Wrong numbers
Chris Dye points to the difficulty of interpreting epidemiological statistics to correctly set priorities for disease control (1 February, p 23). There is an even more fundamental problem. In at least some cases, we are doing a poor job of collecting the numbers used for the statistics in the first place.
In the US we have been told for the past decade that our extensive cancer-prevention programmes are working, and that cancer incidence rates are flat or declining on virtually every front. We now find that this is not true, and was based on incomplete data.
An October 2002 report by researchers at the National Cancer Institute shows that many cancer incidence rates increased significantly every year of the period they studied, from 1981 to 1998 (Journal of the National Cancer Institute, vol 16, p 1537). This study found that delays in filing field reports resulted in conclusions completely at odds with the reality.
The impact of this type of mistake is pervasive. Once the wrong numbers are published, they become the “headline” figures Dye warns against. Indeed, even though the above report was published in October last year, the wrong (more optimistic) numbers are still quoted by the National Cancer Institute, the American Cancer Society, and other prominent US cancer organisations.
Statistics on cancer rates and mortality ultimately affect the lives of millions of people. They are the foundation for decisions on the direction and funding of future research on cancer treatment and prevention. It is inexcusable that something as simple as field reports being filed too late could be causing the wrong decisions to be made.
The beast in us all
Ashutosh Varshney’s development of a methodology in the study of ethnic conflict is encouraging (15 February, p 43). I think that a complementary approach would be to confront and deal with the reality of human behaviour.
We tend to see ourselves as fallen angels and violence as an aberration from our essential goodness. Perhaps if we accepted that we are basically killer apes, with a tendency towards violence at our core, we could begin to confront the problem. We might start to develop insights and personal disciplines based on the reality of our nature. Progress will be faltering until we do this.
Such an approach is unlikely as it would offend our vanity. Much of the opposition to the ideas of Darwin is the result of being repelled by the idea that we are related to monkeys. These feelings are still rampant. As T. S. Eliot said: “Human kind cannot bear very much reality.”
Weighty matters
Your article laments the lack of a precise definition of the kilogram as a unit of mass (22 February, p 32). But looking at the definitions of base units, we find the ampere, mole and candela are all defined using derived units that themselves are based on the kilogram. Both the newton and the watt are derived from mass, length and time: a newton is a kilogram metre per second squared and a watt is a kg.m2s-3.
Does the inaccuracy in the definition of the kilogram have knock-on effects on the accuracy of the ampere, mole and candela, or is there a clever workaround that allows these units to be accurately defined?
Letter
Your list of base units defines the mole as “the amount of a substance that contains as many elementary entities as there are atoms in 0.012 kilograms of carbon-12”.
Surely if a kilogram is an indefinable amount then so must be a mole?
Letter
I remember being told at school that a litre of water has the mass of a kilogram. Even if this is not precisely true, it shouldn’t be too difficult to calculate exactly what volume of pure water, or any other suitable substance for that matter, is required to make up 1 kilogram, taking into account isotopic variation, atomic forces and controlled ambient conditions.
All you have to do after that is produce containers that will hold this volume in the same ambient conditions, for which you need only use the well-defined unit of distance. Once created, anyone anywhere should be able to recreate the controlled environment in order to obtain the correct volume of the chosen substance, with which they can calibrate their measurement systems.
Letter
The article does not mention the following obvious and elegant definition: the mass which, when placed one metre away from an equal mass, generates a gravitational attraction on each of them of G newtons, where G is the numerical value of the gravitational constant G.
However, I seem to remember previous articles on the extreme difficulty of obtaining an accurate value for G. Does that mean this approach is not practicable?
Lemons versus HIV
In your “HIV Focus”, it was disappointing to see the possibility of using lemon juice as an HIV preventative dismissed in two sentences: “But seasoned researchers pointed out that for any product, human trials were essential to ensure it didn’t damage the vaginal epithelium and do more harm than good. And we already have several microbicides based on cheap and readily available chemicals in standardised doses that have passed the research stage and are poised to enter large-scale trials” (8 February, p 44).
Notwithstanding the “cheap and readily available”, it appears that recouping the research costs and then making a profit are more important than finding out whether or not lemon juice does damage the epithelial cells, and possibly providing people who can’t afford even “cheap” drugs, with an effective microbicide they could produce themselves.
