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Comments

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My degree of colorblindness:

Jbcarpen Re:Deeper reds (267 comments)

I likewise see IR bleedoff before it climbs into the lower end of most people's vision.

about a month and a half ago
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Human Blood Substitute Could Help Meet Donor Blood Shortfall

Jbcarpen Re:Old News (172 comments)

While I don't think non-donors should just be left out in the cold, I do think that donors should get priority over non-donors when it comes to receiving donations. (Exceptions for those who have never been able to donate, such as children, anemics, hemophiliacs, etc...)

about 3 months ago
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Yahoo Stops Honoring 'Do-Not-Track' Settings

Jbcarpen Re:They still exist? (300 comments)

After the latest Firefox update, though, typing a search in the address field doesn't go to my preferred (in settings) search engine, but instead to Yahoo.

Firefox stores data about which search engine to use in a set of XML files. If something else gains access to those files, it can edit them to keep the name and icon of, e.g. google, but send the actual search to goatse (or wherever). If you delete the files, then the "restore defaults" button on the "manage search engines" panel will enable, and restore the originals.

about 5 months ago
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Satellite Piece Crashes Through Man's Roof

Jbcarpen Re:The sky is falling! (121 comments)

First space balls, now this?!

A titanium ball of about five kg fell on to the roof of a house in Ordyn district.

No, no, this is still space balls.

more than 2 years ago
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'Free' Games Dominate Top-Grossing Game List On App Store

Jbcarpen Re:Apple isn't a parenting service! (161 comments)

Erm, did you see the post further up the page regarding the $99 in app purchase in smurf village? This is a kids game aimed at four year olds. No excuse there whatsoever.

more than 2 years ago
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The recent snow on the U.S. east coast ...

Jbcarpen Re:World News brought to you by a /. poll (292 comments)

Nah, only the coasts. In Colorado it takes several feet to do that, and even then we're back up and running in <24 hours (usually <12).

more than 2 years ago
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"World's Most Relaxing Music" Composed

Jbcarpen Re:Reaver breeding (239 comments)

Thank you Ted, that was the joke.

more than 2 years ago
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Making Sensitive Data Location Aware

Jbcarpen Re:Unless the phone can copy files (69 comments)

Exactly. If someone who HAD access to that data wanted to break security it would be trivial. The point of this technology is that if they forget to delete the data when they're one with it, it will do it for them. It's for the benefit of non-technologically-inclined people.

more than 2 years ago
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Ohio Supreme Court Drawn Into Magnetic Homes Case

Jbcarpen Re:Why replace? (462 comments)

Ok, so they don't make a permanent magnet strong enough to lift change out of your pocket.

more than 2 years ago
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HADOPI To Disconnect 60 People In France

Jbcarpen Re:MPAA's Three Strikes (255 comments)

Oh for mod points. Someone mod them up please.

more than 2 years ago
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Privacy Groups Ask FTC For Facebook Investigation

Jbcarpen Re:What for? (68 comments)

Because they keep changing which options are available, what the defaults are, and what the settings mean. Then they also reset to default when they change something. So if you want to have the privacy settings turned up in facebook then you need to check all the settings on a regular basis. You also need to not play any of the facebook games, since a lot of them are just given the same permissions with your account that you are. (unless they've "fixed" this last bit again. It's been how many times now?)

more than 2 years ago
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Florida Reduces Penalties For 'Sexting' Teens

Jbcarpen Re:It may be 2011 (295 comments)

Last I checked, Levitical law doesn't say it's ok to kill your daughter for being asked out on a date.

more than 2 years ago
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"Wi-Fi Refugees" Shelter in West Virginia Mountains

Jbcarpen Re:It's contagious, all right (627 comments)

My 6 year old daughter tests as having an extreme allergy to peanuts. As per doctors orders she hasn't been exposed to peanuts and always has an injector for emergencies (which is a real pain at school since they have a no-drugs policy that won't even let them have emergency medicines).

Zero tolerance policies have officially gone too far.

She loves everything fluffy, but prefers dogs over cats.

