No. For typically levels of undersampling CS reconstructs the image perfectly. Yes, it's not exactly intuitive, but it does work.
Re:I am a bit worried about the "fill in the shape
on
Recovering Data From Noise
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· Score: 2, Insightful
The description of the algorithm in the article is quite poor. To reconstruct an MR image you effectively model it with wavelet basis functions, subject to someconstraints: a) the wavelet domain should be as sparse as possible, b) the Fourier coefficients you actually acquired (MR is acquired in the Fourier domain, not the image domain) have to match and usually c) the image should be real. You often also require that the total variation of the image should be as low as possible as well.
Since the image is acquired in the Fourier domain, every measurement you make contains information about all the pixels in the image. For reasonable* under acquisitions CS can produce a perfectly reconstructed image.
* the exact limits of "reasonable" are still under investigation, but typically you only need to acquire about a quarter of the data to be pretty much guaranteed you'll be able to get a perfect reconstruction.
Seriously, watching a CS reconstruction is actually visually more impressive than what they do on CS. I coded up a demo and everyone calls it the magic algorithm.
The poster asked why a 20 year payback period is a problem for PV systems. We're not talking about systems with a payback time of less than 20 years.
Warranties usually specify that the system will operate at some fraction of it's rated capacity after a certain amount of time. If your PV system is warranted to 80% after 20 years, your profit is going to be quite a bit less than you might hope since it is entirely generated by the less-than-peak-performance you get later in the system's life.
Everywhere I've lived the snow conditions you're likely to be slamming your brakes in are either hard packed (no advantage to no ABS) or over the ground clearance of your car anyway.
Gravel is another story. I've got a friend in the oilfield and they specifically teach them braking methods that disable the ABS for stopping in gravel. The techniques aren't really any harder than proper threshold braking and you get the best of both worlds.
Because if the solar panels only last for 20 years (optimistically) and it takes 20 years to recoup the cost, you're not getting anywhere. Nuclear plants and hydro dams are built to last a good bit longer than their break even time.
Nothing rules out that microwave towers can cause cancer. The key is to figure out whether the risk is worth worrying about or not.
We don't generally worry about light bulbs, yet the physics tells us that a light bulb is considerably more likely to be dangerous than the situation the poster is describing. Experiments also tend to support this conclusion.
Does that mean that certain frequencies of RF don't behave in a very special and unprecedented way? Not at all. But the chances of that are small. Even if they do, which frequencies are they? The ones that happen to be emitted by your cell phone? That would be quite the coincidence, wouldn't it?
Remember, the sunlight is a billion times stronger than his likely exposure to the RF.
For a more realistic test, expose yourself to the light from a 30 W incandescent bulb 24/7. It's still many times what you're likely to be getting from a cell tower. Most of us do at least this without even thinking about it.
Oh, and living in Manhattan is probably far worse for your health than anything a measly cell phone tower is going to do to you.
I hope you're wrong on that one. A scientific group should know better.
The problem is not so much that the mistake was made, but how it was made and the reaction when it was discovered. There shouldn't be any dependence on unreviewed work ("grey literature" - just call it what it is). Worse, when the mistake was pointed out the reaction wasn't "yeah, that doesn't sound right... oh yeah, should be 2350," it was "well of course it's right, what are you, a denier?"
If we're to trust the IPCC they have to maintain higher standards than the "we are right because we are right" campaigners on BOTH sides.
I'm not confused, but you've obviously got a pretty strong political agenda. This is a scientific issue. The gray literature supports BOTH "camps." That's because anybody who wants to can write it. Elements of both sides would also like to have it treated as some kind of evidence. From members of the non-scientific community that's not really surprising. From members of the scientific community it is.
A little mistake is fine. Referencing a WWF report is not a little mistake. Arguing that "gray literature" is required to get an accurate picture basically blows your credibility.
In "The Fabric of the Cosmos" Brian Greene addresses that argument for the arrow of time. It quickly leads to all sorts of problems. Sure, it might be true that the past is a fabrication but it's not a very productive assumption.
The screen is glass because glass is much more scratch resistant than plastic is. Yes, for people who let their 2 year olds throw their phones around that might not be ideal, but for everybody else it's quite a nice feature.
