Magnetic structure and dynamics of a strongly one-dimensional cobaltII^{II} metal-organic framework

We investigate the magnetism of the Co$^{II}_4$(OH)$_2$(C$_1$$_0$H$_1$$_6$O$_4$)$_3$ metal-organic framework which displays complex inorganic chains separated from each other by distances of 1 to 2 nm, and which orders at ~5.4 K. The zero-field magnetic structure is determined using neutron powder diffraction: it is mainly antiferromagnetic but posseses a ferromagnetic component along the $\textbf{c}$-axis. This magnetic structure persists in presence of a magnetic field. Ac susceptibility measurements confirm the existence of a single thermally activated regime over 7 decades in frequency ($E/k_B\approx64 K$) whereas time-dependent relaxation of the magnetization after saturation in an external field leads to a two times smaller energy barrier. These experiments probe the slow dynamics of domain walls within the chains: we propose that the ac measurements are sensitive to the motion of existing domain walls within the chains, while the magnetization measurements are governed by the creation of domain walls.Comment: 12 pages, 14 figure

L'hostilité aux OGM survit-elle à des produits attractifs ?

Nous testons ici les dispositions à payer des consommateurs pour des aliments transgéniques de seconde génération, c'est-à-dire ayant des caractéristiques innovantes attractives pour le consommateur par rapport au produit conventionnel. Nous testons également les dispositions à payer de tels produits lorsqu'ils sont obtenus avec des technologies alternatives aux biotechnologies transgéniques. Les résultats indiquent que la disposition à payer positive pour une caractéristique désirable obtenue grâce à un organisme génétiquement modifié compense la perte de disposition à payer qu'entraine, pour le consommateur, l'usage d'une telle technologie. Pour un même produit amélioré pour le consommateur, le recours à la technologie transgénique conduit à une disposition à payer toujours inférieure à celles proposée pour les autres technologies. L'écart est néanmoins d'une ampleur réduite, même si les OGM continuent à subir le coût d'une image négative.aliment génétiquement modifié;, évaluation de préférences individuelles; économie expérimentale

Influence of Two Root Canal Obturation Techniques with Resin Based Sealer to Enterococcus faecalis Penetration

  Introduction: Root canal treatment is done to maintain the teeth to last as long as possible in the oral cavity. This can be done with three main stages, such as biomechanical preparation, sterilization and root canal filling. The hermetic seal of root canal filling has an important role in the success of root canal treatment.   Objective: The aim of this in-vitro study is to compare the microbial leakage of root canals filled with RealSeal sealer/Resilon Points and AH Plus sealer/conventional gutta-percha points using single cone obturation technique and warm vertical compaction technique.   Methods: Thirty-two extracted human mandibular premolars with single canals were decoronated to a standardized root length of 15 mm and prepared using crown-down technique to a master apical file size 30/.09. Teeth were divided into four experimental groups (n = 7 each group) and controls (n = 1 each group). Teeth in the first group were obturated using single master gutta percha cone and AH Plus sealer and second group were obturated with single Resilon gutta percha cone using RealSeal sealer. Third experimental group was filled with warm vertical condensed gutta-percha using AH Plus sealer and fourth group was filled with warm vertical condensed Resilon gutta-percha using RealSeal sealer. The coronal chamber of each sample were inoculated with Enterococcus faecalis.   Results: There were no significant differences between the four experimental groups (P = 0.182). The differences occurred only in the survival time from each group. Group 4 (Warm Vertical Condensation - RealSeal) has the lowest leakage rate among other groups and the fastest leakage occurred in group 1 (Single Cone - AH Plus).   Conclusion: The single-cone techniques does not insure durable apical seal against bacterial leakage. Warm vertical compaction technique using Resilon gutta-percha and RealSeal sealer appears to be more effective in minimizing bacterial leakage than gutta-percha and AH Plus sealer

Efficient RNA Isoform Identification and Quantification from RNA-Seq Data with Network Flows

International audienceSeveral state-of-the-art methods for isoform identification and quantification are based on l1- regularized regression, such as the Lasso. However, explicitly listing the--possibly exponentially-- large set of candidate transcripts is intractable for genes with many exons. For this reason, existing approaches using the l1-penalty are either restricted to genes with few exons, or only run the regression algorithm on a small set of pre-selected isoforms. We introduce a new technique called FlipFlop which can efficiently tackle the sparse estimation problem on the full set of candidate isoforms by using network flow optimization. Our technique removes the need of a preselection step, leading to better isoform identification while keeping a low computational cost. Experiments with synthetic and real RNA-Seq data confirm that our approach is more accurate than alternative methods and one of the fastest available. Source code is freely available as an R package from the Bioconductor web site (http://www.bioconductor.org/) and more information is available at http://cbio.ensmp.fr/flipflop

A convex formulation for joint RNA isoform detection and quantification from multiple RNA-seq samples

