Production primaire et relations trophiques chez les invertébrés des communautés halophiles de Camargue

Les biomasses végétales mesurées dans les zones émergées de la sansouire camarguaise sont relativement élevées dans le Sali cornietum fruticosae, de l’ordre de 3 kg de matière sèche par m2 alors qu’elles n’atteignent que 0,4 kg/m2 dans Y Arthrocnemetum. La production primaire annuelle du S. fruticosae se situe entre 0,5 et 1 kg de matière sèche par m2, soit du même ordre que celle d’un peuplement à Quercus ilex étudié sous le même climat. Elle est réalisée pour l’essentiel en trois mois, de mai à juillet. Ensuite l’abaissement de la nappe aquifère, conséquence de la forte évapo ration estivale, se traduit par une chute du potentiel hydrique et par une régulation efficace de la transpiration. L’étude des niveaux de consommation chez les Invertébrés terrestres montre, qu’en dehors de périodes exceptionnelles de pullulation des chenilles de deux espèces de microlépidoptères, la forte production primaire de S. fruticosae n’est pas utilisée directement. Les détritivores (Coléoptères, Collemboles) et les décomposeurs jouent un rôle essentiel. Dans les zones à submersion temporaire l’abondance des débris végétaux desséchés pendant l’été qui s’ajoute à la production alguale pendant l’inondation hivernale permet la pullulation des Crustacés planctoniques, en particulier celle des Copépodes Cala nides filtreurs dont plusieurs espèces de tailles différentes peuvent proliférer ensemble. Ces populations de Crustacés ainsi que les larves aquatiques d’insectes procurent lors de l’assèchement une nourriture abondante pour la communauté ripicole où les Coléoptères Carabiques sont bien représentés.The above-ground plant biomass in the emerged zones of the Camargue “ sansouire ” is relatively high in Salicornietum fruticosae, about 3 kg of dry matter per square metre, whereas it only reaches 0.4 kg/m2 in Arthrocnemetum. The above-ground annual primary production of Salicornietum fruticosae ranges from 0.5 to 1.0 kg/m2/year, which is approximately equal to that of Quercus ilex stands in the same climate. Production essentially takes place during a three month period from May to July. Afterwards the lowering of the water table resulting from the high level of evaporation during the summer is marked by a decrease in water potential and by an efficient regulation of transpiration. Aside from exceptional outbreaks of caterpillars of two species of microlepidoptera, the primary production of Salicornia is not used by primary consumers, but by detritus feeders (beetles and springt ails) and decomposers. In the areas temporarily flooded, algal production during winter flooding and the accumulation of dried plant debris in summer, allow planktonic Crustacea, Calanoid Copepods particularly, to reach high population densities. These Copepods, together with the larvae of aquatic insects, provide an abundant food for Carabid beetles and other riparian invertebrates when water recedes and the “ sansouire ” dries out

The benefits of participatory methodologies to develop effective community dialogue in the context of a microbicide trial feasibility study in Mwanza, Tanzania

BACKGROUND: As part of a microbicide trial feasibility study among women at high-risk of HIV and sexually transmitted infections in Mwanza City, northern Tanzania we used participatory research tools to facilitate open dialogue and partnership between researchers and study participants. METHODS: A mobile community-based sexual & reproductive health service was established in ten city wards. Wards were divided into seventy-eight geographical clusters and representatives at cluster and ward level elected in a process facilitated by the projects Community Liaison Officer. A city-level Community Advisory Committee (CAC) with representatives from each ward was established. Workshops and community meetings at ward and city-level were conducted to explore project-related concerns using tools adapted from participatory learning and action techniques such as listing, scoring, ranking, chapatti diagrams and pair-wise matrices. RESULTS: Key issues identified included beliefs that blood specimens were being sold for witchcraft purposes; worries about specula not being clean; inadequacy of transport allowances; and delays in reporting laboratory test results to participants. To date, the project has responded by inviting members of the CAC to visit the laboratory to observe how blood and genital specimens are prepared; demonstrated the use of the autoclave to community representatives; raised reimbursement levels; introduced HIV rapid testing in the clinic; and streamlined laboratory reporting procedures. CONCLUSIONS: Participatory techniques were instrumental in promoting meaningful dialogue between the research team, study participants and community representatives in Mwanza, allowing researchers and community representatives to gain a shared understanding of project-related priority areas for intervention

