Stun gun doubts
Our citizens’ group has been tracking taser abuse across the US following the death of James Borden after tasering in our local jail on 6 November 2003.
Our review of dozens of incidents reveals many cases where neither the officer nor the public were threatened. The taser has become the weapon of choice for bullying officers wishing to assert their power over ordinary citizens.
The new technologies referred to in your article create an even greater potential for abuse (19 June, p 24). Taser International asserts that its device is not lethal and is absolutely safe. But the technology may not be as safe as Taser claims. In the case of Borden’s death, according to the Herald Times online, “In December, Monroe County Coroner Dave Toumey ruled that Borden died of cardiac dysrhythmia 鈥� disorder of the heartbeat 鈥� caused by an existing heart condition, pharmacologic intoxication and electric shock.”
Douglas Zipes, a cardiologist who has studied taser-related deaths, commented in the same report that the electrical energy from such stun guns could cause sudden death.
Barks in the forest
Readers may be interested in anthropological evidence for extremely subtle human interpretations of dogs’ barks (12 June, p 52). The highly mobile Native South Americans collectively known as Maku hunt extensively with dogs in the forests of the Upper Rio Negro and the Vaupes region of Colombia and Brazil. Their dogs signal the species of game they are pursuing by the type of bark they emit 鈥� extremely helpful in the dense foliage of the tropical rainforest. Distinct barks identify black or yellow agouti, peccary, pacca, tapir and jaguar.
Experienced hunters have no difficulty in identifying these distinct game barks and react accordingly. A “peccary” bark elicits an immediate sprint through the forest, as they run away from the dog. “Agouti” barks produce a much more relaxed response, as they go to ground in their burrows or in hollow tree trunks and the dog will keep them there until the hunters arrive to dig them out. “Tapir” or “pacca” barks will send the hunters towards the nearest stream as both species will head for water, where they feel safe from the dog. I took part in many successful dog-hunts during ethnographic fieldwork with the Maku.
The bark hunters fear most is a “jaguar” bark. Although a good hunting dog will chase a jaguar, it is often killed. The hunters’ response is to rush through the forest calling to the dog and making as much noise as possible, hoping to call off the dog and scare away the jaguar. Sadly, they are not always successful and few good hunting dogs live for more than a year or two.
Dubious detox
You may be interested in my experience of the Aqua Detox machine (Feedback, 19 June).
I was seeing a physiotherapist, and she offered me a course of treatment with this new cure-all. One look at the leaflet triggered my fruitcake detector, so the opportunity to test it at first hand was irresistible.
The machine comprises a plastic footbath with a central electrode assembly and an external box attached to the electrode. As far as I could see, the electrode was a pair of concentric helices of thick wire in a perforated plastic case. The bath was half filled with warm tap water and the feet placed in it on either side of the electrode. A solution of common salt was added to increase the conductance of the water to a level indicated by the attached gadget. It was then switched on and my feet remained in the water for half an hour. I could feel no sensation throughout this time.
The water gradually turned a rusty orange colour and ended up looking pretty filthy, containing a lot of suspended fine particulate matter with some floating scum. The physio and her assistant clearly believed that this had come out of my feet. But before the water became too opaque I clearly saw the gunge emerging from the electrode rather than my feet. The colour looked to me very like hydrated iron oxide (III), that is, rust. On asking, I was told that the electrode assembly does degrade and needs to be replaced after 40 or 50 treatments. They didn’t know what metal it was made of.
I booked a second treatment a week later. At this, after the water’s conductivity was adjusted, I removed my feet and said that I would like to observe the device on its own, and that I would happily pay the 拢10 treatment fee for the privilege. Exactly the same happened as the previous week, and the physio reluctantly agreed that the water looked just the same as it had when I had included my feet in the process. To her credit, she refused the fee.
Letter
Let’s just suppose that the person operating the Aqua Detox device adds some unspecified salt to the water in the machine, as recommends. To get those “before and after” pictures, you need add nothing more exotic than common salt.
An electric current passing through this salty water will make the electrodes rust, if they are iron, turning the water brown, but it will also turn the water into a solution of sodium hydroxide. This is how sodium hydroxide is made in industry.
Now, as all chemists know, sodium hydroxide is a powerful degreaser 鈥� so powerful that getting it on your skin constitutes an industrial accident. Placing your feet in what slowly becomes a mild solution of sodium hydroxide once the current flows will make some of the skin’s grease react with the sodium hydroxide to produce a soapy gunge, made even gungier by the presence of rust.
