956 resultados para Program performance
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Controlled nanozeolite deposits are prepared by electrochemical techniques on a macroporous carbon support and binderless thin film electrodes of zeolite-templated carbon are synthesized using the deposits as templates. The obtained film electrodes exhibit extremely high area capacitance (10–12 mF cm−2) and ultrahigh rate capability in a thin film capacitor.
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Composite materials made of porous SiO2 matrices filled with single-walled carbon nanotubes (SWCNTs) were deposited on electrodes by an electroassisted deposition method. The synthesized materials were characterized by several techniques, showing that porous silica prevents the aggregation of SWCNT on the electrodes, as could be observed by transmission electron microscopy and Raman spectroscopy. Different redox probes were employed to test their electrochemical sensing properties. The silica layer allows the permeation of the redox probes to the electrode surface and improves the electrochemical reversibility indicating an electrocatalytic effect by the incorporation of dispersed SWCNT into the silica films.
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Improvement of the features of an enzyme is in many instances a pre-requisite for the industrial implementation of these exceedingly interesting biocatalysts. To reach this goal, the researcher may utilize different tools. For example, amination of the enzyme surface produces an alteration of the isoelectric point of the protein along with its chemical reactivity (primary amino groups are the most widely used to obtain the reaction of the enzyme with surfaces, chemical modifiers, etc.) and even its “in vivo” behavior. This review will show some examples of chemical (mainly modifying the carboxylic groups using the carbodiimide route), physical (using polycationic polymers like polyethyleneimine) and genetic amination of the enzyme surface. Special emphasis will be put on cases where the amination is performed to improve subsequent protein modifications. Thus, amination has been used to increase the intensity of the enzyme/support multipoint covalent attachment, to improve the interaction with cation exchanger supports or polymers, or to promote the formation of crosslinkings (both intra-molecular and in the production of crosslinked enzyme aggregates). In other cases, amination has been used to directly modulate the enzyme properties (both in immobilized or free form). Amination of the enzyme surface may also pursue other goals not related to biocatalysis. For example, it has been used to improve the raising of antibodies against different compounds (both increasing the number of haptamers per enzyme and the immunogenicity of the composite) or the ability to penetrate cell membranes. Thus, amination may be a very powerful tool to improve the use of enzymes and proteins in many different areas and a great expansion of its usage may be expected in the near future.
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The electroassisted encapsulation of Single-Walled Carbon Nanotubes was performed into silica matrices (SWCNT@SiO2). This material was used as the host for the potentiostatic growth of polyaniline (PANI) to yield a hybrid nanocomposite electrode, which was then characterized by both electrochemical and imaging techniques. The electrochemical properties of the SWCNT@SiO2-PANI composite material were tested against inorganic (Fe3+/Fe2+) and organic (dopamine) redox probes. It was observed that the electron transfer constants for the electrochemical reactions increased significantly when a dispersion of either SWCNT or PANI was carried out inside of the SiO2 matrix. However, the best results were obtained when polyaniline was grown through the pores of the SWCNT@SiO2 material. The enhanced reversibility of the redox reactions was ascribed to the synergy between the two electrocatalytic components (SWCNTs and PANI) of the composite material.
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But: La perte unilatérale du cortex visuel postérieur engendre une cécité corticale controlatérale à la lésion, qu’on appelle hémianopsie homonyme (HH). Celle-ci est notamment accompagnée de problèmes d’exploration visuelle dans l’hémichamp aveugle dus à des stratégies oculaires déficitaires, qui ont été la cible des thérapies de compensation. Or, cette perte de vision peut s’accompagner d’une perception visuelle inconsciente, appelée blindsight. Notre hypothèse propose que le blindsight soit médié par la voie rétino-colliculaire extrastriée, recrutant le colliculus supérieur (CS), une structure multisensorielle. Notre programme a pour objectif d’évaluer l’impact d’un entraînement multisensoriel (audiovisuel) sur la performance visuelle inconsciente des personnes hémianopsiques et les stratégies oculaires. Nous essayons, ainsi, de démontrer l’implication du CS dans le phénomène de blindsight et la pertinence de la technique de compensation multisensorielle comme thérapie de réadaptation. Méthode: Notre participante, ML, atteinte d’une HH droite a effectué un entraînement d’intégration audiovisuel pour une période de 10 jours. Nous avons évalué la performance visuelle en localisation et en détection ainsi que les stratégies oculaires selon trois comparaisons principales : (1) entre l’hémichamp normal et l’hémichamp aveugle; (2) entre la condition visuelle et les conditions audiovisuelles; (3) entre les sessions de pré-entraînement, post-entraînement et 3 mois post-entraînement. Résultats: Nous avons démontré que (1) les caractéristiques des saccades et des fixations sont déficitaires dans l’hémichamp aveugle; (2) les stratégies saccadiques diffèrent selon les excentricités et les conditions de stimulations; (3) une adaptation saccadique à long terme est possible dans l’hémichamp aveugle si l’on considère le bon cadre de référence; (4) l’amélioration des mouvements oculaires est liée au blindsight. Conclusion(s): L’entraînement multisensoriel conduit à une amélioration de la performance visuelle pour des cibles non perçues, tant en localisation qu’en détection, ce qui est possiblement induit par le développement de la performance oculomotrice.
