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!