If you are identifying people from a population of 30 million you need ceil(log2(30 000 000)) bits for your person identifier; which is 25 bits in this case. However you are likely to need to identify corporations as distinct from persons, which will probably take another bit or so. 26 bits per trading entity into a 24-byte (192-bit) TAC goes 7.4 times.

No matter how you put those IDs into the TAC you can never fit more than 7.4 at a time. So if you are a criminal (or privacy nut) who wants to use this system, make sure there are 8 trades between you and any other party you interact with if you want deniability if someone has access only to the TAC used for the final transaction to you. This is not a very plausible tracking scheme because for practical reasons you will need a timestamp and other gubbins to be encoded in the TAC.

Of course, if you have access to all the TACs you only need to fit two IDs in there at a time to build a chain. This is IMO very plausible.

You are probably right; however it does depend on how rapidly it is broken down and excreted by the body. If it is never got rid of, then this test is using a massive under-dose (from my point of view), since I have certainly swallowed 2 tubes-worth of Colgate Total over the course of my life.

If it is eliminated in 12 hours it is a huge over-dose as you say. Somewhere in between these points is an elimination-rate which makes this number entirely appropriate.

I have a bunch of iOS devices and a Motorola XOOM 2. On paper, the XOOM 2 should kick the arse of, say, an original iPad but it does not. I have tried to browse developer.android.org on both, and only the iPad renders the API Reference correctly: the XOOM leaves the lower-right pane completely empty much of the time.

To be fair I should compare it to my iPad 2, in which case it looks even worse. Pages generally take an age to load, and the only way to get acceptable performance is to turn off the flash plugin. This means you don't get any videos on the majority of sites unless you enable debug mode in the browser and tell it to use the UAString of an iPad.

Now you can point out that the XOOM 2 is running Honeycomb 3.2.2 and not the latest greatest Ice Cream Sandwich 4.0.x, but this is not my choice: Motorola haven't issued an update for ICS yet so I can't have it.

Bigger range? Yes.

Better OS? No. What kind of retard thinks perpetuating a destination-information-free back button is a smart idea? I lose 80px at the bottom of the screen for that, and there are always 600px of blackness which could be used to hint where tapping it will take you, but no.

More Open? Maybe.

Lower Cost? If you don't value your time.

Programmable? Nowhere near as easily as iOS. On iOS I only need to care about the current release because everyone likely to purchase an app has 5.0.1. On Android I have to code for the archaic 2.2 to meet the same market share.

Basically if you buy an iOS device Apple can screw you over, but probably won't. If you buy an Android device Google, the device manufacturer and (if applicable) the carrier can screw you over, and 2 out of the 3 probably will.

I can't; don't have mod points today.

I did a similar exam in, I guess, 1999; you could get an A+ in about 20 seconds without looking at the screen. The last sentence advised you to compare what you had done to sample.doc, so I typed:

Ctrl+O sample.doc Enter Alt+F A .doc Enter.

I then went through the paper to verify that there weren't any hidden extras or obvious flaws in the sample (there weren't) and delete any metadata (there was none).

Don't know about Premiere but I do this all the time with FCP X/Compressor. I understand not all players will play them, but my PS3 does.

There is another consideration.

When generating a 1024-bit random number which you hope is prime you take 1022 bits of random data and then put those bits in a 1-sandwich. For a 512-bit random probable prime you use 510 bits of random data. Having generated the probable prime you then test if it is very likely prime and if not you repeatedly add (or subtract, as long as your algorithm is consistent) two and retest until the test says you've found a winner. Because prime numbers are not perfectly evenly distributed (if they were we could find them very easily) there are sometimes large gaps between primes and random generation using this method will (over many attempts) pick primes following unusually large inter-prime gaps much more commonly than primes following unusually small inter-prime gaps.

So far as I know no-one knows what the distribution of 512- and 1024-bit primes really looks like: but supposing there were only 2^30 very-large gaps in the 1024-bit prime space it would be very worthwhile looking for common factors in 2048-bit RSA public keys.

But which was it, the master or the apprentice?

No need to shoot it. I have a Mac: I'll upload a virus to take care of it.

I want to see people in at most one piece after a car accident.

Because http://en.wikipedia.org/wiki/Credit_card#Costs_to_merchants means the merchant owes the card company at least $0.40 (1% of two $20 transactions) and more likely $1.20. Add postage, packing and the cost of paying employees to unpack and refile the discs and record which customer has returned them and you're probably looking at $5 per cycle before you break even.

Frankly I'm amazed netflix et al are profitable at the prices they charge.