Spatiotemporal monthly rainfall reconstruction via artificial neural network ? case study: south of Brazil

International audienceClimatological records users, frequently, request time series for geographical locations where there is no observed meteorological attributes. Climatological conditions of the areas or points of interest have to be calculated interpolating observations in the time of neighboring stations and climate proxy. The aim of the present work is the application of reliable and robust procedures for monthly reconstruction of precipitation time series. Time series is a special case of symbolic regression and we can use Artificial Neural Network (ANN) to explore the spatiotemporal dependence of meteorological attributes. The ANN seems to be an important tool for the propagation of the related weather information to provide practical solution of uncertainties associated with interpolation, capturing the spatiotemporal structure of the data. In practice, one determines the embedding dimension of the time series attractor (delay time that determine how data are processed) and uses these numbers to define the network's architecture. Meteorological attributes can be accurately predicted by the ANN model architecture: designing, training, validation and testing; the best generalization of new data is obtained when the mapping represents the systematic aspects of the data, rather capturing the specific details of the particular training set. As illustration one takes monthly total rainfall series recorded in the period 1961?2005 in the Rio Grande do Sul ? Brazil. This reliable and robust reconstruction method has good performance and in particular, they were able to capture the intrinsic dynamic of atmospheric activities. The regional rainfall has been related to high-frequency atmospheric phenomena, such as El Niño and La Niña events, and low frequency phenomena, such as the Pacific Decadal Oscillation

Anomalous electron trapping by localized magnetic fields

We consider an electron with an anomalous magnetic moment g>2 confined to a plane and interacting with a nonzero magnetic field B perpendicular to the plane. We show that if B has compact support and the magnetic flux in the natural units is F\ge 0, the corresponding Pauli Hamiltonian has at least 1+[F] bound states, without making any assumptions about the field profile. Furthermore, in the zero-flux case there is a pair of bound states with opposite spin orientations. Using a Birman-Schwinger technique, we extend the last claim to a weak rotationally symmetric field with B(r) = O(r^{-2-\delta}) correcting thus a recent result. Finally, we show that under mild regularity assumptions the existence can be proved for non-symmetric fields with tails as well.Comment: A LaTeX file, 12 pages; to appear in J. Phys. A: Math. Ge

Two-dimensional electron gas in a uniform magnetic field in the presence of a delta-impurity

The density of states and the Hall conductivity of a two-dimensional electron gas in a uniform magnetic field and in the presence of a delta impurity are exactly calculated using elementary field theoretic techniques. Although these results are not new, our treatment is explicitly gauge-invariant, and can be easily adapted to other problems involving a delta potential.Comment: 12+1 pages, 1 ps figure, REVTEX. Corrigendum adde

Crescimento e produção de frutos em mangueira "Tommy Atkins" sob deferentes densidades populacionais.

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Produção e composição do leite de ovelhas Santa Inês e mestiças Lacaune e Santa Inês e desenvolvimento de seus cordeiros.

Na ovinocultura, a raça Santa Inês, amplamente explorada no território brasileiro, possui índices de produção compatíveis com sistemas europeus de exploração leiteira (Susin et al., 2005), e o bom desempenho de animais na fase de cria está diretamente relacionado com a produção de leite das mães (Peeters et al., 1992). A raça Lacaune tem sua origem atrelada à produção de animais de boa carcaça em diversas regiões da França e passou por um programa de melhoramento genético que resultou em aumento da produção de leite e melhora da composição da carcaça dos cordeiros destinados ao abate (Barillet et al., 2001). O presente trabalho teve o objetivo de avaliar a produção e a composição do leite de três genótipos de ovelhas Santa Inês, ½ Lacaune x ½ Santa Inês e ¾ Lacaune x ¼ Santa Inês ? e o desenvolvimento de seus cordeiros durante os quatro primeiros meses de lactação

Phenotypic, genetic and symbiotic characterization of Erythrina velutina rhizobia from Caatinga dry forest.

Erythrina velutina (Mulungu) is a legume ree from Caatinga that associates with rhizobia but the diversity and symbiotic ability of mulungu rhizobia are poorly understood. The aim of this study was to characterize mulungu rhizobia from Caatinga. Bacteria were obteined from Serra Talhada and Caruaru in Caatinga under natural regeneration. The bacteria were evaluated to the amplication of nifH and nod C and to metabolic characteristics. Ten selected bacteria identied by 16S rRNA sequences. They were tested in vitro to NaCl and temperature tolerance, auxin production and calcium phosphate solubilization. The symbiotic ability were assessed in an greenhouse experiment. A total of 32 bacteria were obtained and 17 amplied both symbiotic genes. The bacteria showed a high variable metabolic prole. Bradyrhizobium (6), Rhizobium (3) and Paraburkholderia (1) were identied, differing from their geographic origin. The isolates grew up to 45 ◦ C to 0.51 mol L ? 1 of NaCl. Bacteria which produced more auxin in the medium with l -tryptophan and two Rhizobium and one Bradyrhizobium were phosphate solubilizers. All bacteria nodulated and ESA 90 (Rhizobium sp.) plus ESA 96 (Paraburkholderia sp.) were more efcient symbiotically. Diverse and efcient rhizobia inhabit the soils of Caatinga dry forests, with the bacterial differentiation by the sampling sites

Towards mirror symmetry \`a la SYZ for generalized Calabi-Yau manifolds

Fibrations of flux backgrounds by supersymmetric cycles are investigated. For an internal six-manifold M with static SU(2) structure and mirror \hat{M}, it is argued that the product M x \hat{M} is doubly fibered by supersymmetric three-tori, with both sets of fibers transverse to M and \hat{M}. The mirror map is then realized by T-dualizing the fibers. Mirror-symmetric properties of the fluxes, both geometric and non-geometric, are shown to agree with previous conjectures based on the requirement of mirror symmetry for Killing prepotentials. The fibers are conjectured to be destabilized by fluxes on generic SU(3)xSU(3) backgrounds, though they may survive at type-jumping points. T-dualizing the surviving fibers ensures the exchange of pure spinors under mirror symmetry.Comment: 30 pages, 3 figures, LaTeX; v2: references adde

Aerial release of sterile flies using radio-controlled aircraft.

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Improved semiclassical density matrix: taming caustics

We present a simple method to deal with caustics in the semiclassical approximation to the thermal density matrix of a particle moving on the line. For simplicity, only its diagonal elements are considered. The only ingredient we require is the knowledge of the extrema of the Euclidean action. The procedure makes use of complex trajectories, and is applied to the quartic double-well potential.Comment: 20 pages, 7 figures. Revised version, accepted for publication in Phys. Rev.