1,105 research outputs found

    A Signal Detection Model for the Analysis of Continuous Response Gradients and an Application to Confidence Rating Data

    Get PDF
    see attache

    Powerful obscured AGN among X-ray hard, optically-dim serendipitous Chandra sources

    Full text link
    We present a small sample of Chandra X-ray sources selected from the fields of ACIS observations which probe fluxes around the break in the hard band source counts. The targets of these fields include 9 nearby galaxy clusters, 1 distant cluster and 2 powerful radio galaxy fields. The follow-up of this serendipitous sample was biased towards X-ray hard and optically-dim sources mostly not seen on the Digitized Sky Survey; for these, we present X-ray fluxes, optical and near-infrared photometry leading to 51 photometric redshifts in all and 18 independently measured spectroscopic redshifts. Few sources are associated with the target fields themselves. Fifty-six of 58 sources imaged in the K-band are detected at K<~20 with K_median=18, and of these, 38 have hard X-ray count ratios and 24 of these are significantly hard with most of the counts emerging about 2 keV. We find that almost all are AGN hosted in massive early-type host galaxies with a photometric redshift distribution peaking at z~1. Two type 2 quasars with intrinsic X-ray luminosity L>~10^{45} erg/s, Fe K_alpha emission lines and absorbing column density nH>10^{23} cm^{-2} -- and nH>~10^{24} cm^{-2} in one case -- are discussed in detail; the sample contains at least 12 potential type 2 quasars in all. We discuss various detection strategies for type 2 quasars and calculate their inferred space density. This combines and extends a number of results from subsamples already published by us.Comment: MNRAS accepted; 30 pages, 12 figures, 8 tables; Figures of all targets and other information available in the electronic journal and temporarily at http://www-xray.ast.cam.ac.uk/~pg/xrbsources/imsp

    Comparative phylogeography of two codistributed species of the genus Herichthys (Actinopterygii: Cichliformes: Cichlidae) in northeastern Mexico

    Get PDF
    Phylogeographic patterns of freshwater fishes in coastal regions are highly susceptible to eustatic sea level changes associated with Pleistocene glaciations. In this context, the Plain Coastal Gulf in northeastern Mexico represents an ideal study area due to its low elevation. Herein, we compare the phylogeographic structures of two cichlid species of the genus Herichthys Baird et Girard, 1854 widely distributed in the Pánuco–Tamesí system in northeastern Mexico using two mitochondrial markers. The species studied were: Herichthys carpintis (Jordan et Snyder, 1899) and Herichthys pantostictus (Taylor et Miller, 1983). We estimate their genetic diversity, gene flow, and demographic history and perform biogeographic reconstructions using a Bayesian computation approach and environmental niche modeling. The biogeographic reconstruction suggests a different history for each species. Environmental niche modeling indicates that both species experienced a demographic expansion during the Pleistocene but responded differently to Pleistocene climatic changes. In summary, their current sympatric distribution could be the outcome of contemporary and not historical processes reflecting a pseudo-incongruent pattern

    Large-scale movements of common bottlenose dolphins in the Atlantic : dolphins with an international courtyard

    Get PDF
    Wide-ranging connectivity patterns of common bottlenose dolphins (Tursiops truncatus) are generally poorly known worldwide and more so within the oceanic archipelagos of Macaronesia in the North East (NE) Atlantic. This study aimed to identify long-range movements between the archipelagos of Macaronesia that lie between 500 and 1,500 km apart, and between Madeira archipelago and the Portuguese continental shelf, through the compilation and comparison of bottlenose dolphin's photo-identification catalogues from different regions: one from Madeira (n = 363 individuals), two from different areas in the Azores (n = 495 and 176), and four from different islands of the Canary Islands (n = 182, 110, 142 and 281), summing up 1791 photographs. An additional comparison was made between the Madeira catalogue and one catalogue from Sagres, on the southwest tip of the Iberian Peninsula (n = 359). Results showed 26 individual matches, mostly between Madeira and the Canary Islands (n = 23), and between Azores and Madeira (n = 3). No matches were found between the Canary Islands and the Azores, nor between Madeira and Sagres. There were no individuals identified in all three archipelagos. The minimum time recorded between sightings in two different archipelagos (≈ 460 km apart) was 62 days. Association patterns revealed that the individuals moving between archipelagos were connected to resident, migrant and transient individuals in Madeira. The higher number of individuals that were re-sighted between Madeira and the Canary Islands can be explained by the relative proximity of these two archipelagos. This study shows the first inter-archipelago movements of bottlenose dolphins in the Macaronesia region, emphasizing the high mobility of this species and supporting the high gene flow described for oceanic dolphins inhabiting the North Atlantic. The dynamics of these long-range movements strongly denotes the need to review marine protected areas established for this species in each archipelago, calling for joint resolutions from three autonomous regions belonging to two EU countries.Partnership Program (US) and project ‘‘Cetáceos, Oceanografía y Biodiversidad de las Aguas Profundas de La Palma y El Hierro’’ funded by ‘‘Ministerio de Ciencia e Innovación’’ of the Spanish Government, grant number CETOBAPH-CGL2009-1311218 supported the work in the Canary Island. In Madeira, this study was supported by the Oceanic Observatory of Madeira through the project M1420-01-0142-FEDER-000001 and by the Portuguese Foundation for Science and Technology through the strategic project UID/MAR/04292/2020. Ana Dinis and Filipe Alves have grants funded by ARDITI— Madeira’s Regional Agency for the Development of Research, Technology and Innovation, throughout the project M1420-09- 5369- FSE- 000002, and Annalisa Sambolino is supported by the Portuguese Foundation for Science and Technology through the PhD grant number SFRH/BD/1416092018. In Azores, the MONICET platform is supported by project MEEMO (ACORES-01-0145-FEDER-000079) and Marta Tobena is supported by a PhD grant (M31a/F/0722015). There was no additional external funding received for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.info:eu-repo/semantics/publishedVersio

