Why is flu more prevalent in winter?

Why is flu more prevalent in winter?

we think flu spreads better in winter because of human behaviour because it does this reproducibly in every country in the world and in which it is winter time - it doesn’t mean it goes away completely in summer but it does come much more commonly in winter.

We think that’s because it spreads better in winter because of what humans do. We go indoors more in winter so there are more people together indoors with the windows closed. Also, unlike summer time, it’s less light and therefore there's less ultraviolet radiation to dry out the virus and kill it. So 'flu finds it easier to persist on surfaces spread by coughs and sneezes, and it hangs around for longer.

As a result you have a higher chance of passing it on so that’s what we think goes on. And then the big determinant, the disproportionate determinant, is the school year. The long summer school holiday powerfully knocks 'flu on the head because kids stop mixing and spreading the infection amongst themselves. What normally happens is that they become infected and then go home and give it to their parents and the parents then carry the infection to all of the other parts of the social and age strata, usually through their workplace.

How does 'flu actually infect our cells?

How does 'flu actually infect our cells?

The way flu gets hold of cells is down to proteins on the surface of the virus particle. Each virus particle is tiny, about 1/10,000th for the millimetre across. If you could zoom in on the surface, you’d see that it had these spikes on the surface. These spikes are a structure called haemagglutinin, which is a tiny protein resembling a molecular grappling hook. It’s viral Velcro. It gets hold of something called sialic acid, which is a chemical on the surface of the cells that line our nose and throat, and this enables the virus to grab hold of those cells and pull itself in very close.

Through this interaction the cell thinks the virus is something that it has to take inside the cell. So the cell then does something called receptor-mediated endocytosis, which basically means it pulls the virus inside the cell. Once inside the virus releases it’s genetic material and productively infects the cell.

It’s a bit like a Trojan horse actually because the Trojan horse was this juicy tidbit sitting outside the gate of Troy. The guys inside the city thought, “Wow! That looks fantastic. We’ll pull that inside because it looks good.” And it goes inside the city. And then of course, lurking inside are all these people who are then wreak havoc inside the city. And that’s basically what a flu virus does. It hijacks the cell, turns it into a virus factory and then it infects all of the cells around it and all the people around you!

Why do washing powders remove stains but not dyes?

Why do washing powders remove stains but not dyes?

one of the main and important ingredients used is surfactants and the surfactant molecule is clever in the way that on one side it has a hydrophobic component, that’s a water-hating molecular chain. And on the other side, a hydrophilic water-loving component. The hydrophobic chain finds itself sticking to the stains on your clothes and the hydrophilic heads have a stronger attraction to water. They’re able to surround the dirts and roll it up into a small globular-type ball and the end result is that they’re able to lift the stain from your cloth, into the wash water.

Some of our detergents contain enzymes which are naturally derived molecules. Generally, we use different enzymes such proteases which break down proteins and amylase which breaks down starch and then finally, another major ingredient that we use, like most other detergent manufacturers is bleach. The bleach turns the stain into more soluble colourless particles that can be easily removed and carried away into the wash water. So, in actual fact, it can remove bleachable dye stains. So, to kind of answer the other part of the question, laundry detergents can remove certain dyes, as well as stains.

Most dyes are composed of molecules that these ingredients can’t target. Surfactants can't globuralize the dyes, nor can enzymes gobble them up, unless they're vegetable-based. But bleach can effect dyes and this is why, washing powders designed for colored clothes don’t contain any bleach.

Why is flu more prevalent in winter?

Why is flu more prevalent in winter?

we think flu spreads better in winter because of human behaviour because it does this reproducibly in every country in the world and in which it is winter time - it doesn’t mean it goes away completely in summer but it does come much more commonly in winter.

We think that’s because it spreads better in winter because of what humans do. We go indoors more in winter so there are more people together indoors with the windows closed. Also, unlike summer time, it’s less light and therefore there's less ultraviolet radiation to dry out the virus and kill it. So 'flu finds it easier to persist on surfaces spread by coughs and sneezes, and it hangs around for longer.

As a result you have a higher chance of passing it on so that’s what we think goes on. And then the big determinant, the disproportionate determinant, is the school year. The long summer school holiday powerfully knocks 'flu on the head because kids stop mixing and spreading the infection amongst themselves. What normally happens is that they become infected and then go home and give it to their parents and the parents then carry the infection to all of the other parts of the social and age strata, usually through their workplace.

why don't woodpeckers get brain damage when they hammer into a tree?

why don't woodpeckers get brain damage when they hammer into a tree?

In the late 1970s scientists tackled this by using a very fast camera capable of taking 2000 pictures every second. Analysis of these images showed that a woodpecker's head tolerates a force of about 12 thousand times the force of gravity whenever it hits something, which is a considerable force going through its head, so why shouldn't it get brain damage? Well there are various woodpecker adaptations which means they are able to cope with this trauma, and one of them is that their skull bones are quite spongy which mean they can absorb shocks very well. Another adaptation is that a woodpecker's brain is small and so has a very big surface area to weight ratio, and so the force is spread over a large area. The photography also revealed that woodpeckers line their heads up very straight with whatever they tap into, so there's no rotational injury which, at least in people involved in car accidents, is a major cause of brain injury as delicate nerve fibres are torn by the brain trying to twist on itself.

How do whales hunt and eat prey without swallowing gallons of water?

How do whales hunt and eat prey without swallowing gallons of water?

They filter the water. If you've ever seen a baleen whale, they have a big floppy sack under their jaw, called a baleen, which works like a giant tea strainer. The whale takes a mouthful of water and then squirts it out again through the baleen, trapping all the plankton they want to eat in there so they swallow just plankton and not mouthfuls of water.

Can lightning re-start your heart?

As lightning can strike in the same place twice if you get struck by lightning and it stops your heart and then you get struck by it again would it restart you heart?

Firstly the short answer is yes, it is possible that being struck twice by lightning would firstly stop your heart and then restart your heart. The answer is a bit more complicated than that though. The heart cells maintain a voltage drop across them which controls the inflow and outflow of ions. These ions allow the heart to beat. If the heart’s struck by lightning that voltage drop is immediate and the heart will contract. Unfortunately if the lightning strikes the heart at the wrong part of its relaxation the cells will not contract together, rather chaotically. The heart will enter a rhythm called fibrillation. This doesn’t allow it to pump. For that reason the pulse would stop and the heart would be said to be arrested.

If a second strike of lightning or an electric shock occurred at the same point when a heart was fibrillating it would be possible that the heart cells would all contract together in a more ordered fashion. However, there is a problem. The heart could also be struck by lightning and instead of going into this fibrillating chaotic rhythm it could go into no rhythm at all. It could quite simply not beat again. That’s called asystole. It doesn’t end there unfortunately, our poor unfortunate victim also suffers elsewhere. It’s likely that the chest would become relatively stiff and the chest muscles would go into spasm. These muscles take a lot longer to recover than heart muscles so it would be very unlikely that your victim would be able to breathe again. For that reason, although the heart may well restart the victim may well die.

Why do some people blink more than others?

Why do some people blink more than others?

Most people blink once every two-to-ten seconds. Blinking can be triggered by dust or pollen, if you get hay fever in the summer like I do. It’s mainly controlled by nervous impulses from the brain. Everyone has a sort of blinking pacemaker in their brain and everyone’s is different. Everyone’s is set slightly differently.



This area of the brain is known as the chordate nucleus and it controls your blinking by sending impulses down the nervous system into the muscles around your eyelids. There are of course other things that can affect your blinking like fatigue and also some diseases like Parkinson’s and nerve disorders.



What’s quite interesting is that when we blink we don’t actually notice that we’re blinking because our brains filter out the signal. It’s the same as when you move your eyes around a room. Your brain cuts out the signal of when your eyes are moving so that you don’t get confused and feel like the world is spinning. It’s called corollary discharge.

If a mosquito bites someone with HIV and then goes and bites someone else will it pass on the disease?

If a mosquito bites someone with HIV and then goes and bites someone else will it pass on the disease?

Thankfully, no. Because otherwise Africa would have a much worse problem than it currently has where there are something like 4 million new cases of HIV every year. They’re thankfully not caused by mosquitoes. If they were we would all be in really serious trouble because it would be like malaria. The reason is really simple because we know that mosquitoes are very good at transmitting viruses, certainly things like dengue gets spread by mosquitoes and that’s a virus.

There’s a very good reason why this isn’t the case with HIV which is that HIV is a very specialist virus which has on its surface viral velcro, molecular docking stations that lock on to certain parts of cells, CD4+ cells which you only find in us, in humans. There’s related versions of HIV in chimpanzees (SIV) and they have their own specific cells that it locks onto. Because those specialist cells are only found in us HIV is a very fragile virus. It can’t survive in the mosquito’s intestine, it can’t latch onto cells in the mosquito, therefore the mosquito doesn’t get infected. Therefore the mosquito can’t amplify the dose from the person it bites. Therefore it can’t infect the next person because it can’t inject more viruses than it took in. HIV is very poor at infectivity. It’s actually very hard to catch, believe it or not. You can reassure everyone you’re not going to catch HIV from a bite.

How is oxygen made and recycled on the International Space Station?

How is oxygen made and recycled on the International Space Station?

The oxygen isn’t strictly recycled. The carbon dioxide that the humans breathe out is filtered out of the air with a molecular sieve then simply dumped overboard. The oxygen is created from the water that comes from the air and from the washbasins and from the loos. After that water is cleaned up it is electrolysed. An electric current is passed through it and it is separated into hydrogen and oxygen. The hydrogen is dumped overboard; the oxygen is fed into the cabin for the crew to breathe.

