Self-Duality in D <= 8-dimensional Euclidean Gravity

In the context of D-dimensional Euclidean gravity, we define the natural generalisation to D-dimensions of the self-dual Yang-Mills equations, as duality conditions on the curvature 2-form of a Riemannian manifold. Solutions to these self-duality equations are provided by manifolds of SU(2), SU(3), G_2 and Spin(7) holonomy. The equations in eight dimensions are a master set for those in lower dimensions. By considering gauge fields propagating on these self-dual manifolds and embedding the spin connection in the gauge connection, solutions to the D-dimensional equations for self-dual Yang-Mills fields are found. We show that the Yang-Mills action on such manifolds is topologically bounded from below, with the bound saturated precisely when the Yang-Mills field is self-dual. These results have a natural interpretation in supersymmetric string theory.Comment: 9 pages, Latex, factors in eqn. (6) corrected, acknowledgement and reference added, typos fixe

Revue systématique d’essais comparatifs randomisés d’interventions d’abandon du tabac chez les jeunes

Contexte : Bien que l’usage de la cigarette demeure courant parmi les jeunes, on en sait encore bien peu sur la façon de les aider à cesser de fumer. Seulement quelques revues systématiques d’essais comparatifs randomisés (ECR) ont évalué l’efficacité des interventions d’abandon du tabac chez les jeunes.Objectif : Résumer les connaissances sur l’efficacité des interventions visant à aider les jeunes à cesser de fumer en se basant sur des données probantes provenant d’ECR.Sélection des études et extraction des données : Nous avons retenu tous les ECR publiés qui évaluaient les interventions d’abandon du tabac ciblant les jeunes âgés de 20 ans et moins et qui rapportaient l’abstinence au tabac selon une analyse en intention de traiter. Nous avons relevé les études pertinentes provenant de huit revues de synthèse décrivant des études portant sur des interventions d’abandon du tabac publiées entre 2002 et 2006, ainsi qu’une recherche menée dans les bases de données PubMed et PsycINFO entre 2001 et novembre  2006. Nous rapportons l’abstinence au tabagisme au moment du suivi le plus prolongé. Les auteurs ont sélectionné d’un commun accord les données retenues pour cette revue.Résultats : Nous avons identifié 16 ECR auxquels ont participé 6 623 jeunes ; 11 études évaluant des interventions comportementales qui comprenaient 5 764 participants; quatre examinant des interventions pharmacologiques qui comptaient 529 participants ; et une se penchant sur l’acupuncture au laser qui comportait 330 participants. Trois interventions comportementales menées en milieu scolaire sur quatre et une intervention réalisée en milieu de soins de santé sur quatre ont fait augmenter de façon significative l’abstinence au tabac, quatre semaines à 24 mois suivant les interventions. Parmi les quatre ERC qui évaluaient les interventions pharmacologiques réalisées à l’aide soit de bupropion, de timbres ou de gommes à la nicotine, une étude, où le timbre à la nicotine a été utilisé en combinaison avec un counseling cognitivo-comportemental, a montré une hausse marquée, quoique non significative, de l’abstinence six mois après la date d’abandon.Conclusion : Il existe encore peu de preuves démontrant l’efficacité des interventions d’abandon du tabac chez les jeunes. Quatre programmes en milieu scolaire et une intervention dans un établissement de santé ont mis en évidence une certaine efficacité, tandis que pour la thérapie pharmacologique, les résultats ne sont pas encore concluants.Background: Cigarette use remains common among young people but little is known about how to help adolescent smokers quit. There are few systematic reviews of randomized controlled trials (RCTs) that evaluate the effectiveness of cessation interventions for youth.Objective: To synthesize knowledge on the effectiveness of cessation interventions targeted to youth based on evidence from RCTs.Selection of studies and data extraction: We retained all published RCTs with intention to treat analyses that evaluated cessation interventions targeted to youth aged ≤ 20 years. Relevant studies were identified from eight review articles of smoking cessation intervention studies published between 2002 and 2006, and from a search conducted in PubMed and PsycINFO databases from 2001 to November 2006. The outcome of primary interest was abstinence at the longest reported follow-up. Extraction of data was by consensus of the authors. Results: We identified 16 RCTs with a total of 6623 participants; 11 