Good girl, cats are evil.

about 3 years ago
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Mass. Court Says Constitution Protects Filming On-Duty Police

Jbcarpen Re:Great News! (473 comments)

Really should have logged in before posting. The AC parent is me.

about 3 years ago
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Kentucky Man Builds Bourbon Powered Car

Jbcarpen Re:Use caution. (190 comments)

That's powered by burning combustibles too. They just heat water instead of gasses to transfer the power to the pistons.

more than 3 years ago
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ESRB To Automate Game Rating

Jbcarpen Re:the Questionnaire (119 comments)

But parents can barely be bothered to check the ratings on games as it is. What makes you think they'll be any more likely to read the questionnaire?

more than 3 years ago
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Solar Breakthrough Could Provide Power Without Solar Cells

Jbcarpen Re:Beyond the theoretical limit (223 comments)

So to your first post, the claim is not that you cannot collect all the light nor that you are in fact able to focus it to exactly the intensity of the source. In your system the translucent sphere serves to prevent us from focusing the light anywhere near the intensity of the original source, so there is nothing wrong with that. Further, we would now find ourselves unable to focus the light to a spot any more intense than the surface intensity of the translucent sphere. If one were to envelop the whole system with collectors one could in principle collect all the light, just not at one spot.

If the collectors are all mirrors then I don't see why you couldn't. Admittedly, you can't possibly have a perfect reflector, but there's no reason you couldn't focus all the gathered energy on a single point. If there were a laws-of-thermodynamics reason for that to be impossible than you could never power a laser which has a focal point hotter than the surface of the sun with solar panels. But you can. Yes, that makes a conversion from light to electricity and back, but you lose energy doing so. Therefore it must be possible (within the laws of physics, if not current tech) to focus sunlight down to the same intensity with mirrors.

To your 2nd post, "the system" must include the energy radiated away. The energy is not decreasing, but the entropy is. For a thought experiment, assume you are able to focus the light as tightly as you wish, and heat an object to greater than the source's temperature. You could then connect the two objects together and heat would flow from the hotter one to the cooler because that is what maximizes the entropy. Therefore we had violated the 2nd law when we heated the object above the source's temperature.

would heat flow from the hotter to the colder? Yes. However, it will also radiate outwards from the hotter object in every other direction too. The total entropy is still increasing, it's just doing it more slowly. Congradulations, you just discovered insulation. Homebuilders everywhere thank you.

Your setup with the elliptical reflector would not work. Because the sun has finite size, you would find that at the other focus the light isn't directed to a single point, but at a sphere the same size as the sun. In this most extreme possible scenario, you could heat an object there to exactly the sun's temperature, but no higher. Within that sphere the light is not traveling radially inward to the focus, rather most of the light is missing the focus because it was emitted from the sun's surface, not its center.

Ok, the elliptical reflector only matches the surface temperature. I'd still like to see the proof that something that works better is impossible. You have a link to something with the math? A thought... If I focus a reflector (arbitrarily size) at a point epsilon above the surface of the sun, haven't I just harnessed radiation from the sun to cause a point (not on the surface) to be hotter than it's surface?

more than 3 years ago
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Solar Breakthrough Could Provide Power Without Solar Cells

Jbcarpen Re:Beyond the theoretical limit (223 comments)

Oh for the ability to edit...

Incidentally, it doesn't violate the 2nd law since the total entropy of the system (which includes the collector and the target) never decreases. The system as a whole is still losing energy.

Heck, for that matter, if you were to encompass the entire sun in an elliptical reflector with it at one focus, the other focus point would experience considerably more than the surface intensity. This system still loses energy though, since no reflector is perfect.

more than 3 years ago
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Solar Breakthrough Could Provide Power Without Solar Cells

Jbcarpen Re:Beyond the theoretical limit (223 comments)

There's a theorem in imaging that says you cannot focus a light source to create a beam any more intense then at the surface of what is emitting the light.

Really? If I have a translucent sphere with a smaller spherical source at the center, I have no way to determine by observation what the size of the inner source is, and thus no way to determine the surface intensity of the actual source. Furthermore, if I increase the size of the outer sphere, the apparent intensity at the surface decreases, but if I have a mirror array that fully encompasses it, the total collected flux remains the same.

Does that theorem perchance apply only to refraction not reflection?

more than 3 years ago

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