The BCS-Bose Crossover Theory

We contrast {\it four} distinct versions of the BCS-Bose statistical crossover theory according to the form assumed for the electron-number equation that accompanies the BCS gap equation. The four versions correspond to explicitly accounting for two-hole-(2h) as well as two-electron-(2e) Cooper pairs (CPs), or both in equal proportions, or only either kind. This follows from a recent generalization of the Bose-Einstein condensation (GBEC) statistical theory that includes not boson-boson interactions but rather 2e- and also (without loss of generality) 2h-CPs interacting with unpaired electrons and holes in a single-band model that is easily converted into a two-band model. The GBEC theory is essentially an extension of the Friedberg-T.D. Lee 1989 BEC theory of superconductors that excludes 2h-CPs. It can thus recover, when the numbers of 2h- and 2e-CPs in both BE-condensed and noncondensed states are separately equal, the BCS gap equation for all temperatures and couplings as well as the zero-temperature BCS (rigorous-upper-bound) condensation energy for all couplings. But ignoring either 2h- {\it or} 2e-CPs it can do neither. In particular, only {\it half} the BCS condensation energy is obtained in the two crossover versions ignoring either kind of CPs. We show how critical temperatures $T_{c}$ from the original BCS-Bose crossover theory in 2D require unphysically large couplings for the Cooper/BCS model interaction to differ significantly from the $T_{c}$s of ordinary BCS theory (where the number equation is substituted by the assumption that the chemical potential equals the Fermi energy).Comment: thirteen pages including two figures. Physica C (in press, 2007

MTP -493G/T gene polymorphism is associated with steatosis in hepatitis C-infected patients

The reduction of hepatic microsomal transfer protein (MTP) activity results in fatty liver, worsening hepatic steatosis and fibrosis in chronic hepatitis C (CHC). The G allele of the MTP gene promoter, -493G/T, has been associated with lower transcriptional activity than the T allele. We investigated this association with metabolic and histological variables in patients with CHC. A total of 174 untreated patients with CHC were genotyped for MTP -493G/T by direct sequencing using PCR. All patients were negative for markers of Wilson’s disease, hemochromatosis and autoimmune diseases and had current and past daily alcohol intake lower than 100 g/week. The sample distribution was in Hardy-Weinberg equilibrium. Among subjects with genotype 1, 56.8% of the patients with fibrosis grade 3+4 presented at least one G allele versus 34.3% of the patients with fibrosis grade 1+2 (OR = 1.8; 95%CI = 1.3-2.3). Logistic regression analysis with steatosis as the dependent variable identified genotypes GG+GT as independent protective factors against steatosis (OR = 0.4, 95%CI = 0.2-0.8; P = 0.01). The results suggest that the presence of the G allele of MTP -493G/T associated with lower hepatic MTP expression protects against steatosis in our CHC patients

Estudos sobre a nutrição mineral do milho: II. efeito de doses crescentes de N, R e K no crescimento, produção e composição mineral da variedade Piranão em condições controladas

Maize plants, Piranão cultivar, were grown in nutrient solution with 5 levels each of N, R and K till harvest. Nitrate reductase activity and putrescine level were determined in leaves of plants in the N and K series, respectively, at silking stage. Upper and lower leaves were analysed for N, R and K in the corresponding treatments at the end of the life cycle. The main conclusions were the following : 5.1 There was a linear effect of level of N in the substrate on dry matter production. 5.2. High activities of nitrate reductase suggest that under natural conditions the variety should be very responsive to N fertilization. 5.3. An asymptotic response curve was found in the treatments with increasing levels of R in the medium, as well as in the case of the K treatments. 5.4. Curves of response of roots (dry matter) showed a tendency to level of as a function of increasing levels of element at lower concentrations than the components aeral part of the plant (leaves, stems, ears). 5.5. Determination of leaf putrescine did not of prove a better indicator of the K status leaf K. 5.6. The variety under study seems to be relatively more efficient in the utilization of N for yield components; the efficiency for utilization of K, is rather low and that for R is intermediate, findings that should have a bearing on the fertilization in field conditions.O milho, var. Piranão, foi cultivado em solução nutritiva com níveis crescentes de N, R e K. Houve resposta linear à adição de N e assintótica às doses de R e de K. A determinação da atividade da reductase de nitrato se correlacionou melhor com a produção da matéria seca que a do N total nas folhas. O teor de potássio total nas folhas, por sua vez refletiu melhor o estado nutricional que a determinação de putrescina nas folhas