Well then this simply implies one should take similar precautions with Cannabis and driving that one does with Ethyl Alcohol and driving.
The problem with caffeine is that it builds a chemical dependency so that you need to drink coffee every morning just to return to your baseline level of alertness - if you drink less coffee than usual in the morning you will be more tired than usual. See this article which discusses some research asserting that a regular coffee drinker's morning coffee only counteracts their caffeine withdrawal symptoms, and that they would be just as alert in the morning without drinking coffee. So coffee really does impair you, but because drinking the coffee every morning does seem to make you more alert, it seems like it's helping you instead of hurting you. And it's a psychoactive stimulant drug, so it puts stress on your body when you consumer caffeine. Consider how many more people drink coffee than smoke marijuana, and I wouldn't be surprised if coffee in total does more damage to people's health and the economy than marijuana.
I've switched to drinking coffee only once per week, on the morning I need to get up early after also staying up late. And anecdotally I can say that I'm more energetic on the other mornings of the week now, and the one day I drink coffee it does pep me up because I'm now not dependent on the caffeine.
This is pretty reasonable to me. For example, when I search Google for the title of a book, I'm looking for the Amazon sale page at least 50% of the time. Lots of people are looking to buy stuff when they search for it on Google, and if Google arbitrarily excludes those results it would dilute the value of the search. If there are too many sales results then clarifying the search by adding or excluding certain terms will usually narrow it down enough.
What would really be interesting is if Google could distinguish between, say, commercial and non-commercial results automatically. It obviously has some capabilities in this regard with its product searching options, and if they could put in something like a (buying/not buying) check box it would mean we could find our results even faster without further clarification of search terms.
Good thoughts, but in a typical phased array receiver (which this is), the microphones will be almost equally distant from what they are sensing, because the people are much further away than the diameter of the microphone array, so the desired signal should be just as large at all receiving mics. There could be geometry considerations if they'd made the array fit on a curved surface which could be done to achieve larger scan angles, typical phased arrays work best for under 60 degrees off of normal because otherwise the power received drops too much. But from the picture this array appears to be flat.
It doesn't seem likely that the mics will distort in an ordinary environment, simply because if they could it seems to be like it would affect a large number of the microphones at once. However, it is still a possibility, and it would be interesting to see if they have a method to selectively detect such conditions and temporarily drop the affected mics, or selectively null large interfering signals coming from a particular direction.
Presumably (says I having read the article but not knowing much more about this) the mechanical switches:
How prescient;-)
No, when they mention radiation in the article it's because these devices are radiation-hard, i.e. they will last a long time in a radioactive environment such as many satellites fly in. Standard silicon CMOS devices on the other hand degrade very quickly because charged particles get trapped in the gate oxide changing the gate threshold, degrading performance, and then eventually killing the device. The silicon crystal itself is more vulnerable to defects from radiation, which increases channel resistance, again degrading performance and killing the device.
The SiC MEMs devices are more robust because SiC is more robust at high temperatures and radiation filled environments, plus as a primarily mechanical system rather than electrical, it will probably be more tolerant to crystal defects.
In a computer this will emit just as much electromagnetic radiation as a silicon chip because the radiation comes from the flow of current being turned on and off. It doesn't matter one bit if you do it with a vacuum tube, BJT, MOSFET, or MEMs device, you will get electromagnetic radiation.
It may be more robust to EMP than a Si-CMOS device, but it will still be vulnerable to contact degradation when an EMP causes breakdown of the air or vacuum dielectric.
The military does love the idea of MEMs switches, more so for radar/comms, but they got burned bad after DARPA and DOD agencies funded 10's of millions, or probably more, in R&D with no useful results. The main problem with MEMs switches has always been reliability, which you will see is also a problem in the MEMs devices being promoted in this article.
They address many of these issues in the FAQ if you follow the link: >and head-to-tail collisions would be a real problem. There are long springy bumpers of some sort to make this impact very gentle. The energy is used to push the first driver ahead, it is not dissipated.
