981 resultados para 612.238


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A partir del análisis del perfil del ingeniero en la sociedad europea, se ha elaborado una encuesta amplia mediante la que se solicitó a las empresas del entorno las competencias y materias que consideraban más importantes en la formación de los ingenieros de las titulaciones ofertadas en la Escuela. A partir de los resultados de dichas encuestas, se establece un perfil requerido a los titulados.

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The paper presents: 1) biologic summaries for each of the formations for which paleontologic data are available, with brief discussions of the geologic age; 2) geologic correlations of the formations and the distribution of their age-equivalents in Central America, the West Indies, and the southeastern United States; 3) an outline of the paleogeography of middle America. The biologic summaries are based on the paleontologic memoirs in this vol. by Messars. Howe, Berry, Chuchman, Jackson, Canu and Bassler and Pilsbry, Miss Rathbun and myself.

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目录

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Bi-weekly phytoplankton samples were collected at 0, 10, and 20 m and enumerated by the Utermöhl sedimentation technique; 14C productivity measurements at 10 m, oblique zooplankton tows, and routine hydrographic observations were also made. Northerly winds induce upwelling during December-April, followed by a rainy season; a slight resurgence in upwelling may occur during July and/or August. Annual variations in upwelling intensity and rainfall occur. During upwelling, the upper 50 m, about 30 per cent of the total volume of the Gulf of Panama, is replaced with water 5 to 10 C colder than the more stratified, turbid and nutrient impoverished watermass present during the rainy season. The mean annual runoff accompanying an average annual precipitation of 2731 mm is estimated to equal a layer of fresh water 3.2 m thick. About 10 per cent of the phytoplankton phosphate and inorganic nitrogen requirements during the rainy season are accreted. (PDF contains 260 pages.)

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Radioactivity measured in samples from the NEA-Dumping-Site not only emanated from dumped barrels. Just as everywhere on the world also fallout from former nuclear weapon tests can be found there. Radionuclides which can emanate from different sources do not tell anything about their origin. To assess the fractions from various sources activity ratios from radionuclides can be used. There are different activity ratios for fallout and for waste from peaceful nuclear power engeneering. The comparison of the ratios of the plutonium isotopes Pu-238 and the sum of Pu-239 and Pu-240 (Pu-238/Pu-239,240) in benthic samples from the dumping site and from reference sites without waste dumping gives a clear hint. In the sampling period from 1980 to 2000 for samples from the dumping site this ratio increases significantly from 1986 on. Radioactivity emanating from the dumped barrels is regarded as causing this.

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The Nigerian pelagic fishery contributes about two-thirds of the total marine fishery resources of the country. The main components of this fishery are the clupeid (Ethmalosa, and Sardinella spp) and the scombroid (jacks, barracuda and tuna) fisheries. In 1979 to 1983, fish production from the national inshore and brackishwater zones was 1,702,685 tonnes. Bonga (Ethmalosa fimbriata) which dominates the pelagic fishery in the Cross River State of Nigeria, contributed about 158,612 tonnes (i.e. 9.3%) of this national marine fish catch. Although bonga is caught along the entire Nigerian coast, a significant fishery exists mostly in the wider estuary of the Cross River State, which borders on the Cameroon Republic. In the Cross River State, and within the period, bonga contributed 24% to the marine fish landings. Bonga is supported by a single species (E. fimbriata). The species forms an important fishery all the year-round in the open sea off these estuaries, whenever the canoes venture to sea, but these open sea fisheries are affected by whether conditions. The best, and most suitable gear for bonga are the gill nets, cast nets, boat seines, and shore seines. Dried and smoked bonga are a common market commodity in the southern parts of the country generally, but particularly in the Cross State where it is a readily available and acceptable food item

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Distribution of the genus Anodontites (Mollusca: Bivalvia: Mycetopodidae) in Uruguay. Seven species of the freshwater mussel genus Anodontites were recorded from Uruguay. The populations of these bivalves suffer the negative effects of invasive bivalves, damming, industrial and urban discharges, and agrotoxic runoff. The distribution of these species is generally characterized at the level of basin or politic divisions, and precise geographic records are scarce. In order to detail the distribution of those species, the most representative collections of Uruguay were examined, the material of Anodontites was identified (612 records) and geographic coordenates were assigned at each locality (213 localities), using Geographic Information System (GIS) to obtain a distribution map for each species. Most of the localities with Anodontites were located in the left margin of Uruguay River and southwest of Uruguay, mainly in Soriano, Artigas, Salto and Colonia departments. The Salto Grande basin presented the highest species richness. The species with a highest number of records was A. patagonicus, which was also recorded in all basins. A. trapesialis and A. tenebricosus had a wide distribution and a high number of records. A. lucidus and A. ferrarisii, had a wide distribution (more than 6 basins) but comparatively lower number of records. Finally A. trapezeus and A. trigonus showed a limited distribution. There is a critical lack of samples in Merín Lagoon, Atlantic and Upper Negro River basins. It is necessary to carry out new sampling considering many variables in order to evaluate the current distribution and the ecologic preferences for each species.

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The identification of artificial radionuclides in fish involves some diffculties, because the quantities of these nuclides are very low (10-16 to 10-10 g/kg). The procedures have to be done very carefully. The sample preparation, the radiochemical analyses and the final preparation of the samples for the detection of the radioactivity of strontium-90, plutonium-238, -239, -240 and americium-241 are briefly described. The levels of artificial radioactivity in some species of fish from the North Sea are shown. The additional exposure to radiation by artificial radionuc1ides by ingestion of fish amounts only to about 0,02 % of the mean exposure to natural radiation. Nevertheless further monitoring of radioactivity should be continued in order to ensure that changes can be detected in time.

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The ordinary differential magnetic field line equations are solved numerically; the tokamak magnetic structure is studied on Hefei Tokamak-7 Upgrade (HT-7U) when the equilibrium field with a monotonic q-profile is perturbed by a helical magnetic field. We find that a single mode (m, n) helical perturbation can cause the formation of islands on rational surfaces with q = m/n and q = (m +/- 1, +/- 2, +/- 3,...)/n due to the toroidicity and plasma shape (i.e. elongation and triangularity), while there are many undestroyed magnetic surfaces called Kolmogorov-Arnold-Moser (KAM) barriers on irrational surfaces. The islands on the same rational surface do not have the same size. When the ratio between the perturbing magnetic field B-r(r) and the toroidal magnetic field amplitude B(phi)0 is large enough, the magnetic island chains on different rational surfaces will overlap and chaotic orbits appear in the overlapping area, and the magnetic field becomes stochastic. It is remarkable that the stochastic layer appears first in the plasma edge region.

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Some aspects of the aquaculture potentials and investment opportunity in shrimps and prawn farming in Nigeria were overviewed. This paper presents the breeding pattern, spawner availability, culture water-type and properties, feeds and feeding regimes and other factors needed in practical shrimps and prawns culture. The culture systems, water management, larval management, stocking density, feeding strategies and diseases were fully discussed. The investment opportunity available as government plans to boost production of these resources from both artisanal and aquaculture sector was documented. Management strategies needed in practical practices of shrimps and prawns culture were enlisted. Effected efforts from the government were listed in this paper