Summer Special Q&A Show

US researchers have found that giving young animals diet foods can trigger obesity by encouraging overeating behaviours, suggesting that the same thing could happen to young children. Writing in the journal Obesity, University of Alberta researcher David Pierce and his colleagues have found that giving young rats the rodent equivalent of low-calorie foods affected their ability to learn how to associate the amount of energy in food with its taste. It seems that artifical sweeteners can fool the brain into assuming that all sweet things are equivalently low in calories, which can trigger over-eating when other non-diet foods are consumed. In the present experiments the age of the animals also seemed to be critical, because adolescent rats were not affected, possibly because they had already established the relationship between tastes and calories. "One thing is clear at this point," says Pierce, "our research has shown that young animals can be made to overeat when low-calorie foods and drinks are given to them on a daily basis, and this subverts their bodies' energy-balance systems." The results also fit with other recent findings including a University of Massachusetts study which showed links between diet drink consumption (amongst children) and obesity, diabetes and heart disease. "Diet foods are probably not a good idea for growing youngsters," Pierce cautions.

We often hear about coral reefs being the rainforests of the sea - both habitats are packed full of thousands of species and sadly both are being lost at ever more alarming rates.

And this week we've heard a piece of really bad news for coral reefs, because they may be disappearing much more quickly than we thought they were, and possibly around twice as fast as rainforests.

That's according to a new study from John Bruno and Elizabeth Selig at the University of North Carolina in the United States.

They collected together over six thousand other studies going back to 1968 that documented how much hard coral was growing on particular coral reefs in the Indian and Pacific Oceans, in countries including Indonesia, Australia and the Philippines.

Hard corals are the building blocks of reefs - also known as scleractinia - they provide the main structure and habitat for all the other animals and plants to live on.  Measuring the percentage of the reef that hard corals cover is one of the best ways of gauging how healthy a reef is. [It's a little bit like measuring how much canopy a rainforest has from either air born or satellite images, which is how scientists measure how quickly forests are being lost.]

The bad news is that the coral cover on reefs in the Indian and Pacific Oceans over the last 20 years has dropped by an average of 1% every year which might not sound a lot but it's the equivalent of around fifteen hundred square kms every year.

The study also discovered that reefs in the Indian and Pacific oceans also began declining much earlier than we used to think - it was always thought that reefs on the other side of the planet in the Caribbean were in the worst state, but now it seems the Indo-Pacific is also fairing just as badly.

The cause of these declines could be a combination of global factors, like increased sea surface temperatures that trigger devastating bouts of coral bleaching, as well as more local pressures like damaging fishing techniques and the run off of sediments and pollutants from land.

But it's not all doom and gloom. The researchers found that a number of reefs have in fact been increasing in coral cover, showing that it's not too late, especially if we start taking direct action to stop the decline continuing at all these different levels from local to global.

Protecting reefs makes nothing but good sense.  Not only do the reefs of the Indo-Pacific contain huge numbers of species, the reefs also provide a crucial source of protein for people in many developing countries, they help protect coastlines from erosion and the generate important income in countries with burgeoning tourism industries.

I don't mean to be the harbinger of bad news - but it happens this week we've had another piece of important but incredibly depressing news from the aquatic world.

It looks like we might have to wave goodbye to the Yangtze river dolphin in China. Researchers from Zoology Society of London (ZSL) reported that during a two month expedition along the Yangtze river they found absolutely no trace of these dolphin.

The researchers have pointed the finger of blame at unregulated fisheries that accidentally caught the river dolphins, as well as the construction of dams and collisions with the huge amount of boat traffic that now ply the waters of the Yangtze river.  They proclaimed this as could be the first cetacean to be driven extinct at the hand of mankind and the first extinction of a large vertebrate for over fifty years - so it's the first time a large, charismatic creature has disappeared from the planet that most of us will remember.

