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I was encouraged to read that the National Health Service in England is taking the need to develop IT-based healthcare seriously ( 24 August, p 9 ). Clare Wilson's report rightly pointed out the need for companies developing IT with therapeutic or diagnostic aims to consider evidence-based development as paramount to patient safety and effectiveness. …

Scott McNeil raises concerns (Letters, 3 August ) about producing batteries for electric vehicles and welcomes the discussion of hydrogen power ( 8 June, p 20 ). It is some years since you have covered the potential for an ammonia-based fuel economy. Ammonia can be compressed and stored much more easily than hydrogen. We already …

It is true that cancer kills far more people in the UK than dementia, as Clare Wilson reports ( 17 August, p 10 ). But the many different types of cancer can be readily identified. Dementia is much less clearly defined and it has many side effects, such as falls and pneumonia. Researchers at University …

My first reaction on seeing your report on artificial islands for wind farms at sea was dismay at the potential for environmental damage ( 20 July, p 10 ). On second thought, they have exciting potential. Such islands could host wave energy harvesting devices, using the same infrastructure to get energy to the mainland, and …

Ruby Prosser Scully reports that tree stumps are being kept alive by nearby trees ( 3 August, p 18 ). In 2000, Peter Thomas wrote in Trees: Their natural history that grafts between roots of individuals of the same species are common in both hardwoods and conifers. There are cases where stumps have been kept …

You say peacocks have elaborate tail feathers to impress peahens ( 10 August, p 14 ). The iridescent feathers that make up the bird's train and fan out to impress mates are the upper tail coverts. The male peacock's actual tail is dull and is raised to support the train. It is much shorter than …

I don't understand why Ruby Prosser Scully thinks that the erratic behaviour of the magnetic poles is less worrying than once thought, because any flip will take longer than previously imagined ( 17 August, p17 ). Surely any flip would leave Earth unprotected from solar wind, and the longer the flip takes, the longer the …

• The eruption that caused a mini ice age in the 6th century AD was somewhere in the northern hemisphere ( 31 August, p 14 ). • Waggle room: male drone bees have only one set of chromosomes ( 17 August, p 38 ). • Ouch. Many gallstones are composed of cholesterol and crystals of …

You suggest readers download a computer program to search for Mersenne primes in the background ( 10 August, p 38 ). Yet every week you report the looming peril of climate change and the need to change our behaviour to limit it. Modern laptops and many desktop computers throttle back the processor speed and put …

As Chris deSilva says, exporting hydrogen produced by electrolysis is like exporting water (Letters, 20 July ). But why use fresh water? Pure water is essentially a non-conductor, while seawater conducts electricity, aiding electrolysis. It may also have useful by-products, such as industrially useful rare earth metals, cobalt and lithium. If some desalination is necessary, …