>And if you are moving in a chain of schweebs, there will be the inevitable lazy guy somewhere in the chain not pedaling or pretending to pedal, so someone else will do all the work. This is a problem to an extent. However because of the high mechanical efficiency (greater than an enclosed recumbent bike they say) and the increased efficiency of moving together in a line, it will be tolerant to a certain amount of laziness without significantly increasing the work of the others. Furthermore there are monitoring sensors, and you could presumably be identified in your pod via schweeb membership card you swipe to get in the pod, and problematic riders could be penalized or banned.
>And if the schweeb capsules are publicly shared not privately owned, they'll get really, really gross and sweaty. They say it uses 1/3 the power of walking at 5km/h (30 watts vs. 100) so even an out of shape person should not break a sweat. However I would be concerned about the sun heating them up...
>And if everybody is commuting in one direction and they are a shared public resource, all the schweebs will end up at one end of the line... If x number of people go from point A to point B in the morning, then most of those people will go from B to A in the evening. Thus no pods pile up in any one location. Thus they just need to monitor usage and add new pods based on demand by location, plus extra to account for variability. And they will probably implement some sort of "tugboat" pod to move the pods between stations if pods start piling up in one location.
I admit I several of the same misgivings at first. Here are some problems I still see: -The weirdness factor will turn people off regardless of utility and efficiency. -The economic viability has yet to be established, because it's a new concept. -Will there be airflow to maintain comfort on a sunny day without compromising aerodynamics? The pods look like a little greenhouse.
It's put in the summary for shock value I think, but really what they need is mainly nitrogen (prevalent in fertilizer and also urine) and carbon dioxide. In one of their experiments they fed the algae exhaust from a generator. They could also be fed agricultural runoff rich in fertilizers, which is a problem when it reaches streams and oceans because it is so nutritious for algae that it produces algal blooms.
I'm sure you could feed your algae off of a bag of fertilizer from home depot, it's just like gardening but in water.
In commercial algae growth, the water is not standing, it is agitated. For home algae growth you may not use an agitator, but I imagine at the least you would use an air bubbler like in fish tanks to keep things mixed. And of course, by screening any openings the mosquitoes can't get in to lay eggs.
If it was only the guys at Best Buy or the people who fell for Monster Cable, I'd agree with you. But to hear someone who seemingly knows all about the technology -- well, that just baffles my brain.
It seems that some people truly believe this stuff. Though, as someone pointed out elsewhere in this thread, the placebo affect get stronger the more expensive the placebo. I'm not convinced that it's only people who don't understand the technology who fall for this -- at least they have an excuse of being duped and needing to defend their actions.
Good point, most people tend to do stupid things regardless of how smart they are in certain ways:) Hopefully they just don't waste too much money in the process...
Any sufficiently advanced scam is indistinguishable from blind ignorance.
It's pretty obvious that these cables are a scam preying on people who care about their sound systems but who don't understand enough of the technical aspects to avoid buying overpriced crap. This Stewart fellow is probably getting paid to plug this cable on his blog, but it's possible that he's just an idiot.
You lose accuracy by representing error bounds simply by the significant digits of the number. It is convention-dependent that the last sig fig is assumed to be +/- 1 (zero being assumed non-significant unless followed by a decimal point, unless the zero is already after a decimal point). That's what I remember from high school chem. And it's a convention that makes sense for, say, reading a temperature off of a thermometer. You don't know if the actual value was rounded up or down to give the instrument readout. Of course assuming that a thermometer which has 0.1 degree celsius resolution also has accuracy to 0.1 degree is a not necessarily valid, but that's another topic.
But this is an estimate of the number of books, there is no instrument being read here. This is simply their estimate with error bounds that are obviously much greater than the last significant digit. If they had said 130. million then the value would be assumed to be between 129 milling and 131 million, based on the aforementioned convention which some people use. But if their error bound is +/- 1 million for a given percent certainty then they are more accurate by saying 129,864,880 +/- 1 million than by stating 130. million, even though the two are very close.
By doing a detailed analysis of how accurately their algorithm determines the number of records based on a random sampling of records they could perhaps come up with a way to determine their error bounds. But such an analysis would probably take a great deal of effort, and I think that they just want to give us their best guess at this time.
The international editions are a completely different thing from them coming out with near-identical "new editions".
