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I've heard of people building bridge rectifiers to solve this. You basically use four diodes, and use this to reverse the negative part of the AC wave when the LED isn't on. Click for more information. You will still get some flicker with the bridge, but you can throw in a largish capacitor and that will get rid of most of it. Otherwise, if you can get your hands on a higher voltage DC power supply (100-150V or so) you could probably drive the LEDs off of that.

Terrace's work was a major blow to talking-ape proponents. But their case started looking stronger in 1990, when researcher Emily Sue Savage-Rumbaugh of Georgia State University presented evidence of language development in a bonobo chimp named Kanzi. One of the more telling complaints made about gorillas like Koko who communicated via sign language was that they often babbled, producing long, apparently meaningless strings of signs. Their handlers would then pluck a few lucky hits from the noise and declare that communication had occurred. Savage-Rumbaugh got around this problem by teaching Kanzi to point to printed symbols on a keyboard, a less ambiguous approach. She claimed that the ape demonstrated a rough grasp of grammar using this system. What's more, when presented with 653 sentences making requests using novel word combinations, Kanzi responded correctly 72 percent of the time--supposedly comparable to what a human child can do at two and a half years old. (Emphasis mine)

Terrace's work was a major blow to talking-ape proponents. But their case started looking stronger in 1990, when researcher Emily Sue Savage-Rumbaugh of Georgia State University presented evidence of language development in a bonobo chimp named Kanzi. One of the more telling complaints made about gorillas like Koko who communicated via sign language was that they often babbled, producing long, apparently meaningless strings of signs. Their handlers would then pluck a few lucky hits from the noise and declare that communication had occurred. Savage-Rumbaugh got around this problem by teaching Kanzi to point to printed symbols on a keyboard, a less ambiguous approach. She claimed that the ape demonstrated a rough grasp of grammar using this system. What's more, when presented with 653 sentences making requests using novel word combinations, Kanzi responded correctly 72 percent of the time--supposedly comparable to what a human child can do at two and a half years old. (Emphasis mine)

Terrace's work was a major blow to talking-ape proponents. But their case started looking stronger in 1990, when researcher Emily Sue Savage-Rumbaugh of Georgia State University presented evidence of language development in a bonobo chimp named Kanzi. One of the more telling complaints made about gorillas like Koko who communicated via sign language was that they often babbled, producing long, apparently meaningless strings of signs. Their handlers would then pluck a few lucky hits from the noise and declare that communication had occurred. Savage-Rumbaugh got around this problem by teaching Kanzi to point to printed symbols on a keyboard, a less ambiguous approach. She claimed that the ape demonstrated a rough grasp of grammar using this system. What's more, when presented with 653 sentences making requests using novel word combinations, Kanzi responded correctly 72 percent of the time--supposedly comparable to what a human child can do at two and a half years old. (Emphasis mine)

Yes, but it's spelled "lumen" (strictly speaking, output is measured in lumen, intensity upon an illuminated surface is measured in lux). A theoretical 100%-efficient lightbulb will convert 1 watt of electricity into 683 lumens, however no lightbulb approaches this. For example a 100 watt incandescent will typically output 1700 lumens for a 2.5% efficiency. The 14-watt compact flourescent bulbs I bought for $10/6 output 900 lumens for 9.4% efficiency. Enlux's neutral-white floodlight does 300 lumens with 15 watts input (no lumens data listed for their 22W nominal input) for 2.9% efficiency.

The best low-pressure sodium lamps do 183 lumens per watt, or 26.8% efficiency, however like many high-efficiency lamps they produce only a single output color, meaning that your eye won't be able to distinguish colors of objects illuminated solely by such a bulb. A lamp's ability for it to produce a natural variety of colors is measured by its CRI (Color Rendering Index).

I think this explains it:
Cyclotron
maybe.

Is it though? doesn't that mean it has 3 samples per waveform at 14.7Khz? How then can it reproduce a sine wave, square wave or sawtooth wave accurately at that frequency? How can it differentiate between them?

