Modelo numerico eficiente para flujo electrocinetico en sistemas microfluidicos con geometrias complejas

Microfluidic devices like those used in chemical and biomedical applications basically consist of different networks of microchannels that interconnect chambers and reservoirs. The transport of fluids throughout the network is driven by pressure gradients, electric fields, or a combination of the two, which yields to the so-called electrokinetic flow. Analytical and numerical models have been used to aid in the design and simulation before fabrication with MEMS technology. Efficient numerical models are required since typical microchannel dimensions are in the range of several micrometers in width and depth and some centimeters in length. The numerical solution is carried out by using PETSC-FEM, for which we have developed a python interface for pre- and postprocessing using third-parties programs (Tetgen, Mayavi). A parallelizable preconditioner for Domain Decomposition Methods (DDM) by means of Finite Element discretization of Navier-Stokes equations is used to improve the convergence of problems with different scales like in microfluidic problems.Fil: Kler, Pablo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Guarnieri, Fabio Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina. Universidad Nacional de Entre Ríos; ArgentinaFil: Dalcin, Lisandro Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Modelo numérico eficiente para flujo electrocinético en sistemas microfluídicos con geometrias complejas

Microfluidic devices like those used in chemical and biomedical applications basically consist of different networks of microchannels that interconnect chambers and reservoirs. The transport of fluids throughout the network is driven by pressure gradients, electric fields, or a combination of the two, which yields to the so-called electrokinetic flow. Analytical and numerical models have been used to aid in the design and simulation before fabrication with MEMS technology. Efficient numerical models are required since typical microchannel dimensions are in the range of several micrometers in width and depth and some centimeters in length. The numerical solution is carried out by using PETSC-FEM, for which we have developed a python interface for pre- and postprocessing using third-parties programs (Tetgen, Mayavi). A parallelizable preconditioner for Domain Decomposition Methods (DDM) by means of Finite Element discretization of Navier-Stokes equations is used to improve the convergence of problems with different scales like in microfluidic problems.Fil: Kler, Pablo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Guarnieri, Fabio Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Dalcin, Lisandro Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

A preconditioner for the Schur complement matrix

A preconditioner for iterative solution of the interface problem in Schur Complement Domain Decomposition Methods is presented. This preconditioner is based on solving a global problem in a narrow strip around the interface. It requires much less memory and computing time than classical Neumann–Neumann preconditioner and its variants, and handles correctly the flux splitting among subdomains that share the interface. The aim of this work is to present a theoretical basis (regarding the behavior of Schur complement matrix spectra) and some simple numerical experiments conducted in a sequential environment as a motivation for adopting the proposed preconditioner. Efficiency, scalability, and implementation details on a production parallel finite element code [Sonzogni V, Yommi A, Nigro N, Storti M. A parallel finite element program on a Beowulf cluster. Adv Eng Software 2002;33(7–10):427–43; Storti M, Nigro N, Paz R, Dalcín L. PETSc-FEM: a general purpose, parallel, multi-physics FEM program, 1999–2006] can be found in works [Paz R, Storti M. An interface strip preconditioner for domain decomposition methods: application to hydrology. Int J Numer Methods Eng 2005;62(13):1873–94; Paz R, Nigro N, Storti M. On the efficiency and quality of numerical solutions in cfd problems using the interface strip preconditioner for domain decomposition methods. Int J Numer Methods Fluids, in press].Fil: Storti, Mario Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Dalcin, Lisandro Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Paz, Rodrigo Rafael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Yommi, Alejandra Karina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Sonzogni, Victorio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Nigro, Norberto Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

INVESTIGATION OF BIOFILM FORMATION IN COAGULASE-NEGATIVE STAPHYLOCOCCI ISOLATED FROM PLATELET CONCENTRATE BAGS

Platelet Concentrates (PCs) are the blood components with the highest rate of bacterial contamination, and coagulase-negative staphylococci (CoNS) are the most frequently isolated contaminants. This study investigated the biofilm formation of 16 contaminated units out of 691 PCs tested by phenotypic and genotypic methods. Adhesion in Borosilicate Tube (ABT) and Congo Red Agar (CRA) tests were used to assess the presence of biofilm. The presence of icaADC genes was assessed by means of the Polymerase Chain Reaction (PCR) technique. With Vitek(r)2, Staphylococcus haemolyticus was considered the most prevalent CoNS (31.25%). The CRA characterized 43.8% as probable biofilm producers, and for the ABT test, 37.5%. The icaADC genes were identified in seven samples by the PCR. The ABT technique showed 85.7% sensitivity and 100% specificity when compared to the reference method (PCR), and presented strong agreement (k = 0.8). This study shows that species identified as PCs contaminants are considered inhabitants of the normal skin flora and they might become important pathogens. The results also lead to the recommendation of ABT use in laboratory routine for detecting biofilm in CoNS contaminants of PCs

