4,531 research outputs found
Two-Dimensional Diffusion in the Presence of Topological Disorder
How topological defects affect the dynamics of particles hopping between
lattice sites of a distorted, two-dimensional crystal is addressed.
Perturbation theory and numerical simulations show that weak, short-ranged
topological disorder leads to a finite reduction of the diffusion coefficient.
Renormalization group theory and numerical simulations suggest that
longer-ranged disorder, such as that from randomly placed dislocations or
random disclinations with no net disclinicity, leads to subdiffusion at long
times.Comment: 10 pages, 6 figure
Quantification of bioactive compound content in advanced fenugreek lines selected in Alberta: levels of galactomannan
Non-Peer ReviewedFenugreek (Trigonella foenum-graecum L.) was initially introduced to Alberta as a spice and forage crop. Numerous animal and clinical studies have associated the medicinal properties of the plant with galactomannan, diosgenin and 4-hydroxyisoleucine, the three major bioactive compounds found in fenugreek seed. These bioactive molecules have been demonstrated to regulate plasma cholesterol levels, reduce plasma triglyceride concentrations and stimulate insulin secretion for blood glucose metabolism. Fourteen advanced lines grown satisfactorily in southern Alberta were selected for quantification of these compounds over two harvest seasons. These lines were grown at three locations (Brooks, Bow Island and Lethbridge) in southern Alberta under two growing conditions (rain-fed or irrigated). In this study we report on five different seed lines which possessed a high galactomannan yield during the study; i.e., seed lines F75, L3312, CDC Quatro, F80 and L3308. Seed line F75 was the only line that performed well across all locations and growing conditions. It was observed that seed
yield had a greater influence on galactomannan yield compared to seed galactomannan content. This suggests that cultivation of fenugreek plants for neutraceutical purposes should emphasize lines with high seed yield, as galactomannan content does not vary significantly among lines. An understanding
of the interaction of bioactive compound content with respective ecotypes will assist in the selection of lines for their economic potential in the functional food and natural health product industry
Toda systems in closed string tachyon condensation
We consider equations appearing in the study of localized tachyon
condensations. They are described by various Toda system when we consider the
condensation by the lowest tachyon corresponding to the monomial . The
tachyon potential is calculated as a solution to these equations. The Toda
system appearing in the deformation of \C^2/\Z_n by is identical to that
of singularity deformed by . For \C^3/\Z_n with deformation,
we find only generic non-simple form, similar to the case appearing in
\C/\Z_5\to \C/\Z_3 and we discuss the difficulties in these cases.Comment: 20 pages, no figur
Vortex Lattice Melting into Disentangled Liquid Followed by the 3D-2D Decoupling Transition in YBa_2Cu_4O_8 Single Crystals
A sharp resistance drop associated with vortex lattice melting was observed
in high quality YBa_2Cu_4O_8 single crystals. The melting line is well
described well by the anisotropic GL theory. Two thermally activated flux flow
regions, which were separated by a crossover line B_cr=1406.5(1-T/T_c)/T
(T_c=79.0 K, B_cr in T), were observed in the vortex liquid phase. Activation
energy for each region was obtained and the corresponding dissipation mechanism
was discussed. Our results suggest that the vortex lattice in YBa_2Cu_4O_8
single crystal melts into disentangled liquid, which then undergoes a 3D-2D
decoupling transition.Comment: 5 pages, 4 eps figures, RevTex (Latex2.09
Correlation of pharmacogenetic genotype with steady‐state metabolic profiles of tamoxifen: effect on active metabolite concentrations
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110007/1/cptclpt2003216.pd
Micro-scale flow on naturally occurring and engineered functional surfaces
The deposition and controlled flow of continuous thin
liquid film droplets on surfaces containing complex microscale
surface patterning (either man-made or naturally
occurring) plays a key part in numerous engineering and
biologically related fields. For example, in an engineering
context, complex surface patterning is present in processes
