Letters: Thick-skinned
Q: I have heard that the entire skin of a human is completely replaced
over a period of between three and six months.
If this is the case, why is it that tattoos can last for so long without
fading or vanishing completely?
Donald Angell Bristol
Letters: Spilt thrills
Of course science is interesting, but I do not know if science as taught
in school is very good at fostering curiosity and excitement in students.
I find this distressing. Science should be enjoyable and exciting. How best
to convey this message to pupils in our schools will, I fear, continue to
be one of the most challenging problems in secondary education. I still
think the media are largely to blame: science is still perceived by too
many people as being unconnected with ordinary, everyday living.
Children in primary school typically find science very exciting. They
are increasingly exposed to computers and other technology from an early
age, and yet so many teenagers see science as the domain of ‘spods’ and
‘nerds’. I do not know what goes wrong between the ages of 7 and 14.
Andrew Breeze University of Cambridge
Letters: Spilt thrills
Whoever keeps proclaiming that ‘science is fun!’ sounds like a desperate
mother telling her child that the dentist’s is a happy place. It isn’t necessary.
We don’t hear ‘History – guaranteed to make you chuckle’, or ‘Joy and frolics
in economics’.
A science degree is rewarding, fascinating, imaginative, and can lead
to almost any career. But to enrol more students at A level, the subjects
need to be more lively (Comment, 2 April). Why are there no communication
skills on the science syllabuses? The possibility for debates and essays
is strong, and yet it is easy to go through two years without ever being
asked to voice an opinion. The history of science can be fascinating, yet
just a few names and dates are given at the start of each topic.
This dryness is scaring away the outgoing pupils, and turning science
into an escape route for the quieter types. The only way to reverse this
trend is to provide an exhilarating course, not hands-on contraptions.
James Ockenden, University of Cambridge
Letters: Premature
I would like to add some comments to the article by Jonathan Beard (‘How
lungfulls of liquid can save a tiny life’, 19 March) about ‘ventilating’
premature babies with an oxygenated liquid perfluorochemical. This is potentially
a very valuable technique as it eliminates the need for damaging high gas
pressures and high oxygen tensions (which can cause oxygen toxicity). The
new technique does not, however, completely replicate the situation in the
fetus as stated in the article.
Based on data from sheep, our understanding is that the lungs of the
fetus contain a fluid which, like fetal blood, has a rather low oxygen tension.
The fetal lungs contain 35 to 40 millilitres of this liquid for each kilogram
of body weight.
A common misconception, repeated in the article, is that the lungs contain
amniotic fluid. The lungs actively secrete their own fluid (essentially
sodium chloride solution) which is either swallowed by the fetus or flows
into the amniotic sac. Due to a valve-like action of the upper respiratory
tract of the fetus, amniotic fluid rarely enters the lungs, unless the fetus
is deprived of oxygen and begins gasping. If amniotic fluid enters the lungs,
it may impair the production of surfactant, which is necessary after birth
for lung expansion.
In fetal life it is highly unlikely that oxygen is taken up by the lungs
because the oxygen tension and oxygen content of ‘lung liquid’ is low and
there is very little blood flow through the lungs. Once the baby is born
and is exposed to atmospheric oxygen, blood flow through the lungs greatly
increases, allowing gas exchange to take place. The new technique will only
be effective if this increased blood flow has occurred.
Richard Harding Monash University Australia
Letters: Basqueing in it
I was somewhat surprised to read in the report ‘DNA survey sets Basques
apart’ (Science, 19 March) that earlier views based on archaeological discoveries
have now been reinforced by genetic evidence. The genetic basis of this
distinction was surely well known 40 years ago, when A. E. Mourant wrote
his book, The Distribution of Human Blood Groups (Blackwell Scientific
Publications, 1954).
The abnormally low B gene frequency and the abnormally high d gene frequency
were both already well documented when this fine book was written, Mourant
drawing special attention to Etcheverry’s paper of 1945 on the ‘uniquely
high d frequency’ in the Basques. It was on account of these genetic differences
that set the Basques apart that some of us in the 1950s used to refer to
them as the Protoeuropeans.
