402 research outputs found

    High-Altitude Emission from Pulsar Slot Gaps: The Crab Pulsar

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    We present results of a 3D model of optical to gamma-ray emission from the slot gap accelerator of a rotation-powered pulsar. Primary electrons accelerating to high-altitudes in the unscreened electric field of the slot gap reach radiation-reaction limited Lorentz factors of 2 x 10^7, while electron-positron pairs from lower-altitude cascades flow along field lines interior to the slot gap. The curvature, synchrotron and inverse Compton radiation of both primary electrons and pairs produce a broad spectrum of emission from infra-red to GeV energies. Both primaries and pairs undergo cyclotron resonant absorption of radio photons, allowing them to maintain significant pitch angles. Synchrotron radiation from pairs with a power-law energy spectrum with Lorentz factors 10^2 - 10^5, dominate the spectrum up to 10 MeV. Synchrotron and curvature radiation of primaries dominates from 10 MeV up to a few GeV. We examine the energy-dependent pulse profiles and phase-resolved spectra for parameters of the Crab pulsar as a function of magnetic inclination and viewing angle, comparing to broad-band data. In most cases, the pulse profiles are dominated by caustics on trailing field lines. We also explore the relation of the high-energy and the radio profiles, as well as the possibility of caustic formation in the radio cone emission. We find that the Crab pulsar profiles and spectrum can be reasonably well reproduced by a model with viewing angle 45 degrees and inclination angle 100 or 80 degrees. This model predicts that the slot gap emission below 200 MeV will exhibit correlations in time and phase with the radio emission.Comment: 35 pages, 7 figures, accepted for publication in Astrophysical Journa

    Using Emotional Freedom Techniques (EFT) to Treat PTSD in Veterans: A Review of the Evidence, Survey of Practitioners, and Proposed Clinical Guidelines

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    Abstract BACKGROUND: High prevalence rates of posttraumatic stress disorder (PTSD) in active military and veterans present a treatment challenge. Many PTSD studies have demonstrated the efficacy and safety of Emotional Freedom Techniques (EFT). OBJECTIVES: To develop clinical best practice guidelines for the use of EFT to treat PTSD, on the basis of the published literature, practitioner experience, and typical case histories. METHODS: We surveyed 448 EFT practitioners to gather information on their experiences with PTSD treatment. This included their demographic profiles, prior training, professional settings, use of assessments, and PTSD treatment practices. We used their responses, with the research evidence base, to formulate clinical guidelines applying the "stepped care" treatment model used by the United Kingdom's National Institute for Health and Clinical Excellence. RESULTS: Most practitioners (63%) reported that even complex PTSD can be remediated in 10 or fewer EFT sessions. Some 65% of practitioners found that more than 60% of PTSD clients are fully rehabilitated, and 89% stated that less than 10% of clients make little or no progress. Practitioners combined EFT with a wide variety of other approaches, especially cognitive therapy. Practitioner responses, evidence from the literature, and the results of a meta-analysis were aggregated into a proposed clinical guideline. CONCLUSION: We recommend a stepped care model, with 5 EFT therapy sessions for subclinical PTSD and 10 sessions for clinical PTSD, in addition to group therapy, online self-help resources, and social support. Clients who fail to respond should be referred for appropriate further care

    Methanol on Enceladus

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95284/1/grl26203.pd

    Industrial constructions of publics and public knowledge: a qualitative investigation of practice in the UK chemicals industry

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    This is a post print version of the article. The official published version can be obtained from the link below - © 2007 by SAGE PublicationsWhile the rhetoric of public engagement is increasingly commonplace within industry, there has been little research that examines how lay knowledge is conceptualized and whether it is really used within companies. Using the chemicals sector as an example, this paper explores how companies conceive of publics and "public knowledge," and how this relates to modes of engagement/communication with them. Drawing on qualitative empirical research in four companies, we demonstrate that the public for industry are primarily conceived as "consumers" and "neighbours," having concerns that should be allayed rather than as groups with knowledge meriting engagement. We conclude by highlighting the dissonance between current advocacy of engagement and the discourses and practices prevalent within industry, and highlight the need for more realistic strategies for industry/public engagement.Funding was received from the ESRC Science in Society Programme

    Tephrostratigraphy of the late glacial and Holocene sediments of Puyehue Lake (Southern Volcanic Zone, Chile, 40°S)

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    Author Posting. © Elsevier B.V., 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Quaternary Research 70 (2008): 343-357, doi:10.1016/j.yqres.2008.06.001.We document the mineralogical and geochemical composition of tephra layers identified in the late Quaternary sediments of Puyehue Lake (Southern Volcanic Zone of the Andes, Chile, 40°S) to identify the source volcanoes and to present the first tephrostratigraphic model for the region. For the last millennium, we propose a multi-criteria correlation model based on five tephra layers identified at seven coring sites. The two upper tephras are thin fine-grained green layers composed of more than 80% rhyodacitic glass shards, and associated to the AD 1960 and AD 1921-22 eruptions of the Puyehue-Cordon de Caulle volcanic complex. The third tephra is a sandy layer dominated by orthopyroxene, and related to the AD 1907 eruption of Rininahue maar. An olivine-rich tephra was deposited at the end of the 16th century, and a tephra characterized by a two pyroxene association marks the second half of the first millennium AD. In addition, we detail the tephra succession of an 11.22 m long sediment core covering the last 18,000 years. The results demonstrate that the central province of the Southern Volcanic Zone has been active throughout the last deglaciation and the Holocene, with no increase in volcanic activity during glacial unloading.The ENSO-Chile project is supported by the Belgian Federal Office for Scientific, Technical and Cultural Affairs (OSTC)
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