2,296 research outputs found
Vetoes for Inspiral Triggers in LIGO Data
Full text linkPresented is a summary of studies by the LIGO Scientific Collaboration's
Inspiral Analysis Group on the development of possible vetoes to be used in
evaluation of data from the first two LIGO science data runs. Numerous
environmental monitor signals and interferometer control channels have been
analyzed in order to characterize the interferometers' performance. The results
of studies on selected data segments are provided in this paper. The vetoes
used in the compact binary inspiral analyses of LIGO's S1 and S2 science data
runs are presented and discussed.Comment: Submitted to Classical and Quantum Gravity for the GWDAW-8
proceeding
Tethered orbital refueling study
Get PDFOne of the major applications of the space station will be to act as a refueling depot for cryogenic-fueled space-based orbital transfer vehicles (OTV), Earth-storable fueled orbit maneuvering vehicles, and refurbishable satellite spacecraft using hydrazine. One alternative for fuel storage at the space station is a tethered orbital refueling facility (TORF), separated from the space station by a sufficient distance to induce a gravity gradient force that settles the stored fuels. The technical feasibility was examined with the primary focus on the refueling of LO2/LH2 orbital transfer vehicles. Also examined was the tethered facility on the space station. It was compared to a zero-gravity facility. A tethered refueling facility should be considered as a viable alternative to a zero-gravity facility if the zero-gravity fluid transfer technology, such as the propellant management device and no vent fill, proves to be difficult to develop with the required performance
Rapid and long-term disappearance of CD4+ T lymphocyte responses specific for Anaplasma marginale major surface protein-2 (MSP2) in MSP2 vaccinates following challenge with live A. marginale
Get PDFVolcanism and the Greenland ice cores: A new tephrochronological framework for the last glacial-interglacial transition (LGIT) based on cryptotephra deposits in three ice cores
Get PDFChemical profiles from Greenland ice cores show that the frequency of volcanism was higher during the last glacial-interglacial transition (LGIT) and early Holocene, (17–9 ka b2k) than in any other period during the last 110 kyr. This increased frequency has partly been linked to climate-driven melting of the Icelandic ice sheet during the last deglaciation, with regional isostatic changes thought to alter mantle viscosity and lead to more eruptions. Our study is the first to construct a comprehensive tephrochronological framework from Greenland ice cores over the LGIT to aid in the reconstruction of volcanic activity over this period. The framework is based on extensive high-resolution sampling of three Greenland ice cores between 17.4 and 11.6 ka b2k and comprises a total of 64 cryptotephra deposits from the NGRIP, GRIP and NEEM ice cores. We show that many of these tephras are preserved within the core without an associated chemical signature in the ice, which implies that reconstructions of volcanism based solely on glacio-chemical indicators might underestimate the number of events. Single glass shards from each deposit were geochemically characterised to trace the volcanic source and many of these deposits could be correlated between cores. We show that the 64 deposits represent tephra deposits from 42 separate volcanic events, and of these, 39 are from Iceland, two from the north Pacific region (Japan and USA) and one has an unknown source. Six deposits can be correlated to terrestrial and/or marine tephra deposits in the Northern Hemisphere and the remaining 36 are unreported in other archives. We did not locate tephra from the compositionally distinctive Laacher See eruption (∼13 ka b2k) in our records. Combining our new discoveries with the previously published tephra framework, raises the number of individual tephra horizons found in Greenland ice over this interval to 50. This significantly improves the regional tephrochronological framework, our knowledge of the eruptive history of Iceland during the LGIT and provides new tephra constraints over key LGIT climate events. Consequentially, this framework can guide sampling strategies of future tephra studies in the terrestrial and marine realms aiming to link these records to the Greenland ice cores to assess regional climate synchroneity
Understanding the lived experiences of Mexican informal caregivers with Ambient Assisted Living Technologies
Get PDFAmbient Assisted Living (AAL) Technologies, have the potential to support the people with dementia living in their homes for longer. Dementia is a major public health concern. It currently affects approximately 46.8 million people worldwide and by 2050 this figure will increase to 131.5 million. Low-and-middle income countries (LMIC) will be particularly affected by this situation as their poor health infrastructures and governmental support will mean that they have to rely on the informal caregiver (IC) sector. ICs are people who care for a dependent or disabled family member, commonly spouses or daughters. Mexico was the first Spanish speaking country in the world to recognise dementia as a public health priority. In-home technologies, such as AAL Technologies, are used in dementia care in order to improve patients’ and caregivers’ quality of life. This paper explores the way in which Mexican ICs of people with dementia (PWD) make sense of their lived experiences with AAL technologies
Sexual violence and general functioning among formerly abducted girls in Northern Uganda:the mediating roles of stigma and community relations - the WAYS study
