1000 resultados para Investigaciones científicas


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La Segunda República dedicó cuantiosos recursos, económicos y humanos, a la cartografía de las posesiones coloniales. Los sucesivos gobiernos republicanos mantuvieron una fuerte continuidad, organizativa y funcional, en el ámbito de la cartografía colonial, sin que se detecte ningún cambio significativo respecto a los planes trazados en etapas anteriores. La actividad cartográfica continuó centrada en el territorio de Marruecos, y fue protagonizada por una unidad dependiente del Ministerio de la Guerra, la Comisión Geográfica de Marruecos y Límites. En este trabajo, que se apoya en fuentes primarias, se ofrece una descripción del marco institucional de la cartografía colonial durante el período republicano, se identifica a sus artífices, y se da cuenta de los levantamientos cartográficos realizados.

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El debate sobre las medidas alternativas a la prisión y, en particular, sobre el trabajo en beneficio de la comunidad, ha adquirido un renovado interés durante los últimos años, a raíz del progresivo aumento de la población reclusa española. Partiendo de las diversas teorías que existen sobre la pena, se pretende mostrar que, tras más de diez años de haberse aprobado el Código penal vigente, esa medida, aunque ha experimentado recientemente una notable expansión, sigue sin alcanzar su máximo desarrollo, a pesar de los efectos positivos ya demostrados en otros países de nuestro entorno, en cuanto a su mayor eficacia en la reinserción social de las personas encausadas y, por consiguiente, en la disminución de la densidad carcelaria.

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The bio-economic model "Heures" is a first attempt to develop a simulation procedure to understand the Northwestern Mediterranean fisheries, to evaluate management strategies and to analyze the feasibility of implementing an adaptative management. The model is built on the interaction among three boxes simulating the dynamics of each of the basic actors of a fishery: the stock, the market and the fishermen. A fourth actor, the manager, imposes or modifies the rules, or, in terms of the model, modifies some particular parameters. Thus, the model allows us to simulate and evaluate the mid-term biologic and economic effects of particular management measures. The bio-economic nature of the model is given by the interaction among the three boxes, by the market simulation and, particularly, by the fishermen behaviour. This last element confers to the model its Mediterranean"selfregulated" character. The fishermen allocate their investments to maximize fishing mortality but, having a legal effort limit, they invest in maintenance and technology in order to increase the catchability, which, as a consequence. will be function of the invested capital.

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The theoretical aspects and the associated software of a bioeconomic model for Mediterranean fisheries are presented. The first objective of the model is to reproduce the bioeconomic conditions in which the fisheries occur. The model is, perforce, multispecies and multigear. The main management procedure is effort limitation. The model also incorporates the usual fishermen strategy of increasing efficiency to obtain increased fishing mortality while maintaining the nominal effort. This is modelled by means of a function relating the efficiency (or technological progress) with the capital invested in the fishery and time. A second objective is to simulate alternative management strategies. The model allows the operation of technical and economic management measures in the presence of different kind of events. Both deterministic and stochastic simulations can be performed. An application of this tool to the hake fishery off Catalonia is presented, considering the other species caught and the different gears used. Several alternative management measures are tested and their consequences for the stock and economy of fishermen are analysed.

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La creación de un espacio europeo de libertad, seguridad y justicia en el ámbito civil ha recibido un impulso decisivo con el Tratado de Amsterdam, pero no se trata de una materia absolutamente nueva. En efecto, el art. 220 TCE en su versión original de 1958 dispone que los Estados miembros «entablarán en tanto sea necesario, negociaciones entre sí a fin de asegurar a favor de sus nacionales», entre otras cosas, para «la simplificación de las formalidades a que están sometidos el reconocimiento y la ejecución recíprocos de las decisiones judiciales y de los laudos arbitrales

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La coyuntura política del reino de Túnez repercutió de forma decisiva sobre las aspiraciones y fracasos de sus relaciones diplomáticas y comerciales con las potencias europeas. Tras un periodo prolongado jalonado por acuerdos sucesivos, las viejas pretensiones tributarias de la Corona de Aragón alcanzarán a ser reconocidas en el tratado suscrito en 1360, aunque aquel acuerdo no conseguirá hacer efectiva en la práctica dicha reclamación. El fortalecimiento del poder de los Hafsíes en las últimas décadas del siglo XIV reabre un periodo de confrontación velada con la intensificación de las actividades corsarias, que culminan en sendas expediciones de castigo sobre puertos magrebíes. El tratado de 1403 pondrá fin a dichas hostilidades y reabrirá una nueva estrategia en las relaciones con el Magreb Hafsída.

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The isotopic concentrations of carapace scutes, skin, muscle and blood of loggerhead sea turtles (Caretta caretta) from the Balearic Archipelago were analysed to investigate the pattern of variation between tissues and to assess the position of this species in the trophic webs of the Algerian Basin. Skin showed higher δ13C values than muscle or carapace scutes and these showed higher values than blood. Conversely, muscle showed higher δ15N values than skin, skin showed higher values than blood and blood showed higher values than carapace scutes. Dead and live sea turtles from the same habitat did not differ in the concentration of stable isotopes. However, some of the tissues of the turtles caught in drifting longlines in the oceanic realm showed higher δ13C values than those from the turtles caught by hand or in trammel nets over the continental shelf, although they did not differ in the δ15N. Comparison of the concentration of stable isotopes in the turtles with that of other species from several areas of the Algerian Basin revealed that they consumed planktonic prey and that the trophic level of the sea turtles was higher than that of carnivorous cnidarians but lower than that of zooplanktophagous fish and crustaceans.

