5,727 research outputs found

    Constraints on Dark Energy state equation with varying pivoting redshift

    Full text link
    We assume the DE state equations w(a) = w_0+w_a(a_p-a), and study the dependence of the constraints on w_0 and w_a coefficients on the pivoting redshift 1+z_p=1/a_p. Coefficients are fitted to data including WMAP7, SNIa (Union 2.1), BAO's (including WiggleZ and SDSS results) and H_0 constraints. The fitting algorithm is CosmoMC. We find specific differences between the cases when neutrino mass is allowed or disregarded. More in detail: i) The z_p value yielding uncorrelated constraints on w_0 and w_a is different in the two cases, holding ~0.25 and ~0.35, respectively. (ii) If we consider the intervals allowed to w_0, we find that they shift when z_p increases, in opposite directions for vanishing or allowed neutrino mass. This leads to no overlap between 1sigma intervals already at z_p >~0.4. (iii) The known effect that a more negative state parameter is required to allow for neutrino mass displays its effects on w_a, rather than on w_0. (iv) The w_0-w_a constraints found by using any pivot z_p can be translated into constraints holding at a specific z_p value (0 or the z_p where errors are uncorrelated). When we do so, error ellipses exhibit a satisfactory overlap.Comment: 13 pages, 7 figures, 2 table

    Development of quartz fiber calorimetry

    Get PDF
    Embedding radiation hard (up to Gigarad levels) silica optical fibres into an absorber is proposed for applications in very forward LHC calorimeters. The shower particles produce Cherenkov light. The main advantages of this solution are the fast response (signal duration below 10 ns), transverse dimension of the visible energy of hadronic showers of the order of 1 cm, and insensitivity to radio- and neutron- activation. A comprehensive study of the performance of such detector is proposed

    Morfometría corporal, diversidad natatoria y nicho de los tiburones demersales: estudio comparativo en el mar Mediterráneo

    Get PDF
    Seven demersal shark species belonging to six families, obtained from the southern Mediterranean Sea, were selected as representative of different putative swimming modes, inhabited depths and trophic levels. Caudal fin morphometrics (caudal fin span, area and aspect ratio), hepatosomatic index and muscular-skeletal amount per unit length were estimated and compared within and among species by means of both parametric and non-parametric multivariate and univariate statistical procedures. Intra-specific variation was related to size and, for one species only, also to sex. Two inter-specific patterns of variation were observed: the first pattern was interpreted as a swimming ability gradient between slow benthic and more pelagic species, as a function of caudal morphometry and body characteristics; the second pattern is related to the depth the species inhabit and/or their trophic level. These two hypotheses were tested with the current data and literature information, and discussed in the context of shark swimming modes, habit and environment. Based on observed differences in caudal fin morphometrics, liver and muscular masses, this paper is the first to provide a quantitative and comparative dataset for demersal sharks as a group, and attempts to describe sample variability as a function of expected swimming ability and occupied niche (depth inhabited and/or trophic level).Siete especies de tiburones demersales, pertenecientes a 6 familias, capturadas en el sur del mar Mediterráneo, fueron seleccionadas como representantes de diferentes modos de natación, profundidad que suelen habitar y niveles tróficos. La morfometría de la aleta caudal (longitud, área y relación de aspecto), el índice hepato¬somático y la relación entre músculo y esqueleto por unidad de longitud fueron determinados y comparados entre los indivi¬duos y entre especies a través de procedimientos estadísticos paramétricos y no paramétricos, multivariados y univariados. La variación intra-específica se relacionó con el tamaño y, para una única especie, también con el sexo. Se observaron dos patrones interespecíficos de variación: el primero fue interpretado como un gradiente de la capacidad de natación entre es-pecies bentónicas y las más pelágicas, en función de la morfometría caudal y de las características corporales. El segundo se debió principalmente a la profundidad habitada y / o el nivel trófico. Asociando los datos actuales a la información existente en la literatura, estas dos hipótesis se comprobaron y se examinaron en el contexto del tipo de natación del tiburón y el am¬biente marino. Apartir de las diferencias observadas en la morfometría de la aleta caudal, el hígado y las masas musculares, este documento ofrece por primera vez una base de datos cuantitativos y comparativos sobre los tiburones demersales, como grupo, intentando describir la variabilidad muestral como una función de la capacidad de natación esperada y de los nichos ocupados (profundidad habitada y/ o nivel trófico)

