We propose Elliptic Power and Power parameterizations for the probability distribution of initial state anisotropies in heavy-ion collisions. By assuming a linear eccentricity scaling, the new ...parameterizations can also be applied to fluctuations of harmonic flow. In particular, the recently measured flow multiparticle cumulants and event-by-event distributions are analyzed.
The contribution of B meson decays to nonphotonic electrons, which are mainly produced by the semileptonic decays of heavy-flavor mesons, in p+p collisions at {radical}(s)=200 GeV has been measured ...using azimuthal correlations between nonphotonic electrons and hadrons. The extracted B decay contribution is approximately 50% at a transverse momentum of p{sub T{>=}}5 GeV/c. These measurements constrain the nuclear modification factor for electrons from B and D meson decays. The result indicates that B meson production in heavy ion collisions is also suppressed at high p{sub T}.
The reactions Ca + Ca and Nb + Nb at 400 MeV/nucleon have been studied at the Bevalac using the 'Plastic Ball' spectrometer. A global analysis of the events shows two nontrivial collective flow ...effects: the bounceoff of the projectile fragments, and the side-splash of the intermediate-rapidity fragments for the higher-multiplicity Nb + Nb events. Neither effect is seen in a knockon cascade calculation. A simulation with an event-generating statistical model has been done in order to extract the magnitudes of the effects.
Directed and elliptic flow are reported for charged pions and protons as a function of transverse momentum, rapidity, and centrality in 40 and 158 AGeV Pb + Pb collisions. The standard method of ...correlating particles with an event plane is used. The directed flow of protons is small and shows little variation near to midrapidity, but rises fast towards projectile rapidity in the 40 AGeV data. For most peripheral collisions the flat region becomes negative resulting in
ν
1 changing sign three times. Elliptic flow doesn't seem to change very much from 40 AGeV to 158 AGeV. The difference is smaller than anticipated from the overall energy dependence from AGS to RHIC.
Classic cadherins are synaptic adhesion proteins that have been implicated in synapse formation and targeting. Brief inactivation of classic cadherin function in young neurons appears to abrogate ...synapse formation when examined acutely. It remains unknown if such abrogation is unique to young neurons, whether it occurs by stalling neuronal maturation or by directly interfering with the process of synapse assembly, or whether synapse targeting is altered. Here we asked if sustained pan-cadherin blockade would prevent or alter the progression of axonal and dendritic outgrowth, synaptogenesis, or the stereotypic distribution of excitatory and inhibitory synapses on cultured hippocampal neurons. While pre- and postsynaptic cadherins are required for synapse assembly in young neurons, we find that in neurons older than 10 days, classic cadherins are entirely dispensable for joining and aligning presynaptic vesicle clusters with molecular markers of the postsynaptic density. Furthermore, we find that the proportion and relative distributions of excitatory and inhibitory terminals on single neurons are not altered. However, synapses that form on neurons in which cadherin function is blocked are smaller; they exhibit decreased synaptic vesicle recycling and a decreased frequency of spontaneous EPSCs. Moreover, they fail to acquire resistance to F-actin depolymerization, a hallmark of mature, stable contacts. These data provide new evidence that cadherins are required to promote synapse stabilization and structural and functional maturation, but dispensable for the correct subcellular distribution of excitatory and inhibitory synapses.
The transverse momentum and rapidity distributions of net protons and negatively charged hadrons have been measured for minimum bias proton–nucleus and deuteron–gold interactions, as well as central ...oxygen–gold and sulphur–nucleus collisions at 200 GeV per nucleon. The rapidity density of net protons at midrapidity in central nucleus–nucleus collisions increases both with target mass for sulphur projectiles and with the projectile mass for a gold target. The shape of the rapidity distributions of net protons forward of midrapidity for d+Au and central S+Au collisions is similar. The average rapidity loss is larger than 2 units of rapidity for reactions with the gold target. The transverse momentum spectra of net protons for all reactions can be described by a thermal distribution with ‘temperatures’ between 145 ± 11 MeV (p+S interactions) and 244 ± 43 MeV (central S+Au collisions). The multiplicity of negatively charged hadrons increases with the mass of the colliding system. The shape of the transverse momentum spectra of negatively charged hadrons changes from minimum bias p+p and p+S interactions to p+Au and central nucleus-nucleus collisions. The mean transverse momentum is almost constant in the vicinity of midrapidity and shows little variation with the target and projectile masses. The average number of produced negatively charged hadrons per participant baryon increases slightly from p+p, p+A to central S+S,Ag collisions.
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