14,983 research outputs found

    Model for the free-volume distributions of equilibrium fluids

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    We introduce and test via molecular simulation a simple model for predicting the manner in which interparticle interactions and thermodynamic conditions impact the single-particle free-volume distributions of equilibrium fluids. The model suggests a scaling relationship for the density-dependent behavior of the hard-sphere system. It also predicts how the second virial coefficients of fluids with short-range attractions affect their free-volume distributions.Comment: 7 pages, 5 figure

    Structural anomalies of fluids: Origins in second and higher coordination shells

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    Compressing or cooling a fluid typically enhances its static interparticle correlations. However, there are notable exceptions. Isothermal compression can reduce the translational order of fluids that exhibit anomalous waterlike trends in their thermodynamic and transport properties, while isochoric cooling (or strengthening of attractive interactions) can have a similar effect on fluids of particles with short-range attractions. Recent simulation studies by Yan [Phys. Rev. E 76, 051201 (2007)] on the former type of system and Krekelberg [J. Chem. Phys. 127, 044502 (2007)] on the latter provide examples where such structural anomalies can be related to specific changes in second and more distant coordination shells of the radial distribution function. Here, we confirm the generality of this microscopic picture through analysis, via molecular simulation and integral equation theory, of coordination shell contributions to the two-body excess entropy for several related model fluids which incorporate different levels of molecular resolution. The results suggest that integral equation theory can be an effective and computationally inexpensive tool for assessing, based on the pair potential alone, whether new model systems are good candidates for exhibiting structural (and hence thermodynamic and transport) anomalies.Chemical Engineerin

    New York State Disability and Employment Status Report, 2009.

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    This Status Report is intended to provide information on disability in New York State, focusing on the working-age population (16-64 years old, except where noted). The report presents: 1) estimates of disability prevalence overall and among various groups; 2) indications of where disparities exist in employment rate, educational attainment, and financial status between people with and without disabilities; and 3) characteristics of New York State which may influence employment outcomes for people with disabilities

    Genetically Encoded Photo-cross-linkers Map the Binding Site of an Allosteric Drug on a G Protein-Coupled Receptor

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    G protein-coupled receptors (GPCRs) are dynamic membrane proteins that bind extracellular molecules to transduce signals. Although GPCRs represent the largest class of therapeutic targets, only a small percentage of their ligand-binding sites are precisely defined. Here we describe the novel application of targeted photo-cross-linking using unnatural amino acids to obtain structural information about the allosteric binding site of a small molecule drug, the CCR5-targeted HIV-1 co-receptor blocker maraviroc

    The X-ray Properties of Five Galactic Supernova Remnants Detected by the Spitzer GLIMPSE Survey

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    (Abbreviated) We present a study of the X-ray properties of five Galactic supernova remnants (SNRs) -- Kes 17 (G304.6++0.1), G311.5−-0.3, G346.6−-0.2, CTB 37A (G348.5++0.1) and G348.5−-0.0 -- that were detected in the infrared by Reach et al. (2006) in an analysis of data from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) that was conducted by the Spitzer Space Telescope. We present and analyze archival ASCA observations of Kes 17, G311.5−-0.3 and G346.6−-0.2, archival XMM-Newton observations of Kes 17, CTB 37A and G348.5−-0.0 and an archival Chandra observation of CTB 37A. All of the SNRs are clearly detected in the X-ray possibly except for G348.5−-0.0. Our study reveals that the four detected SNRs all feature center-filled X-ray morphologies and that the observed emission from these sources is thermal in all cases. We argue that these SNRs should be classified as mixed-morphology SNRs (MM SNRs): our study strengthens the correlation between MM SNRs and SNRs interacting with molecular clouds and suggests that the origin of mixed-morphology SNRs may be due to the interactions between these SNRs and adjacent clouds. Our ASCA analysis of G311.5−-0.3 reveals for the first time X-ray emission from this SNR: the X-ray emission is center-filled within the radio and infrared shells and thermal in nature (kTkT ∼\sim 0.98 keV), thus motivating its classification as an MM SNR. We find considerable spectral variations in the properties associated with the plasmas of the other X-ray-detected SNRs, such as a possible overabundance of magnesium in the plasma of Kes 17. Finally, we also estimate such properties as electron density nne_e, radiative age ttrad_{rad} and swept-up mass MMX_X for each of the four X-ray-detected SNRs.Comment: 78 pages, 26 figures, Astronomical Journal, in pres

    Tuning density profiles and mobility of inhomogeneous fluids

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    Density profiles are the most common measure of inhomogeneous structure in confined fluids, but their connection to transport coefficients is poorly understood. We explore via simulation how tuning particle-wall interactions to flatten or enhance the particle layering of a model confined fluid impacts its self-diffusivity, viscosity, and entropy. Interestingly, interactions that eliminate particle layering significantly reduce confined fluid mobility, whereas those that enhance layering can have the opposite effect. Excess entropy helps to understand and predict these trends.Comment: 5 pages, 3 figure

    The 'Jazz Gene': Examining the Use of Jazz Aesthetics in Hip-Hop Music

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    This thesis is made up of 7 original compositions that aid in exploring the common cultural traits and practices of African-American music referred to using the metaphor of the Jazz Gene. These conventions are historically contextualized and analyzed through two categories of rhythm and harmony from a post-Jazz perspective. The compositions in this thesis also highlight influences and artists from various African-American genres whose active compositional styles create unique frameworks in their genres such as James Brown, Joshua Redman, Roy Hargrove, Robert Glasper, and Dr. Dre. I surmise that without these common traits and practices found in these unique frameworks, Hip-Hop music would not persevere or evolve. These aesthetics exist in Hip-Hop just as much as they exist in Funk, Soul, R&B, Gospel, and Jazz music

    Impact of surface roughness on diffusion of confined fluids

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    Using event-driven molecular dynamics simulations, we quantify how the self diffusivity of confined hard-sphere fluids depends on the nature of the confining boundaries. We explore systems with featureless confining boundaries that treat particle-boundary collisions in different ways and also various types of physically (i.e., geometrically) rough boundaries. We show that, for moderately dense fluids, the ratio of the self diffusivity of a rough wall system to that of an appropriate smooth-wall reference system is a linear function of the reciprocal wall separation, with the slope depending on the nature of the roughness. We also discuss some simple practical ways to use this information to predict confined hard-sphere fluid behavior in different rough-wall systems
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