typodupeerror

## Comment Re:Bad idea. (Score 1)189

Did you remember to factor the cost of life in?

No, only the gut feeling that 1e-7 per year is a very low risk compared to e.g. the risk of getting killed in traffic (1e-4 per year). What I read is that F3 tornadoes can usually be survived by staying in an interior room; for F4 and F5 you need an underground shelter or reinforced room. The question is more whether it makes sense financially to build the entire house tornado-resistant or even spend \$10,000 on a storm shelter.

telling them that those lives are only worth as much as the insurance.

It is cold, but the value of life is estimated to be around 7 M\$, based on how much people want to be paid to take risks, and on what (government) measures to prevent loss of life cost. Based on that, a measure that increases the survival probability for an F4/F5 tornado would be allowed to cost about \$1 per person per year.

Disclosure: Tornadoes don't affect me as I live in Netherlands. I should be more worried about flooding...

## Comment Re:Bad idea. (Score 4, Informative)189

People who decided not to live in plywood boxes in tornado country, or in wildfire area or below the sea level between a lake and the sea, or below the river level etc should not be asked to shoulder the burden

For hurricanes and floodings, which could devastate large areas in a single event, I see your point. However, a single tornado usually impacts only a small area. The probability of an individual house in Tornado Alley being struck by an F4 or F5 tornado seems to be 10^(-7) per year. Economically, it makes more sense to insure the risk than to build an F4-tornado-proof house. I couldn't find probabilities for F3 tornadoes, but I could imagine that a similar argument holds there.

## Comment Re:This solves nothing (Score 1)233

"one of the more popular ways to generate ANFO is to pump a hole full of chicken shit and then pour in fuel oil"

What are you smoking? ANFO is ammonium nitrate with 6% fuel oil added. Bird droppings don't contain any significant amount of AN.

## Comment Re:Gross, but... (Score 1)618

If a Pharma company invented any of them today there is no way they'd even be allowed for use with a prescription, let alone stocked in 500-count bottles

Here in Netherlands, they are not allowed to be sold in greater quantities than 20 pills, just to reduce the perception that they are harmless. The strange thing with paracetamol toxicity is that it would be trivial to add a harmless antidote against overdosing to the pills, but this isn't done despite the fact that paracetamol poisoning is the most common type overdose of pharmaceutical products.

## Comment Re:More like Gamma-ray devices (Score 5, Informative)113

"300 Mev photons are high-power gamma rays, not x-rays."

No, an accelerator of 300 MeV per meter over 3 mm gives you 1 MeV, or less if the actual field is over less than the chip size. Tuning down from there will easily get you into the x ray domain.

## Comment Re:Infared Contact Lenses? (Score 1)320

Another poster posted a link to a youtube clip of these contact lenses. They come with built-in fake irises, so only the pupil appears dark. Regarding the definition of near infrared: the standard range of visible light is assumed to be up to 740 nm, but I have worked with 800 nm near-IR lasers for many years and they are still visible, although a 1 watt beam appears to be comparable to that of a 1 mW laser pointer at 675 nm. See for yourself here for the sensitivity curve: http://cvrl.ioo.ucl.ac.uk/cvrlfunctions.htm (under fundamental spectra or luminous efficiency).

## Comment Re:Gross, but... (Score 1)618

You seem to be stating that if I accidentally took 3 paracetamol pills,

See https://en.wikipedia.org/wiki/Paracetamol_toxicity . Short version: maximum recommended intake is 3 grams per 24 hours; a single dose of 10 g can be fatal, as are a few days in a row at 10 g per day spread out over multiple smaller doses.

## Comment Re:Infared Contact Lenses? (Score 1)320

if you put one layer on top of the other, even transparently, I am not sure.

Ink on paper works like this: the paper acts as a diffuse reflector; the ink absorbs light for certain wavelengths, but the light that is not absorbed passes through without changing direction. Putting two layers of ink with different absorption wavelengths on top of each other will result in only the wavelengths that are *not* absorbed by either being reflected by the paper. This is the whole point of the CMY(K) printing process.

Maybe you are thinking of paint, which typically includes its own reflective particles. But paint needs to be applied in a much thicker layer (0.1 mm or 4/1000 inch) to do its job, so it would be rather noticeable; the deck of cards would be 5 mm (1/4 inch) thicker and you would be able to feel the paint with your fingertips.

## Comment Re:a few laws of physics problems here (Score 1)90

But if you collecting acoustic data over a period of time, transient sounds (noise) average out, and the loud peak (gunshot)

Well yeah, if you want to pinpoint the source of a massive transient or the source of an annoying continuous whistling sound or a never-ending repeated playback of some secret message, this sensor could work. But it would not be very useful for recording private conversations.

