457 resultados para Cannabinoides -- Efectes fisiològics


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This paper proposes a test statistic for the null hypothesis of panel stationarity that allows for the presence of multiple structural breaks. Two different speci¿cations are considered depending on the structural breaks affecting the individual effects and/or the time trend. The model is ¿exible enough to allow the number of breaks and their position to differ across individuals. The test is shown to have an exact limit distribution with a good ¿nite sample performance. Its application to a typical panel data set of real per capita GDP gives support to the trend stationarity of these series

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In this paper we examine the effect of tax policy on the relationship between inequality and growth in a two-sector non-scale model. With non-scale models, the longrun equilibrium growth rate is determined by technological parameters and it is independent of macroeconomic policy instruments. However, this fact does not imply that fiscal policy is unimportant for long-run economic performance. It indeed has important effects on the different levels of key economic variables such as per capita stock of capital and output. Hence, although the economy grows at the same rate across steady states, the bases for economic growth may be different.The model has three essential features. First, we explicitly model skill accumulation, second, we introduce government finance into the production function, and we introduce an income tax to mirror the fiscal events of the 1980¿s and 1990¿s in the US. The fact that the non-scale model is associated with higher order dynamics enables it to replicate the distinctly non-linear nature of inequality in the US with relative ease. The results derived in this paper attract attention to the fact that the non-scale growth model does not only fit the US data well for the long-run (Jones, 1995b) but also that it possesses unique abilities in explaining short term fluctuations of the economy. It is shown that during transition the response of the relative simulated wage to changes in the tax code is rather non-monotonic, quite in accordance to the US inequality pattern in the 1980¿s and early 1990¿s.More specifically, we have analyzed in detail the dynamics following the simulation of an isolated tax decrease and an isolated tax increase. So, after a tax decrease the skill premium follows a lower trajectory than the one it would follow without a tax decrease. Hence we are able to reduce inequality for several periods after the fiscal shock. On the contrary, following a tax increase, the evolution of the skill premium remains above the trajectory carried on by the skill premium under a situation with no tax increase. Consequently, a tax increase would imply a higher level of inequality in the economy

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This paper aims to analyse the effects of trade policies in the pattern of regional inequalities within a country. Inspired firstly, by the debate concerning the role of protectionist policies in the settlement of a pattern of striking regional inequalities in the Spanish industrialisation process and secondly, by current evidence of an increase in these inequalities following the entry of Spain in the EU (1986), we set a model that shows that trade liberalisation increases regional inequalities.

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En este artículo se analiza el grado de persistencia de las fluctuaciones cíclicas en la economía española. En concreto, se estudia si el PIB y el PIB por capita de esta economía presentan una raíz unitaria. Con el fin de evitar el sesgo a aceptar raíces unitarias cuando se producen cambios en la función de tendencia, como el originado por la Guerra Civil española (1936-1939), se han aplicado varios contrastes que tienen en cuenta los cambios en la función de tendencia. Los resultados obtenidos muestran que existe una importante evidencia en el sentido que el logaritmo del PIB presenta una raíz unitaria. La principal implicación de este resultado es que los shocks sobre el producto tienen efectos permanentes en el nivel del PIB de la economía española, aun cuando esta hipótesis es más difícil de aceptar por el PIB por capita vista la evidencia contradictoria encontrada a favor de la misma.

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This paper gives new evidence on the relationship between integration and industrial agglomeration in the presence of scale economies, by testing directly one of the predictions that can be derived from Krugman (1991), that is, the existence of regional nominal wage gradients and its transformation following changes in trade regimes. Our case study analyzes the effects of the substitution of an open economy by a closed economy regime, exactly the opposite process studied by Hanson (1996, 1997). In Spain, during the interwar period, protectionist policies would have favored the loss of centrality of the coastal location (Barcelona) and the relative rise of central locations (such as Madrid). Our results indicate the existence of a wage gradient centered in Barcelona during the interwar period (1914-1930) and its weakening after 1925.