What happens in scientific terms in a reaction between acid rain and limestone?

What happens in scientific terms in a reaction between acid rain and limestone?

Limestone is mostly made up of the mineral calcium carbonate ( CaCO 3 ) this is not very soluble so the rocks don't dissolve very quickly. If you add an acid however you add Hydrogen Ions ( H+ ) which will react with the carbonate to form hydrogen carbonate HCO3- ions which are very soluble in water, and the limestone will dissolve. Or if there is more acid about the two Hydrogen ions will react with a carbonate to form H2CO3 which will decompose to form carbon dioxide CO2 and water H2O.

The acid can come from a variety of sources sulphur and nitrogen oxides released by burning fuels will form sulphuric and nitric acids, can carbon-dioxide can dissolve in water to form carbonic acid.

If your hair is red why does it go white? Does it change structure?

If your hair is red why does it go white? Does it change structure?

The process is very likely to be the same as any other hair colour. All you’re doing is losing from the hair the ability to add some colour. The colour is accounted for by different forms of melanin: the same hormone, the same chemical in the skin that makes you go brown. You just lose the ability to add that to the hair so you see the natural colour of the hair: the keratin and that’s the stuff which is white.

Why do we serve white wine when chilled and red wine at room temperature?

Why do we serve white wine when chilled and red wine at room temperature?

First of all, red and white wines have different chemical compositions that influence their sensory perception and their sensory traits. The aromatic white wines and these are things like Chenin Blanc, Gewurztraminer, some of the Rieslings, you serve them the coolest so it would be about 8°C. They have a relatively higher proportion of aldehydes and esters and terpenes that fill up the head space of the glass and at the lower temperature. So they will project their fruitiness which is a big part of the appreciation of those wines at a much lower temperature. The cooler temperature accentuates a bit of the acid and so, it creates a crispier, fresher kind of impression of the wine. If you do a Chardonnay-type wine or a wine in that style that is oaked, it can be served at a slightly higher temperature, so maybe 10°C, maybe 11°C. And the red wines, we have the phenolic compounds in the red wines, but with the polyphenols and the tannins, contribute to the structure in the mouth feel and that’s very much linked to the appreciation in a good quality of red wine. These components are better tasted at a slightly higher temperature. So if you chill the red wine, it’s not just that the flavour components don’t come out into the head space as well, but the tannins and the polyphenols feel much more astringent and harsher in the mouth and the acid is accentuated as well. If you serve a red wine that’s really warm, what you get then is the alcohol starts to dominate the head space in the glass and you get the perception of an alcoholic wine, and you don’t appreciate all the fruity components that are in the wine. So if we serve those at about 19°C, you get a much more pleasant overall balanced wine.

What are the dangers of hypnosis?

What are the dangers of hypnosis?

Hypnosis can help with anxiety, although sometimes the thought of going to a hypnotherapist can make them anxious. However, they have nothing to be nervous about if they go to a properly qualified person. Among professionals, we always say that someone shouldn't treat someone with hypnosis if they wouldn't be competent to treat it without hypnosis. With an anxiety problem, you would probably be thinking about going to see a psychologist. If that psychologist knows how to do hypnosis, he may think about using that as an additional tool. This can help with the effectiveness of the treatment normally given. There is nothing harmful about hypnosis in itself as long as you go to someone properly qualified.

How does something like radiotherapy treat prostate cancer?

How does something like radiotherapy treat prostate cancer?

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.

Does eating chillies help with neuralgia?

Does eating chillies help with neuralgia?

It's not the actual eating of the chillies. The thing that makes chillies hot is called capsaicin. Not only does it make things taste hot but can also be used as a topical ointment on the skin if you have various pain syndromes. One of those is shingles. If you've had chickenpox in the past then you have chickenpox living in your nerve fibres in your body for the rest of your life. Periodically it can come back out and cause a patch of chickenpox vesicles or blisters on one patch of skin. After they go away, it can be tremendously painful. However researchers have found that if you apply this capsaicin to the painful area, it can actually help to relieve the pain. This could possibly be because pain is mediated in the nervous system by a class of tiny nerve fibres referred to as C-fibres. Capsaicin activated those nerve fibres and in some cases activates them to death. This turns them off and indirectly makes them less sensitive, which is why the pain goes away.

Is it dangerous to live 500 metres away from a mobile phone mast?

Is it dangerous to live 500 metres away from a mobile phone mast?

It's far less dangerous than using the phone yourself. No one's actually found a dangerous relationship with using a phone. When you use a phone, that transmitter is a couple of centimetres away from your head, and the strength of the signal goes down with the distance squared. So it's going to be thousands and thousands of times weaker than your mobile phone right next to your head.

To explore the science of this - if you look at the energy of a microwave, and the reason we have these things in our kitchen and cook with them and we are happy to put a microwave source or a mobile phone to the side of our heads, is because the energy in the wave of a microwave is not sufficient to break chemical bonds in the same way that an x-ray or a gamma ray, or more intense forms can. And therefore they're viewed as non-ionising forms of radioation, and are viewed to be safe. That said, there's no evidence that if you do expose your nervous system to these things that they won't have a temperature effect; because we think that they might warm your head up a little bit if you're exposed to a phone. But of course the mast is much further away than a phone is. But also, exposing tissue to microwaves for long periods of time may or may not have some sort of growth related effect.

Certainly in terms of cancer there isn't enough energy in phone radiation to damage DNA which is the ultimate cause of cancer. Virtually all the studies that have been done have not found a significant link between mobile phone use and cancer. The one thing we don't have is really long term data and that's hopefully coming in in the next couple of years. But the studies certainly haven't found an effect in terms of cancer.

Is it safe to swallow chewing gum ?

Is it safe to swallow chewing gum ?

Chewing gum used to be from a rubber plant, but is now artificial. It sticks to the road because it contains long oily polymer chains which are chemically similar to some of the constituents of the road surface. It's very hard wearing stuff and doesn't get digested when you swallow it. It can cling onto the sides of your intestines and distort the gut, are occasionally trigger a dangerous disorder called intussusception where the gut telescopes inside itself, although this is rare in adults. It would be better for the environment if people could swallow it. Until then, it would be good to develop a family of chewing gum-consuming bacteria that could eat it off the pavement !

Why don't spiders run out of silk?

Why don't spiders run out of silk?

Spiders are really actually quite clever. Ancestrally they go back a couple of hundred million years, we think. They have glands at the back end of the spider and now it turns out also on their feet that make silk. And what scientists think, is that the glands on the back of their abdomen that make silk are just adapted limbs, where they used to have some legs. Silk is the reaction of proteins. So you have a chemical reaction going on at the back end of the spider that literally spins silk on demand. The spider eats something that has got protein in it. So when it goes and catches something in its web, it injects a venom into that insect that kills it by paralysing it. The insect is paralysed and doesn't die instantly so it remains fresh, the spider injects digestive juices which liquify an insect. And because an insect is like a husk, with a hard skeleton on the outside with the soft bits in the middle, the spider can literally suck the good bits out of the inside leaving behind a dry, wizened up shrivelled skeleton. That's why you see these sort of husks of insects left under spider webs. All the protein and goodness from inside the insect ends up inside the spider, the spider digests that, absorbs it, and then the proteins go to the back end of the spider. And they get turned into new web, amongst other things a spider needs to make. And some spiders have taken this a step further. What they've done is to make the process even more efficient, by eating their own web. This doesn't do them any harm because web is just protein. By eating their own web they're getting the proteins back into their body and they can then reuse them. Spiders' web is incredible stuff and it can absorb immense amounts of energy. It's got the tensile strength of steel. Scientists are now looking at ways of using it for bullet-proof vests, for example. If you can make this artificially in enough quantities you've got something with the tensile strength of a piece of steel, and the ability to stop bullets much better than a bullet-proof vest. Which means rather than police having to go around in these very thick outfits which restrict movement, if you could make it out of spider silk it would be a) lighter, b) a breatheable fabric, so it wouldn't make you so hot and uncomfortable, and c) it wouldn't restrict your movement so much.

How are seedless grapes grown?

How are seedless grapes grown?

The correct answer is that the plants that grow them are actually clones. So instead of growing them from seeds, they're grown from cuttings, so from existing plants. So obviously the first seedless grapes were a plant that arose through mutation, that means that they don't have seeds. And some growers must have noticed this. And you can basically take a little shoot or a stem off the plant, dip it in rooting powder, put it in the ground, and a new tree will grow. This is how a lot of plants are cultivated now, and also a lot of seedless varieties. It's causing problems now with bananas though. Because they're all clones, they're getting struck down by funguses and things. If a population is genetically identical, it can very easily be wiped out because it has the same resistance to different pathogens.

Does drinking too much milk, or calcium, reduce your physical endurance or stamina?

Does drinking too much milk, or calcium, reduce your physical endurance or stamina?

If you drink milk that isn't skimmed, it's got lots and lots of fat in it. Having lots of fat isn't good for you because of the calories, but also because it furs up your blood vessels. Milk is also very rich in calcium which, in people who are prone to stones, can deposit in the kidney and cause kidney stones. And the other side effect of milk that not many people know, is if you have irritation to the stomach lining and you're at risk of getting stomach ulcers, calcium is used as a co-signal by the wall of the stomach to produce acid. If you have calcium levels in the blood going up, you make more acid. Some people think when they have a dodgy stomach that drinking milk will settle it. When you first do that your stomach feels happier because you've given the acid something to eat other than the wall of your stomach. But then the calcium is absorbed and goes into the blood stream and increases the amount of acid your stomach makes, causing a vicious cycle.

