3,385 research outputs found

    Molecular Gas, Dust and Star Formation in Galaxies: II. Dust properties and scalings in \sim\ 1600 nearby galaxies

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    We aim to characterize the relationship between dust properties. We also aim to provide equations to estimate accurate dust properties from limited observational datasets. We assemble a sample of 1,630 nearby (z<0.1) galaxies-over a large range of Mstar, SFR - with multi-wavelength observations available from wise, iras, planck and/or SCUBA. The characterization of dust emission comes from SED fitting using Draine & Li dust models, which we parametrize using two components (warm and cold ). The subsample of these galaxies with global measurements of CO and/or HI are used to explore the molecular and/or atomic gas content of the galaxies. The total Lir, Mdust and dust temperature of the cold component (Tc) form a plane that we refer to as the dust plane. A galaxy's sSFR drives its position on the dust plane: starburst galaxies show higher Lir, Mdust and Tc compared to Main Sequence and passive galaxies. Starburst galaxies also show higher specific Mdust (Mdust/Mstar) and specific Mgas (Mgas/Mstar). The Mdust is more closely correlated with the total Mgas (atomic plus molecular) than with the individual components. Our multi wavelength data allows us to define several equations to estimate Lir, Mdust and Tc from one or two monochromatic luminosities in the infrared and/or sub-millimeter. We estimate the dust mass and infrared luminosity from a single monochromatic luminosity within the R-J tail of the dust emission, with errors of 0.12 and 0.20dex, respectively. These errors are reduced to 0.05 and 0.10 dex, respectively, if the Tc is used. The Mdust is correlated with the total Mism (Mism \propto Mdust^0.7). For galaxies with Mstar 8.5<log(Mstar/Msun) < 11.9, the conversion factor \alpha_850mum shows a large scatter (rms=0.29dex). The SF mode of a galaxy shows a correlation with both the Mgass and Mdust: high Mdust/Mstar galaxies are gas-rich and show the highest SFRs.Comment: 24 pages, 28 figures, 6 tables, Accepted for publication in A&

    Age Determination of Fifteen Old to Intermediate-Age Small Magellanic Cloud Star Clusters

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    We present CMDs in the V and I bands for fifteen star clusters in the Small Magellanic Cloud (SMC) based on data taken with the Very Large Telescope (VLT, Chile). We selected these clusters from our previous work, wherein we derived cluster radial velocities and metallicities from Calcium II infrared triplet (CaT) spectra also taken with the VLT. We discovered that the ages of six of our clusters have been appreciably underestimated by previous studies, which used comparatively small telescopes, graphically illustrating the need for large apertures to obtain reliable ages of old and intermediate-age SMC star clusters. In particular, three of these clusters, L4, L6 and L110, turn out to be amongst the oldest SMC clusters known, with ages of 7.9 +- 1.1, 8.7 +- 1.2 and 7.6 +- 1.0 Gyr, respectively, helping to fill a possible "SMC cluster age gap" (Glatt et al. 2008). Using the present ages and metallicities from Parisi et al. (2009), we analyze the age distribution, age gradient and age metallicity relation (AMR) of a sample of SMC clusters measured homogeneously. There is a suggestion of bimodality in the age distribution but it does not show a constant slope for the first 4 Gyr (Piatti 2011), and we find no evidence for an age gradient. Due to the improved ages of our cluster sample, we find that our AMR is now better represented in the intermediate/old period than that we derived in Parisi et al. (2009), where we simply took ages available in the literature. Additionally, clusters younger than aprox. 4 Gyr now show better agreement with the bursting model, but we confirm that this model is not a good representation of the AMR during the intermediate-age/old period. A more complicated model is needed to explain the SMC chemical evolution in that period.Comment: 76 pages, 32 figures. Accepted for publication in A

    Assessing the Impact of Mutations and Horizontal Gene Transfer on the AMR Control: A Mathematical Model

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    Antimicrobial resistance (AMR) poses a significant threat to public health by increasing mortality, extending hospital stays, and increasing healthcare costs. It affects people of all ages and affects health services, veterinary medicine, and agriculture, making it a pressing global issue. Mathematical models are required to predict the behaviour of AMR and to develop control measures to eliminate resistant bacteria or reduce their prevalence. This study presents a simple deterministic mathematical model in which sensitive and resistant bacteria interact in the environment, and mobile genetic elements (MGEs) are functions that depend on resistant bacteria. We analyze the qualitative properties of the model and propose an optimal control problem in which avoiding mutations and horizontal gene transfer (HGT) are the primary control strategies. We also provide a case study of the resistance and multidrug resistance (MDR) percentages of Escherichia coli to gentamicin and amoxicillin in some European countries using data from the European Antimicrobial Resistance Surveillance Network (EARS-Net). Our theoretical results and numerical experiments indicate that controlling the spread of resistance in southern European regions through the supply of amoxicillin is challenging. However, the host immune system is also critical for controlling AMR.Comment: 1

