Letter
In the mid-1960s, the pub next door to the BBC’s Riverside studios in London changed its name to Studio 3. I remember telephoning someone who I thought was working in Studio 1, to be told that “He’s in Studio 3”. It wasn’t till I had put the phone down I remembered that there were only two real studios.
Letter
We’ve had a pub called The Bank in the financial quarter of Bristol for some years. Glad to see the rest of Britain catching up.
Millennial archives
When people are considering archiving music, films or books, why do they so often talk in terms of lifetimes of hundreds of years (1 March, p 40)? Is it too forlorn a hope to raise the possibility that humans might still be here in a million years or more, and that they might be interested in hearing about us?
What is needed is some form of reasonably foolproof digital recording and archiving system with a projected lifetime of at least thousands of years, and preferably millions. It should ideally use no compression (or at worst, a “lossless” compression scheme) and be recorded on a totally inorganic medium, perhaps something like laser-cut holes in a pure gold layer on quartz discs.
Gobbling up cells
I read with interest the article by Nektarios Tavernarakis on cell death (15 February, p 30).
This is certainly a fast-moving field, in which genetic studies on model organisms such as Caenorhabditis elegans and drosophila have given us fundamental insight.
Yet the author is incorrect when he refers to necrosis not being described until about 15 years ago. The distinction between apoptosis and necrosis in mammalian systems was recognised by researchers such as John Kerr and Andrew Wiley at least 10 years earlier.
The author is also incorrect in saying that after apoptotic cells die they are gradually dismantled and assimilated into surrounding cells. The main purpose of apoptotsis is for the cell to become a bite-sized morsel that can be engulfed by another cell and digested. Mammals have professional “undertaker” cells, the macrophages, to perform this function.
The really interesting question is how the undertakers can sense a dying cell from a distance, and recognise that it must be eaten. There are a number of recent publications dealing with the nature of the “eat me” signal.
One key difference between apoptosis and necrosis is the failure in the latter case of a process that would normally permit the orderly removal of the corpses of the dead.
Lumpy Earth
The article on volcanic hot spots and how they might be formed did not mention the effects on tectonic plates of the curvature of the Earth (8 March, p 32).
Our planet is an oblate spheroid, with a polar radius 21 kilometres less than its radius at the equator. This may not sound like much, but it means that the summits of Chimborazo, at 6310 metres above mean sea level, and Kilimanjaro, 5895 metres, which are both on the equator, are actually farther from the centre of the Earth than the top of Everest, which is 8848 metres above sea level but at 28掳 North.
As tectonic plates move around the globe, could the stresses caused by changes of curvature as they change latitude cause them to fracture, providing weak points for magma to reach the surface?
Centripetal rules
Oh, dear, centripetal or centrifugal force, that old chestnut (15 March, p 28). Consider the following mind experiment. You are in a lift with your letter writer Alan Calverd’s stone on a string. The string is hanging down, and there is tension in the string exactly balancing the force of gravity.
Now the lift accelerates upwards. You feel heavier. The tension in the string increases. But there is no increase in the downward force, and the increase in the tension is causing the stone to accelerate upwards. Remember Newton: a body stays at rest or continues to move in a straight line unless acted on by an external force.
Now consider the stone being spun round on the end of the string. There is tension in the string (the centripetal force) but there is no centrifugal force opposing it to keep the stone in equilibrium, any more than there was when the string-stone system was in the accelerating lift. The stone is not in state of rest, nor is it travelling in a straight line with constant speed: it is being acted on by an external force (the tension in the string) and so is accelerating along the direction of the string, towards the centre of the circle of rotation.
If the lift could be rotated in this way, and you were inside it, you would feel heavier for exactly the same reason you feel heavier when the lift is accelerating upwards. As the original article in The Word pointed out (1 March, p 47), this is counter to common sense, but then so much science is. That is what makes it challenging and interesting.
Letter
Alan Calverd is wrong to say that the centripetal force is balanced by an equal and opposite centrifugal force. If it were, then a stone being whirled round on a length of string would continue in a straight line, as indicated by Newton’s first law.
To follow a circular path, the stone requires an unbalanced force perpendicular to the motion.
Exact weight
I really enjoyed your article on basic units (22 February, p 32). Contrary to what some of your readers’ letters have said (8 March, p 29), it is possible to arrive at definitions of the ampere, the candela and the mole that are independent of the kilogram.
A single ampere represents 1 coulomb moving past a single point in one second. The coulomb can be expressed as the charge of 6.24 脳 1018 electrons.
