Determination of the reaction plane in ultrarelativistic nuclear collisions

In the particles produced in a nuclear collision undergo collective flow, the reaction plane can in principle be determined through a global event analysis. We show here that collective flow can be identified by evaluating the reaction plane independently in two separate rapidity intervals, and studying the correlation between the two results. We give an analytical expression for the correlation function between the two planes as a function of their relative angle. We also discuss how this correlation function is related to the anisotropy of the transverse momentum distribution. Email contact: [email protected]: Saclay-T93/026 Email: [email protected]

Azimuthal Correlations in the Target Fragmentation Region of High Energy Nuclear Collisions

Results on the target mass dependence of proton and pion pseudorapidity distributions and of their azimuthal correlations in the target rapidity range $-1.73 \le \eta \le 1.32$ are presented. The data have been taken with the Plastic-Ball detector set-up for 4.9 GeV p + Au collisions at the Berkeley BEVALAC and for 200 $A\cdot$GeV/$c$ p-, O-, and S-induced reactions on different nuclei at the CERN-SPS. The yield of protons at backward rapidities is found to be proportional to the target mass. Although protons show a typical ``back-to-back'' correlations, a ``side-by-side'' correlation is observed for positive pions, which increases both with target mass and with impact parameter of a collision. The data can consistently be described by assuming strong rescattering phenomena including pion absorption effects in the entire excited target nucleus.Comment: 7 pages, figures included, complete postscript available at ftp://qgp.uni-muenster.de/pub/paper/azi-correlations.ps submitted to Phys. Lett.

Psychopathologie des Ganser-Syndroms: Literaturübersicht und Falldiskussion

Zusammenfassung: Das Kernsymptom des Ganser-Syndroms besteht im "Vorbeiantworten" auf einfache Fragen. Die Ursache dieses seltenen Syndroms ist unklar. Aktuelle Klassifikationssysteme zählen es zu den dissoziativen Störungen, wobei eine psychogene Ursache der Symptome angenommen wird. Anhand einer Literaturrecherche (n=151) wird jedoch gezeigt, dass das Ganser-Syndrom sehr häufig mit Hirnverletzungen assoziiert ist, wobei detaillierte bildgebende, neuropsychologische und neurologische Untersuchungen weitgehend fehlen. Wir stellen eine rechtshändige Patientin mit einem Ganser-Syndrom nach einem großen linkshemisphärischen Mediainfarkt vor. Die detaillierte neuropsychologische Untersuchung zeigte eine untypische Lateralisierung kognitiver Funktionen mit einer sog. gekreuzten Nichtaphasie und ausgeprägten frontal-exekutiven Funktionsstörungen. Unter Berücksichtigung sowohl der psychiatrischen als auch der neuropsychologischen Aspekte wird diskutiert, in welchem Zusammenhang das psychopathologische Symptom des "Vorbeiantwortens" mit spezifischen frontal-exekutiven Hirnfunktionsstörungen stehen könnt

Diamide resistance: 10 years of lessons from Lepidopteran pests

Diamide insecticides selectively acting on insect ryanodine receptors (RyR) were launched to the market more than 10 years ago, particularly targeted for the control of lepidopteran pest species in diverse agronomic and horticultural cropping systems. They are now globally registered in many countries and provide reliable control levels in most settings. However, their frequent application, due to alternative mode of action chemistries often not providing sufficient levels of control, has resulted in the selection of diamide resistance in some of the world’s most destructive lepidopteran species, including populations of diamondback moth, tomato leafminer, rice stem borer and more recently beet armyworm. High levels of diamide resistance, compromising diamide efficacy at recommended field rates, has been shown to be conferred by RyR target-site mutations affecting diamide binding. The present work reviews the global status of diamide insecticide resistance in lepidopteran pests, with special reference to RyR target-site alterations. Furthermore, we discuss principles enabling the prediction of the impact and spread of diamide resistance, based on population genetics and associated fitness costs as influenced by the known target-site mutations recently described. In this context, we reiterate calls by the Insecticide Resistance Action Committee to implement effective diamide insecticide resistance management by following a three-step strategy of resistance identification, tracking and prediction according to the protocols discussed in this article

Heavy Ion Physics at RHIC

The status of the physics of heavy ion collisions is reviewed based on measurements over the past 6 years from the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. The dense nuclear matter produced in Au+Au collisions with nucleon-nucleon c.m. energy $\sqrt{s_{NN}}=200$ GeV at RHIC corresponds roughly to the density and temperature of the universe a few microseconds after the `big-bang' and has been described as "a perfect liquid" of quarks and gluons, rather than the gas of free quarks and gluons, ``the quark-gluon plasma" as originally envisaged. The measurements and arguments leading to this description will be presented.Comment: 31 pages, 23 figures, Proceedings of Symposium "50+ Years of High Energy Physics at UB", University at Buffalo, NY, October 20-21,200

Proton stopping in C+C, d+C, C+Ta and d+Ta collisions at 4.2A GeV/c

The shape of proton rapidity distributions is analysed in terms of their Gaussian components, and the average rapidity loss is determined in order to estimate the amount of stopping in C+C, d+C, C+Ta and d+Ta collisions at 4.2A GeV/c. Three Gaussians correspond to the nuclear transparency and describe well all peripheral and also C+C central collisions. Two-component shape is obtained in case of d+C and C+Ta central collisions. Finally one Gaussian, found in d+Ta central collisions, corresponds to the full stopping. The calculated values of the average rapidity loss support the qualitative relationship between the number of Gaussian components and the corresponding stopping power. It is also observed, in central collisions, that the average rapidity loss increases with the ratio of the number of target and the number of projectile participants.Comment: 9 pages REVTeX, 1 PS figure replaced, to be published in Phys.Rev.

