Electrophilicity of neutral square-planar organosilver(III) compounds

Neutral Ag(III) complexes stabilised with just monodentate ligands are here unambiguously established. In a series of square-planar (CF3)3Ag(L) compounds with hard and soft Group 15 donor ligands, L, the metal center has been found to exhibit substantial acidity favouring apical coordination of an additional ligand under no coordination constraints

Black-boxing Sustainable Development: Environmental Impact Assessment on the River Uruguay

International audienceThis chapter offers an original account of Environmental Impact Assessment (EIA) as a technology that scripts collective action through black-boxing the politics of governance. After tracing the global trajectory of the instrument, the chapter looks at EIA struggles in the case of pulp mills on the River Uruguay. As actors seeking to halt projects because of their potential harmful impact follow the choreography of EIA, the authoritative governance script is reinforced rather than undermined. There is a tragic aspect to this, in that those wishing to block a project are actually making it stronger. This points to a subtle de-politicization resulting from the evolution of instruments in use, and a need for their re-politicization

Femmes et hommes face aux grossesses non prévues au Maroc et au Sénégal

Cet article étudie la manière dont les femmes ou les couples gèrent les grossesses non prévues dans les capitales du Maroc et du Sénégal (Rabat et Dakar), deux pays soumis à des règles strictes en matière de sexualité des célibataires. Nous analysons les logiques sociales et individuelles qui prévalent à l'annonce d'une grossesse inattendue et la manière dont se prennent les décisions qui vont aboutir à la poursuite de cette grossesse ou à son interruption. Nous nous basons sur des données qualitatives tirées d'un programme financé par l'Union Européenne entre 2005 et 2009, sur l'usage de la contraception d'urgence dans les villes africaines. Nos résultats montrent qu'en dépit de programmes de planification familiale plus performants dans leur pays, les femmes de Rabat vivent leur entrée en sexualité dans des conditions difficiles. Si à Dakar la chasteté avant le mariage est prônée, le non-respect de cette règle entraîne des sanctions beaucoup moins sévères qu'au Maroc. Le choix de l'avortement en cas de grossesse non prévue évolue avec le cycle de vie des individus et selon le stade de la relation. Une pratique envisageable à un moment donné, ne l'est plus forcément à d'autres moments de la relation. Enfin, dans les deux villes, nos données révèlent une forte implication des familles dans la gestion de la formation des couples et de leur fécondité. Cette tendance apparaît cependant plus exacerbée au Maroc où les familles se mobilisent parfois âprement pour obliger ou interdire un avortement

Implications of the Daya Bay observation of \theta_{13} on the leptonic flavor mixing structure and CP violation

The Daya Bay Collaboration has recently reported its first \bar{\nu}_e \to \bar{\nu}_e oscillation result which points to \theta_{13} \simeq 8.8^\circ \pm 0.8^\circ (best-fit \pm 1\sigma range) or \theta_{13} \neq 0^\circ at the 5.2\sigma level. The fact that this smallest neutrino mixing angle is not strongly suppressed motivates us to look into the underlying structure of lepton flavor mixing and CP violation. Two phenomenological strategies are outlined: (1) the lepton flavor mixing matrix U consists of a constant leading term U_0 and a small perturbation term \Delta U; and (2) the mixing angles of U are associated with the lepton mass ratios. Some typical patterns of U_0 are reexamined by constraining their respective perturbations with current experimental data. We illustrate a few possible ways to minimally correct U_0 in order to fit the observed values of three mixing angles. We point out that the structure of U may exhibit an approximate \mu-\tau permutation symmetry in modulus, and reiterate the geometrical description of CP violation in terms of the leptonic unitarity triangles. The salient features of nine distinct parametrizations of U are summarized, and its Wolfenstein-like expansion is presented by taking U_0 to be the democratic mixing pattern.Comment: RevTeX 25 pages, 1 figure, minor changes, version for publicatio

The tropical managed forests observatory: a research network addressing the future of tropical logged forests.

