29 research outputs found

    Modelling the disk atmosphere of the low mass X-ray binary EXO 0748-676

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    Low mass X-ray binaries exhibit ionized emission from an extended disk atmosphere that surrounds the accretion disk. However, its nature and geometry is still unclear. In this work we present a spectral analysis of the extended atmosphere of EXO 0748-676 using high-resolution spectra from archival XMM-Newton observations. We model the RGS spectrum that is obtained during the eclipses. This enables us to model the emission lines that come only from the extended atmosphere of the source, and study its physical structure and properties. The RGS spectrum reveals a series of emission lines consistent with transitions of O VIII, O VII, Ne IX and N VII. We perform both Gaussian line fitting and photoionization modelling. Our results suggest that there are two photoionization gas components, out of pressure equilibrium with respect to each other. One with ionization parameter of 2.5 and a large opening angle, and one with 1.3. The second component is possibly covering a smaller fraction of the source. From the density diagnostics of the O vii triplet using photoionization modelling, we detect a rather high density plasma of > 10^13 cm^-3 for the lower ionization component. This latter component also displays an inflow velocity. We propose a scenario where the high ionization component constitutes an extended upper atmosphere of the accretion disk. The lower ionization component may instead be a clumpy gas created from the impact of the accretion stream with the disk.Comment: A&A accepted, 10 pages, 9 figure

    Preliminary study of the airborne pollen in the atmosphere of Puerto Ayora (Galapagos Islands, Ecuador)

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    Galapagos is an archipelago of volcanic islands located 972 km west from the continental Ecuador. They were declared by the UNESCO as a World Heritage Site and Biosphere Reserve due to their singular environmental value, where a third part of the native plants are endemic to this archipelago (Jaramillo et al., 2011). In spite of the numerous scientific studies carried out in Galapagos, there are not any aerobiological samplings being performed currently. The main objectives of this study were to install a pollen trap for detecting the presence of pollen in the atmosphere of Puerto Ayora (Santa Cruz, Galapagos Islands) and qualitatively identify the different pollen types detected during the studied period. A Durham (1946) gravimetric pollen trap was modified to turn it into a passive impact pollen trap based on Pla Dalmau (1957) modifications. It was placed on the roof of the Galapagos National School (Puerto Ayora, Santa Cruz Island) at a height of 15m above ground level. The samples were obtained by using silicone fluid as adhesive substance and glycerine gelatine as mounting mean. The pollen grains were counted in a surface of 14 x 48 mm in each sample. The pollen types were identified with the aid of the pollen guide of the Galapagos Island by Jaramillo & Trigo (2011) and the Charles Darwin Foundation pollen bank. Pollen types of endemic plants such as Darwiniothamnus sp., Passiflora foetida var. galapagensis Killip, Justicia galapagana Lindau and Castela galapageia Hook. f. were detected together with those of other native and introduced species. A high diversity of pollen types was detected, reflecting the particular vegetation of the island. This preliminary aerobiological information can be used as precedent for further studies on the pollination of native and introduced species of the Galapagos Islands, as well as for detecting possible allergic diseases in the population.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Observaciones sobre "Allium Rouyi Gautier"

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    Se ha localizado una población de Allium rouyi Gautier, especie considerada como extinta. En base al material recolectado se hace una nueva descripción y un estudio de las semillas y polen

    MAREJADAS RURALES Y LUCHAS POR LA VIDA, VOL. II: CONFLICTOS SOCIOTERRITORIALES Y POR RECURSOS NATURALES

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    Volumen 2. Conflictos socioterritoriales y por recursos naturales, coordinado por: Rosalía López Paniagua, Dante Ariel Ayala Ortiz y Armando Contreras Hernández, constituido por 19 trabajos, divididos en tres secciones. La primera titulada Tierra: tenencia y cultivos transgénicos, contiene 6 trabajos, que abordan el persistente conflicto por la tenencia de la tierra y la producción de soya y maíz transgénico y la asociada acumulación del capital por despojo que caracteriza la agricultura transgénica en México, pero también formas de resistencia como la denuncia de contaminación transgénica en la Sierra Juárez de Oaxaca y las instituciones, actores y gestión en la Reserva de la Biósfera El Triunfo en la Sierra Madre de Chiapas. La segunda sección: Territorio: Explotación y envenenamiento, está compuesta por 5 trabajos que hacen referencia a los conflictos socioambientales derivados de la minería en manos de empresas nacionales y extranjeras omisas y gobiernos cómplices de las consecuencias depredadoras que generan en territorios campesinos e indígenas, debido a su asociación con el narcotráfico y por la contaminación del agua y la tierra que provocan, además de las consecuencias perversas en la salud humana y el entorno natural en diversas regiones del país. En la tercera y última sección, Agua: contaminación y escases, los 8 trabajos que la integran, analizan los conflictos socioterritoriales y luchas por la vida, en diversos estados del país. Se trata de investigaciones que estudian movimientos y conflictos sociales actuales en el campo mexicano, como son las luchas por la defensa del territorio y la defensa de la naturaleza, trabajos que abordan especialmente las disputas por el agua, y los problemas asociados del acceso, la escasez y la contaminación, no solo internos sino con empresas y con el Estado mismo que con la aprobación y aplicación de leyes y reglamentos, el despojo a los campesinos de su territorio en el que han trabajado y vivido por generaciones.INSTITUTO DE CIENCIAS AGROPECUARIAS Y RURALES (ICAR), UNIVERSIDAD DE GUADALAJARA, EL COLEGIO DE MICHOACÁN A.C., FACULTAD DE ESTUDIOS SUPERIORES ACATLÁN-UNAM, ECOSUR, CUCOSTA SUR GRANA, ASOCIACIÓN MEXICANA DE ESTUDIOS RURALES A.C

