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When heated at constant volume (isochoric heating) a hot and dense plasma (10-5000 eV, 1-50 g/cm3) exhibits the same persistent microscopic structure over a wide range of temperatures as intuited long time ago by Laughlin [1]. In this steady-state regime, which depends on the chosen density and on the atomic number, the static structure is essentially independent of the temperature and results in the subtle balance between ionization and temperature leading to a constant coupling between ions. This behavior, suggested by simulations, is confirmed by an analysis in the framework of the Thomas-Fermi scaling laws and is driven by the ionization dynamics which regulates the coupling between ions and electrons. A simple fit is derived allowing for predicting the occurrence of this self-organized regime: the Γ-plateau. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We present an Atomic Cluster Expansion (ACE) machine learned potential developed for high-fidelity atomistic simulations of hydrocarbons, targeting pressures and temperatures near and above supercritical fluid regimes for molecular fluids. A diverse set of stoichiometries were covered in training, including 1:0 (pure carbon), 1:4 (methane), and 1:1 (benzene), and rich bonding environments sampled at supercritical temperatures, hydrogen rich, reactive mixtures where metastable stoichiometries arise, including 1:2 (ethylene) and 1:3 (ethane). A high-fidelity training database was constructed by performing large-scale quantum molecular dynamic simulations [density functional theory (DFT) MD] of diamond, graphite, methane, and benzene. A novel approach to selecting structures from DFT MD is also presented, which allows for the rapid selection of unique DFT MD frames from complex trajectories. Comparisons to DFT and experimental data demonstrate that the presented ACE potential accurately reproduces isotherms, carbon melting curves, radial distribution functions, and shock Hugoniots for carbon and hydrocarbon systems for pressures up to 100 GPa and temperatures up to 6000 K for hydrocarbon systems and up to 9000 K for pure carbon systems. This work delivers a potential that can be used for accurate, large-scale simulations of shocked hydrocarbons and demonstrates a methodology for fitting and validating machine learning interatomic potentials to complex molecular environments, which can be applied to energetic materials in future works., (© 2024 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).)

This study conducted integrated experiments and computational modeling to investigate the speeds of a developing shock within granular salt and analyzed the effect of various impact velocities up to 245 m/s. Experiments were conducted on table salt utilizing a novel setup with a considerable bore length for the sample, enabling visualization of a moving shock wave. Experimental analysis using particle image velocimetry enabled the characterization of shock velocity and particle velocity histories. Mesoscale simulations further enabled advanced analysis of the shock wave's substructure. In simulations, the shock front's precursor was shown to have a heterogeneous nature, which is usually modeled as uniform in continuum analyses. The presence of force chains results in a spread out of the shock precursor over a greater ramp distance. With increasing impact velocity, the shock front thickness reduces, and the precursor of the shock front becomes less heterogeneous. Furthermore, mesoscale modeling suggests the formation of force chains behind the shock front, even under the conditions of weak shock. This study presents novel mesoscale simulation results on salt corroborated with data from experiments, thereby characterizing the compaction front speeds in the weak shock regime., (© 2024. The Author(s).)

There is a general consensus that the doctor-patient interview should be as productive and efficient as possible. This is becoming increasingly difficult in a health care insurance system that demands shorter appointment times. Clinicians must therefore find ways to condense the clinical encounter without sacrificing quality. The purposes of this study were: (1) to facilitate shared decision-making between psychiatrist and patient via pre-visit patient agenda-setting, (2) to evaluate the effectiveness and ease of use of the agenda-setting tool, and (3) to determine patient and clinician satisfaction with the clinical encounter. Patients completed questionnaires to assist in agenda-setting via an electronic tablet while in the waiting area before seeing the psychiatrist. Both patients and psychiatrists then completed post-visit questionnaires to assess their satisfaction with the encounter. We measured patient satisfaction and the extent to which the psychiatrist addressed concerns before and after the visit, as well as ease of use for the patient, psychiatrist satisfaction, and clinical helpfulness to the treating psychiatrist. Additional analyses also indicated that there was a significant increase in patient satisfaction scores, compared with an average of all previous visits, and a significant increase in the number of concerns addressed during the current visit when compared with the average number of previous concerns addressed. Patients reported little difficulty using the tablet. Similarly, psychiatrists reported that the device was helpful in the clinical setting and they expressed high levels of satisfaction with the visit. We hope our work will encourage others to use this agenda-setting tool in their practices to facilitate better patient care., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

