The present study examines the stability of bright light circadian readjustment during two consecutive dim light night-work periods and circadian synchronization during the recovery after a night-shift period. A sample of 10 subjects was divided into 2 groups (control group : 6 subjects; experimental group: 4 subjects). All subjects worked during 5 days, between 23:00 and 07:00 h and then went to sleep. Subjects received 2500-3000 lux between 02:00 and 05:00 h during 5 days for the control group and 3 days for the experimental group. During recovery after the night-shift periods, three cycles of bright light were administered at two different times: 12:00-15:00 h for two of six subjects from the control group and 10:00-13:00 h for all subjects (4) of the experimental group. By the fifth cycle of night-work the maximum of urinary aMT6s excretion that occurs at 05:00 h in the baseline condition was shifted to 12:00 h for the control and experimental groups (delay in hours: 7 +/- 1.6 (control); 7 +/- 1(experimental)). This result suggests that three cycles of bright light are sufficient to induce a significant phase delay and that this delay remained stable when night-work proceeded under dim light. The phase delay of the circadian aMT6s excretion by exposure to bright light was accompanied by an improvement of the quality of day sleep and level of cognitive and psychomotor performances for control and experimental groups. No significant difference was observed in the two groups for daytime sleep and nocturnal performance. The two bright light periods used during the three days of recovery induced a complete synchronization in five of six subjects. One subject showed a partial sychronization probably because he remained at the laboratory under dim light during the day and had few family and social contacts.
In order to determine whether chronic exposure to loud noise has demonstrable biological effects on humans, a study was conducted on the effect of mother's exposure to airport noise while pregnant upon birthweight and gestation lenght. In a first step birthweights of children were collected in 12 towns in the Paris area : a sample of 636 subjects from the Orly area (4 towns), another of 1432 subjects from the Roissy area (4 towns) and a reference sample of 1224 subjects from an area not submitted to the aircraft noise (4 towns).The analysis of weights in the three areas shows a significantly higher birthweight for the boys born in the non submitted aircraft noise area, meanweight : 3433.92 g, by comparison with Orly area, 3356.24 g, and Roissy area, 3355.95 g. The mean birthweights of girls of Orly, Roissy and reference samples were respectively : 3231.43 g, 3202.83 g and 3268.24 g.There is a significant difference only between the Roissy and reference samples.The second step of this study, actually in progress, concerns the analysis of the possible influence of other factors : mother's age, primiparity, gestational age, and so on. These factors could be combined or not.
The study's aim was to identify female and male face shape variability in order to establish typical profiles for the design of masks. A specific data acquisition photogrammetric station was used for this purpose. A preliminary survey using anthropometric techniques was conducted on 301 females and 208 males, randomly selected from the French military population, in order to constitute two samples of 30 males and 30 females for the stereometric survey. For each subject, the stereorestitution of face photos was made on three sets of data: (1) 37 anatomical landmarks previously identified by a black point marked on the face; (2) 7 anatomical arcs, also drawn with a black pencil; and (3) 1500-2000 points distributed on horizontal cross-sections at different vertical levels. The analysis only concerned the global face shape, and excluded the central area (eyes, nose and mouth). A common origin and reference axis system was defined. All the three-dimensional (3D) produced data was processed using computer-aided design software, after some adaptations. Subjects were selected iteratively for five levels of cross-section and three anatomical arcs so as to characterize least variation amplitudes, subject by subject. Five groups were identified. All cross-sections were verified to check the validity of the preceding step. By this method, each group was defined by a mean profile form and by the amplitude of this form for each point of the profile. Males and females were present in each group, and for each group, a greater variability was noted at the lower part of the face. This variability can be explained as the result of morphological and functional phenomena. These results can be applied to the design of new protective equipment for the fore-face indeed they were used for the design of a new mask for the French military.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.