End-effects of strongly charged polyelectrolytes - a molecular dynamics study

We investigate end-effects in the ion distribution around strongly charged, flexible polyelectrolytes with a quenched charge distribution by molecular dynamics simulations of dilute polyelectrolyte solutions. We take the counterions explicitly into account and calculate the full Coulomb interaction via an Ewald summation method. We find that the free counterions of the solution are distributed in such a way that a fraction of the chain charges is effectively neutralized. This in turn leads to an effective charge distribution which is similar to those found for weakly charged titrating polyelectrolytes that have an annealed charge distribution. The delicate interplay between the electrostatic interactions, the chain conformation and the counterion distribution is studied in detail as a function of different system parameters such as the chain length Nm, the charge fraction f, the charged particle density rho, the ionic strength and the solvent quality. Comparisons are made with predictions from a scaling theory.Comment: 20 pages, 10 figures. J. Chem. Phys, to appear June 200

Rodrigues, de l’administration par l’Isle de France à l’autonomie dans la République de Maurice

Rodrigues, la « Mascareigne sans sucre », la discrète « Cendrillon des Mascareignes », découverte par les Portugais, peuplée par des Créoles, longtemps administrée par l’Isle de France, devenue République de Maurice, est aujourd’hui autonome.Rodrigues, “Mascareigne without sugarˮ, the discreet “Cinderella of the Mascarene Islandsˮ, discovered by the Portuguese, populated by Creoles, for a long time administred by Isle of France, now Republic of Mauritius, is today autonomous

Traces de l’engagisme de 1933 à La Réunion et à Rodrigues

Suite à des négociations menées entre les colons réunionnais et l’autorité britannique, plusieurs centaines de Rodriguais ont été recrutés, en 1933, pour travailler dans les plantations de canne à sucre et les établissements sucriers, dans la colonie de La Réunion. La majeure partie de ces engagés rodriguais, une fois confrontés aux réalités de la vie à La Réunion, déchantèrent. Du début de l’année 1934 à la fin de l’année 1935, ils ont réclamé leur rapatriement à Rodrigues. Peu nombreux sont ceux qui sont restés à La Réunion. Nous avons recueilli, sur le « terrain » réunionnais et rodriguais, des petits bouts d’histoires de vie, quelques souvenirs familiaux, de brèves anecdotes, des bribes de tradition orale auprès de survivants ou descendants de ces engagés. Les auteurs proposent ici une lecture historique de l’échec de cette immigration rodriguaise et une ethnographie de ses traces sur le « terrain » réunionnais et rodriguais.Following the negotiations led between the Reunion colonists and the British authorities, several hundreds of Rodriguese were recruited in 1933 to work in sugar plantations and sugar-producing factories in Reunion colony. The major part of these indentured people, once confronted with the realities of life in Reunion became disappointed. From the beginning of 1934 till the end of 1935, they claimed to be sent back to Rodrigues. Not many of them stayed in Reunion Island. The authors of this article collected, on the Réunion and Rodrigues terrains, fragments of life and family recollections, brief anecdotes, sections of oral tradition from survivors or descendants of these indentured labourers. They propose here a historical reading of the failure of this Rodriguese immigration and an ethnography of its track on the Reunionese and Rodriguese « fieldworks »

Utilisation des capteurs ultrasonores pour la distinction entre un plan et un coin à l'aide des méthodes statistiques

La technologie ultrasonore permet de développer un système de perception à faible coût pour la robotique de service. L'extraction des informations pertinentes sur l'environnement exige le traitement du signal ultrasonore. Les méthodes statistiques sont capables de discriminer des objets d'un environnement structuré, (plan, coin, etc...). La difficulté principale de la classification est le choix des paramètres discriminants du signal réfléchi par les cibles rencontrées. La dimension de l'espace de représentation des objets est réduite à l'aide de la méthode suboptimal. Les paramètres extraits définissent le vecteur d'entrée du classifieur quadratique. Les résultats obtenus montrent le taux de bonne classification par rapport à la dimension du vecteur d'entrée

Analysis of sequence variability in the CART gene in relation to obesity in a Caucasian population

