Friday 30 March 2012

Not So Ridiculous After All

Caution: (very minor) spoilers for Dracula and Dracula the Undead.

One thing that always bothered me in Dracula was that Lucy was given three blood transfusions, with the three most convenient people as donors, with no question of matching the blood types, with no ill effects. Of course, Stoker couldn't have known that that was a problem, as blood types were discovered shortly after Dracula was published. Indeed, that's a plot point in Dracula the Undead.

But then it occurred to me that depending on your blood type, you might have a pretty chance of a random person being compatible with you. Indeed, if Lucy happened to be AB positive, she could have transfusions from anyone.

So I finally got around to working out the odds of a random person receiving blood transfusions from three different random people, and surviving.

Using some information about distribution of blood types from this page of the NHS Blood and Transplant website, and making the assumptions that that hasn't changed hugely over the past hundred-odd years, and that no-one involved had any rare blood types, I calculated Lucy's chances:

You can receive blood from anyone who doesn't have any of A, B, or Rh that you don't -if you have it and they don't, it's fine.
Add up all of the compatible percentages, and you get the percentage of people who can donate blood to you.
Divide by 100 and you have the probability of a random person being able to donate to you.
Cube that, and the result is the probability of three random people all being able to donate to you.

But that's the probability given that you have a certain blood type, and we don't know Lucy's blood type, so we need to calculate that figure for each blood type, and than calculate:

(probability of having blood type)*(probability of three people being able to donate to blood type)

and add up the results.

I came out with 0.2970, or 30%, to the nearest %, which is not a fantastic chance IRL, but more than plausible enough for fiction, I think.

Wednesday 28 March 2012

At the Bottom of the Garden

... there used to be a pond. To give that name to what there is now would be insulting to all the garden ponds out there. We have what can only be described as a garden swamp.

It's too small to be self-sustaining: there are no fish or waterbirds to eat the plants, so left to its own devices it gets overgrown. I remember once we did clean it out thoroughly, or rather, my dad did, while us (then quite small) children lent assistance which was doubtless more enthusiastic than helpful. but since then it has been allowed to drift slowly into a state of ... indescribableness.

These days, about twice a year, when I'm home in the Easter and summer holidays, I decide to clear it out. i spend some time each day for a few days pulling out dead leaves and twigs and moss and grass and silt and excess pond plants and heaven only - and possibly not even heaven - knows what else and piling up what must be nearly my own bodyweight in assorted muck. The pond is around a metre and a half across, and no more than half a metre deep. The heaps I extract make no obvious difference to it.

Then I give up. I get fed up, or disgusted, or the weather turns, or other matters press. The back right corner is nearly inaccessible thanks to overgrown flowerbeds, and by now looks more like compost than water - with an inexplicable Christmas-tree bauble that certainly never belonged to us, but the other three-quarters is bounded by lawn, and it is from there that I remove a few cubic feet of rubbish twice a year. Invariably, when I next attempt the task, it is a worse state than when I started last time.

This week I've been having another go at the job and this time (as usual) I am determined to actually finish it, or at least make a noticeable difference.

There is more moss and grass growing in there than actual pond-plants. It is monstrously choked with dead leaves, mostly bits of the conifers that overlook it (they were recently trimmed, which may be why there's more than usual in the water). I found a lost golf-ball, which was at the same time invisible beneath the matted vegetation and supported by it.

The yellow-flowered plants - which I think are marsh marigolds, but I couldn't swear to it - that used to stand tall in the centre of the pond now spread throughout, their long stems horizontal, submerged, leafless, root-trailing and in many places indecently bleached shocking white from lack of light, ring the whole pond in a tangled mass, clogged by moss above and fine silt-gathering roots below. The whole thing is a solid mass, several inches thick and intertwined with everything in the pond.

The silt is incredible. I haven't yet dared to plunge my hands into the bottom, where unknown terrors lurk - decaying frogs spring to mind - but the stuff that clings to the roots of the plants is bad enough. It is exceptionally fine, and if I didn't know what it was the soft and silky feel would be quite pleasant. As I pull each handful to light, I see things in it that I would rather not. Some are crawling, some look like eggs, some are wholly unidentifiable. And to talk about the smell of that silt is to waste a perfectly good opportunity to use the word 'stench'.

We have a breeding colony of frogs, but this year I wondered if they'd all died, perhaps at the claws of Poppy or one of the many other cats that haunt our garden, or simply left in disgust, as we didn't appear to have any frogspawn this year. But the pond must just have been too choked up for it to be visible, because the latest crop of tadpoles are swimming around, newly-hatched, and I feel like a murderer. I try to avoid pulling them out with the filth, but I'm certain to kill some.

And when I decide to call it a day, I still have to clean myself up. The smell is always unwilling to let go of my hands, even after somewhat more diligent washing than a surgeon scrubbing in for theatre. Once I came down with a stomach bug the day after, and I doubt it's a coincidence. And tonight I had a disagreement with the cat - equal fault on both sides, I think - which resulted in my worst savaging yet (don't worry: still very superficial injuries, and from past experience my immune system is perfectly able to cope with whatever might be in Poppy's mouth) and I'm not sure I want my lacerated and punctured right arm anywhere near that muck, so this may possibly be it for this bout. I'll see. If you never hear from me again, assume I've died of septicaemia.

Tuesday 27 March 2012

Pearls of Wisdom: Grammar Nazis

I haven't done one of these for ages. Hmmm. Anyway:

 Let he who is without typos cast the first sarcastic reply.

Or she, obviously.

Wednesday 21 March 2012

Ten Rules for Writing Fiction

First of all, I apologise to any regular readers for the longer than usual silence. But I'm here now.

Today Twitter led me in the direction of a rather good Guardian article. I rather like a lot of what was in it. so I thought I'd share it with you.

Sunday 4 March 2012

Playing God

I'm a mathematician and a writer. It sometimes occurs to me that both of these things are sort of like being God.

In maths, you get to say 'Let there be...' and there is, Old Testament style, which feels awesome.
And unlike every other branch of science, maths is Bottom Up. Other sciences are Top Down: you look at the world and try to work out how it fits together and does what it does. In maths, you start from the very building blocks and find out what you can do with them. It's as if a physicist started with the idea of quarks (or whatever they are made up of, if they aren't as small as you can go), and deciphered how atoms and molecules and everything bigger worked from there. Which is presumably what God does, if there is a God (I believe there is, but I have absolutely no problem with it if you don't).
This means that you can prove things in maths: unlike in other sciences where the best you can get is a theory (that is, a comprehensive explanation supported by a great deal of evidence) that is the best explanation anyone can find and fits all the evidence is the nearest you can get to proof, and still could, potentially, turn out to be wrong, in maths you can prove things, and then you can be 100% certain that it's not possible for it to be otherwise.

As for being a writer: I create worlds, and people to fill them.
I put a great deal of effort into it, and make sure that things work - you already know about my scientifically plausible vampires, and just recently I've been looking up pterosaurs to design a basilisk, which in my version is a giant flying snake-creature, for another story - and my characters are all created, to some extent, in my image, because it's not really possible to make someone up without putting some of yourself into them.
And you know, I do seriously wonder sometimes if my creations are real to themselves: I don't see why not as they're pretty real to me. And then I wonder if it's wrong of me to put them through all the things I do, although it's not really possible not to: you can't have a story without conflict, and you can't have conflict without suffering. And stories have a mind of their own, so if they decide on one route, you can either follow, no matter the consequences, or abandon it entirely.

of course that leads to the question: if God is an author, does that make Christianity the biggest work of self-insert fiction ever?