Letters : Local solutions
Coventry
Unfortunately, your article on mines assumed that solutions to the problem in
developing countries must be hi-tech and “parachuted in” from the industrialised
north (“One false step”, 4 May, p 32).
Most mines will, sadly, be cleared “an arm and a leg at a time” by local
people (often children) unless the ability to clear mined land is made available
to those who actually have the problem鈥攖he local population. Access to
low-cost tools and appropriate methods is desperately needed鈥攖ools which
can be locally made, locally repaired and used by local operatives without the
support of outside agents.
The Development Technology Unit at the University of Warwick has been
researching civilian clearance methods and has tested a number of pieces of
equipment. Shields, face protection and other equipment have survived
surprisingly well鈥攅nough to reduce fatality to temporary hearing loss.
These were not multi-layer Kevlar constructions costing thousands of pounds,
but simple kits of steel and plastic made in someone’s garage. Developing
country mine clearers could thus have their protective clothing and equipment
made locally and be able to continue work after the expatriate teams have gone
home.
Most minefields are cleared years after they were laid and in the interim
have probably become bush or forest. Methods which can cope with overgrown
conditions and work much faster are badly needed鈥攅ven at the expense of
reduced clearance efficacy.
Could a small scale miller or flail be built and used? Single-axle tractors
and rotavators are already available in many countries affected by
mines鈥攖hey are much cheaper than four-wheeled ones and could be adapted
for remote control (by trailing cable). They could be replaced or cannibalised
if destroyed by a vehicle mine or larger piece of unexploded ordnance.
We must develop the necessary equipment soon.
Letters : Penny pinching
Milton Keynes
Surely no one is taking seriously the suggestion that the Ministry of Defence
can’t afford to store a database of 72 megabytes in which there is considerable
interest and which may be needed for important legal evidence (“Written out of
history”, 18 May, p 14). Seventy-two megabytes can be stored on a zip disc of
the sort owned by thousands of PC users, and costing about 拢12, or could
be stored about 30 times over on a typical DAT data tape used for computer
backup and costing around 拢5.
I would gladly volunteer to go along to the National Radiological Protection
Board and accept a download of the data for safekeeping if the MoD seriously
maintains it can’t afford to hold it.
Letters : Cementing the facts
Crowthorne, Berkshire
Fred Pearce’s charge that Her Majesty’s Inspectorate of Pollution (HMIP) is
allowing less rigorous standards on emissions from cement works might have
caused more concern if the figures on which it was based had not been so
inaccurate (“Bending the rules on toxic fuels”, 23 March, p 14). Pearce was
misinformed when he said that HMIP had increased the environmental assessment
level of thallium by a factor of 40 000. The figure had, in fact, been increased
four-fold, on the basis of occupational health standards. In addition, the
figures quoted by Pearce for environmental assessment levels of nickel and
arsenic were merely out-of-date, having subsequently been revised by HMIP.
There were other inaccuracies in the article. Emissions of chromium and
nickel at Castle Cement’s Ribblesdale works have not increased “up to nine
times” since the introduction of fuel derived from chemical waste; they have
been reduced, by 33 per cent. The philosophy which drove HMIP was not
“integrated pollution control” but the “best practicable environmental option”.
Whether the traditional fuel in cement kilns, a mixture of coal and petroleum
coke, is “dirty” is perhaps open to dispute. What cannot be disputed, however,
is that petroleum coke is a product of oil refineries, not a “coal product”.
Elsewhere, his arguments were not strictly inaccurate but certainly emotive.
His rhetoric became most expansive when describing problems at Ribblesdale,
where apparently “plumes of dust and dark smoke billowed from the kilns and
engulfed people on the ground”. Dust emissions from all cement kilns have, in
fact, been considerably reduced over a long period. It is true that a
combination of weather conditions and local topography can periodically cause
any chimney plume to reach ground level. Castle has acknowledged that this
happens occasionally at Ribblesdale, has sought assistance from scientists at
AEA Technology and will invest heavily in the correct solution to the
problem.
Letters : Bargain goes bang
Biggleswade, Bedfordshire
Receipt of the latest New 杏吧原创 index has led me to your report
(In Brief, 30 March, p 11) on the “bargain” supposedly being proposed by NASA of
supersonic travel (SST) at a price “[in] line with other commercial
flights鈥攗nlike Concorde, which is considered too expensive . . .”.
No such “supersonic bargain” is possible.
NASA, you report, acknowledges that there are problems of “noise, pollution
and cost”. But NASA abandons reality in proposing that “once [such problems]
have been overcome, American companies could sell supersonic planes worth around
$200 billion”. Very similarly, in 1971 the chairman of the Concorde
builder predicted that by the end of the century 1500 Concordes “could” be in
operation, bringing in [at 1971 values] “拢30 billion”.
