Mobile model
The article about cigarette manufacturers abandoning technologies to develop
a “safer” cigarette
(This Week, 6 March, p 4)
makes one think of the mobile phone industry鈥攚here
patents on shielding devices have already been filed
(This Week, 7 November, p 22).
Let us hope that the tobacco industry’s ethics are not providing a model for
the mobile phone industry.
See page 20 for our special investigation of mobile phones鈥擡d
Maximum security
The Royal Mail is apparently going to sell us an e-mail electronic stamp in
the form of a 128-bit public key encryption system. Furthermore, it isn’t
insisting on key escrow
(This Week, 27 March, p 17).
At first sight it seems a good idea, but with only a 128-digit public key,
key escrow is not required. The system is just plain insecure.
An ad hoc panel of cryptography experts has recently published a report
recommending 500 digits for minimum security for public key ciphers. Public key
ciphers are usually based on the RSA system, which relies on the time taken to
factor a composite number N (1024 digits long) into its two prime
factors, p1 and p2 where
N = p1 脳 p2.
With modern encryption systems, it is never appropriate to use less than the
maximum-security level. If you were stupid enough to use 128 digits for bank
transfers up to 拢1000, 400 digits for up to 拢10 000, and 1024 digits
for transactions above 拢100 000, you would enable an opponent to narrow
his attack by concentrating on the most potentially profitable keys.
If you have a strong system, use it for everything. Suppose that GCHQ can
break a 1024 digit key in three hours. It could cope with eight messages a day.
If you flooded it with 800 messages a day it would never keep up.
Library lottery
I read the comments by John Stonehouse on access to libraries with interest
(Forum, 20 March, p 47).
It is getting harder for scholars to use university
libraries, even for a single day’s reference. Many charge excessive sums and it
is a lottery when you turn up as to whether you will be charged.
There is another barrier. If the information you need is on CD-ROM, then
somehow the library thinks it is different. For example, although Stonehouse
says his library at Imperial College, London (allied with the Science Museum
Library) has free access, this is not so for electronic data. If you are a
member of the public, then CD-ROMs are not available. So, if you want to search
abstracts or indexes, you have to do it the hard way.
Fast work
It is not true to say that “faster clock speeds usually require higher voltages”
(This Week, 20 March, p 14).
They require lower voltages. The reason is that with faster chips, the
transistors are smaller and the packing density higher.
For example, the Intel 486DX-50 used .80 micron-wide transistors (at 5 volts)
whereas the Pentium II uses only 2 volts (the motherboard is informed of the
precise voltage to apply before the chip is initiated by way of four extra
pins). The current is, however, higher, which accounts for the extra power
consumption.
Safe Sinclair
Prompted by your piece on the Amstrad PC1215-50
(Feedback, 13 March),
I would like to point out that the Sinclair QL will also not have any Y2K problems,
despite having been released in 1984. This is because the date is stored in
seconds from an original date in July 1961. The crunch time for users of this
system will come in 2089, when the number will become too large for the
register.
Smog extractors
Lia Hattersley discusses Jorg Schlaich’s “power towers”, wherein the buoyancy
of solar-heated air rising up a tall chimney spins a turbine and generates electricity
(“Electric dreams”, March 6, p 30 and
Letters, 27 March, p 57).
Another use for this giant chimney would be to help free cities of smog. Smog
often occurs when large urban centres are subjected to intense sunlight and poor
atmospheric mixing because of a temperature inversion. The smog “bubble” over a
city is frequently adjacent to relatively clean air, either rural or offshore.
If power towers are located within the city, then the polluted air sucked up the
giant chimneys would be replaced by relatively clean air from outside the urban
centre. These power towers could supply the city with its electricity
requirements as well as keeping the air breathable.
Of course, there are practical considerations, such as how to utilise the
space under the collection areas. Since solar collectors do not have to be
circular perhaps transportation corridors could be used for this purpose. Then
the hot, dirty exhaust from millions of cars and trucks would actually help keep
the urban air clean.
Pirates ahoy
The major record companies appear once again to be trotting out the old
canard of copy protection to justify the encryption of CDs
(This Week, 20 March, p 10).
It is manifestly impossible to prevent copying. At some point the digital
information must be converted to the analogue electrical signal, or line output,
that drives your amplifier and speakers. This signal can be directly recorded in
analogue format鈥攖his is what you do when you tape a friend’s record or CD.
The line output can also be connected to a sound card in a computer. If you
have a writable CD-ROM and good quality sound card, you can then make a CD which
is essentially indistinguishable from the original.
In both cases you are infringing copyright, but in practice it is
unenforceable unless you start distributing your pirate copies.
