ELEVATED SERUM LEVELS OF TNF SOLUBLE RECEPTORS IN PATIENTS WITH POSITIVE ANTI-NEUTROPHIL CYTOPLASMIC ANTIBODIES

ANCA are found in various systemic vasculitis and are supposed to play a role in the pathogenesis of the disease, in cooperation with other factors such as cytokines. A total of 36 ANCA-positive and 10 ANCA-negative serum samples were analysed for the presence of TNF soluble receptors (TNF-sR), which are shed from the surface of activated cells and may act as TNF inhibitors. Of the ANCA-positive samples, 67% had elevated TNF-sR75 and 72% had elevated TNF-sR55 compared to ANCA-negative specimens (mean [S.E.] 18.7 [17.3] vs 3.6 [1.5] and 10.5 [9.7] vs 1.9 [0.7] ng/ml, P<0.01). Elevation of TNF-sR in patients with ANCA suggests that cytokines and their inhibitors are involved in the pathogenesis of ANCA-associated autoimmune disease

Spontaneous arterial thrombosis in a patient with human immunodeficiency virus infection: Successful treatment with pharmacomechanical thrombectomy

AbstractPatients with human immunodeficiency virus (HIV) have various coagulation abnormalities as well as increased risk for development of clinical thrombosis and subsequent embolic events. We report acute lower leg ischemia caused by spontaneous atheroembolism with no identifiable source in a young patient with HIV infection. Treatment included percutaneous mechanical thrombectomy and thrombolysis, which reversed the arterial ischemia. Physicians should be aware of thromboembolic disease as a possible complication of HIV

Impurity center in a semiconductor quantum ring in the presence of a radial electric field

The problem of an impurity electron in a quantum ring (QR) in the presence of a radially directed strong external electric field is investigated in detail. Both an analytical and a numerical approach to the problem are developed. The analytical investigation focuses on the regime of a strong wire-electric field compared to the electric field due to the impurity. An adiabatic and quasiclassical approximation is employed. The explicit dependencies of the binding energy of the impurity electron on the electric field strength, parameters of the QR and position of the impurity within the QR are obtained. Numerical calculations of the binding energy based on a finite-difference method in two and three dimensions are performed for arbitrary strengths of the electric field. It is shown that the binding energy of the impurity electron exhibits a maximum as a function of the radial position of the impurity that can be shifted arbitrarily by applying a corresponding wire-electric field. The maximal binding energy monotonically increases with increasing electric field strength. The inversion effect of the electric field is found to occur. An increase of the longitudinal displacement of the impurity typically leads to a decrease of the binding energy. Results for both low- and high-quantum rings are derived and discussed. Suggestions for an experimentally accessible set-up associated with the GaAs/GaAlAs QR are provided.Comment: 16 pages, 8 figure

Note on Global Regularity for 2D Oldroyd-B Fluids with Diffusive Stress

We prove global regularity of solutions of Oldroyd-B equations in 2 spatial dimensions with spatial diffusion of the polymeric stresses

Hole Localization in Underdoped Superconducting Cuprates Near 1/8th Doping

Measurements of thermal conductivity versus temperature over a broad range of doping in YBa$_2$Cu$_3$O$_{6+x}$ and HgBa$_2$Ca$_{n-1}$Cu$_n$O$_{2n+2+\delta}$ ($n$=1,2,3) suggest that small domains of localized holes develop for hole concentrations near $p$=1/8. The data imply a mechanism for localization that is intrinsic to the CuO$_2$-planes and is enhanced via pinning associated with oxygen-vacancy clusters.Comment: 4 pages, 4 eps fig.'s, to be published, Phys. Rev.

The Internal Structural Adjustment due to Tidal Heating of Short-Period Inflated Giant Planets

Several short-period Jupiter-mass planets have been discovered around nearby solar-type stars. During the circularization of their orbits, the dissipation of tidal disturbance by their host stars heats the interior and inflates the sizes of these planets. Based on a series of internal structure calculations for giant planets, we examine the physical processes which determine their luminosity-radius relation. In order for young or intensely heated gas giant planets to attain quasi-hydrostatic equilibria, with sizes comparable to or larger than two Jupiter radii, their interiors must have sufficiently high temperature and low density such that degeneracy effects are relatively weak compared to those in a mature and compact Jupiter. Consequently, the polytropic index monotonically increases whereas the central temperature increases and then decreases with the planets' size. These effects, along with a temperature-sensitive opacity for the radiative surface layers of giant planets, cause the power index of the luminosity's dependence on radius to decrease with increasing radius. For planets larger than twice Jupiter's radius, this index is sufficiently small that they become unstable to tidal inflation. We make comparisons between cases of uniform heating and cases in which the heating is concentrated in various locations within the giant planet. Based on these results we suggest that accurate measurement of the sizes of close-in young Jupiters can be used to probe their internal structure under the influence of tidal heating.Comment: 39 pages, 12 figures, 2 tables. Accepted for publication in Ap

