3,923 research outputs found
A study of longitudinal oscillations of propellant tanks and wave propagations in feed lines. Part V - Longitudinal oscillation of a propellant-filled flexible oblate spheroidal tank
Analytical method for determining axisymmetric longitudinal mode shapes and frequencies of incompressible and inviscid fluid in pressurized flexible oblate spheroidal propellant tan
Force measurements of a superconducting-film actuator for a cryogenic interferometric gravitational-wave detector
We measured forces applied by an actuator with a YBCO film at near 77 K for
the Large-scale Cryogenic Gravitational-wave Telescope (LCGT) project. An
actuator consisting of both a YBCO film of 1.6 micrometers thickness and 0.81
square centimeters area and a solenoid coil exerted a force of up to 0.2 mN on
a test mass. The presented actuator system can be used to displace the mirror
of LCGT for fringe lock of the interferometer.Comment: 9 pages, 3 figure
Crystals for Demazure Modules of Classical Affine Lie Algebras
We study, in the path realization, crystals for Demazure modules of affine
Lie algebras of types . We find a special sequence of
affine Weyl group elements for the selected perfect crystal, and show if the
highest weight is l\La_0, the Demazure crystal has a remarkably simple
structure.Comment: Latex, 28 page
Ab initio study of reflectance anisotropy spectra of a sub-monolayer oxidized Si(100) surface
The effects of oxygen adsorption on the reflectance anisotropy spectrum (RAS)
of reconstructed Si(100):O surfaces at sub-monolayer coverage (first stages of
oxidation) have been studied by an ab initio DFT-LDA scheme within a
plane-wave, norm-conserving pseudopotential approach. Dangling bonds and the
main features of the characteristic RAS of the clean Si(100) surface are mostly
preserved after oxidation of 50% of the surface dimers, with some visible
changes: a small red shift of the first peak, and the appearance of a distinct
spectral structure at about 1.5 eV. The electronic transitions involved in the
latter have been analyzed through state-by-state and layer-by-layer
decompositions of the RAS. We suggest that new interplay between present
theoretical results and reflectance anisotropy spectroscopy experiments could
lead to further clarification of structural and kinetic details of the Si(100)
oxidation process in the sub-monolayer range.Comment: 21 pages, 8 figures. To be published in Physical Rev.
Spitzer IRAC Imaging of the Relativistic Jet from Superluminal Quasar PKS 0637-752
Emission from the relativistic jet located at hundreds of kpc from the core
of the superluminal quasar PKS 0637-752 was detected at 3.6 and 5.8 microns
with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. The
unprecedented sensitivity and arcsecond resolution of IRAC allows us to explore
the mid-infrared emission from kiloparsec-scale quasar jets for the first time.
The mid-infrared flux from the jet knots, when combined with radio and optical
fluxes, confirms a synchrotron origin of the radio-to-optical emission and
constrains very well the high energy end of the nonthermal electron
distribution. Assuming the X-rays are produced in the relativistically moving
knots via inverse Compton scattering of cosmic microwave background (CMB)
radiation, the infrared observation puts constraints on the matter content of
the quasar extended jet. Specifically, pure electron-positoron pair jet models
are unfavorable based on the lack of an infrared bump associated with ``bulk
Comptonization'' of CMB photons by an ultrarelativistic jet.Comment: 4 pages, 3 figures; accepted for publication in ApJ Letter
Pulse Control of Decoherence in a Qubit Coupled with a Quantum Environment
We study the time evolution of a qubit linearly coupled with a quantum
environment under a sequence of short pi pulses. Our attention is focused on
the case where qubit-environment interactions induce the decoherence with
population decay. We assume that the environment consists of a set of bosonic
excitations. The time evolution of the reduced density matrix for the qubit is
calculated in the presence of periodic short pi pulses. We confirm that the
decoherence is suppressed if the pulse interval is shorter than the correlation
time for qubit-environment interactions.Comment: 5 pages, 2figure
An Infrared Study of the Large-scale Jet in Quasar PKS 1136-135
We present Spitzer IRAC imaging of the large-scale jet in the quasar PKS
1136-135 at wavelengths of 3.6 and 5.8 um, combined with previous VLA, HST, and
Chandra observations. We clearly detect infrared emission from the jet,
resulting in the most detailed multifrequency data among the jets in
lobe-dominated quasars. The spectral energy distributions of the jet knots have
significant variations along the jet, like the archetypal jet in 3C 273. The
infrared measurements with IRAC are consistent with the previous idea that the
jet has two spectral components, namely (1) the low-energy synchrotron spectrum
extending from radio to infrared, and (2) the high-energy component responsible
for the X-ray flux. The optical fluxes may be a mixture of the two components.
We consider three radiation models for the high-energy component: inverse
Compton scattering off CMB photons by radio-emitting electrons in a highly
relativistic jet, synchrotron radiation by a second distinct electron
population, and synchrotron radiation by ultra high energy protons. Each
hypothesis leads to important insights into and constraints on particle
acceleration in the jet, as well as the basic physical properties of the jet
such as bulk velocity, transporting power, and particle contents.Comment: 9 pages, 5 figures (2 color figures), accepted for publication in
ApJ; one typo in Table 1 is correcte
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