    RSE: relación entre perfil del gestor de los programas y determinación de los fines estratégicos

    Get PDF
    The main objective of the present research was to determine if the profile of the management area of Business Social Responsibility (BSR) has any influence in the definition of their strategic aims and the selection of primary stakeholders.The observations presented arise from the information gathered through a survey of businesses and sixteen hundred in-depth interviews with representatives. Four hypotheses were put forward. The first one stated that: Whenever Organizational Development areas manage BSR programs, their main objective lies on consolidation of primary corporate values (social dimension). Whereas primary corporate values respond to universal ones such as justice, equality of opportunity, we can certify that the hypothesis was confirmed, mainly due to explicit motivations that refer to community development and the building of cooperation ties with stakeholders.The second hypothesis, asserting that whenever the areas of Institutional Relations manage BSR programs are aimed to build corporative image (persuasive dimension), was not confirmed. Eventhough corporate image and reputation constitute a crucial aspect of the raison d´etre of these areas and it is considered that BSR provides an important contribution to the building thereof, the main motivation lies on the development of socially responsible actions and the identification of the company as a social actor.Our investigation shows that the third hypothesis cannot be confirmed either: BSR programs managed by areas related to Organizational Development and Corporate Responsibility and Sustainability comprise every stakeholder in the organization. It cannot be proved since like the rest of the areas they focus on priority stakeholders in the organization. What we did properly observe is the fact that stakeholders have different weights, being suppliers the ones with greater presence in their actions compared to the other areas. Regarding the last hypothesis which states that BSR programs managed by the areas of Institutional Relations prioritize external stakeholders, it cannot be confirmed since employees area top-priority audience for every company included in the investigation and are present in their BSR programs regardless of who manages them.The main conclusions are different denominations of the areas managing BSR programs do not involve large differences in the way they do it and the strategic objectives for the implementation of socially responsible policies respond to cross-cutting organizational plans and principles of all corporate activities, and are defined by the institutional philosophy and culture.La investigación tuvo como objetivo principal determinar si el perfil del área de gestión de los programas de Responsabilidad Social Empresaria (RSE) influye en el establecimiento de sus metas estratégicas y en la selección de grupos de interés prioritario. Las observaciones que se presentan surgen de la información relevada mediante una encuesta hecha a cien empresas y dieciséis entrevistas en profundidad realizadas a sus representantes.Se trabajó a partir de cuatro hipótesis. La primera establecía que las áreas de Desarrollo Organizacional,cuando gestionan los programas de RSE, tienen como principal objetivo la consolidaciónde valores corporativos elementales (dimensión social). La hipótesis se comprobó principalmente por las motivaciones manifiestas que hacen referencia al desarrollo comunitario y al establecimiento de lazos de cooperación con los grupos de interés.Como segunda hipótesis, se sostuvo que las áreas de Relaciones Institucionales tienen como principal objetivo la construcción de la imagen corporativa (dimensión persuasiva). Si bien ellas son una parte determinante de la razón de ser de estas áreas, la motivación principal es el desarrollo de acciones socialmente responsables y la identificación de la empresa como actor social. La investigación arroja que tampoco se cumple la tercera hipótesis: los programas de RSE gestionados por las áreas vinculadas al Desarrollo Organizacional y Responsabilidad Corporativay Sustentabilidad abarcan todos los grupos de interés de la organización. Al igual que el resto de las áreas, hacen foco en los grupos de interés prioritarios de la organización. Lo que sí se observa es que el peso de los grupos es distinto; los proveedores son un grupo con mayor presencia en sus acciones en comparación con el resto de las áreas. Con respecto a la última hipótesis, que los programas de RSE gestionados por las áreas de Relaciones Institucionales priorizan los grupos de interés externo, no se comprueba ya que los empleados son un público prioritario para casi la totalidad de las empresas incluidas en la investigación y están presentes en sus programas de RSE, sin importar quién los gestiona. En conclusión, las distintas denominaciones de las áreas que gestionan los programas de RSE no implican grandes diferencias en su modo de operar. Los objetivos estratégicos para laimplementación de políticas socialmente responsables responden a los planes organizacionales, transversales a todas las actividades corporativas, y se encuentran delimitados por la filosofía y cultura institucional

