It turns out that gasoline is amazingly good as a fuel. When you pump it into your car, it's relatively safe. Safe enough that greasemonkeys with little-to-no education or training, hell, even the general public, can do it without much risk of explosion. But the flow rate and energy density of gasoline is such that you're moving about 3 MW of power during the fueling session.
That's the output of an electrical substation. This is not toy levels of power. If you were to try to do that with electricity, you'd need to have the equivalent of 2000 15A home circuits (think two thousand 1500 W hair blowers). If you had a 99.9% energy transfer efficiency (we think of efficient power supplies to be at the 80-85% level, so 99.9% is insanely good), that means 0.1% of 3 MW, or 3 kW of heat would need to be dissipated. Most of the energy loss would happen at the station-to-car contacts, with much of the rest in the cables. Let's be conservative and say only 1/3 of the loss is at the contacts, that's 1kW. 1kW for 5-10 minutes into anything that isn't big or actively cooled or both would get hot. Very, very hot. (Your CPU probably dissipates something in the range of 1/10th this much power.) You couldn't put your hand on it to make or break the contact, for example.
Also, the necessary levels of current will produce substantial electric and magnetic fields. Sure, cables can be well designed and shielded with both magnetic and electrical shielding, but remember that this needs to be something that a person can hold and lift and apply to their car, somehow, so weight is a consideration, too. Personally, I don't like the idea of standing next to electrical substations for any longer than necessary -- having my hand on a cable that is moving 3 MW is something I want to seriously avoid. This is not toy levels of power. Making and breaking contacts at 3 MW is non-trivial. So how about doing it inductively? I'm not standing anywhere near those fields. People are shy about being near their operating microwave ovens. That's (usually) 600 W of E/B fields that are pretty well shielded. We're talking about 4 orders of magnitude more power during refilling.
There are two realistic options. (1) Extend charging time by an order of magnitude or two. This precludes the filling-station model that we already have immense infrastructure for. (2) Instead of recharging, swap batteries for a fresh set which can be recharged at the station at a more leisurely (and less dangerous) pace.
The fundamental problem here is that gasoline is a really good fuel. It has a very high specific energy density (energy per unit volume), allowing us to become accustomed to and dependent upon the idea that refilling is a relatively quick event. Until we can change that perception, refilling all-electric cars is going to be a very difficult engineering task that borders on impossibility. So five-to-ten minute recharge times for these new batteries isn't that relevant for all-electric cars.
Maybe they used some experimental (or nonstandard) fuel...
I believe the SR-71 already uses experimental / nonstandard fuel. Certainly not AvGas or 100LL or anything remotely like that. Kerosene it ain't.
I also recall reading an analysis of SCRAMJET designs that suggested that hydrogen was the only plausible fuel since the window of time air/fuel mixture was physically within the flowstream of the engine was about 1 millisecond, and only hydrogen reacts quickly enough to provide substantial thrust.
Nobody in their right mind sues a lawyer assembly plant, coward or not...
... especially when that assembly plant has over $35 billion in liquid assets. Doubly so when it also happens to be the stomping grounds of high-profile personal-rights lawyers like Alan Dershowitz. To keep this amount of money in perspective, the Presidents and Fellows of Harvard could decide to spend less than 3% of the endowment -- not even this year's interest -- and have ONE BILLION DOLLARS to keep the RIAA in court for the next handful of decades.
No, do not disturb the 350-year-old 800-lb gorilla who has lots of friends and big piles of cash.
However, 1kw produced by an internal combustion engine in a single car is FAR less efficient than 1kw out of 100,000 produced in a central plant.
Yes, this is true, by about a factor of 2. I used to work for a company that produced some massive diesel engines (think building-filling engines running at about 100 RPM). Car engines are thought to be efficient if they hit 25%, diesel power plants routinely hit 50%. It's much easier to design an efficient engine when (a) the rotational speed (RPM) is constant, (b) the load is constant, and (c) the quality of the fuel can be tightly controlled. If you throw in cogeneration capability (to take the waste heat and use it as... heat), total efficiency can hit 80%.
There is no hydrogen economy, and hydrogen fuel is ridiculously hard to manage in compressed or liquid form.
Moreover, generating hydrogen is non-trivial. It can be generated by cracking petroleum, kind of defeating the purpose, or electrolysis of water. Cracking water's fine, except that it generates lots of oxygen and ozone. Ozone (and O2 to a lesser extent) has a nasty tendency to corrode anything it touches. We also know ozone is a major contributor of smog. Switching over to hydrogen as a fuel would release effectively equivalent amounts of O2/O3 into the atmosphere as we are currently releasing CO2. We have no idea what that will do to the climate.
