1,720,999 research outputs found
Engenharia didática e a sequência de padovan e tridovan: uma análise preliminar e a priori
Get PDFNeste trabalho é apresentada uma abordagem didática matemática, por meio da Engenharia Didática, num contexto do objeto de estudo da Sequência de Padovan e da sua extensão Tridovan. Ademais, utiliza-se as suas duas primeiras fases, apresentando uma análise didática e epistemológica durante a primeira fase. Durante a segunda fase, são apresentados possíveis comportamentos dos alunos, orientados pela Teoria das Situações Didáticas, ao elaborar e analisar três situações- problema propostas, podendo serem aplicadas em cursos de formação inicial de professores
Algumas propriedades sobre os números de Richard Padovan e de François Olivier Raoul Perrin (1910)
Get PDFOs autores de livros de História da Matemática costumam desconsiderar, de modo frequente, um amplo conjunto de exemplos de sequências numéricas recorrentes. De fato, aparentemente, a sequência de Fibonacci costuma ser a sequência numérica preferida dos mesmos, em detrimento de vários outros exemplos de sequências. Dessa forma, a presente proposta de sala de aula visa explorar propriedades sobre os números originados das sequências numéricas recorrentes introduzidas por Richard Padovan e pelo engenheiro francês François Olivier Raoul Perrin. Dessa forma, a partir do trabalho de Diskaya & Menken (2022) são propostas um roteiro de situações didáticas visando encetar um projeto investigativo em sala de aula, no contexto da formação inicial de professores de Matemática
Algumas propriedades sobre os números de Richard Padovan e de François Olivier Raoul Perrin (1910)
Get PDFOs autores de livros de História da Matemática costumam desconsiderar, de modo frequente, um amplo conjunto de exemplos de sequências numéricas recorrentes. De fato, aparentemente, a sequência de Fibonacci costuma ser a sequência numérica preferida dos mesmos, em detrimento de vários outros exemplos de sequências. Dessa forma, a presente proposta de sala de aula visa explorar propriedades sobre os números originados das sequências numéricas recorrentes introduzidas por Richard Padovan e pelo engenheiro francês François Olivier Raoul Perrin. Dessa forma, a partir do trabalho de Diskaya & Menken (2022) são propostas um roteiro de situações didáticas visando encetar um projeto investigativo em sala de aula, no contexto da formação inicial de professores de Matemática
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Ion channel and membrane translocation of diphtheria toxin
No full textDiphtheria toxin is the best studied member of a family of bacterial protein toxins which act inside cells. To reach their cytoplasmic targets, these toxins, which include tetanus and botulinum neurotoxins and anthrax toxin, have to cross the hydrophobic membrane barrier. All of them have been shown to form ion channels across planar lipid bilayer and, in the case of diphtheria toxin, also in the plasma membrane of cells. A relation between the ion channel and the process of membrane translocation has been suggested and two different models have been put forward to account for these phenomena. The two models are discussed on the basis of the available experimental evidence and in terms of the focal points of difference, amenable to further experimental investigations. © 1992
DETERMINATION OF DIPHTHERIA-TOXIN NEUTRALIZING ANTIBODY-TITERS WITH A CELL PROTEIN-SYNTHESIS INHIBITION ASSAY
No full textA method which allows an accurate determination of very low titers of antibodies able to neutralize diphtheria toxin has been developed. The assay is based on the incubation of a reference amount of diphtheria toxin with different dilution of the serum and the evaluation of the residual toxicity of diphtheria toxin on Vero cells. The cells are seeded in 96-well plastic plates with the toxin-serum mixtures and the residual toxin activity is measured as the block of cell protein synthesis after incubation with [14C]leucine. Antitoxin titers as low as 0.002 IU can be reproducibly and accurately measured and the method gives a linear response in the range 0.002 to 8.0 IU/ml
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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