Hyers-Ulam-Rassias Stability of Functional Differential Systems with Point and Distributed Delays

This paper investigates stability and asymptotic properties of the error with respect to its nominal version of a nonlinear time-varying perturbed functional differential system subject to point, finite-distributed, and Volterra-type distributed delays associated with linear dynamics together with a class of nonlinear delayed dynamics. The boundedness of the error and its asymptotic convergence to zero are investigated with the results being obtained based on the Hyers-Ulam-Rassias analysis.

Optical transfer of periodic microstructures by interfering femtosecond laser beams

We report on an optical interference method for transferring periodic microstructures of metal film from a supporting substrate to a receiving substrate by means of five-beam interference of femtosecond laser pulses. Scanning electron microscopy and optical microscopy revealed microstructures with micrometer-order were transferred to the receiving substrate. In the meanwhile, a negative copy of the transferred structures was induced in the metal film on the supporting substrate. The diffraction characteristics of the transferred structures were also evaluated. The present technique allows one-step realization of functional optoelectronic devices. (C) 2005 Optical Society of America.

Acima de tudo eu sou professora, educadora, e posso mostrar para eles que eu faço com muito amor": um estudo das representações do professor de inglês sobre seu fazer por meio do Sistema da Avaliatividade

Este trabalho tem por objetivo investigar as representações de professores de língua inglesa de um curso livre de idiomas no Rio de Janeiro, acerca de sua própria profissão e de outros aspectos relacionados ao ensino desta disciplina, procurando identificar a maneira como o discurso destes profissionais constrói suas identidades. Buscamos apontar como são construídas e negociadas no discurso características identitárias dos professores de inglês a fim de compreender como estes professores se veem ou constroem uma imagem de um bom professor de inglês. Para realizar a análise recorremos ao Sistema de Avaliatividade proposto por Martin & White (2005), cujos princípios têm origem na metafunção interpessoal da Linguística Sistêmico Funcional (Halliday, 2004), além de algumas importantes noções da Análise do Discurso Crítica (Fairclough, 2003), especialmente no que diz respeito à concepção de linguagem, discurso e sua relação com as práticas sociais. O conceito de representação utilizado nesta pesquisa foi fundamentado em Minayo (1994) e Fairclough (2003) e a noção de identidade baseia-se em Fairclough (2003) e Hall (2000), observando que as identidades não são apenas representadas no discurso, mas construídas nele, além de terem um caráter instável, mutável, multifacetado e inacabado. O Corpus analisado consiste em transcrição de uma discussão entre oito professores de inglês e foi coletado através da técnica de Grupo Focal. Foram selecionados 20 trechos de falas desta discussão e agrupadas em três temas: a) O professor nativo / Experiência no exterior; b) Ser professor de língua inglesa / O valor da profissão; e c) Como me vejo como professor/a de inglês. Analisamos as avalições feitas segundo os subsistemas de Atitude e Engajamento. Os resultados da análise mostraram que este grupo de professores utiliza preferencialmente avaliações negativas de julgamento de capacidade quando se trata de avaliar o professor nativo, avaliações positivas de julgamento de capacidade e tenacidade quando se trata de avaliar o professor de inglês não nativo e, principalmente, avaliações positivas do tipo Afeto quando se trata de avaliar a profissão ou a sua prática diária. Somados a outros itens recorrentes, estes resultados apontam para o perfil de um bom professor na visão do grupo de sujeitos participantes

Multiple stable reference points in oyster populations: biological relationships for the eastern oyster (Crassostrea virginica) in Delaware Bay

Abstract—In the first of two companion papers, a 54-yr time series for the oyster population in the New Jersey waters of Delaware Bay was analyzed to develop biological relationships necessary to evaluate maximum sustainable yield (MSY) reference points and to consider how multiple stable points affect reference point-based management. The time series encompassed two regime shifts, one circa 1970 that ushered in a 15-yr period of high abundance, and a second in 1985 that ushered in a 20-yr period of low abundance. The intervening and succeeding periods have the attributes of alternate stable states. The biological relationships between abundance, recruitment, and mortality were unusual in four ways. First, the broodstock–recruitment relationship at low abundance may have been driven more by the provision of settlement sites for larvae by the adults than by fecundity. Second, the natural mortality rate was temporally unstable and bore a nonlinear relationship to abundance. Third, combined high abundance and low mortality, though likely requiring favorable environmental conditions, seemed also to be a self-reinforcing phenomenon. As a consequence, the abundance –mortality relationship exhibited both compensatory and depensatory components. Fourth, the geographic distribution of the stock was intertwined with abundance and mortality, such that interrelationships were functions both of spatial organization and inherent populatio

Multiple stable reference points in oyster populations: implications for reference point-based management

In the second of two companion articles, a 54-year time series for the oyster population in the New Jersey waters of Delaware Bay is analyzed to examine how the presence of multiple stable states affects reference-point–based management. Multiple stable states are described by four types of reference points. Type I is the carrying capacity for the stable state: each has associated with it a type-II reference point wherein surplus production reaches a local maximum. Type-II reference points are separated by an intermediate surplus production low (type III). Two stable states establish a type-IV reference point, a point-of-no-return that impedes recovery to the higher stable state. The type-II to type-III differential in surplus production is a measure of the difficulty of rebuilding the population and the sensitivity of the population to collapse at high abundance. Surplus production projections show that the abundances defining the four types of reference points are relatively stable over a wide range of uncertainties in recruitment and mortality rates. The surplus production values associated with type-II and type-III reference points are much more uncertain. Thus, biomass goals are more easily established than fishing mortality rates for oyster population

A New Type of Coincidence and Common Fixed Point Theorem with Applications

Coincidence and common fixed point theorems for a class of 'Ciric-Suzuki hybrid contractions involving a multivalued and two single-valued maps in a metric space are obtained. Some applications including the existence of a common solution for certain class of functional equations arising in a dynamic programming are also discussed..