Uranium hazards
Your discussion of the photoelectric effect as an possible “amplifier” for radiation emitted by depleted uranium (DU) lodged in human tissue is thought-provoking and timely (6 September, p 8). What was missing was a quick review of some of the other well-known problems associated with the use of DU in munitions.
First, the extreme heat generated by the friction of impact and penetration temporarily vaporises the uranium: it immediately reverts to uranium oxide, a solid in the form of a very fine powder with most particles being between 2 and 10 micrometres in diameter. Alas, this size range, it turns out, is the one most difficult for the body to get rid of. Anything smaller will be breathed out as easily as it is breathed in. Anything larger can be intercepted or expelled by various bodily mechanisms from nose hair to ciliary movement in the trachea, or by the kidneys. Thus, DU dust created by military action tends to lodge in the body for extended periods of time.
Military apologists claim that the alpha radiation from DU is so weak that it can be stopped by a piece of paper. They neglect to mention that we don’t walk around with pieces of paper in our soft tissues between DU particles and sensitive genetic material in our cells. Persistent low-level radiation within our bodies 鈥� within our cells 鈥� can be expected to produce much more damage over time than the low-level background radiation outside them so often cited by the Pentagon.
Secondly, there is no mention of the fact that uranium is a much heavier metal than lead, and toxic for chemical reasons as well. DU, so difficult to excrete, can be expected to display chemical toxicity as well.
History of the ozone hole
In 1997 I was walking in the Bulgarian mountains with David George, an Oxford physicist who worked with Joe Farman in the Antarctic. It was David George who actually operated the Dobsonmeter that produced the seminal ultraviolet measurements (20 September, p 46).
He told me Joe realised the significance of the measurements but needed confirmation because he did not really trust the old Dobsonmeter. Therefore Joe arranged to visit the Americans to check their data. Their data confirmed closely the British measurements, but the Americans had not realised their importance, and in fact did not really trust them. I understand that Joe did not waste time trying to convince the Americans otherwise.
Joe went ahead and published his results in Nature, which appears to me a perfectly reasonable course of action, since time was of the essence in initiating action to save the ozone layer.
I read physics at Oxford about the same time as David George, who died a few years ago of cancer.
Hearing graphs
Your interesting article “Graphical search engine will cheer sports fans” (20 September, p 24) overlooks one of the most interesting uses of the technology. Many people who are blind or have low vision are able to read research papers in electronic formats using speech synthesis. However, the lack of simple alternative presentations such as data tables means they are often unable to access the information in graphs and charts. This technology may bring hope in overcoming this barrier by extracting the data from images of charts.
Fantasy banking
You ask whether we should trust the modellers in the banking system who already claim they know where the gaps in their knowledge are (27 September, p 5 and p 8). The answer must be no.
In general, the great economist John Maynard Keynes noted over half a century ago that ““. The mathematician Beno卯t Mandelbrot has argued for years that there is no evidence that markets ever behave for long in a “normal” way, nor are market events independent of each other 鈥� whereas “value at risk” models assume they are.
To avoid a repetition of the current crisis we must understand exactly what went wrong. The liquidity crisis is a symptom, like a fever, of the solvency crisis, which is the disease. Banks are feared to be insolvent (yes, almost all of them) because the regulator allowed them to become radically undercapitalised.
When Lehman Brothers went bankrupt it officially held $11 of “tier 1 capital” (cash and fully paid undated equity) for each $100 of its total risk-weighted assets. But banks had been allowed to include debt instruments maturing on indeterminate dates as equity capital, and to ignore huge swathes of securities altogether by assigning them “zero-risk” weightings.
There is no substitute for clear disclosure of the make-up of bank assets and of the assumptions backing their valuations.
If the regulator steps in between the market and the banks’ managements, and effectively asks us to trust it to get the sums right, then the whole system will rely on one, apparently inadequate, intercessor. One regulator makes one set of obfuscated calculations and we get one enormous systemic collapse.
From John Hastings
Rob Jameson examines the quickest way to kill a bank (27 September, p 8). Surely the real problem is that the banks and financial institutions have forgotten (or ignored) the fact that money has no intrinsic value; it is a token of exchange, a way of comparing our valuation of disparate goods and services (such as houses and food) and a way of valuing the labour we sell.