It can't. It doesn't matter, though because nothing else in the recording or playback system can, either.

Square waves and sawtooth waves, like all waveforms, are the sum of a number of sine waves of different amplitudes, phases, and frequencies.

For example, a square wave contains the original frequency (the fundamental), plus all odd multiples of that frequency (the harmonics). For a 14.7Khz square wave, the lowest frequency harmonic present would be three times 14.7Khz, or 38.1Khz. That's above the frequency response of most of the components in the recording and playback systems. The next harmonic is the fifth, at 67.5Khz. Forget about it.

Even if they could reproduce high enough frequencies to represent and reproduce the square wave, you couldn't hear it as a square wave anyway, because the ear hears sound by breaking it down into it's fundamental soundwaves, and you can't hear above 20Khz at the very highest (probably not even). Since you can't hear the harmonics, you can't hear the difference between a square wave and a sine wave at that frequency.

Interesting info on waveforms.

Why use LASER?

With a laser, The beamwidth is small allowing a greater energy density. See geometry.
One drawback that may come to mind aiming. This is easy to get around if you have an active target, say a LASER signal from the Earth.
The information carying capacity of a radio (or LASER) signal =
POWER * BANDWIDTH. Power = energy * time.
With a narrow beamwidth you've increased the power*bandwidth. Think of a rectangle. Bandwidth is the length, power the height. The area in the rectangle is available for data. The heght of this boxcar is limited by noise power. Low noise is attractive. There are plenty of low noise 'holes' in the spectrum for NASA's LASER. On top of this, it's easy to filter the LASER signal from broadband background noise.

The GOAL for those who didn't RTFA is higher bandwidth communicatrion in interplanetary exploration. Better photos, wider range of instrumentation. More processing power on Earth can be applied to RAW data which for now has to be dealt with by the remote processors.

centrinia___base___N___large___arithmetic___multip lication

Hate to be picky, but muons are actually considered pretty long lived. They have a half life of over 2 microseconds. That sounds short, but it's a lot longer than a free neutron (for example), and it means they're really useful for probing materials.

Are you trolling? Free neutrons have a half-life of about 10 minutes

The general equation is:

fdoppler = (frest * velocity )/ c

Not to be pedantic, but I think it should be mentioned that this is a first order approximation to the relativistic doppler shift as seen (here):
fdoppler = frest * Sqrt(1-beta^2)/(1-beta)
where beta = velocity / c

Not terribly important here, but definitely so in other astronomical fields.

This is enough difference to allow police speed radar traps to work, and for researchers to measure the wind speeds inside tornado's.

Not only that, but I've personally measured changes in velocity of an object on the order of 10s of microns per second using gamma radiation doppler shift (using the Mossbauer Effect). It's really quite incredible - a simple and fun experiment to try if you can.

Cheers,
Justin

The general equation is:

fdoppler = (frest * velocity )/ c

Not to be pedantic, but I think it should be mentioned that this is a first order approximation to the relativistic doppler shift as seen (here):
fdoppler = frest * Sqrt(1-beta^2)/(1-beta)
where beta = velocity / c

Not terribly important here, but definitely so in other astronomical fields.

This is enough difference to allow police speed radar traps to work, and for researchers to measure the wind speeds inside tornado's.

Not only that, but I've personally measured changes in velocity of an object on the order of 10s of microns per second using gamma radiation doppler shift (using the Mossbauer Effect). It's really quite incredible - a simple and fun experiment to try if you can.

Cheers,
Justin

It's not so much that the eye is less sensitive to blue light, but it's less sensitive to *variation* in blue intensities. The blue light content of an image is simply less meaningful to our perception of what an image looks like than red or green. A page on this I got from googling "eye sensitivity blue green" is here

The upshot of this is that, because there are 4 green subpixels, assuming that each subpixel can range from 0-255 in intensity, the color range of one of these "pixels" can go from 0-2047, while the color range in blue is only 0-255. It wouldn't be productive to have as much range in blue as in green or red, simply because we're not as sensitive to such variation. Of course, normal monitors *do* vary as much in blue as red and green, and that's why subpixel rendering is an improvement.

