[en] It has been observed that the momentum distributions of partons in bound nuclei are distorted relative to those of free protons and neutrons. This phenomenon was first observed in deep inelastic scattering experiments with muon and neutrino beams on nuclear targets and is known as the EMC effect. Similar phenomena have been observed in other high energy interactions such as the Drell-Yan process, the hadroproduction of direct photons, and the resonance production of charmonium and bottomonium states. In this work we investigate the possibility that these effects are predominantly of partonic origin. Standard nuclear quantum mechanics predicts that there is a non-zero probability for bound nucleons to overlap forming complex color singlets. We examine whether the observed EMC-type effects can be attributed to the difference between the parton momentum distributions in such clusters and those in single nucleons. We present a systematic way of determining these distributions in the Bjorken scaling limit and of estimating the average number of multiquark clusters in nuclei. The model predicts depletion of the valence quark and enhancement of the ocean quark and gluon components as the cluster baryon number increases. These properties can naturally explain significant features of the high energy behavior of nuclear targets

[en] Electromagnetic Dissociation (ED) occurs in collisions of relativistic heavy ions involving impact parameters larger than the nuclear interaction radius. In such collisions strong electromagnetic fields acting at the nucleus can produce, for high charges and ultrarelativistic energies, cross sections much larger than the total nuclear interaction cross section. In ED collisions absorption of a virtual photon generally leads to excitation of a nuclear giant resonance. The NA53 experiment studied ED by bombarding Au targets with 158 GeV/nucleon Pb projectiles from the SPS accelerator. Preliminary values of σ_ED for the one- and two-neutron removal processes were determined to be 26.4 ± 4.0 and 4.6 ± 0.7 barns, respectively. Theoretical predictions for σ_ED were calculated including the effects of both the E1 and E2 giant resonances. The calculations are extended to energies planned for heavy ion collisions at the RHIC and LHC colliders

[en] Electric charge correlations are studied with the Balance Function method for central Pb + Pb collisions at the CERN - SPS. The results on centrality selected Pb + Pb interactions at 40 and 158 AGeV are presented for the first time for two different rapidity intervals: The mid-rapidity region where a decrease of the width with increasing centrality of the collision is observed and the forward rapidity region where this effect vanishes. This could suggest a delayed hadronization scenario.In addition, the results from a first attempt to study the energy dependence of the Balance Function throughout the whole SPS energy range, will also be presented. The suitably scaled decrease of the width is approximately constant for the intermediate energies (30 to 80 AGeV) and gets stronger for the highest SPS and RHIC energies. On the other hand, both URQMD and HSD simulation results show no dependence on the collision energy

[en] We present the recent Balance Function (BF) results obtained by the NA49 collaboration for the pseudo-rapidity dependence of non-identified charged particle correlations for two SPS energies. Experimental results indicate a clear centrality dependence only in the mid-rapidity region. The results of an energy dependence study of the BF throughout the whole SPS energy range will also be discussed. In addition, the correlation of identified hadrons is studied and presented for the first time. The study of hadron correlation has also been extended in order to cope with the high multiplicity environment that is expected to be seen at LHC. We will present the latest results from simulations concerning the extension of these studies to the ALICE experiment

[en] We report a case of cerebral hydatid disease demonstrated by CT and MRI, treated with albendazole. Follow-up showed complete dissapearance of the cysts with residual focal calcification on CT and presumed gliosis on MRI. (orig.)

[en] The Balance Function analysis method was developed in order to study the long range correlations in pseudo-rapidity of charged particles. The final results on p+p, C+C, Si+Si and centrality selected Pb+Pb collisions at s_NN=17.2 GeV and the preliminary data at s_NN=8.8 GeV are presented. The width of the Balance Function decreases with increasing system size and centrality of the collisions. This could suggest a delayed hadronization scenario

[en] This article is an appraisal of the use of CT in the management of patients with unstable abdominal trauma. We examined 41 patients with abdominal trauma using noncontrast dynamic CT. In 17 patients a postcontrast dynamic CT was also carried out. On CT, 25 patients had hemoperitoneum. Thirteen patients had splenic, 12 hepatic, 6 pancreatic, 8 bowel and mesenteric, 12 renal and 2 vascular injuries. Seven patients had retroperitoneal and 2 patients adrenal hematomas. All but five lesions (three renal, one pancreatic, and one splenic) were hypodense when CT was performed earlier than 8 h following the injury. Postcontrast studies (n = 17), revealed 4 splenic, 3 hepatic, 1 pancreatic, 3 renal, and 2 bowel and mesenteric injuries beyond what was found on noncontrast CT. Surgical confirmation (n = 21) was obtained in 81.81 % of splenic, 66.66 % of hepatic, 83.33 % of pancreatic, 100 % of renal, 100 % of retroperitoneal, and 85.71 % of bowel and mesenteric injuries. The majority of false diagnoses was obtained with noncontrast studies. Computed tomography is a remarkable method for evaluation and management of patients with hemodynamically unstable abdominal trauma, but only if it is revealed in the emergency room. Contrast injection, when it could be done, revealed lesions that were not suspected on initial plain scans. (orig.)

[en] A phenomenological model for the production of ''Centauro''-type cosmic-ray events is developed, assuming a nucleus-nucleus interaction in the upper atmosphere. The model is used to estimate, in a self-consistent way, several thermodynamic and kinematical quantities, characterizing the observed Centauro events. On the basis of this model, we describe a typical ''Centauro'' event, possibly produced in the fragmentation rapidity of an A+A central collision at √s =200A GeV at the BNL Relativistic Heavy Ion Collider. We suggest several characteristic signatures for these events, as well as the possibility of observing ''strangelets.''

[en] A phenomenological method is proposed to select possible Quark matter forming events in ultra-relativistic nucleus-nucleus interactions. We compare the released photonic and hadronic energies from a Quark matter forming event and from a normal Hadronic event and derive a relation, which may be used in an event-by-event analysis to differentiate the two phases. We determine thus two regions of QCD deconfinement. We also discuss the hadronic, photonic energy and multiplicity contents and the < P_T> of several exotic cosmic ray events at ultra high energies. On the basis of the phenomenological model, we suggest that the 'Centauro' type are Quark matter events near the projectile fragmentation region with very large baryochemical potential, μ_b. The 'Anti-Centauro' type events are created by vacuum excitation in the central region with near zero μ_b. (orig.)

[en] In this report we attempt to summarize the lattice formulation of Gauge Theories and investigate some of its most important feautures. The lattice provides a natural cut-off in the ultraviolet limit, which eliminates the need for renormalization and, because of its non-perturbative nature, consists is a good framework for the study of confinement in Quantum Chromodynamics. In addition it indicates the possibility of phase transitions and can be used to investigate the strong coupling limit of Gauge Theories. In its path integral formulation, it allows for the direct application of statistical calculations and Mean Field Theory techniques as well as Monte Carlo simulations which lead to exact results. The availability of sophisticated algorithms and fast computers has developed Lattic Gauge Theories into an active research field