146 research outputs found
Cover Crops Alternatives for Sustainable Agriculture Systems in Uruguay
In Uruguay, the increase of cropland area during the last decade was based on rotation systems intensification and soybean expansion, achieving 1.321.000 ha (Souto, 2014). Diaz (2007) demonstrated the value of the ley-farming systems where the integration of livestock and crop production achieved benefits on sustainability. Despite the advantages of crop-pasture rotation systems (García Prechac et al., 2004), grain market prices and food demand resulted in pasture phase losses in rotation with crops. Recently, Livestock Agriculture and Fisheries Ministry implemented a national soil conservation plan, that regulates cropping rotation systems based on soil erosion estimations and other key soil quality indicators. Although, no-till was full adopted, climatic and soil conditions determine that soil must be cover by residues or vegetation all year to reduce erosion and degradation (Thorup-Kristensen et al., 2003). Cover crops contribute to protect soils during fallow periods. The 17% of total soybean area cultivated is in Eastern Uruguay, being soils with erosion risk , fertility, structure and drainage limitations. This paper evaluates cover crops adaptation, subsequent effects on soybean productivity, and estimations of nitrogen supply and extraction from cover crops and soybean, respectively
Scouting Benefits and Developing Innovations in Temperate Grassland to Sustainable Agriculture Production
Agricultural intensification raises concern about land use and future effects to natural resources. The world demand for grain, meat and forest products is increasing constantly. Changes are occurring at large scale, being a compromise for policy makers to contribute to identify opportunities to readdress the productive scenario. There is available technology to reduce impacts, without restricting necessarily productivity. Grasslands provide a large series of economical and ecological benefits to the agricultural systems, being the literature exhaustive in examples. Ley-farming and cover crops technologies are good examples of environmentally sound soil management practices. The society is also worried about an improper use of the natural resources involved. The drastic increase in the grain crops area leaded by soybean in Uruguay, determined that the government implemented Sustainable Soil Use and Management Plans, based on erosion estimation using the USLE-RUSLE model adapted locally by research conducted over more than 50 years on a series of long term experimental platforms. There is an opportunity for this type of local innovative initiatives to be widely diffused, adopted or adapted. In essence, grasslands will continue playing a key role in maintaining a sustainable production
Assessment of satisfaction and Quality of Life using self - reported questionnaires after urethroplasty : a prospective analysis
Objectives: To assess patient satisfaction and quality of life after urethroplasty using two different self-reported outcome measures and to compare it with objective clinical data. Materials and Methods: We prospectively collected data from 35 consecutive patients who underwent urethroplasty from January 2013 to September 2014. Patient demographics, International Prostate Symptom Score (IPSS), quality of life score, urethral stricture surgery patient-reported outcome measure (USS-PROM), maximum flow rate (Qmax) and post-void residual urine were collected before, two and eight months after surgery. Failure occurred when any postoperative instrumentation was performed. General estimation equation was used to compare the results and linear regression analysis to correlate both questionnaires with objective data. Results: Mean age was 61 years. Urethroplasties were equally divided between anastomotic and buccal mucosa grafts and 19 patients (59.3%) had a previous urethral procedure. Overall success rate was 87.5%. IPSS improved from a mean 19 at baseline to 5.32 at 8 months (p <0.001). The mean USS-PROM score also improved from 13.21 preoperatively to 3.36 after surgery (p <0.001) and 84.3% of patients were satisfied or very satisfied with surgical results. Mean Qmax increased from 4.64mL/s to 11mL/s (p <0.001). Strong negative correlation was found respectively between flow rate and USS-PROM (r=-0.531, p <0.001) and with IPSS (r=-0.512, p <0.001). Conclusions: Significant improvements in urinary symptoms and in quality of life are expected after urethroplasty and they are correlated with objective measures
Digestive physiology and characterization of digestive cathepsin L-like proteinase from the sugarcane weevil Sphenophorus levis
Sugarcane is an important crop that has recently become subject to attacks from the weevil Sphenophorus levis, which is not efficiently controlled with chemical insecticides. This demands the development of new control devices for which digestive physiology data are needed. in the present study, ion-exchange chromatography of S. levis whole midgut homogenates, together with enzyme assays with natural and synthetic substrates and specific inhibitors, demonstrated that a cysteine proteinase is a major proteinase, trypsin is a minor one and chymotrypsin is probably negligible. Amylase, maltase and the cysteine proteinase occur in the gut contents and decrease throughout the midgut; trypsin is constant in the entire midgut, whereas a membrane-bound aminopeptidase predominates in the posterior midgut. the cysteine proteinase was purified to homogeneity through ion-exchange chromatography. the purified enzyme had a mass of 37 kDa and was able to hydrolyze Z-Phe-Arg-MCA and Z-Leu-Arg-MCA with k(cat)/K(m) values of 20.0 +/- 1.1 mu M(-1) s(-1) and 30.0 +/- 0.5 mu M(-1) s(-1), respectively, but not Z-Arg-Arg-MCA. the combined results suggest that protein digestion starts in the anterior midgut under the action of a cathepsin L-like proteinase and ends on the surface of posterior midgut cells. All starch digestion takes place in anterior midgut. These data will be instrumental to developing S. levis-resistant sugarcane. (C) 2011 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Univ São Paulo, Inst Chem, Dept Biochem, BR-05513970 São Paulo, BrazilUniv Fed Sao Carlos, Dept Genet & Evolut, Mol Biol Lab, BR-13565905 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biophys, BR-04044020 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biophys, BR-04044020 São Paulo, BrazilWeb of Scienc
Análise da utilização de um modelo de quatro fatores como ferramenta auxiliar para gestão de carteiras baseadas no IBrX
Using the price series of the assets that compose the IBrX in the period from May 2002 to December 2007, this article examines the influence of the variables beta, market value, price-earnings ratio and book-to-market ratio on the behavior of the Brazilian stock market, comparing the results with those of other studies carried out in Brazil. On investigating the influence of beta, we sought to verify if the premises of the CAPM are valid in the model proposed. We used the SUR and TSCS techniques to estimate the influence of the variables. The results indicate the significance of price-earnings and market value, but the book-to-market ratio presented the greatest stability and was significant in all the proposed models. In relation to the CAPM, the study shows that all the variables analyzed had some degree of influence on the cross-sectional variations of the average stock returns, indicating that other factors besides beta can be associated with the behavior of the assets.Esta pesquisa utilizou como banco de dados os ativos que compuseram o índice IBrX no período de maio de 2002 a dezembro de 2007, examinando a influência das variáveis beta, valor de mercado, índice preço/lucro e índice valor contábil/valor de mercado no comportamento no mercado brasileiro, confrontando o resultado com outras pesquisas realizadas no Brasil. Ao investigar a influência do beta este trabalhou buscou verificar se as premissas adotadas pelo CAPM são válidas no modelo proposto por este estudo. As técnicas de estimação utilizadas nesta pesquisa para estimar o grau de influência das variáveis foram o SUR e o TSCS. Os resultados apontaram significância para as variáveis índice Preço/Lucro e valor de mercado. Porém, a variável valor contábil/valor de mercado foi a que apresentou maior estabilidade sendo significante em todos os modelos propostos. Em relação ao CAPM a pesquisa apontou que todas as variáveis analisadas apresentaram algum grau de influência nas variações cross-section das rentabilidades médias das ações, sinalizando que além do beta, outros fatores podem estar associados ao comportamento dos ativos
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