16,548 research outputs found
Picosecond excitation of jet-cooled hydrogen-bonded systems: Dispersed fluorescence and time-resolved studies of methyl salicylatea
Long progressions involving frequency intervals of 180 cm^(−1) are observed in the fluoresence of MS for 3327.5 Å excitation. (AIP
Observation of intracavity absorption of molecules in supersonic beams
Intracavity absorption studies of DMT and I2 are reported at rotational and vibrational temperatures of <0.1 K and 16 K, respectively
(2,0) theory on circle fibrations
We consider (2,0) theory on a manifold M_6 that is a fibration of a spatial
S^1 over some five-dimensional base manifold M_5. Initially, we study the free
(2,0) tensor multiplet which can be described in terms of classical equations
of motion in six dimensions. Given a metric on M_6 the low energy effective
theory obtained through dimensional reduction on the circle is a Maxwell theory
on M_5. The parameters describing the local geometry of the fibration are
interpreted respectively as the metric on M_5, a non-dynamical U(1) gauge field
and the coupling strength of the resulting low energy Maxwell theory. We derive
the general form of the action of the Maxwell theory by integrating the reduced
equations of motion, and consider the symmetries of this theory originating
from the superconformal symmetry in six dimensions. Subsequently, we consider a
non-abelian generalization of the Maxwell theory on M_5. Completing the theory
with Yukawa and phi^4 terms, and suitably modifying the supersymmetry
transformations, we obtain a supersymmetric Yang-Mills theory which includes
terms related to the geometry of the fibration.Comment: 24 pages, v2 References added, typos correcte
PATHOGENESIS OF THE GLOMERULONEPHRITIS OF NZB/W MICE
The development of glomerulonephritis in NZB/W mice is closely related to the formation of antinuclear, particularly anti-DNA, antibodies. The developing inflammatory glomerular lesions are characterized by the deposition of γG- and β1C-globulins plus DNA and possibly other nuclear antigens, presumably as complexes, in a granular to lumpy pattern along the capillary walls and in the mesangia. Elution studies revealed the γG-globulin in the glomeruli to be largely γG2A-type antibody to soluble nuclear antigens. Enhancement of the antinuclear antibody response by active immunization of young NZB/W mice with DNA-methylated BSA hastens the development and increases the severity of the glomerulonephritis. Similarly, injections of soluble DNA into NZB/W mice with circulating anti-DNA antibodies but with as yet little nephritis causes rapid progression of nephritis
Quantum limit of photothermal cooling
We study the problem of cooling a mechanical oscillator using the
photothermal (bolometric) force. Contrary to previous attempts to model this
system, we take into account the noise effects due to the granular nature of
photon absorption. This allows us to tackle the cooling problem down to the
noise dominated regime and to find reasonable estimates for the lowest
achievable phonon occupation in the cantilever
Suppression of Giant Magnetoresistance by a superconducting contact
We predict that current perpendicular to the plane (CPP) giant
magnetoresistance (GMR) in a phase-coherent magnetic multilayer is suppressed
when one of the contacts is superconducting. This is a consequence of a
superconductivity-induced magneto-resistive (SMR) effect, whereby the
conductance of the ferromagnetically aligned state is drastically reduced by
superconductivity. To demonstrate this effect, we compute the GMR ratio of
clean (Cu/Co)_nCu and (Cu/Co)_nPb multilayers, described by an ab-initio spd
tight binding Hamiltonian. By analyzing a simpler model with two orbitals per
site, we also show that the suppression survives in the presence of elastic
scattering by impurities.Comment: 5 pages, 4 figures. Submitted to PR
Gravity tests with INPOP planetary ephemerides
In this paper, we present several gravity tests made in using the last
INPOP08 planetary ephemerides. We first propose two methods to estimate the PPN
parameter and its correlated value, the Sun J2 and we discuss the
correlation between the Sun J2 and the mass of the asteroid ring. We estimate
possible advance in the planet perihelia. In the end we show that no constant
acceleration larger than 1/4 the Pioneer anomaly can affect the planets of our
solar system.Comment: 11 pages. submitted to proceedings of IAU symposium 264 "Relativity
in Fundamental Astronomy: Dynamics, Reference Frames and Data analysis
Spectral geometry, homogeneous spaces, and differential forms with finite Fourier series
Let G be a compact Lie group acting transitively on Riemannian manifolds M
and N. Let p be a G equivariant Riemannian submersion from M to N. We show that
a smooth differential form on N has finite Fourier series if and only if the
pull back has finite Fourier series on
Superconducting Proximity Effect and Universal Conductance Fluctuations
We examine universal conductance fluctuations (UCFs) in mesoscopic
normal-superconducting-normal (N-S-N) structures using a numerical solution of
the Bogoliubov - de Gennes equation. We discuss two cases depending on the
presence (``open'' structure) or absence (``closed'' structure) of
quasiparticle transmission. In contrast to N-S structures, where the onset of
superconductivity increases fluctuations, we find that UCFs are suppressed by
superconductivity for N-S-N structures. We demonstrate that the fluctuations in
``open'' and ``closed'' structures exhibit distinct responses to an applied
magnetic field and to an imposed phase variation of the superconducting order
parameter.Comment: (4 pages, 5 figures). Corrected typos in equations, added references,
changed Fig. 5 and its discussions. Phys. Rev. B, accepted for publicatio
A Hartree-Fock Study of Persistent Currents in Disordered Rings
For a system of spinless fermions in a disordered mesoscopic ring,
interactions can give rise to an enhancement of the persistent current by
orders of magnitude. The increase in the current is associated with a charge
reorganization of the ground state. The interaction strength for which this
reorganization takes place is sample-dependent and the log-averages over the
ensemble are not representative. In this paper we demonstrate that the
Hartree-Fock method closely reproduces results obtained by exact
diagonalization. For spinless fermions subject to a short-range Coulomb
repulsion U we show that due to charge reorganization the derivative of the
persistent current is a discontinuous function of U. Having established that
the Hartree-Fock method works well in one dimension, we present corresponding
results for persistent currents in two coupled chains.Comment: 4 pages, 6 figures, Submitted to Phys. Rev.
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