Pastagens em sistemas silvipastoris.

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Mathematical Analysis of a Method to Compute Guided Waves in Integrated Optics

In this article, we propose a new method to solve an eigenvalue problem (posed in \B) arising from the computation of guided modes in integrated optics electromagnetic waveguides under the weak guiding assumption. We consider an open stratified waveguide translationally invariant in the infinite propagation direction. Its cross-section is also supposed to be an unbounded and stratified medium where an appropiate perturbation of the refraction index has been introduced to ensure the existence of guided modes. The method presented here appears as a combination of analytical methods which take into account the unbounded and stratified character of the propagation medium and numerical computations which can be reduced to a neighborhood of the perturbation. In this report, we give a complete description of the method, present its main mathematical properties and achieve the convergence analysis with respect to the various approximation parameters

Metabolic syndrome association with fibrosis development in chronic hepatitis B virus inactive carriers

[Abstract] Background and Aim. There are few data of fibrosis development in chronic hepatitis B (CHB) patients classified as inactive carriers. The aim of this study is to determinate the prevalence of significant fibrosis and probable cirrhosis measured by FibroScan in real inactive CHB carriers and investigate the relationship with virological, epidemiological, and metabolic factors. Methods. Cross-sectional cohort study including CHB inactive carriers. Liver stiffness measurement was performed with transient elastography (FibroScan). Significant fibrosis (≥ F2) was defined as stiffness > 7.5 kPa, and probable cirrhosis as > 11.8 kPa. Factors associated with significant fibrosis were explored with univariate and multivariate adjusted logistic regression analyses. Results. Ninety-six CHB inactive carriers were analyzed. Of them, 24 (25%) had significant fibrosis and 7 (7%) probable cirrhosis; mean stiffness was 6.2 ± 2.3 kPa. Of them, 24% had metabolic syndrome, with higher FibroScan value than those without (8.4 kPa vs 5.5 kPa, P < 0.001). Factors associated with significant fibrosis were (odds ratio, 95% confidence interval, P value): central obesity (7.1, 1.8–27.9, 0.005), elevated fasting glucose (4.3, 1.3–27.9, 0.036), reduced high-density lipoprotein cholesterol (5.2, 1.2–23.6, 0.032) and elevated triglycerides (6.2, 1.4–28.3, 0.019). Factors as age, sex, transaminases, hepatitis B virus DNA or genotype were not related with liver fibrosis. The presence of metabolic syndrome has a 69% of positive predictive value and 89% of negative predictive value for significant fibrosis. Conclusion. Different components of metabolic syndrome are associated with fibrosis development in CHB inactive carriers. In the absence of metabolic syndrome, significant fibrosis is uncommon in this population.Instituto de Salud Carlos III; CP08/00214Instituto de Salud Carlos III; PI10/0216

Update on hepatitis C virus resistance to direct-acting antiviral agents

Review[Abstract] Resistance to direct-acting antiviral (DAA) agents against hepatitis C virus (HCV) infection is driven by the selection of mutations at different positions in the NS3 protease, NS5B polymerase and NS5A proteins. With the exception of NS5B nucleos(t)ide inhibitors, most DAAs possess a low genetic barrier to resistance, with significant cross-resistance between compounds belonging to the same family. However, a specific mutation profile is associated with each agent or drug class and varies depending on the genotype/subtype (e.g., genotype 1b showed higher rates of sustained virological response (SVR) and a higher genetic barrier for resistance than genotype 1a). Moreover, some resistance mutations exist as natural polymorphisms in certain genotypes/subtypes at frequencies that require baseline drug resistance testing before recommending certain antivirals. For example, the polymorphism Q80K is frequently found among genotype 1a (19–48%) and is associated with resistance to simeprevir. Similarly, L31M and Y93H, key resistance mutations to NS5A inhibitors, are frequently found (6–12%) among NS5A genotype 1 sequences. In particular, the presence of these polymorphisms may be of relevance in poorly interferon-responsive patients (i.e., null responders and non-CC IL28B) under DAA-based therapies in combination with pegylated interferon-α plus ribavirin. The relevance of pre-existing resistance mutations for responses to interferon-free DAA therapies is unclear for most regimens and requires further study.Instituto de Salud Carlos III; CP08/00214Instituto de Salud Carlos III; PI10/0216

Nitrogen Fertilization and Harvest Management Improve Forage and Crude Protein Content in Crabgrass

Crabgrass (Digitaria spp.) is an annual summer grass that can provide high-quality forage, but optimal management strategies are unclear. Our objective was to compare the yield and quality of crabgrass (Mojo and Quick-N-Big) under different nitrogen rates and harvest management. The experimental design was a randomized complete block with five treatments and three replications for each crabgrass variety, totaling fifteen experimental units for both Mojo and Quick-N-Big, in adjacent sites. Treatments were nitrogen rates (0, 100, and 200 lb N/acre) and harvest management (cut once or twice per year) for two growing seasons (2020 and 2021). Total forage accumulation (TFA) increased with nitrogen fertilization for both cultivars. Mojo had the highest TFA in the first year (7000 lb DM/a/yr) while Quick-N-Big TFA was the highest in the second year (7635 lb DM/a/yr). The highest crude protein (CP) content was obtained with the highest N dose, ranging from 10.5 to 13% for both cultivars. Based on these results, N fertilization and harvest management can contribute to improving forage yield and crude protein of crabgrass varieties during the growing season in forage systems

Total HCV core antigen assay: a new marker of HCV viremia and its application during treatment of chronic hepatitis C

[Abstract] The present study assesses the clinical usefulness of the hepatitis C core antigen assay for monitoring of patients being treated for chronic hepatitis C virus (HCV) infection. Eighty-six serum samples were selected at random from 16 patients and levels of HCV RNA and HCV core antigen were determined simultaneously and in parallel to compare both techniques. The data obtained were compared by Pearson’s correlation and the coefficients calculated by Fisher transformation and by calculating the difference and standard error. A good linear correlation was observed between both techniques. Maximum correlation, with significant difference, was found between patients infected with the 1a genotype and other genotypes. In conclusion, the HCV core antigen assay is useful for the diagnosis of early infection; however, its use for determining the exact timing of viral elimination during treatment is clearly unsuitable

Perdas na silagem de grão de milho triturado reidratado contendo glicerina bruta e inoculante microbiano

Avaliou-se o efeito da inclusão de diferentes níveis de glicerina bruta, com ou sem inoculante microbiano sobre as perdas na silagem de grão de milho triturado e reidratado. O grão seco de milho moído, inoculado ou não com inoculante microbiano, foi reidratado com água e glicerina bruta em diferentes níveis para manter o teor de umidade em 32,5%, conferindo a adição de 0; 7,5; 15,0 e 22,5% de glicerina bruta (matéria natural) e ensilado em silos experimentais de PVC. O experimento foi conduzido em esquema fatorial (2x4x6) segundo o delineamento inteiramente casualizado com três repetições por tratamento. As perdas por efluente aumentaram linearmente com a adição de níveis crescentes de glicerina bruta, independente do uso de inoculante e também nos períodos de fermentação. Porém, as perdas por gás reduziram linearmente e tiveram resposta quadrática com o aumento da inclusão de glicerina bruta para os tratamentos sem e com in oculante. As perdas de matéria seca totais aumentaram com o incremento nos níveis de glicerina bruta, independente do inoculante. A inclusão de 7,5% de glicerina bruta com inoculante propicia as menores perdas de matéria seca total na silagem de grão de milho triturado e reidratado