studies that included 5764 participants evaluated behavioural interventions, four with 529 participants evaluated pharmacological interventions, and one with 330 participants evaluated a laser acupuncture intervention. Three of four behavioural interventions conducted in school settings, and one of four conducted in a health care setting significantly increased abstinence four weeks to 24 months after the interventions. Of four RCTs that evaluated pharmacological interventions using either bupropion or nicotine patch or gum, one study using the nicotine patch coupled with cognitive-behavioural counselling showed a marked albeit non-significant increase in abstinence six months after quit date.Conclusion: There is still limited evidence demonstrating the efficacy of smoking cessation interventions in youth. Four school-based programs and one intervention in a health care setting have shown efficacy, while results for pharmacological therapy are inconsistent across studies.Contexto: si bien el tabaco sigue siendo de uso corriente entre los jóvenes, todavía no se sabe mucho sobre cómo ayudarlos a dejar de fumar. Solamente algunas revisiones sistemáticas de ensayos comparativos aleatorizados han evaluado la eficacia de las intervenciones dirigidas a lograr el abandono del tabaco entre los jóvenes.Objetivo: resumir los conocimientos sobre la eficacia de las intervenciones destinadas a ayudar a jóvenes a dejar de fumar sobre la base de los datos probados de los ensayos comparativos aleatorizados.Selección de estudios y extracción de datos: hemos retenido todos los ensayos comparativos aleatorizados publicados, que evalúan las intervenciones de abandono del tabaco en los jóvenes de 20 años y menos, y que informan sobre la abstinencia de tabaco, según un análisis que tiene la intención de tratar. Hemos seleccionado los trabajos pertinentes provenientes de ocho revistas de síntesis, que describen estudios referidos a intervenciones de abandono del tabaco publicados entre 2002 y 2006, así como una investigación llevada a cabo en las bases de datos PubMed et PsycINFO, realizada entre 2001 y noviembre de 2006. Informamos sobre la abstinencia del tabaquismo en el momento de seguimiento más prolongado. Los autores han seleccionado de común acuerdo los datos retenidos por esta revista.Resultados: hemos identificado dieciséis estudios comparativos aleatorizados en los que participaron 6.623 jóvenes; once estudios que evalúan las intervenciones comportamentales, con 5.764 participantes; cuatro que examinan las intervenciones farmacológicas en las que intervienen 529 participantes y uno que se centra en la acupuntura al láser, con 330 participantes. Tres intervenciones comportamentales realizadas en medio escolar de cada cuatro y una intervención realizada en el medio de la atención sanitaria de cada cuatro, aumentaron de manera significativa la abstinencia al tabaco, cuatro semanas a 24 meses después de las intervenciones. Entre los cuatro estudios comparativos aleatorizados que evaluaban las intervenciones farmacológicas, realizadas ya sea con ayuda de bupropion, de parches o de gomas de mascar a la nicotina, uno de ellos, en el que se utilizó un parche de nicotina en combinación con orientación psicológica cognitivo-comportamental, indicó un aumento marcado, aunque no significativo, de la abstinencia, seis meses después de la fecha de abandono.Conclusión: existen todavía pocas pruebas que demuestren la eficacia de las intervenciones de abandono del tabaco entre los jóvenes. Cuatro programas en medio escolar y una intervención en un establecimiento de salud evidenciaron una cierta eficacia, mientras que los resultados no son todavía concluyentes en lo que se refiere a la terapia farmacológica

Characterising pressure and bruising in apple fruit

A large percentage of apples are wasted each year due to damage such as bruising. The apple journey from orchard to supermarket is very complex and apples are subjected to a variety of static and dynamic loads that could result in this damage occurring. The aim of this work was to use a novel ultrasonic technique to study apple contact areas and stresses under static loading that may occur, for example, in bulk storage bins used during harvesting. These results were used to identify load thresholds above which unacceptable damage occurs. They were also used to validate output from a finite element model, which will ultimately be developed into a packaging design tool to help reduce the likelihood of apple damage occurring

Prospective surveillance of invasive group a streptococcal disease, Fiji, 2005-2007.

