LEDs have almost nothing to do with antennas, aside from the fact that both emit EM radiation. Specifically, there is no oscillator in the LED. The photons are a direct result of the diode band gap -- each electron-hole pair combining emits one photon with energy equal to the electron charge times the forward voltage (ie a 3V forward voltage LED emits photons with 3eV of energy, aka blue visible light). The Wikipedia page has a fuller explanation.
The reason LEDs produce weird light is that their spectrum is a sharp band, as opposed to the broad hump of a black body. This can be fixed (somewhat) by using a phophor to shift some of that frequency (most white LEDs), but the usual techniques for that leave a gap between the LED emission and the phosphor emission. Better, though more expensive, is combining enough different color LEDs that the narrow individual bands blend together to simulate the blackbody output. Eventually, that will get cheap enough to be common, and then you'll see LEDs in common usage as lighting.
My understanding (from a friend, I haven't used them) is that LED xmas lights are half-wave rectified, so they have a 60Hz flicker. If you get out the soldering iron and install a full wave bridge rectifier, and optionally replace the ballast resistor with a somewhat larger one, it will stop flickering. (If you leave the same ballast resistor, it will be twice as bright, but should work just fine.)
First, said doctrine is not correct even in the intended context.
Second, just because you can use some of the same words does not mean that your armchair legal theory has anything to do with their legal theory. That said, it is equally correct (which is a nice way of saying wrong).
I don't need menus for things that aren't adjustable. You'll notice my feature list did not include auto-focus; I don't need to adjust the auto-focus mode, because the only option would be "off." Ditto white balance; the light coming into the camera isn't being affected by that setting, and neither is how the CCD measures it. So the only setting is "flat." White balance is a post-processing step; on a cheap camera that isn't giving you raw output, it's useful to do it before the downsampling of the A/D result and the conversion to jpg, but this (apparently theoretical) camera would not do those because it's saving raw mode. Yes, I'm aware that things like auto-focus are sometimes useful -- but I wasn't inquiring about those cameras, because I know where to find them.
The rights enumerated in the Constitution, like all human rights, apply to all people -- citizens or no. Nowhere does the Constitution grant the federal government the power to abridge those rights simply because the person in question is not an American citizen.
My whole point was that I don't want to play with menu options. I want to have to think about the photo, and what I want the camera to do, and not spend mental resources on making it do it. Getting a user interface that you literally don't have to think about takes work -- and it also takes keeping it minimal. Yes, all those features can be handy -- but they can also be distracting. Finding a camera that has those features is trivial; finding one that doesn't have extra ones isn't.
Those features aren't that important for the early learning. Learning about taking pictures involves getting an intuitive feel for what shutter speeds and apertures do, learning about framing, what makes a good background, what sort of lighting will look good in the final version, etc. These are not things that demand a top of the line image sensor or lens. They do, however, require you to be aware of what is going on inside your camera.
Eventually, yes, you'll want those things. And there's certainly some benefit to having them early on. But they aren't actually that important for the learning process.
One part of learning to take great photos is simply taking lots of photos; no argument that the simple lightweight point and shoot has its place there. But another part is learning what happens to the light, and how that impacts what the final product looks like. And for that, I don't want lots of automatic features hiding the details, and I especially don't want to have to think about things like menu options instead of how I want the camera to behave.
That lack of complicated menus is *specifically* the feature I'm looking for. I don't want lots of options. I don't want to have to worry about whether the auto white balance is on. I don't want to have to hunt through menus -- ever. About the only thing I'd like from the usual collection of digital camera features is a decent quick review mode, but if I have to give that up I'm not overly concerned.
Modern guessers start modifying the dictionary and evaluating things in a prioritized order based on how far away they are from it. Until your password bears no visible relationship to the dictionary, you're too close; it's not just a simple in vs out question. If you care about your password, you need to make a serious evaluation of how many bits of entropy it contains, and assume the attacker can guess in a priority order that will limit its effectiveness to that many bits. If you only have 30 bits of entropy, you should assume your attacker can guess it in half a billion tries or so; making assumptions that he'll be inefficient is a *bad* idea.
If you're worried about the source or transmission channel being compromised (or malicious) you've just inserted *several* bits of entropy. A good password needs 64 bits or more if you want to protect against this sort of attack. A presumed compromised source of random data supplies zero bits of entropy. This is really something you need to do on your own machine, if not manually. Rolling dice just isn't that hard.
