Elliptic flow of resonances at RHIC: probing final state interactions and the structure of resonances

We propose the measurement of the elliptic flow of hadron resonances at the Relativistic Heavy Ion Collider as a tool to probe the amount of hadronic final state interactions for resonances at intermediate and large transverse momenta. This can be achieved by looking at systematic deviations of the measured flow coefficient $v_2$ from the scaling law given by the quark recombination formalism. Our method can be generalized to explore the structure of exotic particles, such as the recently found pentaquark $\Theta^+ (1540)$.Comment: 5 pages, 2 figures; v2: accepted version for publication in Physical Review C rapid communication

Hadronization in heavy ion collisions: Recombination and fragmentation of partons

We argue that the emission of hadrons with transverse momentum up to about 5 GeV/c in central relativistic heavy ion collisions is dominated by recombination, rather than fragmentation of partons. This mechanism provides a natural explanation for the observed constant baryon-to-meson ratio of about one and the apparent lack of a nuclear suppression of the baryon yield in this momentum range. Fragmentation becomes dominant at higher transverse momentum, but the transition point is delayed by the energy loss of fast partons in dense matter.Comment: 4 pages, 2 figures; v2: reference [8] added; v3: Eq.(2) corrected, two references added, version to appear in PR

MAESTRO, CASTRO, and SEDONA -- Petascale Codes for Astrophysical Applications

Performing high-resolution, high-fidelity, three-dimensional simulations of Type Ia supernovae (SNe Ia) requires not only algorithms that accurately represent the correct physics, but also codes that effectively harness the resources of the most powerful supercomputers. We are developing a suite of codes that provide the capability to perform end-to-end simulations of SNe Ia, from the early convective phase leading up to ignition to the explosion phase in which deflagration/detonation waves explode the star to the computation of the light curves resulting from the explosion. In this paper we discuss these codes with an emphasis on the techniques needed to scale them to petascale architectures. We also demonstrate our ability to map data from a low Mach number formulation to a compressible solver.Comment: submitted to the Proceedings of the SciDAC 2010 meetin

Resonance Production in RHIC Collisions

Results of resonance particle production measured at RHIC in $\sqrt{s_{\rm NN}} =$ 200 GeV Au+Au collisions are compared to measurements in p+p and d+Au collisions in order to verify the existence of an extended hardronically interacting medium. Yield and momentum distributions of resonances maybe modified during the fireball lifetime due to resonance decay and the subsequent rescattering of their decay daughters as well as the regeneration of resonances from their decay products. Modified momentum spectra in heavy ion collisions may change the nuclear modification factor R$_{\rm AA}$. The influence on the elliptic flow v$_{2}$ due to late regeneration of resonances is discussed.Comment: 6 pages, 6 figures, Proceedings of the 22st Winter Workshop on Nuclear Dynamics, San Diago, California, 12-18 March, 200

QCD matter within a quasi-particle model and the critical end point

We compare our quasi-particle model with recent lattice QCD results for the equation of state at finite temperature and baryo-chemical potential. The inclusion of the QCD critical end point into models is discussed. We propose a family of equations of state to be employed in hydrodynamical calculations of particle spectra at RHIC energies and compare with the differential azimuthal anisotropy of strange and charm hadrons.Comment: talk at Quark Matter 2005, August 4 - 9, 2005, Budapest, Hungar

Low Mach Number Modeling of Convection in Helium Shells on Sub-Chandrasekhar White Dwarfs. I. Methodology

We assess the robustness of a low Mach number hydrodynamics algorithm for modeling helium shell convection on the surface of a white dwarf in the context of the sub-Chandrasekhar model for Type Ia supernovae. We use the low Mach number stellar hydrodynamics code, MAESTRO, to perform three-dimensional, spatially-adaptive simulations of convection leading up to the point of the ignition of a burning front. We show that the low Mach number hydrodynamics model provides a robust description of the system.Comment: accepted to ApJ many figures degraded in quality to save spac

Progression of myopathology in Kearns-Sayre syndrome

We report on the progression of myopathology by comparing two biopsies from a patient with a Kearns-Sayre-Syndrome. The first biopsy was taken in 1979 and showed 10% ragged-red fibers. Myopathic changes were slight including internal nuclei and fiber splitting in 10% of the fibers. Electron microscopy revealed typical mitochondrial abnormalities with regard to number and shape. In 1989 a second biopsy was performed for an extended analysis of mitochondrial DNA. This time less than 5% of all fibers were ragged-red. Severe myopathic changes could be detected which so far has rarely been reported in mitochondrial cytopathy

White Lines and 3d-Occupancy for the 3d Transition-Metal Oxides

Electron energy-loss spectrometry was employed to measure the white lines at the L23 absorption edges of the 3d transition-metal oxides and lithium transition-metal oxides. The white-line ratio (L3/L2) was found to increase between d^0 and d^5 and decrease between d^5 and d^10, consistent with previous results for the transition metals and their oxides. The intensities of the white lines, normalized to the post-edge background, are linear for the 3d transition-metal oxides and lithium transition-metal oxides. An empirical correlation between normalized white-line intensity and 3d occupancy is established. It provides a method for measuring changes in the 3d-state occupancy. As an example, this empirical relationship is used to measure changes in the transition-metal valences of Li_{1-x}Ni_{0.8}Co_{0.2}O_2 in the range of 0 < x < 0.64. In these experiments the 3d occupancy of the nickel ion decreased upon lithium deintercalation, while the cobalt valence remained constant.Comment: 6 pages, 7 figure

Apm4, the mu subunit of yeast AP-2 interacts with Pkc1, and mutation of the Pkc1 consensus phosphorylation site Thr176 inhibits AP-2 recruitment to endocytic sites.

The AP-2 endocytic adaptor has been extensively characterized in mammalian cells and is considered to play a role both in cargo binding and in formation of endocytic sites. However, despite our detailed knowledge of mechanistic aspects of endocytic complex assembly and disassembly in the model organism Saccharomyces cerevisiae, no function of AP-2 had been described in wild-type yeast under normal growth conditions. A recent study however revealed that disruption of the complex caused by deletion of the gene encoding its mu subunit (APM4) caused defects in cell polarity such that responses to pheromone, nutritional status and cell wall damage were affected. Furthermore, a homozygous deletion of the mu subunit gene in Candida albicans affected its ability to grow hyphae. Direct binding to the yeast cell wall stress sensor Mid2 was detected, and in an apm4 deletion strain Mid2 showed reduced re-localization to the mother bud neck region following cell wall damage with calcofluor or to the mating projection tip. Here we demonstrate an interaction between Apm4 and the yeast cell wall integrity pathway component Pkc1 and show that mutation of the predicted Pkc1 site in the Apm4 hinge region affects recruitment of the AP-2 complex to endocytic sites

A Calculation of Baryon Diffusion Constant in Hot and Dense Hadronic Matter Based on an Event Generator URASiMA

We evaluate thermodynamical quantities and transport coefficients of a dense and hot hadronic matter based on an event generator URASiMA (Ultra-Relativistic AA collision Simulator based on Multiple Scattering Algorithm). The statistical ensembles in equilibrium with fixed temperature and chemical potential are generated by imposing periodic boundary condition to the simulation of URASiMA, where energy density and baryon number density is conserved. Achievement of the thermal equilibrium and the chemical equilibrium are confirmed by the common value of slope parameter in the energy distributions and the saturation of the numbers of contained particles, respectively. By using the generated ensembles, we investigate the temperature dependence and the chemical potential dependence of the baryon diffusion constant of a dense and hot hadronic matter.Comment: 15 pages, 5 figures, LaTeX2