Letters: Pregnant pause
My wife suffers from asthma, and as such I pay attention to any mention
of it in the press and in scientific journals. I have never seen any mention
of the following observation.
Recently my wife and I had a child (mostly my wife, I just smiled a
lot). She suffers from mild asthma, but during the pregnancy, it almost
totally disappeared, only reappearing after the birth. My thought is that
some natural substance produced only during pregnancy (or in greater quantities
than normal) put the asthma in remission.
Obviously it may only be a naturally occurring steroid that is acting
in the same way as the sprays my wife uses, but I would like to know if
anyone else has experienced something similar or whether my wife is just
‘unique’.
Victor Gavin Cleckheaton, West Yorkshire
Letters: Big charge
The cost of a replacement battery quoted at 拢1500 for a lead
acid battery and 拢16 000 for a sodium sulphur one must surely preclude
their use in cars except for a few specialist applications (‘Flat out for
the car of the future’, 7 November.)
Whereas a recharge time of 10 minutes is probably an acceptable substitute
for the time to fill a petrol tank, the logistics of this need careful consideration.
Charging a 20 kilowatt-hours/180-volt battery in 10 minutes would require
a current of 670 amperes at 180-volts DC. And a station with 10 charging
points (equivalent to a petrol filling station) would have a power consumption
of 1 megawatt. Perhaps we should recharge the batteries at the nearest power
station.
Although electric vehicles are less polluting than the internal combustion
engine, the complete energy cycle efficiency is very similar (about 35 per
cent) and electricity generates its own pollution problems. Has any study
addressed a comparison of the total pollution from each complete energy
cycle?
B. Culpin Bolton, Lancashire
Letters: Nothing doing
John Gribbin tells us: ‘What makes the distance between two galaxies
increase is not that they are moving through space, but that empty space
is expanding and carrying them along for the ride.’ (Letters, 21 November).
May another non-cosmologist ask, how can empty space expand? If a region
of space is empty there is nothing there and surely the capacity of ‘nothing’
to expand or indeed do anything is zero? An area of emptiness is defined
by something on its boundary (such as a galaxy). Isn’t it the something
which moves, bringing us back to Jeff Bishop’s original question?
If nothing can expand I fear the consequences for the science budget
if the government gets to hear of it. Imagine: ‘Dear Research Council Chairman,
I am glad to say the government has approved all your project requests.
Please find enclosed nothing which you can expand to pay for them all. .
.’
Tony Grugan Weybridge, Surrey
Letters: War memoir
Edouard Bruyneel’s patent application for an improved supergun (Patents,
31 October) comes about fifty years too late. The Germans got there first
with their V3, some of which were actually constructed, buried in French
cliffs for protection against bombing. They had exactly the system of charges
fired sequentially as described in the patent.
The intention was to reduce London to rubble, and had it not been for
the extraordinary potency of the 10 ton ‘earthquake’ bombs conceived by
Barnes Wallis, which knocked the barrels out of alignment, might have come
nearer to achieving this aim than either of the other two, better known
V-weapons.
Rory Allen Shaftesbury, Dorset
Letters: Shut up, Blumlein!
Two articles in New 杏吧原创, 14 November, have a common link. One
by Feedback quotes the well known fact of Alan Blumlein’s prolific inventiveness.
The other item is a photograph in ‘Hydrogen’s evangelist’ of Rutherford’s
1932 Cavendish team showing a young Eric Leonard Casling White (2nd row
back, 5th from right).
White first worked for Blumlein in the EMI Research team and during
the course of a long career evolved as many patents as Blumlein. Among his
most outstanding are the ‘cathode follower’ and a very efficient TV line
scan system. Although over 50 years old, both ideas have their modern semiconductor
counterparts and are widely used.
I had the privilege and pleasure of working for and with White at EMI
for several years. Although equally original in thought, Blumlein and White’s
methods and actions were a complete contrast.
White would think long and hard over a problem and then speak or write
his summation judgement and proposals. Seldom did they require any serious
revision.
This was in complete contrast to Blumlein, who by all accounts was a
driver and dedicated workaholic who often bombarded a problem to death
with a welter of proposals and solutions.
Anecdote has it that on one particular occasion White was sorting out
a particularly difficult problem in company with Blumlein, who as usual
was throwing out proposals and possible solutions in characteristic nonstop
talk. Finally, in sheer frustrated desperation, White threw up his hands
and shouted ‘Blumlein, for God’s sake shut up. I can’t hear myself think!’
Blumlein was so taken aback by this uncharacteristic outburst that
he did shut up and walked off.
A. T. Lawton Goring, Sussex
Letters: Sticky problem
Can any of your readers please tell me how to remove self-adhesive
labels from a thermoplastic substrate which is liable to damage if you use
solvents or scratching?
While with patience and warm water the paper may be removed, the adhesive
itself is obdurate, much more so than on glass or metal.
Reginald Titt Salisbury, Wiltshire
Letters: Curbing cars
Mike Ellwood’s campaign for ‘severe punishment’ for drivers who cause
injuries is the wrong approach (Letters, 21 November).