ANÁLISE DA COMPETITIVIDADE DO MERCADO EXPORTADOR BRASILEIRO DE CACAU PARA ARGENTINA E ESTADOS UNIDOS

Este trabalho buscou analisar a competitividade das exportações brasileiras de cacau para Argentina e Estados Unidos, no período entre 1999 e 2015. Para isso, calcularam-se os indicadores de Índice de Orientação Regional (IOR) e o Índice de Vantagens Comparativas Reveladas (IVCR). Os dados foram coletados junto às bases de dados do Sistema de Análise das Informações de Comércio Exterior (ALICE WEB) e da United Nations Commodity Trade Statistics Database (UNCOMTRADE). Os resultados indicaram que a Argentina é um importante mercado consumidor do cacau brasileiro, pois essas exportações estão orientadas ao longo do período em questão, além de representarem uma oportunidade de crescimento das relações entre ambos os países. Contudo, para o mercado norte-americano, as exportações brasileiras de cacau foram pouco orientadas

PADRÃO DE ESPECIALIZAÇÃO DAS EXPORTAÇÕES DA BAHIA (1999-2014)

This study aimed to analyze the specialization pattern of exports from the state of Bahia, identifying the most dynamic productive sectors in the period between 1999 and 2014. In this sense, the Revealed Symmetric Comparative Advantage Index (RSCA) was calculated, as well as the Intra-Industry Trade rate (IIT), the Sector Concentration of Exports (ICS) and the Imports Coverage ratio. The results indicated that the state presented a poorly diversified export basket. Thus, it is clear that the pattern of exports consists mainly on products based on natural resources and those from the traditional manufacturing industry, which are barely able to generate dynamic comparative advantages, that is, technological innovation.Este trabalho buscou analisar o padrão de especialização das exportações do Estado da Bahia, identificando os setores produtivos mais dinâmicos, no período entre 1999 e 2014. Neste sentido, calcularam-se os indicadores de Vantagem Comparativa Revelada Simétrica (IVCRS), de Comércio Intraindústria (CII), de Concentração Setorial das Exportações (ICS) e Taxa de Cobertura das Importações (TC). Os resultados indicaram que o estado apresentou uma pauta de exportação pouco diversificada. Com isso, é possível constatar que o padrão das exportações é baseado prioritariamente em produtos intensivos em recursos naturais e produtos da indústria de transformação tradicional, os quais são pouco capazes de gerar vantagens comparativas dinâmicas, ou seja, baseados em inovações tecnológicas

ESTUDO DE CUSTOS COMPARANDO DOIS MÉTODOS DE ADMINISTRAR O AEROSSOL BRONCODILATADOR NO TRATAMENTO DA ASMA AGUDA NA SALA DE EMERGÊNCIA: NEBULIZAÇÃO INTERMITENTE COM FLUXO DE AR COMPRIMIDO VERSUS SPRAY ACOPLADO A ESPAÇADOR VALVULADO

Objetive: Bronchodilator delivery by means of metered-dose inhaler or intermittent nebulization is equivalent in the acute treatment of asthma. Some studies suggest that metereddose inhaler is less costly. The choice of the delivery method will depend on the consideration of costs. The aim of the present study is to compare the costs of aerosol bronchodilator delivery by use of an intermittent nebulizater versus metered-dose inhaler with valved spacer in patients with acute asthma in the adult emergency department.Methods: We compared the costs of different beta-adrenergic agents with and without ipratropium bromide delivered by intermittent nebulizer versus metered-dose inhaler with valved spacer in the adult emergency department of Hospital de Clínicas de Porto Alegre. Comparisons were made for 1, 6 and 12-hour treatment. The costs of all material used were taken into consideration.Results: The metered-dose inhaler with spacer was a less costly method of bronchodilator delivery in comparison to intermittent nebulization for the different beta-agonist agents, with and without ipratropium bromide.Conclusions: Bronchodilator delivery by means of a metered-dose inhaler with valved spacer was cost-saving in comparison to delivery by means of an intermittent nebulization in the treatment of acute asthma in the emergency department. The metered-dose inhaler/spacer treatment is progressively less expensive as the length of stay in the emergency department increases.Objetivo: A administração de broncodilatadores através de dispositivo com aerossol dosimetrado (spray) ou através de nebulizador é equivalente em eficácia no tratamento da asma aguda. Alguns estudos sugerem que o spray tem um custo menor. A escolha do método de administração do aerossol depende de considerações sobre o custo. O objetivo deste estudo é comparar os custos entre nebulização intermitente com fluxo de ar comprimido versus spray acoplado a espaçador valvulado na administração do aerossol broncodilatador no tratamento da asma aguda no setor de adultos da sala de emergência.Méotdo:s Comparamos os custos de diferentes agentes beta-adrenérgicos, com e sem brometo de ipratrópio, administrados por nebulização intermitente versus spray acoplado a espaçador valvulado no setor de adultos da emergência do Hospital de Clínicas de Porto Alegre. As comparações foram feitas para 1, 6 e 12 horas de tratamento. Foram considerados os custos de todos os materiais utilizados.Resutlados: O spray com espaçador consistiu em um método mais barato de administrar o broncodilatador em comparação com a nebulização intermitente para diferentes agentes beta-agonistas, com e sem ipratrópio.Conculsões: A administração do broncodilatador por spray com espaçador valvulado foi mais econômica em comparação à administração por nebulização intermitente no tratamento da asma aguda na sala de emergência. O tratamento com spray/espaçador é progressivamente mais barato à medida que o tempo de permanência no setor de emergência aumenta

