Search results for "NETWORKS"

Paysage & [et] infrastructures de transport : modélisation des impacts des infrastructures sur les réseaux écologiques

2013

The development of linear infrastructures leads to the fragmentation and the artificialisation of the landscape across scales. Landscape fragmentation is a spatial process that is accompanied by a progressive decrease of the connectivity between the elements needed to conduct ecological processes. Thus, maintaining a good level of connectivity between natural habitats, compatible with human activities, has become a major issue for the preservation of biodiversity.By mobilizing methods from graph theory and landscape ecology, the thesis seeks to demonstrate the value of landscape graphs to model ecological networks and analyze impacts of transportation infrastructures at regional scale.The m…

Graphical models for estimating dynamic networks

2012

Het bepalen van dynamische netwerken met behulp van data is een actief onderzoeksgebied, met name in de systeem biologie. Het schatten van de structuur van een netwerk heeft te maken met het bepalen van de aan of afwezigheid van een relatie tussen de hoekpunten in de graaf. Grafische modellen definiëren deze relaties via conditionele afhankelijkheid. In Gaussiaanse grafische modellen (GGM) wordt verondersteld dat de hoekpunten een normale verdeling volgen. Dit heeft grote voordelen vanwege de computationele handelbaarheid van GGM. Standaard GGM zijn echter niet bruikbaar om grote netwerken te bestuderen, i.e. als het aantal waarnemingen minder is dan het aantal hoekpunten van de graaf. Rece…

Percolation and Schramm–Loewner evolution in the 2D random-field Ising model

2011

Abstract The presence of random fields is well known to destroy ferromagnetic order in Ising systems in two dimensions. When the system is placed in a sufficiently strong external field, however, the size of clusters of like spins diverges. There is evidence that this percolation transition is in the universality class of standard site percolation. It has been claimed that, for small disorder, a similar percolation phenomenon also occurs in zero external field. Using exact algorithms, we study ground states of large samples and find little evidence for a transition at zero external field. Nevertheless, for sufficiently small random-field strengths, there is an extended region of the phase d…

Definition of performance indicators for urban water distribution systems in drought conditions

2008

The usage of Twitter from the Spanish media during the elections

2018

Los medios de comunicación tradic ionales han adoptado Twitter c omo otro canal por el que difundir su información y llegar hasta las audiencias digit ales. Este estudio tiene como objetivo analizar las características de los tuits publicados por los me dios españoles durante doce meses en los que se producen dos procesos electorales, para comprobar las di ferencias en la utilización de esta plataforma según el contenido de la cobertura y la fase en que se publica. La investigación se fundamenta en una metodología cua ntitativa, en la que se implem enta un análisis de contenido computarizado de las publicacione s en Twitter que hacen los dis tintos tipos de medios entre 2015 y 2016. Los res…

The human peroxisome in health and disease: The story of an oddity becoming a vital organelle

2013

Abstract Since the first report by Rhodin in 1954, our knowledge on mammalian microbodies/peroxisomes has known several periods. An initial two decades period (1954–1973) has contributed to the biochemical individualisation of peroxisomes as a new class of subcellular organelles (de Duve, 1965). The corresponding research period failed to define a clear role of mammalian peroxisomes in vital functions and intermediary metabolism, explaining why feeling that peroxisomes might be in the human cell oddities has prevailed during several decades. The period standing from 1973 to nowadays has progressively removed this cell oddity view of peroxisomes by highlighting vital function and metabolic r…

Prospective study of sport dropout: A motivational analysis as a function of age and gender

2012

Abstract Introduction: This paper aimed to analyse the predictive ability of a self-determination theory (SDT) based model describing competitive sport dropout, and variance as a function of age and gender. Variables included in the model were: psychological need satisfaction, self-determined motivation, perceived conflict between sport and study, intention to practise sport, and dropout. Methods: A prospective study was performed over a period of 19 months. Variables considered as predictors of sport dropout were measured initially, and after 19 months persistence or dropout was assessed. The sample consisted of 857 athletes aged 11–19 (mean value 15.3; standard deviation = 1.77), 680 male…

From the mouth to digital spaces : mediatization and spectacularization of the political “petites phrases”

2023

The political “petites phrases” seems to occupy a growing place in the newspapers and social media. The development of web 2.0 and digital social networks have boosted this political-media phenomenon that was born in the 1970s, thanks to new formats of televised debates. Our study, based on the initial work of Krieg-Planque (2011) and Maingueneau (2012), aims to analyse specific processes and devices accompanying the reproduction of these fragments of political speech on digital social networks. To this end, we will return to the way in which “petites phrases” are detached and put into circulation, as well as to the media devices aimed at putting into spectacle and reinforcing their polemic…

Drugs and Nondrugs:  An Effective Discrimination with Topological Methods and Artificial Neural Networks

2003

A set of topological and structural descriptors has been used to discriminate general pharmacological activity. To that end, we selected a group of molecules with proven pharmacological activity including different therapeutic categories, and another molecule group without any activity. As a method for pharmacological activity discrimination, an artificial neural network was used, dividing molecules into active and inactive, to train the network and externally validate it. The following plot frequency distribution diagrams were used: a function of the number of drugs within a value interval, and the output value of the neural network versus these values. Pharmacological distribution diagram…

The Prediction of Human Intestinal Absorption Based on the Molecular Structure

2014

Human Intestinal Absorption (HIA) has been modeled many times by using classification models. However, regression models are scarce. Here, Artificial Neural Networks (ANNs) are implemented for this purpose. A dataset of structurally diverse chemicals with their respective experimental HIA were used to design robust, true predictive and widespread applicable ANN models. An input variables pool was made up of structural invariants calculated by using either Dragon or our software Desmol 1. The selection of best variables was performed following three steps using the entire dataset of molecules. Firstly, variables poorly correlated with the experimental data were eliminated. Secondly, input va…