6,595 research outputs found
Sterilization Assembly Development Laboratory - Monitoring plan
Monitoring plan with test requirements and procedures for sterilization assembly development laborator
Development of electrical test procedures for qualification of spacecraft against EID. Volume 2: Review and specification of test procedures
A combined experimental and analytical program to develop system electrical test procedures for the qualification of spacecraft against damage produced by space-electron-induced discharges (EID) occurring on spacecraft dielectric outer surfaces is described. A review and critical evaluation of possible approaches to qualify spacecraft against space electron-induced discharges (EID) is presented. A variety of possible schemes to simulate EID electromagnetic effects produced in spacecraft was studied. These techniques form the principal element of a provisional, recommended set of test procedures for the EID qualification spacecraft. Significant gaps in our knowledge about EID which impact the final specification of an electrical test to qualify spacecraft against EID are also identified
Model Independent Primordial Power Spectrum from Maxima, Boomerang, and DASI Data
A model-independent determination of the primordial power spectrum of matter
density fluctuations could uniquely probe physics of the very early universe,
and provide powerful constraints on inflationary models. We parametrize the
primordial power spectrum as an arbitrary function, and deduce its
binned amplitude from the cosmic microwave background radiation anisotropy
(CMB) measurements of Maxima, Boomerang, and DASI. We find that for a flat
universe with (scale-invariant) for scales h/Mpc, the
primordial power spectrum is marginally consistent with a scale-invariant
Harrison-Zeldovich spectrum. However, we deduce a rise in power compared to a
scale-invariant power spectrum for 0.001 h/{Mpc} \la k \la 0.01 h/{Mpc}. Our
results are consistent with large-scale structure data, and seem to suggest
that the current observational data allow for the possibility of unusual
physics in the very early universe.Comment: substantially revised and final version, accepted by Ap
Acute aortic dissection in a young healthy athlete with androgenic anabolic steroid use: A case report
Background: Acute aortic dissection can occur at the time of intense physical exertion in strength-trained athletes like weight lifters, bodybuilders, throwers, and wrestlers. Rapid rise in blood pressure and history of hypertension are the most common causes of aortic dissection in athletes. It is a very tragic event because of its high mortality rate of about 32% in young patients. We report a case of aortic dissection in a young weightlifter with a history of anabolic steroid usage with an extensive intimal tear of the aorta at Sino tubular junction and arch. All athletes must be assessed for predisposing factors for aortic dissection, and all patients should be encouraged to undergo appropriate diagnostic studies, like echocardiography and blood pressure monitoring while weightlifting to recognize possible predisposing factors for aortic dissection. Athletes who do have a problem should be encouraged to avoid or limit their exercise or activity by their cardiologist. It is vital that this disastrous event be prevented in young people. In conclusion, although a rare occurrence, AD should be considered in symptomatic patients with any family history of early cardiac deaths, a history suggestive of a connective tissue disorder (that is, multiple joint surgeries) or who practice weightlifting
Effects of Line-tying on Magnetohydrodynamic Instabilities and Current Sheet Formation
An overview of some recent progress on magnetohydrodynamic stability and
current sheet formation in a line-tied system is given. Key results on the
linear stability of the ideal internal kink mode and resistive tearing mode are
summarized. For nonlinear problems, a counterexample to the recent
demonstration of current sheet formation by Low \emph{et al}. [B. C. Low and
\AA. M. Janse, Astrophys. J. \textbf{696}, 821 (2009)] is presented, and the
governing equations for quasi-static evolution of a boundary driven, line-tied
magnetic field are derived. Some open questions and possible strategies to
resolve them are discussed.Comment: To appear in Phys. Plasma
Revised Relativistic Hydrodynamical Model for Neutron-Star Binaries
We report on numerical results from a revised hydrodynamic simulation of
binary neutron-star orbits near merger. We find that the correction recently
identified by Flanagan significantly reduces but does not eliminate the
neutron-star compression effect. Although results of the revised simulations
show that the compression is reduced for a given total orbital angular
momentum, the inner most stable circular orbit moves to closer separation
distances. At these closer orbits significant compression and even collapse is
still possible prior to merger for a sufficiently soft EOS. The reduced
compression in the corrected simulation is consistent with other recent studies
of rigid irrotational binaries in quasiequilibrium in which the compression
effect is observed to be small. Another significant effect of this correction
is that the derived binary orbital frequencies are now in closer agreement with
post-Newtonian expectations.Comment: Submitted to Phys. Rev.
NOD-like receptors and inflammation
The nucleotide-binding and oligomerization domain, leucine-rich repeat (also known as NOD-like receptors, both abbreviated to NLR) family of intracellular pathogen recognition receptors are increasingly being recognized to play a pivotal role in the pathogenesis of a number of rare monogenic diseases, as well as some more common polygenic conditions. Bacterial wall constituents and other cellular stressor molecules are recognized by a range of NLRs, which leads to activation of the innate immune response and upregulation of key proinflammatory pathways, such as IL-1β production and translocation of nuclear factor-κB to the nucleus. These signalling pathways are increasingly being targeted as potential sites for new therapies. This review discusses the role played by NLRs in a variety of inflammatory diseases and describes the remarkable success to date of these therapeutic agents in treating some of the disorders associated with aberrant NLR function
Halo White Dwarfs and the Hot Intergalactic Medium
We present a schematic model for the formation of baryonic galactic halos and
hot gas in the Local Group and the intergalactic medium. We follow the
dynamics, chemical evolution, heat flow and gas flows of a hierarchy of scales,
including: protogalactic clouds, galactic halos, and the Local Group itself.
Within this hierarchy, the Galaxy is built via mergers of protogalactic
fragments. We find that early bursts of star formation lead to a large
population of remnants (mostly white dwarfs), which would reside presently in
the halo and contribute to the dark component observed in the microlensing
experiments. The hot, metal-rich gas from early starbursts and merging
evaporates from the clouds and is eventually incorporated into the
intergalactic medium. The model thus suggests that most microlensing objects
could be white dwarfs (m \sim 0.5 \msol), which comprise a significant
fraction of the halo mass. Furthermore, the Local Group could have a component
of metal-rich hot gas similar to, although less than, that observed in larger
clusters. We discuss the known constraints on such a scenario and show that all
local observations can be satisfied with present data in this model. The
best-fit model has a halo that is 40% baryonic, with an upper limit of 77%.Comment: 15 pages, LaTex, uses aas2pp4.sty, 7 postscript figures.
Substantially revised and enlarged to a full-length article. Somewhat
different quantitative results, but qualitative conclusions unchange
Eigen modes for the problem of anomalous light transmission through subwavelength holes
We show that the wide-spread concept of optical eigen modes in lossless
waveguide structures, which assumes the separation on propagating and
evanescent modes, fails in the case of metal-dielectric structures, including
photonic crystals. In addition to these modes, there is a sequence of new
eigen-states with complex values of the propagation constant and non-vanishing
circulating energy flow. The whole eigen-problem ceases to be hermitian because
of changing sign of the optical dielectric constant. The new anomalous modes
are shown to be of prime importance for the description of the anomalous light
transmission through subwavelength holes.Comment: 5 pages, 4 figure
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