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Mars Orbiter Beams Back Images of Comet's Surprisingly Tiny Nucleus

jeffb (2.718) Re:The incredible shrinking nucleus (47 comments)

What a perfect application for a truck-bed-sided fusion plant.

Actually, scale it up a good bit from that. Cold side for heat-engine power cycle? You're sitting on a giant snowball! Boil off volatiles with the hot side of your exchanger, use some of your power to drive the deuterium separation plant you hauled along, and use the rest to accelerate some of the vapor out the back. It's the next best thing to rendezvousing with an already-filled fuel tank.*

* some assembly required

12 hours ago
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Ask Slashdot: Event Sign-Up Software Options For a Non-Profit?

jeffb (2.718) Re:SurveyMonkey (100 comments)

Frankly, when I here "we have unique demands" I ask for clarification an detain gently guid ether to the determination they are not a unique as they think.

I'm a consultant - I convert gibberish into cash-flow.

Speaking of unfinished jobs...?

yesterday
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Mars Orbiter Beams Back Images of Comet's Surprisingly Tiny Nucleus

jeffb (2.718) Re:½mile == 1km? (47 comments)

0.8 kilometer (1/2 mile) is about one kilometer. Claiming more precision ("1/2 mile, or 0.8 kilometer") would actually be misleading.

yesterday
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Facebook To DEA: Stop Using Phony Profiles To Nab Criminals

jeffb (2.718) "makes people FEEL less safe and secure"? (217 comments)

I think this was unintentionally revealing. It's the feeling of safety and security that Facebook is frantic to defend. Actual safety and security? Well, that's... complicated.

yesterday
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Mars Orbiter Beams Back Images of Comet's Surprisingly Tiny Nucleus

jeffb (2.718) The incredible shrinking nucleus (47 comments)

Well, I guess that takes a bit of the sting out of the missed impact opportunity.

If the nucleus really had been 50km in diameter (original estimated maximum), and if it had hit Mars, it would've significantly increased Mars' atmosphere with one blow. I'll confess that I was a bit disappointed when we realized that wasn't going to happen.

A comet this small would still have made an impressive boom, but it would have been perhaps a bit less world-changing.

yesterday
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32 Cities Want To Challenge Big Telecom, Build Their Own Gigabit Networks

jeffb (2.718) Highway analogy (170 comments)

I'd recommend against pushing that highway analogy. It makes it too easy for them to come back with:

"You don't get to drive 150mph on a highway designed for 70mph."

"We need to make sure overweight trucks don't destroy the road surface for the rest of our drivers."

"If everyone drove as much as you do, the roads would be so jammed that nobody would be able to get anywhere."

Each of these points is flawed, but the analogy you posed doesn't do much to help that.

yesterday
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Despite Patent Settlement, Apple Pulls Bose Merchandise From Its Stores

jeffb (2.718) Tonight on AppleDotDotDot... (327 comments)

Okay, okay, it's only the top two stories plus one more on the first page, which I guess makes for... 20% SlashDot market share?

3 days ago
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Apple's Next Hit Could Be a Microsoft Surface Pro Clone

jeffb (2.718) Re:It's the OS, Stupid (250 comments)

2005 called...

Oh my God! Did you warn them? About Beta?

3 days ago
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An Air Traffic Control System For Drones

jeffb (2.718) "Troll"? Really? (77 comments)

Apparently I should've leaned less on snark in my original comment.

By mandating central control, you're making so many assumptions -- the central controller is correct, the central controller scales successfully to the maximum traffic level, there is reliable communication at all times between the central controller and every autonomous agent, every autonomous agent correctly reports its position and status to the central controller, every autonomous agent responds correctly to direction from the central controller, and those are just off the top of my head.

I think the odds of getting every one of those elements right are vanishingly small, compared to "each autonomous agent implements collision and congestion avoidance to the best of its ability". This isn't my field, so I may be far, far off base, but I'm honestly not trying to troll here...

4 days ago
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An Air Traffic Control System For Drones

jeffb (2.718) Where have I seen this pattern before? (77 comments)

Autonomous individuals sometimes do bad things or get into conflicts. The solution is a central, controlling authority that knows what's best for them. A central, controlling authority can always work things out better than autonomous individuals, because it has all information and always knows the best way to act on it.

Wow, why hasn't anyone thought of this before?

5 days ago
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Carl Sagan, as "Mr. X," Extolled Benefits of Marijuana

jeffb (2.718) Re:What 20 years of research on pot has taught us (263 comments)

And, using the average THC content of 5% posted downthread, that means a scrawny 50Kg stoner would have to smoke or ingest 3Kg (six and a half pounds) to risk a 50% chance of death.

So, challenge accepted?

about two weeks ago
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2014 Nobel Prize In Physics Awarded To the Inventors of the Blue LED

jeffb (2.718) Re:As well they should. (243 comments)

No, I'm really not; I'm looking at graphs from references and tutorials, some at a pretty introductory level, some at a more advanced level. None of them are from sites trying to market anything -- unless you're implying that Big Grow Lamp has infiltrated and corrupted biology texts stretching back decades.