Author Alan Stone, chairman of the International Working Group on Microbicides, writes:
鈥� Lemon juice is just one of many “household” items able to inactivate HIV, including other acidic substances like vinegar, inexpensive bleaches, antiseptics and disinfectants. Tests could be carried out to ascertain whether or not lemon juice is likely to be safe enough for use in the vagina.
However, even if it is, we cannot assume it will protect from HIV infection during sex, and promoting the use of an ineffective product 鈥� even if it is intrinsically “safe” 鈥� could actually increase HIV rates by discouraging use of condoms. The acidifying microbicides now being developed use standardised amounts of chemicals formulated as gels that won’t simply dribble out of the vagina, and whose acid-buffering properties are designed to withstand the alkalinity of semen.
Painful mammograms
You report that there may be a refinement to mammogram breast X-rays that will enable them to diagnose more accurately than at present (22 February, p 14).
Many women wish as well that a more comfortable method of giving them could be used. At the moment, the breasts are squashed against flat X-ray plates. A study of 116 women, published in The Journal of the American Medical Association, found that 91 of them experienced pain during mammography, of whom 15 experienced intense pain. If the procedure were less of an ordeal, more women would come forward for screening.
Divided world?
Your editorial states: “It is rare for the world to seem as divided as it is today” (22 February, p 3).
How short is the modern attention span. Have you forgotten that in 1989 the world contained two superpowers with nuclear weapons pointed at each other? Am I alone in believing that the threat the world faces today is several orders of magnitude smaller than it was in those days?
Why do we consider terrorists to be more dangerous than the threat of industrialised warfare? The answer, to me, is clear. Fear is much better at selling newspapers than good news. Under commercial pressure, reason and logic fly out of the journalistic window.
The world may seem divided, but in fact it has never been as united as it has been since 11 September 2001. Let’s try to keep a sense of proportion.
Linguistic cues
Paul Kail comments in his letter (8 February, p 27) on Ken Grimes’s article about “the language bug” (18 January, p 30). Kail rightly points to the fact that the learnability of a given language is affected by many factors that may differ considerably across languages.
The acquisition of language involves the integration of many different types of cues available in the input. However, each cue that the child may use is only partially reliable, and will thus not work in all cases. Research suggests that children may solve this problem by integrating a multitude of correlated and partially overlapping probabilistic cues.
What does this mean for language evolution? The suggestion is that individual languages have evolved to use different constellations of probabilistic cues to facilitate the acquisition process. The exact combination of cues utilised by any given language will be a product of several factors, including limitations imposed by the learning and processing abilities of its speakers (primarily children but also to some extent adults) and influences of neighbouring languages through invasions, trade, and so on. Moreover, just as biological evolution works through “tinkering” with existing forms rather than by engineering design, the evolution of individual languages is similarly constrained, in some cases leading to awkward language structures.
Thus, the languages we encounter today are products of complex pressures deriving from cultural transmission across generations, the use of language within a community, piecemeal evolutionary tinkering and other historical influences.
More voice
If it takes Hans-Peter Salzmann three hours “on a good day” to compose a message of 400 characters by selecting letters using successive binary division of the alphabet, there is obviously room for improvement, even without implanting electrodes (22 February, p 36).
Niels Birbaumer’s work in this area is obviously of tremendous value, and the question is how to build upon it. Would it not be more efficient to use a trinary division method (as has been proven to be the most efficient system for successive division of choices), and to bolster that with the dictionary-based text prediction of mobile phones, which allows one key to stand for any of the three letters it carries?
This would seem to be a relatively simple change to make to the software, and might allow Salzmann and others to write significantly faster.
Feedback corrupts
In your remarks on online surveys you claim “we vote alternate ways to avoid skewing the results” (Feedback, 22 February). Might I point out that you will skew the results, in favour of the minority position. Suppose, for example, that in an admittedly poor response to such a survey, 2 vote one way and 1 the other. Feedback then adds a vote for each side and a 2 to 1 majority slips back to 3 to 2.
I trust that you will be suitably horrified to discover that you have been, albeit inadvertently, corrupting statistical data in this way.
For the record
鈥� An error crept into the edit of our story about atmospheric pollution and ozone (22 February, p 7). The reactive species in question are uncharged hydroxyl radicals not negatively charged hydroxyl ions as we stated.
鈥� In our special report on sunken oil tankers in the Pacific (22 February, p 12), we mistakenly referred to Sefanaia Nawadra, Marine Pollution Adviser at the South Pacific Regional Environment Programme, as a female. Our apologies for any offence caused.