and Nuclear Dynamics

    E-Print Network [OSTI]

    David Merritt

    2006-02-17

    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.

  9. Nuclear Dynamics at the Balance Energy

    E-Print Network [OSTI]

    Aman D. Sood; Rajeev K. Puri

    2003-11-05

    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.

  10. Periodic subsystem density-functional theory

    SciTech Connect (OSTI)

    Genova, Alessandro; Pavanello, Michele; Ceresoli, Davide

    2014-11-07

    By partitioning the electron density into subsystem contributions, the Frozen Density Embedding (FDE) formulation of subsystem Density Functional Theory (DFT) has recently emerged as a powerful tool for reducing the computational scaling of Kohn–Sham DFT. To date, however, FDE has been employed to molecular systems only. Periodic systems, such as metals, semiconductors, and other crystalline solids have been outside the applicability of FDE, mostly because of the lack of a periodic FDE implementation. To fill this gap, in this work we aim at extending FDE to treat subsystems of molecular and periodic character. This goal is achieved by a dual approach. On one side, the development of a theoretical framework for periodic subsystem DFT. On the other, the realization of the method into a parallel computer code. We find that periodic FDE is capable of reproducing total electron densities and (to a lesser extent) also interaction energies of molecular systems weakly interacting with metallic surfaces. In the pilot calculations considered, we find that FDE fails in those cases where there is appreciable density overlap between the subsystems. Conversely, we find FDE to be in semiquantitative agreement with Kohn–Sham DFT when the inter-subsystem density overlap is low. We also conclude that to make FDE a suitable method for describing molecular adsorption at surfaces, kinetic energy density functionals that go beyond the GGA level must be employed.

  11. Low density, resorcinol-formaldehyde aerogels

    DOE Patents [OSTI]

    Pekala, R.W.

    1989-10-10

    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.

  12. Low density, resorcinol-formaldehyde aerogels

    DOE Patents [OSTI]

    Pekala, R.W.

    1988-05-26

    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.

  13. Low density, resorcinol-formaldehyde aerogels

    DOE Patents [OSTI]

    Pekala, Richard W. (Pleasant Hill, CA)

    1989-01-01

    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.

  14. Low density, resorcinol-formaldehyde aerogels

    DOE Patents [OSTI]

    Pekala, Richard W. (Pleasant Hill, CA)

    1991-01-01

    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.

  15. On the correlation between the photoexcitation pathways and the critical energies required for ablation of poly(methyl methacrylate): A molecular dynamics study

    SciTech Connect (OSTI)

    Conforti, Patrick F.; Prasad, Manish; Garrison, Barbara J.

    2008-05-15

    The energetics initiating ablation in poly(methyl methacrylate) (PMMA) are studied using molecular dynamics (MD) simulation. The critical energy to initiate ablation in PMMA following the absorption of photons is investigated for two penetration depths along a range of fluences using a coarse-grained, hybrid Monte Carlo-MD scheme. Both heating and direct bond scission are simulated separately after photon absorption with additional transformation of material occurring via chemical reactions following the photochemical bond cleavage. For a given type of absorption and reaction channel, a critical energy can well describe the amount of energy required to initiate ablation. The simulations show a decrease in the critical energy when a greater amount of photochemistry is introduced in the system. The simulations complement experimental studies and elucidate how enhanced photochemistry lowers ablation thresholds in polymer substrates.

  16. Density Matrix in Quantum Mechanics and Distinctness of Ensembles Having the Same Compressed Density Matrix

    E-Print Network [OSTI]

    Gui Lu Long; Yi-Fan Zhou; Jia-Qi Jin; Yang Sun; Hai-Woong Lee

    2006-04-20

    We clarify different definitions of the density matrix by proposing the use of different names, the full density matrix for a single-closed quantum system, the compressed density matrix for the averaged single molecule state from an ensemble of molecules, and the reduced density matrix for a part of an entangled quantum system, respectively. We show that ensembles with the same compressed density matrix can be physically distinguished by observing fluctuations of various observables. This is in contrast to a general belief that ensembles with the same compressed density matrix are identical. Explicit expression for the fluctuation of an observable in a specified ensemble is given. We have discussed the nature of nuclear magnetic resonance quantum computing. We show that the conclusion that there is no quantum entanglement in the current nuclear magnetic resonance quantum computing experiment is based on the unjustified belief that ensembles having the same compressed density matrix are identical physically. Related issues in quantum communication are also discussed.

  17. M.D. Lemmon, Xiaojun Yang and P. J. Antsaklis, "Inductive Inference of Logical DES Controllers using the L* Algorithm," Technical Report of the ISIS (Interdisciplinary Studies of Intelligent Systems)

    E-Print Network [OSTI]

    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

  18. REU: Interdisciplinary Program in High Performance Computing at UMBC http://www.umbc.edu/hpcreu Department of Mathematics and Statistics University of Maryland, Baltimore County 1000 Hilltop Circle, Baltimore, MD 21250 410-455-2412

    E-Print Network [OSTI]

    Suri, Manil

    ://www.umbc.edu/hpcreu © Department of Mathematics and Statistics · University of Maryland, Baltimore County · 1000 Hilltop Circle, Baltimore, MD 21250 · 410-455-2412 UMBC is an Equal Opportunity and Affirmative Action Institution Interdisciplinary Program in High Performance Computing University of Maryland, Baltimore County (UMBC) Summer 2010

  19. Reduce Building Energy Consumption by Improving the Supply Air Temperature Schedule and Recommissioning the Terminal Boxes, Submitted to the Energy Management and Operations Division at the M.D. Anderson Cancer Center 

    E-Print Network [OSTI]

    Liu, M.; Athar, A.; Zhu, Y.; Claridge, D. E.

    1995-01-01

    At the request of the Energy Management and Operations Department at M.D. Anderson Cancer Center, the Energy Systems Laboratory of Texas A&M University performed a study of optimizing the HVAC operation at its Basic Research Building. The Basic...

  20. Fatal self-poisoning with lithium carbonate M.R. Achong, b sc, mb; P.G. Fernandez, mrcp, frcp[c]; P.J. McLeod, md, frcp[c

    E-Print Network [OSTI]

    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

  1. Cindy W. Christian, MD holds The Children's Hospital of Philadelphia endowed Chair in the Prevention of Child Abuse and Neglect, is a Professor of Pediatrics at the Perelman School of Medicine at The University of

    E-Print Network [OSTI]

    Bushman, Frederic

    Cindy W. Christian, MD holds The Children's Hospital of Philadelphia endowed Chair was appointed as the rst medical director for the Philadelphia Department of Human Services, leading the development of policies and strategies to improve the health of Philadelphia's dependent children. Dr

  2. One Physics Ellipse College Park, MD 20740-3844 USA www.aps.org Direct inquiries to Jennifer Ruberto: 301-209-3275 Fax: 301-209-0867 Email: ruberto@aps.org

    E-Print Network [OSTI]

    Nahar, Sultana Nurun

    One Physics Ellipse · College Park, MD 20740-3844 USA · 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

  3. Galaxy rotation curves with log-normal density distribution

    E-Print Network [OSTI]

    Marr, John H

    2015-01-01

    The log-normal distribution represents the probability of finding randomly distributed particles in a micro canonical ensemble with high entropy. To a first approximation, a modified form of this distribution with a truncated termination may represent an isolated galactic disk, and this disk density distribution model was therefore run to give the best fit to the observational rotation curves for 37 representative galaxies. The resultant curves closely matched the observational data for a wide range of velocity profiles and galaxy types with rising, flat or descending curves in agreement with Verheijen's classification of 'R', 'F' and 'D' type curves, and the corresponding theoretical total disk masses could be fitted to a baryonic Tully Fisher relation (bTFR). Nine of the galaxies were matched to galaxies with previously published masses, suggesting a mean excess dynamic disk mass of dex0.61+/-0.26 over the baryonic masses. Although questionable with regard to other measurements of the shape of disk galaxy g...

