2,682 research outputs found
Low-energy expansion formula for one-dimensional Fokker-Planck and Schr\"odinger equations with asymptotically periodic potentials
We consider one-dimensional Fokker-Planck and Schr\"odinger equations with a
potential which approaches a periodic function at spatial infinity. We extend
the low-energy expansion method, which was introduced in previous papers, to be
applicable to such asymptotically periodic cases. Using this method, we study
the low-energy behavior of the Green function.Comment: author-created, un-copyedited version of an article accepted for
publication in Journal of Physics A: Mathematical and Theoretica
Accommodating Accommodations: How a Small Liberal Arts College Certification Program Redefines the New ELL State Mandates
Origin of Native Driving Force in Protein Folding
We derive an expression with four adjustable parameters that reproduces well
the 20x20 Miyazawa-Jernigan potential matrix extracted from known protein
structures. The numerical values of the parameters can be approximately
computed from the surface tension of water, water-screened dipole interactions
between residues and water and among residues, and average exposures of
residues in folded proteins.Comment: LaTeX file, Postscript file; 4 pages, 1 figure (mij.eps), 2 table
Lee surface flow phenomena over space shuttle at large angles of attack at M sub infinity equal 6
Surface pressure and heat transfer, flow separation, flow field, and oil flow patterns on the leeward side of a space shuttle orbiter model are investigated at a free stream Mach number of 6. The free stream Reynolds numbers are between 1.64 times 10 to the 7th power and 1.31 times 10 to the 8th power per meter, and the angle of attack is varied between 0 deg and 40 deg for the present experiments. The stagnation temperatures for the tests are approximately 500 K and the wall temperature is maintained at 290 K. Existing numerical methods of three-dimensional inviscid supersonic flow theory and compressible boundary layer theory are used to predict the present experimental measurements. Results of the present tests indicate two distinct types of flow separation and surface peak heating depending on the angle of attack
Origin of Tc Enhancement Induced by Doping Yttrium and Hydrogen into LaFeAsO-based Superconductors: 57Fe, 75As, 139La, and 1H-NMR Studies
We report our extensive 57Fe-, 75As-, 139La-, and 1H-NMR studies of
La_{0.8}Y_{0.2}FeAsO_{1-y} (La_{0.8}Y_{0.2}1111) and
LaFeAsO_{1-y}H_{x}(La1111H), where doping yttrium (Y) and hydrogen (H) into
optimally doped LaFeAsO_{1-y} (La1111(OPT)) increases T_c=28 K to 34 and 32 K,
respectively. In the superconducting (SC) state, the measurements of
nuclear-spin lattice-relaxation rate 1/T_1 have revealed in terms of a multiple
fully gapped s_\pm-wave model that the SC gap and T_c in La_{0.8}Y_{0.2}1111
become larger than those in La1111(OPT) without any change in doping level. In
La1111H, the SC gap and T_c also increase slightly even though a decrease in
carrier density and some disorders are significantly introduced. As a
consequence, we suggest that the optimization of both the structural parameters
and the carrier doping level to fill up the bands is crucial for increasing T_c
among these La1111-based compounds through the optimization of the Fermi
surface topology.Comment: 4 pages, 4 figures, 1 table, to be published in J. Phys. Soc. Jpn,
Vol. 79, No. 1
Mathematical Models and Exact Algorithms for the Colored Bin Packing Problem
This paper focuses on exact approaches for the Colored Bin Packing Problem
(CBPP), a generalization of the classical one-dimensional Bin Packing Problem
in which each item has, in addition to its length, a color, and no two items of
the same color can appear consecutively in the same bin. To simplify modeling,
we present a characterization of any feasible packing of this problem in a way
that does not depend on its ordering. Furthermore, we present four exact
algorithms for the CBPP. First, we propose a generalization of Val\'erio de
Carvalho's arc flow formulation for the CBPP using a graph with multiple
layers, each representing a color. Second, we present an improved arc flow
formulation that uses a more compact graph and has the same linear relaxation
bound as the first formulation. And finally, we design two exponential
set-partition models based on reductions to a generalized vehicle routing
problem, which are solved by a branch-cut-and-price algorithm through
VRPSolver. To compare the proposed algorithms, a varied benchmark set with 574
instances of the CBPP is presented. Results show that the best model, our
improved arc flow formulation, was able to solve over 62% of the proposed
instances to optimality, the largest of which with 500 items and 37 colors.
While being able to solve fewer instances in total, the set-partition models
exceeded their arc flow counterparts in instances with a very small number of
colors
Static response of Fermi liquids with tensor interactions
We use Landau's theory of a normal Fermi liquid to derive expressions for the
static response of a system with a general tensor interaction that conserves
the total spin and the total angular momentum of the quasiparticle-quasihole
pair. The magnetic susceptibility is calculated in detail, with the inclusion
of the center of mass tensor and cross vector terms in addition to the exchange
tensor one. We also introduce a new parametrization of the tensor Landau
parameters which significantly reduces the importance of high angular harmonic
contributions. For nuclear matter and neutron matter we find that the two most
important effects of the tensor interaction are to give a contribution from
multipair states and to renormalize the magnetic moments. Response to a weak
probe may be calculated using similar methods, replacing the magnetic moments
with the matrix elements of the weak charges
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