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Biomedical subjects

A Delorme

Publications and source records attributed to A Delorme.

4 recordsLinked to original sources
PubMed1977

Influence of temporal frequency on perceived speed.

The visual perception of velocity was studied in three experiments. The stimulus used in the first experiment was an endless striped belt moving behind a stable fixation line. In the second experiment a vertical moving line was presented in front of a stable striped background. In the third experiment the same moving line was pursued by the eye but the background was stable or moving either with the moving stimulus or in the opposite direction. The variables studied were the speed of the moving stimulus, the speed of the background, and the density (spatial frequency) of the stripes. Two theoretical explanations of the perceptual effects obtained are compared. The first explains variations of perceptual velocity in terms of density. The second asserts effects of perceptual velocity are contingent upon temporal frequency of encounters between the moving stimulus and the stable or moving contextual elements. The results favor the latter interpretation in the three experiments, but part of the results of Exp. 3 could be explained by the influence of ocular pursuit.

Adult↗
PubMed1976

Methodologic problems in plasma renin activity measurements.

The influence of pH and angiotensinase inhibitors on the in vitro generation of angiotensin I during PRA measurements has been investigated. PRA values obtained at pH 5.7 are higher than those obtained at pH 7.4. At pH 5.7, values obtained using diisopropylfluorophosphate (DRP 9 mM) as an angiotensinase inhibitor are higher than values obtained with a mixture of dimercaprol (BAL, 1.6 mM) and hydroxyquinoline (8-OHQ, 3 to 4 mM). Since the two methods for inhibiting angiotensinase are completely and equally efficient, it is suggested that these inhibitors might interfere with the renin angiotensinogen reaction. Significant correlations are observed between the PRA values obtained by the different methods which have been studied. Using an incubation pH of 5.7, and BAL and 8-OH quinoline as angiotensinase inhibitors, the distribution of PRA values in a population of 124 hospitalized hypertensive patients ingesting a normal sodium diet had been studied, and it has been demonstrated that the sensitivity of this method of measurement can detect small changes in PRA in patients with low renin activity.

Adenoma↗