RottenBrains

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Archive for the ‘Science’ Category

Drones toss and catch inverted pendulum – Boing Boing

Thursday, February 21st, 2013

The research drones are at it again. This video is really impressive, if not as showy as some of the previous ones. I can imagine the CIA drones go from blowing up suspects with hellfire missiles to just apprehending them Spiderman style.

Drones toss and catch inverted pendulum – Boing Boing:

Mozzies learn to ignore DEET

Thursday, February 21st, 2013

A test suggested that some mosquitoes can be temporarily desensitized to DEET. I wish I could become as easily desensitized to the the stuff. I’d like to see a similar test for picaridin.

Mozzies learn to ignore DEET | TG Daily

Will we ever do anything like this again?

Sunday, April 17th, 2011

SuperMoon

Saturday, March 19th, 2011

Incandescent Lights: What EISA Really Means

Friday, September 4th, 2009

There’s been a lot of press coverage recently of the incandescent lighting provisions of the Energy Independence and Security Act of 2007, and it’s largely been of the form “The US Government is banning incandescent light bulbs.”

While this makes for good prime-time newsvertainment, it’s not really true.

The tungsten light bulb was invented in 1905 as a fairly radical improvement on the earlier carbon filament bulbs, which would generally last less than a week before burning out. The humble incandescent light bulb was pretty constantly improved — both in terms of lifetime and efficiency — until about 1964. At that point in time, a bulb that used 100 watts could put out between 1,300 and 1,700 lumens. And that’s where we are now. The most commonly used incandescent bulbs have seen no real improvements in the past 45 years.

Now, let’s look at what EISA actually says about incandescent bulbs. A careful reading shows that it doesn’t eliminate incandescent bulbs. Far from it. All it does is set minimum efficiency standards for them. The relevant information comes from Pub.L. 110-140, Subtitle B, Section 321 (a)(3)(A)(ii)(I)(cc); the important columns from the table are:

Lumens Maximum
Wattage
Effective
1490 – 2600
72
2012
1050 – 1489
53
2013
750 – 1049
43
2014
310 – 749
29
2014

The four lines in the table correspond roughly to modern 100, 75, 60, and 40 watt bulbs respectively. So, those are certainly aggressive compared to the ’60’s technology that we’re using today. But it’s not a “ban on incandescent bulbs” any more than recent automobile efficiency regulations are a “ban on internal combustion engines.”

In fact, you can already buy, right now in 2009, a number of bulbs that meet these standards. Sure, they’re a bit pricey right now, but so were 13 SEER air conditioners five years ago. When regulations force minimum efficiency standards, economies of scale almost always kick in and drop the prices to be very close to those of the older, less efficient technologies.

On top of this, we’ve seen some extremely promising advances in incandescent technologies, including laser treatment of filaments and coatings that turn waste heat into visible light. Either of these alone would completely blow the EISA standards out of the water, beating them by a margin of more than 30%. And there’s no reason to believe that they can’t be combined with each other for additional efficiencies.

So, before you start writing your eulogies for the humble incandescent bulb, I’d give the industry some time to show us what they can do when given a challenge.

Edit: there are additional EISA provisions that kick in January 1st, 2020; these require an efficiency of 45 lumens per watt or better. This will be more difficult, but the kinds of advances I talk about above are already close to this standard — the laser technique gets you to 35 lumens per watt — so even that isn’t likely to be incandescent’s death knell.

Homebrew Rocket Reaches Space

Wednesday, October 22nd, 2008

This is wicked cool. A 17 foot homebrew rocket phones home with this picture. Click through to read the details in the flickr comments.

Space, the Final Frontier

(Via Wired)

Lots more details: Pyro Geek Hobbyists Experiment With Homebrew Rockets

Edit: Lots of cool amateur rocketry pics in the same photoset.

Boy, George would be proud

Monday, April 7th, 2008

Cama cama cama cama cama chameleon

(might need a camelid++ category now. Or is that camelid–?)

