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InGaN/GaN devices are currently used for many applications, for example, full color display, white (RGB) illumination systems and for the realization of shorter wavelength emitters for optical data storage. We previously reported a blinking phenomenon in the photo-luminescence of InGaN device ready single quantum well materials. In this study we observe in high resolution this optical instability with a near-field nano-probe. The phenomenon appears only in local confined domains and does not seem to behave as a bistable state process like reported on quantum dots generated photo-luminescence. We investigated by a modified scanning near-field optical microscope (SNOM) and studied the time/intensity profile of the optical signal with a resolution in the range of 100nm. The dynamics of the blinking was time-resolved and its behaviour studied with Fourier analysis. Despite the intensity oscillations were found to have chaotic component (autocorrelation coefficient is about 0.63), the optical oscillations appear to include regular characteristics. Fourier analysis of the light intensity from confined domains exhibit peaks in the range of 4–5 s. The emergence of these intriguingly slow and partially regular dynamics should shed light on the inner mechanism that are involved in the fundamental processes of optical emission in these devices.

6, KJ00000304875, P

The frequency and characteristics of cortical cataract localization within a dilated pupillary area were investigated in a population-based cataract epidemiological survey performed in the city of Reykjavik in Iceland.Among 1045 randomly selected individuals, the right eyes of 277 persons with mild cortical lens opacification (Grade I) were selected for our study. The localization of cortical cataracts was examined using retroillumination images, which were divided into 56 circular and radial sections, and calculations were made of the percentages for each opacified area. A questionnaire was used to record the number of hours spent outdoors during week days, the time of the day and whether the subjects wore spectacles, sunglasses or hats when outside.The percentage of cortical opacification was significantly higher in the lower nasal quadrant than in all other quadrants (p0.05). Furthermore, the percentage of opacification localized in the lower nasal quadrant was higher in individuals with a longer history of outdoor activity than those without (p0.05). The percentage of opacification in individuals, who have had the habit of wearing sunglasses for outdoor activities lasting longer than half an hour during weekdays in their 20's and 30's was lower in all quadrants and statistically significantly lower in the upper temporal quadrant (p0.05) compared to those not wearing sunglasses.This suggests that wearing sunglasses is effective in preventing the development and/or progression of cortical cataracts.