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Friday, August 19th, 2005
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2:01p - modeling phonology; declarative vs procedural a false dichotomy
'Foreign accent syndrome' explained . Do you know anyone who sounds foreign even though they're completely local?
I knew a girl in college who sounded like she was from the South, despite the fact that she had spent her whole life in Connecticut. It annoyed her when even the foreign guy (me) noticed. I am of course *not* implying that people in the South are brain-damaged.
It would be very interesting to make cognitive models of speech production (which is harder than perception) for second-language speakers. Why do Indians render [w] as [v], while Brazilians render it as [u]? (both languages have both phonemes)
This research might even help actors.
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By the way, some knowledge is neither declarative nor procedural: for instance the knowledge that recognize a face.
It's not declarative because you don't know how you do it, and you can't pass it on to someone else.
But it's not procedural because it's about perception, not action.
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2:02p - Wikipedia's List of Film Clichés
The Wikipedia's very large List of Film Clichés is highly recommended for a laugh.
The section on Computers & Internet is a highlight.
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9:47p - co-evolution of virulence and anti-microbial peptides
I've been analyzing more evolution stuff, inspired by ![[info]](http://l-stat.livejournal.com/img/userinfo.gif) tdj. Maybe I'm going a bit overboard (I probably misinterpreted the original meaning, but such speculations are fascinating anyway)
In response to Study reveals a way disease bacteria sense antimicrobials and initiate a counter-defense:
Many living things, from fruit flies to people, naturally produce disease-fighting chemicals, called antimicrobial peptides, to kill harmful bacteria. In a counter move, some disease-causing bacteria have evolved microbial detectors. The bacteria sense the presence of antimicrobial peptides as a warning signal. The alarm sets off a reaction inside the bacteria to avoid destruction.
University of Washington (UW) and McGill researchers have revealed a molecular mechanism whereby bacteria can recognize tiny antimicrobial peptide molecules, then respond by becoming more virulent.
I wrote:
Whoa, such a mechanism could evolve even if it kills the host and stops the bacteria from multiplying. How? Co-evolution: the conditional virulence causes hosts to stop producing antimicrobials (since the ones who produce them die more).
Therefore, the bacteria populations that *do* respond by becoming more virulent have a stable strategy. This is game theory! The 2 players are: HOST'S GENES, and BACTERIA'S GENES, and each player has 2 strategies.
Let's assume virulent reactions to peptide kills the host (-10 for the host).
\ HOST peptide no peptide
BACTERIA
virulent (-10, -1) (-1, +1)
non-virulent (0, 0) (-1, +1)
(HOST_GENES, BACTERIA_GENES)
as long as there is a credible threat of virulence, hosts may "choose" to not produce peptide. I think the evolutionarily stable solution is "mixed strategies".
Individual bacteria do better by not killing the host, but whole bacterial populations that co-evolve with the host do better by having some individuals who become virulent (sacrificing themselves for the greater good of their family), thus "forcing" the host populations' genes to play "no peptide".
I find it plausible that group selection is a strong enough force in bacterial evolution.
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