Eat, sleep and be skinny

Researchers have shown that, somewhat surprisingly, the key to preventing children from becoming overweight is a good nights sleep.

A growing body of evidence now links lack of sleep, increased appetite and weight gain amongst adults, but it wasn't clear whether the same applies to children as they grow up.  A few studies have hinted at higher obesity rates amongst youngsters who take the least sleep, but it wasn't clear which effect came first, and whether being overweight just leads to poorer quality sleep.

To find out Julie Lumeng and her colleagues at the University of Michigan enrolled nearly 800 nine year olds and followed them up for three years, to see whether their sleep patterns (reported by their mothers) were related to changes in weight as they grew up.  The results were astonishing.  The children getting less than nine hours shut-eye per night were much more likely to pile on the pounds over the next three years than their superiorly-slumbering counterparts.  Even more striking was the finding that every extra hour of sleep the children took at the age of nine resulted in a 40% decrease in obesity risk by the age of twelve.  And at age twelve each extra hour reduced the risk by 20%.  The researchers cannot say for certain why extra sleep should keep kids in trim, but there are several explanations.

"Children who are better rested may have more energy to get more exercise," explains Lumeng. "It's also possible that when children are tired they may be more irritable or moody and use food to regulate their mood." It's likely that hormones also play a role.

Amongst adults, sleep deprivation has been linked to a reduction in levels of the appetite-suppressing hormone leptin, and increased production of the appetite-boosting hormone ghrelin.  These changes translate into a stronger urge to eat, increased calorie intake and weight gain.  So, paradoxically, kids might be able to justify missing the school bus in future on the grounds that they're battling the bulge...with a lie-in!

11th Nov 2007

Panoramic Ultrasound Scanner

Researchers have built a panoramic ultrasound scanner to work from inside your body

Ultrasound scanners are normally used from outside your body looking in, most famously for looking at unborn babies. They work by sending pulses of sound into you and then listening for reflections from structures in side your body. The shorter the wavelength of the ultrasound the better the resolution of the system so the better the images. But short wavelengths mean that the signal can't penetrate very far so images deeper into the body are not very detailed.

This problem has been avoided in the past by putting the sensor inside the body on a probe, sometimes down a blood vessel.  The problem is that the sensors could only look in one direction so doctors got a very detailed but blinkered view.

Jing-Kuang Chen and colleagues from New Mexico University may have a solution. They have folded a tiny sensor into a 1mm across hexagonal box. So it can now look forwards and sideways in a total of 7 directions, which should give doctors a panoramic view from inside the patient.

11th Nov 2007

Plants engineered to silence pests

Nobel prize-winning medical research has found an agricultural niche, as two teams of researchers have engineered crop plants to combat the troublesome pests that feed on them by switching off their genes.

In 2006, Craig Mello and Andrew Fire won the Nobel Prize for Physiology and Medicine for their discovery of RNA interference, a process whereby specific, unwanted genes can be switched off. RNA is a template for genes. By inserting into the cell a short piece of RNA, called an interfering RNA, which is the mirror image of the section of RNA that codes for a particular gene, that section can be cancelled out or silenced. This prevents that specific gene from being made.

Now, researchers at Monsanto Company in Missouri, US, have turned plants against their pests using the same technology. Targeting the western corn rootworm - an insect that causes an estimated $1 billion worth of damage to corn crops every year – they inserted a short section of RNA that silenced a gene that the rootworm needs in order to grow.

A second team, based at the Shanghai Institute of Biological Sciences, China, used the same technology to target the cotton bollworm, a moth larva that causes huge damage to cotton plants. They silenced the gene that allows the bollworm to tolerate high levels of gossypol - a toxic polyphenol in cotton. Both insects have developed resistance to insecticides – this new approach allows the plants to hijack the pests’ own cell biology and turn it against them.

11th Nov 2007

Source of 'Oh-My-God' particles

Cosmic rays are very high energy atomic and subatomic particles that hit the earth from space. There are several which pass through you every second, but most of these are fairly low energy and come from the sun. Others come from outside the solar system and the more energy they have the rarer they are. Until about 10 years ago astronomers thought that there was a limit on the speed of these particles because they would get slowed down by hitting photons from the cosmic microwave background radiation.

Then astronomers detected what are sometimes known as "Oh-my-god!" particles in a couple of small cosmic ray experiments. One of these sub-atomic particles has a similar energy to a tennis ball travelling at 60mph despite being about 10 000 000 000 000 000 000 000 times lighter. This is about 100 million times more energy than the particles in our biggest particle accelerators.

Scientists had no idea what was creating these particles until now, to find out they built the Pierre Auger Observatory in Chilie, this is an array of detectors the size of Paris built high up in the Andies mountains. It consists of hundreds of tanks of very pure water which glows when a cosmic ray goes through it. They also look for similar ultra violet glows in the atmosphere above the detectors.  A very high energy particle will hit the air and create a whole cascade of other particles which the detectors can see.

From these observations it would appear that many of these high energy particles are coming from directions with a very similar distribution to very large black holes at the centres of galaxies, but there is still very little data, so astronomers only know it is possible they are coming from the galactic nuclei let alone what is creating them.