I've made the very same statement about the building I worked in while I was at MIT, and the slightly disturbing malapropism is one of the things I find distinctive in people who have been part of EECS at MIT. The misstatement reflects the utter devotion and passion to the subject. Of course you don't live in the building, but your life is in that building. Ahhhh, MIT!
Unless you're actually RMS, in which case, you actually do live in the building. When the Real Time Systems group moved from the 4th floor of 545 Tech Square to the 6th, RMS moved in to my old office, Room 425. And I mean, literally, moved in. That was his domicile. Last I heard, he was similarly living in the Stata Center. Can anyone who works there confirm?
I guess you've never lived or worked in an oppressive environment, else you might not have made such a knee-jerk reaction. I have, and it clearly affected the quality and quantity of work I produced. Is that a shortcoming, or merely human nature?
I hope that people who work in the Stata Center will reply to this thread. I have many friends there, but have not, myself spent more than an occasional afternoon in the complex.
That said, there are some things that buildings, especially public buildings, should do. They should make it easy to find things, especially central, shared resources like elevators, lobbies, cafeterias, and, especially, exits. The Stata Center fails on all counts. It is difficult-to-impossible to navigate to the uninitiated and, from what people who work there tell me, it is difficult for them as well.
The interior spaces are very architecturally interesting. But have so many bugs it is unbelievable. There is one meeting room where the walls are made with perforated plywood; this is a cool idea, but, regrettably, due to the mechanisms that human vision uses to fuse the images between the two eyes, the sea of holes makes people feel queasy in that room. The workspaces are part of a grand open-office design. The previous building where LCS/AI was housed was the antithesis of open design -- a series of small offices -- and it worked very well. With the new building, researchers and students spend more of their time at home, rather than in the building, because the lack of acoustic privacy in the open design makes it extremely difficult to get any research done. In another area, there are ledges high up in one two-story space that are visible only from the story above -- kind of interesting, but these ledges will never, ever be cleaned and are starting to accumulate a goodly layer of dust. This wouldn't be so bad, except that people entering that space from the elevator lobby are immediately faced with this grime.
From what people intimately involved with the planning have told me, Geary approached the design of this building with astonishing hubris and disregard for any of the actual needs of the occupants. Interactions with him were often tense and acrimonious. Geary's willing ignorance of the real use of the building, rather than his imagined fantasy, shows. It's a cool looking structure that works very, very poorly as a research laboratory. Although few people who work there are willing to state it out loud, the rumblings are being felt that the decline of computer science research at MIT has in no small part been due to this negative influence of the building on daily worklife.
A good building will not only be easy to use, but will inspire its occupants. The old building at 545 Tech Square wasn't showy at all, but had some fantastic vistas, and a reasonably efficient use of space. (I had a series of offices in that building over the span of 14 years.) It was perhaps no accident that the basis for much of Computer Science (time-sharing operating systems, language research, the internet, high-performance compilers, distributed computation, microarchitecture, multi-processor design, speech recognition, theory, and a host of other areas) was performed there. I hope that this illustrious history will be continued in the Stata center, but am beginning to wonder if it will.
Yes, there are dozens of sites that mirror Wikipedia with ads. Actually, more like thousands, and most of those don't even bother giving any attribution. Veropedia is different. Whereas all those other sites mirror the most recent revision, Veropedia mirrors a specific revision that has been identified as good. This is where the editorial discretion and quality control come in, making it qualitatively different than other mirrors.
And yet, Veropedia will still be running ads, and therefore, will be beholden to their advertisers. Good luck, but until you have a subscription based service where you are beholden to your users instead of your advertisers, everything, but everything on Veropedia will need to be taken with a grain of salt.
The guy who didn't recognize the "Danger, Will Robinson!" was the best of the lot. I'm amazed at how clueless some people can be.
And provincial. I don't have proof, but I'm willing to wager that all manner of English-speaking folk have never seen nor even heard of "Lost in Space". Say, those from, the UK, Australia, New Zealand, India, even parts of Canada. Moreover, many people who don't come from English-speaking countries can read and write English quite well and have with even higher certainty not seen old American television shows, be those phrases part of the American social idiom or not.
On a per weight basis Aluminum is about 6 times better than gold. Gold conducts about 20% better, but weighs about 7 times as much.
And that, among other reasons like cost, is why you only use gold *plating* on connectors, and use copper alloy of one form or another for the bulk of the connector.
I don't think they do a great job of teaching it in school where they take a very linear approach.