  4. Turbulent density fluctuations in the solar wind

    E-Print Network [OSTI]

    Ingale, Madhusudan

    2015-01-01

    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...

  5. Spin- and Pair-Density-Wave Glasses

    E-Print Network [OSTI]

    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 ...

  6. LANDAU'S NECESSARY DENSITY CONDITIONS FOR LCA GROUPS

    E-Print Network [OSTI]

    Kutyniok, Gitta

    LANDAU'S NECESSARY DENSITY CONDITIONS FOR LCA GROUPS KARLHEINZ GR¨OCHENIG, GITTA KUTYNIOK's conditions to the setting of locally compact abelian (LCA) groups, relying in an analogous way on the basics

  7. Density controlled carbon nanotube array electrodes

    DOE Patents [OSTI]

    Ren, Zhifeng F. (Newton, MA); Tu, Yi (Belmont, MA)

    2008-12-16

    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.

  8. Shock compression of low-density foams

    SciTech Connect (OSTI)

    Holmes, N.C.

    1993-07-01

    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.

  9. Magnetic fields and density functional theory

    SciTech Connect (OSTI)

    Salsbury Jr., Freddie

    1999-02-01

    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.

  10. 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...

  11. Alpha track density using a semiconductor detector 

    E-Print Network [OSTI]

    Hamilton, Ian Scott

    1993-01-01

    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...

  12. Primordial Density Fluctuations in Phase Coupling Gravity

    E-Print Network [OSTI]

    C. E. M. Batista; M. Schiffer

    1996-01-10

    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.

  13. Density shock waves in confined microswimmers

    E-Print Network [OSTI]

    Tsang, Alan Cheng Hou

    2015-01-01

    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...

  14. Density of states of disordered systems 

    E-Print Network [OSTI]

    van Rossum, Mark; Nieuwenhuizen, Th.M; Hofstetter, E; Schreiber, M

    1994-05-15

    Density of states calculations for the tight-binding model with diagonal disorder are presented. An instanton approach is used to calculate the tails of the spectrum, including all prefactors. It is shown that a Hartree ...

  15. Densities of Minor-Closed Graph Families

    E-Print Network [OSTI]

    Eppstein, David

    2010-01-01

    N. Robertson and P. D. Seymour. Graph Minors. XX. Wagner’sChudnovsky, B. Reed, and P. Seymour. The edge-density for KReferences [1] N. Alon, P. Seymour, and R. Thomas. A

  16. Spacetime Average Density (SAD) cosmological measures

    SciTech Connect (OSTI)

    Page, Don N.

    2014-11-01

    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.

  17. Kinetics and thermodynamics of electron transfer in Debye solvents: An analytical and nonperturbative reduced density matrix theory

    E-Print Network [OSTI]

    Ping Han; Rui-Xue Xu; Baiqing Li; Jian Xu; Ping Cui; Yan Mo; YiJing Yan

    2006-04-11

    A nonperturbative electron transfer rate theory is developed based on the reduced density matrix dynamics, which can be evaluated readily for the Debye solvent model without further approximation. Not only does it recover for reaction rates the celebrated Marcus' inversion and Kramers' turnover behaviors, the present theory also predicts for reaction thermodynamics, such as equilibrium Gibbs free-energy and entropy, some interesting solvent-dependent features that are calling for experimental verification. Moreover, a continued fraction Green's function formalism is also constructed, which can be used together with Dyson equation technique, for efficient evaluation of nonperturbative reduced density matrix dynamics.

  18. General relation between density of states and dwell times in mesoscopic systems

    SciTech Connect (OSTI)

    Iannaccone, G. Dipartimento di Ingegneria dell'Informazione: Elettronica, Informatica e Telecomunicazioni, Universita degli Studi di Pisa, Via Diotisalvi 2, I-56126 Pisa )

    1995-02-15

    A relevant relation between the dwell time and the density of states for a three-dimensional system of arbitrary shape with an arbitrary number of incoming channels is derived. This result extends the one obtained by Gasparian and co-workers for the case of a one-dimensional symmetrical potential barrier. We believe that such a strong relation is rich in physical significance because the dwell time is the most widely accepted time measure of a particle's dynamics and the density of states in a given region is one of the most relevant properties of a system in equilibrium.

  19. Ligand identification using electron-density mapcorrelations

    SciTech Connect (OSTI)

    Terwilliger, Thomas C.; Adams, Paul D.; Moriarty, Nigel W.; Cohn,Judith D.

    2006-12-01

    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.

  20. Force Density Balance inside the Hydrogen Atom

    E-Print Network [OSTI]

    Himpsel, F J

    2015-01-01

    Motivated by the long-debated question about the internal stability of the electron, the force densities acting on the charge density of the 1s electron in the H atom are investigated. The problem is mapped onto the canonical formalism for a classical Dirac field coupled to the electric field of an external point charge. An explicit calculation shows that the attractive Coulomb force density is balanced exactly at every point in space by the repulsive confinement force density. The latter requires evaluating the divergence of the stress tensor for the 1s solution of the Dirac equation. Such a local force balance goes beyond the global stability criteria that are usually given for the H atom. This concept is extended to the internal stability of any charged particle by investigating the force densities acting on its surrounding vacuum polarization. At large distances one has to consider only the charge density of virtual electrons and positrons, induced by a point charge in the vacuum of quantum electrodynamic...

  1. Dynamical Bounds for Sturmian Schrödinger Operators

    E-Print Network [OSTI]

    L. Marin

    2009-06-10

    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.

  2. Microscopic Description of Nuclear Fission Dynamics

    E-Print Network [OSTI]

    A. S. Umar; V. E. Oberacker; J. A. Maruhn; P. -G. Reinhard

    2010-03-22

    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.

  3. Dynamics of dendritic polymers in the bulk and under confinement

    SciTech Connect (OSTI)

    Chrissopoulou, K.; Fotiadou, S.; Androulaki, K.; Anastasiadis, S. H.; Tanis, I.; Karatasos, K.; Prevosto, D.; Labardi, M.; Frick, B.

    2014-05-15

    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.

  4. Sandia Energy - Chemical Dynamics

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

    Chemical Dynamics Home Transportation Energy Predictive Simulation of Engines Combustion Chemistry Chemical Dynamics Chemical DynamicsAshley Otero2015-10-28T02:45:37+00:00...

  5. The response of plasma density to breaking inertial gravity wave in the lower regions of ionosphere

    SciTech Connect (OSTI)

    Tang, Wenbo Mahalov, Alex

    2014-04-15

    We present a three-dimensional numerical study for the E and lower F region ionosphere coupled with the neutral atmosphere dynamics. This model is developed based on a previous ionospheric model that examines the transport patterns of plasma density given a prescribed neutral atmospheric flow. Inclusion of neutral dynamics in the model allows us to examine the charge-neutral interactions over the full evolution cycle of an inertial gravity wave when the background flow spins up from rest, saturates and eventually breaks. Using Lagrangian analyses, we show the mixing patterns of the ionospheric responses and the formation of ionospheric layers. The corresponding plasma density in this flow develops complex wave structures and small-scale patches during the gravity wave breaking event.

  6. Probability density adjoint for sensitivity analysis of the Mean of Chaos

    SciTech Connect (OSTI)

    Blonigan, Patrick J., E-mail: blonigan@mit.edu; Wang, Qiqi, E-mail: qiqi@mit.edu

    2014-08-01

    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.