As is well known, if a few design problems were overcome, pigs might fly. SST
obsessives have been trying to overcome their problems (not the pigs’) for 40
years鈥攚itness two cancelled US SST projects, the unsellable Concorde, and
the abandoned Soviet TU144鈥攁nd they are no nearer doing so than they were
at the start.
The SST complex of problems is rooted in two unavoidable concomitants of
supersonic flight in the atmosphere: the supersonic shock wave (the infamous
sonic boom, which precludes operation over land) and aerodynamic heating, both
of which dissipate much energy, resulting in fuel consumption far above that of
subsonic competitors. The same complex of problems also inevitably results in
development and manufacturing costs far above subsonic costs.
So: no “supersonic bargain”.
Letters : Evading expansion
Australia
Far be it for me to be evasive in my description of the expanding Universe as
Noel Hodson implies (Letters, 25 May, p 57). The “atoms” of cosmology are
clusters of galaxies, which steadily retreat from each other. Within a cluster,
motion is more complicated, due to local gravitational effects. Individual
galaxies or stars do not expand with the Universe, as they are gravitationally
bound.
In the same issue, J. Maddison states that entropy decreases in a contracting
universe. There is no sound scientific reason why this should be so, and plenty
of evidence to the contrary. True, the entropy-flip theory does make periodic
reappearances in the literature, most recently when Stephen Hawking repudiated
it.
Finally, Russell Smith asks how one can possibly test the acausality of
quantum events. In fact, several such tests have been carried out over the past
15 years, most notably by Alain Aspect in France. These tests make use of the
famous Bell inequalities, which prove that quantum indeterminism cannot be
produced by unknown causal disturbances, so long as faster-than-light
communication鈥攊tself a source of causal chaos鈥攊s ruled out.
Letters : Working by words
Hale, Cheshire
As a project consultant I find that speech recognition has transformed the
way I work. I thought that some of the statements on the subject were, to say
the least, misleading (“Hello, is anyone there?”, 18 May, p 36).
For example: “While computer users are happy to learn how to type, they baulk
at having to change the way they speak in order to use a speech recogniser.”
Personally, I don’t find putting a minute pause between words very taxing. I
have never tried to learn to type at over a hundred words per minute, but I
suspect I would find this a little more difficult.
Jackie Fenn of the Gartner Group “believes that even with all the
improvements, typing and using a mouse is generally, faster, easier and more
effective for everyday purposes”. I doubt if this would be true even if I could
type at over a hundred words per minute. IBM’s VoiceType, with which I am
“writing” this letter, requires an extra card and takes about 45 minutes to
train. The next version of the OS/2 Warp operating system, available later this
year, will have VoiceType built in, needs no extra hardware, and will need no
training.
The system enables me not only to dictate but to control my computer by
voice. When I have finished dictating this letter I will connect to the
Internet, open the Web browser, navigate to “Planet Science”, and transfer the
text to the letters page all by voice command. And the final word? “Send.”
Letters : Minimal methane
Royal Holloway
“There’s a chiel among ye takin’ notes, and faith, he’ll print it . . .” (or
something like that鈥擨 forget). Not being a politician, I wasn’t on guard
and didn’t expect to be quoted, especially at such length (This Week, 25 May, p
7). Thanks anyway, the point is clearly stated: we need to be concerned about
biomass burning in the tropics, and about the global methane budget, which
offers an excellent first line of attack on the greenhouse problem.
But may I clear up some minor points? I don’t head the European Union’s
methane monitoring unit鈥擨 merely co-ordinate an attempt to quantify
Europe’s methane emissions. Brussels has been and remains supportive.
A group of us have also been studying Russian emissions. It is clear that
emissions from the ex-Soviet gas industry are very large. Losses probably come
from all stages in the system, from wellhead to low pressure distribution. My
point was that the biggest leaks are the ones to go for initially, providing the
best cost/benefit ratio.
In contrast to other large Soviet industries, the gas industry has a
relatively successful recent history, and is vigorously trying to reduce leaks.
However, there is clearly much scope for more investment into leak reduction,
and such investment would probably be profitable. In Britain, much-maligned
British Gas has an excellent record in this sort of investment, for good
commercial reasons: it pays.
Paul Crutzen’s point is worth emphasising: Europe’s best environmental
investment is to look globally (This Week, 18 May, p 4). He argued forcefully
that it is in Europe’s interests to help tropical nations to monitor and to
reduce unnecessary biomass burning. As he points out, this is a key global
problem, and Europe will share in the benefit from its study. The Brussels
meeting was not a deathbed vigil of climate research (no corpse, yet) but a
welcome feast to celebrate Crutzen’s work, and that of Nick Shackleton, Willy
Dansgaard and Bert Bolin, all winners of major prizes. Europe has much to give.
In shaping future research policy, I hope the EU will heed Crutzen’s wise
advice.