5,404 research outputs found
Aharonov-Bohm Effect at liquid-nitrogen temperature: Frohlich superconducting quantum device
The Aharonov-Bohm (AB) effect has been accepted and has promoted
interdisciplinary scientific activities in modern physics. To observe the AB
effect in condensed matter physics, the whole system needs to maintain phase
coherence, in a tiny ring of the diameter 1 micrometer and at low temperatures
below 1 K. We report that AB oscillations have been measured at high
temperature 79 K by use of charge-density wave (CDW) loops in TaS3 ring
crystals. CDW condensate maintained macroscopic quantum coherence, which
extended over the ring circumference 85 micrometer. The periodicity of the
oscillations is h/2e in accuracy within a 10 percent range. The observation of
the CDW AB effect implies Frohlich superconductivity in terms of macroscopic
coherence and will provide a novel quantum interference device running at room
temperature.Comment: 11 pages, 4 figure
Duality Breaking of Vortex Configuration in a Hierarchical Honeycomb Network
We report measurements of Little-Parks oscillation on the hierarchical
honeycomb-superconducting network for investigating possible effects of
hierarchical structure in terms of spatial symmetry, parity and duality. We
observed an asymmetric Little-Parks oscillation about ,
although spatial symmetry was kept in the network. In comparison with a regular
honeycomb network, the asymmetric oscillation is attributed to hierarchy which
induces mixture of commensurate and incommensurate regions. The asymmetric
oscillation is found to indicate breaking of the duality of vortex
configuration.Comment: 12 pages, 6 figure
Stochastic Gravitational Wave Background originating from Halo Mergers
The stochastic gravitational wave background (GWB) from halo mergers is
investigated by a quasi-analytic method. The method we employ consists of two
steps. The first step is to construct a merger tree by using the Extended
Press-Schechter formalism or the Sheth & Tormen formalism, with Monte-Carlo
realizations. This merger tree provides evolution of halo masses. From -body
simulation of two-halo mergers, we can estimate the amount of gravitational
wave emission induced by the individual merger process. Therefore the second
step is to combine this gravitaional wave emission to the merger tree and
obtain the amplitude of GWB. We find for Hz, where is the energy density of the GWB. It
turns out that most of the contribution on the GWB comes from halos with masses
below and mergers at low redshift, i.e., .Comment: 5 pages, 8 figures. Accepted for publication in Physical Review
Modeling Intra-Cluster Gas in Triaxial Dark Halos : An Analytical Approach
We present the first physical model for the non-spherical intra-cluster gas
distribution in hydrostatic equilibrium under the gravity of triaxial dark
matter halos. Adopting the concentric triaxial density profiles of the dark
halos with constant axis ratios proposed by Jing & Suto (2002), we derive an
analytical expression for the triaxial halo potential on the basis of the
perturbation theory, and find the hydrostatic solutions for the gas density and
temperature profiles both in isothermal and polytropic equations of state. The
resulting iso-potential surfaces are well approximated by triaxial ellipsoids
with the eccentricities dependent on the radial distance. We also find a
formula for the eccentricity ratio between the intra-cluster gas and the
underlying dark halo. Our results allow one to determine the shapes of the
underlying dark halos from the observed intra-cluster gas through the X-ray
and/or the Sunyaev-Zel'dovich effects clusters.Comment: accepted by ApJ, LaTex file, 22 pages, 8 postscript figure
Schwinger-Dyson Analysis of Dynamical Symmetry Breaking on a Brane with Bulk Yang-Mills Theory
The dynamically generated fermion mass is investigated in the flat brane
world with (4+delta)-dimensional bulk space-time, and in the Randall-Sundrum
(RS) brane world. We consider the bulk Yang-Mills theory interacting with the
fermion confined on a four-dimensional brane. Based on the effective theory
below the reduced cutoff scale on the brane, we formulate the Schwinger-Dyson
equation of the brane fermion propagator. By using the improved ladder
approximation we numerically solve the Schwinger-Dyson equation and find that
the dynamical fermion mass is near the reduced cutoff scale on the brane for
the flat brane world with delta >= 3 and for the RS brane world. In RS brane
world KK excited modes of the bulk gauge field localized around the y = pi R
brane and it enhances the dynamical symmetry breaking on the brane. The decay
constant of the fermion and the anti-fermion composite operator can be taken to
be the order of the electroweak scale much smaller than the Planck scale.
Therefore electroweak mass scale can be realized from only the Planck scale in
the RS brane world due to the fermion and the anti-fermion pair condensation.
That is a dynamical realization of Randall-Sundrum model which solves the
weak-Planck hierarchy problem.Comment: 21 pages, 12 figures; typos corrected, references added and updated,
footnotes adde
Quantum Melting of Charge Order due to Frustration in Two-Dimensional Quarter-Filled Systems
The effect of geometrical frustration in a two-dimensional 1/4-filled
strongly correlated electron system is studied theoretically, motivated by
layered organic molecular crystals. An extended Hubbard model on the square
lattice is considered, with competing nearest neighbor Coulomb interaction, V,
and that of next-nearest neighbor along one of the diagonals, V', which favor
different charge ordered states. Based on exact diagonalization calculations,
we find a metallic phase stabilized over a broad window at V' ~ V even for
large Coulomb repulsion strengths as a result of frustrating the charge ordered
states. Slightly modifying the lattice geometry relevant to the actual organic
compounds does not alter the results, suggesting that this `quantum melting' of
charge order is a robust feature of frustrated strongly correlated 1/4-filled
systems.Comment: 5 pages, 4 figures, to be published in Phys. Rev.
Solubilization and partial purification of a thylakoidal enzyme of spinach involved in the processing of D1 protein
AbstractThe enzyme involved in the processing of D1 precursor protein was solubilized from spinach thylakoids by Triton X-100 treatment and then partially purified in the presence of the detergent by Sephadex G-75 gel-filtration chromatography. The apparent molecular mass of the enzyme was estimated via this procedure to be about 34 kDa. The D1 precursor protein translated from the extracted spinach chloroplast RNA by a wheat germ cell-free system was used here as a substrate in measurements of the activity
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