Propagation of mesons in asymmetric nuclear matter in a density dependent coupling model

We study the propagation of the light mesons sigma, omega, rho, and a0(980) in dense hadronic matter in an extended derivative scalar coupling model. Within the scheme proposed it is possible to unambiguously define effective density-dependent couplings at the Lagrangian level. We first apply the model to study asymmetric nuclear matter with fixed isospin asymmetry, and then we pay particular attention to hypermatter in beta-equilibrium. The equation of state and the potential contribution to the symmetry coefficient arising from the mean field approximation are investigated.Comment: 17 pages, 15 PostScript figure

Landau parameters for isospin asymmetric nuclear matter based on a relativistic model of composite and finite extension nucleons

We study the properties of cold asymmetric nuclear matter at high density, applying the quark meson coupling model with excluded volume corrections in the framework of the Landau theory of relativistic Fermi liquids. We discuss the role of the finite spatial extension of composite baryons on dynamical and statistical properties such as the Landau parameters, the compressibility, and the symmetry energy. We have also calculated the low lying collective eigenfrequencies arising from the collisionless quasiparticle transport equation, considering both unstable and stable modes. An overall analysis of the excluded volume correlations on the collective properties is performed.Comment: 24 pages, 6 figure

Exposure to polychlorinated biphenyls and hexachlorobenzene, semen quality and testicular cancer risk

PURPOSE: We carried out a case-control study to investigate the possible role of occupational and environmental exposure to endocrine disruptors in the onset of testicular cancer (TC). METHODS: We evaluated 125 TC patients and 103 controls. Seminal fluid examination and organochlorine analysis were performed in all subjects. Cases and controls were also interviewed using a structured questionnaire to collect demographic information, residence, andrological medical history and dietary information. RESULTS: We found that a higher level of reproductive tract birth defects was associated with a higher risk of TC. With regard to diet, cases reported a higher consumption of milk and dairy products than controls. Overall, there was a statistically significant increase in TC risk in cases with detectable values of total polychlorinated organic compounds against controls (14.4 vs. 1.0 %; p < 0.001). TC patients with detectable levels of organochlorines had lower mean semen parameters than those with undetectable levels, although this difference was not statistically significant. CONCLUSION: The International Agency for Research on Cancer recently included dioxin-like polychlorinated biphenyls (PCBs) in Group 1 of known human carcinogens. Our study confirmed and identified various risk factors for testicular cancer: cryptorchidism, consumption of milk and dairy products, parents' occupation and serum concentration of hexachlorobenzene and PCBs and, for the first time, we showed the correlation between semen quality and the serum concentration of these pollutants

Presence of iron in polymers extruded with corrosive contaminants or abrasive fillers

Off-site measurements of the dimensions of extruder screws are used to monitor their wear. This wear causes the presence of metals in the processed polymer. We detected the presence of iron in polymers processed with corrosive contaminants or abrasive fillers. To this end we processed poly(ethylene terephthalate), PET, pure or contaminated with poly(vinyl chloride), PVC, and other thermoplastics reinforced with glass fibers, talc or vegetal fibers, and analyzed the metals in the processed materials by X-ray fluorescence spectroscopy. We show that iron dispersed in the polymer melt is generated by corrosion from the PET contaminated with PVC and by erosion from abrasive fillers. The contents of iron in the extruded polymers clearly indicate equipment wear. This contaminant acts as a polymer pro-degradant, decreasing its lifetime. Additionally, we show that the lower concentration of iron for composites with vegetal fibers indicates a lower abrasion in comparison to talc and glass fibers292FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP2010/17804-