I'm not currently a professional teacher, but I have been one, at a Big Technical University that you have heard of, for four years. My skin crawls when I hear people demeaning a linear pedagogic approach because, frankly, and you can take this as an expert opinion by someone who has won awards for teaching, there is no better way. Period. People learn depth-first by cycling down from coarser details to finer ones. They learn in steps. To quote Prof. Patrick Winston of AI fame, you only learn that which you almost already know. Trying to teach in fuzzy alternate ways, teaching by trickery, emphasizing word problems or case study, teaching two or three paths at the same time, all of that stuff does not work for technical and mathematical subjects, pure and simple.
For the basic mathematics that the original post is inquiring about, the concepts are reasonably simple and straightforward. What they require, however, is what often appears to be mind-numbing repetition. It's work. While I applaud this fellow's current initiative, the effort should have been put in when he was a teenager because it's a lot easier then. It sounds like he's understood the mistake and is currently, as an adult, trying to correct that, which is definitely commendable. Unless he's the sort of person who developed phenomenal self-discipline later in life, however, the best bet is to get to a classroom. There are any of a large number of adult education services in every city I've been to. Often local high schools will have evening adult-ed classes as well. Or, as another poster suggested, the local community college can be a good resource. But basic mathematics requires a lot of rote work. It can be a joy to know that you've learned everything that was used to get mankind to the moon, a tremendous joy in fact, but it takes work.
Anyway, the problem with trying to get some "miles per gallon" efficiency rating on computers is defining the "miles". For example, if computer A is 2 times faster and uses 1.5 times the energy compared to computer B at full load, and both computers are run at full load 8 hrs a day (doing some serious number crunching), which computer is more efficient? A is using more power, but is doing twice the amount of "work" of B. So do you measure straight Watts? Watts / MFLOPS? If you use MFLOPS, how do you account for differences in architecture?
The standard performance in business applications is database transactions per second. It should be pretty easy to publish transactions per Watt instead, for a given power use. Beyond that, for general purpose use, there are standard benchmarks already for an absolute number of operations per second on various tasks, like SPECint, SPECfloat, etc. There's no reason these too can't be normalized by power consumed, eg, SPECint/W.
Duh. A few more clicks and I would have found the answer: http://en.wikipedia.org/wiki/Free-space_loss -- the short version being that it's the diameter of receiving antenna that gives the frequency dependence.
Loss dB = 32.44 + 20 log (dist in km) + 20 log (freq in MHz)
Sorry, I've forgotten 90% of the EM I learned from 20 years ago, but I don't recall that there's a frequency dependence for transmission in vacuum. Is this the right equation to use?
I've heard of an interesting tactic used in a relatively high-profile case here in the US (use Google to search for "David LaMacchia") to prevent the divulging of decryption keys and passwords: make the court-demanded information contain the text of a confession to a crime. By engaging the US Constitution's Fifth Amendment protecting against self-incrimination, the defendant in question was successfully able to avoid divulging the pertinent data. Naturally, this strategy creates the liability of being charged with obstruction of justice, but that's potentially a far lesser crime. IANAL, and this is not legal advice, so take this information for entertainment value only.
I wish people who are trying to communicate ideas that they feel are important would take the time to abide by standard rules of communication like normal punctuation and spelling. The reason we don't, by convention, write in all lower case letters is that it makes it more difficult to read sentences that way. Communication is all, but all, about making your message easy to understand by the reader. In every modern Western written system, that includes using both upper and lower case letters. Yes, it is possible to write without them, but if your reader has only so much energy to put into understanding your words, why would you want him to spend any of it being distracted by superfluous things like unconventional orthography? The point is to communicate knowledge, not to demonstrate how clever you are; if you can communicate well, people will understand how clever you are.
And, yes, I am a scientist, and I get it. We, as scientists, have two functions: first as investigator, to create knowledge through reasoning and discovery, and second as educator, to disseminate this knowledge through the written and oral words. Many scientists give short shrift to the latter; I do not.
IAAN (I Am A Neuroscientist) who works on DBS and prostheses. The cochlear implants are considered peripheral (not central), and therefore not a part of the brain, so you really can't count the people with cochlear implants in the total numbers. But for total DBS implants there are many more than 50 patients.
Last year, I attended a confidential conference where preliminary reports from Phase-1 clinical trials of DBS to treat major depression and OCD were being discussed. The total number of patients at that point were something like 50, for MD and OCD combined. DBS for movement disorders (esp. Parkinson's) is probably in the thousands at this point. The neurosurgeon with whom I collaborate has personally performed about 130 of them, at last count, and while he's among the most experienced, there are plenty of places doing them now.
