Effective Rheology of Bubbles Moving in a Capillary Tube

We calculate the average volumetric flux versus pressure drop of bubbles moving in a single capillary tube with varying diameter, finding a square-root relation from mapping the flow equations onto that of a driven overdamped pendulum. The calculation is based on a derivation of the equation of motion of a bubble train from considering the capillary forces and the entropy production associated with the viscous flow. We also calculate the configurational probability of the positions of the bubbles.Comment: 4 pages, 1 figur

Prevalência de acidentes de trânsito auto-referidos em Rio Branco, Acre

OBJETIVO: Estimar a prevalência de acidentes de trânsito auto-referidos e identificar fatores associados. MÉTODOS: Estudo transversal de base populacional realizado de setembro de 2007 a agosto de 2008, nas zonas urbana e rural de Rio Branco, AC. Foram analisados dados referentes aos adultos (18 a 96 anos, n = 1.516) do inquérito Saúde e Nutrição de Adultos e Crianças de Rio Branco, obtidos em entrevistas domiciliares. As relações entre acidente de trânsito auto-referido e variáveis socioeconômicas e comportamentais foram analisadas por meio de razões de prevalência e intervalos de 95% de confiança; foi efetuada análise de regressão múltipla de Poisson. RESULTADOS: A prevalência de acidente de trânsito auto-referido foi de 36%. Na análise de Poisson, os indivíduos do sexo masculino (RP=1,45 e IC95%: 1,12;1,87), que relatavam consumo de bebida alcoólica (RP=1,25 e IC95%: 0,97;1,62), com renda acima de cinco salários mínimos (RP=1,88 e IC95%: 1,25;2,83), idade entre 18 e 25 anos (RP=1,45 e IC95%: 1,02;2,05) apresentaram maior probabilidade de referir envolvimento em acidente de trânsito. As variáveis idade e escolaridade mostraram associação inversa com o desfecho, enquanto renda apresentou associação positiva, todas elas com tendência significativa. CONCLUSÕES: A prevalência dos acidentes de trânsito auto-referidos aponta risco mais elevado para homens, com renda mais elevada, menor escolaridade e que ingerem bebida alcoólica, os quais devem ser alvo das campanhas preventivas.OBJETIVO: Estimar la prevalencia de accidentes de tránsito auto-referidos e identificar factores asociados. MÉTODOS: Estudio transversal de base poblacional realizado de septiembre de 2007 a agosto de 2008, en las zonas urbana y rural de Rio Branco, Norte de Brasil. Se analizaron datos referentes a los adultos (18 a 96 años, n=1.516) de la Pesquisa Salud y Nutrición de Adultos y Niños de Rio Branco, obtenidos en entrevistas domiciliares. Las relaciones entre accidente de tránsito auto-referido y variables socioeconómicas y conductuales fueron analizadas por medio de tasas de prevalencia e intervalos de 95% de confianza. El análisis multivariado fue efectuado por medio de la regresión de Poisson. RESULTADOS: La prevalencia de accidente de tránsito auto-referido fue de 36%. En el análisis multivariado, los individuos del sexo masculino (RP 1,45 e IC95%: 1,12;1,87), que relataban consumo de bebida alcohólica (RP 1,25 e IC95%: 0,97;1,62), con renta superior a cinco salarios mínimos (RP 1,88 e IC95%: 1,25;2,83), edad entre 18 y 25 años (RP 1,45 e IC95%: 1,02;2,05) presentaron mayor probabilidad de referir envolvimiento en accidente de tránsito. Las variables edad y escolaridad mostraron asociación inversa con el resultado, mientras que renta presentó asociación positiva, todas ellas con tendencia significativa. CONCLUSIONES: La prevalencia de los accidentes de tránsito auto-referidos, señalan riesgo más elevado para hombres, con renta más elevada, menor escolaridad y que ingieren bebida alcohólica, siendo ellos el blanco de las campañas preventivas.OBJECTIVE: To estimate the prevalence of self-reported traffic accidents and identify associated factors. METHODS: Cross-sectional, population-based study carried out from September 2007 to August 2008, in the urban and rural zones of Rio Branco (Northern Brazil). Data referring to adults (aged 18 to 96 years, n = 1,516) of the inquiry Health and Nutrition of Adults and Children of Rio Branco, obtained in home interviews, were analyzed. The relations between self-reported traffic accident and socioeconomic and behavior variables were analyzed by means of prevalence ratios and 95% confidence intervals; Poisson regression analysis was performed. RESULTS: The prevalence of self-reported traffic accident was 36%. In the Poisson analysis, male individuals (PR= 1.45 and 95% CI: 1.12;1.87) who reported alcohol consumption (PR= 1.25 and 95%CI: 0.97;1.62), with income above five minimum wages (PR= 1.88 and 95%CI: 1.25;2.83), aged between 18 and 25 years (PR= 1.45 and 95%CI: 1.02;2.05), presented higher probability of reporting involvement in traffic accidents. The variables age and level of schooling had inverse association with the outcome, while income had a positive association, all of them with significant tendency. CONCLUSIONS: The prevalence of self-reported traffic accidents shows higher risk for men with higher income, lower level of schooling and who ingest alcoholic beverages. They should be the target of prevention campaigns

Growth and Demography of the Solitary Scleractinian Coral Leptopsammia pruvoti along a Sea Surface Temperature Gradient in the Mediterranean Sea

The demographic traits of the solitary azooxanthellate scleractinian Leptopsammia pruvoti were determined in six populations on a sea surface temperature (SST) gradient along the western Italian coasts. This is the first investigation of the growth and demography characteristics of an azooxanthellate scleractinian along a natural SST gradient. Growth rate was homogeneous across all populations, which spanned 7 degrees of latitude. Population age structures differed between populations, but none of the considered demographic parameters correlated with SST, indicating possible effects of local environmental conditions. Compared to another Mediterranean solitary scleractinian, Balanophyllia europaea, zooxanthellate and whose growth, demography and calcification have been studied in the same sites, L. pruvoti seems more tolerant to temperature increase. The higher tolerance of L. pruvoti, relative to B. europaea, may rely on the absence of symbionts, and thus the lack of an inhibition of host physiological processes by the heat-stressed zooxanthellae. However, the comparison between the two species must be taken cautiously, due to the likely temperature differences between the two sampling depths. Increasing research effort on determining the effects of temperature on the poorly studied azooxanthellate scleractinians may shed light on the possible species assemblage shifts that are likely to occur during the current century as a consequence of global climatic change