2,458 research outputs found

    String equations in Whitham hierarchies: tau-functions and Virasoro constraints

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    A scheme for solving Whitham hierarchies satisfying a special class of string equations is presented. The tau-function of the corresponding solutions is obtained and the differential expressions of the underlying Virasoro constraints are characterized. Illustrative examples of exact solutions of Whitham hierarchies are derived and applications to conformal maps dynamics are indicated.Comment: 26 pages, 2 figure

    The noni anthraquinone damnacanthal is a multi-kinase inhibitor with potent anti-angiogenic effects

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    Este es el manuscrito que fue aceptado y que finalmente se publicó en Cancer Letters con el DOI: 10.1016/j.canlet.2016.10.037The natural bioactive compound damnacanthal inhibits several tyrosine kinases. Herein, we show that -in fact- damancanthal is a multi kinase inhibitor. A docking and molecular dynamics simulation approach allows getting further insight on the inhibitory effect of damnacanthal on three different kinases: vascular endothelial growth factor receptor-2, c-Met and focal adhesion kinase. Several of the kinases targeted and inhibited by damnacanthal are involved in angiogenesis. Ex vivo and in vivo experiments clearly demonstrate that, indeed, damnacanthal is a very potent inhibitor of angiogenesis. A number of in vitro assays contribute to determine the specific effects of damnacanthal on each of the steps of the angiogenic process, including inhibition of tubulogenesis, endothelial cell proliferation, survival, migration and production of extracellular matrix remodeling enzyme. Taken altogether, these results suggest that damancanthal could have potential interest for the treatment of cancer and other angiogenesisdependent diseases.Supported by grants BIO2014-56092-R (MINECO and FEDER), P12-CTS-1507 (Andalusian Government and FEDER) and funds from group BIO-267 (Andalusian Government). The "CIBER de Enfermedades Raras" is an initiative from the ISCIII (Spain). JAGV had the financial support of Vicerrectorado de Investigación y Transferencia (University of Málaga, Spain). The funders had no role in the study design, data collection and analysis, decision to publish or preparation of the manuscript

    Influence of the fiber direction on the tribological behavior of carbon-fiber reinforced epoxy composites manufactured by prepeg laminates

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    In this work, friction behavior of different carbon fiber-epoxy composites is evaluated. Linear friction tests are carried out and wear behaviour has been established from several parameters as wear depth, wear band width and macrostructural observation. The experimental variables considered were load (10-40N) and the fiber orientation with respect to the sliding direction (0°, 90° and multidirectional). Layers with the fiber oriented in the sliding direction showed larger wear due to cracks existing in the fibermatrix interface once the wear depth reached the fibers. The best results were obtained in those cases in which no influence of the resin matrix existed

    Exercise addiction and satisfaction of fitness center users as precursors to the intention of continuing to engage in physical activity

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    Exercise addiction occurs when a person engages in excessive physical activity until they lose control. Among individuals attending fitness centers, the risk of developing exercise addiction has been estimated to be close to 10%. The objective of this study was to determine whether exercise addiction may be an antecedent of satisfaction with the service received and/or of the intention of continuing to partake in leisure-time physical activity at fitness centers in a direct or indirect manner. A total of 361 individuals (29.05 ± 11.40 years old) who were physically active at Spanish fitness centers were asked to respond to a questionnaire on exercise addiction, satisfaction with the sports service, and their intention to continue to engage in physical activity. A multi-group analysis was conducted to check for differences in relationships by sex. The results show the relationships between addiction, satisfaction, and intention to continue physical activity. The standardized values display differences between men and women, with women exhibiting the highest values for the relationships between addiction and the rest of the constructs. Satisfaction with the sports service is a mediator in the relationship between exercise addiction and intention to engage in leisure-time physical activity

    Evaluación de la resistencia del ácaro Varroa destructor al fluvalinato en colonias de abejas (Apis mellifera) en Yucatán, México

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    The constant application of pyrethroids for controlling the mite Varroa destructor has caused the appearance of populations of resistant mites to this product in several parts of the world. With the purpose of detecting the possible existence of populations of resistant mites to the fluvalinate in the State of Yucatan, one of the main honey producer states in Mexico, 12 samples were gathered from each apiary, selecting four apiaries where fluvalinate was used in constant way for the control of V. destructor during five years, and a similar quantity of samples coming from apiaries where methods of alternative control have been used during a similar time.La constante aplicación de piretroides para el control del ácaro Varroa destructor ha ocasionado la aparición de poblaciones de ácaros resistentes a este producto en diversas partes del mundo. Con la finalidad de detectar la posible existencia de poblaciones de ácaros resistentes al fluvalinato en el estado de Yucatán, uno de los principales estados productores de miel en México, se colectó un total de 12 muestras por cada apiario, seleccionando cuatro apiarios donde se ha utilizado de manera constante el fluvalinato para el control de V. destructor por un periodo de cinco años, y una cantidad de muestras similar provenientes de apiarios donde se han utilizado métodos de control alternativo durante un tiempo similar