In many countries they cannot afford to buy textbooks at the price that Americans do, so the publisher will make a version that is cheaper to produce (paperback, lower quality printing) and charge less for it. The publisher profits because once they have payed for the creation, editing, typesetting, etc. they need to achieve the maximum profit with respect to production and distribution costs. They have a higher margin in the US to cover more of the up front costs of the book because customers can afford it, and they accept a lower margin overseas because it is more than they would make by selling at the US price overseas. But they cannot easily prevent its sale in the US over sites like eBay and Amazon marketplace. Is it a fair practice by the publishers? Although I think the big textbook companies are kind of evil, this practice seems reasonable to me considering the great difference in purchasing power between different nations.
As a university professor, I take exception to this.
And as a university student, I take exception to this;-)
It depends far too much on context to make this sweeping generalization that a student can read 700 pages of material in a week. I'm an engineer, and one of my hardest courses in grad school covered about 200 pages worth of textbook material over 10 weeks. One of my roommates is a controls engineer (and a very smart guy), and he can spend a week studying a single 20 page journal paper. Maybe you're simply referring to *reading* while I'm talking about *understanding*. It is possible to read 700 pages of technical material in a week, but not possible to understand it, unless it is already below your skill level.
There are courses like "Introduction to Psychology" (not to pick on the field, just the teaching methods I've seen) where all you have to do is skim the textbook and regurgitate key facts on a multiple choice test. I might have read about 50 pages a week for that class, probably in an hour or two, but I don't feel like I learned very much. And I don't feel like that's a useful way to teach a class.
700 pages/week might make sense as say an english student, where you need to read lots of novels/stories/etc but aren't writing an in-depth paper on each and every one.
So don't get arrogant and tell GP that he's just taking too many classes, because in many fields 700 pages a week is way, way too much.
Some of the best lectures I've had were from professors who are just able to go up to a chalkboard and start writing. They usually have a textbook or lecture notes handy for reference, but they understand the material well enough that they can lecture off the top of their head. Technology has nothing to do with it, it's the professors knowledge and their ability to communicate it in their lectures and (hopefully) online lecture notes.
The one "technology" thing which I think all professors should have is a course webpage which includes things like lecture notes, homework assignments, homework and test solutions, and maybe links to useful papers and other references.
I'm split on the idea of blogs. I think that lectures, lecture notes, textbooks, and office hours suffice well for learning the material. But suppose the professor has had a few people asking him the same question, maybe he will write a quick thing about it on his blog so that he doesn't need to get behind schedule by covering it again in the next lecture. But I have doubts about whether it should be an integral part of the instruction process.
The "clickers" are what they use in big lecture classes to try to force students to actually show up when the material is too easy or not interesting enough to keep the students in lecture. It's not even hard to bypass, the simple way is to ask your friend to bring your clicker in class so it looks like you're attending and responding to questions. And there are plenty of students who have hacked these devices so that one remote can act like yours and your 5 friends, or even spoofing a remote on your laptop which waits a few seconds to see what the top answer to the last question was, then selecting that one. And the remotes are expensive to boot, something like $30-50.
Videoconferencing can only alleviate the inconvenience of the professor being out of town and missing the lecture. If the professor wanted to do the best job possible, he wouldn't miss lectures. Unless it refers to the student videoconferencing in presumably because they don't live anywhere near the school, in which case they are missing out on a lot of the one-on-one interactions that make learning and exploring problems easier.
The Cydia App Store has also been around for a while, serving the jailbroken iPhone market. Of course there is not a huge number of apps on it, but there are also lots of free apps in the Cydia repository.
The reselling of books is a huge deal for me. I spend something on the order of $300/yr on books. Now most of that is for textbooks, and I get used copies from Amazon Marketplace or Half.com, for something like 70% of the list price on average. On several occasions I've bought an older edition since the market value usually drops to about $5-10 when a new edition is released. This is currently how textbook publishers fight the used book market, by frequently releasing new editions of their book with only minor changes. Now they are coming out with time-limited digital textbooks which expire after the class is over, leaving the student with nothing to resell.
The FCC has set aside 57-64GHz for high speed unlicensed wireless use. If the IEEE 802.15.3c standard is followed, then this is divided up into 4 channels.
