275 research outputs found

    The USNO-B Catalog

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    USNO-B is an all-sky catalog that presents positions, proper motions, magnitudes in various optical passbands, and star/galaxy estimators for 1,042,618,261 objects derived from 3,643,201,733 separate observations. The data were obtained from scans of 7,435 Schmidt plates taken for the various sky surveys during the last 50 years. USNO-B1.0 is believed to provide all-sky coverage, completeness down to V = 21, 0.2 arcsecond astrometric accuracy at J2000, 0.3 magnitude photometric accuracy in up to five colors, and 85% accuracy for distinguishing stars from non-stellar objects. A brief discussion of various issues is given here, but the actual data are available from http://www.nofs.navy.mil and other sites.Comment: Accepted by Astronomical Journa

    Supermassive Black Holes in Galactic Nuclei: Past, Present and Future Research

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    This review discusses the current status of supermassive black hole research, as seen from a purely observational standpoint. Since the early '90s, rapid technological advances, most notably the launch of the Hubble Space Telescope, the commissioning of the VLBA and improvements in near-infrared speckle imaging techniques, have not only given us incontrovertible proof of the existence of supermassive black holes, but have unveiled fundamental connections between the mass of the central singularity and the global properties of the host galaxy. It is thanks to these observations that we are now, for the first time, in a position to understand the origin, evolution and cosmic relevance of these fascinating objects.Comment: Invited Review, 114 pages. Because of space requirements, this version contains low resolution figures. The full resolution version can be downloaded from http://www.physics.rutgers.edu/~lff/publications.htm

    Dust Processing in Disks around T Tauri Stars

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    The 8-14 micron emission spectra of 12 T Tauri stars in the Taurus/Auriga dark clouds and in the TW Hydrae association obtained with the Infrared Spectrograph (IRS; The IRS is a collaborative venture between Cornell University and Ball Aerospace Corporation funded by NASA through the Jet Propulsion Laboratory and the Ames Research Center.) on board Spitzer are analyzed. Assuming the 10 micron features originate from silicate grains in the optically thin surface layers of T Tauri disks, the 8-14 micron dust emissivity for each object is derived from its Spitzer spectrum. The emissivities are fit with the opacities of laboratory analogs of cosmic dust. The fits include small nonspherical grains of amorphous silicates (pyroxene and olivine), crystalline silicates (forsterite and pyroxene), and quartz, together with large fluffy amorphous silicate grains. A wide range in the fraction of crystalline silicate grains as well as large silicate grains among these stars are found. The dust in the transitional-disk objects CoKu Tau/4, GM Aur, and DM Tau has the simplest form of silicates, with almost no hint of crystalline components and modest amounts of large grains. This indicates that the dust grains in these objects have been modified little from their origin in the interstellar medium. Other stars show various amounts of crystalline silicates, similar to the wide dispersion of the degree of crystallinity reported for Herbig Ae/Be stars of mass <2.5 solar masses. Late spectral type, low-mass stars can have significant fractions of crystalline silicate grains. Higher quartz mass fractions often accompany low amorphous olivine-to-amorphous pyroxene ratios. It is also found that lower contrast of the 10 micron feature accompanies greater crystallinity.Comment: AASTEX, 39 pages text, 14 figures, 4 tables, scheduled to be published July 2006 in the Astrophysical Journa

