Clustering Dynamique par Rayon

National audienceComprendre les dynamiques d'évolution de réseaux sociaux et d'infrastructuresest un problème crucial dans les domaines comme l'épidémiologie, l'urbanismeou la marketing viral. Une quantité croissante de données dynamiquessur des réseaux divers est disponible depuis plusieurs années maisles outils pour analyser ces données ne sont pas toujours adaptés.Nous proposons d'utiliser ces données dynamique pour faire des groupesd'individus de comportement similaire restant stables avec le temps.Pour cela nous introduisons une variante dynamique du problème Sum-Radii Clustering, en utilisant le formalisme du problème DynamicFacility Location, avec la distinction que nous cherchons à minimiser le diamètre des groupes aulieu de la somme des distances au centre. Nous étudions deux adaptations naturelles d'algorithmes probabilistes utilisés pour Dynamic Facility Location (marchant respectivement dans le cas général et quand on se restreint à des espaces métriques). Dans le premier cas, l'algorithme atteint la même borne d'approximation et nous proposons une amélioration, aussi valable pour l'algorithme original (faisant passer le facteur d'approximation de $O(\log nT)$ à $O(\log n)$, où $n$ est le nombre de clients et $T$ la durée en nombre de pas de temps).Enfin, nous montrons que dans le cas métrique, les outils actuels ne permettent pas encorede donner un meilleur résultat, et exhibons un contre-exemple pour le deuxième algorithme, prouvant qu'il ne peut pas atteindre une approximation constante

Gender Differences in Communication with One\u27s Mother and Father and Its Effects on Feelings of Depression Among Young Adults

Depression among young adults is a growing concern that becomes more severe every year. Several factors can contribute to one’s feelings of depression including how much someone communicates their feelings to their parents. Communication with parent’s relationship to depression among young adults is a largely unexplored area of research that this study covers. The purpose of this study is to test gender differences in communication with one’s parents and how parental communication affects feelings of depression. Using the third wave of the National Study of Youth and Religion (NSYR), a nationally representative data set consisting of 1680 young adults living in the United States, this study tests several hypotheses analyzing this relationship. I show that young adults who communicate their feelings to their parents have lower feelings of depression, young adult women are generally more depressed than young adult men, young adults are more likely to communicate their feelings to the same gendered parent, and communicating with either one’s mother or father affects feelings of depression at about the same rate. The results found in the present analysis differ from those found in prior research. This is likely due to differences between adolescents and young adults. These contrary results encourage that more research in this area be done focusing on young adults or older age groups

Steam reforming of pyrolysis oil using nickel-spinel based catalysis

Introduction – Rationale In many areas worldwide, electricity is mainly produced using fuelled generators or as a supplementary power source. The energy efficiency of those units is typically below 30% excluding production and distribution costs. Replacing the fossil fuels used in electricity production with biofuels will allow for lower carbon print, although the amount of biomass available may not be sufficient in arid areas such as the Canadian arctic. It is therefore necessary to reduce the consumption of the propellant by the unit. Fuel cells, which reach an efficiency of 65%, reduce the amount of fuel required by half. Fuel cells do not use liquid fuels directly, but rather a reformer is included to the device to reform the biofuel into syngas or hydrogen-rich syngas. The challenge with reforming complex molecules into syngas lies with carbon deposition. For example, Chen et al.1 tested the La1-xKxMnO3 catalyst, while Xing et al.2 performed catalysis of Co, Ni and Rh over MgAl2O4 for steam reforming of pyrolytic oil from vegetal and both observed carbon deposition. This work focuses on the steam reforming of pyrolytic oils originating from plastic and vegetal materials as biofuels. A comparison is drawn between the behavior of (a) a nickel-alumina spinel catalyst mixed with yttrium oxide stabilized zirconia (YSZ), and (b) a catalyst made of mine wastes (known as UGS), impregnated with nickel. The NiAl2O4-YSZ catalyst used in this study has already been tested for steam reforming of diesel3-5 and other liquid hydrocarbons6 and dry reforming of methane7-8 while the Ni-UGS catalyst has been tested for dry and steam reforming of methane9. Please click Additional Files below to see the full abstract