They Lie Now In Small Packets Upon The Desk, A Position Hardly...

In lieu of an abstract, below is the essay\u27s first paragraph. They lie now in small packets upon the desk, a position hardly appropriate for what they contain. In the clutter and waste that surround them they appear to be almost another pile of insignificant odds and ends. Occasionally will be extracted from this wasteland and examined but these brief glances hardly do justice to the memories they evoke

SDSS 0956+5128: A Broad-line Quasar with Extreme Velocity Offsets

We report on the discovery of a Type 1 quasar, SDSS 0956+5128, with a surprising combination of extreme velocity offsets. SDSS 0956+5128 is a broad-lined quasar exhibiting emission lines at three substantially different redshifts: a systemic redshift of z ~ 0.714 based on narrow emission lines, a broad MgII emission line centered 1200 km/s bluer than the systemic velocity, at z ~ 0.707, and broad H\alpha and H\beta emission lines centered at z ~ 0.690. The Balmer line peaks are 4100 km/s bluer than the systemic redshift. There are no previously known objects with such an extreme difference between broad MgII and broad Balmer emission. The two most promising explanations are either an extreme disk emitter or a high-velocity black hole recoil. However, neither explanation appears able to explain all of the observed features of SDSS 0956+5128, so the object may provide a challenge to our general understanding of quasar physics.Comment: ApJ, accepte

The Milky Way Tomography With SDSS. III. Stellar Kinematics

We study Milky Way kinematics using a sample of 18.8 million main-sequence stars with r 20 degrees). We find that in the region defined by 1 kpc < Z < 5 kpc and 3 kpc < R < 13 kpc, the rotational velocity for disk stars smoothly decreases, and all three components of the velocity dispersion increase, with distance from the Galactic plane. In contrast, the velocity ellipsoid for halo stars is aligned with a spherical coordinate system and appears to be spatially invariant within the probed volume. The velocity distribution of nearby (Z < 1 kpc) K/M stars is complex, and cannot be described by a standard Schwarzschild ellipsoid. For stars in a distance-limited subsample of stars (< 100 pc), we detect a multi-modal velocity distribution consistent with that seen by HIPPARCOS. This strong non-Gaussianity significantly affects the measurements of the velocity-ellipsoid tilt and vertex deviation when using the Schwarzschild approximation. We develop and test a simple descriptive model for the overall kinematic behavior that captures these features over most of the probed volume, and can be used to search for substructure in kinematic and metallicity space. We use this model to predict further improvements in kinematic mapping of the Galaxy expected from Gaia and the Large Synoptic Survey Telescope.NSF AST-615991, AST-0707901, AST-0551161, AST-02-38683, AST-06-07634, AST-0807444, PHY05-51164NASA NAG5-13057, NAG5-13147, NNXO-8AH83GPhysics Frontier Center/Joint Institute for Nuclear Astrophysics (JINA) PHY 08-22648U.S. National Science FoundationMarie Curie Research Training Network ELSA (European Leadership in Space Astrometry) MRTN-CT-2006-033481Fermi Research Alliance, LLC, United States Department of Energy DE-AC02-07CH11359Alfred P. Sloan FoundationParticipating InstitutionsJapanese MonbukagakushoMax Planck SocietyHigher Education Funding Council for EnglandMcDonald Observator

The Milky Way Tomography with SDSS: III. Stellar Kinematics

We study Milky Way kinematics using a sample of 18.8 million main-sequence stars with r<20 and proper-motion measurements derived from SDSS and POSS astrometry, including ~170,000 stars with radial-velocity measurements from the SDSS spectroscopic survey. Distances to stars are determined using a photometric parallax relation, covering a distance range from ~100 pc to 10 kpc over a quarter of the sky at high Galactic latitudes (|b|>20 degrees). We find that in the region defined by 1 kpc <Z< 5 kpc and 3 kpc <R< 13 kpc, the rotational velocity for disk stars smoothly decreases, and all three components of the velocity dispersion increase, with distance from the Galactic plane. In contrast, the velocity ellipsoid for halo stars is aligned with a spherical coordinate system and appears to be spatially invariant within the probed volume. The velocity distribution of nearby ($Z<1$ kpc) K/M stars is complex, and cannot be described by a standard Schwarzschild ellipsoid. For stars in a distance-limited subsample of stars (<100 pc), we detect a multimodal velocity distribution consistent with that seen by HIPPARCOS. This strong non-Gaussianity significantly affects the measurements of the velocity ellipsoid tilt and vertex deviation when using the Schwarzschild approximation. We develop and test a simple descriptive model for the overall kinematic behavior that captures these features over most of the probed volume, and can be used to search for substructure in kinematic and metallicity space. We use this model to predict further improvements in kinematic mapping of the Galaxy expected from Gaia and LSST.Comment: 90 pages, 26 figures, submitted to Ap

