Search

Intestinal parasitism and its epidemiological characteristics were studied in an isolated Amerindian population from Upper Oyapock (French Guiana) that has retained its traditional social and cultural specificities. This population consisted of 138 Wayampi Indians, 68 adults and 70 children (below the age of 15 years), with a sex ratio (M/F) of 0.86, spread over the four villages of the community of Trois Sauts, corresponding to more than two thirds of the population recorded as inhabiting the sector in the last census (375 inhabitants). Fecal examination combined the direct examination of fresh feces with the quantitative techniques of Kato-Katz method, Baermann and MIF staining. Overall, 92 % of the subjects were found to have intestinal parasites, 85 % if only direct examination of fresh stools was taken into account. Fourteen species of human parasite were identified: seven protozoa and seven helminths. We observed in particular 1) a high frequency of hookworm infection due to Necator americanus. Over 50 % of subjects were affected, with a range of 25 % to 75 % according to the village, but with only moderate parasite loads; 2) a high level of parasitism by E. histolytica/E. dispar (17 %), Stongyloides stercoralis (16 %) and Hymenolepis nana (18%) ; 3)a lower level of parasitism by Ascaris lumbricoides and very low levels (almost absent) of Trichiuris trichiura ; 4) the absence of Schistosoma and fluke eggs. With the exception of H. nana, which was more frequent in children than in adults, there was no significant difference in the level of parasitism according to sex and age. Although the Wayampi of French Guiana are French citizens and consequently have quite high incomes and ready access to clinics and medicines, intestinal parasites are far from under control in this population. A lack of fecal hygiene and the habit of walking barefoot are widespread in the unchanging Amazonian environment and contribute to this phenomenon.

In the present study, experiments were carried out in a single-cylinder downsized SI engine with different rates of oxygen (15% to 27% by volume in the total mixture of intake gases except fuel) and equivalence ratios (from 0.45 to 1). Therefore, the oxygen volume fraction is due to oxygen enrichment or nitrogen dilution. The study of the impact of controlling the oxygen concentration on the combustion characteristics and emissions was performed at 1 400 rpm, at several loads (Indicated Mean Effective Pressure (IMEP) from 400 to 1 000 kPa). For each operation point, the spark advance and the intake pressure were adjusted simultaneously in order to maintain the load and obtain a minimum value of the indicated Specific Fuel Consumption (SFC). The effect of the oxygen concentration on the engine combustion characteristics was simulated by using the commercial software AMESim, with the combustion model developed by IFP Energies nouvelles, and an adapted algorithm was used to avoid residual gas calibration. By implementing a correlation for the laminar burning velocity, the in-cylinder pressures were perfectly predicted with a maximum pressure relative error of less than 2% for almost all the operating points. The classification of engine combustion according to the Peters-Borghi diagram, gives a deeper insight into the interaction between turbulence and the flame front.

A comparative analysis of the spalling of (a) cores made of 3 concrete mixes embedded into 3 slabs made of the 3 same concrete mixes; and (b) 3 reference slabs made again of the same 3 concrete mixes has been made. Samples have been exposed to the French Increased HydroCarbon temperature curve. Results confirm that concrete spalling phenomena is not only related to the material properties. Concrete spalling is also very much influenced by the geometry of the samples.

Several concrete mixes have been designed to evaluate the influence of an air entraining agent (AEA) on spalling. Tests have been performed under the ISO curve (occasionally under the HCinc curve) on specimens of various sizes and shapes to assess spalling. Results were somehow erratic on the smallest specimens whereas the beneficial effect of the air-bubble network could be emphasized on slabs.