I and another wrote an alphametics solver in Perl in under 100 bytes. (e.g. SEND+MORE=MONEY. Each letter stands for a distinct digit. Find an assignment of digits to letters that makes the arithmetic correct.) Alas, I don't have the code to hand to post it. The basic algorithm was: (1) $x= pop @ARGV. If it is empty, quit. (2) If $x contains no letters, print it if it 'eval's to true. (3) otherwise pick a letter, and make copies of $x with that letter replaced by every digit not already in $x (unless doing so would give a number with a leading 0). Push these back onto @ARGV. (4) loop to (1).
To run, give the problem in Perl format on the command line: $ perl alphameticssolver send+more==money As it is doing an exhaustive search of up to 10! potential solutions, it takes a few minutes to run.
They aren't solving (quite) the same problem as you are. This scheme is to collect entire satellites, and prevent them from becoming debris over time. It works because you can get a really large amount of debris-to-be in one go.
Yes, with current technology, this would probably be a hopelessly expensive way of deorbiting lost gloves, bolts and pocket watches.
Re:Such systems have been proposed before
on
The Zuckerberg Tax
·
· Score: 2
What about when it all became worthless because those silly companies all dried up and blew away when people finally realized their business plans were idiotic? Is the government going to refund billions of dollar in taxes when that happens?
Yes, according to the article, they WILL refund billions of dollars in taxes when that happens. This has problems of its own, but it does answer your objection.
In all probability new life (unrelated to current life) cannot evolve on Earth because current life either prevents the required conditions (eating the food before it gets concentrated enough for extremely primitive life to make use of it) or out competing the new life as soon as it arises.
If somehow the Earth were cleansed of all life but otherwise left unaffected, there is no great reason to believe it couldn't re-evolve life. However, as we don't understand the origin of life, there is a possibility that necessary conditions are no longer available - e.g. early life relies critically on the presence of a radioactive nucleotide with half-life of a few hundred million years, present in the early Earth but now decayed.
We find evidence of life in pretty much the oldest rocks on Earth which could contain evidence of life. So in the only instance we can study, life arose about as soon as it possibly could have. This suggests (but does not prove) that given the right conditions, evolution of life is an easy step, rather than one which requires a once-in-a-trillion-years fluke occurance.
However, unicellular life was around for some 2.5 to 3 billion years before multicellular life arose (or at least, multicellular life which left fossil evidence.) This suggests that the step from unicellular to multicellular is hard. Or so I've argued, until this result turned up...
So, we have this result, and the fact that multicellularity has arisen multiple times, and although only in Eukaryotes, it has arisen in very distantly related Eukaryotes (plants vs the fungi/animal clade) suggesting that multicellularity is fairly easy to evolve. So why did it take so long? Perhaps it required a certain level of atmospheric oxygen before multicellular life was viable (plot.)
(I have only tangential professional connection to these topics, so these are merely semi-educated ramblings.)
Don't take it for granted that the EASA will do the right thing. The FCC didn't in response to the Windsor incident, thus failing to prevent the, at the time, worst ever airliner crash.
Having said that, I'm not going to get worried about this until I see a number of independent aviation engineers getting worried. Your comment on the consensus of aviation industry forums is reassuring.
Like it or not, there is, and must be, a price on human life. "But it could kill people!" isn't sufficient reason in itself to ground the A380 - the risks and costs must be balanced.
Pulling some numbers out of the air, for argument's sake this problem has a 10% chance of one day causing a crash, which will kill 400 people, and killing the A380 will cost $20 billion. That is $20 billion to save, on average, 40 lives, or $500 million per life. You could instead tax Airbus more heavily for $500 million, and put the money into a branch of health care which on average saves one person per $500,000. The economy is $19.5 billion better off and the population is 960 people better off, by letting the 380 keep flying despite the fact that "it might kill people".
