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Interferon gamma regulates platelet endothelial cell adhesion molecule 1 expression and neutrophil infiltration into herpes simplex virus-infected mouse corneas.
In a mouse model of herpes simplex virus (HSV) 1 corneal infection, tissue destruction results from a CD4+ T cell-mediated chronic inflammation, in which interleukin 2 and interferon (IFN) gamma are requisite inflammatory mediators and polymorphonuclear leukocytes (PMN) are the predominant infiltrating cells. In vivo neutralization of IFN-gamma relieved inflammation at least in part through a specific block of PMN extravasation into HSV-1-infected corneas. Intercellular adhesion molecule (ICAM) 1 and platelet endothelial cell adhesion molecule (PECAM) 1 were upregulated on the vascular endothelium of inflamed corneas. Reduced PMN extravasation in anti-IFN-gamma-treated mice was associated with a dramatic reduction of PECAM-1 but not ICAM-1 expression on vascular endothelium. PMN accumulated in the lumen of corneal vessels after in vivo IFN-gamma neutralization. PECAM-1 was readily detectable on PMN inside the vessels but was not detectable on PMN that extravasated into the infected cornea. Moreover, flow cytometric analysis revealed reduced PECAM-1 expression but elevated major histocompatibility complex class I expression on PMN that recently extravasated into the peritoneal cavity when compared with PMN in the peripheral blood. We conclude that IFN-gamma contributes to HSV-1-induced corneal inflammation by facilitating PMN infiltration; this appears to be accomplished through upregulation of PECAM-1 expression on the vascular endothelium; and PMN downregulate PECAM-1 expression during the process of extravasation
Supernova Blastwaves in Low-density Hot Media: a Mechanism for Spatially Distributed Heating
Most supernovae are expected to explode in low-density hot media,
particularly in galactic bulges and elliptical galaxies. The remnants of such
supernovae, though difficult to detect individually, can be profoundly
important in heating the media on large scales. We characterize the evolution
of this kind of supernova remnants, based on analytical approximations and
hydrodynamic simulations. We generalize the standard Sedov solution to account
for both temperature and density effects of the ambient media. Although cooling
can be neglected, the expansion of such a remnant deviates quickly from the
standard Sedov solution and asymptotically approaches the ambient sound speed
as the swept-up thermal energy becomes important. The relatively steady and
fast expansion of the remnants over large volumes provides an ideal mechanism
for spatially distributed heating, which may help to alleviate the over-cooling
problem of hot gas in groups and clusters of galaxies as well as in galaxies
themselves. The simulations were performed with the FLASH code.Comment: 12 pages, 3 figures, 1 table, accepted for ApJ, uses aaste
A long-lived spin-orbit-coupled degenerate dipolar Fermi gas
We describe the creation of a long-lived spin-orbit-coupled gas of quantum
degenerate atoms using the most magnetic fermionic element, dysprosium.
Spin-orbit-coupling arises from a synthetic gauge field created by the
adiabatic following of degenerate dressed states comprised of optically coupled
components of an atomic spin. Because of dysprosium's large electronic orbital
angular momentum and large magnetic moment, the lifetime of the gas is limited
not by spontaneous emission from the light-matter coupling, as for gases of
alkali-metal atoms, but by dipolar relaxation of the spin. This relaxation is
suppressed at large magnetic fields due to Fermi statistics. We observe
lifetimes up to 400 ms, which exceeds that of spin-orbit-coupled fermionic
alkali atoms by a factor of 10-100, and is close to the value obtained from a
theoretical model. Elastic dipolar interactions are also observed to influence
the Rabi evolution of the spin, revealing an interacting fermionic system. The
long lifetime of this weakly interacting spin-orbit-coupled degenerate Fermi
gas will facilitate the study of quantum many-body phenomena manifest at longer
timescales, with exciting implications for the exploration of exotic
topological quantum liquids.Comment: 11 pages, 8 figures, one appendi
Scalability of Hydrodynamic Simulations
Many hydrodynamic processes can be studied in a way that is scalable over a
vastly relevant physical parameter space. We systematically examine this
scalability, which has so far only briefly discussed in astrophysical
literature. We show how the scalability is limited by various constraints
imposed by physical processes and initial conditions. Using supernova remnants
in different environments and evolutionary phases as application examples, we
demonstrate the use of the scaling as a powerful tool to explore the
interdependence among relevant parameters, based on a minimum set of
simulations. In particular, we devise a scaling scheme that can be used to
adaptively generate numerous seed remnants and plant them into 3D hydrodynamic
simulations of the supernova-dominated interstellar medium.Comment: 12 pages, 1 figure, submitted to MNRAS; comments are welcom
A unified approach to generate risk measures.
Markov inequality; Premium; Premium principle; Principles; Probability; Recall; Risk; Risk measure;
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