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

Cosmic Background of Gravitational Waves from Rotating Neutron Stars

The extragalactic background of gravitational waves produced by tri-axial rotating neutron stars was calculated, under the assumption that the properties of the underlying pulsar population are the same of those of the galactic population, recently derived by Regimbau & de Freitas Pacheco (2000). For an equatorial ellipticity of $\epsilon$ = 10$^{-6}$, the equivalent density parameter due to gravitational waves has a maximum amplitude in the range 2$\times10^{-11}-3\times10^{-9}$, around 0.9-1.5 kHz. The main reasons affecting the theoretical predictions are discussed. This background is comparable to that produced by the ''ring-down'' emission from distorted black holes. The detection possibility of this background by a future generation of gravitational antennas is also examined.Comment: accepted for publication in Astronomy & Astrophysic

Relação entre o intervalo de partos e o custo total de produção de leite por vaca no rebanho.

O intervalo de partos foi a variavel de maior impacto nos custos de producao de vacas da raca holandesa de primeira e segunda lactacoes, seguida da producao total de leite. A idade ao primeiro parto e o valor genetico relacionaram-se apenas com o custo de producao de vacas holandesas de primeira lactacao. No caso de vacas mesticas (HZ) de primeira e segunda lactacao apenas o intervalo de partos e a producao total de leite relacionaram-se com o custo total.Resumo expandido

Quark core formation in spinning-down pulsars

Pulsars spin-down due to magnetic torque reducing its radius and increasing the central energy density. Some pulsar which are born with central densities close to the critical value of quark deconfinement may undergo a phase transition and structural re-arrengement. This process may excite oscillation modes and emmit gravitational waves. We determine the rate of quark core formation in neutron stars using a realistic population synthesis code.Comment: Proceedings of the 2nd International Workshop on Astronomy and Relativistic Astrophysics, to appear in IJMP

Searching Gravitational Waves from Pulsars, Using Laser Beam Interferometers

We use recent population synthesis results to investigate the distribution of pulsars in the frequency space, having a gravitational strain high enough to be detected by the future generations of laser beam interferometers. We find that until detectors become able to recover the entire population, the frequency distribution of the 'detectable' population will be very dependent on the detector noise curve. Assuming a mean equatorial deformation $\epsilon =10^{-6}$, the optimal frequency is around 450 Hz for interferometers of the first generation (LIGO or VIRGO) and shifts toward 85 Hz for advanced detectors. An interesting result for future detection stategies is the significant narrowing of the distribution when improving the sensitivity: with an advanced detector, it is possible to have 90% of detection probability while exploring less than 20% of the parameter space (7.5% in the case of $\epsilon =10^{-5}$). In addition, we show that in most cases the spindown of 'detectable' pulsars represents a period shift of less than a tens of nanoseconds after one year of observation, making them easier to follow in the frequency space.Comment: 5 pages, 3 figures accepted for publication in Astronomy & Astrophysic

Distribuição das raízes do coqueiro-anão verde para o manejo da irrigação e a aplicação de fertilizantes.

O conhecimento da distribuicao do sistema radicular de uma cultura constitui-se em uma importate ferramenta para a otimizacao de praticas agricolas como a irrigacao e a adubacao; O sistema radicular do coqueiro; Distribuicao das raizes do coqueiro-anao em sequeiro; Aplicacao de fertilizantes; Distribuicao das raizes do coqueiro-anao verde irrigado; Informacoes para o manejo da irrigacao do coqueiro-anao; Profundidade efetiva do sistema radicular; Area molhada na irrigacao localizacao; Localizacao de sensores da umidade do solo; Informacoes para aplicacao de fertilizantesbitstream/CNPAT-2010/8607/1/Ci-016.pd