Formation of Quark Phases in compact stars and their connection to Gamma-Ray-Bursts

We analyse the occurrence of quiescent times in the temporal structure of the Gamma-Ray-Bursts (GRBs) light curves. We show that if a long quiescent time is present, it is possible to divide the total duration of GRBs into three periods: the pre-quiescence emission, the quiescent time and the post-quiescence emission. We then discuss a model of the GRBs inner engine based on the formation of quark phases during the life of an hadronic star. Within this model the pre-quiescence emission is interpreted as due to the deconfinement of quark inside an hadronic star and the formation of 2SC quark matter. The post-quiescence emission is due to the conversion of 2SC into the Color-Flavor-Locking (CFL) phase. The temporal delay between these two processes is connected with the nucleation time of the CFL phase in the 2SC phase and it can be associated with the observed quiescent times in the GRBs light curves. The stability of CFL cores in compact stars is also discussed.Comment: 6 pages, 3 figures, to appear in the proceedings of 3th International Conference on Nuclear Physics in Astrophysics (NPAIII), 26 - 31 March 2007 Dresden, German

Maps for Electron Clouds: Application to LHC Conditioning

In this communication we present a generalization of the map formalism, introduced in [1] and [2], to the analysis of electron flux at the chamber wall with particular reference to the exploration of LHC conditioning scenarios.Comment: 3 pages, 4 figure

Testing Deconfinement at High Isospin Density

We study the transition from hadronic matter to a mixed phase of quarks and hadrons at high baryon and isospin densities reached in heavy ion collisions. We focus our attention on the role played by the nucleon symmetry energy at high density.In this respect the inclusion of a scalar isovector meson, the \delta-coupling, in the Hadron Lagrangian appears rather important. We study in detail the formation of a drop of quark matter in the mixed phase, and we discuss the effects on the quark drop nucleation probability of the finite size and finite time duration of the high density region. We find that, if the parameters of quark models are fixed so that the existence of quark stars is allowed, then the density at which a mixed phase starts forming drops dramatically in the range Z/A \sim 0.3--0.4. This opens the possibility to verify the Witten-Bodmer hypothesis on absolute stability of quark matter using ground-based experiments in which neutron-rich nuclei are employed. These experiments can also provide rather stringent constraints on the Equation of State (EoS) to be used for describing the pre-Supernova gravitational collapse. Consistent simulations of neutron rich heavy ion collisions are performed in order to show that even at relatively low energies, in the few AGeV range, the system can enter such unstable mixed phase. Some precursor observables are suggested, in particular a ``neutron trapping'' effect.Comment: 32 pages, 14 figures, elsart late

Dynamics of Phase Transitions in Asymmetric Nuclear Matter

We present several possibilities offered by the reaction dynamics of dissipative heavy ion collisions to study in detail the symmetry term of the nuclear equation of state, $EOS$. In particular we discuss isospin effects on the nuclear liquid-gas phase transition, {\it Isospin Distillation}, and on collective flows. We stress the importance of a microscopic relativistic structure of the effective interaction in the isovector channel. The possibility of an {\it early} transition to deconfined matter in high isospin density regions is also suggested. We finally select {\it Eleven} observables, in different beam energy regions, that appear rather sensitive to the isovector part of the nuclear $EOS$, in particular in more exclusive experiments.Comment: 8 pages, 7 figures, ISPUN02 Conference, Halong-Vietnam, Nov.20-25 2002, to appear in Nucl.Phys.A. Elsevier Proceedings Styl

A confinement model calculation of h_1(x)

The transverse polarization distribution of quarks $h_1(x)$ is computed in a confinement model, the chiral chromodielectric model. The flavor structure of $h_1$, its $Q^2$ evolution and Soffer's inequality are studied. The Drell--Yan double transverse asymmetry $A_{TT}$ is evaluated and found to be one order of magnitude smaller than the double longitudinal asymmetry.Comment: 11 pages, 5 PostScript figures in an uuencoded file h1figures.u

