Things are looking up (by alaric)

Sarah went in for a scan yesterday to look for blood clots in her lungs - and they didn't see any!

So either the past week of anticoagulants have dissolved them, or the clots are/where only in her legs, or it wasn't clots at all.

But she's definitely looking better; she's getting more lively again, and gets breathless less easily!

The scan was interesting. It was one of those where they inject you with a radioisotope, then use a sensitive imaging scintillation detector to get a map of where the isotope has ended up in your body.

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We’re still alive! (by alaric)

Today's bombings, and the refreshing efficiency of the emergency services in dealing with it, have reminded me that I planned to get back with St John Ambulance, and do some more volunteering to do first aid at events.

Right now, they're officially saying about 40 dead and 700 injured.

I wonder if the overall death rate in London today is higher than usual, because of the extra 40, or lower, due to the disruption meaning less road deaths and murders?

I presume that people are just resigned to accept stabbings and shootings and road accidents and falling off of ladders and fires - all of which, just like a bomb on public transport, can happen to people like you or somebody you know, without warning; and can either kill instantly, or slowly, or maim and disfigure. Yes, it is more alarming when lots of people die in one event rather than hundreds of little ones here and there, and it's a lot more alarming when that one event is a deliberate action, but shock and horror is what terrorists are trying to do - please do whatever can be done to resist them!

And please please please don't let the Government use this to rush in a load of new liberty-reducing anti-terror laws of questionable usefulness...

Blood clots (by alaric)

The doctors are now pretty sure there's blood clots lurking in Sarah. They may get the scan tomorrow, which will reveal how many and where.

They say clots are considered a dangerous condition. Not for the baby, which of course they can pluck out with surgery if Sarah seems unable to keep it supplied with blood for any reason, but for Sarah - they can dislodge and zoom round the circulatory system, then wedge somewhere, causing heart attacks or brain damage; the kinds of things that kill people or turn them into vegetables.

Sigh. I was just beginning to think that the part of my life where the things most precious to me were regularly taken from me due to things beyond my control might have been coming to an end. Perhaps not.

Diagnosis? (by alaric)

Well, today's news is that Sarah had to endure the insertion of a cannula and the taking of an arterial blood sample, which involves a special extra-painful needle.

However, after much consultation of doctors, they now think she has pneumonia, and probably blood clots too - either in her legs, lungs, or both.

So she will be there at least a few more days while they give her more antibiotics, along with injections to thin her blood, and take her for an ultrasound scan of her kidney (which appears inflamed) and some kind of mysterious scan (apparently it's not an MRI scan, but it had better bloody not be a CT scan with a baby inside her - and a CT scan wouldn't be that good for soft tissue work, would it?) for blood clots.

But the stress is starting to show on both of us now - when she was told she was having another arterial blood sample today (which was very painful the last time), she got a bit tearful, and when I visited this evening, she really didn't want me to go home. And I'm starting to fold under the strain of knowing I need to move house at the end of the month, while at the same time everyone I do any work for seems to have decided that the end of this month would be a REALLY GOOD TIME to put a deadline.

You see, I normally thrive in critical situations; I become rational and quick-thinking when other people panic. But, it would appear, I can only maintain this for four days in a row before I start to do some very out of character things like snapping at people.

Avalanche functions (by alaric)

One way of looking at the design of a cipher is that you are taking a small fixed-block-size cipher of known good design, and finding a way to extend the security of that small block cipher to a larger block, potentially variable sized.

For example, stream ciphers (and their close cousins, 'cipher modes' like OFB, CFB, and so on) work by splitting the message into smaller blocks and applying the mini-cipher to each block in turn; but if they did that with the same key each time, the result would not be particularly secure for various reasons - weaker than the mini-cipher - so they use various means of causing interrelationships between the mini-blocks.

This brings about a property known as "avalanche"; namely, changing a single bit of the input should cause 'cascading changes' such that (on average) half of the output bits are changed, meaning that the new output is as related to the old output as two independently chosen random bit strings.