Lepton Polarization in Neutrino-Nucleon Interactions

We derive generic formulas for the polarization density matrix of leptons produced in neutrino and antineutrino collisions and briefly consider some important particular cases. Next we employ the general formalism in order to include the final lepton mass and spin into the popular model by Rein and Sehgal for single pion neutrinoproduction.Comment: Talk given at 10th International Workshop on High-Energy Spin Physics (SPIN 03), Dubna, Russia, 16-20 Sep 2003. 12 pages; extended version, typos remove

Drug administration errors by South African anaesthetists - a survey

Objectives. To investigate the incidence, nature of and factors contributing towards wrong drug administrations by South African anaesthetists. Design. A confidential, self-reporting survey was sent out to the 720 anaesthetists on the database of the South African Society of Anaesthesiologists. Results. A total of 133 questionnaires were returned for analysis (18.5% response rate). Of the respondents, 125 (94%) admitted to having inadvertently administered a wrong drug. Thirty respondents (22.6%) said they had made errors on at least four occasions. A total of 303 specific wrong drug administrations were described. Nearly 50% involved muscle relaxants. A further 43 incidents (14%) involved the erroneous administration of vasoactive drugs. Five deaths and 3 nonfatal cardiac arrests were reported. In 9.9% of incidents the anaesthetic time was prolonged by more than 30 minutes. Contributory causes identified included syringe swaps (40%), misidentification of drugs (27.1%), fatigue (14.1%), distractions (4.7%), and mislabelling of syringes (4.7%). Only 19% of respondents regularly use colour-coded syringe labels complying with the national standard. Conclusions. Most anaesthetists experienced at least one drug error. The incidence of wrong drug administrations by South African anaesthetists appears to be similar to that in Australasia and Canada. The commonest error was a ‘syringe swap’ involving muscle relaxants. Most drug errors are inconsequential. An important minority of incidents result in severe morbidity or death. The study supports efforts to improve ampoule labelling, to encourage the use of syringe labels based on the international colour code and to develop a national reporting system for such incidents

Pt nanocrystals formed by ion implantation: a defect-mediated nucleation process

The influence of ion irradiation of SiO₂ on the size of metalnanocrystals (NCs) formed by ion implantation has been investigated. Thin SiO₂ films were irradiated with high-energy Ge ions then implanted with Pt ions. Without Geirradiation, the largest Pt NCs were observed beyond the Pt projected range. With irradiation, Ge-induced structural modification of the SiO₂ layer yielded a decrease in Pt NC size with increasing Ge fluence at such depths. A defect-mediated NC nucleation mechanism is proposed and a simple yet effective means of modifying and controlling the Pt NC size is demonstrated.The authors thank the Australian Research Council for financial support

Mesons in a Poincare Covariant Bethe-Salpeter Approach

We develop a covariant approach to describe the low-lying scalar, pseudoscalar, vector and axialvector mesons as quark-antiquark bound states. This approach is based on an effective interaction modeling of the non--perturbative structure of the gluon propagator that enters the quark Schwinger-Dyson and meson Bethe-Salpeter equations. We consistently treat these integral equations by precisely implementing the quark propagator functions that solve the Schwinger-Dyson equations into the Bethe-Salpeter equations in the relevant kinematical region. We extract the meson masses and compute the pion and kaon decay constants. We obtain a quantitatively correct description for pions, kaons and vector mesons while the calculated spectra of scalar and axialvector mesons suggest that their structure is more complex than being quark-antiquark bound states.Comment: 18 pages LaTeX, 5 figures; some changes in the presentation, new results on axial vector mesons in enlarged mixing scheme; version to be published in Physical Review

Ground-state Spectrum of Light-quark Mesons

A confining, Goldstone theorem preserving, separable Ansatz for the ladder kernel of the two-body Bethe-Salpeter equation is constructed from phenomenologically efficacious $u$, $d$ and $s$ dressed-quark propagators. The simplicity of the approach is its merit. It provides a good description of the ground-state isovector-pseudoscalar, vector and axial-vector meson spectrum; facilitates an exploration of the relative importance of various components of the two-body Bethe-Salpeter amplitudes, showing that sub-leading Dirac components are quantitatively important in the isovector-pseudoscalar meson channels; and allows a scrutiny of the domain of applicability of ladder truncation studies. A colour-antitriplet diquark spectrum is obtained. Shortcomings of separable Ans\"atze and the ladder kernel are highlighted.Comment: 30 pages, LaTeX/REVTEX 3.0, no figure

Pions in the nuclear medium and Drell-Yan scattering

We investigate the modification of the pion-cloud in the nuclear medium and its effect on the nuclear Drell-Yan process. The pion's in-medium self-energy is calculated in a self-consistent delta-hole model, with particle-hole contribution also included. Both the imaginary and real part of the pion's and delta's self-energy are taken into account and related through a dispersion relation assuring causality. The resulting in-medium pion light-cone momentum distribution shows only a slight enhancement compared to the one of the free nucleon. As a consequence the ratio of the cross-section for Drell-Yan scattering on nuclear matter and nucleonic target is close to unity in agreement with experiment.Comment: 33 pages, Latex with epsf, figures included, to appear in Phys. Rev.

Psychological perspectives on obesity: Addressing policy, practice and research priorities

Obesity has received much attention from politicians, policymakers, healthcare professionals, the media and the public over the past few decades. Since the formal recognition from the UK government in 1991 that obesity was a sufficient threat to the health of the nation, a targeted response to address the issue has been a policy priority for almost 30 years. A wide range of policies are now in place, including the establishment of nutritional standards in schools, programmes aimed to boost physical activity, and weight management services. However, while some interventions and services have been successful at the individual and community level, there has been little impact at population level. This report looks at what psychological evidence and perspectives can add to help improve our combined response to obesity. It seeks to guide professionals and policy-makers who are working with individuals, groups and populations that are impacted by obesity to take an approach that is guided by psychology. We have sought to produce guidance that recognises and builds on existing services, while identifying areas where further resources, standards, training and staff are required