While attention on logging in the tropics has been increasing, studies on the long-term effects of silviculture on forest dynamics and ecology remain scare and spatially limited. Indeed, most of our knowledge on tropical forests arises from studies carried out in undisturbed tropical forests. This biasis problematic given that logged and disturbed tropical forests are now covering a larger area thantheso-alled primary forests. A new network of permanent sample plots in logged forests, the Tropical managed Forests Observatory (TmFO), aims to ?ll this gap by providing unprecedented opportunities to examine long-term data on the resilience of logged tropical forests at regional and global scales. TmFO currently includes 24 experimental sites distributed across three tropical regions, with a total of 490 permanent plots and 921 ha of forest inventories

An analysis of factors that influence personal exposure to toluene and xylene in residents of Athens, Greece

BACKGROUND: Personal exposure to pollutants is influenced by various outdoor and indoor sources. The aim of this study was to evaluate the exposure of Athens citizens to toluene and xylene, excluding exposure from active smoking. METHODS: Passive air samplers were used to monitor volunteers, their homes and various urban sites for one year, resulting in 2400 measurements of toluene and xylene levels. Since both indoor and outdoor pollution contribute significantly to human exposure, volunteers were chosen from occupational groups who spend a lot of time in the streets (traffic policemen, bus drivers and postmen), and from groups who spend more time indoors (teachers and students). Data on individual and house characteristics were obtained using a questionnaire completed at the beginning of the study; a time-location-activity diary was also completed daily by the volunteers in each of the six monitoring campaigns. RESULTS: Average personal toluene exposure varied over the six monitoring campaigns from 53 to 80 μg/m(3). Urban and indoor concentrations ranged from 47 – 84 μg/m(3 )and 30 – 51 μg/m(3), respectively. Average personal xylene exposure varied between 56 and 85 μg/m(3 )while urban and indoor concentrations ranged from 53 – 88 μg/m(3 )and 27 – 48 μg/m(3), respectively. Urban pollution, indoor residential concentrations and personal exposures exhibited the same pattern of variation during the measurement periods. This variation among monitoring campaigns might largely be explained by differences in climate parameters, namely wind speed, humidity and amount of sunlight. CONCLUSION: In Athens, Greece, the time spent outdoors in the city center during work or leisure makes a major contribution to exposure to toluene and xylene among non-smoking citizens. Indoor pollution and means of transportation contribute significantly to individual exposure levels. Other indoor residential characteristics such as recent painting and mode of heating used might also contribute significantly to individual levels. Groups who may be subject to higher exposures (e.g. those who spent more time outdoors because of occupational activities) need to be surveyed and protected against possible adverse health effects

Edwardsiella Comparative Phylogenomics Reveal the New Intra/Inter-Species Taxonomic Relationships, Virulence Evolution and Niche Adaptation Mechanisms

Edwardsiella bacteria are leading fish pathogens causing huge losses to aquaculture industries worldwide. E. tarda is a broad-host range pathogen that infects more than 20 species of fish and other animals including humans while E. ictaluri is host-adapted to channel catfish causing enteric septicemia of catfish (ESC). Thus, these two species consist of a useful comparative system for studying the intricacies of pathogen evolution. Here we present for the first time the phylogenomic comparisons of 8 genomes of E. tarda and E. ictaluri isolates. Genome-based phylogenetic analysis revealed that E. tarda could be separate into two kinds of genotypes (genotype I, EdwGI and genotype II, EdwGII) based on the sequence similarity. E. tarda strains of EdwGI were clustered together with the E. ictaluri lineage and showed low sequence conservation to E. tarda strains of EdwGII. Multilocus sequence analysis (MLSA) of 48 distinct Edwardsiella strains also supports the new taxonomic relationship of the lineages. We identified the type III and VI secretion systems (T3SS and T6SS) as well as iron scavenging related genes that fulfilled the criteria of a key evolutionary factor likely facilitating the virulence evolution and adaptation to a broad range of hosts in EdwGI E. tarda. The surface structure-related genes may underlie the adaptive evolution of E. ictaluri in the host specification processes. Virulence and competition assays of the null mutants of the representative genes experimentally confirmed their contributive roles in the evolution/niche adaptive processes. We also reconstructed the hypothetical evolutionary pathway to highlight the virulence evolution and niche adaptation mechanisms of Edwardsiella. This study may facilitate the development of diagnostics, vaccines, and therapeutics for this under-studied pathogen

