2,662 research outputs found
Combination quantum oscillations in canonical single-band Fermi liquids
Chemical potential oscillations mix individual-band frequencies of the de
Haas-van Alphen (dHvA) and Shubnikov-de Haas (SdH) magneto-oscillations in
canonical low-dimensional multi-band Fermi liquids. We predict a similar mixing
in canonical single-band Fermi liquids, which Fermi-surfaces have two or more
extremal cross-sections. Combination harmonics are analysed using a single-band
almost two-dimensional energy spectrum. We outline some experimental conditions
allowing for resolution of combination harmonics
The scaling properties of dissipation in incompressible isotropic three-dimensional magnetohydrodynamic turbulence
The statistical properties of the dissipation process constrain the analysis
of large scale numerical simulations of three dimensional incompressible
magnetohydrodynamic (MHD) turbulence, such as those of Biskamp and Muller
[Phys. Plasmas 7, 4889 (2000)]. The structure functions of the turbulent flow
are expected to display statistical self-similarity, but the relatively low
Reynolds numbers attainable by direct numerical simulation, combined with the
finite size of the system, make this difficult to measure directly. However, it
is known that extended self-similarity, which constrains the ratio of scaling
exponents of structure functions of different orders, is well satisfied. This
implies the extension of physical scaling arguments beyond the inertial range
into the dissipation range. The present work focuses on the scaling properties
of the dissipation process itself. This provides an important consistency check
in that we find that the ratio of dissipation structure function exponents is
that predicted by the She and Leveque [Phys. Rev. Lett 72, 336 (1994)] theory
proposed by Biskamp and Muller. This supplies further evidence that the cascade
mechanism in three dimensional MHD turbulence is non-linear random eddy
scrambling, with the level of intermittency determined by dissipation through
the formation of current sheets.Comment: 9 pages, 6 figures. Figures embedded in text. Typos corrected in text
and references. Published in Physics of Plasmas. Abstract can be found
at:http://link.aip.org/link/?php/12/02230
Immunohistochemical expression of heat shock proteins in the mouse periodontal tissues due to orthodontic mechanical stress
The histopathology of periodontal ligament of the mouse subjected to mechanical stress was studied. Immunohistochemical expressions of HSP27 and pHSP27 were examined. Experimental animals using the maxillary molars of ddY mouse by Waldo method were used in the study. A separator was inserted to induce mechanical stress. After 10 minutes, 20 minutes, 1 hour, 3 hours, 9 hours and 24 hours, the regional tissues were extracted, fixed in 4% paraformaldehyde and 0.05 M phosphate-buffered fixative solution. Paraffin sections were made for immunohistochemistry using HSP27 and p-HSP27. In the control group, the periodontal ligament fibroblasts expressed low HSP27 and p-HSP27. However, in the experimental group, periodontal ligament fibroblasts expressed HSP27 10 minutes after mechanical load application in the tension side. The strongest expression was detected 9 hours after inducing mechanical load. p-HSP27 was also expressed in a time-dependent manner though weaker than HSP27. The findings suggest that HSP27 and p-HSP27 were expressed for the maintenance of homeostasis of periodontal ligament by the activation of periodontal ligament fibroblasts on the tension side. It also suggests that these proteins act as molecular chaperones for osteoblast activation and maintenance of homeostasis
Teores foliares de nutrientes em guavira, em função de época e forma de amostragem.
bitstream/item/66213/1/32009.pdfFERTBIO
Josephson -state in superconductor-Luttinger liquid hybrid systems
Josephson current through a Luttinger liquid (LL) under a magnetic field is
theoretically studied. We derive an analytical expression of Josephson current
for clean interfaces, by using quasiclassical Green's function and functional
bosonization procedure. We show that critical currents can be renormalized by
electron-electron interactions at perfect transparency when LL is adiabatically
connected with superconductors. We also find that a generation of -state,
due to spin-dependent energy shift in Andreev bound states (ABS), is prohibited
even at zero temperature when the strength of repulsive interactions reaches
some critical value. The suppression of -state is caused by the low energy
fluctuations propagating in LL, and making the Zeeman splitting in ABS blurred.Comment: 5 pages, 4figure
Crossover between Levy and Gaussian regimes in first passage processes
We propose a new approach to the problem of the first passage time. Our
method is applicable not only to the Wiener process but also to the
non--Gaussian Lvy flights or to more complicated stochastic
processes whose distributions are stable. To show the usefulness of the method,
we particularly focus on the first passage time problems in the truncated
Lvy flights (the so-called KoBoL processes), in which the
arbitrarily large tail of the Lvy distribution is cut off. We
find that the asymptotic scaling law of the first passage time distribution
changes from -law (non-Gaussian Lvy
regime) to -law (Gaussian regime) at the crossover point. This result
means that an ultra-slow convergence from the non-Gaussian Lvy
regime to the Gaussian regime is observed not only in the distribution of the
real time step for the truncated Lvy flight but also in the
first passage time distribution of the flight. The nature of the crossover in
the scaling laws and the scaling relation on the crossover point with respect
to the effective cut-off length of the Lvy distribution are
discussed.Comment: 18pages, 7figures, using revtex4, to appear in Phys.Rev.
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