The exact mechanism through which DBS acts is still controversial. This is probably because under some circumstances (exact placement of electrodes, exact current settings and stimulation patterns, etc.) the effect is excitatory on the local neurons, and under others, the effect is inhibitory. Somewhat muddying the waters for MD is that the people who are getting electrodes implanted are refractory (non-responsive) to a large array of treatment from intensive psychotherapy through a wide range of pharmacology. Since the normal treatments aren't working, there's something especially out of whack with these early patients making the challenge of understanding mechanisms that much harder.
He was on their property when he was asked to show his receipt, but the receipt and the merchandise were his property at that point. Then a manager and an employee followed him outside the store and physically detained the car he was a passenger in.
A store has a right to protect its property and eject people from its premises. They have no rights concerning someone else's property nor their mobility. They should have written down his license plate number and let the police do the policing.
Indeed, what the store employees did amounts to unlawful detention and kidnapping. CC should be sued.
if you wash you hands a 100 times a day it is better for your skin. Ask you doctor, who has to do this.
There are periods in my professional life where I have to wash my hands many times a day for weeks on end. What works best for me is to wash with normal hand soap and immediately follow with a hand creme.
I often read blog posts about how someone could just take all their three-ounce bottles -- or take bottles from others on the plane -- and combine them into a larger container to make a bomb. I can't get into the specifics, but our explosives research shows this is not a viable option.
The logical conclusion is, therefore, that the arbitrary 3 oz volumetric limit is irrelevant (the research apparently shows this). But let's take a look at the statement anyway. It clearly can't be the container, as passengers are free to take nearly any container on board, as long as it is empty. But then, 10 people going through security at loosely the same time can easily carry 5 vials of 3 oz each, for a total combined volume of 150 oz (this is heavy enough that it requires a little thought and effort for one person to conceal). If nearly 10 pounds (a little over 4 kg) of nasty stuff isn't enough to bring down a plane, then my model of the world is completely borked, and I prefer the alternative explanation that the answers in the interview are not much more than hot air
A terrorist with 5 pounds of C4 surgically implanted in his abdomen can do far more damage than I could with the liter water bottle that TSA just made me throw away.
But there is no effective screening method for that, so we'll pretend that little problem doesn't exist.
Ever departed from the Tel Aviv airport? That, my friend, is security. Sure, they have all of the neat whizzy gizmos that TSA has (better, probably, but it's been a while since I've been through TLV), but the crux of what they do is to interrogate the passengers. Not kidding. They stop and intensely question each and every passenger and assess their motives for being there. I was on a professional trip as part of a scientific delegation, and had to not just produce documents to that effect, but demonstrate that my name was in the conference program, and give part of my talk (naturally, since the agents aren't in my particular profession, I doubt they cared about what I was saying nearly as much as how I was saying it, and whether it appeared I was demonstrating fluency in some topic). There's about 10-20 minutes of this, and it's intense. They're trying to trip you up, to find someone who has something to hide. Like motives for having had surgery to implant C4 in their abdomen, as the parent post suggests.
The part that makes this mechanism tolerable, this mechanism which provides far better security than any purely technological solution, is that they have sufficient bandwidth to process many people despite imposing a 10-20 minute delay on each. There are banks and banks of agents, not just 2 or 3 inspection booths as in the US.
You can't afford to be careless regarding the password coz you never know...
And with that, I stopped reading. Why? Because I don't have enough time to read things that aren't written in at least passable English. If someone has a good idea, and are serious about it, they'll make the effort to communicate it well or have it communicated well for them.
Nothing to see in this article, and, by strong implication, a worthless idea.
I've been thinking for a long time that CPU manufacturers could do well to promote low power chips through the following tact: take an older CPU design (say the venerable PIII) and reimplement in the newer technology. A 1GHz PIII is a reasonable CPU for every-day things like surfing the web, reading email, watching videos (with the help of an MP4 chip), and so forth. At original spec, they dissipate 35 W or so. Current-generation CPUs dissipate 2-3 times as much power, have 3-4 times as much cache, run at 2-3 times the clock rate, have memory systems 4-5 times faster, and on the whole run somewhere between 5 to 10 times faster. How about taking the massive improvements in device design, fabrication, architecture, power management, and so forth that went into these impressive achievements and re-implementing the lowly PIII 1GHz, but at 5-10W maximum power?
Nonsense. It shows that the interviewer cared about the guy's work and accomplishments, not just his alleged crimes.
I disagree. It was used to put his interviewee at ease and to build a working relationship. The journalist was just doing his job of getting his subject to open up.
Slashdot Mirror
Time to trot out this old horse again.
