89 research outputs found

    Kinematics and physical conditions of HI in nearby radio sources. The last survey of the old Westerbork Synthesis Radio Telescope

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    We present an analysis of the properties of neutral hydrogen (HI) in 248 nearby (0.0230mJyandforwhichopticalspectroscopyisavailable.TheobservationswerecarriedoutwiththeWesterborkSynthesisRadioTelescopeasthelastlargeprojectbeforetheupgradeofthetelescopewithphasedarrayfeedreceivers(Apertif).Thesamplecoversalmostfourordersofmagnitudeinradiopowerfrom mJy and for which optical spectroscopy is available. The observations were carried out with the Westerbork Synthesis Radio Telescope as the last large project before the upgrade of the telescope with phased array feed receivers (Apertif). The sample covers almost four orders of magnitude in radio power from \log\,P_{\rm 1.4 \,GHz}=22.5WHz W Hz^{-1}and and 26.2WHz W Hz^{-1}.WedetectHIinabsorptionin. We detect HI in absorption in 27\% \pm 5.5\%oftheobjects.ThedistributionandkinematicsoftheabsorbingHIgasappeartodependonradiopower,thepropertiesoftheradiocontinuumemission,andthedustcontentofthesources.AmongthesourceswhereHIisdetected,gaswithkinematicsdeviatingfromregularrotationismorelikelyfoundastheradiopowerincreases.Inthesecases,theHIprofileisoftenasymmetricwithasignificantblue−shiftedcomponent.Thisisparticularlycommonforsourceswith of the objects. The distribution and kinematics of the absorbing HI gas appear to depend on radio power, the properties of the radio continuum emission, and the dust content of the sources. Among the sources where HI is detected, gas with kinematics deviating from regular rotation is more likely found as the radio power increases. In these cases, the HI profile is often asymmetric with a significant blue-shifted component. This is particularly common for sources with \log\,P_{\rm 1.4 \, GHz}>24WHz W Hz^{-1},wheretheradioemissionissmall,possiblybecausetheseradiosourcesareyoung.Thesameisfoundforsourcesthatarebrightinthemid−infrared,i.e.sourcesrichinheateddust.Inthesesources,theHIisoutflowinglikelyundertheeffectoftheinteractionwiththeradioemission.Conversely,indust−poorgalaxies,andinsourceswithextendedradioemission,atallradiopowersweonlydetectHIdistributedinarotatingdisk.StackingexperimentsshowthatinsourcesforwhichwedonotdetectHIinabsorptiondirectly,theHIhasacolumndensitythatislowerthan, where the radio emission is small, possibly because these radio sources are young. The same is found for sources that are bright in the mid-infrared, i.e. sources rich in heated dust. In these sources, the HI is outflowing likely under the effect of the interaction with the radio emission. Conversely, in dust-poor galaxies, and in sources with extended radio emission, at all radio powers we only detect HI distributed in a rotating disk. Stacking experiments show that in sources for which we do not detect HI in absorption directly, the HI has a column density that is lower than 3.5\times 10^{17} (T_{ \rm spin}/c_f)cm cm^{-2}$. We use our results to predict the number and type of HI absorption lines that will be detected by the upcoming surveys of the Square Kilometre Array precursors and pathfinders (Apertif, MeerKAT, and ASKAP).Comment: 22 pages, 15 figures, 4 tables, accepted for publication in A&

    Pay More for a Good Beef Herd Bull.

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    4 p

    Your Cow and Calf Business.

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    16 p

    Deadly news: the downward trend continues in Aboriginal and Torres Strait Islander smoking 2004-2019

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    Smoking is the leading contributor to the burden of disease among Aboriginal and Torres Strait Islander Australians, and one of the largest causes of preventable morbidity and mortality. Reducing exposure to tobacco provides substantial opportunity for improving the health outcomes of Aboriginal and Torres Strait Islander peoples and is reflected in the Framework Convention on Tobacco Control (FCTC). The FCTC acknowledges concern "about the high levels of smoking and other forms of tobacco consumption by indigenous peoples"(FCTC, Preamble). It is important to continue the focus on reducing tobacco use and promoting smoke-]free environments, consequently improving Aboriginal and Torres Strait Islander health outcomes

    Buried hurricane legacies: increased nutrient limitation and decreased root biomass in coastal wetlands

