Long slit spectroscopy of a sample of isolated spirals with and without an AGN

We present the kinematical data obtained for a sample of active (Seyfert) and non active isolated spiral galaxies, based on long slit spectra along several position angles in the Halpha line region and, in some cases, in the Ca triplet region as well. Gas velocity distributions are presented, together with a simple circular rotation model that allows to determine the kinematical major axes. Stellar velocity distributions are also shown. The main result is that active and control galaxies seem to be equivalent in all kinematical aspects. For both subsamples, the departure from pure circular rotation in some galaxies can be explained by the presence of a bar and/or of a spiral arm. They also present the same kind of peculiarities, in particular, S-shape structures are quite common near the nuclear regions. They define very similar Tully-Fisher relations. Emission line ratios are given for all the detected HII regions; the analysis of the [NII]/Halpha metallicity indicator shows that active and non-active galaxies have indistinguishable disk metallicities. These results argue in favour of active and non-active isolated spiral galaxies having essentially the same properties, in agreement with our previous results based on the analysis of near infrared images. It appears now necessary to confirm these results on a larger sample.Comment: 35 pages, 54 figures, Accepted for publication in Astronomy & Astrophysics The full paper with its figures is available on the anonymous account of ftp.iap.fr in /home/ftp/pub/from_users/durret/marquez.ps.gz (999 kb

Classical properties of algebras using a new graph association

We study the relation between algebraic structures and Graph Theory. We have defined five different weighted digraphs associated to a finite dimensional algebra over a field in order to tackle important properties of the associated algebras, mainly the nilpotency and solvability in the case of Leibniz algebras

Improving carotenoids biosynthesis pathway in the unicelullar microalgae Chlamydomonas reinhardtii

Introduction: Carotenoids are a wide group of isoprenoids synthesized by photosynthetic organisms and some non-photosynthetic yeast and bacteria (1).They are indispensable in light harvesting and energy transference during photosynthesis and in the protection of the photosynthetic apparatus against the photooxidative damage. Mammals cannot synthesize them and must include them in their diet as precursors for essential compounds. The important colorant, antioxidant and provitamin properties of carotenoids, have made of them an important group of high-added value compounds, massively commercialized (1,2).There is an increasing demand of natural carotenoids and microalgae can be an excellent natural source of carotenoids.Results and conclusions: In this work, we describe the subcloning of two genes from the carotenoid biosynthesis pathway in a microalgal expression vector: The PSY gene from Dunaliella salina, encoding phytoene synthase, a key enzyme in the pathway, which catalyzes the formation of phytoene, and CRTI gene encoding for fitoene desaturase from Erwinia Uredowa. The bacterial CRTI gene catalyzes the conversion of phytoene to lycopene, replacing the function of two microalgal enzymes phytoene desaturase (PDS) and chis-carotene desaturase (ZDS) (1,3). PSY and CRTI genes were fused by a short DNA fragment which encodes a self-cleaving peptide and fused to the selective marker gene APHVIII from Streptomyces rimosus, encoding for an aminoglycoside 3'phosphotransferase that confers resistance to the antibiotic paromomycin. All genes were placed under the control of the strong constitutive promoters RBCS2 and HSP70A and terminated by the 3'untranslated region of RBCS2 (plasmid 4-75).C. reinhardtii was nuclear transformated with plasmid 4-75. Obtained transformants were analysed by PCR to check the insertion of the PSY, CRTI and APHVIII genes into the genome of C. reinhardtii and tested for expression at mRNA level. The phenotype of some of the transformants was also analyzed studying their carotenoid composition.The obtained data show that the designed vector allows the insertion of all genes into the genome, although we have detected unexpected DNA cleavage and rearrangements during the integration process, which leads to discontinuous insertion of the genes, as they are placed in the 4-75 plasmid. This has made impossible to isolate any transformant with significant phenotypical changes so far and it is subject of current investigation

Communication: Improving the density functional theoryU description of CeO 2 by including the contribution of the O 2p electrons

Density functional theory (DFT) based approaches within the local-density approximation or generalized gradient approximation frameworks fail to predict the correct electron localization in strongly correlated systems due to the lack of cancellation of the Coulomb self-interaction. This problem might be circumvented either by using hybrid functionals or by introducing a Hubbard-like term to account for the on site interactions. This latter DFTU approach is less expensive and therefore more practical for extensive calculations in solid-state computational simulations. By and large, the U term only affects the metal electrons, in our case the Ce 4f ones. In the present work, we report a systematic analysis of the effect of adding such a U term also to the oxygen 2p electrons. We find that using a set of U f 5 eV and U p 5eV effective terms leads to improved description of the lattice parameters, band gaps, and formation and reduction energies of CeO