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Este artículo, mediante el método de la Contabilidad Generacional, examina la viabilidad a largo plazo y los efectos sobre la redistribución intergeneracional de la renta del sistema de pensiones español. Dado la enorme deuda acumulada, que se traslada a las generaciones futuras, se explora la posibilidad de introducir políticas de reforma por el lado de los ingresos que pretenden mitigar la fuerte dependencia demográfica de las finanzas de la Seguridad Social. El principal resultado obtenido es que la gravedad de la crisis demográfica hace que estos tipos de medidas estudiadas sean claramente insuficientes para restaurar el equilibrio intergeneracional.

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This paper tests some hypothesis about the determinants of the local tax structure. In particular, we focus on the effects that the property tax deductibility in the national income tax has on the relative use of the property tax and user charges. We deal with the incentive effects that local governments face regarding the different sources of revenue by means of a model in which the local tax structure and the level of public expenditure arise as a result of the maximizing behaviour of local politicians subject to the economic effects of the tax system. We attempt to test the hypothesis developed with data corresponding to a set of Spanish municipalities during the period 1987-9l. We find that tax deductibility provides incentives to raise revenues from the property tax but does not introduce a biass against user charges or in favor of overall spending growth

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El presente trabajo analiza desde un punto de vista cuantitativo, mediante un modelo de equilibrio general de generaciones sucesivas, los efectos sobre la economía española de eliminar el actual sistema de Seguridad Social e implantar uno de capitalización. El análisis considera el proceso de transición y mide en términos de bienestar, quiénes son los agentes que se opondrían a este tipo de reforma. La consideración de la interacción entre el sistema de seguridad social y el sistema fiscal implica mayores beneficios asociados a una reforma de la seguridad social. Sin embargo, este tipo de reforma sigue generando pérdidas de bienestar para la mayoría de agentes vivos en el momentodel inicio de la reforma, existiendo un sesgo en favor del status quo.

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One of the limitations of cross-country health expenditure analysis refers to the fact that the financing, the internal organization and political restraints of health care decision-making are country-specific and heterogeneous. Yet, a potential solution is to examine the influence of such effects in those countries that have undertaken decentralization processes. In such a setting, it is possible to examine potential expenditure spillovers across the geography of a country as well as the influence of the political ideology of regional incumbents on public health expenditure. This paper examines the determinants of public health expenditure within Spanish region-states (Autonomous Communities, ACs), most of them subject to similar financing structures although exhibiting significant heterogeneity as a result of the increasing decentralization, region-specific political factors along with different use of health care inputs, economic dimension and spatial interactions

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The age at which school children begin instruction in the foreign language has been brought forward on two main grounds: (1) young children are better language learners than older children, and (2) bilingualism brings cognitive advantages to children. Both statements are critically analysed in this paper. First of all, recent research findings show that the advantage that younger learners show in a naturalistic language learning situation (or through school immersion) disappears in a formal language learning situation with very limited exposure to the target language. Secondly, the positive effects on cognitive development that have been revealed through research correspond to situations of balanced bilingualism, that is, situations in which children have a high command of the two languages. In contrast, children¿s command of the foreign language in our context is very limited and hence far from the situation of balanced bilingualism (or trilingualism) that is said to bring positive cognitive effects.

