A note on the consistency of Hybrid Eulerian/Lagrangian approach to multiphase flows

The aim of the present paper is to introduce and to discuss inconsistencies errors that may arise when Eulerian and Lagrangian models are coupled for the simulations of turbulent poly-dispersed two-phase flows. In these hydrid models, two turbulence models are in fact implicitely used at the same time and it is essential to check that they are consistent, in spite of their apparent different formulations. This issue appears in particular in the case of very-small particles, or tracer-limit particles, and it is shown that coupling inconsistent turbulence models (Eulerian and Lagrangian) can result in non-physical results, notably for second-order fluid velocity moments. This problem is illustrated by some computations for fluid particles in a turbulent channel flow using several coupling strategies.Comment: 14 pages, 3 figure

Langevin PDF simulation of particle deposition in a turbulent pipe flow

The paper deals with the description of particle deposition on walls from a turbulent flow over a large range of particle diameter, using a Langevin PDF model. The first aim of the work is to test how the present Langevin model is able to describe this phenomenon and to outline the physical as- pects which play a major role in particle deposition. The general features and characteristics of the present stochastic model are first recalled. Then, results obtained with the standard form of the model are presented along with an analysis which has been carried out to check the sensitivity of the predictions on different mean fluid quantities. These results show that the physical repre- sentation of the near-wall physics has to be improved and that, in particular, one possible route is to introduce specific features related to the near-wall coherent structures. In the following, we propose a simple phenomenological model that introduces some of the effects due to the presence of turbulent coherent structures on particles in a thin layer close to the wall. The results obtained with this phenomenological model are in good agreement with experimental evidence and this suggests to pursue in that direction, towards the development of more general and rigorous stochastic models that provide a link between a geometrical description of turbulent flow and a statistical one.Comment: 40 pages, 8 figure

Ampliação da sobrevida em crianças com AIDS no Brasil: resultados do segundo estudo nacional de 1999 a 2002

The objective of this study is to characterize survival in children with AIDS diagnosed in Brazil between 1999-2002, compared with the first national study (1983-1998). This national retrospective cohort study examined a representative sample of Brazilian children exposed to HIV from mother-to-child transmission and followed through 2007. The survival probability after 60 months was analyzed by sex, year of birth and death, clinical classification, use of antiretroviral therapy (ART) and prophylaxis for opportunistic diseases. 920 children were included. The survival probability increased: comparing cases diagnosed before 1988 with those diagnosed from 2001-2002 it increased by 3.5-fold (from 25% to 86.3%). Use of ART, initial clinical classification, and final classification were significant (p < 0.001) predictors of survival. Issues regarding quality of records and care were identified. The results point to the success of the Brazilian policy of providing ART. The improvement of clinical status contributes to quality of life, while indicating challenges, particularly practices to improve long-term care.Este estudo caracteriza a sobrevida em crianças com AIDS no Brasil entre 1999-2002, contextualizando com o primeiro estudo nacional (1983-1998). Trata-se de coorte histórica, com crianças expostas ao HIV por transmissão vertical e acompanhadas até 2007. A probabilidade de sobrevivência em 60 meses foi analisada segundo sexo, ano de nascimento e de óbito, classificação clínica, uso de terapia antirretroviral (TARV) e de profilaxia para doenças oportunistas. No total, 920 crianças foram incluídas. A probabilidade de sobrevivência foi ampliada 3,5 vezes nos dois períodos avaliados, passando de 25% antes de 1988 para 86,3% no período de 2001-2002. Uso de TARV, classificação clínica inicial e atual/final foram preditores que influíram significativamente (p < 0,001) para a ampliação da sobrevida. Os resultados deste estudo indicam o sucesso da política brasileira para a abordagem das crianças infectadas com HIV. A melhora do estado clínico contribuiu para melhora da qualidade de vida, mas sinaliza-se para a necessidade de incorporação de práticas pautadas na integralidade do cuidado