11th Nov 2007

Drunken flies and the alcoholics’ genome

US Scientists have sequenced the catalogue of more than 30 genes that are influenced by exposure to alcohol. The study was carried out in drosphila, fruit flies – often used in genetic studies as their genome is very simple to model, and they share many of their genes with humans. The researchers suggest that this could provide a starting point for genetic studies of alcohol, which could eventually identify with genetic predisposition to alcohol addiction.

To measure the effect of alcohol on the flies, the scientists, from North Carolina State University, first had to get them drunk in a piece of apparatus they termed an ‘inebriometer’. This is a tiny tube-shaped pub for flies. Along the inside of the vertical tube are small shelves that slant downwards. The flies cling to the shelves, while the tube is filled with alcohol fumes until the flies are drunk enough to fall off their perches. This gives the researchers an organised stack of flies – lightweights at the bottom and the most hardened drinkers at the top.

The scientists then selected and bred the most booze-resilient and the most lightweight strains of flies, and compared their genomes to examine which genes were responsible for one fly’s ability to drink (or at least absorb) its buddy to the bottom of the tube.

The team also found that flies could be genetically mutated to respond differently to alcohol by inserting additional copies of these genes.

11th Nov 2007

When to add the milk

We were asked whether if you are going to leave your tea for a while should you add the milk at the start or end of your wait? Which way gives the hottest tea?

What you need

What to Do

We are trying to compare what happens to the temperature of milky tea when you add the milk at the beginning or at the end of a wait.

So make 2 identical cups of tea and pour a measured amount of milk into the first at the beginning of the experiment.

Wait 15 minutes then add the milk to the second cup of tea and measure the temperature of both cups.

What may Happen

You should find that once you add the milk to the second cup, the cup which you added the milk to first is the warmest.

Below you can see a graph of the temperature of the tea against time made with a mutilated electronic thermometer plugged into a computer. You can see that the tea which has milk added first cools down more slowly than the tea with no milk in it. So when you add the milk to the second cup of tea it ends up colder.

What is going on?

Adding the milk lowers the temperature of the tea but it doesn't do this by removing energy, it does it by spreading the energy around.

The hotter the tea the bigger the difference in temperature is between it and the room. This big temperature difference means that heat energy is lost more quickly so the tea without milk in cools more quickly than the the one you added milk to at the start. So during the experiment the cup with no milk will loose more heat, but should still always be warmer than the cup with milk. That is until you add milk to it when it will become significantly colder.

Because in the end both cups of tea are identical, at the end the one with the most energy will be the hottest. This means that the tea which had the milk added first has lost less energy so will end up warmer.

Robot Cars - the DARPA Urban Challenge

Chris - Now it’s time to take a look at the world of technology. This month Chris Vallance is going to introduce us to the DARPA Urban Challenge. This is a competition where people develop cars that can drive themselves around town. The Final took place on November 3rd. The competing vehicles had to compete on a sixty mile journey, obeying all the rules of the road and avoiding other drivers. This didn’t happen on public roads because there were one or two accidents. They used an urban military training facility that was in California. It was a big success and the reason they’re trying to do this is to develop driverless vehicles that can be used in war zones. There are likely to be some other big spin-offs for the average driver like you and me.

Chris Vallance - I’m obsessed with robot cars. It was the DARPA Urban Challenge. The reason I like this is that I saw the first challenge that DARPA did. DARPA is the Defence Advanced Research Project Agency. It’s, if you like, the ‘brains trust’ of the US military. It’s their geek squad. They ponied up two million dollars to see if someone could produce a robot car to drive around a simulation of an urban environment on its own. These aren’t remote controlled cars. These are cars with computers on and laser scanners so they can see what is ahead of them. They intelligently drive themselves from point A to point B.

Chris - Have they had much success Chris?

Chris Vallance - Yes, it was won by a Chevvy Taho by the name of Boss produced by a team from Carnegie Mellon University in Pittsburgh. It’s quite a technological feat. I remember back in 2005 they first tried this trick with what’s called the DARPA Grand Challenge. That was out in the Mohave Desert. There was absolutely nothing for miles around. There were dozens of teams trying to compete and driving round the kind of desert terrain, that I think if you or I were driving, we’d come a cropper in 5-10 minutes.  These cars actually drove successfully around that track.

Chris - So what are the challenges that the people who are doing these challenges are going to overcome? It doesn’t sound like rocket science to make a car follow a pre-programmed route.

Chris Vallance - It’s not pre-programmed. They have GPS way points. They know roughly where they’ve got to go but there’s not a pre-programmed route. They’ve got to navigate obstacles for themselves. If the first DARPA challenge that was just navigating rocks and bits of rough road – not driving off cliffs or hitting bridges. In the latest challenge, the Urban Challenge, they had to navigate around other vehicles. They had to stay in the right lane in the road and deal with an urban environment.

Chris - That’s a whole new ballgame. Sounds like a recipe for disaster. Were there any spectacular wipe-outs?