    Effect of cadmium on anion exchange capability through Band 3 protein in human erythrocytes

    Get PDF
    The efficiency of Band 3 protein, mediating HCO3-/Cl- exchange across erythrocytes membrane, is reduced by oxidative stress. The aim of the present study was to verify whether Band 3 protein efficiency is compromised by treatment with Cadmium (Cd2+), an extremely toxic heavy metal known to interfere with antioxidant enzymes, energy metabolism, gene expression and cell membranes. To this end, the rate constant for SO4= uptake through Band 3 protein (accounting for velocity of anion exchange) was measured along with membrane –SH groups, Malonyldialdehyde (MDA) and Band 3 protein expression levels in Cd2+ -treated human erythrocytes (300 µM, 1 mM). Our results show that Cd2+ reduced the rate constant for SO4= uptake, with a significant increase in MDA levels at both concentrations and with a reduction in –SH groups observed after 1 mM Cd2+ treatment, whereas Band 3 protein expression levels were unchanged in both conditions. In conclusion: i) Cd2+ reduces Band 3 protein efficiency via different mechanisms depending on metal concentration and with unchanged expression levels; ii) the assessment of Band 3 protein anion exchange capability is a good tool to assay the impact of heavy metals on cell homeostasis and, possibly, useful for diagnosis and monitoring of devalopment of Cd2+ toxicity-related pathologies

    Primera liberación de juveniles de mero Epinephelus marginatus (Lowe, 1834) (Serranidae: Teleostei) cultivados en criadero en arrecifes artificiales en el mar Mediterráneo: resultados de un estudio experimental

    Get PDF
    A pilot experiment of stock enhancement based on the release of hatchery-reared juveniles of dusky grouper, Epinephelus marginatus, was carried out at two artificial reefs located 0.9 km offshore the south-western Sicilian coast (Central Mediterranean). The fish assemblages inhabiting the reefs were characterized using underwater visual census (UVC) surveys. Despite some differences in fish species richness, diversity and abundance, both artificial reefs provide suitable feeding resources and shelter opportunities for the settlement of dusky grouper juveniles. A total of 95 dusky grouper juveniles, which were 3 and 4 years old, were released. No stress-related effects on fish swimming or behaviour were observed during the step by step transportation to the sea-bottom at 20 m depth. After release, several groupers showed very low reactivity; freezing and schooling were the most common behaviours. The sighting rate after one month of UVC surveys was 15.7% and 20% at the two artificial reefs. No effect of fish size at release on grouper survival was observed. Some groupers were not recorded on the pyramid of release but elsewhere in the same artificial reef, which demonstrated their ability to move around the reef. The extent of dispersal of the released juveniles largely exceeded the area encompassed by the reefs, which was shown by recaptures of tagged groupers by local fishermen up to 13 km from the release site. This result provides a first insight into the potential of stock enhancement of hatchery reared dusky grouper juveniles for marine ranching and conservation purposes.Un experimento de repoblación, basado en la liberación de juveniles de mero Epinephelus marginatus cultivados en criadero, fue realizado en dos arrecifes artificiales situados 0.9 kilómetros fuera de las costas sicilianas sur-occidentales (Mediterráneo Central). La ictiofauna de los arrecifes fue caracterizada a través de inmersiones submarinas, utilizando la técnica de censo visual (UVC). A pesar de algunas diferencias en número de especies, diversidad y abundancia, ambos arrecifes artificiales proporcionaron recursos alimenticios y refugio adecuados para el establecimiento de juveniles de mero. En total se liberaron 95 meros juveniles de 3 y 4 años de edad. Ningún efecto relacionado al estrés fue observado en el comportamiento de natación de los peces durante el gradual transporte hasta 20 m de profundidad. Después de la liberación, varios meros mostraron una reactividad muy baja, siendo el comportamiento más común quedarse inmóviles y agregados. Después de un mes de censos visuales, las tasas de avistamientos obtenidas en los arrecifes artificiales fueron de 15.7% y 20%. No se observó relación entre el tamaño en el momento de la liberación y la supervivencia. Algunos peces no fueron observados cerca del punto de liberación sino en otra parte del mismo arrecife artificial, demostrando así su capacidad de moverse por los alrededores. Según lo indicado por los pescadores locales que recobraron meros marcados hasta 13 kilómetros del punto de liberación, el grado de la dispersión de los juveniles liberados superó ampliamente el área abarcada por los arrecifes. Este resultado proporcionan la primera evaluación del potencial de los juveniles de E. marginatus cultivados en criadero para actividades de cría en mar y conservación