If you do not understand business law, please don't post as if you do.

Do you?

Linky 1
Linky 2
Linky 3 (I love the quote: "The GPL IS a contract. Calling it a license simply describes the type of contract it is. some people get confused and believe licenses are always required when copyright interests are at stake.")

I think the difficulty arises when people read things like this article which state that the GPL is a license because it is not solely enforcable by contract law. This is true. It is enforcable by contract law if the redistributer claims to have accepted the license. Yet the GPL relies on standard copyright law as a backup in case the redistributor claims to have not accepted the contractual requirements of the GPL license.

Now please, run along. For one day, I've been insulted more than enough for knowing what I'm talking about.

Indeed, that is the key point. From this list you can get an idea of the index of refraction of common materials. This ceramic glass has index of refraction of 2.08.

Presumably this ceramic glass has the advantage of being hard and have a very low cost, otherwise they might as well use cubic zirconia (index of refraction 2.17)

This might be a case of a solution finding a problem.

Electrons dont move through copper at the speed of light. However, they do move faster than sound does through a fluid.

(Oh, and before anyone pipes up with the "wind turbines aren't efficient" thing, I'd refer you to the Carnot Efficiency of a heat engine. The typical thermal efficiency of a steam plant is around 40%, the total efficiency of a typical wind turbine about 35%. They're comparable, especially when you consider you don't have to go digging for wind's fuel.)

John Kerry's such a swell guy that one of the most useful electronic devices was named after him. The J-K Flip Flop

This calculator gives some perspective to the comparison: http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic /frecol.html#c1

Just for interest sake, if you scale the time dimension to the same ratio as the space dimension (stars are ~10^19 bigger than a molecule), a molucule would collide with another (at STP) every ~100 years instead of 2E-10s.

I just downloaded the ctss-listings.zip file with Bit Torrent and have posted it on my school account. You can download it here. I don't think that this server can be slashdoted so feel free to use it as much as you want. By the way, I was able to cut down 2 megabytes my switching over to the bz2 format. Nothing was lost here except for some redundancy.

Here is the shameless plug: my project is here. Spread the word.

I just downloaded the ctss-listings.zip file with Bit Torrent and have posted it on my school account. You can download it here. I don't think that this server can be slashdoted so feel free to use it as much as you want. By the way, I was able to cut down 2 megabytes my switching over to the bz2 format. Nothing was lost here except for some redundancy.

Here is the shameless plug: my project is here. Spread the word.

I don't think what he's suggesting will dim the bulbs. His suggestion is basically a hack that screws with the oddities of AC power. Without checking things exactly, I believe what he's done is screw up his Power Factor. In the US (I believe), residential owners are billed without consideration for the Power Factor, so he's probably right that this will save you money. The light won't be any dimmer.

He's also right that it doesn't save any power. And he omits the fact that screwing up your Power Factor is not good for the efficiency of the grid, and probably ends up costing the grid more power than just running normally in the end.

I have heard that other countries measure the PF for residential users-- which is why you see computer power supplies marketed with "active PF correction" to keep your 600W gaming machine's PSU from fucking up the power grid.

Here's an article (and another) that explains the basics of AC Power Factor-- an excess of capacitive or inductive loads will result in a leading or lagging power factor, which results in you getting more current delivered for the same amount of power used, and they eat it as line loss in their grid. Industrial facilities in the US *are* charged for having a leading or lagging (ie, not 1) Power Factor, so for factories with lots of electric motors (big inductors), they'll often have a big capacitor bank to pull the PF back in the other direction.