    La Iniciativa Mérida: un problema común de seguridad

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    A partir de 2006 la política exterior mexicana tendrá entre sus prioridades combatir los problemas de seguridad vinculados al comercio de drogas ilegales, tráfico de armas y trata de personas, generando un mayor apoyo en recursos materiales y asesoría por parte de los Estados Unidos de América. Como resultado de esta colaboración, se resolvió implementar la Iniciativa Mérida. A pesar de los esfuerzos de México y Estados Unidos para erradicar el comercio de drogas por medio de la ejecución de la Iniciativa Mérida, los resultados no han sido los esperados. Esto se debe a que se han olvidado que la salida no debe limitarse al combate de las organizaciones de traficantes; sino que también necesitan atender necesidades como el deterioro en la calidad de vida de la población, la falta de oportunidades educativas y la insuficiente política de generación de empleo. A la vez, resulta necesaria la cooperación eficaz de los EE.UU. en materia de reducción en la demanda de los consumidores, así como del compromiso real de cortar el flujo de armas que abastece a los cárteles mexicanos; no olvidando que si bien éste es un problema que circula por México, su fin último es fluir fuera de las fronteras, haciendo de la cooperación y el compromiso bilateral una herramienta necesaria para enfrentar la situación. Palabras clave: Iniciativa Mérida, narcotráfico, México-Estados Unidos

    Cambios morfosedimentarios causados por la construcción de un espigón en Camet norte, provincia de Buenos Aires, Argentina

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    Se dan a conocer los diversos cambios morfosedimentarios que se produjeron en un sector de costa ubicado al norte de un espigón construido en Camet Norte (Buenos Aires) a fines del año 2011. Durante el período analizado (julio 2011-diciembre 2015) se observó en un punto de control ubicado a 200 m al norte de la estructura, aguas abajo respecto a la deriva litoral, que el nivel de arena en playa rara vez fue superior al valor registrado en julio de 2011, cuatro meses antes de la construcción de la obra. Lo contrario sucedió con otros tres puntos de control distantes a más de 1.275 m del nuevo espigón, en donde rara vez el nivel de arena fue inferior al observado en esa fecha (julio 2011). A su vez, a lo largo del año la granulometría de la arena correspondiente a la playa frontal del área monitoreada cercana a la obra, por lo general fue más gruesa respecto a los restantes puntos de control, indicando posiblemente una mayor energía de ola en ese sector de costa. El menor nivel de arena asociado a una mayor energía de ola en el sector próximo a la estructura, permitió probablemente la afluencia directa del embate de las mismas durante todo el período, reflejándose esto en un mayor retroceso del acantilado y sobre todo del microacantilado, con un total de 96 y 350 cm (22 y 79 cm/año), respectivamente. Estos retrocesos están asociados preferentemente a eventos de corta duración correspondientes a tormentas marítimas denominadas localmente “sudestadas”.Our study shows several morphodynamic changes occurred along a coastal sector downstream of a groin built at Camet Norte locality (Buenos Aires province) by the end of 2011. During the time span analyzed (July 2011-December 2015), at a control site located 200 m north of the structure, downstream relative to the littoral drift, it was possible to observe that the sand level on the beach was seldom higher than that recorded in July 2011, four months before the groin was built. The opposite occurred in other three control sites placed more than 1,275 m far from the new groin, where the sand level was seldom lower than that observed in July 2011. In addition, along the whole year, the size of the sandy particles of the foreshore in the area localized near the structure was generally higher than that of the remaining control sites, suggesting stronger wave energy within the corresponding coastal sector. Most probably, within control site localized next to groin coastal sector a lower sandy level together with stronger wave energy allowed a direct influx and effect of the waves during the whole time span. This is reflected by a stronger retreat of the main cliff and especially the microcliff, with a total of 96 and 350 cm (22 and 79 cm/year), respectively. These retreats are linked mainly to short marine events locally known as “sudestadas”
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