Letters : . . .
Kingston-upon-Thames, Surrey
Dan McKenzie of Cambridge’s earth sciences department has demonstrated that
the basaltic lava produced in the mantle rocks at mid-ocean ridges is released
due to a reduction in pressure on those rocks.
The impact of an asteroid hitting the Earth would have produced not only a
pressure wave from the initial shock but a rarefaction wave when the strata
rebounded, and this rarefaction wave would presumably have followed the same
path as the pressure wave.
Those pressure waves from earthquakes which intersect the Earth’s core can be
shown to be refracted to form a rough focus in the mantle, so I assume that the
same would be true of the rarefaction wave from the impact.
From all this, I suggest that the impact caused a rarefaction wave so intense
that the focused wave momentarily reduced the local pressure to a level which
brought the basalt melt out of the mantle rocks. This melt, being less dense,
then rose to the surface to create the eruption.
Letters : Media magic
Edinburgh
That science is waning and media studies waxing in the curricular sky is a
fact. But your editorial on the phenomenon (“Media studies is the message”, 24
August, p 3) might have had a more meaningful conclusion than the jocular
observation that what science teaching needs are media studies’ “clothes,
hairstyles and a few buzz words”.
Add, for example, “stimulating ideas, variety, humane methodology, and
obvious relevance to its students’ lives” if you want to find more significant
explanations for the popularity of media studies.
Essentially, media studies treats its subject not as a body of external
knowledge detached from life but as a complex human construct set within a moral
universe. Deconstructing its many messages exposes largely invisible but
powerful and ideologically motivated influences on our behaviours. Exchanging
thoughts, attitudes, experiences and expertise between teachers and pupils of
all ages becomes therefore a legitimate way of learning.
Contrasting media studies with science teaching in terms of organising
principles, methods and purposes may suggest some reasons why interest in school
science is declining.
But this decline seems quite unnecessary. Most young people understand that
our biosphere is stumbling into multiple and profound crises. They passionately
want to know and understand more, to become more engaged. Perhaps they, like
most of us, sense survival imperatives and future conditions which will require
a scientifically literate electorate that is capable of taking informed
decisions.
Yet science teaching, despite such complex needs, eager customers and a
universe of marvels and mysteries as its playground, is not attracting them.
This can only suggest a lack of curricular/political imagination of a quite
staggering kind. But the answer is certainly out there. It might well be in
media studies and its methods. So who’s for a deconstruction of The
X-Files to find out what’s really going on?
Letters : A nice cuppa
Perstorp, Sweden
The author of the patent application GB 2 293 548 admits that he does not
know why tea has a healing effect on sores caused by herpes infection (Patents,
27 July, p 22 and Letters, 31 August, p 47).
There is, however, a plausible explanation for this effect. The herpes virus
needs a high humidity to be effective and capable of multiplication. If the
water content in the tissues sinks under a certain minimum the virus becomes
inactivated.
Tea contains tannins and these have an astringent effect on the skin and
tissues. This means a reduction of the available water content in the sites
affected by the virus, with the result that the virus is made ineffective and
the sores heal.
The virus’s sensitivity to dehydrating agents is made use of in other types
of treatment. If alcohol is applied several times a day on the sores, their
healing is accelerated. In folk medicine, herpes zoster (shingles) used to be
treated with kaolin compresses, which dried out the sores. In Germany, silica
gel has been recommended for this purpose.
The suggestion of applying (strong) tea on the herpes sores several times a
day is thus quite reasonable.
Even the idea of preferring Earl Grey tea is not a bad one. This particular
tea contains terpene-rich bergamot oil and it is known that some terpenes have a
favourable effect on the healing process of skin wounds and rashes.
In principle, all herbal teas that are rich in tannins and contain terpenes
(such as peppermint or camomile) can be supposed to help shorten the healing
process of herpes sores, provided they are strong enough and applied as early as
possible and as often as possible (every hour).
