Interacting spin 0 fields with torsion via Duffin-Kemmer-Petiau theory

Here we study the behaviour of spin 0 sector of the DKP field in spaces with torsion. First we show that in a Riemann-Cartan manifold the DKP field presents an interaction with torsion when minimal coupling is performed, contrary to the behaviour of the KG field, a result that breaks the usual equivalence between the DKP and the KG fields. Next we analyse the case of Teleparallel Equivalent of General Relativity Weitzenbock manifold, showing that in this case there is a perfect agreement between KG and DKP fields. The origins of both results are also discussed.Comment: 10 pages, no figures, uses REVTEX. Changes in the presentation, minor misprints and one equation corrected. References updated. To appear in General Relativity and Gravitatio

Sistema de produção de tambaqui em tanques-rede.

bitstream/item/86400/1/Digitalizar0143.pd

Cultivo de tambaqui sob gaiolas flutuantes.

bitstream/item/64479/1/Oriental-RecBas1.pd

Criação de tambaqui Colossoma macropomum em gaiolas flutuantes no município de São Sebastião da Boa Vista, ilha do Marajó, Estado do Pará.

bitstream/item/57778/1/CPATU-PA206.pd

A variabilidade genética do feijoeiro (Phaseolus vulgaris L.): aplicações nos estudos das interações simbióticas e patogênicas.

A variabilidade genética da hospedeira. Como esta variabilidade pode ser manipulada? A simbiose com o rizóbio. Melhoramento genético do feijoeiro visando a fixação biológica de nitrogênio. As interações e sua utilização no melhoramento da planta.bitstream/CNPAB-2010/27393/1/doc126.pd

Spikes in Cosmic Crystallography

If the universe is multiply connected and small the sky shows multiple images of cosmic objects, correlated by the covering group of the 3-manifold used to model it. These correlations were originally thought to manifest as spikes in pair separation histograms (PSH) built from suitable catalogues. Using probability theory we derive an expression for the expected pair separation histogram (EPSH) in a rather general topological-geometrical-observational setting. As a major consequence we show that the spikes of topological origin in PSH's are due to translations, whereas other isometries manifest as tiny deformations of the PSH corresponding to the simply connected case. This result holds for all Robertson-Walker spacetimes and gives rise to two basic corollaries: (i) that PSH's of Euclidean manifolds that have the same translations in their covering groups exhibit identical spike spectra of topological origin, making clear that even if the universe is flat the topological spikes alone are not sufficient for determining its topology; and (ii) that PSH's of hyperbolic 3-manifolds exhibit no spikes of topological origin. These corollaries ensure that cosmic crystallography, as originally formulated, is not a conclusive method for unveiling the shape of the universe. We also present a method that reduces the statistical fluctuations in PSH's built from simulated catalogues.Comment: 25 pages, LaTeX2e. References updated. To appear in Int. J. Mod. Phys. D (2002) in the present for

High Resolution 4.7 um Keck/NIRSPEC Spectra of Protostars. I: Ices and Infalling Gas in the Disk of L1489 IRS

We explore the infrared M band (4.7 um) spectrum of the class I protostar L1489 IRS in the Taurus Molecular Cloud. This is the highest resolution wide coverage spectrum at this wavelength of a low mass protostar observed to date (R=25,000; Dv=12 km/s). Many narrow absorption lines of gas phase 12CO, 13CO, and C18O are detected, as well as a prominent band of solid 12CO. The gas phase 12CO lines have red shifted absorption wings (up to 100 km/s), likely originating from warm disk material falling toward the central object. The isotopes and the 12CO line wings are successfully fitted with a contracting disk model of this evolutionary transitional object (Hogerheijde 2001). This shows that the inward motions seen in millimeter wave emission lines continue to within ~0.1 AU from the star. The colder parts of the disk are traced by the prominent CO ice band. The band profile results from CO in 'polar' ices (CO mixed with H2O), and CO in 'apolar' ices. At the high spectral resolution, the 'apolar' component is, for the first time, resolved into two distinct components, likely due to pure CO and CO mixed with CO2, O2 and/or N2. The ices have probably experienced thermal processing in the upper disk layer traced by our pencil absorption beam: much of the volatile 'apolar' ices has evaporated and the depletion factor of CO onto grains is remarkably low (~7%). This study shows that high spectral resolution 4.7 um observations provide important and unique information on the dynamics and structure of protostellar disks and the evolution of ices in these disks.Comment: 11 pages, 6 figures Scheduled to appear in ApJ 568 n2, 1 April 200

Stellar variability in low-extinction regions towards the Galactic Bulge

Intensive monitoring of low-extinction windows towards the galactic bulge has provided in the last years valuable information for studies about the dynamics, kinematics and formation history of this part of the galaxy, mainly by characterizing the bulge stellar populations (Paczy\'nski, 1996). Since 1997, we have been conducting an intensive photometric-astrometric survey of the galactic bulge, with the monitoring of about 120000 stars in 12 windows uniformly distributed in galactic latitude and longitude (Blanco & Terndrup, 1989 e Blanco, 1988) never before submitted to this kind of survey. For this purpose, we have used the IAG/USP CCD Meridian Circle of the Abrah\~ao de Moraes Observatory. The main objective of this work is the identification and classification of variable objects. In this work we present the set up and development of the necessary tools for a project like this and the posterior analysis of our data. We briefly describe the construction of a program to organize and detect variables among the observed stars, including real time alerts (for variations greater than 0.3 magnitudes). The preliminary analysis after the processing of 76 nights of observation yielded 479 variable stars, from which 96.7 % of them are new. We discuss the preliminary classification of this variables, based on: a) the observed amplitude of variation; b) the shape of light curve; c) the expected variable classes among our data and d) the calculated periods, whenever possible. Finally, we discuss the future perspectives for the project and for the applications and analysis of the discovered variable stars.Comment: 10 pages, 14 figures. Accepted by A&A