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Comment: And yet, here we are on the Internet... (Score 1) 154 154

by jeffb (2.718) (#50011455) Attached to: How Television Is Fighting Off the Internet

...reading your op-ed (as opposed to, oh, I don't know, an actual report containing actual facts).

One of the unique characteristics of the Internet is that it provides a way to monetize tiny minority tastes. That way, bozos can produce books or videos on "Down is Up", "Beanie Babies: The New Future-Proof Investment", or "The Unexpected Triumph of Old Media in the Digital Age", and find enough paying customers to make it worth their while.

Comment: Hypersupervised programming? (Score 5, Insightful) 121 121

Golly! How do you suppose that having one person at a time writing code, with the rest of the team effectively doing simultaneous code review, magically produces "fewer features" but "better code quality" than having everybody writing code, then throwing it together and maybe doing a cursory bit of code review at the end?

Next, you'll be telling me that having one or two testers per developer produces better-quality software than spending all your money on developers so you can "get more features".

Comment: Never thought of plasma sheath as Faraday cage... (Score 1) 62 62

Turning the shield (conductive layer around the craft) into an antenna? I like this idea. And with the full paper freely available through the link in the source article, I could in principle learn more -- if only my math and EM physics were up to it. Sigh.

Comment: Re:skip the gender (Score 1) 412 412

by jeffb (2.718) (#49884307) Attached to: Nobel Prize-Winning Scientist Criticizes Role of Women In Labs

Some of us are heteroromantic, biromantic, homoromantic, panromantic, demiromantic, or even aromantic.

We realize that different cultures have different hygiene practices, but really, can't you put on a bit of deodorant in the morning?

Oh, wait. Never mind.

Comment: Then why say "you" instead of "I"? (Score 2, Insightful) 412 412

by jeffb (2.718) (#49884185) Attached to: Nobel Prize-Winning Scientist Criticizes Role of Women In Labs

"I was just being honest about my own shortcomings -- by talking about what 'you' do when there are women in the lab. 'You', of course, being a straight male, because duh, who else would I be bothering to talk to about science?"

Comment: Re:Cool, but way overstated. (Score 1) 47 47

by jeffb (2.718) (#49805377) Attached to: First Ultraviolet Quantum Dots Shine In an LED

It almost seems like you're interpreting "UV-C" to include the range from 360-380nm. There are apparently some results indicating that emitters in this range can be germicidal, if you use enough power and enough exposure time; is that where our disconnect is arising?

The Nichia page you linked lists only longwave emitters, with 365nm the shortest wavelength. I'm sure they have shortwave emitters, and maybe even samples for some of them, but if they aren't listed on the Web site, I'm not confident how much of a "product" they are to date.

Cree has never sold UV-C LEDs, as far as I can tell. They sold longwave emitters for a while, but then discontinued them.

I spent some time prowling around HaSun's list of UV LEDs. I haven't waded through every listing, but most of the emitters under 300nm seem to be in the range of 1.5mW or less; I found one ("New Technology!!!") that claimed 0.2-0.3W optical output power in the specs, but in the chart below, it said 0.2-0.3mW. WIth forward current of 20 mA and forward voltage of 7-8.5 V, getting out 200mW of anything would be quite the trick.

Again, we can see that the shortwave emitters exist, but it doesn't look like they're common enough or powerful enough to start appearing in products yet.

Comment: Re:Yes and no (Score 2) 47 47

by jeffb (2.718) (#49805259) Attached to: First Ultraviolet Quantum Dots Shine In an LED

I'm flattered that you're reposting my links from below, but I think you're missing GP's point. None of those three links appear to describe units that are "commonly available" -- in one case, it's only engineering samples, and in none of the links do they say a word about pricing or actual availability (the last one claims "mass production", but doesn't back it up).

"UV lasers" are mostly 405nm, not really UV, and the quantum dots from TFA are firmly in longwave territory. So, GP's points stand.

Comment: Re:Water sterilization is the big thing here (Score 1) 47 47

by jeffb (2.718) (#49804679) Attached to: First Ultraviolet Quantum Dots Shine In an LED

Actually, 420 would be a bit too violet for this application. Cree's XR-E emitters seem to use a blue emitter centered around 450nm (pdf), coupled with a yellow phosphor -- blue + yellow = blue + (green + red) = white. That's how most "white" LEDs work. If you used a shorter-wavelength emitter, you'd need to downconvert all its output power, losing efficiency. By using a blue emitter, you pass some of the blue light, and downconvert just enough of it to yield the perceived color temperature you want.

Comment: Re:Cool, but way overstated. (Score 3, Informative) 47 47

by jeffb (2.718) (#49804653) Attached to: First Ultraviolet Quantum Dots Shine In an LED

Links, please? Last I checked, UV-C emitting diodes were essentially experimental items, with output power below 1mW, and sky-high prices. Feel free to ridicule me mercilessly if I'm wrong, but please post links; I'm a lot more interested in learning about UV-C emitters than in defending my hypothetical reputation.

This page crows about UV-C LEDs, but is conspicuously silent about output power (beyond calling it "stable"), availability, or price.

This page claims 5-10mW per device, adding that "limited release engineering samples are available today." The datasheet is mum on device lifespan.

This looks more promising -- 10mW per device, 10,000 hour life -- but where are the products, and where are the prices?

Obviously, I could be missing some products that are already shipping. But if you actually have a bank of UV-C LEDs that's been putting out enough power to kill algae in your aquarium for the last five years, it looks like a lot of electronics and physics journals would be interested in hearing from you. And so, as I said, would I.

Comment: Cool, but way overstated. (Score 3, Informative) 47 47

by jeffb (2.718) (#49802933) Attached to: First Ultraviolet Quantum Dots Shine In an LED

We already have robust conventional LEDs that emit high power at comparable wavelengths (considered "longwave UV"). This wavelength is not especially useful for purification and sterilization. For that, you need UVC, in the range of 250nm and below. That's still difficult with anything other than a fluorescent emitter or an arc; solid-state emitters in that range have very low power and short life, at least last time I checked.

The other problem with very short wavelengths is finding packaging materials that will transmit and withstand them over long periods. Even longwave UV will cause materials to deteriorate over the lifespan of a solid-state emitter; UVC is much more harsh.

Comment: Okay, I thought *I* took a long time... (Score 1) 134 134

by jeffb (2.718) (#49785497) Attached to: A Ph.D Thesis Defense Delayed By Injustice 77 Years

I just really enjoyed grad school too much to want to finish, and they eventually made it clear to me that I'd better defend soon or they'd kick me out. Of course, I also wasn't accomplishing nearly as much in the interim as the article's subject.

It's an inspiring story. All the same, my dissertation defense is something that I'm just as happy I won't have the opportunity to tackle later in life...

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