Letters : Grass for worms
Petersfield, Hampshire
You state that chimps eat certain leaves as roughage to brush out parasitic
worms (New 杏吧原创, Science, 24 August, p 17). Domestic cats and dogs
daily swallow grass which they usually pass quickly in undigested tangles. They
seem to choose the longer blades, perhaps because the mechanical properties are
important or because the under-surfaces are hairier.
It seems likely that the behaviour has a similar de-worming purpose.
Letters : Plane sick
Oxford
Times have moved on since the 1988 edition of Aviation Medicine
which the professor read for his amusing piece, “The naked aviator” (27 July, p
43). Not only has there been a 1993 edition of the book, but the Aviation Health
Institute has also been established.
It is a medical research charity that promotes health and wellbeing of
passengers worldwide. Its main objectives include the investigation of the
effects of flying on health and on the course of common diseases, preventing ill
effects and increasing awareness.
Medical problems on aircraft occur infrequently, at a rate of about 1 in 10
000 passengers, but there are signs that in-flight incidents will increase
significantly over the next five years as the average passenger is getting older
and travelling greater distances.
The lack of communication between airlines and medical bodies results in lax
screening processes, particularly for passengers with illnesses. These can be
exacerbated in-flight, and in some cases a passenger’s condition can be tipped
into a critical state after the flight. Consequently, the travel insurance
industry pays out 拢50 million in health claims each year for problems
arising at destinations.
In a survey by the Association of British Insurers, the claim rate was found
to be 1 in 48 passengers who had taken out health insurance.
We have also come across two interesting cases of passengers who have lost
their driving licences as a result of blackouts while flying. In both cases,
they awoke from sleep on board only to collapse unconscious soon afterwards. The
incidents were related to their doctors, who informed the Driver and Vehicle
Licence Agency. The agency apparently does not recognise the fact that while
driving is carried out at sea level, air travel is conducted on average at a
maximum cabin altitude of 8000 metres. This results in an oxygen deficiency of
25 per cent by pressure which could have triggered off their syncope
episodes.
Letters : Medical paradigm
Blackburn, Lancashire
On 6 April (Forum, p 47) you printed an article entitled “They burn heretics,
don’t they?” This put forward the very powerful idea that science (including
medicine) is based on paradigms and not on evidence. Evidence comes later and
generally speaking will refute a paradigm.
We have within medicine a very powerful paradigm that coronary heart disease
is due to “misbehaviour”鈥攄ue to the way in which we live our lives, what
we eat and whether we smoke, and so on. But the evidence indicates that dietary
manipulation is of no benefit and therefore diet cannot be causative, despite
the paradigm.
A high cholesterol level is associated with coronary heart disease and it is
assumed that “cholesterol is toxic”. But the benefits in lowering cholesterol by
drugs are very small. The idea that a high blood cholesterol is due to diet is a
paradigm that is hard to shake.
My colleagues and I have taken a different look at the relationship between
cholesterol and coronary heart disease by trying to answer the question: “Why do
the northwestern parts of the British Isles and northern Finland have the
world’s highest incident rate of coronary heart disease?” We have explored how
climate might be involved, not as the cause but as a factor influencing
susceptibility. We have looked at sunlight and demonstrated that it might well
be involved in the metabolism of cholesterol and protection against coronary
heart disease.
I also noted your recent article “Can you catch a heart attack?” (8 June, p
38). This looks at Chlamydia pneumoniae as a possible cause of coronary
heart disease. About eight years ago, I was unable to find anyone to publish an
article that I had written entitled “Is coronary heart disease due to a
microbe?”. Once again, we are faced with a paradigm and the idea that the
disease was due to a microbe was, at the time, too far-fetched even to be
considered.
Things are now changing and your article demonstrates this. The
article mentions that C. pneumoniae is only likely to be important if
the coronary arteries are damaged by cholesterol. I believe that it is the other
way round and that the prime mover is the cause (the infection), with
cholesterol producing a secondary effect.
A high cholesterol level is only important in people who have coronary heart
disease. The problem is how do we identify the disease until a clinical event
happens?
