44,668 research outputs found
A cinematographic display of observations of low-energy proton and electron spectra in the terrestrial magnetosphere Progress report, Nov. 1967
Cinematographic display of observations of low energy proton and electron spectra in terrestrial magnetospher
Precessing Jets and Molecular Outflows: A 3-D Numerical Study
We present 3-D numerical hydrodynamical simulations of precessing supersonic
heavy jets to explore how well they serve as a model for generating molecular
outflows from Young Stellar Objects. The dynamics are studied with a number of
high resolution simulations on a Cartesian grid (128x128x128 zones) using a
high order finite difference method. A range of cone angles and precession
rates were included in the study. Two higher resolution runs (256x256x256
zones) were made for comparison in order to confirm numerical convergence of
global flow characteristics. Morphological, kinematical and dynamical
characteristics of precessing jets are described and compared to important
properties of straight jets and also to observations of YSOs. In order to
examine the robustness of precessing jets as a mean to produce molecular
outflows around Young Stellar Objects, ``synthetic observations'' of the
momentum distributions of the simulated precessing jets are compared to
observations of molecular outflows. It is found that precessing jets match
better the morphology, highly forward driven momentum and momentum
distributions along the long axis of molecular outflows than do wind-driven or
straight jet-driven flow models.Comment: Accepted by ApJ, 31 pages, using aasms.sty, Also available in
postscript with figures via a gzipped tar file at
ftp://s1.msi.umn.edu/pub/afrank/3DJet/3DJet.tar.gz . For information contact
[email protected]
Measuring Industry Specific Protection: Antidumping in the United States
This paper provides estimates of the trade impacts of U.S. antidumping law and the determinants of suit filing activity from 1980-1985. We study three possible channels through which the threat or mere possibility of antidumping duties can restrict trade which we believe, when combined with the direct effects of duties, capture most of the trade effects of antidumping law. We refer to these three non- duty effects as the investigation effect, the suspension effect, and the withdrawal effect. Investigation effects occur when an antidumping investigation takes place; suspension effects occur under so-called 'suspension agreements'; and withdrawal effects occur after a petition is simply withdrawn without a final determination. We find substantial trade restrictions associated with the first two effects, but not with the third. Finally, we find evidence suggesting that some firms initiate antidumping procedures for the trade restricting investigation effects alone.
Subluminal OPERA Neutrinos
The OPERA collaboration has announced to have observed superluminal neutrinos
with a mean energy 17.5 GeV, but afterward the superluminal interpretation of
the OPERA results has been refuted theoretically by Cherenkov-like radiation
and pion decay. In a recent work, we have proposed a kinematical resolution to
this problem. A key idea in our resolution is that the OPERA neutrinos are not
superluminal but subluminal since they travel faster than the observed speed of
light in vacuum on the earth while they do slower than the true speed of light
in vacuum determining the causal structure of events. In this article, we dwell
upon our ideas and present some concrete models, which realize our ideas, based
on spin 0, 1 and 2 bosonic fields. We also discuss that the principle of
invariant speed of light in special relativity can be replaced with the
principle of a universal limiting speed.Comment: 17 page
Multi-wavelength Observations of LS I +61 303 with VERITAS, Swift and RXT E: 2006-2008
A long term, multi-wavelength monitoring campaign on the TeV binary LS I +61
303 has been performed utilizing >300 GeV observations with VERITAS along with
monitoring in the 0.2-10 keV band by RXTE and Swift between September 2006 and
February 2008. The source was detected by VERITAS as a variable TeV source with
flux values ranging from 5-20% of the Crab Nebula flux with the strongest flux
levels appearing around apastron. X-ray observations by RXTE and Swift show the
source as a highly variable hard X-ray source with flux values varying in the
range of 0.5-3*10^-11 ergs cm^-2 s^-1 over a single orbital cycle. The
2007-2008 RXTE data set also shows the presence of several extremely large
flaring episodes presenting a flux of up to 7.2*10^-11 ergs cm^-2 s^-1, the
largest such flare recorded from this source. Comparison of the contemporaneous
TeV and X-ray data does not show a correlation at this time, however, the
sparsity of data sets do not preclude the existence of such a correlation.Comment: Submitted to Proceedings of "4th Heidelberg International Symposium
on High Energy Gamma-Ray Astronomy 2008
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