The high cost of density functional theory (DFT) has hitherto limited the ab initio prediction of the equation of state (EOS). In this article, we employ a combination of large scale computing, advanced simulation techniques, and smart data science strategies to provide an unprecedented ab initio performance analysis of the high explosive pentaerythritol tetranitrate (PETN). Comparison to both experiment and thermochemical predictions reveals important quantitative limitations of DFT for EOS prediction and thus the assessment of high explosives. In particular, we find that DFT predicts the energy of PETN detonation products to be systematically too high relative to the unreacted neat crystalline material, resulting in an underprediction of the detonation velocity, pressure, and temperature at the Chapman-Jouguet state. The energetic bias can be partially accounted for by high-level electronic structure calculations of the product molecules. We also demonstrate a modeling strategy for mapping chemical composition across a wide parameter space with limited numerical data, the results of which suggest additional molecular species to consider in thermochemical modeling.

Complex plasma mixtures with three or more components are often encountered in astrophysics or in inertial confinement fusion (ICF) experiments. For mixtures containing species with large differences in atomic number Z, the modeling needs to consider at the same time the kinetic theory for low-Z elements combined with the theory of strongly coupled plasma for high-Z elements, as well as all the intermediate situations that can appear in multicomponent systems. For such cases, we study the pair distribution functions, self-diffusions, mutual diffusion, and viscosity for ternary mixtures at extreme conditions. These quantities can be produced from first principles using orbital free molecular dynamics at the computational expense of very intensive simulations to reach good statistics. Utilizing the first-principles results as reference data, we assess the merit of a global analytic model for transport coefficients, "pseudo-ions in jellium" (PIJ), based on an isoelectronic assumption (iso-n_{e}). With a multicomponent hypernetted-chain integral equation, we verify the quality of the iso-n_{e} prescription for describing the static structure of the mixtures. This semianalytical modeling compares well with the simulation results and allows one to consider plasma mixtures not accessible to simulations. Applications are given for the mix of materials in ICF experiments. A reduction of a multicomponent mixture to an effective binary mixture is also established in the hydrodynamic limit and compared with PIJ estimations for ICF relevant mixtures.

We performed a series of plate impact experiments on NH 3 gas initially at room temperature and at a pressure of ∼100 psi. Shocked states were determined by optical velocimetry and the temperatures by optical pyrometry, yielding compression ratios of ∼5-10 and second shock temperatures in excess of 7500 K. A first-principles statistical mechanical (thermochemical) approach that included chemical dissociation yielded reasonable agreement with experimental results on the principal Hugoniot, even with interparticle interactions neglected. Theoretical analysis of reshocked states, which predicts a significant degree of chemical dissociation, showed reasonable agreement with experimental data for higher temperature shots; however, reshock calculations required the use of interaction potentials. We rationalize the very different shock temperatures obtained, relative to previous results for argon, in terms of atomic versus molecular heat capacities.

Transport properties of mixtures of elements in the dense plasma regime play an important role in natural astrophysical and experimental systems, e.g., inertial confinement fusion. We present a series of orbital-free molecular dynamics simulations on dense plasma mixtures with comparison to a global pseudo ion in jellium model. Hydrogen is mixed with elements of increasingly high atomic number (lithium, carbon, aluminum, copper, and silver) at a fixed temperature of 100 eV and constant pressure set by pure hydrogen at 2g/cm^{3}, namely, 370 Mbars. We compute ionic transport coefficients, such as self-diffusion, mutual diffusion, and viscosity for various concentrations. Small concentrations of the heavy atoms significantly change the density of the plasma and decrease the transport coefficients. The structure of the mixture evidences a strong Coulomb coupling between heavy ions and the appearance of a broad correlation peak at short distances between hydrogen atoms. The concept of an effective one component plasma is used to quantify the overcorrelation of the light element induced by the admixture of a heavy element.

