Nitrated and oxygenated derivatives of polycyclic aromatic hydrocarbons in the ambient air of two French alpine valleys: Part 1: Concentrations, sources and gas/particle partitioning

International audienceAmbient measurements (gas+particle phases) of 16 polycyclic aromatic hydrocarbons, 17 nitrated PAHs (NPAHs) and eight oxygenated PAHs (OPAHs) were carried out during the winter 2002-2003 and the summer 2003 in two French alpine valleys on various types of sites (traffic, sub-urban, altitude and rural). Atmospheric concentrations of these classes of compounds are of interest because they include potential mutagens and carcinogens. During both summer and winter campaigns, OPAH concentration levels were of the same order of magnitude as PAH ones while NPAH concentrations were one to two orders of magnitude lower. Total particulate PAH, OPAH and NPAH concentrations were higher in the Chamonix valley than in the Maurienne valley. A heavier pollutant accumulation process in the Chamonix valley and geomorphology promoting their dispersion seem to explain such differences. Despite reaching lower atmospheric concentrations, NPAHs seemed to account up to 20% of carcinogenic potency of particulates collected at the sites away from pollution sources. The formation of secondary compounds such as NPAHs increases significantly the carcinogenic risk at the sites away from pollution sources. Study with 2-nitrofluoranthene/1-nitropyrene ratio showed that NPAH gas phase formation was hindered in winter, and when relative contribution from primary sources was higher. Nevertheless, in winter under specific conditions, evidence of secondary NPAH formations was observed at sub-urban and traffic sites (snowfalls) and rural site (accumulation of pollutants and snowfalls). For all sampling sites, the daytime OH initiated reaction seemed to be the dominant gas phase formation pathway over the NO3 initiated reaction. The fraction of PAHs, OPAHs and NPAHs associated with the particle phase was strongly depending on their vapour pressure and the ambient conditions

Qualité biologique de l’eau de mer évaluée in situ par le test embryo-larvaire de Crassostrea gigas et Mytilus galloprovincialis = In situ monitoring of sea water quality with the embryo-larval bioassay of Crassostrea gigas and Mytilus galloprovincialis

Embryos and larvae of bivalves are frequently used in marine ecotoxicology for the purpose of assessing seawater quality, because they are very sensitive to pollutants and provide rapid responses. Laboratory studies, however, cannot accurately simulate natural conditions. We conducted bivalve embryo-larval studies in situ at the marina of Arcachon (southwest French Atlantic coast), in order to assess ‘biological quality’ of the water. One experiment conducted in winter 1999 (temperatures of 10 °C) with embryos of the Mediterranean mussel, Mytilus galloprovincialis, has shown that such tests are practicable in winter at low temperatures. This study did not show any deterioration in ‘biological quality’ of the water. Four series of experiments were subsequently performed during summer 2000 (ambient water temperatures of 19 to 22.4 °C) with embryos of the Japanese oyster, Crassostrea gigas. The results show that the ‘sea water biological quality’ deteriorates from the port entrance towards its inner part. To our knowledge, this is the first investigation of the marine environment in which bivalve embryos have been used in situ. They are very suitable for this type of study, because bivalve embryos and larvae are more sensitive to pollutants than the adults, and also because they belong to euryhaline species and the embryos tolerate summer temperatures (both species) as well as winter temperatures (mussels), allowing biomonitoring to be conducted all over the year

Caracterização in silico de genes de expansina presentes em cafeeiro (Coffea arabica L.).

As expansinas (EXPs) são proteínas que promovem o relaxamento e extensão da parede celular em plantas, sendo codificadas por uma multifamília gênica e classificadas em: ?-expansinas, ?-expansinas, expansin-like A (EXLA) e expansin-like B (EXLB). Estas proteínas atuam no alongamento celular, maciez dos frutos, abscisão, germinação e polinização. As ?-expansinas representam a maior família e relacionam-se diretamente com o controle da extensão da parede celular em processos de desenvolvimento. Visto que a maturação uniforme dos frutos de café contribui para a qualidade da bebida, este trabalho teve por objetivo identificar e caracterizar in silico genes de expansinas envolvidas neste processo. Através da mineração dos dados do Genoma Café foram encontrados 28 contigs referentes às EXPs, sendo dois contigs de EXLB, um de EXLA e os demais pertencentes à família das ?-expansinas. Dentro desta ultima família foram identificados quatro contigs relacionados com o desenvolvimento dos frutos do cafeeiro. Comparação dos contigs obtidos nos bancos do Projeto Genoma Café e de contigs no banco de dados HarvEST Coffea permitiu a caracterização in silico da expressão dos contigs nos diferentes estádios de maturação dos frutos

Theory of transient chimeras in finite Sakaguchi-Kuramoto networks

Chimera states are a phenomenon in which order and disorder can co-exist within a network that is fully homogeneous. Precisely how transient chimeras emerge in finite networks of Kuramoto oscillators with phase-lag remains unclear. Utilizing an operator-based framework to study nonlinear oscillator networks at finite scale, we reveal the spatiotemporal impact of the adjacency matrix eigenvectors on the Sakaguchi-Kuramoto dynamics. We identify a specific condition for the emergence of transient chimeras in these finite networks: the eigenvectors of the network adjacency matrix create a combination of a zero phase-offset mode and low spatial frequency waves traveling in opposite directions. This combination of eigenvectors leads directly to the coherent and incoherent clusters in the chimera. This approach provides two specific analytical predictions: (1) a precise formula predicting the combination of connectivity and phase-lag that creates transient chimeras, (2) a mathematical procedure for rewiring arbitrary networks to produce transient chimeras

Composed solutions of synchronized patterns in multiplex networks of Kuramoto oscillators

Networks with different levels of interactions, including multilayer and multiplex networks, can display a rich diversity of dynamical behaviors and can be used to model and study a wide range of systems. Despite numerous efforts to investigate these networks, obtaining mathematical descriptions for the dynamics of multilayer and multiplex systems is still an open problem. Here, we combine ideas and concepts from linear algebra and graph theory with nonlinear dynamics to offer a novel approach to study multiplex networks of Kuramoto oscillators. Our approach allows us to study the dynamics of a large, multiplex network by decomposing it into two smaller systems: one representing the connection scheme within layers (intra-layer), and the other representing the connections between layers (inter-layer). Particularly, we use this approach to compose solutions for multiplex networks of Kuramoto oscillators. These solutions are given by a combination of solutions for the smaller systems given by the intra and inter-layer system and, in addition, our approach allows us to study the linear stability of these solutions