BACKGROUND: Cocaine and amphetamine regulated transcript (CART) is an anorectic neuropeptide located principally in hypothalamus. CART has been shown to be involved in control of feeding behavior, but a direct relationship with obesity has not been established. The aim of this study was to evaluate the effect of polymorphisms within the CART gene with regards to a possible association with obesity in a Caucasian population. RESULTS: Screening of the entire gene as well as a 3.7 kb region of 5' upstream sequence revealed 31 SNPs and 3 rare variants ; 14 of which were subsequently genotyped in 292 French morbidly obese subjects and 368 controls. Haplotype analysis suggested an association with obesity which was found to be mainly due to SNP-3608T>C (rs7379701) (p = 0.009). Genotyping additional cases and controls also of European Caucasian origin supported further this possible association between the CART SNP -3608T>C T allele and obesity (global p-value = 0.0005). Functional studies also suggested that the SNP -3608T>C could modulate nuclear protein binding. CONCLUSION: CART SNP -3608T>C may possibly contribute to the genetic risk for obesity in the Caucasian population. However confirmation of the importance of the role of the CART gene in energy homeostasis and obesity will require investigation and replication in further populations

Missense variants in ANKRD11 cause KBG syndrome by impairment of stability or transcriptional activity of the encoded protein

Purpose Although haploinsufficiency of ANKRD11 is among the most common genetic causes of neurodevelopmental disorders, the role of rare ANKRD11 missense variation remains unclear. We characterized clinical, molecular, and functional spectra of ANKRD11 missense variants. Methods We collected clinical information of individuals with ANKRD11 missense variants and evaluated phenotypic fit to KBG syndrome. We assessed pathogenicity of variants through in silico analyses and cell-based experiments. Results We identified 20 unique, mostly de novo, ANKRD11 missense variants in 29 individuals, presenting with syndromic neurodevelopmental disorders similar to KBG syndrome caused by ANKRD11 protein truncating variants or 16q24.3 microdeletions. Missense variants significantly clustered in repression domain 2 at the ANKRD11 C-terminus. Of the 10 functionally studied missense variants, 6 reduced ANKRD11 stability. One variant caused decreased proteasome degradation and loss of ANKRD11 transcriptional activity. Conclusion Our study indicates that pathogenic heterozygous ANKRD11 missense variants cause the clinically recognizable KBG syndrome. Disrupted transrepression capacity and reduced protein stability each independently lead to ANKRD11 loss-of-function, consistent with haploinsufficiency. This highlights the diagnostic relevance of ANKRD11 missense variants, but also poses diagnostic challenges because the KBG-associated phenotype may be mild and inherited pathogenic ANKRD11 (missense) variants are increasingly observed, warranting stringent variant classification and careful phenotyping

La montagne d'Ambre (nord de Madagascar)

Barat Christian. La montagne d'Ambre (nord de Madagascar). In: Revue de géographie alpine, tome 46, n°4, 1958. pp. 629-681

Les données de la pluviologie dans la zone intertropicale

Barat Christian. Les données de la pluviologie dans la zone intertropicale. In: Bulletin de l'Association de géographes français, N°261-262, 33e année, Novembre-décembre 1956. pp. 175-184

Nargoulan : culture et rites malbar à la Réunion : approche anthropologique / Christian Barat,...

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Robust Tracking of Longitudinal Objects Lying on the Sea Floor with an AUV equipped of a Scanning Sonar

The paper considers the problem of using an autonomous underwater platform equipped with a scanning profiler sonar to track elongated objects lying on the sea floor, e.g., pipelines. The algorithm presented assumes the existence of features that enable the discrimination between sonar profiles received from the tracked object and those received from the background sea bottom. The algorithm does not require explicit classification of the profiles received (as coming from the tracked object or from the sea bottom), and does not rely on reconstruction of the geometry of the surface of the tracked object (allowing tracking of proud or partially buried objects). Simulation results illustrate the performance of the algorithm presented, as well as the effect of departures from the assumed geometric and reflectivity characteristics of the actual tracking configuration. Results of processing of real sonar profiles obtained at sea with a man-made object of cylindrical geometry are presented, demonstrating the appropriateness of the approach propose