Does peanut butter help to lower your cholesterol?

Does peanut butter help to lower your cholesterol?

eanut butter is a source of mono-unsaturated and polyunsaturated fat. So in the context of a balanced diet, it is likely to have some beneficial effect if you are at the same time cutting out saturated fat. So it's really about replacing say the amount of red meat you might be eating with things that are rich in vegetable fats. Another good example of this would be Soya beans. Soya beans are a good source of vegetable fats.

Everybody knows that salt melts ice. Why are there such big icebergs in the sea?

Everybody knows that salt melts ice. Why are there such big icebergs in the sea?

Salt makes ice melt at a lower temperature. So in sea water ice will melt at maybe -5 or -6 degrees centigrade. But if you get cold enough, the water will still freeze. And so you can still get icebergs. It's just got to be a bit colder than if it was in a lake. When there's salt in water, the water can get a bit lost in the salt. It gets in the way of the water forming a crystal. It's more difficult for the water to form the crystal, so it has to be a bit colder for it to actually freeze.

Could sound waves be heard on Mars?

Could sound waves be heard on Mars?

There are two questions here. One is if we had a very loud screaming baby on the Earth, would somebody on Mars in theory hear the baby screaming, or would you need to have some interplanetary baby monitor? The answer is no, you wouldn't be able to hear the sound from Earth on Mars because the space in between Earth and Mars is a vacuum. There's a wonderful experiment you can do where you put an alarm clock under a bell jar and you start a vacuum pump going. You then stop hearing the bell even though the bell is still going. But then the question is, well what if your baby was in the bedroom in your Mars planetary home? Would you be able to hear the baby crying from downstairs in your bedsit? The answer would depend very much on the atmosphere on Mars and my understanding is that there's not very much atmosphere: about 1% of the atmosphere on Earth, so it's getting close to a vacuum. So there are two things: the amount of energy that you can pump into the atmosphere is less; and also the speed of sound would be a lot faster.

Does the sun affect the tides like the moon?

Does the sun affect the tides like the moon?

Yes, but to a lesser extent than the moon, which is the main determinant of our tides. You can work out if we are on a neap tide or a spring tide - that's a high tide or a low tide - depending on whether these two celestial bodies line up with each other. When the sun is in alighnment with the moon we have a new moon (which means you can't see it because it is not illuminated and is dark) and the two bodies work together gravitationally, producing a spring tide. Two weeks later, however, the moon is at 90 degrees to the sun, so they're not in alignment, so you have a neap tide. Two weeks after that you have a full moon and the two are working together again, and you have a spring tide.

Why is it helium in balloons and not hydrogen?

Why is it helium in balloons and not hydrogen?

In order to get a floating balloon you want a gas which is as light as possible. Helium is quite a lot lighter than air weight. It’s about and eighth of the density of air. Hydrogen is about a sixteenth the density of air. So it’ll float in air and will even float upwards. You’d have thought that hydrogen would be a better gas as it would give slightly more lift than helium because it’s lighter. This is true. The problem is hydrogen is explosive and if you have children running around with balloons that could catch fire and blow up in their faces, it may have some health and safety implications. The other thing is that although hydrogen is half as heavy as helium it doesn’t give you twice as much lift because the amount of lift you get is in its difference in density with [respect to] air. It’s actually only another sixteenth of the density of air. It’s a little bit better but not very much, so it’s not worth the danger.

Helium is quite expensive, though, because it’s a limited resource here on the planet. It's only created by radioactive decay on Earth. Atomic nucleuses emitting alpha particles that are actually helium nucleuses. They slow down and gain some electrons and turn into a helium atom. It tends to be found in oil wells where you get a gas-proof layer of rock above a load of rocks containing radioactive elements. They break down to helium. It floats up and gets trapped, often at the top of an oil well . The amount of helium that we can access cheaply is very limited because not all our oil wells have it.

What happens when a bomb explodes underwater?

What happens when a bomb explodes underwater?

Well when any bomb explodes the first thing you're going to get is a lot of high-pressure gas because you've taken a load of solid and turned it into gas. It wants to expand. Water isn't going to move away nearly as quickly as air does. The pressure's going to remain very high, pushing water away. The fastest the water can move away is roughly the speed of sound in water. That's 1400m/s. You're going to form a bubble. As that water is pushed away very fast you're going to get a second powerful sound wave or pressure wave moving away from it. If the water doesn't compress that's going to have a very high pressure and do a lot of damage which is why depth charges can destroy strong things like submarines, even 10-20m away. Apparently it's way that there's a theory of how you might be able to blow up safes. If you fill a safe with water an drop a small charge in then because the pressure change is so much greater it might blow the door off.

Why do babies get jaundice when they are born, and why does a session on a sun bed help get rid of it?

Why do babies get jaundice when they are born, and why does a session on a sun bed help get rid of it?

Babies are not actually born yellow; it develops when they are first born. Every minute we make lots of red blood cells to replace those that have worn out. When old red blood cells are broken down, a yellow-coloured waste product, called bilirubin, is produced. Bilirubin is insoluble in water until it is metabolised by enzymes in the liver which add sugars to the molecule to help it dissolve meaning that it can be excreted in bile, and in urine. However, a developing baby doesn't need this biochemical pathway for metabolising bilirubin until it is born, because the mother removes the bilirubin via the placenta. But when some babies are first born and can no longer rely on their mother to help remove bilirubin for them, particularly if they are premature or have liver problems, there can be a delay in switching on this metabolic pathway and a backlog of bilirubin builds up around the body, making the child yellow. Because , until it is metabolised, bilirubin is insoluble in water but dissolves very well in fats, it accumulates in the skin, where we store most of our body fats, explaining why the babies appear yellow. If it is allowed to continue for a long time, jaundice can cause permanent damage to the brain, but if the baby is put under a blue light, a photochemical reaction occurs, breaking up the bilirubin and making it water soluble. This allows the baby to excrete the excess bilirubin in its urine. The process was discovered accidentally by Judith Ward who used to take babies into sunlight because she thought it was good for them. Having returned them to the hospital, she found that a previously-jaundiced baby had normally-coloured skin on sun-exposed areas, but yellow skin where the nappy had been. As a result the method was quickly adopted for the treatment of neonatal jaundice.

What ingredients go into antibiotics, and how do they work ?

What ingredients go into antibiotics, and how do they work ?

Tablets taken by mouth contain a lot of the actual antibiotic. They also contain lots of other substances which enable the manufacturer to produce a tablet that can be kept in packets and are easy to swallow. For example, the smooth outer coatings of some tablets are often made out of vegetable products. Once the tablet is in your stomach, the active bits distribute around the body through the bloodstream, reach the site(s) of infection, and kill the offending bacteria. There are three different ways antibiotics kill bacteria. Some stop bacteria from growing by stopping their protein production; others stop them from making chromosomes; and the third type stop bacteria from making cell walls. Without a proper cell wall, the bacteria explode and die.

Which bacteria or viruses cause ear infections ?

Which bacteria or viruses cause ear infections ?

The ears have the same linings and are connected to the nose and throat through the eustacian tube. This means that any of the viruses that cause colds and sore throats can get through into your ears. Viruses are the main invaders, but bacteria can cause secondary infection. They seize the opportunity to invade after a virus has caused the initial problem - such as damaging the protective lining of the airway, or blocking up the eustacian tubes in your ears with mucus

Are fizzy and sweet drinks addictive?

Are fizzy and sweet drinks addictive?

Coca Cola, most other fizzy drinks and cold remedies contain huge amount of caffeine. This is a legal drug that gives you energy and perks you up. This is why taking certain 'flu remedies make you feel more awake and generally much better. These are similar effects to those found when drinking coffee. There are specific receptors in your brain for caffeine. These interact with a part of the brain that uses the reward-chemical dopamine, the same system activated by drugs such as cocaine. Although caffeine and cocaine don't give the same kind of rush effect, both have a common mechanism. It's also worth bearing in mind that tea also contains a lot of caffeine.

What keeps the Earth's core so hot?

What keeps the Earth's core so hot?

It's a combination of things. One, the earth's quite a big planet relative to Mars which is a bit smaller. There was a lot of heat that was in the Earth to start with. When the planets were first forming around the sun in what's called a protoplanetary disc a lot of the swirling and spinning material was crammed together and squeezed together. It had a lot of heat from that, those frictional effects. Also the Earth has what's loosely termed as radioactive compounds in the Earth. As these radioactive compounds break down and decay they produce heat. The heat is obviously concentrated in the core of the Earth and then filters up towards the surface. Because the Earth's a big planet it's got a big core. It's got lots of radioactive decay going on. Some of the heat that we're seeing is because the Earth is sustaining it's own heat by radioactive decay.

How can we tell what noises the dinosaurs make ?

How can we tell what noises the dinosaurs make ?

The reason you hear those sounds on TV is to make it more interesting. We know dinosaurs probably made noises because they had very good sense of hearing. If you look at dinosaur fossil skulls, you can trace their ear canals and work out where their ears would have been and the kinds of sound they would have responded to. If they could hear sounds, they could probably make sounds. In the late 90's scientists put a fossil through a CT scanner to look at the bone structure. The headpiece was a series of intricately connected tubes a bit like organ pipes. They analysed the structure of these canals and airways, and used a computer to model what would happen if air were blown past. They found that the dinosaur could probably have produced low pitched rumbling noises that could have carried a long way. So what we use for dinosaur sounds on TV is what can be inferred from studying the shape of their fossilised remains, with a bit of artistic license thrown in.

