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Ralph Ellis' letter points out only half the fallaciousness of British government policy relating to wind power (22 March, p 30) . The assumption that a small reduction in carbon dioxide emissions might influence climatic change has been the reason for deploying these machines. However, as spinning back-up is needed to cope with intermittency, the …

• The formula given in the Spambusters features (8 March, p 44) for calculating the chance that a particular email is spam follows from Bayes's theorem only if two conditions apply: overall, 50 per cent of emails are spam; and among both spam and non-spam, the instances of words such as "rich" and "Viagra" are …

Are Gerald Haug's findings about the Maya really news, or just confirmation of known facts (22 March, p 19) ? My copy of Michael Coe's classic – and hardly obscure – The Maya (1999) makes precisely the same case in the last three paragraphs of the introduction as that reported by you. Specifically, Coe cites …

Terry Allen's article (1 March, p 25) presents many examples of false perceptions with regard to the effects of depleted uranium (DU) ammunition, yet makes no mention of the significant body of independent work which refutes many of these. In your so-called "battle for truth", only one side is represented. Many independent reports have been …

Emma Young's article says that software manuals rely solely on information from the computer programmers who write the software (22 February, p 19) . This is not entirely true. Technical documentation is developed in two basic ways. One is somewhat similar to what your article describes: the developers hand over a functional specification to a …

The BBC's teletext Sci-Tech news item for Thursday 20 March referred to your magazine as follows: "According to the Â鶹´«Ã½ magazine, repair enzymes which heal the body may be able to travel by electrical charge." The writer then states: "This would help to explain why acupuncture is able to exploit energy pathways to heal …

In your article about junk mail and the Bayesian junk mail filter (8 March, p 42) you neglected to mention one of my favourite mail clients: Apple's Mail ( www.apple.com/macosx/jaguar/mail.html ). Apple's program uses a filter that combines the Bayesian and Boolean methods, and by this means manages to find 99 out of 100 pieces …

We are told that only 4 per cent of the Universe is made of baryonic matter that we can observe, and that the remaining 96 per cent of the Universe is "missing" (22 March, p 40) . Perhaps someone or something else is sitting out there trying to figure out where the missing 4 per …

Your article on SUVs was enlightening, and deeply disturbing (8 March, p 12) . It also seems incomplete, as there is no mention of injuries and fatalities inflicted on pedestrians and cyclists. It seems probable that being hit by an SUV, at whatever speed, is going to be worse than being hit by a car. …

I must take issue with the description of Zimbabwe's CAMPFIRE programme as "successful" in your article on the best use of conservation funds (1 March, p 32) . Research on the programme carried out a few years ago by USAID, the US government's international development agency, concluded that without the millions of American aid dollars …

In his enthusiasm for ridding the world of mosquitoes, Oliver Morton seems to have forgotten the simple ecological fact that all species have an effect on the community around them (22 March, p 32) . If the mosquito and the diseases it carries are made extinct, there will be an unknown effect on various wild …