479 research outputs found
GEOGRAPHICAL LABOUR MOBILITY IN SPAIN - A PANEL DATA APPROACH
In this paper, we study geographical labour mobility taken by workers in Spain from a regional standpoint. Using a panel data set referred to the evolution of these decisions in the 1990-2003 period, the main objective is to determine what are the main variables that influence in labour mobility as well as to quantify their impact. To this respect, regional labour market status, spatial variations in employment opportunities and house prices have turned to be the main determinants. Furthermore, also certain socio-demographic characteristic of workers such as education, marital status and the presence of children in the household are also of great relevant.
Vuong and Wald tests. Simplicity vs. Complexity
The specification of cross-sectional models is usually solved following a traditional procedure, highly supported by practitioners. In the first step, a simple model is proposed that will be subsequently improved with different elements if the evidence so advises. This procedure expedites the econometric solution and fits well into the Lagrange Multiplier approach, which contributes to explain its current popularity. However, there are other methods that could also be used, and some of them are considered in this paper. Specifically, we turn our attention to the Vuong test, developed in the context of the Kullback-Leibler information measure. This test represents an intermediate solution between the complexity inherent in the Wald test and the simplicity of the Lagrange Multiplier principle.
Morphological Scale-Space Operators for Images Supported on Point Clouds
International audienceThe aim of this paper is to develop the theory, and to propose an algorithm, for morphological processing of images painted on point clouds, viewed as a length metric measure space . In order to extend morphological operators to process point cloud supported images, one needs to define dilation and erosion as semigroup operators on . That corresponds to a supremal convolution (and infimal convolution) using admissible structuring function on . From a more theoretical perspective, we introduce the notion of abstract structuring functions formulated on length metric Maslov idempotent measurable spaces, which is the appropriate setting for . In practice, computation of Maslov structuring function is approached by a random walks framework to estimate heat kernel on , followed by the logarithmic trick
( max , min )-convolution and Mathematical Morphology
International audienceA formal denition of morphological operators in (max, min)-algebra is introduced and their relevant properties from an algebraic viewpoint are stated. Some previous works in mathematical morphology have already encountered this type of operators but a systematic study of them has not yet been undertaken in the morphological literature. It is shown in particular that one of their fundamental property is the equivalence with level set processing using Minkowski addition and subtraction. Theory of viscosity solutions of the Hamilton-Jacobi equation with Hamiltonians containing u and Du is summarized, in particular, the corresponding Hopf-Lax-Oleinik formulas as (max, min)-operators. Links between (max, min)-convolutions and some previous approaches of unconventional morphology, in particular fuzzy morphology and viscous morphology, are reviewed
Morphological bilateral filtering
International audienceA current challenging topic in mathematical morphology is the construction of locally adaptive operators; i.e., structuring functions that are dependent on the input image itself at each position. Development of spatially-variant filtering is well established in the theory and practice of Gaussian filtering. The aim of the first part of the paper is to study how to generalize these convolution-based approaches in order to introduce adaptive nonlinear filters that asymptotically correspond to spatially-variant morphological dilation and erosion. In particular, starting from the bilateral filtering framework and using the notion of counter-harmonic mean, our goal is to propose a new low complexity approach to define spatially-variant bilateral structuring functions. Then, in the second part of the paper, an original formulation of spatially-variant flat morphological filters is proposed, where the adaptive structuring elements are obtained by thresholding the bilateral structuring functions. The methodological results of the paper are illustrated with various comparative examples
Morphological PDE and dilation/erosion semigroups on length spaces
International audienceThis paper gives a survey of recent research on Hamilton-Jacobi partial dierential equations (PDE) on length spaces. This theory provides the background to formulate morphological PDEs for processing data and images supported on a length space, without the need of a Riemmanian structure. We first introduce the most general pair of dilation/erosion semigroups on a length space, whose basic ingredients are the metric distance and a convex shape function. The second objective is to show under which conditions the solution of a morphological PDE in the length space framework is equal to the dilation/erosion semigroups
Structure Tensor Image Filtering using Riemannian L_1 and L_∞ Center-of-Mass
Structure tensor images are obtained by a Gaussian smoothing of the dyadic product of gradient image. These images give at each pixel a n×n symmetric positive definite matrix SPD(n), representing the local orientation and the edge information. Processing such images requires appropriate algorithms working on the Riemannian manifold on the SPD(n) matrices. This contribution deals with structure tensor image filtering based on Lp geometric averaging. In particular, L1 center-of-mass (Riemannian median or Fermat-Weber point) and L∞ center-of-mass (Riemannian circumcenter) can be obtained for structure tensors using recently proposed algorithms. Our contribution in this paper is to study the interest of L1 and L∞ Riemannian estimators for structure tensor image processing. In particular, we compare both for two image analysis tasks: (i) structure tensor image denoising; (ii) anomaly detection in structure tensor images
Does economic freedom increase income inequality? Evidence from the EU countries
Over the past decades there have been considerable changes in policies and institutions in favor of economic freedom in the EU countries. This trend coincides with widespread increases in income inequality in numerous member states. To what extent does economic freedom encourage inequality? This paper examines the relationship between economic freedom and income inequality in the EU countries using panel data for the 2000s. The empirical evidence suggests that economic freedom seems to entail greater income inequality. However, not all areas of economic freedom affect income distribution similarly. While government size and regulation appear to be robustly associated with income inequality, legal system and property rights, sound money, and freedom to trade internationally seem not to be significantly related with income distribution in the European context.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
- …