Zero-temperature TAP equations for the Ghatak-Sherrington model

The zero-temperature TAP equations for the spin-1 Ghatak-Sherrington model are investigated. The spin-glass energy density (ground state) is determined as a function of the anisotropy crystal field $D$ for a large number of spins. This allows us to locate a first-order transition between the spin-glass and paramagnetic phases within a good accuracy. The total number of solutions is also determined as a function of $D$.Comment: 11 pages, 2 ps figures include

Coalescence Rate of Supermassive Black Hole Binaries Derived from Cosmological Simulations: Detection Rates for LISA and ET

The coalescence history of massive black holes has been derived from cosmological simulations, in which the evolution of those objects and that of the host galaxies are followed in a consistent way. The present study indicates that supermassive black holes having masses greater than $\sim 10^{9} M_{\odot}$ underwent up to 500 merger events along their history. The derived coalescence rate per comoving volume and per mass interval permitted to obtain an estimate of the expected detection rate distribution of gravitational wave signals ("ring-down") along frequencies accessible by the planned interferometers either in space (LISA) or in the ground (Einstein). For LISA, in its original configuration, a total detection rate of about $15 yr^{-1}$ is predicted for events having a signal-to-noise ratio equal to 10, expected to occur mainly in the frequency range $4-9 mHz$. For the Einstein gravitational wave telescope, one event each 14 months down to one event each 4 years is expected with a signal-to-noise ratio of 5, occurring mainly in the frequency interval $10-20 Hz$. The detection of these gravitational signals and their distribution in frequency would be in the future an important tool able to discriminate among different scenarios explaining the origin of supermassive black holes.Comment: 18 pages, 7 figures, to appear in the IJMP

Effects of Random Biquadratic Couplings in a Spin-1 Spin-Glass Model

A spin-1 model, appropriated to study the competition between bilinear (J_{ij}S_{i}S_{j}) and biquadratic (K_{ij}S_{i}^{2}S_{j}^{2}) random interactions, both of them with zero mean, is investigated. The interactions are infinite-ranged and the replica method is employed. Within the replica-symmetric assumption, the system presents two phases, namely, paramagnetic and spin-glass, separated by a continuous transition line. The stability analysis of the replica-symmetric solution yields, besides the usual instability associated with the spin-glass ordering, a new phase due to the random biquadratic couplings between the spins.Comment: 16 pages plus 2 ps figure

Manipulação da vegetação lenhosa da caatinga para fins pastoris.

Potencial forrageiro da caatinga; Controle de especies lenhosas da caatinga; Niveis de manupulacao da vegetacao lenhosa da caatinga; Melhoramento do estrato herbaceo; Recomendacoes.bitstream/item/36461/1/CT-11.pd

Weak measurement og the composite Goo-Haenchen shift in the critical region

By using a weak measurement technique, we investigated the interplay between the angular and lateral Goos-Haenchen shift of a focused He-Ne laser beam for incidence near the critical angle. We verified that this interplay dramatically affects the composite Goos-Haenchen shift of the propagated beam. The experimental results confirm theoretical predictions that recently appeared in the literature.Comment: 10 pages, 3 figure

Desempenho produtivo de ovelhas crioulas em suplementação alimentar e sob três sistemas de acasalamento.

0 experimento foi conduzido na Embrapa Caprinos, Sobral, CE, Brasil com o objetivo de determinar os efeitos da suplementaçao alimentar e do sistema de acasalamento sobre 0 desempenho produtivo de matrizes ovinas crioulas criadas em caatinga manipulada, em urn delineamento experimental inteiramente casualizado, sob 0 sistema de pastoreio rotativo e com uma taxa de lotaçao medio de 3,6 ovinos/ha/ano. A suplementaçao alimentar, ministrada durante a estaçao seca, constou de 200 g de rolao de milho e 300 g de feno de leucena e os sistemas de acasalamento foram a manta continua, a manta anual e a manta a cada oito meses. Na fase de pre-manta, as matrizes nao suplementadas tiveram pesos vivos medias (PVM), na estaçao umida, superiores (P0,05), mas, superiores (P<0,05) aos das nao suplementadas, somente na estacao seca. Ao pre-parto, pos-parto e a desmama, os PVM das matrizes suplementadas superaram (P<0,05) os das nao suplementadas, independentemente da estaçao do ano. A fertilidade ao parto na epoca das chuvas foi de 86,3% para as matrizes suplementadas e de 72,7% para as nao suplementadas, enquanto na epoca seca os valores foram de 75,8% e 60,0%, respectivamente. A taxa media de prolificidade foi de 1,64 crias/ano para as matrizes nao suplementadas e 1,77 para as suplementadas. As reprodutrizes suplementadas desmamaram anualmente 15,6 kg PVM de cordeiros e as nao suplementadas 10,6 kg

Evidence for a Very Large-Scale Fractal Structure in the Universe from Cobe Measurements

In this work, we analyse the temperature fluctuations of the cosmic microwave background radiation observed by COBE and show that the distribution can be fitted by a fractal distribution with a fractal dimension $D= 1.43 \pm 0.07$. This value is in close agreement with the fractal dimension obtained by Coleman and Pietronero (1992) and Luo and Schramm (1992) from galaxy-galaxy and cluster-cluster correlations up to $\sim 100 h^{-1} Mpc$. The fact that the observed temperature fluctuations correspond to scales much larger than $100 h^{-1} Mpc$ and are signatures of the primordial density fluctuations at the recombination layer suggests that the structure of the matter at the early universe was already fractal and thus non-homogeneous on those scales. This result may have important consequences for the theoretical framework that describes the universe.Comment: 11 pages, postscript file, 2 figures available upon request. To appear in ApJ Letter

Histopatologia da interação Alternaria solani e tomateiros resistente e suscetível.

Este trabalho objetivou avaliar, quantitativa e qualitativamente, através de processamentos histológicos e de MEV, os eventos de pré-penetração, penetração e colonização dos tecidos de tomateiros resistente e suscetível a A. solani e tentar esclarecer os mecanismos de resistência, pela comparação dos processos de infecção de A. solani em tomateiros resistente e suscetível