The banks have been buying and selling debts and loans as if they were real commodities such as oil, wheat, consumer goods or railway journeys. If the profits made by the banks on these financial “products” are not backed by actual goods and services, those profits are merely inflationary.
Our governments should certainly not be helping the financial institutions out of holes they have dug for themselves. What they should be doing is decoupling these institutions and their dealings from the real world of goods and services in which the vast majority of us have to live.
Whittlesey, Cambridgeshire, UK
From Tony Budd
You hit the nail on the head: it’s all about misunderstanding and misrepresenting statistics. Over the years, I have had numerous arguments with engineers and architects about the basic design parameters they use and have been told quite seriously that, for instance, “this high-rise block of flats is designed to withstand a wind speed unlikely to be exceeded more than once in 100 years, so since its design life is 60 years, we have got 40 years to spare”. If the basic statistics to back that up were available, which they are not, the correct interpretation would be that there is a 1 per cent chance that the maximum wind speed will be exceeded in any given year, or a 60 per cent chance in the building’s lifetime.
When I point this out I am always greeted with incredulity, even, worryingly, by structural engineers dealing with protection against seismic shock. So bankers stand no chance at all.
What are the chances of the introducing a complete ban on the “not more than once in so many years” statement? Since it gained its charter in 1887 and has not done so yet, I suppose less than once in 121 years.
Wickford, Essex, UK
Brain scam
There may be good reasons for keeping brain scans out of courts (4 October, p 5), but doubt about their ability to “read minds” is not the best of them.
Whenever someone says of brain scanning “it’ll never be able to do that”, it goes and does it. Yet A. C. Grayling, for instance, claims: “neither fMRI nor any other scan can allow a researcher to say ‘you are thinking of Doris Day’, or ‘you are visualising the colour red’. Such fine-grained discriminations might forever be an impossibility” (20 September, p 48). Actually, brain scans can show quite clearly whether someone is seeing a face or a colour. Kendrick Kay and colleagues recently found a way of decoding fMRI images that, they say, makes it “possible to identify, from a large set of completely novel natural images, which specific image was seen by an observer… it may soon be possible to reconstruct a picture of a person’s visual experience from measurements of brain activity alone” ().
Now Cephos says its scans can tell, with 97 per cent accuracy, whether someone is lying (4 October, p 8). Even if this is over-optimistic, brain imaging seems likely to be a more reliable test of truth-telling than the intuitions of a dozen jurors. Yet you warn: “Let’s hope [the judges] are wise enough not to be seduced by a machine that claims to determine truthfulness at the flick of a switch” (4 October, p 5).
As well as being prejudicial, this reaction encourages the notion that mind is “spirit stuff” and therefore beyond scientific investigation. Could some kind of unconscious dualism be at work?
From Kenneth Ramsay
A more rigorous study into the effectiveness of such techniques would be to advertise for volunteers who will put their own cash on the line, with the possibility of winning more if they beat the machine. This would put “real-world” pressure on.
Another benefit of, say, a 拢1000 stake to win 拢10,000 (which with 90 per cent accuracy would break even) is that it would attract real gamblers, lawyers, stockbrokers and others who I suspect are “socialised” psychopaths 鈥� who may be under-represented in tests to date.
If the device can hit 97 per cent accuracy, Cephos could run the first profitable peer-reviewed study. I might even watch it on TV.
Glasgow, UK
Dieldrin and diabetes
Phyllida Brown discusses possible interactions between persistent organic pollutants (POPs), human body fat and diabetes (13 September, p 36). I learned of the connection in 1987. The Victorian Department of Agriculture here in Australia had recommended the POP dieldrin to control wireworm in potato fields 鈥� and then found it in the meat of cattle later grazing those fields.
I suggest that fat people are able to retain much higher levels of POPs in their body, and so suffer the diabetes-inducing effects for longer. And I fear that a whole generation of humans ate high levels of lipophilic organic phosphates in meat before food authorities reduced the levels deemed acceptable.
