Letter: Disappearing data
The thrust of Robin Harbour’s article (Forum, 3 September) about the
dangers of relying only on computer data archives is surely correct.
However, I do not think he covered one danger, which is the rapid obsolescence
of data storage systems.
If you needed to read directly from disc something written on a computer
system of 25 years ago, it is most unlikely that you could do so; similarly,
from the tapes of that period.
Of course, when systems are upgraded, the data then archived can be
copied to the new system, but the prospect of this process continuing indefinitely
for all new data created is not realistic.
The hope of keeping paper copies is not all that optimistic either.
Apart from the problems of storage, and the risk of fire and flood, unless
expensive archive-quality paper is used, the chances of it being readable
much beyond 25 years are low.
Although our generation produces a lot of ‘information’, we may not
leave as much of it for posterity as we might imagine.
Mike Ellwood Abingdon, Oxfordshire
Letter: Disappearing data
Robin Harbour says ‘(In) a nuclear war. . . Bang would go the Internet
and similar systems.’ The Internet was designed around 1964 in its first
incarnation as ARPANET, specifically to survive a nuclear attack. Since
no node of the net is ‘at the centre’, huge chunks of the global i-way could
be blown apart, and the geeks of the world would still be able to e-mail
New 杏吧原创.
Brian Ewins Glasgow
Letter: Light on Einstein
Regarding John Gribbin’s article ‘Do photons really exist?’ (New 杏吧原创,
Science, 20 August), I would like to remind readers of Einstein’s lecture
on 21 September 1909, reproduced in Physikalische Zeitschrift. After a query
by the chairman, Max Planck, Einstein ‘replied that he never looked upon
light quanta as independent particles but only as singularities in a wavefield’.
It is a greater problem that the mass energy equivalence assumes a corpuscular
view of light and, as Einstein pointed out in this Salzburg lecture, the
Planck formula makes wave and quanta inseparable.
A. Hansson London
Letter: Support the support
Articles on science education in schools and colleges fail to mention
or recognise the importance of technical support.
‘Teachers are suffering from low morale, compounded by antiquated laboratories,
overloaded curricula and a lack of opportunities to top up their skills’
(This Week, 20 August). This comment could also be written about science
technicians in schools.
Often it is the technician who has to make, repair, borrow or adapt
equipment. The National Curriculum has increased the amount of science taught,
with greater emphasis on class practicals and open investigations. Teachers
are now teaching outside their own disciplines, while technicians are servicing
all three sciences, as well as electronics and often computing.
Nationally, provision of technical support has not increased with these
demands, grading has not been reviewed and training is almost nonexistent.
Provision of adequate technical support, which has a career structure,
up-to-date training opportunities, possibly specific qualifications for
the job and a reasonable financial reward and status, is essential for science
education in schools. School science technicians are an invaluable asset
in providing quality teaching of science.
Joyce Dalton Bristol
Letter: Teamwork
You report the detection of a nearby spiral galaxy lying behind a highly
obscured portion of the Milky Way (This Week, 27 August). I understand that
the article as originally submitted by your correspondent Govert Schilling
did mention the names of the Dwingeloo Obscured Galaxies Survey team, but
that the final editing led to their removal. The members of the team include
R. Kraan-Korteweg, Groningen University; A. Loan, O. Lahav and D. Lynden-Bell,
Cambridge University; P. Henning, University of New Mexico; H. Ferguson,
Space Telescope Science Institute; and myself.
W. B. Burton Leiden University Observatory The Netherlands
Letter: Coppice crops
The problem of harvesting short rotational coppice (SRC) can be achieved
by the use of a converted maize harvester (Thistle Diary, 20 August). This
machine cuts the crop and chips it, all in one operation. The machine is
usually standing idle in February, the time of harvesting, and its large
wheels could cope better with the land which can be very wet at this time.
