- Email: [email protected]
HIV origins
Letters– How green are we? From Holly Preston I really enjoy reading your magazine, but I am curious to know how much Virgin paid for the full page advert for “Upper Class” service (18 October, p 4). It seems to me that in an issue about the folly of growth (18 October, p 40) to advertise a hugely carbon expensive means of travel for the business travellers who fuel this growth is a bit wrong. In the same issue (of the UK edition) are adverts for cars, laptops and BP. The one that made me laugh most was for Land Rover. It is made green, apparently, because they have built a couple of wind turbines to power the Dagenham factory – while the top urban fuel consumption given at the bottom of the ad is a whopping 22.4 litres per 100 kilometres. Given New Scientist’s standing and position, wouldn’t it be a good idea only to advertise those companies that are really enabling a greener world? And while we are on the subject, why are you still printing and distributing paper copies, rather then being fully online? What is the carbon cost of transporting these copies to those people who read it in the far-flung corners of the world? Sorry, but all this just seems like common sense to me, and I’m only 13. Yorkshire, UK PS: My Dad has bet me £5 you won’t print this letter.
Renewable what? From T. Robertson Your special issue on renewable energy implied that its objective is to generate electricity (11 October, p 28). In fact, the primary purpose is to reduce the discharge of carbon dioxide. The generation of electricity from renewable sources does have merit, as even the best fossil-fuelled power stations convert only half the fuel energy into usable power. 20 | NewScientist | 1 November 2008
A renewable energy source that delivers electricity compatible with grid distribution is therefore doubly effective in reducing CO2. The snag is that it is difficult to maintain a balance between the energy available from a renewable source and the demand for electricity at that time. The need to supply electricity compatible with the grid – at the right voltage and frequency – means that wind turbines operate only above a cutin speed, typically a wind speed of 3 metres per second. The average wind speed over the UK’s lowlands is about 4 m/s. At high wind speeds energy output must be restricted. A typical UK dwelling spends about five times as much on heating as on electricity. There is a demand for domestic hot water
French are managing with 80 per cent of their electricity generation coming from nuclear power would be most interesting. Any more editorials like this (11 October, p 3) and readers will start to think of the magazine as Green Scientist. Enderby, Leicestershire, UK From Anthony Higham You say: “a large, 10-megawatt wind turbine should produce at least 10,000 megawatt-hours of energy in a year” (11 October, p 29). Where are these monsters going to be located? Constructing one of these – bigger in diameter than an Airbus A380 wingspan – for every 1000 homes sounds more like a nightmare than a dream. Edenbridge, Kent, UK The editor writes: ● These large turbines are mostly designed for installation offshore, where the wind is stronger and more predictable.
HIV origins
throughout the year, so an obvious solution is to equip homes with wind generators that deliver heat, replicating the energy conversion system that the physicist James Prescott Joule used to establish the relationship between mechanical energy and heat: paddles rotating in water. Milton, Oxfordshire, UK From David Rose You refer on the cover to “guiltfree energy” (11 October). What is guilt-free about growing and burning biofuels, placing barrages across every suitable estuary, and gigantic windmills coast-to-coast and out to sea? The power generation industry, including nuclear power, should be given a chance to put across its case in your pages. A study of how the
From Ann Hale, University of Sydney New techniques to track HIV infection in Africa show that the virus crossed from chimps to humans as early as 1908, at a time of rapid growth in the major cities in colonised sub-Saharan Africa (4 October, p 10). David Worobey notes the likelihood that high-risk sexual behaviours found in cities allowed the virus “a toehold in the human population”. An equally plausible explanation for this toehold was the widespread use of injections in African cities beginning in the early decades of the 20th century. The use of bismuth injections to treat the yaws infection – even an incomplete dose eliminated visible symptoms – led to a belief in the healing power of the injection and its popular use as a cure for all complaints. My research into HIV transmission in Chiang Mai, Thailand, in 1996 and 1997 documented how Thailand’s
successful response to the epidemic was dependent on major efforts to extend health infrastructure. This effectively eliminated unsafe injections arising from a lack of resources, as well as injections by traditional lay healers. Redfern, New South Wales, Australia From Andreas Keller Debora MacKenzie discusses a possible link between the origin of the AIDS epidemic and “central Africa’s first-ever cities”. But the cities mentioned in the article were not the first in central Africa. Around 1550, there were already M’banza-Kongo, capital of the Kongo kingdom, and Loango, capital of the Loango kingdom. Olfert Dapper’s Description of Africa, published in 1668, includes a panorama of Loango, showing a city comparable in size to many contemporary European cities. Cologne, Germany Debora MacKenzie writes: ● Those earlier cities apparently did not allow HIV to persist, perhaps because they were too small or socially stable, or because their inhabitants didn’t have sex with people who ate chimps. Or perhaps they did support occasional spread of HIV, but it died out without travelling abroad. What struck the researchers about the emergence of HIV around 1908 is that this coincided with rapid, violent social change and urbanisation under the rule of King Leopold II of the Belgians and his ilk.
