492 research outputs found
Stochastic Estimation of Nuclear Level Density in the Nuclear Shell Model: An Application to Parity-Dependent Level Density in Ni
We introduce a novel method to obtain level densities in large-scale
shell-model calculations. Our method is a stochastic estimation of eigenvalue
count based on a shifted Krylov-subspace method, which enables us to obtain
level densities of huge Hamiltonian matrices. This framework leads to a
successful description of both low-lying spectroscopy and the experimentally
observed equilibration of and states in Ni in a
unified manner.Comment: 13 pages, 4 figure
HAND PROPULSION TECHNIQUE OF SKILLED SPRINT SWIMMERS
This study investigated the technique of skilled sprint front-crawl swimmers in terms of the exertion of hand propulsive forces quantified by the dynamic pressure approach. Four skilled sprint front-crawl swimmers, who can swim a 100 m in less than 49 seconds, swam at a 25 m swimming pool where a motion capture system for above and under water was set up. Pressure sensors were attached on the hand to estimate hydrodynamic forces acting on the hand. The mean propulsions in the downsweep, insweep, and upsweep were 26 ± 4 N, 57 ± 12 N, and 46 ± 9 N, respectively. The four swimmers used propulsive lift of 36 ± 6 N in the downsweep, propulsive drag of 40 ± 7 N in the insweep, and propulsive drag and lift of 25 ± 9 N and 21 ± 10 N in the upsweep while swimming at their race pace
Superlattice formation lifting degeneracy protected by non-symmorphic symmetry through a metal-insulator transition in RuAs
The single crystal of RuAs obtained by Bi-flux method shows obvious
successive metal-insulator transitions at T_MI1~255 K and T_MI2~195$ K. The
X-ray diffraction measurement reveals a formation of superlattice of 3x3x3 of
the original unit cell below T_MI2, accompanied by a change of the crystal
system from the orthorhombic structure to the monoclinic one. Simple
dimerization of the Ru ions is nor seen in the ground state. The multiple As
sites observed in nuclear quadrupole resonance (NQR) spectrum also demonstrate
the formation of the superlattice in the ground state, which is clarified to be
nonmagnetic. The divergence in 1/T_1 at T_MI1 shows that a symmetry lowering by
the metal-insulator transition is accompanied by strong critical fluctuations
of some degrees of freedom. Using the structural parameters in the insulating
state, the first principle calculation reproduces successfully the reasonable
size of nuclear quadrupole frequencies for the multiple As sites, ensuring the
high validity of the structural parameters. The calculation also gives a
remarkable suppression in the density of states (DOS) near the Fermi level,
although the gap opening is insufficient. A coupled modulation of the
calculated Ru d electron numbers and the crystal structure proposes a formation
of charge density wave (CDW) in RuAs. Some lacking factors remain, but it shows
that a lifting of degeneracy protected by the non-symmorphic symmetry through
the superlattice formation is a key ingredient for the metal-insulator
transition in RuAs.Comment: 10 pages, 10 figure
Explicitly Multi-Modal Benchmarks for Multi-Objective Optimization
In multi-objective optimization, designing good benchmark problems is an
important issue for improving solvers. Although many benchmark problems have
been proposed and some of them became de facto standards, designing multimodal
problems that have a controllable landscape is still an open problem especially
for high-dimensional cases. We thus propose the Benchmark with Explicit
Multimodality (BEM), which lets the benchmark designer specify the basins of
attraction using a graph structure known as the reachability graph. In this
article, we focus on the mathematical formulation of the BEM. We will see that
the BEM has preferable characteristics such as (i) realizing user-specified
local Pareto set, (ii) allowing high-dimensional design spaces and (iii)
possessing nonseparability
Pre-steady-state kinetic studies of redox reactions catalysed by Bacillus subtilis ferredoxin-NADP+ oxidoreductase with NADP+/NADPH and ferredoxin
Ferredoxin-NADP+ oxidoreductase ([EC1.18.1.2], FNR) from Bacillus subtilis (BsFNR) is a homodimeric flavoprotein sharing structural homology with bacterial NADPH-thioredoxin reductase. Pre-steady-state kinetics of the reactions of BsFNR with NADP+, NADPH, NADPD (deuterated form) and B. subtilis ferredoxin (BsFd) using stopped-flow spectrophotometry were studied. Mixing BsFNR with NADP+ and NADPH yielded two types of charge-transfer (CT) complexes, oxidized FNR (FNRox)-NADPH and reduced FNR (FNRred)-NADP+, both having CT absorption bands centered at approximately 600 nm. After mixing BsFNRox with about a 10-fold molar excess of NADPH (forward reaction), BsFNR was almost completely reduced at equilibrium. When BsFNRred was mixed with NADP+, the amount of BsFNRox increased with increasing NADP+ concentration, but BsFNRred remained as the major species at equilibrium even with about 50-fold molar excess NADP+. In both directions, the hydride-transfer was the rate-determining step, where the forward direction rate constant (~ 500 s- 1) was much higher than the reverse one (< 10 s- 1). Mixing BsFdred with BsFNRox induced rapid formation of a neutral semiquinone form. This process was almost completed within 1 ms. Subsequently the neutral semiquinone form was reduced to the hydroquinone form with an apparent rate constant of 50 to 70 s- 1 at 10 °C, which increased as BsFdred increased from 40 to 120 μM. The reduction rate of BsFNRox by BsFdred was markedly decreased by premixing BsFNRox with BsFdox, indicating that the dissociation of BsFdox from BsFNRsq is rate-limiting in the reaction. The characteristics of the BsFNR reactions with NADP+/NADPH were compared with those of other types of FNRs. © 2016 Elsevier B.V. All rights reserved.Embargo Period 12 month
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