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How Stuff Works has an article detailing the Linux and GNU relationship.

Try going near an MRI machine with change in your pocket. I made that mistake once, and it was tugging hard at the coins from across the room. >1 tesla magnetic fields need to be treated with respect - people can get seriously hurt if anything metallic gets brought into the room - they can get ripped out of your hand or pocket and will fly straight down the central bore where the patient is. I've heard stories of people being killed when someone walked into an MRI room with a pair of scissors in their pocket.

In reality, the origins of Halloween is much more complex that that. Check out this article to find out more. In particular:

In medieval times, one popular All Souls' Day practice was to make "soul cakes," simple bread desserts with a currant topping. In a custom called "souling," children would go door-to-door begging for the cakes, much like modern trick-or-treaters.

It's funny that the whole Halloweeen thing may be an early example of "embrace and extend". The early church rescheduled All Saint's Day to coincide with an older pagan holiday, then told people to go ahead and have fun on the new enhanced hybrid holiday.

In the US, halloween is second only to xmas for total dollars spent, and comes in third for total number of parties (after new years and the super bowl). Also for a more detailed description of the integration in american culture, see here

It is a phase-change technology -- instead of "burning" a dye layer as in CD-R, CD-RW melts a layer of metalic material.

If a spot of this material is heated above its melting point, and then allowed to cool very quickly, i.e. turn the laser on full and then turn it completely off, it solidifies in a kind of cloudy manner, refered to as the amorphous state. This happens because while melted, the various molecules float around in a random orientation. When cooled quickly, they are "frozen" in this random state. This makes that spot cloudy enough so that light isn't reflected clearly by the reflective layer below.

On the other hand, if you heat that same spot again to its melting point (full-power laser) but then let it cool slowly using a lower-power laser to keep it slightly heated, the moluecules have time to crystalize, lining up with each other to form a nice, clear crystal. When the laser finally turns all the way off, that spot is now frozen in this transparent state, no longer cloudy, so that light passes through and reflects brightly off the mirrored surface below.

The downsides are: The contrast between the cloudy==unreflective and clear==reflective states is not as great as a pressed CD or opaque-dye CD-R, so it takes a more sensitive reader. I believe that CD-RW capable readers specifically recognize that it's a CD-RW, and use different thresholds of brightness for determining 1s and 0s. That's why older players aren't compatible.

The other one is that this melting/solidifying process gradually damages the crystaline layer. After enough "meltings", it wears out and gets permanently cloudy.

HowStuffWorks.com has a nice article about CD-R and RW technology.

- Peter

I would have like to see Tom measuring the performance of these PSU's with a UPS attached upstream. Surely the quality of the mains voltage (lack of spikes, brownouts etc) would have a measurable effect on the resulting performance of the PSU... Anyone care to comment?

Most of the questions regarding how the show really works are answered on HowStuffWorks.com.

Most of the questions regarding how the show really works are answered on HowStuffWorks.com.

The vacuum of space prevents the sink losing heat through conduction, it does not prevent heat loss through radiation.

The thermos works to minimise all main energy transfers, the vaccum deals with conduction, the silvered surfaces with radiation etc.
For a good desc. of how a Thermos Works go here.

this happens at much lower frequencies already - just look at the spec sheet of your microwave oven: it operates at 2500MHz (or 2.5GHz). this frequency is absorbed by water molecules which is why your food heats up when you put it into the microwave oven. a radio link in the neighbourhood of this frequency might work in a very dry environment but fog or rain would render it completely useless. the trick is finding a frequency that is not in resonance with any of the vibrational/rotational modes of any of the gases that make up the atmosphere.

They've been using turbines in the M1 tanks for years. If you can handle it in a tank, you can definitely handle it in a locomotive. The main problem in the M1 is the thirst, but it seems like modern turbine engines (at least those of the size a locomotive needs) don't have that handicap.

The M1 tank has a turbine engine also. Generally these types of engines are used in applications where a high power-to-weight ratio is required and cost is not the issue.

The birthday paradox is suprising. It is a good example of how bad humans are at calculating probabilities.

Ask everybody in the workshop to shout out their birthday (day, not year) one at a time, and ask people to raise their hand if they have the same birthday. In a class of 30, the chance of a coincidence is 70% example, explaination.

There is a 50% chance that two people out of a group of 23 will share a birthday.

If noone shares a birthday you may look silly though :-)

I doubt it. They are alot harder than cars to operate. NOT easier. IIRC, there are even videos on how to operate them on howstuffworks.com

This top fuel link should explain all your questions and more.

