Tetrachromates

27 June, 2006

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.”
Read the rest of this entry »

Advertisements

Colour blindness again

27 June, 2006

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

    26 June, 2006

    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

    26 June, 2006

    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.

    Read the rest of this entry »


    And a clean pair of undies

    21 June, 2006

    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

    21 June, 2006

    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.
    Read the rest of this entry »


    Cap and trade versus carbon tax

    20 June, 2006

    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.

    Read the rest of this entry »