J. Gillett London School of Hygiene and Tropical Medicine
Letters: Getting it taped
Re ‘tape resurrection’ (Technology, 5 March and Letters, 26 March):
we have had the problem of magnetic tapes with the older polyurethane coating
degenerating to such a stickiness that they simply jam in the machines.
We have already tried James Watson’s method, using isopropanol, which only
worked for us on short runs of moderately degraded samples.
There is another method, though it is somewhat anti-social. We cooled
the heads with a liberal quantity of CFC and then sprayed the incoming tape
on the base side as the machine was run. This freezes the magnetic coating
to a solid that reproduces as normal, for a while anyway. Even in a room
with artificially reduced humidity this causes a build-up of ice around
the deck.
For long runs, we made a housing of foam polystyrene around the works
and fed it with dry nitrogen that had been chilled in a copper tube coiled
through a freezer. This works a treat. I guess any source of dry cold gas
would do quite as well – though I can’t recommend propane!
Ron Hibberd Leichhardt, NSW, Australia
Letters: Fuel controversy
Re: ‘Alloy takes the shuttle to a higher plane’ (Technology, 19 March).
Wrong. The external fuel tank is not recovered. It either burns up in the
atmosphere or crashes into the Indian Ocean. It is the solid fuelled rocket
boosters that are recovered in the Atlantic. These are the ones you see
on TV dramatically deploying from the shuttle.
Barry Gray Wirral, Merseyside
Letters: Useful razor
William of Occam and his famous razor have had a good run lately, which
is a remarkable achievement for a child of the 13th century. Unfortunately
Colin Tudge’s contribution, ‘The blunting of Occam’s razor’ (Forum, 19
March), misses half the point and omits the delightful contributions of
William Jefferys and James O. Berger’s ‘Ockham’s Razor and Bayesian Analysis’
in the January-February 1992 issue of American 杏吧原创. Readers should
refer to this article for a sound rebuttal to Tudge’s assertion that Occam’s
razor is not statistically oriented.
Tudge’s final assertion is: ‘The Universe does not have to be simple.
Occam’s is a rule of thumb – no less, no more. It does not carry the weight
of law.’ He is wrong. Occam’s razor is the basis of science. It is not an
assertion that the world is simple, it is an assertion that if two alternative
theories explain the same phenomenon, the simpler theory is the more useful.
Scientific assessments must therefore meet two criteria – simplicity
and utility. Tudge implies in his article that utility is the basis for
rejecting Occam. A ‘brilliantly simple explanation of a living system based
on clean and logical engineering principles is likely to be wrong – if not
in outline, then certainly in detail’. Straw men are easily knocked down.
But it is better to be useful than to be true. Einstein is closer to
the truth than Newton, but more often Newton is good enough. Occam’s razor
says use Einstein only when he is more useful.
Ronald Hagen Dhahran, Saudi Arabia
Letters: Nursery skills
As an occasional reader of New 杏吧原创, I found your Comment of 5
March interesting and positive except for one sentence, but what a sentence!
So universities have ‘a ready supply of students who could run creches’
and that is supposed to be a forward-looking, innovative way of attracting
and keeping women members of staff (scientists or not).
Good quality childcare is essential if parents (not just women) are
to be able to concentrate on work without wondering how their offspring
might be faring. It requires committed, well-trained staff, suitable, well-equipped
premises and the kind of continuity that certainly does not come from a
succession of students possibly thinking about the next essay or last night’s
sessionin the pub.
Since good childcare is expensive, we have to take seriously the view
that caring for children is not an individual responsibility but a collective
one, that parents have a right to work, and that we will all benefit from
paying the price in taxes to fund good social childcare through local authorities.
Until that day comes, universities or other employers who decide to
provide childcare for their employees must do so on a properly organised
basis and not in the ad hoc way that your article suggests.
Margaret Levy Newcastle upon Tyne
Letters: Spilt thrills
You hit one nail right on the head when noting that ‘scientists themselves
are partly to blame for the perception’ that science is not a good career.