If the efficiency of the turbine engine is indeed higher than in an internal combustion engine, then the total heat in the turbine exhaust must be less for a given amount of energy production. Otherwise it would violate conservation of energy.
There may be challenges in dealing with the exhaust if the temperature is higher, but the overall heat load on the car is reduced so that probably gives them more wiggle room.
I assume you're referring to the famous two capacitor problem, where charging an empty capacitor from a charged capacitor will always lead to 50% energy loss, once steady state is reached. The trick is that in order to reach steady state there must be loss in the system. The inefficiency applies if you use only a resistance (e.g. of wiring and a relay/switch/mosfet/whatever) to limit the current into the capacitor. If on the other hand an inductance is used to limit current then efficiency can be close to 100%.
Could you elaborate on your claim that a reciever with ~0dB noise figure can detect a signal 15 times smaller than a reciever with ~1dB noise figure? I would expect around 1dB improvement in performance. I did misspeak about that.. at room temperature the improvement would indeed be 1dB. However when receiving from a source that is very cold (eg space or a cryogenic instrument), then the 5K amplifier will get progressively better in comparison, peaking at 15 times better minimum detectable signal when dealing with a source at 0K (no noise), if such a thing were possible.
The definition of minimum detectable signal is arbitrary, unity SNR is just a convenient point since you can't detect anything below that**. You just increase the minimum signal from that point by the SNR requirement of your modulation scheme, which depends on the number and spacing of constellation points for a specific BER.
How ideal, or not ideal are the digital receivers in consumer electronics? I would assume that with modern DSP chips most things have pretty ideal receiver algorithms, but I don't really know much about signal processing.
**Coding gain is a funny thing, because unless there's more to it than I realize, all it's doing is canceling out the "coding loss" that you had at the transmitter in a spread spectrum modulating scheme. The power is spread over a wider bandwidth at transmitter, then unspread at receiver. I'm not sure it's entirely fair to call it negative SNR.. but that's really a philosophical question.
Yes... that's why I mentioned two amplifier examples both with noise temps below room temp. You did read my post, right?
70K at a few GHz is easy as pie with modern GaAs pHEMT, if you want some go to minicircuits.com. They have amps with NF=0.5dB at 2GHz at room temp going for $10. I'm not shilling for them in particular, you can buy similar amps in many places.
-174dBm/sqrt(Hz) is the minimum that you can achieve at "noise room temperature" (290 Kelvin), because that is the spectral density of noise in the RF region that a black body will emit. But every component from the antenna, antenna switch, low noise amplifier, downconverters, filters, more amplifiers, and ADC's will add a certain amount of noise to degrade the signal further. This can be discussed as noise factor, noise figure, noise temperature, and so on, but those are all also equivalent to having an increased noise floor at the signal reaching the antenna, and by converting to input referred noise floor, the minimum detectable signal is often defined as the point where the signal power equals the input referred noise power.
This will definitely NOT be the same for all phones.
A very good cryogenic low noise amplifier like astronomers use for very sensitive radio telescopes might have a noise temperature of 5 Kelvin, corresponding to an addition of -191.5dBm/root(Hz) noise power at the input. However the low noise amplifier in a cell phone probably has a noise temperature around 75 Kelvin (1dB noise figure at room temp), adding -179.7dBm/root(Hz) noise power. The first amplifier would be able to detect a signal 15 times smaller because of its superior noise performance. In fairness though it probably costs about a thousand times more...
Google is correcting their paychecks to be the same amount after taxes, because they have decided that they want to pay their employees on the basis of merit and experience, not sexual orientation. With the reduced tax withholding on a straight employee's check, it could even end up being the exact same value as a gay employee's check, assuming they make the same amount per year.
What is effectively happening is that in order to pay a fair wage to Google's employees, Google must pay a tax to the government for hiring gay people. Blame the government for enforcing this discrimination, that is the root of the problem.
A typical good videoconferencing setup already is going to cost at least a couple thousands bucks. Furthermore, a meeting with 10 people who make $60k/year is already costing $30/hr*10 = $300/hr. If the iPad like device really improves usability or provides additional utility, then the company can get a lot of value out of their investment.
We're talking about the iPad, right? Last I heard it was well over $600 for the base model.
