Author: Eugene

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Blogger hour (or two, or three)

Tonight’s blogger gathering over at the Dog & Duck was pretty good. Had about 13 show up including a couple of new people (Chris from Signal 46 and JJ from I’m not drunk enough for this). Plenty of good random conversation to enjoy over some reasonably tasty bar grub. A little bit of current events, some shared winter stories, the latest bloggings in the lowcountry blog-o-verse, Geoff conducting a few straw polls about UK vs US differences and other topics. And picture taking of course.

They have some fabulously hot wings that I enjoyed. I told the waitress I wanted a dozen wings as hot as they come (they call them Burners). She was a little bit hesitant about it and warned me about the last person who ordered them and ended up sending them back, but I told her to bring them on. Not the absolute hottest I’ve ever had, but pretty close and hot enough to make my nose run a little.

Fun time tonight. Looking forward to the next gathering.

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Holiday spirit

Been here 7 years now, and each year I’m finding it harder and harder to get into a holiday kind of mood. It just never feels like Christmas.

It’s the weather. It’s just not wintry enough for me to get into the right mood for the holidays. Having been born and raised in Edmonton, winter and the accompanying cold and snow are second nature to me. Winter, for me, kicks off the holidays. It means watching the first snowfall, and venturing out into the dark quiet that follows where all the noises seem muffled. It meant Bill Matheson on ITV talking about that “dreaded of all meteorological phenomena, the Siberian High” and the weather in Baker Lake. It was donning layers of warm clothes, filling a backpack with sandwiches, a thermos full of hot chocolate and heading off for a hike through the river valley. It also meant walking to school in skin-numbing -35°C cold on more than a few occasions, but you take the good with the bad.

Now a few flakes falling to the ground is a huge news event and grounds for shutting everything down. A cold day might reach 5°C and just below freezing at night. Is it any wonder I can’t get into the holiday mood when I’m still walking around in shorts?

Don’t get me wrong, I love the mild winters as much as anyone from colder climates would. I love torturing my friends with pictures of me walking on the beach in shorts and a t-shirt on New Year’s Day while they’re freezing their butts back home. Aside from the summers, which are a little toasty for my liking, the weather here is great. It just doesn’t trigger that holiday feeling in me.

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Fast math ops

Just wanted to stash this little tidbit here in case I needed it for something.

This Slashdot article bringing up Origin of Quake3’s Fast InvSqrt(). The original article is a bit of a sleuthing expedition looking for the origins of this little code snippet and makes for an interesting read along with pointing to some other interesting sources.

The algorithm is a remarkable in the way it hides a lot of complexity in a simple looking package. All it does is calculate 1/sqrt(x), but does it very quickly using a cleverly written Newton-Raphson method.

Continue reading “Fast math ops”

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Collaborative writing made easier?

An abstract I wrote up for the little archive project I’ve been collecting data for got accepted as a talk for the SIIM 2007 annual meeting. One of the things they ask accepted presenters to do is to also submit a paper for publication in JDI.

Anybody who’s ever written a paper with more than one author knows that keeping track of all the revisions and changes from one author to another can be problematic, especially if both authors are contributing different sections.

This time I’m going to try something different. I’m going to try using Google Docs for the writing. At least for the content anyway. Google Docs has some neat collaborative functionality and revision tracking capabilities that will probably come in handy. My co-author and I can open the document at the same time, we can both write and even discuss online while we’re editing. Once we get things written, I’ll convert it into a LaTeX document for typesetting and submission.

This should be an interesting experiment.

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Package irradiation

I’ve been doing a little bit of liason work between one of the clinical research coordinators at work and K & S Associates. Someone decided to check out the radiation exposure patients were getting from a particular CT study and ordered some TLD chips for the measurement. Had they consulted us first, we’d have told them it probably wasn’t the best way to get the dosimetry data, but they’d already ordered them.

So calibration chips were irradiated with a measured amount of radiation, and the rest were attached to patients who were then scanned. Then they were sent back for reading.

Normally a report is issued back in a couple of days, but this time there were some strange results. The charge readings K & S were getting were rather low (not surprising considering the amount of exposure they were getting) and somewhat inconsistent. TLD’s normally aren’t used for this kind of application either, so the charge stored on the chips was pretty close to the low end of their ability to read reliably. Normally these TLD chips are used to measure therapy doses, which are several orders of magnitude higher than what they would have been exposed to for this project.

So in the course of investigating the discrepancies, and several phone calls to me to confirm the calibration conditions, the tech at K & S learned that both UPS and FedEx have started running all the packages they handle through an x-ray scanner (one of those DHS screening things I’m sure).

The dose to the packages is far from trivial either. The K & S guy figured the TLD chips got anywhere from 0.5 to 1 cGy (50-100 mrad), which is about the radiation you’d get from 3 or 4 chest x-rays. With the TLD exposures the K & S are used to seeing, this amount of radiation is pretty negligible, but relative to the exposures we were using it’s pretty honkin’ big and can definitely skew the results in a big way.

For most packages this is hardly anything to be worried about, but for radiosensitive things like TLD chips and film it can be problematic. Photographic film, likely a non-issue, although perhaps some minor fogging possible.

Bottom line, if you’re shipping anything radiosensitive or photosensitive, UPS/FedEx might not be the best choices.