Why do mints make your breath feel cold ?

Why do mints make your breath feel cold ?

According to a group of scientists in San Francisco, the reason is that the same nerve fibres that signal hot and cold are also sensitive to menthol, an ingredient in mints. Normally when the temperature changes it causes pores on the surface of the nerve cell to open and close, changing the electrical activity of the cell, which the brain interprets as a change in temperature. But menthol can also affect the function of the pores in the same way and triggers the nerve cell into thinking that the temperature is lower than it is.

Who is sweatier, men or women ?

Who is sweatier, men or women ?

Men are definitely sweatier than women. Previously this was put down to the larger male stature, but a team of scientists at University of Dortmund, Germany, led by Barbara Griefahn, say different. In their laboratory they have set up a mock 'sweltering car'. 'Volunteers' sit for up to 2 hours under heat lamps, mimicking the effect of the sun beating down through the windscreen. Under these conditions men lose about 250 mls of sweat per hour during the experiment, 70 mls an hour more than female volunteers. This makes them officially sweatier, even allowing for size and weight, say the scientists.

Is it normal for you to have a body temperature lower than 36.7celsius ?

Is it normal for you to have a body temperature lower than 36.7celsius ?

Normal body temperature is 37?C. This is set by part of your nervous system and the hypothalamus, which is found in the brain stem. The hypothalamus monitors your body temperature and changes it if it becomes too hot or too cold. Your body temperature doesn't have to be exactly 37?C: exercise can make you hotter, while going outside on an icy day can make you cooler. The place in which you measure your temperature is very important. Putting a thermometer under your armpit will show you your peripheral temperature, and this can be quite a bit lower than your 'real' body temperature called your core temperature, or the temperature at the centre of your body. This varies very little at all in day to day life. It can best be measured by putting a thermometer in your bottom! You have to get very cold to change your core temperature, such as being stuck in freezing weather for a long time. People who have a drop in core body temperature have what is known as hypothermia. This makes them drowsy, and if left untreated, they will eventually become unconscious. When the body is cold, the chemical reactions that provide your cells with energy don't work as well. This makes cells function abnormally and, if prolonged, can be fatal.

Does the nicotine vaccine stop the cravings to smoke?

Does the nicotine vaccine stop the cravings to smoke?

Probably not. The mechanism works by stopping the effects, and so might actually increase the cravings. The vaccine is probably best used in combination with something that helps with the withdrawal symptoms. However, by stopping the effects, it also helps to break the cycle of reinforcement. Eventually this may lead to people stopping people smoking because it does nothing to help the cravings.

Which bacteria or viruses cause ear infections ?

Which bacteria or viruses cause ear infections?

The ears have the same linings and are connected to the nose and throat through the eustacian tube. This means that any of the viruses that cause colds and sore throats can get through into your ears. Viruses are the main invaders, but bacteria can cause secondary infection. They seize the opportunity to invade after a virus has caused the initial problem - such as damaging the protective lining of the airway, or blocking up the eustacian tubes in your ears with mucus.

What causes narcolepsy?

What causes narcolepsy?

Narcolepsy is the disorder where people fall asleep repeatedly during the day and there seems to be genetic component to this. Luckily there are drugs which can be used to treat it. There can be frightening aspects to narcolepsy, for instance people have been known to suddenly fall down as they fall asleep, or have nasty hallucinations as they fall asleep. The brain chemistry behind it is better understood now, and we do know about the genes that are linked to this. One particular chemical is a substance called hypocretin, and people with narcolepsy tend to have problems with the receptors for this brain chemical, or an abnormal form of this chemical. There are also people with 'clock' genes that give them a faster or slower body clock, but this shouldn't be mistaken for narcolepsy.

Would someone with a psychiatric disorder be better able to pass a lie detector test as they may not feel remorse?

Would someone with a psychiatric disorder be better able to pass a lie detector test as they may not feel remorse?

Old-fashioned lie detectors like the polygraph only detect stress. If the lack of remorse meant that the interviewees had reduced stress levels that would help them pass. Our lie detector, Silent Talker, makes its judgement on non-verbal behaviour: crudely what people call body language. Silent Talker can detect stress but lying involves other factors. We can only juggle a certain number of mental variables at once while we’re thinking. If we’ve got to try and maintain a whole load of different factors about an imaginary story it’s very difficult to do all the mental processing to keep that consistent. That’s what’s known as having a high cognitive load which affects non-verbal behaviour. Also duping delight occurs when liars get a kick out of getting a lie across successfully and again this affects non-verbal behaviour. In one of our own experiments on the general population we taught silent talk to recognise guilty feelings the participants felt while they were lying. When we added this information to the general lie detection we got more accurate classifications. In another independent study conducted by a different university using Silent Talker it was found that Silent Talker was effective at detecting lies told by psychopaths in interviews. So there we have it: evidence that remorse is a factor in the general population but also evidence that in the case of one disorder it’s not the only factor.

Why do we laugh when we find something funny?

Why do we laugh when we find something funny?

Something that’s funny is by definition something that makes us laugh. I’ll talk about why we laugh. Laughter is really a social phenomenon. If we look back to its origins, laughter, the ‘ha ha’ originated in the ‘pant pant’ of rough and tumble play such as you would find in tickle or the rough and tumble play of children. ‘Pant pant’ became the human ‘ha ha.’ With adults, however the arena of laughter has shifted from tickle and rough and tumble to a more linguistic and cognitive arena whereby, for example, the play of adults has to do with wordplay during conversations. You don’t have to tickle one of your colleagues to get them to laugh. You can tell them the joke. Even within conversation the key to laughter is the presence of another person. Laughter almost totally disappears when we’re alone. The key element for producing laughter is another person and not a joke. In fact we have followed people around and recorded what was said before people laugh. In only 10 or 15% is it anything remotely joke-like. Most laughter follows comments like ‘hey, where have you been? Ha ha!’ or ‘I’ve gotta go now, haha!’ These aren’t jokes so it basically is about developing bonds and relationships with other people.

Why does one get cramp?

Why does one get cramp?

Cramp is a muscle spasm and we don’t actually know what cramp is. We just know that if people have regular cramps – and it tends to happen quite often at night and it tends to happen in younger people more often than older people and it tends to be relieved with quinine, the same stuff that makes tonic water taste nice. A muscle spasm is when some of the muscle fibres – because a muscle isn’t just one homogeneous giant thing. It’s actually made up of lots of individual little muscle fibres. Some of those muscle fibres go into a spasm. In other words, the contract more than they should and they lock in a contracted state. Surprisingly, muscle actually takes energy to relax, not to contract. When a body of a person dies, they go into rigor mortis because the cells in their muscles run out of energy and their muscles can’t relax and they stay rigid. That’s why a person gets rigor mortis. If you leave them a bit longer then the rigor mortis goes away again when the muscle breaks down and starts to relax. What cramp could be is for some reason that clutch of muscle fibres don’t have enough energy in them, perhaps because there’s been a reduction in blood flow that’s insufficient for the muscles needs. Therefore the muscle runs a little bit short of energy and this trips its inability to relax properly and you get a cramp. Rubbing a muscle and massaging it to get the blood through it can make it better.

Why do we wake up when we need to urinate?

Why do we wake up when we need to urinate?

It’s the same reflex if you need to roll over in bed when you’re uncomfortable. If you stayed in one position in bed all the time all night you would get a pressure sore because the pressure of tissue against the bed would stop blood flow through that area. As a result you would end up with a de-vascularised bit of skin and it would necrose. Patients who are left in one position in hospital for too long get exactly the same problem. The body has a series of reflexes programmed into it even when you are asleep. You can react and respond to various stimuli with an appropriate thing. If you’re getting uncomfortable in bed you can roll over. If, on the other hand, your bladder’s getting full then your brain says wake up, you need to go to the loo. It’s an automatic reflex. Some people lose that reflex as they get older. Some people when they’re very little actually wet the bed because it hasn’t developed yet. That’s why little kiddies have to respond to those signals the right way. That’s all about potty training and bladder training.

Why are Australian snakes so much more toxic in general than other snakes in other parts of the world?

Why are Australian snakes so much more toxic in general than other snakes in other parts of the world?

The idea that Australian venomous snakes are more toxic than those anywhere else is, to a large extent, a myth which started out with a study that was published approximately thirty years ago. They took 25 different snake venoms and showed that the top ten of those were Australian. It only included five non-Australian snakes so it’s rather like the American baseball World Series: you can’t lose if you don’t include the competition. In reality the two snakes in the world with the most toxic venoms drop for drop are in fact Australian. Immediately after that when you look at the table of most toxic venom's you start having a large number of other snakes coming in. A large number of Australian venomous snakes are actually not spectacular at all in their potency of their venom. There’s nothing intrinsic about Australian snakes being particularly toxic. The amazing thing is that the snake with the most toxic venom in the world – the inland Taipan has never actually killed anyone. Some snakes live in remote areas and in places where there is no medical treatment and other snakes live in areas which either are very remote and people don’t go to so they don’t bite anyone or there is good anti-venom and good treatment available. If you’re bitten in Australia a flying doctor comes and picks you up and you go to a hospital and 99.5% of cases everything’s going to be just fine. If you get bitten in West Africa then there is no anti-venom, there is no hospital that can treat you and you slowly bleed to death from a snake that has a fraction of the killing power.

Could the retina be repaired using stem cell research?

Could the retina be repaired using stem cell research?