Texas “Body Farm” on Hold

Thursday, May 10th, 2007

Sometimes the news is breath-takingly weird.

It seems that Texas State University in San Marcos, TX, had to put their “body farm” project on hold. What’s a body farm, you ask? It’s a location to study the decomposition of, well, bodies. Human ones. For forensic research purposes. There are a couple of these in the USA already, but Texas has a different enough climate to warrant one of its own.

But that’s not the really weird part. The reason this is being put on hold is not the obvious “not in my backyard” argument. Rather, it is the concern that the resulting buzzard density might endanger traffic at a nearby community airport.

Chocolate as an Antitussive

Thursday, December 28th, 2006

According to a 2004 article in New Scientist, theobromine maybe a stronger cough suppressant than codeine.

Theobromine is an alkaloid primarily found in dark chocolate.

Edit: The article did not actually say it was better than Codeine. I read that somewhere else–I forget where.

Edit 2: Anyone in the Estacado Systems office this week would tell you I was in need of such. I tried some–and it worked for a while, anyway. (Thanks, Brian!)

Hypercolor Monitors in the Works?

Saturday, September 2nd, 2006

In an earlier post, I discussed the difference between purple and violet, and explored some of the color limitations of electronic display technology. Phil recently pointed out an article in Wired that discusses the use of adjustable diffraction gratings to produce arbitrary colors. (In practice, the gratings don’t produce the colors; they diffract a white light in such a way that the desired color can be made to pass through a pinhole). In theory, an array of these can be constructed to produce vivid-color televisions and monitors.

There’s something I find a bit suspect about the article, though. I mean, yeah, it’s full of the traditional Wired-style junk science (e.g., using relative voltage to compare power efficiency without taking current into account — plus, it includes a diagram of all the colors monitors can’t display [pause two beats here to let that sink in]), but in terms of color rendering, it says one thing that stands out as really bizarre.

The researchers are quoted as saying they intend to use white LEDs as the light source for this technology.

What?

LEDs are diodes made with materials specifically chosen so that electrons crossing the p-n junction cause a photon to be released. The wavelength of these photons (color of the produced light) depends on the exact materials being used. Note I said “wavelength,” not “wavelengths” — LEDs produce a single color out of the spectrum at a time. (Strictly speaking, they produce a very narrow range of wavelengths, typically about 20 to 30 nm wide, with very steep drop-offs — but this is as close to a pure color as to make no difference for this conversation).

White LEDs can be produced by mixing together two or more carefully chosen single-color LEDs, but this is rarely done. Almost all white LEDs produced today use a blue LED as their base (gallium-nitride based, with a wavelength of ~460 nm); on top of this LED, they layer a phosphorescent substance (cerium-doped yttrium aluminum garnet) which absorbs part of the blue light and emits a yellow light centered around 580 nm.

If you take the light from one of these LEDs and pass it through a prism, you’ll get a very thin, bright line of blue, and a slightly wider beam of orange/yellow/green.

By now, you should see where I’m going with this. If you use a white LED as your color source for a monitor that uses a diffraction grating, the results will be no better than today’s color display technologies, and arguably worse. Not only will you lack the ability to display colors below 460 nm (keeping in mind that s-cones peak at 420 nm: no violet for you!), but you’ll have gaps in the lower green and upper red spectrum as well.

Nonetheless, the adjustable diffraction technology is fascinating, and I hope something like this eventually gets to see the light of day — hopefully using something more wide spectrum than what the article implies for a light source.

Now all we need is a CCD that can record a full-spectrum scene, and we’re good to go.

Got a spare $100,000?

Saturday, August 26th, 2006

Ben brought to my attention a new breed of electic car that Tesla Motors is producing. The vehicles themselves are styled and manufactured by Lotus.