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The purpose of this article is to treat a currently much debated issue, the effects of age on second language learning. To do so, we contrast data collected by our research team from over one thousand seven hundred young and adult learners with four popular beliefs or generalizations, which, while deeply rooted in this society, are not always corroborated by our data.Two of these generalizations about Second Language Acquisition (languages spoken in the social context) seem to be widely accepted: a) older children, adolescents and adults are quicker and more efficient at the first stages of learning than are younger learners; b) in a natural context children with an early start are more liable to attain higher levels of proficiency. However, in the context of Foreign Language Acquisition, the context in which we collect the data, this second generalization is difficult to verify due to the low number of instructional hours (a maximum of some 800 hours) and the lower levels of language exposure time provided. The design of our research project has allowed us to study differences observed with respect to the age of onset (ranging from 2 to 18+), but in this article we focus on students who began English instruction at the age of 8 (LOGSE Educational System) and those who began at the age of 11 (EGB). We have collected data from both groups after a period of 200 (Time 1) and 416 instructional hours (Time 2), and we are currently collecting data after a period of 726 instructional hours (Time 3). We have designed and administered a variety of tests: tests on English production and reception, both oral and written, and within both academic and communicative oriented approaches, on the learners' L1 (Spanish and Catalan), as well as a questionnaire eliciting personal and sociolinguistic information. The questions we address and the relevant empirical evidence are as follows: 1. "For young children, learning languages is a game. They enjoy it more than adults."Our data demonstrate that the situation is not quite so. Firstly, both at the levels of Primary and Secondary education (ranging from 70.5% in 11-year-olds to 89% in 14-year-olds) students have a positive attitude towards learning English. Secondly, there is a difference between the two groups with respect to the factors they cite as responsible for their motivation to learn English: the younger students cite intrinsic factors, such as the games they play, the methodology used and the teacher, whereas the older students cite extrinsic factors, such as the role of their knowledge of English in the achievement of their future professional goals. 2 ."Young children have more resources to learn languages." Here our data suggest just the opposite. The ability to employ learning strategies (actions or steps used) increases with age. Older learners' strategies are more varied and cognitively more complex. In contrast, younger learners depend more on their interlocutor and external resources and therefore have a lower level of autonomy in their learning. 3. "Young children don't talk much but understand a lot"This third generalization does seem to be confirmed, at least to a certain extent, by our data in relation to the analysis of differences due to the age factor and productive use of the target language. As seen above, the comparably slower progress of the younger learners is confirmed. Our analysis of interpersonal receptive abilities demonstrates as well the advantage of the older learners. Nevertheless, with respect to passive receptive activities (for example, simple recognition of words or sentences) no great differences are observed. Statistical analyses suggest that in this test, in contrast to the others analyzed, the dominance of the subjects' L1s (reflecting a cognitive capacity that grows with age) has no significant influence on the learning process. 4. "The sooner they begin, the better their results will be in written language"This is not either completely confirmed in our research. First of all, we perceive that certain compensatory strategies disappear only with age, but not with the number of instructional hours. Secondly, given an identical number of instructional hours, the older subjects obtain better results. With respect to our analysis of data from subjects of the same age (12 years old) but with a different number of instructional hours (200 and 416 respectively, as they began at the ages of 11 and 8), we observe that those who began earlier excel only in the area of lexical fluency. In conclusion, the superior rate of older learners appears to be due to their higher level of cognitive development, a factor which allows them to benefit more from formal or explicit instruction in the school context. Younger learners, however, do not benefit from the quantity and quality of linguistic exposure typical of a natural acquisition context in which they would be allowed to make use of implicit learning abilities. It seems clear, then, that the initiative in this country to begin foreign language instruction earlier will have positive effects only if it occurs in combination with either higher levels of exposure time to the foreign language, or, alternatively, with its use as the language of instruction in other areas of the curriculum.

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This paper analyzes the relationship between spatial density of economic activity and interregional differences in the productivity of industrial labour in Spain during the period 1860-1999. In the spirit of Ciccone and Hall (1996) and Ciccone (2002), we analyze the evolution of this relationship over the long term in Spain. Using data on the period 1860-1999 we show the existence of an agglomeration effect linking the density of economic activity with labour productivity in the industry. This effect was present since the beginning of the industrialization process in the middle of the 19th century but has been decreasing over time. The estimated elasticity of labour productivity with respect to employment density was close to 8% in the subperiod 1860-1900, reduces to a value of around 7% in the subperiod 1914-1930, to 4% in the subperiod 1965-1979 and becomes insignificant in the final subperiod 1985-1999. At the end of the period analyzed there is no evidence of the existence of net agglomeration effects in the industry. This result could be explained by an important increase in the congestion effects in large industrial metropolitan areas that would have compensated the centripetal or agglomeration forces at work. Furthermore, this result is also consistent with the evidence of a dispersion of industrial activity in Spain during the last decades.