You even place a value on your own life. Do you own and habitually wear a bullet proof vest? Do you wear a crash helmet when driving? Do you buy a new vehicle every year with safety features almost entirely dictating your choice? If not, it is because you value money (and other benefits such as comfort and avoiding ridicule) over slight reductions in your chance of an early death.
(Note: I don't know the risk/benefit numbers for the specific case of the A380 cracks. I'm saying this analysis is grossly inadequate to justify grounding the A380, not that it shouldn't be grounded.)
But it does not follow from this that this proposed spending will efficiently remedy a lack of computer literacy in the students. That requires that students lack computer literacy now, that the spending will fix this, and that it will do so at reasonable cost.
I'm too removed from this situation to make a judgement, but the views of the teachers deserve careful consideration.
747-400 engines have thrust between 265 and 282 kN (depending on engine model). 777 engines have thrust between 338 and 514 kN. You can get more thrust out of four 777 engines than you can six 747 engines. The design has a high wing, so engine diameter isn't an issue. Why use six engines instead of four?
(A330 and A380 engines have only a small advantage over 747, at 310-320 kN.)
The 747-400 has been around 6 more years than the 777, and 747-300 much longer again. Maybe they can get six used 747 engines much cheaper than four used 777 engines. As a low-usage aircraft, it makes sense to have increased maintenance costs if it saves enough on capital costs.
No, it wasn't living conditions. For avian flu, it is because it isn't very contagious to people. For swine flu, it just wasn't any more deadly than ordinary flu (even in places where living conditions are poor.)
If any state out there wants to pay top dollar for a nuclear scientist who'll tell them all about s process nucleosynthesis while asking no questions about what the knowledge will be used for, for a 10% finder's fee I may be able to put you in touch with someone.
It was looking awesome until I saw the close up, where horribly misuse Greek letters according to their coincidental resemblance to Roman letters. They use a Lambda instead of an "A"! ARRRRRGHH! I'd hate myself for having that on my wrist.
I read that sentence quite differently to you. To me it said "The CEOs have a strong tendency to band together and protect each other, yet Fiorina's incompetence is so great that it overcomes this tendency." I.e. no sexism and agreeing with you. If my reading is correct, "good ol' boys club" is an unfortunate phrase to use, as it allows your interpretation.
No. The resonance (physical size) of the cavity controls the color; it doesn't depend upon how many layers are in there. The resonance size controls the wavelength which is most strongly reflected. The number of layers controls how sharp that peak is.
An LCD is a very different situation, as an LCD emits its own light. The interferometric display only reflects incident light. We judge the whiteness of an object by how much it reflects compared to other things (so that we don't get misled by changes in ambient illumination) so if anything truly white is visible near the display, I would still expect the display to appear grey. (Actually, anything which is brighter at any wavelength than your 'white' surface I think will do it.)
No. Each pixel holds many elements.
OK, so there are very many very small subpixels - which is (nearly) what I said would be needed to avoid dithering. So they've solved that problem by the brute force approach.
You might be right, but I'm not sure. This isn't like ink, where you can put two inks on the same place and have each subtract different colours. However, the point I'm trying to make works equally well if it is a CMY(K) colour scheme. The colour response will not be highly specific, so you won't be able to display pure colours.
As described, I'd expect poor image quality for three independent reasons.
First, the cavities have just two reflecting surfaces. The interference design may work wonders on butterfly wings, but they have many reflective layers, not just two. With just two, the wavelength specificity of the reflected light will be poor: you won't be able to make a bright green spot, merely a greenish spot.
Second, each subpixel can reflect only a particular colour (presumably they'll go for red, green and blue subpixels.) So if for a pixel all the subpixels are turned on, than means that 1/3 of the red light falling on the pixel will be reflected (i.e. from the red subpixel), 1/3 of the green light, and 1/3 of the blue light. This means that if we try to set the pixel as bright as possible (all subpixels on) we'll still only get a medium grey, not white.
Third, each subpixel is either on or off, so each pixel can only display 8 colours. To get better colour reproduction will require dithering, which requires very many very small pixels to not visibly affect image quality.