Please do note that I am not talking about nitroglycerin. That's an extremly unstable high explosive. That would be a death wish as it's sensitive to shock, vibration and heat which is exactly what you're going to see on race cars. What I'm talking about is nitromethane which is often simply referred to as nitro. Even still, nitromethane is highly volatile which is why they "cut" by 10%. One laste note, this is distinct "stuff" and should not be confused with NO2 either, even though NO2 does have racing applications as well.

It wouldn't be carbon dating. Carbon 14 has a half life of about 5700 years, so after ~6000 years, it's got about 1/1000th of what was originally there (which is rather low to begin with). After that, I'm guessing that there's just too little to get reliable statistics from (perhaps noise from other decay sequences??).
Besides the problem of the (relatively) short half-life of Carbon14, the fossilization process leaches most of the carbon out of the body anyways-- so there is (almost) no carbon to date. Even if it didn't 1/2^(77million/5700) => 1/(2e4066). In other words, if you started with a chunk of carbon14 the size of Jupiter, you'd be lucky to find 2 atoms of carbon14 after 60million years of radioactive decay)

There's a nice intro to carbon dating at howstuffworks.com, with even more data at c14dating.com. They mention that you can use carbon-14 style radioisotape dating with isotopes that have a longer halflife than carbon 14. These are the methods are what are used to date older rocks.

The reason why carbon 14 isn't useful for recent items is the nuclear age. In the early years of the nuclear age, the US and later 'nuclear club' members did atmospheric nuke tests that completely messed up (read: randomized) the isotope ratios for everything that's died since the late '40s. Cherbonyl didn't help much, either. Anything earlier than that (and recent enough that there's a statistically valid percentage of C14 left in the body) is a good candidate for Carbon dating.

Prior to nuclear fallout, the primary source of Carbon14 was atmospheric Nitrogen being bombarded by cosmic rays.

Initial financing for the project, amounting to $140,000, came from the Scottish Higher Education Funding Council.

$24,917 * 7 = ~175k

Which, ironically, is about the cost of the tuition for the 7 years of med school for only one student. If they get two students, they will already be doubling their money ;-)

HowTo become a doctor

http://www.howstuffworks.com/news-item107.htm

For example, the base tower would have to be 31 miles high, according to this article. Which is 90 times higher than the current tallest structure on earth, the CN Tower in Toronto, Canada is only 1/3 of a mile (about 170 stories) high.

There is also talk about using carbon nanotubes to make up the cable. The pricetag, 40 billion dollars (see 2nd link).

I'm sure a lot of the people here already know how quantum computers work, or will work, o whatever. ;)

But here is a great article for those who havn't read anything yet.

I had lasik eye surgery performed by Dr Noel Alpins at the Melbourne NewVision Clinic last January. Before the operation my prescription was -7.5 and -3.5 in my left and right eyes respectively with astigmatism in both. I now have 20/16 vision, which is better than 20/20 - I can read the lowest line on the optician's chart without straining. I can highly recommend this clinic.

The surgery takes about a minute and a half from start to finish, for both eyes. Your eye cannot feel anything during the procedure, all you have to be able to do is look at a little orange dot for about forty five seconds with each eye. After surgery, they tape plastic shields, a bit like large sun-glasses, over your eyes to prevent you from rubbing them. When you come back the next day they remove the shields and give you an eye test. You then have to take eye drops for the next fortnight or so.

Improvement in vision is immediate. The only artefact is that, at first, in situations of high contrast, such as bright lights at night or watching television in a dark room, you will observe some mild haloing (the effect is much less annoying than, say, a fingerprint smudge on your glasses.) The effect diminishes to nothing over the next four to eight weeks.

Risks: I was naturally very concerned about any risk to my eyesight. My prescription was sufficiently strong that I didn't want anything to make it worse. Dr Alpins explained to me that by having worn contact lenses for more than eighteen months (about a decade or so, in fact) I had already exposed my eyes to greater risk than would be the case for undergoing LASIK. The clinic aims to get at least 20/20 vision in each patient; they consider it a failure when somebody has to return three months later for minor corrective work to reach 20/20 (this happens in about 3% of cases, if I recall correctly.)

Finally, you can check Dr Alpins' publication list on the web and verify his claims to have invented a number of improvements to the technique over the last fifteen years that are now in use worldwide.

Going for surgery has had a marvellous effect on my life. It pays for itself every day by removing the hassle of glasses and contacts. It's especially good when you go swimming or clubbing or play sport and so forth. Magic stuff.

