971 resultados para Inputs supraspinal


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In this paper we seek to verify the hypothesis that trust and cooperation between individuals, and between them and public institutions, can encourage technological innovation and the adoption of knowledge. Additionally, we test the extent to which the interaction of social capital with human capital and R&D expenditures improve their effect on a region’s ability to innovate. Our empirical evidence is taken from the Spanish regions and employs a knowledge production function and longitudinal count data models. Our results suggest that social capital correlates positively with innovation. Further, our analysis reveals a powerful interaction between human and social capital in the production of knowledge, whilst the complementarity with R&D efforts would seem less clear.

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The aim of the present study was to determine if phenobarbital affects the nociception threshold. Systemic (1-20 mg/kg) phenobarbital administration dose dependently induced hyperalgesia in the tail-flick, hot-plate and formalin tests in rats and in the abdominal constriction test in mice. Formalin and abdominal constriction tests were the most sensitive procedures for the detection of hyperalgesia in response to phenobarbital compared with the tail-flick and hot-plate tests. The hyperalgesia induced by systemic phenobarbital was blocked by previous administration of 1 mg/kg ip picrotoxin or either 1-2 mg/kg sc or 10 ng icv bicuculline. Intracerebroventricular phenobarbital administration (5 µg) induced hyperalgesia in the tail-flick test. In contrast, intrathecal phenobarbital administration (5 µg) induced antinociception and blocked systemic-induced hyperalgesia in this test. We suggest that phenobarbital may mediate hyperalgesia through GABA-A receptors at supraspinal levels and antinociception through the same kind of receptors at spinal levels.

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We apply to the Senegalese input-output matrix of 1990, disagregated into formal and informal activities, a recently designed structural analytical method (Minimal-Flow-Analysis) which permits to depict the direct and indirect production likanges existing between activities.

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Research on soil fertility management in sub-Saharan Africa was criticized lately for largely ignoring farmers’ management strategies and the underlying principles. To fill this gap of knowledge, detailed interviews were conducted with 108 farm households about their rationale in managing the soil fertility of 307 individual fields in the agro-pastoral village territory of Chikal in western Niger. To amplify the farmers’ information on manuring and corralling practices, repeated measurements of applied amounts of manure were carried out within six 1-km^2 monitoring areas from February to October 1998. The interviews revealed that only 2% of the fields were completely fallowed for a period of 1–15 years, but 40% of the fields were at least partially fallowed. Mulching of crop residues was mainly practiced to fight wind erosion but was restricted to 36% of the surveyed fields given the alternative use of straw as livestock feed. Manure application and livestock corralling, as most effective tools to enhance soil fertility, were targeted to less than 30% of the surveyed fields. The application of complete fallow and manuring and corralling practices were strongly related to the households’ endowment with resources, especially with land and livestock. Within particular fields, measures were mainly applied to spots of poor soil fertility, while the restoration of the productivity of hard pans was of secondary importance. Given the limited spatial coverage of indigenous soil fertility measures and their strong dependence on farmers’ wealth, supplementary strategies to restrict the decline of soil fertility in the drought prone areas of Niger with their heavily weathered soils are needed.

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In West Africa, yam can be an important crop to reduce poverty and hunger if Research and Development measures identify and properly engage its key production factors for enhanced outputs and better income. Data from 1400 households in Ghana and Nigeria were collected in a multistage random sampling survey (and complementary data from 76 farm family fields) with a structured questionnaire and qualitative interview questions. The results showed that yam is produced mainly with crude inputs/technologies to reduce high dependence on labour, seed production and control of pests and diseases. Yam is produced widely with purchased inputs including seed yam and hired labour; chemical fertiliser, herbicide and pesticides are less often used. Analyses of determinants of use of purchased inputs reveal three serious impediments to expansion in yam production: the increasing scarcity and high cost of hired labour, shortage of suitable land and poor farm roads. As employment opportunities for unskilled labour in urban centres are presently expanding, increased yam production will be hard to achieve without labour-saving inputs for at least some of the production tasks, especially seedbed preparation and weeding, and without improvement in infrastructure.

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This thesis explores the correlation between school factors and the differentiated results on sexual behaviour between boys and girls in Bogota. A school stratified propensity score matching was performed to match each boy of the sample with the most similar girls in individual, household and school characteristics. A regression analysis was performed to estimate the correlation between the five school factors evaluated with four main outcomes: have had sexual intercourse, condom use in the last sexual intercourse, incidence of teenage childbearing and age at first intercourse. Boys - in relation to girls - begin earlier their sexual life, more of them reported have used condom in their last sexual intercourse and have a lower incidence of teenage childbearing. These differences are correlated with have reported the school as main source of knowledge about reproductive health and contraceptive methods, a larger proportion of teachers with a graduate or postgraduate degree, a larger proportion of teachers with a related pedagogy degree and to the average age of teachers in the school. The results suggest that the content of the message about sex that is delivered to girls at school is not complete or accurate and that the competences of the school teachers in charge of this task should be improved to reach equally boys and girls.