I'm all in favor of digital, but the archival problem is far from trivial. Good quality prints on good paper can be expected to still be good quality prints in decades or even longer. Storing digital data for that long requires more than simply storing the print in a cool dark room with temperature and humidity controlled to reasonable levels. You have to be sure you can read the media, and also the file format. There are original photo prints well over 100 years old; books can be even older. Storing digital data that long in a usable form will take work.
Careful with that line of reasoning. A lot of what a camera with better manual modes does is simply make you aware of what is happening. As you try to make your photos look better, awareness of things like aperture and focal length and shutter speed will help. I'm aware that for many people, goal-directed learning works better -- but for some, especially geeky types, just paying attention and observing the differences between (eg) comparably exposed shots with different aperture settings will be very helpful. It's not (so much) that there are things the SLR can do that the P&S can't; it's that you'll be more aware of what the camera is doing.
So, if he wants to take better pictures, and is willing to put effort in, a more manual camera is a good investment early on. Having to fight with the camera is a big turnoff. Of course, the more expensive camera isn't better if you don't use what it gives you. It's *part* of how you learn about photography, and it certainly won't teach you by itself.
Does anyone make a (reasonably priced...) digital equivalent of the old standard learning camera -- fully manual, no gobs of features, just shutter, aperture, focus, and an exposure meter? Probably SLR, though not required, and ideally with a fixed length lens in the basic package. It seems these days the designers observe they have a microprocessor available and pack everything in, and it's hard to find that older elegant simplicity.
Be very careful when reading stats on pilot error. Generally, if a report claims something was pilot error, it is appropriate to ask what caused the pilot error. The answer can usually be found in some sort of human factors design flaw -- poorly laid out controls, confusing instruments or indicator layout, overly complex procedures, poor scheduling leading to fatigue, etc. When you decide the pilot made a mistake, that is not the end of the investigation -- and it doesn't mean that the correct solution is to replace the pilot with an AI, either.
It does not reach full brightness in one cycle. 50 ms will get it nearly there, perhaps 100ms or a little more to get all the way. I'm afraid I'm away from my scope right now...
Do you think that some form of stimulus is required? If so, and it's not gov spending, what is it? (And, from a policy standpoint, I would say that inefficient and ineffective counts as bad. If the stimulus won't help anything, then I'd just as soon have lower taxes and less national debt.)
Taxes on people who were going to put their money in a bank account because they're scared to invest right now.
Borrow from foreigners and banks and others who weren't going to invest in US businesses (see above about banks being scared to invest right now -- that's the whole 'credit crunch' thing) via treasury instruments.
Government spending isn't inherently good or bad; neither is deficit spending. Much like private spending, and private spending with borrowed money (eg a mortgage). In both cases you have to look at the details before deciding whether it's a good idea or not. Surprise! Economics is not trivial.
For DC and AC with the same RMS voltage, both require the same RMS current for equal power. They both lose the same amount of power to heat from resistive line losses for equivalent transmission lines.
Of course, in the real world, things are more complicated. AC won historically because you can convert voltages easily; as you're well aware, transmission lines want low current and high voltage to minimize losses. That means a transformer at either end. Now, with high efficiency switching supplies, that reason has disappeared (in some cases, anyway).
Of course, that's not the whole story either. AC transmission lines also have radiative losses -- they're giant antennas, and they lose some power as radio waves as a result. For long lines, that matters. Also, most of the voltage ratings are based on *peak* voltages, not RMS -- so if you switch to DC current, you can push the voltage 40% higher than the equivalent AC RMS voltage. The current is based on RMS and thermal effects, normally, so the same line can carry the same current in either case. P=IV means the DC line carries 40% more power over equivalent hardware.
Of course, very little of this matters for this application, where you have to do AC-DC conversion regardless. Here it's just a question of whether it's cheaper and more efficient to convert high voltage AC to low voltage DC in one power supply on the computer, or to split it apart and centralize the conversion to high voltage DC and then do DC-DC in the server. (See my other comment for some reasons it might be. I've designed power supplies, but not this class of them, and it's not something I do a lot of work with. So I'd say I'm medium-qualified to comment...)
