Compulsive eating
In arguing that food addiction is mere fiction, Maia Szalavitz misinterprets the real meaning of addiction (23 August, p 23).
The hallmark of addiction 鈥� to food or anything else 鈥� is not an identified biological mechanism, such as altered brain function. Rather, the diagnosis hinges on behaviour 鈥� the compulsion to continue use while enduring harm. Food addictions have been recognised for decades and been the subject of numerous scientific journal reports.
That said, biological mechanisms are coming to the fore. As I point out in my book Breaking the Food Seduction, certain foods, especially sugar-fat mixtures, chocolate, cheese and meat, appear to trigger the release of opiates in the brain. Studies show that opiate-blocking drugs, such as naloxone, counteract this process, particularly in binge eaters.
Why do some people fall prey to addictions, while others do not? Part of the answer lies in a single gene that leads to a reduced number of brain receptors for dopamine, the brain’s key feel-good chemical. Many affected individuals will do anything 鈥� eat, drink, smoke or gamble 鈥� to achieve normal feelings of equanimity.
There is little question that food addiction is as real as tobacco addiction. The risks are also real. Numerous studies link diets high in animal fat to breast and colon cancer. And the growing epidemics of obesity and heart disease suggest that we have not dealt with the addictions central to the destructive food choices many of us make daily.
Platinum crisis
In your special report, hydrogen was suggested as a way to avert an impending energy crisis (16 August, p 8). However, using hydrogen in fuel cells for mobile applications requires a significant amount of platinum catalyst to combine hydrogen and oxygen at low temperatures to produce power.
But even if only 1 million fuel cell cars were built per year, each with between 70 and 140 grams of platinum, the worldwide supply of platinum would be insufficient.
Letter
Fuel cells can use many different fuels. Indeed, there are great thermodynamic advantages in avoiding hydrogen through the direct oxidation of hydrocarbons or the use of solar-chemical systems, such as those using zinc.
Dogs and dingoes
Laurie Corbett’s conclusion that no pure-bred dingo populations exist in Australia is premature, coming as it does when genetic surveys of the extant populations in New South Wales have yet to be completed (9 August, p 6).
This work is being supported by the NSW National Parks and Wildlife Service (NPWS) to identify relatively pure dingo populations and determine conservation priorities for dingo populations in general. The preliminary results from this work have confirmed that Canis lupus dingo still exists. For example, the dog fences that sheep farmers built along the eastern edge of the New England Tablelands in the late 1800s to protect sheep from dingo attack served a dual purpose in limiting breeding between dingoes and domestic dogs.
The NPWS has carried out extensive research into the natural history of dingoes and their management in north-east New South Wales, the results of which have been used to develop management plans for dingoes on NPWS lands. These plans aim to protect livestock from wild dog attack while conserving dingoes and the other species that live on NPWS lands.
I fear that those who wish to undermine this balanced approach will pick up Corbett’s statements and use them to justify continued demands for dingoes to be culled in parks.
Dose of sunshine
In her article about the benefits of sunshine, Celeste Biever says that government bodies fight shy of recommending a daily allowance of sunshine.
However, the German Federal Office for Radiation Protection has a leaflet that recommends 15 minutes’ exposure to sunshine three times a week to support the synthesis of vitamin D.
Pinstriped universe
Reading your article on the “fabric” of the universe, I became uncomfortable with the arrogance of the researchers (16 August, p 22). They have decided what they want to find, and are desperate to find it.
They seemed pleased that their Standard Model Extension covered “every feasible manner in which Lorentz symmetry can be violated”, and when the desired results didn’t appear, blamed anything but the fact that their theory may be wrong.
Luckily the balance is restored later in the same issue (Interview, p 38), when Abdolkarim Soroush states: “It is impossible to advance new theories鈥hen you are under the influence of a particular view, or under the pressure of a particular dogma.”
Letter
The whole universe is believed to be like an (expanding) balloon, with a four-dimensional surface filled with the five-dimensional “air” in which the big bang took place. Physicists are currently looking for pinstripes on the four-dimensional space-time fabric, but what if the pinstripe forces pierce through our space-time, coming from the inside of the balloon to the outside? The force would not point in any direction in our four dimensions, but would in five.
