ASCA Slew Survey

We are systematically analyzing ASCA GIS data taken during the satellite attitude maneuver operation. Our motivation is to search for serendipitous hard X-ray sources and make the ASCA Slew Survey catalog. During its operational life from 1993 February to 2000 July, ASCA carried out more than 2,500 maneuver operations, and total exposure time during the maneuver was ~415 ksec after data screening. Preliminary results are briefly reported.Comment: Proceedings for "X-ray surveys in the light of new observations", Santander (Spain), 2002 September. 1 pag

The X-ray Line Emission from the Supernova Remnant W49B

The Galactic supernova remnant W49B has one of the most impressive X-ray emission line spectra obtained with the Advanced Satellite for Cosmology and Astronomy (ASCA). We use both plasma line diagnostics and broadband model fits to show that the Si and S emission lines require multiple spectral components. The spectral data do not necessarily require individual elements to be spatially stratified, as suggested by earlier work, although when ASCA line images are considered, it is possible that Fe is stratified with respect to Si and S. Most of the X-ray emitting gas is from ejecta, based on the element abundances required, but is surprisingly close to being in collisional ionization equilibrium. A high ionization age implies a high internal density in a young remnant. The fitted emission measure for W49B indicates a minimum density of 2 cm^-3, with the true density likely to be significantly higher. W49B probably had a Type Ia progenitor, based on the relative element abundances, although a low-mass Type II progenitor is still possible. We find persuasive evidence for Cr and possibly Mn emission in the ASCA spectrum--the first detection of these elements in X-rays from a cosmic source.Comment: 22 pages incl 8 postscript figures, to appear in Ap

Aclimatação e quarentena: manejos muitas vezes esquecidos - quando não realizados, podem representar grandes perdas.

Quem nunca comprou um peixe e ao chegar em casa colocouo direto no aquário e, em um período compreendido entre quatro e sete dias, ele morreu ou todos os peixes do aquário começam a adoecer? Bom, esse é um cenário bem mais comum do que se imagina. Isso ocorre principalmente devido à falta de cuidados e de manejos adequados para a manutenção desse animal em cativeiro.bitstream/item/123109/1/12-aclimatacao-e-quarentena.pd

Nambu-Goldstone Mechanism in Real-Time Thermal Field Theory

In a one-generation fermion condensate scheme of electroweak symmetry breaking, it is proven based on Schwinger-Dyson equation in the real-time thermal field theory in the fermion bubble diagram approximation that, at finite temperature $T$ below the symmetry restoration temperature $T_c$, a massive Higgs boson and three massless Nambu-Goldstone bosons could emerge from the spontaneous breaking of electroweak group $SU_L(2)\times U_Y(1) \to U_Q(1)$ if the two fermion flavors in the one generation are mass-degenerate, thus Goldstone Theorem is rigorously valid in this case. However, if the two fermion flavors have unequal masses, owing to "thermal flactuation", the Goldstone Theorem will be true only approximately for a very large momentum cut-off $\Lambda$ in zero temperature fermion loop or for low energy scales. All possible pinch singularities are proven to cancel each other, as is expected in a real-time thermal field theory.Comment: 11 pages, revtex, no figure, Phys. Rev. D, to appea

Identity of the imaginary-time and real-time thermal propagators for scalar bound states in a one-generation Nambu-Jona-Lasinio model

By rigorous reanalysis of the results, we have proven that the propagators at finite temperature for scalar bound states in one-generation fermion condensate scheme of electroweak symmetry breaking are in fact identical in the imaginary-time and the real-time formalism. This dismisses the doubt about possible discrepancy between the two formalisms in this problem. Identity of the derived thermal transformation matrices of the real-time matrix propagators for scalar bound states without and with chemical potential and the ones for corresponding elementary scalar particles shows similarity of thermodynamic property between the two types of particles. Only one former inference is modified, i.e. when the two flavors of fermions have unequal nonzero masses, the amplitude of the composite Higgs particle will decay instead grow in time.Comment: 5 pages, revtex4, no figure

Aumentar a produção de peixes ornamentais cultivados: um desafio ambiental e econômico

O comércio internacional de organismos aquáticos ornamentais cresce, desde 1985, a uma taxa média anual de 14%. Mundialmente os maiores produtores de peixes ornamentais em cativeiro estão localizados em Singapura, Malásia, Hong Kong,Tailândia, Indonésia, Japão, Israel e sul dos Estados Unidos, que contribuem com cerca de 90% deste setor no comércio.bitstream/item/123077/1/07-Aumentar-a-producao.pd

Mechanisms for High-frequency QPOs in Neutron Star and Black Hole Binaries

We explain the millisecond variability detected by Rossi X-ray Timing Explorer (RXTE) in the X-ray emission from a number of low mass X-ray binary systems (Sco X-1, 4U1728-34, 4U1608-522, 4U1636-536, 4U0614+091, 4U1735-44, 4U1820-30, GX5-1 and etc) in terms of dynamics of the centrifugal barrier, a hot boundary region surrounding a neutron star. We demonstrate that this region may experience the relaxation oscillations, and that the displacements of a gas element both in radial and vertical directions occur at the same main frequency, of order of the local Keplerian frequency. We show the importance of the effect of a splitting of the main frequency produced by the Coriolis force in a rotating disk for the interpretation of a spacing between the QPO peaks. We estimate a magnitude of the splitting effect and present a simple formula for the whole spectrum of the split frequencies. It is interesting that the first three lowest-order overtones fall in the range of 200-1200 Hz and match the kHz-QPO frequencies observed by RXTE. Similar phenomena should also occur in Black Hole (BH) systems, but, since the QPO frequency is inversely proportional to the mass of a compact object, the frequency of the centrifugal-barrier oscillations in the BH systems should be a factor of 5-10 lower than that for the NS systems. The X-ray spectrum formed in this region is a result of upscattering of a soft radiation (from a disk and a NS surface) off relatively hot electrons in the boundary layer. We also briefly discuss some alternative QPO models, including a possibility of acoustic oscillations in the boundary layer, the proper stellar rotation, and g-mode disk oscillations.Comment: The paper is coming out in the Astrophysical Journal in the 1st of May issue of 199

Gap equation in scalar field theory at finite temperature

We investigate the two-loop gap equation for the thermal mass of hot massless $g^2\phi^4$ theory and find that the gap equation itself has a non-zero finite imaginary part. This indicates that it is not possible to find the real thermal mass as a solution of the gap equation beyond $g^2$ order in perturbation theory. We have solved the gap equation and obtain the real and the imaginary part of the thermal mass which are correct up to $g^4$ order in perturbation theory.Comment: 13 pages, Latex with axodraw, Minor corrections, Appendix adde

Densidade de estocagem e manejo alimentar na criação de Acarás-bandeira.

O comércio de peixes ornamentais é considerado um dos setores mais lucrativos da piscicultura brasileira e vem se expandindo rapidamente com o aumento na demanda mundial, sendo o acará-bandeira (Pterophyllum scalare) uma das espécies nativas de água doce de maior procura no mercado nacional.bitstream/item/122979/1/Densidade-de-estocagem-COT145.pd