International audienceDetecting and quantifying isoforms from RNA-seq data is an important but challenging task. The problem is often ill-posed, particularly at low coverage. One promising direction is to exploit several samples simultaneously.We propose a new method for solving the isoform deconvolution problem jointly across several samples. We formulate a convex optimization problem that allows to share information between samples and that we solve efficiently. We demonstrate the benefits of combining several samples on simulated and real data, and show that our approach outperforms pooling strategies and methods based on integer programming.Our convex formulation to jointly detect and quantify isoforms from RNA-seq data of multiple related samples is a computationally efficient approach to leverage the hypotheses that some isoforms are likely to be present in several samples. The software and source code are available at http://cbio.ensmp.fr/flipflop

Chloride Balance in Preterm Infants during the First Week of Life

Objective. To describe the chloride balance in infants born 25–32-week gestation, analyze the association of chloride changes with hydroelectrolytic status and their relationship with perinatal conditions, morbidities, and neurological outcome. Methods. For 7 days after birth, sodium and chloride balance, plasma potassium, phosphate, and total carbon dioxide (tCO2) were prospectively determined and strong ion difference (SID) calculated. Three multivariate regression analyses were performed to identify factors associated with high plasma chloride concentration, low SID, and low tCO2. Results. 107 infants were studied. Plasma chloride concentration was significantly positively associated with plasma sodium concentration. Higher plasma chloride and lower SID were significantly associated with lower plasma tCO2. Chloride intake was the main independent factor associated with high plasma chloride, low SID, and low plasma tCO2, with lesser contribution of sodium intake and low gestational age (GA). Also, patent ductus arteriosus and birth weight loss were independent factors affecting plasma chloride and SID. Neither high chloride levels nor low SID were associated to impaired neurological outcome. Conclusions. In preterm infants, chloride balance is influenced by GA and by interrelationship between sodium and chloride intake. High chloride levels are associated with metabolic acidosis but not related to increased risk of impaired neurological outcome

Dynamiques rurales et développement régional dans la province Nord de Nouvelle-Calédonie

Dans le contexte de transition institutionnelle que connaissent le Territoire et la Province Nord, le Programme Agricultures familiales du CIRAD-Tera a réalisé une étude de diagnostic sur les dynamiques rurales et le développement régional dans la Province Nord à la demande de la Direction du développement rural et de la pêche (DDRP). Ce diagnostic, conduit en étroite collaboration avec les agents et responsables de la DDRP, repose sur une approche globale des activités agricoles et non agricoles des ruraux combinant : - une analyse sectorielle mettant en évidence les enseignements et les limites des approches "filières" ;- une analyse des stratégies individuelles, des activités et des revenus des ruraux - une approche des dynamiques collectives : organisations professionnelles, dynamiques associatives et territoriales ;- une approche de la diversité des situations et des dynamiques territoriales en Province Nord.Le diagnostic débouche sur des propositions susceptibles de renforcer la construction d'un projet de développement régional de la Province Nord en cohérence avec l'élaboration d'un projet territorial. Se fondant sur une appréciation des atouts de la Province, les propositions opérationnelles sont structurées autour de trois axes : - le renforcement des positions provinciales sur les marchés territoriaux- l'élargissement du marché provincial ;- la promotion des approches de développement local. Le développement de ces trois axes suppose que des appuis adaptés soient apportés pour renforcer les capacités d'analyse et de négociation des acteurs locaux. Au plan opérationnel, la mise en oeuvre d'un conseil de gestion global pour l'appui aux exploitations agricoles et d'un dispositif d'accompagnement des dynamiques de développement local apparaissent comme des priorités

Methylmercury Contamination of Laboratory Animal Diets

In the midst of research focusing on the neurodevelopmental effects of mercury vapor in rats, we detected significant levels of mercury (30–60 ng/g) in the blood of nonexposed control subjects. We determined that the dominant form of the mercury was organic and that the standard laboratory chow we used in our vivarium was the source of the contamination. The dietary levels were deemed of potential biologic significance, even though they might have fallen below the limits of measurement specified by the supplier. All investigators employing animals in research must assess such potential contamination because dietary agents may alter a) conclusions based on intentionally administered doses, b) outcomes by interacting with other agents that are the primary focus of the research, and c) outcomes of research unrelated to the toxic effects of experimentally administered agents

Problemas generales de la arqueología del Chaco occidental

Los propósitos de este trabajo son (a) remarcar que el área arqueológica chaquense constituye tan sólo una parte de la totalidad del Gran Chaco americano; (b) destacar que,si bien etnográficamente, los grupos conocidos como "chaquenses típicos"; presentan rasgos culturales que los caracterizan y separan de las demás etnias de los habitats vecinos, los restos arqueológicos carecen, en general, de una estructuración suficiente como para hablar de una "cultura arqueológica chaquense" (c) postular que el área cultural chaquense pudo caracterizarse por una intensa dinámica de desplazamiento en época prehispánica, al igual que la registrada por la etnografía; (d) proponer que el occidente del Chaco es un territorio óptimo para el estudio de un aspecto importante de la dinámica aborigen prehispánica; (e) plantear la posibilidad de que el occidente chaquense, pudo presentar antaño características ambientales más beneficiosas que las actuales para ciertos desarrollos culturales aborígenes