182 research outputs found

    Restauración y reciclaje del Centro de Documentación Adolfo López Mateos: Análisis del proceso constructivo y de equipamiento

    Get PDF
    Los centros de documentación son espacios difusores de la información organizada y especializada para usuarios. Sin embargo, tanto la adecuada planeación como la edi cación de estos espacios no cuentan con una normativa especí ca en México. El objetivo de este artículo es analizar las características que deberían cumplir y el proceso constructivo que dio origen al Centro de Documentación Presidente Adolfo López Mateos de la UAEMéx. El texto revisa la literatura especializada en centros de documentación, también considera dos propuestas de restauración y reciclaje de edi cios históricos para detallar el proceso constructivo y de equipamiento de estos recintos documentales. Se concluye que este centro de documentación debería constituir y difundir un fondo documental especializado, no sólo producido por la propia institución, sino también promover la docencia, la investigación y otros servicios documentales. Además, las técnicas de restauración y reciclaje empleadas permitieron el uso e ciente del espacio que actualmente ocupa. De igual manera, se de ende la idea de aplicar estos métodos provenientes de la arquitectura antes de la construcción de espacios nuevos

    Variación estacional de la producción de huevos del copépodo calanoideo Centropages furcatus (Dana, 1852) en la Bahía de La Paz, México

    Get PDF
    The egg production rate (EPR) was estimated for Centropages furcatus in Bahia de La Paz, Baja California Sur, Mexico during 2003. This species is one of the most abundant and frequent copepod in the zone. The highest egg production in carbon estimations for C. furcatus were observed in summer (1.20 ± 0.7 µg C female-1 d-1) and the lowest was found during spring (0.58 ± 0.42 µg C female-1 d-1). The longest prosome length (PL) was registered in summer (1.15 ± 0.05 mm) and the shorter during autumn (1.01 ± 0.04 mm). No significant correlation was found in a daily base between EPR and PL with chlorophyll a (Chl a) concentration neither the sea surface temperature (SST). In temporal scale, in winter, spring and summer the SST was low (<23.2°C) in contrast, autumn presented high SST (>27 °C). Chl a was low (<1 mg m-3) in winter, spring and autumn, whereas in summer it was high (>3 mg m-3). Although the correlation was non significant between the biological parameters and the environmental variables (p> 0.05), the species showed high values of LP and TPH in summer when SST were low and the concentration of Chl a was high.Se estimó la tasa de producción de huevos (TPH) para Centropages furcatus en la Bahía de la Paz, Baja California Sur, México, durante 2003. Esta especie es una de las más abundantes y frecuentes de los copépodos en la zona. La estimación en carbono de la producción de huevos fue máxima en verano (1.20 ± 0.7 µg C hembra-1 d-1) y mínima en primavera (0.58 ± 0.42 µg C hembra-1 d-1). La mayor longitud del prosoma (LP) fue registrada en verano (1.15 ± 0.05 mm) y la menor en otoño (1.01 ± 0.04 mm). No hubo correlación significativa entre LP y TPH con la concentración de clorofila a (Cl a) ni con la temperatura superficial del mar (TSM). En invierno, primavera y verano la TSM fue menor a 23.2 °C, a diferencia de otoño que presentó TSM mayores a 27 °C. En relación a la Cl a, tanto en invierno, primavera y otoño los valores fueron menores a 1 mg m-3, mientras que en verano fueron mayores a 3 mg m-3. Aunque la correlación no fue significativa (p >0.05) entre los parámetros biológicos y las variables ambientales, la especie presentó valores altos de LP y TPH en verano cuando la TSM fue baja y la concentración de Cl a fue la más alta

    Cambios diarios en la composición y abundancia de copépodos planctónicos al sur de Bahía de La Paz (Octubre 2002)

    Get PDF
    The goal of this work to analyze the changes in the copepods community, and its relationships with the sea temperature, chl-a concentration and tidal level south of Bahía de La Paz during October 2002. The statistical analysis split the study period with different communities. During the first phase, the oceanic and neritic-oceanic species were dominant (e.g. Labidocera acutifrons, L. acuta, L. diandra, and L. trispinosa), whereas during the second period an increase of the abundance and species richness of coastal and estuarine species was measured (e.g. Acartia lilljeborgii, A. clausi, Nannocalanus minor, and Canthocalanus pauper). These changes were mainly associated with changes in the tide level with respect to de mean sea level as well as with the chlorophyll-a concentration.El objetivo de este trabajo fue analizar los cambios de la comunidad de copépodos y su relación con la temperatura del mar, concentración de Cl a y la altura de la marea al sur de Bahía de La Paz durante octubre del 2002. El análisis estadístico dividió el periodo de estudio en dos etapas con distintas comunidades. En la primera etapa dominaron especies oceánicas y neríticooceánicas (Ej. Labidocera acutifrons, L. acuta, L. diandra, L. trispinosa), y en la segunda se incrementó la abundancia y número de especies costeras y lagunares (Ej. Acartia lilljeborgii, A. clausi, Nannocalanus minor y Canthocalanus pauper). Estos cambios, se asociaron principalmente a cambios en la altura de la marea con respecto al nivel medio del mar y a incrementos en la concentración de Cl a

    Seek Help from Teachers or Fight Back? Student Perceptions of Teachers’ Actions during Conflicts and Responses to Peer Victimization

