Letter
While it pains me to be cynical, my instincts tell me to follow the money and ask who profits from time spent online. If collecting spam with my regular e-mail doubles the time that I spend online to my internet service provider, then it doubles the value of my email-related business to my phone provider and, I assume, to my ISP. Small increases in individual spend translate to large increases in revenue to the companies involved.
Unbelievable Bayes
Robert Matthews talks of the connection between belief and Bayes’s theorem (13 March, p 38). He seems to think that, because you have to start with some arbitrary level of belief in order for Bayesian reasoning to work, it follows that different people starting from different points, and looking at the same evidence, might never come to the same conclusions.
In fact this point was addressed in your previous feature on Bayes’s theorem (22 November, p 36). There it was pointed out that the system was largely insensitive to the initial arbitrary starting probability. No matter where you start from, you will still converge on the truth.
Alternatively, consider that Bayesian reasoning can be applied to any kind of belief in the face of evidence, including belief in the validity of Bayesian reasoning itself. If it were possible for people starting with different assumptions, looking at the same evidence, to come to different conclusions about the validity of Bayesian reasoning, then that would make the validity of Bayesian reasoning itself completely subjective, according to Matthews’s own argument.
Which means his argument itself is built on an entirely subjective basis, and is not to be taken seriously.
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Dominic Dickson, coauthor of the “Physics karaoke” paper, gave a very enjoyable colloquium in York a few weeks ago. It even resulted in the next third-year homework assignment being to write karaoke songs.
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Why not? Ask Lynda Williams, the Physics Chanteuse. It has already been done. See her web page at .
I'm watching you
No doubt everyone has their anecdotes about remote staring, but here is some systematic observation (13 March, p 34).
While invigilating examinations, I sometimes pass the time by staring at a student with head down hard at work, willing him/her to look up. Result: nothing. However, at other times when my mind has wandered off into a trance 鈥� which is not hard when invigilating 鈥� I have found myself staring vacantly at a student without my being conscious of it. Guess what: the student looks up. It works nearly every time.
So if remote staring does have any effect, I conjecture that it may have to do with the “sender” being in a state of mental unfocus while the “receiver” is in a state of high focus or possibly scanning around for mental input.
Have Richard Wiseman and Marylin Schlitz tried this one? They are welcome to invigilate a long exam for me any time they like.
All together now
I think Feedback has unfairly dismissed a splendid idea (27 March). Physics karaoke is a brilliant concept, if only for the fun that can be had converting songs into science.
However, this is not a new idea. The Biochemist’s Songbook by Harold Baum sets major biochemical pathways to familiar tunes, and includes such gems as The Michaelis Anthem (to the tune of Tannenbaum 鈥� better known to British socialists as The Red Flag), and a splendid account of protein synthesis to My Bonny Lies Over the Ocean. When I was an undergrad I found them handy for recalling pathways that so easily escape one under exam conditions, although this did involve a certain amount of furious humming.
Finally, none of us should forget that Michael Flanders and Donald Swann got there first with their song about the first and second laws of thermodynamics.
Red light reactions
The “vibrating accelerator pedal” is a clever device and it is easy to see how designers would be seduced into including in it ever more complex and comprehensive features (20 March, p 24).
But consider this. Motorists who see a red light 200 metres ahead and simply roar up to it and slam on their brakes fall into one of two categories: the ignorant and the stupid. Ignorance is cured by a little education: a simple explanation of the benefits to fuel consumption, tyre and brake wear, not to mention personal stress levels, of lifting the foot off the accelerator.
Stupidity, on the other hand may be incurable and those drivers too dim to see that a red light in the distance means “start slowing now” are unlikely to take any notice of a vibrating pedal telling them the same thing.
Better safe than sorry
As a retired medical physicist who was formerly much involved with the diagnosis and treatment of thyroid illnesses, I think your article gave a misleading impression of the situation, and risks causing patients undue alarm (6 March, p 10).
Some decades ago, patients with Graves disease would undergo a series of diagnostic tracer tests to establish the size of the gland, the distribution of radio-iodine, and the uptake and rate of turnover. They would then be given a treatment dose of iodine-131 that was tailored to each patient individually, with the aim of producing a euthyroid state. But it was found that this could leave the patient in a hyperthyroid condition, requiring a second treatment dose.
So more recently, as your article reports, medical opinion has swung in favour of giving most patients an “ablative dose”, which will quickly correct the overactive thyroid and within weeks produces a hypothyroid state, which can be easily controlled by a maintenance dose of thyroxine.
