943 resultados para Languages for Specific Purposes


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Arrhenius law implicates that only those molecules which possess the internal energy greater than the activation energy E-a can react. However, the internal energy will not be proportional to the gas temperature if the specific heat ratio gamma and the gas constant R vary during chemical reaction processes. The varying gamma may affect significantly the chemical reaction rate calculated with the Arrhenius law under the constant gamma assumption, which has been widely accepted in detonation and combustion simulations for many years. In this paper, the roles of variable gamma and R in Arrhenius law applications are reconsidered, and their effects on the chemical reaction rate are demonstrated by simulating one-dimensional C-J and two-dimensional cellular detonations. A new overall one-step detonation model with variable gamma and R is proposed to improve the Arrhenius law. Numerical experiments demonstrate that this improved Arrhenius law works well in predicting detonation phenomena with the numerical results being in good agreement with experimental data.

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Resumen: Este ensayo establece una territorialización de los lenguajes teatrales alternativos como zona específica de la cultura urbana, y los historiza en la tradición de la escena independiente argentina. Analiza el contexto específico de la crisis financiera que eclosionó en 2001 y la producción más reciente, dando cuenta de un periodo tan conflictivo en lo económico como prolífico en lo teatral. Se describen las actividades de gestión y producción escénicas, que incluyen la búsqueda de espacios, subsidios y respaldo institucional, y la implementación de estrategias de difusión y explotación. Estas labores específicas son desarrolladas de manera particular por numerosos teatristas argentinos de entre 30 y 40 años, ya legitimados, incluso a nivel internacional. Estos dramaturgos-actores-directores co-construyen representaciones sociales compartidas, y manifiestan diferentes modalidades estratégicas asociativas, tales como la rotación de roles y el trabajo en colaboración.

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The concept ''sample-specific'' is suggested to describe the behavior of disordered media close to macroscopic failure. it is pointed out that the transition from universal scaling to sample-specific behavior may be a common phenomenon in failure models of disordered media. The dynamical evolution plays an important role in the transition.

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[EN]This paper undertakes the study of the occurrence of non-corresponding demonstrative forms in Spanish, Basque and English in exactly the same linguistic context. It is proposed that the differenccs in the choice of the demonstratives result from the differences in the kind of iniormation that must be coded in each of the languages. Thus, I will argue that in Spanish and Basque the obligatory coding of the aspectual categories of the imperfect and the preterit has the function of imposing specific viewing arrangements onto the situations they designate. By contrast, in English, where the aspectual distinction is not overtly coded, the demonstrativcs are proposed to fulfil this function.

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[ES] Este artículo trata sobre el proceso fonológico que en euskera convierte en africadas las fricativas sibilantes tras consonante sonante. El análisis de dicho proceso es particularmente adecuado para la discusión de la relación recíproca entre fonética y fonología tal y defendida por la Fonología Natural. Es ese marco teórico, este trabajo estudia la motivación fonética de la fonología; por otro lado, explora las consecuencias perceptivas –tal vez también productivas– de los distintos inventarios fonémicos de cada lengua, comparando el proceso de africación vasco con el más conocido proceso inglés de inserción oclusiva. Se argumenta que la opción terminológica africación vs. inserción podría no ser una cuestión trivial sino el reflejo de alguna diferencia en el procesamiento fonológico de condiciones fonéticas básicamente equivalentes. La optimización de la estructura silábica se presenta como otro posible elemento de la configuración del proceso y como factor que contribuye a la mayor o menor relevancia de éste en lenguas tipológicamente distintas. Se ofrecen en la sección 3 algunos comentarios sobre imágenes espectrográficas como muestra de las observaciones que dieron lugar al trabajo de investigación en curso.

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The identification of sea bass (Centropristis) larvae to species is difficult because of similar morphological characters, spawning times, and overlapping species ranges. Black sea bass (Centropristis striata) is an important fishery species and is currently considered to be overfished south of Cape Hatteras, North Carolina. We describe methods for identifying three species of sea bass larvae using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) assays based on species-specific amplification of rDNA internal transcribed spacer regions. The assays were tested against DNA of ten other co-occurring reef fish species to ensure the assay's specificity. Centropristis larvae were collected on three cruises during cross-shelf transects and were used to validate the assays. Seventy-six Centropristis larva were assayed and 69 (91%) were identified successfully. DNA was not amplified from 5% of the larvae and identification was inconclusive for 3% of the larvae. Those assays can be used to identify sea bass eggs and larvae and will help to assess spawning locations, spawning times, and larval dispersal.

