216 research outputs found
Chemical distribution of HII regions towards the Galactic anticentre
We study the physical and chemical properties of a sample of HII regions
located at RG >11 kpc and present the radial distribution of abundances towards
the Galaxy anticentre.
We carried out optical spectroscopic observations of nine HII regions with
the WHT. The sample was increased by searching the literature for optical
observations of regions towards the Galactic anticentre, re-analysing them to
obtain a single sample of 23 objects covering the Galactocentric radius from 11
kpc to 18 kpc to be processed in a homogeneous and consistent manner. Accurate
electron densities and temperatures of several ionic species were derived in 13
HII regions. These physical parameters were applied to the spectra to determine
direct total chemical abundances. For those regions without direct estimations
of temperature, chemical abundances were derived by performing tailor-made
photoionisation models and/or by using an empirical relation obtained from
radio recombination and optical temperatures.
We performed weighted least-squares fits to the distribution of the derived
abundances along the Galactocentric distances to study the radial gradients of
metallicity. The distributions O/H, N/H, S/H, and Ar/H towards the anticentre
can be represented by decreasing linear radial gradients, while in the case of
N/O abundances the radial distribution is better fitted with a two-zone model.
The He/H radial gradient is presented here for the first time; we find a slope
that is not significantly different from zero. The derived gradient for oxygen
shows a clear decrease with distance with a slope of -0.053dex/kpc. Although a
shallower slope at large Galactocentric distances is suggested by our data, the
flattening of the distribution cannot be confirmed and more objects towards the
anticentre need to be studied in order to establish the true form of the
metallicity gradient.Comment: Accepted for publication in Section 5. Galactic structure, stellar
clusters and populations of Astronomy and Astrophysics. The official date of
acceptance is 13/09/2016. 19 pages, 15 figures and 10 table
Can National Innovation Substitute The Role of Environmental Regulation to Improve Corporate Environmental Performance?
Environmental regulatory uncertainty has attracted extraordinary attention among scholars, managers, policy-makers and other members of society. Despite this increasing attention, the impact of environmental regulatory uncertainty on the environmental approaches of firms is difficult to estimate in the business context. Considering that environmental regulations are not the only mechanism enabling firms to develop proactive environmental management practices, we show that the national institutional profile delineates a firm’s environmental progress. Specifically, we argue that the national level of innovation is an essential institutional condition that can encourage firms to develop advanced environmental approaches and even overcoming the effect of environmental regulatory uncertainty on corporate environmental performance. Using a sample of 1,912 firms from 19 countries, we developed different scenarios that combine the effects of environmental regulatory uncertainty and the national level of innovation. Knowledge of these different situations illustrates how managers cope with environmental regulatory uncertainty.Environmental Regulatory Uncertainty; National Level of Innovation; Corporate Environmental Performance
Effect of abiotic stress on the production on lutein and beta-carotene by Chlamydomonas acidophila
Chlamydomonas acidophila growing autotrophically with continuous PAR light (160 µE.m-2.s-1) and 30 ºC may accumulate carotenoids which increase in response to abiotic stress, like high light intensity, UV-A radiation and temperature fluctuation. At 240 µE.m-2.s-1 the alga contains 57.5 ± 1.6 mg.l-1 of total carotenoids after 20 days of growing, which does not significantly change by an irradiance of 1000 µE.m-2.s-1. Lutein (20 ± 0.5 mg.l-1) and β-carotene (8.3 ± 0.2 mg.l-1) production were particularly high in C. acidophila, while zeaxanthine (0.2 ± 0.1 mg.l-1) was low. Enhanced production of these carotenoids was also observed in cultures illuminated with PAR light (160 µE.m-2.s-1) supplemented with moderate UV-A radiation (10 µE.m-2.s-1).
