From: Anders Sandberg (asa@nada.kth.se)
Date: Fri May 26 2000 - 11:07:56 MDT
This week's fun papers
This time, a bit of theoretical AI research, some megaengineering,
some tasty science, genetics of life aging, a bit of optimism and
self-help and some human evolution.
* The smartest AI possible
* Lunar solar power for use on Earth
* Menthol vs. Chili
* Healthy and unhealthy things in wine
* Does theanine make green tea relaxing, and is it good for memory?
* Is there any disadvantage of being long-lived?
* Gene expression during aging and how caloric restriction helps
* Does Optimism save us from burnout?
* Who reads self-help books and do they need it?
* Finger length ratios, musical ability and sex
* Migration and dopamine receptors
A Theory of Universal Artificial Intelligence based on Algorithmic
Complexity
Marcus Hutter
arXiv:cs.AI/0004001
http://xxx.lanl.gov/abs/cs.AI/0004001
What do you get when you combine decision theory and Solomonoff's
theory of universal induction? This paper. The author studies agents
acting in a probabilistic environment trying to maximise some utility;
this is roughly equivalent to reinforcement learning and sequential
decision theory. By adding ideas from algorithmic complexity he
describes a model called AIxi that optimizes the utility in an
arbitrary environment. Hutter claims that his AIxi model is the most
intelligent unbiased agent possible. It only has the slight drawback
of being uncomputable, so he constructs a modified algorithm that is
still effectively more intelligent than any other time t and space l
bounded agent.
Overall, a heavy paper I did not have the time to truly get into. I'm
uncertain whether this is a significant big idea or just a lot of
formalism. However, the ambition to describe the upper bounds of
intelligence is interesting, and likely very relevant for our
transhumanist ambitions.
Lunar Solar Power System: Review of the Technology Base of an
Operational LSP System
David R. Criswell, Acta Astronautica 46:8 531-540 (2000)
Space power systems (SPS) collect solar energy in space and beam it to
Earth using microwave beams. Here Criswell proposes a moon-based
system and looks at how feasible it is given today's technology. The
solar cells are nothing new, materials close at hand. Using phased
arrays microwaves can be sent as nice beams, possibly reflected using
satelites. It seems to be quite doable using today's technology.
Menthol desensitization of capsaicin irritation: Evidence of a
short-term anti-nociceptive effect
Barry G. Green and Betsy McAuliffe, Physiology & Behavior 68 (2000) 631-639
Methol produces a cool or biting feeling in the mouth and nose. So how
does it interact with the hot taste of capsaicin (the active
ingredient in chili peppers)? Will they amplify each other, or will
one of them decrease the feeling produced by the other? If menthol is
given 15 minutes before exposure to capsaicin the irritation grows
stronger. But as the interval decreases, the irritation grows
weaker. When mixed with menthol, stronger capsaicin solutions did not
feel as intense as weaker. It appears that menthol can make the
tounge less sensitive to capsaicin; they discuss whether this can be
used in clinical treatments, but from a hedonic point of view this
suggests interesting experiments in taste.
Current knowledge of the health benefits and disadvantages of wine
consumption
John F. Tomera, Trends in Food Science & Technology 10 (1999) 129-138
A review of the effects of various components in red and white
wine. Overall it doesn't come to any firm conclusions, but a lot of
interesting facts about the polyphenols, contaminants, heavy metals,
claimed health benefits, known health problems etc.
L-theanine - a unique amino acid of green tea and its relaxation
effect in humans
Lekh Raj Juneja, Djong-Chi Chu, Tsutomu Okubo, Yukiko Nagato and
Hidehiko Yoyogoshi, Trends in Food Science and Technology 10 (1999)
199-204
Green tea is healthy and said to be relaxing, but what constituents
have what effects? This review paper claims that the amino acid
theanine is responsible for the relaxation effect. The authors
describe an experiment where volunteers given theanine exihibit more
alpha-wave activity; I'm somewhat sceptical of their treatment of the
EEG and the causality here. Theanine seems to reduce serotonin levels
and significantly reduce blood pressure. It seems to improve learning
somewhat in rats. Overall, this paper does not hold the standards
found in (say) Psychopharmacology for testing, but it seems to point
at an interesting new cognitive enhancer.
Evolution of lifespan in C. elegans
David W. Walker, Gawain McColl, Nicole L. Jenkins, Jennifer Harris and
Gordon J. Lithgow, Nature 405 18 May 2000 296-297
A letter to nature looking into the natural selection of aging. If
genes like age-1 can be changed to produce a more long-lived animal,
why haven't selection produced one? A likely explanation is that there
is some evolutionary cost associated with this, making genes that are
bad when you are old beneficial when you are young and vice versa.
The authors tested this by growing a mixed population of C elegans
under normal conditions and with periodic starvation. In the first
case the frequency of long-lived and short-lived alleles did not
change, but with the starvation the age-1 frequency
decreased. Apparently it did have some disadvantage when subjected to
starvation. A nice demonstration of the pleiotrope theory of aging.