Letters : Short surges
Helmut Zarzycki (Letters, 17 August, p 49) is a little unfair about the
British failure to protect the Europa 2 ELDO launch vehicle’s inertial guidance
system against electrical earthing problems. It is not true that nothing was
done to protect against a known failure mode.
In fact, an automatic restart capability was added (in hardware not in
software), but it did not provide sufficient protection. The design of the
protection circuitry assumed鈥攑robably unintentionally鈥攖hat any
pulses resulting from such a failure would last at least as long as the
switching time of the logic gates, which at that time was about 10 microseconds
(using 1960s technology).
Post-flight analysis revealed that several current
surges occurred in the flight computer’s earthing strap as a result of the arc
discharge mentioned by Zarzycki, but each of these surges lasted considerably
less than 10 microseconds. Consequently, the logic circuitry was hung up in an
unanticipated state.
Letters : . . .
Glasgow
Natural deer populations are kept in control by predators, disease and
competition for food.
The critical short-term change to encourage forests to manage themselves must
be to reintroduce large native predators hunted to extinction in recent
centuries. In Scotland this means the wolf, brown bear and the wild boar.
Fires are a natural process which must be tolerated. They are made much more
devastating by the small size of many areas of potentially “natural”
woodland.
A sustainable though cyclically variable level of dead-wood build-up and its
associated fire risk must be accepted. It is the same deadwood that provides the
habitat and food for many endangered species of insects and which keeps a
substantial portion of the ecosystem’s energy within the forest.
Letters : Not devastated
Peterborough
Guy Pearce raises the spectre of future forests being either eaten up by deer
or devastated by fires (Letters, 17 August, p 50). Deer are a serious problem in
our woods and, as he states, affect both ground flora and regeneration. However,
it is unrealistic (and unnatural) to expect to eliminate them totally. If,
instead, we can learn how to manage deer at low densities, they will increase
the diversity in the composition and the structure of our woods.
The fire threat may also be overstated, not least because the public does not
have unrestricted access to forests. Conifer woods and plantations are at risk
but closed-canopy broad-leaved woods do not burn well at all. It is in these
that an increase in deadwood and old trees would most benefit the conservation
of invertebrates and fungi.
Recent surveys suggest that our managed broad-leaved woods have only about a
tenth of the fallen wood found in undisturbed near-natural stands, so there is
plenty of scope for an increase. It is even possible that if there were more
fallen branches left on the forest floor, there might be more opportunities for
seedlings and saplings to grow up without attracting the attention of deer.
Letters : Mobbing the mag
While reading the 24 August issue in the open air last week, I noticed a very
peculiar phenomenon.
I was aware of a group of insects hovering around a shrub near where I sat.
Not having any training in entomology, I cannot identify the species, but they
were like half-size wasps, and they had the ability to hover absolutely
motionless.
Anyway, when I opened the magazine to read the contents page, the insects
absolutely mobbed me, seemingly interested in the yellow area of the “Planet
Science” advertisement inside the front cover, the part where your Web address
appears.
I tried to shake them off, but they hovered resolutely above the yellow area.
Finally, I turned the page, and they immediately flew off and showed no further
interest. We examined the page under UV to look for fluorescence, but found
none.
Letters : Double whammy
Isle of Mull, Argyll
In his comments on The Great Dinosaur Extinction Controversy, Bob
White hedges his bets by suspecting that meteorite and volcanic activity both
played their part in the demise of the large dinosaurs (Review, 10 August, p
42). If two rare events of such massive proportions occurred “at exactly the
same time”, as he says, might they not be connected?
At the time of the Cretaceous-Tertiary boundary, were the Mexican crater and
what was then the island of India in antipodal positions to each other? If so,
could the seismic disturbance from the meteorite impact have been sufficient, on
arrival at the opposite side of the world, to trigger the eruptions that
resulted in the Deccan Traps?
