'Enough' grain depends on use
The world's population can satisfy its hunger quite well with either a grain-based or a meat-based diet ("Can Grain Yields Keep Pace?" SN: 8/16/97, p. 104). Thus every individual has a choice: meat or grain.
But what of the collective? The process of turning grain crops into meat is grossly inefficient. If we, collectively, were to choose to eat grain -- as bread, pasta, and so on -- instead of feeding it to cattle, we could, in theory, feed many times our current world population with today's harvests.
The collective health benefits of such a choice would be equally dramatic.
Rita Colwell states that "remote sensing may help researchers provide early warnings of when and where cholera will strike. Such warnings may encourage people to take extra precautions with their drinking water" (SN: 8/2/97, p. 72). This implies that cholera epidemics are primarily due to misinformation of some sort on the part of sufferers and that the information provided by remote sensing would significantly help these people to avoid the disease.
Cholera is essentially a disease of poverty. It is caused not by lack of information but by horrible living conditions and polluted water. I hardly think that telling poverty-stricken people they should "take extra precautions with their drinking water" is very meaningful when they are forced to live in hovels and get their water from polluted sources. In fact, doing so would be an insult to their intelligence!
Cholera is indeed a disease born of poverty. Yet this poverty will not be eliminated in the near future, and Colwell believes that warnings of cholera outbreaks can be useful immediately. For example, she and her colleagues have shown that people can significantly lower the risk of cholera infection if they filter water through a folded sari, a traditional garment worn by millions of women. -- J. Travis
How much steroid is too much?
As an occasional user of inhaled steroids for asthma, I was concerned about the article linking them to cataracts ("Inhaled steroids linked to cataracts," SN: 7/26/97, p. 60). One thing was missing from the article, though: dosages.
Just how often do you have to use the inhalers before these effects appear?
Patrick J. Murphy
There is no clear-cut answer. "We just do not have enough data to say how many puffs a day and how many years of use are unsafe for the lens," replies Robert G. Cumming, an epidemiologist at the University of Sydney in Australia and lead author of the study. For posterior subcapsular cataracts, the most serious kind, more than 2 grams of beclomethasone, a corticosteroid, in a lifetime imparts about double the risk of a 1-gram dose, his research shows.
Asthmatics who use steroids should discuss proper dosage with their physicians, he says, but should remember that asthma, which can be fatal, is a more serious condition than cataracts, which can be treated surgically. -- N. Seppa
Gamma rays combat restenosis
In regard to Richard Petrasso's letter (SN: 8/23/97, p. 125) about "Unclogging arteries? Radiation helps" (SN: 6/14/97, p. 364), the distance from the Ir-192 source to the cells of the vessel at risk of restenosis can be measured in centimeters. As such, gamma rays are the treatment, not beta rays. Further, the iridium sources are encapsulated in metal, thereby attenuating and eliminating the beta emission. Indeed, when beta emitters are used, they are placed in contact with the vessel wall, usually by radioactive stent, because beta rays' effective range is so small.
James P. Vaughan
Department of Radiation Oncology
Buffalo General Hospital
New vantage on theropod flight
Why hasn't anyone proposed that smaller theropods were arboreal ("A Fowl Fight," SN: 8/23/97, p. 120)? If kangaroos, leopards, and bears can climb trees, why couldn't those short forearms have been used to scramble up bare trunks?
Some paleontologists are beginning to explore the idea that small theropods climbed trees and evolved flight from this vantage point. Alan Feduccia, however, argues that the anatomy of theropod pelvic bones precluded them from climbing trees. -- R. Monastersky
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