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

Umbuzeiro (Spondias tuberosa Arruda): planta nativa da caatinga, importante repositório natural de moscas-das-frutas.

O objetivo desse trabalho foi conhecer as espécies de moscas-das-frutas no umbuzeiro e o índice de infestação natural, no município de Petrolina, Pernambuco

DESIGN, CONSTRUCTION AND EVALUATION OF A THERMAL CONDUCTIVITY METER BASED ON ASTM E1225 STANDARD

The focus of this work is the design, construction and evaluation of a thermal conductivity meter apparatus based on ASTM E- 1225 standard. The thermal conductivity is a heat-transport propriety and with the development of new materials the determination of thermophysical properties for its correct use becomes necessary. The apparatus was projected in CAD software and the material selection was done following the standard recommendations. For the meter bars were used 304 stainless steel, since its thermal conductivity is known. The heater was made with an aluminum cylinder block and a cartridge electric resistance. The cooling system was assembled using a Peltier thermoelectric plate and a fin heat sink equipped with a fan. Lastly, a steel pipe was used for building the guard cylinder. In order to evaluate the apparatus, the first specimen tested was the 304 stainless steel, the same material as the meter bars. The result of thermal conductivity showed an error of 6% relative to the value found in literature. However, in this test the temperature of isothermal guard cylinder was lower than the temperature required by the standard. Thus, the future goals will be the development of a temperature control for the guard cylinder and realization of more tests with different materials

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

Emprego do método RAPD na análise de diversidade genética em linhagens de fungos causadores de podridões do tronco da videira.

Uma abordagem para investigar a variabilidade genética em diferentes espécies de fungos causadores de podridão do tronco da videira isolados no Rio Grande do Sul foi experimentada por sua facilidade e praticidade: o RAPD (Random Amplified Polymorphic DNA). O RAPD auxilia na identificação e caracterização da diversidade genética em linhagens de fitopatógenos. Para isso, uma coleção de trabalho com diferentes espécies foi selecionada a partir da confirmação de seus produtos de PCR, sequenciamento e BLASTn

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

Geometrically induced singular behavior of entanglement

We show that the geometry of the set of quantum states plays a crucial role in the behavior of entanglement in different physical systems. More specifically it is shown that singular points at the border of the set of unentangled states appear as singularities in the dynamics of entanglement of smoothly varying quantum states. We illustrate this result by implementing a photonic parametric down conversion experiment. Moreover, this effect is connected to recently discovered singularities in condensed matter models.Comment: v2: 4 pags, 4 figs. A discussion before the proof of Proposition 1 and tomographic results were included, Propostion 2 was removed and the references were fixe

Exigências em energia e proteína líquida para ovelhas da raça Santa Inês em lactação.

Objetivou-se determinar as necessidades de proteína e energia líquida de ovelhas em lactação submetidas a dois manejos nutricionais na gestação e dois tipos de gestação. Os ensaios experimentais foram conduzidos nas instalações do Laboratório de Metabolismo e Calorimetria Animal do Departamento de Zootecnia da Escola de Veterinária da UFMG. Foram utilizadas 28 ovelhas da raça Santa Inês, em um delineamento experimental inteiramente casualizado em arranjo fatorial 2x2, e considerou-se dois tipos de gestação (simples e gemelar) e dois tipos de manejo nutricional (com e sem restrição). As ovelhas eram colocadas sobre plataforma e contidas para realização da ordenha. Para análise dos dados referentes às semanas em lactação utilizou-se o modelo de medidas repetidas no tempo. Os grupos experimentais foram avaliados mediante utilização do teste SNK a 5% de significância. A produção de leite não foi afetada pelo manejo nutricional, bem como a quantidade de gordura, proteína, energia e as necessidades em energia e proteína. Portanto, ficou evidenciado neste estudo que somente o manejo nutricional não foi capaz de alterar as variáveis estudadas. Ovelhas com gestação dupla apresentaram maior produção de leite, maiores teores de gordura e proteína no leite bem como maior valor energético do mesmo. As necessidades em energia e proteína foram maiores para ovelhas com gestação dupla. A produção de leite e as necessidades em energia e proteína foram maiores até a décima semana de lactação. A exigência nutricional em energia e proteína acompanhou a curva de produção de leite. [Net requirement of protein and energy of Santa Inês ewe in lactation]. Abstract: This study aimed to obtain the protein and liquid energy requirements from lactating ewes under two nutritional managements during pregnancy and under two types of pregnancy. Experimental tests were conducted at the Animal Metabolism and Calorimetry Laboratory on Department of Animal Science from Veterinary School of UFMG. For the experimental testing, were used 28 Santa Ines sheeps in a completely randomized design under 2 x 2 factorial arrangement, considering two pregnancy types (single and double) and two nutritional managements (with and without restriction). Sheeps were placed on the platform and contained for milking. To analyse data regarding milking weeks it was used the model of repeated measures in time. The experimental groups were evaluated using the SNK test at 5% significance level. (1) Diets were compound of corn meal (Zea mays), soybean meal (Glycine max), chopped Tifton grass hay (Cynodon spp.) and limestone. Sheep?s specific mineralsupplement was offered ad libitum to the animals Milk production was not affected by nutritional management, as the amount of fat, protein and, energy from milk. The same results were observed to energy and protein requirements. This fact shows that the nutritional management, per se, was not able to change the variables studied. The double pregnancy produced more milk, fat and protein in milk increasing its energy value. Energy and protein requirements were higher in ewes with double pregnancy. Milk production, energy and protein requirements were higher until the tenth week of lactation. Energy and protein nutritional requirement followed the milk production curve