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Scientists Develop Solar Cell That Can Also Emit Light

Soulskill posted about 6 months ago | from the bidirectional-photon-technology dept.

Power 79

An anonymous reader writes: "Scientists at the Nanyang Technological University have developed a solar cell that not only converts sunlight into electricity but also emits light as electricity passes through it. Tuning the composition of the solar cell enables it to emit different wavelengths of light (abstract), and because it is only about 1 micrometer thick, the material is semi-translucent and therefore could potentially be used in windows. The solar cell is comprised of the semiconducting mineral perovskite, which has been studied as a replacement for silicon in solar panels since 2009. Perovskite solar cells are not yet as efficient at energy conversion as silicon solar cells, but gains in this area of development coupled with cheaper manufacturing costs (10-20 cents per watt projected as opposed to 75 cents per watt with silicon solar panels and 50 cents per watt with fossil fuels) make perovskite a popular subject matter in the solar cell industry."

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Heinlein? (3, Interesting)

Cpt_Kirks (37296) | about 6 months ago | (#46577499)

Didn't Heinlein come up with a similar concept? In the story with the moving roads?

Re: Heinlein? (1)

Quila (201335) | about 6 months ago | (#46577739)

The book was Friday.

Re: Heinlein? (3, Informative)

Bill_the_Engineer (772575) | about 6 months ago | (#46577767)

Actually it was a short story called "Let there be light!" published in May 1940. Friday was published in 1982.

Re: Heinlein? (1)

Quila (201335) | about 6 months ago | (#46586443)

Must be one of Heinlein's recurring themes.

Re: Heinlein? (0)

Anonymous Coward | about 6 months ago | (#46578353)

Gotta get down on Friday.

Re: Heinlein? (3, Insightful)

Alomex (148003) | about 6 months ago | (#46577919)

And/ I can come up with a concept in a novel about a very clean, efficient family car that spits into four when needed and rejoins into one when going for vacation.

That took a minute of my time. Still the entire credit would go to whoever actually built such contraption.

Re: Heinlein? (0)

Anonymous Coward | about 6 months ago | (#46581299)

> And/ I can come up with a concept in a novel about a very clean, efficient family car that spits into four when needed and rejoins into one when going for vacation.

Stan Lee beat you to it by over 50 years.

http://en.wikipedia.org/wiki/F... [wikipedia.org]

like to follow the development process (1)

swschrad (312009) | about 6 months ago | (#46578611)

for instance, how many times did they make one a noise-emitting diode?

Back asswards (2)

Tablizer (95088) | about 6 months ago | (#46577513)

"Ralos Cell"

Infinite energy! (3, Funny)

kheldan (1460303) | about 6 months ago | (#46577517)

o Solar cell that also emits light
o Sandwich it with a perfect mirror
o Short the leads together
o Infinite energy!

Re:Infinite energy! (-1, Troll)

ArcadeMan (2766669) | about 6 months ago | (#46577547)

o Since when is the lowercase "O" a bullet?

Re: Infinite energy! (0)

Anonymous Coward | about 6 months ago | (#46577589)

o no!

Re:Infinite energy! (2)

galloog1 (3433335) | about 6 months ago | (#46577621)

The military uses them in form software that does not allow for special formatting. It could be out of habit.

Re:Infinite energy! (2, Funny)

Anonymous Coward | about 6 months ago | (#46577651)

No, you got it wrong, it's to the tune of "O Tannenbaum"

O Solar cell, that emits a light,
O Sandwich it with a perfect mirror,
O Short the leads together, dear,
Infinite energy, and free beer.

Re:Infinite energy! (0)

kheldan (1460303) | about 6 months ago | (#46577653)

I post a Troll Physics/Infinite Energy meme just to be stupid-funny and you complain about my choice of what to use for a bullet point? Seriously?

Re:Infinite energy! (0)

ArcadeMan (2766669) | about 6 months ago | (#46577679)

Why so serious?

Re:Infinite energy! (0)

Anonymous Coward | about 6 months ago | (#46577725)

He hasn't figured out the cat + buttered toast system yet. Once it is understood, all seriousness doesn't matter.

Re:Infinite energy! (0)

Anonymous Coward | about 6 months ago | (#46577929)

I do believe you have been metatrolled.