Chris Vallance - Well, there was a spectacular wipe-out. One of the really interesting vehicles from the Defence Agency’s point of view was a vehicle called Terramax. It’s a big, big truck that tried to drive into a disused shop. The cars do get a bit confused. It’s not a perfect science by any means and it is quite a difficult computational and object-detection problem that these teams have to face. If you look at these vehicles they are absolutely covered in scanners. They have these things called lidars, laser detection systems and radars. They have all kinds of detections systems to help them figure out what’s the road and what isn’t. If you think about an environment where there are lots of drivers about that becomes really, really crucial.

Chris - How do we think that this information that goes into making these cars able to do this on their own could be translated to making my life, getting to work in Cambridge, through a horrible rush hour a lot easier?

Chris Vallance - Well, funnily enough the DARPA are primarily interested in the military implications of this stuff. If you think about the casualties in places like Iraq there are people in convoys hit by improvised explosive devices and there’s actually a mandate from congress for a certain number of US military vehicles to be robotic by a certain date. In terms of the kind of cars that your or I drive, they are very keen to have this technology work its way into regular vehicles. This is Chris Earnson from the winning team of Carnegie Mellon University talking about how he sees some of this tech eventually working its way into the regular vehicles that you or I might drive.

Chris Earnson - We’re hoping that you’d get to a point where the car that you’re driving won’t crash. You could always drive it if you want to but if there’s something going wrong it might help you and prevent the collision. In the morning when you’re commuting to work you wouldn’t have to be behind the wheel. You could be having a nap or checking your email or on the phone and doing that safely. You’d be trusting the vehicle to get you where you’re going.

Chris - He’s talking about avoiding crashes, Chris. What about getting into tight parking spaces because we have a nightmare time when someone’s parked and they’ve left a just slightly bigger space than my car. I’m not brave enough to go into those spaces sometimes. It technology able to help?

Chris Vallance - I think that’s one of the things that we’ll see this technology help with in parking assist. There was a Japanese motor show very recently where we had all kinds of vehicles that could park themselves. That’s definitely one of the priorities, parking. Who wants a ding on your car when you’re trying to get into a tight space?

Chris - Who indeed and we’ve heard from Paula in Lowestoft. She says, “cars using sat-nav these days often get lost. Just look at that lorry that got jammed in a country lane for three days recently. Will we end up with robot cars driving around getting lost everywhere?” Probably, is the answer to that one.

November 2007

Micro-microwaves and Mini-Fuel Cells

Chris - Time now to catch up, as we do once a month, with Mark Peplow. He’s from Chemistry World. We were talking about microwaves just now and you’re talking about a microwave oven which is absolutely excruciatingly tiny?

Mark - That’s right, last week an American Scientist was claiming it’s the world’s smallest microwave oven. It’s shorter than an ant and half as wide as a single human hair. It’s a tiny thread of an oven. You could fit a pin head’s worth of liquid in it. About a millionth of a litre.

Chris - People say ready meals are making the population too fat. Maybe we should just give them one of those microwaves because they’d get a microcalorie. What’s the point of this?

Mark - Yeah, you wouldn’t get much of your evening dinner in this.  Essentially this is to create a device where you could heat small amounts of material very easily and very quickly.  A good example is if you were doing forensic work out in the field and you wanted to analyse some DNA. One of the ways that people do that is to use a reaction called the polymerase chain reaction. That involves heating and cooling. It actually amplifies your DNA sample so that you can do a test on it. If you imagine a handheld device, it needs a very small heating facility within it. What these guys are proposing is that they can use this microwave oven, tiny as it is, to do this sort of analysis.

Chris - How does it actually work?

Mark - Essentially it’s very much like the microwave oven in principle. You have a small cavity hollowed out of a polymer block where your sample goes in and small channels to deliver that liquid into the cavity. You have a very fine tracery of gold wires etched into the polymer block. It’s the electrical current moving through those in a particular way that delivers the microwaves.

Chris - Sounds amazing but sticking with the very small, fuel cells are hot topic at the moment.

Mark - Yes, fuel cells are a way of turning chemical energy in a gas like hydrogen into an electrical current. Researchers in Oxford, led by Fraser Armstrong, have created a microscopic fuel cell. They’ve taken a graphite particle – graphite is the stuff in your pencil – and they’ve stuck an enzyme on it that converts hydrogen into an electrical current. They’ve proved that this is working by sticking another enzyme on the other end of the graphite particle which does another reaction. They’re saying this is a proof of principle that you can take these sorts of fuel cells, which are already being used in cars and lighthouses, and use them to run chemical reactions in these microscopic test tubes that chemists are working on. So called, ‘labs on a chip.’

Chris - Application-wise, you would think people are quite eager to have ways of powering tiny robotic things that you could put inside bodies or do very, very technical things on tiny scales. Energy sources like this must be very important for them.

Mark - That’s right. Conventional batteries have proved incredibly difficult to miniaturise in that sense. Conventional battery technology just ends up making very bulky battery packs. Fuel cells are an alternative way you can really shrink things down. You can have a tiny volume of gas that serves as an energy source like hydrogen and this would be the converter to give you a constant current.

November 2007