Tetrachromates

While ferreting around on the previous post I found reference to the fact that some women may actually be tetrachromates, seeing four basic colours rather than 3 for normal people or two and a bit like me.

There doesn’t seem to be an awful lot published on the issue, a few papers like this one but not a vast literature from what I can find.

The idea is interesting. There is even the suggestion that it could be expressed in the mothers of colour blind boys, which would have an impact I imagine about whether colourblindness genes were a net negative or positive selection criteria.

For years now, scientists have known that some fraction of women have four different cone photopigments in their retinas. The question still remains, however, whether any of these females have the neural circuitry that enables them to enjoy a different — surely richer — visual experience than the common run of humanity sees. “If we could identify these tetrachromats, it would speak directly to the ability of the brain to organize itself to take advantage of novel stimuli,” says Dr. Neitz. “It would make us a lot more optimistic about doing a gene therapy for color blindness.”

Colour blindness again

Interestingly, my previous post about my colour blindness seems to be getting me the most search hits. Hopefully it has helped direct people to some of the things they are interested in. If not here are some other places to look.

For those of you who are interested in reading about this, don’t miss Colorblindor a blog mostly about the experience of being colourblind. This post also discusses the experience.

This blog has a post about the troubles someone in practice may have reading the website (ie. not many but some).

This site has some facts and a short self test, plus some links, as does this one and this one.

Update: Some scientific papers on colour blindness.

Defective Colour Vision and its Inheritance (scanned pdf)

Impact of congenital colour vision deficiency on education and unintentional injuries: findings from the 1958 British birth cohort which has some responses

Colour vision deficiency in the medical profession. (pdf)

New aspects of an old theme: the genetic basis of human color vision. (pdf)

Doctors and the assessment of clinical photographs–does colour blindness matter? (pdf)

Slow week

What with the world cup, child rearing and general other stuff I haven’t added much new content. That will change I can assure both of you loyal readers!

Climate change and insurance

A few links and comments about how the insurance industry is treating the issue of climate change. Given that they are badly exposed if there is to be a say increase in severe weather events, the insurance industry is taking this issue pretty seriously. For example this report from Lloyds highlighting amongst other things the risk of increased Atlantic hurricanes.

There is clearly a strong correlation between ‘warm’ phases of the cycle and more intense hurricane activity. On this basis, the intense hurricane seasons in 2004 and 2005 can hardly have been a surprise as warned in 2001 by academics.
…
Current high Atlantic sea surface temperatures are of particular concern for the North American economy and for the insurance sector, given the resultant insurance exposures. Recent temperatures are probably outside the range of past oscillations, and seem to suggest we will be caught in an upward cycle for some time to come. It is now vitally important that we monitor and keep pace with scientific developments going forward.

And a clean pair of undies

CBD workers should have individual emergency packs with them according to the recommendations of the CBD emergency sub plan.

The guidelines suggest people put in place personal emergency plans, including making up emergency packs containing maps, water bottles and additional clothing.
…
“Simple things like a bottle of water – if they need to be evacuated, they might have to walk for an hour or stand out in the sun.

“Even a battery radio so they can listen to what is going on.”

Its just like going bush walking in the city. I’ll be sure to pack a clean pair of undies in case I get taken away in an ambulance just to keep my Mum happy as well.

The continuing Iraq debacle

I can’t look at anything about Iraq without finding it depressing. Three years later we’ve 2500+ US soldiers, a few hundred other coalition troops, thousands of Iraq police and army and tens of thousands of Iraqi civilians killed.

The power supply is bumping along at near pre-war levels (its better outside Baghdad and much worse in Baghdad). Few other indicators are better than pre-war. – for these stats check the Brookings institute Iraq Index.

I’ve never believed that the external imposition of “freedom” was likely to succeed. While I believe that Iraq should be democratic, I think the Iraqis have to come at it on their own, and I question the real value of democracy if it is simple majoritarianism, rather than liberal democracy with basis rights of individuals respected. Better than dictatorship, but a long way from we in the West think of as a democratic state.