But look at it from this side: a normal microphone measures pressure as a function of time, i.e. p(t). If their is only one source of sound, you can reconstruct the sound wave at the source. If there are two sources, it becomes impossible to distinguish. This transducer will generate three signals: vx(t), vy(t), and vz(t). If you have three sources of sound, then you could, with proper tuning and calibration, disentangle the signal and reconstruct the output of each of the sources individually. As soon as there are more than three sources, say in a pub with 20 conversations going on at the same time, you cannot do this anymore simply because there are more bits of data being transmitted than being transduced; you would need to solve a system of three equations with twenty unknowns.

## Comment Re:Infared Contact Lenses? (Score 1)320

... a well chosen filter can indeed make two light bundles look different that look exactly the same without the filter.

Yes, that's what makes the skin look weird under cheap white LED lights and older fluorescent tubes. This effect is called metamerism.

But unless you print the entire back sides of the playing cards with a pattern of two different inks that look the same under the casino lights but look different through your filter, you cannot use this to label cards after the fact. Ink absorbs light, so when applied to white paper, the surface will look darker than before, no matter what.

## Comment Re:Infared Contact Lenses? (Score 1)320

...IR detector card has a strip of chemicals on it that glow pink when a remote control is aimed at it.

That is not frequency doubling, but a special form of phosphorence. Visible/blue light is used to generate long-lived excitations in the molecules. Infrared then excites them further to a slightly higher level with a short excitation lifetime; as that excitation decays, it emits visible light. It shares the disadvantages of common phosphorence: it is not directional.

## Comment Re:Infared Contact Lenses? (Score 4, Informative)320

Near-infrared ink (as posted by an AC) sounds like the most plausible approach. In the range 700-750 nm, the sensitivity for light is less than 1% of the peak sensitivity. You would need (1) a proper long-wavelength-pass filter, (2) ink that absorbs only in this wavelength range, and (3) an illumination source that is heavy in this wavelength area (e.g. halogen/incandescent lights).

For the naked eye, the ink would appear as a very pale cyan color. With a proper filter, everything would look very dark due to the filter removing 99% of the visible light, but the ink would show up with much more contrast. Effective long-pass filters do exist, e.g. Schott RG695 or RG715 for a 695 or 715 nm cut-off, respectively. There are plenty of suitable dyes. Probably you would want to have this filter only on one eye, otherwise the world around you might appear very dark.

The other theories that have been posted here make no sense.

Frequency-doubling needs extremely high intensities (like a high-power or focused low-power laser beam), which would render you blind. Moreeover, frequency-doubling requires proper phase matching, which boils down to the requirement of an exact combination of angle and wavelength.

Polarizers: it is not possible to turn unpolarized light into polarized light without throwing away half of the light. Once the light is polarized, the polarization direction can be manipulated with optically active materials, though.

A high-refractive index coating would not only change at the Brewster angle, it would make the cards much more glossy as seen from any angle. It is not possible to make the refractive index change dramatically within a short wavelength range without changing the absorption as well, so the glossiness would appear in visible light as well.

A phosphor coating would not work for several reasons: phosphors do not emit the phosphorence in the same direction as the absorbed radiation; they always convert from short wavelengths to long wavelengths, and the phosphorence light would be completely out of focus.

## Comment Smart Wifi Toggler for Android (Score 2)189

This article actually starts as a question, but there are only a few posts addressing practical ways to deal with it. I for one use Smart Wifi Toggler on Android. It decides when to switch on Wifi based on cell tower locations. I use it mainly because it saves some battery.

## Comment Free electron lasers as EUV source (Score 1)32

Average power is low now, but there is a clear path to at least kilowatt average powers (see the LBNL NGLS) and 10s of KW are pretty straightforward.

A clear path to kilowatt powers, that's sounds a bit like the stories about the EUV sources years ago. Reality turned out to be quite a bit harder...

There has been quite a bit of work on EUV / Xray optics, but again the parts are really expensive (an X-ray mirror runs \$1M. )

Are those normal incidence or grazing incidence mirrors? For proper imaging, you need to image one area onto another area with low aberrations, not one focal point onto another focal point. This is far easier to do with mirrors designed for normal incidence than for grazing incidence. Even then, it turns out that you need about 10 reflections from the EUV source to the silicon wafers; it's because with every reflection you lose about 1/3 of the power that we would like to have a kilowatt to start with. If the reflection losses are a bit larger due to a larger number of mirrors or a higher per-mirror loss, then you need to start with even more power.

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