Home' Technology Review : March April 2007 Contents From the Labs
94 FROM THE LABS
TECHNOLOGY REVIEW /
WHY IT MATTERS: Scientists would
like to create dr ugs that can mimic the
e ects of age-defying genes. But rst,
they must identify the genetic variations
that allow some people to stay physi-
cally and mentally healthier in old age.
In a previous study of Ashkenazi Jews,
Nir Barzilai and colleagues found that
this gene variant is seen three times
as often in centenarians as in others.
People with the variant also seem to
have larger cholesterol particles in their
blood, providing a hint at the gene s
mechanism. Now the researchers have
linked the gene to preser vation of men-
tal function. Taken together, the nd-
ings point to a potential target for dr ugs
that could protect against dementia and
other wise delay the aging process.
METHODS: Barzilai and his col-
league Gil Atzmonran tested people of
Ashkenazi Jewish descent who were
95 or older and con rmed the results
in a group of 75- to 85-year-olds of the
same descent. Medical geneticists often
study groups, such as the Ashkenazi,
descended from a relatively small num-
ber of ancestors because they re more
genetically homogenous, making it
easier to identify genetic associations.
NEXT STEPS: Scientists are now
examining the frequency of the gene
variant in people with Alzheimer s.
They also plan to study how expres-
sion of the protein produced by the
gene a ects the brain in animals.
A new approach helps computer-
animated fluids flow more naturally
SOU RC E: "Stable, Circulation-Preserving,
Mathieu Desbrun et al.
ACM Transactions on Graphics 26(1)
RESULTS: Researchers at the California
Institute of Technology have developed
a new geometric approach to simulat-
ing uid ow that s more realistic.
WHY IT MATTERS: Numerical
approaches commonly used in com-
puter animation and in aerodynam-
ics simulations contain inaccuracies
that can cause graphically depicted
liquids to appear to ow unnaturally.
For instance, when used to model
whirlpools, these equations predict
an exaggerated decrease in energy,
so animations of swirling water slow
down for no apparent reason. Ani-
mators need to spend time correct-
ing these errors by hand. A numerical
treatment that better respects liquids
actual behavior could save animation
studios time and money.
METHODS: The researchers used a
new type of mathematics called dis-
crete di erential geometry to calculate
the ux of a owing liquid, a prop-
erty that deter mines the velocity and
position of the liquid at any time. The
researchers say that because their equa-
tions use ux, rather than just uid
velocity, they more accurately capture
the behavior of swirling liquids.
NEXT STEPS: The new approach
should yield simulations that better
predict the ow of uids---say, water
or air turbulence around planes or
boats. Eventually, the approach could
be incorporated into software for
movie studios, but that will require
more research on how to modify the
equations to simulate a wider range
of natural phenomena.
Extra Room for
New architecture could make chips
faster and keep Moore s Law alive
SOU R CE: "Nano/CMOS Architectures
Using a Field-Programmable Nanowire
Gregory S. Snider and R. Stanley Williams
Nanotechnology 18: 035204
RESULTS: Hewlett-Packard Labs
researchers R. Stanley Williams and
Greg Snider have redesigned the chips
known as eld-programmable gate
arrays to make room for eight times
as many transistors, without shrinking
the transistors themselves.
WHY IT MATTERS: As electronic
devices, such as transistors, grow
smaller, engineers can pack them
closer together, producing faster and
more powerful computer chips. In the
next decade, however, the standard
techniques for shrinking transistors
will run up against fundamental physi-
cal limits, so engineers are looking for
new ways to increase the density of
METHODS: In today s chips, some
of the silicon real estate is taken up
by aluminum-wire interconnects
that supply power and instr uctions
to the transistors. To make room for
more transistors, the HP researchers
designed a chip whose wires are on top
of instead of in between the transistors.
They used what they called a "cross-
bar str ucture," a sort of nanoscale wire
mesh developed at HP. Each junction
in the mesh acts as a switch that con-
trols the ow of electrons to and from
the transistor beneath it.
NEXT STEPS: The researchers are
developing a laboratory prototype that
uses the design, and Williams expects
it to be complete by the end of the year.
By 2010, he says, the technology should
be ready for manufacturing.
MATHIEU DESBRUN, APPLIED GEOMETRY LAB, CALTECH
The spinning liquid in this snow globe is
the product of a new animation technique
developed at Caltech. The researchers say
their geometric approach yields more real-
istic simulations of moving liquid.
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