Geomorphological control of fine sedimentation on the northern Portuguese shelf

Six cores sampled at two mud fields located on the northern Portuguese continental shelf have been studied in order to evaluate the control processes of fine sedimentation. The southern mud patch, offshore from the Douro River, is limited on the western side by some Cretaceous and Paleocene outcrops that constitute reliefs of 5-30 m in width; on the contrary, the northern mud patch, offshore from the Minho River, extends along a flat region. Granulometric distribution shows that the sediments from the Minho mud patch are coarser than those from the Douro mud patch, where the grain size diminishes towards the west. Carbonate content is also higher in the Minho mud field. The sediment organisation in fining-up sequences in the Minho mud patch and in the eastern part of the Douro mud patch indicates sediment remobilisation by storms. The Douro mud patch has higher sedimentation rates than the Minho mud patch. The highest values are probably related to the existence of reliefs, which may offer hydrodynamic protection or function as a fine sediment barrier. The elemental distribution for chemical elements was determined in different fractions of these cores. Geochemical patterns are generally quite similar for both mud fields, indicating a common continental origin for the sediments. The major differences in the chemical composition are mainly controlled by the grain-size distribution, either reflecting the presence of coarse quartz particles or a local enrichment in biogenic material.En este trabajo se han estudiado seis testigos de la zona norte de la plataforma continental portuguesa con el objetivo de evaluar los procesos que controlan la sedimentación de materiales finos en esta región. Los fangos acumulados más al sur, frente a la desembocadura del río Duero, están limitados al oeste por relieves cretácicos y paleocenos de 5 a 30 m de altura. Los fangos septentrionales, frente a la desembocadura del río Miño, se extienden sobre una región plana. La distribución granulométrica muestra que estos últimos son más gruesos que los depositados frente al Duero, en los que el tamaño de grano disminuye hacia el oeste. El contenido en carbonato es más elevado en la zona del Miño. Las secuencias granodecrecientes encontradas en los fangos del Miño y en los del sector oriental del Duero indican retrabajamiento del sedimento por tormentas. La tasa de sedimentación es mayor en los fangos situados frente al Duero, donde los valores más altos están relacionados probablemente con la existencia de relieves, los cuales ofrecerían una protección hidrodinámica o actuarían como una barrera para los sedimentos. La distribución de la concentración de diversos elementos químicos a lo largo de los testigos fue determinada para diferentes fracciones. El patrón geoquímico es bastante similar en ambas zonas y pone de manifiesto una procedencia continental de los sedimentos. Las principales diferencias en la composición química están fundamentalmente controladas por la distribución granulométrica, bien por la presencia de granos gruesos de cuarzo, bien por un enriquecimiento local en material biogénico.Instituto Español de Oceanografí

Nonlinear statistical effects in relativistic mean field theory

We investigate the relativistic mean field theory of nuclear matter at finite temperature and baryon density taking into account of nonlinear statistical effects, characterized by power-law quantum distributions. The analysis is performed by requiring the Gibbs conditions on the global conservation of baryon number and electric charge fraction. We show that such nonlinear statistical effects play a crucial role in the equation of state and in the formation of mixed phase also for small deviations from the standard Boltzmann-Gibbs statistics.Comment: 9 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:1005.4643 and arXiv:0912.460

The dopamine and cannabinoid interaction in the modulation of emotions and cognition: assessing the role of cannabinoid CB1 receptor in neurons expressing dopamine D1 receptors

Although cannabinoid CB1 receptors (CB1Rs) are densely expressed in neurons expressing dopamine D1 receptors (D1Rs), it is not fully understood to what extent they modulate emotional behaviors. We used conditional CB1R knock-out animals lacking CB1Rs in neurons expressing D1R (D1-CB1(-/-)) in order to answer this question. To elucidate the behavioral effects of CB1R deficiency in this specific neuronal subpopulation, we subjected D1-CB1(-/-) mice to a battery of behavioral tests which included exploration-based tests, depressive-like behavioral tests, social behavior, and fear-related memory paradigms. D1-CB1(-/-) did not show any difference in the exploration-based paradigms such as open field, elevated plus maze, or novel object investigation test, except for an increase in novelty-induced grooming. By contrast, they showed a mild anhedonia-like state as described by the slightly decreased preference for sweet solution, as compared to wild-type control group. This decrease, however, could be observed only during the first day of exposure, thus suggesting increased neophobia as an alternative explanation. Accordingly, mutant mice performed normally in the forced swim test, a procedure widely used for evaluating behavioral despair in rodents. However, weak-to moderate anxiety-like phenotypes were evident when D1-CB1(-/-) mice were tested for social behavior. Most strikingly, D1-CB1(-/-) mice exhibited significantly increased contextual and auditory-cued fear, with attenuated within session extinction, suggesting that a specific reduction of endocannabinoid signaling in neurons expressing dopamine D1Rs is able to affect acute fear adaptation. These results provided first direct evidence for a cross-talk between dopaminergic D1Rs and endocannabinoid system in terms of controlling negative affect