  7. Energy Density Fluctuations in Inflationary Cosmology

    E-Print Network [OSTI]

    Harald F. Muller; Christoph Schmid

    1994-12-07

    We analyze the energy density fluctuations contributed by scalar fields $\\Phi$ with vanishing expectation values, $\\langle\\Phi\\rangle=0$, which are present in addition to the inflaton field. For simplicity we take $\\Phi$ to be non--interacting and minimally coupled to gravity. We use normal ordering to define the renormalized energy density operator $\\rho$, and we show that any normal ordering gives the same result for correlation functions of $\\rho$. We first consider massless fields and derive the energy fluctuations in a single mode $\\vk$, the two--point correlation function of the energy density, the power spectrum, and the variance of the smeared energy density, $\\ddR$. Mass effects are investigated for energy fluctuations in single modes. All quantities considered are scale invariant at the second horizon crossing (Harrison--Zel'dovich type) for massless and for unstable massive fields. The magnitude of the relative fluctuations $\\de\\rho/\\rt$ is of order $(\\Hi/\\Mp)^2$ in the massless case, where $\\Hi$ is the Hubble constant during inflation. For an unstable field of mass $m_\\Phi\\ll\\Hi$ with a decay rate $\\Gamma_\\Phi$ the magnitude is enhanced by a factor $\\sqrt{m_\\Phi/\\Gamma_\\Phi}$. Finally, the prediction for the cosmic variance of the average energy density in a sample is given in the massless case.

  8. Fast magnetic reconnection in low-density electron-positron plasmas

    SciTech Connect (OSTI)

    Bessho, Naoki; Bhattacharjee, A.

    2010-10-15

    Two-dimensional particle-in-cell simulations have been performed to study magnetic reconnection in low-density electron-positron plasmas without a guide magnetic field. Impulsive reconnection rates become of the order of unity when the background density is much smaller than 10% of the density in the initial current layer. It is demonstrated that the outflow speed is less than the upstream Alfven speed, and that the time derivative of the density must be taken into account in the definition of the reconnection rate. The reconnection electric fields in the low-density regime become much larger than the ones in the high-density regime, and it is possible to accelerate the particles to high energies more efficiently. The inertial term in the generalized Ohm's law is the most dominant term that supports a large reconnection electric field. An effective collisionless resistivity is produced and tracks the extension of the diffusion region in the late stage of the reconnection dynamics, and significant broadening of the diffusion region is observed. Because of the broadening of the diffusion region, no secondary islands, which have been considered to play a role to limit the diffusion region, are generated during the extension of the diffusion region in the outflow direction.

  9. Fabrication of low density ceramic material

    DOE Patents [OSTI]

    Meek, T.T.; Blake, R.D.; Sheinberg, H.

    1985-01-01

    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.

  10. Statistical approach to nuclear level density

    SciTech Connect (OSTI)

    Sen'kov, R. A.; Horoi, M.; Zelevinsky, V. G.

    2014-10-15

    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.

  11. High power density solid oxide fuel cells

    DOE Patents [OSTI]

    Pham, Ai Quoc; Glass, Robert S.

    2004-10-12

    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.

  12. Strongly Interacting Matter at High Energy Density

    E-Print Network [OSTI]

    Larry McLerran

    2008-12-08

    This lecture concerns the properties of strongly interacting matter (which is described by Quantum Chromodynamics) at very high energy density. I review the properties of matter at high temperature, discussing the deconfinement phase transition . At high baryon density and low temperature, large $N_c$ arguments are developed which suggest that high baryonic density matter is a third form of matter, Quarkyonic Matter, that is distinct from confined hadronic matter and deconfined matter. I finally discuss the Color Glass Condensate which controls the high energy limit of QCD, and forms the low x part of a hadron wavefunction. The Glasma is introduced as matter formed by the Color Glass Condensate which eventually thermalizes into a Quark Gluon Plasma.

  13. Density functional theory study of (OCS)2^-

    E-Print Network [OSTI]

    Bilalbegovic, G

    2007-01-01

    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.

  14. Low density, microcellular foams, preparation, and articles

    DOE Patents [OSTI]

    Young, Ainslie T. (Los Alamos, NM); Marsters, Robert G. (Jemez Springs, NM); Moreno, Dawn K. (Espanola, NM)

    1984-01-01

    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.

  15. Low density, microcellular foams, preparation, and articles

    DOE Patents [OSTI]

    Young, A.T.

    1982-03-03

    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.

  16. Dark Energy Density in Brane World

    E-Print Network [OSTI]

    Hai-Bao Wen; Xin-Bing Huang

    2005-02-08

    We present a possible explanation to the tiny positive cosmological constant under the frame of AdS$_5$ spacetime embedded by a dS$_4$ brane. We calculate the dark energy density by summing the zero point energy of massive scalar fields in AdS$_5$ spacetime. Under the assumption that the radius of AdS$_5$ spacetime is of the same magnitude as the radius of observable universe, the dark energy density in dS$_4$ brane is obtained, which is smaller than the observational value. The reasons are also discussed.

  17. Configuration Interactions Constrained by Energy Density Functionals

    E-Print Network [OSTI]

    B. Alex Brown; Angelo Signoracci; Morten Hjorth-Jensen

    2010-09-24

    A new method for constructing a Hamiltonian for configuration interaction calculations with constraints to energies of spherical configurations obtained with energy-density-functional (EDF) methods is presented. This results in a unified model that reproduced the EDF binding-energy in the limit of single-Slater determinants, but can also be used for obtaining energy spectra and correlation energies with renormalized nucleon-nucleon interactions. The three-body and/or density-dependent terms that are necessary for good nuclear saturation properties are contained in the EDF. Applications to binding energies and spectra of nuclei in the region above 208Pb are given.

  18. Stochastic thermodynamics of fluctuating density fields: Non-equilibrium free energy differences under coarse-graining

    SciTech Connect (OSTI)

    Leonard, T.; Lander, B.; Seifert, U.; Speck, T.

    2013-11-28

    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.

  19. On the Determination of the Mean Cosmic Matter Density and the Amplitude of Density Fluctuations

    E-Print Network [OSTI]

    Thomas H. Reiprich

    2002-07-02

    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.

  20. neutron density. The neutron density (nn) of the source was modeled by solving the simul-

    E-Print Network [OSTI]

    West, Stuart

    neutron density. The neutron density (nn) of the source was modeled by solving the simul- taneousT is the thermal neutron velocity, l is the decay constant, Ns is the s-process abun- dance, bsÀ is the maxwellian-averaged neutron capture cross-section, and t0 is the average neutron exposure (21). The branching decay of 186Re

  1. Energy transport in stochastically perturbed lattice dynamics

    E-Print Network [OSTI]

    Giada Basile; Stefano Olla; Herbert Spohn

    2008-09-12

    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.

  2. PHYSICAL REVIEW A 87, 053406 (2013) Exterior complex scaling method in time-dependent density-functional theory

    E-Print Network [OSTI]

    Chu, Shih-I

    2013-01-01

    -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

  3. Density of vacuum energy for multidimensional model of Kazner with scalar field and cosmological birth of particles

    E-Print Network [OSTI]

    Sergey Yakovlev

    2011-12-22

    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.

  4. Energy density fluctuations in inflationary cosmology

    E-Print Network [OSTI]

    Müller, H F; Muller, Harald F; Schmid, Christoph

    1994-01-01

    We analyze the energy density fluctuations contributed by scalar fields \\Phi with vanishing expectation values, \\langle\\Phi\\rangle=0, which are present in addition to the inflaton field. For simplicity we take \\Phi to be non--interacting and minimally coupled to gravity. We use normal ordering to define the renormalized energy density operator \\rho, and we show that any normal ordering gives the same result for correlation functions of \\rho. We first consider massless fields and derive the energy fluctuations in a single mode \\vk, the two--point correlation function of the energy density, the power spectrum, and the variance of the smeared energy density, \\ddR. Mass effects are investigated for energy fluctuations in single modes. All quantities considered are scale invariant at the second horizon crossing (Harrison--Zel'dovich type) for massless and for unstable massive fields. The magnitude of the relative fluctuations \\de\\rho/\\rt is of order (\\Hi/\\Mp)^2 in the massless case, where \\Hi is the Hubble constan...