His trick is to use the fact that light bulbs could care less about PF, AC, or DC to run them roughly DC. The diode clips off the bottom half of the 120V sine wave. The capacitor (charged during the "up" cycle) will supply power during the "down" half of the cycle (which is now off, thanks to the diode), with side effect of giving him a leading power factor.

My EE classes are getting rusty, so if anybody wants to post a more thorough analysis or point out any mistakes, feel free.

Yes, you are very correct; it was my faulty memory: no parity check. Both NAND and NOR are universal.

For the interested: NAND and NOR gate logic.

Yes, you are very correct; it was my faulty memory: no parity check. Both NAND and NOR are universal.

For the interested: NAND and NOR gate logic.

How about using some aerogel for robot footwear protection? Hrm, doing a google it appears that melted rock has a temperature of 1200 degrees C, which is the same as aerogel. Perhaps a combination of ceramic and aerogel?

I believe I understand what the parent was trying to say, however the only way I am able to adequatly explain this is with a Minkowski diagram. I suggest you try googling it.

On a side note it is this reason I have always had trouble with the whole time dilation effect of light speed. In that same example if you left here in a ship traveling at light speed you would arrive on the parallel earth in 7 years time, or in the year 2011 on both planets. Its 2004 there now and in seven years you would be there in 2011. Many people seem to think you would get there in 2004. If you have twins, one set here and one set there where one makes the trip then according to relativity the twin that makes the trip will be the same age as when they left thus from their perspective making the trip instantly while 7 years would pass for the twins that remained on their respective planets.

Actually, due to the fact that the ship (and you) have mass, you cannot travel at v=c, however you can approach c. For the sake of example, let v=.99c. In that case, the trip would not be insantaneous,it would take t' = t*[(1-v^2/c^2)]^1/2. Take t = 7 years and we find t' = .7 years. As for your concerns, time dilation is an observable effect. It is quite real.

Q: Why couldn't the ESR scientist ever get a date?

A: Because he was such a Bohr! (explanation)

Oh, you didn't mean Electron Spin Resonance? Sorry.

1/r^2 stands true for all electromagnetic waves. That means the intensity of the signal will decrease by the square of its distance.

This isn't a true statement depending on what exactly you mean...

For one the range of the electromagnetic force is infinite (see this for more information).

Second the inverse square law comes from the fact that the area of the shell of radiation coming off of a point source (star for example) increases to the square of the radius from the source (basic geometry). Yet the amount of energy (number of photons in the case of electromagnetic radiation) that is in that shell of radiation is constant so the density of those photons reduces by the inverse of the square of the distance (See this for a graphical explination.)

So if you look at a given photon traveling through space its "signal" will not weaken with the square of the distance, if it did this universe would be a dark dark place (also it would break the concept of quanta).

Also if you have photons traveling parallel to each other then the inverse square law doesn't apply because you have not radius to begin with.

Now it is hard to get fully parallel photons but you can get close (lasers, maser, etc.) and the closer you get the greater the radius of the theoretical point source for the signal. The greater the radius of the point source the father the signal can propagate before the exponential effects of the inverse square law begins to take hold.

So yes it is likely that the inverse square law applies to signals such as these but the point source radius to use in the calculation can be relatively huge if you take steps to focus the signal (attempt to have the photons travel in a parallel beam).

1/r^2 stands true for all electromagnetic waves. That means the intensity of the signal will decrease by the square of its distance.

This isn't a true statement depending on what exactly you mean...

For one the range of the electromagnetic force is infinite (see this for more information).

Second the inverse square law comes from the fact that the area of the shell of radiation coming off of a point source (star for example) increases to the square of the radius from the source (basic geometry). Yet the amount of energy (number of photons in the case of electromagnetic radiation) that is in that shell of radiation is constant so the density of those photons reduces by the inverse of the square of the distance (See this for a graphical explination.)

So if you look at a given photon traveling through space its "signal" will not weaken with the square of the distance, if it did this universe would be a dark dark place (also it would break the concept of quanta).

