From: Anders Sandberg (asa@nada.kth.se)
Date: Fri Feb 12 1999 - 16:59:53 MST
Making myoglobin better at breaking down peroxides
Spinal microstimulation for erection
An unusual memory enhancer
No free lunch theorems for optimization
Glyphs for visualizing data
Information murals
Startlecam: a wearable camera linked to attention
Using small-world networks
Quantum game theory
In vitro evolution of horse heart myoglobin to increase peroxidase activity
L. Wan, M. B. Twitchett, L. D. Eltis, A. G. Mauk and M. Smith
Proc Natl Acad Sci U S A, 95:22 12825--31 Oct 27 1998
Myoglobin, just like hemoglobin, is able to break down hydrogen
peroxide. In this experiment they made a gene for the protein,
subjected it to mutations, implanted it in bacteria, screened for
peroxidase activity, took the best version and continued the
process. The result was a protein 25 times as active as the
original. Nice to see that it is possible to improve on nature using
so few iterations.
Penile erection produced by microstimulation of the sacral spinal cord
of the cat
C. Tai and A. M. Booth and W. C. de Groat and J. R. Roppolo
IEEE Trans Rehabil Eng, 6:4 374--81, Dec 1998
The neural pathways of erection are rather messy, but this paper
studies how microstimulation in the spinal cord can cause it. The
obvious application is of course for helping people with spinal cord
injury, but I think there might be transhumanist potential for hedonic
engineering here.
Phlorizin, a competitive inhibitor of glucose transport, facilitates
memory storage in mice
M. M. Boccia, S. R. Kopf and C. M. Baratti
Neurobiol Learn Mem, 71:1 104-12, Jan 1999
And the obligatory new memory enhancer :-) It is known that glucose
enhances memory encoding, so it would appear that an inhibitor like
phlorizin would make encoding worse, but the opposite is true. When
injected after training it made mice quicker at avoiding an electric
shock they had learned before, but there was no effect if given just
before the testing, so it just enhances encoding, not retrieval. It
shows the usual inverted U-curve, and counteracted the memory decrease
caused by insulin. So it seems that it is enough that a substance is
glucose-like to affect memory, very odd.
No Free Lunch Theorems for Optimization
David H Wolpert and Wiliam G Macready
IEEE Transactions on Evolutionary Computation, 1:1 67--82 1997
It might look like some ways of optimizing are better than others
(like genetic algorithms being better than hillclimbing which is
better than random search), but surprisingly it is wrong. If an
algorithm for finding an optimim performs better than another
algorithm on a certain set of optimization problems, then the reverse
must be true for all other optimization problems! This means that
there is no best method, and in fact they are all just as bad as
random search. This might look very strange or even depressing, but it
is really fairly trivial: the set of all optimization problems include
a vast majority of completely intractable problems (like finding the
optimum of a pseudorandom function), the set of "reasonable" problems
we are used to is vanishingly small. Over a certain set of problems,
there are certainly functions that are better than others. This is
just another demonstration that prior knowledge is essential for
problem solving.
Information Rich Glyphs for Software Management Data
Mei C Chuah and Stephen G Eick
IEEE Computer Graphics and Applications, 24--29 July/August 1998
Just some more visualization tricks, this time glyphs representing
things such as added lines, errors, number of changes, people etc in a
database of software releases. They use a wheel-like or bug-like
glyphs and discuss their advantages and disadvantages. Maybe useful
for analyzing mailing list archives?
The Information Mural: A Technique for Displaying and Navigating Large
Information Spaces
Dean F Jerding and John T. Stasko IEEE Transactions on Visualization
and Computer Graphics, 4:3 257--271, July-September 1998
Another nice way of visualizing data: have a shrunken "mural"
depicting the whole document/database at the side of the magnified
view you watch. Makes it possible to both get an overview, notice
patterns and search.
StartleCam: a cybernetic wearable camera
Healey, J.; Picard, R.W.
Wearable Computers, 1998. Digest of Papers. Second International Symposium on
A fun system, now actually implemented in reality. The wearer has
sensors measuring galvanic skin response, and a wearable video
camera. If the skin response rises, the system stores the pictures
leading up to that point. Seems to be able to trigger not just to
surprises or stress, but also attention. Very interesting, and
suggests that affective computing can become quite useful.
Characterization and control of small-world networks
S. A. Pandit, R. E. Amritkar
http://xxx.lanl.gov/abs/chao-dyn/9901017
Small-world networks (the kind of networks where some long-range
connections makes almost every node close to every other node, despite
having mostly local connections; examples include collaboration
graphs, neural networks and power grids) appears to be useful for a
lot of things. This paper studies how the sensitive dependence on the
long-range connections makes it possible to control the spread of an
epidemic by first immunizing the long-range connections. It also turns
the problem around, and sufggests that the best way of spreading
advertisements (or memes) would be to target the long-range links.
Quantum Strategies
David A. Meyer Physical Review Letters 82:5 1052--1055 1999
Since computation can be generalized to quantum computation, why not
generalize game theory? This paper deals with the odd things that can
happen if you allow players to choose quantum superpositions of
strategies. As an example Meyer describes a game between captain
Picard of Star Trek and the superbeing Q, where they take turns of
either flipping a hidden coin or not. Classically, this is a fair
zero-sum game with an equilibrium of mixed strategies. But if Q makes
quantum moves, then he can win against the classical Picard! There is
no equilibrium if both players play deterministic quantum strategies,
but Meyer shows that there is an equilibrium if both plays mixed
quantum strategies (i.e. they select randomly between a number of
quantum strategies). A fun generalization, and it ties in with quantum
error correction (where nature is one of the players).
-- ----------------------------------------------------------------------- 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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