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Biomedical subjects

A Richard

Publications and source records attributed to A Richard.

At least 181 records · Page 10Linked to original sources
PubMedDate not supplied

A three-state Markov model of Plasmodium falciparum parasitemia.

A three-state Markov model taking into account clinical signs of malaria infections by P. falciparum is described. The three states considered are the noninfected (state 0), the infected exhibiting no clinical signs (state 1), and the infected with clinical signs (state 2). Methods for estimating the transition rates from longitudinal data are indicated. This model was used to assess the effect on children of an intervention trial on the use of mosquito nets impregnated with insecticide. The trial was conducted in West Africa (Burkina Faso) between 1985 and 1987. The analysis showed that the intervention was most effective on transition rates between state 1 and state 2.

Burkina Faso↗
PubMedDate not supplied

Field enhancement and apertureless near-field optical spectroscopy of single molecules.

We report on fluorescence enhancement in near field optical spectroscopy by apertureless microscopy. Our apertureless microscope is designed around a confocal fluorescence microscope associated with an AFM head. First, we show that the confocal microscope alone allows single molecule imaging and single molecule fluorescence analysis. When associated with the AFM head, we demonstrate, for the first time to our knowledge, that single molecule fluorescence is enhanced under the silicon tip. We tentatively attribute this effect to field enhancement under the tip.

Journal Article↗
PubMedDate not supplied

Gender differences in neonatal subcutaneous fat store in late gestation in relation to maternal weight gain.

OBJECTIVE: To study gender differences in fat store in human newborns and their relation to duration of gestation and maternal weight gain. METHODS: The ratios subscapular skinfold thickness/body weight (SST/BW) and tricipital skinfold thickness/body weight (TST/BW) were calculated in a sample of 13609 premature and term neonates from the maternity hospital of Clamart, Hauts-de-Seine, France. RESULTS: Whereas BW, SST and TST increased with gestational age, SST/BW and TST/BW ratios decreased regularly, in males as in females. This result reflects a progressive reduction of subcutaneous fat store per body weight unit as the duration of gestation increases. Males had smaller values of SST/BW and TST/BW ratios than females whatever the gestational age. Increasing maternal weight gain during the third gestational trimester did not improve the subcutaneous fatness per body weight unit of the newborn. Earlier amount of maternal weight gain had an effect on the TST/BW index exclusively in females. CONCLUSIONS: In newborns, a gender difference was observed in the ratio of subcutaneous fat per unit of body weight; this ratio is lower in males than in females. This result argues for a gender difference in mobilization of fat store to ensure normal growth in the last weeks of pregnancy: males lose more fat but gain more weight than females in this period. Late maternal weight gain does not affect the proportion of subcutaneous fatness by body weight unit in both genders.

Adult↗
PubMedDate not supplied

Ethnic difference in duration of pregnancy.

It is suggested that the observed difference in duration of pregnancy between Blacks and Whites is partly physiological since it is not entirely explained by social inequities alone. This study compares women with well-defined gestational periods seeking attention at the Antoine Béclère Maternity Clinic. Group A consists of French women of European ancestry, Group B, those born in the French Antilles of mixed ancestry, and Group C black African women with insignificant European admixture. When compared to Group A, within each socio-economic class, group B and C have shorter gestational periods. These differences persist after adjustment for socio-economic variables, so that other explanations should be considered, specifically genetic determinants.

Africa↗