Um, no. We're talking about the Asus E-Reader Tablet which is said to have a release price of $199. RTFT (read the fucking title) of the article if you're not sure about what's under discussion;-)
Slashdot Mirror
Well then this simply implies one should take similar precautions with Cannabis and driving that one does with Ethyl Alcohol and driving.
The problem with caffeine is that it builds a chemical dependency so that you need to drink coffee every morning just to return to your baseline level of alertness - if you drink less coffee than usual in the morning you will be more tired than usual. See this article which discusses some research asserting that a regular coffee drinker's morning coffee only counteracts their caffeine withdrawal symptoms, and that they would be just as alert in the morning without drinking coffee. So coffee really does impair you, but because drinking the coffee every morning does seem to make you more alert, it seems like it's helping you instead of hurting you. And it's a psychoactive stimulant drug, so it puts stress on your body when you consumer caffeine. Consider how many more people drink coffee than smoke marijuana, and I wouldn't be surprised if coffee in total does more damage to people's health and the economy than marijuana.
I've switched to drinking coffee only once per week, on the morning I need to get up early after also staying up late. And anecdotally I can say that I'm more energetic on the other mornings of the week now, and the one day I drink coffee it does pep me up because I'm now not dependent on the caffeine.
This is pretty reasonable to me. For example, when I search Google for the title of a book, I'm looking for the Amazon sale page at least 50% of the time. Lots of people are looking to buy stuff when they search for it on Google, and if Google arbitrarily excludes those results it would dilute the value of the search. If there are too many sales results then clarifying the search by adding or excluding certain terms will usually narrow it down enough.
What would really be interesting is if Google could distinguish between, say, commercial and non-commercial results automatically. It obviously has some capabilities in this regard with its product searching options, and if they could put in something like a (buying/not buying) check box it would mean we could find our results even faster without further clarification of search terms.
Good thoughts, but in a typical phased array receiver (which this is), the microphones will be almost equally distant from what they are sensing, because the people are much further away than the diameter of the microphone array, so the desired signal should be just as large at all receiving mics. There could be geometry considerations if they'd made the array fit on a curved surface which could be done to achieve larger scan angles, typical phased arrays work best for under 60 degrees off of normal because otherwise the power received drops too much. But from the picture this array appears to be flat.
It doesn't seem likely that the mics will distort in an ordinary environment, simply because if they could it seems to be like it would affect a large number of the microphones at once. However, it is still a possibility, and it would be interesting to see if they have a method to selectively detect such conditions and temporarily drop the affected mics, or selectively null large interfering signals coming from a particular direction.
How prescient ;-)
No, when they mention radiation in the article it's because these devices are radiation-hard, i.e. they will last a long time in a radioactive environment such as many satellites fly in. Standard silicon CMOS devices on the other hand degrade very quickly because charged particles get trapped in the gate oxide changing the gate threshold, degrading performance, and then eventually killing the device. The silicon crystal itself is more vulnerable to defects from radiation, which increases channel resistance, again degrading performance and killing the device.
The SiC MEMs devices are more robust because SiC is more robust at high temperatures and radiation filled environments, plus as a primarily mechanical system rather than electrical, it will probably be more tolerant to crystal defects.
In a computer this will emit just as much electromagnetic radiation as a silicon chip because the radiation comes from the flow of current being turned on and off. It doesn't matter one bit if you do it with a vacuum tube, BJT, MOSFET, or MEMs device, you will get electromagnetic radiation.
It may be more robust to EMP than a Si-CMOS device, but it will still be vulnerable to contact degradation when an EMP causes breakdown of the air or vacuum dielectric.
The military does love the idea of MEMs switches, more so for radar/comms, but they got burned bad after DARPA and DOD agencies funded 10's of millions, or probably more, in R&D with no useful results. The main problem with MEMs switches has always been reliability, which you will see is also a problem in the MEMs devices being promoted in this article.
They address many of these issues in the FAQ if you follow the link:
>and head-to-tail collisions would be a real problem.
There are long springy bumpers of some sort to make this impact very gentle. The energy is used to push the first driver ahead, it is not dissipated.
>And if you are moving in a chain of schweebs, there will be the inevitable lazy guy somewhere in the chain not pedaling or pretending to pedal, so someone else will do all the work.
