Identification of complex network topologies through delayed mutual information

The definitions of delayed mutual information and multi-information are recalled. It is shown how the delayed mutual information may be used to reconstruct the interaction topology resulting from some unknown scale-free graph with its associated local dynamics. Delayed mutual information is also used to solve the community detection problem. A probabilistic voter model defined on a scale-free graph is used throughout the paper as an illustrative example.Comment: 6 pages, 9 figures. arXiv admin note: text overlap with arXiv:1911.0654

Transmission of Migration Propensity Increases Genetic Divergence Between Populations

The advent of molecular genetics has brought invaluable information, which is now routinely used by anthropologists in their attempt to reconstruct our demographic past. Since the mitochondrial DNA loci are much more similar between populations than are the Y chromosome loci, it has been suggested that women had a much higher migration rate than men throughout history. Based on an examination of intergenerational migration patterns in three large demographic databases, we bring this inference into question. In some early Canadian settlements (St. Lawrence Valley and Saguenay), and in the past Krummhörn region of Northwest Germany, men whose father was a migrant were more likely to migrate, while the migration probability of women was largely independent of that of their mothers. As a result, men’s movements were less effective in preventing genetic differentiation between populations than women’s movements. If it is largely prevalent among human societies, this male-specific transmission of migration propensity could partly explain the geographical clustering of Y chromosome distributions. In order to account for its impact, we propose a slight modification of Wright’s Island model. We also address the relevance of this model with respect to previously reported measures of population differentiation and we discuss the supporting historical and anthropological literature. We conclude that the widespread patrilocal rules of post-marital residence have generated both a higher female migration rate and a patrilineal dependency in the propensity to migrate

Films d'oxydes semi-conducteurs nanoporeux et nanocristallins pour dispositifs photovoltaïques hybrides

Dans le contexte de la mise au point de dispositifs photovoltaïques efficaces, bon marché et respectueux de l environnement, la synthèse d oxydes métalliques semi-conducteurs tels que SnO2, Zn2SnO4 et WO3 de morphologies et textures diverses a été développée afin d élaborer des photoanodes poreuses pour cellules solaires à colorant. D après les études réalisées par différentes méthodes (MEB, MET, DRX et BET), les matériaux obtenus présentent des caractéristiques texturales, morphologiques et structurales appropriées pour l application visée. Des cellules solaires à colorant ont donc été réalisées à partir de ces oxydes, puis différents paramètres influençant leurs performances ont été optimisés afin d améliorer l efficacité de la conversion photovoltaïque. Notamment l influence positive de différents traitements des photoanodes (i.e. solution aqueuse de TiCl4 ou traitement à l eau) sur les rendements de conversion énergétique et la stabilité des dispositifs a été démontrée. Ainsi, des performances comparables ou supérieures à l état de l art ont été atteintes pour les systèmes à base de SnO2. Ces performances ont ensuite été interprétées en déterminant les processus électroniques et ioniques ayant lieu dans ces cellules par différentes méthodes physiques (mesures de tension de seuil et de décroissance de circuit-ouvert, spectroscopie d impédance). Enfin, des électrodes réalisées à partir de WO3 déposé sur substrats flexibles ont démontré des propriétés électrochromes très prometteuses ce qui ouvre de nouvelles perspectives dans le domaine de l affichage.In the context of the development of efficient, low-cost and environmentally friendly photovoltaic devices, the synthesis of metal-oxide semiconductors such as SnO2, Zn2SnO4 and WO3 with various textures and morphologies have been developed in order to achieve nanoporous photoanodes for dye-sensitized solar cells. According to studies carried out by different characterization methods (SEM, TEM, XRD and BET), the resulting materials show interesting features for the expected application. Dye solar cells were then fabricated from photoanodes processed with these oxides and several parameters influencing their performance were optimized to improve the overall conversion efficiency. In particular, the beneficial effect of different treatments of the photoanodes (ie aqueous TiCl4 or water treatment) on the power conversion efficiency and the stability of the devices has been evidenced. Thus, state-of-the art or, even, record efficiencies were reached in the case of SnO2-based systems. These performances were then rationalized by determining the electronic and ionic processes occurring in these devices by various physical methods (threshold voltage and open-circuit photovoltage decay measurements, electrochemical impedance spectroscopy). Finally, electrodes based on WO3 and deposited on flexible substrates have shown very promising electrochromic properties, which opens up new prospects in the field of smart displays.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF

