Science, Technology & Health: June 2005 Archives

From Bernardo, here's a pretty cool picture of a real-life Eye of Sauron. Good thing it's pretty far away. If anyone else has good astronomy pics, why not post some links in the comments?

Here's a question for any C# gurus out there. I've created a delegate in C# to pass out to unmanaged C as a function pointer. It works fine, but how can I explicitly make sure it doesn't get garbage collected? I can't use any Microsoft-specific interoperability stuff because the code needs to work with Mono. In fact, it does work with Mono because Mono must do garbage collection differently than Microsoft does; my main problem is preventing Microsoft from collecting the delegate before my unmanaged code is done with it. Right now I'm continually reassigning the callback function pointer in a loop in C#, but that's not very elegant.

One of the hardest things to do in the field of artificial intelligence is to interpret what exactly a neural network is doing and why it's doing it. Artificial neural networks (ANNs) are deterministic in the sense that, given adequate information about one's state, it is always possible to exactly predict what it will do. However, due to their complexity and chaotic nature it is almost always difficult to go backwards from an end state to discover how the various parts of the neural network contributed to that end state. By "difficult" I mean that it is theoretically possible but practically impossible; the math says it can be done, and we know how to do it, but the calculations are so onerous that it basically can't be done. (Very simplified explanation.)

For this reason, it is very difficult to determine where in a given ANN a certain piece of knowledge is stored. We can put in inputs and get out outputs that indicate that the ANN knows something, and we can probe for real-time data, but it's difficult to determine which neuron (or connection between neurons) or set of neurons (or set of connections) stores a given piece of knowledge just by looking at the structure. Sometimes, in simple networks, neurons can be analyzed and isolated to demonstrate their function, but most of the time a given piece of knowledge is distributed across many neurons, all of which contribute towards generating the appropriate output. One advantage of distributed storage is that if a single neuron breaks the output will only degrade slightly (in theory).

Human brains are far more complex than artificial neural networks, but they're similar in many respects (or so it would appear). Recent research from UCLA and Caltech indicates that knowledge may not be as distributed across neurons as was previously thought. Earlier speculation was that no single neuron was responsible for any specific piece of knowledge, but that everything we consider "memories" is distributed across billions of neurons. However, now there's some evidence that, even if no specific piece of knowledge exists only on a single neuron, some neurons are tied to a specific piece of knowledge.

In the current issue of the journal Nature, a research team led by neuroscientists at UCLA and Caltech has rather haphazardly located a neuron that "looks for all the world like a 'Jennifer Aniston' cell," writes Charles Connor of John Hopkins University. Conner was not involved in the study.

The cell in question was found in the brain of one subject as part of an epilepsy study. When the person was shown 87 images of various celebrities, well-known buildings, animals and objects, the neuron only fired for seven separate snapshots of the Friends actress.

It may be that many other neurons that weren't probed also fired for Jennifer Aniston. It may also be that the researchers simply couldn't find another thought that would trigger that neuron, but that such a thought does actually exist. Either way, these results are somewhat surprising.

However, no one is claiming that there is only one cell in the brain for Jennifer Aniston, the Eiffel Tower, and your grandmother.

"One straightforward objection to this idea is that we don't have enough neurons in the brain to represent each object in the world," said Connor.

Well, the adult human brain has around 100 billion neurons, which would seem to be more than enough to devote one to each person you know or know of, plus more than enough for every other proper noun conceivable. Futher, there are far more connections than there are neurons, and connections certainly play a role in thought and memory, perhaps even more of a role than the neurons themselves. (In ANNs, the connections between neurons are where all the work is generally done.)

"Sparseness has its advantages, especially for memory, because compact coding maximizes total storage capacity," Connor said.

Actually though, the method of knowledge distribution (sparse or dense) probably has little effect on how much capacity a given piece of knowledge requires to store. There may be some overhead associated with distributing knowledge across neurons and weights, but given the highly parallel nature of the human brain it's not likely to be very much.

For brains, anyway.

RICHMOND, Va. (June 17, 2005) – People with bigger brains are smarter than their smaller-brained counterparts, according to a study conducted by a Virginia Commonwealth University researcher published in the journal “Intelligence.” ...

“For all age and sex groups, it is now very clear that brain volume and intelligence are related,” said lead researcher Michael A. McDaniel, Ph.D., an industrial and organizational psychologist who specializes in the study of intelligence and other predictors of job performance.

Well... duh? Big muscles mean more strength, so these results are pretty obvious. But then, mine is enormous.

Downside: can't wear hats.

The pun is so obvious -- given Clayton Cramer's interests I'm almost ashamed that he didn't think of it himself. Mr. Cramer sent an email claiming that no one else is blogging about the important issue of defending oneself against bears and he links to several studies about bears and pepper spray.

Smith said that although research has shown that red pepper spray is highly effective as a deterrent in aggressive grizzly and brown bear encounters when sprayed directly in a bear's eyes or nose, his pilot study shows that spray residues did attract brown bears when used in nonaggressive situations. Brown bear responses to red pepper spray-treated sites in his study ranged from mere sniffing to whole body rolling in the residues, an uncommon bear behavior.

Mr. Cramer recommends a mixed strategy of pepper spray and a .44 Magnum, but another option he fails to mention is the bear-proof suit, which also has the benefit of being truck-proof and arrow-proof. The only downside (if you see it as such) is that the suit's appearance is so unearthly that bears won't even attack it.