    Dissecting common and unique effects of anti-alpha4beta7 and anti-tumor necrosis factor treatment in ulcerative colitis

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    Background and Aims:Vedolizumab is an anti-α4β7 antibody approved for the treatment of ulcerative colitis [UC]. Although it is assumed that vedolizumab blocks intestinal homing of lymphocytes, its effects on different intestinal cell populations are not fully stablished. In order to establish the unique mechanisms of action of vedolizumab in UC patients, we compared its effects to those induced by anti-tumour necrosis factor [TNF]. Methods:patients with active UC [endoscopic Mayo score >1] starting vedolizumab [n = 33] or anti-TNF [n = 45] and controls [n = 22] were included. Colon biopsies [at weeks 0, 14 and 46] and blood samples [at weeks 0, 2, 6, 14, 30 and 46] were used for cell phenotyping, transcriptional analysis [qPCR], and to measure receptor occupancy. Results:Vedolizumab, in contrast to anti-TNF, significantly reduced the proportion of α4β7+ cells within intestinal T subsets while preserving the percentage of α4β7+ plasma cells. The marked decrease in α4β7 did not change the percentage of colonic αEβ7+ cells [at 46 weeks]. Both vedolizumab and anti-TNF significantly downregulated inflammation-related genes in the colon of responders [Mayo score < 2]. Moreover, both treatments significantly decreased the percentage of intestinal, but not blood, total lymphocytes [T and plasma cells], as well as the proportion of α4β1+ cells within intestinal T lymphocytes. Conclusions:Our data show that while vedolizumab and anti-TNF block two unrelated targets, they induce remarkably similar effects. On the other hand, vedolizumab's unique mechanism of action relies on blocking intestinal trafficking of α4β7 T cells, despite effectively binding to B and plasma cells that express α4β7

    Chromosomal bands affected by acute oil exposure and DNA repair errors

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    Background: In a previous study, we showed that individuals who had participated in oil clean-up tasks after the wreckage of the Prestige presented an increase of structural chromosomal alterations two years after the acute exposure had occurred. Other studies have also reported the presence of DNA damage during acute oil exposure, but little is known about the long term persistence of chromosomal alterations, which can be considered as a marker of cancer risk. Objectives: We analyzed whether the breakpoints involved in chromosomal damage can help to assess the risk of cancer as well as to investigate their possible association with DNA repair efficiency. Methods: Cytogenetic analyses were carried out on the same individuals of our previous study and DNA repair errors were assessed in cultures with aphidicolin. Results: Three chromosomal bands, 2q21, 3q27 and 5q31, were most affected by acute oil exposure. The dysfunction in DNA repair mechanisms, expressed as chromosomal damage, was significantly higher in exposed-oil participants than in those not exposed (p= 0.016). Conclusion: The present study shows that breaks in 2q21, 3q27 and 5q31 chromosomal bands, which are commonly involved in hematological cancer, could be considered useful genotoxic oil biomarkers. Moreover, breakages in these bands could induce chromosomal instability, which can explain the increased risk of cancer (leukemia and lymphomas) reported in chronically benzene-exposed individuals. In addition, it has been determined that the individuals who participated in clean-up of the oil spill presented an alteration of their DNA repair mechanisms two years after exposure.For this study was provided by grants from the Health Institute Carlos III FEDER/ERDF (PI03/1685), Sociedad Española de Neumología y Cirugía Torácica (SEPAR), Comissionat per a Universitats i Recerca from Generalitat de Catalunya (SGR09-1107), Centro de Investigación en Red de Enfermedades Respiratorias and Universidad Autónoma de Barcelona (PS-456-01/08)
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