6,554 research outputs found

    Study of alternate optical and fine guidance sensor designs for the space infrared telescope facility (SIRTF)

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    A unique optical design was developed that compensates for the coma degraded images caused by field chopping in SIRTF. The conic constants of a Cassegrain telescope were altered to compensate for the coma induced by the secondary mirror tilt. The modulation transfer function is essentially independent of secondary mirror tilt, and diffraction limited image quality is maintained over a several arcminute field during chopping. With an untilted secondary mirror, the coma compensated (CC) design has a smaller field than the unchopped Ritchey-Chretien design; but use of relay optics, such as the inverted Cassegrain design developed for the fine guidance sensor (FGS), can increase the CC telescope's field size. A reactionless secondary mirror chopper mechanism that uses superconducting magnets was studied. The heart producing elements are confined to a reaction plate that is not directly viewed by the IR focal plane. A design was also developed for a low moment of inertia, reticulated HIP beryllium secondary mirror consistent with blank fabrication technology and optical finishing requirements

    INTERNET ADOPTION AND USE OF E-COMMERCE STRATEGIES BY AGRIBUSINESS FIRMS IN ALABAMA

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    Electronic commerce (e-commerce) is relatively new to the agricultural industry, and affects such aspects of the organization as its strategy, processes, customer relationships, information technology, and business culture. This paper analyzes the factors influencing agribusiness firms' desire or need to adopt the Internet and employ e-commerce strategies. The relationship between the factors driving the choice of distribution channel and Internet usage for e-commerce will empirically be estimated. This study will also assess how Internet adoption and the use of e-commerce strategies impact rural development and the overall sustainability paradigm.Agribusiness,

    Some observations on the prehistory of the Buvuma island group of Lake Victoria

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    During the early part of 1967, a short expedition was made to Buvuma and neighbouring islands, primarily as part of a study of the relationship of laterite to landscape development. The characteristic island skyline of flat laterite capped hills is typical of Buganda topography, a topography which has been the source of much discussion (Pallister 1960, etc). The drowning of the topography by Lake Victoria, which left the laterite mesas as islands standing above the lake, has resulted in a particularly attractive variant of the typical Buganda scene

    Alien Registration- Mcfarlane, Gertrude M. (Houlton, Aroostook County)

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    https://digitalmaine.com/alien_docs/35932/thumbnail.jp

    Experiences of sickness absence among NHS staff: A grounded theory analysis

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    Reducing sickness absence and speeding up return to work following absence is usually beneficial for employees and organisations. However, current theory on sickness absence is not sophisticated enough to meaningfully inform policies which adequately promote employee wellbeing. This research aimed to explore employees’ decisions about taking sickness absence and returning to work and to identify factors which help employees to remain in or return to work. Two studies are presented. Study 1 was a systematic review evaluating the evidence that cognitive-behavioural (CBT) pain management improves work outcomes (return to work, sickness absence and hours worked) in employees with chronic pain. Fifteen studies were reviewed. A meta-analysis of a subgroup of four good or adequate quality studies showed no effect of intervention. Other high and adequate quality studies found no effect of intervention, with one exception. Lower quality studies lacked appropriate control groups, therefore conclusions could not be drawn about their effectiveness. Overall, insufficient evidence was found that CBT pain management improves vocational outcomes. Complex interventions, which target workplace and health issues, may be required. Study 2 was a grounded theory study of sickness absence among NHS staff in South Wales. Face-to-face interviews were conducted with 18 employees. Interviews were transcribed verbatim and analysed using Charmaz’s (2006) approach to grounded theory. A new process model of sickness absence is presented which goes beyond established theories. The establishment of the legitimacy of absence and its negotiation with others, particularly health professionals and managers, were core to the model. The absence process was complex, with different factors becoming important at different points in time, including the type and severity of illness; the work context; the employees’ beliefs about illness and work; their values and support. Line managers had a key role in managing absence but may require additional support and training. Health psychologists should now turn their attention to understanding the specific beliefs which are relevant to absence from work in order to further develop theories of sickness absence

    The relationship between Hippocampal asymmetry and working memory processing in combat-related PTSD: a monozygotic twin study

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    BACKGROUND: PTSD is associated with reduction in hippocampal volume and abnormalities in hippocampal function. Hippocampal asymmetry has received less attention, but potentially could indicate lateralised differences in vulnerability to trauma. The P300 event-related potential component reflects the immediate processing of significant environmental stimuli and has generators in several brain regions including the hippocampus. P300 amplitude is generally reduced in people with PTSD. METHODS: Our study examined hippocampal volume asymmetry and the relationship between hippocampal asymmetry and P300 amplitude in male monozygotic twins discordant for Vietnam combat exposure. Lateralised hippocampal volume and P300 data were obtained from 70 male participants, of whom 12 had PTSD. We were able to compare (1) combat veterans with current PTSD; (2) their non-combat-exposed co-twins; (3) combat veterans without current PTSD and (4) their non-combat-exposed co-twins. RESULTS: There were no significant differences between groups in hippocampal asymmetry. There were no group differences in performance of an auditory oddball target detection task or in P300 amplitude. There was a significant positive correlation between P300 amplitude and the magnitude of hippocampal asymmetry in participants with PTSD. CONCLUSIONS: These findings suggest that greater hippocampal asymmetry in PTSD is associated with a need to allocate more attentional resources when processing significant environmental stimuli.Timothy Hall, Cherrie Galletly, C.R. Clark, Melinda Veltmeyer, Linda J. Metzger, Mark W. Gilbertson, Scott P. Orr, Roger K. Pitman and Alexander McFarlan

    Post-traumatic stress disorder: findings from the Australian National Survey of Mental Health and Well-being

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    Background. We report on the epidemiology of post-traumatic stress disorder (PTSD) in the Australian community, including information on lifetime exposure to trauma, 12-month prevalence of PTSD, sociodemographic correlates and co-morbidity. Methods. Data were obtained from a stratified sample of 10641 participants as part of the Australian National Survey of Mental Health and Well-being. A modified version of the Composite International Diagnostic Interview was used to determine the presence of PTSD, as well as other DSM-IV anxiety, affective and substance use disorders. Results. The estimated 12-month prevalence of PTSD was 1.33%, which is considerably lower than that found in comparable North American studies. Although females were at greater risk than males within the subsample of those who had experienced trauma, the large gender differences noted in some recent epidemiological research were not replicated. Prevalence was elevated among the never married and previously married respondents, and was lower among those aged over 55. For both men and women, rape and sexual molestation were the traumatic events most likely to be associated with PTSD. A high level of Axis 1 co-morbidity was found among those persons with PTSD Conclusions. PTSD is a highly prevalent disorder in the Australian community and is routinely associated with high rates of anxiety, depression and substance disorders. Future research is needed to investigate rates among other populations outside the North American continent.M. Creamer, P. Burgess and A. C. Mcfarlan
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