116,947 research outputs found

    The Neumann problem for quasilinear differential equations

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    summary:In this note we prove the existence of extremal solutions of the quasilinear Neumann problem (x(t)p2x(t))=f(t,x(t),x(t))-( \vert x^{^{\prime }}(t) \vert ^{p-2}x^{^{\prime }}(t))^{^{\prime }} = f(t,x(t),x ^{^{\prime }}(t)), a.e. on TT, x(0)=x(b)=0x^{^{\prime }}(0) = x^{^{\prime }}(b) =0, 2p<2\le p < \infty in the order interval [ψ,φ][\psi ,\varphi ], where ψ\psi and φ\varphi are respectively a lower and an upper solution of the Neumann problem

    Three nontrivial solutions for the p-Laplacian Neumann problems with a concave nonlinearity near the origin

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    We consider a nonlinear Neumann problem driven by the p- Laplacian, with a right-hand side nonlinearity which is concave near the origin. Using variational techniques, combined with the method of upper-lower solutions and with Morse theory, we show that the problem has at least three nontrivial smooth solutions, two of which have a constant sign (one positive and one negative).FCTPOCI/MAT/55524/200

    Mean Curvature Flow with a Neumann Boundary Condition in Flat Spaces

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    In this thesis I study mean curvature flow in both Euclidean and Minkowski space with a Neumann boundary condition. In Minkowski space I show that for a convex timelike cone boundary condition, with compatible spacelike initial data, mean curvature flow with a perpendicular Neumann boundary condition exists for all time. Furthermore, by a blowdown argument I show convergence as t →∞ to a homothetically expanding hyperbolic hyperplane. I also study the case of graphs over convex domains in Minkowski space. I obtain long time existence for spacelike initial graphs which are taken by mean curvature flow with a Neumann boundary condition to a constant function as t →∞. In Euclidean space I consider boundary manifolds that are rotational tori where I write t for the unit vector field in the direction of the rotation. If the initial manifold M₀ is compatible with the boundary condition, and at no point has t as a tangent vector, then mean curvature flow with a perpendicular Neumann boundary condition exists for all time and converges to a flat cross-section of the boundary torus. I also discuss other constant angle boundary conditions

    Equilibrio competitivo y soportes del crecimiento en el modelo de Von Neumann

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    This paper shows the existence of a reproducible competitive equilibrium in the general Von Neumann growth model, extending in this way a result due to Roemer.

    The von Neumann Model and the Early Models of General Equilibrium

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    The paper reconstructs the von Neumann model, comments on its salient features and critically reviews some of its generalisations. The issues related to thetreatment of consumption, decomposability and uniqueness of the rate of growth and interest will be especially scrutinised. The most prominent models of general equilibrium that appeared before or roughly at the same time as von Neumann's model will be also reviewed in the paper and compared with it. It will be demonstrated that none of them had any noticeable influence on von Neumann's model, which is genuinely distinct, ideologically free and methodologically fresh and forward-looking. It will be argued that the model can be viewed as a brilliant mathematical metaphor of some deep-rooted old vision, pertaining to the core issues of commodity production

    Irrational behavior in the Brown-von Neumann-Nash dynamics

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    We present a class of games with a pure strategy being strictly dominated by another pure strategy such that the former survives along most solutions of the Brown-von Neumann-Nash dynamics.Nash map, BNN dynamics, Dominated strategies

    On The Two Dimensional Gierer-Meinhardt system with strong coupling

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    We construct solutions with a single interior condensation point for the two-dimensional Gierer-Meinhardt system with strong coupling. The condensation point is located at a nondegenerate critical point of the diagonal part of the regular part of the Green's function for -\Delta +1 nder the Neumann boundary condition. Our method is based on Liapunov-Schmidt reduction for a system of elliptic equations

    Álgebras de von Neumann - fatores

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    Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Matemática e Computação Científica, Florianópolis, 2011Dada uma álgebra de von Neumann M em L(H), onde L(H) é o espaço dos operadores lineares e limitados sobre um espaço de Hilbert H, dizemos que M é um fator se seu centro consiste somente por múltiplos escalares do operador identidade de L(H). Quando M é um fator, podemos classificá-lo em tipo I, II e III. Além disso, o tipo II pode ser dividido em dois sub-tipos. O objetivo dessa dissertação é exibir exemplos de fatores, bem como exemplos dos tipos I, II e seus sub-tipos

    Chemical electric field effects in biological macromolecules

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    Neumann E. Chemical electric field effects in biological macromolecules. Progress in Biophysics and Molecular Biology. 1986;47(3):197-231
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