Re:Infinite energy! (3, Insightful)

camperdave (969942) | about 6 months ago | (#46577869)

o Since when is the lowercase "O" a bullet?

Since Slashdot stopped honouring the <OL> and <UL> HTML codes.

Re:Infinite energy! (0)

Anonymous Coward | about 6 months ago | (#46578039)

Um, profit?

Re:Infinite energy! (0)

Anonymous Coward | about 6 months ago | (#46578081)

o Solar cell that also emits light
o Sandwich it with a perfect mirror
o Short the leads together
o Infinite energy!

Wrong!

Finite energy in an infinite loop.

Re:Infinite energy! (1)

X-Ray Artist (1784416) | about 6 months ago | (#46579147)

I wish I had points. I also had similar thoughts about some sort of feedback system

Re: Infinite energy! (0)

Anonymous Coward | about 6 months ago | (#46581387)

So are we magining the first solar powered sun?

Mirror = (1)

Rosco P. Coltrane (209368) | about 6 months ago | (#46577525)

Infinite energy.

Genius...

Re:Mirror = (0)

cyborg_monkey (150790) | about 6 months ago | (#46577593)

You're a bit too slow with your "humorous" take on the story.

"Let There Be Light" (1)

hewearsmanyhats (2539624) | about 6 months ago | (#46577527)

Douglas-Martin sunpower screens, which also appeared in "The Roads Must Roll"

Whoa (1)

jovius (974690) | about 6 months ago | (#46577531)

A window with tunable coloring.

New generation of displays? (1)

ArcadeMan (2766669) | about 6 months ago | (#46577573)

Tuning the composition of the solar cell enables it to emit different wavelengths of light

Could this be used to make displays? Pros/cons?

At long last! (1)

Anonymous Coward | about 6 months ago | (#46577577)

The Solar Powered Flashlight is a reality

Yin and Yang (5, Interesting)

Dan East (318230) | about 6 months ago | (#46577597)

Speakers can be used as microphones.
LEDs can be used to detect light.
Motors can be used as generators.
Now some solar cells can emit light.

Problem is it's matter of efficiency, which is always more of a one way street.

Re:Yin and Yang (1, Redundant)

steelfood (895457) | about 6 months ago | (#46577835)

Problem is it's matter of the second law of thermodynamics, which is always more of a one way street.

FTFY. I'm waiting for the yang of that yin to show up. Maybe it won't.

Re:Yin and Yang (0)

Anonymous Coward | about 6 months ago | (#46578051)

I'm waiting for the yang of that yin to show up

You're waiting the in wrong direction of time, that's all.

Re:Yin and Yang (4, Insightful)

Sir Holo (531007) | about 6 months ago | (#46580953)

Absolutely brilliant comment. Also, you are correct.

For those who didn't get this post: A transducer is a transducer. It can go either direction, as the physical mechanism is the same, whether one direction or the other. For example, electromagnets move a speaker cone to create sound. Yell at a speaker, and the sound pressure will generate a small voltage (a microphone).

When poster called it a "one way street," he was referring to the way we engineer and design these transducers. They are optimized, for example to produce sound accurately. This inevitably leads to design trade-offs and optimizations for a particular application. That's all. No one is threatening the second law.

When land-line phones were wired (not cordless), I discovered as a child that I could yell into the earpiece, which modulated the voltage on the line, and a faint sound could be heard at the other end. The implications for eaves-droppers was that removing the microphone from your phone handset would not render you undetectable to the other people on the line, precisely for the reasons above.

Re:Yin and Yang (1)

coofercat (719737) | about 6 months ago | (#46583427)

I'm still waiting for a microwave over that can cool things down though ;-)

Re:Yin and Yang (0)

Anonymous Coward | about 6 months ago | (#46582337)

LEDs can be used to detect light. ...
Now some solar cells can emit light.

You do realize that those two points are exactly the same? Light emission might be inefficient due to indirect semiconductors, and may be in the infrared, but most pn-junctions will also emit light if you pump them hard enough.

Let There Be Light (1)

nani popoki (594111) | about 6 months ago | (#46577615)

by Robert A. Heinlein postulated a solar cell that would emit light http://en.wikipedia.org/wiki/L... [wikipedia.org] . The story came at it from the opposite direction -- a lighting panel that turned out to also work as a photovoltaic cell. Heinlein's story was published in 1940. Only took 3/4 of a century for engineering to catch up with science fiction.