Get PDFBACKGROUND: Although sexual violence in war is associated with long-term mental health problems, little is known about its association with general functioning and the factors that explain this association. This study aims to illuminate the path from sexual violence to poor functioning. The prevalence of sexual violence among formerly abducted girls in Northern Uganda was assessed as well as the extent to which stigma and community relations explain the association between sexual violence and general functioning. METHOD: In a cross-sectional analysis using data from the WAYS study (N = 210, baseline age 22.06, SD = 2.06, minimum-maximum 18-25), the extent of mediation of the association between sexual violence and general functioning was assessed in multiple regression models. RESULTS: Sexual violence was found to be associated with increased stigma, poor community relations, and poor general functioning. The association between sexual violence and general functioning was mediated by stigma and community relations. The bootstrap results indicated significant mediation by stigma of 47 % (95 % confidence interval [CI] 35 to 78 % and by community relations of 67 % (95 % CI: 52 to 78 %) in the association between sexual violence and general functioning. CONCLUSION: Thus, poor functioning among formerly abducted girls is largely mediated by stigma and poor community relations. However, due to the relatively small effect sizes of the associations, targeted interventions to prevent impaired functioning may have only modest benefits to the formerly abducted girls. Interventions to alleviate the toxic effects of sexual violence in formerly abducted girls would benefit from a holistic approach that targets stigma and poor relationships within communities
Effects of mode degeneracy in the LIGO Livingston Observatory recycling cavity
Get PDFWe analyze the electromagnetic fields in a Pound-Drever-Hall locked,
marginally unstable, Fabry-Perot cavity as a function of small changes in the
cavity length during resonance. More specifically, we compare the results of a
detailed numerical model with the behavior of the recycling cavity of the Laser
Interferometer Gravitational-wave Observatory (LIGO) detector that is located
in Livingston, Louisiana. In the interferometer's normal mode of operation, the
recycling cavity is stabilized by inducing a thermal lens in the cavity mirrors
with an external CO2 laser. During the study described here, this thermal
compensation system was not operating, causing the cavity to be marginally
optically unstable and cavity modes to become degenerate. In contrast to stable
optical cavities, the modal content of the resonating beam in the uncompensated
recycling cavity is significantly altered by very small cavity length changes.
This modifies the error signals used to control the cavity length in such a way
that the zero crossing point is no longer the point of maximum power in the
cavity nor is it the point where the input beam mode in the cavity is
maximized.Comment: Eight pages in two-column format. Six color figures. To be published
JOSA
Transverse Polarization of Top Quark Pairs at the Tevatron and the Large Hadron Collider
Full text linkWe investigate the prospects to observe effects of transverse polarization of
top quarks in . QCD absorptive parts generate a
polarization of top quarks and antiquarks transverse to the production plane in
the partonic processes and , which
reaches values of a few percent. These perturbative QCD effects are decreased
at the hadronic level. A measurement through momentum correlations among the
and decay products will be difficult both at an upgraded Tevatron
and at the LHC.Comment: 14 pages, LaTeX; 8 uuencoded, tar-compressed figures added separatel
A Holocene cryptotephra record from the Chukchi margin: the first tephrostratigraphic study in the Arctic Ocean
Get PDFDeveloping geochronology for sediments in the Arctic Ocean and its continental margins is an important but challenging task complicated by multiple problems. In particular, the Chukchi/Beaufort margin, a critical area for reconstructing paleoceanographic conditions in the Pacific sector of the Arctic, features widespread dissolution of calcareous material, which limits posibilities for radiocarbon chronology. In order to evaluate the untapped potential of tephrochronology for constraining the age of these sediments, we investigated a sediment core from the eastern Chukchi Sea margin for cryptotephra. The core was collected in the area of sediment focusing on the upper slope (Darby et al., 2009). Samples were taken from the upper sedimentary unit composed of homogenous, fine-grained mud inferred to represent marine environmental conditions of the last 8-9 ka. Based on this age estimate, the initial set of 36 samples has an average resolution of ~250 years. Freeze-dried samples (0.5 g) were treated with HCl, wet-sieved to obtain a 80-25-μm fraction, treated with 1% NaOH to disaggregate clay clumps, and separated at specific density between 2.3 and 2.5 g/cm3. Residues in all samples featured abundant shards of colorless volcanic glass with an admixture of brown shards in the lower part of the unit. Three apparent tephra peaks were identified in the upper part of the record. The electron microprobe analysis of individual shards from these peaks showed nearly identical chemical compositions indicative of the late-Holocene tephras of the Aniakchak volcano in southwestern Alaska (e.g., Kaufman et al., 2012). The glasses analyzed exhibit a continuous composition range from 55 to 77 wt% SiO2 overlapping with two major populations of Aniakchak glasses (andesitic and dacitic) and also including some intermediate compositions. We infer that the three tephra peaks identified correspond to the three prominent tephra layers investigated in lake deposits between Aniakchak and the core site and dated to ~0.4, 3.1, and 3.7 ka (Kaufman et al., 2012). Further detailed study of tephra distribution in the Chukchi margin cores is underway. Identification of distinct tephra peaks with the composition traceable to specific known eruptions provides a powerful, independent chronological tool, much needed for Arctic paleoceanography. The consistent presence of cryptotephra in the analyzed samples suggests its wide occurrence in at least the Chukchi margin sediments; studies from other Arctic shelves and basins are needed to understand the geographic pattern of tephra distribution in seafloor sediments from this part of the world.
Darby, D.A., Ortiz, J. Polyak, L., et al., 2009. The role of currents and sea ice in both slowly deposited central Arctic and rapidly deposited Chukchi-Alaskan margin sediments. Global Planet. Change 68, 58-72.
Kaufman, D.S., Jensen, B.J.L., Reyes, A.V., et al., 2012. Late Quaternary tephrostratigraphy, Ahklun Mountains, SW Alaska. J. Quatern. Sci. 27, 344–359
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