"it likely won't catch on among more technical audiences"
I agree with you on everything else, but I'm not sure on that one. Just like the iPhone, the iPad might just find a lot of techie uses.
I'm looking forward to having one to carry around a library of technical and academic texts (can't do that on an e-reader because they don't do graphics well and don't have colour). It might also be good for some SSH work. I actually SSH from my iPhone quite a bit but both the keyboard and the screen are a bit too small to make it really convenient.
Writing a report/essay - a PITA on a netbook. The keyboard and screen are too small. Yeah, you can do it, but it's not nice. Just use a proper computer. Most people don't need highly mobile means to write reports and essays.
Stats - most people never do stats, but I don't see why you couldn't use an iPad to do just as well or better.
PDF annotation - that's going to be a serious winner on a tablet over a netbook.
SSH to a more powerful computer - again, a very niche task falling perfectly into the GPs category 1.
Change "magic" to interface. I think they might be right.
A netbook is a crappy laptop. An iPad is an even crappier laptop.
A netbook is a crappy web browser, book reader, light productivity/e-mail/Facebook/IM/whatever device. An iPad... maybe a pretty decent web browser, book reader, light productivity/e-mail/Facebook/IM/whatever device.
If you want to write a bunch of code, write a novel or do some heavy duty spreadsheet stuff you'd but nuts to buy an iPad and only slightly less nuts to buy a netbook - you need to get a laptop or desktop. But if you want to read a novel or show off a spreadsheet at a meeting, maybe an iPad is just what you need.
So what you're saying is that you can't maintain control over your own computers and your neighbor is the dumbass?
If you really really couldn't convince your wife's laptop not to connect to random aps you need to get it fixed, replace it, or use an OS without such serious bugs.
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No. For typically levels of undersampling CS reconstructs the image perfectly. Yes, it's not exactly intuitive, but it does work.
The description of the algorithm in the article is quite poor. To reconstruct an MR image you effectively model it with wavelet basis functions, subject to someconstraints: a) the wavelet domain should be as sparse as possible, b) the Fourier coefficients you actually acquired (MR is acquired in the Fourier domain, not the image domain) have to match and usually c) the image should be real. You often also require that the total variation of the image should be as low as possible as well.
Since the image is acquired in the Fourier domain, every measurement you make contains information about all the pixels in the image. For reasonable* under acquisitions CS can produce a perfectly reconstructed image.
* the exact limits of "reasonable" are still under investigation, but typically you only need to acquire about a quarter of the data to be pretty much guaranteed you'll be able to get a perfect reconstruction.
Seriously, watching a CS reconstruction is actually visually more impressive than what they do on CS. I coded up a demo and everyone calls it the magic algorithm.
The poster asked why a 20 year payback period is a problem for PV systems. We're not talking about systems with a payback time of less than 20 years.
Warranties usually specify that the system will operate at some fraction of it's rated capacity after a certain amount of time. If your PV system is warranted to 80% after 20 years, your profit is going to be quite a bit less than you might hope since it is entirely generated by the less-than-peak-performance you get later in the system's life.
On SOFT snow.
Everywhere I've lived the snow conditions you're likely to be slamming your brakes in are either hard packed (no advantage to no ABS) or over the ground clearance of your car anyway.
Gravel is another story. I've got a friend in the oilfield and they specifically teach them braking methods that disable the ABS for stopping in gravel. The techniques aren't really any harder than proper threshold braking and you get the best of both worlds.
Molecules are pretty huge in terms of quantum mechanics.
Because if the solar panels only last for 20 years (optimistically) and it takes 20 years to recoup the cost, you're not getting anywhere. Nuclear plants and hydro dams are built to last a good bit longer than their break even time.
Nothing rules out that microwave towers can cause cancer. The key is to figure out whether the risk is worth worrying about or not.
We don't generally worry about light bulbs, yet the physics tells us that a light bulb is considerably more likely to be dangerous than the situation the poster is describing. Experiments also tend to support this conclusion.
Does that mean that certain frequencies of RF don't behave in a very special and unprecedented way? Not at all. But the chances of that are small. Even if they do, which frequencies are they? The ones that happen to be emitted by your cell phone? That would be quite the coincidence, wouldn't it?
