An implicit finite difference approximation to the one-dimensional transport equation

The properties of an implicit three-level finite difference scheme are investigated. The modified equivalent partial differential equation is used to determine the speed and amplitude characteristics of the scheme, and these are used to determine the optimal value of the weighting between a central difference and an upwind biased difference. Results of numerical experiments that confirm that the predicted value of the weight does minimise the error are presented

Control of sulphide during anaerobic treatment of S-containing wastewaters by adding limited amounts of oxygen or nitrate

Sulphide generated during anaerobic treatment of S-containing wastewaters represents an environmental problem. Adding limited amounts of oxygen or nitrate (or nitrite) to biologically (or chemically) oxidise sulphide forms a simple process level strategy to control this problem. This short review evaluates the feasibility and limitations of this strategy on the basis of the results of bioreactor studies.Sulphide generated during anaerobic treatment of S-containing wastewaters represents an environmental problem. Adding limited amounts of oxygen or nitrate (or nitrite) to biologically (or chemically) oxidise sulphide forms a simple process level strategy to control this problem. This short review evaluates the feasibility and limitations of this strategy on the basis of the results of bioreactor studies.Spanish Ministry of Education and Science; AEA Technology Environment; Nova Energie; The Swedish Gas Centre; University of Southern Denmark

Influence of Milk-Feeding Type and Genetic Risk of Developing Coeliac Disease on Intestinal Microbiota of Infants: The PROFICEL Study

Interactions between environmental factors and predisposing genes could be involved in the development of coeliac disease (CD). This study has assessed whether milk-feeding type and HLA-genotype influence the intestinal microbiota composition of infants with a family history of CD. The study included 164 healthy newborns, with at least one first-degree relative with CD, classified according to their HLA-DQ genotype by PCR-SSP DQB1 and DQA1 typing. Faecal microbiota was analysed by quantitative PCR at 7 days, and at 1 and 4 months of age. Significant interactions between milk-feeding type and HLA-DQ genotype on bacterial numbers were not detected by applying a linear mixed-model analysis for repeated measures. In the whole population, breast-feeding promoted colonization of C. leptum group, B. longum and B. breve, while formula-feeding promoted that of Bacteroides fragilis group, C. coccoides-E. rectale group, E. coli and B. lactis. Moreover, increased numbers of B. fragilis group and Staphylococcus spp., and reduced numbers of Bifidobacterium spp. and B. longum were detected in infants with increased genetic risk of developing CD. Analyses within subgroups of either breast-fed or formula-fed infants indicated that in both cases increased risk of CD was associated with lower numbers of B. longum and/or Bifidobacterium spp. In addition, in breast-fed infants the increased genetic risk of developing CD was associated with increased C. leptum group numbers, while in formula-fed infants it was associated with increased Staphylococcus and B. fragilis group numbers. Overall, milk-feeding type in conjunction with HLA-DQ genotype play a role in establishing infants' gut microbiota; moreover, breast-feeding reduced the genotype-related differences in microbiota composition, which could partly explain the protective role attributed to breast milk in this disorder

Modeling effects of voltage dependent properties of the cardiac muscarinic receptor on human sinus node function.

The cardiac muscarinic receptor (M2R) regulates heart rate, in part, by modulating the acetylcholine (ACh) activated K+ current IK,ACh through dissociation of G-proteins, that in turn activate KACh channels. Recently, M2Rs were noted to exhibit intrinsic voltage sensitivity, i.e. their affinity for ligands varies in a voltage dependent manner. The voltage sensitivity of M2R implies that the affinity for ACh (and thus the ACh effect) varies throughout the time course of a cardiac electrical cycle. The aim of this study was to investigate the contribution of M2R voltage sensitivity to the rate and shape of the human sinus node action potentials in physiological and pathophysiological conditions. We developed a Markovian model of the IK,ACh modulation by voltage and integrated it into a computational model of human sinus node. We performed simulations with the integrated model varying ACh concentration and voltage sensitivity. Low ACh exerted a larger effect on IK,ACh at hyperpolarized versus depolarized membrane voltages. This led to a slowing of the pacemaker rate due to an attenuated slope of phase 4 depolarization with only marginal effect on action potential duration and amplitude. We also simulated the theoretical effects of genetic variants that alter the voltage sensitivity of M2R. Modest negative shifts in voltage sensitivity, predicted to increase the affinity of the receptor for ACh, slowed the rate of phase 4 depolarization and slowed heart rate, while modest positive shifts increased heart rate. These simulations support our hypothesis that altered M2R voltage sensitivity contributes to disease and provide a novel mechanistic foundation to study clinical disorders such as atrial fibrillation and inappropriate sinus tachycardia

