Transparency of 0.2% GdCl3 Doped Water in a Stainless Steel Test Environment

The possibility of neutron and neutrino detection using water Cerenkov detectors doped with gadolinium holds the promise of constructing very large high-efficiency detectors with wide-ranging application in basic science and national security. This study addressed a major concern regarding the feasibility of such detectors: the transparency of the doped water to the ultraviolet Cerenkov light. We report on experiments conducted using a 19-meter water transparency measuring instrument and associated materials test tank. Sensitive measurements of the transparency of water doped with 0.2% GdCl3 at 337nm, 400nm and 420nm were made using this instrument. These measurements indicate that GdCl3 is not an appropriate dopant in stainless steel constructed water Cerenkov detectors.Comment: 17 pages, 11 figures, corrects typos, changes formatting, adds error bars to figure

Non-Gaussianity and large-scale structure in a two-field inflationary model

Single field inflationary models predict nearly Gaussian initial conditions and hence a detection of non-Gaussianity would be a signature of the more complex inflationary scenarios. In this paper we study the effect on the cosmic microwave background and on large scale structure from primordial non-Gaussianity in a two-field inflationary model in which both the inflaton and curvaton contribute to the density perturbations. We show that in addition to the previously described enhancement of the galaxy bias on large scales, this setup results in large-scale stochasticity. We provide joint constraints on the local non-Gaussianity parameter $\tilde f_{\rm NL}$ and the ratio $\xi$ of the amplitude of primordial perturbations due to the inflaton and curvaton using WMAP and SDSS data

Nonlinear Structure Formation, Backreaction and Weak Gravitational Fields

There is an ongoing debate in the literature concerning the effects of averaging out inhomogeneities (``backreaction'') in cosmology. In particular, some simple models of structure formation studied in the literature seem to indicate that the backreaction can play a significant role at late times, and it has also been suggested that the standard perturbed FLRW framework is no longer a good approximation during structure formation, when the density contrast becomes nonlinear. In this work we use Zalaletdinov's covariant averaging scheme (macroscopic gravity or MG) to show that as long as the metric of the Universe can be described by the perturbed FLRW form, the corrections due to averaging remain negligibly small. Further, using a fully relativistic and reasonably generic model of pressureless spherical collapse, we show that as long as matter velocities remain small (which is true in our model), the perturbed FLRW form of the metric can be explicitly recovered. Together, these results imply that the backreaction remains small even during nonlinear structure formation, and we confirm this within the toy model with a numerical calculation.Comment: 8 pages, eas format, talk given at July 2008 CRAL-IPNL conference on "Dark Energy and Dark Matter

Uso da ferramenta Pentaho BI-Server para obtenção de informações gerenciais do Sistema Aberto e Integrado de Informação em Agricultura (Sabiia).

Nesse contexto de ambiente de informação, acesso e extração de informações gerenciais da base de dados do sistema Sabiia, o projeto definiu como objetivo estratégico o uso de soluções livres de BI para obtenção de informações e respostas gerenciais, tais como: Quantos provedores de dados estão sendo coletados ? Quais são os provedores de dados coletados em cada país ? Qual é a quantidade de consultas efetuadas por ano, mês e país no sistema ? Quais são as buscas mais efetuadas no sistema ? Devido à maior experiência da Embrapa Informática Agropecuária no uso de soluções livres e arquitetura Java Enterprise Edition (Java EE)4 em projetos de pesquisa, o projeto Sabiia optou pelo uso da ferramenta Pentaho-BI Server5 como solução de (BI) para obtenção de informações gerenciais

Uso de software livre para implementação de provedores de serviços OAI-PMH: caso do provedor de serviços Sabiia.

(LEITE et al., 2009) destacam que a Empresa Brasileira de Pesquisa Agropecuária (Embrapa), por meio do Sistema Embrapa de Bibliotecas (SEB), definiu como objetivo estratégico a inserção da empresa no movimento Acesso Aberto (Open Access Initiative) para armazenamento e disseminação da informação técnico-científica produzida pela área de Pesquisa e Desenvolvimento (P&D) e a criação do provedor de serviços Sistema Aberto e Integrado de Informação em Agricultura (Sabiia), caracterizado como sistema responsável pela integração de todos os dados provenientes de repositórios institucionais, periódicos científicos, bibliotecas digitais e outros, tanto internos quanto externos, de interesse da Embrapa. O presente trabalho focará as soluções livres escolhidas para a construção da ferramenta

Nuclear Photoabsorption at Photon Energies between 300 and 850 Mev

We construct the formula for the photonuclear total absorption cross section using the projection method and the unitarity relation. Our treatment is very effective when interference effects in the absorption processes on a nucleon are strong. The disappearance of the peak around the position of the $D_{13}$ resonance in the nuclear photoabsorption can be explained with the cooperative effect of the interference in two-pion production processes,the Fermi motion, the collision broadenings of $\Delta$ and $N^*$, and the pion distortion in the nuclear medium. The change of the interference effect by the medium plays an important role.Comment: 22pages,7figures,revtex