Albatross of ill omen From Andy Maloney I was surprised to discover a new, super-heavy 22-kilogram breed of albatross exists (4 October, p 10). I have worked with southern royal albatrosses, which are generally around 9 kilograms. These have a hard time taking off and landing, so I can’t imagine how the 22-kg monsters avoid crashing! I recall a Mars probe crashing www.newscientist.com
Renewable what? From T. Robertson Your special issue on renewable energy implied that its objective is to generate electricity (11 October, p 28). In fact, the primary purpose is to reduce the discharge of carbon dioxide. The generation of electricity from renewable sources does have merit, as even the best fossil-fuelled power stations convert only half the fuel energy into usable power. 20 | NewScientist | 1 November 2008
A renewable energy source that delivers electricity compatible with grid distribution is therefore doubly effective in reducing CO2. The snag is that it is difficult to maintain a balance between the energy available from a renewable source and the demand for electricity at that time. The need to supply electricity compatible with the grid – at the right voltage and frequency – means that wind turbines operate only above a cutin speed, typically a wind speed of 3 metres per second. The average wind speed over the UK’s lowlands is about 4 m/s. At high wind speeds energy output must be restricted. A typical UK dwelling spends about five times as much on heating as on electricity. There is a demand for domestic hot water
French are managing with 80 per cent of their electricity generation coming from nuclear power would be most interesting. Any more editorials like this (11 October, p 3) and readers will start to think of the magazine as Green Scientist. Enderby, Leicestershire, UK From Anthony Higham You say: “a large, 10-megawatt wind turbine should produce at least 10,000 megawatt-hours of energy in a year” (11 October, p 29). Where are these monsters going to be located? Constructing one of these – bigger in diameter than an Airbus A380 wingspan – for every 1000 homes sounds more like a nightmare than a dream. Edenbridge, Kent, UK The editor writes: ● These large turbines are mostly designed for installation offshore, where the wind is stronger and more predictable.
HIV origins
throughout the year, so an obvious solution is to equip homes with wind generators that deliver heat, replicating the energy conversion system that the physicist James Prescott Joule used to establish the relationship between mechanical energy and heat: paddles rotating in water. Milton, Oxfordshire, UK From David Rose You refer on the cover to “guiltfree energy” (11 October). What is guilt-free about growing and burning biofuels, placing barrages across every suitable estuary, and gigantic windmills coast-to-coast and out to sea? The power generation industry, including nuclear power, should be given a chance to put across its case in your pages. A study of how the
From Ann Hale, University of Sydney New techniques to track HIV infection in Africa show that the virus crossed from chimps to humans as early as 1908, at a time of rapid growth in the major cities in colonised sub-Saharan Africa (4 October, p 10). David Worobey notes the likelihood that high-risk sexual behaviours found in cities allowed the virus “a toehold in the human population”. An equally plausible explanation for this toehold was the widespread use of injections in African cities beginning in the early decades of the 20th century. The use of bismuth injections to treat the yaws infection – even an incomplete dose eliminated visible symptoms – led to a belief in the healing power of the injection and its popular use as a cure for all complaints. My research into HIV transmission in Chiang Mai, Thailand, in 1996 and 1997 documented how Thailand’s
successful response to the epidemic was dependent on major efforts to extend health infrastructure. This effectively eliminated unsafe injections arising from a lack of resources, as well as injections by traditional lay healers. Redfern, New South Wales, Australia From Andreas Keller Debora MacKenzie discusses a possible link between the origin of the AIDS epidemic and “central Africa’s first-ever cities”. But the cities mentioned in the article were not the first in central Africa. Around 1550, there were already M’banza-Kongo, capital of the Kongo kingdom, and Loango, capital of the Loango kingdom. Olfert Dapper’s Description of Africa, published in 1668, includes a panorama of Loango, showing a city comparable in size to many contemporary European cities. Cologne, Germany Debora MacKenzie writes: ● Those earlier cities apparently did not allow HIV to persist, perhaps because they were too small or socially stable, or because their inhabitants didn’t have sex with people who ate chimps. Or perhaps they did support occasional spread of HIV, but it died out without travelling abroad. What struck the researchers about the emergence of HIV around 1908 is that this coincided with rapid, violent social change and urbanisation under the rule of King Leopold II of the Belgians and his ilk.
Albatross of ill omen From Andy Maloney I was surprised to discover a new, super-heavy 22-kilogram breed of albatross exists (4 October, p 10). I have worked with southern royal albatrosses, which are generally around 9 kilograms. These have a hard time taking off and landing, so I can’t imagine how the 22-kg monsters avoid crashing! I recall a Mars probe crashing www.newscientist.com