Avaliação econômica dos métodos de irrigação por gotejo e por sulco na cultura do melão.

Realizou-se uma análise econômica de um trabalho de comparação de métodos de irrigação realizado no período de agosto a novembro de 1977 no Campo Experimental de Bebedouro, pertencente ao Centro de Pesquisa Agropecuária do Trópico Semi-Árido (EMBRAPA), Petrolina, PE. Foram apropriados os custos e benefícios dos métodos de irrigação por sulcos e gotejo em diversas condições de manejo na cultura do melão, variedade Valenciano Amarelo.bitstream/item/133206/1/32103-1.pd

Torção aguda do cordão espermático: factor de risco para anticorpos anti-espermatozóides?

A torção aguda do cordão espermático é uma urgência urológica dada a isquémia testicular acompanhante, podendo mesmo levar à necrose testicular se não resolvida atempadamente. A correcção cirúrgica passa pela destorção do cordão espermático atingido e orquidopexia bilateral ou, na presença de torção com isquémia testicular irreversível, pela orquidectomia e orquidopexia contralateral. As eventuais sequelas desta entidade clínica independentemente da cirurgia efectuada, passam por alterações quantitativas e/ou qualitativas do espermograma com repercussão ainda mal esclarecidaemtermos de fertilidade masculina. Caracterizámos os valores de testosterona total, espermograma e a presença sérica de anticorpos anti-espermatozóides (AAE) em 9 doentes com torção aguda unilateral do cordão espermático de modo a caracterizar a sua prevalência nesta amostra comparando os resultados com grupo controlo de 15 indivíduos. Todos os doentes obtiveram valores normais de testosterona total sérica. Cinco doentes não apresentaram AAE, representando 55,6% da amostra e quatro doentes apresentaram AAE, representando 44,4% da amostra. O tempo médio entre a cirurgia e a pesquisa de anticorpos foi de 23,75 meses (6-66) para doentes com AAE positivos e 37,2 meses (10-48) para doentes com AAE negativos. O espermograma revelou-se normal em todos os parâmetros avaliados em apenas três doentes (um com AAE e dois semAAE) e anormal em seis doentes (três com AAE e três sem AAE). Os dois doentes com concentrações mais baixas de espermatozóides apresentavam AAE. Os 15 indivíduos do grupo de controlo não apresentaram AAE. O nosso estudo aponta a torção do cordão espermático como factor de risco para a presença de AAE e para alterações do espermograma, independentemente da presença de AAE e da correcção cirúrgica efectuada

Impact of motor vehicles-bicycles interaction on route selection, traffic performance, emissions and safety

No abstract available.publishe

Ensuring successful introduction of Wolbachia in natural populations of Aedes aegypti by means of feedback control

The control of the spread of dengue fever by introduction of the intracellular parasitic bacterium Wolbachia in populations of the vector Aedes aegypti, is presently one of the most promising tools for eliminating dengue, in the absence of an efficient vaccine. The success of this operation requires locally careful planning to determine the adequate number of individuals carrying the Wolbachia parasite that need to be introduced into the natural population. The introduced mosquitoes are expected to eventually replace the Wolbachia-free population and guarantee permanent protection against the transmission of dengue to human. In this study, we propose and analyze a model describing the fundamental aspects of the competition between mosquitoes carrying Wolbachia and mosquitoes free of the parasite. We then use feedback control techniques to devise an introduction protocol which is proved to guarantee that the population converges to a stable equilibrium where the totality of mosquitoes carry Wolbachia.Comment: 24 pages, 5 figure

Gene identification for the cblD defect of vitamin B12 metabolism

Background Vitamin B12 (cobalamin) is an essential cofactor in several metabolic pathways. Intracellular conversion of cobalamin to its two coenzymes, adenosylcobalamin in mitochondria and methylcobalamin in the cytoplasm, is necessary for the homeostasis of methylmalonic acid and homocysteine. Nine defects of intracellular cobalamin metabolism have been defined by means of somatic complementation analysis. One of these defects, the cblD defect, can cause isolated methylmalonic aciduria, isolated homocystinuria, or both. Affected persons present with multisystem clinical abnormalities, including developmental, hematologic, neurologic, and metabolic findings. The gene responsible for the cblD defect has not been identified. Methods We studied seven patients with the cblD defect, and skin fibroblasts from each were investigated in cell culture. Microcell-mediated chromosome transfer and refined genetic mapping were used to localize the responsible gene. This gene was transfected into cblD fibroblasts to test for the rescue of adenosylcobalamin and methylcobalamin synthesis. Results The cblD gene was localized to human chromosome 2q23.2, and a candidate gene, designated MMADHC (methylmalonic aciduria, cblD type, and homocystinuria), was identified in this region. Transfection of wild-type MMADHC rescued the cellular phenotype, and the functional importance of mutant alleles was shown by means of transfection with mutant constructs. The predicted MMADHC protein has sequence homology with a bacterial ATP-binding cassette transporter and contains a putative cobalamin binding motif and a putative mitochondrial targeting sequence. Conclusions Mutations in a gene we designated MMADHC are responsible for the cblD defect in vitamin B12 metabolism. Various mutations are associated with each of the three biochemical phenotypes of the disorder

