Measuring the effect of node aggregation on community detection

Many times the nodes of a complex network, whether deliberately or not, are aggregated for technical, ethical, legal limitations or privacy reasons. A common example is the geographic position: one may uncover communities in a network of places, or of individuals identified with their typical geographical position, and then aggregate these places into larger entities, such as municipalities, thus obtaining another network. The communities found in the networks obtained at various levels of aggregation may exhibit various degrees of similarity, from full alignment to perfect independence. This is akin to the problem of ecological and atomic fallacies in statistics, or to the Modified Areal Unit Problem in geography. We identify the class of community detection algorithms most suitable to cope with node aggregation, and develop an index for aggregability, capturing to which extent the aggregation preserves the community structure. We illustrate its relevance on real-world examples (mobile phone and Twitter reply-to networks). Our main message is that any node-partitioning analysis performed on aggregated networks should be interpreted with caution, as the outcome may be strongly influenced by the level of the aggregation.Comment: 12 pages, 5 figure

Mercury (Hg) in meteorites: variations in abundance, thermal release profile, mass-dependent and mass-independent isotopic fractionation

We have measured the concentration, isotopic composition and thermal release profiles of Mercury (Hg) in a suite of meteorites, including both chondrites and achondrites. We find large variations in Hg concentration between different meteorites (ca. 10 ppb to 14'000 ppb), with the highest concentration orders of magnitude above the expected bulk solar system silicates value. From the presence of several different Hg carrier phases in thermal release profiles (150 to 650 {\deg}C), we argue that these variations are unlikely to be mainly due to terrestrial contamination. The Hg abundance of meteorites shows no correlation with petrographic type, or mass-dependent fractionation of Hg isotopes. Most carbonaceous chondrites show mass-independent enrichments in the odd-numbered isotopes 199Hg and 201Hg. We show that the enrichments are not nucleosynthetic, as we do not find corresponding nucleosynthetic deficits of 196Hg. Instead, they can partially be explained by Hg evaporation and redeposition during heating of asteroids from primordial radionuclides and late-stage impact heating. Non-carbonaceous chondrites, most achondrites and the Earth do not show these enrichments in vapor-phase Hg. All meteorites studied here have however isotopically light Hg ({\delta}202Hg = ~-7 to -1) relative to the Earth's average crustal values, which could suggest that the Earth has lost a significant fraction of its primordial Hg. However, the late accretion of carbonaceous chondritic material on the order of ~2%, which has been suggested to account for the water, carbon, nitrogen and noble gas inventories of the Earth, can also contribute most or all of the Earth's current Hg budget. In this case, the isotopically heavy Hg of the Earth's crust would have to be the result of isotopic fractionation between surface and deep-Earth reservoirs.Comment: 43 Pages, 9 Figures. Accepted for publication in Geochimica et Cosmochimica Act

L’Art au service de l’apprentissage du Français Langue Étrangère Apprendre le français au travers de grands artistes de l’histoire de l’art

Cet article présente une réflexion didactique et des fiches pédagogiques originales (dont un exemple en annexes) à utiliser dans l’enseignement et l’apprentissage du français langue étrangère. L’apprenant aura, dans un premier temps, le plaisir de découvrir et d’observer des chefs-d’œuvre de l’histoire de l’art. Leurs valeurs artistiques universelles transcendent les diversités individuelles et facilitent ainsi l’accès, dans un deuxième temps, aux réalités linguistiques. Si toute maîtrise d’une langue étrangère est un art, la motivation des apprenants par le biais d’œuvres d’art ne peut être qu’un éveil heureux

Lead Isotopic Composition of Fly Ash and Flue Gas Residues from Municipal Solid Waste Combustors in France: Implications for Atmospheric Lead Source Tracing.

Fly ash and flue gas residues from eight municipal solid waste combustors (MSWC) in France (1992-93 and 1998/2002) were analyzed for their Pb isotopic composition. Fly ashes are more representative of solid residual particles, whereas flue gas residues reflect mostly the composition of gas phases. Both sample types contain hundreds to thousands of micrograms of metals per gram. Leaching experiments showed that metals are present in condensed phases, probably as sulfates and chlorides, and suggest that Cd, Pb, and Zn are highly fractionated from one another during volatilization/condensation processes occurring during combustion. Although all the samples analyzed define a fairly restricted range in Pb isotopic compositions (206Pb/207Pb = 1.148-1.158 and 208Pb/206Pb = 2.101-2.114) compared to other environmental samples, some MSWC produce materials having distinct isotopic compositions, whereas others display very similar ones. Isotopic heterogeneity is also measured between samples from a single MSWC. This is interpreted as resulting from the heterogeneity of the waste source materials. The range of Pb isotopic composition of incinerator materials form a well-defined linear array in the 208Pb/206Pb versus 206Pb/207Pb diagram. This array is compatible with the previously reported European standard pollution (ESP) line and most probably represent the average lead isotopic composition of industrial atmospheric emissions in France, with the following ratios: 206Pb/207Pb = 1.154 ± 0.003 and 208Pb/206Pb = 2.107 ± 0.003 (1)