I have seen many posts here that disregard the serious technical limitation imposed by classical computing by just saying 'Engineers will solve it, they always do'. That is like saying that faster than light travel is only an engineering problem. New computing paradigms are needed. Most predictions says that most of us will witness Moore's Law fail due to quantum mechanical and thermodynamical reasons. Instead of blindly pretending that the engineers will magically solve the problem it would be more proactive to start learning more about the prospects the next generation of technologies. We need to think, not to hope for something magical to happen.

Huh? You're trying to tell me that the earth only has a mass of 122880 kilograms(6144*20)? While simple logic can tell you that's untrue, this page can confirm it, as can this one.

Yeah, funny and all, but this is in fact really dangerous. The magnetic field produced in Magnetic Resonance Imaging machines are only about 1/500 the strength of this magnet and the warning signs around these machines are very real and important: http://www.howstuffworks.com/question698.htm

For example a 2.1MP camera only produces pictures @ 1600x1200 which contains 1,920,000 pixels. This is a ratio of about 10:11. This means that the 13.8MP camera gives pictures with approx. 12.5 Mpixels You do the math of figuring out the res.

[disclaimer]I am not into digital cameras, and all I know, I learned from this article, so don't fry me OK!!![/disclaimer]

I did a lesson at college on Stereolithography about 10 years ago. The process of curing two-part epoxy resin with the heat generated with laser lights. It was very accurate back then; more than adequate for producing A1 models and patterns.

I'm wondering how accurate it is now or how accurate it could become.

Solar cells unfortunately need the UV light to fuction properly

That's not true. The spectra of radiation that can be converted to energy by a solar cell is directly related to the bandgap energy of the material the cell is made from, and there is an optimum (for efficiency) bandgap that corresponds to the visible spectrum of light. Most solar cells do not convert significant energy in the UV area of the spectrum

That's part of the reason that solar cells are quoted as being only 10-15% efficient. That's of the total solar spectrum. Most are better than 50% efficient within the relatively narrow part of the spectrum that they are tuned for.

For a little more information, see the ever popular How Stuff Works.

How Caffeine works...
How Beer works...
How Pot works...

Google is great for finding out important, health-related information. :-)

This is exactly what the switch-mode power supply in your PC does. See How Stuff Works.

--zawada

A relative of mine installed a reverse osmosis filter in his house. This filters out everything including chlorine: the water is so clean that it squeaks. The next time he refiilled his aquarium, the fish started dying. He had to add a little chlorine and flourine to their water to revive them. You have substantial amounts of chlorine incorporated into your own body.

It may also interest you to know that even oxygen can be poisonous. (-:

Perhaps you should have qualified yourself with `large concentrations of chlorine...' - even if only to reduce `period pain'.

Here is a pretty cool article on the future possbility of a space elevator

You can also read about Project Orion in John McPhee's book The Curve of Binding Energy . This book is mostly a long conversation between McPhee and Ted Taylor, (more) a physicist and ex- nuclear weopons engineer. In the early 70's Taylor becomes worried about how easy it is to build a fission bomb. Taylor and McPhee drive around and survey the security of nuclear materials while Taylor talks bomb theory and practice. The title comes from the curve on this page.

[1] Image Quality [2] Bandwidth [3] Frames per Second (speed)

The other posters are correct pointing out the limitations inherent in high speed digital photography because today there are certainly a few that need to be over come before the transition can be made. With the speed of memory technology we are able to store a limited amount of image data on camera and allow for this to be transfered after capture has taken place. Already we see the beginings of high speed digitals that can be run indefinately with a loss in image quality. When you take out color completely and drop frame resolution than there is alot you can make a digital camera do. The reason that you have a loss in image quality as the speed increases is because the CCD / CMOS / CIF [Common Interchange Format] can't read out the image data fast enough between frames. Current implementations make one chip act as two whereby only one half of the imager captures at a time while the other half is busy transferring its data.

Readers should keep in mind that CMOS is used primarly in video because you can change the analog image data over to a digital value much quicker since there are more A/D converters and they are located closer to each pixel. If you are having trouble with the difference between the two How Stuff Works has a decent explaination. If you are looking for a vendor or want to read some data sheets to get a better idea of the differences between High Speed and High Resolution than I suggest visiting Redlake , one of the many vendors that have products on the market. If you want a better explaination of the target Image Quality that digital is trying to achieve than head over to this guy's site. I guess I will make this my paragraph of website plugs. I couldn't resist linking to an article written by a Professor of the program that I graduated from. It is about capturing a picture of a bullet hitting an object using a conventional megapixel imager.