Also if you have photons traveling parallel to each other then the inverse square law doesn't apply because you have not radius to begin with.

Now it is hard to get fully parallel photons but you can get close (lasers, maser, etc.) and the closer you get the greater the radius of the theoretical point source for the signal. The greater the radius of the point source the father the signal can propagate before the exponential effects of the inverse square law begins to take hold.

So yes it is likely that the inverse square law applies to signals such as these but the point source radius to use in the calculation can be relatively huge if you take steps to focus the signal (attempt to have the photons travel in a parallel beam).

for speed of gravity, see Kopeikin et al, on www.arxiv.org (eg. gr-qc/0310065 and references therein); note that there has been criticism of this paper, I can't judge who's right.
But it seems that John Baez is convinced by Kopeikin's result, and I'd trust Baez' word on this.
I don't know of any measurements of the speed of the strong and weak force. This is certainly extremely difficult, since they are short-range interactions (acting within nuclei only, 10^-15m and shorter, see here ).
I'm not aware of any problems with the standard model: the particles mediating the weak interaction (W+,W-,Z) are massive, hence the speed of the weak force should be smaller than c. The force between quarks is mediated by "gluons" which are predicted to be massless, hence the speed shoud be c.

The only thing I do not like is the weird quark all optical mice have.

Ahem.

I think you meant strange quark .

Sorry, correcting incorrect assumptions about physics is a strange quirk. of mine. :)

The only thing I do not like is the weird quark all optical mice have.

Ahem.

I think you meant strange quark .

Sorry, correcting incorrect assumptions about physics is a strange quirk. of mine. :)

You were not lied to.

For those not versed in things nuclear (and why positive temperature coefficient of reactivity reactors are a BAD IDEA), a good background on the accident and nuclear power in general.

"Spent" fuel still has plenty of Uranium in it. So you can take that spent fuel, do a quick chemical seperation, and generate more *usable* fuel. Like the earlier poster said, PU (plutonium) can also be used and generated in certain reactor designs (commonly called "breeder" reactors). By using a system like this, it's stated that you can use about 75% of the uranium, rather than 1% of light water reactors. And a number of the byproducts will also fission, producing even more power. More than 75 times the power? I'd say that'd extend the lifespan of fission! It'd give us plenty of time to figure out fusion, or your solar energy. Waste wouldn't be as big of a deal, because there'd be 1/75 as much of it, and I've read that the waste has a shorter half life, so it'd only be dangerously radioactive for a couple centuries rather than thousands of years.

Fore more information, there are a number of sites such as this
Reason why we don't have breeder reactors
I've read that any nucleas heavier than Iron gives off energy when split, and atom lighter gives energy when fused. The further from Iron, the easier and more energy it gives.

She has the same problem with distinguishing light blues from light greens that you describe. I suspect that she has cones with a slightly different response curve than mine, with the difference probably in the mid-range cones. The other possiblity is that her ``blue boosting'' mechanism is slightly different than mine. This seems a bit more plausible, since it's apparently based on something in the nervous system rather than having a different chemical in her cones.

She has the same problem with distinguishing light blues from light greens that you describe. I suspect that she has cones with a slightly different response curve than mine, with the difference probably in the mid-range cones. The other possiblity is that her ``blue boosting'' mechanism is slightly different than mine. This seems a bit more plausible, since it's apparently based on something in the nervous system rather than having a different chemical in her cones.

No. This is just moronic marketing hype from people who should know better targeting people who don't.

First of all it's not a new idea - we looked into it at apple in the mid 80's as a way of getting more brightness out of LCDs. Using a CMYG pattern for example.

Second, a cursory glance at the CIE diagram teaches those who understand how it works that well placed RGB primaries cover almost the entire visible gamut (90% or so). There just isn't 20% left to add with a few more primaries, let alone 65%. That's not how vision works. (A cyan primary might add about 10%, but a yellow doesn't do much of anything and magenta just isn't a primary).

