News
A Harvard-based research team have successfully produced a miniature movie of the generation of platelets, the key elements that allow blood to clot.
Tobias Junt and his co-workers used a fluorescent dye to label up platelet-producing cells in the bone-marrow of mice and then watched in real time a...
Scientists have worked out why it is so difficult to mix ingredients into a cake. Emmanuelle Gouillart and a team from CEA Saclay near Paris have been studying how things mix together in a bowl. He added black dye to a clear syrup and mixed it automatically with a rod and studied the results.
He fo...
Researchers in Tbilisi, Georgia, have uncovered the oldest human remains ever found outside of Africa, a species of Homo which might even have returned to Africa to spawn modern man.
The Georgian National Museum's David Lordkipanidze and his colleagues, working at a site in Dmanisi, have uncovered...
Scientists in Japan have discovered that thunderstorms act as huge particle accelerators. Harafumi Tsuchita of Japan's RIKEN research institute and collegues installed a directional gamma ray detector at a nuclear power plant. Recently this picked up a 40 second burst of high energy gamma rays. Thes...
Scientists have solved a long-running conundrum connecting high levels of air pollution with an increased risk of heart attacks and strokes.
Writing in the Journal of Clinical Investigation, Gokhan Mutlu and colleagues from Northwestern University in Illinois found that mice exposed to airbourne p...
Kitchen Science
Make yourself an electromagnet powered by a small battery and find out some of the mysteries of magnetism.
QotW
This question was answered by Professor Ron Douglas
It is true that amphibious animals, such as ducks, seals and turtles, can see well in both air and water. For humans, however, the world becomes all blurred as soon as we stick our heads under the water. This is because in animals such as ourselves that live in air, two parts of the eye focus light; The lens within the eye and the cornea, which is a transparent window at the front. Of these, in humans, the cornea does about three quarters of the focussing because there is a large difference in refractive index between the air and the cornea. The lens in our eyes is relatively flat, and is mainly responsible for fine focussing of the image, as we look at things at different distances, by slightly changing it's shape, becoming fatter as we look at closer objects. Our world becomes blurred underwater because water and the cornea have very similar refractive indices, so the cornea no longer focuses light. We therefore become very long sighted under water, as our lens is not optically strong enough to focus the light.
What something like a duck does, therefore, is when it is in air, it has the same basic eyes that we do; with a cornea that focusses most of the light, and a flattish lens. When it goes under water, however, when the cornea no longer focusses light, it pushes it's soft lens against a quite hard iris, and part of the lens bulges through the pupil, forming a sort of nipple on the front surface of the lens. This acts as a very powerful lens, and allows the animal to see underwater, when the cornea isn't working as an optical surface. This allows diving birds, for example, to both successfully hunt for fish underwater, and to catch the bread that you throw for them on the surface.
Interestingly, there is a group of humans that seem to see quite well underwater; these are the Moken, who are wondering sea gypsies inhabiting the coast off Thailand and Malaysia. They make a living by diving in the sea, often without goggles to harvest things like abalone. It turns out that when you compare their ability to see detail underwater to a similar group of Europeans, the Moken do much better. Any camera enthusiast will tell you that if you want to see a large range of distances in focus, in other words, to have a large depth of field, you close down the aperture of the camera. So when the Moken go underwater what they have learned to do is to close down their pupil, giving them a large depth of field, and compensating for the long sightedness induced by losing the cornea as an optical surface under water. Interestingly, given time, European children can learn to do this as well.
Diana finds out how sea birds can see both underwater and in the air, and we learn how you can train yourself to do so too!
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Interviews
Once a judge on Robot Wars, Professor Noel Sharkey told us about the part robots have to play in real wars...
What do we need robots for in genetics? Just what difference do they make? We sent Meera to the Wellcome Trust Sanger Institute to find out...
The Semantic Robot Vision Challenge was set up to find robots which could locate an object in real space, after only seeing it in cyberspace. We spoke to Professor Jim Little and Dr Per-Erik Forssen about their winning robot, Curious George
Professor Nigel Shadbolt is the President of the British Computer Society - he gave a talk at the BA festival of science asking examining artificial intelligence titled 'Free thinking Machines or Murderous intellects'. Scary stuff indeed...
Questions
Do you get wetter if you run or walk through the rain?
The simplest answer is it depends on the rain, but if we assume that the rain is falling constantly and is falling straight down and you don't change shape as you walk, you will get wetter if you walk.
This is because the rain can hit you in two ways, it can hit all your horizontal surfaces by just falling on them, or it can hit your front by you walking into it. If there is no wind, the amount of rain that hits you on the front is just dependent on the amount of space you walk though, so how far you walk. If we assume that this is a constant the only thing that will change is the amount of rain that actually falls on your horizontal surfaces which is just dependent on how long you are in the rain for, so running probably does make sense.
Of course in the real world everything is a bit more complex, if there is a wind moving with you it may pay to move a little slower as you can get to where you are going without walking though any rain, just have it fall on your head by walking at the same speed as the wind.
Also if you are in a very short thunder shower that will finish quickly it may pay to move slowly during the shower as you won't run into any rain while it is at it's heaviest.
Although I still think in general running is your best strategy, unless you trip up and twist your ankle...
Why do metal pots spark in the microwave?
I guess the cast iron pot had a cast iron lid as well. Microwaves cause electric currents to flow through metal, so you would get a current flowing through both the pot and the lid. If the pot and the lid were insulated from each other, and there was enough voltage, you would get a spark as the current jumped between the pot and the lid. This would explain the flash, and it may have damaged the enamel on the surface. The spark is incredibly hot, and so this could have vapourized some of the enamel, which may be the cause of the smell.
It's unlikely that cookware manufacturers use anything too toxic in the enamel, as you may scrub bits loose and they could wind up in the food. So although there may have been some enamel in the food, it should be relatively safe and in such tiny quantities that the food would not have been dangerous.
How do mouse pads work?
I think that trackpads on laptops work by having two sets of wires, one running horizontally and one vertically, and they they look at the capacitance between the two of them - so if you make a voltage with one of them, how much is that voltage picked up by the other one. If you put your finger near it, this changes quite considerably, in fact if you put anything conductive near it it will change. The problem is that if you've got thick, dry, calloused skin on the tip of your finger, this acts as an insulator and stops this effect from happening. The ipod click wheel is either more sensitive, or possibly pressure sensitive.
Can old people not use mousepads?
As you age, your skin tends to get thinner, so it's unlikely to be the same effect as with the guitar string callouses. In fact, thinner skin should be picked up more easily by the trackpad system. Obviously, it depend on your life history - maybe your mature friend is a thrash metal guitarist?
The naked scientists invention are very helpful in terms of household works. ...
- HarryZhen1990 - 30th Apr 09
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