451 research outputs found
Local Isometric immersions of pseudo-spherical surfaces and evolution equations
The class of differential equations describing pseudo-spherical surfaces,
first introduced by Chern and Tenenblat [3], is characterized by the property
that to each solution of a differential equation, within the class, there
corresponds a 2-dimensional Riemannian metric of curvature equal to . The
class of differential equations describing pseudo-spherical surfaces carries
close ties to the property of complete integrability, as manifested by the
existence of infinite hierarchies of conservation laws and associated linear
problems. As such, it contains many important known examples of integrable
equations, like the sine-Gordon, Liouville and KdV equations. It also gives
rise to many new families of integrable equations. The question we address in
this paper concerns the local isometric immersion of pseudo-spherical surfaces
in from the perspective of the differential equations that give
rise to the metrics. Indeed, a classical theorem in the differential geometry
of surfaces states that any pseudo-spherical surface can be locally
isometrically immersed in . In the case of the sine-Gordon
equation, one can derive an expression for the second fundamental form of the
immersion that depends only on a jet of finite order of the solution of the
pde. A natural question is to know if this remarkable property extends to
equations other than the sine-Gordon equation within the class of differential
equations describing pseudo-spherical surfaces. In an earlier paper [11], we
have shown that this property fails to hold for all other second order
equations, except for those belonging to a very special class of evolution
equations. In the present paper, we consider a class of evolution equations for
of order describing pseudo-spherical surfaces. We show that
whenever an isometric immersion in exists, depending on a jet of
finite order of , then the coefficients of the second fundamental forms are
functions of the independent variables and only.Comment: Fields Institute Communications, 2015, Hamiltonian PDEs and
Applications, pp.N
Implantação do curso pós-técnico florestal na Amazônia.
1 CD-ROM. Autoria bilíngue: CONGRESSO E EXPOSICAO INTERNACIONAL SOBRE FLORESTAS, 5., 1999, Curitiba
Forrageiras em regime de corte avaliadas pela técnica in vitro semi-automática de produção de gases.
O objetivo deste trabalho foi determinar, atraves da tecnica in vitro semi-automatica de producao de gases, os potenciais maximos de producao de gases, degradabilidade da materia seca (DMS) e as taxas de producao de gases (mi) e de degradacao da MS (c) do capim Elefante (Pennisetum purpureum) - cv. Napier, cana-de-acucar (Saccharum officinarum) - var. rb 72454 e de dois hibridos de sorgo com capim Sudao (Sorghum bicolor x Sorghum sudanense) - AG 2501 e BRS 800, avaliados em regime de corte. Foi utilizado o modelo de descricao matematica da cinetica ruminal proposto por FRANCE et al. (1993( ara determinacao dos potenciais maximos de producao de gases (A) de 237, 232, 217 e 213 ml/g MS e taxas de producao de gases (mi) de 0,028, 0,079, 0,022 ml/h, empregando-se a equacao sugerida por ORSKOV et al. (1980) , foram encontrados potenciais de degradabilidade da MS (A) de 68,7, 66,2, 65,9 e 65,8% e taxas de degradacao da MS (c) de 0,054, 0,033, 0,051 e 0,049 %/h para o capim Elefante, a cana-de-acucar, o Ag 2501 e o BRS 800, respectivamente. para todos os alimentos foram notadas altas correlacoes entre as producoes cumulativas de gases e as degradabilidades da MS
Extensão de recomendação da cultivar de arroz de terras altas "BRS Soberana" para Goiás.
A BRS Soberana originou-se de um cruzamento triplo realizado pela Embrapa Arroz e Feijão, em 1990, envolvendo os genitores Cuiabana, CNAx 1235-8-3 e CNA 6673. A fim de compensar a redução da disponibilidade de sementes da BRS Primavera, a Embrapa Arroz e Feijão lançou uma nova cultivar de padrão próximo ao dela, a BRS Soberana, que se mostrara, inicialmente, melhor adaptada ao Estado do Mato Grosso.bitstream/CNPAF/21541/1/comt_73.pd
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