Re:Let There Be Light (1)

OzPeter (195038) | about 6 months ago | (#46577755)

by Robert A. Heinlein . Only took 3/4 of a century for engineering to catch up with science fiction.

So where is the gratuitous sex between the Researcher and his mother? It can't be a Heinlein rip off unless there is gratuitous sex somewhere.

Re:Let There Be Light (1)

lister king of smeg (2481612) | about 6 months ago | (#46577845)

by Robert A. Heinlein . Only took 3/4 of a century for engineering to catch up with science fiction.

So where is the gratuitous sex between the Researcher and his mother? It can't be a Heinlein rip off unless there is gratuitous sex somewhere.

I don't think ALL of Heinlein books had gratuitous sex scenes I don't remember one in Sixth Column for example but it has been a while since I read it so I may be mistaken.

Re:Let There Be Light (0)

Anonymous Coward | about 6 months ago | (#46579333)

There are none in my edition of 6th column. Would have surprised me if there were any. It was a pamphlet written in the midst of war, with censors looking at everything and aimed at general consumption in a magazine (Astounding SF). Not really the time or place for steamy sex scenes.

Perovskite is a mineral ... but this isn't it (5, Informative)

qparadox (1105733) | about 6 months ago | (#46577665)

When the article references perovskites, it is referring to a crystalline structure similar to the mineral perovskite (calcium titanate). These solar cells are NOT made of calcium titanate, nor is calcium or titanium even in them. Instead, they are make of organic - inorganic halides, in this case: CH3NH3PbX3 (where X = Cl, Br, I). The proper wikipedia link for the summary is: https://en.wikipedia.org/wiki/... [wikipedia.org]

Re:Perovskite is a mineral ... but this isn't it (1)

alva_edison (630431) | about 6 months ago | (#46585055)

I'm actually curious where you got the information from. The linked articles from Wikipedia don't mention specific materials, with the exception of one. That material is specifically C.H3.N.H3.Pb.I.Cl2 (starting from C.H3.N.H3.I and Pb.Cl2), which falls within your broader categorization.

<offtopic>Why is Slashdot using a font where it is easy to confuse I and l?</offtopic>

Solar cell that emits light.... (3, Funny)

Anonymous Coward | about 6 months ago | (#46577707)

Any solar cell will emit light ... if you run enough current through it.

Re:Solar cell that emits light.... (4, Funny)

camperdave (969942) | about 6 months ago | (#46577997)

Any solar cell will emit light ... if you run enough current through it.

Ah yes! Reminds me of the smoke emitting diodes I used to play with as a young lad.

Re:Solar cell that emits light.... (0)

Anonymous Coward | about 6 months ago | (#46578099)

Well, we went from light emitting resistors to light emitting diodes, clearly the next step is light emitting transistors.

Re:Solar cell that emits light.... (1)

LordLimecat (1103839) | about 6 months ago | (#46578361)

Just about anything will emit light if you pump enough current through it.

Re:Solar cell that emits light.... (1)

camperdave (969942) | about 6 months ago | (#46579627)

Well, we went from light emitting resistors to light emitting diodes, clearly the next step is light emitting transistors.

Like these [nature.com] or these [uq.edu.au] ?

Re:Solar cell that emits light.... (0)

Anonymous Coward | about 6 months ago | (#46578395)

All CPUs run on magic smoke. If you increase the voltage too much, the smoke gets out and it stops working.

Re:Solar cell that emits light.... (1)

Lodlaiden (2767969) | about 6 months ago | (#46580145)

That has the potential to be an awesome troll argument later on. I'll be saving that one.

Re:Solar cell that emits light.... (0)

Anonymous Coward | about 6 months ago | (#46580567)

Welcome to Slashdot. You'll be needing a copy of our language reference. [catb.org]

Re:Solar cell that emits light.... (0)

Anonymous Coward | about 6 months ago | (#46578477)

As my EE professor used to say in the lab: "anything can be a fuse".

Re:Solar cell that emits light.... (0)

Anonymous Coward | about 6 months ago | (#46578859)

Depends on if you define light as only visible though....