If you were a muon
I hope that I am not the first to point out the error in “The editor writes” under John Ponsonby’s letter about the speed of muons (16 August, p 20).
Time dilation means that the muon travelling close to the speed of light has a lifetime, relative to the stationary observer, that is greater than that which the muon itself experiences. It is manifestly incorrect to say that “from the muons’ point of view their lifetime is effectively extended”. The muon’s time frame, in which proper time is measured, is unchanged, as is its lifetime. The time period observed, however, is dilated and hence the muon’s lifetime as measured is extended.
Remote switch-off
Writing on ways of preventing power failures that plunged the north-eastern US and Ontario into darkness last month, Jeff Hecht says: “A more promising technology, under test, will allow power companies to remotely switch off some heavy loads for short intervals,” (23 August, p 7).
There cannot be much need for testing. Many domestic customers in Switzerland have been subjected to just this technology for many years. The electricity supplier uses a remote-control box, fitted next to the meter, to switch circuits in and out whether the householder likes it or not. In practice, this does not cause much of a problem: it only means that circuits supplying appliances such as water heaters and washing machines are switched off during meal-cooking times.
Planetary warming
The mystery of the rapidly eroding ice caps on Mars and global warming on Earth may well be connected by the sun (23 August, p 40). Surely any increased radiation from the sun would affect both planets and could account for both phenomena?
Under Lake Vostok
Why on earth are researchers studying Lake Vostok proposing to drill right through the kilometres of ice covering it, risking the contamination of its pristine contents and the possible explosive release of dissolved gases (23 August, p 21)? The waters of the lake could be directly explored and sampled without ever breaking its seal.
Ice can be melted by both heat and pressure. So an autonomous submersible, powered by a plutonium power pack such as those used on spacecraft exploring the outer solar system, could be sterilised and lowered down a blind drill hole. The hole would then be filled with water, which would freeze to seal it. The submersible would initially be heavy, giving it negative buoyancy. Its weight, and the waste heat from the power pack, would melt it down through the remaining ice until it fell into the lake, where it would dump weights to give itself neutral buoyancy.
It could then move about the lake under remote control, sending back pictures and other data. This phase of the research could run for years if need be, as the power pack could last as long as those on Voyager or Pioneer have. Finally, samples could be taken and more weight discarded, giving the submersible positive buoyancy. It would then melt its way back up through the ice 鈥� which would again re-freeze behind it sealing its path 鈥� to a height where it could be retrieved by drilling.
The ice seal would never have been broken. Large volumes of the lake could be explored, many samples could be taken, and there would be no danger of contamination or degassing. And we would even get the expensive submersible and its plutonium back.
'Displaced' organs
The misleading appearance of the organs in cadavers referred to in your feature on the “mechanical properties of the body’s squishy bits” once led to a completely unnecessary and dangerous operation (16 August, p 34).
In the 1920s, when X-rays were becoming common, physicians noticed that a surprising number of people had all their internal organs displaced downwards by some 5 centimetres. Surgeons devised an operation to shorten the suspensory ligaments and get the organs back in place. It had not occurred to them that the textbook positions came from cadavers that had been dissected on their backs, whereas their patients had been X-rayed standing up. No doubt lives were shortened as well as ligaments.
Inquisition's weapon
While fascinating, the idea put forward by Paul Ormerod and Andrew Roach that the Inquisition relied on the mathematics of scale-free networks is patently false (16 August, p 32). Everyone knows that the Inquisition’s chief weapon was surprise. Or, rather, fear and surprise. OK, fear, surprise and ruthless effici鈥h, forget it.
Letter
It seems that the science to fight heretics could be used to fight terrorists.
For the record
鈥� Due to an editing mistake, we omitted the affiliation of Steve O’Shea, one of the researchers featured in “Monsters of the deep” (2 August, p 24). O’Shea is a senior research fellow at the Auckland University of Technology in New Zealand.