Search results for " Normal"
showing 10 items of 336 documents
Adaptive independent vector analysis for multi-subject complex-valued fMRI data.
2017
Abstract Background Complex-valued fMRI data can provide additional insights beyond magnitude-only data. However, independent vector analysis (IVA), which has exhibited great potential for group analysis of magnitude-only fMRI data, has rarely been applied to complex-valued fMRI data. The main challenges in this application include the extremely noisy nature and large variability of the source component vector (SCV) distribution. New method To address these challenges, we propose an adaptive fixed-point IVA algorithm for analyzing multiple-subject complex-valued fMRI data. We exploited a multivariate generalized Gaussian distribution (MGGD)- based nonlinear function to match varying SCV dis…
La Universidad pública española post-Covid-19: comparación de los modelos de actividad docente para el curso 2020-2021
2020
La pandemia del Covid-19 y la medida sanitaria adoptada mediante el confinamiento de la población a nivel global con diferentes grados e intensidades para tratar de controlar los contagios han afectado prácticamente a todos los sectores de la población y a las formas y maneras de desarrollar el trabajo. A escala global, las medidas de confinamiento han supuesto, al mismo tiempo, el cierre de los centros educativos en todos sus niveles. Dicha medida ha impulsado, en su mayoría, que la educación pasara de la modalidad presencial a la modalidad online. Los organismos internacionales recomendarían el desarrollo de protocolos de contingencia y adaptación de la docencia a las Instituciones de Edu…
Elliptically Symmetric Distributions: A Review of Achieved Results and Open Issues
2005
The spherically and elliptically symmetrical distributions are used in different statistical areas for different purposes such as the description of multivariate data, in order to find alternatives to the normal distribution in multinormality tests and in the creation of statistical models in which the usual assumption of normality is not realistic. Some achieved results, open issues and some proposals for their use in applications, especially in the financial area, are here presented.
A Synthetic Approach to Multivariate Normal Clustering
1982
Two methods have been suggested for grouping together observations originated from the same multivariate normal distributions, both based on a maximum-likelihood (ML) estimation, but leading to different conclusions. In this paper we compare the use of Day’s approach and that of Scott and Symons in clustering procedures from the theoretical and computational point of view. Based on this comparison, we suggest an approach unifying those approaches. The workability of the approach will be verified by numerical experiments.
How do normalization schemes affect net spillovers? A replication of the Diebold and Yilmaz (2012) study
2019
Abstract This paper replicates the Diebold and Yilmaz (2012) study on the connectedness of the commodity market and three other financial markets: the stock market, the bond market, and the FX market, based on the Generalized Forecast Error Variance Decomposition, GEFVD. We show that the net spillover indices (of directional connectedness), used to assess the net contribution of one market to overall risk in the system, are sensitive to the normalization scheme applied to the GEFVD. We show that, considering data generating processes characterized by different degrees of persistence and covariance, a scalar-based normalization of the Generalized Forecast Error Variance Decomposition is pref…
Visual information flow in Wilson-Cowan networks.
2020
In this paper, we study the communication efficiency of a psychophysically tuned cascade of Wilson-Cowan and divisive normalization layers that simulate the retina-V1 pathway. This is the first analysis of Wilson-Cowan networks in terms of multivariate total correlation. The parameters of the cortical model have been derived through the relation between the steady state of the Wilson-Cowan model and the divisive normalization model. The communication efficiency has been analyzed in two ways: First, we provide an analytical expression for the reduction of the total correlation among the responses of a V1-like population after the application of the Wilson-Cowan interaction. Second, we empiri…
How to standardize (if you must)
2017
In many situations we are interested in appraising the value of a certain characteristic for a given individual relative to the context in which this value is observed. In recent years this problem has become prominent in the evaluation of scientific productivity and impact. A popular approach to such relative valuations consists in using percentile ranks. This is a purely ordinal method that may sometimes lead to counterintuitive appraisals, in that it discards all information about the distance between the raw values within a given context. By contrast, this information is partly preserved by using standardization, i.e., by transforming the absolute values in such a way that, within the s…
A Non-Normal Incidence Pumped Ni-Like Zr XRL for Spectroscopy of Li-Like Heavy Ions at GSI/FAIR
2008
One of the unique features of the PHELIX laser installation is the combination of the ultra-high intensity laser with the heavy-ion accelerator facility at GSI and its planned extension FAIR. Due to this combination, PHELIX will allow novel investigations in the fields of plasma physics, atomic physics, nuclear physics, and accelerator studies. An important issue within the scientific program is the generation of high quality x-ray laser beams for x-ray laser spectroscopy of highly-charged ions. The long range perspective is the study of nuclear properties of radioactive isotopes within the FAIR [1] project. A novel single mirror focusing scheme for the TCE XRL has been successfully impleme…
Mode anormal de paiement. Cession de créance, Mode de paiement communément admis dans les relations d'affaires, Relations entre l'URSSAF et les assuj…
1994
International audience; (Com. 14 déc. 1993, Sudre, ès qual. c/ URSSAF du Puy-de-Dôme)
Période suspecte. Nullité de plein droit. Paiement par un procédé anormal. Convention prévoyant un paiement par remise d'animaux. Obligation pour le …
1999
International audience; (Com. 2 févr. 1999, Liquidateur de la Sté Le Calvez c/ Sté Cie Cargill-Hens)