Ingéniérie, synthèse et étude de chromophores organiques et organométalliques pour cellules solaires à colorant

Le principal objectif de ce travail de thèse était d imaginer, de synthétiser et de caractériser de nouveaux chromophores push-pull pour finalement évaluer leurs propriétés photovoltaïques en cellules solaires à colorant. Deux approches distinctes ont été développées : i) la première consiste en l élaboration de chromophores tout-organiques de type push-pull basés sur un motif électro-donneur carbazole à potentiel d oxydation élevé. Ces nouveaux colorants ont été conçus dans le but d être utilisés avec des électrolytes à potentiel standard supérieur à celui du couple rédox I-/I3- ; ii) la seconde approche est basée sur un nouveau concept de chromophores organométalliques de type ruthénium-acétylure. Ces chromophores ont été développés dans le but de combiner à la fois les propriétés avantageuses d une structure de type push-pull et les transferts de charges (MLCT) impliquant le motif [Ru(dppe)2], également connu pour constituer un excellent relai électronique.The aim of this PhD research work was to design, synthesize and characterize new push-pull chromophores and finally to determine their photovoltaic properties in dye-sensitized solar cells. Two different approaches were developed: i) the first one consists in the preparation of metal-free organic push-pull chromophores based on a carbazole electron-donor part presenting high oxidation potential. These new chromophores were designed in view of being used with electrolytes showing standard potential superior to that of I-/I3-; redox couple ii) the second approach is based on a new concept of ruthenium-diacetylide organometallic complex dyes. These chromophores were developed in order to combine the advantageous properties of a push-pull structure and the charge transfer processes (MLCT) due to the [Ru(dppe)2] metal fragment, also known as an excellent electron relay.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF

Telomere length tracking in children and their parents:Implications for adult onset diseases

Adults with comparatively short or long leukocyte telomere length (LTL) typically continue to display comparatively short or long LTL throughout life. This LTL tracking stems from the inability of person-to-person variation in age-dependent LTL shortening during adulthood to offset the wide interindividual LTL variation established prior to adult life. However, LTL tracking in children is unstudied. This study aimed to examine LTL shortening rates and tracking in children and their parents. Longitudinal study in children (n = 67) and their parents (n = 99), whose ages at baseline were 11.4 +/- 0.3 and 43.4 +/- 0.4 yr, respectively. LTL was measured by Southern blotting at baseline and similar to 14 yr thereafter. LTL displayed tracking in both children [intraclass correlation coefficient (ICC) = 0.905, P <0.001] and their parents (ICC = 0.856, P <0.001). The children's rate of LTL shortening was twice that of their parents (40.7 +/- 2.5 bp/yr; 20.3 +/- 2.1 bp/yr, respectively; P <0.0001). LTL tracking applies not only to adulthood but also to the second decade of life. Coupled with previous work showing that the interindividual variation in LTL across newborns is as wide as in their parents, these findings support the thesis that the LTL-adult disease connection is principally determined before the second decade of life, perhaps mainly at birth

A short leucocyte telomere length is associated with development of insulin resistance

