La enseñanza de la gravitación universal de Newton orientada por la historia y filosofía de la ciencia: una propuesta didáctica con un enfoque en la argumentación

Aquest treball presenta una proposta didàctica per ensenyar la gravitació universal de Newton (GU), orientada per la història i la filosofia de la ciència, per promoure millores en l'habilitat d'argumentació dels alumnes. Aquesta proposta és la culminació d'un treball més ampli que ja va produir alguns resultats (Teixeira et al., 2010a; Teixeira et al., 2010b). La proposta inclou alguns textos de referència per a la seva implementació, sent un d'ells presentat en la segona secció d'aquest treball que discuteix el layout d'argumentació de Toulmin (1958/2006), la referència sobre argumentació que subsidia el nostre treball. Presentem finalment una síntesi de la seqüència didàctica proposta i els instruments d'orientació i avaluació suggerits per a la seva implementació a la classe.This paper presents a didactical proposal to teach Newton’s universal gravitation (GU)guided by the history and philosophy of science (HPS) to promote improvements in students’ argumentation skills. This proposal is the culmination of a larger work that has already produced some results (Teixeira et al., 2010a; Teixeira et al., 2010b). The proposal includes some reference texts for implementation, one of which is presented in the second section of the paper that discusses the Toulmin’s layout of argument (Toulmin, 2006), which is the argumentation framework we have adopted in our work. Finally, this paper presents a synthesis of the didactical sequence and the tools for guidance and evaluation suggested for implementation in the classroom.Este trabajo presenta una propuesta didáctica para enseñar la gravitación universal de Newton (GU), orientada por la historia y la filosofía de la ciencia, para promover mejoras en la habilidad de argumentación de los alumnos. Esta propuesta es la culminación de un trabajo más amplio que ya produjo algunos resultados (Teixeira et al., 2010a; Teixeira et al., 2010b). La propuesta incluye algunos textos de referencia para su implementación, siendo uno de ellos presentado en la segunda sección de este trabajo que discute el layout de argumentación de Toulmin (1958/2006), la referencia sobre argumentación que subsidia nuestro trabajo. Presentamos finalmente una síntesis de la secuencia didáctica propuesta y los instrumentos de orientación y evaluación sugeridos para su implementación en la clase. 

ESTIMATION OF COST ALLOCATION COEFFICIENTS AT THE FARM LEVEL USING AN ENTROPY APPROACH

This paper aims to estimate the farm cost allocation coefficients from whole farm input costs. An entropy approach was developed under a Tobit formulation and was applied to a sample of farms from the 2004 FADN data base for Alentejo region, Southern Portugal. A Generalized Maximum Entropy model and Cross Generalized Entropy model were developed to the sample conditions and were tested. Model results were assessed in terms of their precision and estimation power and were compared with observed data. The entropy approach showed to be a flexible and valid tool to estimate incomplete information, namely regarding farm costs. Keywords: Generalized maximum entropy; costs; estimation; Alentejo, FADN

Sobre o Mestrado Nacional ProÖssional em Ensino de Física

O recém criado Mestrado Nacional Profissional em Ensino de Física, organizado pela Sociedade Brasileira de Física, com apoio da CAPES, é analisado com ênfase nos seus principais objetivos: a formação inicial e continuada de professores de física da educação básica. Elementos do projeto e sua concepçãoo, bem como o estágio atual de sua implantação, seus desafios, potencialidades elimites, são então abordados.&nbsp

Flavin-Containing Monooxygenase 1 Catalyzes the Production of Taurine from Hypotaurine

Taurine is one of the most abundant amino acids in mammalian tissues. It is obtained from the diet and by de novo synthesis, from cysteic acid or hypotaurine. Despite the discovery in 1954 that the oxygenation of hypotaurine produces taurine, the identification of an enzyme catalyzing this reaction has remained elusive. In large part this is due to the incorrect assignment, in 1962, of the enzyme as an NAD-dependent hypotaurine dehydrogenase. For more than 55 years the literature has continued to refer to this enzyme as such. Here we show, both in vivo and in vitro, that the enzyme that oxygenates hypotaurine to produce taurine is flavin-containing monooxygenase 1 (FMO1). Metabolite analysis of the urine of Fmo1-null mice by 1H NMR spectroscopy revealed a build-up of hypotaurine and a deficit of taurine in comparison with the concentrations of these compounds in the urine of wild-type mice. In vitro assays confirmed that human FMO1 catalyzes the conversion of hypotaurine to taurine utilizing either NADPH or NADH as co-factor. FMO1 has a wide substrate range and is best known as a xenobiotic- or drug-metabolizing enzyme. The identification that the endogenous molecule hypotaurine is a substrate for the FMO1-catalyzed production of taurine resolves a long-standing mystery. This finding should help establish the role FMO1 plays in a range of biological processes in which taurine or its deficiency is implicated, including conjugation of bile acids, neurotransmitter, anti-oxidant and anti-inflammatory functions, and the pathogenesis of obesity and skeletal muscle disorders

BIOREMEDIATION OF CLAY SOILS IMPACTED BY PETROLEUM

The application of bioremediation processes in recuperating contaminated sites is gaining ground, due to its efficiency in removing a number of different classes of contaminants and its cost, which tends to be lower than that of other technologies. In this work, the influence of some factors that are important for the biodegradation of the petroleum present in clay soil was studied. Experiments were conducted using two types of reactor, a slurry-phase reactor and a fixed bed reactor. The processes employed were shown to be highly effective in decontaminating the soil, achieving removal rates of around 80%

An Improved Description of the Dielectric Breakdown in Oxides Based on a Generalized Weibull distribution

In this work, we address modal parameter fluctuations in statistical distributions describing charge-to-breakdown $(Q_{BD})$ and/or time-to-breakdown $(t_{BD})$ during the dielectric breakdown regime of ultra-thin oxides, which are of high interest for the advancement of electronic technology. We reobtain a generalized Weibull distribution ($q$-Weibull), which properly describes $(t_{BD})$ data when oxide thickness fluctuations are present, in order to improve reliability assessment of ultra-thin oxides by time-to-breakdown $(t_{BD})$ extrapolation and area scaling. The incorporation of fluctuations allows a physical interpretation of the $q$-Weibull distribution in connection with the Tsallis statistics. In support to our results, we analyze $t_{BD}$ data of SiO$_2$-based MOS devices obtained experimentally and theoretically through a percolation model, demonstrating an advantageous description of the dielectric breakdown by the $q$-Weibull distribution.Comment: 5 pages, 3 figure