From: LARRY KLAES (ljk4_at_msn.com)
Date: Tue Nov 04 2003 - 08:51:38 PST
----- Original Message -----
From: physnews_at_aip.org
Sent: Tuesday, November 04, 2003 11:21 AM
To: ljk4_at_MSN.COM
Subject: Physics News Update 660
PHYSICS NEWS UPDATE
The American Institute of Physics Bulletin of Physics News
Number 660 November 4, 2003 by Phillip F. Schewe, Ben Stein, and
James Riordon
MICRO-ORIGAMI FABRICATED MICROMIRRORS. Microelectromechanical
systems (MEMS) are becoming increasingly important as researchers
develop miniaturized mechanical devices for communications,
biotechnology, and a variety of measurement applications. Often
these machines include hinged parts that must be set in place before
operation, which can lead to challenging and time consuming manual
manipulation of components at ever decreasing scales. Recently,
researchers from the ATR Adaptive Communications Research
Laboratories in Japan proposed a technique that they call
micro-origami to fabricate MEMS devices that automatically move into
position. The group has now tested the technique, in collaboration
with researchers at Konan University and Osaka City University, by
creating hinged micromirrors that lift themselves up following the
final fabrication stage. The key to the micro-origami technique is
to manufacture hinges out of a pair of material layers with slightly
different atomic spacings. This lattice mismatch causes a stress
that in turn bends the hinge (see figure at www.aip.org/mgr/png )
and, in this case, raises a mirror above the substrate. (The effect
is reminiscent of the bimetallic strips in some thermostats, which
consist of bonded layers of metals that expand at different rates
when heated, leading to stresses that bend the strips as
temperatures change.) Once a mirror was in place, the researchers
could move it on its hinge by illuminating the mirror with a high
power argon laser. It is not yet entirely clear what mechanism
caused the illuminated mirror to move; the force due to radiation
pressure, in particular, was too small and in the wrong direction to
account for the effect. Nevertheless, the researchers (Jose M.
Zanardi Ocampo, 81-774-95-1582, zanardi_at_atr.co.jp) were able to use
the motion of the micromirror to control the position of a reflected
helium-neon laser beam. Potentially, the micro-origami mirror could
lead to optical MEMS switches or other small devices that
automatically pop into place without human or mechanical
intervention, dramatically speeding and simplifying construction of
miniature machines. (J. M. Zanardi Ocampo et al., Applied Physics
Letters, 3 November 2003)
ACCELERATION DISRUPTS QUANTUM TELEPORTATION, a new study has shown
(Paul Alsing, University of New Mexico, 505-277-9094,
alsing_at_ahpcc.unm.edu). In quantum teleportation (see
http://www.aip.org/enews/physnews/1997/split/pnu350-1.htm),
researchers create a pair of particles (such as photons) and cause
them to interact so their properties become interrelated (a process
called "entanglement"). Subsequently, after the particles go their
separate ways, one can measure the first particle's properties (such
as the direction its electric field is wiggling), destroy the
particle (a requirement), and then instantly transmit (or
"teleport") its exact properties to the second particle, even if it
ends up being light years away. Quantum teleportation is different
from Star Trek teleportation in that real-life physicists are only
teleporting a particle's properties, rather than the particle
itself. Now, a new analysis has shown that quantum teleportation
would malfunction if the receiver of the second particle is
accelerating relative to the first particle. (Coincidentally,
spaceships in Star Trek usually don't teleport crew members when
they accelerate into warp drive.) The disruption to quantum
teleportation arises from the Davis-Unruh effect (see
http://focus.aps.org/story/v8/st19), in which acceleration, even in
empty space, creates a bath of hot particles resulting from the
energy of the acceleration. This thermal bath of particles
inextricably disrupts the receiver's ability to perfectly recreate
(with the second accelerated particle) the properties of the first
(unaccelerated) particle that have been teleported from the sender.
While this effect is small for typical accelerations in Earthly labs
the result shows an interesting relationship between the effects of
space-time motion and the quantum world. (Alsing and Milburn,
Physical Review Letters, 31 October 2003)
A CLOSE LOOK AT HAGFISH SLIME. Hagfish are primitive, eel-like fish
that are nearly blind and lack jaws or true vertebrae. One thing
they do have is the unnerving ability to produce copious amounts of
slime when disturbed. Researchers from the Cambridge Polymer Group
in Boston and the University of British Columbia are now taking a
close look at hagfish slime, in an attempt to understand how the
slime protects the fish in nature and to determine if the slime
could lead to practical materials for industry or medicine. Hagfish
slime is a concoction of mucus and threadlike fibers, and is
produced in concentrated form from a series of pores that line the
sides of the fish's body. Upon contact with seawater, the
concentrated slime expands into a sticky gel that can ensnare and
sometimes suffocate an attacker. Unlike the mucous produced by the
membranes of humans and other animals, which functions best at body
temperature, the researchers (Gavin Braithwaite, 617-629-4400,
gavin_at_campoly.com; Douglas Fudge, dfudge_at_interchange.ubc.ca) found
that the properties of hagfish slime are relatively temperature
independent over a broad range (from roughly 5 to 30 degrees
Celsius). The insensitivity to temperature ensures that slime is an
effective defense in a variety of conditions, and also suggests that
artificial materials that mimic hagfish slime chemistry might make
good space-filling gels. One potential application for such gels,
explain the researchers, is as a way to curtail bleeding in an
accident victim or during surgery. In addition, studying the slime
may help us understand how mucins, the components of mucous,
function in our own bodies and elsewhere. There is currently some
debate regarding the relative importance of the fibers and the
mucous in the material properties of hagfish slime. The recent
research, which was presented earlier this month at the 75th Annual
Society of Rheology meeting in Pittsburgh
(http://www.rheology.org/sor/annual_meeting/2003Oct/default.htm),
focused on characterizing the properties of the mucous after the
fibers had been removed from the slime.
***********
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