112 research outputs found

    Accelerated motion and the self-force in Schwarzschild spacetime

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    We provide expansions of the Detweiler-Whiting singular field for motion along arbitrary, planar accelerated trajectories in Schwarzschild spacetime. We transcribe these results into mode-sum regularization parameters, computing previously unknown terms that increase the convergence rate of the mode-sum. We test our results by computing the self-force along a variety of accelerated trajectories. For non-uniformly accelerated circular orbits we present results from a new 1+1D discontinuous Galerkin time-domain code which employs an effective-source. We also present results for uniformly accelerated circular orbits and accelerated bound eccentric orbits computed within a frequency-domain treatment. Our regularization results will be useful for computing self-consistent self-force inspirals where the particle's worldline is accelerated with respect to the background spacetime.Comment: 19 pages, 6 figures (accepted CQG special issue article version

    Streptococcus pneumoniae, Brooklyn, New York: Fluoroquinolone Resistance at our Doorstep

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    To examine the resistance rates and epidemiology of Streptococcus pneumoniae in Brooklyn, New York, isolates were collected during two boroughwide surveillance periods in 1997 and 1999. Of 138 isolates, 67% were susceptible to penicillin and 34% to ciprofloxacin. Susceptibility rates to ciprofloxacin decreased dramatically from 1997 to 1999 (47% to 16%, p=0.0003). Five isolates (3.6%) were resistant to levofloxacin. Western Brooklyn had lower rates of susceptibility to penicillin compared with eastern neighborhoods. More isolates in the eastern neighborhoods belonged to the Spanish/French 9/14 clone, and isolates in the western neighborhoods tended to belong to the Spanish/USA 23F clone. Residents of the western neighborhoods were more likely to be white and elderly and less likely to be receiving Medicaid or public assistance, characteristics associated with increased health-care and antibiotic use. Brooklyn residents appear to be at high risk for fluoroquinolone-resistant S. pneumoniae. Our results underscore the need for vigilant regional surveillance

    Climate geoengineering: issues of path-dependence and socio-technical lock-in

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    As academic and policy interest in climate geoengineering grows, the potential irreversibility of technological developments in this domain has been raised as a pressing concern. The literature on socio-technical lock-in and path dependence is illuminating in helping to situate current concerns about climate geoengineering and irreversibility in the context of academic understandings of historical socio-technical development and persistence. This literature provides a wealth of material illustrating the pervasiveness of positive feedbacks of various types (from the discursive to the material) leading to complex socio-technical entanglements which may resist change and become inflexible even in the light of evidence of negative impacts. With regard to climate geoengineering, there are concerns that geoengineering technologies might contribute so-called ‘carbon lock-in’, or become irreversibly ‘locked-in’ themselves. In particular, the scale of infrastructures that geoengineering interventions would require, and the issue of the so-called ‘termination effect’ have been discussed in these terms. Despite the emergent and somewhat ill-defined nature of the field, some authors also suggest that the extant framings of geoengineering in academic and policy literatures may already demonstrate features recognizable as forms of cognitive lock-in, likely to have profound implications for future developments in this area. While the concepts of path-dependence and lock-in are the subject of ongoing academic critique, by drawing analytical attention to these pervasive processes of positive feedback and entanglement, this literature is highly relevant to current debates around geoengineering

    Evaluation of early and late presentation of patients with ocular mucous membrane pemphigoid to two major tertiary referral hospitals in the United Kingdom

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    PURPOSE: Ocular mucous membrane pemphigoid (OcMMP) is a sight-threatening autoimmune disease in which referral to specialists units for further management is a common practise. This study aims to describe referral patterns, disease phenotype and management strategies in patients who present with either early or established disease to two large tertiary care hospitals in the United Kingdom.\ud \ud PATIENTS AND METHODS: In all, 54 consecutive patients with a documented history of OcMMP were followed for 24 months. Two groups were defined: (i) early-onset disease (EOD:<3 years, n=26, 51 eyes) and (ii) established disease (EstD:>5 years, n=24, 48 eyes). Data were captured at first clinic visit, and at 12 and 24 months follow-up. Information regarding duration, activity and stage of disease, visual acuity (VA), therapeutic strategies and clinical outcome were analysed.\ud \ud RESULTS: Patients with EOD were younger and had more severe conjunctival inflammation (76% of inflamed eyes) than the EstD group, who had poorer VA (26.7%=VA<3/60, P<0.01) and more advanced disease. Although 40% of patients were on existing immunosuppression, 48% required initiation or switch to more potent immunotherapy. In all, 28% (14) were referred back to the originating hospitals for continued care. Although inflammation had resolved in 78% (60/77) at 12 months, persistence of inflammation and progression did not differ between the two phenotypes. Importantly, 42% demonstrated disease progression in the absence of clinically detectable inflammation.\ud \ud CONCLUSIONS: These data highlight that irrespective of OcMMP phenotype, initiation or escalation of potent immunosuppression is required at tertiary hospitals. Moreover, the conjunctival scarring progresses even when the eye remains clinically quiescent. Early referral to tertiary centres is recommended to optimise immunosuppression and limit long-term ocular damage.\ud \u