We study how concentration changes ionic transport properties along isobars-isotherms for a mixture of hydrogen and silver, representative of turbulent layers relevant to inertial confinement fusion and astrophysics. Hydrogen will typically be fully ionized while silver will be only partially ionized but can have a large effective charge. This will lead to very different physical conditions for the H and Ag. Large first principles orbital free molecular dynamics simulations are performed and the resulting transport properties are analyzed. Comparisons are made with transport theory in the kinetic regime and in the coupled regime. The addition of a small amount of heavy element in a light material has a dramatic effect on viscosity and diffusion of the mixture. This effect is explained through kinetic theory as a manifestation of a crossover between classical diffusion and Lorentz diffusion.

We present an alternative method for interpreting the velocity autocorrelation function (VACF) of a fluid with application to extracting the entropy in a manner similar to the methods developed by Lin et al. [J. Chem. Phys. 119, 11792 (2003)]JCPSA60021-960610.1063/1.1624057 and improved upon by Desjarlais [Phys. Rev. E 88, 062145 (2013)]PLEEE81539-375510.1103/PhysRevE.88.062145. The liquid VACF is decomposed into two components, one gas and one solid, and each contribution's entropic portion is calculated. However, we fit both the gas and solid portions of the VACF in the time domain. This approach is applied to a single-component liquid (a two-phase model of liquid Al at the melt line) and two different two-component systems: a superionic-to-superionic (bcc to fcc) phase transition in H_{2}O at high temperatures and pressures and a metastable liquid state of MgO. For all three examples, comparisons to existing results in the literature demonstrate the validity of our alternative.

Orbital-free molecular dynamics simulations are used to benchmark two popular models for hot dense plasmas: the one component plasma (OCP) and the Yukawa model. A unified concept emerges where an effective OCP (EOCP) is constructed from the short-range structure of the plasma. An unambiguous ionization and the screening length can be defined and used for a Yukawa system, which reproduces the long-range structure with finite compressibility. Similarly, the dispersion relation of longitudinal waves is consistent with the screened model at vanishing wave number but merges with the OCP at high wave number. Additionally, the EOCP reproduces the overall relaxation time scales of the correlation functions associated with ionic motion. In the hot dense regime, this unified concept of EOCP can be fruitfully applied to deduce properties such as the equation of state, ionic transport coefficients, and the ion feature in x-ray Thomson scattering experiments.

We have performed finite-temperature density functional theory molecular dynamics simulations on dense methane, ammonia, and water mixtures (CH4:NH3:H2O) for various compositions and temperatures (2000 K ≤ T ≤ 10,000 K) that span a set of possible conditions in the interiors of ice-giant exoplanets. The equation-of-state, pair distribution functions, and bond autocorrelation functions (BACF) were used to probe the structure and dynamics of these complex fluids. In particular, an improvement to the choice of the cutoff in the BACF was developed that allowed analysis refinements for density and temperature effects. We note the relative changes in the nature of these systems engendered by variations in the concentration ratios. A basic tenet emerges from all these comparisons that varying the relative amounts of the three heavy components (C,N,O) can effect considerable changes in the nature of the fluid and may in turn have ramifications for the structure and composition of various planetary layers.

We present simulations of a four-component mixture of HCNO with orbital free molecular dynamics (OFMD). These simulations were conducted for 5-200 eV with densities ranging between 0.184 and 36.8 g/cm3. We extract the equation of state from the simulations and compare to average atom models. We found that we only need to add a cold curve model to find excellent agreement. Additionally, we studied mass transport properties. We present fits to the self-diffusion and shear viscosity that are able to reproduce the transport properties over the parameter range studied. We compare these OFMD results to models based on the Coulomb coupling parameter and one-component plasmas.

In the warm dense matter (WDM) regime, material properties like diffusion and viscosity can be obtained from lengthy quantum molecular dynamics simulations, where the quantum behavior of the electrons is represented using either Kohn-Sham or orbital-free density functional theory. To reduce the simulation duration, we fit the time dependence of the autocorrelation functions (ACFs) and then use the fit to find values of the diffusion and viscosity. This fitting procedure avoids noise in the long time behavior of the ACFs. We present a detailed analysis of the functional form used to fit the ACFs, which is always a more efficient means to obtain mass transport properties. We use the fits to estimate the statistical error of the transport properties. We apply this methodology to a dense correlated plasma of copper and a mixture of carbon and hydrogen. Both systems show structure in their ACFs and exhibit multiple time scales. The mixture contains different structural forms of the ACFs for each component in the mixture.