But to ‘communicate . . . the thrills of a life in science’ will be hard
if the first thrilled scientists many students meet are their university
lecturers. Too few of these remain thrilled by their lives in science. Until
this problem is resolved, I fear the thrill (which is real and communicable)
will remain uncommunicated.
Hugh Torrens Madeley, Crewe
Letters: Up the Antipodes
I must protest at another case of hemispheric bias in New 杏吧原创.
For years Australian readers have endured references to cold northerly winds,
wintertime Christmases and the North v South debate, where the southern
hemisphere is supposedly poor. Why, Australia is so rich we recently exported
a multimillionaire, Christopher Skase, to Spain to redress the hemispheric
fiscal balance.
Now we have Nicholas Humphrey (Letters, 19 March) proposing an analogy
wherein the hands on our internal clocks would rotate clockwise if they
evolved from cutaneous sundials. I have just looked out of the window and
yes, the sun is moving anticlockwise, just as it has always done.
Clearly, Humphrey’s analogy must allow opposite rotations in opposite
hemispheres. What then, of the internal clocks of children born to parents
who evolved in opposite hemispheres? Presumably, severe horological schizophrenia,
or, more likely, given the recent proliferation of electronic gadgets, a
Lamarckian digital display.
Mark Yandle Millmerran, Queensland Australia
Letters: Smart sidestepper
Q: Why and how do crabs walk sideways?
Jennifer March (aged 10) Tring, Hertfordshire
Letters: Round the twist
Q: I have often observed defects, or knots, in helical telephone cords.
The areas to either side of the defect show opposite helicity (see figure).
Strangely enough, there is often only one such defect in the cord, although
two defects, enclosing one anomalous region, would be expected. It takes
a considerable effort to untangle the cord, which seems to be the only way
to restore uniform helicity.
How do these defects happen and how can they occur spontaneously during
normal handling of the telephone?
Jan Stumpel Tokyo
Letters: Light fantastic
Q: Why does the filament in a standard household light bulb start glowing
when it is put into a microwave oven (and the oven is turned on).
Ulf Johanson Lund, Sweden
Letters: Coloured bloomers
Q: There seem to be four main colours of flowers: white, red, blue and
yellow.
Why is it that many types of plant which flower early in the season,
such as mimosa and forsythia, can only produce yellow flowers, while other
plants, such as roses, tulips and crocuses, produce flowers that appear
in more than one colour?
A few plant species, such as violets and freesia, even manage to produce
flower varieties in all of the four main colours. How can some plants do
this, while others cannot?
Jan Baurdoux Soest, Netherlands
Letters: Stirring stuff
Q: What is the significance of James Bond’s famous phrase ‘shaken, not
stirred’?
Is there really a difference in the taste of a shaken vodka martini,
as opposed to a stirred one? And if there is, why?
Mark Langford Stockport, Cheshire
Letters: Ready to roll
Here is our final week of questions before we launch the first full
page of answers in next week’s issue. The new column, which will be called
The Last Word, will then take its place on the inside back cover of the
magazine, opposite Feedback. Don’t miss it. In the meantime, please keep
sending us your answers to questions we have already published and any more
questions based on your observations of everyday scientific phenomena. We
have had a marvellous response already but more questions are welcome. Authors
of all published answers will receive a 拢10 book token.
Letters: Relatively late
I note with interest the advert in New 杏吧原创 (2 April) for astronomy
courses at Queen Mary and Westfield College, starting in September 1993.
Presumably mere attendance at the examination in July 1992 on Jupiter
will suffice to earn a Merit in the Special Relativity module.
Trevor Barker Ilford, Essex
Letters: Up the Antipodes
We Kiwis continue to lead the Commonwealth. First atop Everest and to
the South Pole, first with women’s suffrage – 1893 – and in 1993 first again
with a woman president of the Royal Society of New Zealand, in the person
of Philipa Black, professor of geology and associate dean of science at
the University of Auckland. And with The Piano, our women picked up three
Oscars – one, Anna Paquin, starting at a tender age. The ‘gentlemen’s club’
could do worse than look to the Antipodes.
Max Purdie Auckland, New Zealand