Study of psi' and chi_c decays as feed-down sources of J/psi hadro-production

The interpretation of the J/psi suppression patterns observed in nuclear collisions, at CERN and RHIC, as a signature of the formation of a deconfined phase of QCD matter, requires knowing which fractions of the measured J/psi yields, in pp collisions, are due to decays of heavier charmonium states. From a detailed analysis of the available mid-rapidity charmonium hadro-production cross sections, or their ratios, we determine that the J/psi feed-down contributions from psi' and chi_c decays are, respectively, (8.1 +/- 0.3) % and (25 +/- 5) %. These proton-proton values are derived from global averages of the proton-nucleus measurements, assuming that the charmonium states are exponentially absorbed with the length of matter they traverse in the nuclear targets.Comment: 12 pages, 4 figures, 3 table

Absorption and J/psi Suppression in Heavy Ion Collisions

We discuss the J/psi suppression in the framework of multiple collision models. From the analysis of the Pb-Pb NA50 data we conclude that the strength of the absorption has increased, but we find no clear evidence for the formation of the quark-gluon plasma.Comment: 8 pages, 4 figure

Quinoidization of regioregular oligo(THIENO[3,4-b]THIOPHENE)s

Caracterización de oligotiofenosUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

A Expressão Global da Doença de Chagas – Oportunidades Emergentes e Impacto em Portugal

Chagas disease, caused by the protozoan Trypanosoma cruzi is endemic in the countries of Central and South America. Despite vector control programs and other measures taken in the blood banks and maternity hospitals, it is estimated that there are about eight million people infected worldwide. Although traditionally associated with rural life and poverty, the current migration flows transform it into a global public health problem. In Portugal, this problem is poorly known, with an estimated underdiagnosis index that exceeds 99%. In European countries, besides imported cases, autochthonous infections arise through vertical transmission and blood/organ donation.The conventional serological tests for diagnosing Chagas disease and verifying its cure are indirect hemagglutination (IHA), indirect immunofluorescence (IFAT), and enzyme-linked immunoabsorbent assay (ELISA).The hypothesis of autoimmunity as a basic mechanism of this disease and the absence of early markers of cure are the causes of controversy regarding the specific treatment of this disease. The currently available drugs have adverse effects on a large number of patients and parasitological efficacy in chronic disease is suboptimal.The authors reinforce the need of a high level of suspicion in patients with suggestive epidemiology and the need of populational screening of specific high risk groups

The effect of gamma-cyclodextrin addition in the self-assembly behavior of pyrene labeled poly(acrylic) acid with different chain sizes

The interaction between poly(acrylic acid) polymers (PAA) of low- (2000 g/mol) and high- (450,000 g/mol) molecular weight (Mw) hydrophobically modified with pyrene (PAAMePy) and beta- and gamma-cyclodextrins (beta-CD, gamma-CD) was investigated with fluorescent techniques. The interaction with beta-CD promotes little variation in the spectral and photophysical behavior of the polymer, whereas significant changes are observed upon addition of gamma-CD. The degree of inclusion (between the pyrene groups of the polymer and the cyclodextrins) is followed through the observation of the changes in the absorption, excitation (collected in the monomer and excimer emission regions) and emission (IE/IM ratio) spectra and from time-resolved data. Within the studied range of gamma-CD concentration, the fluorescence decays of the long chain (high Mw) PAAMePy polymers were found tri-exponential in the monomer and excimer emission regions in agreement with previous studies. In the case of the low Mw PAAMePy polymers, tri-exponential decays were observed at the monomer and excimer emission wavelengths. However, when a gamma-CD concentration of 0.01 and 0.03 M is reached for, respectively, the low- and high-labeled pyrene short chain (low Mw) polymers, the fluorescence decays in the excimer region become biexponential (two excimers) with no rising component, thus showing that all pyrene groups are encapsulated (and preassociated) into the gamma-CD cavity. In the case of the high Mw polymers, the addition of gamma-CD has been found to change the level of polymer interaction from pure intramolecular (water in the absence of cyclodextrin) to a coexistence of intra- with intermolecular interactions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1402-1415, 200

Feigenbaum networks

We study dynamical systems composed of a set of linearly coupled quadratic maps which, if uncoupled, would be on the Feigenbaum accumulation point. For two units we prove the existence of an infinite number of sinks for an open set of coupling parameters. In the limit of many units a mean field analysis also implies the stabilization in periodic orbits of, at least, a subset of the coupled units. Possible applications in the fields of control of chaos, signal processing through complex dynamics and as models of self-organization, are discussed