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Comment: Re:Neutrinos? (Score 4, Interesting) 267

by volsung (#41201145) Attached to: Radioactive Decay Apparently Influenced By the Sun

Since you mention neutrinos, it is also worth noting that there was similar discussion (5 or so years ago) as to whether we can observe periodic variation in the number of neutrinos seen on Earth using various experiments. (Note that periodicities in neutrino rates are not what physicists call "neutrino oscillations". That's an entirely different effect.) Those papers claiming a periodicity included one of the authors on this study of radioactivity decay, and the analysis techniques were disputed by other papers as giving an unacceptably high rate of false positives. The experiments presented counter-analyses showing no significant signal once the probability of false positives was dealt with. (Disclaimer: I was tangentially involved in one of those papers.)

I haven't looked closely enough at the radioactive decay papers to see if the same issue has cropped up again here, but the neutrino periodicity argument is a good example of how these signals can fall apart under closer scrutiny.

Comment: Re:This is exciting (Score 4, Insightful) 267

by volsung (#41201083) Attached to: Radioactive Decay Apparently Influenced By the Sun

Another relatively easy control would be to conduct simultaneous experiments in the northern and southern hemispheres. Many external effects (like temperature) would be 180 degrees out of phase, while the distance from the Sun will be essentially the same for the two experiments.

Comment: Re:This is exciting (Score 4, Informative) 267

by volsung (#41201063) Attached to: Radioactive Decay Apparently Influenced By the Sun

I think the problem is that the link is not yet established. What we have is a link between count rates in a detector observing a sample of some isotope and time of year, which no one disputes (we reasonably assume they are not making up their data). The argument is whether you can make the inductive leap to the claim that radioactive decay rates depend on the amount of solar radiation. As shown in some of those papers above, other experiments don't (like the test with the MESSENGER probe) show the effect you would expect if solar radiation were the cause.

Even if we do find there is an external influence on decay rates (which would be pretty nifty), that definitely does not imply that the times of individual radioactive decays are predictable.

Comment: Re:This is exciting (Score 4, Informative) 267

by volsung (#41200891) Attached to: Radioactive Decay Apparently Influenced By the Sun

This argument about solar influence on nuclear decay rates has been going on for a few years now. The experimental issues are hard to interpret, because you have to be able to rule out external influences on your counting apparatus. It is extremely hard when the period of your signal matches the orbit of the Earth, which aliases all sorts periodic behavior that has nothing to do with new physics. There are seasonal variations in temperature, cosmic rays, the voltage delivered by the power company, foot traffic near your lab, etc, etc. Verifying that none of these things can possibly influence your results is what takes all the time.

A semi-random selection of earlier papers on the subject:

"Experimental investigation of changes in beta-decay count rate of radioactive elements" (1999):
Claiming 24 hour and 27 day periodicities in the decay rates of cobalt-60 and cesium-137
http://arxiv.org/pdf/hep-ex/9907008v1.pdf

"Power Spectrum Analyses of Nuclear Decay Rates" (2010):
Reports of an annual periodicity in the decay rates of chlorine-36, silicon-32, manganese-56, and radium-226.
http://arxiv.org/abs/1007.0924

"Solar Influence on Nuclear Decay Rates: Constraints from the MESSENGER Mission" (2011)
A study of cesium-137 decay rates on a spacecraft going to Mercury show no change as the spacecraft travelled closer to the Sun.
http://arxiv.org/abs/1107.4074

"Search for the time dependence of the 137Cs decay constant" (2012)
Cesium-137 decays in a detector underground (shielding it from most cosmic rays) show no significant periodicity, with limits much lower than claimed signals.
http://arxiv.org/abs/1202.3662

"Power Spectrum Analysis of LMSU (Lomonosov Moscow State University) Nuclear Decay-Rate Data: Further Indication of r-Mode Oscillations in an Inner Solar Tachocline" (2012)
Studies of strontium-90 decays show a variety of periodic variations, ranging from 0.26 per year to 3.96 per year.
http://arxiv.org/abs/1203.3107

This list goes on and on. There is hardly any consensus on the issue.

Comment: Re:I don't see it (Score 1) 139

by volsung (#41199835) Attached to: Windows Has a Future In RAM: AgigaTech Samples DDR3+Flash DIMM

One of the advantages laptops have over desktop computers is effectively a built-in, relatively lightweight UPS. When someone kicks out the cord on my laptop, I don't even notice, but on my desktop, that would be very annoying. If some upgraded RAM/Flash + operating system support would allow hibernation on a desktop when the power was cut, that would be very handy. Some thought would have to be given to how this should interact with filesystems, since the hard drive would instantly lose power as well. Any writes in progress would have to be reattempted when the system booted up again.

Of course, the main problem is that laptops are quickly becoming people's desktops, and that might kill the market for this before it even starts.

Comment: Re:Variable rate of decay? (Score 1) 199

by volsung (#41001507) Attached to: Advance Warning System For Solar Flares Hinges On Surprising Hypothesis

Just FYI: Nearly all physics articles from the last 15 years are posted in "preprint" form on the arXiv before submission to a journal. The arXiv is completely free, and is where nearly all physicists read papers from, rather than from the journals themselves.

Just Google the title of the paper you are interested in, and you usually find the preprint version:

http://arxiv.org/abs/1205.0205

Comment: Re:Groupon needs a staggered approach (Score 1) 611

by volsung (#38138696) Attached to: Baker Has to Make 102,000 Cupcakes For Grouponers

There already is a simple limit scheme available, but this business owner chose not to use it. Presumably this failure was a combination of lack of due diligence by the business owner and some pressure from Groupon sales staff. Groupon assumes that few businesses will ever offer a deal through them twice, so their strategy seems to be squeezing as many sales out of them as possible, margins and customer quality be damned.

Hopefully stories like this will make more small business owners aware of the risks associated with massive cut-rate promotions through sites like Groupon.

Comment: Re:Wait for Top Gear (Score 1) 426

by volsung (#37586184) Attached to: Tesla Model S: 0-60 In 4.5 Seconds

Moreover, why do we need to adopt Highlander Rules here? An electric car is a practical replacement for people whose driving habits don't require a fuel station on every corner. That doesn't work for everyone, and those people shouldn't buy a pure electric car.

However, complaints about the range issue do highlight one of the real problems in selling electric vehicles: discomfort in giving up some capability regardless of how often you actually use that capability. I owned my first car (quite the beater) for two years, and drove it more than 150 miles from home exactly once. Would I have been happy with a vehicle that had a 300 mile range? Sure. (Would I have spent $200k rather than $2k? No, but I would not have spent that much money on a car, even if I never had to refuel it.)

Comment: Re:Editing. (Score 2) 359

by volsung (#37370676) Attached to: Why We Don't Need Gigabit Networks (Yet)

For the software end of this, check out CrashPlan. It saves incremental backups of your system to external hard drives, your friend's computer (also running CrashPlan) and/or the CrashPlan servers. It's great stuff, and works on Win/Mac/Linux. Plus, your backup data is encrypted before it leaves your computer, so you don't have to worry about the security of your friend's computer. (By default, your data can be decrypted on the CrashPlan server in order to support web access to your files. If you don't want that, you can set an encryption password that CrashPlan can't access, and then no one can see your data outside of your computer.)

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