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Comment: Economic risk (Score 1) 54

by Michael Woodhams (#47717771) Attached to: How Argonne National Lab Will Make Electric Cars Cheaper

Some new game changing battery/supercapacitor breakthrough might be just around the corner. If so, all that investment in the battery megafactory could get wiped out. Ditto with investing in lithium mining.

So the megafactory might be still happily minting money 25 years from now, or it might be nearly worthless 5 years from now. Presumably this means we'll be paying a risk premium on lithium and lithium batteries. It seems to me that it would be smart for Tesla to be investing in the very technologies that might disrupt their factory, as an insurance policy. That way, if the fortune you've invested in the factory evaporates, hopefully you'll have a new replacement fortune due to having a stake in the new technology. However, this strategy requires that you have the funds for this speculative investment, and has you encouraging the very research which will ruin your factory investment. (Also, maybe you won't have invested in the right places and won't have a stake in the new technology.) In the case of Tesla, they are major consumers as well as (soon to be) major manufacturers of batteries, so there is an additional up-side to investing in the hypothetical tech breakthrough.

Is lithium mining expanding fast enough to feed this factory when it comes online?

Comment: Re:how are cops like bank executives? (Score 4, Interesting) 223

From TFA:

“Now we’re going to give you what you deserve for meddling in our business and when we finish with you, you can sue the city for $5 million and get rich, we don’t care,” Lt. Dennis Ferber said, according to the suit filed in Brooklyn Federal Court.

It appears the police followed exactly your logic. However if that statement is substantiated, Ferber's boss would be seriously derelict in their duty if they didn't fire him for this. He's publicly stated that he doesn't care about knowingly causing a multi-million dollar liability for his employer. IANAL, but I expect that should these cops not get punished and pull a similar stunt again, the city would open themselves up for greater punitive damages, as they'd let employees with a known track record of rights abuse continue working where they were likely to abuse again.

It would be good to see criminal proceedings, but I doubt it will happen.

Comment: Re:Not gonna happen (Score 2) 111

Most metals are not ferromagnetic, and so are not held in place by magnets. I'm pretty sure neither indium nor gallium are ferromagnetic.

As they are good conductors, metals do develop eddy currents in a changing magnetic field, which heats them. (Try dropping a magnet through a narrow aluminium tube. The energy loss due to eddy currents will slow its fall considerably.) If you had this liquid metal inside you, having an MRI scan might be a really bad idea - I wouldn't rule out the possibility that the bits of you in contact with the metal could get cooked. This would be a considerable drawback in a cancer treatment. It would be no different than having metal inside you for other reasons - e.g. titanium pins used in surgery. Does anyone know how those react to MRI?

Comment: Big lump of dead cells (Score 1) 111

Aside from the risks of what happens to the liquid metal after it's done its job, you also end up with a big lump of dead cells inside the body, which can't be good. On the other hand, presumably successful radiation therapy has the same result, and the result doesn't have to be 'good', it just has to be 'better than having a tumor'. Would someone with actual medical knowledge care to comment?

Comment: Re:A little behind the times (Score 1) 315

by Michael Woodhams (#47628401) Attached to: Why the "NASA Tested Space Drive" Is Bad Science

I agree. The theory can be rubbished in very simple terms: The inventors assume no new physics, and conclude their device will violate conservation of momentum. All the 'input' physics conserves momentum. Therefore their analysis is wrong.

If I give you a list of numbers which are all even and ask you to add them up, and you give me a sum which is odd, I know you've messed up. I don't need to check the details of your adding and point to exactly where you went wrong. This situation is analogous.

So if the device *does* work (which I very much doubt) it will be pure wild coincidence, not due to any cleverness on the part of the inventors.

(Note: these comments are based on the description of the EmDrive in New Scientist some years ago. I am unfamiliar with the Cannae Drive, so I don't know if it has the same theoretical flaw. If it *does* end up working, I will revoke my vow to never again subscribe to New Scientist.)

Comment: Link to abstract (Score 4, Insightful) 63

by Michael Woodhams (#47555199) Attached to: UK Team Claims Breakthrough In Universal Cancer Test

Here is the abstract. The actual paper is behind a paywall.