In the last twelve months we’ve seen evidence that perhaps it can. The stumbling block at the moment is that perhaps we don’t have the stem cells necessarily, ethically, to do it. Scientists in University College London published a paper in the journal Nature about this time last year. They took mice which had been genetically programmed develop a disease like the human disease, macular degeneration, and they took stem cells from the retina of newborn mice. They implanted these stem cells into the eyes of the mice that had macular degeneration. They were able to show that the mice got back their ability to see. By following where the stem cells went in the eyes they found that they migrated to the right part of the retina and turned back into photo-receptors. These cells take the light and turn it into information that the brain can understand.

Sharp Sounds Damage Hearing?

Which is worse for your hearing - the short sharp sound of a hammer, or the constant drone of a chainsaw?


Whenever you listen to sound, the sound actually hits the eardrum. That sound is actually amplified by a series of tiny little bones in the ear called ossicles. These ossicles vibrate and stimulate the float within the cochlear which, in turn converts the sound energy into electrical energy which is perceived
as noise by the brain.

There are two different types of noise induced hearing loss. You have acute stage hearing loss, for example due to a large explosion or you may have something more gradual. This is more common in most people. This gradual increase in hearing loss is a combination of both the intensity of the sound as well as the duration of the sound. So for example, someone who shoots guns for a hobby may be exposed to very short bursts of noise but very high intensity and they may experience a similar degree of hearing loss compared to someone who's in a slightly different environment where the sound intensity's actually much lower but much more constant (e.g. the mining industry). There are also additional factors that can influence noise induced hearing loss. It's not just the combination of noise because people's tolerance to noise varies. Therefore there's some genetic influences in this as well. Noise induced hearing loss is not just the simple of noise experienced but also the genes that influence your hearing.

If you get cold sores and give blood, can the virus be passed on?

If you get cold sores and give blood, can the virus be passed on?

There’s probably almost zero chance of that. The virus that causes cold sores, the Herpes Simplex Virus (HSV), most of us acquire this when we’re very young because of our parents kissing us and children dribbling over each other in nurseries – it spreads in saliva. When you first get it, it produces a sore throat, ulcers in the mouth, swollen glands in the neck and a high temperature. It then invades the sensory nerves that supply your mouth and tongue, as well as other parts of the body it can infect. It goes inside these nerve cells and switches off. It exists there as a piece of DNA, loitering alongside the cell’s own DNA, and periodically comes back to life. We don’t know exactly what triggers it to come back to life, but we know that things like damage to the skin, for example sunburn, menstruation, depression and immune depression, can bring it out again. The virus turns back on its DNA, makes new virus particles which come down the nerve and pop out of the skin, causing the infectious lesion, the cold sore. When you kiss someone who’s got one, that’s how you pick it up.

Thankfully, it doesn’t really get into the blood stream, so you should be safe from HSV from blood products. Other members of the herpes family do spread through blood, but not HSV.

What causes sleep apnoea?

What causes sleep apnoea?

You are lucky to have had it diagnosed because lots of people with it and are undiagnosed. People who have apnoea stop breathing, maybe hundreds of times a night, which means that your brain is regularly starved of oxygen producing symptoms of tiredness, poor concetration and irritability the next day. There is a way of treating this and that is to wear a mask which pushes air down into the lungs under pressure - maybe your doctors have told you about this - but you'd need to use this every night for life. There are two possibilities for what causes sleep apnoea: central apnoea is where the bit of the brain which tells you to breathe whilst you're asleep switches off - but this is rare. More common are problems in the throat so when you fall asleep your muscle tone goes away and your throat collapses, obstructing the airway. This is why pushing air down with a mask can help. People who have this can have surgery to correct it, but the surgery is fairly major.

What are the risks associated with tubal ligation and vasectomy?

What are the risks associated with tubal ligation and vasectomy?

Tubal ligation means that you go inside the peritoneal cavity in the woman, in the pelvis. You identify the fallopian tube on each side. You can see that quite easily because they’re about 5 mm across, and you clamp them. You put a very large paper clip which is squashed onto the tube, and it crunches the tube closed. And the idea of that is that then what it does is basically squashes the tubes so that the egg released by the ovary cannot make its way down the tube to get into the uterus. And at the same time, a sperm cannot get along the tube to meet the egg and fertilize it. Otherwise, you might get the risk of what’s called an ectopic pregnancy, the actual egg starting to be fertilized and grow outside the uterus.

The risks of tubal ligation are that it doesn’t work. It’s a small risk but there’s nonetheless a risk that you could fail to completely close off the pathway. Another possibility with any invasive procedure is, of course, that you can cause pain. You could cause bleeding. You could get a localized infection.

With vasectomy, it's a very safe procedure, pretty similar though. You basically are cutting, folding back on themselves and tying off the vas deferens, which are the tubes that carry sperm from the testicle up inside the body. The idea being that then you interrupt the route that the sperm will follow after the testes. The risks are pretty similar to having tubal ligation and the fact is that occasionally there is incomplete severance. There may be a route by which sperm can still make it through. Also, you don’t stop being fertile. The minute you have it done there’s a flush out or a washout period afterwards.

And so if someone just has a vasectomy and then assumes they’re now no longer capable of fathering children, they could be in for a shock.

Why is it that stars appear spiky and not spherical? And why do they twinkle?

Why is it that stars appear spiky and not spherical? And why do they twinkle?

The main reason that stars look spiky is that the optical instrument you are looking at them with is not perfect. Because light is a wave, if you shine it through a small hole you get a pattern known as an interference pattern, this is because different light waves interfere with each other, making patterns of light and dark.

If the hole was circular you would get a relatively clean picture, but if it isn't then you will get various visual artifacts. These are much dimmer than the object itself so during the day you can't see them, but if a bright object is surrounded by darkness they are very obvious.

So if you look at a streetlight you often see streaks coming off it. If you squint, you make your pupil even less circular so the streaks get much stronger. The interference pattern will have a similar symmetry to the hole, so if you squint your eyes into a slit you get 2 strong streaks. Your camera doesn't have a perfectly circular aperture so you get streaks, the number will depend on the shape of the aperture.

Large telescopes need structures to hold their secondary mirrors, and it is the diffraction from these that you see in pictures from the Hubble Space Telescope etc.

But the reason they’re actually twinkly when we look at them is nothing to do with that. They’re twinkly when we see them through the Earth’s atmosphere because the Earth’s atmosphere is not uniform. There’s air which is at hotter temperatures, and therefore, less dense, and there’s air which is at colder temperatures, and therefore, more dense. And when light goes from a medium, which is more dense, into a medium which is less dense, it changes speed. In fact, it speeds up a bit. And it’s that change in speed that causes the light to bend a little bit. And that means that when you see rays of light coming from a long way away, they appear to be coming from one place, and then another place, and another place, and then another because the light rays are being bent alternately as it goes in and out of warm and cold patches of the Earth’s atmosphere. And that’s what makes the star twinkle. And you see the same thing happening if you look at the lights from a harbour across a sea harbour or a port, for example.

What is it that keeps planets spinning, as well as keeping them moving in their orbits?

What is it that keeps planets spinning, as well as keeping them moving in their orbits?

Well, it’s a fairly simple piece of physics. One of the things that keep on moving their orbit, there’s nothing to stop them. They’re not hitting anything, so to speak. So they’re not losing any energy, and they’re not losing, more importantly, angular momentum. So angular momentum is a conserved thing. It can’t just be taken away by, just by wishing it away. It has to be taken away by things, and the Earth is just sitting there, rotating. Nothing’s taking its angular momentum away except the Moon. The Moon is actually going to steal some of the Earth’s angular momentum, slow it down, and at some point in the future, the Earth and the Moon will be locked together they would both have lost angular momentum. At the moment, we only see one face of the Moon. In the future, only one face of the Earth will be facing the Moon. So we’ll only be able to see the Moon from one side of the Earth, and vice versa.

Do bacteria have intelligence? How do they find their food?

Do bacteria have intelligence? How do they find their food?

Bacteria have no brain, but on the surface of a bacterial cell there are receptors for different chemicals. This means that they can tell which way to travel by comparing, chemically, how many of those receptors have things that they like attached. They assume that the side with the most ‘good’ receptors filled is closest to their food. They use this concentration as a guidance mechanism to control where they go.

Bacteria travel towards desirable chemicals, or away from toxic ones, using a flagellum. This is like a propeller, powered by a protein ‘motor’. When the ‘motor’ burns energy it causes the protein to change shape, quickly spinning the long ‘tail’ part. This lets bacteria move so quickly that they are officially the worlds fastest swimmers, and can travel 60x their body length in each second.

Why do different types of meat get different colours when they’re cooked?

Why do different types of meat get different colours when they’re cooked?Beef turns dark brown, pork light brown and chicken turns white. Most fish are also white, except for Salmon and some other red fish. What makes the difference in the colour?

Its down to a chemical called myoglobin. Myoglobin is a bit like haemoglobin, the red coloured stuff that ferries iron around in the bloodstream, except myoglobin is locked up in muscle (and meat is muscle). Red meat contains a lot more myoglobin than white meat, as the muscles that tend to be red are the ones most active in an animal. The legs of a standing animal will be redder, and have more myoglobin, as the muscle has been tuned up for long term activity.

Muscles that aren’t used as often, fast-twitch muscles, tend to have low blood supply, little myoglobin, and therefore little colour (white meat). Chicken breast and wings don’t get a huge amount of use (as chickens don’t fly), and so they are white muscle.

With fish, most of our salmon has a red colour because we tend to buy farmed salmon, and to keep the meat looking a healthy colour the fish are fed astaxanthin. They would get this in the wild environment from yeast and from algae, it’s an antioxidant similar to the chemical which makes carrots orange. Shrimps eat the algae, salmon eat the shrimps and the colour passes through the food chain.

