Correlation measurements in high-multiplicity events

Requirements for correlation measurements in high--multiplicity events are discussed. Attention is focussed on detection of so--called hot spots, two--particle rapidity correlations, two--particle momentum correlations (for quantum interferometry) and higher--order correlations. The signal--to--noise ratio may become large in the high--multiplicity limit, allowing meaningful single--event measurements, only if the correlations are due to collective behavior.Comment: MN 55455, 20 pages, KSUCNR-011-92 and TPI-MINN-92/47-T (revised). Revised to correct typo in equation (30), and to fill in a few steps in calculations. Now published as Phys. Rev. C 47 (1993) 232

Thermal photon production in high-energy nuclear collisions

We use a boost-invariant one-dimensional (cylindrically symmetric) fluid dynamics code to calculate thermal photon production in the central rapidity region of S+Au and Pb+Pb collisions at SPS energy ($\sqrt{s}=20$ GeV/nucleon). We assume that the hot matter is in thermal equilibrium throughout the expansion, but consider deviations from chemical equilibrium in the high temperature (deconfined) phase. We use equations of state with a first-order phase transition between a massless pion gas and quark gluon plasma, with transition temperatures in the range $150 \leq T_c \leq 200$ MeV.Comment: revised, now includes a_1 contribution. revtex, 10 pages plus 4 figures (uuencoded postscript

Source-receptor matrix calculation with a Source-receptor matrix calculation with a backward mode

International audienceThe possibility to calculate linear-source receptor relationships for the transport of atmospheric trace substances with a Lagrangian particle dispersion model (LPDM) running in backward mode is shown and presented with many tests and examples. The derivation includes the action of sources and of any first-order processes (transformation with prescribed rates, dry and wet deposition, radioactive decay, ...). The backward mode is computationally advantageous if the number of receptors is less than the number of sources considered. The combination of an LPDM with the backward (adjoint) methodology is especially attractive for the application to point measurements, which can be handled without artificial numerical diffusion. Practical hints are provided for source-receptor calculations with different settings, both in forward and backward mode. The equivalence of forward and backward calculations is shown in simple tests for release and sampling of particles, pure wet deposition, pure convective redistribution and realistic transport over a short distance. Furthermore, an application example explaining measurements of Cs-137 in Stockholm as transport from areas contaminated heavily in the Chernobyl disaster is included

Source-receptor matrix calculation with a Lagrangian particle dispersion model in backward mode

International audienceThe possibility to calculate linear-source receptor relationships for the transport of atmospheric trace substances with a Lagrangian particle dispersion model (LPDM) running in backward mode is shown and presented with many tests and examples. This mode requires only minor modifications of the forward LPDM. The derivation includes the action of sources and of any first-order processes (transformation with prescribed rates, dry and wet deposition, radioactive decay, etc.). The backward mode is computationally advantageous if the number of receptors is less than the number of sources considered. The combination of an LPDM with the backward (adjoint) methodology is especially attractive for the application to point measurements, which can be handled without artificial numerical diffusion. Practical hints are provided for source-receptor calculations with different settings, both in forward and backward mode. The equivalence of forward and backward calculations is shown in simple tests for release and sampling of particles, pure wet deposition, pure convective redistribution and realistic transport over a short distance. Furthermore, an application example explaining measurements of Cs-137 in Stockholm as transport from areas contaminated heavily in the Chernobyl disaster is included

Space Networking Demonstrated for Distributed Human-Robotic Planetary Exploration

Communications and networking experts from the NASA Glenn Research Center designed and implemented an innovative communications infrastructure for a simulated human-robotic planetary mission. The mission, which was executed in the Arizona desert during the first 2 weeks of September 2002, involved a diverse team of researchers from several NASA centers and academic institutions

Chemische Triebkräfte : Von der Verbrennung zum Herzschlag

Was hat eine einfache chemische Verbrennung mit dem Herzschlag zu tun? Diese Frage soll im Rahmen einer physikalisch-chemischen Experimentalvorlesung beantwortet werden. Dabei fügen sich anscheinend weit voneinander entfernte Phänomene in ein klar strukturiertes Bild. Es wird deutlich, dass der menschliche Körper aus thermodynamischer Sicht eine biologische \u27Wärmekraftmaschine\u27 ist, deren Wirkungsgrad höher als der Wirkungsgrad mechanische Wärmekraftmaschinen (\u27Dampfmaschinen\u27). Spröde anmutende thermodynamische Sätze füllen sich mit Leben - die Begriffe \u27Energie, Wärme, Entropie\u27 werden anschaulich. Anhand einfacher Demonstrationsexperimente wird ein Bogen über 250 Jahre Forschung im Bereich der chemischen Energiewandlung gespannt

Identification of the Biological Function of Rab-GGT β-Subunits by Reverse Techniques

Protein prenylation is a post-translational process where lipids are added to carboxyl end groups, which allows proteins to function properly in the eukaryotic cell. The job of prenylation is to help in targeting certain proteins to specific membrane along with promoting protein-protein interactions. We use reverse genetics techniques to understand the function of prenylation in plant development by examining the phenotypic changes caused by specific gene disruption. One of the excellent model organisms Physcomitrella patens (moss) is used due to its simple structure, limited tissue and cells, sequenced genome, and its high gene targeting efficiency. Rab geranylgeranyl transferase-II (Rab-GGT) is one of three enzymes that can perform protein prenylation and the actual function of Rab-GGT is largely unknown. Moss has one copy of Rab-GGT α subunit (PpRGTA1) and two copies of β subunit (PpRGTB1 and PpRGTB2). This study focuses on the role of the Rab-GGT β subunit in the moss. It has been found that the knockout of either PpRGTB1 or PpRGTB2 results in no visible phenotype, which leads us to believe that these genes are functionally redundant. The knockout of both PpRGTB1 and PpRGTB2 genes has shown to be lethal, which means Rab-GGT is required for viability. To figure out the function of Rab-GGT, we use RNA interference approach to down-regulate the expression level of PpRGTB2 in the PpRGTB1 knockout background so we can observe the phenotypic consequences.https://ir.library.louisville.edu/uars/1049/thumbnail.jp