    Moonraker -- Enceladus Multiple Flyby Mission

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    Enceladus, an icy moon of Saturn, possesses an internal water ocean and jets expelling ocean material into space. Cassini investigations indicated that the subsurface ocean could be a habitable environment having a complex interaction with the rocky core. Further investigation of the composition of the plume formed by the jets is necessary to fully understand the ocean, its potential habitability, and what it tells us about Enceladus' origin. Moonraker has been proposed as an ESA M-class mission designed to orbit Saturn and perform multiple flybys of Enceladus, focusing on traversals of the plume. The proposed Moonraker mission consists of an ESA-provided platform, with strong heritage from JUICE and Mars Sample Return, and carrying a suite of instruments dedicated to plume and surface analysis. The nominal Moonraker mission has a duration of 13.5 years. It includes a 23-flyby segment with 189 days allocated for the science phase, and can be expanded with additional segments if resources allow. The mission concept consists in investigating: i) the habitability conditions of present-day Enceladus and its internal ocean, ii) the mechanisms at play for the communication between the internal ocean and the surface of the South Polar Terrain, and iii) the formation conditions of the moon. Moonraker, thanks to state-of-the-art instruments representing a significant improvement over Cassini's payload, would quantify the abundance of key species in the plume, isotopic ratios, and physical parameters of the plume and the surface. Such a mission would pave the way for a possible future landed mission.Comment: Accepted for publication in The Planetary Science Journa

    A patient-driven registry on Behçet’s disease: the AIDA for patients pilot project

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    IntroductionThis paper describes the creation and preliminary results of a patient-driven registry for the collection of patient-reported outcomes (PROs) and patient-reported experiences (PREs) in Behcet's disease (BD). MethodsThe project was coordinated by the University of Siena and the Italian patient advocacy organization SIMBA (Associazione Italiana Sindrome e Malattia di Behcet), in the context of the AIDA (AutoInflammatory Diseases Alliance) Network programme. Quality of life, fatigue, socioeconomic impact of the disease and therapeutic adherence were selected as core domains to include in the registry. ResultsRespondents were reached via SIMBA communication channels in 167 cases (83.5%) and the AIDA Network affiliated clinical centers in 33 cases (16.5%). The median value of the Behcet's Disease Quality of Life (BDQoL) score was 14 (IQR 11, range 0-30), indicating a medium quality of life, and the median Global Fatigue Index (GFI) was 38.7 (IQR 10.9, range 1-50), expressing a significant level of fatigue. The mean Beliefs about Medicines Questionnaire (BMQ) necessity-concern differential was 0.9 &amp; PLUSMN; 1.1 (range - 1.8-4), showing that the registry participants prioritized necessity belief over concerns to a limited extent. As for the socioeconomic impact of BD, in 104 out of 187 cases (55.6%), patients had to pay from their own pocket for medical exams required to reach the diagnosis. The low family socioeconomic status (p &lt; 0.001), the presence of any major organ involvement (p &lt; 0.031), the presence of gastro-intestinal (p &lt; 0.001), neurological (p = 0.012) and musculoskeletal (p = 0.022) symptoms, recurrent fever (p = 0.002), and headache (p &lt; 0.001) were associated to a higher number of accesses to the healthcare system. Multiple linear regression showed that the BDQoL score could significantly predict the global socioeconomic impact of BD (F = 14.519, OR 1.162 [CI 0.557-1.766], p &lt; 0.001). DiscussionPreliminary results from the AIDA for Patients BD registry were consistent with data available in the literature, confirming that PROs and PREs could be easily provided by the patient remotely to integrate physician-driven registries with complementary and reliable information

    Stewart-Treves syndrome: MR imaging of a postmastectomy upper-limb chronic lymphedema with angiosarcoma

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    The rare occurrence of angiosarcoma in postmastectomy upper-limb lymphedema with magnetic resonance (MR) imaging is discussed. Unfamiliarity with this aggressive vascular tumor and its harmless appearance often leads to delayed diagnosis. Angiosarcoma complicating chronic lymphedema may be low in signal intensity on T2-weighting and short tau inversion recovery (STIR) imaging reflecting the densely cellular, fibrous stroma, and sparsely vascularized tumor histology. Additional administration of intravenous contrast medium revealed significant enhancement of the tumorous lesions. Awareness of angiosarcoma and its MR imaging appearance in patients with chronic lymphedema may be a key to early diagnosis or allow at least inclusion in the differential diagnosis
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