Relative age effect on national selection process in triathlon

El objetivo de este estudio fue analizar el efecto de la edad relativa (RAE) en el proceso de selección nacional de triatletas (n = 1321) durante las temporadas 2013-2015. La muestra fue divida por categorías y sexo. Cada una fue subdividida en 4 cuartiles según la fecha de nacimiento. Las diferencias fueron analizadas mediante la prueba no paramétrica Krustal-Wallis. Para la comparación múltiple se utilizó U de Mann Whitney. Los resultados mostraron que el rendimiento en las pruebas analizadas presentaba una mejor tendencia en aquellos deportistas nacidos en el primer cuartil del año para el sexo masculino. En esta línea, los atletas nacidos en la última parte mostraron un peor rendimiento general. Estos resultados fueron menos consistentes para el sexo femenino. Este trabajo ha puesto de manifiesto la influencia del RAE en los procesos de identificación de talentos y la estructura competitiva, sugiriendo su consideración en los procesos de selecciónThe aim of this study was to analyze the influence of relative age effect on the selection process in triathlon (n = 1321). The sample was divided by category and gender. Each category was allocated into four quartiles - based on date of birth according to the selection year. The Krustal-Wallis and Mann-Whitney test were used to analyze the intra-categorical and intra-gender differences. The results showed a better performance trend in those athletes that were born in the first quartile. In contrast, athletes that were born in the latter part of the year showed poorer overall performance and a lower score in the point scale. However, these results were less consistent for females. This work has shown a significant loss of potential triathlon talent due to the influence of RAE in the selection process and competitive structureEste trabajo ha sido financiado por la Secretaría de Investigación, Desarrollo e Innovación del Ministerio de Economía [DEP2012-32124

Is there a pre-Cretaceous source rock in the Colombia Putumayo Basin? : clues from a study of crude oils by conventional and high resolution geochemical methods

A geochemical characterization of sixteen crude oil samples from the Putumayo Basin, southern Colombia, was carried out. This basin is located to the north of Ecuador's Oriente Basin, one of the most prolific hydrocarbon basins in South America. Regardless of the fact that these two basins seem to share the same geological evolution, the volume of hydrocarbon reserves found in the Oriente Basin is five times greater than in the Putumayo Basin. This represents an exploratory opportunity to the extent that a better understanding of the petroleum system processes in the Putumayo Basin can be achieved. Newly available geochemical technology shows evidence that these crude oils originated from Late Cretaceous source rocks. The novel application of an age-related biomarker, the C25-highly branched isoprenoid, has constrained the age of the principal source of all these oils as Late Cretaceous or younger. Advanced geochemical technologies, such as compound specific isotope analyses of biomarkers (CSIA-B) and diamondoids (CSIA-D), and quantitative extended diamondoid analysis (QEDA), have confirmed, repeatedly, that the oil samples are all related to the same source with minor facies variations. The integration of these results with geological data suggests the presence of a very efficient petroleum system, characterized by an alternating sequence of soçurce and reservoir rocks. Thermal maturity of the oils from biomarker and diamondoid parameters ranges from well before the peak of hydrocarbon expulsion to the beginning of the late hydrocarbon generation phase. The aerial distribution of these maturity parameters suggests the existence of two, or possibly three, pods of active source rocks, located to the southwest and to the east of the basin, and possibly to the north. This would modify the classic hydrocarbon migration model for the Putumayo Basin, increasing the hydrocarbon potential of the basin. Given the low level of thermal maturity documented in the Cretaceous sequence that has been drilled, the possibility to evaluate the presence of a very reactive kerogen with hydrocarbon expulsion thresholds at lower temperatures is proposed

The detection of stellar velocity dispersion drops in the central regions of five isolated Seyfert spirals

