Search results for "Similarity"
showing 10 items of 474 documents
Evaluation of different similarity indices as measures of succession in arthropod communities of the forest floor after clear-cutting.
1979
Communities of spiders (Araneae) and beetles (Coleoptera) living in the soil and litter of clear-cut areas were compared with those of intact forest stands. Sixteen different indices of similarity were tested on three sets of material: spiders and beetles examined during one year in three clear-cut areas felled 3, 6 and 9 years earlier, and spiders in one clear-cut area examined during 7 successive years after felling. Other sources of evidence showed that succession in the spider community was divergent for at least 7 years after felling. The indices that seemed to express the changes best were: (1) Kendall's rank correlation test, (2) the Bray-Curtis measure, (3) Renkonen's percentage sim…
Clustering and Registration of Multidimensional Functional Data
2013
In order to find similarity between multidimensional curves, we consider the application of a procedure that provides a simultaneous assignation to clusters and alignment of such functions. In particular we look for clusters of multivariate seismic waveforms based on EM-type procedure and functional data analysis tools.
Adapted Transfer of Distance Measures for Quantitative Structure-Activity Relationships and Data-Driven Selection of Source Datasets
2012
Quantitative structure–activity relationships are regression models relating chemical structure to biological activity. Such models allow to make predictions for toxicologically relevant endpoints, which constitute the target outcomes of experiments. The task is often tackled by instance-based methods, which are all based on the notion of chemical (dis-)similarity. Our starting point is the observation by Raymond and Willett that the two families of chemical distance measures, fingerprint-based and maximum common subgraph-based measures, provide orthogonal information about chemical similarity. This paper presents a novel method for finding suitable combinations of them, called adapted tran…
The development of children's perception of hierarchical patterns : an investigation across tasks and populations
2011
The thesis investigated the development of children’s global/local processing hierarchical patterns introduced by Navon (1977). The objectives were to understand more comprehensively the developmental characteristics of children’s perception through their global and local processing of hierarchical patterns, by considering the effects of age, stimuli properties, duration of exposure to the stimuli and gender in a perceptual task and a drawing task. These effects were tested in 3 different populations: typically developing children, children with mental retardation and early blind children. The results revealed that typically developing children attended to both the local and global level of…
Deepen Into the Social Segregation of Secondary Schools in the Community of Madrid
2021
Recientes estudios han mostrado que la segregación escolar por nivel socioeconómico en la Comunidad de Madrid es muy alta, la más alta de España, y una de las más elevadas de Europa. Esta investigación profundiza en el conocimiento de la segregación escolar por nivel socioeconómico en educación secundaria con datos recientes mediante la consecución de tres objetivos: a) estimando su magnitud con diversas estrategias, calculando su perfil para 19 grupos minoritarios y comparándola con otras Comunidades; b) estudiando el papel de los centros públicos, privados concertados y no concertados; y c) determinando la aportación del programa de bilingüismo a la segregación. Se realiza una explotación…
A link between the residual-based gradient plasticity theory and the analogous theories based on the virtual work principle
2009
A link is shown to exist between the so-called residual-based strain gradient plasticity theory and the analogous theories based on the (extended) virtual work principle (VWP). To this aim, the former theory is reformulated and cast in a residual-free form, whereby the insulation condition and the (nonlocal) Clausius–Duhem inequality, on which the theory is grounded, are substituted with equivalent residual-free ingredients, namely the energy balance condition and the residual-free form of the Clausius–Duhem inequality. The equivalence of the residual-free formulation to the original one is shown, also in their ability to cope with energetic size effects and interfacial energy ones. It emer…
Prediction of the difficulty level in a standardized reading comprehension test : contributions from cognitive psychology and psychometrics
2013
Esta investigación busca identificar posibles variables predictoras del nivel de dificultad de los ítems de comprensión de lectura utilizados en una prueba psicométrica estandarizada para la admisión a una institución universitaria. Se propusieron varios posibles predictores del nivel de dificultad, a saber: densidad proposicional, negaciones, estructura sintáctica, dificultad del vocabulario, presencia elementos de realce (palabras resaltadas tipográficamente), abstracción del ítem y grado de similitud entre opción correcta y texto relevante para resolver el ítem. Mediante el Modelo Logístico Lineal de Rasgo Latente se encontró que la cantidad de proposiciones, la estructura sintáctica y, …
Weighted Likelihood Function of Multiple Statistical Parameters to Retrieve 2D TRUS-MR Slice Correspondece for Prostate Biopsy
2012
International audience; This paper presents a novel method to identify the 2D axial Magnetic Resonance (MR) slice from a pre-acquired MR prostate volume that closely corresponds to the 2D axial Transrectal Ultrasound (TRUS) slice obtained during prostate biopsy. The shape-context representations of the segmented prostate contours in both the imaging modalities are used to establish point correspondences using Bhattacharyya distance. Thereafter, Chi-square distance is used to find the prostate shape similarities between the MR slices and the TRUS slice. Normalized mutual information and correlation coefficient between the TRUS and MR slices are computed to find the information theoretic simi…
A hybrid framework of multiple active appearance models and global registration for 3D prostate segmentation in MRI.
2012
International audience; Real-time fusion of Magnetic Resonance (MR) and Trans Rectal Ultra Sound (TRUS) images aid in the localization of malignant tissues in TRUS guided prostate biopsy. Registration performed on segmented contours of the prostate reduces computational complexity and improves the multimodal registration accuracy. However, accurate and computationally efficient 3D segmentation of the prostate in MR images could be a challenging task due to inter-patient shape and intensity variability of the prostate gland. In this work, we propose to use multiple statistical shape and appearance models to segment the prostate in 2D and a global registration framework to impose shape restri…
Group analysis and similarity solutions of the compressible boundary layer equations
1989
In this paper the application of Lie's methods to the equations of the laminar boundary layer is discussed. The momentum and energy equations in Prandtl's form are considered for a steady, viscous, compressible laminar flow with non zero pressure gradient, variable viscosity and thermal conductivity. Group analysis yields similarity solutions for given pressure distributions and particular values of the invariance group parameters (group classification). Crocco's transformation is obtained for the infinite-dimensional group of the Lie's algebra admitted by the equations.