150 research outputs found

    What triggers galaxy transformations? The environments of post-starburst galaxies

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    (abridged) There are good observational reasons to believe that the progenitors of red galaxies have undergone starbursts, followed by a post-starburst phase. We investigate the environments of post-starburst galaxies by measuring \textsl{(1)} number densities in 8h1Mpc8 h^{-1} \mathrm{Mpc} radius comoving spheres, \textsl{(2)} transverse distances to nearest Virgo-like galaxy clusters, and \textsl{(3)} transverse distances to nearest luminous-galaxy neighbors. We compare the post-starburst galaxies to currently star-forming galaxies identified solely by A-star excess or \Halpha emission. We find that post-starburst galaxies are in the same kinds of environments as star-forming galaxies; this is our ``null hypothesis''. More importantly, we find that at each value of the A-star excess, the star-forming and post-starburst galaxies lie in very similar distributions of environment. The only deviations from our null hypothesis are barely significant: a slight deficit of post-starburst galaxies (relative to the star-forming population) in very low-density regions, a small excess inside the virial radii of clusters, and a slight excess with nearby neighbors. None of these effects is strong enough to make the post-starburst galaxies a high-density phenomenon, or to argue that the starburst events are primarily triggered by external tidal impulses (e.g., from close passages of massive galaxies). The small excess inside cluster virial radii suggests that some post-starbursts are triggered by interactions with the intracluster medium, but this represents a very small fraction of all post-starburst galaxies.Comment: ApJ in pres

    Selection and photometric properties of K+A galaxies

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    Two different simple measurements of galaxy star formation rate with different timescales are compared empirically on 156,395156,395 fiber spectra of galaxies with r<17.77r<17.77 mag taken from the Sloan Digital Sky Survey in the redshift range 0.05<z<0.200.05<z<0.20: a ratio \Aamp / \Kamp found by fitting a linear sum of an average old stellar poplulation spectrum (\Kamp) and average A-star spectrum (\Aamp) to the galaxy spectrum, and the equivalent width (EW) of the \Halpha emission line. The two measures are strongly correlated, but there is a small clearly separated population of outliers from the median correlation that display excess \Aamp /\Kamp relative to \Halpha EW. These ``K+A'' (or ``E+A'') galaxies must have dramatically decreased their star-formation rates over the last 1\sim 1 Gyr. The K+A luminosity distribution is very similar to that of the total galaxy population. The K+A population appears to be bulge-dominated, but bluer and higher surface-brightness than normal bulge-dominated galaxies; it appears that K+A galaxies will fade with time into normal bulge-dominated galaxies. The inferred rate density for K+A galaxy formation is 104h3Mpc3Gyr1\sim 10^{-4} h^3 Mpc^{-3} Gyr^{-1} at redshift z0.1z\sim 0.1. These events are taking place in the field; K+A galaxies don't primarily lie in the high-density environments or clusters typical of bulge-dominated populations.Comment: submitted to Ap

    A framework for security assessment of android mobile banking applications

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    ABSTRACT: Mobile banking applications make users' daily lives easier by allowing them to access banking services, such as balance inquiries and bill payments, anytime and anywhere. Since these applications manage very sensitive financial data, special attention must be paid to data security. Several works in the literature assess the security of mobile banking applications. However, we observe the lack of a widely adopted framework among researchers for assessing the security of mobile banking applications. In this paper, we propose a framework consisting of twenty-six criteria for assessing the security of Android mobile banking applications. These criteria are divided into five categories: mobile device security, data in transit, data storage, cryptographic misuse, and others. Subsequently, we evaluate the proposed framework based on predefined requirements. These requirements are no redundancy, no ambiguity, and comprehensiveness. As a case study, we assess the security of the Android mobile banking applications of seven major Canadian banks. The results show that data in transit is adequately protected by these applications

    Predicting bee community responses to land-use changes: Effects of geographic and taxonomic biases

