85 research outputs found

    Chern-simon type photon mass from fermion electric dipole moments at finite temperature in 3+1 dimensions

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    We study the low energy effective field theory of fermions with electric and magnetic dipole moments at finite temperature. We find that at one loop there is an interaction term of the Chern-Simon form LI=mμ AνF~μν{\cal L_I}=m_\mu\>A_\nu {\tilde F}^{\mu\nu}. The four vector mμ≃diμimi2 ∂μ (lnT)m_\mu \simeq d_i \mu_i m_i^2 ~{\partial_\mu}\>(ln T) is interpreted as a Chern- Simon type mass of photons, which is determined by the electric (magnetic) dipole moments did_i (μi\mu_i) of the fermions in the vacuum polarisation loop diagram. The physical consequence of such a photon mass is that, photons of opposite circular polarisations, propagating through a hot medium, have different group velocities. We estimate that the time lag between the arrival times of the left and right circularly polarised light signals from pulsars. If the light propagates through a hot plasma (where the temperature in some regions is T∼100MeVT \sim 100 MeV) then the time lag between the two circularly polarised signals of frequency ω\omega will be Δt(ω)≃10−6/ω\Delta t(\omega) \simeq 10^{-6} /\omega. It may be possible to observe this effect in pulsar signals which propagate through nebula at high temperatures.Comment: plain TeX, 9 page

    Black hole determinants and quasinormal modes

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    We derive an expression for functional determinants in thermal spacetimes as a product over the corresponding quasinormal modes. As simple applications we give efficient computations of scalar determinants in thermal AdS, BTZ black hole and de Sitter spacetimes. We emphasize the conceptual utility of our formula for discussing `1/N' corrections to strongly coupled field theories via the holographic correspondence.Comment: 28 pages. v2: slightly improved exposition, references adde

    Lectures on holographic methods for condensed matter physics

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    These notes are loosely based on lectures given at the CERN Winter School on Supergravity, Strings and Gauge theories, February 2009 and at the IPM String School in Tehran, April 2009. I have focused on a few concrete topics and also on addressing questions that have arisen repeatedly. Background condensed matter physics material is included as motivation and easy reference for the high energy physics community. The discussion of holographic techniques progresses from equilibrium, to transport and to superconductivity.Comment: 1+85 pages. 15 figures. v2: typos fixed and references added. v3: another typo fixe

    Reduced Quantitative Ultrasound Bone Mineral Density in HIV-Infected Patients on Antiretroviral Therapy in Senegal

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    Background: Bone status in HIV-infected patients on antiretroviral treatment (ART) is poorly documented in resource-limited settings. We compared bone mineral density between HIV-infected patients and control subjects from Dakar, Senegal. Methods: A total of 207 (134 women and 73 men) HIV-infected patients from an observational cohort in Dakar (ANRS 1215) and 207 age-and sex-matched controls from the general population were enrolled. Bone mineral density was assessed by quantitative ultrasound (QUS) at the calcaneus, an alternative to the reference method (i.e. dual X-absorptiometry), often not available in resource-limited countries. Results: Mean age was 47.0 (+/- 8.5) years. Patients had received ART for a median duration of 8.8 years; 45% received a protease inhibitor and 27% tenofovir; 84% had undetectable viral load. Patients had lower body mass index (BMI) than controls (23 versus 26 kg/m(2), P<0.001). In unadjusted analysis, QUS bone mineral density was lower in HIV-infected patients than in controls (difference: -0.36 standard deviation, 95% confidence interval (CI): -0.59;-0.12, P = 0.003). Adjusting for BMI, physical activity, smoking and calcium intake attenuated the difference (-0.27, CI: -0.53; -0.002, P = 0.05). Differences in BMI between patients and controls explained a third of the difference in QUS bone mineral density. Among patients, BMI was independently associated with QUS bone mineral density (P<0.001). An association between undetectable viral load and QUS bone density was also suggested (beta = 0.48, CI: 0.02; 0.93; P = 0.04). No association between protease inhibitor or tenofovir use and QUS bone mineral density was found. Conclusion: Senegalese HIV-infected patients had reduced QUS bone mineral density in comparison with control subjects, in part related to their lower BMI. Further investigation is needed to clarify the clinical significance of these observations

    The immediate and long-term effects of exercise and patient education on physical, functional, and quality-of-life outcome measures after single-level lumbar microdiscectomy: a randomized controlled trial protocol