Until 1979, the candela was defined as the luminance of a Planckian black-body radiator at the melting temperature platinum (a black body being a theoretical object that completely absorbs all incident radiation and also emits electromagnetic radiation at all wavelengths, the emitted radiation being related to its temperature by Wien’s constant).
The mole is related to a constant whole number. Although defined as the number of atoms in 0.012 kilograms of carbon-12, it can also be defined as the amount of substance in which the number of elementary entities is equal to Avogadro’s constant, which is approximately 6.022 脳 1023. This can be applied to any elementary particle, so we can have a mole of atoms, a mole of molecules, a mole of electrons, and so on.
So why is it not possible for the kilogram to be defined as the mass of the number of carbon-12 atoms equal to (1000 梅 12) 脳 Avogadro’s constant?
Placebo or con?
As the originator of the crystal homeopathy hoax, I have no problem with crystals acting as placebos, despite what Peter Carroll suggests in his letter (15 March, p 29). What I do have a problem with is people insisting that different crystals have specific “energies”, and citing pseudoscience to support their claims. I have an even bigger problem with some people charging 拢100 a session for crystal healing.
As for tricking snake-bite victims into believing they have received a treatment, I don’t think it is the placebo effect that is at work here. Rather, it may help the doubtless agitated and desperate-for-treatment individual to calm down, which is likely to ease the panicky heartbeat and slow the spread of the venom. It will also make the victim’s last moments on Earth look more dignified.
Beauty of biodiesel
The article on using jojoba oil to fuel cars and trucks described something that sounds suspiciously like biodiesel (8 March, p 18). Biodiesel is also made from vegetable oils, using a catalyst (lye) and an alcohol (methanol) to produce a methyl ester and glycerol. An article on the website shows you how can make it yourself, or you can get more info from the biodiesel folks:
Any long-chain fatty acid can be made into a fuel. Where I live, there is plenty of corn, peanut, soybean and sunflower that will do the trick. Biodiesel is the only alternative fuel that has been approved by the Environmental Protection Agency.
Back to Morse
Some years ago, a colleague and I helped someone with a similar problem to that of Hans-Peter Salzmann (22 February, p 36). At the time, she was using a sequential selection device known as Possum to write books and we devised a system based on Morse Code to speed letter selection.
The structure of the Morse alphabet assigns the shortest codes to the most frequently used letters, and appears to be an almost optimum solution. The ternary system used on mobile phones is a very frustrating input method as it is not letter-frequency optimised.
I'm at the office
Pubs called The Library and The Office are good destinations on weekdays (Feedback, 8 March). For Sunday, what could be better than The Chapel, in Coggeshall, Essex?
Letter
There is a pub opposite the Royal Infirmary in Edinburgh called The Doctors. My wife was quite alarmed when our son, a medical student at the time, rang her and said that he was “at the Doctors”.
Pay for spam
Filters will never solve the problem of spam, just help to manage it (8 March, p 42). I use a Bayesian filter inspired by Paul Graham’s article “A plan for spam” (). It works quite well, but I still have to review every message it labels as spam because it does make mistakes. A better solution is needed 鈥� and I suggest that the answer is to make spammers pay.
With real mail, the sender pays the cost of printing and delivery. This gives senders a strong incentive to maintain an accurate mailing list of people actually interested in their product or service.
Not so for spam. Send one spam or a million and the cost is the same. There is no incentive for the senders to vet their mailing lists, so they just let them grow. If we made senders pay a small charge for every email, even $0.001, spam volume would drop dramatically and the spammers’ collections of undifferentiated email addresses would be rendered worthless.
I would gladly pay for every message I sent if it meant that I did not have to deal with so much spam: 112 in past three days.
Problem with HRT
The article highlighting the link between hormone replacement therapy and breast cancer made the usual mistake of using the word “progesterone” as the name for groups of synthetic progesterones that are properly called progestins or progestogens (8 March, p 8).
Progestins have a different molecular structure from natural progesterone. Some researchers say the side effects are specific to progestins. The pharmaceutical industry says it uses progestins for HRT so that the medications can be taken orally.
Synthetic hormones identical to those the body produces 鈥� sometimes called natural hormones or bio-identical hormones 鈥� are available on the market. In Australia they are sold on prescription in the form of creams. But it is difficult to get a prescription if your doctor doesn’t know anything about them, and as far as I am aware they have never been tested in large-scale trials. And, of course, the creams would not be patentable, so the pharmaceutical industry does not seem to be interested.