Not so new (1)

eastjesus (3182503) | about 6 months ago | (#46577751)

I remember the Heinlein story - it's been many years, I'll have to dust off that old book and read it again - but I also recall that regular LED's have always done this too, but just very poorly on the light to electricity conversion part. Seems I remember a project long ago taking advantage of this - something from Forrest Mims maybe?

Re:Not so new (0)

Anonymous Coward | about 6 months ago | (#46577877)

Yup, he did several articles about using LEDs as frequency specific photodiodes, as well as using cadmium sulfide photodetectors as, iirc, green light sources.

Re:Not so new (1)

Anonymous Coward | about 6 months ago | (#46577911)

something from Forrest Mims maybe?

Is that the "box of chocolate" guy? He seems to have been everywhere.

Fossil fuels are 50 cents per watt? (1)

bunratty (545641) | about 6 months ago | (#46577889)

Maybe the equipment needed to generate electricity from fossil fuels costs 50 cents per watt, but then you also need to buy the fossil fuels. I would expect the cost of fossil fuels would be measured in cents per Joule. If solar cells can produce electricity for 10 cents per watt with no fuel costs, I think we should work on scaling this up as fast as we can. We can all have more energy for less money than ever before! Of course, we also need to work on how to store energy produced on sunny days for use during the night and cloudy days.

Re:Fossil fuels are 50 cents per watt? (1)

mdsolar (1045926) | about 6 months ago | (#46580073)

I agree this is the wrong unit since fuel costs are the main thing (plus environmental and public health costs) but someone may have tried to make things inter-comparable by integrating over twenty years of solar panel use, found the equivalent fossil fuel cost and divided back down. Looks like they may have forgotten to make electricity from the fossil fuels (neglected efficiency) since grid parity comes in at around $1/Watt for solar.

Projected? (0)

Anonymous Coward | about 6 months ago | (#46577967)

Let me know when reality starts to look anything like your cost projections. I'll be over here, not holding my breath.

Better learn Chinese (0)

gelfling (6534) | about 6 months ago | (#46578041)

so you can have a job in one of China's call centers set up to do customer service while the US was too busy trying to have LGBTQ liberal arts programs for illegal Mexicans who are illiterate in their own language.

...all the way down. (1)

mythosaz (572040) | about 6 months ago | (#46578213)

It's transparent solar panels on top of transparent solar panels.

It's transparent solar panels all the way down...

Cents per Watt (2)

q4Fry (1322209) | about 6 months ago | (#46578229)

Can someone who understands the subject matter better than I do please explain to me how "cents per watt" is an applicable comparative metric for fossil fuels and solar cells?

It would (at least apparently) seem to me that when you use a unit of fossil fuel, it is gone. By contrast, if you have a solar cell, it will continue to be useful for as long as the sun and the cell have line of sight.

So aren't fossil fuels inherently measured in Joules?

Re:Cents per Watt (1)

geekoid (135745) | about 6 months ago | (#46578495)

when talking about solar, money per watt is usually the cost of the cell divided by the watt output.

So a 200 watt solar panel* that cost 100 dollars would be 50 cents a watt.

*yes I just changed it form cell to panel.

Re:Cents per Watt (0)

Anonymous Coward | about 6 months ago | (#46582397)

You can buy 300W panels for RMB800 a pop, so we're at USD$0.43c a watt already.
Add shipping and duties, and you're at 50c a watt.

This is good.

 

Re:Cents per Watt (5, Informative)

Maury Markowitz (452832) | about 6 months ago | (#46579811)

> Can someone who understands the subject matter better than I do please explain
> to me how "cents per watt" is an applicable comparative metric for fossil fuels and solar cells

The price of electricity is basically the total money you put into running the plant over its lifetime divided by the total amount of power you get out of it during that lifetime. That's called the "levelized cost of electricity" or LCoE.

For plants that don't use fuel - wind, hydro, PV - the total amount of money is basically the price of the plant, the price of repairs and operations, and the price of borrowing the money to pay for the first two. For systems that go up in a short time, like wind and PV, the costs are utterly dominated by the price of the equipment.

For other sources the total cost of operations varies. Nuclear plants use fuel, but so little of it that it's not a major factor. However, these plants have enormous up front costs and decades long building cycles, so their LCoE tends to be utterly dominated by the prevailing interest rate. Coal and natural gas plants cost about 1/4 that of a nuclear plant and are therefore more heavily dominated by fuel costs, so their cost of operations goes up and down with the cost of the fuel.