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Exchange of immature loggerhead sea turtles (Caretta caretta) between the northern and southern regions of the western Mediterranean was investigated using data obtained from several Spanish tagging programmes. Tagged turtles ranged in straight carapace length from 23.0 to 74.0 cm. Thirty-six turtles were recaptured after an average interval of 390.5±462.6 days (SD). As the mean dispersal distance (MDD) of a turtle population that spreads over the western Mediterranean would stabilize after 117 days (CI 95%: 98 to 149), two analyses were conducted that included data from turtles recaptured after 98 and 149 days respectively. In both analyses, turtles were recaptured more often than expected in the same region where they had been tagged. No difference was found in either of the two regions between the average distance between the capture and recapture locations and the expected MDD if the turtles were to remain in the region where they were first captured. Turtles recaptured after 15 and 25 days respectively were excluded from the analysis to ensure data independence. The overall evidence indicates that immature turtles exhibit strong site fidelity to certain areas and that there is a strong barrier to dispersal between the northern and southern parts of the western Mediterranean. Therefore, loggerhead turtles in the western Mediterranean should be split into at least two management units.

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This study tests the hypothesis that female South American sea lions shift from off-shore, pelagic prey to coastal, benthic prey after parturition in order to reduce the foraging trip duration and hence the time pups remain unattended on the beach during early lactation. The δ13C and δ15N values of the serum and blood cells of 26 South American sea lion suckling pups from northern Patagonia were used to track the dietary changes of their mothers from late pregnancy to early lactation, after correction for differential isotopic fractionation between tissues. Primary producers and potential prey species were also analysed to establish a baseline for interpreting the stable isotope concentration of serum and blood cells. Isotopic ratios revealed a generalized increase in the consumption of coastal-benthic prey after parturition. Such a generalized post-partum shift will allow females to spend more time on land and look after their pups. The effects of this foraging strategy on the nutritional quality of the female"s diet are discussed.

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Se estudia la variabilidad de los caracteres utilizados tradicionalmente en la taxonomía de los afínes Verbascum blattaria L. y V. virgatum Stokes, sobre la base de materiales procedentes de la Península Ibérica. El estudio comparado de ambas entidades ha comportado la creación de un nuevo taxon: V. virgatum Stokes subsp. dertosense Benedí and Rovira, restringido por ahora a las montañas tarraconenses de los Ports de Beseit (Horta de Sant Joan, Tarragona).

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First genome size estimations for some eudicot families and genera.- Genome size diversity in angiosperms varies roughly 2400-fold, although approximately 45% of angiosperm families lack a single genome size estimation, and therefore, this range could be enlarged. To contribute completing family and genera representation, DNA C-Values are here provided for 19 species from 16 eudicot families, including first values for 6 families, 14 genera and 17 species. The sample of species studied is very diverse, including herbs, weeds, vines, shrubs and trees. Data are discussed regarding previous genome size estimates of closely related species or genera, if any, their chromosome number, growth form or invasive behaviour. The present research contributes approximately 1.5% new values for previously unreported angiosperm families, being the current coverage around 55% of angiosperm families, according to the Plant DNA C-Values Database.

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This paper describes petrologic and morphologic characteristics of fossil beaches submerged in the sector of the Costa Brava located between the Pals Beach and Blanes (Girona). These submerged beaches are composed of large-grain sandstone andconglomerate platforms, situated at a depth between 0.5 and 2.5 meters. These platforms are slightly inclinated towards the open sea. These deposits have been formed very recently, and date from Holocene, as noted by the presence of fragments of roman ceramics inside sandstone

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Durante el mes de febrero de 1638 se celebraron en el palacio del Buen Retiro las fiestas de carnestolendas. Entre las actividades programadas, se realizó una academia literaria en la que participaron poetas y cortesanos. De ella se conservan tres vejámenes: el de Alfonso de Batres, el de Antonio Coello y el de Francisco de Rojas Zorrilla. En el presente artículo se analiza y edita críticamente el vejamen que Batres defendió ante sus majestades en el Salón Real del Retiro el 11 de febrero de 1638.

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Nota sobre les conseqüències de la invasió del mol·lusc d'aigua dolça, Anodonta woodiana, a la Península Ibèrica

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Rural depopulation and abandonment of farming activities have resulted in an intense transformation of the characteristic landscapes of Mediterranean mountains. A dynamic characterized by an intense process of expansion of forested cover in detriment to livestock and agricultural areas. This process, which produces effects such as biodiversity and cultural heritage loss and contributes to the spread of wildfires, can be mapped, quantified and described with high accuracy through the means of digital mapping, geographic information systems and landscape indexes. But what is the perception and valuation of these changes by the stakeholders involved in the management of these territories? This article attempts to answer this question in the protected area of Alta Garrotxa (Girona), where a strong correlation between landscape dynamics and their perception by the stakeholders is revealed. On the other hand, the valuation and future prospects produce diverse and often contradictory points of views that illustrate the existing difficulties to management