The first car out the gate is the “Tesla Roadster” — a two seater with a trunk that can be described only as “vestigial.” It’s a soft-top convertable with a hard top option. So it’s an electic sports car? Yep. It shouldn’t be too much of a surprise: the Japanese have been outperfoming gas-powered cars using electric prototypes for years. (According to Wired, Tesla Motors has other cars in the works as well).

This car is as different from the electric cars of yesteryear — most of which were glorified golf carts — as is possible. With a 200 kW powertrain (that’s almost 270 horsepower for you luddites), it can go from a standstill to 60 miles per hour in 4 seconds. It has a top speed somewhere north of 130 miles per hour. Under normal driving conditions, it can go 250 miles on a single charge. And while previous electric cars required exotic charging stations, this one has an optional “travel charger” that allows you to plug it into a normal wall outlet. (It does come with an exotic charging station that you install at your house that charges it up more quickly — empty to full in 3 1/2 hours).

And, for Ben’s sake, I’ll point out that the iPod dock comes standard.

At $100,000, I’m not quite putting in my down payment yet — but it’s really promising that someone can make a batch of these (1,000 for the 2007 year model) for a price that’s almost on par with gasoline cars in the same class. At this price, the first batch (limited edition) of 100 sold out — prepaid — within two weeks. They’re taking orders for the second batch right now.

Gastronomique at 2-Billion degreez

Sunday, March 19th, 2006

There are several fun new devices coming out for those who like to explore in their cooking.

Add a little more science and things could get really  interesting:

<dr-evil>Two BILLION Degrees!</dr-evil>

Friday, March 10th, 2006

Using a setup they term a “Z-Machine,” Sandia Labs has managed to get a bundle of tungsten up above two billion degrees Kelvin. If that’s not enough, it appears that the total power output (in the form of x-rays) from the system is greater than the total power input. They’re not certain what’s going on, but the possibilities for nuclear power generation are intriguing.


The Z-Machine in Action;
Click for a larger version

Conflicting Evidence on Fiber

Wednesday, December 14th, 2005

Reuters is reporting that a recent analysis of previous dietary studies has concluded that dietary fiber has no discernable correlation to incidence of colon cancer.

The article is careful to point out that the other benefits of dietary fiber haven’t been called into doubt (and that, in fact, this analysis did turn up a reduction in rectal cancer in individuals with higher-fiber diets).

Violet is not Purple: Is digital imaging broken?

Sunday, May 1st, 2005

Last night, as I was trying to get to sleep, I had a series of thoughts that brought me to a troublesome gap in my understanding of human vision1. My problem? I couldn’t figure out how we see purple.

See, growing up, we were always taught that the spectral colors, starting from the longest wavelength, were red, orange, yellow, green, blue, indigo, and violet. If you ever asked the teacher what violet was, they’d say “it’s just another name for purple.” Indigo? “It’s kind of a puplish-blue. It’s named after a type of flower.” Thus, we are taught that the rainbow, and therefore the spectrum of colored light visible to humans, looks like this:


~400 nm                                                  ~650 nm
This Is Wrong

There is plenty of confusion to go around here, so let’s start with the basics.

Average human eyes have four types of receptors — rods and three kinds of cones.

The rods operate well in low-light, are far denser than cones, respond more slowly than cones, and help distinguish contrast and detail.

The cones require strong light, pick up colors, and help process motion more quickly. These cones each have a broad range of sensitivity. The short-wave ones, s-cones (often erroneously called “blue cones”) are most receptive around 420 nm. The medium-wave ones, m-cones (“green cones”), 534 nm; Long-wave cones, l-cones (“red cones” ), 564 nm. In reality, 420 nm appears violet to humans, while 564 nm is really more of a yellowish-green (and not anything like red at all).


Approximate Cone and Rod Responsiveness by Wavelength (normalized)

The responsivness of the l-cones is insignificant below 450 nm and above 700 nm; m-cones range from about 440 nm to 675 nm, and s-cones, from somewhere shorter than 400 nm to about 520 nm.