Functional Interaction between CFTR and the Sodium-Phosphate Co-Transport Type 2a in Xenopus laevis Oocytes

A growing number of proteins, including ion transporters, have been shown to interact with Cystic Fibrosis Transmembrane conductance Regulator (CFTR). CFTR is an epithelial chloride channel that is involved in Cystic Fibrosis (CF) when mutated; thus a better knowledge of its functional interactome may help to understand the pathophysiology of this complex disease. In the present study, we investigated if CFTR and the sodium-phosphate co-transporter type 2a (NPT2a) functionally interact after heterologous expression of both proteins in Xenopus laevis oocytes.NPT2a was expressed alone or in combination with CFTR in X. laevis oocytes. Using the two-electrode voltage-clamp technique, the inorganic phosphate-induced current (IPi) was measured and taken as an index of NPT2a activity. The maximal IPi for NPT2a substrates was reduced when CFTR was co-expressed with NPT2a, suggesting a decrease in its expression at the oolemna. This was consistent with Western blot analysis showing reduced NPT2a plasma membrane expression in oocytes co-expressing both proteins, whereas NPT2a protein level in total cell lysate was the same in NPT2a- and NPT2a+CFTR-oocytes. In NPT2a+CFTR- but not in NPT2a-oocytes, IPi and NPT2a surface expression were increased upon PKA stimulation, whereas stimulation of Exchange Protein directly Activated by cAMP (EPAC) had no effect. When NPT2a-oocytes were injected with NEG2, a short amino-acid sequence from the CFTR regulatory domain that regulates PKA-dependent CFTR trafficking to the plasma membrane, IPi values and NPT2a membrane expression were diminished, and could be enhanced by PKA stimulation, thereby mimicking the effects of CFTR co-expression.We conclude that when both CFTR and NPT2a are expressed in X. laevis oocytes, CFTR confers to NPT2a a cAMPi-dependent trafficking to the membrane. This functional interaction raises the hypothesis that CFTR may play a role in phosphate homeostasis

Clustering gene expression data with a penalized graph-based metric

<p>Abstract</p> <p>Background</p> <p>The search for cluster structure in microarray datasets is a base problem for the so-called "-omic sciences". A difficult problem in clustering is how to handle data with a manifold structure, i.e. data that is not shaped in the form of compact clouds of points, forming arbitrary shapes or paths embedded in a high-dimensional space, as could be the case of some gene expression datasets.</p> <p>Results</p> <p>In this work we introduce the Penalized k-Nearest-Neighbor-Graph (PKNNG) based metric, a new tool for evaluating distances in such cases. The new metric can be used in combination with most clustering algorithms. The PKNNG metric is based on a two-step procedure: first it constructs the k-Nearest-Neighbor-Graph of the dataset of interest using a low k-value and then it adds edges with a highly penalized weight for connecting the subgraphs produced by the first step. We discuss several possible schemes for connecting the different sub-graphs as well as penalization functions. We show clustering results on several public gene expression datasets and simulated artificial problems to evaluate the behavior of the new metric.</p> <p>Conclusions</p> <p>In all cases the PKNNG metric shows promising clustering results. The use of the PKNNG metric can improve the performance of commonly used pairwise-distance based clustering methods, to the level of more advanced algorithms. A great advantage of the new procedure is that researchers do not need to learn a new method, they can simply compute distances with the PKNNG metric and then, for example, use hierarchical clustering to produce an accurate and highly interpretable dendrogram of their high-dimensional data.</p