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    BACKGROUND: Low back pain remains a costly quality-of-life-related health problem. Microdiscectomy is often the surgical procedure of choice for a symptomatic, single-level, lumbar disc herniation in younger and middle-aged adults. The question of whether a post-microdiscectomy exercise program enhances function, quality of life, and disability status has not been systematically explored. Thus, the overall purpose of this study is to assess immediate and long-term outcomes of an exercise program, developed at University of Southern California (USC), targeting the trunk and lower extremities (USC Spine Exercise Program) for persons who have undergone a single-level microdiscectomy for the first time. METHODS/DESIGN: One hundred individuals between the ages of 18 and 60 who consent to undergo lumbar microdiscectomy will be recruited to participate in this study. Subjects will be randomly assigned to one of two groups: 1) one session of back care education, or 2) a back care education session followed by the 12-week USC Spine Exercise Program. The outcome examiners (evaluators), as well as the data managers, will be blinded to group allocation. Education will consist of a one-hour "one-on-one" session with the intervention therapist, guided by an educational booklet specifically designed for post-microdiscectomy care. This session will occur four to six weeks after surgery. The USC Spine Exercise Program consists of two parts: back extensor strength and endurance, and mat and upright therapeutic exercises. This exercise program is goal-oriented, performance-based, and periodized. It will begin two to three days after the education session, and will occur three times a week for 12 weeks. Primary outcome measures include the Oswestry Disability Questionnaire, Roland-Morris Disability Questionnaire, SF-36(® )quality of life assessment, Subjective Quality of Life Scale, 50-foot Walk, Repeated Sit-to-Stand, and a modified Sorensen test. The outcome measures in the study will be assessed before and after the 12-week post-surgical intervention program. Long-term follow up assessments will occur every six months beginning one year after surgery and ending five years after surgery. Immediate and long-term effects will be assessed using repeated measures multivariate analysis of variance (MANOVA). If significant interactions are found, one-way ANOVAs will be performed followed by post-hoc testing to determine statistically significant pairwise comparisons. DISCUSSION: We have presented the rationale and design for a randomized controlled trial evaluating the effectiveness of a treatment regimen for people who have undergone a single-level lumbar microdiscectomy

    The effectiveness of home versus community-based weight control programmes initiated soon after breast cancer diagnosis: a randomised controlled trial

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    BackgroundBreast cancer diagnosis may be a teachable moment for lifestyle behaviour change and to prevent adjuvant therapy associated weight gain. We assessed the acceptability and effectiveness of two weight control programmes initiated soon after breast cancer diagnosis to reduce weight amongst overweight or obese women and prevent gains in normal-weight women.MethodsOverweight or obese (n?=?243) and normal weight (n?=?166) women were randomised to a three-month unsupervised home (home), a supervised community weight control programme (community) or to standard written advice (control). Primary end points were change in weight and body fat at 12 months. Secondary end points included change in insulin, cardiovascular risk markers, quality of life and cost-effectiveness of the programmes.ResultsForty-three percent of eligible women were recruited. Both programmes reduced weight and body fat: home vs. control mean (95% CI); weight ?2.3 (?3.5, ?1.0) kg, body fat ?1.6 (?2.6, ?0.7) kg, community vs. control; weight ?2.4 (?3.6, ?1.1) kg, body fat ?1.4 (?2.4, ?0.5) kg (all p?&#x3c;?0.001). The community group increased physical activity, reduced insulin, cardiovascular disease risk markers, increased QOL and was cost-effective.ConclusionsThe programmes were equally effective for weight control, but the community programme had additional benefits.Clinical trial registrationISRCTN6857614

    Proceedings of the Thirteenth International Society of Sports Nutrition (ISSN) Conference and Expo

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    Meeting Abstracts: Proceedings of the Thirteenth International Society of Sports Nutrition (ISSN) Conference and Expo Clearwater Beach, FL, USA. 9-11 June 201

    The Influence of Episodic Future Thinking and Graphic Warning Labels on Delay Discounting and Cigarette Demand

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    Delay discounting and operant demand are two behavioral economic constructs that tend to covary, by degree, with cigarette smoking status. Given historically robust associations between adverse health outcomes of smoking, a strong preference for immediate reinforcement (measured with delay discounting), and excessive motivation to smoke cigarettes (measured with operant demand), researchers have made numerous attempts to attenuate the extent to which behaviors corresponding to these constructs acutely appear in smokers. One approach is episodic future thinking, which can reportedly increase the impact of future events on present decision making as well as reduce the reinforcing value of cigarettes. Graphic cigarette pack warning labels may also reduce smoking by increased future orientation. Experiment 1 evaluated the combined effects of episodic future thinking and graphic warning labels on delay discounting; Experiment 2 evaluated solely the effects of episodic future thinking on delay discounting and operant demand. We observed no statistically significant effects of episodic future thinking when combined with graphic warning labels or when assessed on its own. These results serve as a call for further research on the boundary conditions of experimental techniques reported to alter behaviors associated with cigarette smoking

    Letter to the Editor: Subdermal contraceptive implant-related neuropathy of the upper limb: A time for change

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    According to the World Health Organisation, the subdermal contraceptive implant (SCI) is one of the most commonly prescribed contraceptives worldwide. The Nexplanon device, containing 68 mg etonogestrel, is listed as one of the most effective contraceptives, with a reported Pearl Index of 0.00 (95% CI, 0.00–0.14). 1 Nexplanon is the current licensed SCI within the UK and Ireland, replacing its predecessor the Implanon. Although serious adverse events are rare, significant morbidity has been identified in clinical practice (1.7% incidence) occurring at the time of Implanon device insertion (deep plane insertion and migration) and removal (injury to neurovascular structures - Median nerve, Medial Antebrachial Cutaneous Nerve, Ulnar nerve, and Brachial Artery2 ). Sequelae for the affected young female cohort include upper limb neuropathic pain, sensorimotor deficits3 and psychosocial dysfunction negatively impacting upon their quality of life.</p
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