14,983 research outputs found
Model for the free-volume distributions of equilibrium fluids
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
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.
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
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
(Abbreviated) We present a study of the X-ray properties of five Galactic
supernova remnants (SNRs) -- Kes 17 (G304.60.1), G311.50.3, G346.60.2,
CTB 37A (G348.50.1) and G348.50.0 -- 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,
G311.50.3 and G346.60.2, archival XMM-Newton observations of Kes 17, CTB
37A and G348.50.0 and an archival Chandra observation of CTB 37A. All of the
SNRs are clearly detected in the X-ray possibly except for G348.50.0. 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 G311.50.3 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 ( 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
, radiative age and swept-up mass 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
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
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
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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