    A CCD Search for Variable Stars in the Open Cluster NGC 6611

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    We present the results of the UBVICUBVI_C variability survey in the young open cluster NGC 6611 based on observations obtained during 34 nights spanning one year. In total, we found 95 variable stars. Most of these stars are classified as periodic and irregular pre-main sequence (PMS) stars. The analysis of the JHKSJHK_S 2MASS photometry and four-colour IRAC photometry revealed 165 Class II young stellar sources, 20 of which are irregular variables and one is an eclipsing binary. These classifications, complemented by JHKJHK UKIDSS photometry and riHαriH\alpha VPHAS photometry, were used to identify 24 candidates for classical T Tauri stars and 30 weak-lined T Tauri stars. In addition to the PMS variables, we discovered eight δ\delta Scuti candidates. None of these were previously known. Furthermore, we detected 17 eclipsing binaries where two were previously known. Based on the proper motions provided by the Gaia EDR3 catalogue, we calculated the cluster membership probabilities for 91 variable stars. For 61 variables, a probability higher than 80% was determined, which makes them cluster members. Only 25 variables with a probability less than 20% were regarded to be non-members.Comment: 30 pages, 31 figure

    GOODS-HerschelHerschel: identification of the individual galaxies responsible for the 80-290μ\mum cosmic infrared background

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    We propose a new method of pushing HerschelHerschel to its faintest detection limits using universal trends in the redshift evolution of the far infrared over 24μ\mum colours in the well-sampled GOODS-North field. An extension to other fields with less multi-wavelength information is presented. This method is applied here to raise the contribution of individually detected HerschelHerschel sources to the cosmic infrared background (CIRB) by a factor 5 close to its peak at 250μ\mum and more than 3 in the 350μ\mum and 500μ\mum bands. We produce realistic mock HerschelHerschel images of the deep PACS and SPIRE images of the GOODS-North field from the GOODS-HerschelHerschel Key Program and use them to quantify the confusion noise at the position of individual sources, i.e., estimate a "local confusion noise". Two methods are used to identify sources with reliable photometric accuracy extracted using 24μ\mum prior positions. The clean index (CI), previously defined but validated here with simulations, which measures the presence of bright 24μ\mum neighbours and the photometric accuracy index (PAI) directly extracted from the mock HerschelHerschel images. After correction for completeness, thanks to our mock HerschelHerschel images, individually detected sources make up as much as 54% and 60% of the CIRB in the PACS bands down to 1.1 mJy at 100μ\mum and 2.2 mJy at 160μ\mum and 55, 33, and 13% of the CIRB in the SPIRE bands down to 2.5, 5, and 9 mJy at 250μ\mum, 350μ\mum, and 500μ\mum, respectively. The latter depths improve the detection limits of HerschelHerschel by factors of 5 at 250μ\mum, and 3 at 350μ\mum and 500μ\mum as compared to the standard confusion limit. Interestingly, the dominant contributors to the CIRB in all HerschelHerschel bands appear to be distant siblings of the Milky Way (zz\sim0.96 for λ\lambda<<300μ\mum) with a stellar mass of MM_{\star}\sim9×\times1010^{10}M_{\odot}.Comment: 22 pages, 16 figures. Accepted for publication by Astronomy and Astrophysic

    A simulation study of diagnostics for bias in non-probability samples

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    A non-probability sampling mechanism is likely to bias estimates of parameters with respect to a target population of interest. This bias poses a unique challenge when selection is \u27non-ignorable\u27, i.e. dependent upon the unobserved outcome of interest, since it is then undetectable and thus cannot be ameliorated. We extend a simulation study by Nishimura et al. [International Statistical Review, 84, 43--62 (2016)], adding a recently published statistic, the so-called \u27standardized measure of unadjusted bias\u27, which explicitly quantifies the extent of bias under the assumption that a specified amount of non-ignorable selection exists. Our findings suggest that this new sensitivity diagnostic is considerably correlated with, and more predictive of, the true, unknown extent of selection bias than other diagnostics, even when the underlying assumed level of non-ignorability is incorrect