You raise interesting points (in other subthreads here) about green light penetrating further into a growing plant, and I'll certainly grant that the absorption curves don't reach zero in the yellow-green range.

I'm not in a position to watch or listen to a video; can you link to any other information about the "ZERO LIGHT growing technology" you mention?

about two weeks ago
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2014 Nobel Prize In Physics Awarded To the Inventors of the Blue LED

jeffb (2.718) Re:As well they should. (243 comments)

Also, green light is great for plants. Don't let old science fool you. Why do you think an HPS lamp works so well despite about 80% of its visible light output being green and yellow?

When I GIS "photosynthesis spectrum", I see a million different curves, but they all peak in red and violet-through-blue-green. Even if you don't look at emission and absorption curves, just look at a plant. Its leaves are green. That means that it's reflecting more green light relative to other colors. That should be a clue that green light isn't the most efficient choice for feeding plants. (It's not conclusive, of course; nature's paths aren't always optimized for efficiency.)

Why do HPS lamps work so well? I don't know, but here are some possibilities:

They're many times more efficient than incandescent grow lamps, so you get more usable light per watt even if its spectrum isn't ideal.

HPS grow lamps are tweaked to produce more red light.

HPS lamps put out a huge total radiant flux, so they're just brighter than alternatives, in both useful and wasteful wavelengths.

Can you provide some supporting evidence that "green light is great for plants", when it's near the bottom of the photosynthetic absorption spectrum?

about two weeks ago
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US Navy Develops Robot Boat Swarm To Overwhelm Enemies

jeffb (2.718) You've hit the nail on the head... (142 comments)

Basically, seems like a large amount of money for a system...

...and, in the "defense" arena, that's what makes the world go around.

about two weeks ago
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New OS X Backdoor Malware Roping Macs Into Botnet

jeffb (2.718) Re: I have seen some malware trying to infect my M (172 comments)

And this differs from the average user of every other consumer or business platform in what way, again? I mean, average Windows or Android users may not "think their machine is impervious to viruses", but they seem to "see no issue in" downloading random "music" or "videos" or "software" from even the skankiest sources.

It used to be that a combination of perhaps-somewhat-better security design and low platform population kept Mac users relatively safe even in the face of "average" ignorance and complacency. They're probably still safer than they would be on Windows (perhaps even Android), because they're still a bit of a niche market, but the margin continues to narrow.

about three weeks ago
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Hong Kong Protesters Use Mesh Networks To Organize

jeffb (2.718) I wonder what a government node could do. (85 comments)

Mesh networking, peer-to-peer, power to the decentralized people -- it all sounds great. But some of those people will still be on the side of the government. I wonder how much information one mesh node could accumulate to incriminate other participants? How many of "the people" will be willing to participate in an uprising like this if they know that a government stooge is likely no more than two or three hops away?

about three weeks ago
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Energy Utilities Trying To Stifle Growth of Solar Power

jeffb (2.718) Fine. Legislate for externalities. (488 comments)

There's a long tradition of regulating electrical utilities -- their new-plant construction, their service build-out, and most especially their rates. If connecting single-household solar installations and buying back power from them is imposing an undue burden, and they can prove this, adjust the tariffs accordingly.

But you shouldn't quash an entire emerging industry just to protect an old and established one. Unfortunately, that seems to be one of the main duties of legislatures.

about three weeks ago
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3D Bioprinter Creates "Living Bandage" Skin Grafts For Burn Victims

jeffb (2.718) Psst. It's 3D printing for LIFE EXTENSION. (26 comments)

I repeat. It's 3D PRINTING FOR LIFE EXTENSION -- specifically, preserving the life of patients who would otherwise face a fairly quick (and extremely painful) death.

I'm listening for that faint sound of a certain Fark refugee's skull rupturing in the distance.

about a month ago
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Device Allows Paralyzed Rats To Walk, Human Trials Scheduled Next Summer

jeffb (2.718) Food for thought for rat supporters... (85 comments)

If this kind of rat experimentation bothers you, and I can't say that it shouldn't, I'd like to ask two follow-up questions.

First, have you ever seen what a cat does when it encounters a rat or a mouse? Cats are predators, but they don't always just swiftly kill and eat their prey. They often toy with it for quite a long time.

Second, having learned about this behavior, are you ready to call for the abolition of cats? I'll promise you that cats torture and kill far more rats worldwide than all scientists put together, and we gain far less from that activity than we do from medical research.

If you oppose animal testing, I can see that as a principled and well-supported stand. But if you aren't willing to go further and call for the end of domestic cat propagation, I'd very much like some insight into your reasoning.

about a month ago

Submissions

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CES: Laser headlights edge closer to real-world highways

jeffb (2.718) jeffb (2.718) writes  |  about 10 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  |  about 5 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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