Crystal structure of solid Oxygen at high pressure and low temperature

Results of X-ray diffraction experiments on solid oxygen at low temperature and at pressures up to 10 GPa are presented.A careful sample preparation and annealing around 240 K allowed to obtain very good diffraction patterns in the orthorhombic delta-phase. This phase is stable at low temperature, in contrast to some recent data [Y. Akahama et al., Phys. Rev. B64, 054105 (2001)], and transforms with decreasing pressure into a monoclinic phase, which is identified as the low pressure alpha-phase. The discontinuous change of the lattice parameters, and the observed metastability of the alpha-phase increasing pressure suggest that the transition is of the first order.Comment: 4 pages with three figure

The STACEE-32 Ground Based Gamma-ray Detector

We describe the design and performance of the Solar Tower Atmospheric Cherenkov Effect Experiment detector in its initial configuration (STACEE-32). STACEE is a new ground-based gamma ray detector using the atmospheric Cherenkov technique. In STACEE, the heliostats of a solar energy research array are used to collect and focus the Cherenkov photons produced in gamma-ray induced air showers. The large Cherenkov photon collection area of STACEE results in a gamma-ray energy threshold below that of previous detectors.Comment: 45 pages, 25 figures, Accepted for publication in Nuclear Instruments and Methods

Evaluación metodológica de la relación entre presión arterial sanguinea y pliegue cutáneo: un enfoque epidemiológico Evolução metodológica da relação entre pressão arterial sangüínea e prega cutânea: um enfoque epidemiológico Methodological evaluation of the relation between arterial blood pressure and skinfold: an epidemiological approach

Se presentan las conclusiones de la revisión de varios trabajos que estudian la relación entre ciertas características antropométricas (pliegue del tríceps, adiposidad y circunferencia del brazo) y la presión arterial sanguinea. Después de analizar críticamente la calidad de diversos estudios basándonos en el diseño del estudio, la calidad de las mediciones y el tipo de análisis estadísticos, se encontró que en los trabajos elegidos la asociación entre el pliegue cutáneo del tríceps y la presión arterial se relaciona con tres características demográficas. Sin embargo, la pregunta sobre la independencia de esta asociación aún permanece sin respuesta. Se discute el efecto del panículo adiposo del brazo sobre la medición de la presión arterial. Se hacen una serie de recommendaciones para la medición estandarizada de la presión arterial con el fin de uniformizar el procedimiento de medida clínica y de investigación epidemiológica en esta área.<br>Foi elaborada revisão de vários trabalhos que estudam a relação entre certas características antropométricas (prega do tricípite, adiposidade e circunferência do braço) e a pressão arterial sangüínea. Após analisar criticamente a qualidade de diversos estudos, com base no desenho do estudo, na qualidade das medições e no tipo de análises estatísticas, verificou-se que, nos trabalhos selecionados, a associação entre prega cutânea do tricípite e a pressão arterial relaciona-se com três características demográficas. A questão da independência dessa associação ainda permanece sem resposta. Discute-se o efeito da membrana adiposa do braço sobre a medida da pressão arterial. Faz-se série de recomendações para a padronização da medida de pressão arterial com a finalidade de uniformizar o procedimento na clínica e na investigação epidemiológica.<br>The empirical evidence concerning the relationship between blood pressure and anthropometric characteristics (triceps skinfold, adiposity, and arm circumference) was assessed by means of meta-analysis. Different studies were evaluated critically for strength of design, methods and associations. It was found that the association between blood pressure and triceps skinfold holds for three different demographic categories. The question as to the independence of these associations remained unsolved. The effect of arm adiposity on the measurement of blood pressure was also discussed. Recommendations are give in order to standardize blood pressure measurements in clinical and research settings