A trajetória de Henrique da Rocha Lima e as relações teuto-brasileiras (1901-1956) The career of Henrique da Rocha Lima and German-Brazilian relations (1901-1956)

A trajetória de Henrique da Rocha Lima vincula-se estreitamente às relações científicas e culturais entre Brasil e Alemanha. Seus trabalhos científicos foram produzidos em instituições de pesquisa biomédica dos dois países, mas foi na Alemanha que ele conquistou projeção internacional, graças a suas pesquisas nos campos da microbiologia, patologia e medicina tropical. Lastreado pelo prestígio e boa inserção nas comunidades científicas brasileira e alemã, contribuiu para o estreitamento do intercâmbio intelectual entre os dois países, mobilizando diversos personagens e instituições como pontos de apoio. Apresentam-se percalços e desafios impostos pelo estudo desse personagem complexo, cuja trajetória lança luz, a um só tempo, sobre os meandros das relações científicas internacionais e sobre processos sócio-históricos marcantes na institucionalização das ciências no Brasil.<br>The career of Henrique da Rocha Lima is closely linked to cultural and scientific relations between Brazil and Germany. He pursued his scientific work at biomedical research institutions in both countries, but it was in Germany that he attained international standing, thanks to his research in the fields of microbiology, pathology and tropical medicine. His prestige and active participation in both Brazil's and Germany's scientific communities meant he was able to further academic interchange between both nations, mobilizing many people and institutions to contribute to this process. I present the obstacles and challenges faced in studying this complex character, whose career sheds light on the machinations of international scientific relations and some socio-historical processes that marked the institutionalization of science in Brazil

Current pediatric indications for cisapride: A position paper by a panel convened by the European Society for Pediatric Gastroenterology, Hepatology and Nutrition

SCOPUS: re.jinfo:eu-repo/semantics/publishe

Field science in the Railroad Era: the tools of knowledge empire in the American West, 1869-1916 Pesquisas de campo na era das ferrovias: os instrumentos do império dos conhecimentos no Oeste dos Estados Unidos, 1869-1916

Focusing on the field sciences during the late nineteenth and early twentieth centuries, this paper analyzes how railroads served as tools of knowledge empire in the American West. The political economy of this region, shaped by the rise of Populism and capitalist development with federal and state government support, provided the context for cooperation between field scientists and railroad companies. Early on, the displacement of American Indians and their concentration on reservations was intertwined with the research of the Bureau of Ethnology under John Wesley Powell. Later, railroad companies became important patrons of field research, primarily through their provision of free or reduced-fare passes for travel. This research ranged from state universities undertaking research in horticulture and irrigation engineering to metropolitan natural history museums whose field work in paleontology had cultural or symbolic value.<br>Ao analisar pesquisas de campo realizadas no final do século XIX e início do XX, o artigo mostra como as estradas de ferro foram instrumentos do império dos conhecimentos no Oeste dos Estados Unidos. A economia política da região foi modelada pela ascensão do populismo e pelo desenvolvimento do capitalismo com o apoio dos governos estaduais e federal. Criaram-se assim as condições para a cooperação entre cientistas e companhias ferroviárias. Num primeiro momento, o deslocamento dos índios e sua concentração em reservas estiveram relacionados às pesquisas do Escritório de Etnologia, então dirigido por John Wesley Powell. As companhias ferroviárias tornaram-se importantes patrocinadoras de pesquisas de campo fornecendo passagens gratuitas ou a custos reduzidos para as viagens dos cientistas, desde aqueles ligados a universidades públicas que promoviam estudos sobre horticultura e engenharia da irrigação, até museus metropolitanos de história natural, cujos trabalhos de campo em paleontologia tinham valor simbólico ou cultural