Influence of aging on the color visual field in humans: A cross-sectional study.

ABSTRACT: Age-related narrowing of the visual field is observed in the elderly, which leads to reduced cognitive and psychomotor functions. The aim of the present cross-sectional study was to determine the influence of aging on the visual field for color vision in humans, with respect to angular thresholds for object detection and color detection.The subjects were divided into the elderly group (mean 76.1-year-old [70-89]) and the control group (25.2 [18-47]). Visual fields for different colors (blue, green, yellow, and red) were measured by manual kinetic perimetry and evaluated in terms of 2 measures of visual-field width: angular thresholds for object detection and those for color detection.While angular thresholds for object detection were significantly wider than those for color detection in the control group (P < .001), there was no difference in the elderly group (P = .06). Moreover, angular thresholds for object detection were significantly wider in the control group than in the elderly group (P = .019), but angular thresholds for color detection were not significantly different between the 2 groups (P = .903).The observed age-related changes in angular thresholds for object detection in color vision may reflect an age-related reduction in rod function. Stable cone function might explain the preserved angular thresholds for color detection in the elderly.

Nitrogen dioxide (NO2) created by gamma-rays in Antarctic ice and rime ice.

Antarctic ice and rime ice after gamma-irradiation at 77 K were studied by electron spin resonance (ESR). The signal of nitrogen dioxide (NO2) was detected in both ices. The NO2 in the Antarctic ice, in particular, may be created from NO3- by reactions associated with intrinsic OH radicals. The detection limit of NO2 in solid samples was estimated to be approximately 0.02 ppm with ESR. The analysis using ESR in natural ice has a potential to trace environmental NO2.

ESR investigation of gamma-irradiated natural methane hydrate from Blake Ridge Diapir, off east North America in ODP Leg 164.

Natural methane hydrate under deep ocean floor in Ocean Drilling Program (ODP) Leg 164 was studied by electron spin resonance (ESR) after gamma-ray irradiation. The methyl radical (g=2.0024+/-0.0005, A=2.3+/-0.1 mT) as well as an unidentified signal was observed. Although the parameters and the thermal stability were very similar to those in a synthetic sample, the signal intensity was about one eightieth of that in synthetic one because methane hydrate had partially changed to ice. ESR signal intensity of the methyl radical after gamma-ray irradiation could be used to estimate the amount of methane hydrate in a sample mixed with ice.