    Curcumin Protects -SH Groups and Sulphate Transport after Oxidative Damage in Human Erythrocytes

    Get PDF
    Background/Aims: Erythrocytes, continuously exposed to oxygen pressure and toxic compounds, are sensitive to oxidative stress, namely acting on integral Band 3 protein, with consequences on cell membranes deformability and anion transport efficiency. The aim of the present investigation, conducted on human erythrocytes, is to verify whether curcumin (1 or 10µM), a natural compound with proved antioxidant properties, may counteract Band 3-mediated anion transport alterations due to oxidative stress. Methods: Oxidative conditions were induced by exposure to, alternatively, either 2 mM N-ethylmaleimide (NEM) or pH-modified solutions (6.5 and 8.5). Rate constant for SO4= uptake and -SH groups estimation were measured to verify the effect of oxidative stress on anion transport efficiency and erythrocyte membranes. Results: After the exposure of erythrocytes to, alternatively, NEM or pH-modified solutions, a significant decrease in both rate constant for SO4= uptake and -SH groups was observed, which was prevented by curcumin, with a dose-dependent effect. Conclusions: Our results show that: i) the decreased efficiency of anion transport may be due to changes in Band 3 protein structure caused by cysteine -SH groups oxidation, especially after exposure to NEM and pH 6.5; ii) 10 µM Curcumin is effective in protecting erythrocytes from oxidative stress events at level of cell membrane transport

    Sulphate and Chloride-Dependent Potassium Transport in Human Erythrocytes are Affected by Crude Venom from Nematocysts of the Jellyfish Pelagia noctiluca

    Get PDF
    Background: It has been reported that biologically active compounds extracted from Cnidaria venom may induce damage by oxidative stress. Erythrocytes are constantly exposed to oxidative stresses, which can contribute to sulphydril (SH-) group oxidation and cell membrane deformability accompanied with activation of K-Cl co-transport and inhibition of anion transport. In this regard, Band 3 protein is responsible for mediating the electroneutral exchange of chloride (Cl-) for bicarbonate (HCO3-), particularly in erythrocytes, where it is the most abundant membrane protein. The aim of this study was to elucidate the effect of crude venom extracted from Pelagia noctiluca nematocysts on Band 3 -mediated anion transport in human erythrocytes. Methods: Erythrocytes were tested for SO42- uptake, K+ efflux, glutathione (GSH) levels and concentration of SH- groups. Results: The rate constant of SO42- uptake decreased progressively to 58% of control with increasing venom doses, and showed a 28% decrease after 2 mM NEM treatment. These effects can be explained by oxidative stress, which was reflected by decreased GSH levels in venom-treated erythrocytes. Hence, the decreased efficiency of anion transport may be due to changes in Band 3 structure caused by SH-group oxidation and reduced GSH concentration. In addition, an increased Cl--dependent K+ efflux was observed in venom-treated erythrocytes. Conclusion: Our results suggest that crude venom from Pelagia noctiluca alters cell membrane transport in human erythrocytes
    corecore