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L’acceptabilité d’un décès lors d’une simulation médicale reste débattue mais il existe peu de données sur la perspective des apprenants. Des médecins résidents ont effectué une pratique de code et ont rempli un questionnaire pré et post-simulation. Ils ont été exposés à deux scénarios où un bébé naissait sans signe de vie: 1. Nouveau-né ne répondant pas aux manœuvres de réanimation (DCD); 2. Nouveau-né s’améliorant avec une réanimation adéquate (REA). Les performances étaient évaluées à l’aide de la grille standardisée du Programme de Réanimation Néonatale. Le stress objectif (cortisol salivaire) et subjectif a été mesuré après le code. La rétroaction («feedback»), individuelle et en groupe, fut analysée à l’aide de méthodologies qualitatives. 59/62 apprenants ont répondu au questionnaire et 42 ont participé à la simulation. Tous les résidents trouvent les simulations bénéfiques et souhaitent y être exposés davantage. Le type et l’ordre des scénarios n’ont pas eu d’impact sur la performance. Un seul résident a interrompu les manœuvres de réanimation après 10 minutes d’asystolie, tel que recommandé, et 31% ont poursuivi après 20 minutes. Les participants trouvaient le scénario DCD plus stressant. Les niveaux de cortisol salivaire ont augmenté après les simulations (p<0.001) et ce, pour les deux scénarios. Cette augmentation était indépendante du scénario (p=0.06) et n’était pas associée à la performance. Les réponses à la question « Comment a été votre expérience? », ont permis d’identifier deux thèmes: 1. Le mannequin ne meurt pas en simulation médicale; 2. Le décès lors de la simulation signifie une réanimation inadéquate. Le décès lors d’une pratique de code est stressant, mais n’interfère pas avec la performance des soignants. Les apprenants trouvent cet exercice acceptable et bénéfique à leur pratique future.
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The use of recycled materials in asphalt mixtures such as reclaimed asphalt pavements (RAP) have become widely accepted as a replacement for virgin asphalt binder or virgin aggregates. In this study, the RAP content was 30%, and CR additives were blended with the soft unmodified binder by using dry processes. The objective of this study was to investigate and evaluate the engineering properties of dry method application of crumb rubber influences on reclaimed asphalt pavement (RAP) mixtures. To evaluate the effect of rubber-bitumen interaction on the mixture’s mechanical properties, a laboratory investigation has been conducted on a range of dense graded and 30% RAP by dry process crumb rubber modified (CRM) asphalt mixtures containing 0% (control), 1% crumb rubber by the total aggregate mass. The experimental program in this research include the binder extraction for estimating the amount of aged binder in the both fine and coarse RAP material. Before extracting the binder the RAP sieve analysis, have been done to provide the Black grading curve. In continue after the binder extraction the material sieved again to providing the white curve. The comparison of Black and White curve indicated that there is a remarkable difference between the aggregate grading even for the fine RAP. The experimental program was continued by fabricating 12 specimens in different 4 types of mixtures. For the first group no RAP, no rejuvenator and no crumb rubber were used. For the second group 30% of virgin aggregates substituted by RAP material and the third group was similar to the second group just with 0.01% rejuvenator. the forth group was the group, which in that the specimens contain RAP, rejuvenator and crumb rubber. Finally the specimens were tested for Indirect tensile strength. The results indicated that the addition of crumb rubber increased the optimum amount of binder in the mixture with 30% RAP.
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In contrast to the remarkable progress in developing countries in improving primary education, access to higher education in many countries remains limited, especially in rural areas where the quality of education is inadequate. We evaluate a DVD-based distance-learning program in rural Bangladesh, targeted at students aiming to take university entrance tests. We conducted two experiments: one to evaluate the effect of the distance-learning program and the second to determine the demand and price sensitivity. Our first experiment shows that the DVD-based distance-learning program has a considerable positive effect on the number of students passing entrance exams. This effect does not depend on cognitive scores, but does depend on non-cognitive attributes, indicating the importance of commitment, which is imposed through our program. In the second experiment, we offered a random subsidy to interested participants. The uptake decision is price-sensitive, although the price sensitivity is not correlated with students' past academic performance or their socio-economic status, suggesting that increasing the price should not disproportionately exclude poor students.
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National Highway Traffic Safety Administration, Washington, D.C.
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National Highway Traffic Safety Administration, Washington, D.C.
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National Highway Traffic Safety Administration, Washington, D.C.
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Mode of access: Internet.
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Mode of access: Internet.
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Transportation Department, Washington, D.C.
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National Highway Traffic Safety Administration, Washington, D.C.