Pedigree-free animal models : the relatedness matrix reloaded

Animal models typically require a known genetic pedigree to estimate quantitative genetic parameters. Here we test whether animal models can alternatively be based on estimates of relatedness derived entirely from molecular marker data. Our case study is the morphology of a wild bird population, for which we report estimates of the genetic variance-covariance matrices (G) of six morphological traits using three methods: the traditional animal model; a molecular marker-based approach to estimate heritability based on Ritland's pairwise regression method; and a new approach using a molecular genealogy arranged in a relatedness matrix (R) to replace the pedigree in an animal model. Using the traditional animal model, we found significant genetic variance for all six traits and positive genetic covariance among traits. The pairwise regression method did not return reliable estimates of quantitative genetic parameters in this population, with estimates of genetic variance and covariance typically being very small or negative. In contrast, we found mixed evidence for the use of the pedigree-free animal model. Similar to the pairwise regression method, the pedigree-free approach performed poorly when the full-rank R matrix based on the molecular genealogy was employed. However, performance improved substantially when we reduced the dimensionality of the R matrix in order to maximize the signal to noise ratio. Using reduced-rank R matrices generated estimates of genetic variance that were much closer to those from the traditional model. Nevertheless, this method was less reliable at estimating covariances, which were often estimated to be negative. Taken together, these results suggest that pedigree-free animal models can recover quantitative genetic information, although the signal remains relatively weak. It remains to be determined whether this problem can be overcome by the use of a more powerful battery of molecular markers and improved methods for reconstructing genealogies.

Discapacidad intelectual y necesidades educativas especiales asociadas.

Tratar de llegar a conseguir una forma de diagnóstico de la discapacidad intelectual asociada a retraso mental ligero (r.m.l.) en el ámbito escolar a través del diseño de una forma diferente de evaluación de la discapacidad cognitiva y partiendo de los resultados obtenidos en esta investigación. Se realizan tres estudios empíricos: Estudio 1. Evaluación de las capacidades cognitivas. Los tests de inteligencia (K-BIT, WISC-R, MATRICES PROGRESIVAS DE RAVEN Y TONI-2) se administran a 88 niños y 63 niñas de Enseñanza Primaria Obligatoria de 6 a 12 años de diez centros escolares de zonas de Málaga de actuación educativa preferente. Los alumnos de estos centros son de clase social baja y media baja. Es un criterio común entre los profesores o diferentes profesionales que trabajan en esta zona el identificar estos centros como semejantes en esta condición. Es preciso aclarar que la muestra inicial es de 205 alumnos. Seis de estos centros son de titularidad pública y cuatro privados concertados. Los instrumentos utilizados son Tests de Inteligencia y Cuestionario Criterio. Estudio 2. Evaluación de las diferencias entre alumnos diagnosticados con y sin discapacidad en relación con las capacidades cognitivas. Los sujetos que participan en esta investigación son 136 niños y niñas (67 y 69) de Enseñanza Primaria Obligatoria de 6 a 12 años de diez centros escolares de zonas de Málaga de actuación educativa preferente. Los alumnos de esta muestra son de clase social baja y media baja. De los que participan, 57 son asignados a grupo de discapacidad y 69 a grupo de no discapacidad. La asignación a cada grupo la hace la orientadora de cada centro, una vez aplicados los tests de inteligencia, cumplimentado el Cuestionario Criterio y llegando a un consenso en cada caso con el profesor tutor del alumno. Además de los tests de inteligencia y del Cuestionario Criterio citados en el estudio 1, se han utilizado como materiales específicos para esta investigación el Test de la Figura Compleja de Rey y las Notas Escolares. Estudio 3. Estudio del cuestionario aplicado a los orientadores. El cuestionario se envía a 60 profesionales distribuidos de la siguiente forma. Un total de 30 cuestionarios se entrega a los orientadores en ejercicio de los Equipos de Orientación Educativa de Málaga (titulados que forman parte de la Asociación de Psicólogos y Pedagogos de Málaga, ASIPEMA), mediante correo electrónico o bien personalmente; 30 cuestionarios más se entregan a otros orientadores de Enseñanza Primaria. Todos estos profesionales son titulados en Psicología, Pedagogía o Psicopedagogía, con al menos 5 años de experiencia. De ellos se reciben cumplimentados los de 35 orientadores (6 titulados en Pedagogía, 18 titulados en Psicología, 2 en Psicopedagogía y 9 en Psicología y Pedagogía), en total 21 mujeres y 14 hombres . Se ha partido de que a veces el diagnóstico de retraso mental puede no estar claramente delimitado, lo que da lugar a confusiones en el diagnóstico. Si se sigue el criterio que se expone, la mayoría de los alumnos que se califican en los colegios como retrasados, no lo son. La demanda de evaluación y diagnóstico de retraso mental responde más a una necesidad de ayuda del profesor para ese alumno concreto en cuanto a dificultades de aprendizaje o problemas de conducta que a una supuesta discapacidad o deficiencia. Como resultado de los dos primeros estudios empíricos se puede decir que, en la muestra que se ha analizado, existen diferencias entre los tests que se utilizan para la evaluación de la inteligencia, pero esta diferencia no ha sido significativa en el caso de los tests K-BIT y MATRICES PROGRESIVAS DE RAVEN, siendo éstos dos los que presentan una puntuación media con respecto al resto de los tests empleados, por lo que parece que es más útil la utilización de ambas pruebas. Como resumen de las conclusiones obtenidas se destaca lo siguiente: La opinión de los profesionales expertos que cumplimentaron el cuestionario, es que en la valoración de la discapacidad mental se deben incluir como componentes el funcionamiento intelectual global y el específico, la conducta adaptativa, la competencia curricular, la motivación para aprender y el potencial de aprendizaje.

