628 research outputs found

    Yakhot's model of strong turbulence: A generalization of scaling models of turbulence

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    We report on some implications of the theory of turbulence developed by V. Yakhot [V. Yakhot, Phys. Rev. E {\bf 57}(2) (1998)]. In particular we focus on the expression for the scaling exponents ζn\zeta_{n}. We show that Yakhot's result contains three well known scaling models as special cases, namely K41, K62 and the theory by V. L'vov and I. Procaccia [V. L'vov & I. Procaccia, Phys. Rev. E {\bf 62}(6) (2000)]. The model furthermore yields a theoretical justification for the method of extended self--similarity (ESS).Comment: 8 page

    Algebraic Structures and Eigenstates for Integrable Collective Field Theories

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    Conditions for the construction of polynomial eigen--operators for the Hamiltonian of collective string field theories are explored. Such eigen--operators arise for only one monomial potential v(x)=μx2v(x) = \mu x^2 in the collective field theory. They form a ww_{\infty}--algebra isomorphic to the algebra of vertex operators in 2d gravity. Polynomial potentials of orders only strictly larger or smaller than 2 have no non--zero--energy polynomial eigen--operators. This analysis leads us to consider a particular potential v(x)=μx2+g/x2v(x)= \mu x^2 + g/x^2. A Lie algebra of polynomial eigen--operators is then constructed for this potential. It is a symmetric 2--index Lie algebra, also represented as a sub--algebra of U(s(2)).U (s\ell (2)).Comment: 27 page

    “I wouldn’t know what to do with the breasts”: the impact of patient gender on medical student confidence and comfort in clinical skills

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    Background: Previous research has found a relationship between students’ gender and attitudes surrounding peer physical examination, but relationship between patient gender and confidence/comfort is less clear. We explored whether patient gender affects medical students’ levels of confidence and comfort in clinical examination skills. Methods: An electronic survey and focus groups were conducted with medical students from one UK institution. Students reported levels of confidence/comfort when carrying out clinical examinations on men/women. An inductive thematic analysis was performed. Results:    Of a total of 1500 students provided with the opportunity to participate, ninety (6%) responded. For cardiovascular and respiratory examinations, confidence/comfort were higher when examining male-presenting patients. The opposite was true for mental state examinations. Barriers to confidence/comfort included perceiving males as a norm, difficulty navigating breasts, tutors’ internalised gendered attitudes and a wider sociocultural issue. Facilitators of confidence/comfort included students relating to patients, embodying a professional role, gender blindness, and authentic clinical environments. Fewer than 20% (n = 18) of students felt they had enough opportunity to practice clinical skills on women, versus 90% (n = 82) on men. Conclusion: Our study identified an area where students’ confidence and comfort in clinical examinations could be enhanced within medical education. Changes were implemented in the institution under study’s vocational skills teaching, which is rooted in general practice. Information on gender and clinical skills was provided within course handbooks, time was scheduled to discuss gender and clinical skills in small group settings, and equitable gender representation was ensured in clinical assessment

    Clinical Outcomes and Survival Following Treatment of Metastatic Castrate-Refractory Prostate Cancer With Docetaxel Alone or With Strontium-89, Zoledronic Acid, or Both