There are 23 million drivers in the country, and annually 1500 pedestrian
road deaths and 54 000 pedestrian casualties. It follows that the normal
driver would spend on average 425 years before being involved in even the
slightest injury to a pedestrian, and 15 000 years before a death.
Risks at this level for an activity performed by most motorists several
times a day are therefore, at the individual level, so low that the ‘it
won’t happen to me’ attitude is a psychological certainty, which means in
turn that we must look to engineering rather than emotive solutions.
Ellwood makes this point when he mentions the ‘broad sweeping curves’
allowing ‘cars to corner at speed’. I am old enough to remember the conversion
into high-speed curves of many old right-angled junctions which had previously
forced cars to engage bottom gear and corner at walking pace, and the change
of many light-controlled crossroads into the pedestrian’s nightmare of the
urban roundabout.
The consequences are detailed in an article in the Department of Transport’s
Road Accidents GB for 1991 – pedestrian accidents at such junctions have
increased from 44 per cent in 1951 to 60 per cent in 1991.
The answer is clear: bring back the lights and the right-angled bends.
Also, 75 per cent of pedestrian accidents happen in built-up areas.
The severity of these is very much speed related: a child hit by a car travelling
at 40 mph is ten times more likely to be killed than if hit by one travelling
at 20 mph. Yet the most ignored safety law is the 30 mph limit. It is also
the easiest to enforce, again by an engineering means – the ‘sleeping policeman’.
G. E. Haines Woodbridge, Suffolk
Letters: Curbing cars
On most modern cars there is an electronic engine management system.
We are told that road pricing is technically feasible. Why not have suitable
low power transmitters at every point where there is a change of speed limit?
These would send a code to the car’s electronic system instructing it to
set a maximum speed for the vehicle which could not be exceeded.
Pedestrian injuries could be instantly reduced. Police would no longer
have to put themselves and others at huge risk chasing the so-called joyriders
through towns at over 100 miles per hour. An un-macho motorist like myself
could be spared all the headlight flashing and other harassment from those
who disapprove of our observance of speed limits imposed by bodies which
we elected.
Brian Moss Tamworth, Staffordshire
Letters: Curbing cars
My job entails me driving several thousand miles around the country
each month in all traffic conditions.
I can only observe that cyclists in particular are their own worst enemies.
If nothing else they obviously believe that all car drivers are blessed
with the gift of ESP or second sight.
Over the past month since the clocks altered I have compiled the following
statistics from direct observation: No front or rear lights at all, 67 per
cent; no front lights (rears only), 11 per cent; no rear lights (fronts
only), 9 per cent; no reflectors (side or rear), 63 per cent.
This leaves only 13 per cent who were adequately provided with lights.
The total sample size was 1072 cyclists counted during the hours of official
lighting-up time.
Cyclists be warned: black cats in coal cellars get trodden on.
John Bailey Aldershot, Hampshire
Letters: Hot on Hotol
Before the European Space Agency (ESA) embarks on a new Hermes spaceplane
from the ashes of the old one (This Week, 21 November), a full review of
design alternatives is necessary.
As British designers Alan Bond and Robert Parkinson showed in the Hotol
(horizontal take-off and landing) project investigated by British Aerospace
and Rolls-Royce, the cost of launching satellites and space station cargo
can be cut substantially if such vehicles are unmanned and remote-controlled.
BAe has already studied with Russia prospects for launching an Interim
Hotol from the back of a modified Antonov An-225 cargo aircraft. This vehicle,
powered by Russian liquid oxygen/liquid hydrogen rocket engines, could be
one of the most cost-effective solutions. The design aim is to place payloads
of 6 to 8 tonnes into a 300-kilometre circular orbit.
If Britain is to remain in the vanguard of aerospace technology in the
21st century, we need to be at the centre of ESA’s deliberations, with the
full support of government.
Kenneth Gatland Ewell, Surrey
Letters: Counting in tens
Steve Homer’s assertion that the assembler programmers of the patriot
missile software were responsible for the use of a decimal fraction, resulting
in a binary irrational in the timing controls, because ‘it was easier for
them’ does not stand scrutiny (‘Battling on with veteran computers’,
14 November).
Assembler programmers find it more convenient to work in binary or hexadecimal
(base 16) than to use decimal, and are probably the only people on earth
who routinely do mental calculations in bases other than 10.
It is much more likely that the choice of tenths of a second as a unit
was specified by a design team of non-programmers or high-level language
programmers and imposed on the assembler programmers.
Decimal thinking is only easy and convenient when programming in high-level
languages. The higher the level, the less the programmer understands or
controls what is actually going on in the hardware. This is exacerbated
by compiler bugs, which insert errors at the machine instruction level
even when fed error-free high-level language source. By contrast, assembler
programmers specify machine level instructions directly. Any programming
errors are their own; they can find them and fix them, while high-level
programmers are at the mercy of their compilers. All compilers produce
arithmetical ’rounding errors’ of the kind described when their easy, convenient
decimal maths features are used in programming.
Iolo Davidson Tetbury, Gloucestershire