Vacuum Polarization for a Massless Spin-1/2 Field in the Global Monopole Spacetime at Nonzero Temperature

In this paper we present the effects produced by the temperature in the renormalized vacuum expectation value of the zero-zero component of the energy-momentum tensor associated with massless left-handed spinor field in the pointlike global monopole spacetime. In order to develop this calculation we had to obtain the Euclidean thermal Green function in this background. Because the expression obtained for the thermal energy density cannot be expressed in a closed form, its explicit dependence on the temperature is not completely evident. So, in order to obtain concrete information about its thermal behavior, we develop a numerical analysis of our result in the high-temperature limit for specific values of the parameter $\alpha$ which codify the presence of the monopole.Comment: 22 pages, LaTex format, 5 figure

Review of a Small-scale Pelagic Longline Fishery off Northeastern Brazil

The annual catches of four small longliners operating off northeast Brazil from 1983 to 1997 were examined across different areas and locations. The total catch comprised tunas (30%), sharks (54%), billfishes (12%), and other fish species (4%). Fishing strategy and annual composition of catches showed large spatial and temporal variabilities with the dominant catches alternating among yellowfin tuna, Thunnus albacares; gray sharks, Carcharhinus spp.; and blue shark, Prionace glauca. Catches of blue and gray sharks showed a significant interaction among seamounts, with gray sharks occurring in maximum abundance around those seamounts that had relatively deep summits and low-sloping depth profiles. Results are discussed in terms of the various factors that may have influenced distribution of effort

Vacuum Polarization by a Magnetic Flux Tube at Finite Temperature in the Cosmic String Spacetime

In this paper we analyse the effect produced by the temperature in the vacuum polarization associated with charged massless scalar field in the presence of magnetic flux tube in the cosmic string spacetime. Three different configurations of magnetic fields are taken into account: $(i)$ a homogeneous field inside the tube, $(ii)$ a field proportional to $1/r$ and $(iii)$ a cylindrical shell with $\delta$-function. In these three cases, the axis of the infinitely long tube of radius $R$ coincides with the cosmic string. Because the complexity of this analysis in the region inside the tube, we consider the thermal effect in the region outside. In order to develop this analysis, we construct the thermal Green function associated with this system for the three above mentioned situations considering points in the region outside the tube. We explicitly calculate in the high-temperature limit, the thermal average of the field square and the energy-momentum tensor.Comment: 16 pages, 1 figur

Relativistic Quantum Scattering on a Cone

We study the relativistic quantum mechanical scattering of a bosonic particle by an infinite straight cosmic string, considering the non-minimal coupling between the bosonic field and the scalar curvature. In this case, an effective two-dimensional delta-function interaction takes place besides the usual topological scattering and a renormalization procedure is necessary in order to treat the problem that appears in connection with the delta-function.Comment: 22 pages, LATEX fil

Desenvolvimento inicial e trocas gasosas do meloeiro sob temperatura elevada.

O objetivo desse trabalho foi avaliar o crescimento inicial e as trocas gasosas de meloeiros crescidos sob dois diferentes regimes de temperatura

Ponto de murcha permanente de um neossolo flúvico usando novas plantas indicadoras.

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Componentes estruturais do resíduo pós-corte em capim-massai adubado com cinco doses de nitrogênio.

Objetivou-se avaliar os componentes da biomassa do resíduo pós-corte em capim-massai submetido a cinco doses de nitrogênio (0; 150; 300; 450 e 600 mg N dm-3 de solo) num delineamento inteiramente casualizado, com cinco repetições (vasos) em casa de vegetação. Avaliaram-se a altura residual, a densidade populacional de perfilhos (DPP), a massa seca de forragem total residual (MSFTr), de forragem verde residual (MSFVr), de forragem morta residual (MSFMr), de lâmina foliar verde residual (MSLVr), de colmo verde residual (MSCVr), relação lâmina foliar/haste (LF/C), a massa seca radicular (MS radicular) e a relação parte aérea/raiz. Observou-se efeito quadrático dos níveis de adubação nitrogenada sobre a altura residual. As variáveis MSFTr, MSFVr e MSCVr responderam positivamente, enquanto a MSLVr revelou comportamento quadrático com os níveis de N. Constatou-se valores estimados de 13,35 e 39,73 g MS/vaso para MSFTr, de 9,71 e 24,69 g MS/vaso para MSFVr e de 3,65 e 15,07 g MS/vaso para MSFMr nas doses de 0 a 600 mg N dm-3 de solo, respectivamente. A MS radicular respondeu positivamente às doses de N. A adubação nitrogenada proporciona resultados positivos sobre as características estruturais do resíduo pós-corte do capim-massai. After cut structural components of massai grass under five nitrogen fertilizer levels. Abstract - After cut residue of Massai grass under five nitrogen fertilized levels were evaluated. A completely randomized design with five nitrogen levels (0; 150; 300; 450 and 600 mg N dm-3 of soil) and five replicates (plots) in greenhouse was used. It was evaluated the residual canopy height (RCH), the tiller population density (TPD), the total residual forage dry mass (TFDM), the residual green forage dry mass (GFDM), the senescent forage dry mass (SFDM), the residual green leaf dry mass (GLDM), the residual green culm dry mass (GCDM), leaf/culm ratio (L/C), root dry mass (RDM) and above ground/root ratio (A/R). There was square effect of nitrogen fertilization on RCH. There were crescent and linear effect of nitrogen fertilization on TFDM, GFDM and GCDM. There was square effect of nitrogen fertilization on GLDM. The values were estimated in 13.35 and 39.73 g DM/plot to TFDM; 9.71 and 24.69 g DM/plot to GFDM and 3.65 and 15.07 g DM/plot to SFDM on 0 and 600 mg N dm-3 of soil, respectively. The RDM presented positively response to the N levels. It was concluded that the nitrogen fertilizing brought benefits for all structural characteristics after cut of Massai grass

Mal-do-panamá em Rondônia: levantamento da ocorrência e distribuição da doença.

Este trabalho teve como objetivo mapear a distribuição do Mal-do-Panamá no estado de Rondônia, numa parceria firmada entre a Embrapa Rondônia e a Agência Idaron permitiu um levantamento da ocorrência da doença no período de 2004 a 2012