Letters : A problem addressed
Bristol
Quite a few ideas have been proposed recently to make it possible to
purchase items on the Internet using credit cards. Some include special
passwords that the bank and customer have, and there are various other more
complicated ideas.
Why has no one thought of having some kind of system where the credit card
number incorporates the address of the customer? This would, admittedly, mean
that the customer could only receive mail-order goods at one address, but also,
computer hackers could only buy goods which would be sent to the address of the
customer.
Letters : Better by half
Colombo, Sri Lanka
I seem to be the victim of a typographical conspiracy. You have rendered
my first sentence (Letters, 9 March, p 53) meaningless by leaving out the “陆”
in “GMT + 5陆 hours”.
And last week the local Sri Lankan papers omitted the initial “s” in
“slowest” when I repeated the old joke that “cricket is the slowest form of
animal life”. Only swift damage control saved me from joining Salman
Rushdie.
Letters : Dicing with grants
Hamilton, Canada
Alan Camina’s suggestion that peer review selection of grants could be
replaced by a random lottery has a good track record (Letters, 2 March, p 49).
Doges in Venice were appointed by a random draw from the pool of eligible
candidates (and Venice did not do particularly bad in the course of history).
Imagine the American presidential election by a random draw from a few
finalists. Political campaigning would probably be more healthy, constructive
and cooperative and much less loaded with false promises.
Jonathan Swift in his immortal Gulliver’s Travels provides a
description of an “idea generation machine”. By rotating cubes with scientific
terms written on them, scientists in Laputa produced various combinations of
ideas for their academic contemplations. Recently the role of randomised
stimulation (a kind of conceptual analogue of a Tarot deck) was emphasised by
Edward De Bono, a writer on human creativity. One may also recall an earlier
bestseller, The Dice Man by Luke Rhinehart, where the protagonist made
all the decisions by tossing a dice.
A random grant system would be enormously cheaper to run than the present
funding bureaucracy. And in terms of results it will probably be better, not
worse, than the present highly selective (and hence equally arbitrary) funding
system. At least a random model is free from the conformist pressures
characteristic of any peer review system. Innovative research has better chances
in a random system than under the pressures of a peer review mechanism.
To avoid the extremes, the applicants, of course, should satisfy criteria
based on their credentials and track record (no need for in-depth peer review to
establish this) and random awards should vary in amounts in such a way as to
avoid zero funding for an active research programme. Let’s give this system a
try.
Letters : Sounding off
Milton Keynes
The Recording Industry Association of America has proposed the BBN system
for adding coded information about copyright to music CDs (Technology, 2 March,
p 22). Some of us try to reproduce music from CDs and other sources as
realistically and as close to the original performance as possible. One of the
great things about CD is its potential 90-plus decibels of signal-to-noise
ratio. Now along comes BBN to reduce this to 19 decibels, right across the
middle of the audio frequency band.
Some years ago, the equally ridiculous Copycode system was rejected because
it quite audibly ruined sound quality. Let us hope this updated version will
suffer a similar fate. After all, why go to all the trouble of developing
high-quality systems such as CD only to throw away their quality advantage? We
might just as well have stuck with a cheap analogue cassette-playing system.
Letters : …
Washington DC
As Barry Fox correctly states, the “spread spectrum” code signal uses
psychoacoustic masking to ensure that the code is inaudible when added to music
signals at low levels. The result of this process is that the code signal is
very similar in character to the accompanying music鈥攕o similar, in fact,
that if the code is listened to on its own the associated music is easily
identified.
Consequently, when the encoded music is subject to sound-compression systems
also employing psychoacoustic techniques, the embedded signals are not
distinguished from the audio and are transmitted unharmed.
Communication theory states that the embedded energy is nearly ideally
matched to the channel and is of minimum entropy. It is therefore very difficult
to separate it from the audio signal by any process. Tests with different
encoders have confirmed this result. Furthermore, the code signal survives
processing by multiple codecs.
