72,837 research outputs found
Operators with Large Quantum Numbers, Spinning Strings, and Giant Gravitons
We study the behaviour of spinning strings in the background of various
distributions of smeared giant gravitons in supergravity. This gives insights
into the behaviour of operators of high dimension, spin and R-charge. Using a
new coordinate system recently presented in the literature, we find that it is
particularly natural to prepare backgrounds in which the probe operators
develop a variety of interesting new behaviours. Among these are the possession
of orbital angular momentum as well as spin, the breakdown of logarithmic
scaling of dimension with spin in the high spin regime, and novel
splitting/fractionation processes.Comment: 22 pages, 9 figures, LaTe
Thermodynamic and transport properties of fluids and selected solids for cryogenic applications Summary report, 1 Dec. 1965 - 1 Nov. 1970
Summary data on thermodynamic and transport properties of fluids and solids for cryogenic application
Low-temperature acoustic characteristics of the amorphous alloy Zr41.2Ti13.8Cu12.5Ni10Be22.5
The temperature dependences of the sound velocity v and attenuation alpha of high-frequency (50–160 MHz) sound in the bulk amorphous alloy Zr41.2Ti13.8Cu12.5Ni10Be22.5 are studied at helium temperatures in the normal and superconducting states. The alloy is characterized by a relatively small constant C determining the intensity of interaction between an elastic wave and two-level systems. The density of states of the latter systems is estimated. The peculiarities in the variation of v during the superconducting transition point to the possibility of a gapless superconductivity in a narrow temperature interval near Tc
Testing extra dimensions with boundaries using Newton's law modifications
Extra dimensions with boundaries are often used in the literature, to provide
phenomenological models that mimic the standard model. In this context, we
explore possible modifications to Newton's law due to the existence of an
extra-dimensional space, at the boundary of which the gravitational field obeys
Dirichlet, Neumann or mixed boundary conditions. We focus on two types of extra
space, namely, the disk and the interval. As we prove, in order to have a
consistent Newton's law modification (i.e., of the Yukawa-type), some of the
extra-dimensional spaces that have been used in the literature, must be ruled
out.Comment: Published version, title changed, 6 figure
Containment experiments in vortex tubes with radial outflow and large superimposed axial flows
Containment tests of vortexes with radial outflow in basic vortex tube, and in axial-flow vortex tub
A Cu\u3csub\u3e4\u3c/sub\u3eS Model for the Nitrous Oxide Reductase Active Sites Supported Only by Nitrogen Ligands
To model the (His)7Cu4Sn (n = 1 or 2) active sites of nitrous oxide reductase, the first Cu4(μ4-S) cluster supported only by nitrogen donors has been prepared using amidinate supporting ligands. Structural, magnetic, spectroscopic, and computational characterization is reported. Electrochemical data indicates that the 2-hole model complex can be reduced reversibly to the 1-hole state and irreversibly to the fully reduced state
Oblique-Basis Calculations for Ti
The spectrum and wave functions of Ti are studied in oblique-basis
calculations using spherical and SU(3) shell-model states. Although the results
for Ti are not as good as those previously reported for Mg, due
primarily to the strong spin-orbit interaction that generates significant
splitting of the single-particle energies that breaks the SU(3) symmetry, a
more careful quantitative analysis shows that the oblique-basis concept is
still effective. In particular, a model space that includes a few SU(3)
irreducible representations, namely, the leading irrep (12,0) and next to the
leading irrep (10,1) including its spin S=0 and 1 states, plus spherical
shell-model configurations (SSMC) that have at least two valence nucleons
confined to the orbit -- the SM(2) states, provide results that are
compatible with SSMC with at least one valence nucleon confined to the
orbit -- the SM(3) states.Comment: 3 pages, no figures, contribution to Computational and Group
Theoretical Methods in Nuclear Physics, Playa del Carmen, Mexico, February
18-21, 200
Magnetic susceptibility of ultra-small superconductor grains
For assemblies of superconductor nanograins, the magnetic response is
analyzed as a function of both temperature and magnetic field. In order to
describe the interaction energy of electron pairs for a huge number of
many-particle states, involved in calculations, we develop a simple
approximation, based on the Richardson solution for the reduced BCS Hamiltonian
and applicable over a wide range of the grain sizes and interaction strengths
at arbitrary distributions of single-electron energy levels in a grain. Our
study is focused upon ultra-small grains, where both the mean value of the
nearest-neighbor spacing of single-electron energy levels in a grain and
variations of this spacing from grain to grain significantly exceed the
superconducting gap in bulk samples of the same material. For these ultra-small
superconductor grains, the overall profiles of the magnetic susceptibility as a
function of magnetic field and temperature are demonstrated to be qualitatively
different from those for normal grains. We show that the analyzed signatures of
pairing correlations are sufficiently stable with respect to variations of the
average value of the grain size and its dispersion over an assembly of
nanograins. The presence of these signatures does not depend on a particular
choice of statistics, obeyed by single-electron energy levels in grains.Comment: 40 pages, 12 figures, submitted to Phys. Rev. B, E-mail addresses:
[email protected], [email protected], [email protected]
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