    Optical and Infrared Photometry of the Unusual Type Ia Supernova 2000cx

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    We present optical and infrared photometry of the unusual Type Ia supernova 2000cx. With the data of Li et al. (2001) and Jha (2002), this comprises the largest dataset ever assembled for a Type Ia SN, more than 600 points in UBVRIJHK. We confirm the finding of Li et al. regarding the unusually blue B-V colors as SN 2000cx entered the nebular phase. Its I-band secondary hump was extremely weak given its B-band decline rate. The V minus near infrared colors likewise do not match loci based on other slowly declining Type Ia SNe, though V-K is the least ``abnormal''. In several ways SN 2000cx resembles other slow decliners, given its B-band decline rate (Delta m_15(B) = 0.93), the appearance of Fe III lines and weakness of Si II in its pre-maximum spectrum, the V-K colors and post-maximum V-H colors. If the distance modulus derived from Surface Brightness Fluctuations of the host galaxy is correct, we find that the rate of light increase prior to maximum, the characteristics of the bolometric light curve, and the implied absolute magnitude at maximum are all consistent with a sub-luminous object with Delta m_15(B) ~ 1.6-1.7 having a higher than normal kinetic energy.Comment: 46 pages, 17 figures, to be published in Publications of the Astronomical Society of the Pacifi

    VALES: IV. Exploring the transition of star formation efficiencies between normal and starburst galaxies using APEX/SEPIA Band-5 and ALMA at low redshift

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    In this work we present new APEX/SEPIA Band-5 observations targeting the CO (J=2-1J=2\text{-}1) emission line of 24 Herschel-detected galaxies at z=0.10.2z=0.1-0.2. Combining this sample {with} our recent new Valpara\'iso ALMA Line Emission Survey (VALES), we investigate the star formation efficiencies (SFEs = SFR/MH2M_{\rm H_{2}}) of galaxies at low redshift. We find the SFE of our sample bridges the gap between normal star-forming galaxies and Ultra-Luminous Infrared Galaxies (ULIRGs), which are thought to be triggered by different star formation modes. Considering the SFE\rm SFE' as the SFR and the LCOL'_{\rm CO} ratio, our data show a continuous and smooth increment as a function of infrared luminosity (or star formation rate) with a scatter about 0.5 dex, instead of a steep jump with a bimodal behaviour. This result is due to the use of a sample with a much larger range of sSFR/sSFRms_{\rm ms} using LIRGs, with luminosities covering the range between normal and ULIRGs. We conclude that the main parameters controlling the scatter of the SFE in star-forming galaxies are the systematic uncertainty of the αCO\alpha_{\rm CO} conversion factor, the gas fraction and physical size.Comment: 9pages, 7 figures, 1 table, accepted for publication in MNRA

    Effect of dietary free fatty acid content on growth and hepatic morphology in sole (Solea Senegalensis) juveniles

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    Utilization in aquaculture of unusual meals with unbalanced lipid content or inadequate previous treatment may result in harmful state for fish. This research studied the effects caused by different dietary free fatty acid (FFA) content on growth performance and hepatic morphology in liver in sole juveniles. Results revealed an inverse relationship between dietary FFA content and ability of fish to grow. Moreover, hepatic morphology analysis indicated an overall healthier status in hepatocytes of fish fed with low dietary FFA content. Dietary fatty acids must be esterified to glycerols seem an absolutely necessary requisite in sole, allowing a proper energy storing and its latter mobilisation to gain biomass.This work was supported by Interreg Project 0251_ECOAQUA_5_E, financed by the EDRF (European Regional Development Fund). www.juntadeandalucia.es/agriculturaypesca/ifapa/ecoaquaLa utilizaci&oacute;n en la acuicultura de dietas inusuales con contenido lip&iacute;dico desequilibrados o tratamientos previos inadecuados puede resultar nocivo para los peces. Esta investigaci&oacute;n estudi&oacute; los efectos causados por distintas dietas con diferente contenido en &aacute;cidos grasos libres (FFA) en el crecimiento y la morfolog&iacute;a hep&aacute;tica en juveniles de lenguado. Los resultados revelaron una relaci&oacute;n inversa entre el contenido de FFA en la dieta y la capacidad de los peces para crecer. Por otra parte, el an&aacute;lisis de la morfolog&iacute;a hep&aacute;tica indic&oacute; un estado m&aacute;s saludable en los hepatocitos de los peces alimentados con una dieta baja en FFA . La esterificaci&oacute;n con glicerina de &aacute;cidos grasos es un requisito indispensable en lenguados, lo que permite un adecuado almacenamiento de energ&iacute;a y su posterior movilizaci&oacute;n para ganar biomasa.Este trabajo fue apoyado por el proyecto Interreg 0251_ECOAQUA_5_E , financiado por el FEDER (Fondo Europeo de Desarrollo Regional). www.juntadeandalucia.es/agriculturaypesca/ifapa/ecoaqua.</p

    Indices of nonâ ignorable selection bias for proportions estimated from nonâ probability samples

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151805/1/rssc12371_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151805/2/rssc12371.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151805/3/rssc12371-sup-0001-SupInfo.pd
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