  5. Photovoltaic retinal prosthesis with high pixel density

    E-Print Network [OSTI]

    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

  6. Density Functional Theory Models for Radiation Damage

    E-Print Network [OSTI]

    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

  7. Liquid Walls Innovative High Power Density Concepts

    E-Print Network [OSTI]

    California at Los Angeles, University of

    erosion as limiting factors -Results in smaller and lower cost components (chambLiquid Walls Innovative High Power Density Concepts (Based on the APEX Study) http for the Chamber Technology that can: 1. Improve the vision for an attractive fusion energy system 2. Lower

  8. IMPROVED DENSITY ESTIMATORS FOR INVERTIBLE LINEAR PROCESSES

    E-Print Network [OSTI]

    Wefelmeyer, Wolfgang

    IMPROVED DENSITY ESTIMATORS FOR INVERTIBLE LINEAR PROCESSES Anton Schick Department of Mathematical-statistic with kernel of the form K(x) = k(x - ay)k(y) dy. Schick and Wefelmeyer (2004b, 2007a) prove functional central and Schick (2007) obtain similar results for derivatives of convolutions. Schick and Wefelmeyer (2008b

  9. Population density of San Joaquin kit fox

    SciTech Connect (OSTI)

    McCue, P.; O'Farrell, T.P.; Kato, T.; Evans, B.G.

    1982-01-01

    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)

  10. ADAPTIVE DENSITY ESTIMATION WITH MASSIVE DATA SETS

    E-Print Network [OSTI]

    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

  11. Nuclear spin-density wave theory

    E-Print Network [OSTI]

    Yao Cheng

    2009-09-15

    Recently [arXiv:0906.5417], we reported a quantum phase transition of 103mRh excited by bremsstrahlung pumping. The long-lived Moessbauer excitation is delocalized as a neutral quasiparticle carrying a spin current. This letter gives a general theory for a nuclear spin-density wave propagating on crystals consisting of identical nuclei with a multipolar transition.

  12. Durable high-density data storage

    SciTech Connect (OSTI)

    Stutz, R.A.; Lamartine, B.C.

    1996-09-01

    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.

  13. Density waves in the Calogero model - revisited

    SciTech Connect (OSTI)

    Bardek, V. Feinberg, J. Meljanac, S.

    2010-03-15

    The Calogero model bears, in the continuum limit, collective excitations in the form of density waves and solitary modulations of the density of particles. This sector of the spectrum of the model was investigated, mostly within the framework of collective-field theory, by several authors, over the past 15 years or so. In this work we shall concentrate on periodic solutions of the collective BPS-equation (also known as 'finite amplitude density waves'), as well as on periodic solutions of the full static variational equations which vanish periodically (also known as 'large amplitude density waves'). While these solutions are not new, we feel that our analysis and presentation add to the existing literature, as we explain in the text. In addition, we show that these solutions also occur in a certain two-family generalization of the Calogero model, at special points in parameter space. A compendium of useful identities associated with Hilbert transforms, including our own proofs of these identities, appears in Appendix A. In Appendix B we also elucidate in the present paper some fine points having to do with manipulating Hilbert-transforms, which appear ubiquitously in the collective field formalism. Finally, in order to make this paper self-contained, we briefly summarize in Appendix C basic facts about the collective field formulation of the Calogero model.

  14. High Energy Density Laboratory Plasmas Program | National Nuclear...

    National Nuclear Security Administration (NNSA)

    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...

  15. Controlling the Actuation Rate of Low Density Shape Memory Polymer...

    Office of Scientific and Technical Information (OSTI)

    Controlling the Actuation Rate of Low Density Shape Memory Polymer Foams in Water Citation Details In-Document Search Title: Controlling the Actuation Rate of Low Density Shape...

  16. Using Radio Waves to Control Fusion Plasma Density

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

    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...

  17. Real-Time Simultaneous Measurements of Size, Density, and Composition...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Simultaneous Measurements of Size, Density, and Composition of Single Ultrafine Diesel Tailpipe Particles Real-Time Simultaneous Measurements of Size, Density, and Composition of...

  18. Density Log At Valles Caldera - Redondo Geothermal Area (Wilt...

    Open Energy Info (EERE)

    Density Log At Valles Caldera - Redondo Geothermal Area (Wilt & Haar, 1986) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Density Log At Valles...

  19. DIAGNOSTICS FOR ION BEAM DRIVEN HIGH ENERGY DENSITY PHYSICS EXPERIMENTS

    E-Print Network [OSTI]

    Bieniosek, F.M.

    2010-01-01

    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.

  20. Error Analysis in Nuclear Density Functional Theory (Journal...

    Office of Scientific and Technical Information (OSTI)

    Error Analysis in Nuclear Density Functional Theory Citation Details In-Document Search Title: Error Analysis in Nuclear Density Functional Theory Authors: Schunck, N ; McDonnell,...

  1. Error Analysis in Nuclear Density Functional Theory (Journal...

    Office of Scientific and Technical Information (OSTI)

    Error Analysis in Nuclear Density Functional Theory Citation Details In-Document Search Title: Error Analysis in Nuclear Density Functional Theory You are accessing a document...

  2. 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...

  3. Inhomogeneity smoothing using density valley formed by ion beam...

    Office of Scientific and Technical Information (OSTI)

    Inhomogeneity smoothing using density valley formed by ion beam deposition in ICF fuel pellet Citation Details In-Document Search Title: Inhomogeneity smoothing using density...

  4. WAVE-ENERGY DENSITY AND WAVE-MOMENTUM DENSITY OF EACH SPECIES OF A COLLISION-LESS PLASMA

    E-Print Network [OSTI]

    Cary, John R.

    2012-01-01

    A LiBRARY ANL WAVE-ENERGY DENSITY AND WAVE-MOMENTUM DENSITYof Califomia. To be in WAVE-ENERGY DENSITY AND WAVE~HOMENTUMExpress1ons for the wave-energy density and wave-momentum

  5. E-Cloud Effects on Singe-Bunch Dynamics in the Proposed PS2

    E-Print Network [OSTI]

    Venturini, M.

    2012-01-01

    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

  6. ?Linear Gas Jet with Tailored Density Profile"

    SciTech Connect (OSTI)

    KRISHNAN, Mahadevan

    2012-12-10

    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.

  7. Wide range equation of state for fluid hydrogen from density functional theory

    SciTech Connect (OSTI)

    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)

    2013-09-15

    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.

  8. The problem of the universal density functional and the density matrix functional theory

    SciTech Connect (OSTI)

    Bobrov, V. B. Trigger, S. A.

    2013-04-15

    The analysis in this paper shows that the Hohenberg-Kohn theorem is the constellation of two statements: (i) the mathematically rigorous Hohenberg-Kohn lemma, which demonstrates that the same ground-state density cannot correspond to two different potentials of an external field, and (ii) the hypothesis of the existence of the universal density functional. Based on the obtained explicit expression for the nonrel-ativistic particle energy in a local external field, we prove that the energy of the system of more than two non-interacting electrons cannot be a functional of the inhomogeneous density. This result is generalized to the system of interacting electrons. It means that the Hohenberg-Kohn lemma cannot provide justification of the universal density functional for fermions. At the same time, statements of the density functional theory remain valid when considering any number of noninteracting ground-state bosons due to the Bose condensation effect. In the framework of the density matrix functional theory, the hypothesis of the existence of the universal density matrix functional corresponds to the cases of noninteracting particles and to interaction in the Hartree-Fock approximation.

