244,200 research outputs found
The Angular Momenta of Neutron Stars and Black Holes as a Window on Supernovae
It is now clear that a subset of supernovae display evidence for jets and are
observed as gamma-ray bursts. The angular momentum distribution of massive
stellar endpoints provides a rare means of constraining the nature of the
central engine in core-collapse explosions. Unlike supermassive black holes,
the spin of stellar-mass black holes in X-ray binary systems is little affected
by accretion, and accurately reflects the spin set at birth. A modest number of
stellar-mass black hole angular momenta have now been measured using two
independent X-ray spectroscopic techniques. In contrast, rotation-powered
pulsars spin-down over time, via magnetic braking, but a modest number of natal
spin periods have now been estimated. For both canonical and extreme neutron
star parameters, statistical tests strongly suggest that the angular momentum
distributions of black holes and neutron stars are markedly different. Within
the context of prevalent models for core-collapse supernovae, the angular
momentum distributions are consistent with black holes typically being produced
in GRB-like supernovae with jets, and with neutron stars typically being
produced in supernovae with too little angular momentum to produce jets via
magnetohydrodynamic processes. It is possible that neutron stars are imbued
with high spin initially, and rapidly spun-down shortly after the supernova
event, but the available mechanisms may be inconsistent with some observed
pulsar properties.Comment: ApJ Letters, accepte
Role of IL-33 in inflammation and disease
Interleukin (IL)-33 is a new member of the IL-1 superfamily of cytokines that is expressed by mainly stromal cells, such as epithelial and endothelial cells, and its expression is upregulated following pro-inflammatory stimulation. IL-33 can function both as a traditional cytokine and as a nuclear factor regulating gene transcription. It is thought to function as an 'alarmin' released following cell necrosis to alerting the immune system to tissue damage or stress. It mediates its biological effects via interaction with the receptors ST2 (IL-1RL1) and IL-1 receptor accessory protein (IL-1RAcP), both of which are widely expressed, particularly by innate immune cells and T helper 2 (Th2) cells. IL-33 strongly induces Th2 cytokine production from these cells and can promote the pathogenesis of Th2-related disease such as asthma, atopic dermatitis and anaphylaxis. However, IL-33 has shown various protective effects in cardiovascular diseases such as atherosclerosis, obesity, type 2 diabetes and cardiac remodeling. Thus, the effects of IL-33 are either pro-or anti-inflammatory depending on the disease and the model. In this review the role of IL-33 in the inflammation of several disease pathologies will be discussed, with particular emphasis on recent advances
First Measurement Of The Jet Cross Section In Polarized p+p Collisions At GeV
We present preliminary measurements of the inclusive jet cross section in the
transverse momentum region 5<<50 GeV/\textit{c} from 0.2 of
polarized p+p data at =200 GeV. The data were corrected for detector
inefficiency and resolution using PYTHIA events processed through a full GEANT
simulation. The measured jet cross section agrees well with NLO pQCD
calculations over seven orders of magnitude. These "proof of principal"
measurements pave the way for ongoing analyses of the higher statistics (
3 ) data sample from the 2005 RHIC run.Comment: Proceedings from PANIC 200
Compact Binaries as Sources of Gravitational Radiation
With current terrestrial gravitational wave detectors working at initial
design sensitivities, and upgrades and space missions planned, it is likely
that in the next five to ten years gravitational radiation will be detected
directly from a variety of classes of objects. The most confidently expected of
these classes is compact binaries, involving neutron stars or black holes.
Detection of their coalescence, or their long-term orbits, has the potential to
inform us about the evolutionary history of compact binaries and possibly even
star formation over the past several billion years. We review what is currently
known about compact binaries as sources of gravitational radiation, as well as
the current uncertainties and what we expect to learn from future detections of
gravitational waves from these systems.Comment: To appear in the proceedings of the meeting "The Multicoloured
Landscape of Compact Objects and their Explosive Origins", Cefalu, Italy,
June 2006, to be published by AIP, Eds. L. Burderi et a
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