Then we read this leaked memo from the US Embassy in Iraq to the White House, and I begin to question whether the continued occupation has past the point where it is more hindrance than help to establishing a viable state for Iraq.

Cap and trade versus carbon tax

I’ve been trying to read up on what are the relative merits of Cap and Trade schemes for limiting pollution versus Carbon Tax. I’ve dug up a couple of links regarding this issue but haven’t as yet had time to consider them properly.

One of these contains this as a succinct comparison.

Some say “use a carbon tax,” while others say “use cap and trade.” The advantage of the tax is that when we set it at, say, $5/ton we know this is the cost we will impose on carbon users and no more. The downside is we don’t know how much that will limit carbon. The advantage of cap and trade is that we know how much we will limit carbon, but we have little idea how much allowances will cost–the market will decide later.

Hot Rocks

Brian mentioned in a recent thread at LP it would be good to hear more about Hot Rocks as a power source. While we hear a lot about nuclear and wind power solving our energy needs it seems that geothermal energy is decidedly unsexy. One of the basic problems with the electricity supply is the need for 24 hour base load power generation. Currently Hydro is the main contender for a renewable base load source, but in a dry continent its scope is limited. Biofuels are another possibility but have generally been seen to be too expensive.

Probably the most promising renewable base load solution is geothermal energy. The first geothermal electricity plant was constructed in 1904 in Italy. These plants used hydrothermal power, relying on underground aquifers venting steam or high-pressure hot water to the surface. There is some potential for this in Australia ans there is a limited amount of electricity currently generated by this method in Birdsville, Queensland.

There are other Australian schemes for harnessing Geothermal power which are currently being investigated. Over the past few years a number of Australian companies have listed on the stock exchange with their primary goal being to explore and tap hot dry rocks. These are based around the idea of injecting water into rocks kilometres below the surface and extracting the superheated high-pressure water coming back out to drive generators.

Probability is not intuitive.

I was thinking about how people don’t have a good intuition on nuclear power probability and how this effects people’s thinking on nuclear power. In nuclear power there is a very small risk of something very bad happening, and we must weight this up against say a coal power station where there is a large chance of creating an incrementally small bad effect (ie. additional global warming). Maybe I’ll say something useful later as I think this has real implications for the evaluation of the worth of nuclear power, but this is not the point of the post.

During these thoughts I remembered reading a nice piece from The Economist from years back discussing this sort of thing. It gave three examples, the first is the well known birthday problem where the chance of two people having the same birthday in a group is always more likely than people expect. The second is the Monty Hall problem, where you have less chance of getting a goat than you think. I heard both of these before, but the one I hadn’t heard was the false positive one.

The false-positive puzzle. You are given the following information. (a) In random testing, you test positive for a disease. (b) In 5% of cases, this test shows positive even when the subject does not have the disease. (c) In the population at large, one person in 1,000 has the disease. What is the probability that you have the disease?

It seems pretty obvious but is it?

Indonesian justice

If you inspire mass murder:

Militant Islamic cleric Abu Bakar Bashir, the alleged spiritual head of terrorist group Jemaah Islamiah, is set to walk free from a Jakarta jail today.

The Australian government is unhappy but says it accepts the Indonesian legal decision.

The firebrand cleric, convicted of involvement in the first Bali bombings in 2002, has completed a 25 month jail term for giving blessings as leader of JI to the attacks which killed 202 people, including 88 Australians.

If you bring in cannabis:

An Indonesian court has reinstated the original 20-year sentence given to convicted drug smuggler Schapelle Corby.

Corby, 28, was found guilty last May of smuggling 4.1 kilograms of marijuana into Bali in a boogie board bag.

The Australian government’s view of the decision

“(Mr Howard) already mentioned that in our relations we should respect the judicial processes of each other’s country including the decision about Abu Bakar Bashir,” he said.

True but of course, the reverse doesn’t apply when we are issuing protection visa’s to West Papuan refugees.