5,212 research outputs found
Mef2 induction of the immediate early gene Hr38/Nr4a is terminated by Sirt1 to promote ethanol tolerance.
Drug naïve animals given a single dose of ethanol show changed responses to subsequent doses, including the development of ethanol tolerance and ethanol preference. These simple forms of behavioral plasticity are due in part to changes in gene expression and neuronal properties. Surprisingly little is known about how ethanol initiates changes in gene expression or what the changes do. Here we demonstrate a role in ethanol plasticity for Hr38, the sole Drosophila homolog of the mammalian Nr4a1/2/3 class of immediate early response transcription factors. Acute ethanol exposure induces transient expression of Hr38 and other immediate early neuronal activity genes. Ethanol activates the Mef2 transcriptional activator to induce Hr38, and the Sirt1 histone/protein deacetylase is required to terminate Hr38 induction. Loss of Hr38 decreases ethanol tolerance and causes precocious but short-lasting ethanol preference. Similarly, reduced Mef2 activity in all neurons or specifically in the mushroom body α/β neurons decreases ethanol tolerance; Sirt1 promotes ethanol tolerance in these same neurons. Genetically decreasing Hr38 expression levels in Sirt1 null mutants restores ethanol tolerance, demonstrating that both induction and termination of Hr38 expression are important for behavioral plasticity to proceed. These data demonstrate that Hr38 functions as an immediate early transcription factor that promotes ethanol behavioral plasticity
Universal scaling in BCS superconductivity in two dimensions in non-s waves
The solutions of a renormalized BCS model are studied in two space dimensions
in , and waves for finite-range separable potentials. The gap
parameter, the critical temperature , the coherence length and the
jump in specific heat at as a function of zero-temperature condensation
energy exhibit universal scalings. In the weak-coupling limit, the present
model yields a small and large appropriate to those for high-
cuprates. The specific heat, penetration depth and thermal conductivity as a
function of temperature show universal scaling in and waves.Comment: 11 pages, LATEX, 4 postscript figures embedded using eps
Black soliton in a quasi-one-dimensional trapped fermion-fermion mixture
Employing a time-dependent mean-field-hydrodynamic model we study the
generation of black solitons in a degenerate fermion-fermion mixture in a
cigar-shaped geometry using variational and numerical solutions. The black
soliton is found to be the first stationary vibrational excitation of the
system and is considered to be a nonlinear continuation of the vibrational
excitation of the harmonic oscillator state. We illustrate the stationary
nature of the black soliton, by studying different perturbations on it after
its formation.Comment: 7 pages, 10 figure
Convergent variational calculation of positronium-hydrogen-atom scattering lengths
We present a convergent variational basis-set calculational scheme for
elastic scattering of positronium atom by hydrogen atom in S wave. Highly
correlated trial functions with appropriate symmetry are needed for achieving
convergence. We report convergent results for scattering lengths in atomic
units for both singlet () and triplet () states.Comment: 11 pages, 1 postscript figure, Accepted in J. Phys. B (Letter
Two phase transitions in (s+id)-wave Bardeen-Cooper-Schrieffer superconductivity
We establish universal behavior in temperature dependencies of some
observables in -wave BCS superconductivity in the presence of a weak
wave. There also could appear a second second-order phase transition. As
temperature is lowered past the usual critical temperature , a less
ordered superconducting phase is created in wave, which changes to a more
ordered phase in wave at (). The presence of two phase
transitions manifest in two jumps in specific heat at and . The
temperature dependencies of susceptibility, penetration depth, and thermal
conductivity also confirm the new phase transition.Comment: 6 pages, 5 post-script figures
Relativistic Effect on Low-Energy Nucleon-Deuteron Scattering
The relativistic effect on differential cross sections, nucleon-to-nucleon
and nucleon-to-deuteron polarization transfer coefficients, and the spin
correlation function, of nucleon-deuteron elastic scattering is investigated
employing several three-dimensional relativistic three-body equations and
several nucleon-nucleon potentials. The polarization transfer coefficients are
found to be sensitive to the details of the nucleon-nucleon potentials and the
relativistic dynamics employed, and prefer trinucleon models with the correct
triton binding energy. (To appear in Phys. Rev. C)Comment: pages: 21, LaTex text + 7 ps-figures at the en
Lattice Discretization in Quantum Scattering
The utility of lattice discretization technique is demonstrated for solving
nonrelativistic quantum scattering problems and specially for the treatment of
ultraviolet divergences in these problems with some potentials singular at the
origin in two and three space dimensions. This shows that lattice
discretization technique could be a useful tool for the numerical solution of
scattering problems in general. The approach is illustrated in the case of the
Dirac delta function potential.Comment: 9 page
Performance of a prototype active veto system using liquid scintillator for a dark matter search experiment
We report the performance of an active veto system using a liquid
scintillator with NaI(Tl) crystals for use in a dark matter search experiment.
When a NaI(Tl) crystal is immersed in the prototype detector, the detector tags
48% of the internal K-40 background in the 0-10 keV energy region. We also
determined the tagging efficiency for events at 6-20 keV as 26.5 +/- 1.7% of
the total events, which corresponds to 0.76 +/- 0.04 events/keV/kg/day.
According to a simulation, approximately 60% of the background events from U,
Th, and K radioisotopes in photomultiplier tubes are tagged at energies of 0-10
keV. Full shielding with a 40-cm-thick liquid scintillator can increase the
tagging efficiency for both the internal K-40 and external background to
approximately 80%.Comment: Submitted to Nuclear Instruments and Methods in Physics Research
Section
Run-and-tumble particles with hydrodynamics: sedimentation, trapping and upstream swimming
We simulate by lattice Boltzmann the nonequilibrium steady states of
run-and-tumble particles (inspired by a minimal model of bacteria), interacting
by far-field hydrodynamics, subject to confinement. Under gravity, hydrodynamic
interactions barely perturb the steady state found without them, but for
particles in a harmonic trap such a state is quite changed if the run length is
larger than the confinement length: a self-assembled pump is formed. Particles
likewise confined in a narrow channel show a generic upstream flux in
Poiseuille flow: chiral swimming is not required
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