20 research outputs found

    The Atacama Cosmology Telescope: A Catalog of >4000 Sunyaev–Zel’dovich Galaxy Clusters

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    We present a catalog of 4195 optically confirmed Sunyaev–Zel'dovich (SZ) selected galaxy clusters detected with signal-to-noise ratio >4 in 13,211 deg2 of sky surveyed by the Atacama Cosmology Telescope (ACT). Cluster candidates were selected by applying a multifrequency matched filter to 98 and 150 GHz maps constructed from ACT observations obtained from 2008 to 2018 and confirmed using deep, wide-area optical surveys. The clusters span the redshift range 0.04 1 clusters, and a total of 868 systems are new discoveries. Assuming an SZ signal versus mass-scaling relation calibrated from X-ray observations, the sample has a 90% completeness mass limit of M500c > 3.8 × 1014 M⊙, evaluated at z = 0.5, for clusters detected at signal-to-noise ratio >5 in maps filtered at an angular scale of 2farcm4. The survey has a large overlap with deep optical weak-lensing surveys that are being used to calibrate the SZ signal mass-scaling relation, such as the Dark Energy Survey (4566 deg2), the Hyper Suprime-Cam Subaru Strategic Program (469 deg2), and the Kilo Degree Survey (825 deg2). We highlight some noteworthy objects in the sample, including potentially projected systems, clusters with strong lensing features, clusters with active central galaxies or star formation, and systems of multiple clusters that may be physically associated. The cluster catalog will be a useful resource for future cosmological analyses and studying the evolution of the intracluster medium and galaxies in massive clusters over the past 10 Gyr

    The Theory of Brown Dwarfs and Extrasolar Giant Planets

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    Straddling the traditional realms of the planets and the stars, objects below the edge of the main sequence have such unique properties, and are being discovered in such quantities, that one can rightly claim that a new field at the interface of planetary science and and astronomy is being born. In this review, we explore the essential elements of the theory of brown dwarfs and giant planets, as well as of the new spectroscopic classes L and T. To this end, we describe their evolution, spectra, atmospheric compositions, chemistry, physics, and nuclear phases and explain the basic systematics of substellar-mass objects across three orders of magnitude in both mass and age and a factor of 30 in effective temperature. Moreover, we discuss the distinctive features of those extrasolar giant planets that are irradiated by a central primary, in particular their reflection spectra, albedos, and transits. Aspects of the latest theory of Jupiter and Saturn are also presented. Throughout, we highlight the effects of condensates, clouds, molecular abundances, and molecular/atomic opacities in brown dwarf and giant planet atmospheres and summarize the resulting spectral diagnostics. Where possible, the theory is put in its current observational context.Comment: 67 pages (including 36 figures), RMP RevTeX LaTeX, accepted for publication in the Reviews of Modern Physics. 30 figures are color. Most of the figures are in GIF format to reduce the overall size. The full version with figures can also be found at: http://jupiter.as.arizona.edu/~burrows/papers/rm

    Track D Social Science, Human Rights and Political Science

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138414/1/jia218442.pd

    Matrix metalloproteinase-13 influences ERK signalling in articular rabbit chondrocytes

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    Summary Objective Matrix metalloproteinase-13 (MMP-13) is an extracellular MMP that cleaves type II collagen, the major protein component of cartilage, with high specificity and has been implicated in the pathology of osteoarthritis. The present study aimed to characterize the binding and internalization kinetics of MMP-13 in normal rabbit chondrocytes and whether MMP-13 affected cell signalling. Methods Rabbit chondrocytes were used in [125I]-MMP-13 binding assays to investigate the MMP-13 binding kinetics and Western analysis allowed for the assessment of intracellular signalling cascades. Results Rabbit chondrocytes were found to express the cartilage-specific genes aggrecan and type II collagen throughout their in vitro culture period. Appreciable specific cell-association of [125I]-MMP-13 was detected after 10 min of exposure to the ligand and equilibrium was obtained after 2 h. Binding of [125I]-MMP-13 to chondrocytes was specific and approached saturation at 75 nM. Internalization of MMP-13 was evident after 20 min, reached a maximum at 30 min and had returned to baseline by 90 min. Addition of receptor-associated protein (RAP) inhibited the internalization of MMP-13 indicating a likely role for low-density lipoprotein receptor-related protein-1 (LRP1) in this process. Interestingly the presence of MMP-13 induced phosphorylation of the extracellular signal-regulated kinase 1/2 (ERK1/2) protein showing that there is initiation of a signalling process in response to MMP-13 being bound and internalized by rabbit chondrocytes. However, this activation does not involve the MMP-13 internalization receptor LRP1. Conclusion These studies demonstrate and characterize the MMP-13 binding and internalization system in rabbit chondrocytes and indicate that MMP-13 may regulate the phenotype of the chondrocytes through this receptor syste
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