Variational Mean Field approach to the Double Exchange Model

It has been recently shown that the double exchange Hamiltonian, with weak antiferromagnetic interactions, has a richer variety of first and second order transitions than previously anticipated, and that such transitions are consistent with the magnetic properties of manganites. Here we present a thorough discussion of the variational Mean Field approach that leads to the these results. We also show that the effect of the Berry phase turns out to be crucial to produce first order Paramagnetic-Ferromagnetic transitions near half filling with transition temperatures compatible with the experimental situation. The computation relies on two crucial facts: the use of a Mean Field ansatz that retains the complexity of a system of electrons with off-diagonal disorder, not fully taken into account by the Mean Field techniques, and the small but significant antiferromagnetic superexchange interaction between the localized spins.Comment: 13 pages, 11 postscript figures, revte

Punica granatum L. protects mice against hexavalent chromium-induced genotoxicity

This study investigated the chemoprotective effects of Punica granatum L. (Punicaceae) fruits alcoholic extract (PGE) on mice exposed to hexavalent chromium [Cr(VI)]. Animals were pretreated with PGE (25, 50 or 75 mg/kg/day) for 10 days and subsequently exposed to a sub-lethal dose of Cr(VI) (30 mg/kg). The frequency of micronucleated polychromatic erythrocytes in the bone marrow was investigated and the Cr(VI) levels were measured in the kidneys, liver and plasm. For the survival analysis, mice were previously treated with PGE for 10 days and exposed to a single lethal dose of Cr(VI) (50 mg/kg). Exposure to a sub-lethal dose of Cr(VI) induced a significant increase in the frequency of micronucleated cells. However, the prophylactic treatment with PGE led to a reduction of 44.5% (25 mg/kg), 86.3% (50 mg/kg) and 64.2% (75 mg/kg) in the incidence of micronuclei. In addition, the 50 mg/kg dose of PGE produced a higher chemoprotective effect, since the survival rate was 90%, when compared to that of the non-treated group. In these animals, reduced amounts of chromium were detected in the biological materials, in comparison with the other groups. Taken together, the results demonstrated that PGE exerts a protective effect against Cr(VI)-induced genotoxicity

Descrição morfológica e morfométrica da glândula vesicular de cobaias durante o desenvolvimento pós-natal

Glândulas vesiculares são essenciais para a reprodução, pois suas secreções afetam a função espermática. Cobaias (Cavia porcellus) são um excelente modelo experimental para estudo destas glândulas, contudo não existem dados morfológicos e morfométricos durante seu desenvolvimento. Neste estudo a morfologia (projeções das pregas (PP) e altura das células epiteliais (AE) da túnica mucosa) e a morfometria (massa (MG), volume (VG), comprimento (CG), largura das porções cranial (LCR), média (LM) e caudal (LCA)) das glândulas vesiculares foram determinadas em cobaios (N= 25) com uma (S1), três (S3), cinco (S5), oito (S8) e onze (S11) semanas de idade (N=5/grupo de idade). Em adição massa (MC), comprimento (CC) e altura (AC) corporais e o índice organo-somático (IOS) foram também determinados e o coeficiente de correlação (r) estabelecido entre as variáveis. As glândulas restringiam-se a cavidade pélvica e tinham seu interior repleto de uma massa semi-sólida e, após a S8, ocuparam também a cavidade abdominal e tiveram o conteúdo aumentado significativamente. A túnica mucosa era pregueada e forrada de um epitélio simples colunar. MC, CC e AC aumentaram continuamente com a idade. MG, VG, CG e LCA não se alteraram da S1 a S5 e aumentaram na S8; enquanto que MF, VG e LCA também aumentaram na S11. IOS e PP aumentaram na S8 e S11 e AE na S5, S8 e S11. Houve (r) significativo entre a idade, Bc e MFg,; IOS e MG na S8 e S11; idade e PP; idade e AE e entre PP e AE. Em conclusão, as glândulas vesiculares de cobaios seguiram o padrão morfológico observado em ratos e hamsters, mas diferiram em alguns aspectos de outros histricomorfos, podendo ser utilizadas como modelo experimental e seu desenvolvimento morfológico e morfométrico podem ser divididos em três fases: da S1 a S5, quando são discretos; da S6 a S8 de idade, quando são acentuados de maneira geral e após a S8, quando há incremento intenso da capacidade secretória

ARIA 2016: Care pathways implementing emerging technologies for predictive medicine in rhinitis and asthma across the life cycle

The Allergic Rhinitis and its Impact on Asthma (ARIA) initiative commenced during a World Health Organization workshop in 1999. The initial goals were (1) to propose a new allergic rhinitis classification, (2) to promote the concept of multi-morbidity in asthma a