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.

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.

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

Second Order Phase Transitions : From Infinite to Finite Systems

We investigate the Equation of State (EOS) of classical systems having 300 and 512 particles confined in a box with periodic boundary conditions. We show that such a system, independently on the number of particles investigated, has a critical density of about 1/3 the ground state density and a critical temperature of about $2.5~ MeV$. The mass distribution at the critical point exhibits a power law with $\tau = 2.23$. Making use of the grand partition function of Fisher's droplet model, we obtain an analytical EOS around the critical point in good agreement with the one extracted from the numerical simulations.Comment: RevTex file, 17 pages + 9 figures available upon request from [email protected]

On Deusons or Deuteronlike Meson-Meson Bound States

The systematics of deuteronlike two-meson bound states, {\it deusons}, is discussed. Previous arguments that many of the present non-$q\bar q$ states are such states are elaborated including, in particular, the tensor potential. For pseudoscalar states the important observation is made that the centrifugal barrier from the P-wave can be overcome by the $1/r^2$ and $1/r^3$ terms of the tensor potential. In the heavy meson sector one-pion exchange alone is strong enough to form at least deuteron-like $B\bar B^*$ and $B^*\bar B^*$ composites bound by approximately 50 MeV, while $D\bar D^*$ and $D^*\bar D^*$ states are expected near the threshold.Comment: Invited talk at the Hadron93 International Conf. on Hadron Spectroscopy, Como, Italy 22.-25.6. 1993. 5 pages in LATEX HU-SEFT R 1993-13

Elliptical flow -- a signature for early pressure in ultrarelativistic nucleus-nucleus collisions

Elliptical energy flow patterns in non-central Au(11.7AGeV) on Au reactions have been studied employing the RQMD model. The strength of these azimuthal asymmetries is calculated comparing the results in two different modes of RQMD (mean field and cascade). It is found that the elliptical flow which is readily observable with current experimental detectors may help to distinguish different reasonable expansion scenarios for baryon-dense matter. The final asymmetries are very sensitive to the pressure at maximum compression, because they involve a partial cancelation between early squeeze-out and subsequent flow in the reaction plane. This cancelation can be expected to occur in a broad energy region covered by the current heavy ion fixed-target programs at BNL and at CERN.Comment: 14 pages LaTeX including 3 postscript figure

Heavy ion collisions with non-equilibrium Dirac-Brueckner mean fields

The influence of realistic interactions on the reaction dynamics in intermediate energy heavy ion collisions is investigated. The mean field in relativistic transport calculations is derived from microscopic Dirac-Brueckner (DB) self-energies, taking non-equilibrium effects, in particular the anisotropy of the local phase space configurations, into account. Thus this approach goes beyond the local density approximation. A detailed analysis of various in-plane and out-of-plane flow observables is presented for Au on Au reactions at incident energies ranging from 250 to 800 A.MeV and the results are compared to recent measurements of the FOPI collaboration. An overall good agreement with in-plane flow data and a reasonable description of the out-of-plane emission is achieved. For these results the intrinsic momentum dependence of the non-equilibrium mean fields is important. On the other hand, the local density approximation with the same underlying DB forces as well as a standard non-linear version of the $\sigma\omega$ model are less successful in describing the present data. This gives evidence of the applicability of self energies derived from the DB approach to nuclear matter also far from saturation and equilibrium.Comment: 63 pages Latex, using Elsevier style, 20 ps-figures, to appear in Nucl. Phys.