Objective structured clinical examinations (OSCEs), psychiatry and the clinical assessment of skills and competencies (CASC) : same evidence, different judgement

Background: The Objective Structured Clinical Examination (OSCE), originally developed in the 1970’s, has been hailed as the "gold standard" of clinical assessments for medical students and is used within medical schools throughout the world. The Clinical assessment of Skills and Competencies (CASC) is an OSCE used as a clinical examination gateway, granting access to becoming a senior Psychiatrist in the UK. Discussion: Van der Vleuten’s utility model is used to examine the CASC from the viewpoint of a senior psychiatrist. Reliability may be equivalent to more traditional examinations. Whilst the CASC is likely to have content validity, other forms of validity are untested and authenticity is poor. Educational impact has the potential to change facets of psychiatric professionalism and influence future patient care. There are doubts about acceptability from candidates and more senior psychiatrists. Summary: Whilst OSCEs may be the best choice for medical student examinations, their use in post graduate psychiatric examination in the UK is subject to challenge on the grounds of validity, authenticity and educational impact

MCFM for the Tevatron and the LHC

A summary is given of the current status of the next-to-leading order (NLO) parton-level integrator MCFM. Some details are given about the Higgs + 2-jet process and the production and decay of $t \bar{t}$, both of which have recently been added to the code. Using MCFM, comparisons between the Tevatron running at $\sqrt{s}=2$~TeV and the LHC running at $\sqrt{s}=7$~TeV are made for standard model process including the production of Higgs bosons. The case for running the Tevatron until 16fb$^{-1}$ are accumulated by both detectors is sketched.Comment: Talk presented by R.K Ellis at Loops and Legs in Quantum Field Theory 2010, Woerlitz, Germany, April 25-30, 2010, (6 pages and 4 figures

QCD corrections to the hadronic production of a heavy quark pair and a W-boson including decay correlations

We perform an analytic calculation of the one-loop amplitude for the W-boson mediated process 0 \to d u-bar Q Q-bar l-bar l, retaining the mass for the quark Q. The momentum of each of the massive quarks is expressed as the sum of two massless momenta and the corresponding heavy quark spinor is expressed as a sum of two massless spinors. Using a special choice for the heavy quark spinors we obtain analytic expressions for the one-loop amplitudes which are amenable to fast numerical evaluation. The full next-to-leading order (NLO) calculation of hadron+hadron \to W(\to e nu) b b-bar with massive b-quarks is included in the program MCFM. A comparison is performed with previous published work.Comment: 45 pages, 17 figure

Magneto-optical determination of the electron-solid phase-boundary

We have obtained a two-dimensional electron-solid phase diagram in the extreme magnetic quantum limit by studying the temperature dependence of the radiative recombination of electrons in a GaAs/AlxGa1-xAs heterojunction with holes bound to a delta-layer, 250 A away in the GaAs, of Be acceptors. The low-energy shoulder to the luminescence line, indicating the presence of the electron solid, is seen to disappear at a filling-factor-dependent critical temperature. We observe no shoulder above a filling factor of 0.25, and the critical temperature falls to below 0.4 K at filling factors 1/5 and 1/7

Accelerator Constraints on Neutralino Dark Matter

The constraints on neutralino dark matter \chi obtained from accelerator searches at LEP, the Fermilab Tevatron and elsewhere are reviewed, with particular emphasis on results from LEP 1.5. These imply within the context of the minimal supersymmetric extension of the Standard Model that m_\chi \ge 21.4 GeV if universality is assumed, and yield for large tan\beta a significantly stronger bound than is obtained indirectly from Tevatron limits on the gluino mass. We update this analysis with preliminary results from the first LEP 2W run, and also preview the prospects for future sparticle searches at the LHC.Comment: Presented by J. Ellis at the Workshop on the Identification of Dark Matter, Sheffield, September, 1996. 14 pages; Latex; 12 Fig

Effects of the Running of the QCD Coupling on the Energy Loss in the Quark-Gluon Plasma

Finite temperature modifies the running of the QCD coupling alpha_s(k,T) with resolution k. After calculating the thermal quark and gluon masses selfconsistently, we determine the quark-quark and quark-gluon cross sections in the plasma based on the running coupling. We find that the running coupling enhances these cross sections by factors of two to four depending on the temperature. We also compute the energy loss dE/dx of a high-energy quark in the plasma as a function of temperature. Our study suggests that, beside t-channel processes, inverse Compton scattering is a relevant process for a quantitative understanding of the energy loss of an incident quark in a hot plasma.Comment: 14 pages, 6 figure

Electroweak supersymmetric effects on high energy unpolarized and polarized single top production at LHC

We consider various processes of single top production at LHC in the theoretical framework of the MSSM and examine the role of the supersymmetric electroweak one-loop corrections in a special moderately light SUSY scenario, in an initial parton-pair c.m. high energy range where a logarithmic asymptotic expansion of Sudakov type can be used. We show that the electroweak virtual effects are systematically large, definitely beyond the relative ten percent size, particularly for a final $tH^-$ pair where a special enhancement is present. We show then in a qualitative way the kind of precision tests of the model that would be obtainable from accurate measurements of the energy distributions of the various cross sections and of the top polarization asymmetries.Comment: 30 pages, 9 figure

Colliders and Cosmology

Dark matter in variations of constrained minimal supersymmetric standard models will be discussed. Particular attention will be given to the comparison between accelerator and direct detection constraints.Comment: Submitted for the SUSY07 proceedings, 15 pages, LaTex, 26 eps figure

Irrotational dust with Div H=0

For irrotational dust the shear tensor is consistently diagonalizable with its covariant time derivative: $\sigma_{ab}=0=\dot{\sigma}_{ab},\; a\neq b$, if and only if the divergence of the magnetic part of the Weyl tensor vanishes: $div~H = 0$. We show here that in that case, the consistency of the Ricci constraints requires that the magnetic part of the Weyl tensor itself vanishes: $H_{ab}=0$.Comment: 19 pages. Latex. Also avaliable at http://shiva.mth.uct.ac.za/preprints/text/lesame2.te