Produtividade e valor nutritivo das frações forrageiras da erva-sal (Atriplex nummularia) irrigada com quatro diferentes volumes de efluentes da criação de tilápia em água salobra.

Avaliou-se a produtividade e o valor nutritivo da erva sal cultivada sob irrigação de quatro volumes de efluentes oriundos de viveiros de criação de tilápia (Oreochromis sp.), cuja salinidade média durante o cultivo foi de 8,29 dS m-l. O delíneamento experimental foi de blocos ao acaso com quatrO tratamentos e três repetições. Os tratamentos de 75, 150, 225 e 300 litros de efluente por planta foram aplicados semanalmente. Os diferentes volumes de água influenciaram a produtividade de matéria seca, mas não influenciaram a composição químico-bromatológica e digestibilidade in vitro da matéria seca em qualquer dos componentes da planta. Os teores de minerais (MM) mostraram-se elevados nas folhas, requerendo assim, cuidados com dietas contendo alta proporção de folhas de erva sal, a ponto de não permitir que teores elevados de sais sejam comprometedores do consumo animal. O teor de proteína bruta e digestibilidade ín vítro da matéria seca médio dos tratamentos para as folhas foi de 15,1 e 67,9%, respectivamente. Ramos e Caules apresentaram elevados teores de FDN e FDA e baixos valores de DIVMS. Independente do nível de água aplicado, a erva sal mostrou características forrageiras desejável, que podem ainda ser melhoradas com práticas de manejo voltadas para tal fim

A photometric and spectroscopic survey of solar twin stars within 50 parsecs of the Sun: I. Atmospheric parameters and color similarity to the Sun

Solar twins and analogs are fundamental in the characterization of the Sun's place in the context of stellar measurements, as they are in understanding how typical the solar properties are in its neighborhood. They are also important for representing sunlight observable in the night sky for diverse photometric and spectroscopic tasks, besides being natural candidates for harboring planetary systems similar to ours and possibly even life-bearing environments. We report a photometric and spectroscopic survey of solar twin stars within 50 pc of the Sun. Hipparcos absolute magnitudes and (B-V)_Tycho colors were used to define a 2 sigma box around the solar values, where 133 stars were considered. Additional stars resembling the solar UBV colors in a broad sense, plus stars present in the lists of Hardorp, were also selected. All objects were ranked by a color-similarity index with respect to the Sun, defined by uvby and BV photometry. Moderately high-resolution, high-S/N spectra were used for a subsample of equatorial-southern stars to derive Teff, log g, and [Fe/H] with average internal errors better than 50 K, 0.20 dex, and 0.08 dex, respectively. Ages and masses were estimated from theoretical HR diagrams. The color-similarity index proved very successful. We identify and rank new excellent solar analogs, which are fit to represent the Sun in the night sky. Some of them are faint enough to be of interest for moderately large telescopes. We also identify two stars with near-UV spectra indistinguishable from the Sun's. We present five new "probable" solar twin stars, besides five new "possible" twins. Masses and ages for the best solar twin candidates lie very close to the solar values, but chromospheric activity levels range somewhat. We propose that the solar twins be emphasized in the ongoing searches for extra-solar planets and SETI searches.Comment: 25 pages, 15 figures, 14 table

A Link Between the Semi-Major Axis of Extrasolar Gas Giant Planets and Stellar Metallicity

The fact that most extrasolar planets found to date are orbiting metal-rich stars lends credence to the core accretion mechanism of gas giant planet formation over its competitor, the disc instability mechanism. However, the core accretion mechanism is not refined to the point of explaining orbital parameters such as their unexpected semi-major axes and eccentricities. We propose a model, which correlates the metallicity of the host star with the original semi-major axis of its most massive planet, prior to migration, considering that the core accretion scenario governs giant gas planet formation. The model predicts that the optimum regions for planetary formation shift inward as stellar metallicity decreases, providing an explanation for the observed absence of long period planets in metal-poor stars. We compare our predictions with the available data on extrasolar planets for stars with masses similar to the mass of the Sun. A fitting procedure produces an estimate of what we define as the Zero Age Planetary Orbit (ZAPO) curve as a function of the metallicity of the star. The model also hints that the lack of planets circling metal-poor stars may be partly caused by an enhanced destruction probability during the migration process, since the planets lie initially closer to the central stars.Comment: Nature of the replacement: According to recent simulations, the temperature profile, T, is more adequately reproduced by beta = 1 rather than beta = 2. We have introduced a distance scale factor that solves the very fast drop of T for low metallicity and introduces naturally the inferior distance limit of our ZAPO. Under this modification all the fitting process was altere