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    Importance Bony metastatic castrate-refractory prostate cancer (CRPC) has a poor prognosis and high morbidity. Zoledronic acid (ZA) is commonly combined with docetaxel in practice but lacks evidence that combining is effective, and strontium-89 (Sr89) is generally used palliatively in patients unfit for chemotherapy. Phase 2 analysis of the TRAPEZE trial confirmed combining the agents was safe and feasible, and the objectives of phase 3 include assessment of the treatments on survival. Objective To determine clinical effectiveness and cost-effectiveness of combining docetaxel, ZA, and Sr89, all having palliative benefits and used in bony metastatic CRPC to control bone symptoms and, for docetaxel, to prolong survival. Design, Setting, and Participants The TRAPEZE trial is a 2 × 2 factorial trial comparing docetaxel alone or with ZA, Sr89, or both. A cohort of 757 participants were recruited between February 2005 and February 2012 from hospitals in the United Kingdom. Overall, 169 participants (45%) had received palliative radiotherapy, and the median (IQR) prostate-specific antigen level was 146 (51-354). Follow-ups were performed for at least 12 months. Interventions Up to 10 cycles of docetaxel alone; docetaxel with ZA; docetaxel with a single Sr89 dose after 6 cycles; or docetaxel with both ZA and Sr89. Main Outcomes and Measures Primary outcomes included clinical progression-free survival (CPFS) (pain progression, skeletal-related events [SREs], or death) and cost-effectiveness. Secondary outcomes included SRE-free interval, pain progression–free interval, total SREs, and overall survival (OS). Results Overall, of 757 participants, 349 (46%) completed docetaxel treatment. Median (IQR) age was 68 (63-73) years. Clinical progression-free survival did not reach statistical significance for either Sr89 or ZA. Cox regression analysis adjusted for all stratification variables showed benefit of Sr89 on CPFS (hazard ratio [HR], 0.85; 95% CI, 0.73-0.99; P = .03) and confirmed no effect of ZA (HR, 0.98; 95% CI, 0.85-1.14; P = .81); ZA had a significant effect on SRE-free interval (HR, 0.78; 95% CI, 0.65-0.95; P = .01). For OS, there was no effect of either Sr89 (HR, 0.92; 95% CI, 0.79-1.08; P = 0.34) or ZA (HR, 0.99; 95% CI, 0.84-1.16; P = 0.91). Conclusions and Relevance Strontium-89 combined with docetaxel improved CPFS but did not improve OS, SRE-free interval, or total SREs; ZA did not improve CPFS or OS but did significantly improve median SRE-free interval and reduced total SREs by around one-third, suggesting a role as postchemotherapy maintenance therapy

    The role of Central Asian uplift in East Asian Monsoon circulation and its palaeoclimate implication

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    It has been clearly established that the climate of Asia is significantly affected by high-elevation orogens such as the Tibetan Plateau, Mongolian Plateau and Tian-Shan. The East Asian Monsoon (EAM), one of the most prominent features of Asian climate, has been well studied in a modern context and its dynamics are generally well understood. However, specific features of the EAM are less studied and understood in a palaeoclimate context, largely because of associated uncertainties in palaeotopography for the Cenozoic era. Here, we investigate changes in the individual stages of the EAM in response to increasing topography over Central Asia. We perform a series of sensitivity experiments with different palaeogeographic elevations using a coupled ocean-atmosphere General Circulation Model (HadCM3), to investigate seasonal variability of the EAM, and investigate the emergent critical threshold in elevation where the patterns of atmospheric circulation and climate over Asia attains the characteristics observed in the modern climate system. Our results indicate that above an elevation threshold of 3000 m, EAM circulation follows the modern pattern, but below that threshold, EAM circulation and precipitation follow a distinctly different pattern, where the westerly jet does not propagate into the higher latitudes and monsoonal precipitation is limited to June and July. This shift in circulation pattern has important implications for the successful interpretation of proxy-based palaeoclimate and environmental reconstructions. In addition, our results emphasize the importance of the latitudinal position of high-elevation on the EAM circulation, by showing that low-elevation can produce modern-like EAM conditions, if located at different latitudes than modern

    The fuzzy S^2 structure of M2-M5 systems in ABJM membrane theories

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    We analyse the fluctuations of the ground-state/funnel solutions proposed to describe M2-M5 systems in the level-k mass-deformed/pure Chern-Simons-matter ABJM theory of multiple membranes. We show that in the large N limit the fluctuations approach the space of functions on the 2-sphere rather than the naively expected 3-sphere. This is a novel realisation of the fuzzy 2-sphere in the context of Matrix Theories, which uses bifundamental instead of adjoint scalars. Starting from the multiple M2-brane action, a U(1) Yang-Mills theory on R^{2,1} x S^2 is recovered at large N, which is consistent with a single D4-brane interpretation in Type IIA string theory. This is as expected at large k, where the semiclassical analysis is valid. Several aspects of the fluctuation analysis, the ground-state/funnel solutions and the mass-deformed/pure ABJM equations can be understood in terms of a discrete noncommutative realisation of the Hopf fibration. We discuss the implications for the possibility of finding an M2-brane worldvolume derivation of the classical S^3 geometry of the M2-M5 system. Using a rewriting of the equations of the SO(4)-covariant fuzzy 3-sphere construction, we also directly compare this fuzzy 3-sphere against the ABJM ground-state/funnel solutions and show them to be different.Comment: 60 pages, Latex; v2: references added; v3: typos corrected and references adde

