1,814 research outputs found
Characterization of Anopheles pseudopunctipennis larval habitats
A survey of #Anopheles pseudopunctipennis$ larval habitats was performed throughout most of its known geographic range. Eleven key environment variables characterized most larval habitats of this important vector of malaria in the Americas. Larval habitats occurred mainly in valley and foothill areas which were often situated in arid regions. Immatures were found primarily during the dry season in sun-exposed freshwater stream pools with clear, shallow, stagnant water containing abundant filamentous green algae and/or aquatic vegetation. (Résumé d'auteur
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Experimental investigation of fast electron diffusion during ECRH
The spatial diffusion of fast electrons created by electron cyclotron resonant heating (ECRH) is examined using electron cyclotron emissions viewed along a nearly vertical chord in the TEXT-U tokamak. Enhanced emission at frequencies downshifted from the cold cyclotron frequency is attributed to non-thermal electrons. The emission spectra during ECRH are consistent with the presence of low density suprathermal electrons. Comparison of the spectra measured during ECRH with a bounce averaged Fokker-Planck code which incorporates the effects of magnetic and/or electrostatic turbulence on the distribution function, shows that the level of magnetic fluctuations in the center of TEXT-U is between 3 and 5 {times} 10{sup {minus}5}. This level of magnetic fluctuation is a factor of 2 to 5 too small to explain the transport of thermal electrons (E {approximately} 1 keV) in TEXT. Thus, magnetic fluctuations are an unlikely major cause of the transport of thermal electrons in TEXT
General Algorithm For Improved Lattice Actions on Parallel Computing Architectures
Quantum field theories underlie all of our understanding of the fundamental
forces of nature. The are relatively few first principles approaches to the
study of quantum field theories [such as quantum chromodynamics (QCD) relevant
to the strong interaction] away from the perturbative (i.e., weak-coupling)
regime. Currently the most common method is the use of Monte Carlo methods on a
hypercubic space-time lattice. These methods consume enormous computing power
for large lattices and it is essential that increasingly efficient algorithms
be developed to perform standard tasks in these lattice calculations. Here we
present a general algorithm for QCD that allows one to put any planar improved
gluonic lattice action onto a parallel computing architecture. High performance
masks for specific actions (including non-planar actions) are also presented.
These algorithms have been successfully employed by us in a variety of lattice
QCD calculations using improved lattice actions on a 128 node Thinking Machines
CM-5.
{\underline{Keywords}}: quantum field theory; quantum chromodynamics;
improved actions; parallel computing algorithms
PHYLO-ASP: Phylogenetic Systematics with Answer Set Programming
This note summarizes the use of Answer Set Programming to solve various computational problems to infer phylogenetic trees and phylogenetic networks, and discusses its applicability and effectiveness on some real taxa
CsI(Tl) for WIMP dark matter searches
We report a study of CsI(Tl) scintillator to assess its applicability in
experiments to search for dark matter particles. Measurements of the mean
scintillation pulse shapes due to nuclear and electron recoils have been
performed. We find that, as with NaI(Tl), pulse shape analysis can be used to
discriminate between electron and nuclear recoils down to 4 keV. However, the
discrimination factor is typically (10-15)% better than in NaI(Tl) above 4 keV.
The quenching factor for caesium and iodine recoils was measured and found to
increase from 11% to ~17% with decreasing recoil energy from 60 to 12 keV.
Based on these results, the potential sensitivity of CsI(Tl) to dark matter
particles in the form of neutralinos was calculated. We find an improvement
over NaI(Tl) for the spin independent WIMP-nucleon interactions up to a factor
of 5 assuming comparable electron background levels in the two scintillators.Comment: 16 pages, 8 figures, to be published in Nucl. Instrum. and Meth. in
Phys. Res.
Scaling of the 3P0 strength in heavy meson strong decays
The phenomenological 3P0 decay model has been extensively applied to
calculate meson strong decays. The strength \gamma\ of the decay interaction is
regarded as a free flavor independent constant and is fitted to the data. We
calculate through the 3P0 model the total strong decay widths of the mesons
which belong to charmed, charmed-strange, hidden charm and hidden bottom
sectors. The wave function of the mesons involved in the strong decays are
given by a constituent quark model that describes well the meson phenomenology
from the light to the heavy quark sector. A global fit of the experimental data
shows that, contrarily to the usual wisdom, the \gamma\ depends on the reduced
mass of the quark-antiquark pair in the decaying meson. With this
scale-dependent strength \gamma, we are able to predict the decay width of
orbitally excited B mesons not included in the fit.Comment: 7 pages, 5 tables, 2 figure
First evidence of industrial fly-ash in an Antarctic ice core
Spheroidal carbonaceous particles (SCPs) are a component of fly-ash, the particulate by-product of industrial high temperature combustion of fuel-oil and coal-series fuels. We provide the first evidence that these indelible markers of industrialisation have been deposited in Antarctic ice, thousands of kilometres from any potential source. The earliest observed particle was deposited in an ice layer from 1936 CE. While depositional fluxes are low, chemical analysis of individual SCPs indicates a coal combustion origin
Three-dimensional digital reconstruction of human placental villus architecture in normal and complicated pregnancies.
Objective: This study aimed to examine the use of digital technology in the three-dimensional reconstruction of human placentas. Study design: Placentas obtained at term elective caesarean section were sampled, formalin-fixed and embedded in paraffin. Two hundred 5 mm consecutive sections were cut from each specimen and the resultant slides stained with haematoxylin and eosin. Slides were then scanned and the digitised images reconstructed using customised software. Results: Three-dimensional reconstructions were successfully achieved in placentas from normal pregnancies and those complicated by pre-eclampsia, growth restriction, and gestational diabetes. Marked morphological differences were readily identifiable, most clearly in the stem villus architecture. Conclusion: This method is an emerging research tool for examining placental histoarchitecture at high resolution and gaining clinically relevant insight into the placental pathology allied to pregnancy complications such as PET, IUGR and GD
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