Hydrocarbon influence on denitrification in bioturbated Mediterranean coastal sediments

An in situ experiment has been carried out inbioturbated Mediterranean coastal marine sediments (Gulfof Fos) in order to study the influence of hydrocarbons ondenitrification after 1, 4 and 6 months. In theabsence of hydrocarbons in the control sediments, the presenceof macrofauna stimulated denitrificationby 160%. This stimulation is induced by sediment reworkingthat favours both direct NO-3 supply fromthe water column and the penetration of O{2}, which in turnstimulated nitrification, the other source ofNO-3 in sediment. The presence of hydrocarbons in theexperimental sediments either stimulated orinhibited the denitrification. The denitrification response tothe presence of hydrocarbon is dependent onthe quantity of matter buried by the macrofauna activity. Insmall quantities, the organic matter relatedto hydrocarbons 120% enhanced the denitrification compared tothe controls. On the other hand, whenburied hydrocarbon concentrations were higher (>100 mgsaturated hydrocarbon fraction kg-1 drysediment), the denitrification was inhibited.On the basis of the results obtained, a descriptive model ofthe patterns of denitrification in relation to the presence ofmacrofauna and the distribution of hydrocarbons in sediments is proposed

Quelques observations sur An. moucheti S.l. : différences morphologiques d'une population d'An. moucheti issue de Ebogo : rapport de mission effectuée du 12 au 14 novembre 1991 à Ebogo (Nyong et So'o)

1- Observations sur la composition du genre Anopheles au sein des différentséchanrillonnages.Le genre Anopheles est essentiellement composé par l'espèce An.moucheti. Sur976 identifications, nous avons observé 1 An. paludis issu de capture sur homme àl'extérieur des maisons et 1 An. gambiae issu de capture sur homme à l'intérieur d'unemaison de Soo-Assi.Tous les Anopheles capturés par les pièges lumineux étaient desAn.mouchetì.Conclusion: compte-tenu de la composition du genre Anopheles échantillonné à Ebogo,on ne peut pas retenir ce village comme station expérimentale pour tester les différentsadulticides OMS. La prospection d'un village où les captures sont composées par An.gambiae doit se poursuivre autour de Yaoundé.2-Observations sur les différences morphologiques d'une population d'An.moucheti.morphologiques qui interviennent dans l'identification et la différenciation des 2 sousespèces d'An.mouchetì et d'An.bewoetsi. An.bervoetsi est très proche d'An.mouchetì:on le retrouve assez souvent dans les collections d'An.moucheti. Pour chaque critère dedifférenciation, nous précisons quelles ont été nos observations pour la souche"Ebogo".En ce qui concerne les pattes, Gillies et de Meillon (1968) proposent pour :- An. moucheti moucheti Evans, 1925: tous les tarses, sauf le 5ème de toutes les pattes etle 4ème des pattes antérieures, avec une bande apicale claire Ctroite mais visible. - variations: des prélèvement issus d'Ouganda présentaient des tarses 4 antérieurs avecune petite tache apicale.- An.moucheti nìgeriensìs Evans, 1931: pas de différence avec An. mouchetì moucheti. - An.bervoetsi DHaenens, 1961: tarses antérieurs 4 avec une bande claire bien visible àl'apex

Example of the dockside accident risk

In many maritime countries, the work of sea fishermen is one of the most hazardous of occupations. The number of accidents is much greater than in other occupations on land or at sea, and the accidents themselves are often more serious. When considering the risks and hazards of fishing, one initially thinks of major risks like collisions or vessels running aground, as well as the work related injuries which are mainly caused by the fishing equipment (otter boards, ropes) and by the motions of the vessel. These accidents and, in a more general sense, the dangers met by fishermen at sea have already been studied. But little research has been undertaken on the problem of accidents of fishermen while the vessel is in port; and in France, these accidents account for about 30 % of all registered injuries for the sea fishing industry. The presented report takes a look at this category of accidents, on the basis of data on 5074 accidents registered between 1996 and 2005. An examination of statistics therefore points to certain types of risks and dangerous situations, but it also leaves a number of questions pending. One of these is the number of “unknown” causes. Falls, in particular, are usually linked to an outside factor which is not listed on the form the sailors must fill out. To compensate for the limitations of the epidemiological analysis, on-site observation seemed to be the best way of understanding the risks of the activities of fishermen in the port

Power of three multitrait methods for QTL detection in crossbred populations

The multitrait detections of QTL applied to a mixture of full- and half-sib families require specific strategies. Indeed, the number of parameters estimated by the multivariate methods is excessive compared with the size of the population. Thus, only multitrait methods based on a univariate analysis of a linear combination (LC) of the traits can be extensively performed. We compared three strategies to obtain the LC of the traits. Two linear transformations were performed on the overall population. The last one was performed within each half-sib family. Their powers were compared on simulated data depending on the frequency of the two QTL alleles in each of the grand parental populations of an intercross design. The transformations from the whole population did not lead to a large loss of power even though the frequency of the QTL alleles was similar in the two grand parental populations. In these cases, applying the within-sire family transformation improved the detection when the number of progeny per sire was greater than 100

Methods for the detection of multiple linked QTL applied to a mixture of full and half sib families

A new multiple trait strategy based on discriminant analysis was studied for efficient detection of linked QTL in outbred sib families, in comparison with a multivariate likelihood technique. The discriminant analysis technique describes the segregation of a linear combination of the traits in a univariate likelihood. This combination is calculated for each pair of positions depending on the inheritance of the pairs of QTL haplotypes in the progeny. The gains in power and accuracy for position estimations of multiple trait methods in grid searches were evaluated in reference to single trait detections of linked QTL. The methods were applied to simulated designs with two correlated traits submitted to various effects from the linked QTL. Multiple trait strategies were generally more powerful and accurate than the single trait technique. Linked QTL were distinguished when they were separated enough to identify informative recombinations: at least two genetic markers and 25 cM between the QTL under the simulated conditions. Except in a particular case, discriminant analysis was at least as powerful as the multivariate technique and its implementation was five times faster. Combining the advantages from both methodologies, we finally propose a complete strategy for rapid and efficient systematic multivariate detections in outbred populations