Switch mode supplies that run off DC input don't require a big high voltage input capacitor. They also don't require complicated PFC circuitry. Basically, a modern AC-DC SMPS has an input boost converter that goes to ~380-400VDC, and then a forward or flyback converter that turns that into usable voltages. This is required to get power factor correction, which is required for high efficiency on a large system. This system moves the first half of that outside the computer into one large device. Running the large converter off three-phase power makes it mildly more complex but removes the bulk capacitors. Between that and the fact that there is only one of these converters, it's a lot cheaper. Also, power electronics generally get more efficient as they get larger, for a variety of reasons; this takes advantage of that.
The major economic reason to run off 48VDC instead of 400VDC is that some gear already exists thanks to the telcos; the major reason not to is thicker more expensive wiring. Which one wins depends on the size of the market, and it sounds like the market is big enough that the 400VDC probably wins.
If you really wanted to, you could push the AC-DC efficiency higher with more expensive electronics -- but centralizing it is cheaper, so why bother?
There's a meaningful difference between having your perception of what is there altered, and perceiving things that are not there. The latter is a hallucination (in the technical sense), the former is not. That doesn't mean that the altered perception is real. It doesn't even say much about whether the hallucination or the distortion is a stronger effect. Is hearing your cell phone ring when it didn't a milder effect than having the geometric designs of your wallpaper morph into animals that walk across the wall? Probably. It's also a true hallucination, while the other isn't.
The researchers do not state there is causation;/. does. The researchers state "However, they also suggest that people who are more prone to hallucinations could also be more stressed and more likely to consume large amounts of caffeine." Another reasonable conclusion is that people who need sleep hallucinate more -- and that people drinking caffeine spend more time in a sleep-deprived state (making the caffeine a contributing factor rather than "the cause"). Yet another is that hallucinations correlate with other mental features that cause people to drink caffeine. I don't know what those would be, or whether they correlate, but I do know that such factors exist -- eg people with ADD tend to self-medicate with caffeine (and sometimes stronger things) if not on prescription meds.
Slashdot Mirror
If, as the paper claims, they are hardly better than guessing, then how are they even worthy of the title "good tool"?
If there were large black holes in the solar system, they would be trivially detectable. That is how Neptune was found, after all.
LEDs have almost nothing to do with antennas, aside from the fact that both emit EM radiation. Specifically, there is no oscillator in the LED. The photons are a direct result of the diode band gap -- each electron-hole pair combining emits one photon with energy equal to the electron charge times the forward voltage (ie a 3V forward voltage LED emits photons with 3eV of energy, aka blue visible light). The Wikipedia page has a fuller explanation.
The reason LEDs produce weird light is that their spectrum is a sharp band, as opposed to the broad hump of a black body. This can be fixed (somewhat) by using a phophor to shift some of that frequency (most white LEDs), but the usual techniques for that leave a gap between the LED emission and the phosphor emission. Better, though more expensive, is combining enough different color LEDs that the narrow individual bands blend together to simulate the blackbody output. Eventually, that will get cheap enough to be common, and then you'll see LEDs in common usage as lighting.
My understanding (from a friend, I haven't used them) is that LED xmas lights are half-wave rectified, so they have a 60Hz flicker. If you get out the soldering iron and install a full wave bridge rectifier, and optionally replace the ballast resistor with a somewhat larger one, it will stop flickering. (If you leave the same ballast resistor, it will be twice as bright, but should work just fine.)
Citation needed.
First, said doctrine is not correct even in the intended context.
Second, just because you can use some of the same words does not mean that your armchair legal theory has anything to do with their legal theory. That said, it is equally correct (which is a nice way of saying wrong).
He was trying to carve his initials on it with the sharpened end of an interspace toothbrush.
I don't need menus for things that aren't adjustable. You'll notice my feature list did not include auto-focus; I don't need to adjust the auto-focus mode, because the only option would be "off." Ditto white balance; the light coming into the camera isn't being affected by that setting, and neither is how the CCD measures it. So the only setting is "flat." White balance is a post-processing step; on a cheap camera that isn't giving you raw output, it's useful to do it before the downsampling of the A/D result and the conversion to jpg, but this (apparently theoretical) camera would not do those because it's saving raw mode. Yes, I'm aware that things like auto-focus are sometimes useful -- but I wasn't inquiring about those cameras, because I know where to find them.
