December 13, 1997
Letters
Other routes to improving the census
Regarding "Sampling and the Census" (SN: 10/11/97, p. 238): I propose that threatening to cut off future mail delivery to people who do not return census forms would enhance the return of those forms. Actually, the cost would not be as great as that of some of the other corrective measures being considered.A boldly printed message on the envelope would advise addressees of the threat, and postal workers could check off compliance or a justifiable reason for noncompliance on a form easily transmitted to the Census Bureau. Also, noncompliance could be measured and possibly corrected for in some way.
William C. Rose
Crystal, Minn.
If the Census Bureau simply counted people instead of becoming intrusive and offensive in the quest for information irrelevant to its Constitutional mandate, returns would improve greatly. I've spoken to many people about this, and the feeling is quite prevalent that most of the questions asked are none of the government's business. The arrogance and intrusiveness of the census takers alienates people who would otherwise cooperate in answering a simple head count or citizenship question.
Fix this problem and the count will improve.
V.E. Henley
Morgan Hill, Calif.
Use 'obese' with caution
I hope Velimir Matkovic was speaking with his tongue firmly in his cheek, because he appeared to be saying that anyone who is not unusually skinny or a fitness fanatic is obese ("Leptin linked to onset of monthly cycles," SN: 10/18/97, p. 247).This is the sort of thinking that sends teenage girls to the toilet to stick their fingers down their throats.
Daniel J. Berger
Bluffton, OhioSafety of ultrasound
When I read "Bursting bubbles break chemical bonds" (SN: 10/11/97, p. 228), this sentence jumped out at me: "Cavitation also occurs when ultrasound waves pass through liquids, producing bubbles that grow rapidly and then collapse in a flash of light."Millions of pregnant women receive ultrasound as a normal part of keeping tabs on their pregnancies. If this is not "ultrasound passing through liquid," I don't know what is.
Is there any research on this?
Jim Richings
Maydelle, Texas
A very good question! Only low-intensity ultrasound waves are used to image fetuses in the womb, so the procedure is safe. The waves that produce violently collapsing bubbles have a much higher intensity.
Actually, several groups are looking at high-intensity ultrasound to treat ailments such as kidney stones or to perform surgery without a scalpel. -- C. Wu
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Table
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