O gálio e a patologia óssea.

Estima-se que mais de 200.000 cirurgias para fusão da coluna vertebral são realizadas a cada ano nos EUA. Artrodese lombar posterolateral intertransversalis é o procedimento mais comum realizado, ainda que a falha para obter uma sólida união óssea ocorre em 10% a 40% dos pacientes com único nível envolvido e mais freqüentemente em múltiplos níveis. Esta alta taxa de pseudoartrose indica que eventos fisiológicos, biológicos e químicos, cruciais para este processo, não são adequadamente compreendidos. A não união óssea frequentemente leva a uma resolução insatisfatória dos sintomas clínicos e usualmente resulta em maior custo médico e morbidade, bem como a necessidade de intervenções adicionais(1). Infelizmente, o efeito dos íons metálicos no processo de mineralização não tem recebido considerável atenção até recentemente, entretanto dados interessantes da participação do alumínio e gálio no metabolismo ósseo foram publicados há mais de 15 anos(2). Atualmente, o número de publicações dedicadas ao papel do gálio na patologia óssea está crescendo rapidamente, todavia, revisões abrangentes não estão disponíveis. A intenção do presente estudo é preencher esta lacuna, considerando a formação, crescimento e solubilidade da hidroxiapatita na presença de sais de gálio, a incorporação do gálio dentro do tecido ósseo e o mecanismo de atividade terapêutica deste elemento

Ages, metallicities and α\alpha-element enhancement for galaxies in Hickson compact groups

Central velocity dispersions and eight line-strength Lick indices have been determined from 1.3${\rm \AA}$ resolution long-slit spectra of 16 elliptical galaxies in Hickson compact groups. These data were used to determine galaxy properties (ages, metallicities and $\alpha$-element enhancements) and allowed a comparison with the parameters determined for a sample of galaxies in lower density environments, studied by Gonz\'alez (1993). The stellar population parameters were derived by comparison to single stellar population models of Thomas et al. (2003) and to a new set of SSP models for the indices Mg$_2$, Fe5270 and Fe5335 based on synthetic spetra. These models, based on an update version of the fitting functions presented in Barbuy et al. (2003), are fully described here. Our main results are: (1) the two samples have similar mean values for the metallicities and [$\alpha$/Fe] ratios, (2) the majority of the galaxies in compact groups seem to be old (median age of 14 Gyr for eight galaxies for which ages could be derived), in agreement with recent work by Proctor et al. (2004). These findings support two possible scenarios: compact groups are either young systems whose members have recently assembled and had not enough time to experience any merging yet or, instead, they are old systems that have avoided merging since their time of formation.Comment: Accepted for publication in A

Quantifying Global Tolerance of Biochemical Systems: Design Implications for Moiety-Transfer Cycles

Robustness of organisms is widely observed although difficult to precisely characterize. Performance can remain nearly constant within some neighborhood of the normal operating regime, leading to homeostasis, but then abruptly break down with pathological consequences beyond this neighborhood. Currently, there is no generic approach to identifying boundaries where local performance deteriorates abruptly, and this has hampered understanding of the molecular basis of biological robustness. Here we introduce a generic approach for characterizing boundaries between operational regimes based on the piecewise power-law representation of the system's components. This conceptual framework allows us to define “global tolerance” as the ratio between the normal value of a parameter and the value at such a boundary. We illustrate the utility of this concept for a class of moiety-transfer cycles, which is a widespread module in biology. Our results show a region of “best” local performance surrounded by “poor” regions; also, selection for improved local performance often pushes the operating values away from regime boundaries, thus increasing global tolerance. These predictions agree with experimental data from the reduced nicotinamide adenine dinucleotide phosphate (NADPH) redox cycle of human erythrocytes