The spectrum of an open vertex model based on the U(q)[SU(2)] algebra at roots of unity

We study the exact solution of an N-state vertex model based on the representation of the U(q)[SU(2)] algebra at roots of unity with diagonal open boundaries. We find that the respective reflection equation provides us one general class of diagonal K-matrices having one free-parameter. We determine the eigenvalues of the double-row transfer matrix and the respective Bethe ansatz equation within the algebraic Bethe ansatz framework. The structure of the Bethe ansatz equation combine a pseudomomenta function depending on a free-parameter with scattering phase-shifts that are fixed by the roots of unity and boundary variables. (C) 2010 Elsevier B.V. All rights reserved.

Abelian vectors and self-dual tensors in six-dimensional supergravity

In this note we describe the most general coupling of abelian vector and tensor multiplets to six-dimensional (1,0) supergravity. As was recently pointed out, it is of interest to consider more general Chern-Simons couplings to abelian vectors of the type H(r) = dB(r) - 1/2 c(rab)AadAb, with c(r) matrices that may not be simultaneously diagonalized. We show that these couplings can be related to Green-Schwarz terms of the form B(r)c(r)/abFaFb, and how the complete local Lagrangian, that embodies factorized gauge and supersymmetry anomalies (to be disposed of by fermion loops) is uniquely determined by Wess-Zumino consistency conditions, aside from an arbitrary quartic coupling for the gauginos. (C) 2000 Elsevier Science B.V.

Eigenvalues of Casimir invariants for Uq[osp(m|n)]

For each quantum superalgebra U-q[osp(m parallel to n)] with m > 2, an infinite family of Casimir invariants is constructed. This is achieved by using an explicit form for the Lax operator. The eigenvalue of each Casimir invariant on an arbitrary irreducible highest weight module is also calculated. (c) 2005 American Institute of Physics.

Generalized Perk-Schultz models: solutions of the Yang-Baxter equation associated with quantized orthosymplectic superalgebras

The Perk-Schultz model may be expressed in terms of the solution of the Yang-Baxter equation associated with the fundamental representation of the untwisted affine extension of the general linear quantum superalgebra U-q (gl(m/n)], with a multiparametric coproduct action as given by Reshetikhin. Here, we present analogous explicit expressions for solutions of the Yang-Baxter equation associated with the fundamental representations of the twisted and untwisted affine extensions of the orthosymplectic quantum superalgebras U-q[osp(m/n)]. In this manner, we obtain generalizations of the Perk-Schultz model.

