547 research outputs found

    Pion and Vector Meson Form Factors in the Kuperstein-Sonnenschein holographic model

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    We study phenomenological aspects of the holographic model of chiral symmetry breaking recently introduced by Kuperstein and Sonnenschein (KS). As a first step, we calculate the spectrum of vector and axial-vector mesons in the KS model. We numerically compute various coupling constants of the mesons and pions. Our analysis indicates that vector meson dominance is realized in this model. The pion, vector meson and axial-vector meson form factors are obtained and studied in detail. We find good agreement with QCD results. In particular, the pion form factor closely matches available experimental data.Comment: v1: 27 pages, 9 figures, 4 tables; v2: minor changes, added more general discussion of vector meson dominance; v3: minor changes and additions, version accepted for publication in JHE

    Standardised assessment of personality – a study of validity and reliability in substance abusers

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    <p>Abstract</p> <p>Background</p> <p>Brief screening instruments for co-morbid personality disorders could potentially have great value in substance abuse treatment settings.</p> <p>Methods</p> <p>We assessed the psychometric properties of the 8-item Standardised Assessment of Personality – Abbreviated Scale (SAPAS) in a sample of 58 methadone maintenance patients.</p> <p>Results</p> <p>Internal consistency was modest, but similar to the original value (alpha = 0.62), and test-retest correlation at four months follow-up was moderately encouraging for a short instrument such as this (n = 31, test retest intraclass correlation = 0.58), and change at the mean level was minimal, but marginally significant (from an average of 3.3 to 3.8, p = 0.06). Analyses of nurse ratings of patients' behaviour at the clinic showed that SAPAS was significantly correlated with nurse ratings of externalizing behaviour (r = 0.42, p = 0.001), and Global Assessment of Functioning (r = -0.36, p = 0.006), but unrelated to intoxication (r = 0.02, NS), or withdrawal (r = 0.20, NS).</p> <p>Conclusion</p> <p>There is evidence that the SAPAS is a modestly valid and relatively reliable brief screening measure of personality disorders in patients with ongoing substance abuse undergoing methadone maintenance. It can be used in situations where limited resources are available, and researchers or others wish to get an impression of the degree of personality pathology in a clinical population, as well as for screening purposes.</p

    Use of zinc phosphate cement as a luting agent for Denzir™ copings: an in vitro study

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    BACKGROUND: The clinical success rate with zinc phosphate cemented Procera crowns is high. The objective with this study was to determine whether CADCAM processed and zinc phosphate cemented Denzir copings would perform as well as zinc phosphate cemented Procera copings when tested in vitro in tension. METHODS: Twelve Procera copings and twenty-four Denzir copings were made. After the copings had been made, twelve of the Denzir copings were sandblasted on their internal surfaces. All copings were then cemented with zinc phosphate cement to carbon steel dies and transferred to water or artificial saliva. Two weeks after cementation, half of the samples were tested. The remaining samples were tested after one year in the storage medium. All tests were done in tension and evaluated with an ANOVA. RESULTS: Sandblasted and un-sandblasted Denzir copings performed as well as Procera copings. Storage in water or artificial saliva up to one year did not decrease the force needed to dislodge any of the coping groups. Three copings fractured during testing and one coping developed a crack during testing. The three complete fractures occurred in Procera copings, while the partly cracked coping was a Denzir coping. CONCLUSION: No significant differences existed between the different material groups, and the retentive force increased rather than decreased with time. Fewer fractures occurred in Denzir copings, explained by the higher fracture toughness of the Denzir material. Based on good clinical results with zinc phosphate cemented Procera crowns, we foresee that zinc phosphate cement luted Denzir copings are likely to perform well clinically

    Quasi-Normal Modes of Stars and Black Holes

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    Perturbations of stars and black holes have been one of the main topics of relativistic astrophysics for the last few decades. They are of particular importance today, because of their relevance to gravitational wave astronomy. In this review we present the theory of quasi-normal modes of compact objects from both the mathematical and astrophysical points of view. The discussion includes perturbations of black holes (Schwarzschild, Reissner-Nordstr\"om, Kerr and Kerr-Newman) and relativistic stars (non-rotating and slowly-rotating). The properties of the various families of quasi-normal modes are described, and numerical techniques for calculating quasi-normal modes reviewed. The successes, as well as the limits, of perturbation theory are presented, and its role in the emerging era of numerical relativity and supercomputers is discussed.Comment: 74 pages, 7 figures, Review article for "Living Reviews in Relativity

    Validity of the disabilities of the Arm, Shoulder and Hand patient-reported outcome measure (DASH) and the Quickdash when used in Dupuytren’s disease