This, of course, does not constitute a healthy “detox”. Rather it will lead to dry and cracked skin if overused. If sodium hydroxide really is being produced in the water, it makes it all the more alarming that the Aqua Detox company once condoned immersing babies in the chemical brew, something they have recently removed from their UK website. Indeed, their policy now seems to be to say as little as possible on this site, though the reference to babies is still on the American one.
As for the claims about the electric current: aside from producing the sodium hydroxide and the rusty discolouration, the current has no effect on the body at all. It flows around rather than through the skin.
Bearing jewels
Colin Finch’s theory on why CD jewel cases are so called is certainly imaginative and possibly even convincing, but sadly incorrect (19 June, p 31).
Jewel cases get their name from two small plastic bumps, or bearings, that the cover hinges on. The practice of using real jewels as bearings in watches and clocks is commonplace, and so all such bearings are termed jewels.
Quite why such a technical term was applied to the low-tech CD case is, perhaps, less obvious.
Don't blame retardant
Fred Pearce’s article “Flame retardant shows up in Arctic” wrongly assumes that there is a lack of scientific data on the flame retardant deca-BDE (12 June, p 10). It does not mention that after 10 years of scientific analysis and more than 100 studies, a scientific assessment by the European Union could find no identifiable risk to child or adult health, nor to the environment, from using deca-BDE.
In 2003 Frank Wania and Chandrasagar Dugani reported that deca-BDE has “a very low potential to reach remote areas”. Although all the data from the new study has not been published yet, even the Norwegian Polar Institute recognises that the levels found are “low”. Indeed, previous research found that deca-BDE levels in the same region were typically around 0.5 parts per billion. At this level the flame retardant poses no environmental or health risks.
Cool combustion
John Griffiths explains clearly the benefits of cool-flame combustion (5 June, p 28). But low-temperature combustion must decrease the Carnot efficiency. This theoretical maximum efficiency for converting heat into mechanical energy is determined solely by the temperature difference between heat source and sink.
Typical combustion temperatures for an engine using cool-flame ignition may be around 1800 掳C. This is lower than with spark ignition. What is the penalty in decreased efficiency?
John Griffiths replies:
鈥� Typical combustion temperatures for an engine using cool flames is around 1600 掳C, reducing the engine’s maximum efficiency by around 15 per cent. However what legislators are interested in are the benefits 鈥� lower emissions of pollutants such as soot and nitrogen oxide.
Sofa and no further
It has been widely reported that a meteorite crashed through the roof of a house in New Zealand and rebounded off the sofa, making a second hole in the ceiling (19 June, p 12).
Wait a minute. This rock hurtled around space for 4.5 billion years, before heading towards Earth at around 50,000 kilometres per hour, penetrated 100 kilometres of Earth’s atmosphere, smashed through a roof and a ceiling, and then鈥� bounced off a sofa?
What are the special properties of sofas? Has NASA been told?
You can cancel all those expensive plans for deflecting life-threatening asteroids with improbable combinations of nuclear warheads. All you need to do is build a giant sofa at the projected impact site, and bounce that sucker right back where it came from.
Fido's feelings
If humanity is defined by an ability to love, empathise, feel guilt and embarrassment, and understand deception and cooperation (19 June, p 32) then dogs are human! I thought so (as do they).
Avian togetherness
The article on birds flocking refers to them “flying in one great and inexplicable mass” (26 June, p 48). It seems to me that it has (since) been explained as emergent group behaviour built on very simple individual behaviour following these rules:
1. Keep together.
2. But not too close.
3. Follow the one in front.
4. Move away from anything that might be a predator.
5. Go towards a goal 鈥� roost, feeding place, water, hide under cover鈥�
A relatively simple computer simulation can and does demonstrate this behaviour.
Tiny engine, big noise
Your article on the use of miniature internal combustion engines as power sources for portable electronic equipment leaves some questions unanswered (19 June, p 26). For example: how do you prevent excessive wear over the lifetime of the power source? Most commonly used lubricants produce some exhaust residues and need to be delivered to the moving parts in some way.
What levels and frequencies of sound do these power sources generate? How large would the silencing system need to be to make the noise level acceptable in a confined space, or in areas containing multiple units? How will the power source be isolated from the electronics to prevent damage to components and connections through vibration?
I doubt there will be a mass market for a laptop that buzzes like a wasp, smells of hot oil and gently massages my lap with its vibrations.
Radio daze
I agree that software bloat is a pain (19 June, p 30). In the good old days, I could twiddle a knob and see the radio tuning in. Now I just have to assume that the setting is optimal.