Ruinas, círculos, construcciones

This article is organized around three groups of 'citations' from architectural forms, texts, images, which generate three options of imagination, representation and reading of space: ruins, circular constructions, and rhetoric (in particular figures of repetition). I discuss the story of Borges "Las ruinas circulares" and examples from Iain Sinclair, London orbital (2002), Gianni Biondillo and Michele Monina, Tangenziali. Due viandanti ai bordi della città (2010), and Nicolò Bassetti, Sapo Matteucci, Sacro romano GRA (2013). The circularity generates a repetitive and disparate look allowing the observation of a complementary rhythm of destruction and construction characteristic of progress in the world

Very high resolution study of high Rydberg levels of the configurations 4f14 6snd of Yb I

High Rydberg levels of ytterbium were studied in a beam of metastable atoms. Levels of the series 4f14 6snd were populated from the metastable 4f14 6s 6p 3Po level by means of the U.V. light of a frequency-doubled single-mode dye laser and detected using the field ionization technique. The critical ionization fields Fc of the levels 4f14 6snd 3D1 (24 ≤ n ≤ 57) were measured and found to obey the saddle point law (Fc = (16 n* 4)-1). The hyperfine structures of the odd isotopes were investigated. They are very peculiar due to the fact that the hyperfine interaction is of the same order of magnitude as (or even for the highest n values, much more important than) the spin-orbit and electrostatic interactions. A theoretical account of the observed structures using the Slater-Condon parametric method is given. The relative influence of the excited (nd) and of the non-excited (6s) optical electron could thus be studied. Furthermore the influence of a valence level perturbing only the odd isotopes components for n = 26 was demonstrated.Les niveaux de Rydberg élevés de l'ytterbium ont été étudiés sur un jet d'atomes métastables. Les niveaux de la série 4f14 6snd ont été peuplés à partir du niveau métastable 4f14 6s 6p 3P 0 grâce à la lumière ultraviolette d'ùn laser à colorant monomode double en fréquence et détectés par la méthode d'ionisation par un champ électrique. Les champs critiques d'ionisation Fc des niveaux 4f14 6snd 3D1 (24 ≤ n ≤ 57) ont été mesures; ils obéissent à la loi du col(Fc = (16 n*4)-1). Les structures hyperfines des isotopes impairs ont été analysées; comme l'interaction hyperfine est du même ordre de grandeur que les interactions électrostatiques et spin-orbite (ou même pour les valeurs de n les plus élevées plus importantes que ces dernières), ces structures ont un aspect très particulier. Les structures observées ont été interprétées théoriquement par la méthode paramétrique de Slater-Condon. Les influences respectives de l'électron optique excité ( nd) et de l'électron optique non excité (6s) ont ainsi pu être étudiées. De plus, l'influence d'un niveau de valence perturbant seulement les composantes des isotopes impairs a été mise en évidence pour le nombre quantique n = 26

Assessment of the Impacts of Anthropogenic Activities on a Large River Using Longfin Eel as a Bioindicator

The Matāura River is the sixth largest river system in New Zealand and has long been subject to agricultural, industrial, and residential land use activities. The catchment has economic value and is of great cultural importance for local Māori, who have concerns over potential adverse impacts that anthropogenic stressors exert on the health of the river. There is a dearth of information on the impacts of these stressors towards the health of native species such as the longfin eel Anguilla dieffenbachii. This study assessed the environmental status of the Matāura River using biological and chemical methodologies incorporating A. dieffenbachii as a bioindicator species for exposure to multiple anthropogenic stressors. A range of biomarkers were measured in caged and wild-caught eels (when available) to characterize site-specific responses to anthropogenic stressors. While there was no clear indication of cumulative impacts moving from pristine headwaters to the lower reaches of the Matāura River, biomarkers of xenobiotic metabolization were induced in A. dieffenbachia and there was evidence of chemical contamination in sediment and tissue samples

Spatial variation in density and total size estimates in fragmented primate populations : the golden-crowned sifaka (Propithecus tattersalli)

International audienc