My second point concerns high-quality analogue-to-digital converters, which
give very low noise levels, such as 20 to 22-bit PCM units or the new Sony
Bit-Stream device. The BBN signals survive such methods because the
code-to-music ratio of minus 19 decibels is maintained down to the noise-floor
of the digital system. One can regard the noise-floor as a random “music” signal
with well-known statistics, and the psychoacoustic coder has the rather easy
task of ensuring that the buried data signal has the same spectral content. The
decoder also has an easy task since the “music” (in this case noise) has a very
low correlation with the wanted embedded signal.
Therefore the decoder can operate with a greater discrimination threshold
than would occur with some forms of music that may intermittently have a higher
correlation with the embedded signal. Far from being a problem, high-definition
or high signal-to-noise ratio systems benefit from the signalling methodology
employed by the proposed RIAA/BBN system without significantly altering the very
low background noise level.
Letters : Loopy electrics
Newbury, Berkshire
I share D. W. Mullard’s concerns (Letters, 16 March, p 58) about Vincent
Kiernan’s explanation (Technology, 17 February, p 23) of the way in which
electricity might be generated by a satellite-on-a-string. To induce electricity
one needs an inductive loop not a single wire.
However, it struck me that Kiernan was wrong and the power was being
collected from the flux of charged particles radiating from the Sun, which would
constitute an electric current. The satellite-on-a-string merely plugs into two
points on the voltage gradient. This would be like Benjamin Franklin’s classic
experiment in which he flew a kite from a metal wire in a thunderstorm. No drag
would be caused.
Letters : …
Harlow, Essex
Mullard suggests that taking current from the cable would cause drag and
the consequent re-entry of the satellite, I have an even more fundamental
problem. How is it possible to take direct current from a single wire? Surely a
loop is necessary? Is the “cable” actually a narrow loop鈥攐r what?
Watch out for an article on this topic in the near
蹿耻迟耻谤别鈥抬诲
Letters : Morse market
Watford, Hertfordshire
I strongly suspect that the denigration of Morse code is the work of
certain people with vested interests (Technology, 20 January, p 20 and Letters,
9 March, p 53 and 17 February, p 50). What they are actually after is the
wavelengths used, as these can be sold to communications companies (pager and
mobile telephone services) at great profit, with highly paid directorships being
a further reward at a later date.
Letters : Forest first
Hillhead, Glasgow
I was dismayed to read your article about the closure of the Iwokrama
International Rain Forest Programme in Guyana (This Week, 9 March, p 10). As the
organiser and leader of an undergraduate expedition to the forest in 1995, I
experienced this model programme at first-hand. The views and aims of the
programme are nothing short of revolutionary in terms of whole-system management
and it was hoped that the programme could be used as a model for future
rainforest management programmes in Guyana and abroad.
A brief letter cannot do justice to the experiences of the 13 people on this
expedition, but our project aims and the diversity of forest types, waterways
and savannah we encountered, as well as wonderful encounters with local
Amerindian people, all made this a unique and unforgettable experience.
I must contradict the point made in the article that the field centre is
plagued with malaria. Malaria is present but the centre is perfectly well
equipped to prevent and deal with the disease, with permethrin-impregnated
mosquito nets over all the beds, a microscopist at hand for weekly blood tests
and a medic to administer drugs in the event of anyone contracting the disease.
Evacuation is also no problem with an airfield just an hour away.
It would be a tragedy if this programme were allowed to fold. Lack of cash
seems a totally unjustifiable reason in the light of the programme’s potential
achievements. Ivan Anderson (the contracted British scientist who helped arrange
our visit) hints that the programme may survive if certain measures are taken. I
would therefore urge those involved with the funding of the programme to get
things rolling faster and would encourage potential funders or investors to look
into the possibility of becoming involved. This is a golden opportunity for
anyone interested in tropical rainforests or their products to obtain good
results in a region with excellent facilities.
As a token towards increasing the general awareness of the programme I would
like to make copies of the Glasgow University Guyana ’95 Expedition Report
available upon request. To obtain a copy please send an A4 SAE to Dr R. Downie,
Department of Environmental and Evolutionary Biology, IBLS, University of
Glasgow, Glasgow G12 8QQ.
Letters : Slick work
I am writing in response to your editorial and news item about oil tanker
disasters (2 March, pp 3 and 4).
