343 research outputs found

    Single spin asymmetry measurements for π0\pi^0 inclusive productions in p+pπ0+Xp+p_{\uparrow} \to \pi^0 + X and \pi^-+\p_{\uparrow}\to \pi^0+X reactions at 70 and 40 GeV respectively

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    The inclusive π0\pi^0 asymmetries were measured in reactions p+pπ0+Xp+p\uparrow \to \pi^0+X and π+pπ0+X\pi^-+p\uparrow \to \pi^0+X at 70 and 40 GeV/c respectively. The measurements were made at the central region (for the first reaction) and asymmetry is compatible with zero in the entire measured pTp_T region. For the second reaction the asymmetry is zero for small xFx_F region (0.4<xF<0.1,0.5<pT(GeV/c)<1.5-0.4<x_F<-0.1, 0.5<p_T(GeV/c) <1.5) and increases with growth of xF\mid x_F\mid. Averaged over the interval 0.8<xF<0.4,1<pT(GeV/c)<2-0.8<x_F<-0.4, 1<p_T(GeV/c)<2 the asymmetry was (13.8±3.8)-(13.8\pm 3.8)%.Comment: 4 pages, 2 figures; Presented at SPIN-2004 at Trieste, October 10-16,200

    Tumor suppressor function of the SEMA3B gene in human lung and renal cancers

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    The SEMA3B gene is located in the 3p21.3 LUCA region, which is frequently affected in different types of cancer. The objective of our study was to expand our knowledge of the SEMA3B gene as a tumor suppressor and the mechanisms of its inactivation. In this study, several experimental approaches were used: tumor growth analyses and apoptosis assays in vitro and in SCID mice, expression and methylation assays and other. With the use of the small cell lung cancer cell line U2020 we confirmed the function of SEMA3B as a tumor suppressor, and showed that the suppression can be realized through the induction of apoptosis and, possibly, associated with the inhibition of angiogenesis. In addition, for the first time, high methylation frequencies have been observed in both intronic (32-39%) and promoter (44-52%) CpG-islands in 38 non-small cell lung carcinomas, including 16 squamous cell carcinomas (SCC) and 22 adenocarcinomas (ADC), and in 83 clear cell renal cell carcinomas (ccRCC). Correlations between the methylation frequencies of the promoter and the intronic CpG-islands of SEMA3B with tumor stage and grade have been revealed for SCC, ADC and ccRCC. The association between the decrease of the SEMA3B mRNA level and hypermethylation of the promoter and the intronic CpG-islands has been estimated in renal primary tumors (P < 0.01). Using qPCR, we observed on the average 10- and 14-fold decrease of the SEMA3B mRNA level in SCC and ADC, respectively, and a 4-fold decrease in ccRCC. The frequency of this effect was high in both lung (92-95%) and renal (84%) tumor samples. Moreover, we showed a clear difference (P < 0.05) of the SEMA3B relative mRNA levels in ADC with and without lymph node metastases. We conclude that aberrant expression and methylation of SEMA3B could be suggested as markers of lung and renal cancer progression

    Pion-Xi correlations in Au-Au collisions at STAR

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    We present pion-Xi correlation analysis in Au-Au collisions at sqrt(s_NN)= 200 GeV and sqrt(s_NN) = 62.4 GeV, performed using the STAR detector at RHIC. A Xi*(1530) resonance signal is observed for the first time in Au-Au collisions. Experimental data are compared with theoretical predictions. The strength of the Xi* peak is reproduced in the correlation function assuming that pions and Xis emerge from a system in collective expansion.Comment: To appear in the proceedings of 18th Nuclear Physics Division Conference of the EPS (NPDC18),Prague, 23.8.-29.8. 200

    Particle-type dependence of azimuthal anisotropy and nuclear modification of particle production in Au+Au collisions at s(NN)**(1/2) = 200-GeV

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    We present STAR measurements of the azimuthal anisotropy parameter v2v_2 and the binary-collision scaled centrality ratio RCPR_{CP} for kaons and lambdas (Λ+Λˉ\Lambda+\bar{\Lambda}) at mid-rapidity in Au+Au collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV. In combination, the v2v_2 and RCPR_{CP} particle-type dependencies contradict expectations from partonic energy loss followed by standard fragmentation in vacuum. We establish pT5p_T \approx 5 GeV/c as the value where the centrality dependent baryon enhancement ends. The KS0K_S^0 and Λ+Λˉ\Lambda+\bar{\Lambda} v2v_2 values are consistent with expectations of constituent-quark-number scaling from models of hadron fromation by parton coalescence or recombination.Comment: 6 pages, 4 figures, 1 table. As published in PRL on Feb. 2, 2004; Significant revisions have been made to the text and color has been added to plot

    Correlations in STAR: interferometry and event structure

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    STAR observes a complex picture of RHIC collisions where correlation effects of different origins -- initial state geometry, semi-hard scattering, hadronization, as well as final state interactions such as quantum intensity interference -- coexist. Presenting the measurements of flow, mini-jet deformation, modified hadronization, and the Hanbury Brown and Twiss effect, we trace the history of the system from the initial to the final state. The resulting picture is discussed in the context of identifying the relevant degrees of freedom and the likely equilibration mechanism.Comment: 8 pages, 6 figures, plenary talk at the 5th International Conference on Physics and Astrophysics of Quark Gluon Plasma, to appear in Journal of Physics G (http://www.iop.org
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