2,917 research outputs found
Changes of some blood indices and myocardial electrolyte content during hypokinesia
Using special hypokinetic cages, the volume changes of circulating blood, its hematocrit and protein content, volume ratios between extra- and intracellular liquids in the body, as well as electrolyte content in the blood and myocardium during hypokinesia were investigated experimentally in rabbits
Computations of Three-Body Continuum Spectra
We formulate a method to solve the coordinate space Faddeev equations for
positive energies. The method employs hyperspherical coordinates and analytical
expressions for the effective potentials at large distances. Realistic
computations of the parameters of the resonances and the strength functions are
carried out for the Borromean halo nucleus 6He (n+n+alpha) for J = 0+, 0-, 1+,
1-, 2+,2-. PACS numbers: 21.45.+v, 11.80.Jy, 31.15.Ja, 21.60.GxComment: 10 pages, 3 postscript figures, LaTeX, epsf.sty, corrected misprints
in the caption of Fig.
On calculating the Berry curvature of Bloch electrons using the KKR method
We propose and implement a particularly effective method for calculating the
Berry curvature arising from adiabatic evolution of Bloch states in wave vector
k space. The method exploits a unique feature of the Korringa-Kohn-Rostoker
(KKR) approach to solve the Schr\"odinger or Dirac equations. Namely, it is
based on the observation that in the KKR method k enters the calculation via
the structure constants which depend only on the geometry of the lattice but
not the crystal potential. For both the Abelian and non-Abelian Berry curvature
we derive an analytic formula whose evaluation does not require any numerical
differentiation with respect to k. We present explicit calculations for Al, Cu,
Au, and Pt bulk crystals.Comment: 13 pages, 5 figure
Three-Body Halos in Two Dimensions
A method to study weakly bound three-body quantum systems in two dimensions
is formulated in coordinate space for short-range potentials. Occurrences of
spatially extended structures (halos) are investigated. Borromean systems are
shown to exist in two dimensions for a certain class of potentials. An
extensive numerical investigation shows that a weakly bound two-body state
gives rise to two weakly bound three-body states, a reminiscence of the Efimov
effect in three dimensions. The properties of these two states in the weak
binding limit turn out to be universal.
PACS number(s): 03.65.Ge, 21.45.+v, 31.15.Ja, 02.60NmComment: 9 pages, 2 postscript figures, LaTeX, epsf.st
Stability and correlations in dilute two-dimensional boson systems
The hyperspherical adiabatic expansion method is used to describe
correlations in a symmetric boson system rigorously confined to two spatial
dimensions. The hyperangular eigenvalue equation turns out to be almost
independent of the hyperradius, whereas the solutions are strongly varying with
the strength of the attractive two-body potentials. Instability is encountered
in hyperangular, hyperradial, and mean-field equations for almost identical
strengths inversely proportional to the particle number. The derived conditions
for stability are similar to mean-field conditions and closely related to the
possible occurrence of the Thomas and Efimov effects. Renormalization in
mean-field calculations for two spatial dimensions is probably not needed.Comment: 5 pages, two figures, submitted to Phys. Rev. A, second version
contains added discussion, especially of renormalizatio
LR and L+R Systems
We consider coupled nonholonomic LR systems on the product of Lie groups. As
examples, we study -dimensional variants of the spherical support system and
the rubber Chaplygin sphere. For a special choice of the inertia operator, it
is proved that the rubber Chaplygin sphere, after reduction and a time
reparametrization becomes an integrable Hamiltonian system on the
--dimensional sphere. Also, we showed that an arbitrary L+R system
introduced by Fedorov can be seen as a reduced system of an appropriate coupled
LR system.Comment: 18 pages, 1 figur
ARPES Study of the Metal-Insulator Transition in Bismuth Cobaltates
We present an angle-resolved photoemission spectroscopy (ARPES) study of a
Mott-Hubbard-type bismuth cobaltate system across a metal-insulator transition.
By varying the amount of Pb substitution, and by doping with Sr or Ba cation, a
range of insulating to metallic properties is obtained. We observe a systematic
change in the spectral weight of the coherent and incoherent parts, accompanied
by an energy shift of the incoherent part. The band dispersion also shows the
emergence of a weakly dispersing state at the Fermi energy with increasing
conductivity. These changes correspond with the changes in the
temperature-dependent resistivity behavior. We address the nature of the
coherent-incoherent parts in relation to the peak-dip-hump feature seen in
cuprates superconductors
The motion of the 2D hydrodynamic Chaplygin sleigh in the presence of circulation
We consider the motion of a planar rigid body in a potential flow with
circulation and subject to a certain nonholonomic constraint. This model is
related to the design of underwater vehicles.
The equations of motion admit a reduction to a 2-dimensional nonlinear
system, which is integrated explicitly. We show that the reduced system
comprises both asymptotic and periodic dynamics separated by a critical value
of the energy, and give a complete classification of types of the motion. Then
we describe the whole variety of the trajectories of the body on the plane.Comment: 25 pages, 7 figures. This article uses some introductory material
from arXiv:1109.321
Collective Decoherence of Nuclear Spin Clusters
The problem of dipole-dipole decoherence of nuclear spins is considered for
strongly entangled spin cluster. Our results show that its dynamics can be
described as the decoherence due to interaction with a composite bath
consisting of fully correlated and uncorrelated parts. The correlated term
causes the slower decay of coherence at larger times. The decoherence rate
scales up as a square root of the number of spins giving the linear scaling of
the resulting error. Our theory is consistent with recent experiment reported
in decoherence of correlated spin clusters.Comment: 4 pages, 4 figure
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