Thanks for taking the time to reply in detail. its especially useful as a concerned parent to see the other side of the coin.

I really wasn't aware that ipads were so physically rugged compared to most Android pads. Given that cases are also available for most android tablets, and the approximately 3 android pads to 1 iPad purchase (and therefore replacement) cost ratio, I'm still not really convinced that the iPads increased ruggedness over any/all other Android pads is really as much of a justifiable argument for iPads in schools as you suggest.

I also still think Apple (or Microsoft) is the wrong way to go a a de-facto standard in educational computing tools because vendor-lockin means unavoidably brainwashing kids with the idea that the entirety of computing is only one corporations products. This is an especially bad thing to do when other more open, relatively brand-agnostic and still approximately functionally equal options do exist.

Also I really don't like the idea that this is all still an experiment to see if pads in the classroom are really a good/bad thing or not. My kid's education and therefore his entire adult life is directly at stake here, and there is no chance of a do-over if pads do turn out to be a bad idea.

I myself was similarly permanently fucked in the 1970's by the introduction of an experimental math program called SMP during my critical years at school. After a couple of years it was generally accepted that SMP was a massive cock-up and math teaching goet very quickly reverted back to the classical style, but it was too late for a whole generation of English kids upon which the damage had already been done.

COnsequently If there's still any doubt at all that pads might not be the best approach in school, I'd strongly prefer we take the low-risk option and stay with a traditional method (books etc) that we already know from centuries of experience works well enough.

>> Not an argument pro or anti Apple per se, but standardising on a device means less time spent working out how to set up each device and worrying about app compatibility,

I can certainly see the wisdom in that, but the question is why would a supposedly strapped-for-cash organization pick the most expensive (by far) tablet out there that is also arguably functionally inferior, with more locked-in and expensive apps, and less flexible than many much cheaper (android) pads? It seems so badly ill-considered to even be reasonable to think it could be blatant corruption, especially knowing that literally millions of pad purchases hang on that decision, and that for even reasonably well off parents, $400 is still a very non-trivial sum to find.

>> Ubiquitous tablet computing is very new - but it's not going away and we do need to teach our children how to use it well.

Thats like saying we need to have lessons on teaching kids how to operate a phone or a microwave. How to use a pad takes about 5 minutes for a moderately intelligent adult to work out, and about 30 seconds for the average kid. Its easily just one of the things you learn just by being alive these days.

The school my 9 year old son is at is pushing for parents to donate so they can buy iPads too.

Given iPads are like $400-500 each and a good Android tablet is maybe $150 (and also has access to a lot more useful free software than iPads do), this kind of crap makes it obvious that the education sector is at least very badly managed and more likely very corrupt. I'll bet that someone high up in the education department is getting a very nice fat kickback from Apple.

Just because of this locked-in pro-Apple money wasting mentality I refuse to donate or vote for the very populist local props in my area that want to raise our taxes to give more money to supposedly underfunded schools. Its already very clear that all they are all planning to do with any extra money is blow it on yet more overpriced Apple products.

I'm also having a hard time understanding why a 9 year old kid needs an ipad at school in the first place at all. After talking to the principal and class teachers at my sons school its very clear that they think that ipads in the classroom are somehow a self-evidently good thing, and have no solid justification other than "because tech===future". They are clearly just throwing iPads at kids and hoping something good will come of it, rather than the iPad actually being a necessary tool and part of a larger well-considered strategy with already tested/proven benefits.

I'm sure most kids would say they need an iPad too but if my 9 year old son is anything to go by, at least 99% of them secretly just want it only for gaming or as some kind of trendy fashion accessory.

See I've been there myself. I remember back in the 70's when I was a kid, the excuse/lie that a PC would help with homework was the standard and accepted way by me and all my friends.of getting a new gaming machine.