We undertook a prospective active surveillance study of invasive group A streptococcal (GAS) disease in Fiji over a 23-month period, 2005-2007. We identified 64 cases of invasive GAS disease, which represents an average annualized all-ages incidence of 9.9 cases/100,000 population per year (95% confidence interval [CI] 7.6-12.6). Rates were highest in those >65 years of age and in those <5 years, particularly in infants, for whom the incidence was 44.9/100,000 (95% CI 18.1-92.5). The case-fatality rate was 32% and was associated with increasing age and underlying coexisting disease, including diabetes and renal disease. Fifty-five of the GAS isolates underwent emm sequence typing; the types were highly diverse, with 38 different emm subtypes and no particular dominant type. Our data support the view that invasive GAS disease is common in developing countries and deserves increased public health attention

Nonsingular Black Hole Evaporation and ``Stable'' Remnants

We examine the evaporation of two--dimensional black holes, the classical space--times of which are extended geometries, like for example the two--dimensional section of the extremal Reissner--Nordstrom black hole. We find that the evaporation in two particular models proceeds to a stable end--point. This should represent the generic behavior of a certain class of two--dimensional dilaton--gravity models. There are two distinct regimes depending on whether the back--reaction is weak or strong in a certain sense. When the back--reaction is weak, evaporation proceeds via an adiabatic evolution, whereas for strong back--reaction, the decay proceeds in a somewhat surprising manner. Although information loss is inevitable in these models at the semi--classical level, it is rather benign, in that the information is stored in another asymptotic region.Comment: 23 pages, 6 figures, harvmac and epsf, RU-93-12, PUPT-1399, NSF-ITP-93-5

Stable U(IV) Complexes Form at High-Affinity Mineral Surface Sites

Uranium (U) poses a significant contamination hazard to soils, sediments, and groundwater due to its extensive use for energy production. Despite advances in modeling the risks of this toxic and radioactive element, lack of information about the mechanisms controlling U transport hinders further improvements, particularly in reducing environments where UIV predominates. Here we establish that mineral surfaces can stabilize the majority of U as adsorbed UIV species following reduction of UVI. Using X-ray absorption spectroscopy and electron imaging analysis, we find that at low surface loading, UIV forms inner-sphere complexes with two metal oxides, TiO2 (rutile) and Fe3O4 (magnetite) (at <1.3 U nm–2 and <0.037 U nm–2, respectively). The uraninite (UO2) form of UIV predominates only at higher surface loading. UIV–TiO2 complexes remain stable for at least 12 months, and UIV–Fe3O4 complexes remain stable for at least 4 months, under anoxic conditions. Adsorbed UIV results from UVI reduction by FeII or by the reduced electron shuttle AH2QDS, suggesting that both abiotic and biotic reduction pathways can produce stable UIV–mineral complexes in the subsurface. The observed control of high-affinity mineral surface sites on UIV speciation helps explain the presence of nonuraninite UIV in sediments and has important implications for U transport modeling

Mortality after admission for acute myocardial infarction in Aboriginal and non-Aboriginal people in New South Wales, Australia: a multilevel data linkage study

Background - Heart disease is a leading cause of the gap in burden of disease between Aboriginal and non-Aboriginal Australians. Our study investigated short- and long-term mortality after admission for Aboriginal and non-Aboriginal people admitted with acute myocardial infarction (AMI) to public hospitals in New South Wales, Australia, and examined the impact of the hospital of admission on outcomes. Methods - Admission records were linked to mortality records for 60047 patients aged 25–84 years admitted with a diagnosis of AMI between July 2001 and December 2008. Multilevel logistic regression was used to estimate adjusted odds ratios (AOR) for 30- and 365-day all-cause mortality. Results - Aboriginal patients admitted with an AMI were younger than non-Aboriginal patients, and more likely to be admitted to lower volume, remote hospitals without on-site angiography. Adjusting for age, sex, year and hospital, Aboriginal patients had a similar 30-day mortality risk to non-Aboriginal patients (AOR: 1.07; 95% CI 0.83-1.37) but a higher risk of dying within 365 days (AOR: 1.34; 95% CI 1.10-1.63). The latter difference did not persist after adjustment for comorbid conditions (AOR: 1.12; 95% CI 0.91-1.38). Patients admitted to more remote hospitals, those with lower patient volume and those without on-site angiography had increased risk of short and long-term mortality regardless of Aboriginal status. Conclusions - Improving access to larger hospitals and those with specialist cardiac facilities could improve outcomes following AMI for all patients. However, major efforts to boost primary and secondary prevention of AMI are required to reduce the mortality gap between Aboriginal and non-Aboriginal people