Everybody knows that salt melts ice. Why are there such big icebergs in the sea?

Everybody knows that salt melts ice. Why are there such big icebergs in the sea?

Salt makes ice melt at a lower temperature. So in sea water ice will melt at maybe -5 or -6 degrees centigrade. But if you get cold enough, the water will still freeze. And so you can still get icebergs. It's just got to be a bit colder than if it was in a lake. When there's salt in water, the water can get a bit lost in the salt. It gets in the way of the water forming a crystal. It's more difficult for the water to form the crystal, so it has to be a bit colder for it to actually freeze.

Should coffee be stored in the freezer?

Should coffee be stored in the freezer?

The main reason you want to freeze it is to keep in all the volatile chemicals and aromas. If you keep it in a warm place then the volatile chemicals come out of the coffee and it won’t taste as good.

What's actually happening when you fry food?

What's actually happening when you fry food?

Its called the Maillard reaction after a French chemist Louis Camille Maillard. This is a chemical reaction between carbohydrate groups (that's sugars largely) and protein or amino-acids (those are the building blocks of proteins). It takes place at around 148 degrees and when these sugar groups lock on to the amino-acid groups they form these nice, brown caramelised substances which taste great – that's the nice aroma you get from cooking. As it happens at 148 degrees – that's 48 degrees hotter than water boils at – that's why you get a very different consistency and taste and texture to fried food compared to boiled.

How do cats purr?

How do cats purr?

Now, there isn’t really a special purring organ in a cat. It’s simply a very fast movement of their voice box. So it’s fast twitching of the muscles in their larynx which rapidly kind of flap up and down something called the glottis. That’s some little flaps inside your throat, and it causes air vibrations when you inhale and exhale. And interestingly, a fact for you is that tigers, lions, jaguars, and leopards can only purr when they’re breathing out!

If human and worm DNA are so similar, why are we so different?

If human and worm DNA are so similar, why are we so different?

There are certain major genes, sometimes called Hox genes and sometimes called developmental genes, that switch on a whole suite of other genes. They are simply like switches in early developmental processes. To give an example that's a little bit closer to home, look for the nearest man and see how different you are from that person. Now although not everything that's different is down to one gene, the fact that you are female and he is male is down to a single gene called SRY. Very early in development, if SRY is present it makes testes, and if it's not, ovaries are made. So you've got just one single gene that switches over from one type to another, and then everything else follows from that, including the hormones produced by testes and ovaries. In worms, they've got a different set of these Hox genes, which start the whole process off. They're switching on a completely different set of genes in a different order, and so the developmental process is utterly different.

What would happen if a bird drank fizzy water ?

What would happen if a bird drank fizzy water ?

Legend says that giving birds fizzy water can make them explode as gas builds up in their stomachs. But this is probably not correct - birds can burp it up. Bird's guts are somewhat different to humans, containing different chambers, but they do have an oesophagus which allows the bird's food to reach the crop (where a human's stomach would be). As bird's have no teeth they swallow food whole. It travels down to the crop ready for regurgitation to feed their young. It follows that, if they can regurgitate food, they should be able to regurgitate gas too. However it's not really natural for birds or other animals to drink fizzy water so best to stick to still water for your pets!

Where does all the sand in the Sahara desert come from?

Where does all the sand in the Sahara desert come from?

Sand is tiny fragments of rock. When rock wears down you get smaller bits of rock, or pebbles, and when they wear down you get even smaller bits and eventually you get down to sand, or silica. The reason it ends up washing up on the beach is that the sea or wind can move sand around very easily while rocks are more likely to stay put. This separates things by size, and the sand ends up on the beach and the rocks end up on the seabed. There were lots of sand stones in the Sahara which have weathered and broken down over time from rain, and sun and wind. This has produced accumulations of sand which have built up over time to produce this massive desert. Rocks are made up of lots of different things other than silica, or quartz. But the silica is the toughest material which is why it gets left over after a lots of weathering, when everything else has dissolved or turned to dust.

What is global dimming?

What is global dimming?

When you put particles into the air, such as from cars, industry and volcanoes, the particles reflect some of the sun's rays back into space and stop it coming through into the atmosphere. The sun is the key source of warming and energy input into our planet. So actually in real terms when you have a big volcano, despite the fact that it releases an enormous amount of heat, it releases an enormous amount of ash. That correspondingly cools the planet. Most people might think that volcanoes would heat the planet up, but they actually cool it down for quite a long time. A recent piece of research in the journal Nature showed that Krakatoa, which blew up over Indonesia about 100 years ago, still has a legacy living on in the oceans today. Over 100 years later we can still see a cold body of water and lower sea level because of that.

How does the weather affect weaker ocean currents?

How does the weather affect weaker ocean currents?

In terms of the ocean affecting the weather, the ocean has a very strong influence on seasonal weather. If you're talking about needing weather predictions several months ahead, then you do very much need to look at the ocean temperatures. In fact, if we look at this last winter, it's been incredibly dry here in the UK. That's been closely connected to the fact that we've had incredibly warm sea temperatures in the tropical Atlantic. If we look back to the autumn we had lots of hurricane activity including the one in New Orleans, and that was also connected with sea surface temperatures. For European winters, you have one of two situations. You either have the case where you have a very strong jet stream that brings all the storms across the Atlantic to the UK. In those situations you'll typically have warm, wet winters. The other situation is where you have a much weaker jet stream and the storms tend to get deflected up north or down south. In those situations you typically have a cold, dry winter in the UK. Whether or not you're in one or the other situation is largely modulated by the sea surface temperatures are like in the Atlantic Ocean.

What are flames made of?

What are flames made of?

Flames are simply soot particles made when a wick (in the example of a candle) burns. Because these soot particles are so hot, travel upwards and glow, just as a red hot poker might glow. They glow a yellow colour and so create a flame.

What gives us a toothache?

What gives us a toothache?

A toothache is when you have irritation to the nerve supply to a tooth. The most common reason for this is sensitivity to cold, when you have sensitive teeth, but usually it’s because you have a hole in your tooth – a carie. Holes in teeth are caused by bacteria, usually streptococcal bacteria, metabolising sugars in your diet into acids, which then drill holes in teeth. Teeth are made of calcium phosphate, and so can be dissolved by acid.

When the hole becomes big enough, the bacteria can start to change the chemical environment inside the tooth, and you can get abscesses. These are painful because they cause inflammation and swelling, or just because of the change in chemistry.

Another less common, but very serious cause of toothache can be an infection in a sinus. The nerves that supply your teeth run through, for example, the floor of the maxillary air sinus, the sinus behind your cheek. An infected sinus could make you feel that you have a toothache, when there’s nothing wrong with your teeth.

When you put wood on a fire, why does some wood spit and crackle while other wood burns slowly and quietly?

When you put wood on a fire, why does some wood spit and crackle while other wood burns slowly and quietly?

There are a couple of reasons for this. It's usually to do with how dry the wood is. What splits the wood apart is the expansion of pockets of water vaporising as the wood gets very hot. The expansion is like its own mini explosion.

What's the difference between fuel sold in the winter and in the summer?

What's the difference between fuel sold in the winter and in the summer?

Fuel is different between winter and summer because the conditions it is used in are different. The starting conditions are particularly different, as engines have to get going from a much lower temperature. What you can do to winter fuel is add chemicals that make the petrol vaporise at a lower temperature, which facilitates cold starting. Using a better mix makes it easier for your car to start on a very cold day.

What would happen if you lit a match in space?

What would happen if you lit a match in space? Considering there's oxygen in the air on a space station but no up or down, what would be the structure of the flame?

A flame goes upwards because of convection. The hot gas created by the flame rises. As you say, there's no up or down in space so the gas just forms a sphere around where it's burning and you just get a sort of circular flame. But actually stuff doesn't really burn very well in space. This is because the process of the gas going upwards (as happens on Earth) gets rid of the carbon dioxide formed in the burning process and sucks in more oxygen to keep the flame stoked. This keeps everything burning quickly. As there's no upward movement of gas in space, you don't have much oxygen getting into the flame and it's quite a poor flame that is formed. So essentially it chokes itself in its own waste products and just goes out.

Why do cars smell like rotten eggs after a while? Is this down to catalytic converters?

Why do cars smell like rotten eggs after a while? Is this down to catalytic converters?

This is not exactly a myth but is something that's becoming less of an issue nowadays. The reason that that happens is that there is sulphur in fuel and when sulphur burns in oxygen it forms sulphur dioxide. This only really happens in a petrol engine, which can operate under fuel-rich or fuel-lean conditions. In fuel-lean conditions there's quite a lot of oxygen so the sulphur in the fuel gets oxidised to sulphates. This is a real pain because this clogs up the catalyst and builds up on the surface of the monolith. But when you start a car, this is the point when you have fuel-rich conditions. This is going to convert the sulphate that has built up on the catalyst into H2S, which is hydrogen sulphide. That's the kind of eggy smell that you get out. But this is also why we're getting a lot more low-sulphur fuels nowadays and to be honest it's a lot less of a problem than it used to be.

Why do pictures fade in paintings and books? Is it a chemical reaction?

Why do pictures fade in paintings and books? Is it a chemical reaction?