Milky Way Tomography IV: Dissecting Dust

We use SDSS photometry of 73 million stars to simultaneously obtain best-fit main-sequence stellar energy distribution (SED) and amount of dust extinction along the line of sight towards each star. Using a subsample of 23 million stars with 2MASS photometry, whose addition enables more robust results, we show that SDSS photometry alone is sufficient to break degeneracies between intrinsic stellar color and dust amount when the shape of extinction curve is fixed. When using both SDSS and 2MASS photometry, the ratio of the total to selective absorption, $R_V$, can be determined with an uncertainty of about 0.1 for most stars in high-extinction regions. These fits enable detailed studies of the dust properties and its spatial distribution, and of the stellar spatial distribution at low Galactic latitudes. Our results are in good agreement with the extinction normalization given by the Schlegel et al. (1998, SFD) dust maps at high northern Galactic latitudes, but indicate that the SFD extinction map appears to be consistently overestimated by about 20% in the southern sky, in agreement with Schlafly et al. (2010). The constraints on the shape of the dust extinction curve across the SDSS and 2MASS bandpasses support the models by Fitzpatrick (1999) and Cardelli et al. (1989). For the latter, we find an $R_V=3.0\pm0.1$(random) $\pm0.1$(systematic) over most of the high-latitude sky. At low Galactic latitudes (|b|<5), we demonstrate that the SFD map cannot be reliably used to correct for extinction as most stars are embedded in dust, rather than behind it. We introduce a method for efficient selection of candidate red giant stars in the disk, dubbed "dusty parallax relation", which utilizes a correlation between distance and the extinction along the line of sight. We make these best-fit parameters, as well as all the input SDSS and 2MASS data, publicly available in a user-friendly format.Comment: Submitted to ApJ, 55 pages, 37 figure

Reoperative aortic valve replacement in the octogenarians-minimally invasive technique in the era of transcatheter valve replacement

Objective: Reoperative aortic valve replacement (re-AVR) in octogenarians is considered high risk and therefore might be indicated for transcatheter AVR. The minimally invasive technique for re-AVR limits dissection and might benefit this patient population. We report the outcomes of re-AVR in high-risk octogenarians who might be considered candidates for transcatheter AVR to assess the safety of re-AVR and minimally invasive operative techniques. Methods: We identified 105 patients, aged >= 80 years, who underwent open re-AVR at our institution from July 1997 to December 2011. Patients requiring concomitant coronary bypass surgery and/or other valve surgery were excluded. The outcomes of interest included operative mortality, postoperative complications, and midterm postoperative survival. Results: Of the 105 patients, 51 underwent minimally re-AVR through upper hemisternotomy (Mre-AVR) and 54 standard full sternotomy (Fre-AVR). The mean patient age was 82.8 +/- 3.8 years. No significant differences were found in the patient risk factors. Postoperatively, 6 patients (5.7%) underwent reoperation for bleeding, 4 (3.8%) experienced permanent stroke, 4 (3.8%) developed new renal failure, and 22 (21.0%) had new-onset atrial fibrillation. Overall, the operative mortality was 6.7%, and the 1- and 5-year survival was 87% and 53%, respectively. When Mre-AVR and Fre-AVR were compared, the operative mortality was 9.2% in the Fre-AVR group and 3.9% in the Mre-AVR group (P = .438). Kaplan-Meier analysis showed a survival benefit at both 1 year (79% +/- 11.7% vs 92% +/- 7.8%) and 5 years (38% +/- 17.6% vs 65% +/- 15.7%, P = .028) favoring Mre-AVR. Cox regression analysis identified heparin-induced thrombocytopenia, reoperation for bleeding, older age, full sternotomy, and an infectious complication as predictors of mortality. Conclusions: Octogenarians who undergo re-AVR are thought to be high-risk surgical candidates. The present single-center series revealed acceptable in-hospital outcomes and operative mortality. Mre-AVR was associated with better survival compared with Fre-AVR and might benefit this populatio

The Milky Way Tomography with SDSS. III. Stellar Kinematics

We study Milky Way kinematics using a sample of 18.8 million main-sequence stars with r 20°). We find that in the region defined by 1 kpc <Z< 5 kpc and 3 kpc <R< 13 kpc, the rotational velocity for disk stars smoothly decreases, and all three components of the velocity dispersion increase, with distance from the Galactic plane. In contrast, the velocity ellipsoid for halo stars is aligned with a spherical coordinate system and appears to be spatially invariant within the probed volume. The velocity distribution of nearby (Z < 1 kpc) K/M stars is complex, and cannot be described by a standard Schwarzschild ellipsoid. For stars in a distance-limited subsample of stars (<100 pc), we detect a multi-modal velocity distribution consistent with that seen by HIPPARCOS. This strong non-Gaussianity significantly affects the measurements of the velocity-ellipsoid tilt and vertex deviation when using the Schwarzschild approximation. We develop and test a simple descriptive model for the overall kinematic behavior that captures these features over most of the probed volume, and can be used to search for substructure in kinematic and metallicity space. We use this model to predict further improvements in kinematic mapping of the Galaxy expected from Gaia and the Large Synoptic Survey Telescope.Astronom