Quantification of the transmural dynamics of atrial fibrillation by simultaneous endocardial and epicardial optical mapping in an acute sheep model

BACKGROUND: Therapy strategies for atrial fibrillation based on electrical characterization are becoming viable personalized medicine approaches to treat a notoriously difficult disease. In light of these approaches that rely on high-density surface mapping, this study aims to evaluate the presence of three-dimensional electrical substrate variations within the transmural wall during acute episodes of atrial fibrillation. METHODS AND RESULTS: Optical signals were simultaneously acquired from the epicardial and endocardial tissue during acute fibrillation in ovine isolated left atria. Dominant frequency, regularity index, propagation angles and phase dynamics were assessed and correlated across imaging planes to gauge the synchrony of the activation patterns compared to paced rhythms. Static frequency parameters were well correlated spatially between the endocardium and the epicardium (dominant frequency, 0.79+/-0.06 and regularity index, 0.93+/-0.009). However, dynamic tracking of propagation vectors and phase singularity trajectories revealed discordant activity across the transmural wall. The absolute value of the difference in the number, spatial stability, and temporal stability of phase singularities between the epicardial and endocardial planes was significantly greater than 0 with a median difference of 1.0, 9.27%, and 19.75%, respectively. The number of wavefronts with respect to time was significantly less correlated and the difference in propagation angle was significantly larger in fibrillation compared to paced rhythms. CONCLUSIONS: Atrial fibrillation substrates are dynamic three-dimensional structures with a range of discordance between the epicardial and endocardial tissue. The results of this study suggest that transmural propagation may play a role in AF maintenance mechanisms

Neutrons from multiplicity-selected La-La and Nb-Nb collisions at 400A MeV and La-La collisions at 250A MeV

Triple-differential cross sections for neutrons from high-multiplicity La-La collisions at 250 and 400 MeV per nucleon and Nb-Nb collisions at 400 MeV per nucleon were measured at several polar angles as a function of the azimuthal angle with respect to the reaction plane of the collision. The reaction plane was determined by a transverse-velocity method with the capability of identifying charged-particles with Z=1, Z=2, and Z > 2. The flow of neutrons was extracted from the slope at mid-rapidity of the curve of the average in-plane momentum vs the center-of-mass rapidity. The squeeze-out of the participant neutrons was observed in a direction normal to the reaction plane in the normalized momentum coordinates in the center-of-mass system. Experimental results of the neutron squeeze-out were compared with BUU calculations. The polar-angle dependence of the maximum azimuthal anisotropy ratio $r(\theta)$ was found to be insensitive to the mass of the colliding nuclei and the beam energy. Comparison of the observed polar-angle dependence of the maximum azimuthal anisotropy ratio $r(\theta)$ with BUU calculations for free neutrons revealed that $r(\theta)$ is insensitive also to the incompressibility modulus in the nuclear equation of state.Comment: ReVTeX, 16 pages, 17 figures. To be published in Physical Review

Dynamical cluster-decay model for hot and rotating light-mass nuclear systems, applied to low-energy 32^{32}S + 24^{24}Mg →56\to ^{56}Ni reaction

The dynamical cluster-decay model (DCM) is developed further for the decay of hot and rotating compound nuclei (CN) formed in light heavy-ion reactions. The model is worked out in terms of only one parameter, namely the neck-length parameter, which is related to the total kinetic energy TKE(T) or effective Q-value $Q_{eff}(T)$ at temperature T of the hot CN, defined in terms of the both the light-particles (LP), with $A \leq$ 4, Z $\leq$ 2, as well as the complex intermediate mass fragments (IMF), with $4 2$, is considered as the dynamical collective mass motion of preformed clusters through the barrier. Within the same dynamical model treatment, the LPs are shown to have different characteristics as compared to the IMFs. The systematic variation of the LP emission cross section $\sigma_{LP}$, and IMF emission cross section $\sigma_{IMF}$, calculated on the present DCM match exactly the statistical fission model predictions. It is for the first time that a non-statistical dynamical description is developed for the emission of light-particles from the hot and rotating CN. The model is applied to the decay of $^{56}$Ni formed in the $^{32}$S + $^{24}$Mg reaction at two incident energies E$_{c.m.}$ = 51.6 and 60.5 MeV. Both the IMFs and average $\bar{TKE}$ spectra are found to compare reasonably nicely with the experimental data, favoring asymmetric mass distributions. The LPs emission cross section is shown to depend strongly on the type of emitted particles and their multiplicities