The first live tests of Troy Hurtubise's grizzly-proof suit have found that its best protective feature is its bizarre appearance. Hurtubise donned the suit and squared up to a 145-kilogram (320-pound) female grizzly last week but the bear just found it too weird.

When confronted by Hurtubise in the Ursus Mark VI suit, the bear smelled a human, but saw an alien. "There's no grizzly that's going to come near you in that suit," the bear handler told him, after he spent 10 minutes in a cage with the cowering animal.

Unfortunately the Ursus Mark VI wasn't strong enough to face the intended 1200 pound Kodiak, but don't worry, the Ursus Mark VII was completed less than a year later, in 2002. I haven't been able to discover the results of Mark VII vs. Kodiak, but one thing's for sure: I wouldn't coat the suit with pepper spray before jumping in the ring.

I have a friend who I believe to be knowledgable on the matter who claims that asbestos-related mesothelioma is a scam dreamed up by personal injury lawyers; I can't find a lot of information on the web that isn't directly related to soliciting business for said lawyers. Does anyone have any sources of information about the cancer that I'm not finding on Google?

I bought a cheap elliptical machine from Wal-Mart and I totally love it. I started running almost ten years ago, and my knees were starting to bother me from the constant pounding. I bought the elliptical machine last weekend and have been using it all week, and my knees are feeling better than ever.

First off, the elliptical is zero-impact, so it's a lot easier on my joints. Secondly, it exercises my legs more completely than running, so the muscles that support my knees are getting strengthened. Third, it provides a whole body workout for my abs, chest, shoulders, and arms, which running just can't do.

The only significant downside is that I don't get to feel the wind in my hair as I zip through the neighborhood... but on the other hand, I'm much less likely to get hit by a car. All in all, I'd highly recommend an elliptical trainer to anyone who runs -- your knees and hips and ankles will thank you.

Here's a nifty tool that combines Google Maps with a database of observed gas prices: Cheap Gas. You select your location and it shows you where all the cheapest gas locations are (here's a hint: far away). It would be really nice if you could type in a location and have it calculate which station is the most efficient to fill up at based on gas price and distance. It would also be nice if you could input start and end points and have it find a cheap station that's on your way....

Another great use of Google Maps is HousingMaps, which scrapes rental listings from craigslist and maps them out for you by price.

(HT: My cube-mate, who probably got them from this thread on Slashdot.)

Here's another use for experimental ecnomics: scientists have isolated the chemical they dub trust in a bottle.

A Swiss-led research team tested their creation on volunteers playing an investment game for real money. When they inhaled the nasal spray, investors were more likely to hand over money to a trustee, knowing that, although they could make a hefty profit, they could also lose everything if the trustee decided not to give any of the money back.

The potion's magic ingredient is oxytocin, a chemical that is produced naturally in the brain. Its production is triggered by a range of stimuli, including sex and breastfeeding, and it is known to be important in the formation of social ties, such as mating pairs and parent-offspring bonds. It is perhaps no surprise that the compound has been nicknamed the 'love hormone'.

Experts think that oxytocin exerts its range of effects by boosting some social behaviours: it may encourage animals or people to overcome their natural wariness when faced with a risky situation. The theory argues that people only decide to trust each other - when forming a sexual or business relationship, for example - when the brain's oxytocin production is boosted.

Many human behaviors -- from advertising to romance -- are tailored to elicit an increase in oxytocin production in their target. Administering the chemical directly would only flatten the playing field and lessen the advantage enjoyed by those of us who are particularly charming. Is that fair? In a way, bottled oxytocin is to a social misfit what a gun is to a physical weakling. Still, convincing someone with natural charm seems somehow less creepy than using a chemical in a bottle.

(HT: GeekPress.)

Is it possible that the Japanese abortion industry actually encourages policies that have led to a surge in AIDS infections? As I quoted last year, many Japanese view abortion as a primary method of birth control:

It is common knowledge that abortion has long been one of the most popular forms of birth control in Japan, largely because it's such an enormous money-spinner for those who perform the procedure that they have fought tooth-and-nail to prevent proliferation of alternative means.

Perhaps that's why Japanese appear reluctant to use condoms?

Among women, Sato is one of the careful ones. The 23-year-old Tokyoite has unprotected sex with multiple partners, but at least she occasionally gets herself tested for HIV.

"I know about the risks of disease, but usually the guys I'm with refuse to use a condom _ so we just end up having sex without one," said Sato, who would give only her last name as she waited for her blood to be drawn at a health center.

The risky behavior also extends far beyond youth: Older men often consort with part-time prostitutes of high-school age, businessmen go abroad on "sex tours" thinly disguised as company trips, and the country's enormous sex industry offers services condom-free for higher prices.

Ok, so, I'm not sure what to make of this. John Vescio sent me a link to a product called HuFu which, according to the HuFu FAQ, "is designed to resemble, as humanly possible, the taste and texture of human flesh" while actually containing "no human or animal products". Got it? It's a vegan product that tastes like human flesh. The site isn't graphic, but still, you may not want to go read more.

Update:
TM Lutas thinks HuFu is in poor taste. He also makes a larger point about taboos existing for a reason, and I agree (isn't that part of being "conservative"?); cannibalism is a particularly valuable taboo, in my humble opinion.