Marcos da história da radioatividade e tendências atuais

The first days of radioactivity, the discoveries of X-rays, radioactivity, of alpha- and beta- particles and gamma- radiation, of new radioactive elements, of artificial radioactivity, the neutron and positron and nuclear fission are reviewed as well as several adverse historical marks, such as the Manhattan project and some nuclear and radiological accidents. Nuclear energy generation in Brazil and the world, as an alternative to minimize environmental problems, is discussed, as are the medicinal, industrial and food applications of ionizing radiation. The text leads the reader to reflect on the subject and to consider its various aspects with scientific and technological maturity.

Rigidez do papelão ondulado: comparação entre resultados experimentais e os obtidos por cálculo analítico

Cardboard packing for horticultural products has as main function to protect them. The design of a cardboard packing request the knowledge of the bending stiffens which is depending on the modulus of elasticity. The objective of this work was to calculate the cardboard modulus of elasticity from data obtained in laboratory using physical characterization test, with different methods, and comparing the results with the values obtained experimentally. Ten samples of each cardboard selected for this study were tested in the paper fabrication direction and in its transverse direction. The papers liner and medium resistance to the traction, used to calculate the bending stiffness, was determined in a universal machine test. To obtaining of the bending stiffens the four points test was accomplished. Expressive variations among the methods from which the modulus of elasticity is obtained were observed and that influence the bending stiffness of the structure. The stiffness values obtained experimentally were always greater than the values obtained from analytical method. This difference can be attributed to two factors, the production processes that assurance a larger rigidity than the components separately and the addition of the adhesive layer that is not taken in consideration in the analytic calculations.

História, filosofia e sociologia da educação matemática na formação do professor: um programa de pesquisa

We present and discuss in this article some features of a research program whose central object of investigation is the way in which the recent fields of history, philosophy, and sociology of mathematical education could take part in a critical and qualified manner in the initial and continuing training of teachers in this area. For that, we endorse the viewpoint that the courses for mathematics teacher education should be based on a conception of specificity through which a new pedagogical project could be established. In such project those new fields of investigation would participate, in an organic and clarifying way, in the constitution of multidimensional problematizations of school practices, in which mathematics would be involved, and that would be guided by academic investigations about the issues that currently challenge teachers in the critical work of incorporation, resignification, production, and transmission of mathematical culture in the context of the school institution.

História do lazer na natureza no Rio de Janeiro entre 1779 e 1838 : um estudo de caso

Universidade Estadual de Campinas . Faculdade de Educação Física

Comitê Paralímpico Brasileiro : 15 anos de história

Universidade Estadual de Campinas. Faculdade de Educação Física