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    Plant identity and cover in coastal wetlands is changing in worldwide, and many subtropical salt marshes dominated by low-stature herbaceous species are becoming woody mangroves. Yet, how changes affect coastal soil biogeochemical processes and belowground biomass before and after storms is uncertain. We experimentally manipulated the percent mangrove cover (Avicennia germinans) in 3 × 3 m cells embedded in 10 plots (24 × 42 m) comprising a gradient of marsh (e.g., Spartina alterniflora, Batis maritima) and mangrove cover in Texas, USA. Hurricane Harvey made direct landfall over our site on 25 August 2017, providing a unique opportunity to test how plant composition mitigates hurricane effects on surface sediment accretion, soil chemistry (carbon, C; nitrogen, N; phosphorus, P; and sulfur, S), and root biomass. Data were collected before (2013 and 2016), one-month after (2017), and one-year after (2018) Hurricane Harvey crossed the area, allowing us to measure stocks before and after the hurricane. The accretion depth was higher in fringe compared with interior cells of plots, more variable in cells dominated by marsh than mangrove, and declined with increasing plot-scale mangrove cover. The concentrations of P and ή34S in storm-driven accreted surface sediments, and the concentrations of N, P, S, and ή34S in underlying soils (0–30 cm), decreased post-hurricane, whereas the C concentrations in both compartments were unchanged. Root biomass in both marsh and mangrove cells was reduced by 80% in 2017 compared with previous dates and remained reduced in 2018. Post-hurricane loss of root biomass in plots correlated with enhanced nutrient limitation. Total sulfide accumulation as indicated by ή34S, increased nutrient limitation, and decreased root biomass of both marshes and mangroves after hurricanes may affect ecosystem function and increase vulnerability in coastal wetlands to subsequent disturbances. Understanding how changes in plant composition in coastal ecosystems affects responses to hurricane disturbances is needed to assess coastal vulnerability

    Comparison between echocardiographic and non-ECG-gated CT measurements in dogs

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    The aim of this study was to compare echocardiographic measurements with non-ECG-gated contrast-enhanced cardiac CT measurements in dogs. Fifty-seven dogs were included in the study. The following echocardiographic parameters were measured: M-mode interventricular septum in diastole and systole, left ventricular internal diameter in diastole and systole, left ventricular free wall in diastole and systole, 2D left atrial maximal diameter, 2D left atrium to aorta ratio in diastole, 2D aortic annulus in systole and 2D pulmonary annulus in diastole and systole. CT measurements were obtained from multiplanar reconstruction images, replicating the imaging planes used for 2D measurements on echocardiography. It was not possible to discriminate between systole and diastole. The results showed moderate Lin's concordance correlation coefficients between the left ventricular internal diameter in systole (0.77), the aortic annuli (0.84) and the pulmonary annuli in diastole (0.78) and systole (0.80). Low coefficients were obtained between the other parameters. Bland-Altman plots for the parameters with highest concordance correlation coefficients were calculated. They suggested equivalence between the measurements of the aortic annuli. Equivalence was not seen between the remaining echocardiographic and CT measurements. Therefore, non-ECG-gated CT is not a reliable way of quantitatively assessing cardiac size

    MIGHTEE-HI: the HI Size-Mass relation over the last billion years

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    We present the observed HI size-mass relation of 204204 galaxies from the MIGHTEE Survey Early Science data. The high sensitivity of MeerKAT allows us to detect galaxies spanning more than 4 orders of magnitude in HI mass, ranging from dwarf galaxies to massive spirals, and including all morphological types. This is the first time the relation has been explored on a blind homogeneous data set which extends over a previously unexplored redshift range of 0<z<0.0840 < z < 0.084, i.e. a period of around one billion years in cosmic time. The sample follows the same tight logarithmic relation derived from previous work, between the diameter (DHID_{\rm HI}) and the mass (MHIM_{\rm HI}) of HI discs. We measure a slope of 0.501±0.0080.501\pm 0.008, an intercept of −3.252−0.074+0.073-3.252^{+0.073}_{-0.074}, and an observed scatter of 0.0570.057 dex. For the first time, we quantify the intrinsic scatter of 0.054±0.0030.054 \pm 0.003 dex (∌10%{\sim} 10 \%), which provides a constraint for cosmological simulations of galaxy formation and evolution. We derive the relation as a function of galaxy type and find that their intrinsic scatters and slopes are consistent within the errors. We also calculate the DHI−MHID_{\rm HI} - M_{\rm HI} relation for two redshift bins and do not find any evidence for evolution with redshift. These results suggest that over a period of one billion years in lookback time, galaxy discs have not undergone significant evolution in their gas distribution and mean surface mass density, indicating a lack of dependence on both morphological type and redshift.Comment: 10 pages, 5 figures, accepted for publication in MNRA
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