So, from the description I'm expecting a greyish display with washed out dithered colours. The tiny photo they include in the article shows considerably better quality than I'm expecting. (I really want to see a close up, high quality photo of the display showing a challenging image.) Are there reasons why my objections above are not valid?
Two things: The one nearly ready is a new distance formula suitable for binary characters which evolve by a Dollo process, which (among other things) is suitable for DArT (diversity array technology) data. The other one, I'm more of a junior author, but it involves group theory, models of DNA evolution, and finding models such that if the model parameters vary with time, the overall process is still within the model. To give a counter example: generate two Markov matrices for the GTR model, with different parameters. Multiply them together (as would happen if your sequence evolves for a while under one model, and then evolves under the other.) The resulting composite Markov matrix will not (in general) be a GTR Markov matrix. We're looking at models which do not suffer this 'defect'. The senior authors have developed the models, but I'm implementing them to see how they go on real world data. The opening salvo of this project is http://arxiv.org/pdf/1105.4680.
I wrote software as part of my Ph.D. that is now distributed world wide. I guarantee you've never heard of it - it sets the standard for how to do certain types of phylogenetic analysis, but almost no one does that analysis.
Given that right now I'm writing* proof-of-concept code for phylogenetic analysis, I might have. Would you care to be more specific?
I've got a paper nearing submission on how to best phylogenetically analyse data generated by a method which nearly no one uses.
* or more accurately, procrastinating from writing
And how much space and air conditioning do you have? Depending on the answers do these questions, the optimal* solution might be 'get a bunch of 5 year old computers nearly for free.'
* Optimal for your friend, not for her university.
Slashdot Mirror
I and another wrote an alphametics solver in Perl in under 100 bytes. (e.g. SEND+MORE=MONEY. Each letter stands for a distinct digit. Find an assignment of digits to letters that makes the arithmetic correct.) Alas, I don't have the code to hand to post it. The basic algorithm was:
(1) $x= pop @ARGV. If it is empty, quit.
(2) If $x contains no letters, print it if it 'eval's to true.
(3) otherwise pick a letter, and make copies of $x with that letter replaced by every digit not already in $x (unless doing so would give a number with a leading 0). Push these back onto @ARGV.
(4) loop to (1).
To run, give the problem in Perl format on the command line:
$ perl alphameticssolver send+more==money
As it is doing an exhaustive search of up to 10! potential solutions, it takes a few minutes to run.
I'm sorry, but I'm going to burst your bubble with a single word: griefers.
They aren't solving (quite) the same problem as you are. This scheme is to collect entire satellites, and prevent them from becoming debris over time. It works because you can get a really large amount of debris-to-be in one go.
Yes, with current technology, this would probably be a hopelessly expensive way of deorbiting lost gloves, bolts and pocket watches.
What about when it all became worthless because those silly companies all dried up and blew away when people finally realized their business plans were idiotic? Is the government going to refund billions of dollar in taxes when that happens?
Yes, according to the article, they WILL refund billions of dollars in taxes when that happens. This has problems of its own, but it does answer your objection.
In all probability new life (unrelated to current life) cannot evolve on Earth because current life either prevents the required conditions (eating the food before it gets concentrated enough for extremely primitive life to make use of it) or out competing the new life as soon as it arises.
If somehow the Earth were cleansed of all life but otherwise left unaffected, there is no great reason to believe it couldn't re-evolve life. However, as we don't understand the origin of life, there is a possibility that necessary conditions are no longer available - e.g. early life relies critically on the presence of a radioactive nucleotide with half-life of a few hundred million years, present in the early Earth but now decayed.
We find evidence of life in pretty much the oldest rocks on Earth which could contain evidence of life. So in the only instance we can study, life arose about as soon as it possibly could have. This suggests (but does not prove) that given the right conditions, evolution of life is an easy step, rather than one which requires a once-in-a-trillion-years fluke occurance.