Endocrinologists, aware of possible heart problems associated with long-term overactive thyroids, often preferred this approach as giving a more certain outcome. The quantity of radio-iodine would generally be larger than that calculated to produce a euthyroid state, and this is what your article picks up on.
The decision to use an ablation dose rather than a dose tailored to an individual patient has to be made on clinical grounds, and it would be wrong to call it an overdose.
Having said that, if I were to suffer from hyperthyroidism, I would prefer to be given a dose tailored to produce a normal thyroid, without having to rely on the lifelong use of thyroxine.
Don't open spam
It has certainly not been my experience that URL links to the advertisers in spam messages are inactive, nor would I recommend that others emulate Noel Hodson’s investigation of these links (13 March, p 30). The latter point is a matter for the urgent notice of all but the most masochistic or lonely of email users.
The notorious spammer Alan Ralsky boasts that his messages detect when a reader opens them, and register yet another “live” prospect. This could be used to generate a marketable list of confirmed active email addresses of people who are prepared to view spam. Anecdotal evidence suggests that the practice may be widespread, as indicated by a rapid increase in spam volume reported by those who open their spam or even who just preview it, and by the reduction when they cease the practice.
I have checked around 2000 spam messages received in a little less than three months and found that the majority of links are indeed active and are, little doubt, being used to target further “hits” on incautious visitors. The notable exception is the “opt-out” link sometimes provided. That is very often fake or inactive.
My time zone is well in advance of GMT, whereas most of the spam I receive is aimed at North America, which is well behind GMT. This could partially explain the difference between my experience and Hodson’s. It could be that, for people targeted in their own time zone, some of the “spamvertised” sites have already been taken offline by their web hosts by the time the spam is opened.
Publish or be damned
Mark Davies’s idea that ethics committees should insist that results of clinical trials be published is an admirable one (27 March, p 30). But the pressure needs to be applied to the journals as well as the scientists.
I know from bitter experience that it is almost impossible to get a “treatment has no effect” result published in a journal with a respectable impact. This is unethical in that it results in experiments on humans and animals not being published. It also leads to a waste of resources, as treatments that have been exhaustively tested and rejected are tested again by researchers who have no way of accessing the results already in existence.
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Legislation in Spain, due to take effect on 1 May, will oblige drug companies to publish in scientific journals all the findings 鈥� both positive and negative 鈥� of the clinical trials they sponsor in this country. The law also states that the results of research on medications, when published, are to be accompanied by information on the funds (and their source) obtained by the authors for performing the research. Moreover, the new law establishes stricter procedures for the oversight of clinical trials by local clinical research ethics committees and a national coordinating centre.
Drug companies may be unwilling to comply with voluntary guidelines if they think that openness might hurt sales. But once patients who participate in clinical trials get used to the sort of transparency and reporting of results required by European directive 2001/20/CE, companies may be more inclined to follow voluntary ethical guidelines. Failure to do so could undermine consumers’ trust in their products.
Burn-out
I was very interested in Timothy Noakes’s “central governor” idea of protective fatigue discussed in the article “Running on empty” (20 March, p 42). It seems to fit with some of my experiences of steady exercise.
However, it doesn’t seem to square with the condition of sudden exhaustion well known to cyclists (especially myself as a rather unfit example) as “bonking”, in which the victim suddenly, and with little or no prior fatigue, feels completely drained of energy, shaky and almost unable to continue. I’m no physiologist, but I believe this is a hypoglycaemic state, as taking in plenty of glucose and water brings about rapid recovery.
What interests me is that there seems to be no protective fatigue prior to the onset of exhaustion here. I wonder how this would fit with the ideas discussed.
Timothy Noakes replies:
鈥� We are actively researching this question. We have found that there are two responses to reduced liver glucose/glycogen stores 鈥� the ultimate cause of the symptoms Smaje describes.
Athletes who are on a high carbohydrate diet and who take in carbohydrate during exercise will usually stop when they experience some of the symptoms that you describe, but with almost normal blood glucose concentrations. The governor can be said to work well in their case, as it terminates the exercise before chemical hypoglycaemia develops.
In contrast, those who do not eat a particularly high-carbohydrate diet, or who do not take in carbohydrates in training or in competition, are likely to have very low blood glucose concentrations when they reach the point of exhaustion. Clearly the governor has failed to stop these exercisers prior to system failure.
Interestingly, the fact that glucose ingestion rapidly reverses these symptoms provides good evidence for the action of a brain controller sensitive to either blood glucose concentrations or liver glycogen stores, or the rate of liver glucose production, or combinations of any of these variables.