  9. Mixing Water and Oil Under Static High Pressure H.K. Ploeg1, M.D. McCluskey2,3, G.J. Hanna2,3

    E-Print Network [OSTI]

    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

  10. Transactions Dynamic Article Links

    E-Print Network [OSTI]

    -density solids have been utilized in catalysis,18,19 gas storage,20 and chemical separations,21 where their large

  11. A study of density modulation index in the inner heliospheric solar wind during solar cycle 23

    SciTech Connect (OSTI)

    Bisoi, Susanta Kumar; Janardhan, P.; Ingale, M.; Subramanian, P.; Ananthakrishnan, S.; Tokumaru, M.; Fujiki, K. E-mail: jerry@prl.res.in E-mail: p.subramanian@iiserpune.ac.in E-mail: tokumaru@stelab.nagoya-u.ac.jp

    2014-11-01

    The ratio of the rms electron density fluctuations to the background density in the solar wind (density modulation index, ? {sub N} ? ?N/N) is of vital importance for understanding several problems in heliospheric physics related to solar wind turbulence. In this paper, we have investigated the behavior of ? {sub N} in the inner heliosphere from 0.26 to 0.82 AU. The density fluctuations ?N have been deduced using extensive ground-based observations of interplanetary scintillation at 327 MHz, which probe spatial scales of a few hundred kilometers. The background densities (N) have been derived using near-Earth observations from the Advanced Composition Explorer. Our analysis reveals that 0.001 ? ? {sub N} ? 0.02 and does not vary appreciably with heliocentric distance. We also find that ? {sub N} declines by 8% from 1998 to 2008. We discuss the impact of these findings on problems ranging from our understanding of Forbush decreases to the behavior of the solar wind dynamic pressure over the recent peculiar solar minimum at the end of cycle 23.

  12. Ion Density Deviations in Semipermeable Ionic Microcapsules

    E-Print Network [OSTI]

    Qiyun Tang; Alan R. Denton

    2015-07-07

    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.

  13. Ultra-high density diffraction grating

    DOE Patents [OSTI]

    Padmore, Howard A.; Voronov, Dmytro L.; Cambie, Rossana; Yashchuk, Valeriy V.; Gullikson, Eric M.

    2012-12-11

    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.

  14. Density of States for HP Lattice Proteins

    E-Print Network [OSTI]

    Michael Bachmann; Wolfhard Janke

    2007-10-22

    The density of states contains all informations on energetic quantities of a statistical system, such as the mean energy, free energy, entropy, and specific heat. As a specific application, we consider in this work a simple lattice model for heteropolymers that is widely used for studying statistical properties of proteins. For short chains, we have derived exact results from conformational enumeration, while for longer ones we developed a multicanonical Monte Carlo variant of the nPERM-based chain growth method in order to directly simulate the density of states. For simplification, only two types of monomers with respective hydrophobic (H) and polar (P) residues are regarded and only the next-neighbour interaction between hydrophobic monomers, being nonadjacent along the chain, is taken into account. This is known as the HP model for the folding of lattice proteins.

  15. Global coherence of dust density waves

    SciTech Connect (OSTI)

    Killer, Carsten; Melzer, André

    2014-06-15

    The coherence of self-excited three-dimensional dust density waves has been experimentally investigated by comparing global and local wave properties. For that purpose, three-dimensional dust clouds have been confined in a radio frequency plasma with thermophoretic levitation. Global wave properties have been measured from the line-of-sight integrated dust density obtained from homogenous light extinction measurements. Local wave properties have been obtained from thin, two-dimensional illuminated laser slices of the cloud. By correlating the simultaneous global and local wave properties, the spatial coherence of the waves has been determined. We find that linear waves with small amplitudes tend to be fragmented, featuring an incoherent wave field. Strongly non-linear waves with large amplitudes, however, feature a strong spatial coherence throughout the dust cloud, indicating a high level of synchronization.

  16. Inductor Geometry With Improved Energy Density

    SciTech Connect (OSTI)

    Cui, H; Ngo, KDT; Moss, J; Lim, MHF; Rey, E

    2014-10-01

    The "constant-flux" concept is leveraged to achieve high magnetic-energy density, leading to inductor geometries with height significantly lower than that of conventional products. Techniques to shape the core and to distribute the winding turns to shape a desirable field profile are described for the two basic classes of magnetic geometries: those with the winding enclosed by the core and those with the core enclosed by the winding. A relatively constant flux distribution is advantageous not only from the density standpoint, but also from the thermal standpoint via the reduction of hot spots, and from the reliability standpoint via the suppression of flux crowding. In this journal paper on a constant-flux inductor (CFI) with enclosed winding, the foci are operating principle, dc analysis, and basic design procedure. Prototype cores and windings were routed from powder-iron disks and copper sheets, respectively. The design of CFI was validated by the assembled inductor prototype.

  17. Interfacial Ionic Liquids: Connecting Static and Dynamic Structures

    E-Print Network [OSTI]

    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

    2014-12-06

    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).

  18. Dynamics of a Two-Dimensional System of Quantum Dipoles

    SciTech Connect (OSTI)

    Mazzanti, F.; Astrakharchik, G. E.; Boronat, J.; Zillich, R. E.

    2009-03-20

    A detailed microscopic analysis of the dynamic structure function S(k,{omega}) of a two-dimensional Bose system of dipoles polarized along the direction perpendicular to the plane is presented and discussed. Starting from ground-state quantities obtained using a quantum diffusion Monte Carlo algorithm, the density-density response is evaluated in the context of the correlated basis functions (CBF) theory. CBF predicts a sharp peak and a multiexcitation component at higher energies produced by the decay of excitations. We discuss the structure of the phonon-roton peak and show that the Feynman and Bogoliubov predictions depart from the CBF result already at low densities. We finally discuss the emergence of a roton in the spectrum, but find the roton energy not low enough to make the system unstable under density fluctuations up to the highest density considered that is close to the freezing point.

  19. Energy flux density in a thermoacoustic couple

    SciTech Connect (OSTI)

    Cao, N.; Chen, S. |; Olson, R.; Swift, G.W.

    1996-06-01

    The hydro- and thermodynamical processes near and within a thermoacoustic couple are simulated and analyzed by numerical solution of the compressible Navier-Stokes, continuity, and energy equations for an ideal gas, concentrating on the time-averaged energy flux density in the gas. The numerical results show details of the heat sink at one end of the plates in the thermoacoustic couple. 15 refs., 10 figs., 1 tab.

  20. Fluctuations at finite temperature and density

    E-Print Network [OSTI]

    Borsanyi, Szabolcs

    2015-01-01

    Fluctuations of conserved charges in a grand canonical ensemble can be calculated as derivatives of the free energy with respect to the respective chemical potential. They are directly related to experimentally available observables that describe the hadronization in heavy ion collisions. The same derivatives can be used to extrapolate zero density results to finite chemical potential. We review the recent lattice calculations in the staggered formalism and discuss its implications to phenomenology and resummed perturbation theory.

  1. Nuclear fission in covariant density functional theory

    E-Print Network [OSTI]

    A. V. Afanasjev; H. Abusara; P. Ring

    2013-09-12

    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.

  2. Energy-momentum Density of Gravitational Waves

    E-Print Network [OSTI]

    Amir M. Abbassi; Saeed Mirshekari

    2014-11-29

    In this paper, we elaborate the problem of energy-momentum in general relativity by energy-momentum prescriptions theory. Our aim is to calculate energy and momentum densities for the general form of gravitational waves. In this connection, we have extended the previous works by using the prescriptions of Bergmann and Tolman. It is shown that they are finite and reasonable. In addition, using Tolman prescription, exactly, leads to same results that have been obtained by Einstein and Papapetrou prescriptions.

  3. Self-siphon simulation using molecular dynamics method: a preliminary study

    E-Print Network [OSTI]

    Viridi, Sparisoma; Khotimah, Siti Nurul; Novitrian,; Masterika, Fannia

    2011-01-01

    A self activated siphon, which is also known as self-siphon or self-priming siphon, is simulated using molecular dynamics (MD) method in order to study its behavior, especially why it has a critical height that prevents fluid from flowing through it. The trajectory of the fluid interface with air in front of the flow or the head is also fitted the trajectory modeled by parametric equations s, which is derived from geometry construction of the self-siphon. Numerical equations solved using MD method is derived from equations of motion of the head which is obtained by introducing all considered forces influencing the movement of it. Time duration needed for fluid to pass the entire tube of the self-siphon, {\\tau}, obtained from the simulation is compared quantitatively to the observation data from the previous work and it shows inverse behavior. Length of the three vertical segments are varied independently using a parameter for each segment, which are N5, N3, and N1. Room parameters of N5, N3, and N1 are constr...