And third, neither video nor movies are color matched anyway. There's no "right" color for a tv program. It's what you want it to be. That's why NTSC stands for Never Twice the Same Color. Expanding the gamut is just like turning up the saturation on your TV. Is your saturation maxed? If so, you'd probably like a TV with a larger gamut (OK, it's not quite that simple, but video programming is targeted to the typical gamut of a TV, so the new technologies typically have to be turned down or they look a unnatural, as the article described. That is, if you really use the new gamut, it looks borked anyway, unless you like that sort of thing.)

If you've got crappy, unsaturated primaries, then adding more colors can expand the range, but at the expense of monumental complexity in the color math. Comon - getting color matching to work even marginally right with only three primaries is a task yet to be even partially achieved - how many of you have color calibrated monitors? And you want to add more primaries? Get a grip on the 3 you've got!

The press release does speak of a truth in subtractive color displays (like LCDs but not CRTs) that there is an intrinsic trade off between color purity (gamut) and brightness. Of course you can always use a brighter lightbulb/backlight... Or an alternative primary color technology like CRTs LEDs OLEDs Lasers... etc today. Large screen OLEDS would have a far better gamut than this crap anyway.

If you want to see amazing color look to laser displays or Sony's new reflective ribbon technology (that uses a laser as the source) with pure RGB primaries, there's no advantage to be had...

As for the technology being unique or special (not short bus special, though it is that) it's not. Your 5/6/7/etc. color inkjet printer does exactly the same thing. With reflective images (subtractive color) you don't really have primaries, you've got inks, and long ago people chose to print in RGB complement CMY (the K part is just because most inks suck and CMY all togehter would be grey, not black, so they added the black - sound familiar to the story? That's only about 100 years old). Anyway, looking back at our old CIE diagram we see that Cyan Magenta and Yellow inscribe a wee triangle even with fully saturated inks, so Epson chose to add a few more colors (and then more, and more) and figure out the color math behind the transformation from CRT RGB primaries (or CIE LAB) to CMYKC2Y2M2 etc. It works well with printers (Epson was actually copying Pantone's Hexachrome offset process, which itself is probably not the first).

It's an OK idea to improve the image quality of the color mixing functions used to filter incoming light for color cameras (typicaly CMYG, though some cameras now use RGB), but it's just silly with LCDs. If you're really a color fanatic you're probably using a CRT anyway.

As an aside, in the persuit of some research about 10 years ago I found a paper article presenting research in capturing archival images of paintings and other works of art, and seeking to eliminate all possible metamerism between the color mixing functions of the detector and the human visual system. The authors found that to do so required a 7 primary system. I haven't been able to find the article again and I'm not

Deuterium is or can be generally extracted from seawater. Look here for simple fusion info.

If one had the technology to vary the intensity of red, green, and blue over an infinite set of real values, then RGB would be able to perfectly replicate any color.

Wrong. Take a look at a CIE Chromaticity diagram and you'll see that no matter what three wavelengths you choose as your primary set, there will be some colors you can't mimic.

In particular, if one judges the 'distance between a two shades of red using a RGB colorspace, and compares that to two similar distances between shades of blue, they would guess those distances to be wildly different.

the cie color space is far more accurate for displaying percieved distances between colors.

• We will never consume all the oil in the ground; if we tried, we'd be dead from global warming before we managed to burn it all.
• Electricity and hydrogen are not energy sources, they are energy currencies (or carriers).
• Electricity and hydrogen are complementary:
  1. Electricity can be transmitted over distance efficiently, can be used by data processing equipment, can be converted to physical work (motors). Electricity can be converted into hydrogen (with a conversion cost).
  2. Hydrogen can be stored (eg: for use in airplanes). Hydrogen can be converted into electricity (with a conversion cost).
• Fuel cells don't require hydrogen; you can use any fuel in a fuel cell.
• What makes fuel cells great is they are not limited by the Carnot cycle. Internal combustion engines are heat engines. All heat engines have an efficiency upper bound converting energy into work. Fuel cells are not limited by the carnot cycle and therefore have higher theoretical maximum efficiency.
• Nuclear is an energy source - one of the only energy sources not involving the carbon cycle.
• Nuclear is expensive.
• Clean, non-nuclear energy sources (wind, solar, tidal, etc) collectively cannot provide enough energy to satisfy our needs, making nuclear an eventuality, not an option.

