Editor's pick: A graphical approach to cancer screening
Your leader on screening is clear and accurate (7 April, p 5). When I was a general medical practitioner, I was often unsure what to do with a marginally raised level of prostate specific antigen (PSA), which may indicate prostate cancer.
The problem is that the gland's enlargement in benign prostatic hypertrophy also leads to more PSA due to increasing numbers of cells. In prostate cancers, the gland has a few more cells, but the key difference is that they leak more PSA into the blood. That's what my urologist told me before extracting my cancerous prostate.
Mostly, I arranged repeated tests for my patients, often over many years. I was then faced with the problem of how to deal with slowly rising levels of PSA. This was solved by one patient who had undergone years of testing. He had plotted his PSA levels against time and he came to see me when the PSA rise accelerated. This indicated that the leakiness or the number of cells was shooting up. He underwent successful treatment for his cancer.
Science education in the UK needs to wake up
Your careers special highlights the dramatic challenge Brexit poses to the UK's ability to attract and retain top scientists and engineers from Europe (7 April, p 49). But what faces young people in the UK who are considering such fields?
After a career in aerospace, I have been a “” for nearly two years. This involves going into schools to talk about my career, discussing job prospects in science, technology, engineering and mathematics, and trying to encourage students towards a future in these fields.
But schools seem to offer little exposure, up to the age of 16, to applied computing and electronics. There is little practical engineering or science project work. The science and maths curricula seem to present a series of facts, rather as one might discuss disjointed events from the Napoleonic wars.
Primary schoolboys and girls often say “I want to be an engineer!” However, by the time they are 14 or 15, although often naming maths and science as their favourite subjects, students seem to have no interest in their own future in these fields.
Something is very wrong with our secondary education system. If the UK is to “go it alone”, it needs to wake up fast.
First class post – 28 April 2018
What is suggested for us emergency services people who have to work all hours? Gail F on what to do about late nights being correlated with an early death (21 April, p 18)
If it's intelligent, it will just make stuff up
Timothy Revell discusses whether artificial intelligences should be required to explain their decisions (14 April, p 40). This seems reasonable until we apply the same rules to humans.
When people have to make quick decisions in complex situations they confabulate, making up a plausible reason for a decision even when this has no link to it (16 December 2017, p 35). All competent AIs will come up with explanations – and these may bear no relation to the decision actually made. AIs will also learn that any justifications given mustn't include issues such as race or sex – even if inbuilt biases mean they are involved.
Are fathers affected by delayed baby-holding?
You report Anna Machin's research on fatherhood's effect on men (24 March, p 37). The birth of our first baby was medically “normal”, but slightly odd circumstances meant I was handed the hastily wrapped baby to hold (and put my face near) very soon after birth.
This seemed to have a long-term emotional effect. I was rather “hooked” on the child. Is there any evidence that the usual delays – and careful preparation of babies – might have an unintended effect on fathers?
Better ways of making use of carbon dioxide (1)
Michael Marshall suggests we can capture carbon dioxide from the air to make building materials by reacting it with calcium oxide to form calcium carbonate (17 March, p 34). Surely it would be better to capture the CO2 in a more concentrated form from the chimneys of lime kilns, where calcium oxide is produced by decomposing calcium carbonate. This involves lots of energy 鈥� generally from fossil fuels.
Better ways of making use of carbon dioxide (2)
In discussing ways to turn carbon dioxide into useful products, Marshall highlights that the energy costs of splitting hydrogen from water and carbon from CO2 may make “carbon emission free” petrol too expensive.
Is this a post-oil opportunity for countries like Saudi Arabia? They have plenty of sun to generate solar energy. Desalinated seawater could provide the H2O. The sunlight conversion efficiency might be low, but the sunlight itself would be free. The resulting liquid fuels would be compatible with existing infrastructure in such oil-producing countries.
More idiocy in the internet of things
I couldn't agree more with Paul Marks on the stupidity of “killer kettles” and other internet of things products (24 March, p 24). An example that particularly concerns me is the enthusiasm the UK government and energy companies have for installing “smart” meters.
These are not smart at all – they can simply be read remotely. Current models have repeatedly been shown to be laughably insecure. They risk being infected with malware to create huge “botnets”. Data from them can be used to build profiles of householders' behaviour.
The government and energy companies claim that smart meters will cost us nothing and will provide a valuable service. Despite protestations to the contrary, these meters are entirely designed to reduce costs for the supplier not the customer. I can already read my existing meter whenever I want.
The push to install these devices is a colossal waste of resources that involves replacing millions of perfectly functional meters. A smart meter will consume far more energy than my existing one in order to run its higher-powered processors and a data connection. And it won't be my energy supplier paying for that power – it'll be me.
How do these 'good' GM crops stack up?
Mark Lynas says the genetically modified staple crops he is now advocating “have nothing to do with the corporate behemoths that are the usual targets of suspicion in the GM debate” (7 April, p 26). But is it possible for poor farmers to harvest seeds to be used the following year? If not, the farmers still have to buy new seed each year, leading them into debt – as is the case with seed from those corporations. The important question for me is not the unproven risk of GM crops to humans, but the economics and farmers' lack of autonomy.
It is also wise to keep a range of crop varieties. When a GM crop is attacked by something it isn't programmed to cope with, then a new GM variety needs to be created and this has to use a non-GM plant as a starting point.
That's an awful lot of water in my pint
You quote Charles Denby saying that it takes 50 litres of water to grow enough hops to make a pint of beer (24 March, p 19). I am an avid home brewer and use about 200 grams of hops per 40-litre batch – nearly 3 grams per pint.
A typical hop plant yields 600 grams. On these figures, each plant would require 10 cubic metres of water. If a plant occupies a quarter of a square metre, that implies a water column 40 metres high, around five times the height of the plant.
The editor writes:
• Beer recipes vary, as do estimates of hops' water needs. One source says it took 2746 litres of water to produce 1 kilogram of hops ().
Looking forth over the 'wine-dark' ethane
It was great to read that finally someone is thinking outside the box in the search for life (24 March, p 40). One simple and definitive test for life wasn't mentioned. Complex carbon compounds such as sugars and amino acids typically have two chemically identical forms, called enantiomers, that are mirror images of each other.
Non-biological processes produce both in equal amounts. In our biology, structure is important and only one version of each compound is formed – the opposite-handed version just doesn't fit. This would surely have to apply equally to any carbon-based biology. So seeing a preponderance of one enantiomer over its mirror image would be an unmistakeable indicator of life.
Also, Leah Crane refers to “dark, oily liquids” on Titan. I have used liquid ethane in my research, at temperatures found on Titan, and it is a clear liquid that looks to be much less viscous than water.
The editor writes:
• The researchers respond that liquid methane and ethane indeed look like gasoline or petrol. But, as with water, you would see the colour of the sky in the deeper lakes and seas.
My head did literally explode, in a sense
Tom Gauld's cartoon depicts a conversation: “Did you hear about Professor Larson's new theory? It's literally blowing people's minds.” “I think you're misusing the word ‘literally’.” “Sadly, I'm not.” (Letters, 20 January). Many of our heads were literally blown a few years ago when dictionaries began to include for the word “literally” – to mean “figuratively”. This cartoon helped me get over it.
For the record – 28 April 2018
鈥� In the satire Great Apes, the actors were of course playing apes not monkeys (7 April, p 48).
鈥� It was private investment in renewable energy in the developed countries that has halved since 2011 (14 April, p 25).