So when you're trying to compare the price of a PV plant to a coal plant, for instance, the key metric in the case of PV is the cost of the panels. That's because there's no fuel cost and almost zero maintenance (had mine 5 years, done exactly $0 work on them so far).

Since the amount of sunlight shining in a particular area is averaged over long periods and available online, you can then predict the amount of power the plant will produce over its lifetime. For instance, in Toronto 1000 W worth of panels (i.e., a set of panels that will produce 1000 watts under specific conditions) will produce about 1200 kWh of power every year, after all conversion losses are factored in. We expect those panels to last about 25 years. So then

LCoE = (cost in cents/watt * size of system in watts) / (25 years * 1200 kWh * system size in KILOwatts)

So let's say the system, *all in*, costs you $3.50 a watt (about right these days). Then if you put up a system with 12 panels like mine, you get

LCoE = (3.50 * 3000) / (25 * 1200 * 3) = 11.66 cents/kWh

I think you'll find that is very comparable to what you are paying from your local utility, which is why PV is the fastest growing power source in the world today.

This same basic formula can be used with any power source, but the inputs will differ. For instance, the equivalent number for a nuclear power plant is about 7500 to 8000 kWh per kW of panels installed, because they run full out 24/7, or at apt 85% full power, or "capacity factor". But as you might expect, construction costs are much higher, about $8/W or more (that plant in Florida came in at about $11/W, which is why they cancelled it).

Likewise, wind turbines here in Ontario average about 30% "capacity factor" (CF), so that's about 2600 kWh/kW. That sounds bad until you consider they cost about $2/W installed. So when you compare the two head up it's something like (2 / 0.3) = 6.66 for wind vs. (8 / 0.85) = 9.41 for nuclear, which is why wind is the second fastest growing power source on the planet.

And that's why we measure everything in terms of cents per watt. If you know that (although dollars per watt is the typical figure) and the capacity factor, everything else sort of disappears. So you can get a *very* good idea of the economics simply by dividing the ($/W) by (CF).

If you'd like to do this on your own, with real numbers and more factors, you can. It's actually very easy and you can run through a given location in about 2 minutes:

http://matter2energy.wordpress.com/2012/05/21/green-apples/

Re:Cents per Watt (1)

Neil Boekend (1854906) | about 6 months ago | (#46583635)

It's probably the energy cost to make 1 watt of solar panel.
Assuming the summary is correct it costs 75 cents of power to make 1 watt of solar panel if you use solar panels to deliver that power and 50 cents of power if you use fossil fuels.
The reason for the cost/kwh is properly explained by sibling posters.

Solar panels that emit light (2)

SimonInOz (579741) | about 6 months ago | (#46578549)

So we could have a torch (sorry, flashlight) that only works in sunlight ... ? I'm not sure I'd buy one of those.

Re:Solar panels that emit light (1)

Neil Boekend (1854906) | about 6 months ago | (#46583639)

There is a magic trick for that: a small battery to store the gathered energy for night time use.
Besides, it'll be perfect for windows. Tinted windows by day and light emitting panels by night.

This isn't a new property of solar cells (1)

Anonymous Coward | about 6 months ago | (#46578811)

Solar panels are fundamentally identical to LEDs, just optimized to absorb light instead of emit it. Forward-biasing a solar panel and measuring its light emissions is a common method of inspecting the panel for damage. Perhaps they managed to get this particular solar cell technology to emit visible light for the first time? Silicon solar cells generally only emit infrared light, but it's pretty easy to get a gallium arsenide cell to glow red without damaging it.

"Cheaper manufacturing costs" from phys.org (2)

Animats (122034) | about 6 months ago | (#46579023)

Another one of those "nanomaterial" stories. Claims of "cheaper manufacturing costs" for a product not yet produced in volume. Yet another "solar cell made with printing technology" scheme. Sigh.

So this thing is one micrometer thick and they want to print it on windows. How long does it last, hammered by UV and weather and thermal cycling? Lifetimes for silicon solar panels are now up to 25 years (warranties are available for that long), and there's falloff in output over that time. Can a 1 micrometer film match that? Realistically, it's going to have to be behind a protective layer. Maybe it could be on the surface of the middle layer in double-pane glass, but now you have a complex sandwich to manufacture. There goes the "cheap manufacturing".

