Leptonic and charged kaon decay modes of the phi meson measured in heavy-ion collisions at the CERN super proton synchrotron.

We report on results of a measurement of meson production in central Pb-Au collisions at E(lab) = 158A GeV. For the first time in the history of high energy heavy-ion collisions, phi mesons were reconstructed both in the K+K- and the dilepton decay channels in the same experiment. This measurement yields rapidity densities near midrapidity, from the two decay channels, of 2.05 +/- 0.14(stat) +/- 0.25(syst) and 2.04 +/- 0.49(stat) +/- 0.32(syst), respectively. The shape of the measured transverse momentum spectrum is also in close agreement in both decay channels. The data rule out a possible enhancement of the phi yield in the leptonic over the hadronic decay channel of a factor 1.6 or larger at the 95% C.L. This rules out the discrepancy reported in the literature between measurements of the hadronic and dimuon decay channels by two different experiments.

Semihard scattering unraveled from collective dynamics by two-pion azimuthal correlations in 158A GeV/c Pb+Au collisions.

Elliptic flow and two-particle azimuthal correlations of charged hadrons and high-p(T) pions (p(T)>1 GeV/c) have been measured close to midrapidity in 158A GeV/c Pb+Au collisions by the CERES experiment. Elliptic flow (v(2)) rises linearly with p(T) to a value of about 10% at 2 GeV/c. Beyond p(T) approximately 1.5 GeV/c, the slope decreases considerably, possibly indicating a saturation of v(2) at high p(T). Two-pion azimuthal anisotropies for p(T)>1.2 GeV/c exceed the elliptic flow values by about 60% in midcentral collisions. These nonflow contributions are attributed to nearside and back-to-back jetlike correlations, the latter exhibiting centrality dependent broadening.

Enhanced production of low-mass electron-positron pairs in 40-AGeV Pb-Au collisions at the CERN SPS.

We report on first measurements of low-mass electron-positron pairs in Pb-Au collisions at the CERN SPS beam energy of 40 AGeV. The observed pair yield integrated over the range of invariant masses 0.2e(+)e(-) annihilation with a modified rho propagator. They may be linked to chiral symmetry restoration and support the notion that the in-medium modifications of the rho are more driven by baryon density than by temperature.

Universal pion freeze-out in heavy-ion collisions.

Based on an evaluation of data on pion interferometry and on particle yields at midrapidity, we propose a universal condition for thermal freeze-out of pions in heavy-ion collisions. We show that freeze-out occurs when the mean free path of pions lambda(f) reaches a value of about 1 fm, which is much smaller than the spatial extent of the system at freeze-out. This critical mean free path is independent of the centrality of the collision and beam energy from the Alternating Gradient Synchrotron to the Relativistic Heavy Ion Collider.

Widespread occurrence of anti-troponin T crossreactive components in non-muscle cells.

Using a monoclonal antibody generated against striated muscle troponin T, we previously noted the presence of crossreactive components in smooth muscle and non-muscle cells. Since the presence of troponin T in tissues other than striated muscle is controversial, we sought to establish the nature of the crossreaction and to determine the extent of its occurrence. For this study, indirect immunofluorescence microscopy and immunoblot analyses were performed. Crossreactive material was found in diverse cells from the animal, plant and fungal kingdoms. On the basis of morphological distributions, both microtubule-associated and non-microtubule-associated components were revealed. Microtubule-associated components of animal cell lines included a 35 X 10(3) Mr protein, similar in electrophoretic mobility to skeletal troponin T (37 X 10(3) Mr). Reactive components of comparable mobility were observed in immunoblots of brain and cerebellar homogenates. Filamentous staining was observed in a variety of mammalian cells in culture and in cells of vertebrate tissues. Chick cerebellar tissue showed reactions in the neurites of the molecular layer and granule cell bodies. In the plant kingdom, examination of the onion root-tip cells indicated an association of crossreactive components with interphase cortical microtubules, preprophase bands, the mitotic spindle and phragmoplast microtubules. In the fungal kingdom, both interphase and mitotic spindle microtubules in a cellular slime mould were reactive. Non-microtubule-associated components were observed in the centrosphere regions of mitotic sea-urchin eggs, in mitotic and interphase plasmodia of Physarum polycephalum, and in trichocysts and basal bodies of Paramecium tetraurelia. In all systems examined, the troponin T crossreactive components were located in regions or on structures of possible Ca2+ or calmodulin activity, suggesting a possible functional similarity to troponin T.

A monoclonal antitroponin-T cross-reacts with smooth muscle and nonmuscle cells.

A mouse monoclonal antibody was prepared against chicken skeletal troponin-T. Indirect immunofluorescence microscopy of smooth muscle and nonmuscle cells indicated the presence of a cross-reactive component(s). In contrast to the definitive I-band reactivity in striated muscle, the smooth muscle components from chicken gizzard, lung, and small intestine showed diffuse, cytoplasmic staining. A filamentous pattern which converged on a perinuclear focus was observed in interphase cells (356 fibroblasts). This cross-reaction was determined to be associated with microtubules. To assess the extent of occurrence of the cross-reactive species, representatives of both the fungal and plant kingdoms were examined. In both Dictyostelium discoideum and cells of the onion (Allium) root tip, the antitroponin-T detected cross-reactive components associated with microtubules. Immunoblot experiments conducted to determine the molecular specificity of the antibody showed cross-reaction with only troponin-T in striated muscle preparations. Similar experiments with the antitroponin-T on chicken gizzard smooth muscle indicated reactivity with two bands whose electrophoretic mobilities are within the range reported for striated muscle troponin-T. Our results indicate the presence of a highly conserved troponin-T cross-reactive determinant in all muscle types, as well as nonmuscle cells. They raise the possibility of a troponin-like molecule in smooth muscle and nonmuscle cells which may confer calcium sensitivity in their cellular filament systems.