It turns out that gasoline is amazingly good as a fuel. When you pump it into your car, it's relatively safe. Safe enough that greasemonkeys with little-to-no education or training, hell, even the general public, can do it without much risk of explosion. But the flow rate and energy density of gasoline is such that you're moving about 3 MW of power during the fueling session.
That's the output of an electrical substation. This is not toy levels of power. If you were to try to do that with electricity, you'd need to have the equivalent of 2000 15A home circuits (think two thousand 1500 W hair blowers). If you had a 99.9% energy transfer efficiency (we think of efficient power supplies to be at the 80-85% level, so 99.9% is insanely good), that means 0.1% of 3 MW, or 3 kW of heat would need to be dissipated. Most of the energy loss would happen at the station-to-car contacts, with much of the rest in the cables. Let's be conservative and say only 1/3 of the loss is at the contacts, that's 1kW. 1kW for 5-10 minutes into anything that isn't big or actively cooled or both would get hot. Very, very hot. (Your CPU probably dissipates something in the range of 1/10th this much power.) You couldn't put your hand on it to make or break the contact, for example.
Also, the necessary levels of current will produce substantial electric and magnetic fields. Sure, cables can be well designed and shielded with both magnetic and electrical shielding, but remember that this needs to be something that a person can hold and lift and apply to their car, somehow, so weight is a consideration, too. Personally, I don't like the idea of standing next to electrical substations for any longer than necessary -- having my hand on a cable that is moving 3 MW is something I want to seriously avoid. This is not toy levels of power. Making and breaking contacts at 3 MW is non-trivial. So how about doing it inductively? I'm not standing anywhere near those fields. People are shy about being near their operating microwave ovens. That's (usually) 600 W of E/B fields that are pretty well shielded. We're talking about 4 orders of magnitude more power during refilling.
There are two realistic options. (1) Extend charging time by an order of magnitude or two. This precludes the filling-station model that we already have immense infrastructure for. (2) Instead of recharging, swap batteries for a fresh set which can be recharged at the station at a more leisurely (and less dangerous) pace.
The fundamental problem here is that gasoline is a really good fuel. It has a very high specific energy density (energy per unit volume), allowing us to become accustomed to and dependent upon the idea that refilling is a relatively quick event. Until we can change that perception, refilling all-electric cars is going to be a very difficult engineering task that borders on impossibility. So five-to-ten minute recharge times for these new batteries isn't that relevant for all-electric cars.
Maybe they used some experimental (or nonstandard) fuel ...
I believe the SR-71 already uses experimental / nonstandard fuel. Certainly not AvGas or 100LL or anything remotely like that. Kerosene it ain't.
I also recall reading an analysis of SCRAMJET designs that suggested that hydrogen was the only plausible fuel since the window of time air/fuel mixture was physically within the flowstream of the engine was about 1 millisecond, and only hydrogen reacts quickly enough to provide substantial thrust.
Nobody in their right mind sues a lawyer assembly plant, coward or not ...
... especially when that assembly plant has over $35 billion in liquid assets. Doubly so when it also happens to be the stomping grounds of high-profile personal-rights lawyers like Alan Dershowitz. To keep this amount of money in perspective, the Presidents and Fellows of Harvard could decide to spend less than 3% of the endowment -- not even this year's interest -- and have ONE BILLION DOLLARS to keep the RIAA in court for the next handful of decades.
No, do not disturb the 350-year-old 800-lb gorilla who has lots of friends and big piles of cash.
However, 1kw produced by an internal combustion engine in a single car is FAR less efficient than 1kw out of 100,000 produced in a central plant.
... heat), total efficiency can hit 80%.
Yes, this is true, by about a factor of 2. I used to work for a company that produced some massive diesel engines (think building-filling engines running at about 100 RPM). Car engines are thought to be efficient if they hit 25%, diesel power plants routinely hit 50%. It's much easier to design an efficient engine when (a) the rotational speed (RPM) is constant, (b) the load is constant, and (c) the quality of the fuel can be tightly controlled. If you throw in cogeneration capability (to take the waste heat and use it as
There is no hydrogen economy, and hydrogen fuel is ridiculously hard to manage in compressed or liquid form.
Moreover, generating hydrogen is non-trivial. It can be generated by cracking petroleum, kind of defeating the purpose, or electrolysis of water. Cracking water's fine, except that it generates lots of oxygen and ozone. Ozone (and O2 to a lesser extent) has a nasty tendency to corrode anything it touches. We also know ozone is a major contributor of smog. Switching over to hydrogen as a fuel would release effectively equivalent amounts of O2/O3 into the atmosphere as we are currently releasing CO2. We have no idea what that will do to the climate.
