91av

Paul Davies's article about extraterrestrial messages embedded in DNA resonated with me, because on 29 October 1999 I sent a letter to 91av that covered the same idea from a slightly different viewpoint (7 August, p 30) . Perhaps if I had spelled it out in more detail – especially the final paragraph – …

Instead of spending millions fighting bootleggers, the movie industry could easily save the money and divert the bootleggers' revenue to itself at the same time (14 August, p 22) . People who buy bootleg movies clearly do not mind watching poor-quality films as long as they get them cheaply and as soon as they are …

Rob Hawarth is right to point out that, thanks to Feedback's article on googlewhackblatts, a search for alapacoid now brings up two results (31 July, p 24) . On the other hand, when spelled correctly, alopecoid (meaning fox-like) brings up 1960 results.

There is an attraction in the solar "power tower" in that it may be, at the moment, more cost-effective than conventional photovoltaics. However, it is considerably more expensive than wind power and likely to be overtaken by other solar technologies even before it is completed (31 July, p 42) . This would not be a …

Your description of what goes on in a fast breeder reactor is incorrect (7 August, p 26) . Fissionable plutonium is not produced by reactions between plutonium, uranium-238 and other uranium isotopes. It is produced by irradiating uranium-238 with some of the fast neutrons released by uranium-235 and plutonium-239 as they undergo fission. This converts …

Your Feedback item about a supermarket placing 13 types of trolley at customers' disposal, which I am sure to the initiated is quite amusing, is absolutely incomprehensible to me (7 August) . Say "trolley" and I think of an electric rail-car running along tracks, often set in a street, and obtaining power from overhead lines …

I hope you will be interested to know that John Martinez, the US importer of kopi musang (the coffee made from beans that have passed through a civet cat's digestive tract), was awarded the Ig Nobel prize for nutrition in 1995, so his contribution to relations between the common palm civet, Paradoxurus hermaphroditus, and humans …

• We mistakenly attributed a comment in the article "Bug-based sensors raise the fire alarm" (7 August, p 20) to Dan Lang of the California Department of Forestry and Fire Protection in Sacramento. We wrote: "Lang envisions hundreds of cheap 'beetle-based' sensors being deployed throughout forests, perhaps with wireless links to a central computer, to …

Your leader repeats the tired moral cliché that people will always pick a child over an animal (7 August, p 3) . This simply isn't so. In the UK this year, we will spend around £2 billion feeding, pampering and providing medical care for our pets while 10 million children will die across the world. …

Why doesn't Tam Dalyell tell the health minister that the UK's medicines regulator and Committee on Safety of Medicines (CSM) have failed over SSRI drugs (14 August, p 45) ? It took two exposés of the effects of Seroxat by BBC TV's Panorama to force the current review. In March, Richard Brook, the chief executive …

You report that perhaps 3.5 per cent of US teenagers use steroids. You also suggest that the experiment you describe had very few adverse effects. What then is the fundamental problem with steroid use among ordinary people? Perhaps rather than fighting it, it would be better to regularise the practice by authorising doctors to prescribe …

It is extremely disappointing to read that the scientific community has responded to the perceived shortage of primates by focusing attention on how the supply to laboratories can be increased to satisfy demand (21 August, p 6) . The RSPCA believes that science, industry and regulators are too ready to take the view that primate …

Your article about cheating in athletics (14 August, p 6) stated that no rigorous study of the effects of performance-enhancing drugs took place until 1996, but I can tell you that the first attempt of which I am aware was some 30 years earlier. It took place in Leeds General Infirmary in the late 1960s …