    New approaches in W-gravities

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    We have devoted an effort to study some nonlinear actions, characteristics of the W{\cal W}-theories, in the framework of the soldering formalism. We have disclosed interesting new results concerning the embedding of the original chiral W{\cal W}-particles in different metrical spaces in the final soldered action, i.e., the metric gets modified by the soldering interference process. The results are presented in a weak field approximation for the WN{\cal W}_N case when N is greater than 3 and also in an exact way for W2{\cal W}_2. We have promoted a generalization of the interference phenomena to WN{\cal W}_N-theories of different chiralities and shown that the geometrical features introduced can yield a new understanding about the interference formalism in quantum field theories.Comment: 28 pages, Late

    Application of phage display to high throughput antibody generation and characterization.

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    We have created a high quality phage display library containing over 1010 human antibodies and describe its use in the generation of antibodies on an unprecedented scale. We have selected, screened and sequenced over 38,000 recombinant antibodies to 292 antigens, yielding over 7,200 unique clones. 4,400 antibodies were characterized by specificity testing and detailed sequence analysis and the data/clones are available online. Sensitive detection was demonstrated in a bead based flow cytometry assay. Furthermore, positive staining by immunohistochemistry on tissue microarrays was found for 37% (143/381) of antibodies. Thus, we have demonstrated the potential of and illuminated the issues associated with genome-wide monoclonal antibody generation.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

    Centrality Dependence of the High p_T Charged Hadron Suppression in Au+Au collisions at sqrt(s_NN) = 130 GeV

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    PHENIX has measured the centrality dependence of charged hadron p_T spectra from central Au+Au collisions at sqrt(s_NN)=130 GeV. The truncated mean p_T decreases with centrality for p_T > 2 GeV/c, indicating an apparent reduction of the contribution from hard scattering to high p_T hadron production. For central collisions the yield at high p_T is shown to be suppressed compared to binary nucleon-nucleon collision scaling of p+p data. This suppression is monotonically increasing with centrality, but most of the change occurs below 30% centrality, i.e. for collisions with less than about 140 participating nucleons. The observed p_T and centrality dependence is consistent with the particle production predicted by models including hard scattering and subsequent energy loss of the scattered partons in the dense matter created in the collisions.Comment: 7 pages text, LaTeX, 6 figures, 2 tables, 307 authors, resubmitted to Phys. Lett. B. Revised to address referee concerns. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are publicly available at http://www.phenix.bnl.gov/phenix/WWW/run/phenix/papers.htm

    Measurement of the p-pbar -> Wgamma + X cross section at sqrt(s) = 1.96 TeV and WWgamma anomalous coupling limits

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    The WWgamma triple gauge boson coupling parameters are studied using p-pbar -> l nu gamma + X (l = e,mu) events at sqrt(s) = 1.96 TeV. The data were collected with the DO detector from an integrated luminosity of 162 pb^{-1} delivered by the Fermilab Tevatron Collider. The cross section times branching fraction for p-pbar -> W(gamma) + X -> l nu gamma + X with E_T^{gamma} > 8 GeV and Delta R_{l gamma} > 0.7 is 14.8 +/- 1.6 (stat) +/- 1.0 (syst) +/- 1.0 (lum) pb. The one-dimensional 95% confidence level limits on anomalous couplings are -0.88 < Delta kappa_{gamma} < 0.96 and -0.20 < lambda_{gamma} < 0.20.Comment: Submitted to Phys. Rev. D Rapid Communication
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