Five-Dimensional f(R) Braneworld Models

After incorporating the f(R) gravity into the general braneworld sum rules scope, it is shown that some particular class of warped five dimensional nonlinear braneworld models, which may be interesting for the hierarchy problem solution, still require a negative tension brane. For other classes of warp factors (suitable and not suitable for approaching the hierarchy problem) it is not necessary any negative brane tension in the compactification scheme. In this vein, it is argued that in the bulk f(R) gravity context, some types of warp factors may be useful for approaching the hierarchy problem and for evading the necessity of a negative brane tension in the compactification scheme.Comment: 10 pages, references updated, small modifications. Accepted for publication in Phys. Rev.

Influência de parâmetros ambientais sobre a comunidade de peixes de um afluente da margem esquerda do Rio Amazonas, Amazônia Oriental.

A distribuição de espécies sempre foi a preocupação central da ecologia. Este estudo visa compreender a relação de fatores abióticos que podem afetar a distribuição especial e sazonal da ictiofauna do rio Matapi um afluente da margem esquerda do rio Amazonas na região central do estado do Amapá, região da Amazônia Oriental, em um percurso de aproximadamente 90 km de extensão. Os peixes foram coletados bimensalmente durante um ciclo anual, utilizando rede de emalhar de diferentes tamanhos, matapis, tarrafas, linhas de mão e espinhel de fundo, em um raio de 1000 metros. Também o pH, condutividade elétrica, sólidos suspensos, transparência e outros fatores secundários como profundidade e largura do rio foram mensurados. Análise de variância com dois fatores (ANOVA- Two-way) foi usada para testar as diferenças espaciais e temporais para os fatores abióticos analisados. Foram identificadas 105 espécies, mas apenas as espécies com frequência a partir de 0,5% fizeram parte da analise, de forma que somente 29 espécies foram usadas. As matrizes foram submetidas à analise multivariada de ordenação (Co-inércia) para encontrar padrões na estrutura da ictiofauna relacionados aos diferentes fatores abióticos investigados. Os resultados indicaram parâmetros ambientais não mostraram diferenças sazonais, mas sim entre áreas de coleta. Já a ictiofauna mostrou diferenças tanto sazonal como espacial. Análise de co-inércia sumarizou eficientemente que a estrutura da ictiofauna e dos fatores ambientais ocorreram espacialmente, independentemente da sazonalidade e que os fatores determinantes dessa distribuição foram a transparência, condutividade, largura do rio e sólidos suspensos.Esses estudos podem contribuir para orientar a gestão ambiental e esforços de conservação ao longo desse importante tributário do rio Amazonas.CB19

Determinants of continuance intention to use mobile self-scanning applications in retail

Retailers are increasingly using self-service technologies to improve customer experience and reduce costs. The purpose of this study is to identify factors that could explain the level of continuance intention of mobile self-scanning applications in retail. Based on previous theoretical streams, the present study integrates technology readiness (TR) and service quality into the technology acceptance model (TAM). Using data collected through an online survey of 217 users of a mobile self-scanning application of a large supermarket chain operating in Portugal, the study uses partial least squares structural equation modeling to test the proposed hypotheses. The results indicate that the continuance usage of the self-scanning Apps is directly driven by users’ satisfaction, and perceived usefulness. Findings also show that technology readiness has a positive and significant impact on ease of use and perceived usefulness. Ease of use has a positive impact on users’ satisfaction and perceived usefulness but has no direct effect on the continuance intention to use the application. Perceived quality has a positive direct effect on satisfaction, and a positive indirect effect on continuance intention. Finally, need for interaction has a negative effect on technological readiness. This work contributes to a better understanding of the emerging market for mobile self-scanning applications in retail applications, particularly relevant in a digital transition context.info:eu-repo/semantics/acceptedVersio

Complexity and predictability of daily precipitation in a semi-arid region: an application to Ceará, Brazil

International audienceComplexity and predictability of daily precipitation in a tropical semi-arid region (Ceará State, Brazil) is assessed by applying entropy concepts. Precipitation regimes in that region depend on several dynamical forcings, the most important being the displacement and activity of the Inter-tropical Convergence Zone in the Atlantic Ocean. Topography is another important factor that influences the spatial distribution of rainfall in the region. A hierarchical approach based on sequences of events of different lengths is used to estimate complexity of daily precipitation records. It is shown that precipitation in Ceará exhibit more random than periodic sequences, which indicates a large degree of complexity. Nevertheless, there is indication of potentially inherent rules in the precipitation time-series that could ultimately improve prediction on time-scales between 9?11 days. It is suggested that synoptic-scale disturbances (1?8 days) represent important sources of rules in the precipitation regimes in this region

Endoparasitos do pacu-manteiga Mylossoma duriventre Cuvier, 1817 (Characidae) do lago Coari, região do Médio Rio Solimões, Estado do Amazonas.

Resumo simples

Caracterização da macrofauna invertebrada do solo sob diferentes fitofisionomias do Pantanal.

bitstream/item/66197/1/31473.pdfFERTBIO