It's a Doppler effect. Police radar works on the Doppler wavelength shifting of the reflection from the moving car, and the microwaves of radar are a part of the electromagnetic spectrum along with light.

The blackbody curve of solar radiation has a peak in about the green wavelengths. The curve falls rapidly as the wavelengths get shorter (bluer), which is why it takes minutes instead of seconds to get a sunburn even under the most intense sunlight. But the curve slopes off much more gently to the red end of the spectrum (see this page).

The problem with what you're saying is that you seem to assume that the only way that a site can look good in IE is by using IE-only features. This is just not true. I just launched a site using web standards that looks exceedingly good in all major web browsers. I did have to use a proprietary IE feature (If statements) to get around parts of IE's broken ass CSS engine but the design as a whole caters to web standards, not just one browser.

If you read the feedback on those IE pages you'll see that there is a HUGE demand for the features discussed. Couple that with the fact that IE is losing marketshare and you may find that catering to IE really amounts to painting yourself in a corner.

As Schroeder puts it "So don't bother installing a Carnot engine in your car; while it would increase your gas mileage, you would be passed on the highway by pedestrians."

In this case the speed is not related to the wave height at all, only water depth.

A short-wavelength wave will move slowly in any depth of water; the speed of rogue waves is determined by the same factors as those of other wind-driven waves. The distinguishing feature of "rogue waves" is that they are tall and steep, and the same factors which allow them to do damage make them theoretically amenable to surfing.

With a Carnot engine, that means you get half of that, max, assuming perfect cooling (which doesn't really exist).

Sorry, that was bunk. With perfect cooling, you can get 100%. At reasonable temperatures for the hot and cold sides, the max is about 50%.

True enough. Although there are precision applications, such as aircraft controls, where you want to take even a small amount of fluid compression into account - if your flaps are a degree or two lower or higher than you think they are, the results are potentially unpleasant.

Anyway, I just wanted to point out that liquids do indeed compress, albeit generally not as easily as gases, as you say - under normal conditions, it's not at all incorrect to think of water as being incompressible, but it is compressible to some small degree, as you can see here ;)

I'd like to note that nuclear weapons have become much more powerful since then.

From here:

On August 6, 1945, a uranium fission bombwas detonated over the Japanese city of Hiroshima. The bomb, called "Little Boy" was a "gun-type" device which used an explosive charge to force two sub-critical masses of U-235 together. It was 28 inches in diameter and 120 inches long, a relatively small package to deliver an explosive force of some 20,000 tons of TNT by converting about 1 gram of matter into energy. This could be accomplished with a sphere of U-235 about the size of a baseball. This kind of device had never been tested, in contrast to the plutonium bomb which was dropped on Nagasaki three days later. No device like this has been used since, making the estimates of radiation exposure at Hiroshima very difficult. Casualties included both direct blast victims plus those who died from radiation-induced cancer in subsequent years.

The bomb was triggered to explode at a height of 550 meters (1800 ft), a height calculated to cause the widest area of damage.

In the detonation of the uranium fission bomb over Hiroshima, about 130,000 people were reported killed, injured, or missing. Another 177,000 were made homeless.

The U.S. exploded a 15 megaton fusion bomb on March 1, 1954. It had a fireball 4.8 km in diameter and created a huge characteristic mushroom-shaped cloud. Analysis of the radioactive fallout from this bomb revealed it to be a fission-fusion-fission weapon, a "hydrogen bomb" with an outer sheath of natural uranium to increase the yield.