42 research outputs found

    Paper Session I-B - Payload Ground Handling Mechanism Vision Measurement System

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    For installation of payloads into the Orbiter cargo bay while at the pad, the payload is delivered to the launchpad in a canister. The payload is then transferred into the payload bay of the Shuttle Orbiter . The mechanism responsible for manipulating the payload, the Payload Ground Handling Mechanism (PGHM), consists of a set of movable J-Hooks that lift the payload by its trunnions . Successful, safe integration of the payload requires careful position measurement of the J-Hooks relative to the payload trunnions and the payload relative to the Orbiter payload bay. Due to the complex nature and high missionto -mission variability of the geometry involved with the flight hardware, rulers are presently the best way to measure these relative positions; however measurement with rulers is difficult, time-consuming, and relatively inaccurate. The PGHM Vision Measurement System alleviates this measurement problem by using a standard inexpensive, RS - 170, monochrome camera coupled with digital image processing to precisely measure the relative position of the payload. The image processing algorithms are specifically designed to locate and track uniquely designed targets . The system accurately measures the X, Y, and Z position of the payload via the vector position of the targets . The vision measurement system is currently being integrated into the PGHM

    The Gravity Collective: A Search for the Electromagnetic Counterpart to the Neutron Star-Black Hole Merger GW190814

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    We present optical follow-up imaging obtained with the Katzman Automatic Imaging Telescope, Las Cumbres Observatory Global Telescope Network, Nickel Telescope, Swope Telescope, and Thacher Telescope of the LIGO/Virgo gravitational wave (GW) signal from the neutron star-black hole (NSBH) merger GW190814. We searched the GW190814 localization region (19 deg2^{2} for the 90th percentile best localization), covering a total of 51 deg2^{2} and 94.6% of the two-dimensional localization region. Analyzing the properties of 189 transients that we consider as candidate counterparts to the NSBH merger, including their localizations, discovery times from merger, optical spectra, likely host-galaxy redshifts, and photometric evolution, we conclude that none of these objects are likely to be associated with GW190814. Based on this finding, we consider the likely optical properties of an electromagnetic counterpart to GW190814, including possible kilonovae and short gamma-ray burst afterglows. Using the joint limits from our follow-up imaging, we conclude that a counterpart with an rr-band decline rate of 0.68 mag day−1^{-1}, similar to the kilonova AT 2017gfo, could peak at an absolute magnitude of at most −17.8-17.8 mag (50% confidence). Our data are not constraining for ''red'' kilonovae and rule out ''blue'' kilonovae with M>0.5M⊙M>0.5 M_{\odot} (30% confidence). We strongly rule out all known types of short gamma-ray burst afterglows with viewing angles <<17∘^{\circ} assuming an initial jet opening angle of ∼\sim5.2∘5.2^{\circ} and explosion energies and circumburst densities similar to afterglows explored in the literature. Finally, we explore the possibility that GW190814 merged in the disk of an active galactic nucleus, of which we find four in the localization region, but we do not find any candidate counterparts among these sources.Comment: 86 pages, 9 figure

    Magmatic haggertyite in olivine lamproites of the West Kimberley region, Western Australia

