The answer is that your daughter is mosaic, as all women are. I don't mean that all women are little bits of ceramic pottery, but because we have two X-chromosomes as women, one of them gets switched off in every cell. In healthy people, this is a completely random process. Colour blindness is caused when there is a faulty gene on one of the X-chromosomes, and if you're a man then you don't have a counter balance to that (ie: another 'non-faulty' X-chromosome.) If you're a woman and one of your X-chromosomes is dodgy, you may have it switched on in some cells and off in others. The fact it's a mixture means that the healthy cells are going to compensate for that, so you're not going to be colour blind in just one eye. Some of the cells will have the colour blindness problem but there will be enough healthy ones to compensate.

This is called a hypnic jerk, and the reason we think it happens is that when you go to sleep, your body is completely paralysed. The reason for that, we think, is that you don't want to be acting out your dreams because otherwise it could get nasty! You must have had that dream when someone's chasing you and you have that horrible sensation of running through treacle. That's because you're literally paralysed in your sleep. However the process of that paralysis kicking in occasionally causes these funny jerks. People have done experiments on cats where they temporarily turn off the bit of the brain that causes you to be paralysed during sleep. The result is that you get cats prancing around and acting out these dreams.

We've had a few answers sent in for this question. Thanks to everyone for their input!

Dan in New Jersey - I think it's because over time when you're driving around you get pitting in your front windscreen from dust, water and stones. This could act as a nucleation site for ice, which encourages ice to form.

Bill in Canada - I think it's probably due to moisture at the front of the car and greater air circulation at the back of the car, making for a greater differential of temperature and moisture at the front. This might make it more likely to freeze up.

Thomas Coop in Germany - Ice is more likely to form on the front windscreen because it cools more quickly and to a lower temperature than the side windows. Frost normally forms during nights that are clear and calm and under such conditions, the trees and ground and many other objects cool mainly by a process called radiative cooling. That is, that they emit energy in the form of infrared radiation. The same happens to the front and side windows of your car, but the side windows cool more slowly because they are almost vertical. This allows them to pick up some of the radiation given off by trees and houses, which makes them cool more slowly. In contrast, the front windscreen points up into the clear cold sky and therefore receives very little radiation from other objects and cools more quickly. Since they cool more quickly, they are colder and frost is more likely to form on them.

The resolution of MR is in millimetres. Obviously if you wanted to go further with CT, you could, but it would require a greater radiation dose.

There are three ways of using radiotherapy: one is something called x-ray beam radiotherapy where x-rays are fired at a target. Another way is brachytherapy where a radioactive source is put in a tumour, and the third way is injecting a radioactive substance like radioactive iodine, which treats thyroid cancer. The reason it destroys the cancer is due to the way the radioactivity interacts with cells and causes DNA damage. It's specifically the ionising radiation that we use because the interaction with the cell causes electrons to be given off and leaving cells that are ionised. Usually when x-rays or gamma rays interact with the body, they actually interact with water and that water can form free radicals. The free radicals can cause damage to the cells by damaging the DNA.