Pour un habitat écoresponsable de qualité en Saône-et-Loire

Cette thèse interroge l’accessibilité sociale et économique au logement. Elle est centrée sur une recherche prospec­tive de nouvelles formes et de nouveaux modes de production d’habitat écores­ponsable. Elle a saisi l’opportunité d’une demande de réflexion d’élus de Saône­et-Loire, et s’est déroulée dans le cadre d’une convention Cifre avec le conseil général de ce département. La méthode mise en place vise une meilleure compré­hension de la complexité du territoire d’étude avec une analyse de ses spécifici­tés, enjeux, potentiels, freins et blocages pour comprendre et éclairer les possibles afin de mener une réflexion prospective permettant de faire émerger des pistes pour un habitat écoresponsable. Une démarche itérative croisant enquêtes de terrain, analyse de références et dialogue avec les acteurs locaux a été mise en place. Pour avoir une vision globale de l’ensemble des données et faire émerger des pistes, l’outil de la carte conceptuelle, représentation graphique non linéaire, a été utilisé.The main purpose of this Ph D research is to cross-examine social and economical accessibility to housing. lt focuses on a prospective study for new production modes and forms of eco-responsible housing. lt jumped at the opportunity of a reflexion request from some elected representatives of Saône-et-Loire, and took place within the framework of a Cifre with the regional council. The method aims at providing a better understanding of the study area complexity, with an analysis of its specificities, stakes, potentials and brakes, in order to throw light on possibilities, conduct a prospective reflection, let emerging paths for an eco-responsible housing. An iterative approach has been carried out, based on field enquiries crossed with external references and dialogue with local actors. ln order to have a global vision of ail the datas and to let emerging paths, the tool of the concept map, a non-linear graphical representation, has been used

Comment on “The biosphere: A homogeniser of Pb-isotope signals” by C. Reimann, B. Flem, A. Arnoldussen, P. Englmaier, T.E. Finne, F. Koller and Ø. Nordgulen

Reimann et al. (2008) recently published a study on Pb-isotope signature along a 120 km long transect cutting the city of Oslo. Based on concentration but also isotope data, they misinterpret Pb concentration of the biosphere in rural places and explain these large enrichments of Pb as being due to natural processes. The study ignores numerous previous studies either on local, regional or global scales (see reviews by Shotyk and Le Roux, 2005 and Callender, 2003, and references therein), which clearly demonstrate that anthropogenic Pb emitted in the atmosphere from different sources (leaded gasoline, coal burning, metallurgy, etc.) was and is dispersed worldwide. The study also ignores work on Norway by the Steinnes and colleagues group (Harmens et al., 2008, Steinnes et al., 2005a, Steinnes et al., 2005b and Åberg et al., 2004), and measurements and modelling by the EMEP network (www.emep.int/, EMEP, 2005). The study also neglects numerous works on preanthropogenic Pb deposition rate and isotopic signature using continental archives of atmospheric deposition like peat bogs (Shotyk et al., 1998, Klaminder et al., 2003, Kylander et al., 2005 and Le Roux et al., 2005). These studies have shown that preanthropogenic Pb atmospheric deposition rate and its Pb isotopic signature is regionally defined, but also that those signals are negligible compared to past 2 ka and recent Pb atmospheric fluxes (Table 1)

Disability, social inclusion and the marketing of tourist attractions

Publisher policy: author can archive post-print on institutional repository after a 18 months embargo. Publisher's version/PDF cannot be used. Published source must be acknowledged. Must link to publisher version. peerreview_statement: The publishing and review policy for this title is described in its Aims & Scope. aims_and_scope_url: http://www.tandfonline.com/action/journalInformation?show=aimsScope&journalCode=rsus2

Inter-calibration of a proposed new primary reference standard AA-ETH Zn for zinc isotopic analysis

We have prepared a large volume of pure, concentrated and homogenous zinc standard solution. This new standard solution is intended to be used as a primary reference standard for the zinc isotope community, and to serve as a replacement for the nearly exhausted current reference standard, the so-called JMC-Lyon Zn. The isotopic composition of this new zinc standard (AA-ETH Zn) has been determined through an inter-laboratory calibration exercise, calibrated against the existing JMC-Lyon standard, as well as the certified Zn reference standard IRMM-3702. The data show that the new standard is isotopically indistinguishable from the IRMM-3702 zinc standard, with a weighted δ66/64Zn value of 0.28 ± 0.02‰ relative to JMC-Lyon. We suggest that this new standard be assigned a δ66/64Zn value of +0.28‰ for reporting of future Zn isotope data, with the rationale that all existing published Zn isotope data are presented relative to the JMC-Lyon standard. Therefore our proposed presentation allows for a direct comparison with all previously published data, and that are directly traceable to a certified reference standard, IRMM-3702 Zn. This standard will be made freely available to all interested labs through contact with the corresponding author