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Comments

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Dear Museums: Uploading Your Content To Wikimedia Commons Just Got Easier

jeffb (2.718) Re:interesting split developing (24 comments)

I had been wondering about this. A FOAF was a curator at a museum on the West Coast, and when I talked to him about the idea of online displays, he was completely dismissive -- it seemed like anything other than "Maximum Lockdown" didn't even register with him. Then again, this was probably 15 years ago. Was Maximum Lockdown the usual stance before the Internet explosion, or do all three approaches have a well-established history?

2 days ago
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Ask Slashdot: Preparing an Android Tablet For Resale?

jeffb (2.718) I wouldn't keep the hardware intact. (112 comments)

If you really want to sell it for parts, disassemble it and destroy the main circuit board, or at least grind or pry off the chips with nonvolatile storage.

Any general treatment (heat, overvoltage, etc.) will surely destroy the rest of the phone before you can be sure it's cleared the nonvolatile storage.

3 days ago
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Stanford Team Creates Stable Lithium Anode Using Honeycomb Film

jeffb (2.718) I'm worried about a hurdle nobody's mentioned. (117 comments)

It makes perfect sense to use lithium metal as an anode, as a way to minimize weight and maximize specific energy.

The problem is, it's an alkali metal, useful in a number of chemical processes -- including processes used to make meth. And so far, regulators in the US (and many other areas) have demonstrated that they'll do whatever they can to Fight the Meth Menace, no matter how much collateral damage they cause to industries, economies, and human well-being.

What kind of ridiculous regulations do you think they'll try to impose on devices that contain a multi-kilogram slab of Widely-Known Drug Precursor? Will we get cars that would have 500-mile range, but for the extra 500 pounds and two kilowatts of DEA/HSA-mandated security shielding and monitoring around the battery pack?

3 days ago
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Stanford Team Creates Stable Lithium Anode Using Honeycomb Film

jeffb (2.718) Re:*Yawn* (117 comments)

Yep, real men would never be happy with today's battery technology. That's why I still use a two-cycle engine in my phone.

3 days ago
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Stanford Team Creates Stable Lithium Anode Using Honeycomb Film

jeffb (2.718) Don't be silly. (117 comments)

You know that light delivery trucks will soon be replaced by drones. That's why we really need the improved batteries.

At least, that's what Amazon seems to want us to think...

3 days ago
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Two South African Cancer Patients Receive 3D Printed Titanium Jaw Implants

jeffb (2.718) Well, I'm picking my jaw up off the floor... (71 comments)

No, actually, I'm fortunate enough not to have that option. Still, it's good to see this happening for the people who do.

5 days ago
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Nightfall: Can Kalgash Exist?

jeffb (2.718) Re:fundementally impossible (86 comments)

Epsilon Lyrae, and the vast number of amateur astronomers who've known about it for ages, would beg to differ. Two components that are naked-eye visible, one a double, one a triple. All gravitationally bound, and apparently quite dynamically stable. Five other nearby stars may be gravitationally bound to the system as well.

Castor (Alpha Geminorum) is a sextuple system.

But, of course:

"It's simply not possible for a system like this to exist. If you point out that systems like this do exist, it doesn't mean that my statement is wrong, it means that you're a wack job, so just shut up."

Bravo, good AC. Bravo.

5 days ago
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Social Security Administration Joins Other Agencies With $300M "IT Boondoggle"

jeffb (2.718) A large IT project is late and over budget? (142 comments)

I've never heard of such a thing. Thank goodness Slashdot is here to challenge our preconceptions.

about a week ago
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Researchers Test Developer Biometrics To Predict Buggy Code

jeffb (2.718) This misses two of the biggest developer problems: (89 comments)

1) Arrogance. You know that average developers have a hard time with some kinds of code, but you're a superprogrammer, and you don't have those problems. If someone decides later that there's something wrong with your code, well, they should've gotten their requirements straightened out before they told you to go and build it. The only time you lose your cool is when you have to deal with idiot managers, analysts, or users.

1) Complacency. You've been pounding on this code forever, and you just don't care any more. Yeah, there'll be bugs, people will yell, they'll get fixed. That's just the way development goes. Why get worked up about it?

about two weeks ago
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AirMagnet Wi-Fi Security Tool Takes Aim At Drones

jeffb (2.718) Arguments based on drone range (52 comments)

It's possible to connect a controller to an antenna that vastly extends its range. Is your property extensive enough to give you a 2-kilometer perimeter around your house?

about two weeks ago
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AirMagnet Wi-Fi Security Tool Takes Aim At Drones

jeffb (2.718) I've got a similar idea in the works... (52 comments)

It's a receiver to detect the EM signature from the onboard electronics of a Prius.

See, I've heard that it's possible for a Prius driver to run over kids who are playing in the street. So I've designed this receiver that fits into a kiddy backpack, and sounds an alarm when there's a Prius nearby. That way, when my kids are playing in the street and a Prius approaches, they'll hear the alarm. I guess then they can get out of the street, but what I'm really looking for is a way to ban Priuses from driving on my street. After all, I'm a responsible parent who's keenly aware of the dangers Priuses pose to kids who play in the street.

about two weeks ago
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Verizon Boosts FiOS Uploads To Match Downloads

jeffb (2.718) And if you're in the vast FIOS-free zones... (234 comments)

...you'll be upgraded to pound sand with both hands.