involving printing/photolithography [1] and the application
of precision protective coatings [2]; in biological systems
they occur in such diverse areas as plant disease control [3],
in redistribution of lung linings in respiratory systems [4],
and in sustaining life itself, as in the unusual case of the
Namibian desert beetle which drinks by harvesting morning mists [5] -- the mist condenses on hydrophilic
bumps on its upper surface to form larger droplets which
then roll down waxy hydrophobic channels between the
bumps to reach the beetle's mouth
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
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Locating Ground-Water Discharge in the Hanford Reach of the Columbia River
A bottom-contacting probe for measuring electrical conductivity at the sediment-water interface was used to scan the bed of the Columbia River adjacent to the Hanford Site in southeast Washington State during a 10-day investigation. Four river-sections, each about a kilometer in length, were scanned for variations in electrical conductivity. The probe was towed along the riverbed at a speed of 1 m/s and is position was recorded using a Global Positioning System. The bottom tows revealed several areas of elevated electrical conductivity. Where these anomalies were relatively easy to access, piezometers were driven into the riverbed and porewater electrical conductivity ranged from 111 to 150 uS/cm. The piezometers, placed in electrical conductivity “hotspots,” yielded chemical or isotopic data consistent with previous analyses of water taken from monitoring wells and visible shoreline seeps. Tritium, nitrate, and chromium exceeded water quality standards in some porewaters. The highest tritium and nitrate levels were found near the Old Hanford Townsite at 120,000 pCi/L (+ 5,880 pCi/L total propagated analytical uncertainty) and ug/L (+ 5,880 ug/L), respectively. The maximum chromium (total and hexavalent) levels were found near 100-H reactor area where unfiltered porewater total chromium was 1,900 ug/L (+ 798 ug/L) and hexavalent chromium was 20 ug/L. The electrical conductivity probe provided rapid, cost-effective reconnaissance for ground-water discharge areas when used in combination with conventional piezometers. It may be possible to obtain quantitative estimates of both natural and contaminated ground-water discharge in the Hanford Reach with more extensive surveys of river bottom
Density Waves in a Transverse Electric Field
In a quasi-one-dimensional conductor with an open Fermi surface, a Charge or
a Spin Density Wave phase can be destroyed by an electric field perpendicular
to the direction of high conductivity. This mechanism, due to the breakdown of
electron-hole symmetry, is very similar to the orbital destruction of
superconductivity by a magnetic field, due to time-reversal symmetry.Comment: 3 pages, Latex, 2 figures, to appear in Phys. Rev. B Rapid Com
Spin-dynamics simulations of the triangular antiferromagnetic XY model
Using Monte Carlo and spin-dynamics methods, we have investigated the dynamic
behavior of the classical, antiferromagnetic XY model on a triangular lattice
with linear sizes . The temporal evolutions of spin configurations
were obtained by solving numerically the coupled equations of motion for each
spin using fourth-order Suzuki-Trotter decompositions of exponential operators.
From space- and time-displaced spin-spin correlation functions and their
space-time Fourier transforms we obtained the dynamic structure factor for momentum and frequency . Below
(Kosterlitz-Thouless transition), both the in-plane () and the
out-of-plane () components of exhibit very strong
and sharp spin-wave peaks. Well above , and
apparently display a central peak, and spin-wave signatures are still seen in
. In addition, we also observed an almost dispersionless domain-wall
peak at high below (Ising transition), where long-range order
appears in the staggered chirality. Above , the domain-wall peak
disappears for all . The lineshape of these peaks is captured reasonably
well by a Lorentzian form. Using a dynamic finite-size scaling theory, we
determined the dynamic critical exponent = 1.002(3). We found that our
results demonstrate the consistency of the dynamic finite-size scaling theory
for the characteristic frequeny and the dynamic structure factor
itself.Comment: 8 pages, RevTex, 10 figures, submitted to PR
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