In both articles it was either stated or implied that salvors operate on a
“no cure, no pay” basis. Although in principle this is correct, it must be said
that the modern Standard Form of Salvage Agreement (LOF-95) contains a clause
relating to an actual or imminent pollution incident. This allows the salvor to
make a claim for compensation when it has used its “best endeavours” to prevent
or minimise damage to the environment that may be caused by the escape of any
pollutant from a vessel. This compensation will cover all reasonably incurred
expenses and a “special compensation” may also be awarded of up to 30 per cent
of the total expenses. This may be increased to 100 per cent by a tribunal.
The main reason for the inclusion of this compensation clause was to ensure
that prompt action would be taken by the salvor to limit environmental impact
from an incident and only then consider the “no cure, no pay” aspect of salvage
agreements.
Why this appears to have failed in the case of the Sea Empress will
undoubtedly be revealed in the official inquiry, the findings of which I believe
will be a correct report based upon the known facts (judging by the Marine
Accident Investigation Branch’s record to date). What action, if any, the
government choose to take will, I hope, be more positive than their track
record so far indicates.
Name and address supplied
Letters : Down to earth
Newbury, Berkshire
I must admit to being somewhat sceptical of Denis Henshaw’s conclusions
about the hazards of radon and electrical fields, as described by Claire O’Brien
(This Week, 17 February, p 4). I have always understood from textbooks that
alpha particles do not penetrate very far and are mostly stopped by the
epidermis of the skin.
On the more positive side, however, while still being doubtful about the
evidence, it might be a good public relations exercise for the National Grid to
sling earth lines below the lower conductors on power lines (which presumably
are responsible for most of the field at ground level) in residential and
industrial areas. Such lines being at earth potential would screen off most of
the field at ground level. Unfortunately the neutral line, which could otherwise
be useful in this respect, is usually slung from the apex of the pylons. Is my
reasoning correct?
Letters : Coal in the sky
Great Wakering, Essex
I thought that you might be interested in the German proposals at the end
of the Second World War to use coal as a fuel in high performance aircraft,
which, while experimental were certainly scientific fact, not fiction (Letters,
3 February, p 56, 2 March, p 50, and 23 March, p 64). The proposals must have
stemmed from the oil shortage of the latter years of the war, which as your
correspondent Richard Courtney points out, affected German defence capabilities
to an enormous degree.
Information on the plane can be found in standard reference works on
Luftwaffe jets and experimentals, but the best source is German Jet
Genesis by David Masters published by Janes in 1982.
Coal was to be used to fuel a ramjet engine for a supersonic fighter plane
called the Lippisch DM P13a designed by the noted engineer and scientist
Professor Lippisch who also designed the engine fuelled by brown coal
(presumably lignite?). I am unsure as to how far the engine design progressed,
but the tiny delta winged aircraft had a triangular tail fin into which the
pilots cockpit was built. He sat above the ramjet and also had a rocket engine
for take off and to achieve the required ignition speed of the ramjet. Wind
tunnel work was well advanced and a smaller unpowered glider of the same
planform was almost complete. This was captured by the US Army at the end of the
war.
From what I can gather from Masters’s book, the coal particles would have
been suspended in the airflow and rotated, then ignited by a gas flame. The
resulting heated gas would produce thrust to propel the plane at supersonic
speeds. Other planes were also to be powered by the ramjet.
Letters : Tomato trivia
Sevenoaks, Kent
In your editorial you say the public might be frightened if they are told
that a food product is genetically engineered (9 March, p 3). But a recent
problem arose because the public was “protected” from the truth about government
guidelines on arms sales. (Maybe in some cases the food is not genetically
changed, but only genetically “relaxed”.)
When attempts are made to “reassure the public” this usually implies that the
scientist is on the side of the producer against the consumer. This is usually
true, (a) because the producer provides the scientist’s job, and (b) because the
scientist is often developing a product that’s looking for a market. In the case
in question, when the drum roll fades out and the smoke clears, the public is
supposed to be staring spellbound at Marvo the Magician unveiling three small
but perfectly formed genetically engineered tomatoes.