North Carolina was promised FIOS "real soon now" for years. At this point, it's pretty clear that if you don't already have it, you won't be getting it. Google blimps, drones, and sewer lines will bring us high-speed broadband long before Verizon significantly extends their buildout.

about two weeks ago
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A Look At NASA's Orion Project

jeffb (2.718) Re:Old dreams (108 comments)

Well, if it tries to explode them out its nose, it doesn't go in the right direction.

about two weeks ago
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Cosmologists Show Negative Mass Could Exist In Our Universe

jeffb (2.718) Re:Negative mass is weird (214 comments)

Okay, as long as I've got you on the line... :)

What's supposed to happen when negative and positive mass collide?

If I throw a tennis ball at a wall, it bounces off (and the wall recoils imperceptibly). If I throw a negative tennis ball at a wall -- or throw it away, causing it to move toward the wall, whatever -- what happens when it hits? It seems like it would try to "recoil" in the same direction it was traveling, maybe even giving the wall a "tug" instead of a "push" when it hit. But it can't move forward, because presumably negative and positive matter can't simply interpenetrate -- or can they?

Gaah, so many microscopic/macroscopic behavior assumption violations...

about two weeks ago
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Cosmologists Show Negative Mass Could Exist In Our Universe

jeffb (2.718) Re:Negative mass- not antimatter, but odd (214 comments)

Negative mass is very diferent from antimatter. Antimatter is opposite to normal matter in charge and quantum numbers (such as baryon number, etc.), but still has positive mass.

Negative mass reacts oppositely to both gravity and intertia. Oddly, that means that negative mass still falls down in a gravitational field: The gravitational force is opposite, but negative mass responds negatively to force (a=F/m, where both F and m are negative). So negative mass particles repel each other gravitationally, but are attracted to positive mass objects.

Trying my best to ignore my intuition, which is heavily biased toward "all mass is positive":

A negative mass would fall down in a gravitational field (generated by a positive mass) -- it would experience a force directed away from the positive mass, and it would respond to that force by moving toward the positive mass.

However, the negative mass would repel the positive mass gravitationally -- effectively, exert a force directed away from itself -- correct?

It seems to me that if you had two equal but opposite masses in freefall, the negative mass would accelerate toward the positive, the positive would accelerate away from the negative, and the negative mass would chase the positive mass off the edge of the universe at constant acceleration.

It also seems like two negative masses would repel each other (exert a force directed away from each other), but respond to that repulsion by accelerating toward each other.

What am I missing?

about two weeks ago
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Brazil Nut Effect Explains Mystery of the Boulder-Strewn Surfaces of Asteroids

jeffb (2.718) Re:Explains the TV News (58 comments)

Still does nothing to explain the similar sorting of Slashdot comments, as illustrated in this thread.

about two weeks ago
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Phase-Changing Material Created For Robots

jeffb (2.718) "An' when they git ready..." (35 comments)

'... I say, when they git ready...... ever hear tell of a shoggoth?"

Terminator 2? Feh.

about two weeks ago

Submissions

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CES: Laser headlights edge closer to real-world highways

jeffb (2.718) jeffb (2.718) writes  |  about 7 months ago

jeffb (2.718) (1189693) writes "Audi will display laser-headlight technology on a concept car at the 2014 Consumer Electronics Show, joining BMW, whose plug-in hybrid should reach production in 2014. A November article on optics.org describes the technology in more detail. This approach does not scan or project a "laser beam" from the car; instead, it uses blue lasers as highly efficient light emitters, and focuses their light onto a yellow phosphor, producing an extremely intense and compact white light source and then forming that light into a conventional headlamp beam. The beam isn't coherent or point-sourced, so it won't produce the "speckling" interference effects of direct laser illumination, and it won't pose specular-reflection hazards. It's just a very bright and very well-controlled beam of normal white light.

HOWEVER, if multi-watt blue laser emitters go into mass production for the automotive market, it's likely to drive down their prices in other applications — for example, grey-market multi-watt "laser pointers". If you're looking for a tool to burn holes in the tires of drivers who offend you, this technology may indirectly help to fulfill your wish."
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Son of Therac-25: CT overdoses from "reset error"

jeffb (2.718) jeffb (2.718) writes  |  more than 4 years ago

jeffb (2.718) (1189693) writes "As the LA Times reports, 206 patients receiving CT scans at Cedar Sinai hospital received up to eight times the X-ray exposure intended. (The FDA alert gives details about the doses involved.) A misunderstanding over an "embedded default setting" appears to have led to the error. Human-computer interaction classes from the late 1980's onward have pounded home the lesson of the Therac-25, whose usability issues led to multiple deaths. Will we ever learn enough to make these errors truly uncommittable?"
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