  4. High Energy Density Utracapacitors: Low-Cost, High Energy and Power Density, Nanotube-Enhanced Ultracapacitors

    SciTech Connect (OSTI)

    2010-04-01

    Broad Funding Opportunity Announcement Project: FastCAP is improving the performance of an ultracapacitor—a battery-like electronic device that can complement, and possibly even replace, an HEV or EV battery pack. Ultracapacitors have many advantages over conventional batteries, including long lifespans (over 1 million cycles, as compared to 10,000 for conventional batteries) and better durability. Ultracapacitors also charge more quickly than conventional batteries, and they release energy more quickly. However, ultracapacitors have fallen short of batteries in one key metric: energy density—high energy density means more energy storage. FastCAP is redesigning the ultracapacitor’s internal structure to increase its energy density. Ultracapacitors traditionally use electrodes made of irregularly shaped, porous carbon. FastCAP’s ultracapacitors are made of tiny, aligned carbon nanotubes. The nanotubes provide a regular path for ions moving in and out of the ultracapacitor’s electrode, increasing the overall efficiency and energy density of the device.

  5. Radiography to measure the longitudinal density gradients of Pd compacts

    SciTech Connect (OSTI)

    Back, D.D.

    1992-05-14

    This study used radiography to detect and quantify density gradients in green compacts of Palladium powder. Ultrasonic velocity measurements had been tried previously, but they were affected by material properties, in addition to the density, so that an alternative was sought. The alternative technique used radiographic exposures of a series of standard compacts whose density is known and correlated with the radiographic film density. These correlations are used to predict the density in subsequent compacts.

  6. Dynamical Friction on extended perturbers

    E-Print Network [OSTI]

    O. Esquivel; B. Fuchs

    2008-04-01

    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.

  7. Dynamical Friction on extended perturbers

    E-Print Network [OSTI]

    Esquivel, O

    2008-01-01

    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.

  8. Equation of state in the generalized density scaling regime studied from ambient to ultra-high pressure conditions

    E-Print Network [OSTI]

    Andrzej Grzybowski; Kajetan Koperwas; Marian Paluch

    2013-11-15

    In this paper, based on the effective intermolecular potential with well separated density and configuration contributions and the definition of the isothermal bulk modulus, we derive two similar equations of state dedicated to describe volumetric data of supercooled liquids studied in the extremely wide pressure range related to the extremely wide density range. Both the equations comply with the generalized density scaling law of molecular dynamics versus $h(\\rho ) / T$ at different densities $\\rho $ and temperatures $T$, where the scaling exponent can be in general only a density function $\\gamma(\\rho ) = \\it{d} \\rm{ln} \\it{h / d} \\rm{ln}\\rho $ as recently argued by the theory of isomorphs. We successfully verify these equations of state by using data obtained from molecular dynamics simulations of the Kob-Andersen binary Lennard-Jones liquid. As a very important result, we find that the one-parameter density function $h(\\rho )$ analytically formulated in the case of this prototypical model of supercooled liquid, which implies the one-parameter density function $\\gamma(\\rho )$, is able to scale the structural relaxation times with the value of this function parameter determined by fitting the volumetric simulation data to the equations of state. We also show that these equations of state properly describe the pressure dependences of the isothermal bulk modulus and the configurational isothermal bulk modulus in the extremely wide pressure range investigated by the computer simulations. Moreover, we discuss the possible forms of the density functions $h(\\rho )$ and $\\gamma(\\rho )$ for real glass formers, which are suggested to be different from those valid for the model of supercooled liquid based on the Lennard-Jones intermolecular potential.

  9. A STUDY OF COMPUTATIONAL FLUID DYNAMICS APPLIED TO ROOM AIR FLOW

    E-Print Network [OSTI]

    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

  10. Computational Improvements to Quantum Wave Packet ab Initio Molecular Dynamics Using a Potential-Adapted,

    E-Print Network [OSTI]

    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

  11. Vortex dynamics in three-dimensional continuous myocardium with fiber rotation: Filament instability and fibrillationa...

    E-Print Network [OSTI]

    Mascia, Corrado

    Vortex dynamics in three-dimensional continuous myocardium with fiber rotation: Filament, or filament. This twist can then significantly alter the dynamics of the filament. This paper explores transmural filament and cause a transition to a wave turbulent state characterized by a high density

  12. Optimizing MLC-based STT-RAM Caches by Dynamic Block Size Reconfiguration

    E-Print Network [OSTI]

    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

  13. The Microscopic Linear Dynamics

    E-Print Network [OSTI]

    Penny, Will

    The Microscopic Brain Will Penny Linear Dynamics Exponentials Matrix Exponential Eigendecomposition References The Microscopic Brain Will Penny 7th April 2011 #12;The Microscopic Brain Will Penny Linear;The Microscopic Brain Will Penny Linear Dynamics Exponentials Matrix Exponential Eigendecomposition

  14. Computational Chemical Dynamics of Complex Systems University of Minnesota

    E-Print Network [OSTI]

    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

  15. Dynamic Simulation of DFIG Wind Turbines on FPGA Boards

    E-Print Network [OSTI]

    Zambreno, Joseph A.

    Dynamic Simulation of DFIG Wind Turbines on FPGA Boards Hao Chen, Student Member, IEEE, Song Sun is a friction coefficient. The wind turbine model is based on the relation between the upstream wind speed V w + 1 where p is the air density; Rw is the wind turbine radius; cp (A, (3) is the performance

  16. Dynamic Particle Coupling for GPU-based Fluid Simulation

    E-Print Network [OSTI]

    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

  17. COMPUTATIONAL FLUID DYNAMICS MODELING OF SOLID OXIDE FUEL CELLS

    E-Print Network [OSTI]

    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

  18. Carla E. Ca ceres Seasonal dynamics and interspecic competition

    E-Print Network [OSTI]

    Cáceres, Carla E.

    .Y. Both species have persisted in the lake for decades, but their water-column densities are negatively variation in vertebrate predation pressure, predation alone cannot explain the irregular daphnid dynamics. In 1992±1995, I examined the water-column abundances, birth and death rates of both species. D. pulicaria

  19. CURRICULUM VITAE David Lehman, MD

    E-Print Network [OSTI]

    Squire, Larry R.

    Prescribing License #12;AWARDS: 2004 Kaiser Permanente Award for Excellence in Teaching 2004 Medical Student and Neurology Certificate #55655 LICENSURE: 2002-present California License #A77927 2010-present Buprenorphine Teaching Award, UCSD Department of Psychiatry 2004 Chairman's Research Award, UCSD Department of Psychiatry

  20. Structural fluctuations and quantum transport through DNA molecular wires: a combined molecular dynamics and model Hamiltonian approach

    E-Print Network [OSTI]

    R. Gutierrez; R. Caetano; P. B. Woiczikowski; T. Kubar; M. Elstner; G. Cuniberti

    2009-10-02

    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.

  1. Nuclear Energy Density Optimization: UNEDF2

    E-Print Network [OSTI]

    M. Kortelainen; J. McDonnell; W. Nazarewicz; E. Olsen; P. -G. Reinhard; J. Sarich; N. Schunck; S. M. Wild; D. Davesne; J. Erler; A. Pastore

    2014-10-30

    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.

  2. Landau's necessary density conditions for LCA groups

    E-Print Network [OSTI]

    Gröchenig, K; Seip, K

    2008-01-01

    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.

  3. Particle transport inferences from density sawteeth

    SciTech Connect (OSTI)

    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)

    2014-05-15

    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.

  4. Method of high-density foil fabrication

    DOE Patents [OSTI]

    Blue, Craig A.; Sikka, Vinod K.; Ohriner, Evan K.

    2003-12-16

    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.

  5. Symmetry energy in nuclear density functional theory

    E-Print Network [OSTI]

    W. Nazarewicz; P. -G. Reinhard; W. Satula; D. Vretenar

    2013-07-22

    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.

  6. Identification of cell density signal molecule

    DOE Patents [OSTI]

    Schwarz, R.I.