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En este artículo se analizan los determinantes de la localización de la actividad industrial en España durante la segunda mitad del siglo XIX. El objetivo es estudiar la existencia de cambios en los factores explicativos de la localización, con el fin de identificar los efectos de la integración económica sobre la geografía industrial española. Para hacerlo, en primer lugar se analiza la literatura histórica existente. En segundo lugar, se describen las teorías que explican la localización de l'actividad. En tercer lugar, se realiza un análisis empírico de la localización y la concentración de la industria española al siglo XIX. A continuación, se propone un estudio econométrico de los determinantes de la localización industrial en dos cortes temporales, 1856 y 1893. Los resultados son consistentes con las teorías del comercio. Durante el decurso de la segunda mitad del siglo XIX, España paso a ser una economía integrada, la movilidad del trabajo y del capital se vio favorecida y como resultado, las diferencias relativas en las dotaciones de factores perdieron importancia en la explicación de las pautas de especialización industrial. Por el contrario, la integración económica favoreció la significación relativa de las economías de escala o de la proximidad a los mercados como elementos explicativos de la localización de la industria, favoreciendo, de esta manera, la aglomeración de la actividad industrial

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This paper gives new evidence on the relationship between integration and industrial agglomeration in the presence of scale economies, by testing directly one of the predictions that can be derived from Krugman (1991), that is, the existence of regional nominal wage gradients and its transformation following changes in trade regimes. Our case study analyzes the effects of the substitution of an open economy by a closed economy regime, exactly the opposite process studied by Hanson (1996, 1997). In Spain, during the interwar period, protectionist policies would have favored the loss of centrality of the coastal location (Barcelona) and the relative rise of central locations (such as Madrid). Our results indicate the existence of a wage gradient centered in Barcelona during the interwar period (1914-1930) and its weakening after 1925.

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Aquest article és fruit de la recerca duta a terme en el marc del projecte conjunt REDICE08, PID08, PID09 'Com motivar, com adequar l"avaluació continuada i com mesurar el treball a les assignatures de Matemàtiques' durant els cursos 2008 2009 i 2009-2010. El projecte aborda temes relacionats amb els resultats de les enquestes sobre l"actuació docent del professorat a l"ensenyament de Matemàtiques de la Universitat de Barcelona (UB), en què l"alumnat posa de manifest, en general, un baixa motivació del professorat i un elevat volum de feina en les assignatures. Com a resultat de l"estudi i de la pràctica docent en les assignatures involucrades en el projecte citat abans, es desprèn que la motivació de l"alumnat s"aconsegueix sumant esforços en diferents direccions: d"una banda, cal una tria adequada i una bona comunicació dels continguts, que fomenti el diàleg amb l"alumnat; d"altra banda, cal que l"avaluació continuada presenti un esglaonament progressiu en la dificultat de les activitats no presencials i una atenció continuada a l"alumnat mentre les duu a terme. Finalment, cal quantificar la dedicació de l"alumnat a les diferents activitats no presencials, ja que serveix de gran ajuda al professorat a l"hora d"adequar-les a la dedicació requerida, i ponderar les diferents activitats d"avaluació acreditativa en la qualificació de forma proporcional a aquesta dedicació. La motivació pren molta força com a element clau que cal tenir en compte en el bon desenvolupament de la docència universitària. L"alumnat motivat respon amb una més gran dedicació, cosa que comporta la integració de l"alumnat en les assignatures, millors resultats acadèmics i una millor motivació del professorat. Aquest cicle de motivació es va realimentant i va produint efectes molt positius tant en el professorat com en l"alumnat. Una consideració final és que el camí per millorar la docència a Matemàtiques és, segurament, llarg. Tot i així, les reflexions i les actuacions fetes per un nombre considerable de professors de diferents disciplines i departaments de la Facultat de Matemàtiques són experiències que segurament serviran en moltes assignatures de Matemàtiques i d"altres ensenyaments.