Impact of Indian Total Sanitation Campaign on latrine coverage and use: a cross-sectional study in Orissa three years following programme implementation.

BACKGROUND: Faced with a massive shortfall in meeting sanitation targets, some governments have implemented campaigns that use subsidies focused on latrine construction to overcome income constraints and rapidly expand coverage. In settings like rural India where open defecation is common, this may result in sub-optimal compliance (use), thereby continuing to leave the population exposed to human excreta. METHODS: We conducted a cross-sectional study to investigate latrine coverage and use among 20 villages (447 households, 1933 individuals) in Orissa, India where the Government of India's Total Sanitation Campaign had been implemented at least three years previously. We defined coverage as the proportion of households that had a latrine; for use we identified the proportion of households with at least one reported user and among those, the extent of reported use by each member of the household. RESULTS: Mean latrine coverage among the villages was 72% (compared to <10% in comparable villages in the same district where the Total Sanitation Campaign had not yet been implemented), though three of the villages had less than 50% coverage. Among these households with latrines, more than a third (39%) were not being used by any member of the household. Well over a third (37%) of the members of households with latrines reported never defecating in their latrines. Less than half (47%) of the members of such households reported using their latrines at all times for defecation. Combined with the 28% of households that did not have latrines, it appears that most defecation events in these communities are still practiced in the open. CONCLUSION: A large-scale campaign to implement sanitation has achieved substantial gains in latrine coverage in this population. Nevertheless, gaps in coverage and widespread continuation of open defecation will result in continued exposure to human excreta, reducing the potential for health gains

Aspects of Plane Wave (Matrix) String Dynamics

We analyse two issues that arise in the context of (matrix) string theories in plane wave backgrounds, namely (1) the use of Brinkmann- versus Rosen-variables in the quantum theory for general plane waves (which we settle conclusively in favour of Brinkmann variables), and (2) the regularisation of the quantum dynamics for a certain class of singular plane waves (discussing the benefits and limitations of regularisations of the plane-wave metric itself).Comment: 29 page

Number of years of participation in some, but not all, types of physical activity during adolescence predicts level of physical activity in adulthood: Results from a 13-year study

Abstract: Background: Adolescent physical activity (PA) levels track into adulthood. However it is not known if type of PA participated in during adolescence is associated with PA levels later in life. We aimed to identify natural groupings of types of PA and to assess whether number of years participating in these different groupings during adolescence is related to PA level in early adulthood. Methods: 673 adolescents in Montreal, Canada, age 12–13 years at baseline (54 % female), reported participation in 29 physical activities every 3 months over 5 years (1999–2005). They also reported their PA level at age 24 years (2011–12). PA groupings among the 29 physical activities were identified using factor analysis. The association between number of years participating in each grouping during adolescence and PA level at age 24 was estimated using linear regression within a general estimating equation framework. Results: Three PA groupings were identified: “sports”, “fitness and dance”, and “running”. There was a positive linear relationship between number of years participating in sports and running in adolescence and PA level at age 24 years (β (95 % confidence interval) = 0.09 (0.04-0.15); 0.08 (0.01-0.15), respectively). There was no relationship between fitness and dance in adolescence and PA level at age 24. Conclusions: The association between PA participation in adolescence and PA levels in young adulthood may be specific to certain PA types and to consistency of participation during adolescence. Results suggest that efforts to establish the habit of participation in sports and running in adolescence may promote higher PA levels in adulthood