Facts about the Yangtze river dolphin:

• It was the only remaining member of an entire branch of the evolutionary tree, called the Lipotidae, a group of mammals that separated from other marine mammals around 40-20 million years ago.
• If any Yangtze river dolphins had been found during ZSL's expedition, they would have been taken to an oxbow lake to begin a captive rearing programme.
• The Yangtze river dolphin had a long narrow beak which it used to feed on fish.
• The Yangtze river dolphin was top of the list on ZSL's EDGE programme, which stands for "Evolutionarily Distinct and Globally Endangered species" - the world's mammals were ranked in terms of how distantly related each one is to it's nearest neighbour and how engendered they are.
• The extinction of the Yangtze river dolphin highlights the threats faced by other rare and endangered species in the river ecosystem which includes endangered freshwater porpoises, giant salamanders and Siberian cranes.

There are two possibilities with this; noises you can hear that come out of nowhere could be tinnitus, which is caused when you have damage to your hearing system.

The damage removes the input of certain parts of the hearing spectrum, (you hear across a range of frequencies).

In the same way as some people get "phantom pain" in an amputated limb, the brain 'invents' some sound to make up for a lack of input from a part of the hearing system.

Tinnitus is normally a high pitched ringing noise, so probably not the cause of a droning sound.

The most likely explanation for a drone is that you have blood vessels in your ears, and these pulsate. In some situations, such as a very quiet room or when you put your head on a pillow and create a sound chamber in your ear, you can hear the sound of blood rushing through those vessels.

This only works on old fashioned tv screens or computer monitors, so to understand why this happens we need to know how they work. Inside a television there is a big glass chamber which has had all the air sucked out to make a vacuum. At the back of this chamber is an electrical gun which fires electrons towards the back of the screen. The screen is covered with tiny lumps of phosphor, which glows when an electron hits it. If you cover the whole screen with one colour of phosphor, you get a black and white tv.

To make a colour tv screen, they put tiny spots of three different colours of phosphor on the screen in groups. Each group contains a spot of red, a spot of green and one of blue. Lighting these up in different combinations can make all the colours you see on your tv.

As electrons fly towards the screen, they can be moved using a magnetic field - this lets you aim the electrons at the right spot of phosphor and get the right colours in the right place.

When you put a magnet near the tv, it diverts the electrons away from where they should go, and so the wrong phosphor spots light up and you don't get the right colours.

Sometimes, if you put a magnet near a tv for too long, you can make bits of it magnetic and so it will always distort the colours: this is how the colours stay there.

Some tv's have a degaussing coil inside them that re-sets the magnetism when you switch them on, so the colours go back to being correct.

Even the Earth's magnetic field is enough to distort the colours, so if you turn a tv upside down when it's switched on, this can also make the colours go wrong.

We did this experiment in kitchen science.

Chris -   "What's Science ever done for us" is also the title of a new book that's out at the moment. It's been written by Professor Paul Halpern, he's from the University of Philadelphia. He joins us now. Hello Paul.

Paul -   Hello Chris.

Chris -   Thank you for joining us on the naked scientists to tell us about your book. Why have u written this? And don't say to make money because that was Boris Johnson's answer on Radio 2 the other day.

Paul -   Well I noticed throughout the years that the Simpson's features marvellous Scientific references on the show and features scientific guests and many illusions to people such as Neil spore, Einstein, Darwin and Newton...I thought it was about time to look at the Simpson's episodes and explore the real science behind the series.

Chris -   Well, few people have the sort of insight into how you've done this,  it's nice this because you get a taste of the Simpson's upfront and then you get how it's relevant to science in the second part of the chapter.

Paul -   That's right in each chapter I look at how an episode of the Simpson's handles the science then I look at the background behind it. For example, in one episode Lisa invents her own perpetual motion machine and Homer gets obsessed by it and shouts at her: "Lisa, in this house we obey the laws of thermodynamics." So I take off from that episode into an exploration of whether or not perpetual motion is possible and I explore the laws of thermodynamics. So I find it provides a great intro into some interesting science.

Chris -   Now, how does the Simpson's sit with you as a professional physicist engaged in research in a US university?