    1998-04-21

    Disclosed herein is a novel proteinaceous cell density signal molecule (CDS) between 25 and 35 kD, which is secreted by fibroblastic primary avian tendon cells in culture, and causes the cells to self-regulate their proliferation and the expression of differentiated function. It effects an increase of procollagen production in avian tendon cell cultures of ten fold while proliferation rates are decreased. CDS, and the antibodies which recognize them, are important for the development of diagnostics and treatments for injuries and diseases involving connective tissues, particularly tendon. Also disclosed are methods of production and use. 2 figs.

  7. Identification of cell density signal molecule

    DOE Patents [OSTI]

    Schwarz, Richard I. (Oakland, CA)

    1998-01-01

    Disclosed herein is a novel proteinaceous cell density signal molecule (CDS) between 25 and 35 kD, which is secreted by fibroblastic primary avian tendon cells in culture, and causes the cells to self-regulate their proliferation and the expression of differentiated function. It effects an increase of procollagen production in avian tendon cell cultures of ten fold while proliferation rates are decreased. CDS, and the antibodies which recognize them, are important for the development of diagnostics and treatments for injuries and diseases involving connective tissues, particularly tendon. Also disclosed are methods of production and use.

  8. Category:Rock Density | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION JEnvironmentalBowerbank,CammackFLIR Jump to:RAPID Roadmap ContactRock Density Jump to: navigation,

  9. Categorical Introduction to Dynamical Systems Symbolic Dynamical Systems

    E-Print Network [OSTI]

    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

  10. Intramolecular and nonlinear dynamics

    SciTech Connect (OSTI)

    Davis, M.J. [Argonne National Laboratory, IL (United States)

    1993-12-01

    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.

  11. The density of states approach for the simulation of finite density quantum field theories

    E-Print Network [OSTI]

    K. Langfeld; B. Lucini; A. Rago; R. Pellegrini; L. Bongiovanni

    2015-03-02

    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.

  12. The density of states approach for the simulation of finite density quantum field theories

    E-Print Network [OSTI]

    Langfeld, K; Rago, A; Pellegrini, R; Bongiovanni, L

    2015-01-01

    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...

  13. Dynamic behavior of interfacila water at the silica surface

    SciTech Connect (OSTI)

    Argyris, Dr. Dimitrios [University of Oklahoma; Cole, David R [ORNL; Striolo, Alberto [Oklahoma University

    2009-01-01

    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.

  14. Density-Dependent Carrier Dynamics in a Quantum Dots-in-a-Well...

    Office of Scientific and Technical Information (OSTI)

    (SNL-NM), Albuquerque, NM (United States) Sponsoring Org: USDOE National Nuclear Security Administration (NNSA) Country of Publication: United States Language: English...

  15. Redox Potentials and Acidity Constants from Density Functional Theory Based Molecular Dynamics

    E-Print Network [OSTI]

    Cheng, Jun; Liu, Xiandong; VandeVondele, Joost; Sulpizi, Marialore; Sprik, Michiel

    2014-11-03

    . Critical error anal- ysis will be carried out to demonstrate how the delocalization error in GGAs affects redox potentials. The improvement by hybrid functionals reinforces this claim. We will end this Account with some conclusions and an outlook. Method... and theoretical (photo-)electrochemistry and catalysis. Xiandong Liu is an associate professor at Nanjing University. He joined the Sprik group at Cambridge in 2012 to work on computational geochemistry of mineral interfaces and transition metal complexes. Joost...

  16. 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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfate Reducing BacteriaConnectlaser-solid interaction (JournalArticle) |SciTech

  17. Introduction Dynamical properties of (-)-transformation Dynamical properties of

    E-Print Network [OSTI]

    /04/2010 Digital expansions, dynamics and tilings, Aussois Dynamical properties of the (-)-transformation 1/17 #12 of (-)-transformation Digital expansions, dynamics and tilings, Aussois Dynamical properties of the (-)-transformation 2/17 #12;Introduction Dynamical properties of (-)-transformation Introduction Digital expansions, dynamics

  18. Stellar Wind Accretion in GX301-2: Evidence for a High-density Stream

    E-Print Network [OSTI]

    D. A. Leahy; M. Kostka

    2007-09-04

    The X-ray binary system GX301-2 consists of a neutron star in an eccentric orbit accreting from the massive early-type star WRAY 977. It has previously been shown that the X-ray orbital light curve is consistent with existence of a gas stream flowing out from Wray 977 in addition to its strong stellar wind. Here, X-ray monitoring observations by the Rossi X-ray Timing Explorer (RXTE)/ All-Sky-Monitor (ASM) and pointed observations by the RXTE/ Proportional Counter Array (PCA) over the past decade are analyzed. We analyze both the flux and column density dependence on orbital phase. The wind and stream dynamics are calculated for various system inclinations, companion rotation rates and wind velocities, as well as parametrized by the stream width and density. These calculations are used as inputs to determine both the expected accretion luminosity and the column density along the line-of-sight to the neutron star. The model luminosity and column density are compared to observed flux and column density vs. orbital phase, to constrain the properties of the stellar wind and the gas stream. We find that the change between bright and medium intensity levels is primarily due to decreased mass loss in the stellar wind, but the change between medium and dim intensity levels is primarily due to decreased stream density. The mass-loss rate in the stream exceeds that in the stellar wind by a factor of 2.5. The quality of the model fits is significantly better for lower inclinations, favoring a mass for WRAY 977 of 53 to 62 Msun.

  19. Molecular dynamics studies of interfacial water at the alumina surface.

    SciTech Connect (OSTI)

    Argyris, Dr. Dimitrios [University of Oklahoma; Ho, Thomas [ORNL; Cole, David [Ohio State University

    2011-01-01

    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.

  20. A Relativistic Dynamical Collapse Model

    E-Print Network [OSTI]

    Philip Pearle

    2014-12-21

    A model is discussed where all operators are constructed from a quantum scalar field whose energy spectrum takes on all real values. The Schr\\"odinger picture wave function depends upon space and time coordinates for each particle, as well as an inexorably increasing evolution parameter $s$ which labels a foliation of space-like hypersurfaces. The model is constructed to be manifestly Lorentz invariant in the interaction picture. Free particle states and interactions are discussed in this framework. Then, the formalism of the CSL (Continuous Spontaneous Localization) theory of dynamical collapse is applied. The collapse-generating operator is chosen to to be the particle number space-time density. Unlike previous relativistically invariant models, the vacuum state is not excited. The collapse dynamics depends upon two parameters, a parameter $\\Lambda$ which represents the collapse rate/volume and a scale factor $\\ell$. A common example of collapse dynamics, involving a clump of matter in a superposition of two locations, is analyzed. The collapse rate is shown to be identical to that of non-relativistic CSL when the GRW-CSL choice of $\\ell=a=10^{-5}$cm, is made, along with $\\Lambda=\\lambda/a^{3}$ (GRW-CSL choice $\\lambda=10^{-16}s^{-1}$). However, it is also shown that the change of mass of a nucleon over the age of the universe is then unacceptably large. The case where $\\ell$ is the size of the universe is then considered. It is shown that the collapse behavior is satisfactory and the change of mass over the age of the universe is acceptably small, when $\\Lambda= \\lambda/\\ell a^{2}$.

  1. Satellite number density profiles of primary galaxies in the 2dFGRS

    E-Print Network [OSTI]

    Laura Sales; Diego G. Lambas

    2004-10-21

    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.

  2. Interaction of a Polyelectrolyte Solution with an Attractive Surface Kate Barteau

    E-Print Network [OSTI]

    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

  3. Molecular dynamics simulations of grain boundary thermal resistance in UO2

    SciTech Connect (OSTI)

    Tianyi Chen; Di Chen; Bulent H. Sencer; Lin Shao

    2014-09-01

    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.

  4. Relativistic Coulomb excitation within the time dependent superfluid local density approximation

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

    Stetcu, I.; Bertulani, C. A.; Bulgac, A.; Magierski, P.; Roche, K. J.