Record companies argue that recording from the analogue signal degrades the
sound. If you have a good quality system the analogue audio signal will be
excellent and you would be unlikely to detect any audible difference between the
original and your pirate copy.
A similar argument applies to Microsoft’s attempts to use Reciprocal’s
encryption system to protect music downloaded from the Net
(p 11, same issue).
The data stream must be sent to your sound card or computer screen in
unencrypted format. Capturing this unencrypted data stream may be difficult but
it is not impossible and I don’t doubt that there are dozens of pony-tailed
computer nerds already devising algorithms to do just that.
In the grip of memes
Reading Susan Blackmore’s article on memetics and the subsequent review of her recent book
(“Meme, Myself, I”, 13 March, p 40,
Review, 20 March, p 43,
Letters, 27 March, p 56 and
Letters, 3 April, p 54),
it occurred to me that if she is right in her conclusions, then she doesn’t really exist,
and we need take no notice of her. It’s just her memeplex at work for its own selfish ends.
However, if she is wrong, then she does exist, and we should evaluate her ideas
carefully. Of course, if we then concluded that they are correct . . .
I hope this helps. But, if not, it’s not my fault鈥攖he memes made me
write this . . . or did they?
Back to the woods
Allan Savory claims there is increasing desertification of much of the US
(Letters, 27 March, p 56).
On the contrary, a century and more ago much of the
US was cleared of forests and turned into farmland, and this probably destroyed
some species. But a recent increase in the efficiency of US agriculture is now
releasing land from farming.
Forests are regrowing on abandoned US farmland at such a great rate that it
seems the tree growth is consuming as much carbon dioxide as the total US
industrial emissions of this gas.
This forest regrowth can be expected to result in greater biodiversity
because existing species will enter the new forests and new species may evolve
with the growing forests.
Early warning
Jon Day of the ADAS Terrington Research Centre argues that it is unacceptable
on welfare grounds and “bad for farm productivity” that some piglets weaned as
early as three weeks can take a further week to learn to eat solid food
(This Week, 20 March, p16).
His proposal to put garlic into the feed of pregnant sows
leaves me in despair at our stewardship of the animal kingdom.
In natural conditions, pigs are weaned between nine and twenty weeks. Rather
than tinkering with present early weaning practices, scientists should
acknowledge that this method of animal production is so severely detrimental to
the welfare of the sows and piglets that it should be abandoned.
Letter
As consultant anaesthetists we never cease to be amazed by the prowess of our
surgical colleagues. However, at the current time (and for most of this century)
anaesthetics have been administered by medically qualified anaesthetists who
have undergone postgraduate training.
The title of the article would also seem to suggest a confusion over two
separate methods of inducing and maintaining anaesthesia. Asking the patient to
count backwards from ten (an outdated practice) is associated with the use of
intravenous induction agents, the mechanisms of action of which are reasonably
well elucidated.
It is true to say, however, that the mechanisms by which inhalational
anaesthetic agents produce unconsciousness is still unknown.
Land of nod
The sleep-inducer oleamide may work by thinning the fats in cell lipid membranes
(“Ten, nine, eight . . . you’re under”, 20 March, p 34).
Its discoverer, Richard Lerner, speculates that it might also help to keep cell
membranes at the right viscosity when they get cold.
A friend and I, when in our teens, capsized a sailing dinghy in the middle of
Lyme Bay. There was a strong wind and a 3-metre swell, so when we had got it
righted it didn’t stay still long enough for both of us to get back in. As I
waited for my friend to tack back and pick me up, I started to get
cold鈥攖he only danger, given that I was secure enough in my life jacket. My
friend eventually reached me and we set out for the harbour. And, despite all
the excitement, I fell asleep in the bilges on the way back.
A common adjunct to exposure is sleepiness. Could this be caused by the body
synthesising oleamide to keep the lipid membranes at the right consistency,
triggering the sleep-inducing side effect in the same way as anaesthetics seem
to? Might it be possible to find a drug that did one and not the other, and to
put a couple of pills of it in the pocket of every life jacket?
Sadly, the discredited old remedy of brandy probably doesn’t offer quite the
right combination of characteristics to be reinstated.
Letter
The most intriguing fact I remember from my training in anaesthesia was that
one could anaesthetise tadpoles at atmospheric pressure, but if one increased
the ambient pressure they then woke up. Tadpole anaesthesia鈥攖here’s a
specialist field!
Indeed, I thought that anaesthesia itself was a specialist field. I trained
for six years at university for my basic MBChB to become a doctor, and for a
further ten in anaesthesia to pass specialist exams from the College (now Royal
College) of Anaesthetists, before becoming a consultant in anaesthesia.
Imagine my surprise therefore, to read your article’s first sentence:
“Surgeons have been putting patients under with general anaesthesia for 150
years.”