The rights enumerated in the Constitution, like all human rights, apply to all people -- citizens or no. Nowhere does the Constitution grant the federal government the power to abridge those rights simply because the person in question is not an American citizen.
My whole point was that I don't want to play with menu options. I want to have to think about the photo, and what I want the camera to do, and not spend mental resources on making it do it. Getting a user interface that you literally don't have to think about takes work -- and it also takes keeping it minimal. Yes, all those features can be handy -- but they can also be distracting. Finding a camera that has those features is trivial; finding one that doesn't have extra ones isn't.
Those features aren't that important for the early learning. Learning about taking pictures involves getting an intuitive feel for what shutter speeds and apertures do, learning about framing, what makes a good background, what sort of lighting will look good in the final version, etc. These are not things that demand a top of the line image sensor or lens. They do, however, require you to be aware of what is going on inside your camera.
Eventually, yes, you'll want those things. And there's certainly some benefit to having them early on. But they aren't actually that important for the learning process.
One part of learning to take great photos is simply taking lots of photos; no argument that the simple lightweight point and shoot has its place there. But another part is learning what happens to the light, and how that impacts what the final product looks like. And for that, I don't want lots of automatic features hiding the details, and I especially don't want to have to think about things like menu options instead of how I want the camera to behave.
That lack of complicated menus is *specifically* the feature I'm looking for. I don't want lots of options. I don't want to have to worry about whether the auto white balance is on. I don't want to have to hunt through menus -- ever. About the only thing I'd like from the usual collection of digital camera features is a decent quick review mode, but if I have to give that up I'm not overly concerned.
Modern guessers start modifying the dictionary and evaluating things in a prioritized order based on how far away they are from it. Until your password bears no visible relationship to the dictionary, you're too close; it's not just a simple in vs out question. If you care about your password, you need to make a serious evaluation of how many bits of entropy it contains, and assume the attacker can guess in a priority order that will limit its effectiveness to that many bits. If you only have 30 bits of entropy, you should assume your attacker can guess it in half a billion tries or so; making assumptions that he'll be inefficient is a *bad* idea.
If you're worried about the source or transmission channel being compromised (or malicious) you've just inserted *several* bits of entropy. A good password needs 64 bits or more if you want to protect against this sort of attack. A presumed compromised source of random data supplies zero bits of entropy. This is really something you need to do on your own machine, if not manually. Rolling dice just isn't that hard.
I'm all in favor of digital, but the archival problem is far from trivial. Good quality prints on good paper can be expected to still be good quality prints in decades or even longer. Storing digital data for that long requires more than simply storing the print in a cool dark room with temperature and humidity controlled to reasonable levels. You have to be sure you can read the media, and also the file format. There are original photo prints well over 100 years old; books can be even older. Storing digital data that long in a usable form will take work.
Careful with that line of reasoning. A lot of what a camera with better manual modes does is simply make you aware of what is happening. As you try to make your photos look better, awareness of things like aperture and focal length and shutter speed will help. I'm aware that for many people, goal-directed learning works better -- but for some, especially geeky types, just paying attention and observing the differences between (eg) comparably exposed shots with different aperture settings will be very helpful. It's not (so much) that there are things the SLR can do that the P&S can't; it's that you'll be more aware of what the camera is doing.
So, if he wants to take better pictures, and is willing to put effort in, a more manual camera is a good investment early on. Having to fight with the camera is a big turnoff. Of course, the more expensive camera isn't better if you don't use what it gives you. It's *part* of how you learn about photography, and it certainly won't teach you by itself.
Does anyone make a (reasonably priced...) digital equivalent of the old standard learning camera -- fully manual, no gobs of features, just shutter, aperture, focus, and an exposure meter? Probably SLR, though not required, and ideally with a fixed length lens in the basic package. It seems these days the designers observe they have a microprocessor available and pack everything in, and it's hard to find that older elegant simplicity.
Be very careful when reading stats on pilot error. Generally, if a report claims something was pilot error, it is appropriate to ask what caused the pilot error. The answer can usually be found in some sort of human factors design flaw -- poorly laid out controls, confusing instruments or indicator layout, overly complex procedures, poor scheduling leading to fatigue, etc. When you decide the pilot made a mistake, that is not the end of the investigation -- and it doesn't mean that the correct solution is to replace the pilot with an AI, either.