Cost comparison of two aerosol bronchodilator delivery methods in patients with acute asthma in the emergency department : intermittent nebulization versus metered-dose inhaler with valved spacer

Objetivo: A administração de broncodilatadores através de dispositivo com aerossol dosimetrado (spray) ou através de nebulizador é equivalente em eficácia no tratamento da asma aguda. Alguns estudos sugerem que o spray tem um custo menor. A escolha do método de administração do aerossol depende de considerações sobre o custo. O objetivo deste estudo é comparar os custos entre nebulização intermitente com fluxo de ar comprimido versus spray acoplado a espaçador valvulado na administração do aerossol broncodilatador no tratamento da asma aguda no setor de adultos da sala de emergência. Métodos: Comparamos os custos de diferentes agentes beta-adrenérgicos, com e sem brometo de ipratrópio, administrados por nebulização intermitente versus spray acoplado a espaçador valvulado no setor de adultos da emergência do Hospital de Clínicas de Porto Alegre. As comparações foram feitas para 1, 6 e 12 horas de tratamento. Foram considerados os custos de todos os materiais utilizados. Resultados: O spray com espaçador consistiu em um método mais barato de administrar o broncodilatador em comparação com a nebulização intermitente para diferentes agentes beta-agonistas, com e sem ipratrópio Conclusões: A administração do broncodilatador por spray com espaçador valvulado foi mais econômica em comparação à administração por nebulização intermitente no tratamento da asma aguda na sala de emergência. O tratamento com spray/espaçador é progressivamente mais barato à medida que o tempo de permanência no setor de emergência aumenta. Unitermos: Estudo de custo; medicina de emergência; tratamento da asma aguda; espaçador; nebulizador.Objetive: Bronchodilator delivery by means of metered-dose inhaler or intermittent nebulization is equivalent in the acute treatment of asthma. Some studies suggest that metereddose inhaler is less costly. The choice of the delivery method will depend on the consideration of costs. The aim of the present study is to compare the costs of aerosol bronchodilator delivery by use of an intermittent nebulizater versus metered-dose inhaler with valved spacer in patients with acute asthma in the adult emergency department. Methods: We compared the costs of different beta-adrenergic agents with and without ipratropium bromide delivered by intermittent nebulizer versus metered-dose inhaler with valved spacer in the adult emergency department of Hospital de Clínicas de Porto Alegre. Comparisons were made for 1, 6 and 12-hour treatment. The costs of all material used were taken into consideration. Results: The metered-dose inhaler with spacer was a less costly method of bronchodilator delivery in comparison to intermittent nebulization for the different beta-agonist agents, with and without ipratropium bromide. Conclusions: Bronchodilator delivery by means of a metered-dose inhaler with valved spacer was cost-saving in comparison to delivery by means of an intermittent nebulization in the treatment of acute asthma in the emergency department. The metered-dose inhaler/spacer treatment is progressively less expensive as the length of stay in the emergency department increases

The value of continuity: Refined isogeometric analysis and fast direct solvers

We propose the use of highly continuous finite element spaces interconnected with low continuity hyperplanes to maximize the performance of direct solvers. Starting from a highly continuous Isogeometric Analysis (IGA) discretization, we introduce . C0-separators to reduce the interconnection between degrees of freedom in the mesh. By doing so, both the solution time and best approximation errors are simultaneously improved. We call the resulting method "refined Isogeometric Analysis (rIGA)". To illustrate the impact of the continuity reduction, we analyze the number of Floating Point Operations (FLOPs), computational times, and memory required to solve the linear system obtained by discretizing the Laplace problem with structured meshes and uniform polynomial orders. Theoretical estimates demonstrate that an optimal continuity reduction may decrease the total computational time by a factor between . p2 and . p3, with . p being the polynomial order of the discretization. Numerical results indicate that our proposed refined isogeometric analysis delivers a speed-up factor proportional to . p2. In a . 2D mesh with four million elements and . p=5, the linear system resulting from rIGA is solved 22 times faster than the one from highly continuous IGA. In a . 3D mesh with one million elements and . p=3, the linear system is solved 15 times faster for the refined than the maximum continuity isogeometric analysis

Weight Loss During the Intensive Intervention Phase of the Weight-Loss Maintenance Trial

To improve methods for long-term weight management, the Weight Loss Maintenance (WLM) trial, a four-center randomized trial, was conducted to compare alternative strategies for maintaining weight loss over a 30-month period. This paper describes methods and results for the initial 6-month weight-loss program (Phase I)