However, unicellular life was around for some 2.5 to 3 billion years before multicellular life arose (or at least, multicellular life which left fossil evidence.) This suggests that the step from unicellular to multicellular is hard. Or so I've argued, until this result turned up...
So, we have this result, and the fact that multicellularity has arisen multiple times, and although only in Eukaryotes, it has arisen in very distantly related Eukaryotes (plants vs the fungi/animal clade) suggesting that multicellularity is fairly easy to evolve. So why did it take so long? Perhaps it required a certain level of atmospheric oxygen before multicellular life was viable (plot.)
(I have only tangential professional connection to these topics, so these are merely semi-educated ramblings.)
But now you can waterproof the rest of your guitar so you can play electric guitar in the shower! [NSFW]
Don't take it for granted that the EASA will do the right thing. The FCC didn't in response to the Windsor incident, thus failing to prevent the, at the time, worst ever airliner crash.
Having said that, I'm not going to get worried about this until I see a number of independent aviation engineers getting worried. Your comment on the consensus of aviation industry forums is reassuring.
Like it or not, there is, and must be, a price on human life. "But it could kill people!" isn't sufficient reason in itself to ground the A380 - the risks and costs must be balanced.
Pulling some numbers out of the air, for argument's sake this problem has a 10% chance of one day causing a crash, which will kill 400 people, and killing the A380 will cost $20 billion. That is $20 billion to save, on average, 40 lives, or $500 million per life. You could instead tax Airbus more heavily for $500 million, and put the money into a branch of health care which on average saves one person per $500,000. The economy is $19.5 billion better off and the population is 960 people better off, by letting the 380 keep flying despite the fact that "it might kill people".
You even place a value on your own life. Do you own and habitually wear a bullet proof vest? Do you wear a crash helmet when driving? Do you buy a new vehicle every year with safety features almost entirely dictating your choice? If not, it is because you value money (and other benefits such as comfort and avoiding ridicule) over slight reductions in your chance of an early death.
(Note: I don't know the risk/benefit numbers for the specific case of the A380 cracks. I'm saying this analysis is grossly inadequate to justify grounding the A380, not that it shouldn't be grounded.)
How on earth does this get to be a criminal offense rather than civil one?
Did they acquire rights from the families of the celebrities as well as from the photographers? If not, they're still hypocritical.
But it does not follow from this that this proposed spending will efficiently remedy a lack of computer literacy in the students. That requires that students lack computer literacy now, that the spending will fix this, and that it will do so at reasonable cost.
I'm too removed from this situation to make a judgement, but the views of the teachers deserve careful consideration.
747-400 engines have thrust between 265 and 282 kN (depending on engine model). 777 engines have thrust between 338 and 514 kN. You can get more thrust out of four 777 engines than you can six 747 engines. The design has a high wing, so engine diameter isn't an issue. Why use six engines instead of four?
(A330 and A380 engines have only a small advantage over 747, at 310-320 kN.)
The 747-400 has been around 6 more years than the 777, and 747-300 much longer again. Maybe they can get six used 747 engines much cheaper than four used 777 engines. As a low-usage aircraft, it makes sense to have increased maintenance costs if it saves enough on capital costs.
And then we can sue anyone who catches the disease for patent infringement!
What stopped it from being just as deadly?
No, it wasn't living conditions. For avian flu, it is because it isn't very contagious to people. For swine flu, it just wasn't any more deadly than ordinary flu (even in places where living conditions are poor.)
Why is the Secret Service involved? This doesn't seem to involve currency or protection of VIPs.
If any state out there wants to pay top dollar for a nuclear scientist who'll tell them all about s process nucleosynthesis while asking no questions about what the knowledge will be used for, for a 10% finder's fee I may be able to put you in touch with someone.
It was looking awesome until I saw the close up, where horribly misuse Greek letters according to their coincidental resemblance to Roman letters. They use a Lambda instead of an "A"! ARRRRRGHH! I'd hate myself for having that on my wrist.
