844 research outputs found

    Heat transfer distribution on a discontinuously convective cooled surface

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    An active cooling scheme in which discrete cooling passages are used was investigated. In this scheme, the coolant passages are placed perpendicular to the main stream direction. Streamwise temperature oscillations result from the highly cooled regions, near the coolant channels, being next to regions not directly cooled between the channels. The accuracy of the heat transfer rate predictions by these approximations was evaluated by means of both experimental and numerical investigations. Experiments were conducted at free stream Mach number of 6 with several cooling passages. Heat transfer measurements were made and corresponding theoretical analysis were performed for comparison in evaluating both local and overall deviations in the heat transfer rate

    Estimacion de los riesgos de lixiviation de nitratos en suelos agricolas: Enfoque numerico o analytico ?

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    The environmental problem of nitrate contaminant effects from agricultural sources exists in many rural regions around the world. The use of simulation models could be a way for knowing the risks of different agricultural practices on nitrate leaching. Nowadays, there is a wide variety of models capable of simulating water and solute movement in agricultural soils. The main objective of this work is to compare two models, with different approach for solving the 1D water flux and nitrate movements in soil, in relation to their ability to estimate the risks of nitrate leaching. The first model is STICS with an analytical approach, whereas HYDRUS-1D is chosen for its numerical approach. In order to reach this objective, 15 experimental trials, with different doses and kind of nitrogen fertilizers, were carried out in Baix Empordà (northeast of Spain) agricultural region during spring of 2004. The results show the good correlation between STICS and HYDRUS-1D models. However, HYDRUS-1D predicts amounts of nitrates leached greater that STICS. Considering the results obtained, we establish the first step for accepting the simulations of STICS in order to predict the risks of nitrate leaching on plots with furrow irrigation during all the crop seaso

    MAO: a Multiple Alignment Ontology for nucleic acid and protein sequences

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    The application of high-throughput techniques such as genomics, proteomics or transcriptomics means that vast amounts of heterogeneous data are now available in the public databases. Bioinformatics is responding to the challenge with new integrated management systems for data collection, validation and analysis. Multiple alignments of genomic and protein sequences provide an ideal environment for the integration of this mass of information. In the context of the sequence family, structural and functional data can be evaluated and propagated from known to unknown sequences. However, effective integration is being hindered by syntactic and semantic differences between the different data resources and the alignment techniques employed. One solution to this problem is the development of an ontology that systematically defines the terms used in a specific domain. Ontologies are used to share data from different resources, to automatically analyse information and to represent domain knowledge for non-experts. Here, we present MAO, a new ontology for multiple alignments of nucleic and protein sequences. MAO is designed to improve interoperation and data sharing between different alignment protocols for the construction of a high quality, reliable multiple alignment in order to facilitate knowledge extraction and the presentation of the most pertinent information to the biologist

    Conservation of soil organic carbon, biodiversity and the provision of other ecosystem services along climatic gradients in West Africa

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    Terrestrial carbon resources are major drivers of development in West Africa. The distribution of these resources co-varies with ecosystem type and rainfall along a strong Northeast-Southwest climatic gradient. Soil organic carbon, a strong indicator of soil quality, has been severely depleted in some areas by human activities, which leads to issues of soil erosion and desertification, but this trend can be altered with appropriate management. There is significant potential to enhance existing soil carbon stores in West Africa, with benefits at the global and local scale, for atmospheric CO2 mitigation as well as supporting and provisioning ecosystem services. Three key factors impacting carbon stocks are addressed in this review: climate, biotic factors, and human activities. Climate risks must be considered in a framework of global change, especially in West Africa, where landscape managers have few resources available to adapt to climatic perturbations. Among biotic factors, biodiversity conservation paired with carbon conservation may provide a pathway to sustainable development, and biodiversity conservation is also a global priority with local benefits for ecosystem resilience, biomass productivity, and provisioning services such as foodstuffs. Finally, human management has largely been responsible for reduced carbon stocks, but this trend can be reversed through the implementation of appropriate carbon conservation strategies in the agricultural sector, as shown by multiple studies. Owing to the strong regional climatic gradient, country-level initiatives will need to consider carbon sequestration approaches for multiple ecosystem types. Given the diversity of environments, global policies must be adapted and strategies developed at the national or sub-national levels to improve carbon storage above and belowground. Initiatives of this sort must act locally at farmer scale, and focus on ecosystem services rather than on carbon sequestration solely

    Temperament and attachment as predictive factors for the risk of addiction to substances in adolescents.