As such I believe that the onus still lies with the schools to show that iPads in the classroom are not actually just another distraction that comes between the student and the teacher. Assuming they can do that, then they still need to show some real justification why 3x $150 Android pads is worse than 1 $450 iPad with respect to actual benefit in the classroom.

20,000 students with 6 text books will go roughly $12,000,000 for the books. And a lot higher percentage of these go missing, broken or damaged. As the kids are forced to lug around a bunch of books.

Everyone covers up mistakes. Everyone reveals everyone else's mistakes.

The San are pretty much where they were when humanity evolved.

Nothing is objectively known about the airliner. Everything, from Ukrainian air traffic control ordering the plane to descend to a dangerous altitude to who detected what, is all supposition and hearsay at this point.

It is my personal suspicion that the Ukrainian authorities were hoping for an accident of this sort and were intent on placing a civilian airliner in as dangerous a position as possible. Whether that was the case for this specific airliner on this specific flight is unclear.

And I'd argue that Korean Airlines 007 is a better example for this reason. The US had been using civilian airliners for spying on Russia for some time and doctored the evidence to remove Russian pilots radioing warnings to the aircraft in order to make the incident more incriminating than it was. Whether that flight was used for spying, was shadowed by such an aircraft, or merely happened to be in the wrong place at the wrong time, all becomes incidental. The accident was inevitable and the US government of the time was guilty of ensuring civilians would someday die for the benefit of military intelligence. It was merely a matter of which plane would be blown out of the sky and when.

In this case, the Ukranian authorities deliberately downplayed the risk of missile attacks on overflying aircraft and deliberately worked to place aircraft in the most dangerous air corridors that the airlines would permit. That is indisputable. Their opponents were known to be firing on aircraft and had shot several down. When your time to respond is measured in milliseconds, the nearest aircraft identification guide is mere hours away, to paraphrase what Americans often say about cops.

An accident was inevitable. The separatists weren't interested in avoiding one, the Ukrainian authorities certainly weren't. It was merely who would die for someone else's ideals. Whether or not this aircraft was deliberately placed in the path of a SAM battery is unimportant.

Both sides are therefore guilty. Both sides deserve blame.

>> After all, by definition these other universes are not part of ours, so we can't get at them.

I'm not clear how your conclusion necessarily follows from your statement. I'll agree that we probably can't get to them just by changing physical location within our own universe, but that's about it.

>> I think conservation is always a good idea when practical,

Just like every other change, conservation will require some compromise somewhere else, so if you always prioritize other sources of endless short term issues (such as business/economics/politics) above long term planning activities such as conservation, no conservation will ever get done at all.

It always amazes me to see how completely short-term most thinking in the US is. It is truly bizarre to me how most Americans will make excuses for some company permanently damaging the environment to make their CEO's annual bonus even bigger this year.

Its like many Americans apparently feel literally no sense of responsibility to protect the earth we all need to survive on, or care about what we are handing to the next generation, especially if there's a quick buck to be made.

So what type of mathematical/scientific proof theorem covers "proof by fictional story"?

Science Fiction

Fiction: invention or fabrication as opposed to fact.

Minimum wage is actually not the big of a deal.
Most Companies do not pay their employers minimum wage they pay them higher.
Minimum wage usually will go the the Teens first job, And other part time work.
For people who are working full time, they get paid above the minimum wage.
The exception is for Tip workers. Where these laws do not effect as much anyways.

Most of the growth activity is actually in areas that don't pay minimum wage anyways.

In short minimum wage laws do the following.
For the Democrats it make it look like they are looking out the little guy, with a law without any real benefit or cost.

For the Republicans it gives them a talking point against the democrats, explaining how they are not focusing on the big picture and trying to keep jobs.

Nither side is really that effective, or hazardous. Until you get a significant increase in wages. Say $20 minimum wage, where it would be enough for the low end workers to have a significant improvement in quality of life, however at the same time, making many jobs much to expensive to maintain, and force companies to find ways to improve efficiency or outsource.
 

