213 research outputs found

    Fisheries Production of the Gulf of Mexico

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    Simulating fisheries for the assessment of optimum harvesting strategies

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    Some results of a line of research explored by the author in recent years, and concerning the small-scale fisheries of Mexico are discussed. Clarity of goals for fisheries management is stressed as a departure point before taking any step towards model building. Age-structured simulation models require input data and parameters such as growth rates, natural mortality, age at first capture and maturity, longevity, the longest possible catch records series, and estimates of numbers caught per age group. The link between each cohort and the following can then be established by means of the Ricker stock recruitment or the Beverton-Holt models. Simulation experiments can then be carried out by changing fishing mortality. Whenever data on profits and costs and catch are available, these can also be analyzed. The use of simulation models is examined with emphasis on the benefits derived from their use for fisheries management

    Small Angle X-ray Scattering analysis of porous powders of CaCO3

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    Academic language socialisation in high school writing conferences

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    This study examines multilingual high school writers’ individual talk with their teachers in two advanced English language development classes to observe how such talk shapes linguistically diverse adolescents’ writing. Addressing adolescent writers’ language socialization through microethnographic discourse analysis, the author argues that teachers’ oral responses during writing conferences can either scaffold or deter students’ socialization into valued ways of using academic language for school writing. She suggests what forms of oral response provide scaffolding and what forms might limit multilingual adolescent learners’ academic literacy. Constructive interactions engaged students in dialogue about their writing, and students included content or phrasing from the interaction in their texts. Unhelpful interactions failed to foster students’ language development in observable ways. Although teachers attempted to scaffold ideas and language, they often did not guide students’ discovery of appropriate forms or points. These interactions represent restrictive academic language socialization: while some students did create academic texts, they learned little about academic language use

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
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