The colours in pictures are made out of chemicals. They tend to be chemicals that interact with light quite well because they have a colour, meaning that they absorb some colours and reflect others. If they are exposed to too much light, especially ultraviolet light from the sun, they break, become damaged and stop being coloured. It depends what dyes you're using. Inorganic dyes that include metals tend to survive a lot better in sunlight than organic ones, but basically the chemicals get damaged and bleached. If the molecule is broken by absorbing lots of UV light, then its absorbency changes. The same thing happens with human hair in summer. You can make the process happen a little bit quicker if you put some lemon juice on. On a similar point, the reason why bleaches work is that dye molecules are sensitive and quite easily damaged. A bleach is something which oxidizes something, and goes round and damages things at random. The things that get damaged first tend to be the colour molecules and so things tend to go white.

Why does your stomach rumble when you are hungry ?

Why does your stomach rumble when you are hungry ?

The rumbling sounds you hear are your stomach gearing up to accept food. Whenever we feel hungry we usually placate our stomachs with some food soon afterwards and so the digestive system prepares itself in advance by releasing digestive juices and increasing the peristalsis of the stomach muscles. When we eat the food dampens the sound of the juices squirting around so the stomach sounds quiet. When we are empty though there is nothing to soak up the sounds and the result can be noisy !

Why can birds sit on a power line and not be electrocuted ?

Why can birds sit on a power line and not be electrocuted ?

The reason that birds can sit unharmed on power lines is that no current flows through them because they are not completing the electrical circuit by sitting on one line only. Rather like water flowing down hill, electricity needs to flow down an electrical hill, otherwise known as a potential difference. So if you connect the plus side of a battery to the minus side current flows because there are lots of positive charges at the plus pole and very few at the negative, so the current flows to try to equal things out. So going back to the bird sitting on a power line, no current flows through the bird because it has the same charge as the wire it is sitting on. If it were to straddle a positive and a negative line, on the other hand, it would certainly be curtains ! Ditto if it put one leg on the ground and another leg on the wire. Under these circumstances there is a big difference between the amount of charge in the wire and the charge on the ground, so electricity would flow through the bird in an attempt to balance things out.

Since skin continuously replaces itself, why do tattoos last a lifetime ?

Since skin continuously replaces itself, why do tattoos last a lifetime ?

The upper layer of the skin, the epidermis, which consists of flattened dried-out dead cells, is replaced continuously throughout life. As cells are worn away from the top layer of skin they are replaced by new cells from below. Tattoos are injected deeper into the skin into a layer called the dermis below where the cells that make the epidermis come from. This means that the dye stays where it is put for life.
Show featuring dermatologist Jane Sterling about the skin and skin diseases

What is a mirage?

What is a mirage?

A mirage is a trick of light seen in hot places like deserts (hence the association with thirsty travellers) and road surfaces. Like the end of a rainbow (another light trick) you can never actually reach a mirage. They form because when air is heated up light rays pass through it more rapidly, causing them to bend, or refract, upwards. They bend upwards because warm air close to the road surface, for instance, allows the light to pass through more rapidly than cooler air higher up, but when the rays reach your eye they are interpreted as coming from the road surface (like a reflection), rather than the sky, and so you see a mirage.

How big is the internet ?

How big is the internet ?

This depends on whether you mean how many pages are there, or how many people are there using the web ? In terms of the number of pages, the search-engine Google claims to currently index over 2 billion. In terms of the size of the online community, current estimates suggest about 544 million people, according to internet demographics source nua.com.

How fast do sperm swim?

How fast do sperm swim?

About 3 mm per minute. Interestingly, scientists have found that mouse sperm are very altruistic and line up nose-to tail to swim along in convoy, thus helping more of them make it further. In humans, results announced by Brazilian scientists at a meeting of the American Society for Reproductive Medicine meeting in San Antonio, reveal that sperm motility can be increased by caffeine. Dr Fabio F. Pasqualotto, a human reproductive medicine specialist at the Conception Center for Human Reproduction, University of Sao Paulo, Brazil, compared semen samples from 232 non-coffee-drinkers, 156 men who drank 1 to 3 cups daily, 198 men who drank 4 to 6 cups daily and 164 heavy drinkers who consumed more than 6 cups per day. He found no differences in the quality of the sperm in all cases but did observe that the sperm from the coffee drinkers appeared to be in more of a hurry, suggesting that a cup of coffee could boost fertility! Meanwhile, another way to speed up sperm is to send it into space. German researcher U. Engelmann measured sperm swimming speeds aboard a European Space Agency mission in 1988 and found that the cells moved faster under microgravity conditions.

What do you mean by 'dust'?

What do you mean by 'dust'?

Well, by dust, we’re talking about small particles, because remember that when things form to start with, they don’t necessarily have to form big things and then be ground down into little things. Small things will attract other small things because they’ll stick together, one way or another. So when we’re talking about dust, we’re talking about amorphous materials that can include big bits, small bits, and bits of gas. So it’s a way of not having to define exactly what that entity is, but saying it’s a mixture of chemical entities which have all of the necessary pre-requisite ingredients to actually form planets and stars.

What is tryptophan? Does eating turkey really make you sleepy?

What is tryptophan? Does eating turkey really make you sleepy?

There's been a question about sleepiness caused by tryptophan in turkey and this is a popular myth in the United States that a feeling of sleepiness arises after the Thanksgiving meal and it's caused by the Thanksgiving turkey having a high content of a substance called tryptophan. Tryptophan is an amino acid, one of the building blocks of protein which means that pretty much all proteins contain some Tryptophan but turkey's not unusual in its tryptophan content. It has about the same amount as chicken or beef. Tryptophan is involved in the desire to sleep after a heavy meal but only indirectly. The root cause of the drowsiness but only indirectly. The root cause is the large carbohydrate intake that usually accompanies a celebratory festive meal. All those roast potatoes, the stuffing, not to mention sugar-rich puddings. They all result in a burst of insulin in the blood stream as the body tries to cope with this influx of sugars. One of the side-effects of this secretion of insulin is that tryptophan gets into the brain more easily and once there part of the tryptophan is transformed into a substance that's called melatonin. Melatonin is a hormone involved in sleep regulation and it can encourage sleep. But really it's the carbohydrate in a heavy meal that triggers drowsiness and tryptophan is just a bit player in the biochemical consequences of over-indulgence in carbohydrates.

How does the Richter Scale work?

How does the Richter Scale work?

The Richter Scale, contrary to popular perception, is actually just derived for California. It's a measurement based on the displacement measured on a seismograph. This measures the displacement of the Earth due to ground motion. It's an empirical measure, and also logarithmic. If you take a magnitude 5 and a magnitude 6 earthquake, the magnitude 6 will be bigger in terms of energy release than a magnitude 5. But a magnitude 7 will be roughly 1000 times bigger than a magnitude 5.

How much water is actually produced by a human on an average day of metabolism?

How much water is actually produced by a human on an average day of metabolism?

About a third of a litre per day is the amount of water that your body makes just through metabolising, just by burning sugar because the equation is glucose: C6H12O6. If you burn that using six molecules of oxygen: plus 6 O2, this goes to 6 molecules of carbon dioxide: six CO2 plus 6 H2O, six water molecules, and that all adds up to about a third of a litre a day which is why you get some of the water that you need from actually your own metabolism.

Why does the body needs salt and what happens if you have low salt levels?

Why does the body needs salt and what happens if you have low salt levels?

The reason the body needs salt is because every single one of our cells contains large amounts of salt and, salt is the generic term for ions, charged particles, and most of the cells in our body in fact, all of the cells in our body are electrical. In other words they pump these ions from one side of their cell membrane which is a lipid or oily substance and therefore an insulator so they pump ions from one side of that membrane to the other and this means there is an electrical potential difference across the membrane of a cell and this means that this gradient this electrical difference can be used by the cell to do other sorts of work. So cells for instance do have channels that sodium can flow in to the cell and it comes down its potential difference in concentration gradient and the result is that it can be used to pull in glucose at the same time. So sugars can get into cells.

So we need salts in our cells - that’s how they regulate their size by bringing water in by osmosis. That’s how they regulate electrical activity. Nerve cells for instance couldn’t carry information without actually having this electrical gradient across the membrane because all that’s happening when a nerve cells fires off an impulse is that you get a sudden flood of sodium in to one patch of a nerve cell. This brings in lots of plus in to that part of the cell and therefore an electrical signal goes whizzing goes down the nerve and gets built up and regenerated as it goes down the nerve and it travels at about 50 to a 100 meters a second so very rapid transmission of information.

So we need salts in our body, we take in salt in our diet, we absorb salts and those salts are also include important things like calcium to make your bone strong but you’re also losing salts all the time when you go to the toilet for example you lose calcium, you lose phosphates. This is both in urine and faeces so you have to continuously top up the number of salts that you have in your body because you have obligate or insensible losses.

The body is very good at scavenging salt from what you eat and what you drink so it’s very rare for people to get too lower levels of salt in the body based on diet alone. Usually there’s something pathological going on. Sometimes what happens is that people have a problem called syndrome of inappropriate ADH. This is anti-diuretic hormone and the body saves too much water so it scavenges back water and as a result your blood can become too dilute and you have very low sodium levels and this can cause problems with your brain swelling. It can also cause the accumulation of water elsewhere around the body and it can cause heart failure so a bad thing to have. But that can cause low salt levels that can make people feel dizzy.

Does laughing gas really make you laugh?

Does laughing gas really make you laugh?