This is a problem to an extent. However because of the high mechanical efficiency (greater than an enclosed recumbent bike they say) and the increased efficiency of moving together in a line, it will be tolerant to a certain amount of laziness without significantly increasing the work of the others. Furthermore there are monitoring sensors, and you could presumably be identified in your pod via schweeb membership card you swipe to get in the pod, and problematic riders could be penalized or banned.
>And if the schweeb capsules are publicly shared not privately owned, they'll get really, really gross and sweaty.
They say it uses 1/3 the power of walking at 5km/h (30 watts vs. 100) so even an out of shape person should not break a sweat. However I would be concerned about the sun heating them up...
>And if everybody is commuting in one direction and they are a shared public resource, all the schweebs will end up at one end of the line...
If x number of people go from point A to point B in the morning, then most of those people will go from B to A in the evening. Thus no pods pile up in any one location. Thus they just need to monitor usage and add new pods based on demand by location, plus extra to account for variability. And they will probably implement some sort of "tugboat" pod to move the pods between stations if pods start piling up in one location.
I admit I several of the same misgivings at first. Here are some problems I still see:
-The weirdness factor will turn people off regardless of utility and efficiency.
-The economic viability has yet to be established, because it's a new concept.
-Will there be airflow to maintain comfort on a sunny day without compromising aerodynamics? The pods look like a little greenhouse.
It's put in the summary for shock value I think, but really what they need is mainly nitrogen (prevalent in fertilizer and also urine) and carbon dioxide. In one of their experiments they fed the algae exhaust from a generator. They could also be fed agricultural runoff rich in fertilizers, which is a problem when it reaches streams and oceans because it is so nutritious for algae that it produces algal blooms.
I'm sure you could feed your algae off of a bag of fertilizer from home depot, it's just like gardening but in water.
In commercial algae growth, the water is not standing, it is agitated. For home algae growth you may not use an agitator, but I imagine at the least you would use an air bubbler like in fish tanks to keep things mixed. And of course, by screening any openings the mosquitoes can't get in to lay eggs.
Good point, most people tend to do stupid things regardless of how smart they are in certain ways :) Hopefully they just don't waste too much money in the process...
Any sufficiently advanced scam is indistinguishable from blind ignorance.
It's pretty obvious that these cables are a scam preying on people who care about their sound systems but who don't understand enough of the technical aspects to avoid buying overpriced crap. This Stewart fellow is probably getting paid to plug this cable on his blog, but it's possible that he's just an idiot.
You lose accuracy by representing error bounds simply by the significant digits of the number. It is convention-dependent that the last sig fig is assumed to be +/- 1 (zero being assumed non-significant unless followed by a decimal point, unless the zero is already after a decimal point). That's what I remember from high school chem. And it's a convention that makes sense for, say, reading a temperature off of a thermometer. You don't know if the actual value was rounded up or down to give the instrument readout. Of course assuming that a thermometer which has 0.1 degree celsius resolution also has accuracy to 0.1 degree is a not necessarily valid, but that's another topic.
But this is an estimate of the number of books, there is no instrument being read here. This is simply their estimate with error bounds that are obviously much greater than the last significant digit. If they had said 130. million then the value would be assumed to be between 129 milling and 131 million, based on the aforementioned convention which some people use. But if their error bound is +/- 1 million for a given percent certainty then they are more accurate by saying 129,864,880 +/- 1 million than by stating 130. million, even though the two are very close.
By doing a detailed analysis of how accurately their algorithm determines the number of records based on a random sampling of records they could perhaps come up with a way to determine their error bounds. But such an analysis would probably take a great deal of effort, and I think that they just want to give us their best guess at this time.
The international editions are a completely different thing from them coming out with near-identical "new editions".
In many countries they cannot afford to buy textbooks at the price that Americans do, so the publisher will make a version that is cheaper to produce (paperback, lower quality printing) and charge less for it. The publisher profits because once they have payed for the creation, editing, typesetting, etc. they need to achieve the maximum profit with respect to production and distribution costs. They have a higher margin in the US to cover more of the up front costs of the book because customers can afford it, and they accept a lower margin overseas because it is more than they would make by selling at the US price overseas. But they cannot easily prevent its sale in the US over sites like eBay and Amazon marketplace. Is it a fair practice by the publishers? Although I think the big textbook companies are kind of evil, this practice seems reasonable to me considering the great difference in purchasing power between different nations.