The gravitational S-matrix

We investigate the hypothesized existence of an S-matrix for gravity, and some of its expected general properties. We first discuss basic questions regarding existence of such a matrix, including those of infrared divergences and description of asymptotic states. Distinct scattering behavior occurs in the Born, eikonal, and strong gravity regimes, and we describe aspects of both the partial wave and momentum space amplitudes, and their analytic properties, from these regimes. Classically the strong gravity region would be dominated by formation of black holes, and we assume its unitary quantum dynamics is described by corresponding resonances. Masslessness limits some powerful methods and results that apply to massive theories, though a continuation path implying crossing symmetry plausibly still exists. Physical properties of gravity suggest nonpolynomial amplitudes, although crossing and causality constrain (with modest assumptions) this nonpolynomial behavior, particularly requiring a polynomial bound in complex s at fixed physical momentum transfer. We explore the hypothesis that such behavior corresponds to a nonlocality intrinsic to gravity, but consistent with unitarity, analyticity, crossing, and causality.Comment: 46 pages, 10 figure

On the comparison of results regarding the post-Newtonian approximate treatment of the dynamics of extended spinning compact binaries

A brief review is given of all the Hamiltonians and effective potentials calculated hitherto covering the post-Newtonian (pN) dynamics of a two body system. A method is presented to compare (conservative) reduced Hamiltonians with nonreduced potentials directly at least up to the next-to-leading-pN order.Comment: Conference proceedings for the 7th International Conference on Gravitation and Cosmology (ICGC2011), 4 page

Next to leading order spin-orbit effects in the motion of inspiralling compact binaries

Using effective field theory (EFT) techniques we calculate the next-to-leading order (NLO) spin-orbit contributions to the gravitational potential of inspiralling compact binaries. We use the covariant spin supplementarity condition (SSC), and explicitly prove the equivalence with previous results by Faye et al. in arXiv:gr-qc/0605139. We also show that the direct application of the Newton-Wigner SSC at the level of the action leads to the correct dynamics using a canonical (Dirac) algebra. This paper then completes the calculation of the necessary spin dynamics within the EFT formalism that will be used in a separate paper to compute the spin contributions to the energy flux and phase evolution to NLO.Comment: 25 pages, 4 figures, revtex4. v2: minor changes, refs. added. To appear in Class. Quant. Gra

Capacitação e atualização tecnológica das famílias do Projeto Quintais Sustentáveis.

O Projeto Quintais Sustentáveis nasceu da interlocução com as demandas da sociedade no estado de Roraima por profissionais ligados ao tema do rural e do agrário, especialmente, no que tange à projetos sociais, ainda que técnico-produtivos, mas que foca em linhas de atuação que tenham a perspectiva de desenvolvimento local da agricultura familiar a partir dos atores e potencialidades locais

Fórum de Agricultura Familiar de Roraima: A Experiência de Construção Social com Foco no Desenvolvimento Territorial.

presente artigo procurou abordar a estratégia de trabalho e ação que os Fóruns de Agricultura Familiar do Estado de Roraima, no Norte do Brasil, vêm procurando incentivar, no intuito de focalizar processos de desenvolvimento local e regional de forma participativa, na ótica da territorialidade, nos quais as representações dos agricultores familiares estejam à frente da articulação e do encaminhamento das demandas que afetam a vida e a dinâmica social da agricultura familiar, direcionadas ao Estado e às diversas esferas, seja em termos de sistemas de produção, seja em questões relacionadas a políticas públicas, acesso a recursos, canais de comercialização e qualidade de vida

Quintais Sustentáveis: alternativa para a segurança alimentar e nutricional de famílias de baixa renda na perspectiva da agricultura periurbana de Boa Vista, RR.

O Projeto Quintais Sustentáveis nasceu da interlocução com as demandas da sociedade no estado de Roraima por profissionais ligados ao tema do rural e agrário, especialmente, no que tange a projetos sociais, ainda que técnico produtivos, mas que foca em linhas de atuação de projetos sociais que tenham a perspectiva de desenvolvimento local da agricultura familiar a partir dos atores e potencialidades locais