    2015-01-06

    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 238U. The approach is based on the superfluid local density approximation 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 compute 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, themore »dipole pygmy resonance, and giant quadrupole modes are excited during the process. As a result, the one-body dissipation of collective dipole modes is shown to lead a damping width ???0.4 MeV and the number of preequilibrium neutrons emitted has been quantified.« less

  5. Collapse models with non-white noises II: particle-density coupled noises

    E-Print Network [OSTI]

    Stephen L. Adler; Angelo Bassi

    2008-08-22

    We continue the analysis of models of spontaneous wave function collapse with stochastic dynamics driven by non-white Gaussian noise. We specialize to a model in which a classical "noise" field, with specified autocorrelator, is coupled to a local nonrelativistic particle density. We derive general results in this model for the rates of density matrix diagonalization and of state vector reduction, and show that (in the absence of decoherence) both processes are governed by essentially the same rate parameters. As an alternative route to our reduction results, we also derive the Fokker-Planck equations that correspond to the initial stochastic Schr\\"odinger equation. For specific models of the noise autocorrelator, including ones motivated by the structure of thermal Green's functions, we discuss the qualitative and qantitative dependence on model parameters, with particular emphasis on possible cosmological sources of the noise field.

  6. Molecular dynamics simulation of diffusion coefficients and structural properties of some alkylbenzenes in supercritical carbon dioxide at infinite dilution

    SciTech Connect (OSTI)

    Wang, Jinyang; Zhong, Haimin; Qiu, Wenda; Chen, Liuping; Feng, Huajie

    2014-03-14

    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.

  7. Prediction of Thermal Conductivity for Irradiated SiC/SiC Composites by Informing Continuum Models with Molecular Dynamics Data

    SciTech Connect (OSTI)

    Nguyen, Ba Nghiep; Gao, Fei; Henager, Charles H.; Kurtz, Richard J.

    2014-05-01

    This article proposes a new method to estimate the thermal conductivity of SiC/SiC composites subjected to neutron irradiation. The modeling method bridges different scales from the atomic scale to the scale of a 2D SiC/SiC composite. First, it studies the irradiation-induced point defects in perfect crystalline SiC using molecular dynamics (MD) simulations to compute the defect thermal resistance as a function of vacancy concentration and irradiation dose. The concept of defect thermal resistance is explored explicitly in the MD data using vacancy concentrations and thermal conductivity decrements due to phonon scattering. Point defect-induced swelling for chemical vapor deposited (CVD) SiC as a function of irradiation dose is approximated by scaling the corresponding MD results for perfect crystal ?-SiC to experimental data for CVD-SiC at various temperatures. The computed thermal defect resistance, thermal conductivity as a function of grain size, and definition of defect thermal resistance are used to compute the thermal conductivities of CVD-SiC, isothermal chemical vapor infiltrated (ICVI) SiC and nearly-stoichiometric SiC fibers. The computed fiber and ICVI-SiC matrix thermal conductivities are then used as input for an Eshelby-Mori-Tanaka approach to compute the thermal conductivities of 2D SiC/SiC composites subjected to neutron irradiation within the same irradiation doses. Predicted thermal conductivities for an irradiated Tyranno-SA/ICVI-SiC composite are found to be comparable to available experimental data for a similar composite ICVI-processed with these fibers.

  8. Author's Accepted Manuscript ORBIT-CENTERED ATMOSPHERIC DENSITY

    E-Print Network [OSTI]

    Wohlberg, Brendt

    solar and geomagnetic activities and different prediction windows. Compar- ison with previouslyAuthor's Accepted Manuscript ORBIT-CENTERED ATMOSPHERIC DENSITY PREDICTION USING ARTIFICIAL NEURAL Shoemaker, Riccardo Bevilacqua, ORBIT-CENTERED ATMOSPHERIC DENSITY PREDICTION USING ARTIFICIAL NEURAL

  9. Wood-Fiber/High-Density-Polyethylene Composites: Compounding Process

    E-Print Network [OSTI]

    Wood-Fiber/High-Density-Polyethylene Composites: Compounding Process J. Z. Lu,1 Q. Wu,1 I. I parameters for the wood-fiber/high-density-polyethylene blends at 60 rpm were a temperature of 180°C

  10. Innovative fuel designs for high power density pressurized water reactor

    E-Print Network [OSTI]

    Feng, Dandong, Ph. D. Massachusetts Institute of Technology

    2006-01-01

    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 ...

  11. Design of annular fuel for high power density BWRs

    E-Print Network [OSTI]

    Morra, Paolo

    2005-01-01

    Enabling high power density in the core of Boiling Water Reactors (BWRs) is economically profitable for existing or new reactors. In this work, we examine the potential for increasing the power density in BWR plants by ...

  12. Lanai high-density irradiance sensor network for characterizing...

    Office of Scientific and Technical Information (OSTI)

    Lanai high-density irradiance sensor network for characterizing solar resource variability of MW-scale PV system. Citation Details In-Document Search Title: Lanai high-density...

  13. Cosmological and astrophysical aspects of finite-density QCD

    E-Print Network [OSTI]

    Dominik J. Schwarz

    1998-07-23

    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.

  14. Observable to explore high density behaviour of symmetry energy

    E-Print Network [OSTI]

    Aman D. Sood

    2011-09-28

    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.

  15. Tunable Laser Plasma Accelerator based on Longitudinal Density Tailoring

    E-Print Network [OSTI]

    Gonsalves, Anthony

    2012-01-01

    38 fs. Laser and electron beam diagnostics Laser radiationdiagnostic provided charge density images of the electron beam

  16. Gray squirrel density, habitat suitability, and behavior in urban parks

    E-Print Network [OSTI]

    Gompper, Matthew E.

    densities. We used linear regression (SAS Institute, SAS/STAT user's guide. SAS Institute, Cary, NC, 2005

  17. High current density cathode for electrorefining in molten electrolyte

    DOE Patents [OSTI]

    Li, Shelly X.

    2010-06-29

    A high current density cathode for electrorefining in a molten electrolyte for the continuous production and collection of loose dendritic or powdery deposits. The high current density cathode eliminates the requirement for mechanical scraping and electrochemical stripping of the deposits from the cathode in an anode/cathode module. The high current density cathode comprises a perforated electrical insulated material coating such that the current density is up to 3 A/cm.sup.2.

  18. Competition between superconductivity and spin density wave

    E-Print Network [OSTI]

    Tian De Cao

    2012-08-25

    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.

  19. Observation of Density Segregation inside Migrating Dunes

    E-Print Network [OSTI]

    Christopher Groh; Ingo Rehberg; Christof A. Kruelle

    2011-09-18

    Spatiotemporal patterns in nature, such as ripples or dunes, formed by a fluid streaming over a sandy surface show complex behavior despite their simple forms. Below the surface, the granular structure of the sand particles is subject to self-organization processes, exhibiting such phenomena as reverse grading when larger particles are found on top of smaller ones. Here we report results of an experimental investigation with downscaled model dunes revealing that, if the particles differ not in size but in density, the heavier particles, surprisingly, accumulate in the central core close to the top of the dune. This finding contributes to the understanding of sedimentary structures found in nature and might be helpful to improve existing dating methods for desert dunes.

  20. Level Density in the Complex Scaling Method

    E-Print Network [OSTI]

    Ryusuke Suzuki; Takayuki Myo; Kiyoshi Kato

    2005-05-18

    It is shown that the continuum level density (CLD) at unbound energies can be calculated with the complex scaling method (CSM), in which the energy spectra of bound states, resonances and continuum states are obtained in terms of $L^2$ basis functions. In this method, the extended completeness relation is applied to the calculation of the Green functions, and the continuum-state part is approximately expressed in terms of discretized complex scaled continuum solutions. The obtained result is compared with the CLD calculated exactly from the scattering phase shift. The discretization in the CSM is shown to give a very good description of continuum states. We discuss how the scattering phase shifts can inversely be calculated from the discretized CLD using a basis function technique in the CSM.