    Get PDF
    Previous research has shown that teachers’ actions when addressing conflict on school grounds can shape adolescent perceptions regarding how well the school manages victimization. Our objective in this study was to determine how these perceptions influenced the likelihood that adolescent students would react to victimization scenarios by either seeking help from school authority or physically fighting back. Vignettes describing two events of victimization were administered to 148 ethnic minority adolescents (Latino, African American, and Asian backgrounds; 49% female) attending an urban high school with high rates of conflict. Positive perceptions of teachers’ actions during conflicts—assessed via a questionnaire tapping how teachers manage student conflicts both generally and in a specific instance of strife—predicted a greater willingness to seek help from school authority, which in turn negatively predicted self-reported aggressive responses to the victimization scenarios. Path analysis established the viability of this indirect effect model, even when we controlled for sex, beliefs about the acceptability of aggression, and previous levels of reactive aggression. Adolescents’ perceptions of teachers’ actions during conflicts are discussed in relation to social information processing models, improving student–teacher relations, and decreasing aggression at schools

    A review of elliptical and disc galaxy structure, and modern scaling laws

    Full text link
    A century ago, in 1911 and 1913, Plummer and then Reynolds introduced their models to describe the radial distribution of stars in `nebulae'. This article reviews the progress since then, providing both an historical perspective and a contemporary review of the stellar structure of bulges, discs and elliptical galaxies. The quantification of galaxy nuclei, such as central mass deficits and excess nuclear light, plus the structure of dark matter halos and cD galaxy envelopes, are discussed. Issues pertaining to spiral galaxies including dust, bulge-to-disc ratios, bulgeless galaxies, bars and the identification of pseudobulges are also reviewed. An array of modern scaling relations involving sizes, luminosities, surface brightnesses and stellar concentrations are presented, many of which are shown to be curved. These 'redshift zero' relations not only quantify the behavior and nature of galaxies in the Universe today, but are the modern benchmark for evolutionary studies of galaxies, whether based on observations, N-body-simulations or semi-analytical modelling. For example, it is shown that some of the recently discovered compact elliptical galaxies at 1.5 < z < 2.5 may be the bulges of modern disc galaxies.Comment: Condensed version (due to Contract) of an invited review article to appear in "Planets, Stars and Stellar Systems"(www.springer.com/astronomy/book/978-90-481-8818-5). 500+ references incl. many somewhat forgotten, pioneer papers. Original submission to Springer: 07-June-201

    Discovery of a new class of inhibitors for the protein arginine deiminase type 4 (PAD4) by structure-based virtual screening

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Rheumatoid arthritis (RA) is an autoimmune disease with unknown etiology. Anticitrullinated protein autoantibody has been documented as a highly specific autoantibody associated with RA. Protein arginine deiminase type 4 (PAD4) is the enzyme responsible for catalyzing the conversion of peptidylarginine into peptidylcitrulline. PAD4 is a new therapeutic target for RA treatment. In order to search for inhibitors of PAD4, structure-based virtual screening was performed using LIDAEUS (Ligand discovery at Edinburgh university). Potential inhibitors were screened experimentally by inhibition assays.</p> <p>Results</p> <p>Twenty two of the top-ranked water-soluble compounds were selected for inhibitory screening against PAD4. Three compounds showed significant inhibition of PAD4 and their IC<sub>50 </sub>values were investigated. The structures of the three compounds show no resemblance with previously discovered PAD4 inhibitors, nor with existing drugs for RA treatment.</p> <p>Conclusion</p> <p>Three compounds were discovered as potential inhibitors of PAD4 by virtual screening. The compounds are commercially available and can be used as scaffolds to design more potent inhibitors against PAD4.</p

    The influence of salinity on the effects of Multi-walled carbon nanotubes on polychaetes

    Get PDF
    Salinity shifts in estuarine and coastal areas are becoming a topic of concern and are one of the main factors influencing nanoparticles behaviour in the environment. For this reason, the impacts of multiwalled carbon nanotubes (MWCNTs) under different seawater salinity conditions were evaluated on the common ragworm Hediste diversicolor, a polychaete species widely used as bioindicator of estuarine environmental quality. An innovative method to assess the presence of MWCNT aggregates in the sediments was used for the first time. Biomarkers approach was used to evaluate the metabolic capacity, oxidative status and neurotoxicity of polychaetes after long-term exposure. The results revealed an alteration of energy-related responses in contaminated polychaetes under both salinity conditions, resulting in an increase of metabolism and expenditure of their energy reserves (lower glycogen and protein contents). Moreover, a concentration-dependent toxicity (higher lipid peroxidation, lower ratio between reduced and oxidized glutathione and activation of antioxidant defences and biotransformation mechanisms) was observed in H. diversicolor, especially when exposed to low salinity. Additionally, neurotoxicity was observed by inhibition of Cholinesterases activity in organisms exposed to MWCNTs at both salinities.publishe

    Advances in reforming and partial oxidation of hydrocarbons for hydrogen production and fuel cell applications

    Get PDF
    One of the most attractive routes for the production of hydrogen or syngas for use in fuel cell applications is the reforming and partial oxidation of hydrocarbons. The use of hydrocarbons in high temperature fuel cells is achieved through either external or internal reforming. Reforming and partial oxidation catalysis to convert hydrocarbons to hydrogen rich syngas plays an important role in fuel processing technology. The current research in the area of reforming and partial oxidation of methane, methanol and ethanol includes catalysts for reforming and oxidation, methods of catalyst synthesis, and the effective utilization of fuel for both external and internal reforming processes. In this paper the recent progress in these areas of research is reviewed along with the reforming of liquid hydrocarbons, from this an overview of the current best performing catalysts for the reforming and partial oxidizing of hydrocarbons for hydrogen production is summarized
    corecore