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    We report the first occurrence of magmatic haggertyite (BaFe6Ti5MgO19) from the Miocene lamproites of the West Kimberley region of Western Australia. This contrasts with the metasomatic formation reported in an olivine lamproite host at the type locality, Prairie Creek, Arkansas. Haggertyite occurs in the groundmass of a diamondiferous olivine lamproite pipe in the Ellendale field, and within the large zoned Walgidee Hills lamproite where it forms part of an extensive suite of Ba- and K-bearing titanate and Ti-rich silicate minerals. The haggertyite co-exists with chromian spinel, perovskite, and ilmenite in the Ellendale lamproite, and with priderite and perovskite and, in one locality, with priderite, jeppeite, ilmenite, and perovskite, in the Walgidee Hills lamproite. Unlike priderite and perovskite, which are common groundmass phases in the Ellendale olivine lamproites and present throughout the Walgidee Hills lamproite, haggertyite appears restricted in its occurrence and crystallization interval, with sparse ilmenite apparently mostly crystallizing as an alternative phase. In the Walgidee Hills lamproite the haggertyite-bearing assemblage is succeeded by the Ba-titanate assemblage priderite plus jeppeite in the evolved central part of the body. The haggertyite in the main zone of the Walgidee Hills lamproite has an average composition of B a 0.7 K 0.3 1.0 T i 5.0 F e 2.1 3 + C r 0.1 F e 3.8 2 + M n 0.2 M g 0.6 N a 0.1 12 O 19 (Ba0.7K0.3)1.0(Ti5.0Fe2.13+Cr0.1Fe3.82+Mn0.2Mg0.6Na0.1)12O19\left(\mathrm{Ba}_{0.7} \mathrm{K}_{0.3}\right)_{1.0}\left(\mathrm{Ti}_{5.0} \mathrm{Fe}_{2.1}^{3+} \mathrm{Cr}_{0.1} \mathrm{Fe}_{3.8}^{2+} \mathrm{Mn}_{0.2} \mathrm{Mg}_{0.6} \mathrm{Na}_{0.1}\right)_{12} \mathrm{O}_{19}and is thus very similar to the original haggertyite described from xenoliths in the Prairie Creek lamproite apart from being poorer in Cr and Ni. Haggertyite in the groundmass of the Ellendale olivine lamproite and the central zone of the Walgidee Hills lamproite, in addition to variations in Mg and Cr, show significant variation in Ti and Fe contents and in calculated Fe3+ and Fe2+. A linear inverse relationship between Ti and Fe, and Ti and Fe3+, indicates that Fe3+ is accommodated by the coupled substitution Ti4+ + Fe2+ Fe3+. A marked trend to higher Fe3+ in the haggertyite in Ellendale 9 olivine lamproite is ascribed to increasing oxidation during crystallization, with fO2 estimated from the olivine- spinel thermometer and oxygen barometer at Dlog FMQ = -1 to +3 at temperatures of 790-660 °C. The haggertyite in the central zone of the Walgidee Hills lamproite, in contrast, shows a marked trend to Fe2+ enrichment, which is associated with decreasing Fe in perovskite. This is inferred to indicate formation under more reducing conditions, but suficiently oxidized to permit Fe3+ in co-existing priderite and jeppeite. Trace-element analysis by LA-ICP-MS shows the Walgidee Hills haggertyite contains minor amounts of Na, Si, Ca, V, Co, Zn, Sr, Zr, Nb, and Pb, and only traces of Al, P, Sc, Rb, REE, Hf, and Ta. Moreover, the haggertyite is preferentially enriched in certain lithophile (Ba, Sr), siderophile (Mn, Fe, Co, Ni), and chalcophile (Zn, Pb) elements relative to co-existing priderite. Haggertyite crystallization appears to be a consequence not only of the very high Ba, Ti, and K contents of the lamproite, but of relatively high-Fe concentrations and low temperatures in evolved olivine lamproite magma with the Fe3+/Fe2+ ratio determined by the prevailing f O 2. fO2.f_{\mathrm{O}_{2}}.The new data suggest that haggertyite might also be present but previously unrecognized in the evolved groundmass of other olivine lamproites. Haggertyite is one of an increasing number of new minerals in upper mantle rocks and volcanics derived from the upper mantle hosting large-ion-lithophile and high field strength cations.The authors acknowledge the facilities and the scientific and technical assistance of Microscopy Australia at the Advanced Imaging Precinct, Australian National University, a facility that is funded by the University, and State and Federal Governments. The project was partially supported by ARC Discovery Project DP140103841

    Increased Susceptibility to Hypoxic Pulmonary Hypertension in Bmpr2 Mutant Mice is Associated with Endothelial Dysfunction in the Pulmonary Vasculature

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    Patients with familial pulmonary arterial hypertension inherit heterozygous mutations of the type 2 bone morphogenetic protein (BMP) receptor BMPR2. To explore the cellular mechanisms of this disease, we evaluated the pulmonary vascular responses to chronic hypoxia in mice carrying heterozygous hypomorphic Bmpr2 mutations (Bmpr2 delta Ex2/+). These mice develop more severe pulmonary hypertension after prolonged exposure to hypoxia without an associated increase in pulmonary vascular remodeling or proliferation compared with wild-type mice. This is associated with defective endothelial-dependent vasodilatation and enhanced vasoconstriction in isolated intrapulmonary artery preparations. In addition, there is a selective decrease in hypoxia-induced, BMP-dependent, endothelial nitric oxide synthase expression and Smad signaling in the intact lungs and in cultured pulmonary microvascular endothelial cells from Bmpr2 delta Ex2/+ mutant mice. These findings indicate that the pulmonary endothelium is a target of abnormal BMP signaling in Bmpr2 delta Ex2/+ mutant mice and suggest that endothelial dysfunction contributes to their increased susceptibility to hypoxic pulmonary hypertension

    Implications of SENSE MR in routine clinical practice

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    Sensitivity encoding (SENSE) uses multiple MRI receive coil elements to encode spatial information in addition to traditional gradient encoding. Requiring less gradient encodings translates into shorter scan times, which is extremely beneficial in many clinical applications. SENSE is available to routine diagnostic imaging for the past 2 years. This paper highlights the use of SENSE with scan time reduction factors up to 6 in contrast-enhanced MRA, routine abdominal imaging, mammography, cardiac and neuro imaging. It is shown that SENSE has opened new horizons in both routine and advanced MR imaging. © 2002 Elsevier Science Ireland Ltd. All rights reserved.SCOPUS: re.jinfo:eu-repo/semantics/publishe
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