update.550 (fwd)

[Jim Choate]

---------- Forwarded message ----------
Date: Wed, 1 Aug 2001 14:13:49 -0400 (EDT)
From: AIP listserver <physnews at aip.org>
To: physnews-mailing at aip.org
Subject: update.550


PHYSICS NEWS UPDATE                         
The American Institute of Physics Bulletin of Physics News
Number 550  August 1, 2001   by Phillip F. Schewe, Ben Stein, and
James Riordon

ELEMENT 118 HAS BEEN ERASED FROM THE PERIODIC TABLE.
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INSECT SENSES SUGGEST NOVEL NEURAL NETWORKS. 
Animals gather information about their environments when sensory
neurons fire minute electrical signals in response to chemicals, light,
sounds, and other stimuli. Studying networks of neurons in animals
and insects can provide us with insight to the natural world as well as
inspiration for manmade networks to aid in computing and other
applications.  A new model of neural networks, based on recent
studies of fish and insect olfactory systems, suggests a way that
neurons can be linked together to allow them to identify many more
stimuli than possible with conventional networks. Researchers from
the Institute for Nonlinear Science at the University of California,
San Diego (M. Rabinovich, mrabinovich at ucsd.edu, 858-534-6753)
propose that connections between neurons can cause one neuron to
delay the firing of another neuron. As a result, a given stimulus leads
to a specific time sequence of neural impulses. In essence, the
interconnected neurons include time as another dimension of sensory
systems through an encoding method called Winnerless Competition
(WLC).   Using a locust antenna lobe exposed to fragrances such as
cherry and mint for comparison, the researchers found their model
could identify roughly (N-1)! (equal to (N-1) x (N-2) x ...x 2) items
with a network built of N neurons. That is, a ten neuron WLC
network should be able to identify hundreds of thousands as many
items as a conventional ten-neuron network, and the benefits increase
as networks grow.  The WLC model helps explain how the senses of
animals, insects, and even humans can accurately and robustly
distinguish between so many stimuli. In other words, it is a
mathematical rationale as to why a rose, by any other name, would
smell as sweet---but doesn't smell like an onion. Ultimately, the WLC
model may lead to high capacity, potent computing networks that
resemble an insect antenna or a human nose more than a desktop PC.
(M. Rabinovich et al, Physical Review Letters, 6 August 2001)

THE MOST PRECISELY LOCATED ASTRONOMICAL OBJECT
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DELIVERY OF SINGLE ATOMS ON DEMAND is now possible. 
Physicists at the University of Bonn hold cold cesium atoms in a
magneto-optic trap, but can shuttle the neutral atoms, one a time,
with great control over distances up to a centimeter by shifting an
additional laser-light interference pattern serving as local potential
well.  This kind of conveyor belt for atoms is expected to be of help
in various quantum entanglement experiments or as part of an atomic
shift register.  (Kuhr et al., Science, 13 July 2001; kuhr at iap.uni-
bonn.de.)