82,090 research outputs found
SeaSat-A Satellite Scatterometer Mission Summary and Engineering Assessment Report
The SeaSat-A satellite was launched on June 26, 1978 and operated in orbit through October 9, 1978. The SeaSat-A satellite scatterometer ocean surface wind field sensor began taking data on July 10, 1978 with virtually continuous operation for 95-1/2 days. A review of mission events significant to the scatterometer and a report on the hardware and software engineering assessment are presented
Health Transfers: An Application of Health-Health Analysis to Assess Food Safety Regulations
The authors apply a Health-Health Analysis to risks associated with harvesting Gulf oysters to evaluate that approach to managing health and safety risks
Effect of external conditions on the structure of scrolled graphene edges
Characteristic dimensions of carbon nanoscrolls - "buckyrolls" - are
calculated by analyzing the competition between elastic, van der Waals, and
electrostatic energies for representative models of suspended and
substrate-deposited graphene samples. The results are consistent with both
atomistic simulations and experimental observations of scrolled graphene edges.
Electrostatic control of the wrapping is shown to be practically feasible and
its possible device applications are indicated.Comment: 4 pages, 3 figure
Soluble Fermentable Dietary Fibre (Pectin) Decreases Caloric Intake, Adiposity and Lipidaemia in High-Fat Diet-Induced Obese Rats
Funding: This work was funded by the Scottish Government Rural and Environment Science and Analytical Services Division. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD
Evidence for Differential Rotation on a T Tauri Star
Five years of photometric monitoring of the T Tauri star HBC 338 in NGC 1333
has revealed that it is a periodic variable, but the period has changed
significantly with time. From 2000-2003, a period near 5.6 days was observed,
while in the last two seasons, the dominant period is near 4.6 days. No other T
Tauri star has been seen to change its period by such a large percentage. We
propose a model in which a differentially rotating star is seen nearly
equator-on and a high latitude spot has gradually been replaced by a low
latitude spot. We show that this model provides an excellent fit to the
observed shapes of the light curves at each epoch. The amplitude and sense of
the inferred differential rotation is similar to what is seen on the Sun. This
may be surprising given the likely high degree of magnetic surface activity on
the star relative to the Sun but we note that HBC 338 is clearly an exceptional
T Tauri star.Comment: Acepted for publication in PAS
The ground state of a spin-1/2 neutral particle with anomalous magnetic moment in a Aharonov-Casher configuration
We determine the (bound) ground state of a spin 1/2 chargless particle with
anomalous magnetic moment in certain Aharonov-Casher configurations. We recast
the description of the system in a supersymmetric form. Then the basic physical
requirements for unbroken supersymmetry are established. We comment on the
possibility of neutron trapping in these systems
Jet-cloud interations and the brightening of the narrow line region in Seyfert galaxies
We study the kinematical and brightness evolution of emission line clouds in
the narrow line region (NLR) of Seyfert galaxies during the passage of a jet.
We derive a critical density above which a cloud remains radiative after
compression by the jet cocoon. The critical density depends mainly on the
cocoon pressure. Super-critical clouds increase in emission line brightness,
while sub-critical clouds generally are highly overheated reducing their
luminosity below that of the inter-cloud medium. Due to the pressure
stratification in the bow-shock of the jet, a cylindrical structure of nested
shells develops around the jet. The most compact and brightest compressed
clouds surround the cloud-free channel of the radio jet. To support our
analytical model we present a numerical simulation of a supersonic jet
propagating into a clumpy NLR. The position-velocity diagram of the simulated
H_alpha emission shows total line widths of the order of 500 km/s with
large-scale variations in the radial velocities of the clouds due to the
stratified pressure in the bow-shock region of the jet. Most of the luminosity
is concentrated in a few dense clouds surrounding the jet. These morphological
and kinematic signatures are all found in the well observed NLR of NGC1068 and
other Seyfert galaxies.Comment: 11 pages, 3 figures, accepted for publication in The Astrophysical
Journal Letter
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