Forest peoples' rights
Hunter-gatherers in the Congo basin will be happy to hear that international conservation organisations are finally realising how important they are to the conservation of tropical wildlife (20 September, p 6). Baka Pygmy communities were hunting sustainably in forests recently overlapped by the Boumba Bek and Nki national parks in south-east Cameroon long before biological researchers arrived to find such abundance on their lands. It was the Baka who first showed the researchers around.
The arrival of big conservation organisations coincided with the introduction of boundaries and rules, and violent repression against their communities by forest guards. Funds from well-meaning people in Europe and North America are still helping to pay for these violations of indigenous peoples’ rights.
To conserve wildlife, the Baka are demanding to become recognised as the main guardians of their forests 鈥� a development that would be in accordance with widely agreed conservation principles and intergovernmental agreements. Conservation organisations in Cameroon have since accepted revised management plans in the Campo Ma’an National Park, allowing Bagyeli Pygmy communities to go back to hunting and gathering in their traditional hunting grounds. Surely it is time for international conservation organisations to put these principles into practice everywhere.
Electric caveats
While electric cars are promising, your graph greatly overstates their greenhouse gas emissions advantage (20 September, p 26).
I estimate that it shows the tailpipe emissions of a conventional vehicle as about 210 grams of carbon dioxide per kilometre, and of a hybrid vehicle as 140 grams per kilometre.
But The Economist magazine (6 September) listed the mean emissions of CO2 per kilometre for the European “fleets” of various manufacturers as 160 grams/kilometre. You must have used US conventional vehicles as your comparison.
Even the thirstiest European vehicles look good by that standard, and many mass market cars beat plug-in hybrid vehicle performance if fossil-fuelled electricity is used. I have logged the fuel consumption of my 2005 Volkswagen TDI car as 120 grams/kilometre over its 70,000 kilometres (53 mpg or 5.3 litres/100 kilometre) and a 2005 “smart” CDI as 103 grams/kilometre over 40,000 kilometres (63 mpg or 4.5 litres/100 kilometres).
When you describe the advantages of a new technology, please do not use the worst alternative as a comparison, and please take “feel-good” stories from the US with the proverbial pinch of salt.
Jim Giles in his article on electric cars is wired too fast to ideas from the past about mobility. Who needs 1.5 tonnes of material to propel 75 kilograms of average person over a distance of some 5 to 20 miles from front door to factory gate 鈥� at 200 kilometres/hour?
Where did Giles get this idea of anything more reasonable being no more than a “pootling golf cart”? The real lean and mean stuff would be vehicles such as the TWIKE, a three-wheeler that seats two people, does up to 85 kilometres/hour, and will be good for some 60 to 150 kilometres depending on the number and type of batteries installed.
I have driven one since 2002, and have now ordered the “active” type. At about 280 kilograms, it weighs no more than stability demands. The full power of a 5-kilowatt machine is available at all speeds, so even this midget gives you some oomph at the traffic lights. Maneouverabilty is excellent by means of a walking-stick type joystick that keeps no more than two fingers busy from time to time pushing a key for acceleration or deceleration; both can be given a short nudge to keep the speed constant without further fingerwork. And yes, you’ve guessed it: deceleration means recuperation of electricity at the same time. Once you’ve got used to weaselling about in a TWIKE, the lonely brake pedal will be all but orphaned.
Your mention of General Motor’s Chevy Volt brings to mind a television piece several decades ago. As a project, some polytechnic students built a car with a 500cc motorbike engine which ran at its most efficient speed, driving a generator. The generator charged two banks of car batteries which powered the pair of electric motors attached to the back wheels. As I recall, it produced the performance of a 2-litre engine and delivered 100 mpg (2.8 litres/100 kilometres).
Does anyone else remember any details about this?
Thirty years ago, as an automotive development engineer, it occurred to me (as it undoubtedly did to others) that a petrol-electric hybrid would make a very suitable commuter car. There was no need for an expensive prototype; all the relevant design parameters had been established for many years. At the beginning of the 20th century there were more electric cars on the road than petrol-driven ones.
I asked my colleagues to drive their cars to and from work, trips of 20 to 30 kilometres in areas including freeways but little or no bumper-to-bumper traffic, restricting their speed to 50 kilometres/hour top speed during peak hour. The consensus was that there was hardly any difference in travel time.
