Analysis of residual dependencies of independent components extracted from fMRI data

Independent component analysis (ICA) of functional magnetic resonance imaging (fMRI) data can be employed as an exploratory method. The lack in the ICA model of strong a priori assumptions about the signal or about the noise leads to difficult interpretations of the results. Moreover, the statistical independence of the components is only approximated. Residual dependencies among the components can reveal informative structure in the data. A major problem is related to model order selection, that is, the number of components to be extracted. Specifically, overestimation may lead to component splitting. In this work, a method based on hierarchical clustering of ICA applied to fMRI datasets is investigated. The clustering algorithm uses a metric based on the mutual information between the ICs. To estimate the similarity measure, a histogram-based technique and one based on kernel density estimation are tested on simulated datasets. Simulations results indicate that the method could be used to cluster components related to the same task and resulting from a splitting process occurring at different model orders. Different performances of the similarity measures were found and discussed. Preliminary results on real data are reported and show that the method can group task related and transiently task related components

Auto and crosscorrelograms for the spike response of LIF neurons with slow synapses

An analytical description of the response properties of simple but realistic neuron models in the presence of noise is still lacking. We determine completely up to the second order the firing statistics of a single and a pair of leaky integrate-and-fire neurons (LIFs) receiving some common slowly filtered white noise. In particular, the auto- and cross-correlation functions of the output spike trains of pairs of cells are obtained from an improvement of the adiabatic approximation introduced in \cite{Mor+04}. These two functions define the firing variability and firing synchronization between neurons, and are of much importance for understanding neuron communication.Comment: 5 pages, 3 figure

Transparency, Openness and Knowledge Sharing for Rebuilding and Strengthening Government Institutions

The developing of the Open Government Model is allowing an organizational revolution for public administrations, providing to citizens and entrepreneurs a better access to information and public services. It also can allow the increasing of transparency in public agencies and citizen participation, indirectly enhancing collaboration and facilitating democratic processes. Transparency and open data can be powerful tools to stimulate and support public services’ improvements, faster innovation and empower citizens’ rights. So actually many governmental organizations are reviewing and rearranging their processes, information and data to improve policies, enhance legitimacy and openness toward outside parties and citizens. An “open” public knowledge may contribute to establish a collaboration and participation culture among the main stakeholders. In this paper authors focus on a new organizational model to deliver transparent services and to improve an effective collaboration between the public administrations. The research methodology adopted is based on a theoreticaldeductive approach. The study describes general principles to come, through the case strategy, to the empirical analysis of an innovative national government portal called “Transparency Compass Portal”. It tries also to identify the distinctive aspects of some administrative services offered by several public organizations

Modeling dry-port-based freight distribution planning

In this paper we review the dry port concept and its outfalls in terms of optimal design and management of freight distribution. Some optimization challenges arising from the presence of dry ports in intermodal freight transport systems are presented and discussed. Then we consider the tactical planning problem of defining the optimal routes and schedules for the fleet of vehicles providing transportation services between the terminals of a dry-port-based intermodal system. An original service network design model based on a mixed integer programming mathematical formulation is proposed to solve the considered problem. An experimental framework built upon realistic instances inspired by regional cases is described and the computational results of the model are presented and discussed

A field study on thermal comfort in naturally - ventilated buildings located in the equatorial climatic region of Cameroon

The purpose of this research is to create a thermal comfort data base in three climatic regions in Cameroon. This will help to define guidelines for constructing more comfortable buildings in Cameroon. There is not enough data regarding comfort in residential environment in the inter tropical sub Saharan Africa. Thus experimental and subjective results of hygrometric thermal comfort conducted in 290 buildings located in three cities of the equatorial climatic zone of Cameroon is presented. An adaptive approach according to ASHRAE55/2004, ISO7730 and 10551 was adopted. A specific questionnaire has been elaborated for the investigation. 710 questionnaires in the dry season and 410 in the rainy season were distributed to inhabitants and filled while different experimental value of indoor parameters were measured. The comfortable temperature ranges for the three cities was found between 22. 1 C and 29.1 C. The 61.24 % of voters found acceptable their thermal habitat, the 13.72% considered it neutral

Sign-changing tower of bubbles for a sinh-Poisson equation with asymmetric exponents

Motivated by the statistical mechanics description of stationary 2D-turbulence, for a sinh-Poisson type equation with asymmetric nonlinearity, we construct a concentrating solution sequence in the form of a tower of singular Liouville bubbles, each of which has a different degeneracy exponent. The asymmetry parameter $\gamma\in(0,1]$ corresponds to the ratio between the intensity of the negatively rotating vortices and the intensity of the positively rotating vortices. Our solutions correspond to a superposition of highly concentrated vortex configurations of alternating orientation; they extend in a nontrivial way some known results for $\gamma=1$. Thus, by analyzing the case $\gamma\neq1$ we emphasize specific properties of the physically relevant parameter $\gamma$ in the vortex concentration phenomena

Almond diversity and homozygosity define structure, kinship, inbreeding, and linkage disequilibrium in cultivated germplasm, and reveal genomic associations with nut and seed weight

Almond [Prunus dulcis Miller (D.A. Webb)] is the main tree nut species worldwide. Here, genotyping-by-sequencing (GBS) was applied to 149 almond cultivars from the ex situ collections of the Italian Council for Agricultural Research (CREA) and the Spanish National Research Council (CSIC), leading to the detection of 93,119 single-nucleotide polymorphisms (SNPs). The study of population structure outlined four distinct genetic groups and highlighted diversification between the Mediterranean and Californian gene pools. Data on SNP diversity and runs of homozygosity (ROHs) allowed the definition of kinship, inbreeding, and linkage disequilibrium (LD) decay in almond cultivated germplasm. Four-year phenotypic observations, gathered on 98 cultivars of the CREA collection, were used to perform a genome-wide association study (GWAS) and, for the first time in a crop species, homozygosity mapping (HM), resulting in the identification of genomic associations with nut, shell, and seed weight. Both GWAS and HM suggested that loci controlling nut and seed weight are mostly independent. Overall, this study provides insights on the almond cultivation history and delivers information of major interest for almond genetics and breeding. In a broader perspective, our results encourage the use of ROHs in crop science to estimate inbreeding, choose parental combinations minimizing the risk of inbreeding depression, and identify genomic footprints of selection for specific traits