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This paper explores the correlation between school factors and the differentiated results on sexual behavior between boys and girls in Bogota. A school stratified propensity score matching was per-formed to match each boy of the sample with the most similar girls in individual, household and school characteristics. A regression analysis was performed to estimate the correlation between school factors and the main outcomes, namely sexual status, condom use in last intercourse, teenage childbearing and age at first intercourse. Boys - in relation to girls - begin earlier their sexual life, report larger use of condom and lower incidence of teenage childbearing. These differences are correlated with sex education at school, and teacher’s characteristics age, education level and pedagogy degree. The results suggest that the content of sex education that is delivered to girls at school is not complete or accurate and that teachers play a key role to reduce this gender bias

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Se estudia cómo se percibe el ocio en los manuales de ELE utilizados en la enseñanza pública marroquí en los últimos cuarenta años. Se analizan desde una perspectiva multimodal los aspectos socioculturales y la manera en que éstos se transmiten a través de los inputs visuales. Se valoran especialmente la imagen que se muestra de lo hispánico y los valores que con ella se pretenden trasmitir. Para llevar a cabo este análisis se ha elaborado una ficha metodológica adaptada al contexto marroquí y a las particularidades y especificidades del mismo, tales como el plurilingüismo y la importancia que el sistema educativo de Marruecos concede al estudio de las segundas lenguas.

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Memoria de Máster de formación de profesores de ELE (Universitat de Barcelona, 2007). Resumen basado en el de la publicación

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An inventory of heavy metal inputs (Zn, Cu, Ni, Pb, Cd, Cr, As and Hg) to agricultural soils in England and Wales in 2000 is presented, accounting for major sources including atmospheric deposition, sewage sludge, livestock manures, inorganic fertilisers and lime, agrochemicals, irrigation water, industrial by-product 'wastes' and composts. Across the whole agricultural land area, atmospheric deposition was the main source of most metals, ranging from 25 to 85% of total inputs. Livestock manures and sewage sludge were also important sources, responsible for an estimated 37-40 and 8-17% of total Zn and Cu inputs, respectively. However, at the individual field scale sewage sludge, livestock manures and industrial wastes could be the major source of many metals where these materials are applied. This work will assist in developing strategies for reducing heavy metal inputs to agricultural land and effectively targeting policies to protect soils from long-term heavy metal accumulation. (C) 2003 Elsevier Science B.V. All rights reserved.

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This study used the novel approach of statistical modelling to investigate the control of hypothalamic-pituitary-adrenal (HPA) axis and quantify temporal relationships between hormones. Two experimental paradigms were chosen, insulin-induced hypoglycaemia and 2 h transport, to assess differences in control between noncognitive and cognitive stimuli. Vasopressin and corticotropin-releasing hormone (CRH) were measured in hypophysial portal plasma, and adrenocorticotropin hormone (ACTH) and cortisol in jugular plasma of conscious sheep, and deconvolution analysis was used to calculate secretory rates, before modelling. During hypoglycaemia, the relationship between plasma glucose and vasopressin or CRH was best described by log(10) transforming variables (i.e. a positive power-curve relationship). A negative-feedback relationship with log(10) cortisol concentration 2 h previously was detected. Analysis of the 'transport' stimulus suggested that the strength of the perceived stimulus decreased over time after accounting for cortisol facilitation and negative-feedback. The time course of vasopressin and CRH responses to each stimulus were different However, at the pituitary level, the data suggested that log(10) ACTH secretion rate was related to log(10) vasopressin and CRH concentrations with very similar regression coefficients and an identical ratio of actions (2.3 : 1) for both stimuli. Similar magnitude negative-feedback effects of log(10) cortisol at -110 min (hypoglycaemia) or -40 min (transport) were detected, and both models contained a stimulatory relationship with cortisol at 0 min (facilitation). At adrenal gland level, cortisol secretory rates were related to simultaneously measured untransformed ACTH concentration but the regression coefficient for the hypoglycaemia model was 2.5-fold greater than for transport. No individual sustained maximum cortisol secretion for longer than 20 min during hypoglycaemia and 40 min during transport. These unique models demonstrate that corticosteroid negative-feedback is a significant control mechanism at both the pituitary and hypothalamus. The amplitude of HPA response may be related to stimulus intensity and corticosteroid negative-feedback, while duration depended on feedback alone.

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Boolean input systems are in common used in the electric industry. Power supplies include such systems and the power converter represents these. For instance, in power electronics, the control variable are the switching ON and OFF of components as thyristors or transistors. The purpose of this paper is to use neural network (NN) to control continuous systems with Boolean inputs. This method is based on classification of system variations associated with input configurations. The classical supervised backpropagation algorithm is used to train the networks. The training of the artificial neural network and the control of Boolean input systems are presented. The design procedure of control systems is implemented on a nonlinear system. We apply those results to control an electrical system composed of an induction machine and its power converter.

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The flux of nitrogen (N) to coastal marine ecosystems is strongly correlated with the “net anthropogenic nitrogen inputs” (NANI) to the landscape across 154 watersheds, ranging in size from 16 km2 to 279 000 km2, in the US and Europe. When NANI values are greater than 1070 kg N km−2 yr−1, an average of 25% of the NANI is exported from those watersheds in rivers. Our analysis suggests a possible threshold at lower NANI levels, with a smaller fraction exported when NANI values are below 1070 kg N km−2 yr−1. Synthetic fertilizer is the largest component of NANI in many watersheds, but other inputs also contribute substantially to the N fluxes; in some regions, atmospheric deposition of N is the major component. The flux of N to coastal areas is controlled in part by climate, and a higher percentage of NANI is exported in rivers, from watersheds that have higher freshwater discharge.