Please create an account to participate in the Slashdot moderation system


Forgot your password?
DEAL: For $25 - Add A Second Phone Number To Your Smartphone for life! Use promo code SLASHDOT25. Also, Slashdot's Facebook page has a chat bot now. Message it for stories and more. Check out the new SourceForge HTML5 Internet speed test! ×

Comment Re:Not regulated ... (Score 2) 65

A basic lens is pretty cheap; the cost goes up when you start adding various coatings or have to do special optics (extreme astigmatism, etc.). In fact, the frame ends up being the costliest part of my glasses, because I want ones that look good on me. I find it curious these adjustable glasses don't correct for astigmatism, though I suppose it's because you'd double the price if you had two cylindrical adjustable lenses instead of a spherical one in there.

Comment Re:"Just" A Patent Application? (Score 1) 52

Does anyone have a link to the actual patent application? The summary on the linked blog pretty much gives no details about the specifics of the patent (i.e., pretty much any design for a holographic display would have the components listed in the summary of the patent given by the blog) The big elephants in the room are: (1) how do you build a spatial light modulator that has micron-size pixels and yet be big enough to comfortably view a big image, and (2) how do you compute in real time what values those pixels need to be? A holographic display would need one or two orders of magnitude higher pixel density than Apple's "Retina Displays". The summary unfortunately sounds like the equivalent of "we present a patent for making a horse-drawn carriage, wherein you have a horse and it's attached to a carriage, which may be made of metal or wood or some other material, and wow look at the equation that gives you the shape of one of the pieces of the carriage!"

Comment Re:Integrity? (Score 3, Informative) 94

Sure, technology made this fraud a lot easier to commit, but technology isn't an intrinsic part of this ploy; he simply used computer algorithms to implement a lightning-fast pump-and-dump scheme.

Basically, what he did was the equivalent of putting out fake advertisements in a newspaper saying that he'd buy a lot of shares of a certain stock at elevated prices. Traders, seeing these ads, get the feeling that this stock is now worth a lot more than what it is trading at, so they start buying this stock at higher and higher prices. This allows him to eventually sell at high prices the shares he had already owned, making a profit. Meanwhile, when these other traders try to answer these ads, they get no answer and are thus left with a ton of overvalued stock.

Pump-and-dump, insider trading, etc. can all screw up the value of stocks, and they need to be prevented for the market to operate "correctly"; that's why there's laws making these schemes illegal. And while laws don't prevent these crimes, they can certainly help in reducing them.

Comment Re:Spiral filter, and a Tardis (Score 4, Informative) 122

Frankly, I am still confused as to why it's not (more simply) "circular polarisation" that has been known about since the early days of radio.

Since you linked to Wikipedia, I'm going to assume that Wikipedia didn't do a very good job at explaining the difference. While OAM and circular polarisation both describe some sort of spinning, they correspond to different phenomena. As you may know, electromagnetic waves are oscillations of the electric (and magnetic) field, with the field at each spatial position varying over time. You may also recall from your high school physics class that the electric field at any position is a vector quantity --- it has both a strength and a direction. The polarisation of a electromagnetic field is a description of the direction that the electric field points, and circular polarisation can be roughly seen as the electric field direction rotating as you travel in the direction of propagation. What OAM is describing is the phase relationship between the oscillations of the field at different positions (whether the oscillation at one point is lagged or ahead compared to a different point); it can be roughly thought of as a spinning motion in the transfer of energy inside an electromagnetic field.

For a rather inaccurate, but perhaps intuitive, analogy, try imagining a giant stream of asteroids coming your way in outer space. If the rocks are following a spiral trajectory as they come at you, then this corresponds to the rocks having "orbital angular momentum". If the rocks are themselves spinning, then this corresponds the rocks being "circularly polarised".

Comment Re:I wonder who they would have blamed (Score 2) 586

Well, at the time the air base near the crash site was the home of a B-52 bomber wing. The Strategic Air Command had dispersed its bombers among a bunch of smaller wings scattered across the country; obviously that made the bombers harder to destroy, but it also increased the number of potential strategic targets.

Comment Re:**what caused the plane to 'drop' the bombs?** (Score 4, Informative) 586

Others have already linked to Wikipedia's article about the crash, with one guy saying "sounds like a wing fell off". Reading the article, that seems fairly close to the mark, though not quite right. Here's a summary of what happened to the bomber:

The bomber was on an "airborne alert mission", meaning that it was carrying live nukes while flying on a route and schedule that would make it ready to perform a nuclear attack on the Soviet Union on short notice. (This was part of a program called Operation Chrome Dome.) While it was refueling from a tanker over North Carolina, the tanker crew told the bomber crew that the bomber's right wing was leaking fuel. The bomber broke off from the refueling, informed ground control, and were ordered to fly offshore and hold to burn off most of their fuel load, to reduce the risk of an emergency landing. However, on the way to the holding point, the fuel leak rapidly worsened and became critical, and the plane was then ordered to land immediately. During the descent toward the field, while passing through 10,000 feet altitude, the pilots found they could no longer keep the aircraft under control. The captain ordered the crew to eject; those who survived reported that the plane was still intact when they last saw it. Once the airplane went out of control, it must have gone into an uncontrolled spiral dive, a "tailspin"; that's what frequently happens to a flying airplane when control is lost. Such a dive is often fatal for the airplane long before it reaches the ground; the aerodynamic stresses increase so fast that it breaks up in the air.