So the $600 pre-refund of taxes that Bush2 put in place (which made a negligible increase in per paycheck take-home) and the SS 2% rebate by Obama (which had a similar result) were useless? No, they weren't, they were identified as having an impact on the economy, even though the money wasn't even in consumers hands when it was announced/started.

Minimum wage has nothing to do with minimum ability. It sets a price floor for labor. The people who lose out are those just above the minimum wage floor who see their less skilled/experienced/tenured coworkers elevated to a higher wage while theirs remains stagnant. (This happened to me, btw, and it sowed a short period of discord in that company)

For businesses with very small margins, the costs will be transferred pretty much one for one. As the margin of the business increases, the cost will be passed on in a proportionally smaller magnitude. People are (almost) never hired because they're "cheap" but because work needs to be done to meet demand. Just as nobody hires people if their taxes go down, or fire people if taxes rise. Might it delay hiring? In some instances it makes greater efficiency more valuable, with businesses investing in machines (which are built by people) instead of people. However most of the time it's just a cost of production. If you need to make more silk shirts and the cost of silk goes up, you don't buy less silk - you buy as much as you need to meet demand.

FWIW I agree vis-a-vis using UDP for a business critical thing. I'd want exemption from responsiblity for any missed packets purely due to the infrastructure in between.

First - the problem with python is that because it's a VM you've got a whole lot of baggage in that process out of your control (mutexes, mallocs, stalls for housekeeping).

Basically you've got a strict timing guarantee dictated by the fact that you have incoming UDP packets you can't afford to drop.

As such, you need a process sat on that incoming socket that doesn't block and can't be interrupted.

The way you do that is to use a realtime kernel and dedicate a CPU using process affinity to a realtime receiver thread. Make sure that the only IRQ interrupt mapped to that CPU is the dedicated network card. (Note: I say realtime receiver thread, but in fact it's just a high priority callback down stack from the IRQ interrupt).

This realtime receiver thread should be a "complete" realtime thread - no malloc, no mutexes. Passing messages out of these realtime threads should be done via non-blocking ring buffers to high (regular) priority threads who are in charge of posting to something like zeromq.

Depending on your deadlines, you can make it fully non-blocking but you'll need to dedicate a CPU to spin lock checking that ring buffer for new messages. Second option is that you calculate your upper bound on ring buffer fill and poll it every now and then. You can use semaphores to signal between the threads but you'll need to make that other thread realtime too to avoid a possible priority inversion situation.

> how do you then ensure that the process receiving the incoming UDP messages is high enough priority to make sure that the packets are definitely, definitely received

As mentioned, dedicate a CPU mask everything else off from it and make the IRQ point to it.

> what support from the linux kernel is there to ensure that this happens

With a realtime thread the only other thing that could interrupt it would be another realtime priority thread - but you should make sure that situation doesn't occur.

> is there a system call which makes sure that data received on a UDP socket *guarantees* that the process receiving it is woken up as an absolute priority over and above all else

Yes, IRQ mapping to the dedicated CPU with a realtime receiver thread.

> the message queue destination has to have locking otherwise it will be corrupted. what happens if the message queue that you wish to send the UDP packet to is locked by a *lower* priority process

You might get away with having the realtime receiver thread do the zeromq message push (for example) but the "real" way to do this would be lock-free ring buffers and another thread being the consumer of that.

> what support in the linux kernel is there to get the lower priority process to have its priority temporarily increased until it lets go of the message queue on which the higher-priority task is critically dependent

You want to avoid this. Use lockfree structures for correctness - or you may discover that having the realtime receiver thread do the post is "good enough" for your message volumes.

> to the best of my knowledge the linux kernel has absolutely no support for these kinds of very important re-prioritisation requirements

No offense, but Linux has support for this kind of scenario, you're just a little confused about how you go about it. Priority inversion means you don't want to do it this way on _any_ operating system, not just Linux.