13 research outputs found

    The Canada-UK deep submillimeter survey. VII. Optical and near-infrared identifications for the 14 hour field

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    We present the multiwavelength identifications for 23 sources in the Canada-UK Deep Submillimeter Survey (CUDSS) 14h field. The identifications have been selected on the basis of radio and near-infrared data, and we argue that, to our observational limits, both are effective at selecting the correct counterparts of the SCUBA sources. We discuss the properties of these identifications and find that they are very red in near-infrared color, with many classified as extremely red objects, and show disturbed morphologies. Using the entire CUDSS catalog of 50 sources, we use a combination of spectroscopic redshifts (four objects), 1.4 GHz : 850 μm flux ratio redshift estimates (10 objects), and redshift lower limits based on nondetections at 1.4 GHz (the rest of the sample) to estimate a lower limit on the median redshift of the population of zmed \u3e 1.4. Working from simple models and using the properties of the secure identifications, we discuss general and tentative constraints on the redshift distribution and the expected colors and magnitudes of the entire population

    Resolving CO (2−1) in z ∼ 1.6 Gas-rich Cluster Galaxies with ALMA: Rotating Molecular Gas Disks with Possible Signatures of Gas Stripping

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    © 2019. The American Astronomical Society. All rights reserved. We present the first spatially resolved observations of molecular gas in a sample of cluster galaxies beyond z > 0.1. Using ALMA, we detect CO (2-1) in eight z ∼ 1.6 cluster galaxies, all within a single 70″ primary beam. The cluster, SpARCS-J0225, was discovered by the Spitzer Adaptation of the Red-sequence Cluster Survey, and is replete with gas-rich galaxies in close proximity, thus affording an efficient multiplexing strategy to amass the first sample of resolved CO in distant clusters. Mapping out the kinematic structure and morphology of molecular gas on ∼3.5 kpc scales reveals rotating gas disks in the majority of the galaxies, and some kinematic peculiarities, including a central gas void, a merger, and one-sided gas tails. We find that the extent of the molecular gas is slightly smaller than that of the optical HST stellar component; this is even more pronounced in low-redshift Virgo cluster galaxies. However, limited by small sample sizes of spatially resolved CO, we are unable to differentiate the distribution of stellar-to-gas radii between cluster and field environments at high redshift. Thus, at first glance, while the cluster galaxies generally look like galaxies infalling from the field, with typical main-sequence star formation rates and massive molecular gas reservoirs situated in rotating disks, they have potentially remarkable attributes, including elevated gas fractions, slightly smaller CO disks, and asymmetric gas tails. Taken in tandem, these signatures are tentative evidence for gas stripping in the z ∼ 1.6 cluster, though verification of these trends will require larger samples

    Performance, carcass yield, and qualitative characteristics of breast and leg muscles of broilers fed diets supplemented with vitamin E at different ages

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    The effects of vitamin E supplementation (300 mg/kg diet) in the diet of broiler chickens for different periods during rearing on the performance and qualitative traits of breast and leg muscles were evaluated. Seven hundred and twenty day-old chicks were distributed into six treatments: basal diet (25 mg vitamin E/kg diet), and diet supplemented with vitamin E from 1 to 15, 1 to 30, 1 to 45, 14 to 45 and 30 to 45 days of age. Vitamin E content, lipid percentage, TBARS (0 and 3 days of storage), color (*L, *a, *b), and pH were evaluated. There were no differences (p>0.05) among treatments in performance, carcass yield, and cut yields. Qualitative parameters (pH and color) presented no differences, although vitamin E positively affected TBARS values at 3 days of storage, mainly in leg muscles. Vitamin E levels in both muscles were higher in the birds supplemented throughout the experiment

    From earthquakes to island area: multi-scale effects upon local diversity

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    Tropical forests occupy small coral atolls to the vast Amazon basin. They occur across bioregions with different geological and climatic history. Differences in area and bioregional history shape species immigration, extinction and diversification. How this effects local diversity is unclear. The Indonesian archipelago hosts thousands of tree species whose coexistence should depend upon these factors. Using a novel dataset of 215 Indonesian forest plots, across fifteen islands ranging in area from 120 to 785 000 km2, we apply Gaussian mixed effects models to examine the simultaneous effects of environment, earthquake proximity, island area and bioregion upon tree diversity for trees ≥ 10 cm diameter at breast height. We find that tree diversity declines with precipitation seasonality and increases with island area. Accounting for the effects of environment and island area we show that the westernmost bioregion Sunda has greater local diversity than Wallacea, which in turn has greater local diversity than easternmost Sahul. However, when the model includes geological activity (here proximity to major earthquakes), bioregion differences are reduced. Overall, results indicate that multi-scale, current and historic effects dictate tree diversity. These multi-scale drivers should not be ignored when studying biodiversity gradients and their impacts upon ecosystem function
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