Thursday Jan 05, 2006

My birthday present

This year, for my birthday I'm getting a trip to Las Vegas for TAM 4. This is a critical-thinking conference, and they have a bunch of great guests. I'm expecting to have a wonderful time, and will almost certainly post a trip report at a later date. Almost all the spaces have been sold, so if you'd like to go, hurry up and register!

Wednesday Sep 28, 2005

Brain-controlled computers

Nature is reporting on their news pages about an electrode-array-bearing cap that a person can wear, which allows them to navigate a virtual environment by visualising walking. Although it takes practice to get used to the system, the breakthrough here is that you don't need to have the electrodes implanted. Just having them held onto your head is good enough. Meanwhile, another group has been using trans-cranial magnetic stimulation to produce an artificial feeling of motion. So that's the start of neural input and output. Maybe I really will live to see cyberpunk technology come true. That would be cool.


Wednesday Sep 21, 2005

The Truth Machine

According to a news report on Nature's news page, some proponents of fMRI are now claiming to be able to reliably detect lies by monitoring brain activity. This seems like it might actually be a plausible "lie detector" — unlike the polygraph, which has been proven time and again to be unreliable. I'm not sure what the implications of this are. Certainly one can imagine situations where being able to demonstrate that you are telling the truth about something would be very useful. But suppose it turns out that you don't need to stick someone's head into a giant magnet to do this. Suppose any random social interaction could be measured for degree of truthfulness by either party, using a small potentially concealed device. That could change our world a bit, I'd think.

Anyway, the article made me think of a novel I read a while ago, called The Truth Machine, by James L. Halperin. If I remembered a darn thing about it, I'd give you a mini-review right here, but I don't. So I'm putting it on the "to read" pile. I'll be interested to see how Halperin thinks society would be changed by such technology. (If I recall correctly, the technology was restricted to judicial uses in his novel.)

Wednesday Aug 24, 2005

Pitch-specific neurones found

There was an interesting piece in Nature today about the discovery of pitch-sensitive neurones in primate brains (the study was done on monkeys, and I'm glad I wasn't one of those monkeys...) Apparently there is a region which has specific neurones which fire in a kind of "pitch map". I suppose this is vaguely similar to the sensory homonculus region, in as much as there's a physical mapping of cells in the brain from something external. The fascinating thing is that the cells react to the percived fundamental frequency of a note. Humans typically will hear a note as having a particular pitch based on the harmonics present, even if there is no energy in the fundamental frequency. As I understand it, this isn't the case for the hair cells in the cochelea which actually detect the sound. So what we have is one step more abstract than the physical representation which is the "output" of the ear. Hopefully this physical work will eventually tie up with the cog psych guys and their fMRI experiments on people listening to music. The brain sure is complex, but it seems to me that we've gotten quite a bit further in understanding it in the last 10 years.

Thursday Aug 18, 2005


Pet peeve time.

The word "entropy" has a very specific meaning. Yes, statistical thermodynamics says that it is related to disorder. No, it's not entropy's fault that your desk is a mess. Although it hasn't been hijacked to the extent that the word "quantum" has, it does tend to be misused. If you want to tell me about entropy, explain about heat engines and Carnot efficiency first, so I know you aren't just spouting buzz words, okay?

Friday Jul 01, 2005

More about Palo Verde trees

Palo Verde seed pods

Here are some seed pods from a Mexican Palo Verde tree (Parkinsonia aculeata). This is one of two Palo Verde species common around here (the other being the Foothills Palo Verde, Cercidium microphyllum). I collected these pods from the gutter next to a vacant lot. The Mexican Palo Verde is rated an "obnoxious weed" due to the ease of its propogation from seed. But it is quite an attractive tree, really. I intend to grow on or two for the garden. By the way, that's a 6" (15 cm) metal rule, for scale.

Thursday Jun 23, 2005

The importance of regular maintainance

Physical objects require regular maintainance. Want proof? Look what happened to my bonsai tree when I didn't prune it for a while...

Chinese Elm

Ulmus Parvifolia, the Chinese Elm

Friday Jun 17, 2005

Palm trees in flower

Washingtonia in flower

Palm trees in flower. You often don't get to see this, because most gardeners trim last year's leaves at around the time the flower spikes are developing, and they usually cut the spikes too. I believe these trees are Washingtonia Robusta (Mexican Fan Palm), but I'm not any kind of expert at identifing palms.

Thursday Jun 16, 2005

Minor earthquake felt in Palm Springs

We just had a minor tremblor, probably an aftershock from the moderate quake on Sunday. I completely missed the Sunday event - I was out riding my bike, and I didn't feel a thing. Today there was some very mild shaking, and the house made some noise, but nothing dramatic.

Oops, according to the USGS, it was a 5.3, in Yucaipa. That's about as big as Sunday's event, but further away from here. Hope everyone over there is all right.


Saturday Jun 11, 2005


Roadrunner on wall

Geococcyx californianus the Greater Roadrunner. Not a great picture, but it's a tricky subject. They don't like to stay still and have their photo taken. I've never heard one make a vocalization of any kind, so I guess the "meep-meep" thing was just invented by Warner Bros. They do run very fast though.


Sunday Jun 05, 2005

Risk homeostasis

Reading the occasional off-hand remark about helmets in Chris's blog has led me to take a look at risk homeostasis. It is one of the arguments advanced by the "anti-helmet" web sites that Chris has provided links to. The basic idea is that people tend to maintain a constant level of absolute risk in the face of wide variations in the safety of a particular activity. For instance, if we improve roads — better surfacing, cambered bends, etc. — people will tend to drive faster, so that their chance of adverse consequence per unit time stays the same (although the chance of a crash per unit distance would go down). I personally find this rather disturbing, and wish it were not true. Unfortunately, there is plenty of evidence that it is the case. The classic studies were done on road safety, but the idea is now being applied to other areas too. For instance, some poeple have the perception that antiretroviral drugs make HIV much less of a problem in the "developed world" these days, and sure enough, infection rates here seem to be rising.

Since I find it rather depressing to think about this in the context of people's lives at risk, I started to wonder whether it applies to software development. If we insist that people build the full train before they put back their changes, will they put back stuff that is known to compile, but is less likely to work (correctly)? If we insist that people write unit tests for their code, will they then spend less time thinking about whether their algorithm really works?

I don't have any answers for these questions, but I'm going to be on the lookout for examples.

Friday Jun 03, 2005

Yucca flowers

I saw these two flower spikes on a yucca this morning, and I couldn't resist taking a photo.

yucca flowers

Thursday May 19, 2005

Street Names

My shaky command of Spanish doesn't help me much trying to understand street names here in Southern California. For instance, there are a lot of "Palo Verde" streets around here. Verde - green. Fair enough. Palo - um, mast, stick, that kind of thing? Green Stick street?

It turns out that there is a medium-sized shrubby tree common in the area called a Palo Verde tree. It's twigs are bright green, as is the trunk. It bears pretty yellow flowers around this time of year. So yes, Green Stick (tree) Street!

Palo Verde tree,  Parkinsonia aculeata(?)



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