Optimum algae growth takes place at 40 ºC, like the maximum amount of intracellular lutein and β-carotene. On the other hand, the presence of iron in the culture medium, in a range between 5-35 mM, significantly decreased the cell viability and the intracellular content of carotenoids, however cupper, at 1-5 mM, appears to increase the synthesis of β-carotene. The alga can growth under mixotrophic conditions, with glucose or acetate, 10 mM, as carbon source, but such conditions did not improved the intracellular content of carotenoids
IAA : Información y actualidad astronómica (2)
Sumario : Investigación: La misión Envisat.--
Una década de investigación con el telescopio espacial
Hubble.--
Ventana Abierta: ¿Ciencias o letras?...Jose Carlos del Toro Iniesta.--
Charlas con...John Huchra.--
Especial: 25 años del IAA.--
Actualidad Científica: Plano a gran escala, tal vez, pero no euclídeo.--
Detección óptica de impactos en la cara oscura de la
Luna.--
Actividades IAA.--
Agenda.N
Evaluation of generic skills training in university computer engineering
Recepción: 21 de septiembre de 2015 | Revisión: 28 de septiembre de 2015 | Aceptación/Publicación: 5 de octubre de 2015Correspondencia: [email protected] modelo universitario de enseñanza aprendizaje basado en competencias supone un reto que implica no solo una innovación metodológica en la práctica docente sino también tecnológica, por la utilización de entornos virtuales de aprendizaje diseñados de forma específica para el desarrollo de competencias a partir de tareas contextualizadas acordes con el perfil profesional que se está formando y, finalmente, de modificaciones en las herramientas y técnicas de evaluación. Se presenta en este artículo, en relación a la innovación en evaluación, el proceso de elaboración y validación por expertos de un instrumento de evaluación de competencias basado en el uso de rúbricas, a aplicar en formación universitaria de Ingeniería en Informática en Argentina. El diseño parte de la definición de las competencias y pasa por la validación de la rúbrica por parte de 10 expertos. Se ofrece como conclusión la rúbrica generada.Abstrac: A university teaching-learning model based on competences is a challenge that involves not only a methodological innovation in teaching but also technological, for the use of virtual learning environments designed specifically for skills development from contextualized tasks chords with the professional profile being formed and eventually changes in the tools and techniques of evaluation. The development and validation process is presented in this article, in relation to innovation in assessment by experts of a skills assessment tool based on the use of rubrics, to apply to university education in Computer Engineering in Argentina. The design part of the definition of powers and go through the validation of the heading by 10 experts. Heading generated is offered in conclusion.Universidad de Granada. Departamento de Psicología Social. Proyecto de Innovación Docente ReiDoCre
Nearby supernova host galaxies from the CALIFA survey: II. Supernova environmental metallicity
The metallicity of a supernova progenitor, together with its mass, is one of the main parameters that can rule the progenitor's fate. We present the second study of nearby supernova (SN) host galaxies (0.005 10 dex) by targeted searches. We neither found evidence that the metallicity at the SN location differs from the average metallicity at the galactocentric distance of the SNe. By extending our SN sample with published metallicities at the SN location, we are able to study the metallicity distributions for all SN subtypes split into SN discovered in targeted and untargeted searches. We confirm a bias toward higher host masses and metallicities in the targeted searches. By combining data from targeted and untargeted searches, we found a sequence from higher to lower local metallicity: SN Ia, Ic, and II show the highest metallicity, which is significantly higher than those of SN Ib, IIb, and Ic-BL. Our results support the scenario according to which SN Ib result from binary progenitors. Additionally, at least part of the SN Ic are the result of single massive stars that were stripped of their outer layers by metallicity-driven winds. We studied several proxies of the local metallicity that are frequently used in the literature and found that the total host metallicity allows estimating the metallicity at the SN location with an accuracy better than 0.08 dex and very small bias. In addition, weak AGNs that cannot be seen in the total spectrum may weakly bias (by 0.04 dex) the metallicity estimate that is derived from the galaxy-integrated spectrum. © ESO, 2016.This work was partly funded by FCT with the research grant PTDC/CTE-AST/112582/2009. Support for L.G. is partially provided by FCT, by CONICYT through FONDECYT grant 3140566, and from the Ministry of Economy, Development, and Tourism's Millennium Science Initiative through grant IC12009, awarded to The Millennium Institute of Astrophysics (MAS). V.S. acknowledges financial support from Fundacao para a Ciencia e a Tecnologia (FCT) under program Ciencia 2008. C.J.W. acknowledges support through the Marie Curie Career Integration Grant 303912.Peer Reviewe
