We report the first observations of the first harmonic (directed flow, v(1)) and the fourth harmonic (v(4)), in the azimuthal distribution of particles with respect to the reaction plane in Au+Au ...collisions at the BNL Relativistic Heavy Ion Collider (RHIC). Both measurements were done taking advantage of the large elliptic flow (v(2)) generated at RHIC. From the correlation of v(2) with v(1) it is determined that v(2) is positive, or in-plane. The integrated v(4) is about a factor of 10 smaller than v(2). For the sixth (v(6)) and eighth (v(8)) harmonics upper limits on the magnitudes are reported.
Direct-detection CMOS image sensors optimized for charged-particle imaging applications, such as electron microscopy and particle physics, have been designed, fabricated and characterized. Based on ...standard silicon CMOS active pixel sensor (APS) technology, the sensor arrays uses an 8 to 20 mum epitaxial layer that acts as a thicker sensitive region in the generation and collection of ionization electrons resulting from impinging high-energy particles. A range of optimizations to this technology have been developed via simulation and experimental device design. These include the simulation and measurement of charge collection efficiency versus recombination, effect of diode size and stray capacitance versus signal gain and noise, and the effect of different epitaxial silicon depths and the energy of incident electrons. Results from several experimental devices are presented and compared with simulations, including measurements from two prototypes that systematically and independently vary pixel pitch and diode area.
It has been shown that peripheral T cell tolerance can be induced by systemic antigen administration. We have been interested in using this phenomenon to develop antigen-specific immunotherapies for ...T cell-mediated autoimmune diseases. In patients with the demyelinating disease multiple sclerosis (MS), multiple potentially autoantigenic epitopes have been identified on the two major proteins of the myelin sheath, myelin basic protein (MBP) and proteolipid protein (PLP). To generate a tolerogenic protein for the therapy of patients with MS, we have produced a protein fusion between the 21.5-kD isoform of MBP (MBP21.5) and a genetically engineered form of PLP (deltaPLP4). In this report, we describe the effects of treatment with this agent (MP4) on clinical disease in a murine model of demyelinating disease, experimental autoimmune encephalomyelitis (EAE). Treatment of SJL/J mice with MP4 after induction of EAE either by active immunization or by adoptive transfer of activated T cells completely prevented subsequent clinical paralysis. Importantly, the administration of MP4 completely suppressed the development of EAE initiated by the cotransfer of both MBP- and PLP-activated T cells. Prevention of clinical disease after the intravenous injection of MP4 was paralleled by the formation of long-lived functional peptide-MHC complexes in vivo, as well as by a significant reduction in both MBP- and PLP-specific T cell proliferative responses. Mice treated with MP4 were resistant to disease when rechallenged with an encephalitogenic PLP peptide emulsified in CFA, indicating that MP4 administration had a prolonged effect in vivo. Administration of MP4 was also found to markedly ameliorate the course of established clinical disease. Finally, MP4 therapy was equally efficacious in mice defective in Fas expression. These results support the conclusion that MP4 protein is highly effective in suppressing disease caused by multiple neuroantigen epitopes in experimentally induced demyelinating disease.
Using reverse kinematics, we have studied the breakup of 1.0ital A GeV gold nuclei incident on a carbon target. The detector system permitted exclusive event reconstruction of nearly all charged ...reaction products. The moments of the resulting charged fragment distribution provide strong evidence that nuclear matter possesses a critical point observable in finite nuclei. We have determined values for the critical exponents gamma, beta, and tau. These values are close to those for liquid-gas systems and clearly different than those for 3D percolation and the liquid-gas mean field limit.
The activity of Src-related protein-tyrosine kinases is repressed by the phosphorylation of a conserved carboxyl-terminal tyrosine by another cytoplasmic protein-tyrosine kinase termed p50csk. In ...this study, we characterize Ntk, a protein-tyrosine kinase bearing striking similarities to p50csk. Like p50csk, Ntk possesses Src homology 3 and Src homology 2 domains and lacks the consensus tyrosine phosphorylation and myristoylation sites found in members of the Src family. Expression of ntk transcripts was maximal in brain, and was observed at significant levels in thymus and spleen. ntk RNA levels were dramatically reduced upon mitogenic stimulation of normal T lymphocytes and were minimal in transformed T-cell populations. Firm evidence that Ntk is a Csk-related enzyme was provided by the observation that it phosphorylated a Src-related polypeptide on the inhibitory carboxyl-terminal tyrosine. These findings indicate that Ntk is a Csk-related enzyme that may play an inhibitory role in the control of T-cell proliferation.
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