I read that sentence quite differently to you. To me it said "The CEOs have a strong tendency to band together and protect each other, yet Fiorina's incompetence is so great that it overcomes this tendency." I.e. no sexism and agreeing with you. If my reading is correct, "good ol' boys club" is an unfortunate phrase to use, as it allows your interpretation.
No. The resonance (physical size) of the cavity controls the color; it doesn't depend upon how many layers are in there.
The resonance size controls the wavelength which is most strongly reflected. The number of layers controls how sharp that peak is.
An LCD is a very different situation, as an LCD emits its own light. The interferometric display only reflects incident light. We judge the whiteness of an object by how much it reflects compared to other things (so that we don't get misled by changes in ambient illumination) so if anything truly white is visible near the display, I would still expect the display to appear grey. (Actually, anything which is brighter at any wavelength than your 'white' surface I think will do it.)
No. Each pixel holds many elements.
OK, so there are very many very small subpixels - which is (nearly) what I said would be needed to avoid dithering. So they've solved that problem by the brute force approach.
You might be right, but I'm not sure. This isn't like ink, where you can put two inks on the same place and have each subtract different colours. However, the point I'm trying to make works equally well if it is a CMY(K) colour scheme. The colour response will not be highly specific, so you won't be able to display pure colours.
As described, I'd expect poor image quality for three independent reasons.
First, the cavities have just two reflecting surfaces. The interference design may work wonders on butterfly wings, but they have many reflective layers, not just two. With just two, the wavelength specificity of the reflected light will be poor: you won't be able to make a bright green spot, merely a greenish spot.
Second, each subpixel can reflect only a particular colour (presumably they'll go for red, green and blue subpixels.) So if for a pixel all the subpixels are turned on, than means that 1/3 of the red light falling on the pixel will be reflected (i.e. from the red subpixel), 1/3 of the green light, and 1/3 of the blue light. This means that if we try to set the pixel as bright as possible (all subpixels on) we'll still only get a medium grey, not white.
Third, each subpixel is either on or off, so each pixel can only display 8 colours. To get better colour reproduction will require dithering, which requires very many very small pixels to not visibly affect image quality.
So, from the description I'm expecting a greyish display with washed out dithered colours. The tiny photo they include in the article shows considerably better quality than I'm expecting. (I really want to see a close up, high quality photo of the display showing a challenging image.) Are there reasons why my objections above are not valid?
Two things: The one nearly ready is a new distance formula suitable for binary characters which evolve by a Dollo process, which (among other things) is suitable for DArT (diversity array technology) data. The other one, I'm more of a junior author, but it involves group theory, models of DNA evolution, and finding models such that if the model parameters vary with time, the overall process is still within the model. To give a counter example: generate two Markov matrices for the GTR model, with different parameters. Multiply them together (as would happen if your sequence evolves for a while under one model, and then evolves under the other.) The resulting composite Markov matrix will not (in general) be a GTR Markov matrix. We're looking at models which do not suffer this 'defect'. The senior authors have developed the models, but I'm implementing them to see how they go on real world data. The opening salvo of this project is http://arxiv.org/pdf/1105.4680.
I wrote software as part of my Ph.D. that is now distributed world wide. I guarantee you've never heard of it - it sets the standard for how to do certain types of phylogenetic analysis, but almost no one does that analysis.
Given that right now I'm writing* proof-of-concept code for phylogenetic analysis, I might have. Would you care to be more specific?
I've got a paper nearing submission on how to best phylogenetically analyse data generated by a method which nearly no one uses.
* or more accurately, procrastinating from writing
Their 'power saving' bar chart has gratuitously chopped off the bottom 20% of the graph.
And how much space and air conditioning do you have? Depending on the answers do these questions, the optimal* solution might be 'get a bunch of 5 year old computers nearly for free.'
* Optimal for your friend, not for her university.