9,148 research outputs found
Canonical and Microcanonical Distributions for Fermi Systems
Recursion relations are presented that allow exact calculation of canonical
and microcanonical partition functions of degenerate Fermi systems, assuming no
explicit two-body interactions. Calculations of the level density, sorted by
angular momentum, are presented for Ni-56 are presented. The issue of treating
unbound states is also addressed.Comment: 5 pages, 5 figure
Isospin Fluctuations from a Thermally Equilibrated Hadron Gas
Partition functions, multiplicity distributions, and isospin fluctuations are
calculated for canonical ensembles in which additive quantum numbers as well as
total isospin are strictly conserved. When properly accounting for
Bose-Einstein symmetrization, the multiplicity distributions of neutral pions
in a pion gas are significantly broader as compared to the non-degenerate case.
Inclusion of resonances compensates for this broadening effect. Recursion
relations are derived which allow calculation of exact results with modest
computer time.Comment: 10 pages, 5 figure
Analytical Validation of Variants to Aid in Genotype-Guided Therapy for Oncology
The Clinical Laboratory Improvement Amendments (CLIA) of 1988 requires that pharmacogenetic genotyping methods need to be established according to technical standards and laboratory practice guidelines before testing can be offered to patients. Testing methods for variants in ABCB1, CBR3, COMT, CYP3A7, C8ORF34, FCGR2A, FCGR3A, HAS3, NT5C2, NUDT15, SBF2, SEMA3C, SLC16A5, SLC28A3, SOD2, TLR4, and TPMT were validated in a CLIA-accredited laboratory. As no known reference materials were available, DNA samples that were from Coriell Cell Repositories (Camden, NJ) were used for the analytical validation studies. Pharmacogenetic testing methods developed here were shown to be accurate and 100% analytically sensitive and specific. Other CLIA-accredited laboratories interested in offering pharmacogenetic testing for these genetic variants, related to genotype-guided therapy for oncology, could use these publicly available samples as reference materials when developing and validating new genetic tests or refining current assays
An end to Nordic exceptionalism? Europeanisation and Nordic development policies
The Nordic countries have traditionally been praised for their generous and advanced development policies. Recently, however, it has been claimed that the Nordic model has faded: that the Nordic donors have become more similar to other European donors. One possible reason for such trends is influences from EU policies, that is, Europeanisation. This article critically evaluates such claims by presenting arguments for and against Europeanisation effects. We argue that changes have indeed taken place. The Nordic exceptionalism has been eroded. At the same time, a convergence of European aid policies has occurred. The question is if this is the consequence of Europeanisation – or is it rather a result of Nordicisation (the Nordic countries influencing the EU), or perhaps like-mindisation (a broader set of progressive member states having impact upon EU policies)? We suggest that Europeanisation has been extremely weak while there is strong evidence of Nordicisation but also, and increasingly, of like-mindisation. Today, a core group of mainly northern member states, including the Nordics, are the main driving forces behind European aid convergence
Origin of entropy convergence in hydrophobic hydration and protein folding
An information theory model is used to construct a molecular explanation why
hydrophobic solvation entropies measured in calorimetry of protein unfolding
converge at a common temperature. The entropy convergence follows from the weak
temperature dependence of occupancy fluctuations for molecular-scale volumes in
water. The macroscopic expression of the contrasting entropic behavior between
water and common organic solvents is the relative temperature insensitivity of
the water isothermal compressibility. The information theory model provides a
quantitative description of small molecule hydration and predicts a negative
entropy at convergence. Interpretations of entropic contributions to protein
folding should account for this result.Comment: Phys. Rev. Letts. (in press 1996), 3 pages, 3 figure
Effect of the source charge on charged-beam interferometry
We investigate quantal perturbations of the interferometric correlations of
charged bosons by the Coulomb field of an instantaneous, charged source. The
source charge increases the apparent source size by weakening the correlation
at non-zero relative momenta. The effect is strongest for pairs with a small
total momentum and is stronger for kaons than for pions of the same momenta.
The experimental data currently available are well described by this effect
without invoking Pratt's exploding source model. A simple expression is
proposed to account for the effect.Comment: 9 pages TEX, 3 Postscript figures available at
http://www.krl.caltech.edu/preprints/MAP.htm
Quantum-Statistical Correlations and Single Particle Distributions for Slowly Expanding Systems with Temperature Profile
Competition among particle evaporation, temperature gradient and flow is
investigated in a phenomenological manner, based on a simultaneous analysis of
quantum statistical correlations and momentum distributions for a
non-relativistic, spherically symmetric, three-dimensionally expanding, finite
source. The parameters of the model emission function are constrained by fits
to neutron and proton momentum distributions and correlation functions in
intermediate energy heavy-ion collisions. The temperature gradient is related
to the momentum dependence of the radius parameters of the two-particle
correlation function, as well as to the momentum-dependent temperature
parameter of the single particle spectrum, while a long duration of particle
evaporation is found to be responsible for the low relative momentum behavior
of the two-particle correlations.Comment: 20 pages + 5 ps figures, ReVTeX, uses psfig.sty, the description is
extended to include final state interactions, phenomenological evaporation
and to fit intermediate energy heavy ion proton and neutron spectrum and
correlation dat
Probable Gravitational Microlensing towards the Galatic Bulge
The MACHO project carries out regular photometric monitoring of millions of
stars in the Magellanic Clouds and Galactic Bulge, to search for very rare
gravitational microlensing events due to compact objects in the galactic halo
and disk. A preliminary analysis of one field in the Galactic Bulge, containing
{} stars observed for 190 days, reveals four stars which show
clear evidence for brightenings which are time-symmetric, achromatic in our two
passbands, and have shapes consistent with gravitational microlensing. This is
significantly higher than the event expected from microlensing by
known stars in the disk. If all four events are due to microlensing, a 95\%
confidence lower limit on the optical depth towards our bulge field is , and a ``best fit" value is ,where is the detection efficiency of the
experiment, and . If the true optical depth is close to the
``best fit" value, possible explanations include a ``maximal" disk which
accounts for most of the galactic circular velocity at the solar radius, a halo
which is centrally concentrated, or bulge-bulge microlensing.Comment: submitted to Astrophysical Journal Letters, 10 pages text as
uuencoded compressed PostScript, 5 figures and paper also available via
anonymous ftp from merlin.anu.edu.au in /pub/kcf/mach
Advanced stratified charge rotary aircraft engine design study
A technology base of new developments which offered potential benefits to a general aviation engine was compiled and ranked. Using design approaches selected from the ranked list, conceptual design studies were performed of an advanced and a highly advanced engine sized to provide 186/250 shaft Kw/HP under cruise conditions at 7620/25,000 m/ft altitude. These are turbocharged, direct-injected stratified charge engines intended for commercial introduction in the early 1990's. The engine descriptive data includes tables, curves, and drawings depicting configuration, performance, weights and sizes, heat rejection, ignition and fuel injection system descriptions, maintenance requirements, and scaling data for varying power. An engine-airframe integration study of the resulting engines in advanced airframes was performed on a comparative basis with current production type engines. The results show airplane performance, costs, noise & installation factors. The rotary-engined airplanes display substantial improvements over the baseline, including 30 to 35% lower fuel usage
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