27,227 research outputs found

    Approximate solution to the CGHS field equations for two-dimensional evaporating black holes

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    Callan, Giddings, Harvey and Strominger (CGHS) previously introduced a two-dimensional semiclassical model of gravity coupled to a dilaton and to matter fields. Their model yields a system of field equations which may describe the formation of a black hole in gravitational collapse as well as its subsequent evaporation. Here we present an approximate analytical solution to the semiclassical CGHS field equations. This solution is constructed using the recently-introduced formalism of flux-conserving hyperbolic systems. We also explore the asymptotic behavior at the horizon of the evaporating black hole

    Ultrasound guided glenohumeral injections in adhesive capsulitis

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    Thesis (M.A.)--Boston UniversityObjective: The objective of this thesis was to assess outcomes of glenohumeral corticosteroid injections for adhesive capsulitis. Design: The thesis was composed of two parts. First, a systematic literature review was conducted on glenohumeral corticosteroid injections on shoulder outcomes for adhesive capsulitis. Second, an original prospective study was conducted to measure the effect of ultrasound-guided injections on pain and function for adhesive capsulitis patients. Setting: All injections for the prospective injection study were conducted at Brigham and Women’s Hospital in Boston, MA. Patients: Inclusion criteria were patients receiving an ultrasound guided injection for adhesive capsulitis. 67 patients were included, 59 patients were available at first follow up, and 40 patients were available at final follow up. Methods: The literature review was conducted using the online databases PubMed (1966-present), Embase (1947-present), Web of Science (1900– present), and the Cochrane Central Register of Controlled Trials. Study criteria were limited to clinical trials that evaluated the application of corticosteroid injections, both alone and in combination with other treatment modalities, specifically for the condition of adhesive capsulitis in the shoulder. Studies involving non-corticosteroid injections or injections for conditions not specific to adhesive capsulitis were excluded. Results were limited to papers in the English language. A data table summarizing pain, function, and range of motion outcomes of each treatment was produced. A percent change from baseline was calculated to facilitate comparisons. For the injection study, the first follow-up took place after an average of 2.0 months and patients' improvement in pain and range of motion were assessed. During a final follow-up after an average of 10.4 months, patients’ pain and shoulder function scores were assessed over telephone. [TRUNCATED

    Charged null fluid and the weak energy condition

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    Uses the Einstein-Maxwell field equations to derive the fundamental equation of motion for charged null fluid. This equation of motion includes a Lorentz force term. Using this equation, it is shown that charged null fluid always satisfies the weak energy condition. This result is in contrast to previous interpretations of the charged Vaidya solution (a special case of a charged null fluid), which produced violations of the weak energy condition. The errors in the previous interpretations are explained. The new interpretation is then applied explicitly to the charged Vaidya solution
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