657 research outputs found
Resilient Reducibility in Nuclear Multifragmentation
The resilience to averaging over an initial energy distribution of
reducibility and thermal scaling observed in nuclear multifragmentation is
studied. Poissonian reducibility and the associated thermal scaling of the mean
are shown to be robust. Binomial reducibility and thermal scaling of the
elementary probability are robust under a broad range of conditions. The
experimental data do not show any indication of deviation due to averaging.Comment: 5 pages, 6 figures, submitted to Physical Review
The Role of Phase Space in Complex Fragment Emission from Low to Intermediate Energies
The experimental emission probabilities of complex fragments by low energy
compound nuclei and their dependence upon energy and atomic number are compared
to the transition state rates. Intermediate-mass-fragment multiplicity
distributions for a variety of reactions at intermediate energies are shown to
be binomial and thus reducible at all measured transverse energies. From these
distributions a single binary event probability can be extracted which has a
thermal dependence. A strong thermal signature is also found in the charge
distributions. The n-fold charge distributions are reducible to the 1-fold
charge distributions through a simple scaling dictated by fold number and
charge conservation.Comment: 15 pages, TeX type, psfig, also available at
http://csa5.lbl.gov/moretto/ps/brazil.ps, to appear in Proceedings of the 1st
International Conference on Nuclear Dynamics at Long and Short Distances,
April 8-12, 1996, Angra dos Reis, Brazi
Correlations in Nuclear Arrhenius-Type Plots
Arrhenius-type plots for multifragmentation process, defined as the
transverse energy dependence of the single-fragment emission-probability,
-ln(p_{b}) vs 1/sqrt(E_{t}), have been studied by examining the relationship of
the parameters p_{b} and E_{t} to the intermediate-mass fragment multiplicity
. The linearity of these plots reflects the correlation of the fragment
multiplicity with the transverse energy. These plots may not provide thermal
scaling information about fragment production as previously suggested.Comment: 12 pages, Latex, 3 Postscript figures include
The complement: a solution to liquid drop finite size effects in phase transitions
The effects of the finite size of a liquid drop undergoing a phase transition
are described in terms of the complement, the largest (but still mesoscopic)
drop representing the liquid in equilibrium with the vapor. Vapor cluster
concentrations, pressure and density from fixed mean density lattice gas
(Ising) model calculations are explained in terms of the complement. Accounting
for this finite size effect is key to determining the infinite nuclear matter
phase diagram from experimental data.Comment: Four two column pages, four figures, two tables; accepted for
publication in PR
Fidelity of SNP array genotyping using Epstein Barr virus-transformed B-lymphocyte cell lines: Implications for genome-wide association studies
Background: As availability of primary cells can be limited for genetic studies of human disease, lymphoblastoid cell lines (LCL) are common sources of genomic DNA. LCL are created in a transformation process that entails in vitro infection of human B-lymphocytes with the Epstein-Barr Virus (EBV). Methodology/Principal Findings: To test for genotypic errors potentially induced by the Epstein-Barr Virus transformation process, we compared single nucleotide polymorphism (SNP) genotype calls in peripheral blood mononuclear cells (PBMC) and LCL from the same individuals. The average mismatch rate across 19 comparisons was 0.12% for SNPs with a population call rate of at least 95%, and 0.03% at SNPs with a call rate of at least 99%. Mismatch rates were not correlated across genotype subarrays run on all sample pairs. Conclusions/Significance: Genotypic discrepancies found in PBMC and LCL pairs were not significantly different than control pairs, and were not correlated across subarrays. These results suggest that mismatch rates are minimal with stringent quality control, and that most genotypic discrepancies are due to technical artifacts rather than the EBV transformation process. Thus, LCL likely constitute a reliable DNA source for host genotype analysis. © 2009 Herbeck et al
Z-dependent Barriers in Multifragmentation from Poissonian Reducibility and Thermal Scaling
We explore the natural limit of binomial reducibility in nuclear
multifragmentation by constructing excitation functions for intermediate mass
fragments (IMF) of a given element Z. The resulting multiplicity distributions
for each window of transverse energy are Poissonian. Thermal scaling is
observed in the linear Arrhenius plots made from the average multiplicity of
each element. ``Emission barriers'' are extracted from the slopes of the
Arrhenius plots and their possible origin is discussed.Comment: 15 pages including 4 .ps figures. Submitted to Phys. Rev. Letters.
Also available at http://csa5.lbl.gov/moretto
A statistical interpretation of the correlation between intermediate mass fragment multiplicity and transverse energy
Multifragment emission following Xe+Au collisions at 30, 40, 50 and 60 AMeV
has been studied with multidetector systems covering nearly 4-pi in solid
angle. The correlations of both the intermediate mass fragment and light
charged particle multiplicities with the transverse energy are explored. A
comparison is made with results from a similar system, Xe+Bi at 28 AMeV. The
experimental trends are compared to statistical model predictions.Comment: 7 pages, submitted to Phys. Rev.
Pyroelectric and photovoltaic properties of Nb doped PZT thin films
Nb-doped lead zirconate titanate (PZT) films with up to 12 at. % of Nb were co-sputtered from oxide PZT and metallic Nb targets at a substrate temperature of 600 °C. Up to 4 at. % of Nb was doped into the perovskite structure with the formation of B-site cation vacancies for charge compensation. The preferential (111) PZT orientation decreased with Nb-doping within the solid solution region. The ferroelectric response of the films was affected by the large values of the internal field present in the samples (e.g., −84.3 kV cm−1 in 12 at. % Nd doped films). As-deposited unpoled films showed large values of the pyroelectric coefficient due to self-poling. The pyroelectric coefficient increased with Nb-doping and showed a complex dependence on the applied bias. The photovoltaic effect was observed in the films. The value of the photocurrent increased with the A/B ratio. The combined photovoltaic–pyroelectric effect increased the values of the measured current by up to 47% upon light illumination
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