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

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

Caráter mocho e infertilidade em caprinos.

Não é possível obter uma linhagem de caprinos mochos e férteis, uma vez que o gene que determina o caráter mocho tem efeito pleiotrópico sobre a fertilidade. O caráter mocho só acarreta problemas de infertilidade quando ambos os pais são mochos (homozigoto). Assim, para evitar problemas futuros na condução do rebanho, basta que um dos pais tenha chifres, de preferência o reprodutor, que deixa maior número de descendentes no rebanho. Deste modo, não é recomendado manter o reprodutor mocho no rebanho.bitstream/CNPC/20196/1/cot60.pd

Fungos associados à pluma e às sementes de algodão com línter.

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