Collaboration networks from a large CV database: dynamics, topology and bonus impact

Understanding the dynamics of research production and collaboration may reveal better strategies for scientific careers, academic institutions and funding agencies. Here we propose the use of a large and multidisciplinar database of scientific curricula in Brazil, namely, the Lattes Platform, to study patterns of scientific production and collaboration. In this database, detailed information about publications and researchers are made available by themselves so that coauthorship is unambiguous and individuals can be evaluated by scientific productivity, geographical location and field of expertise. Our results show that the collaboration network is growing exponentially for the last three decades, with a distribution of number of collaborators per researcher that approaches a power-law as the network gets older. Moreover, both the distributions of number of collaborators and production per researcher obey power-law behaviors, regardless of the geographical location or field, suggesting that the same universal mechanism might be responsible for network growth and productivity.We also show that the collaboration network under investigation displays a typical assortative mixing behavior, where teeming researchers (i.e., with high degree) tend to collaborate with others alike. Finally, our analysis reveals that the distinctive collaboration profile of researchers awarded with governmental scholarships suggests a strong bonus impact on their productivity.Comment: 8 pages, 8 figure

Maturidade fisiológica de sementes do híbrido simples BR 201 fêmea de milho (Zea mays L.) produzidas no inverno.

Sementes de milho hibrido simples BR 201 femea produzidas no periodo de inverno, foram colhidas em intervalos de sete dias, a partir do 30 dia apos a floracao ate o 128 com o objetivo de se estudar a maturidade fisiologica. as sementes foram analisadas quanto ao grau de umidade, materia seca, ocorrencia de camada preta, germinacao e vigor. Nas condicoes em que o trabalho foi realizado, os resultados permitiram chegar as seguintes conclusoes: a maturidade fisiologica das sementes, com base no acumulo de materia seca, ocorreu aos 58 dias apos a floracao- sementes de alta qualidade fisiologica podem ser obtidas com colheitas antecipadas em relacao ao maximo acumulo de materia seca, implicando em um intervalo otimo para colheita em ate 14 dias antes do ponto de maturidade fisiologica: a producao de sementes no inverno, permite a obtencao de sementes de alta qualidade, em menor espaco de tempo que no cultivo em epoca normal

Relação entre a qualidade de semente e densidade de plantio na produção de milho.

Trabalho apresentado no X Congresso Brasileiro de Sementes

Axial-Vector Torsion and the Teleparallel Kerr Spacetime

In the context of the teleparallel equivalent of general relativity, we obtain the tetrad and the torsion fields of the stationary axisymmetric Kerr spacetime. It is shown that, in the slow rotation and weak field approximations, the axial-vector torsion plays the role of the gravitomagnetic component of the gravitational field, and is thus the responsible for the Lense-Thirring effect.Comment: 9 pages, no figures, to appear in Class. Quant. Gra