Vertical windows are poorly oriented for capturing power. Solar shingles [dowpowerhouse.com] are better oriented. (Also, they exist, and you can buy them now.) And, as the head of Applied Material Solar pointed out a decade ago, half the cost is installing the thing. These guys need better numbers to back up their cost claims.

Re:"Cheaper manufacturing costs" from phys.org (1)

R3d M3rcury (871886) | about 6 months ago | (#46579199)

Vertical windows are poorly oriented for capturing power.

While true, I believe the concept is more for skyscrapers/tall building where there is far more surface area down the sides on the building than on the top. So even if it is less efficient, you've got the space and it might as well be used for generating electricity.

No, I'm not going to take the solar panels off of my roof and just get fancy solar-energy generating windows. But if I was building a 20-story skyscraper, I might consider doing this. Assuming, of course, that your other valid concerns are addressed...

Re:"Cheaper manufacturing costs" from phys.org (2)

Mspangler (770054) | about 6 months ago | (#46579955)

"Vertical windows are poorly oriented for capturing power."

In the winter a south-facing vertical window does pretty well with the winter sun being rather low in the sky if you are 40 degrees or more of latitude.

Re:"Cheaper manufacturing costs" from phys.org (1)

Agent0013 (828350) | about 6 months ago | (#46583335)

You will also have much less snow on the side of the house than you will on the roof.

Re:"Cheaper manufacturing costs" from phys.org (1)

Neil Boekend (1854906) | about 6 months ago | (#46583773)

Solar shingles are better oriented. (Also, they exist, and you can buy them now.)

These things seem a hell to install. So many separate panels means so many separate cables.
And the heat buildup! Directly placed on the isolation is a bad idea. air needs to flow behind solar panels to keep them cool. A raised panel creates a chimney effect behind it, cooling quite efficient.
On a hot day in a reasonably warm climate (the Netherlands) roof tiles of 80ÂC (180F) aren't strange.
Normal shingles can handle temperatures of far over 100ÂC. (I have no data on how much exactly, but boiling water should be no problem).
Solar panels loose efficiency as temperature increases.
At 100ÂC there will be no to next to no efficiency left, but the exact efficiency losses are brand dependent.
Do you really want your solar panels to stop on the hottest days?
And that is added to the problem that semiconductors tend to die in heat. Have you ever ran a high power microprocessor without cooling?

Gallium Arsenide Cells Emit light when reversed (1)

acvolt (241850) | about 6 months ago | (#46579067)

If you reverse the voltage enough on a Gallium Indium Arsenide solar cell it will glow red just like a diffuse light emitting diode. You have to remove the protection diode from the cell for that to work however.

Pfft (4, Funny)

Hamsterdan (815291) | about 6 months ago | (#46579369)

That's nothing, while learning electronics as a kid, I invented a way to turn LEDs into Smoke Emitting Diodes...

75 cents? (0)

Anonymous Coward | about 6 months ago | (#46579607)

> coupled with cheaper manufacturing costs (10-20 cents per watt projected as opposed to
> 75 cents per watt with silicon solar panels and 50 cents per watt with fossil fuels

Ummm, you can buy silicon solar panels on the market for about 55 cents.

Even retail is 70 to 80.

farmland (1)

sp0tter (1456139) | about 6 months ago | (#46579953)

Does this mean these cells could be installed over farmland/ in greenhouses so we could get double use out of the same land? I kinda like this idea.

Re:farmland (0)

Anonymous Coward | about 6 months ago | (#46580875)

It would have the extra benefit of keeping any naturally occurring water from reaching the plants below.

Re:farmland (1)

Maury Markowitz (452832) | about 6 months ago | (#46582829)

> Does this mean these cells could be installed over farmland/ in greenhouses

You mean like this?

http://matter2energy.wordpress.com/2013/08/16/enphase-joins-the-big-leagues-a-2-mw-micro-inverter-system/

Not too bright (0)

Anonymous Coward | about 6 months ago | (#46583511)

Any common silicon solar cell will emit infrared light if you pass current through it. This effect is used during manufacturing to characterize defects.
http://www.mpi-halle.mpg.de/mpi/publi/pdf/8470_08.pdf

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