Yes, it kind of does. Laughing gas is nitrous oxide, and it acts as an anaesthetic-type agent. It makes your brain feel a bit woozy in the same way that alcohol does. As a result, if you take some laughing gas, you fell a little bit drunk and a little bit cheerful. If you have enough of it, you start to feel a little bit sleepy, but it's very good at pain killing. If you're having an operation, it's sometimes used with other anaesthetics to kill pain and make you more comfortable. There is a sub-set of people in the population that have a particular form of a gene that is involved in making new blood cells. If they have this sub-set and have laughing gas, then it can affect their bone marrow in the long term. It can make your bone marrow work less well. Luckily, it's only temporary, but I don't think that I'll be inhaling lots of laughing gas.

What is the fifth taste you can sense on your tongue?

What is the fifth taste you can sense on your tongue?

The fifth taste is umami. This has been known for a very long time in the East, and is called umami because the Japanese recognise it. It's only in the last 20 years that it's really been recognised in the West as well. Umami is the sense that is triggered by monosodium glutamate, which I'm sure you know is in soy sauce and food from Chinese restaurants. But most people don't realise what it really is. It's actually very common and is found in tomato puree and it's in parmesan cheese.

Can you use spectroscopy to spot whether ID cards are real, or faked on a home printer?

Can you use spectroscopy to spot whether ID cards are real, or faked on a home printer?

It is very difficult to fake identity cards properly. Using bank notes as an example, an immense number of security measures have been put into them. Many of these measures are very hard and expensive to fake. One security feature on bank notes is the use of phosphors that give off different colours under light. Therefore, despite concerns about ID cards, they shouldn't be easy to forge.

Is it dangerous to live 500 metres away from a mobile phone mast?

Is it dangerous to live 500 metres away from a mobile phone mast?

It's far less dangerous than using the phone yourself. No one's actually found a dangerous relationship with using a phone. When you use a phone, that transmitter is a couple of centimetres away from your head, and the strength of the signal goes down with the distance squared. So it's going to be thousands and thousands of times weaker than your mobile phone right next to your head.

To explore the science of this - if you look at the energy of a microwave, and the reason we have these things in our kitchen and cook with them and we are happy to put a microwave source or a mobile phone to the side of our heads, is because the energy in the wave of a microwave is not sufficient to break chemical bonds in the same way that an x-ray or a gamma ray, or more intense forms can. And therefore they're viewed as non-ionising forms of radioation, and are viewed to be safe. That said, there's no evidence that if you do expose your nervous system to these things that they won't have a temperature effect; because we think that they might warm your head up a little bit if you're exposed to a phone. But of course the mast is much further away than a phone is. But also, exposing tissue to microwaves for long periods of time may or may not have some sort of growth related effect.

Certainly in terms of cancer there isn't enough energy in phone radiation to damage DNA which is the ultimate cause of cancer. Virtually all the studies that have been done have not found a significant link between mobile phone use and cancer. The one thing we don't have is really long term data and that's hopefully coming in in the next couple of years. But the studies certainly haven't found an effect in terms of cancer.

How far is the nearest galaxy?

How far is the nearest galaxy?

The nearest galaxy to our galaxy, the Milky Way, is called Andromeda. It's about 2 million light years away, and we think it looks very similar to our own galaxy. It's difficult to know what our own galaxy looks like because we're in it, but calculations show that it's a flat spiral disc shape. For a long time, people thought that our galaxy was the only galaxy, and that any smudges they saw in the sky were nebulae, which are clouds of gas that form new stars. It was only after some more looking and calculations that people realised that these smudges were too far away to be in our own galaxy. Even Einstein fell foul of misconceptions of that sort. When he was developing his theory of relativity, he had to put in a term that made the universe nice and stable. He thought it consisted of these fixed stars.

How do scientists measure the life of the sun?

How do scientists measure the life of the sun?

We can't actually observe any single star evolving because the time scales involved are far too long. Our sun is sort of middle aged at the moment, and is about 5 billion years old. It should be kicking around for another 5 billion years or so. The way that people understand stars is really by modelling their structure and then observing lots of examples of different stars in different stages of their evolution and seeing if the collection of observations you make fits the theory. We believe that we understand the structure of these stars and so it's really a theoretical construct. We have a model for these stars, it matches all the stars that we see. When we look at the sun, we know what kind of star it is and its properties, and we can say that it's about 5 billion years old.

Was the Star of Bethlehem a real astronomical event?

Was the Star of Bethlehem a real astronomical event?

There have been quite a lot of people who've looked into this sort of thing to see whether it was actually a real event. In fact, my lecturers when I was back at university wrote a paper on that exact same thing. He looked at the theory that if you get Jupiter, Saturn, Mars and as many planets as possible in the same spot in the sky, can you get a star bright enough to look like the Star of Bethlehem? He found that that probably wasn't the case, as it wouldn't have been bright enough. However, there are some other possibilities. These include comets, asteroids and possibly supernovae as well. When stars explode, they can give out as much light as an entire galaxy, but they don't last for a very long time. This could be an explanation.

Why as we get older do we get brown pigmented spots on our hands, and when pregnant ?

Why as we get older do we get brown pigmented spots on our hands, and when pregnant ?

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.

What would happen if you lit a match in space?

What would happen if you lit a match in space?

A flame goes upwards because of convection. The hot gas created by the flame rises. As you say, there's no up or down in space so the gas just forms a sphere around where it's burning and you just get a sort of circular flame. But actually stuff doesn't really burn very well in space. This is because the process of the gas going upwards (as happens on Earth) gets rid of the carbon dioxide formed in the burning process and sucks in more oxygen to keep the flame stoked. This keeps everything burning quickly. As there's no upward movement of gas in space, you don't have much oxygen getting into the flame and it's quite a poor flame that is formed. So essentially it chokes itself in its own waste products and just goes out

Why do pictures fade in paintings and books? Is it a chemical reaction?

Why do pictures fade in paintings and books? Is it a chemical reaction?

The colours in pictures are made out of chemicals. They tend to be chemicals that interact with light quite well because they have a colour, meaning that they absorb some colours and reflect others. If they are exposed to too much light, especially ultraviolet light from the sun, they break, become damaged and stop being coloured. It depends what dyes you're using. Inorganic dyes that include metals tend to survive a lot better in sunlight than organic ones, but basically the chemicals get damaged and bleached. If the molecule is broken by absorbing lots of UV light, then its absorbency changes. The same thing happens with human hair in summer. You can make the process happen a little bit quicker if you put some lemon juice on. On a similar point, the reason why bleaches work is that dye molecules are sensitive and quite easily damaged. A bleach is something which oxidises something, and goes round and damages things at random. The things that get damaged first tend to be the colour molecules and so things tend to go white.

Why is it that bubbles are always round?

Why is it that bubbles are always round?

You may have heard of surface tension this is due to water molecules pulling together and trying to minimize the number of them on the surface and not surrounded by other water molecules, it can hold up pond skaters and float pins etc. Now the water in the soap film is trying to minimize it's area too, and as there is a fixed amount of air trapped within the bubble and the shape with the least surface area for its volume is a sphere, bubbles are spherical.

Why is the sun so hot?

Why is the sun so hot?

The sun is so hot because the sun is a giant nuclear reactor in the sky. It's mixing on hydrogen with another hydrogen to make another light gas called helium. You can find helium in the funky balloons that float. When you mix the two hydrogens together, you get a lot of heat energy, and so the sun on its surface is at least six thousand degrees centigrade. That's what keeps us warm.

Does the nicotine vaccine stop the cravings to smoke?

Does the nicotine vaccine stop the cravings to smoke?

Probably not. The mechanism works by stopping the effects, and so might actually increase the cravings. The vaccine is probably best used in combination with something that helps with the withdrawal symptoms. However, by stopping the effects, it also helps to break the cycle of reinforcement. Eventually this may lead to people stopping people smoking because it does nothing to help the cravings.

Why don't I ever dream?

Why don't I ever dream?

Surveys have shown that about 6% of the population say that they absolutely never dream. There doesn't seem to that much difference between them and the rest of the population, but what has also been done is take some of these people and wake them up in sleep lab when they're in REM sleep. Every 90 minutes or so during your sleep the majority of people go into REM sleep, so you put these people in the lab, wire them up, and what happens is that you can wake people up during these periods of sleep when they ought to be dreaming. With most people you've got about an 80% chance of a dream being reported if you wake them up like this. Now if you're a non-reporter of dreams, that is one of the 6%, what's been found is that 0.6% of these absolutely never report a dream even if you wake them up during REM sleep, so in your case Betty, it is quite possible that you are having dreams and you just don't remember them.

What ingredients go into antibiotics, and how do they work ?

What ingredients go into antibiotics, and how do they work ?

Tablets taken by mouth contain a lot of the actual antibiotic. They also contain lots of other substances which enable the manufacturer to produce a tablet that can be kept in packets and are easy to swallow. For example, the smooth outer coatings of some tablets are often made out of vegetable products. Once the tablet is in your stomach, the active bits distribute around the body through the bloodstream, reach the site(s) of infection, and kill the offending bacteria. There are three different ways antibiotics kill bacteria. Some stop bacteria from growing by stopping their protein production; others stop them from making chromosomes; and the third type stop bacteria from making cell walls. Without a proper cell wall, the bacteria explode and die.

Is it safe to swallow chewing gum ?

Is it safe to swallow chewing gum ?

Chewing gum used to be from a rubber plant, but is now artificial. It sticks to the road because it contains long oily polymer chains which are chemically similar to some of the constituents of the road surface. It's very hard wearing stuff and doesn't get digested when you swallow it. It can cling onto the sides of your intestines and distort the gut, are occasionally trigger a dangerous disorder called intussusception where the gut telescopes inside itself, although this is rare in adults. It would be better for the environment if people could swallow it. Until then, it would be good to develop a family of chewing gum-consuming bacteria that could eat it off the pavement !