All that is sent to your brain (in terms of distinguing colors) is relative values from these three cones. So, consider a single, pure light wave with a wavelength of 570 nm. People with normal eyes will perceive this as yellow (because it stimulates both the m-cones and l-cones in the right ratio). Two simultaneous waves of light at, say, 510 nm (green) and 590 nm (red) in the right ratio will produce the same reaction from the cones — meaning it will appear to be the identical shade of yellow.

So, here’s where I got caught up: if purple (which at the time I thought was the same as violet) can be simulated as a mix of red and blue, how does violet — at the low end of the spectrum — stimulate the l-cones?

The answer is that apparently, it doesn’t. And the key to that answer is this: purple and violet are very different colors. Physiologically, violet results from stimulation of the s-cones without stimulating the m-cones. (Perceiving blue requires stimulation of the m-cones to some degree). Purple requires at least two wavelengths, so that the s-cones and l-cones are both stimulated without having too much stimulation of the m-cones. I’m going to have to grab a prism and play around with a few things to be fully comfortable with my understanding, but I think I have a functioning model again.

But here’s where things get odd.

The lowest wavelength that your screen can display is this:


      
 
 
 
Here is Blue

Exactly how that blue is produced (and its exact color) depends on whether you’re using a CRT or an LCD screen, and a wide variety of other factors. It’ll probably be around 460 nm, though. That’s right around what people like to call “blue.” Anyway, the fact is that your screen simply mixes Red, Green, and Blue together to make the colors that it can produce. And the blue that we see above is still stimulating your m-cones, or it would appear violet to you.

So, as far as I can tell, modern televisions, computer monitors, scanners — even digital cameras — simply ignore indigo and violet. There’s no way to record them, and no way to display them. Taking a digital picture of a violet flower or a bird with violet markings will produce an image that substitutes blue — probably dark blue — for violet.

A key example of this shortcoming is shown by any attempt to electronically render Yves Klein’s trademark “International Klein Blue,” which contains a lot of indigo and/or violet in it. In person, Klein’s art making use of this patented color is absolutely breathtaking, even if it’s just something simple like a sea sponge dipped in paint. Stunning. Unforgettable. Seeing a work like this in person is absolutely shocking:


You don’t understand how pretty this is

On your computer screen, it’s pretty unremarkable, isn’t it? To understand what you’re missing — and what’s wrong with stopping the spectrum at blue — make it a point to seek out some of Klein’s work the next time you’re near a modern art museum.

So, this raises an interesting question: why do all consumer electronics use only red, green, and blue? Consider that, if cameras and monitors instead used a red/green/violet color scale, we would be able to have the same range of color reproduction that we do currently, plus the visible colors from 400 nm to 460 nm. In practice, most people just don’t take much note of violet, and simply don’t miss it. But wouldn’t it still make more sense to be able to reproduce it when it is present?

I mean, doesn’t your monitor suddenly feel strangely defective now that you realize that there are colors you can see but which it completely lacks the ability to render?


1 The thoughts themselves started off with wondering whether a very low intensity LED (or similar light source) with a peak output around 496 nm — the peak sensitivity of the rods in human eyes — would be useful for assiting with seeing in low-light conditions without reducing night vision for objects not illuminated by the LED. In the final equasion, it seems that the use of red light works at least as well. But that’s the sort of random thought that goes through my mind when I’m drifting off.

Plants Create Genetic Backups?

Thursday, March 24th, 2005

Recent findings suggest that certain plants might have the ability to revert to gene sequences present in their grandparents’ DNA. One theory is that these reversions are activated if the genes passed to a plant by their parents cause them stress. It’s not clear where the backup copies of genetic information are being stored yet.

If these findings withstand scrutiny, and if such mechanisms also exist in animals, the implications for genetic engineering are staggering.

Apes Gone Wild!

Wednesday, February 23rd, 2005

So, if you teach Apes to communicate, what exactly do they ask for? Lewd acts, apparently.


Skysa App Bar