To determine whether sickle-cell trait and glucose-6-phosphate dehydrogenase deficiency influence the course and fatality rates of certain diseases requiring hospitalization, especially those associated with thrombotic phenomena, we conducted a co-operative study of 65,154 consecutively admitted, black male patients in 13 Veterans Administration hospitals. The overall frequency of sickle-cell trait was 7.8 per cent and of glucose-6-phosphate dehydrogenase dificiency 11.2 per cent. Both conditions were present in 0.9 per cent of those examined. There were regional, but no age-dependent, differences in the frequency of sickle-cell trait. Sickle-cell trait had no effect on average age at hospitalization or death, overall mortality, length of hospitalization on medical and surgical wards and frequency of any diagnosis, except essential hematuria and pulmonary embolism. Although statistically significant (P less than 0.001), the differences for the latter were small (1.5 per cent of all patients with normal hemoglobin and 2.2 per cent of patients with sickle-cell trait). Glucose-6-phosphate dehydrogenase deficiency had no adverse effect.
Using Keck laser guide star adaptive optics imaging, we have found that the T9 dwarf WISE J1217+1626 and T8 dwarf WISE J1711+3500 are exceptional binaries, with unusually wide separations (≈0.8 ′′ , 8-15 AU), large near-IR flux ratios (≈2-3 mags), and small mass ratios (≈0.5) compared to previously known field ultracool binaries. Keck/NIRSPEC H-band spectra give a spectral type of Y0 for WISE J1217+1626B, and photometric estimates suggest T9.5 for WISE J1711+3500B. The WISE J1217+1626AB system is very similar to the T9+Y0 binary CFBDSIR J1458+1013AB; these two systems are the coldest known substellar multiples, having secondary components of ≈400 K and being planetary-mass binaries if their ages are 1 Gyr. Both WISE J1217+1626B and CFBDSIR J1458+1013B have strikingly blue Y − J colors compared to previously known T dwarfs, including their T9 primaries. Combining all available data, we find that Y − J color drops precipitously between the very latest T dwarfs and the Y dwarfs. The fact that this is seen in (coeval, mono-metallicity) binaries demonstrates that the color drop arises from a change in temperature, not surface
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AbstractWe present a catalog of 9888 M, L and T dwarfs detected in the Pan-STARRS13π Survey (PS1), covering threequarters of the sky. Our catalog contains nearly all known objects of spectral types L0-T2 in the PS1 field, with objects as early as M0 and as late as T9, and includes PS1, 2MASS, AllWISE, and GaiaDR1 photometry. We analyze the different types of photometry reported by PS1 and use two types in our catalog in order to maximize both depth and accuracy. Using parallaxes from the literature, we construct empirical SEDs for field ultracool dwarfs spanning 0.5-12 μm. We determine typical colors of M0-T9 dwarfs and highlight the distinctive colors of subdwarfs and young objects. We combine astrometry from PS1, 2MASS, and GaiaDR1 to calculate new proper motions for our catalog. We achieve a median precision of 2.9mas yr −1 , a factor of ≈3−10 improvement over previous large catalogs. Our catalog contains proper motions for 2405M6-T9 dwarfs and includes the largest set of homogeneous proper motions for L and T dwarfs published to date, 406objects for which there were no previous measurements, and 1176objects for which we improve upon previous literature values. We analyze the kinematics of ultracool dwarfs in our catalog and find evidence that bluer but otherwise generic late-M and Lfield dwarfs (i.e., not subdwarfs) tend to have tangential velocities higher than those of typical field objects. With the public release of the PS1 data, this survey will continue to be an essential tool for characterizing the ultracool dwarf population.
We present the detection of [3.6 µm] photometric variability in two young, L/T transition brown dwarfs, WISE J004701.06+680352.1 (W0047) and 2MASS J2244316+204343 (2M2244) using the Spitzer Space Telescope. We find a period of 16.4 ± 0.2 hr and a peak-to-peak amplitude of 1.07 ± 0.04% for W0047, and a period of 11 ± 2 hr and amplitude of 0.8 ± 0.2% for 2M2244. This period is significantly longer than that measured previously during a shorter observation. We additionally detect significant J-band variability in 2M2244 using the Wide-Field Camera on UKIRT. We determine the radial and rotational velocities of both objects using Keck NIR-SPEC data. We find a radial velocity of −16.0 +0.8 −0.9 km s −1 for 2M2244, and confirm it as a bona fide member of the AB Doradus moving group. We find rotational velocities of v sin i = 9.8 ± 0.3 km s −1 and 14.3 +1.4 −1.5 km s −1 for W0047 and 2M2244, respectively. With inclination angles of 85 +5• −9 and 76 +14• −20 , W0047 and 2M2244 are viewed roughly equator-on. Their remarkably similar colours, spectra and inclinations are consistent with the possibility that viewing angle may influence atmospheric appearance. We additionally present Spitzer [4.5 µm] monitoring of the young, T5.5 object SDSS111010+011613 (SDSS1110) where we detect no variability. For periods < 18 hr, we place an upper limit of 1.25% on the peak-to-peak variability amplitude of SDSS1110.
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