I live in this building.
I've made the very same statement about the building I worked in while I was at MIT, and the slightly disturbing malapropism is one of the things I find distinctive in people who have been part of EECS at MIT. The misstatement reflects the utter devotion and passion to the subject. Of course you don't live in the building, but your life is in that building. Ahhhh, MIT!
Unless you're actually RMS, in which case, you actually do live in the building. When the Real Time Systems group moved from the 4th floor of 545 Tech Square to the 6th, RMS moved in to my old office, Room 425. And I mean, literally, moved in. That was his domicile. Last I heard, he was similarly living in the Stata Center. Can anyone who works there confirm?
I guess you've never lived or worked in an oppressive environment, else you might not have made such a knee-jerk reaction. I have, and it clearly affected the quality and quantity of work I produced. Is that a shortcoming, or merely human nature?
I hope that people who work in the Stata Center will reply to this thread. I have many friends there, but have not, myself spent more than an occasional afternoon in the complex.
That said, there are some things that buildings, especially public buildings, should do. They should make it easy to find things, especially central, shared resources like elevators, lobbies, cafeterias, and, especially, exits. The Stata Center fails on all counts. It is difficult-to-impossible to navigate to the uninitiated and, from what people who work there tell me, it is difficult for them as well.
The interior spaces are very architecturally interesting. But have so many bugs it is unbelievable. There is one meeting room where the walls are made with perforated plywood; this is a cool idea, but, regrettably, due to the mechanisms that human vision uses to fuse the images between the two eyes, the sea of holes makes people feel queasy in that room. The workspaces are part of a grand open-office design. The previous building where LCS/AI was housed was the antithesis of open design -- a series of small offices -- and it worked very well. With the new building, researchers and students spend more of their time at home, rather than in the building, because the lack of acoustic privacy in the open design makes it extremely difficult to get any research done. In another area, there are ledges high up in one two-story space that are visible only from the story above -- kind of interesting, but these ledges will never, ever be cleaned and are starting to accumulate a goodly layer of dust. This wouldn't be so bad, except that people entering that space from the elevator lobby are immediately faced with this grime.
From what people intimately involved with the planning have told me, Geary approached the design of this building with astonishing hubris and disregard for any of the actual needs of the occupants. Interactions with him were often tense and acrimonious. Geary's willing ignorance of the real use of the building, rather than his imagined fantasy, shows. It's a cool looking structure that works very, very poorly as a research laboratory. Although few people who work there are willing to state it out loud, the rumblings are being felt that the decline of computer science research at MIT has in no small part been due to this negative influence of the building on daily worklife.
A good building will not only be easy to use, but will inspire its occupants. The old building at 545 Tech Square wasn't showy at all, but had some fantastic vistas, and a reasonably efficient use of space. (I had a series of offices in that building over the span of 14 years.) It was perhaps no accident that the basis for much of Computer Science (time-sharing operating systems, language research, the internet, high-performance compilers, distributed computation, microarchitecture, multi-processor design, speech recognition, theory, and a host of other areas) was performed there. I hope that this illustrious history will be continued in the Stata center, but am beginning to wonder if it will.
Yes, there are dozens of sites that mirror Wikipedia with ads. Actually, more like thousands, and most of those don't even bother giving any attribution. Veropedia is different. Whereas all those other sites mirror the most recent revision, Veropedia mirrors a specific revision that has been identified as good. This is where the editorial discretion and quality control come in, making it qualitatively different than other mirrors.
And yet, Veropedia will still be running ads, and therefore, will be beholden to their advertisers. Good luck, but until you have a subscription based service where you are beholden to your users instead of your advertisers, everything, but everything on Veropedia will need to be taken with a grain of salt.
The guy who didn't recognize the "Danger, Will Robinson!" was the best of the lot. I'm amazed at how clueless some people can be.
And provincial. I don't have proof, but I'm willing to wager that all manner of English-speaking folk have never seen nor even heard of "Lost in Space". Say, those from, the UK, Australia, New Zealand, India, even parts of Canada. Moreover, many people who don't come from English-speaking countries can read and write English quite well and have with even higher certainty not seen old American television shows, be those phrases part of the American social idiom or not.
On a per weight basis Aluminum is about 6 times better than gold. Gold conducts about 20% better, but weighs about 7 times as much.
And that, among other reasons like cost, is why you only use gold *plating* on connectors, and use copper alloy of one form or another for the bulk of the connector.
I don't think they do a great job of teaching it in school where they take a very linear approach.
