Letters: Not so sloppy
A flight level is a pressure altitude, expressed in feet with the final
two zeros dropped; hence FL280 is at 28 000 feet above mean sea level
in standard atmospheric conditions, not 2800 feet as stated in ‘Careless
talk that costs lives’ (Review, 6 August).
The apparently bewildering exchanges between pilots and controllers
are actually a highly efficient dialogue reflecting the pressures of the
real flying environment. Tony Jones’s example ‘we are two for four’ (actually
enunciated ‘two f’-four’) would be as clearly understood by those ‘sloppy
airfolk’ as ‘fish ‘n’ chips’ is by any Englishman.
In the end, the preposterous technological fixes for garbled messages,
described in the review, may be by-passed or overtaken by the development
of non verbal methods of data-transfer (remotely piloted airlines?). Until
then, a bit more respect for aircrew please.
Erik Addison London
Letters: Slow ant
I was intrigued by Charles Arthur’s article about BT’s new ‘software
ant’ idea (This Week, 4 June). Unfortunately, although the ‘smart ant’ approach
may well have useful applications to other problems, its value for the travelling
salesman problem is not as great as the article would have us believe. Its
achievement of getting within 4 per cent of optimal on a 30 000 city instance
in 44 hours on a workstation could have been bested by traditional algorithms
10 years ago (on the machines of that time).
As mentioned in an earlier article in your journal (‘Why sales reps
pose a hard problem’, 12 December 1992), our own implementation of the 1973
Lin-Kernighan algorithm (joint work with Lyle McGeoch of Amherst College)
gets within 1.5 per cent of optimal on million-city instances in just 3
hours on a workstation with sufficient memory. On our current (5 times faster)
processor, we can get within 2.9 per cent of optimal on a 30 000 city instance
in just 18 seconds using the ancient 3-Opt algorithm, and within 1.5 per
cent in 40 seconds using Lin-Kernighan.
David Johnson AT&T Bell Laboratories New Jersey
Letters: Contented termites
As another summer day begins, and the air starts to get hot and sticky,
I, for one, very much like the idea of joining the compass termites to work
in giant underground chambers below wedge-shaped cooling towers stretching
up into the sky (‘Offices that breathe naturally’, 11 June).
Many hordes of us dedicated workers are squeezed into any minute partitioned
space available, within already cluttered offices, when the original intention
of the building’s designer was for open-plan floor space and uninterrupted
airflow. As Robert Webb so rightly states in his article, the design of
a building in relation to ventilation and airflow is only half the problem
– the other half seems to be the illogical use made of the space by the
office accommodation planners after the architects have gone home.
Perhaps if our office planners were made more aware of how best to utilise
interior spaces to keep air circulating freely, and the designers and architects
took into account the fact that the occupants of their buildings will forever
be adapting the space to suit their current needs, then maybe airflow and
temperatures inside would be easier to monitor and control, making us dedicated
workers happier little termites.
Bernise O’Reilly London
Letters: Murphic tunnelling
The observation by Ian Fells (Letters, 16 July) that Murphy’s Law cannot
be proved because it interferes with the testing process, is an important
step in Murphic research. However, his comment that ‘Murphy’s Law operates
at all times’ reminds me of a little known corollary which illustrates
some of the subtleties of this principle.
Some workers have observed that things occasionally go right. This is
not a violation of Murphy’s Law but rather an illustration of its universality.
Murphy’s Law is subject to its own restrictions and cannot ensure that
everything that should go wrong actually does. It is only because of such
quantum Murphic tunnelling that anything ever actually gets done.
Graham Hagens Ontario, Canada
Letters: Right to inquire
‘. . . can it really be argued that a local authority should have the
right – or indeed obligation imposed by law – to re-examine the technical
fundamentals, and the implications for a national energy policy, not to
mention decommissioning costs . . .’? asks Ian Lloyd (Forum, 30 July).
The government has told us that its energy policy is to leave everything
to the market. But the Nonfossil Fuel Obligation is a manifest distortion
of the market: surely not only the local authorities but all of us have
a right to ask what the policy is, if indeed there is one.
With regard to decommissioning, it was reported in the press (The Guardian,
14 June) that Nuclear Electric had put forward three alternatives for the
future of Trawsfynydd (closed last year): to enclose parts of the site for
135 years while the radioactivity decays, at an estimated cost of 拢60
million; to bury the building under a mound of quarry waste, at a cost of
拢95 million; or to dismantle it and dispose of the parts, at a cost
of 拢500 million. Since none of these things has yet been done to a
station of this type, these estimates must be based largely on guesswork.
Naturally, Nuclear Electric wants to use the cheapest option, whereas
the local people want to be rid of the thing altogether. Surely a planning
committee has a right to know whether, in the long term, it is going to
be left with a new and slightly radioactive hill, or a derelict industrial
monument for its descendants to clear up, or what?
If the policy in these matters were known, and were known to be generally
acceptable, planning authorities might have an easier job.
P. W. Agnew Aberfeldy, Tayside
Letters: Malthus was right
I was surprised to read your call for more investment in research into
farming systems in order to stop famine in Africa. I was surprised, having
spent a lifetime working in African agriculture and having just read James
Morton’s The Poverty of Nations: The Aid Dilemma at the Heart of Africa.
It is about Sudan, which I agree is very different from Rwanda, but the
points he makes are relevant.
