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The ideas for efficiency improvements in trucks described by Phil McKenna are welcome – if late (15 August, p 34) . However, the realities of road haulage were not adequately addressed in the article. In the UK, hauliers feel compelled to maintain a fleet of the biggest vehicles permitted, in order to be seen as …

Clive Semmens discusses the practicalities of producing electricity in your home (18 July, p 27) . These vary from country to country. Here in Jamaica, I quite easily generate some 2 kilowatt-hours per day to supply my house, but I do so via a huge ex-forklift battery that weighs nearly 800 kilograms. The grid is …

In his thought-provoking essay, George Marshall suggests that action on climate change is going to be difficult to achieve until the population has a shared belief (25 July, p 24) . But is such a shared belief something we can realistically hope to achieve? Is it a prerequisite to taking action, collectively and individually? In …

In his letter (15 August, p 23) , Peter Carr challenges research showing that hermit crabs feel and remember pain (11 July, p 24) on the basis that "internal pain receptors would be pointless" ina crustacean, as the damage has already happened when the shell is penetrated. Pain is not only a powerful prompt to …

Proponents of the electric car studiously avoid discussing the problem of refuelling (18 July, p 42) . If we want electric cars to have anything like the performance and versatility of internal combustion ones, they have to "refuel" reasonably quickly; the idea of exchangeable battery packs is an environmental and practical minefield. A 60-litre tankful …

• It was Miguel Nicolelis's group at Duke University in Durham, North Carolina, who implanted electrodes into the brains of macaque monkeys (29 August, p 14) . Dietmar Plenz, who we wrongly credited with the technique, analysed the resulting data.