Gravitation Wave Emission from Radio Pulsars Revisited

We report a new pulsar population synthesis based on Monte Carlo techniques, aiming to estimate the contribution of galactic radio pulsars to the continuous gravitational wave emission. Assuming that the rotation periods of pulsars at birth have a Gaussian distribution, we find that the average initial period is 290 ms. The number of objects with periods equal to or less than 0.4 s, and therefore capable of being detected by an interferometric gravitational antenna like VIRGO, is of the order of 5100-7800. With integration times lasting between 2 and 3 yr, our simulations suggest that about two detections should be possible, if the mean equatorial ellipticity of the pulsars is $\epsilon$ =10$^{-6}$. A mean ellipticity an order of magnitude higher increases the expected number of detections to 12-18, whereas for $\epsilon < 10^{-6}$, no detections are expectedComment: accepted for publication in A&A, 9 pages, 8 figure

Ages of Elliptical Galaxies: Single versus Multi Population Interpretation

New calibrations of spectrophotometric indices of elliptical galaxies as functions of spectrophotometric indices are presented, permitting estimates of mean stellar population ages and metallicities. These calibrations are based on evolutionary models including a two-phase interstellar medium, infall and a galactic wind.Free parameters were fixed by requiring that models reproduce the mean trend of data in the color-magnitude diagram as well as in the plane of indices Hbeta-Mg2 and Mg2-. To improve the location of faint ellipticals(MB > -20) in the Hbeta-Mg2 diagram, down-sizing was introduced. An application of our calibrations to a sample of ellipticals and a comparison with results derived from single stellar population models is given. Our models indicate that mean population ages span an interval of 7-12 Gyr and are correlated with metallicities, which range from approximately half up to three times solar.Comment: 10 pages and 6 figures. Accepted for publication in Monthly Notices of the Royal Astronomical Society Main Journa

Evidence that the degree of band 3 phosphorylation modulates human erythrocytes nitric oxide efflux – in vitro model of hyperfibrinogenemia

© 2011 – IOS Press and the authors. All rights reservedRecent evidence has shown that plasma fibrinogen, a major cardiovascular risk factor, interacts with the erythrocyte membrane and acts to influence blood flow via erythrocyte nitric oxide (NO) modulation. In the present pioneer in-vitro study, whole blood samples were harvested from healthy subjects and aliquots were incubated in the absence (control aliquots) and presence of fibrinogen at different degrees of band 3 phosphorylation, and the levels of NO, nitrite, nitrate and S-nitroglutathione (GSNO) were determined. Hyperfibrinogenemia interferes with erythrocyte NO mobilization without changing its efflux in a way that seems to be dependent of the degree of band 3 phosphorylation. In presence of higher fibrinogen concentrations the NO efflux is reinforced when band 3 is phosphorylated (p < 0.001). Higher levels of nitrite, nitrate and GSNO were documented (p < 0.05). However, the mechanisms by which fibrinogen signalling modulates erythrocyte function remain to be clarified and are currently under study. These conditions may be considered an approach to be followed in blood storage for transfusions.This study was supported by grants from the FCT - Fundação para a Ciência e a Tecnologia (project reference PTDC/SAU-OSM/73449/2006

The generation and transmission of pressure fluctuations in pump suction lines.

Dissertation submitted for the degree of Doctor of Philosophy of the University of Bat