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Andy Coghlan asks: "After decades of clinical failures and ethical controversy, could 2008 mark a new dawn for artificial blood?" (5 January, p 11) . Unfortunately, I can't see how it will mark an end to ethical controversy, since the article goes on to say that the new substitute uses "haemoglobin extracted from cow blood". …

Your article on brain training included the puzzle below (12 January, p 26) . You give the answer as 53, apparently by numbering the rows and columns starting at the bottom right corner, and appending the row number to the column number. Another solution would be: the first digit in one column plus the first …

• The bee in the illustration to the article "Where have all the honeybees gone?" (22/29 December 2007, p 22) was not a honeybee, but a female solitary mining bee of the genus Colletes . • We misnamed Kanav Kahol of the Banner Good Samaritan Medical Center in Phoenix, Arizona, who researched surgeons' performance after …

"It is time to put science back in charge" states the one-man bandwagon Gary Taubes (19 January, p 17) . Despite the fact that "we are overeating" it seems that dieting does not work. But blaming the theory is not helpful. If a patient is prescribed penicillin for an infection and neglects to take it, …

Your article about the lack of suitable non-gendered third person pronouns and the neologisms various sub-cultures employ as substitutes (5 January, p 7) ignored the simplest solution of all. I have noticed a growing prevalence, at least in written essays, of substituting the plural form of the pronoun for the singular. In much the same …

David Peat's article on language and physics (5 January, p 42) was most timely, given that languages are going extinct at roughly one per fortnight. About 5000 distinct languages remain, but comprise only a few dozen unrelated groups. Languages such as Algonquin, Gilyak (spoken in Outer Manchuria) or Nama (spoken in Namibia) contain treasures of …

It is interesting that you report on the risk of hydrogen-fuelled vehicles colliding in tunnels (10 November 2007, p 29) . Six years ago I discussed the infrastructural changes that will be necessary to support a hydrogen vehicle economy, at the Fuel Cells Summit V meeting at the University of Maryland in the summer of …

A gender bias in publication of refereed articles (19 January, p 7) ? Does that really happen? Well, there was that time when a journal that did not use double-blind refereeing sent back the reviewers' comments and judgement to reject, not to little old first and corresponding author me, but to the second, male, author. …

So we're too clean? Let's have an injection (12 January, p 34) ! Is that the logical answer? Or could the products we use to keep ourselves so clean be implicated in causing the cancers that follow? We must learn to think rationally. If we keep adding to our complex world, rather than simplifying it, …

Instead of waiting on artificial intelligence to analyse data gathered by animal reality-TV cameras (19 January, p 22) why not use human intelligence, which is already available – and much of which is wasted in watching human reality-TV shows? If you put the raw footage online with some instructions, you might be surprised how many …

Lawrence Krauss, commenting on the US presidential hopefuls, says "reason has to be the key basis of political decision-making" (5 January, p 45) . While I acknowledge that every branch of science intrinsically requires reason as its primary platform, reason alone is not a satisfactory basis for management of a laboratory, let alone the government …

Jeremy Tomkinson says that biofuels "are the only available near to medium-term options for reducing vehicle exhaust emissions" (19 January, p 18) . Not so. Reductions in national speed limits, firmly enforced, would have an immediate and permanent effect.

The UK government has finally given its backing to a new nuclear energy programme (19 January, p 6) , presumably in response to ongoing concerns over climate change and security of supply. Setting aside the debates about economics, uranium availability or the somewhat controversial matter of whether nuclear power stations are really carbon-neutral, there is …

I was absolutely disgusted to read about the cuts in funding for physics projects in the UK and the US ( 19 January, p 5 and p 8 ). An £80 million cut for British physics is, frankly, ridiculous, and it only adds insult to injury that it comes after increases in funding had been …

Gary Taubes is right to question whether we get fat because we overeat, or overeat because there is some regulatory or hormonal phenomenon that drives us to fatten (19 January, p 17) . Whether he is right to pin all the blame on stimulation of insulin secretion by refined carbohydrates is another matter. There are …

It was good to see your comment that we need to consider the genes that are being deployed rather than the technique used to introduce them into crops ( 5 January, p 3 and p 28 ). However, we were puzzled by the claims that crops with increased drought or salt tolerance "might create highly …