I am glad that /. finially decided to run an article on this topic :) although it is plain to see that some of you are confused about what this technology is used for. Also I found it quite humorus that the one guy quoted image size of what he assumed the image sensor as 1024x768 which is the most commonly used screen resolution but probably has never been a image sensor size. Here is a good reminder from micron concerning the differences in resolutions. Most image sensors that are developed are of the same size in both dimensions. Not all but most.

Bandwidth isn't a problem. Another misconception that I hope to alievate. With fiber you are not limited by the amount of data that you can transfer through the cable, but by how you store the data once it is transferred. Now of course changing the data from light into electrical would cause a slow down. The reverse is also true. What someone should find out is the limitations of these converters. The only way we would see an advantage of using fiber was if we could finish developing new methods to store the data. I have read scientific columns on 3D optical storage techniques that might be applicable in the future. I think I got a bit off the track let me try and get back on.

The reason Bandwidth isn't a problem is because we don't have the capability to produce digital images at the same rate as with film technology. While it would be nice to have a 1024 x 1024 sensor running at 12K - 40K fps, it is not something that we can do currently.

So the question is what do you want to do with the high speed camera? How much important is Image Quality? How much do you want to spend on capturing the image data? See when it comes down to it, it all depends on the situation.

I am not quite sure why we are talking about high speed digital cameras in the first place. Maybe the person who wrote the article didn't research the equipment that this guy was using. I found his website and it says he is using film. Oh nevermind I reread it and he posed the question about why not use digital. I sure hope that I have answered that question!

Someone should brave the Japanese site linked off of the itworld site and find out the resolution of the 1 million fps Japanese camera. I bet it isn't very much.

How does an optical mouse work

I doubt this could be done (at least with any kind of reliability) at the driver level. It definately could be done with a little creative rewiring, but I would not be the right person to ask how to actually accomplish this.

I'm glad someone brought this up... Blue Linx Inc. has been working on this for quite some time now. The question is whether it will be adopted by the industry or not (be sure to read the FAQ on Blue Linx's site). There's also another article mentioning Quiet-Zones here.

I had tried posting this before, but I crashed and didn't feel like typing out all I said... since this thread has died down a lot, I'll be more likely to be herd now by the inquirer... Check this out for some mighty insightful reading. Might change your mind about buying this so called "rare" gem... Check it out here

But a totally viable alternative to Diamond is Moissanite. Better than Diamond in almost every way (except hardness, and even there it's pretty damn close). Check out: How Stuff Works or the manufacturer.

Diamonds are not time honored tradition!! It's all a DeBeer's ploy. Don't believe me, this article talks about it and has links to people like the Washington Post. DeBeer's created the diamond market and created the "tradition." They've received advertising honors for this feat!

http://www.howstuffworks.com/diamond3.htm

I'm surprised I haven't seen this one mentioned yet.

Moissanite

Synthetic gemstone made of silicon carbide. Similar to a diamond in toughness and beauty, so much so that many trained jewelers can't tell the difference. Also costs about 1/10 as much.

Rumors say that some jewelry stores will literally throw you out if you ask about Moissanite. DeBeers sure as hell doesn't sell it, but a quick Google search turns up many retailers who do.

at the mean time, please realize that diamonds are not all that precious (material-wise), and it's under heavy monopolic powers (deBeers). however, platinum IS, so get a good platinum band and engrave something on there.

here is a good link on diamonds and the such.

p.s. artificial diamonds are making good progress. it (crystal structure) is getting too perfect until they exhibit phosphorescence. which is how they distinguish artificial diamond now. ha! (the most perfect diamonds are actually worthless. isn't that amazing?)

anyway. ask her if a dual G4+dual CinemaHD would cut it engagement-wise =)

While I agree it should be fair use to backup one's VHS tapes to DVD, you're way off on Macrovision. It is very much in the tape-encoding, specifically so they wouldn't have to force manufacturers to adopt their technology. For a complete explanation of how it works, check out here.

Nanotechnology Here is a Marshall Brains explanation for those who don't know.

LOL that's not the first watch ever! Mechanical watches were around centuries earlier.

Ever heard of self-winding watches? Then learn How does a Self-Winding Watch Work?

Find a good short FAQ about automatic watches Here

The first hand watch was invented in the 1741. Then self-winding watches came about when Rolex invented the mechanism in 1931. On howstuffworks.com there might be an image of a transparent backside of an "automatic" or self-winding watch showing the mechanism. It's basically a half of a disk at the bottom of the watch that slides back and forth whenever the wearer does anything to move the watch (walk, write, etc.) This keeps them recharged for as much as 48 hours when you stop wearing them!

Apparently self-winding watches are coming back into style because they're so sweet and lose their accuracy at a rate of only a couple of seconds each month.