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Lionfish (Pterois volitans/miles complex) are venomous coral reef fishes from the Indian and western Pacific oceans that are now found in the western Atlantic Ocean. Adult lionfish have been observed from Miami, Florida to Cape Hatteras, North Carolina, and juvenile lionfish have been observed off North Carolina, New York, and Bermuda. The large number of adults observed and the occurrence of juveniles indicate that lionfish are established and reproducing along the southeast United States coast. Introductions of marine species occur in many ways. Ballast water discharge, a very common method of introduction for marine invertebrates, is responsible for many freshwater fish introductions. In contrast, most marine fish introductions result from intentional stocking for fishery purposes. Lionfish, however, likely were introduced via unintentional or intentional aquarium releases, and the introduction of lionfish into United States waters should lead to an assessment of the threat posed by the aquarium trade as a vector for fish introductions. Currently, no management actions are being taken to limit the effect of lionfish on the southeast United States continental shelf ecosystem. Further, only limited funds have been made available for research. Nevertheless, the extent of the introduction has been documented and a forecast of the maximum potential spread of lionfish is being developed. Under a scenario of no management actions and limited research, three predictions are made: ● With no action, the lionfish population will continue to grow along the southeast United States shelf. ● Effects on the marine ecosystem of the southeast United States will become more noticeable as the lionfish population grows. ● There will be incidents of lionfish envenomations of divers and/or fishers along the east coast of the United States. Removing lionfish from the southeast United States continental shelf ecosystem would be expensive and likely impossible. A bounty could be established that would encourage the removal of fish and provide specimens for research. However, the bounty would need to be lower than the price of fish in the aquarium trade (~$25-$50 each) to ensure that captured specimens were from the wild. Such a low bounty may not provide enough incentive for capturing lionfish in the wild. Further, such action would only increase the interaction between the public and lionfish, increasing the risk of lionfish envenomations. As the introduction of lionfish is very likely irreversible, future actions should focus on five areas. 1) The population of lionfish should be tracked. 2) Research should be conducted so that scientists can make better predictions regarding the status of the invasion and the effects on native species, ecosystem function, and ecosystem services. 3) Outreach and education efforts must be increased, both specifically toward lionfish and more generally toward the aquarium trade as a method of fish introductions. 4) Additional regulation should be considered to reduce the frequency of marine fish introduction into U.S. waters. However, the issue is more complicated than simply limiting the import of non-native species, and these complexities need to be considered simultaneously. 5) Health care providers along the east coast of the United States need to be notified that a venomous fish is now resident along the southeast United States. The introduction and spread of lionfish illustrates the difficulty inherent in managing introduced species in marine systems. Introduced species often spread via natural mechanisms after the initial introduction. Efforts to control the introduction of marine fish will fail if managers do not consider the natural dispersal of a species following an introduction. Thus, management strategies limiting marine fish introductions need to be applied over the scale of natural ecological dispersal to be effective, pointing to the need for a regional management approach defined by natural processes not by political boundaries. The introduction and success of lionfish along the east coast should change the long-held perception that marine fish invasions are a minimal threat to marine ecosystems. Research is needed to determine the effects of specific invasive fish species in specific ecosystems. More broadly, a cohesive plan is needed to manage, mitigate and minimize the effects of marine invasive fish species on ecosystems that are already compromised by other human activities. Presently, the magnitude of marine fish introductions as a stressor on marine ecosystems cannot be quantified, but can no longer be dismissed as negligible. (PDF contains 31 pages)

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Eguíluz, Federico; Merino, Raquel; Olsen, Vickie; Pajares, Eterio; Santamaría, José Miguel (eds.)

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A literature review was conducted to locate information on the flow of energy from primary producers to the fishery stocks of the Puerto Rican-Virgin Islands insular shelf. This report uses site-specific information to describe the major ecological subsystems, or habitats, of the region, to identify the more common species and the subsystems in which they occur, to quantify productivity and biomass, and to outline trophic relationships. Discussions on each topic and subsystem vary in substance and detail, being limited by the availability and accessibility of information. (PDF contains 189 pages) Seven distinct subsystems are described: mangrove estuary, seagrass bed, coral reef, algal plain, sand/mud bottom, shelf break, and overlying pelagic. Over 50 tables provide lists of species found in each habitat on various surveys dating back to 1956. Estimates of density, relative abundance, and productivity are provided when possible. We evaluated whether sufficient information exists to support an analysis of the energy basis of fishery production in the area, beginning with the design and development of an ecosystem model. Data needs in three categories - species lists, biomass, and trophic relations - were examined for each subsystem and for each of three species groups - primary producers, invertebrates, and fish. We concluded that adequate data, sufficient for modeling purposes, are available in 16 (25%) of 64 categories; limited data, those requiring greater extrapolation, are available in 35 (55%) categories; and no data are available in 13 (20%) categories. The best-studied subsystems are seagrass beds and coral reefs, with at least limited data in all categories. Invertebrates, the intermediate link in the food web between primary producers and fishes, are the least quantified group in the region. Primary production and fishes, however, are relatively well-studied, providing sufficient data to support an ecosystem-level analysis and to initiate a modeling effort.