Dental sealant stance questioned
I applaud the American Dental Association's (ADA) sponsorship of further research into the safety of dental sealants ("Dental Sealant Safety Reconsidered," SN: 11/22/97, p. 324). However, I find it troubling that ADA would continue its "strong recommendation that dental sealants be used as appropriate."
Dental sealants are now big business within the dental community. Consequently, ADA must maintain its impartiality regarding sealant safety until all of the data can be gathered and analyzed.
ADA's apparent lack of objectivity undermines its credibility and the credibility of the studies it sponsors.
Mount Pleasant, Mich.
Enhancing the beholder's eye
The title "Supernormal Vision" may be misleading (SN: 11/15/97, p. 312). I was fortunate enough to have attended the meeting where David R. Williams presented the work on achieving better imaging by warping optics, and I am not at all sanguine about this leading to promising improvements in patients' vision through the development of new types of spectacles or contact lenses.
Among other things, these new elements add their own source of optical aberration. Glasses may slide down the nose to different positions, for example, or contact lenses may rotate or float on tear films of different thickness.
The great promise of this work lies in enhancing the ability to observe the back of the human eye. Better visualization of the retina, vasculature, nerve fiber layer, and optic nerve head should prove extremely helpful in characterizing normal structure, as well as the effects of disease.
Alfredo A. Sadun
Professor of Ophthalmology
University of Southern California
Los Angeles, Calif.
Magnetic fields in hospitals
Did anyone suggest that the magnetic field of the average hospital room be examined ("Magnetic fields can diminish drug action," SN: 11/29/97, p. 342)? Often, the most aggressive drug therapy takes place in the hospital setting. Clearly, this might influence the results of certain clinical trials also.
Los Altos, Calif.
Social forces and chip technology
I just finished reading "Fine Lines for Chips" (SN: 11/8/97, p. 302). The concluding paragraphs comment briefly about economic and political factors potentially affecting technologies for future chips. Maybe these factors should have been discussed first.
We live in such a politicized and profit-driven society that, realistically, economics and politics will probably be the driving forces behind technological advancement.
"Astronomers Aglow About Infrared Maps" (SN: 1/10/98, p. 20) notes that the accompanying map reveals the pattern of extragalactic background light at a wavelength of 240 millimeters. The correct number is 240 micrometers.
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