    The Circumgalactic Medium in Massive Halos

    Full text link
    This chapter presents a review of the current state of knowledge on the cool (T ~ 1e4 K) halo gas content around massive galaxies at z ~ 0.2-2. Over the last decade, significant progress has been made in characterizing the cool circumgalactic gas in massive halos of Mh ~ 1e12-1e14 Msun at intermediate redshifts using absorption spectroscopy. Systematic studies of halo gas around massive galaxies beyond the nearby universe are made possible by large spectroscopic samples of galaxies and quasars in public archives. In addition to accurate and precise constraints for the incidence of cool gas in massive halos, detailed characterizations of gas kinematics and chemical compositions around massive quiescent galaxies at z ~ 0.5 have also been obtained. Combining all available measurements shows that infalling clouds from external sources are likely the primary source of cool gas detected at d >~ 100 kpc from massive quiescent galaxies. The origin of the gas closer in is currently less certain, but SNe Ia driven winds appear to contribute significantly to cool gas found at d < 100 kpc. In contrast, cool gas observed at d <~ 200 kpc from luminous quasars appears to be intimately connected to quasar activities on parsec scales. The observed strong correlation between cool gas covering fraction in quasar host halos and quasar bolometric luminosity remains a puzzle. Combining absorption-line studies with spatially-resolved emission measurements of both gas and galaxies is the necessary next step to address remaining questions.Comment: 29 pages, 7 figures, invited review to appear in "Gas Accretion onto Galaxies", Astrophysics and Space Science Library, eds. A. Fox & R. Dave, to be published by Springe

    Sulfated Polysaccharide Extracted from the Green Algae Codium bernabei: Physicochemical Characterization and Antioxidant, Anticoagulant and Antitumor Activity

    Get PDF
    Codium bernabei is a green alga that grows on Chilean coasts. The composition of its structural polysaccharides is still unknown. Hence, the aim of this work is to isolate and characterize the hot water extracted polysaccharide fractions. For this purpose, the water extracts were further precipitated in alcohol (TPs) and acid media (APs), respectively. Both fractions were characterized using different physicochemical techniques such as GC-MS, GPC, FTIR, TGA, and SEM. It is confirmed that the extracted fractions are mainly made of sulfated galactan unit, with a degree of sulfation of 19.3% (TPs) and 17.4% (ATs) and a protein content of 3.5% in APs and 15.6% in TPs. Other neutral sugars such as xylose, glucose, galactose, fucose, mannose, and arabinose were found in a molar ratio (0.05:0.6:1.0:0.02:0.14:0.11) for TPs and (0.05:0.31:1.0:0.03:0.1:0.13) for ATs. The molecular weight of the polysaccharide samples was lower than 20 kDa. Both polysaccharides were thermally stable (Tonset > 190 °C) and showed antioxidant activity according to the ABTS•+ and DPPH tests, where TPs fractions had higher scavenging activity (35%) compared to the APs fractions. The PT and APTTS assays were used to measure the anticoagulant activity of the polysaccharide fractions. In general, the PT activity of the TPs and APs was not different from normal plasma values. The exception was the TPs treatment at 1000 µg mL−1 concentration. The APTTS test revealed that clotting time for both polysaccharides was prolonged regarding normal values at 1000 µg mL−1. Finally, the antitumor test in colorectal carcinoma (HTC-116) cell line, breast cancer (MCF-7) and human leukemia (HL-60) cell lines showed the cytotoxic effect of TPs and APs. Those results suggest the potential biotechnological application of sulfate galactan polysaccharides isolated from a Chilean marine resource