The chips produced by a maize harvester happen to be the best for use in
the combined heat and power generators that are currently being developed
by both Bob Talbott of Staffordshire (100 kilowatt) and Border Biofuels
in Berwickshire (5 megawatt). The machine suggested in the report is much
more labour intensive. Murray Carter of Ripon is experimenting with planting
and harvesting machines developed in Sweden.
Despite a ‘fanfare’ of publicity in the Department of Energy’s own Renewable
Energy magazine, of the five farmers to be involved in trials of SRC, I
am told that most have abandoned the idea. I am given to understand that
the grant aid they received made them unable to claim the set-aside grants,
which made them no better off.
SRC on farmland may in any case not be the answer, especially when
with the first year cut back, the first crop is not available for four years,
and then every three years after that. In the current economic climate both
the farmers and the banks require much quicker returns than this.
I read with interest about the support from the ministry. My own attempts
to gain funding for field trials of SRC on coal spoil have met with no
more than 50 per cent support from the Energy Technology Support Unit,
and then only for a plot no greater than 0.9 of a hectare. It is most likely
that I will have to fund my own experiments.
Melvyn Rutter Leeds
Letter: Written records
I was interested to read about the current success of the government
in getting 80 per cent of family doctors to hold their records on computers
(Technology, 27 August).
You do not quote where this information comes from, but I am sure it
is misleading and incorrect. It may be that 80 per cent of family doctors
have computers on which they hold a list of their patients, and a large
number of those will have details of immunisations, etc. I think you will
find that probably less than 20 per cent actually keep their day-to-day
records on computers.
Christopher Everett Alton, Hampshire
Letter: Caught in a quake
Feedback muses on the activity of people caught in an earthquake (20
August). I can give you a first-hand account as I was staying in Los Angeles
on the night of the big 6.6 in January (I have the T-shirt to prove it!).
I was only there for one night, in a fairly old 10-storey hotel north
of LA airport, quite close to the epicentre.
At 4.31 am, I woke up to a roaring sound before the shaking started
and assumed it was a massive thunderstorm. As I had been in a deep sleep
it was some time before I managed to pull myself together enough to panic.
Being a complete novice, I did not have the first idea about what to do
but all my senses were screaming at me to get outside as quickly as possible.
However, the adrenaline rush and almost audible heart-pounding seemed to
make it very difficult to do much apart from try to grab something solid.
Thank goodness everything in a hotel room is bolted down.
After what seemed like an age I did the most ridiculous thing imaginable:
I threw the curtains open to see what was going on outside the window (a
large, plate glass, hotel window ). Luckily the window stayed intact.
It was then that Don Anderson’s remarks ring true. I was overwhelmingly
caught up in the motion. It changed very noticeably from a jarring, jerky,
side-to-side movement to a rolling wave, almost smooth but with unbelievable
power. Despite being absolutely terrified, I was very definitely aware of
the changing forces at work.
After 40 seconds I managed to make enough sense of the situation to
run down the long corridor and out of the fire escape just as the main shock
came to an end. Thankfully, the building stayed where it was, although the
power was off and everyone was very bewildered.
I later learnt that one of the safest rooms would have been the bathroom.
However, I’m not sure if this is because of the proximity of the four vertical
walls or because it’s the best place to change one’s underwear.
Andrew Holder Salisbury Wiltshire
Letter: Unholy smell
Tam Dalyell need not be worried about the effect of nitrous oxide
on our historic buildings (Thistle Diary, 20 August). I was attending an
abbey service recently, at a time of high air pollution, and did notice
that the congregation tended to break out in giggles during the perfectly
serious sermon. This was of course due to the unusually high concentration
of nitrous oxide present. While the result was somewhat irreverent, the
stonework could not have been affected, since the gas is quite inert in
this respect. The main culprit is always sulphuric acid from the sulphur
dioxide in polluted air.
Tom Nash Sherborne Dorset
Letter: Causal connection
Emma Young correctly noted our discovery that most dyslexic children
show symptoms characteristic of cerebellar damage (New 杏吧原创, Science,
6 August). She then noted that correlation does not prove causation. But
the evidence is very much stronger.