"ROC analysis of [the test statistic], for cancers plus precancerous/suspect conditions vs. controls, cancer vs. precancerous/suspect conditions plus controls, and cancer vs. controls, gave areas under the curve of 0.87, 0.89, and 0.93, respectively (P<0.001). Optimization allowed test sensitivity or specificity to approach 100% with acceptable complementary measures."

The ROC curve has area under it of 1 for a perfect classifier and 0.5 for wild guessing. This is a more useful measurement than the p-value. (E.g. if I look at height vs sex for humans, it won't take too big a sample to get a great p-value for there being a difference, yet classifying people as male/female depending on whether they exceed some height threshold is a very poor diagnostic system.) I don't have much of a feel for how good ROC area of about 0.9 is for a medical test. I'd guess it is good enough to be useful, but you'd not want to rely on that test alone.

Comment: Re:I don't see the problem. (Score 4, Informative) 667

by Michael Woodhams (#47497149) Attached to: Russian Government Edits Wikipedia On Flight MH17

The plane was 10km up. It wasn't shot down by something bought for $50,000 from Bob's Quality Used Implements of Death and Destruction and delivered to you by a courier van. The suspected weapon system requires at minimum one tank sized tracked launcher vehicle, and for full capability it requires three such vehicles. This is way out of Bob the arms dealer's league. Although I'm pretty much guessing here, the missile alone I expect would cost over a million dollars to manufacture.

Having said that, the possibility exists that rebels with military experience seized such a weapon system from an overrun Ukrainian military base.

Comment: Re:Neandertals and light skin (Score 2) 133

by Michael Woodhams (#47374319) Attached to: Tibetans Inherited High-Altitude Gene From Ancient Human

Immune system genes are often under balancing selection - i.e. the rarest alleles are favoured (until, due to this favouring, they cease to be rarest, then other alleles are favoured.) An infusion of new different alleles from Neandertals could be favoured simply because they are different, not because they are evolved to European conditions.

Testing between these hypotheses seems difficult. The 'balancing selection' hypothesis predicts that the genes will readily spread back into Africa, whereas the 'evolved for European conditions' predicts they will not. The problem is that you need some neutral mutations that arose in Europe at the same time as a 'control' for comparison purposes. I'm not sure how to identify such mutations, but I expect it could be done.

Comment: Neandertals and light skin (Score 3, Interesting) 133

by Michael Woodhams (#47374055) Attached to: Tibetans Inherited High-Altitude Gene From Ancient Human

There is another obvious point in history where such a gene transfer could have occurred. European conditions favour light skin, and Neandertals had been hanging out there for some tens of thousands of years before modern humans turned up and so had evolved light skin. These newcomers, having recent ancestry in Africa, were probably dark skinned. Interbreeding could easily have introduced the beneficial-to-European-conditions light skin mutations into the modern population.

My memory of the literature (which I have followed just a little bit, not closely) is that this did not happen - genetic analysis shows that modern Europeans and Neandertals acquired light skin through different mutations. However, Wikipedia says this is still under debate.

Comment: Re:Careful (Score 2) 116

by Michael Woodhams (#47365287) Attached to: Renewable Energy Saves Fortune 100 Companies $1.1B Annually

This is a silly objection. That isn't how payback times are used.

Payback time is a quick indication of return on investment. You then compare that return on investment with the other options available to you, such as leaving the money in the bank.

If you included interest rates in payback time, you'd need to be constantly adjusting it as rates changed, and it would differ for different entities depending on their access to finance. Instead you keep it simple, and each entity has its own idea (based on circumstances and current interest rates) of what the effective payback time is of leaving the money in the bank (or not borrowing it, or investing it in other opportunities.) (For example, a start-up is likely to require a very short payback time - they're strapped for cash and are trying to get their Big New Idea to market where they hope it will make a fortune. Up-front money is then very expensive compared to down-the-road money. For them, it may make sense to lease a supercomputer even if buying it would have a two year payback time.)

What is missing from this analysis is depreciation of assets. After 6.4 years, money in the bank will have depreciated much less than the solar cells. Payback time is a rough guide - it tells you whether it is worth your while doing a more detailed analysis including finance cost, depreciation, tax implications etc.

If a 6600 used paper tape instead of core memory, it would use up tape at about 30 miles/second. -- Grishman, Assembly Language Programming