Rhubarb, rhubarb
Please inform John Emsley that the deaths which occurred after consumption of rhubarb leaves (New 杏吧原创, Science, 5 November) were probably not caused by oxalic acid. According to E. Streicher (Deutsche medizinische Wochenschrift, vol 89, 1964), it is the antrachinones (total content 0.5 to 1.0 per cent) in young rhubarb leaves which is responsible for the toxic effects. So your heading and picture caption seem unduly alarmist.
Table salt can also be toxic.
Feynman's joke?
During the autumn I supervised an undergraduate course in “Rigid Bodies Dynamics”. On my lookout for supplementary problems for my students a scene in Surely you’re joking, Mr Feynman came to mind. In the chapter “The dignified Professor”, Feynman describes a scene in a cafeteria where he is observing a guy throwing a plate in the air:
“As the plate went up in the air I saw it wobble, and I noticed the red medallion of Cornell on the plate going around. It was pretty obvious to me that the medallion went around faster than the wobbling. I had nothing to do, so I started to figure out the motion of the rotating plate. I discovered that when the angle was very slight the medallion rotated twice as fast as the wobble rate 鈥� two to one. It came out of a complicated equation.”
Using Euler’s equations for a symmetric object one can find the body and space frequency of the plate, with the body frequency corresponding to the rotation of the medallion and the space frequency to the wobbling. For small angles the equations do indeed become beautifully simple but the ratio is not two to one as Feynman states. It is one to two.
The wobbling is faster than the rotation of the medallion, so how Feynman can write that “It was pretty obvious to me that the medallion went around faster than the wobbling” is not clear. Perhaps it demonstrates his well known objection to authorities and is a hint that people should not trust anybody, but work the things out themselves. At least it taught me, and hopefully my students, a valuable lesson.
Do we exist?
J.N. Chubb, criticising the New 杏吧原创 for using the promotional line “You are what you know” maintains that “It is truer to say you are what you do” (Letters, 3 December).
Bertrand Russell once spoke of the “egocentric predicament”, the problem in the theory of knowledge arising from the fact that the individual subject is confined to the closed circle of his own current sensations, and has no way of reaching knowledge beyond them.
This strict empiricism supports New 杏吧原创’s “You are what you know”, and rules out J. N. Chubb’s “You are what you do”, with its assumption of “other people” who give “feedback on the utility and truth of your ‘knowledge'”.
For the purpose of this letter I am assuming the existence of the New 杏吧原创 and J. N. Chubb, even though they may not exist outside my mind.
Smoke scheme
Nobel prizewinners should think themselves lucky they get anything at all (Comment, 17 December).
Alfred Nobel’s original plan for the use of his fortune was for the construction of crematoria in major cities all over Europe, if the reputable French reference book Quid is to be believed. However, opposition to the idea from the Roman Catholic church was so strong that he had to devise another scheme.
It is also said that the reason that there has never been a prize for mathematics is that Nobel’s wife had had an affair with a mathematician.
'p ubbliqs pea king
Another example of a phrase which the reader-aloud may not make sense of, though his hearers do (Letters, 19 November), is given in Text Book of Psychology by William James, published about 1902: Pas de lieu Rh么ne que nous.
As a curiosity it is more elegant, consisting only of quite common real French words.
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Hazardous food
John Maurice rightly brings the topic of food poisoning back to the headlines as the number of cases continues to rise (“The rise and rise of food poisoning”, 17 December). He mentions HACCP (Hazard Analysis by Critical Control Point) as a means of halting the trend.
Traditionally, laboratory analysis of the end products has been the principal check on the microbiological safety of foods, but since, logistically, the number of samples that can be analysed is low, negative results 鈥� that is, the absence of the pathogen being sought 鈥� do not give the required degree of assurance. However, any positive samples are highly significant.
Sectors of the food industry have abandoned end-product testing and, at the request of the major retailers, have adopted HACCP.
Microbiological analyses are done only occasionally as part of the procedure for verifying that the appropriate control points have been identified and are under control. The chances of detecting deviations from specifications are thus even lower than those from end-product testing.
As the incidence of food-borne disease continues to increase, it is evident that HACCP as currently practised is not giving the consumer safe food. I advocate HACCP systems, which have proved invaluable as a management tool in determining what actually is done in factories, but feel that at present they should complement and not replace end-product testing. There are numerous rapid and automated methods available which yield results before the food would be consumed.