    Understanding the psychosocial experiences of adults with mild-moderate hearing loss: an application of Leventhal’s self-regulatory model

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    Objective: This study explored the psychosocial experiences of adults with hearing loss using the self-regulatory model as a theoretical framework. The primary components of the model, namely cognitive representations, emotional representations, and coping responses, were examined. Design: Individual semi-structured interviews were conducted. The data were analysed using an established thematic analysis procedure. Study sample: Twenty-five adults with mild-moderate hearing loss from the UK and nine hearing healthcare professionals from the UK, USA, and Canada were recruited via maximum variation sampling. Results: Cognitive representations: Most participants described their hearing loss as having negative connotations and consequences, although they were not particularly concerned about the progression or controllability/curability of the condition. Opinions differed regarding the benefits of understanding the causes of one’s hearing loss in detail. Emotional representations: negative emotions dominated, although some experienced positive emotions or muted emotions. Coping responses: engaged coping (e.g. hearing aids, communication tactics) and disengaged coping (e.g. withdrawal from situations, withdrawal within situations): both had perceived advantages and disadvantages. Conclusions: This novel application of the self-regulatory model demonstrates that it can be used to capture the key psychosocial experiences (i.e. perceptions, emotions, and coping responses) of adults with mild-moderate hearing loss within a single, unifying framework

    The persisting burden of invasive pneumococcal disease in HIV patients: an observational cohort study

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    <p>Abstract</p> <p>Background</p> <p>The increasing use of highly active antiretroviral therapy (HAART) and pneumococcal immunization along with shifting community exposures may have altered the burden of <it>Streptococcus pneumoniae </it>disease in HIV-infected persons. We describe the burden and risk factors for pneumococcal disease in the modern era of HIV care and evaluate the use of a 23-valent pneumococcal polysaccharide vaccine (PPV-23).</p> <p>Methods</p> <p>The incidence of invasive pneumococcal disease (IPD) between January 1<sup>st</sup>, 2000 and January 1<sup>st</sup>, 2010 in a regional HIV population in Southern Alberta, Canada was determined by linking comprehensive laboratory and hospital surveillance data. Clinical and epidemiologic data including risk factors for <it>S. pneumoniae</it>, history of pneumococcal immunization, serotypes of infections, and length of any hospitalizations for pneumococcal disease were evaluated with multivariate analysis. CD4 count and viral load at immunization were evaluated with a nested case-control analysis.</p> <p>Results</p> <p>In 1946 HIV-patients with 11,099 person-years of follow up, there were 68 distinct episodes of pneumococcal disease occurring in 50 patients. Increased risk was seen if female, age >60, Aboriginal ethnicity, lower education, injection drug use, smoking, nadir CD4 <200/μL, chronic obstructive pulmonary disease, and hepatitis C. Overall, the incidence of IPD was 342/100,000 person-years and was reduced to 187/100,000 within three years of PPV-23 immunization (P < 0.01). Although 78% of patients received PPV-23, 74% of IPD episodes were caused by PPV-23 serotypes. In a case-control analysis, HIV viral load at immunization was significantly predictive of PPV-23 failure, while CD4 count was not. 80% of IPD cases required hospitalization: median length of stay was 7 days (range: 1-71); four patients died.</p> <p>Conclusions</p> <p>Despite universal access to intensive measures to prevent pneumococcal disease including the widespread use of HAART and PPV-23 immunization, the incidence of IPD remains high in HIV patients with its associated morbidity and mortality.</p

    Original Climax Films: historicizing the British hardcore pornography film business

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    This article presents findings from my research into the British hardcore pornography business. Porn studies has given little coverage to the British pornography business, with much of the academic literature focusing on the American adult entertainment industry. Recently, there has been a rising interest in the historical framework of porn cinemas both in popular culture and in academic work. This article contributes to this debate, taking both a cultural and an economic approach to explore the conditions that led to the emergence of British hardcore production as an alternative economy in the 1960s. In this economy, entrepreneurs make use of new technologies to produce artefacts that are exchanged for an economic benefit, while circumventing laws to distribute their artefacts. To historicize this economy, I draw on ethnohistorical research, which includes interviews with people involved in the British hardcore business and archival research. I argue that a combination of glamour filmmaking, a relaxation of political and cultural attitudes towards sexuality, the location of Soho, London, and emerging technologies for producing films collectively contribute to the emergence of an alternative economy of British hardcore production. I focus specifically on the practices of two entrepreneurs within this economy, Ivor Cook and Mike Freeman, considering how their actions inadvertently created the British hardcore film business, and played a significant role in the development of hardcore production outside of the United Kingdom
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