Supernova Enrichment of Dwarf Spheroidal Galaxies

(Abridged) Many dwarf galaxies exhibit sub-Solar metallicities, with some star-to-star variation, despite often containing multiple generations of stars. The total metal content in these systems is much less than expected from the heavy element production of massive stars in each episode of star formation. Such a deficiency implies that a substantial fraction of the enriched material has been lost from these small galaxies. Mass ejection from dwarf galaxies may have important consequences for the evolution of the intergalactic medium and for the evolution of massive galaxies, which themselves may have formed via the merger of smaller systems. We report here the results of three-dimensional simulations of the evolution of supernova-enriched gas within dwarf spheroidal galaxies (dSph's), with the aim of determining the retention efficiency of supernova ejecta. We consider two galaxy models, selected to represent opposite ends of the dSph sequence. For each model galaxy we investigate a number of scenarios, ranging from a single supernova in smooth gas distributions to more complex multiple supernovae in highly disturbed gas distributions. The results of these investigations suggest that, for low star-formation efficiencies, it is difficult to completely expel the enriched material from the galaxy. Most of the enriched gas is, however, lost from the core of the galaxy following multiple supernovae, especially if the interstellar medium is already highly disturbed by processes such as photo-ionization and stellar winds. If subsequent star formation occurs predominantly within the core where most of the residual gas is concentrated, then these results could explain the poor self-enrichment efficiency observed in dwarf galaxies.Comment: 29 pages, 10 figures, to appear in Astrophysical Journa

The Landscape of Particle Production: Results from PHOBOS

Recent results from the PHOBOS experiment at RHIC are presented, both from Au+Au collisions from the 2001 run and p+p and d+Au collisions from 2003. The centrality dependence of the total charged particle multiplicity in p+p and d+Au show features, such as Npart-scaling and limiting fragmentation, similar to p+A collisions at lower energies. Multiparticle physics in Au+Au is found to be local in (pseudo)rapidity, both when observed by HBT correlations and by forward-backward pseudorapidity correlations. The shape of elliptic flow in Au+Au, measured over the full range of pseudorapidity, appears to have a very weak centrality dependence. Identified particle ratios in d+Au reactions show little difference between the shape of proton and anti-proton spectra, while the absolute yields show an approximate m_T scaling.Comment: 8 Pages, 11 Figures, Plenary talk at Quark Matter 2004, Oakland, CA, January 11-18, 200

A Two Micron All-Sky Survey View of the Sagittarius Dwarf Galaxy: II. Swope Telescope Spectroscopy of M Giant Stars in the Dynamically Cold Sagittarius Tidal Stream

We present moderate resolution (~6 km/s) spectroscopy of 284 M giant candidates selected from the Two Micron All Sky Survey photometry. Radial velocities (RVs) are presented for stars mainly in the south, with a number having positions consistent with association to the trailing tidal tail of the Sagittarius (Sgr) dwarf galaxy. The latter show a clear RV trend with orbital longitude, as expected from models of the orbit and destruction of Sgr. A minimum 8 kpc width of the trailing stream about the Sgr orbital midplane is implied by verified RV members. The coldness of this stream (dispersion ~10 km/s) provides upper limits on the combined contributions of stream heating by a lumpy Galactic halo and the intrinsic dispersion of released stars, which is a function of the Sgr core mass. The Sgr trailing arm is consistent with a Galactic halo containing one dominant, LMC-like lump, however some lumpier halos are not ruled out. An upper limit to the total M/L of the Sgr core is 21 in solar units. A second structure that roughly mimics expectations for wrapped, leading Sgr arm debris crosses the trailing arm in the Southern Hemisphere; however, this may also be an unrelated tidal feature. Among the <13 kpc M giants toward the South Galactic Pole are some with large RVs that identify them as halo stars, perhaps part of the Sgr leading arm near the Sun. The positions and RVs of Southern Hemisphere M giants are compared with those of southern globular clusters potentially stripped from the Sgr system and support for association of Pal 2 and Pal 12 with Sgr debris is found. Our discussion includes description of a masked-filtered cross-correlation methodology that achieves better than 1/20 of a resolution element RVs in moderate resolution spectra.Comment: 41 pages, 6 figures, Astronomical Journal, in press (submitted Nov. 24, 2003; tentatively scheduled for July 2004 issue