I'm not currently a professional teacher, but I have been one, at a Big Technical University that you have heard of, for four years. My skin crawls when I hear people demeaning a linear pedagogic approach because, frankly, and you can take this as an expert opinion by someone who has won awards for teaching, there is no better way. Period. People learn depth-first by cycling down from coarser details to finer ones. They learn in steps. To quote Prof. Patrick Winston of AI fame, you only learn that which you almost already know. Trying to teach in fuzzy alternate ways, teaching by trickery, emphasizing word problems or case study, teaching two or three paths at the same time, all of that stuff does not work for technical and mathematical subjects, pure and simple.
For the basic mathematics that the original post is inquiring about, the concepts are reasonably simple and straightforward. What they require, however, is what often appears to be mind-numbing repetition. It's work. While I applaud this fellow's current initiative, the effort should have been put in when he was a teenager because it's a lot easier then. It sounds like he's understood the mistake and is currently, as an adult, trying to correct that, which is definitely commendable. Unless he's the sort of person who developed phenomenal self-discipline later in life, however, the best bet is to get to a classroom. There are any of a large number of adult education services in every city I've been to. Often local high schools will have evening adult-ed classes as well. Or, as another poster suggested, the local community college can be a good resource. But basic mathematics requires a lot of rote work. It can be a joy to know that you've learned everything that was used to get mankind to the moon, a tremendous joy in fact, but it takes work.
Anyway, the problem with trying to get some "miles per gallon" efficiency rating on computers is defining the "miles". For example, if computer A is 2 times faster and uses 1.5 times the energy compared to computer B at full load, and both computers are run at full load 8 hrs a day (doing some serious number crunching), which computer is more efficient? A is using more power, but is doing twice the amount of "work" of B. So do you measure straight Watts? Watts / MFLOPS? If you use MFLOPS, how do you account for differences in architecture?
The standard performance in business applications is database transactions per second. It should be pretty easy to publish transactions per Watt instead, for a given power use. Beyond that, for general purpose use, there are standard benchmarks already for an absolute number of operations per second on various tasks, like SPECint, SPECfloat, etc. There's no reason these too can't be normalized by power consumed, eg, SPECint/W.
Duh. A few more clicks and I would have found the answer: http://en.wikipedia.org/wiki/Free-space_loss -- the short version being that it's the diameter of receiving antenna that gives the frequency dependence.
Loss dB = 32.44 + 20 log (dist in km) + 20 log (freq in MHz)
Sorry, I've forgotten 90% of the EM I learned from 20 years ago, but I don't recall that there's a frequency dependence for transmission in vacuum. Is this the right equation to use?
... that includes a "Muffler Throw-Out Bearing."
Please, it's a zircon-encrusted muffler throw-out bearing!
I've heard of an interesting tactic used in a relatively high-profile case here in the US (use Google to search for "David LaMacchia") to prevent the divulging of decryption keys and passwords: make the court-demanded information contain the text of a confession to a crime. By engaging the US Constitution's Fifth Amendment protecting against self-incrimination, the defendant in question was successfully able to avoid divulging the pertinent data. Naturally, this strategy creates the liability of being charged with obstruction of justice, but that's potentially a far lesser crime. IANAL, and this is not legal advice, so take this information for entertainment value only.
I wish people who are trying to communicate ideas that they feel are important would take the time to abide by standard rules of communication like normal punctuation and spelling. The reason we don't, by convention, write in all lower case letters is that it makes it more difficult to read sentences that way. Communication is all, but all, about making your message easy to understand by the reader. In every modern Western written system, that includes using both upper and lower case letters. Yes, it is possible to write without them, but if your reader has only so much energy to put into understanding your words, why would you want him to spend any of it being distracted by superfluous things like unconventional orthography? The point is to communicate knowledge, not to demonstrate how clever you are; if you can communicate well, people will understand how clever you are.
And, yes, I am a scientist, and I get it. We, as scientists, have two functions: first as investigator, to create knowledge through reasoning and discovery, and second as educator, to disseminate this knowledge through the written and oral words. Many scientists give short shrift to the latter; I do not.
IAAN (I Am A Neuroscientist) who works on DBS and prostheses. The cochlear implants are considered peripheral (not central), and therefore not a part of the brain, so you really can't count the people with cochlear implants in the total numbers. But for total DBS implants there are many more than 50 patients.
Last year, I attended a confidential conference where preliminary reports from Phase-1 clinical trials of DBS to treat major depression and OCD were being discussed. The total number of patients at that point were something like 50, for MD and OCD combined. DBS for movement disorders (esp. Parkinson's) is probably in the thousands at this point. The neurosurgeon with whom I collaborate has personally performed about 130 of them, at last count, and while he's among the most experienced, there are plenty of places doing them now.
