Brane World Cosmology In Jordan-Brans-Dicke Theory

We consider the embedding of 3+1 dimensional cosmology in 4+1 dimensional Jordan-Brans-Dicke theory. We show that exponentially growing and power law scale factors are implied. Whereas the 4+1 dimensional scalar field is approximately constant for each, the effective 3+1 dimensional scalar field is constant for exponentially growing scale factor and time dependent for power law scale factor.Comment: 11 page

Supergravity Inflation on the Brane

We study N=1 Supergravity inflation in the context of the braneworld scenario. Particular attention is paid to the problem of the onset of inflation at sub-Planckian field values and the ensued inflationary observables. We find that the so-called $\eta$-problem encountered in supergravity inspired inflationary models can be solved in the context of the braneworld scenario, for some range of the parameters involved. Furthermore, we obtain an upper bound on the scale of the fifth dimension, M_5 \lsim 10^{-3} M_P, in case the inflationary potential is quadratic in the inflaton field, $\phi$. If the inflationary potential is cubic in $\phi$, consistency with observational data requires that $M_5 \simeq 9.2 \times 10^{-4} M_P$.Comment: 6 pages, 1 figure, to appear in Phys. Rev.

A Review Characterizing 25 Ecosystem Challenges to Be Addressed by an Ecosystem Approach to Fisheries Management in Europe

The impacts of fisheries on ocean resources are no longer considered in isolation but should account for broader ecosystem effects. However, ongoing ecosystem-wide changes added to the inherent dynamics of marine ecosystems, create challenges for fisheries and fisheries management by affecting our ability to ensure future fishing opportunities and sustainable use of the seas. By reviewing a corpus of fisheries science literature, we contribute to informing managers and policymakers with considerations of the various threats to fisheries and the marine ecosystems that support them. We identify and describe 25 ecosystem challenges and 7 prominent families of management options to address them. We capture the challenges acting within three broad categories: (i) fishing impacts on the marine environments and future fishing opportunities, (ii) effects of environmental conditions on fish and fishing opportunities, and (iii) effects of context in terms of socioeconomics, fisheries management, and institutional set-up on fisheries. Our review shows that, while most EU fisheries are facing a similar array of challenges, some of them are specific to regions or individual fisheries. This is reflected in selected regional cases taking different perspectives to exemplify the challenges along with fishery-specific cases. These cases include the dramatic situation of the Baltic Sea cod, facing an array of cumulative pressures, the multiple and moving ecosystem interactions that rely on the North Sea forage fish facing climate change, the interaction of fishing and fish stocks in a fluctuating mixed fishery in the Celtic Sea, the bycatch of marine mammals and seabirds and habitat degradation in the Bay of Biscay, and finally the under capacity and lack of fundamental knowledge on some features of the EU Outermost Regions. In addition to these ecoregion specific findings, we discuss the outcomes of our review across the whole of European waters and we conclude by recognizing that there are knowledge gaps regarding the direction of causality, nonlinear responses, and confounding effects. All of the challenges we identify and characterize may guide further data collection and research coordination to improve our fundamental understanding of the system and to monitor real changes within it, both of which are required to inform an Ecosystem Approach to Fisheries Management (EAFM). An European EAFM could build upon an array of management measures currently tailored for fisheries management only, including promoting funding interdisciplinary research and ecosystem monitoring. Such integrative management should reduce uncertainties in environmental, social and economic trends, and lower the risk for disruptive events or ecosystem effects with far-reaching consequences, including a shift toward less productive marine ecosystems.En prens

Fine-Tuning Solution for Hybrid Inflation in Dissipative Chaotic Dynamics

We study the presence of chaotic behavior in phase space in the pre-inflationary stage of hybrid inflation models. This is closely related to the problem of initial conditions associated to these inflationary type of models. We then show how an expected dissipative dynamics of fields just before the onset of inflation can solve or ease considerably the problem of initial conditions, driving naturally the system towards inflation. The chaotic behavior of the corresponding dynamical system is studied by the computation of the fractal dimension of the boundary, in phase space, separating inflationary from non-inflationary trajectories. The fractal dimension for this boundary is determined as a function of the dissipation coefficients appearing in the effective equations of motion for the fields.Comment: 10 pages, 4 eps figures (uses epsf), Revtex. Replaced with version to match one in press Physical Review

Biology and fertility life table of Mahanarva fimbriolata (Stål) (Hemiptera: Cercopidae) in sugarcane

Mahanarva fimbriolata (Stål) (Hemiptera: Cercopidae) is the most important pest of sugarcane harvested without the use of fire to burn leaf trash. Its biology was studied for three generations in order to obtain basic information about its life cycle. A fertility life table was used to evaluate the quality of laboratory-reared insects. Data were obtained at a temperature of 25 ± 1ºC, RH of 70 ± 10%, and a 14-hour photophase. The incubation period lasted 21 days with a viability of 81%; the nymph stage had a duration of 37 days, with a 94% viability; the male and female longevities were 18 and 23 days, respectively, with a pre-oviposition period of 5 days and an oviposition period of 16 days, with a fecundity of 342 eggs, with a life-cycle (egg-adult) of 60 days. A net reproductive rate (Ro) of 131 females produced per female per generation was measured, with a finite rate of increase (lambda) of 1.085. The fertility life table proved to be adequate to be evaluate the quality of laboratory-reared M. fimbriolata populations.A cigarrinha-das-raízes, Mahanarva fimbriolata (Stål) (Hemiptera: Cercopidae), é considerada a principal praga da cana-de-açúcar colhida sem despalha a fogo no Brasil. Neste trabalho, estudou-se sua biologia por três gerações, visando obter informações básicas sobre seu ciclo de vida. Para avaliar a qualidade dos insetos criados em laboratório utilizou-se a tabela de vida de fertilidade. Os dados foram obtidos sob temperatura de 25 ± 1ºC, UR de 70 ± 10% e fotofase de 14 horas. O período de incubação foi de 21 dias e a viabilidade de 81%; a duração da fase ninfal foi de 37 dias, com viabilidade de 94%; as longevidades de machos e de fêmeas foram de 18 e 23 dias respectivamente, com período de pré-oviposição de 5 dias e oviposição de 16 dias, com fecundidade de 342 ovos, com duração do ciclo de vida (ovo-adulto) de 60 dias. A taxa líquida de reprodução (Ro) foi de 131 fêmeas geradas por fêmea por geração e a taxa finita de aumento (lambda) de 1,085. A tabela de vida de fertilidade mostrou-se adequada para avaliar a qualidade de populações de M. fimbriolata mantidas em criação de laboratório