Following the discovery that dyslexic children balance poorly, we tested
large panels of dyslexic and control children on 45 tasks covering the skill
spectrum. These studies have been published or accepted for publication
in the academic literature. The strongest, most consistent deficits were
in reading and spelling (as expected), and also in phonological skill,
motor skill and in blindfold balance.
Recent evidence that the cerebellum is significantly involved in each
of these latter three skills led us to formulate the ‘dyslexic cerebellar
deficit’ hypothesis. In a stringent test, funded by the Medical Research
Council, we replicated a study showing that cerebellar lesions lead to specific
deficits in time estimation. Precisely the predicted pattern of results
was obtained, with dyslexic children showing large impairments on time estimation
but none on a control loudness-estimation task. No other theory of dyslexia
predicted this pattern of results.
Furthermore, in applied work using further subject panels, we have established
that cerebellar tests are very sensitive to dyslexia, with two simple tests
correctly classifying 90 per cent of the subjects. By adding established
tests, the discrimination is further improved. This forms the basis for
our dyslexia screening tests for 5 years and upwards (available 1995).
In short, rather than a chance correlation, the link between cerebellar
symptoms and dyslexia was predicted from years of laboratory research. The
discovery should illuminate the causes of dyslexia and the cerebellum’s
role in skill development and, crucially, should lead to better educational
prospects for dyslexic children.
Rod Nicolson, Angela Fawcett and Paul Dean University of Sheffield
Letter: Optimum population
Having just read Debora MacKenzie’s excellent article (‘Will tomorrow’s
children starve?’, 3 September), I would like to suggest that, if a world
population of 10 billion – or 8 billion or 6 billion – is beyond the Earth’s
carrying capacity, then the question we should logically be asking ourselves
is: what population would be within the Earth’s carrying capacity? More
specifically, the question might be: What human populations, for the world
and its regions, would be most compatible with the option of a good quality
of life for everybody everywhere?
It is the ‘everybody everywhere’ part that complicates matters. If there
is to be a ratio of one car for every three persons in Europe, equity requires
that the option of the same ratio should be available in Asia.
Of the many criteria that have to be considered in looking for an answer,
the three most fundamental are: the maintenance of biodiversity, the availability
of freshwater, and the availability of land.
From papers presented at the Optimum Population Congress in Cambridge
last August and from studies made since, some tentative figures for maximum
sustainable populations are beginning to emerge; for example, the following
top-down figures: for the world, 2 billion; Asia and Oceania, 1 billion
(15 million for Australia, 20 million for Japan . . .); Africa, 400 million,
for the Americas 400 million; Europe, 200 million (25 million for Germany,
20 million each for France, Italy and Britain, 15 million for Spain. .
.).
Calculations for individual countries tend to produce even smaller figures;
for example, 16 million for Germany calculated by Wolfram Ziegler of Munich
University, who maintains that the ‘critical environmental strain’, defined
as ‘the point of just avoiding the anthropogenic extinction of species’,
was reached there in the early 1880s, when energy consumption first exceeded
4000 kilowatts per square kilometre per day. In the case of France, Maurice
Allais, a Nobel prizewinner for economics, argues that the optimum population
would be around 10 million, a figure he bases mainly on the possibilities
for foreign trade. In the case of Switzerland, Gonzague Pillet of Fribourg
University concludes that the population could not be more than 1 million
at the 1992 standard of living if the economy were only run on the flow
from the country’s own natural resources.
The scientists concerned go out of their way to stress the speculative
nature of their figures. On his proposed maximum world population of 2 billion,
based on average per capita energy consumption of 3 kilowatts for all continents,
Paul Ehrlich of Stanford University comments: ‘Suppose we have underestimated
the optimum and it actually is 4 billion? Since the present population is
over 5.5 billion and growing rapidly, the initial policy implications of
our conclusions are still clear.’