Letters : Organic origin
Padua, Italy
Ruth Paradice, a British psychologist, suggests that postnatal depression is
a form of grieving for a lost lifestyle (This Week, 20 July, p 7). As has
recently been shown (May issue of Journal of Clinical Endocrinology and
Metabolism, p 1912), postnatal depression is simply due to the central
suppression of hypothalamic corticotrophin-releasing hormone secretion during
the postpartum period.
In his recent essay “Burying Freud” (The Lancet, 9 March, p 669),
Professor Tallis appropriately points out that “Psychoanalysts have frequently
imitated their master in attributing to psychological causes serious illnesses
that have organic origins, with often fatal consequences.”
Letters : Stud granddads
Fort Wayne, Indiana, US
I read with great interest Stephen Budiansky’s feature, “Don’t bet on faster
horses” (10 August, p 29), on the lack of improvement in racehorse performance.
His quick mention of the improvement of the performance of standard-bred horses
overlooks one likely explanation.
Unlike their Thoroughbred equivalents, the standard-bred breeders have
finally begun to return to the original principles of breeding. To achieve
gains, one must line breed (cross with a relative such as a grandparent, but not
to a sibling or parent) and occasionally even inbreed. This is anathema to
Thoroughbred breeders; I have even seen horses with two crosses to the same
individual in the 6th generation referred to as being inbred.
When standard-bred breeders returned to line breeding, the racing times
started to come down.
Letters : Source of sneezes
De Punt, Netherlands
A very interesting and, for me, quite new view on hayfever was given in
your article about the expected increase of fungal spores as a result of
doubling the level of CO2 in the atmosphere (This Week, 24 August, p
5).
We are told that “the air in the CO2-rich chambers was thick with
spores鈥攋ust like those that cause allergic reactions in millions of
people”.
In the classic textbook Pollen Grains by R. P. Wodehouse, there is a
chapter about hayfever in which he talks about the plants that cause it. The
word fungi is not mentioned once.
Both pollen grains and fungal spores have walls composed of sporopollenin, a
durable organic polymer that contains proteinaceous matter. Proteins in pollens
are supposed to cause allergic reactions. So fungal spores could in theory cause
hayfever.
Can anyone tell me whether the assumed cause of hayfever has shifted from
plant pollen to fungal spores?
Letters : . . .
It would appear that the only hope for radio astronomy is to set up receivers
on the Moon, clear of the interference from the proposed global network of
cellphone satellites. But how to pay for this expensive project?
The answer is obvious: blackmail. A few years of using the world’s radio
telescopes to eavesdrop on indiscreet cellphone conversations should easily
provide enough saleable material to cover the costs of a few trips to the Moon
and the necessary construction work. And should there be ethical objections to
such a scheme, radio astronomers can claim the moral high ground. What could
possibly be fairer than asking the polluters of radio astronomy to pay for its
relocation?
Letters : Sky farmers
Chislehurst, Kent
Referring to your article “Are we killing astronomy?” (24 August, p 28), I
thought I might tell you a story of a village in southern England where there
aren’t any streetlamps. It’s a very attractive village. Recently, some newly
moved-in retired persons put before the parish council a proposal to make the
place more like what they’d just paid good money to move out of, by installing
streetlights.
The idea was rejected by a large majority because the residents would not be
able to see the stars; and secondly, you could put them in, but couldn’t stop
resentful citizens taking them out with air guns, tractors, or whatever was
needed.
There still isn’t a streetlamp within ten miles, you can still watch the
Milky Way evolve when the Moon is down, it’s still the best place to camp in
England, and I’d be mad to tell you where it is.
The point is, these people aren’t astronomers, just farmers and the like.
They are very clear about not wanting their celestial observations mucked about
with. A lot more places could follow their example.
Letters : Falling sideways
Address not supplied
Has anyone else spotted the deliberate mistake on p 20 of the 17 August
issue? The three photographs of the block of flats being demolished are all
sideways. And if they were meant to be looked at side-on, then their order
should be reversed. Gremlins in the works?