Searching for selective scaffolds against Plasmodium falciparum glucose-6-phosphate dehydrogenase 6-phosphogluconolactonase
Malaria is a parasitic disease caused by Plasmodium spp., being one of the major causes of death worldwide with two-hundred million new infections and hundreds of thousands of deaths in 2015. Despite the important advances in its prevention and treatment, its resistance to current drug therapies is still a serious risk in its eradication. There is urgency in finding novel targets and drugs operating by novel mechanisms, avoiding cross-resistance to classical antimalarials. In this context, the bifunctional enzyme Glucose-6- phosphate dehydrogenase 6-phosphogluconolactonase appears to be a promising therapeutic target due to its crucial role in regulating the PPP pathway (pentose phosphate pathway), which is the major source of redox potential in Plasmodium falciparum. In the last few years, our group detected a specific mutation between the human and the Plasmodium falciparum form in the binding site of Glucose-6-phosphate (G6P), the endogenous ligand of Glucose-6-phosphate dehydrogenase (G6PD). This mutation involves the substitution of an Arginine (human) by an Aspartate (parasite), which allowed us to create a validated in-house homology model of PfG6PD. Based on this result, the group has focused their efforts, through different molecular modelling techniques, in the discovery of selective scaffolds against PfG6PD. Current efforts address the development of a complete structural model of the bifunctional enzyme, which may offer novel opportunities to develop molecules capable of inhibiting this relevant enzyme
IAA : Información y actualidad astronómica (10)
Sumario : Investigación:
Chorros relativistas en núcleos activos de galaxias.--
Materia oscura: a tientas por el Universo.--
Ventana Abierta:
Físico teórico autónomo se ofrece para.--
Charlas con… Robert Haberle.--
Actualidad Científica:
La búsqueda de las estrellas más viejas de la Galaxia.--
Un superbólido más brillante que la Luna llena surcó el cielo argelino.--
Actividades IAA.--
Agenda.Esta revista se publica con la ayuda de la Acción Especial DIF 2001-4284-E del Programa Nacional de Difusión
de la Ciencia y la Tecnología, del Ministerio de Ciencia y TecnologíaN
A Slow-Digesting Carbohydrate Diet during Rat Pregnancy Protects O spring from Non-Alcoholic Fatty Liver Disease Risk through the Modulation of the Carbohydrate-Response Element and Sterol Regulatory Element Binding Proteins
High-fat (HF) and rapid digestive (RD) carbohydrate diets during pregnancy promote
excessive adipogenesis in o spring. This e ect can be corrected by diets with similar glycemic
loads, but low rates of carbohydrate digestion. However, the e ects of these diets on metabolic
programming in the livers of o spring, and the liver metabolism contributions to adipogenesis, remain
to be addressed. In this study, pregnant insulin-resistant rats were fed high-fat diets with similar
glycemic loads but di erent rates of carbohydrate digestion, High Fat-Rapid Digestive (HF–RD) diet
or High Fat-Slow Digestive (HF–SD) diet. O spring were fed a standard diet for 10 weeks, and the
impact of these diets on the metabolic and signaling pathways involved in liver fat synthesis and
storage of o spring were analyzed, including liver lipidomics, glycogen and carbohydrate and lipid
metabolism key enzymes and signaling pathways. Livers from animals whose mothers were fed an
HF–RD diet showed higher saturated triacylglycerol deposits with lower carbon numbers and double
bond contents compared with the HF–SD group. Moreover, the HF–RD group exhibited enhanced
glucose transporter 2, pyruvate kinase (PK), acetyl coenzyme A carboxylase (ACC) and fatty acid (FA)
synthase expression, and a decrease in pyruvate carboxylase (PyC) expression leading to an altered
liver lipid profile. These parameters were normalized in the HF–SD group. The changes in lipogenic
enzyme expression were parallel to changes in AktPKB phosphorylation status and nuclear expression
in carbohydrate-response element and sterol regulatory element binding proteins. In conclusion, an
HF–RD diet during pregnancy translates to changes in liver signaling and metabolic pathways in
o spring, enhancing liver lipid storage and synthesis, and therefore non-alcoholic fatty liver disease
(NAFLD) risk. These changes can be corrected by feeding an HF–SD diet during pregnancy.This research was funded by the European Union’s Seventh Framework Programme (FP7/2007–2013):
project EarlyNutrition, under grant agreement no. 289346
La radiación solar: efectos en la salud y el medio ambiente
140 páginasEl incremento de cierto tipo de radiaciones ultravioletas procedentes del sol, perjudiciales para la salud y el medio ambiente es un tema de candente actualidad, a pesar de la aparente recuperación de la capa de ozono, filtro protector de la biosfera y de la calidad de vida de los seres que habitan el Planeta. La obra ha tratado de definir la situación actual de este gas a escala planetaria, analizando las causas físicas de su aparición y de su destrucción y las consecuencias que para el medio ambiente y la salud tiene el incremento de radiación ultravioleta
- …