It's basically the same concept as Windows Starter Edition
And as a university student, I take exception to this ;-)
It depends far too much on context to make this sweeping generalization that a student can read 700 pages of material in a week. I'm an engineer, and one of my hardest courses in grad school covered about 200 pages worth of textbook material over 10 weeks. One of my roommates is a controls engineer (and a very smart guy), and he can spend a week studying a single 20 page journal paper. Maybe you're simply referring to *reading* while I'm talking about *understanding*. It is possible to read 700 pages of technical material in a week, but not possible to understand it, unless it is already below your skill level.
There are courses like "Introduction to Psychology" (not to pick on the field, just the teaching methods I've seen) where all you have to do is skim the textbook and regurgitate key facts on a multiple choice test. I might have read about 50 pages a week for that class, probably in an hour or two, but I don't feel like I learned very much. And I don't feel like that's a useful way to teach a class.
700 pages/week might make sense as say an english student, where you need to read lots of novels/stories/etc but aren't writing an in-depth paper on each and every one.
So don't get arrogant and tell GP that he's just taking too many classes, because in many fields 700 pages a week is way, way too much.
Some of the best lectures I've had were from professors who are just able to go up to a chalkboard and start writing. They usually have a textbook or lecture notes handy for reference, but they understand the material well enough that they can lecture off the top of their head. Technology has nothing to do with it, it's the professors knowledge and their ability to communicate it in their lectures and (hopefully) online lecture notes.
The one "technology" thing which I think all professors should have is a course webpage which includes things like lecture notes, homework assignments, homework and test solutions, and maybe links to useful papers and other references.
I'm split on the idea of blogs. I think that lectures, lecture notes, textbooks, and office hours suffice well for learning the material. But suppose the professor has had a few people asking him the same question, maybe he will write a quick thing about it on his blog so that he doesn't need to get behind schedule by covering it again in the next lecture. But I have doubts about whether it should be an integral part of the instruction process.
The "clickers" are what they use in big lecture classes to try to force students to actually show up when the material is too easy or not interesting enough to keep the students in lecture. It's not even hard to bypass, the simple way is to ask your friend to bring your clicker in class so it looks like you're attending and responding to questions. And there are plenty of students who have hacked these devices so that one remote can act like yours and your 5 friends, or even spoofing a remote on your laptop which waits a few seconds to see what the top answer to the last question was, then selecting that one. And the remotes are expensive to boot, something like $30-50.
Videoconferencing can only alleviate the inconvenience of the professor being out of town and missing the lecture. If the professor wanted to do the best job possible, he wouldn't miss lectures. Unless it refers to the student videoconferencing in presumably because they don't live anywhere near the school, in which case they are missing out on a lot of the one-on-one interactions that make learning and exploring problems easier.
The Cydia App Store has also been around for a while, serving the jailbroken iPhone market. Of course there is not a huge number of apps on it, but there are also lots of free apps in the Cydia repository.
The reselling of books is a huge deal for me. I spend something on the order of $300/yr on books. Now most of that is for textbooks, and I get used copies from Amazon Marketplace or Half.com, for something like 70% of the list price on average. On several occasions I've bought an older edition since the market value usually drops to about $5-10 when a new edition is released. This is currently how textbook publishers fight the used book market, by frequently releasing new editions of their book with only minor changes. Now they are coming out with time-limited digital textbooks which expire after the class is over, leaving the student with nothing to resell.
The FCC has set aside 57-64GHz for high speed unlicensed wireless use. If the IEEE 802.15.3c standard is followed, then this is divided up into 4 channels.
If the efficiency of the turbine engine is indeed higher than in an internal combustion engine, then the total heat in the turbine exhaust must be less for a given amount of energy production. Otherwise it would violate conservation of energy.
There may be challenges in dealing with the exhaust if the temperature is higher, but the overall heat load on the car is reduced so that probably gives them more wiggle room.