David Willey Optimum Population Trust Manchester
Letter: Optimum population
The increase in mass migration predicted for the 21st century has already
started. In 1970 the numbers of displaced people in Africa receiving food
relief was about 1 million. The number has doubled every six years, that
is, at four times the growth rate of the population of the region as a whole,
reaching 13 million in 1994 (not including the recent Rwandan refugees).
Informal estimates suggest at least as many again may not have been counted.
Thus, by the end of the century, something like 50 million people in Africa
alone, members of tribal or religious minorities, or simply the landless
poor, will be either stateless or destitute in their own countries, their
lives depending on international food aid.
Malthus’s suggestion that food supply would always come to limit and
regulate the size of a population is by no mean the most pessimistic model.
Fred Hoyle, in his St John’s College Cambridge Lecture of 1963, argued
that episodes of mass mortality are more likely than chronic starvation.
Market exchange of agricultural products and new technology make it possible
to support densities of population well above those of subsistence societies.
But markets and investment in technology depend on stable, integrated and
complex social organisation and infrastructures. As the level of complexity
increases, any disrupting political or natural event risks a visit by the
four horsemen of the apocalypse – which in turn could trigger a self-reinforcing
collapse of food supply.
Hoyle calculated that the whole cycle of growth, from the (1960) level
of 5 billion up to a maximum of 25 billion, followed by a catastrophic collapse,
would take about 200 years. Even with his assumption of a global society,
this was perhaps optimistic. With the current low investment in agriculture
and adverse terms of trade for regions such as Africa, it seems likely that
the cycle will be much shorter.
Philip Payne St Margarets, Herefordshire
Letter: Hot coal?
It is claimed that power stations using ‘clean coal’ technology are
more attractive than nuclear reactors (In Brief, 27 August).
Many years ago I read a report that the radioactivity issuing with the
flue gas from an average coal-fired power station (due to naturally occurring
potassium-40 in coal) was five times that allowed from a nuclear plant.
Is there any truth in this?
F. G. Grisley Barry, Glamorgan
Letter: Growth means cars
Lynn Hunt’s argument (Letters, 3 September) that the government’s ‘multibillion
pound road-building programme’ is likely to be correlated with forecasts
of increasing traffic over the next thirty years does not stand up to examination.
For a reasonable correlation to be established, the planned increase in
road capacity would have to bear some reasonable relationship with forecasts
of increasing traffic, which she quotes as between 69 and 113 per cent by
2025. In practice the road programme would increase the physical size of
the network by some 3 to 5 per cent over 10 to 15 years.
Using the size of the road network as a simple proxy for road capacity,
total road length/capacity increased by 5 per cent over the past ten years,
while vehicle traffic increased by 44 per cent. While new roads may have
some limited generative impact on traffic, Hunt’s assertion that ‘the doubling
of traffic . . . is dependent upon new roads’ really is nonsense.
Each 1 per cent of economic growth means 拢7 billion more economic
activity, with more journeys to buy and sell raw materials and goods and
services, more journeys to work and more demand for leisure travel. Given
the prospect of 2.5 to 3 per cent gross domestic product growth in the medium
term, these are the factors which will generate traffic growth and transport
demand.
J. McLaughlin British Aggregate Construction Materials Industries London
Letter: Awkward truths
Being economical with the actuality seems to be a way of life in both
local and central government. So two recent letters (20 August) came as
little surprise.
In ‘Scottish Water’, Adrian Shaw waxed lyrical over the efficiency of
Strathclyde Regional Council’s sewage services. He failed to mention how
cheap pumping untreated waste into bathing water can be. If a private company
practised such environmental vandalism, the council would (rightly) be quick
to condemn. Is it a case of who guards the guards?
On the same page, Jan Thompson (‘Wrong Country’) defends Norway’s exceptional
record on sulphur dioxide emissions. Perhaps the Norwegian administration
believes it is environmentally preferable to live by selling fossil fuels
than by burning them.
Stuart Randall Dunfermline, Fife