TV is ultrahigh frequency, and once Tony Blair's got his way, we'll all be using digital TV anyway so you won't be able to use your analogue radio to listen to your TV/radio anyway because it will be in the wrong format, unless of course you've got a digital radio.

Chocolate also has a number of other chemicals like theobromine which can mimic the feelings that you have of warmth and love - similar to the chemicals in your brain when you fall in love. So probably the feelings that you get when you stop eating chocolate are the withdrawal from those sorts of chemical not from the caffeine, and of course the sugar.

I'm not aware of any effects of magnets on blood flow, but they can be used to measure blood flow, in a technique called MRI - Magnetic Resonance Imaging. This works by putting someone in a very strong strong magnet, and under those magnetic conditions all the water molecules in the body line up in a straight line. The scanner then sends a pulse of radio waves which disrupts some the water molecules, some of the hydrogen actually, and they flip into a different orientation, and then flip back, producing a signal which enables you to measure what the tissue looks like in an Magnetic Resonance Scan. You can also do this to measure blood flow using a process referred to as MRA or Magnetic Resonance Angiography.

Dandruff is very common - you probably recognise it as flakes for skin that fall onto your jumper or jacket.
It's caused by a yeast that lives on our skin, so part of the treatment is to control that yeast, which can be done in a number of ways e.g. shampoos that you can get in the chemist which contain chemical which help to control the growth the yeast and so control the condition. A really old fashioned remedy that I quite like is a tar shampoo, but not everyone likes the smell of tar, but it does help to calm down the condition. Fortunately you can't catch it; we've all got these yeasts living on our skin. The reason why one person has dandruff, and another doesn't, is probably the way we react to these immune systems with our immune systems. So don't worry you can't pass it on and you can't catch it.

Athletes foot is really very common - if you took 100 young men who do a lot of sport the vast majority of them have athlete's foot. If you are a young man who does a lot spot and you check between the 3rd and 4th toe and find a little bit of skin flaking in-between the toes, that's athlete's foot. That's caused by another bug that lives on the skin - another fungus, that spreads from person to person. You can leave little bits on the floor if you do have this, so I suppose you could catch this form somebody else, but it takes up home in those nooks and crannies where air doesn't circulate so that's particularly common between the toes. Now if someone has got a really bad case of athlete's foot they will have some of this fungus but they may also have some extra bacteria that have got in through the soft mushy skin. So if they've got really bad feet there are some treatments that can be used to get rid of the extra trouble makers - the bacteria, and also the athletes foot fungus that's the cause in the first place.

That's a tough one, especially on the radio, to be able to make a guess as to what that is. Of course skin cancer usually comes as a single bump, so someone with something that's popping up a lots of bumps is less likely to have cancer, so maybe that's not so much of a worry. I'm thinking lots of people get those tiny little white cysts that come up under the eyes, which are little tiny collections of dead skin cells, and they usually work to the surface. But some people can get a few more, under the eyes and over the cheeks - it is a pure guess, as it is impossible to know without seeing the person.

Birthmarks are marks that appear at birth. There are two main types; blood vessel mark like President Gorbechav had on top of his head. The other sort of common birth mark, is a big brown mole which can be present at birth. They can come in all sorts of sizes, from just a few millimetres across to many centimetres - 10cm or more. Most people are born with very many moles, and you tend to develop them as you grow up. Most moles are developed during childhood, but there's often a boost in the number during puberty, and some during early adulthood, but not very many tend to develop later on in life.

A freckle is a collection of the skin pigment melanin in the skin, but in a concentration. Some people who are very freckly, have very pale skin in-between their freckles, so they have little patches of skin which makes the pigment not many cells which make the pigment outside that patch. A mole is the cells in the skin which make the pigment but more them in a lumpy patch.

We all get wrinkly as we age - they come because our skin gets less elastic as we get older. If you get look at a child's skin it has plenty of stretch and twang, but an older person's skin doesn't have this. As you get older your skin gets saggy, and loses its elasticity, causing wrinkles. Creams on the market can help with the really small wrinkles, but the deep ones, of the sort you can see a couple of feet away, I'm afraid, creams won't do anything for those. Things that you can do of course, are not go out in the sun, particularly when you're young, and not smoke. If you look at smokers, particularly women, they can be incredibly wrinkled. It's not known quite how that happens, but it is thought that it may be a chemical reaction in the skin and may also be a genetic predisposition in some people.

Moles which stick out a bit can rub on clothes and get a bit sore as a result. If there are a lot of moles doing this, it could be that there's an underlying skin condition that's going on at the some time, so it might be worth Dave going back to his doctor to make sure that everything is otherwise all right. He certainly should try not to scratch - but you would have to scratch regularly for a few years to run the risk of increasing the chance of cancerous change. If you have a sore patch of skin, a break or ulcer of skin then eventually after a number of years that area can become cancerous. But the average bit of trouble or itchy skin or moles is not going to tip the balance into cancer.

Certainly some people experience skin reactions related to certain components of their diet. The commonest manifestations are swelling and utricarial reactions (like nettle rash), but eczema can also be triggered this way. If the case is severe then it is probably sensible for a sufferer to undergo sensitivity or "prick" testing whereby a small amount of different potential allergens are left in contact with the skin surface to see which ones provoke a red "flare" reaction consistent with an allergic response. Food items containing that allergen can then be avoided, which can help to improve skin symptoms. But in mild cases full scale sensitivity testing like this is probably not necessary. Instead a "trial and error" approach can be used, with possible causative food items being eliminated from the diet one at a time. If after a certain food is withdrawn the symptoms improve this substance may be the culprit. To find out for sure, reintroduce the item to see whether the skin symptoms return.

We can get two sorts of colour changes as we get older and again it tends to be on the sun exposed bits like the hand and forearms. The pigment cells start to not work as well as they used to do. You can get pale spots; you can also get darker spots, which sometimes get called liver spots. I'm afraid it's part of the aging process really; the pigmentation mechanism doesn't work quite so well as it did before. In relation to pregnancy, lots of people notice that they get an increase in pigmentation, which can happen on the face, on the abdomen and around the nipples and freckles can do as well. This is because of the hormone changes increase the amount of pigment production and when you give birth and the hormones go back to normal again, those darker patches usually fade gradually.

Hair bleach is hydrogen peroxide - it's an irritant, so it can make your skin itch, and feel a bit dry and tight for a while afterwards, but there shouldn't be any long term consequences.