Specific heat amplitude ratios for anisotropic Lifshitz critical behaviors

We determine the specific heat amplitude ratio near a $m$-axial Lifshitz point and show its universal character. Using a recent renormalization group picture along with new field-theoretical $\epsilon_{L}$-expansion techniques, we established this amplitude ratio at one-loop order. We estimate the numerical value of this amplitude ratio for $m=1$ and $d=3$. The result is in very good agreement with its experimental measurement on the magnetic material $MnP$. It is shown that in the limit $m \to 0$ it trivially reduces to the Ising-like amplitude ratio.Comment: 8 pages, RevTex, accepted as a Brief Report in Physical Review

Avaliação do crescimento de mudas de pinhão manso (Jatropha curcas L.) em recipientes de diferentes volumes e acompanhamento do desenvolvimento em campo.

O objetivo deste trabalho foi quantificar o efeito dos diferentes volumes de recipiente na formação de mudas de pinhão-manso (Jatropha curcas L.) e no crescimento em campo aos seis meses após o plantio.bitstream/CPAF-RO-2010/14513/1/107-pinhaomanso.pd

Vigor de plântulas de pupunha em função de doses de giberlina aplicadas como tratamento pré-germinativo.

Este trabalho teve como objetivo avaliar o efeito do tratamento de sementes de pupunha com GA3 no vigor das plântulas

Effect of scorpion toxin on the enterochromaffin-like cells in normal and Trypanosoma cruzi-infected rats: a morphological study

Intravenous injection of scorpion toxin (Tityus serrulatus) in normal and Trypanosoma cruzi infected rats did not cause ultrastructural morphologic changes on enterochromaffin-like (ECL) cells of the stomach, although it induced a significant increase of the gastric secretion. Our data seem to indicate that gastric ECL cells structure is not affected by stimulation with scorpion toxin or by acute infection with T. cruzi in the rat.A injeção intravenosa de toxina escorpiônica (Tityus serrulatus) em ratos normais e infectados pelo Trypanosoma cruzi não causou alterações morfológicas ultra-estruturáis das células enterocromaflns-like (ECL) do estómago, embora tenha induzido a aumento significativo da secreção do suco gástrico. Nossos resultados parecem indicar que a estrutura das células ECL do estómago de ratos não é afetada pela estimulação com a toxina escorpiônica ou pela infecção aguda pelo T. cruzi

A new picture of the Lifshitz critical behavior

New field theoretic renormalization group methods are developed to describe in a unified fashion the critical exponents of an m-fold Lifshitz point at the two-loop order in the anisotropic (m not equal to d) and isotropic (m=d close to 8) situations. The general theory is illustrated for the N-vector phi^4 model describing a d-dimensional system. A new regularization and renormalization procedure is presented for both types of Lifshitz behavior. The anisotropic cases are formulated with two independent renormalization group transformations. The description of the isotropic behavior requires only one type of renormalization group transformation. We point out the conceptual advantages implicit in this picture and show how this framework is related to other previous renormalization group treatments for the Lifshitz problem. The Feynman diagrams of arbitrary loop-order can be performed analytically provided these integrals are considered to be homogeneous functions of the external momenta scales. The anisotropic universality class (N,d,m) reduces easily to the Ising-like (N,d) when m=0. We show that the isotropic universality class (N,m) when m is close to 8 cannot be obtained from the anisotropic one in the limit d --> m near 8. The exponents for the uniaxial case d=3, N=m=1 are in good agreement with recent Monte Carlo simulations for the ANNNI model.Comment: 48 pages, no figures, two typos fixe