954 resultados para Exposição físico-natural


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The objective of the present study was to determine the most suitable extender and their respective dilution ratios for African catfish sperm for artificial induced breeding and cryopreservation purposes. Three natural extenders were tested i.e. coconut water, sugarcane water and soybean solutions, at three different levels of sperm to extender dilutions of 1:20, 1:30 and 1:40. While Ringer solution was used as a control Diluted sperm were fertilized with ready isolated eggs to assess the fertility and hatching rate at 0, 6 and 12 hour intervals. The results showed that the eggs hatched approximately 19 to 27 hours after fertilization. In general, the fertilization and hatching rates decreased with increasing dilution ratio. With respect to natural extenders, the coconut water showed the highest fertility and hatching rates at 1:20 dilution ratio. Therefore, coconut water at 1:20 dilution ratio was the optimal condition for African catfish spermatozoa among the natural extenders investigated.

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El objetivo de este proyecto es la simulación de la Flota P del fabricante CAF comprado recientemente por la compañía Metro Sao Paulo. Esta flota forma parte de un proyecto con cuatro trenes más que LANDER había desarrollado anteriormente y deja la posibilidad de añadir más trenes en el futuro, si la compañía quisiera incorporarlos al simulador. La simulación es una herramienta segura y rentable que permite entrenar situaciones catastróficas en un entorno virtual que no se pueden reproducir en la realidad y, además, evita gastos de electricidad y de desgaste de materiales, tanto del material rodante como de la infraestructura porque la que se mueve el tren. Por otra parte, para el entrenamiento de maquinistas en trenes reales se emplean las horas nocturnas ya que durante el día las vías están ocupadas por trenes que deben cumplir horarios de las líneas; por tanto, un simulador ofrece una amplia disponibilidad para el entrenamiento. Sin embargo, los simuladores no sólo se emplean con futuros maquinistas sino con maquinistas veteranos para evitar que aquellos que nunca han tenido ningún contratiempo, actúen de forma relajada, despreocupada o, incluso inconsciente. Además, el simulador les permite ejercitar situaciones que exijan reacciones rápidas, como objetos en la vía o averías, de este modo entrenan protocolos de actuación para normalizar en lo posible el servicio de la línea.

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Proyecto desarrollado en castellano. Trata sobre los efectos de la actividad física en la prevención del cáncer de colon y cómo su práctica puede reducir el riesgo de padecerlo.

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Dados los beneficios que el ejercicio físico aporta sobre la salud de las personas, varios estudios han demostrado la efectividad de éste para la reducción del riesgo cardiovascular, problema principal de las personas que pese a tener normopeso, son fumadoras y sedentarias. OBJETIVO: Comprobar la efectividad del ejercicio físico aeróbico y de fuerza en la mejora de la calidad de vida, composición corporal, capacidad cardiovascular y reducción de los factores de riesgo y edad vascular en una persona con normopeso, fumadora y sedentaria, así como habituar a la persona a la práctica de ejercicio físico y adquisición de un estilo de vida más saludable.

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Unremitting waves and occasional storms bring dynamic forces to bear on the coast. Sediment flux results in various patterns of erosion and accretion, with an overwhelming majority (80 to 90 percent) of coastline in the eastern U.S. exhibiting net erosion in recent decades. Climate change threatens to increase the intensity of storms and raise sea level 18 to 59 centimeters over the next century. Following a lengthy tradition of economic models for natural resource management, this paper provides a dynamic optimization model for managing coastal erosion and explores the types of data necessary to employ the model for normative policy analysis. The model conceptualizes benefits of beach and dune sediments as service flows accruing to nearby residential property owners, local businesses, recreational beach users, and perhaps others. Benefits can also include improvements in habitat for beach- and dune-dependent plant and animal species. The costs of maintaining beach sediment in the presence of coastal erosion include expenditures on dredging, pumping, and placing sand on the beach to maintain width and height. Other costs can include negative impacts on the nearshore environment. Employing these constructs, an optimal control model is specified that provides a framework for identifying the conditions under which beach replenishment enhances economic welfare and an optimal schedule for replenishment can be derived under a constant sea level and erosion rate (short term) as well as an increasing sea level and erosion rate (long term). Under some simplifying assumptions, the conceptual framework can examine the time horizon of management responses under sea level rise, identifying the timing of shift to passive management (shoreline retreat) and exploring factors that influence this potential shift. (PDF contains 4 pages)

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En este trabajo se dercriben cuales son los efectos del paso del tiempo en el cuerpo humano y como se pueden disminuir o eliminar estos efectos a través de la actividad fisica.

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Terpenes represent about half of known natural products, with terpene synthases catalyzing reactions to increase the complexity of substrates and generate cyclizations of the linear diphosphate substrates, therefore forming rings and stereocenters. With their diverse functionality, terpene synthases may be highly evolvable, with the ability to accept a wide range of non-natural compounds and with high product selectivity. Our hypothesis is that directed evolution of terpene synthases can be used to increase selectivity of the synthase on a specific substrate. In the first part of the work presented herein, three natural terpene synthases, Cop2, BcBOT2, and SSCG_02150, were tested for activity against the natural substrate and a non-natural substrate, called Surrogate 1, and the relative activities on both the natural and non-natural substrates were compared. In the second part of this work, a terpene synthase variant of BcBOT2 that has been evolved for thermostability, was used for directed evolution for increased activity and selectivity on the non-natural substrate referred to as Surrogate 2. Mutations for this evolution were introduced using random mutagenesis, with error prone polymerase chain reactions, and using site-specific saturation mutagenesis, in which an NNK library is designed with a specific active site amino acid targeted for mutation. The mutant enzymes were then screened and selected for enhancement of the desired functionality. Two neutral mutants, 19B7 W367F and 19B7 W118Q, were found to maintain activity on Surrogate 2, as measured by the screen.

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89 ripe female brooders of the catfish, Clarias anguillaris (Body wt. Range 150g-1, 200g) were induced to spawn by hormone (Ovaprim) induced natural spawning technique over a period of 10 weeks. Matching ripe males were used for pairing the females at the ratio of two males to a female. Six ranges of brood stock body weights were considered as follows; <200g; 200g-399g; 400g-599g; 600-799g; 800g-999g; > 1000g and the number of fry produced by each female brooder was scored/recorded against the corresponding body weight range. The number of fry per unit quantity of hormone and the cost of production a fry based on the current price of Ovaprim (hormon) were determined so as to ascertain most economic size range. The best and most economic size range was between 400g-599g body weight with about 20,000 fry per ml of hormone and N0.028 per fry, while the females above 1000g gave the poorest results of 9,519 fry per ml of hormone and N0.059 per fry. For optimum production of Clarias anguillaris fry and maximum return on investment female brooders of body weights ranging between 400g-599g are recommended for hormone induced natural breeding exercises