Una propuesta : enseñar física a niños de grados elementales

With the purpose of doing a previous presentation on Physics issues to children in their school initial steps, we intend to discuss a proposition using the scope of some tales as an appropriate tool to reach that objective. Our paper deals with two experiences. We have presented and established some comments in two of our municipality of Rio de Janeiro schools. In one of them, a public school which deals with students of a lower economic class and another one, a private school dealing with students of a middle economic class. In order to assist achvely in the process of Physics teaching, as a sequence of our proposition, we are describing one of our experiences, which is being developed with educators responsible for students of these levels

Pesos ao nascimento, a desmama e ao sobreano de animais Nelores e cruzados Canchim X Nelore.

Com o objetivo de avaliar o potencial da raça Canchim em cruzamentos, estudaram-se os pesos ao nascimento, a desmama e ao sobreano de bezerros Nelores e cruzados Canchim X Nelore, nascidos durante o período de 1987 a 1990 e criados em regime de pastagens na região Oeste do Estado de São Paulo.Resumo

Tecnologia de sementes de Sclerolobium paniculatum Vogel.

O trabalho envolveu a tecnologia de sementes de Sclerolobium paniculatum Vogel, tachi-branco, tendo sido realizado no Laboratório de Sementes Florestais ? Embrapa Amazônia Oriental. A espécie Sclerolobium paniculatum Vogel, apresentou baixa percentagem de germinação em laboratório sendo necessário maior desenvolvimento de pesquisa para definir a sua utilização mais adequada

Aplicação de técnicas de sensoriamento remoto na estimativa da biomassa vegetal de pastagem no Mato Grosso do Sul.

As técnicas de sensoriamento remoto têm sido promissoras para o desenvolvimento de medidas confiáveis e economicamente viáveis da produção vegetal em grandes áreas. Este trabalho objetivou aplicação de técnicas de sensoriamento remoto e do algoritmo SEBAL (Surface Energy Balance Algorithm for Land) na estimativa da biomassa vegetal acima do solo das áreas de pastagem na Fazenda Experimental da Embrapa Gado de Corte, Campo Grande, Mato Grosso do Sul. Para a área de estudo, foram encontrados valores de biomassa vegetal variando de 0 a 4.755 kg MS ha-1, com valor médio de 1.981 kg MS ha-

COMPARISON BETWEEN ANALYTICAL PYROLYSIS AND NITROBENZENE OXIDATION FOR DETERMINATION OF SYRINGYL/GUAIACYL RATIO IN Eucalyptus spp. LIGNIN

Pyrolysis-gas chromatography/mass spectrometry (Py-GC-MS) was applied to measure the lignin syringyl/guaiacyl (S/G) ratio in E. dunni, E. grandis, E. nitens, E. urograndis, and E. urophylla woods. A total of 41 compounds were identified, of which 11 were derived from carbo-hydrates and 30 from lignins. The S/G ratio was calculated on the basis of the areas of peaks recorded in the pyrograms and compared with the results obtained by alkaline nitrobenzene oxidation. The values of S/G found by pyrolysis were similar for all the species using the compounds guaiacol, 4-methylguaiacol, 4-vinylguaiacol, vanillin, 4-ethylsyringol, 4-vinylsyringol, homosyringaldehyde, acetosyringone, and syringylacetone, as lignin markers. The selected markers were efficient for the deter-mination of S/G ratio in eucalyptus wood by Py-GC-MS. The Py-GC-MS technique produced results that are comparable to the nitrobenzene oxidation method, with the advantage of requiring small wood samples and a short analysis time