Search results for "descent"
showing 10 items of 99 documents
Cyclic coordinate for penalized Gaussian graphical models with symmetry restriction
2014
In this paper we propose two efficient cyclic coordinate algorithms to estimate structured concentration matrix in penalized Gaussian graphical models. Symmetry restrictions on the concentration matrix are particularly useful to reduce the number of parameters to be estimated and to create specific structured graphs. The penalized Gaussian graphical models are suitable for high-dimensional data.
A study on the degree of relationship between two individuals.
2000
The paper studies the likely degree of relationship between two individuals who could possibly be half sibs. The possible common ancestor was dead, which further complicated the problem. The model used was devised by Thompson [in Rao and Chakraborty (eds): Handbook of Statistics, North-Holland, Amsterdam, 1991] and establishes a correspondence between the possible degree of relationship and certain feasible probability distributions on the number of identical by descent genes. Two statistical approaches are considered: the classical one, in which the maximum likelihood estimation for the parameters of Thompson’s model are obtained, and the Bayesian one, in which the test of the hypothesis o…
Los Órganos de control externo (OCEX): una aproximación desde la perspectiva de las Relaciones Intergubernamentales
2017
LABURPENA: Konfiantza-ezak eta eragile politikoen arteko lankidetza-urritasunak ezaugarritu izan dituzte Espainiako gobernuen arteko harremanak. Gobernuen arteko eztabaida-testuinguru horretan, jarduera onen kasu arrakastatsu bat aurkezten du artikulu honek, non Kanpo Kontrolerako Organo Autonomikoak (OCEX) izan ziren protagonista. Autonomia-erkidego batzuek beren Kanpo Kontrolerako Organo Autonomikoak sortu zituzten, eta foroak eta lankidetza-topaketak instituzionalizatu zituzten, emaitza bikainekin, Fiskalizazioko Goi Mailako Erakundeen Nazioarteko Erakundearen (INTOSAI) «Experientia mutua omnibus prodest» leloaren pean. RESUMEN: Las relaciones intergubernamentales en España se han caract…
Determining the efficiency of optical sources using a smartphone's ambient light sensor
2017
This work reports the use of a smartphone’s ambient light sensor as a valuable tool to study and characterize the efficiency of an optical source. Here, we have measured both luminous efficacy and efficiency of several optical sources (incandescent bulb and halogen lamp) as a function of the electric power consumed and the distance to the optical detector. The illuminance of LEDs as a function of the distance to the optical detector is characterized for different wavelength emissions. Analysis of the results confirms an inverse-square law of the illuminance with the detector–source distance and shows good agreement with values obtained by classical experiments. This experience will trigger …
Evaluation of a susceptibility gene for schizophrenia on chromosome 6p by multipoint affected sib-pair linkage analysis
1995
The influence of genetic factors in schizophrenia has been convincingly demonstrated by family, twin and adoption studies, but the mode of transmission remains uncertain. The reported pattern of recurrence risks suggests a set of interacting loci. Based on prior evidence for linkage on chromosome 6p (K. Kendler, pers. comm.), we have scanned the short arm of chromosome 6 in 54 families for loci predisposing to schizophrenia, using 25 microsatellite markers spanning 60 centiMorgans (cM). Allele sharing identity by descent was examined in affected sib-pairs from these families, followed by multipoint sib-pair linkage analysis. Positive lod scores were obtained over a wide region (D6S470 to D6…
A Sequential Quadratic Programming Method for Volatility Estimation in Option Pricing
2006
Our goal is to identify the volatility function in Dupire's equation from given option prices. Following an optimal control approach in a Lagrangian framework, we propose a globalized sequential quadratic programming (SQP) algorithm with a modified Hessian - to ensure that every SQP step is a descent direction - and implement a line search strategy. In each level of the SQP method a linear-quadratic optimal control problem with box constraints is solved by a primal-dual active set strategy. This guarantees L^1 constraints for the volatility, in particular assuring its positivity. The proposed algorithm is founded on a thorough first- and second-order optimality analysis. We prove the existe…
Diagnostics of capillary light sources by means of line shape measurements and modeling
2012
In this work the Hg visible triplet spectral lines were measured by means of Fourier Transform spectrometer and deconvoluted by Tikhonov's regularisation method and line shape modelling. The lines were collected from Hg/Ar and Hg/Xe high frequency capillary lamps. In our previous work, the spatial plasma homogeneity of isotope Hg/Xe and Hg/Ar capillary lamps was investigated by means of tomography. The lamps were operated in different working positions – horizontally and vertically. In this work the spectral diagnostics of capillary light sources by means of spectral line shape measurements and modelling is presented to obtain plasma temperature. The results are compared with the results fo…
Learning the relevant image features with multiple kernels
2009
This paper proposes to learn the relevant features of remote sensing images for automatic spatio-spectral classification with the automatic optimization of multiple kernels. The method consists of building dedicated kernels for different sets of bands, contextual or textural features. The optimal linear combination of kernels is optimized through gradient descent on the support vector machine (SVM) objective function. Since a na¨ive implementation is computationally demanding, we propose an efficient model selection procedure based on kernel alignment. The result is a weight — learned from the data — for each kernel where both relevant and meaningless image features emerge after training. E…
Light transmission of the human lens and its relation with aging
2011
Purpose To determine the visible light transmission of the human crystalline lens of persons of different ages, using both solar and incandescent illumination. Methods The spectral transmission of lens was measured by using the Perkin-Elmer 800 UV/VIS spectrophotometer. With these data we calculated the percentage of visible light transmission for solar illumination, simulated by the CIE D65 illuminant, and for incandescent illumination (A illuminant). Results The total amount of visible light transmitted by nine crystalline lenses is represented as a function of age: with solar illumination and with incandescent illumination and the comparison between both illuminants.In general, the amoun…
Age‐induced change in the color of the human crystalline lens
2011
Purpose To determine the chromatic coordinates of different human crystalline lenses to analyze the age-induced change in the color of the crystalline. Methods The spectral transmission of nine human crystalline lenses of different ages were measured by using a Perkin-Elmer 800 UV/VIS spectrophotometer. Using these data we calculated the chromatic coordinates of each crystalline lens for both solar and incandescent illumination. The study adheres to the tenets of the Declaration of Helsinki for Research Including Human Subjects and was approved by the Institutional Review Board. Results The results show a greater saturation of color with the increase of age. In principle, the change tends t…