    Expedición cangrejo negro : informe técnico

    Get PDF
    El huracán Iota que pasó por las islas de providencia y Santa catalina el 16 de noviembre de 2020 produjo efectos importantes en los ecosistemas de las islas, así como en los servicios que estos ofrecen a las comunidades locales y que dan lugar a un atractivo turístico que se constituye en la principal actividad económica de las islas. Este trabajo corresponde a un esfuerzo por identificar áreas importantes para la prestación de los servicios ecosistémicos (SSE) en especial aquellas que pudieron haber resultado especialmente afectadas como resultado de Iota, para tal fin se aborda un enfoque basado en el análisis de datos geoespaciales, apoyado por la consulta de información secundaria. La revisión de la información secundaria permitió identificar SSE relevantes en la isla fundamentalmente relacionados con protección frente a desastres naturales y servicios de provisión y regulación hídrica, mientras que los análisis espaciales permitieron identificar cuencas importantes frente a estos servicios como Freshwater, Bailey, Bowden y Santa Catalina Sur, los análisis de imágenes satelitales por su parte permitieron identificar áreas afectadas por la pérdida de vegetación y acumulación de biomasa.Bogot

    Worldwide trends in underweight and obesity from 1990 to 2022: a pooled analysis of 3663 population-representative studies with 222 million children, adolescents, and adults

    Get PDF
    Background Underweight and obesity are associated with adverse health outcomes throughout the life course. We estimated the individual and combined prevalence of underweight or thinness and obesity, and their changes, from 1990 to 2022 for adults and school-aged children and adolescents in 200 countries and territories. Methods We used data from 3663 population-based studies with 222 million participants that measured height and weight in representative samples of the general population. We used a Bayesian hierarchical model to estimate trends in the prevalence of different BMI categories, separately for adults (age ≥20 years) and school-aged children and adolescents (age 5–19 years), from 1990 to 2022 for 200 countries and territories. For adults, we report the individual and combined prevalence of underweight (BMI &lt;18·5 kg/m2) and obesity (BMI ≥30 kg/m2). For school&#x2;aged children and adolescents, we report thinness (BMI &lt;2 SD below the median of the WHO growth reference) and obesity (BMI &gt;2 SD above the median). Findings From 1990 to 2022, the combined prevalence of underweight and obesity in adults decreased in 11 countries (6%) for women and 17 (9%) for men with a posterior probability of at least 0·80 that the observed changes were true decreases. The combined prevalence increased in 162 countries (81%) for women and 140 countries (70%) for men with a posterior probability of at least 0·80. In 2022, the combined prevalence of underweight and obesity was highest in island nations in the Caribbean and Polynesia and Micronesia, and countries in the Middle East and north Africa. Obesity prevalence was higher than underweight with posterior probability of at least 0·80 in 177 countries (89%) for women and 145 (73%) for men in 2022, whereas the converse was true in 16 countries (8%) for women, and 39 (20%) for men. From 1990 to 2022, the combined prevalence of thinness and obesity decreased among girls in five countries (3%) and among boys in 15 countries (8%) with a posterior probability of at least 0·80, and increased among girls in 140 countries (70%) and boys in 137 countries (69%) with a posterior probability of at least 0·80. The countries with highest combined prevalence of thinness and obesity in school-aged children and adolescents in 2022 were in Polynesia and Micronesia and the Caribbean for both sexes, and Chile and Qatar for boys. Combined prevalence was also high in some countries in south Asia, such as India and Pakistan, where thinness remained prevalent despite having declined. In 2022, obesity in school-aged children and adolescents was more prevalent than thinness with a posterior probability of at least 0·80 among girls in 133 countries (67%) and boys in 125 countries (63%), whereas the converse was true in 35 countries (18%) and 42 countries (21%), respectively. In almost all countries for both adults and school-aged children and adolescents, the increases in double burden were driven by increases in obesity, and decreases in double burden by declining underweight or thinness. Interpretation The combined burden of underweight and obesity has increased in most countries, driven by an increase in obesity, while underweight and thinness remain prevalent in south Asia and parts of Africa. A healthy nutrition transition that enhances access to nutritious foods is needed to address the remaining burden of underweight while curbing and reversing the increase in obesit
    corecore