It does not reach full brightness in one cycle. 50 ms will get it nearly there, perhaps 100ms or a little more to get all the way. I'm afraid I'm away from my scope right now...
Do you think that some form of stimulus is required? If so, and it's not gov spending, what is it? (And, from a policy standpoint, I would say that inefficient and ineffective counts as bad. If the stimulus won't help anything, then I'd just as soon have lower taxes and less national debt.)
You missed a couple:
Taxes on people who were going to put their money in a bank account because they're scared to invest right now.
Borrow from foreigners and banks and others who weren't going to invest in US businesses (see above about banks being scared to invest right now -- that's the whole 'credit crunch' thing) via treasury instruments.
Government spending isn't inherently good or bad; neither is deficit spending. Much like private spending, and private spending with borrowed money (eg a mortgage). In both cases you have to look at the details before deciding whether it's a good idea or not. Surprise! Economics is not trivial.
For DC and AC with the same RMS voltage, both require the same RMS current for equal power. They both lose the same amount of power to heat from resistive line losses for equivalent transmission lines.
Of course, in the real world, things are more complicated. AC won historically because you can convert voltages easily; as you're well aware, transmission lines want low current and high voltage to minimize losses. That means a transformer at either end. Now, with high efficiency switching supplies, that reason has disappeared (in some cases, anyway).
Of course, that's not the whole story either. AC transmission lines also have radiative losses -- they're giant antennas, and they lose some power as radio waves as a result. For long lines, that matters. Also, most of the voltage ratings are based on *peak* voltages, not RMS -- so if you switch to DC current, you can push the voltage 40% higher than the equivalent AC RMS voltage. The current is based on RMS and thermal effects, normally, so the same line can carry the same current in either case. P=IV means the DC line carries 40% more power over equivalent hardware.
Of course, very little of this matters for this application, where you have to do AC-DC conversion regardless. Here it's just a question of whether it's cheaper and more efficient to convert high voltage AC to low voltage DC in one power supply on the computer, or to split it apart and centralize the conversion to high voltage DC and then do DC-DC in the server. (See my other comment for some reasons it might be. I've designed power supplies, but not this class of them, and it's not something I do a lot of work with. So I'd say I'm medium-qualified to comment...)
Switch mode supplies that run off DC input don't require a big high voltage input capacitor. They also don't require complicated PFC circuitry. Basically, a modern AC-DC SMPS has an input boost converter that goes to ~380-400VDC, and then a forward or flyback converter that turns that into usable voltages. This is required to get power factor correction, which is required for high efficiency on a large system. This system moves the first half of that outside the computer into one large device. Running the large converter off three-phase power makes it mildly more complex but removes the bulk capacitors. Between that and the fact that there is only one of these converters, it's a lot cheaper. Also, power electronics generally get more efficient as they get larger, for a variety of reasons; this takes advantage of that.
The major economic reason to run off 48VDC instead of 400VDC is that some gear already exists thanks to the telcos; the major reason not to is thicker more expensive wiring. Which one wins depends on the size of the market, and it sounds like the market is big enough that the 400VDC probably wins.
If you really wanted to, you could push the AC-DC efficiency higher with more expensive electronics -- but centralizing it is cheaper, so why bother?
There's a meaningful difference between having your perception of what is there altered, and perceiving things that are not there. The latter is a hallucination (in the technical sense), the former is not. That doesn't mean that the altered perception is real. It doesn't even say much about whether the hallucination or the distortion is a stronger effect. Is hearing your cell phone ring when it didn't a milder effect than having the geometric designs of your wallpaper morph into animals that walk across the wall? Probably. It's also a true hallucination, while the other isn't.
The researchers do not state there is causation; /. does. The researchers state "However, they also suggest that people who are more prone to hallucinations could also be more stressed and more likely to consume large amounts of caffeine." Another reasonable conclusion is that people who need sleep hallucinate more -- and that people drinking caffeine spend more time in a sleep-deprived state (making the caffeine a contributing factor rather than "the cause"). Yet another is that hallucinations correlate with other mental features that cause people to drink caffeine. I don't know what those would be, or whether they correlate, but I do know that such factors exist -- eg people with ADD tend to self-medicate with caffeine (and sometimes stronger things) if not on prescription meds.