2,489 research outputs found
Ultrasound instrumentation for the 7 inch Mach seven tunnel
The use of an Apple II+ microcomputer to collect data during the operation of the 7 inch Mach Seven Tunnel is discussed. A method by which the contamination of liquid oxygen is monitored with sound speed techniques is investigated. The electrical equivalent of a transducer bonded to a high pressure fill plug is studied. The three areas are briefly explained and data gathered for each area are presented
Quantum spin Hall effect and spin-charge separation in a kagome lattice
A two-dimensional kagome lattice is theoretically investigated within a
simple tight-binding model, which includes the nearest neighbor hopping term
and the intrinsic spin-orbit interaction between the next nearest neighbors. By
using the topological winding properties of the spin-edge states on the
complex-energy Riemann surface, the spin Hall conductance is obtained to be
quantized as () in insulating phases. This result keeps
consistent with the numerical linear-response calculation and the
\textbf{Z} topological invariance analysis. When the sample boundaries
are connected in twist, by which two defects with flux are introduced, we
obtain the spin-charge separated solitons at 1/3 (or 2/3) filling.Comment: 13 NJP pages, 7 figure
Optical excitations in hexagonal nanonetwork materials
Optical excitations in hexagonal nanonetwork materials, for example,
Boron-Nitride (BN) sheets and nanotubes, are investigated theoretically. The
bonding of BN systems is positively polarized at the B site, and is negatively
polarized at the N site. There is a permanent electric dipole moment along the
BN bond, whose direction is from the B site to the N site. When the exciton
hopping integral is restricted to the nearest neighbors, the flat band of the
exciton appears at the lowest energy. The higher optical excitations have
excitation bands similar to the electronic bands of graphene planes and carbon
nanotubes. The symmetry of the flat exciton band is optically forbidden,
indicating that the excitons related to this band will show quite long lifetime
which will cause strong luminescence properties.Comment: 4 pages; 3 figures; proceedings of "XVIth International Winterschool
on Electronic Properties of Novel Materials (IWEPNM2002)
Heat-Treated Soybean Proteins for Lactating Dairy Cattle
The value of heat treatment of protein supplements to reduce protein solubility and increase protein utilization was studied in two lactation trials. Experiment I was designed to study the utilization of heat-treated soybean meal (HSBM) by cows in early lactation. An extrusion process with moist heat was used to produce HSBM - a product with lower protein solubility than regular soybean meal (SBM). Ten cows, 3 wks post-partum, were assigned to treatments of HSBM or SBM. Due to a problem in feed bag labeling the concentrate mix containing SBM and corn was not as formulated. A large amount of ground whole soybeans was substituted for SBM making the concentrate mix lower in protein and higher in fat than intended. Milk production was higher for the cows fed HSBM due to either the higher amount of protein that they received and/or the lower protein solubility of that diet. No change was seen in milk fat percent, protein, protein components or total solids. Experiment II used a switchback design with 12 cows to determine the feeding value of a heat treated soybean product. Treatments were commercially available heat-treated soybeans (HTP), the unheated ingredients of HTP (HTP-U) and regular soybean meal (SBM). Nitrogen solubility of the protein sources in 10% Burrough\u27s buffer solution was 9.4, 25.4, and 13.8%, respectively. Concentrate mixes of protein sources and corn were formulated to contain 16% crude protein and fed at the rate of 1 kg/3 kg milk. Production of 4% fat-corrected-milk was similar for all treatments, although, production tended to be highest for cows fed heat-treated soybeans. No differences were observed in milk fat percent or total solids. Protein percent of milk was lower when fed HTP and HTP-U probably due to the higher fat content of those diets. Amounts of long chain unsaturated fatty ·acids in milk fat were increased with HTP and HTP-U diets. Rumen ammonia and serum urea were lower when fed HTP and HTP-U. This study indicates that heating soybeans improved their value slightly as a feed for lactating cows, but milk production by cows past peak production was not significantly greater than production achieved with conventional corn-soybean meal diets
Modulation Equations: Stochastic Bifurcation in Large Domains
We consider the stochastic Swift-Hohenberg equation on a large domain near
its change of stability. We show that, under the appropriate scaling, its
solutions can be approximated by a periodic wave, which is modulated by the
solutions to a stochastic Ginzburg-Landau equation. We then proceed to show
that this approximation also extends to the invariant measures of these
equations
On microscopic origins of generalized gradient structures
Classical gradient systems have a linear relation between rates and driving
forces. In generalized gradient systems we allow for arbitrary relations
derived from general non-quadratic dissipation potentials. This paper describes
two natural origins for these structures.
A first microscopic origin of generalized gradient structures is given by the
theory of large-deviation principles. While Markovian diffusion processes lead
to classical gradient structures, Poissonian jump processes give rise to
cosh-type dissipation potentials.
A second origin arises via a new form of convergence, that we call
EDP-convergence. Even when starting with classical gradient systems, where the
dissipation potential is a quadratic functional of the rate, we may obtain a
generalized gradient system in the evolutionary -limit. As examples we
treat (i) the limit of a diffusion equation having a thin layer of low
diffusivity, which leads to a membrane model, and (ii) the limit of diffusion
over a high barrier, which gives a reaction-diffusion system.Comment: Keywords: Generalized gradient structure, gradient system,
evolutionary \Gamma-convergence, energy-dissipation principle, variational
evolution, relative entropy, large-deviation principl
Effective rate equations for the over-damped motion in fluctuating potentials
We discuss physical and mathematical aspects of the over-damped motion of a
Brownian particle in fluctuating potentials. It is shown that such a system can
be described quantitatively by fluctuating rates if the potential fluctuations
are slow compared to relaxation within the minima of the potential, and if the
position of the minima does not fluctuate. Effective rates can be calculated;
they describe the long-time dynamics of the system. Furthermore, we show the
existence of a stationary solution of the Fokker-Planck equation that describes
the motion within the fluctuating potential under some general conditions. We
also show that a stationary solution of the rate equations with fluctuating
rates exists.Comment: 18 pages, 2 figures, standard LaTeX2
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