Biological effects of excimer laser radiation
Article Abstract:
The two most important medical uses of lasers are removing artherosclerotic plaque from arteries with the 308-nanometer (nm) XeCl excimer laser and improving vision by controlled ablation of the cornea with the 193 nm ArF excimer laser. However, researchers have been concerned that exposing living tissue to 193- or 308-nm ultraviolet (UV) radiation could cause DNA damage, possibly leading to mutation or tumor formation. UVA radiation initiates photochemical reactions of chromophores in tissue and cells. Laser radiation at 254 nm and 308 nm causes cell mutation and death at fluences similar to those needed for low-intensity 254- and 313-nm radiation. Absorption of 193-nm radiation by protein surrounding the nuclear DNA and lower quantum yields of toxic DNA photoproducts at this wavelength account for its low biological effectiveness.
Publication Name: Proceedings of the IEEE
Subject: Electronics
ISSN: 0018-9219
Year: 1992
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Time, frequency and space geodesy: impact on the study of climate and global change
Article Abstract:
New space-based instruments are undertaking one of the most important investigations of the Earth; the measurement of open ocean circulation and sea level as an indicator of global warming. The data provided will be a vital means for assessing the effectiveness of remedial actions. The science of time and frequency metrology enabled the development of the space geodetic systems that are accurately tracking these instruments. A wide variety of competing instrument related artifacts and geophysical signals must be measured, modeled and removed before sea level signals can be distinguished. Time and frequency issues are included in all of these space geodetic techniques.
Publication Name: Proceedings of the IEEE
Subject: Electronics
ISSN: 0018-9219
Year: 1991
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