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    Abstract: This study aims to relate the dimensions of temperament and attachment with the risk of addiction to substances in a group of 642 adolescents between 13 and 19 years old, and to assess which dimensions of these constructs acted as risk or protective factors. It also relates the two constructs between them. There was a positive correlation between the risk of addiction and the temperament dimension "Novelty seeking" and with those of attachment, "Self-sufficiency and parental resentment" and "Child trauma". The correlation was negative with "Persistence" (temperament) and "Security" (attachment). "Novelty seeking", "Family concern" and age, acted as risk factors; whereas “Security” in attachment was a factor of protection. The temperament and attachment profiles with a higher risk of addiction correlated with each other; they also correlated those with a low risk. Resumen: Temperamento y apego como factores predictivos para el riesgo de adicción a sustancias en adolescentes.Este estudio busca relacionar las dimensiones de temperamento y apego con el riesgo de adicción a sustancias en un grupo de 642 adolescentes de entre 13 y 19 años, y valorar qué dimensiones de estos constructos actúan como factores de riesgo o de protección. También se relacionan los dos constructos entre ellos. Hubo una correlación positiva entre el riesgo de adicción y la dimensión de temperamento “Búsqueda de novedad”, y con las de apego “Autosuficiencia y rencor hacia los padres” y “Trauma infantil”. La correlación fue negativa con “Persistencia” (temperamento) y “Seguridad” (apego). “Búsqueda de la novedad”, “Preocupación familiar” y edad, actuaron como factores de riesgo; mientras que la “Seguridad “en el apego fue un factor de protección. Los perfiles de temperamento y apego con riesgo más elevado de adicción correlacionaron entre ellos; también correlacionaron aquellos con un riesgo bajo.        

    Supporting teachers’ use of data-based instruction to improve students’ early writing skills

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    We examined the effects of a professional development (PD) system designed to support teachers’ use of data-based instruction (DBI) to improve early writing outcomes for children with intensive needs. The PD system, called DBI-TLC, provided tools for early writing assessment and intervention, learning modules including face-to-face workshops followed by classroom application, and ongoing coaching to support DBI implementation. Special education teachers in 19 classrooms in 2 Midwestern districts were assigned randomly to receive DBI-TLC or to a business-as-usual control group. All teachers completed pre- and posttests of DBI knowledge and skills and self-efficacy, and DBI-TLC teachers’ fidelity to DBI was assessed. Fifty-three students (2 to 3 from each classroom) completed pre- and posttests of early writing using curriculum-based measures (CBM) and the Test of Early Written Language-3 (TEWL-3). DBI-TLC teachers outperformed controls at posttest on DBI knowledge and skills (Hedge’s g = 2.88) and reported a more explicit writing instruction orientation compared to controls (g = 1.63). DBI fidelity varied (on average, 84% for assessment, 79% for intervention, and 52% for decision-making). Students whose teachers implemented DBI showed a pattern of stronger early writing performance compared to control students on CBM, with effect sizes of 0.23 to 0.40, but not on the TEWL-3 (0.02 to 0.13). We discuss the promise of DBI-TLC to improve teacher practice and student outcomes, as well as the need to continue to explore ways to support teachers’ implementation of DBI with fidelity. (PsycINFO Database Record (c) 2019 APA, all rights reserved

    Morphometric and microstructural characteristics of hippocampal subfields in mesial temporal lobe epilepsy and their correlates with mnemonic discrimination.

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    Pattern separation (PS) is a fundamental aspect of memory creation that defines the ability to transform similar memory representations into distinct ones, so they do not overlap when storing and retrieving them. Experimental evidence in animal models and the study of other human pathologies have demonstrated the role of the hippocampus in PS, in particular of the dentate gyrus (DG) and CA3. Patients with mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HE) commonly report mnemonic deficits that have been associated with failures in PS. However, the link between these impairments and the integrity of the hippocampal subfields in these patients has not yet been determined. The aim of this work is to explore the association between the ability to perform mnemonic functions and the integrity of hippocampal CA1, CA3, and DG in patients with unilateral MTLE-HE. To reach this goal we evaluated the memory of patients with an improved object mnemonic similarity test. We then analyzed the hippocampal complex structural and microstructural integrity using diffusion weighted imaging. Our results indicate that patients with unilateral MTLE-HE present alterations in both volume and microstructural properties at the level of the hippocampal subfields DG, CA1, CA3, and the subiculum, that sometimes depend on the lateralization of their epileptic focus. However, none of the specific changes was found to be directly related to the performance of the patients in a pattern separation task, which might indicate a contribution of various alterations to the mnemonic deficits or the key contribution of other structures to the function. we established for the first time the alterations in both the volume and the microstructure at the level of the hippocampal subfields in a group of unilateral MTLE patients. We observed that these changes are greater in the DG and CA1 at the macrostructural level, and in CA3 and CA1 in the microstructural level. None of these changes had a direct relation to the performance of the patients in a pattern separation task, which suggests a contribution of various alterations to the loss of function
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