Paul -   Well, physicists that watch televisions tend to enjoy series like the Simpson's because it's one of the few series, it's not the only series, to have scientific references on the show and it does a number of fun and very sophisticated things with science. For example, exploring higher dimensions, looking into the possibility of time travel, bringing up genetics, robots, artificial intelligence... it's just amazing how much interesting science there is in the show.

Chris -   I thought it was hilarious when Homer Simpson managed to end up crossing a tomato and tobacco plant to make an addictive form of a tomato

Paul -   That's right it's called Tomacco and the interesting thing is he uses plutonium to make this hybrid

Chris -   And he gets it where..?

Paul -   [laughs] He manages to get it shipped in from his nuclear plant, it's no problem for him since he works in this plant so he just manages to phone up his friend and get some plutonium shipped into his farm that he's trying to grow crops on. He grows this tomacco and produces this tomacco plant, which is highly addictive.

Helen -   I don't know if this is in your book but one of my favourite bits in one of the shows is when they discover that Homer, as a young child, pushed a crayon up his nose and into his brain and that's why he's... 'Homer' shall we say. They take it out and he becomes very intelligent and then they decide in the end to put it back again. Do you think, is there any reality in having a pencil in your brain and changing your behaviour?

Paul -   Well it's interesting. The Simpson's brings up a number of theories throughout the years on why Homer is so different than the people in his family, for example Lisa, who is much brighter and in one episode they attribute it to genetics. Then, in the episode called 'Homer' which is a parody of Flowers for Algernon, they suggest it's an accident that Homer had as a child where he had the crayon lodged in his brain and that it affected his intelligence, but the strange thing is once they pull out the crayon he's very unhappy. He preferred being not so bright

Chris -   I think that goes for a lot of people in some cases though doesn't it? I mean, not that everyone would have a crayon jammed up their brain but some people find that ignorance is bliss don't they?

Paul -   That's right sometimes u can know too much about a subject and you might not be happy about it, you'll be well informed but perhaps not particularly happy about if say you know that something dyer is going to happen

Chris -   Well Paul, I have to say I thoroughly enjoyed your book. It had me sniggering at midnight last night so thank u for sending us a copy. Thank you for joining us on the Naked Scientists to tell us about it. It's out now is that right?

Paul -   That's right. Yes. Thank you very much. It's my pleasure.

Chris -   It's been a pleasure to have you on the programme. Thank you

Paul -   Bye

Chris -   That's Professor Paul Halpen. He's written a book called "What's Science ever done for us". It's all about how the Simpson's, as we've been exploring, actually has its firm roots in science and you can get it in all good bookshops right now.

Self-raising flour contains baking powder, which is usually a mixture of bicarbonate of soda, cream of tartar and something called calcium aluminium phosphate.

Bicarbonate of soda has lots of carbon dioxide locked up in it, which is let out by reacting with an acid.

Cream of tartar becomes tartaric acid when it gets wet, so these then react together and produce bubbles of carbon dioxide in the cake, making the cake rise.

Calcium aluminium phosphate only becomes acidic when it gets to a certain temperature, giving extra bubbles, and so an extra rising stimulus, while the cake bakes.

When you've got a blocked coronary artery, for example, in the heart, what people used to do was to stick a line in through the top of the leg, into the artery, thread it back to where the heart is, go into the blood vessels supplying the heart and then you inflate a tiny balloon inside the artery.

This opened up the artery by squashing the blockage which was making the artery narrow. When they did that to start with, what would happen is, very quickly the artery would block up, or fur up, again. 

So then doctors discovered that the best approach is you if you deploy what's called a stent, which is like a metal scaffold.

Now it's very very tiny when you first put it in and it's threaded over the end of the balloon and when it gets to the right point in the artery where you want to deploy it, you inflate the balloon, which stretches the scaffold. It's almost like it ratchets out and locks in position. It props open the wall of the artery, stopping it constricting again and this should hold the problem area open and make sure it doesn't block again.