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    This study investigated aspects of the validity and reliability of the 30-item Disabilities of the Arm, Shoulder and Hand patient-reported outcome measure (DASH) and its relationship with the shorter 11-item QuickDASH in patients with Dupuytren’s disease. Seven hundred and fifty-nine DASH questionnaires were studied, covering pre- and postoperative patients undergoing different treatments for Dupuytren’s disease. Items related to pain rose early after treatment before returning to baseline, suggesting that studying pain is relevant during postoperative recovery. Across all 759 sets of responses, the QuickDASH agreed closely with the DASH. In exploratory factor analysis, the DASH was not unidimensional, questioning the validity of the DASH summary score in Dupuytren’s disease. Further validation of existing PROMs for use in Dupuytren’s disease is needed. These data suggest that pain is a relevant symptom to study during postoperative recovery following treatment for Dupuytren’s disease

    BMI, Diet and Female Reproductive Factors as Risks for Thyroid Cancer: A Systematic Review

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    Background: Thyroid cancer incidence rates have been increasing worldwide but the reason behind this is unclear. Both the increasing use of diagnostic technologies allowing the detection of thyroid cancer and a true increase in thyroid cancer incidence have been proposed. This review assesses the role of body mass index (BMI), diet, and reproductive factors on the thyroid cancer trend. Methods: Epidemiologic studies of the selected risk factors up to June 2010 were reviewed and critically assessed. Results: Among the thirty-seven studies reviewed and despite variation in the risk estimates, most papers supported a small but positive association for BMI (risk estimate range: 1.1–2.3 in males and 1.0–7.4 in females.). Among specific dietary components, there was no consistent association of thyroid cancer risk with iodine intake through fortification (risk estimate range: 0.49–1.6) or fish consumption (risk estimate range 0.6–2.2), nor with diets high in cruciferous vegetables (risk estimate range 0.6–1.9). A small number of studies showed a consistent protective effect of diets high in non-cruciferous vegetable (risk estimate range: 0.71–0.92). Among reproductive factors (pregnancy, parity, number of live births, use of prescription hormones, menstrual cycle regularity, and menopausal status), none were consistently associated with higher thyroid cancer risk. Conclusions: BMI had the strongest link to thyroid cancer risk among those examined. Detailed examinations of populationleve

    Problems in obtaining precise and accurate Sr isotope analysis from geological materials using laser ablation MC-ICPMS

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    This paper reviews the problems encountered in eleven studies of Sr isotope analysis using laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICPMS) in the period 1995–2006. This technique has been shown to have great potential, but the accuracy and precision are limited by: (1) large instrumental mass discrimination, (2) laser-induced isotopic and elemental fractionations and (3) molecular interferences. The most important isobaric interferences are Kr and Rb, whereas Ca dimer/argides and doubly charged rare earth elements (REE) are limited to sample materials which contain substantial amounts of these elements. With modern laser (193 nm) and MC-ICPMS equipment, minerals with >500 ppm Sr content can be analysed with a precision of better than 100 ppm and a spatial resolution (spot size) of approximately 100 μm. The LA MC-ICPMS analysis of 87Sr/86Sr of both carbonate material and plagioclase is successful in all reported studies, although the higher 84Sr/86Sr ratios do suggest in some cases an influence of Ca dimer and/or argides. High Rb/Sr (>0.01) materials have been successfully analysed by carefully measuring the 85Rb/87Rb in standard material and by applying the standard-sample bracketing method for accurate Rb corrections. However, published LA-MC-ICPMS data on clinopyroxene, apatite and sphene records differences when compared with 87Sr/86Sr measured by thermal ionisation mass spectrometry (TIMS) and solution MC-ICPMS. This suggests that further studies are required to ensure that the most optimal correction methods are applied for all isobaric interferences

    Measurement of CP-violation asymmetries in D0 to Ks pi+ pi-

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    We report a measurement of time-integrated CP-violation asymmetries in the resonant substructure of the three-body decay D0 to Ks pi+ pi- using CDF II data corresponding to 6.0 invfb of integrated luminosity from Tevatron ppbar collisions at sqrt(s) = 1.96 TeV. The charm mesons used in this analysis come from D*+(2010) to D0 pi+ and D*-(2010) to D0bar pi-, where the production flavor of the charm meson is determined by the charge of the accompanying pion. We apply a Dalitz-amplitude analysis for the description of the dynamic decay structure and use two complementary approaches, namely a full Dalitz-plot fit employing the isobar model for the contributing resonances and a model-independent bin-by-bin comparison of the D0 and D0bar Dalitz plots. We find no CP-violation effects and measure an asymmetry of ACP = (-0.05 +- 0.57 (stat) +- 0.54 (syst))% for the overall integrated CP-violation asymmetry, consistent with the standard model prediction.Comment: 15 page
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