Potential of a cyclone prototype spacer to improve in vitro dry powder delivery

Copyright The Author(s) 2013. This article is published with open access at Springerlink.com. This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are creditedPurpose: Low inspiratory force in patients with lung disease is associated with poor deagglomeration and high throat deposition when using dry powder inhalers (DPIs). The potential of two reverse flow cyclone prototypes as spacers for commercial carrierbased DPIs was investigated. Methods: Cyclohaler®, Accuhaler® and Easyhaler® were tested with and without the spacers between 30-60 Lmin-1. Deposition of particles in the next generation impactor and within the devices was determined by high performance liquid chromatography. Results: Reduced induction port deposition of the emitted particles from the cyclones was observed due to the high retention of the drug within the spacers (e.g. salbutamol sulphate (SS): 67.89 ± 6.51 % at 30 Lmin-1 in Cheng 1). Fine particle fractions of aerosol as emitted from the cyclones were substantially higher than the DPIs alone. Moreover, the aerodynamic diameters of particles emitted from the cyclones were halved compared to the DPIs alone (e.g. SS from the Cyclohaler® at 4 kPa: 1.08 ± 0.05 μm vs. 3.00 ± 0.12 μm, with and without Cheng 2, respectively) and unaltered with increased flow rates. Conclusion: This work has shown the potential of employing a cyclone spacer for commercial carrier-based DPIs to improve inhaled drug delivery.Peer reviewe

El derecho como punto de partida al concepto filosófico de "presunción": la contribución de Ullmann-Margalit

Resumen: El presente paper analiza la contribución de Edna Ullmann-Margalit al desarrollo del concepto filosófico de presunción (asumir desde la ocurrencia de un hecho conocido la ocurrencia de un hecho no conocido a modo de actuar sobre él). Ullman-Margalit toma el contexto jurídico como punto de partida de su teoría porque, según ella, el lenguaje técnico del derecho dispone de más precisión que el lenguaje ordinario en lo que respeta a la “presunción” y sus parientes terminológicos. Dado que su paper de 1983 se haya convertido en una referencia a todos los que se dedican a qué significa “presumir”, aquí se ofrecerán dos objeciones a la contribución de Ullmann-Margalit. Abstract: The present paper analyzes Edna Ullman-Margalit's contribution for the development of a philosophical concept of presumption (assume from the occurrence of a known fact the occurrence of an unknown fact in order to act on its basis). Ullman-Margalit takes the legal context as a departure point for her theory because she believes that technical legal language is more precise than ordinary language in relation to the concept of "presumption" and its terminological cousins. Given that her 1983 paper has been a reference to those who attempt to understand what it means to "presume", this paper will offer two objections to Ullman-Margalit's contribution

Evaluation and comparison of trace metals accumulation in different tissues of potential bioindicator organisms: Macrobenthic filter feeders Styela plicata, sabella spallanzanii and Mytilus galloprovincialis

Trace metal concentrations were measured in different tissues of Sabella spallanzanii, Styela plicata and Mytilus galloprovincialis collected in Termini Imerese harbor, located in Sicily (Italy), in order to evaluate the potential use of these species as bioindicators. The higher bioaccumulation factors (BAFs) were calculated in tube of Sabella spallanzanii, except for As which shows the higher BAF in branchial crown of the same specie. Regarding the other species analyzed, higher BAFs were found in the digestive gland of Mytilus galloprovincialis. An exception is represented by Pb that is significantly more concentrated in branchial basket and tunic of Styela plicata. The BAFs here calculated, show that all the species analyzed are able to accumulate a certain amount of metals as a consequence of filter feeding mechanisms, and thus assess the suitability of the species Styela plicata, Sabella spallanzanii and Mytilus galloprovincialis as indicators of water quality. Particularly, the tube of Sabella spallanzanii is an important compartment in metal retention and the more suitable for the evaluation of the contamination caused by trace elements. This article is protected by copyright. All rights reserved

Short CommunicationMating system parameters in Stylosanthes guianensis (Aubl.) Sw. based on RAPD markers

This study investigated the mating systems in Stylosanthes guianensis, an important tropical forage legume. Twelve progenies were analyzed with 21 polymorphic random amplified polymorphic DNA (RAPD) loci. The mating parameters estimated using the mixed mating model showed that this population practices a mixture of selfing (61.4%) and out-crossing (38.6%) for reproduction. The results also indicated that the fraction of multilocus out-crossing of about 8.2% occurred among related individuals. Low values were obtained for correlation of paternity (0.212 ± 0.046) and correlation of selfing among families (0.102 ± 0.001). These results have important implications to establish strategies of maintenance of germplasm and genetic breeding.Keywords: Mixed mating model, out-crossing rate, tropical forage legumeAfrican Journal of Biotechnology Vol. 9(36), pp. 5820-5822, 6 September, 201