Dificuldades de professores de física em início de carreira

Neste trabalho, procuramos, através de uma pesquisa qualitativa, realizada por meio de entrevistas e narrativas, identificar as principais dificuldades encontradas por três professores de física em início de carreira. Percebemos nos casos estudados, que, ao se depararem com a realidade de sala de aula em suas primeiras experiências, os professores se chocam com questões básicas do ensino, como a indisciplina, a motivação dos estudantes, como se portar em sala e que, nos momentos iniciais, estas questões fazem parte do seu desenvolvimento profissional assim como muitas vezes determinam a continuidade ou não de alguns professores em suas carreiras. Apresentamos nossos dados, relacionando, classificando e analisando as principais dificuldades encontradas por estes professores, a luz de algumas teorias relacionadas à formação de professores

Mechanical qubit-light entanglers in hybrid nonlinear qubit optomechanics

Interfacing between matter qubits and light is a crucial provision for numerous quantum technological applications. However, a generic qubit may not directly interact with a relevant optical field mode, and hence, one could necessitate adjusting frequencies to match resonance conditions between parties. In this work, we show how a parametric coupling of the qubit with a mechanical oscillator, in conjunction with the trilinear radiation pressure coupling of the same object with light, can induce maximal qubit-light entanglement at an optimal time. Furthermore, we show how our method enables conditional (dynamical) nonclassical state preparation of the optical field via qubit measurement in the weak (moderate-to-strong) optomechanical coupling regime. Our scheme benefits from not requiring any cooling of the mechanical component and not needing an adjusting of the detunings and transition frequencies to have resonance between any pairs of quantum systems

Semiclassical back reaction around a cosmic dislocation

The energy-momentum vacuum average of a conformally coupled massless scalar field vibrating around a cosmic dislocation (a cosmic string with a dislocation along its axis) is taken as source of the linearized semiclassical Einstein equations. The solution up to first order in the Planck constant is derived. Motion of a test particle is then discussed, showing that under certain circumstances a helical-like dragging effect, with no classical analogue around the cosmic dislocation, is induced by back reaction.Comment: Published version, 4 pages, no figures, REVTeX4 fil

Stellar equilibrium configurations of white dwarfs in the f(R,T)f(R,T) gravity

In this work we investigate the equilibrium configurations of white dwarfs in a modified gravity theory, na\-mely, $f(R,T)$ gravity, for which $R$ and $T$ stand for the Ricci scalar and trace of the energy-momentum tensor, respectively. Considering the functional form $f(R,T)=R+2\lambda T$, with $\lambda$ being a constant, we obtain the hydrostatic equilibrium equation for the theory. Some physical properties of white dwarfs, such as: mass, radius, pressure and energy density, as well as their dependence on the parameter $\lambda$ are derived. More massive and larger white dwarfs are found for negative values of $\lambda$ when it decreases. The equilibrium configurations predict a maximum mass limit for white dwarfs slightly above the Chandrasekhar limit, with larger radii and lower central densities when compared to standard gravity outcomes. The most important effect of $f(R,T)$ theory for massive white dwarfs is the increase of the radius in comparison with GR and also $f(R)$ results. By comparing our results with some observational data of massive white dwarfs we also find a lower limit for $\lambda$, namely, $\lambda >- 3\times 10^{-4}$.Comment: To be published in EPJ

Parâmetros reprodutivos de rebanho caprino no Sertão Pernambucano.

O presente estudo teve como objetivo avaliar os parâmetros reprodutivos de rebanho caprino e os pesos ao nascimento das crias em sistema de produção no Sertão Pernambucano. Foram utilizadas 83 cabras divididas em dois grupos (G1 n=41 e G2 n=42), mantendo cada grupo em área de Caatinga de 40,5 ha durante o período chuvoso e em 13 ha de capim-bufel (Cenchrus ciliaris L.), na época seca. A estação de monta teve duração de 60 dias entre os meses de fevereiro a abril de 2012. As variáveis mensuradas foram: taxa de parição (fêmeas paridas / fêmeas expostas x 100), taxa de concepção (fêmeas cobertas / fêmeas expostas x 100), taxa de fertilidade (fêmeas paridas / fêmeas cobertas x 100), prolificidade (crias nascidas / fêmeas paridas), taxa de mortalidade (crias mortas / crias nascidas x 100), além dos pesos das crias, em relação ao sexo e ordem de parto das matrizes. Foram obtidos 52 partos, 24 no G1 e 28 no G2. O rebanho apresentou valores médios de 62,6% de taxa de parição, 73,6% de taxa de concepção, 85,2% de taxa de fertilidade, além de 1,53 crias nascidas por matriz parida e 10% de taxa mortalidade das crias de 1 a 90 dias. Os pesos ao nascimento foram em média 1,98 kg (2,20 kg para os machos e 1,84 para fêmeas). Os animais nascidos de fêmeas pluríparas apresentaram 2,05 kg, enquanto os filhos das primíparas tiveram 1,76 kg. Em geral, os parâmetros reprodutivos do rebanho e os pesos ao nascer das crias foram satisfatórios, considerando o sistema produtivo, obtendo-se valores superiores aos observados no sistema de criação extensivo tradicional

Development of an Optoelectronic Sensor for Detecting and Classifying Fruit Fly (Diptera:,Tephritidae) for Use in Real-Time Intelligent Traps.

Fruit flies (Diptera: Tephritidae) cause losses to world fruit growing. For a fast and effective control of the pest, it is necessary to identify the species and their populations. Thus, we developed an infrared optoelectronic sensor using phototransistors to capture the signal of the partial occlusion of the infrared light caused by the beating of the fly wings. Laboratory experiments were conducted using the sensor to capture the wing beat signal of A. fraterculus and C. capitata. The captured signals were used to obtain the characteristics of the flies’ wing beats frequency and for a production of a dataset made available as one of the results of this work. For the passage detection, we developed the algorithm of detection of events of passage (PEDA) that uses the root mean square (RMS) value of a sliding window applied to the signal compared to a threshold value. We developed the algorithm of detection of events of passage (CAEC) that uses the techniques of autocorrelation and Fourier transform for the extraction of the characteristics of the wings’ beat signal. The results demonstrate that it is possible to use the sensor for the development of an intelligent trap with detection and classification in real time for A. fraterculus and C. capitata using the wing beat frequency obtained by the developed sensor