From the sound of it, there was some sort of structural failure in the right wing which got rapidly worse. The wing did not actually fall off while the pilots were inside, but the failure became so bad that they couldn't maintain control and were forced to bail out. Unfortunately, even this article puts so much focus on what happened to the nukes that the important question of what caused the bomber accident in the first place is ignored. It would be nice to see what the Air Force's accident report has to say on this.

Comment This problem may affect more than just Xerox... (Score 4, Informative) 163

An earlier blog posting from Kriesel on this issue says that a reader reported similar behavior from a Brother copier:

And one of the comments to that posting says:

I have experimented with the open source jbig2enc library available at, which has a encoding parameter called the “threshold”, described like this:

“sets the fraction of pixels which have to match in order for two symbols to be classed the same. This isn't strictly true, as there are other tests as well, but increasing this will generally increase the number of symbol classes”

The included command tool accepts values for this parameter between 0.4 and 0.9, with 0.85 as the default.

I have found replaced digits in single-page numerical tables encoded with this parameter set as high as 0.82. As with the other examples you have found, the errors are not in any ways obvious to the eye which is, of course, the real problem.

Since JBIG2 has been supported in PDF since 2001, it would be surprising if only Xerox have fallen into this trap.

Comment Re:You pray if you like (Score 4, Informative) 147

Yeah they serve all right.. I'm guessing it's not too terribly dangerous to fly about in an armored helicopter shooting at a bunch of asiatic hillbillies with AK-47s.

With AK-47s, and heavy machine guns, and RPG launchers, and portable surface-to-air missiles and such. Oh, and there's always the risks of bad weather and mechanical failure inherent to helicopter flight. Helicopters are dangerous, period, and the Apaches are far from invulnerable. A number have been lost in Afghanistan and Iraq, and some crews have died.

In general, when a piece of military hardware is heavily protected, it also faces powerful threats that make that protection necessary. Otherwise it'd just be carrying extra dead weight that would better be replaced with useful equipment. The military isn't in the business of building invulnerable weapons or letting soldiers fight in "god mode".

And don't you think their opponents wouldn't love to have the coup of bringing down a royal? Just by being in the combat zone, they put themselves at risk.

Comment Re:You pray if you like (Score 3, Insightful) 147

Because you know if there's ever an imminent threat the members of the Royal Family aren't going to be sat at Buck House with a cuppa tea counting down the seconds...they'll be on their merry way to the other three corners of the globe.

Any member of the Royal Family who did that would rightly be disowned by the rest of the family and the British public, and would probably be looked down upon by much of the rest of the world as well. If the monarch herself did it (and I can't imagine Elizabeth II doing it in a thousand years--she may look like a little granny, but she has far too much backbone for that), she would effectively have abdicated. In the face of such a selfish, craven act, Britain would either find itself a new monarch with more spine, or get rid of the monarchy entirely.

The Royal Family enjoys a lot of privileges, but in the end they exist to serve the British state, as its personification. Their lives are far more controlled and circumscribed than ordinary people.

Just look at the case of Edward VIII to see how Britain might treat a monarch who doesn't take his duty seriously.

Comment Re:Why is it a sealed criminal complaint? (Score 1) 442

Easiest thing is to see what comes up under the "Glenn Greenwald" tag in LGF's archives. (You have to scroll to the bottom repeatedly for the page to load older posts, but there's stuff there going back to 2006.) Johnson has spoken contemptuously of Greenwald as dishonest for years, well before Johnson's falling out with the right. A past incident where Greenwald was supposedly caught "sockpuppeting" as commenters defending him on other blogs certainly didn't help matters. Anyway, I get the feeling that once Johnson makes up his mind like that about someone, there's not much that will change it, regardless of ideology.

Comment Re:Why is it a sealed criminal complaint? (Score 1) 442

If you read LGF's take on it more closely, it seems to have a lot to do with Charles Johnson's relationship with Glenn Greenwald, who's been the main guy other than Snowden himself pushing the Snowden story. Johnson himself has remarked that there are indeed very troubling issues with today's overgrown surveillance apparatus, but he has zero trust for Greenwald.

Comment Re:Is that still being updated? (Score 4, Informative) 88

It wasn't the heart operation itself that was the problem, it was the heart condition he needed the operation for. He'd known about it for a long time, but had previously believed it to be harmless. Actually, it had gradually been getting worse. While the long pauses between comics had been bad for quite a while, his situation really became terrible the last half year, because he was *completely* sapped of energy. That's when he saw a doctor and found out the state of things, which led him to have the operation. Sounds like he's been feeling vastly improved.

Slashdot Top Deals

We don't really understand it, so we'll give it to the programmers.