Sorry to bore you, but I did this research a few weeks earlier because I was interested in getting a watch of this type. :)
(No Signature file found.)

In no particular order:

Wi-Fi - IEEE 802.11b compliant products

IEEE - Institute of Electrical and Electronics Engineers

EFF - Electronic Frontier Foundation, an organization dedicated to preserving online rights

NAT - Network Address Translation, typically used to provide Internet address for a local area network while using only one external IP address

ISP - Internet Service Provider, an organization who provides access to the Internet

BTW, cars with either manual OR automatic transmissions DO have flywheels, but they're relatively lightweight and they're main purpose is to transfer energy, not store it (although it can help to maintain speed on uphills, but you loose acceleration due to more mass you have to start rotating).

Here's a couple links showing the flywheels. Go here or here

While we're on the topic of regenerative braking, here's a solution from Ford using HPA (Hydraulic Power Assist) to help trucks accelerate.
Go here Or Here

BTW, cars with either manual OR automatic transmissions DO have flywheels, but they're relatively lightweight and they're main purpose is to transfer energy, not store it (although it can help to maintain speed on uphills, but you loose acceleration due to more mass you have to start rotating).

Here's a couple links showing the flywheels. Go here or here

While we're on the topic of regenerative braking, here's a solution from Ford using HPA (Hydraulic Power Assist) to help trucks accelerate.
Go here Or Here

Well, I can't speak for hard disk drives, but I can maybe draw an analogy.

Wheel bearings - on cars, trucks, bicycles, whatever - use ball bearings. They're a set of caged balls, and one surface literally rolls over the other on a cushion of tiny little balls or cylindrical rollers. Here's an animated GIF and some other neat stuff. The problem is that, whatever the lubrication, eventually the balls and their races will wear, which increases the clearance between the two surfaces and causes looseness ("play") within the bearings. In wheel bearings, this translates into a shimmy in the wheel and weird tire wear. In a hard disk drive, this would result in a shimmy to the platters, causing less precision in data reading and writing as the platters vibrate nanometers back and forth under the heads. As the drives get to higher and higher capacities with the same physical disk size, the tracks being used must be getting smaller, and therefore this error becomes more crucial. Also, notice that hard drives which have been running for a long time tend to get noisy... Never mind that bits of metal being worn out of bearings have to be contained somehow so that the platters and heads don't get damaged.

Liquid bearings are used in all modern car engines. Oil is pumped from the oil pan into a very tiny space between a relatively soft bearing shell and a very smooth and hard crankshaft or camshaft journal. As the shaft spins, the oil is distributed thoughout the bearing surface and eventually leaks out the sides where it drains back to the pan to be pumped through the system again. Here's a picture of the main bearings of a Ford V8. You can see the little holes where oil is pumped into them. While the engine is running, theoretically, the shaft's journal and the bearing surface never actually touch each other; they ride on a cushion of continually replaced microscopic ball bearings (oil molecules). During circulation, the oil takes the heat away from the bearings, and washes away impurities.

How you'd implement something like this in a hard disk drive, I have no idea, and I'd love to see any real techical info on it. (Marketing hype will not answer the questions I have.) But it's a great idea; in a server, with the hard disks spinning all the time, the hydrodynamics of the situation suggest that the platter bearings would never wear, and would therefore never have their tolerances open up and incur vibration.

But a seal would be required to keep the lubricant off the platters, and that seal would itself eventually wear out. Not to mention that it's unlikely they'll include a provision to do an oil change on these things. Stopping and starting cycles will wear the bearing and journal material, causing tiny abrasive bits to be floating in the oil.

I like the idea, I think it's a great step, and I'll look forward to seeing how hard disk manufacturers have solved the problems.

For sure! Even if it costs less to machine these than the super-tight clearance ball-bearings that modern hard disks must use, they'll still be a "new feature" which can enhance prices and profit margins. But I think they will actually cost more to make; it's just that ball bearings (like older stepper motor head actuators) have too many limitations to work with modern capacity and track density demands.

Slashdot has reviews of this strange new technology known as a Dynamo?! Wow! Now we no longer have to wonder if these results of witchcraft actually work.

I wondered myself, since it's brand new technology :P

What is so amazing about this again?

...an old joke. I once knew a guy who worked at Ford Aerospace. This was back when anti-lock brakes were still in their research phase. I asked him when they might go on the market. His response was that he had too little faith in software to rely on it to stop his car. His exact words: "It brings a whole new meaning to the halting problem!"

A few quotes and the standard journalist rambling. It might be appropriate on this day to find out/brush up on how they work.