International audienceAIMS/HYPOTHESIS:A number of studies have shown that leucocyte telomere length (LTL) is inversely associated with insulin resistance and type 2 diabetes mellitus. The aim of the present longitudinal cohort study, utilising a twin design, was to assess whether shorter LTL predicts insulin resistance or is a consequence thereof.METHODS:Participants were recruited between 1997 and 2000 through the population-based national Danish Twin Registry to participate in the GEMINAKAR study, a longitudinal evaluation of metabolic disorders and cardiovascular risk factors. Baseline and follow-up measurements of LTL and insulin resistance over an average of 12 years were performed in a subset of the Registry consisting of 338 (184 monozygotic and 154 dizygotic) same-sex twin pairs.RESULTS:Age at baseline examination was 37.4 ± 9.6 (mean ± SD) years. Baseline insulin resistance was not associated with age-dependent changes in LTL (attrition) over the follow-up period, whereas baseline LTL was associated with changes in insulin resistance during this period. The shorter the LTL at baseline, the more pronounced was the increase in insulin resistance over the follow-up period (p < 0.001); this effect was additive to that of BMI. The co-twin with the shorter baseline LTL displayed higher insulin resistance at follow-up than the co-twin with the longer LTL.CONCLUSIONS/INTERPRETATION:These findings suggest that individuals with short LTL are more likely to develop insulin resistance later in life. By contrast, presence of insulin resistance does not accelerate LTL attrition

Buildup from birth onward of short telomeres in human hematopoietic cells

Telomere length (TL) limits somatic cell replication. However, the shortest among the telomeres in each nucleus, not mean TL, is thought to induce replicative senescence. Researchers have relied on Southern blotting (SB), and techniques calibrated by SB, for precise measurements of TL in epidemiological studies. However, SB provides little information on the shortest telomeres among the 92 telomeres in the nucleus of human somatic cells. Therefore, little is known about the accumulation of short telomeres with age, or whether it limits the human lifespan. To fill this knowledge void, we used the Telomere-Shortest-Length-Assay (TeSLA), a method that tallies and measures single telomeres of all chromosomes. We charted the age-dependent buildup of short telomeres (&lt;3 kb) in human hematopoietic cells from 334 individuals (birth-89 years) from the general population, and 18 patients with dyskeratosis congenita-telomere biology disorders (DC/TBDs), whose hematopoietic cells have presumably reached or are close to their replicative limit. For comparison, we also measured TL with SB. We found that in hematopoietic cells, the buildup of short telomeres occurs in parallel with the shortening with age of mean TL. However, the proportion of short telomeres was lower in octogenarians from the general population than in patients with DC/TBDs. At any age, mean TL was longer and the proportion of short telomeres lower in females than in males. We conclude that though converging to the TL-mediated replicative limit, hematopoietic cell telomeres are unlikely to reach this limit during the lifespan of most contemporary humans.</p

Simulations of the inelastic response of silicon to shock compression

Recent experiments employing nanosecond white-light X-ray diffraction have demonstrated a complex response of pure, single crystal silicon to shock compression on ultra-fast timescales. We present here details of a Lagrangian code which tracks both longitudinal and transverse strains, and successfully reproduces the experimental response by incorporating a model of the shock-induced, yet kinetically inhibited, phase transition. This model is also shown to reproduce results of classical molecular dynamics simulations of shock compressed silicon

Shedding light on the elusive role of endothelial cells in cytomegalovirus dissemination.

Cytomegalovirus (CMV) is frequently transmitted by solid organ transplantation and is associated with graft failure. By forming the boundary between circulation and organ parenchyma, endothelial cells (EC) are suited for bidirectional virus spread from and to the transplant. We applied Cre/loxP-mediated green-fluorescence-tagging of EC-derived murine CMV (MCMV) to quantify the role of infected EC in transplantation-associated CMV dissemination in the mouse model. Both EC- and non-EC-derived virus originating from infected Tie2-cre(+) heart and kidney transplants were readily transmitted to MCMV-naïve recipients by primary viremia. In contrast, when a Tie2-cre(+) transplant was infected by primary viremia in an infected recipient, the recombined EC-derived virus poorly spread to recipient tissues. Similarly, in reverse direction, EC-derived virus from infected Tie2-cre(+) recipient tissues poorly spread to the transplant. These data contradict any privileged role of EC in CMV dissemination and challenge an indiscriminate applicability of the primary and secondary viremia concept of virus dissemination