Extending the well-known Thomas-Fermi Z-scaling laws to the Coulomb coupling parameter, we investigate the stabilization of the ionic coupling in isochoric heating [Clérouin et al., Phys. Rev. E 87, 061101 (2013)]. This stabilization is restricted to a domain in atomic number Z, temperature, and density, including strong limitations on high couplings, that can only be obtained for high-Z elements. Contact is made with recent isochoric heating experiments. The consequences for corresponding states with respect to ionic coupling are also quantified via orbital free molecular dynamics simulations. This opens avenues for future isochoric heating experiments.

We study the superfluid character of a dipolar Bose-Einstein condensate (DBEC) in a quasi-two dimensional geometry. We consider the dipole polarization to have some nonzero projection into the plane of the condensate so that the effective interaction is anisotropic in this plane, yielding an anisotropic dispersion relation. By performing direct numerical simulations of a probe moving through the DBEC, we observe the sudden onset of drag or creation of vortex-antivortex pairs at critical velocities that depend strongly on the direction of the probe's motion. This anisotropy emerges because of the anisotropic manifestation of a rotonlike mode in the system.

We use universality in two-body dipolar physics to study three-body recombination. We present results for the universal structure of weakly bound two-dipole states that depend only on the s-wave scattering length (a). We study threshold three-body recombination rates into weakly bound dimer states as a function of the scattering length. A Fermi golden rule analysis is used to estimate rates for different events mediated by the dipole-dipole interaction and a phenomenological contact interaction. The three-body recombination rate in the limit where a≫D contains terms which scale as a{4}, a{2}D{2}, and D4, where D is the dipolar length. When a≪D, the three-body recombination rate scales as D4.

We explore the impact of the short-range interaction on the scattering of ground state polar molecules and study the transition from a weak to strong dipolar scattering over an experimentally reasonable range of energies and electric field values. In the strong dipolar limit, the scattering scales with respect to a dimensionless quantity defined by mass, induced dipole moment, and collision energy. The scaling has implications for all quantum mechanical dipolar scattering. Furthermore the universal scattering regime will readily be achieved with polar molecules at ultracold temperatures.

Objectives: To describe and examine, in a sample of depressed outpatients, the relationship between level of response to a previous SSRI or SNRI antidepressant trial and subsequent response to duloxetine hydrochloride., Experimental Design: Data collected from a multicenter trial that evaluated the safety and efficacy of duloxetine for the treatment of major depressive disorder were analyzed to determine the relationship between response to previous antidepressant treatment and degree of response to duloxetine. Time to first response, first remission, sustained response, and sustained remission during the first 12 weeks of duloxetine treatment were compared across patient groups., Principal Observations: Response and remission with duloxetine treatment ranged between 57 and 68% and 29 and 57%, respectively, and did not differ significantly across previous response levels. An additional analysis, collapsing the partial responder and responder without remission groups, indicated significantly lower rates of remission in those patients who demonstrated nonresponse to the most recent antidepressant treatment., Conclusion: Findings suggest that patient's response to duloxetine, when used as a switch treatment, may not be significant influenced by degree of response to the most recent antidepressant treatment.

Colorectal cancer is the second most leading cause of cancer death among adult Americans. Two autosomal dominant hereditary forms of the disease, familial adenomatous polyposis and hereditary nonpolyposis colorectal cancer, together account for perhaps 5% of all cases. However, in approximately 20% of additional colon cancer cases, the affected individuals report a family history of colon cancer in a first-degree relative. Similar familial clusters of colon cancer and early-onset colon adenomas have also been reported. To determine whether such familial aggregations arise by chance or reflect a hereditary colon cancer susceptibility, we conducted a whole genome scan to test for genetic linkage in 53 kindreds in which two or more siblings were affected by age 65 or younger with colon cancer or with advanced colon adenomas that were >1 cm in size or that showed high-grade dysplasia. In this cohort we found genetic linkage of disease (P = 0.00045) to chromosomal region 9q22.2-31.2 in a pattern consistent with autosomal dominant disease alleles. These data suggest that a single locus can contribute to disease susceptibility in a subset of patients with nonsyndromic forms of familial colorectal neoplasia.