Gene Expression Profile of Aging and Its Retardation by Caloric Restriction
Cheol-Koo Lee, Roger G. Klopp, Richard Weindruch and Tomas A. Prolla,
Science vol 285 1390--1393 27 August 1999
The authors looked at which genes were expressed in aged mouse muscles
compared to young mice, and found that for the most part the
expression pattern was similar. Only 1.8% of the genes showed more
than a two-fold change in expression due to age. Of the genes that
increased in expression 16% were mediators of stress response and 9%
neural growth related genes. Among the decreased genes 13% were
involved in energy metabolism. When mice were put on caloric
restriction the pattern changed noticeably. 29% of the age-related
changes were completely prevented and 34% partially suppressed; of the
four major gene classes affected by age 84% were completely or
partially suppressed. It increased protein metabolism and biosynthesis
genes, and decreased the activity of DNA repair, heat shock factors,
detoxification systems and other damage repair systems. Overall, it
sugegsts that CR has quite profound effects on the way cells act, and
at least partially counteracts ageing.
Optimism and risk for job burnout among working college students:
stress as a mediator
Edward C. Chang, Kevin L. Rand and Daniel R. Strunk, Personality and
Individual Differences 29 (2000) 255-263
Optimism (the general expectation of positive outcomes) has been shown
to be related to greater psychological and physical adjustment. Is it
strong enough to decrease the stress that appears to be related to
burnout? If you expect good things you will be less stressed, and this
might make burnout less likely. The authors did a survey where they
measured optimism, stress and brunout risk using standard tests. They
found a significant negative correlation between optimism and
perceived stress, exhaustion and cynicism and a positive correlation
to feelings of efficacy. They explain the findings by a model where
optimism decreases perceived stress, which in turn affects the factors
leading to burnout. In short, practical optimism is a weapon in the
fight against burnout, and if managers and organisers can make people
more optimistic there is less stress and risk of burnout.
Who reads self-help books? Development and validation of the self-help
reading attitudes survey
Dawn M. Wilson and Thomans F. Cash, Personality and Individual
Differences 29 (2000) 119-129
Exactly who reads self-help books and why? This paper presents a
survey intended to study the attitudes of people to self-help. They
tested it on 264 male and female students, getting an acceptable
validity of the survey. Persons favorable to self-help books were in
general more pro-reading , more psychologically minded, more oriented
towards self-control and reported more life satisfaction. Women and
psychology majors were more positive than others to self-help
books. Noting truly unexpected, but nice to see things validated. How
much the books help is another matter, it might be that people who
need them less tend to be the ones who read them.
Second to fourth digit ratio in elite musicians: Evidence for musical
ability as an hones stignal of male fitness
Vanessa A. Sluming and John T. Manning, Evolution and Human Behavior
21 (2000) 1-9
The amount of testosterone during fetal development influences a lot
of things, and may influence musical ability too. The ratio of the
length of second and fourth digit may be related to prenatal
testosterone levels and is negatively related to adult testosterone
levels; at least one study has shown a link to sexual
preferences. This study looked at the D2:D4 ratio among the members of
a symphony orchestra. They found that the men had consistently lower
ratio than the control group of non-musicians; female members did not
differ significantly. There was no difference between different
instruments, so it was not due to mechanical advantages. Among the
violinists there is a ranking, and it was found that higher ranked
violinists had lower D2:D4 ratio. The authors suggest that all this
points at musical ability is sexually selected for in men, since it
signifies a high level of testosterone and presumably good genes. I
don't know how much one should make of this paper, but it definitely
belong to the category 'fun' papers.
Population Migration and the Variation of Dopamine D4 Receptor (DRD4)
Allele Frequencies Around the Globe
Chuansheng Chen, Michael Burton, Ellen Greenberger and Julia Dmitrieva
Evolution and Human Behavior 20: 309--324 (1999)
Some variants of the dopamine D4 receptor (long alleles) has been
claimed to be linked with traits such as 'novelty-seeking' and a
tendency to go exploring. Is there any differences in the D4 allele
frequencies between different ethnic groups and does this have
anything to do if they have migrated in the past? This study compiled
data from 39 groups (2320 individuals) and found that compared to
populations that had not moved much in the past migratory populations
showed a higher proportion of long alleles of DRD4. There was a strong
correlation (0.85) between long-range macromigration and a somewhat
weaker but still relevant (0.52) correlation for having a nomadic
lifestyle. This was apparently the only gene showing this kind of
correlation. While one explanation might be that restless novelty
seekers found new settlements and over time there is a founder
selection, another possibility is that there is selection for this
gene in a culture that is moving. It is this later conclusion this
paper supports.
-- ----------------------------------------------------------------------- Anders Sandberg Towards Ascension! asa@nada.kth.se http://www.nada.kth.se/~asa/ GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y
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