Remember, the sunlight is a billion times stronger than his likely exposure to the RF.
For a more realistic test, expose yourself to the light from a 30 W incandescent bulb 24/7. It's still many times what you're likely to be getting from a cell tower. Most of us do at least this without even thinking about it.
Oh, and living in Manhattan is probably far worse for your health than anything a measly cell phone tower is going to do to you.
"uses almost no gray literature"
I hope you're wrong on that one. A scientific group should know better.
The problem is not so much that the mistake was made, but how it was made and the reaction when it was discovered. There shouldn't be any dependence on unreviewed work ("grey literature" - just call it what it is). Worse, when the mistake was pointed out the reaction wasn't "yeah, that doesn't sound right... oh yeah, should be 2350," it was "well of course it's right, what are you, a denier?"
If we're to trust the IPCC they have to maintain higher standards than the "we are right because we are right" campaigners on BOTH sides.
I'm not confused, but you've obviously got a pretty strong political agenda. This is a scientific issue. The gray literature supports BOTH "camps." That's because anybody who wants to can write it. Elements of both sides would also like to have it treated as some kind of evidence. From members of the non-scientific community that's not really surprising. From members of the scientific community it is.
Sure, but it's a lot better than just believing anything somebody at the WWF decides to write.
A little mistake is fine. Referencing a WWF report is not a little mistake. Arguing that "gray literature" is required to get an accurate picture basically blows your credibility.
In "The Fabric of the Cosmos" Brian Greene addresses that argument for the arrow of time. It quickly leads to all sorts of problems. Sure, it might be true that the past is a fabrication but it's not a very productive assumption.
The screen is glass because glass is much more scratch resistant than plastic is. Yes, for people who let their 2 year olds throw their phones around that might not be ideal, but for everybody else it's quite a nice feature.
Is that anything like delta radiation? A tachyon field? The omega particle?
I also like this, from the summary: "the highest legal levels." Hm.
"iPad (hate that name)"
You're right. It should have been iPadd.
You can use any bluetooth keyboard you want, unjailbroken.
"it likely won't catch on among more technical audiences"
I agree with you on everything else, but I'm not sure on that one. Just like the iPhone, the iPad might just find a lot of techie uses.
I'm looking forward to having one to carry around a library of technical and academic texts (can't do that on an e-reader because they don't do graphics well and don't have colour). It might also be good for some SSH work. I actually SSH from my iPhone quite a bit but both the keyboard and the screen are a bit too small to make it really convenient.
Writing a report/essay - a PITA on a netbook. The keyboard and screen are too small. Yeah, you can do it, but it's not nice. Just use a proper computer. Most people don't need highly mobile means to write reports and essays.
Stats - most people never do stats, but I don't see why you couldn't use an iPad to do just as well or better.
PDF annotation - that's going to be a serious winner on a tablet over a netbook.
SSH to a more powerful computer - again, a very niche task falling perfectly into the GPs category 1.
Change "magic" to interface. I think they might be right.
A netbook is a crappy laptop. An iPad is an even crappier laptop.
A netbook is a crappy web browser, book reader, light productivity/e-mail/Facebook/IM/whatever device. An iPad... maybe a pretty decent web browser, book reader, light productivity/e-mail/Facebook/IM/whatever device.
If you want to write a bunch of code, write a novel or do some heavy duty spreadsheet stuff you'd but nuts to buy an iPad and only slightly less nuts to buy a netbook - you need to get a laptop or desktop. But if you want to read a novel or show off a spreadsheet at a meeting, maybe an iPad is just what you need.
It's all fun and games until you (a) take your notebook outside the house or (b) have a neighbour who figures out how to set the admin password.
So what you're saying is that you can't maintain control over your own computers and your neighbor is the dumbass?
If you really really couldn't convince your wife's laptop not to connect to random aps you need to get it fixed, replace it, or use an OS without such serious bugs.
Yes, because people do their best work fresh out of the womb without exposure to anything else in their field of endeavour. Mozart, for example, didn't study music at all, and his father wasn't a music director and teacher.
Free neutrons. Better?