Morton questions the viability of proposals for more investment in agricultural
research and training which (according to the World Bank, 1989) were to
have been the basis for an annual 3 per cent growth in the productivity
of African agriculture. He observes that this ‘old fashioned’ policy disregards
the findings of the 1980s, during which the high levels of investment in
agricultural research in Africa (more than in South Asia) have proved no
more productive than earlier attempts to transfer off-the-shelf technology
to African farmers.
In western Sudan, three factors have been at work in retarding growth
in productivity: the relative abundance (not shortage) of land; the acute
shortage of foreign exchange (and the fact that import licences were obtainable
for only the basic essentials); and the loss of markets for crops (primarily
due to the breakdown of transport links) and the scarcity of imported consumer
goods on which farmers can spend their money. Morton insists that since
growth in regional trade over the last twenty years has been so seriously
impeded, there is no point in expecting farmers to take up new technologies
when they cannot exploit the ones they already have.
Over the major part of Africa, where labour is in short supply at critical
times of the year, farmers are reluctant to adopt innovations which produce
more food, but involve more work. Ester Boserup, in her important book The
Conditions of Agricultural Growth, argued that intensification would happen
automatically once people-to-land ratios had reached the critical point
where there was no more land to clear. Changes in agricultural methods were
themselves the consequence of population growth.
Martin Adams Girton, Cambridge
Letters: Food for thought
I read with great interest the reported comments of Alan Smithers regarding
food in technology teaching (This Week, 30 July). If he believes that nutrition
should be part of the technology curriculum why has the Engineering Council
been so vehement in its opposition to retaining food as a mandatory part
of the technology curriculum?
For the past two years, the British Nutrition Foundation has been trying
to help the School Curriculum Assessment Authority and others (including
the Engineering Council) to understand what food technology is all about.
In our view, food technology is about the conversion of raw materials to
edible products founded in domestic practice. Processing enables the nutrients
contained in the materials to be made available to people. This is true
of both industrial and domestic practice and as a consequence nutrition
is an essential component of food technology.
It would seem that Smithers now shares our view, so does this mean that
the Engineering Council has advised SCAA that food and nutrition should
be retained as compulsory elements in the technology curriculum for all
pupils aged 5-11 years?
Gill Fine British Nutrition Foundation London
Letters: Why the surprise?
The limits to the effectiveness of theoretical astronomy are demonstrated
by the Comet Shoemaker-Levy 9 story (This Week, 30 July). Astronomers, no
doubt professional ones, had expected to see water among the other compounds
thrown up by the comet’s entry into the Jovian atmosphere. The fact that
they did not is now apparently explained by the assumption that the debris
did not penetrate down to the water-bearing layers. Yet this should have
not been unexpected since we were told that comparable objects disintegrate
high up in our atmosphere when they are on target for Earth.
Moreover, we read of the surprise expressed at the amount of sulphur
and metallic elements detected during the impact. Why the surprise, if one
accepts the plausible story that these merely characterised the constitution
of the comet itself? Even an amateur might have predicted this effect (and
many probably did).
The foregoing tempts me to conclude that theoretical astronomy is embarrassingly
inadequate at predicting what will happen in the case of a pretty-much deterministic
event in the neighbourhood of our own planet. How, then, are we to regard
cosmologists, who spend their lives assembling theories about the entire
Universe in the certain and perhaps comfortable knowledge that there will
be little or no opportunity for their work to be subjected to the acid test
of experiment? Is the philosophical parallel between cosmology and theology
indeed as close as some have always maintained?
Colin Pykett London
Letters: False memories
I feel that Phil Bagnall’s article ‘Hypnotherapy: who is abusing whom?’
(Forum, 30 July) is like blaming the telephone for the message.
I have trained both in this country and in the US and have never seen
a memory implanted in a client’s mind. What a properly trained hypnotherapist
does is to put the client in touch with his/her own unconscious; the therapist
acts as a means of communication and not as a guide to, or controller of,
the client’s unconscious.
I am of the opinion that Freud, who used hypnosis in his early cases,
abandoned the method precisely because it did not give him a degree of control
over his patients.
One pitfall is that hypnotherapy heightens the unconscious mind, which
contains delusions and fixations, as well as repressed memories. This explains
why stage hypnotists, who should rightly be under some form of control,
can produce such spectacular results. I am not saying that all cases of
false memory syndrome are due to the release of repressed fantasies, but
feel that the possibility should be researched.
L. Forster London
Letters: Malthus was right
Garrett Hardin once observed that no one ever dies of overpopulation.
Your Comment on the crisis in Rwanda (30 July) would appear to support his
view.
After reading the words of the Rwandan agriculture minister and your
statistics concerning the density and growth rate of the Rwandan population,
I was rather surprised to read your conclusion that population issues were
not the problem in Rwanda – rather, that the problem stemmed from Rwanda
having a technology base inappropriately low for its population size.
What most surprised me was that the economist’s view of shortage of
supply, as opposed to the ecologist’s ‘longage’ of demand, still holds sway
in your journal. As well as appearing naive about the rapidity by which
population growth will nullify any technical assistance, your article sounded
suspiciously like a salesperson’s drive to promote science.
You drew attention to the ineffectiveness of past famine relief efforts
in easing the suffering in other parts of Africa. While the provision of
new technology will help people beyond the cessation of media coverage,
it will ultimately be swamped under the rising human tide. Both types of
endeavour should always be supported by an appropriate population programme
to prevent the return to the former suffering. Malthus’s conclusions in
his great work imply as much, but almost two centuries on his words still
fall on deaf ears.
Andrew Yool Kenilworth, Warwickshire