2-D R-matrix propagation: A large scale electron scattering simulation dominated by the multiplication of dynamically changing matrices

We examine the computational aspects of propagating a global R-matrix, R, across sub-regions in a 2-D plane. This problem originates in the large scale simulation of electron collisions with atoms and ions at intermediate energies. The propagation is dominated by matrix multiplications which are complicated because of the dynamic nature of R, which changes the designations of its rows and columns and grows in size as the propagation proceeds. The use of PBLAS to solve this problem on distributed memory HPC machines is the main focus of the paper.

Structural and textural variations in carbonaceous chondrite matrices

Recent studies of C2 carbonaceous chondrite matrices using high resolu­tion transmission electron microscopy (HRTEM)have shown that structural details of the matrix minerals can be imaged [1-4]. The Murchison and Mighei matrices contain minerals having ordered and disordered mixed-layer structures [1,3,4] in addition to chrysotile- and lizardite-type structures [2].

Improved estimation of size-transition matrices using tag-recapture data

We derive a new method for determining size-transition matrices (STMs) that eliminates probabilities of negative growth and accounts for individual variability. STMs are an important part of size-structured models, which are used in the stock assessment of aquatic species. The elements of STMs represent the probability of growth from one size class to another, given a time step. The growth increment over this time step can be modelled with a variety of methods, but when a population construct is assumed for the underlying growth model, the resulting STM may contain entries that predict negative growth. To solve this problem, we use a maximum likelihood method that incorporates individual variability in the asymptotic length, relative age at tagging, and measurement error to obtain von Bertalanffy growth model parameter estimates. The statistical moments for the future length given an individual's previous length measurement and time at liberty are then derived. We moment match the true conditional distributions with skewed-normal distributions and use these to accurately estimate the elements of the STMs. The method is investigated with simulated tag-recapture data and tag-recapture data gathered from the Australian eastern king prawn (Melicertus plebejus).

The connection between Mueller and Jones matrices of polarization optics

A necessary and sufficient condition for the 4 × 4 Mueller matrix to be derivable from the 2 × 2 Jones matrix is obtained. This condition allows one to determine if a given Mueller matrix describes a totally polarized system or a partially polarized (depolarizing) system. The result of Barakat is analysed in the light of this condition. A recently reported experimentally measured Mueller matrix is examined using this condition and is shown to represent a partially polarized system.

Improved estimation of size-transition matrices using tag-recapture data

We derive a new method for determining size-transition matrices (STMs) that eliminates probabilities of negative growth and accounts for individual variability. STMs are an important part of size-structured models, which are used in the stock assessment of aquatic species. The elements of STMs represent the probability of growth from one size class to another, given a time step. The growth increment over this time step can be modelled with a variety of methods, but when a population construct is assumed for the underlying growth model, the resulting STM may contain entries that predict negative growth. To solve this problem, we use a maximum likelihood method that incorporates individual variability in the asymptotic length, relative age at tagging, and measurement error to obtain von Bertalanffy growth model parameter estimates. The statistical moments for the future length given an individual’s previous length measurement and time at liberty are then derived. We moment match the true conditional distributions with skewed-normal distributions and use these to accurately estimate the elements of the STMs. The method is investigated with simulated tag–recapture data and tag–recapture data gathered from the Australian eastern king prawn (Melicertus plebejus).

A complete characterization of pre-Mueller and Mueller matrices in polarization optics

The Mueller-Stokes formalism that governs conventional polarization optics is formulated for plane waves, and thus the only qualification one could require of a 4 x 4 real matrix M in order that it qualify to be the Mueller matrix of some physical system would be that M map Omega((pol)), the positive solid light cone of Stokes vectors, into itself. In view of growing current interest in the characterization of partially coherent partially polarized electromagnetic beams, there is a need to extend this formalism to such beams wherein the polarization and spatial dependence are generically inseparably intertwined. This inseparability brings in additional constraints that a pre-Mueller matrix M mapping Omega((pol)) into itself needs to meet in order to be an acceptable physical Mueller matrix. These additional constraints are motivated and fully characterized. (C) 2010 Optical Society of America