As a purchaser, I have no problem with existing tomatoes and tomato paste. It
is the producers’ and retailers’ problem, and I have no incentive to do them the
favour of buying a genetically engineered product.
What society really wants, whether consciously or not, are things like a
Dorian Gray tablet to get rid of old age, or a matter transmitter to deal with
excess traffic. Science cannot provide these (whether through lack of funding or
simple impossibility), so it gives us funny tomatoes and a cooking oil that is
all fart and no fat (This Week, 25 November 1995, p 10). Of course this isn’t
the responsibility of “science”. But the science establishment does tend to be
on the side of trivial progress. Newton and Pasteur would turn in their graves
on learning that scientists were employed to make food less nutritious.
On TV programmes one can easily distinguish between the tame scientist
(fenced in by the corporation) and the wild scientist (rampaging around the
campus). We need more wild scientists and less genetically engineered pap.
Letters : Engineers nil
Cambridge
I was appalled to read Alan Gamble’s views on engineers (Letters, 16
March, p 59). He referred to the description of William Hawthorne as “an
engineer from the University of Cambridge” as “disparaging 鈥� you make him
sound like the assistant caretaker”.
The Concise Oxford Dictionary defines “engineering” as “application
of science for the control and use of power, esp. by means of machines”. Surely
Hawthorne’s work on gas turbines and his contribution to the early development,
with Frank Whittle and others, of the jet engine, makes him exactly
that鈥攁n engineer.
While the status of engineers in Britain, in contrast to most other
countries, is so devalued, there is little chance that the brightest people will
become “wealth creators”. The perpetuation of this view, as exemplified in this
letter, is deplorable. It can only lead to Britain continuing to lose out in the
international economic arena.
Letters : Flawed sight
Gloucester
The Office of Science and Technology’s “Foresight 2000” poster given to
subscribers with the 16 March issue of New 杏吧原创 was, I feel, very
revealing. Is it really the case that when selecting the 34 people to lead such
an initiative there were only two suitable women and no one other than white
Europeans? I believe this shows tunnel vision not foresight.
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With the poster’s miniatures of 32 men and 2 women, all moulded in
corporate images and all looking more than 40, is it any wonder that the young,
and women in particular, are turning away from science and technology as a
potential career?
This is one we shall keep as an example of the semiotics of science and
technology, not as an example of informing the public about what these people
will actually be doing.
Mick Nott and Di Bentley
Sheffield Hallam University
Letters : Mass observation
We read with interest your article on radiation safety limits (This Week,
2 December 1995, p 10), which quotes Maurice Tubiana of the French Academy of
Sciences as saying: “Studies [to determine what levels are safe] can be carried
out in a few years.”
The Centers for Disease Control and Prevention is evaluating workers and
communities exposed to elevated levels of manmade radiation. Another way to
study radiation health effects is to investigate large cohorts of individuals
exposed to differing levels of natural background radiation (which increases
with altitude).
Pochin (Health Physics, vol 31, p 148) has estimated that 10 000
people exposed to an increase in annual radiation dose of 5 millisieverts would
need to be observed for 56 years to detect even a change in mortality risk as
large as 7 per cent. But Pochin’s example has limited statistical power. To
increase this power, it would require a sample size of 100 000 and 35 years of
observation to detect such a change in risk. To detect a change in risk as small
as 1 per cent, six million persons would need to be observed for 30 years.
Thus, studying small relative risk changes associated with low levels of
radiation exposure will require a very large cohort exposed to background
radiation as great as 5 millisieverts per year. Finding such cohorts will be
difficult because most humans are not naturally exposed to these levels.
Worldwide, only about two million people live in six cities above 10 000 feet
with background exposures of 3 to 4 millisieverts per year.
Large sample size
increases may not be sufficient for evaluating small changes in risk, however,
since confounding factors and misclassification become more problematic.
With current study designs, Tubiana’s above statement may be valid for
detecting large changes in risk, but not smaller changes, such as 5 per cent or
less. In future, alternative study designs or better methods for measuring
exposures and outcomes could possibly reduce the resources and time required to
detect such small differences.