Antisera were raised against peptides corresponding to the N-termini of capsid proteins VP1 and VP2 from the parvovirus minute virus of mice. Epitopes in the 142-amino-acid VP1-specific region were not accessible in the great majority of newly released viral particles, and sera directed against them failed to neutralize virus directly or deplete stocks of infectious virions. However, brief exposure to temperatures of 45 degreesC or more induced a conformational transition in a population of full virions, but not in empty viral particles, in which VP1-specific sequences became externally accessible. In contrast, the VP2 N-terminus was antibody-accessible in all full, but not empty, particles without prior treatment. An electrophoretic mobility shift assay, in which particles were heat-treated and/or preincubated with antibodies prior to electrophoresis, confirmed this pattern of epitope accessibility, showing that the heat-induced conformational transition produces a retarded form of virion that can be supershifted by incubation with VP1-specific sera. The proportion of virions undergoing transition increased with temperature, but at all temperatures up to 70 degreesC viral particles retained structure-specific antigenic determinants and remained essentially intact, without shedding individual polypeptide species or subunits. However, despite the apparent integrity of its protective coat, the genome became accessible to externally applied enzymes in an increasing proportion of virions through this temperature range, suggesting that the conformational transitions that expose VP1 likely also allow access to the genome. Heating particles to 80 degreesC or above finally induced disassembly to polypeptide monomers., (Copyright 1999 Academic Press.)

Chromosomal deletions ("deficiencies') are powerful tools in the genetic analysis of complex genomes. They have been exploited extensively in Drosophila melanogaster, an organism in which deficiencies can be efficiently induced and selected. Spontaneous deletions in humans have facilitated the dissection of phenotypes in contiguous gene syndromes and led to the positional cloning of critical genes. In mice, deletion complexes created by whole animal irradiation experiments have enabled a systematic characterization of functional units along defined chromosomal regions. However, classical mutagenesis in mice is logistically impractical for generating deletion sets on a genome-wide scale. Here, we report a high-throughput method for generating radiation-induced deletion complexes at defined regions in the genome using ES cells. Dozens of deletions of up to several centiMorgans, encompassing a specific locus, can be created in a single experiment and transmitted through the germline. The ability to rapidly create deletion complexes along chromosomes will facilitate systematic functional analyses of the mammalian genome.

The function of DNA methylation in higher plants was investigated by expression of a complementary DNA encoding a cytosine methyltransferase (MET1) from Arabidopsis thaliana as an antisense RNA in transgenic plants. This expression resulted in a 34 to 71 percent reduction in total genomic cytosine methylation. Loss of methylation was observed in both repetitive DNA and single-copy gene sequences. Developmental effects included altered heterochrony, changes in meristem identity and organ number, and female sterility. Cytosine demethylation prolonged both vegetative and reproductive phases of development. These findings implicate DNA methylation in establishing or maintaining epigenetic developmental states in the meristem.

Transmission ratio distortion (TRD) of mouse t haplotypes occurs through the interaction of multiple distorter loci with the t complex responder (Tcr) locus. Males heterozygous for a t haplotype will transmit the t-bearing chromosome to nearly all of their offspring. This process is mediated by the production of functionally inequivalent gametes: wild-type meiotic partners of t spermatozoa are rendered functionally inactive. The Tcr locus, which is required for TRD to occur, is thought to somehow protect its host spermatid from the sperm-inactivating effects of linked distorter genes (Lyon 1984). In previous work, Tcr was mapped to a small genetic interval in t haplotypes, and a candidate gene from this region was isolated (Tcp-10bt). In this work, we further localize Tcr to a 40-kb region that contains the 21-kb Tcp-10bt gene. A cloned genomic copy of Tcp-10bt was used to generate transgenic mice. The transgene was bred into a variety of genetic backgrounds to test for non-Mendelian segregation. Abberrant segregation was observed in some mice carrying either a complete t haplotype or a combination of certain partial t haplotypes. These observations, coupled with those of Snyder and colleagues (in this issue), provide genetic and functional evidence that the Tcp-10bt gene is Tcr. However, other genotypes that were predicted to produce distortion did not. The unexpected data from a variety of crosses in this work and those of our colleagues suggest that elements to the TRD system and the Tcr locus remain to be identified.

Striving for an educational balance between psychodynamics and psychotherapy led to the creation of a Psychotherapy Service. Psychodynamic teaching was preserved while biological teaching was increased. The history, philosophy, and structure of this service, combined with a chart review, give a picture of the kind of clinical experience and training available on such a service.