844 research outputs found

    Estrogen influences cocaine-induced blood oxygen level-dependent signal changes in female rats

    Get PDF
    We investigated the effect of estrogen on cocaine-induced brain activity using blood oxygen level-dependent (BOLD) magnetic resonance imaging. Ovariectomized (Ovx) rats without estrogen and Ovx rats with estrogen (Ovx+E) were given a single saline or cocaine injection (15 mg/kg, i.p.) for 5 d. After 7 d of withdrawal from injections, rats were challenged with cocaine during functional imaging. Acute cocaine administration produced positive BOLD activation in the prefrontal cortex, nucleus accumbens, striatum, ventral tegmental area, and hippocampus, among other brain regions. Positive BOLD signal changes were lower in Ovx+E than in Ovx rats. With repeated cocaine administration, Ovx+E rats showed enhanced BOLD signal changes in the nucleus accumbens, ventral tegmental area, and hippocampus compared with acutely treated animals. Our results indicate that estrogen influences the effects of acute and repeated cocaine administration on BOLD signal changes. The data suggest that in females with estrogen, cocaine-induced neuronal activity is enhanced after repeated cocaine administration. It is possible that the actions of estrogen within the aforementioned brain regions potentiate the behavioral response to cocaine observed in female rats

    Eficacia de finasterida en el tratamiento de la hematuria asociada a la hiperplasia protática benigna

    Get PDF
    La hematuria es una complicación de la hiperplasia benigna de próstata (HBP), tanto en su evolución natural como durante el seguimiento post cirugía prostática. En el estudio de Mebust et al., de 3000 pacientes sometidos a prostactectomía por Hiperplasia prostática benigna (HBP), en el 12 % la presencia de hematuria fue la causa de esta indicación quirúrgica (1). Existen escasas referencias de la acción de la finasterida ante dicho síntoma (2-7), aunque los resultados publicados hasta el momento demuestran un efecto terapéutico precoz y estable mientras dura el tratamient

    An eco-physiological and biotechnological approach to conservation of the world-wide rare and endangered aquatic liverwort Riella helicophylla (Bory et Mont.) Mont.

    Get PDF
    The rare aquatic liverwort Riella helicophylla (Bory et Mont.) Mont., inhabitant of temporary shallow ponds around the Mediterranean basin, is considered threatened throughout its distribution range. In addition, little is known of its biology and ecology or of its role in such an important ecosystem where envi- ronmental conditions vary yearly in unpredictable ways. In these variable habitats, due to the seasonal fluc- tuation of water levels, there is no guarantee of yearly spore input into the spore bank. Spore germination rate and the effects of different culture media in an axenic culture establishment, as well as propagation proce- dures of R. helicophylla, were tested. New insights into the ecology and biology of R. helicophylla are given. Spore dormancy is documented, and the protocols for the in vitro culture establishment, propagation and ac- climatization of this liverwort are developed. Dry storage at 20 ± 2 °C for about three months broke the dor- mancy of spores, which subsequently germinated in a high percentage (over 90%). A two phase (solid and liquid) culture media system was developed for the purpose of achieving fully developed gametophytes. The liquid phase contained electrolytes simulating brackish water

    An immersed boundary method to conjugate heat transfer problems in complex geometries. Application to an automotive antenna

    Get PDF
    Considering that the most common reason for electronic component failure is the excessive temperature level, an efficient thermal management design can prolong the operating life of the equipment, while also increasing its performance. Computational Fluid Dynamics and Heat Transfer (CFD&HT) have proved valuable in the study of these problems, since they can produce reliable fields of fluid flow, temperature and heat fluxes. Moreover, thanks to the recent advances in high-performance computers, CFD&HT numerical simulations are becoming viable tools to study real problems. The conventional approach, which consists of employing body-conformal meshes to the solids and fluids regions, often results costly and ineffective in applications with very complex geometries and large deformation. For these cases, an alternative approach, the Immersed Boundary Method (IBM), which employs a non-body conformal mesh and discretizes the entire domain using a special treatment in the vicinity of the solid-fluid interfaces, has proven more effective. In this work, an IBM was extended to simulate problems with conjugate heat transfer (CHT) boundary conditions taking into account the radiative exchange between surfaces. It was designed to work with any type of mesh (domain discretization) and to handle any body geometry. The implementation was validated and verified by several simulations of benchmark cases. Moreover, the IBM was applied in an industrial application which consists of the simulation of a Smart Antenna Module (SAM). All in all, the carried out studies resulted in a monolithic methodology for the simulation of realistic situations, where all three heat transfer mechanisms can be considered in complex geometries.Peer ReviewedPostprint (author's final draft

    Approach for the analysis of TES technologies aiming towards a circular economy: Case study of building-like cubicles

    Full text link
    The objective of this study is to establish an initial framework to evaluate and improve the sustainability of technologies integrating thermal energy storage to come closer to a circular economy. This is applied to a case study for a building-like cubicle that includes different options of phase change materials. For the construction of a cubicle, materials can come from ores and virgin or recycled feedstock. In order to decrease the impact of materials and approach to a circular economy, the recycled content of materials at the start of life should be as high as possible. This recycled fraction in current supply depends on the available technologies for reintroducing the recycled materials in the production processes, together with virgin materials coming from primary sources. The results of the analysis show that the decrease of the environmental impact of recycling at the end of life is lower than 5%, while using recycled materials replacing virgin raw materials could reduce the overall impact by up to 30%. Most relevant materials are bricks, steel, and aluminum. Thus, reuse and recycling of materials and components must be integrated into the initial design in order to come closer to the concept of circular economy

    Considerations for the use of metal alloys as phase change materials for high temperature applications

    Get PDF
    The use of paraffin, salts and salt hydrates as phase change materials (PCMs) have been researched extensively and used in a number of commercial applications. However, metals and metal alloys, which possess a high storage density on a volume basis as well as a substantially higher thermal conductivity, has received much less attention. This paper discusses the considerations for the use of metal and metal alloys as phase change materials for high temperature thermal storage applications, as well as summarises the literature on the limited research in this area. Although some pure metals and metal alloys present interesting thermal properties to be used as PCMs in thermal storage systems, there is a lack of understanding on the implications of the metallurgical aspects related to the melting and solidification of these materials under thermal cycling at high temperatures. The main issues to be considered include vapour pressure, undercooling, corrosion, segregation, changes in composition and microstructure, changes in thermal properties and undesired reactions. Further research is needed before these materials can be used as PCMs in thermal energy storage systems in industry
    • …
    corecore