389 research outputs found
Conformal Field Theory as Microscopic Dynamics of Incompressible Euler and Navier-Stokes Equations
We consider the hydrodynamics of relativistic conformal field theories at
finite temperature. We show that the limit of slow motions of the ideal
hydrodynamics leads to the non-relativistic incompressible Euler equation. For
viscous hydrodynamics we show that the limit of slow motions leads to the
non-relativistic incompressible Navier-Stokes equation. We explain the physical
reasons for the reduction and discuss the implications. We propose that
conformal field theories provide a fundamental microscopic viewpoint of the
equations and the dynamics governed by them.Comment: 4 page
Shocks and Universal Statistics in (1+1)-Dimensional Relativistic Turbulence
We propose that statistical averages in relativistic turbulence exhibit
universal properties. We consider analytically the velocity and temperature
differences structure functions in the (1+1)-dimensional relativistic
turbulence in which shock waves provide the main contribution to the structure
functions in the inertial range. We study shock scattering, demonstrate the
stability of the shock waves, and calculate the anomalous exponents. We comment
on the possibility of finite time blowup singularities.Comment: 37 pages, 7 figure
Localization of Multi-Dimensional Wigner Distributions
A well known result of P. Flandrin states that a Gaussian uniquely maximizes
the integral of the Wigner distribution over every centered disc in the phase
plane. While there is no difficulty in generalizing this result to
higher-dimensional poly-discs, the generalization to balls is less obvious. In
this note we provide such a generalization.Comment: Minor corrections, to appear in the Journal of Mathematical Physic
Reentrant vortex lattice transformation in four-fold symmetric superconductors
The physics behind the rhombicsquarerhombic flux line lattice
transformation in increasing fields is clarified on the basis of Eilenberger
theory. We demonstrate that this reentrance observed in LuNiBC is due
to intrinsic competition between superconducting gap and Fermi surface
anisotropies. The calculations reproduce not only it but also predict yet not
found lock-in transition to a square lattice with different orientation in
higher field. In view of physical origin given, this sequence of transitions is
rather generic to occur in four-fold symmetric superconductors.Comment: 5 pages, 4 figures,submitted to Phys. Rev. Let
No quasi-long-range order in strongly disordered vortex glasses: a rigorous proof
The paper contains a rigorous proof of the absence of quasi-long-range order
in the random-field O(N) model for strong disorder in the space of an arbitrary
dimensionality. This result implies that quasi-long-range order inherent to the
Bragg glass phase of the vortex system in disordered superconductors is absent
as the disorder or external magnetic field is strong.Comment: 3 pages, Revte
Stepwise RNP assembly at the site of H/ACA RNA transcription in human cells
Mammalian H/ACA RNPs are essential for ribosome biogenesis, premessenger RNA splicing, and telomere maintenance. These RNPs consist of four core proteins and one RNA, but it is not known how they assemble. By interrogating the site of H/ACA RNA transcription, we dissected their biogenesis in single cells and delineated the role of the non-core protein NAF1 in the process. NAF1 and all of the core proteins except GAR1 are recruited to the site of transcription. NAF1 binds one of the core proteins, NAP57, and shuttles between nucleus and cytoplasm. Both proteins are essential for stable H/ACA RNA accumulation. NAF1 and GAR1 bind NAP57 competitively, suggesting a sequential interaction. Our analyses indicate that NAF1 binds NAP57 and escorts it to the nascent H/ACA RNA and that GAR1 then replaces NAF1 to yield mature H/ACA RNPs in Cajal bodies and nucleoli
Astrophysical Fluids of Novae: High Resolution Pre-decay X-ray spectrum of V4743 Sagittarii
Eight X-ray observations of V4743 Sgr (2002), observed with Chandra and
XMM-Newton are presented. The nova turned off some time between days 301.9 and
371, and the X-ray flux subsequently decreased from day 301.9 to 526 following
an exponential decline time scale of days. We use the absorption
lines present in the SSS spectrum for diagnostic purposes, and characterize the
physics and the dynamics of the expanding atmosphere during the explosion of
the nova. The information extracted from this first stage is then used as input
for computing full photoionization models of the ejecta in V4743 Sgr. The SSS
spectrum is modeled with a simple black-body and multiplicative Gaussian lines,
which provides us of a general kinematical picture of the system, before it
decays to its faint phase (Ness et al. 2003). In the grating spectra taken
between days 180.4 and 370, we can resolve the line profiles of absorption
lines arising from H-like and He-like C, N, and O, including transitions
involving higher principal quantum numbers. Except for a few interstellar
lines, all lines are significantly blue-shifted, yielding velocities between
1000 and 6000 km/s which implies an ongoing mass loss. It is shown that
significant expansion and mass loss occur during this phase of the explosion,
at a rate . Our measurements show that the efficiency of the amount of
energy used for the motion of the ejecta, defined as the ratio between the
kinetic luminosity and the radiated luminosity , is
of the order of one.Comment: 25 pages, 9 figures. Accepted in book: Recent Advances in Fluid
Dynamics with Environmental Applications, pp.365-39
Equilibration and Dynamic Phase Transitions of a Driven Vortex Lattice
We report on the observation of two types of current driven transitions in
metastable vortex lattices. The metastable states, which are missed in usual
slow transport measurements, are detected with a fast transport technique in
the vortex lattice of undoped
2H-NbSe. The transitions are seen by following the evolution of these
states when driven by a current. At low currents we observe an equilibration
transition from a metastable to a stable state, followed by a dynamic
crystallization transition at high currents.Comment: 5 pages, 4 figure
Travelling waves in a drifting flux lattice
Starting from the time-dependent Ginzburg-Landau (TDGL) equations for a type
II superconductor, we derive the equations of motion for the displacement field
of a moving vortex lattice without inertia or pinning. We show that it is
linearly stable and, surprisingly, that it supports wavelike long-wavelength
excitations arising not from inertia or elasticity but from the
strain-dependent mobility of the moving lattice. It should be possible to image
these waves, whose speeds are a few \mu m/s, using fast scanning tunnelling
microscopy.Comment: 4 pages, revtex, 2 .eps figures imbedded in paper, title shortened,
minor textual change
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