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    Land-use change and intensification threaten bee populations worldwide, imperilling pollination services. Global models are needed to better characterise, project, and mitigate bees' responses to these human impacts. The available data are, however, geographically and taxonomically unrepresentative; most data are from North America and Western Europe, overrepresenting bumblebees and raising concerns that model results may not be generalizable to other regions and taxa. To assess whether the geographic and taxonomic biases of data could undermine effectiveness of models for conservation policy, we have collated from the published literature a global dataset of bee diversity at sites facing land-use change and intensification, and assess whether bee responses to these pressures vary across 11 regions (Western, Northern, Eastern and Southern Europe; North, Central and South America; Australia and New Zealand; South East Asia; Middle and Southern Africa) and between bumblebees and other bees. Our analyses highlight strong regionally-based responses of total abundance, species richness and Simpson's diversity to land use, caused by variation in the sensitivity of species and potentially in the nature of threats. These results suggest that global extrapolation of models based on geographically and taxonomically restricted data may underestimate the true uncertainty, increasing the risk of ecological surprises

    Anomalously low PAH emission from low-luminosity galaxies

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    The Spitzer Space Telescope First Look Survey Infrared Array Camera (IRAC) near and mid-infrared imaging data partially overlaps the Sloan Digital Sky Survey (SDSS), with 313 visually selected (r<17.6 mag) SDSS Main Sample galaxies in the overlap region. The 3.5 and 7.8 um properties of the galaxies are investigated in the context of their visual properties, where the IRAC [3.5] magnitude primarily measures starlight, and the [7.8] magnitude primarily measures PAH emission from the interstellar medium. As expected, we find a strong inverse correlation between [3.5]-[7.8] and visual color; galaxies red in visual colors (`red galaxies') tend to show very little dust and molecular emission (low `PAH-to-star' ratios), and galaxies blue in visual colors (`blue galaxies,' ie, star-forming galaxies) tend to show large PAH-to-star ratios. Red galaxies with high PAH-to-star ratios tend to be edge-on disks reddened by dust lanes. Simple, visually inferred attenuation corrections bring the visual colors of these galaxies in line with those of face-on disks; ie, PAH emission is closely related to attenuation-corrected, optically inferred star-formation rates. Blue galaxies with anomalously low PAH-to-star ratios are all low-luminosity star-forming galaxies. There is some weak evidence in this sample that the deficiency in PAH emission for these low-luminosity galaxies may be related to emission-line metallicity.Comment: submitted to ApJ. Because of some obscure arXiv bug, the RGB figure may appear correctly only in the PDF versio

    Effect of aliskiren on post-discharge outcomes among diabetic and non-diabetic patients hospitalized for heart failure: insights from the ASTRONAUT trial

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    Aims The objective of the Aliskiren Trial on Acute Heart Failure Outcomes (ASTRONAUT) was to determine whether aliskiren, a direct renin inhibitor, would improve post-discharge outcomes in patients with hospitalization for heart failure (HHF) with reduced ejection fraction. Pre-specified subgroup analyses suggested potential heterogeneity in post-discharge outcomes with aliskiren in patients with and without baseline diabetes mellitus (DM). Methods and results ASTRONAUT included 953 patients without DM (aliskiren 489; placebo 464) and 662 patients with DM (aliskiren 319; placebo 343) (as reported by study investigators). Study endpoints included the first occurrence of cardiovascular death or HHF within 6 and 12 months, all-cause death within 6 and 12 months, and change from baseline in N-terminal pro-B-type natriuretic peptide (NT-proBNP) at 1, 6, and 12 months. Data regarding risk of hyperkalaemia, renal impairment, and hypotension, and changes in additional serum biomarkers were collected. The effect of aliskiren on cardiovascular death or HHF within 6 months (primary endpoint) did not significantly differ by baseline DM status (P = 0.08 for interaction), but reached statistical significance at 12 months (non-DM: HR: 0.80, 95% CI: 0.64-0.99; DM: HR: 1.16, 95% CI: 0.91-1.47; P = 0.03 for interaction). Risk of 12-month all-cause death with aliskiren significantly differed by the presence of baseline DM (non-DM: HR: 0.69, 95% CI: 0.50-0.94; DM: HR: 1.64, 95% CI: 1.15-2.33; P < 0.01 for interaction). Among non-diabetics, aliskiren significantly reduced NT-proBNP through 6 months and plasma troponin I and aldosterone through 12 months, as compared to placebo. Among diabetic patients, aliskiren reduced plasma troponin I and aldosterone relative to placebo through 1 month only. There was a trend towards differing risk of post-baseline potassium ≥6 mmol/L with aliskiren by underlying DM status (non-DM: HR: 1.17, 95% CI: 0.71-1.93; DM: HR: 2.39, 95% CI: 1.30-4.42; P = 0.07 for interaction). Conclusion This pre-specified subgroup analysis from the ASTRONAUT trial generates the hypothesis that the addition of aliskiren to standard HHF therapy in non-diabetic patients is generally well-tolerated and improves post-discharge outcomes and biomarker profiles. In contrast, diabetic patients receiving aliskiren appear to have worse post-discharge outcomes. Future prospective investigations are needed to confirm potential benefits of renin inhibition in a large cohort of HHF patients without D

    Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

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    A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

    Conservación de pechugas de pollo con aceite esencial de orégano mexicano//Conservation of chicken breasts with mexican oregano essential

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    Pechugas de pollo se marinaron sin y con aceite de orégano (AO) para evaluar su calidad durante 14 días a 4 °C. Los tratamientos fueron T1 = pechuga marinada sin AO, T2 = pechuga marinada con 2000 mg/kg AO y T3 = pechuga marinada con 4000 mg/kg AO. Las pechugas tratadas con AO presentaron los valores de pH más altos y bajos después de 1 y 7 días de almacenamiento, respectivamente. El T2 causó los valores más altos (p &lt; 0.05) en luminosidad y el T3 la mayor (p &lt; 0.05) pigmentación amarilla. El contenido de proteína presentó su valor máximo (p &lt; 0.05) a los 14 días. Los tratamientos T1, T2 y T3 a los 14 días causaron los valores más altos (p &lt; 0.05) de capacidad antioxidante, mesófilos, psicrótrofos y bacterias ácido lácticas. Estos tratamientos presentaron la menor (p &lt; 0.05) carga de hongos y levaduras. La textura de las pechugas presentó los valores más bajos (p &lt; 0.05) a los 14 días. Los tratamientos T2 y T3 mejoraron (p &lt; 0.05) la aceptabilidad del olor global y olor a orégano a los 7 y 14 días, mientras que la dureza y aceptabilidad causada por el T2 fueron mejores (p &lt; 0.05) a los 14 días. El AO puede ser usado a dosis de 2000 y 4000 mg/kg en el marinado de pechugas para conservar sus propiedades fisicoquímicas, contenido nutrimental, textura y aceptabilidad.ABSTRACTChicken breast was marinated with oregano oil (OO) to evaluate its quality over 14 days at 4 °C. Treatments were T1 = marinated chicken breast without OO, T2 = marinated chicken breast + 2000 mg/kg of OO, and T3 = marinated chicken breast + 4000 mg/kg of OO. Chicken breast with OO showed higher and lower (p &lt; 0.05) values of pH after over 1 and 7 days, respectively. T2 had higher (p &lt; 0.05) values on lightness and T3 the highest (p &lt; 0.05) yellowness. Protein content showed the maximum (p &lt; 0.05) value at 14 days. At these days T1, T2 y T3 given higher (p &lt; 0.05) values on antioxidant capacity, mesophilic, psychrophilic and lactic acid bacteria. These treatments obtained the lowest (p &lt; 0.05) fungi and yeast number. Chicken breast texture presented the highest (p &lt; 0.05) values at 14 d. T2 and T3 improved (p &lt; 0.05) the acceptance of global odor and oregano odor at 7 and 14 d, while hardness and overall acceptability for T2 were the best (p &lt; 0.05) at 14 d. Oregano oil can be used (2000 and 4000 g/kg) into chicken breast marinated to preserve their physicochemical traits, nutrient content, texture and acceptability
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