Secular dynamics and family identification among highly inclined asteroids in the Euphrosyne region

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Possible effects of secular resonances in Phobos and Triton

Due to the tides, the orbits of Phobos and Triton are contracting. While their semi major axes are decreasing, several possibilities of secular resonances involving node, argument of the pericenter and mean motion of the Sun will take place. In the case of Mars, if the obliquity (epsilon), during the passage through some resonances, is not so small, very significant variations of the inclination will appear. In one case, capture is almost certain provided that epsilon greater than or equal to 20degrees. For Triton there are also similar situations, but capture seems to be not possible, mainly because in S-1 state, Triton's orbit is sufficiently inclined (far) with respect to the Neptune's equator. Following Chyba et al. (Astron. Astrophys. 219 (1989) 123), a simplified equation that gives the evolution of the inclination versus the semi major axis, is derived. The time needed for Triton crash onto Neptune is longer than that one obtained by these authors, but the main difference is due to the new data used here. In general, even in the case of non-capture passages, some significant jumps in inclination and in eccentricities are possible. (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Cartilha de alfabetização e cultura escolar: um pacto secular

No Brasil, a partir da última década do século XIX, com a organização republicana da instrução pública, observa-se o início de um movimento de escolarização das práticas de leitura e escrita e de identificação entre o processo de ensino inicial dessas práticas e a questão dos métodos. A partir de então, a cartilha vai-se consolidando como um imprescindível instrumento de concretização dos métodos propostos e, em decorrência, de configuração de determinado conteúdo de ensino, assim como de certas silenciosas, mas operantes, concepções de alfabetização, leitura, escrita e texto, cuja finalidade e utilidade se encerram nos limites da própria escola e cuja permanência se pode observar até os dias atuais. O objetivo deste artigo é, mediante análise dessas questões, problematizar a relação entre cartilha de alfabetização e cultura escolar e seus desdobramentos na história da educação e da alfabetização em nosso país.

Dinâmica secular rotacional de corpos tri-axiais: expansão de V em ressonâncias de primeira ordem

Consider a finite body of mass m (C1) with moments of inertia A, B and C. This body orbits another one of mass much larger M (C2), which at first will be taken as a point, even if it is not completely spherical. The body C1, when orbit C2, performs a translational motion near a Keplerian. It will not be a Keplerian due to external disturbances. We will use two axes systems: fixed in the center of mass of C1 and other inertial. The C1 attitude, that is, the dynamic rotation of this body is know if we know how to situate mobile system according to inertial axes system. The strong influence exerted by C2 on C1, which is a flattened body, generates torques on C1, what affects its dynamics of rotation. We will obtain the mathematical formulation of this problem assuming C1 as a planet and C2 as the sun. Also applies to case of satellite and planet. In the case of Mercury-Sun system, the disturbing potential that governs rotation dynamics, for theoretical studies, necessarily have to be developed by powers of the eccentricity. As is known, such expansions are delicate because of the convergence issue. Thus, we intend to make a development until the third order (superior orders are not always achievable because of the volume of terms generated in cases of first-order resonances). By defining a modern set of canonical variables (Andoyer), we will assemble a disturbed Hamiltonian problem. The Andoyer's Variables allow to define averages, which enable us to discard short-term effects. Our results for the resonant angle variation of Mercury are in full agreement with those obtained by D'Hoedt & Lemaître (2004) and Rambaux & Bois (2004)

Do sagrado ao secular: a contribuição do saber médico para a construção dos cemitérios oitocentistas

Pós-graduação em História - FCHS