When the cause and source of half the reported cases of food poisoning cannot be determined, and new pathogens are regularly reported, it is optimistic to expect that all appropriate control points and control measures can be put in place.
Non-humanised
Phyllida Brown refers to the Lancet paper by Caren Lanting and her colleagues on neurological differences between 9-year-old children previously fed breast milk or formula (This Week, 19 November). These authors comment “despite the long history of evidence” on the need for arachidonic (AA) and docosahexanoic (DHA) acids for brain development, the manufacturers have not yet updated what they call “humanised” formulas to make them similar to breast milk in this respect.
That long history dates back to evidence in the early 1970s showing that AA and DHA were limiting factors in brain development and function. It also includes the report of the International Expert Committee called by the Food and Agricultural Organisation and WHO in 1977, which stated that milk manufacturers should follow the composition of human milk in this respect.
Brown reported that an SMA Nutrition spokesperson defended the industry’s lack of response by saying that the evidence should be critically scrutinised and safety proven. Having published details of the composition of human milk in 1974, Bernard Laurance and I, in collaboration with Reckitt and Colman and Huntingdon Research, produced a milk containing AA and DHA. It was tested successfully on 63 babies. The points made were (i) it was possible to do it with well-tested and commercially available materials and (ii) the loss of circulating AA and DHA seen in formula compared to breast-fed babies could be avoided in this way.
Egg lecithin provided AA and cod liver oil supplied DHA and fat-soluble vitamins. Egg lecithin was considered safe as it had been used for a long time in the food and baking industry as an emulsifier. Cod liver oil had a long history as a supplement for babies fed cow’s milk formula and was even delivered free to the doorsteps of women with babies during the war.
“Humanised” as a term to describe milk substitute is misleading where vegetable oils are used to replace the animal lipids in human milk. Asses used to be kept at a Paris hospital to provide milk for preterm babies. The lipid components of asses, or even pigs’ milks would be better than the vegetable oils used in milk substitutes.
Sex and similarity
I have noticed the pattern of inheritance mentioned by Martin Cole for many years (Letters, 10 December). I have never come across any studies relating to it nor have I found anyone interested except my husband.
I am so sure of the pattern that I say to someone who has mentioned a child in conversation, “Of course, he/she is like the mother (or father).” The person says, “How do you know? That’s right.” The first child is like the parent of the opposite sex and the second child is like the other parent. If this is not immediately obvious, sometimes the child resembles not so much this parent as the grandparent, but the same side of the family. It doesn’t matter how many years separate child one and child two.
Any old change
Bravo! The Reno Post Office and Rocky Mountain Institute researchers have rediscovered what their fellow countryman Frederick Winslow Taylor (1856-1915) first discovered nearly 100 years ago (This Week, 10 December).
One of the founders of industrial psychology and work study methods, Taylor found, in an experiment conducted in Hawthorne, Massachusetts, that a change in work conditions results in an increase in productivity. He went on to demonstrate that it is not only change for the better that yields results; when he changed the conditions back to their previous state, he found, to everyone’s surprise, that productivity improved again.
In fact, the increases in productivity were due to the motivating effect of the unaccustomed attention the workers received, more than the nature of the changes themselves. Does this mean that the Reno Post Office should now revert to its original lighting system?
Order anomaly
Perhaps John Negus (Letters, 10 December) should have gone just one step further in his observations on Steve Adams’s article about entropy (Inside Science No 75, 22 October) and asked about the beginning of the Universe itself.
Unless we know the whole, surely our knowledge so far should be regarded as sub judice. Who wound the clock? Who turned the hour glass over? Perhaps more significantly, who made them and put them in position in the first place?
I appreciate that illustrations are limited to the relevance of models, but if our concept of entropy is to be complete, we must know how order was first established. It is contrary to the second law of thermodynamics as it stands.
That first 10鈭�45 seconds has a lot to answer for.
Thumper was first
Apropos the courting tree frogs (This Week, 10 December), the American author Ernest Thompson Seton in his book Wild Animals I Have Known, published earlier in this century, has a story of a rabbit which gave an alarm signal to its offspring and others nearby by thumping on the ground with a hind foot.
Seton was a faithful, not a fanciful, portrayer of nature, and his description of such behaviour implies that seismic communication was discovered long before 1980.
Moreover it is known that snakes receive early warning of approaching humans (among other animals) by the vibrations of their footfalls, which could be a half-way step to using this sensitivity to convey a warning to others.