I also asked them whether they would buy one of my projected commuter cars which would probably yield an economy of 4 to 5 litres/100 kilometres. The consensus was that they wouldn’t be seen dead in a vehicle that couldn’t “pull the skin off a rice pudding”, a task which I had admittedly not included in my specifications.
Jim Giles’s article displays precisely the same attitude: it quotes the usual merit figures of a top speed which is unachievable and illegal, at a cost which makes one’s hair stand on end. There is the usual confusion of kilowatts and kilowatt-hours. Even the old horsepower gets mentions, although horses nowadays pull cars only in emergencies. Accidents and traffic-jams don’t exist in this Boy’s Own world.
Giles proves, once again, that the motor car is not only unsuitable as a means of mass transport, but it also breeds an attitude which ensures that reality doesn’t get a look-in.
Blackburn, Victoria, Australia
I have been following the evolution of the electric car with some interest. The latest cars are environmentally friendly, economical and fast.
The only downside so far seems to be accidents caused by people walking into the path of a “silent” car.
A one-liner in a recent magazine article started to ring alarm bells. It is proposed that a noise generator be added to these vehicles to warn pedestrians of their approach.
Simple enough? No. Beware… Remember when mobile phones had one ring tone? Remember the “crazy frog”? The evolution of ring tones took a while.
So you think the “noise” added to your electric car will be an electronic version of an engine. Think again. The crazy frog could make a comeback, or any manner of other noises could be introduced.
Imagine the worst-case scenario. Two modified electric cars meet head on in a narrow lane, and both have the latest modified engine noise of Ozzy Osborne going full tilt.
Sunningdale, Berkshire, UK
Fantasy bankers
Rob Jameson describes William Perraudin saying that developing a model to cope with feedback in economies is “fiendishly difficult” (27 September, p 8). No, it isn’t. It is impossible. Economies are monumentally chaotic, representing the financial antics of millions of us, and thus susceptible to our well-known tendency to make decisions for the strangest and most irrelevant of reasons.
True, when everything is calm, “trends” can be picked out of the plethora of figures, but these have as much predictive capability as a horoscope and they disintegrate as soon as a “Black Swan” appears. So what to do? Be it household or country, those responsible for the purse strings should work to Micawber principles 鈥� spend less than you earn 鈥� and those lending money should lend only to those who can reasonably be expected to pay their loan back. Any chance of a Nobel prize for this vivid insight? I could use the money.
Fly-by chaos
Marcus Chown writes about possible sources of the anomalies in spacecraft’s fly-by velocities (20 September, p 38). Surprisingly, he does not mention that calculating the interaction of the Earth, moon and spacecraft is a three-body problem, doable only by iterative approximation, and tends to chaos. Could the anomalies arise from errors in the approximations?
Sweet success
Walter Mischel’s experiment to determine whether 4-year-olds could resist marshmallows was interesting, but his conclusions were wide of the mark (13 September, p 40). The children who had two marshmallows did better in life than the children who had one. So marshmallows are essential for a child’s development, and two are better than one. Indeed, I would encourage all those who were denied that crucial second marshmallow to mount a class-action suit, as may those in the control group in any experiment who are fed placebos while the more fortunate are cured by the miracle drug under test.
That said, is it too late for me to gorge on marshmallows and become happy and successful?
Bat mobile
Perhaps the answer to bats exploding in low-pressure vortices at the tips of wind-turbine blades (30 August, p 4) is to fit the blades with . As I understand it, the winglets attached to the ends of aircraft wings increase efficiency by reducing vortex formation. So perhaps winglets would not only help to reduce bat deaths, but also increase efficiency. Of course, they might just present another sharp edge to chop up passing birds.
For the record
鈥� The paper by Mile Gu and colleagues on emergent properties of Ising lattices is at (4 October, p 12).
鈥� We said ambiguously that “a molecule released by bacteria called lipopolysaccharide seems to initiate tolerance” to bacteria (27 September, p 16). To clarify: lipopolysaccharides are a class of molecules.
鈥� We seemed to say both that pterosaurs weighed up to a quarter of a tonne and that they were four times heavier than a 22-kilogram albatross (4 October, p 10). We meant to say that members of the extinct teratorn family of birds weighed up to 88 kilograms 鈥� which is more than the proposed 40 kilogram limit for flight.