Editor's pick: Build for a warmer future the way people used to do it (1)
Michael Le Page notes that using air conditioning in response to climate change produces yet more heat (4 August, p 18). But there is a useful alternative to the refrigeration method: evaporative air conditioning. The effect was used by the ancient Egyptians, who wafted, or had slaves waft, a current of air over soaked earthenware pots, lowering its temperature by evaporation.
Now we can pass hot air from outside through water-soaked pads. The water evaporates and absorbs a large amount of energy, lowering the air's temperature. A fan pushes this air through the building. This system is far less costly to install, run and maintain than a refrigeration system.
The lower the relative humidity of the incoming air, the better. If it has a temperature of 30°C and a relative humidity of 40 per cent it can theoretically be cooled to 15°C, which is its dew point. Even at night, with a temperature of 18°C and a relative humidity of 80 per cent, a bedroom's temperature can be lowered by 3°C. This system is widely used in the southern US and in southern Australia, where temperatures are often high and relative humidity low. It will not work well in conditions of high humidity such as India at monsoon time. But in many locations, it will make life much more comfortable at a much lower cost to the planet.
Editor's pick: Build for a warmer future the way people used to do it (2)
Le Page's outline for designing houses to combat climate change sounded rather familiar. Our house is shaded by trees, has dense walls 760 millimetres thick and is partially underground. It is approximately three times as long as it is wide and high, with small windows left open at night. Without air conditioning, it has remained cool this summer. It's a Yorkshire Dales stone cottage built in about 1640.
In whose interests are autism adaptations?
Poppy-Jayne Morgan reports on glasses that project emojis to help children with autism read faces (11 August, p 10). She says of one that “Alex's gaze avoidance remained a significant issue for him”. Is this not projecting onto an autistic boy the emotional state of his mother?
I have seen others suggest that, as is typical for autistic people, Alex was not troubled by his lack of eye contact. He may have found it uncomfortable or merely uninteresting. Avoidance of eye contact was to him a successful solution to this problem. The person to whom avoidance was a problem was Alex's mother.
The interests of Alex and his mother are not aligned. He wants to be able to cope with the outside world. She wants him to appear normal. An improvement for one would not necessarily satisfy the other. The intervention described has fortuitously helped both sides, by teaching Alex new social skills in a way that incidentally makes his behaviour more pleasing to his mother.
First class post 鈥� 1 September 2018
I'm still not going to take it. Apparently you are as sick as a dog afterwards.
Claire Farrow that taking ayahuasca is like having a near-death experience (25 August, p 14)
Fast-healing mouths as an ancient adaptation
I have often wondered whether mouth wounds heal faster than skin wounds, and it was good to see research answering this (4 August, p 16). It seems to open up new research possibilities related to wound healing. I now wonder whether the genes involved are evolutionarily conserved, ancient and now widespread. They would provide a crucial advantage in the constant fight to survive and reproduce. All animals need their mouths in the best condition for feeding.
Civilised, voluntary population control
Is Ian Angus saying that it is morally wrong to seek a lower human population as we combat climate change (25 August, p 22)? In the , first issued in 1992 and repeated , the majority of the then-living Nobel laureates signed up to say, among other things, that pressures resulting from unrestrained population growth put demands on the natural world that can overwhelm any efforts to achieve a sustainable future.
The statement goes on to advocate sexual equality and to guarantee women control over their own reproductive decisions – all women, everywhere, with no mention of coercion.
Using civilised, voluntary means, we must rapidly stabilise, then reduce, our population. The means are well-known and cheap: education for women everywhere; free contraception; and removal of social, political and financial incentives for big families. This applies to rich and poor alike.
Smart meters may make even noisier neighbours
Sam Edge says current smart meters are a flawed way for electricity generators to try to reduce peak demand (Letters, 11 August). They do need to do this, but the plan to use smart meters to adjust electricity prices to encourage people to use more off-peak power, and thereby less peak power, has me worried.
As one who has been kept awake at night by a washing machine and tumble dryer in a neighbour's flat, I worry about what people are expected to use electricity for, off-peak. Other than phone and tablet charging, only unattended clothes washing and drying equipment come to mind. I challenge anyone to sleep through an off-balance load being spun in the middle of the night, or even the start-stop rumble of a dryer.
Short dogs may aim high to erase others' marks
You report behavioural ecologist Betty McGuire finding that small dogs tend to aim high when urinating and suggest that this may be the canine equivalent of macho posturing (11 August, p 13). I'm not sure.
Anyone who walks dogs will attest that they continually sample scents, and often investigate a site closely before delivering urine. Do they not only need to lay down a territorial marker, but also flush away traces of existing marks? To do so, dogs whose apparatus is closer to the ground would need to aim high to achieve success. Taller dogs are unlikely to detect any marker higher than their own natural arc and will not need to stretch.
Eukaryote evolution may explain a scarcity of life
Guy Cox describes how eukaryotes are thought to have evolved by an archaeon engulfing a bacterium that then became the mitochondrion (The Last Word, 28 July). Other engulfed bacteria became chloroplasts in plants.
These processes seem to have happened only a few times, suggesting they were very unlikely to succeed. Archaea and bacteria have different cell membrane structures, so it might not be possible for the engulfing to happen with two archaea or two bacteria because the cell membranes would simply merge.
It seems rather odd that we have these two distinct types of microorganism. Why did the first to evolve not fill all ecological niches, leaving no room for the second to establish itself?
Could this mean that a life-bearing world lacking two such separate microorganism families cannot evolve complex cells, multicellular organisms and a technological civilisation?
A freezer may not help you much in a crisis
Clare Wilson suggests buying another freezer to guard against food shortages in case of a Brexit disaster (4 August, p 21). This may not be helpful.
If the UK crashes out of the European Union with no deal, it is probable that the pound will similarly crash against the euro and dollar. Oil and gas are still critical to UK electricity generation and are priced in dollars. I presume electricity imports are priced in euros. Is the UK government going to be able to ensure electricity generation? You need to stock up on dried and tinned food. I will be.
Even for robots, no rights without responsibilities
The speaker schedule for your 快猫短视频 Live event on 20-23 September includes “” (, back page). More pertinent, especially to those displaced by robots, is: should robots pay tax? No rights without responsibilities!
Discharged batteries do have a little less mass
Howard Bobry takes his local emergency preparedness meeting to task for assuring him that a discharged alkaline battery weighs less than a fresh one (Feedback, 7 July). But as Paul Hewitt notes in his textbook , a change of energy of any object at rest is accompanied by a change in its mass, so a hot cup of tea has more mass than it does cold. The catch, of course, is that the change in mass is tiny. I calculate that for a small battery with a full charge of 15,000 joules, that is equivalent to less than 0.2 nanograms.
The size of this glacier will astound you
I read that the melting Totten glacier could on its own raise sea levels by 3 metres (11 August, p 4). Really? It must be very big.
The editor writes:
• It is: its catchment area is more than 500,000 square kilometres and researchers in fact that its total loss could raise sea levels by 3.5 metres.
We don't know it all, but we're moving that way
You write: “You may think you already know everything there is to know…” (Leader, 28 July). Surely, the fact that we are reading 快猫短视频 means we don't?
For the record 鈥� 1 September 2018
• The shield of the Parker Solar Probe is necessary to protect against radiation from the sun's surface (18 August, p 5).