Editor's pick: We can do trials of a ketogenic diet
Hal Hodson suggests that it might not be possible to conduct a randomised clinical trial of the ketogenic diet, which involves cutting back on carbohydrates and increasing fat intake, for the treatment of brain cancer (27 February, p 10). While people would of course know what diet they were on, so the trial could not be “blind”, randomised trials of diets have been done, such as those of the Mediterranean diet.
Instead of giving a sample of people such a diet and monitoring them for two years, as suggested by an oncologist interviewed for the article, I think it would be better to place half of a sample of, say, 50 people at random on the diet, and half not.
This would allow a clear comparison of recurrence rates in the two groups. If instead we follow the design outlined in the article, it would not be possible to determine whether any reduction in recurrence of cancer was due to patient selection or the effects of the diet itself.
Until a randomised trial has been done, many clinicians, quite rightly, would not recommend such a diet. A small, rigorous trial should be done to demonstrate whether this diet has merit.
The evidence for a maternity review
Clare Wilson’s online opinion piece, published on 25 February, argued that the recent will lead to harm to mothers and babies (newscientist.com/article/2078853). We were surprised that no reference was made to the scientific evidence underpinning the review. A of 15 randomised controlled trials on the benefits of continuity of midwifery-led care found that it reduces rates of both preterm birth and overall fetal and neonatal death, and improves maternal outcomes.
High-quality studies comparing outcomes for healthy women and babies found that planned out-of-hospital births resulted in , and in .
The most recent National Institute for Health and Care Excellence (NICE) recommends that healthy women are given evidence-based information and supported in their choice of birth place.
Our reading of the Maternity Review recommendations is that they are designed to deliver respectful, kind, safe, evidence-based maternity care, centred on the values and needs of women and their families and intended to improve their wellbeing and that of their babies.
Preston, Lancashire & London, UK
鈥� See newscientist.com/letter/2080286 for references and all signatories.
From Bill Kirkup
Wilson’s piece is misleading in several respects. Much of this springs from the perceived link between the investigation into failings in maternity services at Morecambe Bay NHS Trust (which I chaired) and the National Maternity Review (of which I was a member). The national review may have had its origin in the response to events at Morecambe Bay, but it was much more wide-ranging.
The national review does not “extol the virtues of births at home or at midwifery-led units separate from hospitals”. Enabling more women to exercise an informed choice may well mean fewer births in obstetric units, because more women would like this than manage it currently, and 鈥� as the review rightly puts it 鈥� there is no evidence that outcomes differ by place of birth in second or subsequent pregnancies.
When assisted birth is required, there is sometimes a choice between caesarean section, forceps and vacuum extraction. There is a legitimate and continuing debate about which to use when, but this has nothing to do with either place of birth or midwife-led care.
Observations such as “spitting on the graves of those who died” are offensive to everyone who contributed to the review.
Correction, 18 March 2016: This letter has been updated because one signatory was listed in error.
First class post
The problem is those in engineering who aren't used to the presence of a female thinker in their team
Zara Teaffee Talat that her problem wasn't encouragement to go into engineering (newscientist.com/gallery/unsung-heroines)
Humans also paint landscape of fear
Sam Wong writes that predators “don't control populations of their prey just by killing them. They also paint… a landscape of fear” (27 February, p 9). Does this apply to dominating managers too? In an industrial landscape of this kind, will fear drive the innovative managers into hiding for fear of being eaten alive?
Humans also paint landscape of fear
After the study finding that the sound of dogs barking reduced raccoon feeding time through fear, it seems that the real question is not about the absence of large predators, but what is the effect of essentially every animal on the planet being mortally scared of humans?
When following orders is adaptive
The Milgram experiment in which participants willingly deliver (fake) electric shocks to actors because they are “only obeying orders” could be tapping into normal learned behaviour (27 February, p 14). Humans are socially primed from childhood to respond to commands.
If, as you report, astronauts react more quickly to voice alerts than to other audible sounds (p 19), it may simply be part of the same pattern of behaviour. Airline cockpits are already equipped with voice alerts where urgent action is needed, such as terrain avoidance (“pull up, pull up!”). “Only obeying orders” in these circumstances could save lives.
Feedback on <i>The Ecologist</i> and Zika
Feedback is admirable for its exposure of fruitloopery but a recent item taking aim at The Ecologist and me as purveyors of “conspiracy theories” over Brazil's microcephaly cases misses the mark (27 February).
Feedback attacked the idea of a link between the insecticide pyriproxyfen, used to kill mosquitoes in water tanks, and the birth defects: “There is no evidence to suggest it causes birth defects – and plenty to demonstrate that it doesn't, having been thoroughly tested in animals” (27 February).
The same was once said of the drug thalidomide, and we know how that ended. Exposure of humans to pyriproxyfen in drinking water without the strict clinical surveillance programmes advised in the wake of thalidomide is a public health scandal that leaves the possibility of a link open.
You can read my full response to this, and to Feedback's comments on my piece about Zika virus and genetically modified mosquitoes (20 February), on .
Driverless cars roll on and on
Anna Nowogrodzki discusses the time it takes for self-driving cars to start up when traffic lights turn green (23 January, p 21). Much of the reason for traffic congestion is that the faster cars are moving, the more distance there needs to be between them for safety. This holds true whether or not the cars have a driver. Even though a self-driving car could react faster if the car in front of it slows or stops, it would still take time for it to slow or stop itself.
Driverless cars roll on and on
This phenomenon is the reason why, contrary to the expectations of many non-engineers, a lower speed limit allows a greater throughput of vehicles per hour. Cars can travel with less space between them at the lesser speed. The safe space increases as the square of the speed.
Driverless cars roll on and on
Some years ago research was carried out in Switzerland on maximising the number of cars passing through traffic lights each cycle. The optimum was found to involve a two-car space between all cars and the whole line moving off simultaneously.
In practice this is never going to happen, but we can each stop further back, so we can see where the rear wheels of the vehicle in front touch the ground, and move off as soon as the vehicle in front does.
Who will accept ownerless cars?
Emily Wolfe suggests that driverless cars could provide environmental benefits by encouraging a shift to ownerless cars (Letters, 5 March). Suburban streets are currently lined with cars that are driverless for days on end. Why should the desire to own cars used only once or twice a week change, because the latest cars are robotic?
Who will accept ownerless cars?
Another major reason to encourage driverless cars is to make it possible to charge for road travel by distance, varying with the time of day and how busy the road is. The UK government has long wanted to do this. The monitoring technology is easy, but at present it would be too expensive to catch cheats. A self-driving car can't lie about where it is and is going.
Who will accept ownerless cars?
Hal Hodson's discussion of self-driving cars (16 January, p 20) made me think about the problems to be encountered by these vehicles. Simple decisions, such as keeping an appropriate distance from other vehicles, are easy to solve. But what about issues like which car reverses when two meet on a single-track road? If both are driverless, they can communicate. But if one has a human driver who never gives way, what happens?
To see the colour of the hat, look
One hundred people standing in line, each wearing either a red or blue hat, can only see those in front. Devise a strategy to maximise the chance of guessing one's own hat colour (/27 February, p 25). Simple: move your head close to the person in front and look for the reflected colour change on his/her clothing.
For the record
• The histogram showing how UK companies recruit showed too long a bar for “trade publications” ().