17 research outputs found
Seawater carbonate chemistry and impact of different carbonate system parameters on benthic foraminifera from controlled growth experiments
No full textInsights into past marine carbon cycling and water mass properties can be obtained by means of geochemical proxies calibrated through controlled laboratory experiments with accurate seawater carbonate system (C-system) manipulations. Here, we explored the use of strontium/calcium ratio (Sr/Ca) of the calcite shells of benthic foraminifera as a potential seawater C-system proxy through a controlled growth experiment with two deep-sea species (Bulimina marginata and Cassidulina laevigata) and one intertidal species (Ammonia T6). To this aim, we used two experimental set-ups to decouple as much as possible the individual components of the carbonate system, i.e., changing pH at constant dissolved inorganic carbon (DIC) and changing DIC at constant pH. Four climatic chambers were used with different controlled concentrations of atmospheric pCO2 (180 ppm, 410 ppm, 1000 ppm, 1500 ppm). Our results demonstrated that pH did not influence the survival and growth of the three species. However, low DIC conditions (879 μmol kg−1) negatively affected B. marginata and C. laevigata through reduced growth, whereas no effect was observed for Ammonia T6. Our results also showed that Sr/Ca was positively correlated with total Alkalinity (TA), DIC and bicarbonate ion concentration ([HCO3−]) for Ammonia T6 and B. marginata; i.e., DIC and/or [HCO3−] were the main controlling factors. For these two species, the regression models were coherent with published data (existing so far only for Ammonia T6) and showed overall similar slopes but different intercepts, implying species-specific effects. Furthermore, the Sr/Ca – C-system relationship was not impacted by ontogenetic trends between chamber stages, which is a considerable advantage for paleo-applications. This applied particularly to Ammonia T6 that calcified many chambers compared to the two other species. However, no correlation with any of the C-system parameters was observed for Sr/Ca in C. laevigata. This might imply either a strong species-specific effect and/or a low tolerance to laboratory conditions leading to a physiological stress, thereby impacting the Sr incorporation into the calcite lattice of C. laevigata
Bunch length measurements from the incoherent synchrotron radiation fluctuation at
No full textAbstract Bunch length measurements can be made by analysing the pulse to pulse intensity fluctuation of the incoherent synchrotron radiation as it has been reported at the AL
PREVALENCE DES CARDIOPATHIES RHUMATISMALES CHEZ LES JEUNES COLLEGIENS A PARAKOU EN 2012 (BENIN).
No full textRESUME : L’objectif était de déterminer la prévalence des cardiopathies rhumatismales dans le Collège d’Enseignement Général (CEG) Okédama de Parakou. Une étude transversale et descriptive a été menée sur deux mois (07 Mai au 05 Juillet 2012). Etaient inclus, tous les élèves présents, ayant accepté de participer à l’étude et dont les parents ont signé le consentement écrit. Le diagnostic de maladie rhumatismale a été posé sur la base des critères de Jones. La cardite rhumatismale a été retenue sur la base des critères échocardiographiques. Au total, 483 élèves ont été inclus. L’âge moyen était de 14,2 ±3,2 ans et la sex-ratio M/F de 0,46. Au terme des investigations, aucun élève n’a présenté de critères majeurs de Jones mais l’accumulation de deux critères mineurs a été retrouvée dans 1,9% des cas. La preuve biologique d’une infection à streptocoque bêta hémolytique du groupe A n’a été faite chez aucun élève. Finalement, aucun cas de cardiopathie rhumatismale n’a été retrouvé dans cet établissement. Une étude à grande échelle est nécessaire pour vérifier ces données
4CPS-031 Audit of antibiotic prophylaxis practice in visceral surgery in an African country
No full textAntibioprophylaxis in cesarean section: what are the current practices in four hospitals in Benin ?
No full textpeer reviewe
Epidemiology of Peripheral Artery Disease of Lower Limbs among Workers to Cotonou in 2013
No full textThe BaBar detector: Upgrades, operation and performance
No full textContains fulltext :
121729.pdf (Author’s version preprint ) (Open Access
Hand hygiene to prevent healthcare associated infections: investigation in Beninese settings.
No full text
Assessing the impact of different carbonate system parameters on benthic foraminifera from controlled growth experiments
No full textInternational audienceInsights into past marine carbon cycling and water mass properties can be obtained by means of geochemical proxies calibrated through controlled laboratory experiments with accurate seawater carbonate system (C-system) manipulations. Here, we explored the use of strontium/calcium ratio (Sr/Ca) of the calcite shells of benthic foraminifera as a potential seawater C-system proxy through a controlled growth experiment with two deep-sea species (Bulimina marginata and Cassidulina laevigata) and one intertidal species (Ammonia T6). To this aim, we used two experimental setups to decouple as much as possible the individual components of the carbonate system, i.e., changing pH at constant dissolved inorganic carbon (DIC) and changing DIC at constant pH. Four climatic chambers were used with different controlled concentrations of atmospheric pCO2 (180 ppm, 410 ppm, 1000 ppm, 1500 ppm). Our results demonstrated that pH did not influence the survival and growth of the three species. However, low DIC conditions (879 µmol kg-1) negatively affected B. marginata and C. laevigata through reduced growth, whereas no effect was observed for Ammonia T6. Our results also showed that Sr/Ca was positively correlated with total Alkalinity (TA), DIC and bicarbonate ion concentration ([HCO3-]) for Ammonia T6 and B. marginata; i.e., DIC and/or [HCO3-] were the main controlling factors. For these two species, the regression models were coherent with published data (existing so far only for Ammonia T6) and showed overall similar slopes but different intercepts, implying species-specific effects. Furthermore, the Sr/Ca-Csystem relationship was not impacted by ontogenetic trends between chamber stages, which is a considerable advantage for paleo-applications. This applied particularly to Ammonia T6 that calcified many chambers compared to the two other species. However, no correlation with any of the C-system parameters was observed for Sr/Ca in C. laevigata. This might imply either a strong species-specific effect and/or a low tolerance to laboratory conditions leading to a physiological stress, thereby impacting the Sr incorporation into the calcite lattice of C. laevigata