The exact mechanism through which DBS acts is still controversial. This is probably because under some circumstances (exact placement of electrodes, exact current settings and stimulation patterns, etc.) the effect is excitatory on the local neurons, and under others, the effect is inhibitory. Somewhat muddying the waters for MD is that the people who are getting electrodes implanted are refractory (non-responsive) to a large array of treatment from intensive psychotherapy through a wide range of pharmacology. Since the normal treatments aren't working, there's something especially out of whack with these early patients making the challenge of understanding mechanisms that much harder.
He was on their property when he was asked to show his receipt, but the receipt and the merchandise were his property at that point. Then a manager and an employee followed him outside the store and physically detained the car he was a passenger in.
A store has a right to protect its property and eject people from its premises. They have no rights concerning someone else's property nor their mobility. They should have written down his license plate number and let the police do the policing.
Indeed, what the store employees did amounts to unlawful detention and kidnapping. CC should be sued.
if you wash you hands a 100 times a day it is better for your skin. Ask you doctor, who has to do this.
There are periods in my professional life where I have to wash my hands many times a day for weeks on end. What works best for me is to wash with normal hand soap and immediately follow with a hand creme.
From the article:
I often read blog posts about how someone could just take all their three-ounce bottles -- or take bottles from others on the plane -- and combine them into a larger container to make a bomb. I can't get into the specifics, but our explosives research shows this is not a viable option.
The logical conclusion is, therefore, that the arbitrary 3 oz volumetric limit is irrelevant (the research apparently shows this). But let's take a look at the statement anyway. It clearly can't be the container, as passengers are free to take nearly any container on board, as long as it is empty. But then, 10 people going through security at loosely the same time can easily carry 5 vials of 3 oz each, for a total combined volume of 150 oz (this is heavy enough that it requires a little thought and effort for one person to conceal). If nearly 10 pounds (a little over 4 kg) of nasty stuff isn't enough to bring down a plane, then my model of the world is completely borked, and I prefer the alternative explanation that the answers in the interview are not much more than hot air
A terrorist with 5 pounds of C4 surgically implanted in his abdomen can do far more damage than I could with the liter water bottle that TSA just made me throw away.
But there is no effective screening method for that, so we'll pretend that little problem doesn't exist.
Ever departed from the Tel Aviv airport? That, my friend, is security. Sure, they have all of the neat whizzy gizmos that TSA has (better, probably, but it's been a while since I've been through TLV), but the crux of what they do is to interrogate the passengers. Not kidding. They stop and intensely question each and every passenger and assess their motives for being there. I was on a professional trip as part of a scientific delegation, and had to not just produce documents to that effect, but demonstrate that my name was in the conference program, and give part of my talk (naturally, since the agents aren't in my particular profession, I doubt they cared about what I was saying nearly as much as how I was saying it, and whether it appeared I was demonstrating fluency in some topic). There's about 10-20 minutes of this, and it's intense. They're trying to trip you up, to find someone who has something to hide. Like motives for having had surgery to implant C4 in their abdomen, as the parent post suggests.
The part that makes this mechanism tolerable, this mechanism which provides far better security than any purely technological solution, is that they have sufficient bandwidth to process many people despite imposing a 10-20 minute delay on each. There are banks and banks of agents, not just 2 or 3 inspection booths as in the US.
From the article's first paragraph:
...
You can't afford to be careless regarding the password coz you never know
And with that, I stopped reading. Why? Because I don't have enough time to read things that aren't written in at least passable English. If someone has a good idea, and are serious about it, they'll make the effort to communicate it well or have it communicated well for them.
Nothing to see in this article, and, by strong implication, a worthless idea.
I've been thinking for a long time that CPU manufacturers could do well to promote low power chips through the following tact: take an older CPU design (say the venerable PIII) and reimplement in the newer technology. A 1GHz PIII is a reasonable CPU for every-day things like surfing the web, reading email, watching videos (with the help of an MP4 chip), and so forth. At original spec, they dissipate 35 W or so. Current-generation CPUs dissipate 2-3 times as much power, have 3-4 times as much cache, run at 2-3 times the clock rate, have memory systems 4-5 times faster, and on the whole run somewhere between 5 to 10 times faster. How about taking the massive improvements in device design, fabrication, architecture, power management, and so forth that went into these impressive achievements and re-implementing the lowly PIII 1GHz, but at 5-10W maximum power?
Nonsense. It shows that the interviewer cared about the guy's work and accomplishments, not just his alleged crimes.
I disagree. It was used to put his interviewee at ease and to build a working relationship. The journalist was just doing his job of getting his subject to open up.