I assume you're referring to the famous two capacitor problem, where charging an empty capacitor from a charged capacitor will always lead to 50% energy loss, once steady state is reached. The trick is that in order to reach steady state there must be loss in the system. The inefficiency applies if you use only a resistance (e.g. of wiring and a relay/switch/mosfet/whatever) to limit the current into the capacitor. If on the other hand an inductance is used to limit current then efficiency can be close to 100%.
http://www.smpstech.com/charge.htm
Could you elaborate on your claim that a reciever with ~0dB noise figure can detect a signal 15 times smaller than a reciever with ~1dB noise figure? I would expect around 1dB improvement in performance.
I did misspeak about that.. at room temperature the improvement would indeed be 1dB. However when receiving from a source that is very cold (eg space or a cryogenic instrument), then the 5K amplifier will get progressively better in comparison, peaking at 15 times better minimum detectable signal when dealing with a source at 0K (no noise), if such a thing were possible.
The definition of minimum detectable signal is arbitrary, unity SNR is just a convenient point since you can't detect anything below that**. You just increase the minimum signal from that point by the SNR requirement of your modulation scheme, which depends on the number and spacing of constellation points for a specific BER.
How ideal, or not ideal are the digital receivers in consumer electronics? I would assume that with modern DSP chips most things have pretty ideal receiver algorithms, but I don't really know much about signal processing.
**Coding gain is a funny thing, because unless there's more to it than I realize, all it's doing is canceling out the "coding loss" that you had at the transmitter in a spread spectrum modulating scheme. The power is spread over a wider bandwidth at transmitter, then unspread at receiver. I'm not sure it's entirely fair to call it negative SNR.. but that's really a philosophical question.
Yes... that's why I mentioned two amplifier examples both with noise temps below room temp. You did read my post, right?
70K at a few GHz is easy as pie with modern GaAs pHEMT, if you want some go to minicircuits.com. They have amps with NF=0.5dB at 2GHz at room temp going for $10. I'm not shilling for them in particular, you can buy similar amps in many places.
You're sort of right.
-174dBm/sqrt(Hz) is the minimum that you can achieve at "noise room temperature" (290 Kelvin), because that is the spectral density of noise in the RF region that a black body will emit. But every component from the antenna, antenna switch, low noise amplifier, downconverters, filters, more amplifiers, and ADC's will add a certain amount of noise to degrade the signal further. This can be discussed as noise factor, noise figure, noise temperature, and so on, but those are all also equivalent to having an increased noise floor at the signal reaching the antenna, and by converting to input referred noise floor, the minimum detectable signal is often defined as the point where the signal power equals the input referred noise power.
This will definitely NOT be the same for all phones.
A very good cryogenic low noise amplifier like astronomers use for very sensitive radio telescopes might have a noise temperature of 5 Kelvin, corresponding to an addition of -191.5dBm/root(Hz) noise power at the input. However the low noise amplifier in a cell phone probably has a noise temperature around 75 Kelvin (1dB noise figure at room temp), adding -179.7dBm/root(Hz) noise power. The first amplifier would be able to detect a signal 15 times smaller because of its superior noise performance. In fairness though it probably costs about a thousand times more...
Google is correcting their paychecks to be the same amount after taxes, because they have decided that they want to pay their employees on the basis of merit and experience, not sexual orientation. With the reduced tax withholding on a straight employee's check, it could even end up being the exact same value as a gay employee's check, assuming they make the same amount per year.
What is effectively happening is that in order to pay a fair wage to Google's employees, Google must pay a tax to the government for hiring gay people. Blame the government for enforcing this discrimination, that is the root of the problem.
A typical good videoconferencing setup already is going to cost at least a couple thousands bucks. Furthermore, a meeting with 10 people who make $60k/year is already costing $30/hr*10 = $300/hr. If the iPad like device really improves usability or provides additional utility, then the company can get a lot of value out of their investment.
You didn't miss anything, GP did.
http://abcnews.go.com/Technology/wireStory?id=10367109
I'm not sure though if the Obama administration's proposed budget has made it through Congress yet
Um, no. We're talking about the Asus E-Reader Tablet which is said to have a release price of $199. RTFT (read the fucking title) of the article if you're not sure about what's under discussion ;-)