7,091 research outputs found
Embedding a regular subpencil into a general linear pencil
AbstractWe study the possible strictly equivalence classes of a pencil when a regular subpencil is prescribed. We also study the possible invariant polynomials and the possible characteristic polynomials of A+BY+XC+XDY when X and Y vary
Weakly spectrally complete pair of matrices
Let and be matrices over an algebraically closed field. Let be elements of such that and . We give necessary and sufficient condition for the existence of matrices and similar to and, respectively, such that has eigenvalues
Schr\"odinger formalism for a particle constrained to a surface in
In this work it is studied the Schr\"odinger equation for a non-relativistic
particle restricted to move on a surface in a three-dimensional Minkowskian
medium , i.e., the space equipped with the
metric . After establishing the consistency of the
interpretative postulates for the new Schr\"odinger equation, namely the
conservation of probability and the hermiticity of the new Hamiltonian built
out of the Laplacian in , we investigate the confining
potential formalism in the new effective geometry. Like in the well-known
Euclidean case, it is found a geometry-induced potential acting on the dynamics
which, besides
the usual dependence on the mean () and Gaussian () curvatures of the
surface, has the remarkable feature of a dependence on the signature of the
induced metric of the surface: if the signature is ,
and if the signature is . Applications to surfaces of
revolution in are examined, and we provide examples where the
Schr\"odinger equation is exactly solvable. It is hoped that our formalism will
prove useful in the modeling of novel materials such as hyperbolic
metamaterials, which are characterized by a hyperbolic dispersion relation, in
contrast to the usual spherical (elliptic) dispersion typically found in
conventional materials.Comment: 26 pages, 1 figure; comments are welcom
Completion problems for real matrices, II
Thirty years ago, G.N. de Oliveira has proposed the following completion problems: Describe the possible characteristic polynomials of [C-ij], i,j is an element of {1, 2}, where C-1,C-1 and C-2,C-2 are square submatrices, when some of the blocks C-ij are fixed and the others vary. Several of these problems remain unsolved. This paper gives the solution, over the field of real numbers, of Oliveira's problem where the blocks C-1,C-1, C-2,C-2 are fixed and the others vary
Why are some prices stickier than others? Firm-data evidence on price adjustment lags
Infrequent price changes at the firm level are now well documented in the literature. However, a number of issues remain partly unaddressed. This paper contributes to the literature on price stickiness by investigating the lags of price adjustments to different types of shocks. We find that adjustment lags to cost and demand shocks vary with firm characteristics, namely the firm’s cost structure, the type of pricing policy, and the type of good. We also document that firms react asymmetrically to demand and cost shocks, as well as to positive and negative shocks, and that the degree and direction of the asymmetry varies across firms. JEL Classification: C41, D40, E31Firm heterogeneity, Panel-ordered probit, real rigidities, survey data
Estratégia h-adaptativa para a análise elasto-plástica bidimensional
Neste trabalho apresenta-se uma estratégia h-adaptativa para problemas de elasticidade bidimensional, discretizados por elementos finitos triangulares lineares, considerando a nao linearidade do material. Esta estratégia é baseada na técnica de remalhamento (remeshing) onde, através de estimativa de erro a posteriori, se prediz o tamanho do elemento necessário para atingir um nível de precisao pré-especificado. O comportamento nao linear do material é tratado através do modelo de subcamadas, nao se limitando portanto a modelos bilineares.Peer Reviewe
Estratégia h-adaptativa para a análise elasto-plástica bidimensional
Neste trabalho apresenta-se uma estratégia h-adaptativa para problemas de elasticidade bidimensional, discretizados por elementos finitos triangulares lineares, considerando a nao linearidade do material. Esta estratégia é baseada na técnica de remalhamento (remeshing) onde, através de estimativa de erro a posteriori, se prediz o tamanho do elemento necessário para atingir um nível de precisao pré-especificado. O comportamento nao linear do material é tratado através do modelo de subcamadas, nao se limitando portanto a modelos bilineares.Peer Reviewe
Symmetry Constrained Two Higgs Doublet Models
We study Two-Higgs-Doublet Models (2HDM) where Abelian symmetries have been
introduced, leading to a drastic reduction in the number of free parameters in
the 2HDM. Our analysis is inspired in BGL models, where, as the result of a
symmetry of the Lagrangian, there are tree-level scalar mediated
Flavour-Changing-Neutral-Currents, with the flavour structure depending only on
the CKM matrix. A systematic analysis is done on the various possible schemes,
which are classified in different classes, depending on the way the extra
symmetries constrain the matrices of couplings defining the flavour structure
of the scalar mediated neutral currents. All the resulting flavour textures of
the Yukawa couplings are stable under renormalisation since they result from
symmetries imposed at the Lagrangian level. We also present a brief
phenomenological analysis of the most salient features of each class of
symmetry constrained 2HDM.Comment: 30 pages, 5 Table
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