We analyze the kinematics of the central regions of five isolated Seyfert spiral galaxies from the DEGAS sample (four with new data presented in this paper, IC184, UGC3223, NGC2639, NGC6814, and NGC6951 from our previous data), by using long slit spectroscopy in the CaII triplet range (at ~ 8600 A) obtained with a 4m-class telescope. A drop of the velocity dispersions in the innermost 1-3 arcsec is observed in four of them, and hinted in the remaining galaxy (NGC6814). The available HST images for our sample together with another nine galaxies with reported velocity dispersion drops, are also used to investigate the presence of morphological inner structures at the scales of the kinematical drops. Evidence for disk-like shapes is found in 12 out of the 14 cases. The only exceptions are NGC6814 and NGC6951. Existing N-body simulations including stars, gas and star formation predict that such a drop is most probably due to a young stellar population born from dynamically cold gas accreted in a circumnuclear disk formed during an episode of central gas accretion driven by a bar. The equivalent widths of the Calcium triplet lines for our 5 galaxies have been measured. Even if the profiles could be formally consistent with constant EW(CaT) values, they seem to indicate the presence of a local maximum in the regions corresponding spatially to the drops; if confirmed, this would imply the presence of a different stellar population, whose properties could help constraining the models.Comment: A&A accepted for publicatio

Cómo motivar a los estudiantes de secundaria mediante actividades de ciencias atractivas y divertidas

Se presenta una propuesta de formación del profesorado llevada a cabo durante dos cursos académicos (2006/08) con la finalidad de mejorar la motivación e interés de los estudiantes hacia el aprendizaje de las ciencias. Se diseñó e implementó un curso desde la perspectiva de una ciencia comprometida, pero también amena, creativa y divertida, incluyendo actividades interactivas realizadas en colaboración con el Museo de Ciencias Príncipe Felipe, experimentos de laboratorio, textos divulgativos con enfoques CTSA (Ciencia-Tecnología-Sociedad-Ambiente), juguetes científicos, así como el aporte de experiencias provenientes de otros países europeos (Alemania, Francia y Reino Unido). Esta iniciativa, en la que han participado 80 profesores ha sido un instrumento eficaz tanto para la mejora de la motivación como para promover la formación de comunidades de práctica

Controlled manipulation of enzyme specificity through immobilization-induced flexibility constraints

It is thought that during immobilization enzymes, as dynamic biomolecules, may become distorted and this may alter their catalytic properties. However, the effects of different immobilization strategies on enzyme rigidity or flexibility and their consequences in specificity and stereochemistry at large scale has not been yet clearly evaluated and understood. This was here investigated by using as model an ester hydrolase, isolated from a bacterium inhabiting a karstic lake, with broad substrate spectrum (72 esters being converted; 61.5 U mg$^{-1}$ for glyceryl tripropionate) but initially non-enantiospecific. We found that the enzyme (7 nm × 4.4 nm × 4.2 nm) could be efficiently ionic exchanged inside the pores (9.3 nm under dry conditions) of amino-functionalized ordered mesoporous material (NH$_{2}$-SBA-15), achieving a protein load of 48 mg g−1, and a specific activity of 4.5 ± 0.1 U mg$^{-1}$. When the enzyme was site-directed immobilized through His interaction with an immobilized cationon the surface of two types of magnetic micro-particles through hexahistidine-tags, protein loads up to 10.2 μg g$^{-1}$ and specific activities of up to 29.9 ± 0.3 U mg$^{-1}$, were obtained. We found that ionically exchanged enzyme inside pores of NH2-SBA-15 drastically narrowed the substrate range (17 esters), to an extent much higher than ionically exchanged enzyme on the surface of magnetic micro-particles (up to 61 esters). This is attributed to differences in surface chemistry, particle size, and substrate accessibility to the active site tunnel. Our results also suggested, for the first time, that immobilization of enzymes in pores of similar size may alter the enzyme structures and produce enzyme active centers with different configuration which promote stereochemical conversions in a manner different to those arising from surface immobilization, where the strength of the ionic exchange also has an influence. This was shown by demonstrating that when the enzyme was introduced inside pores with a diameter (under dry conditions) slightly higher than that of the enzyme crystal structure a biocatalyst enantiospecific for ethyl (R)-4-chloro-3-hydroxybutyrate was produced, a feature not found when using wider pores. By contrast, immobilization on the surface of ferromagnetic microparticles produced selective biocatalysts for methyl (S)-(+)-mandelate or methyl (S)-lactate depending on the functionalization. This study illustrates the benefits of extensive analysis of the substrate spectra to better understand the effects of different immobilization strategies on enzyme flexibility/rigidity, as well as substrate specificity and stereochemistry. Our results will help to design tunable materials and interfaces for a controlled manipulation of specificity and to transform non-enantiospecific enzymes into stereo-chemically substrate promiscuous biocatalysts capable of converting multiple chiral molecules