A unified law of motion of lithospheric plates and the driving mechanism

From observed data on lithospheric plates, a unified empirical law for plate motion,valid for continental as well as oceanic plates, is obtained in the following form: The speedof plate motion U depends linearly on a geometric parameter T_d, ratio of the sum of effectiveridge length and trench arc length to the sum of area of continental part of plate and total areaof cold sinking slab. Based on this unified law, a simple mechanical analysis shows that, themain driving forces for lithospheric plates come from push along the mid-ocean ridge andpull by the cold sinking slab, while the main drag forces consist of the viscous traction beneaththe continental part of plate and over both faces of the sinking slab. Moreover, the specific-push along ridge and pull by slab are found to be of equal magnitude.

A scaling law of photoionization in ultrashort pulses

By means of the numerical solution of time-dependant Schrodinger equation, we verify a scaling law of photoionization in ultrashort pulses. We find that for a given carrier-envelope phase and duration of the pulse, identical photoionizations are obtained provided that when the central frequency of the pulse is enlarged by k times, the atomic binding potential is enlarged by k times, and the laser intensity is enlarged by k(3) times. The scaling law allows us to reach a significant control over direction of photoemission and offers exciting prospects of reaching similar physical processes in different interacting systems which constitutes a novel kind of coherent control.

A scaling law of photoelectron angular distributions in one-cycle laser pulses

The photoelectron angular distributions (PADs) from above-threshold ionization of atoms irradiated by one-cycle laser pulses satisfy a scaling law. The scaling law denotes that the main features of the PADs are determined by four dimensionless parameters: (1) the ponderomotive number u(p) = U-p/hw, the ponderomotive energy U-p in units of laser photon energy; (2) the binding number E-b = E-b/h(w), the atomic binding energy E-b in units of laser photon energy; (3) the number of absorbed photons q; (4) the carrier-envelope phase phi(0), the phase of the carrier wave with respect to the envelope. We verify the scaling law by theoretical analysis and numerical calculation, compared to that in long-pulse case. A possible experimental test to verify the scaling law is suggested.

A scaling law of photoionization in few-cycle regime

In this paper, a scaling law of photoionization of atoms irradiated by intense, few- cycle laser pulses is established. The scaling law sets a relation to the phase- dependent ionization with the kinetic energy of photoelectrons, the duration and peak intensity of short pulses, and the ionization potential of the target atoms. We find that it will be advantageous to manifest the phase- dependent photoionization by choosing the target atoms with larger ionization potential, using laser with smaller carrier- frequency, and increasing the pulse intensity. (c) 2007 Optical Society of America.

O cantar da Germânia: política e cultura na Alemanha na passagem dos séculos XII e XIII

Esta tese desenvolvida na linha de pesquisa Política e Cultura destaca o interesse pelos fenômenos da transmissão do conhecimento intelectual. A tese reconstrói a expressão da cultura política medieval germânica pela ótica de dois poetas, Walther von der Vogelweide e Wolfram von Eschenbach, integrantes da aristocracia guerreira. Os suportes teóricos dos Sprüche, sentenças de natureza política de Vogelweide e do Parzifal de Eschenbach, foram fundamentais para compreender o posicionamento político e cultural alemão frente às transformações que afetaram a Cristandade no período de fins do século XII ao início do século XIII. Esse período foi marcado pelo confronto de Papas e Imperadores em torno do direito de exercer a autoridade no âmbito do Sacro Império Romano-Germânico. O movimento cruzadista, o renascimento urbano e a ascensão de novos atores sociais burgueses integram o conjunto dos elementos a serem levados em conta na elaboração da tese. A ideia norteadora do trabalho tornou necessário recorrer a obras literárias com objetivo de elucidar questões de natureza histórica, tendo claro que a Literatura não é um contraponto da História e o texto resultante contribua para ressignificar a produção política da cultura medieval e um melhor entendimento dos mecanismos do poder na Alemanha medieval. No plano teórico-metodológico recorremos à chamada História Cultural fornecendo uma visão integradora dos planos político, social e econômico.