Brain Sparks, Live
It is well known that the nervous system uses electrical activity for sensing what's going on around us,
controlling bodily functions and just plain thinking.
Naturally, doctors and other researchers have long been
eager to find ways to monitor and control what's going
on in our heads. Doing so generally involves the use of
electrode banks, the use of voltage-sensitive (and highly
toxic) dyes, or by detecting a surge of calcium ions that
appear when a neuron receives a signal. In fact,
progress has been made in developing genetically
encoded calcium indicators (GECIs) which allow the
calcium ions to fluoresce, offering a visual image of
brain activity. This is an indirect process, however, as
detecting calcium is not the same thing as detecting the
voltage sparks themselves.
Now, some scientists at Yale's School of Medicine
( medicine.yale.edu) have come up with a variation
called genetically encoded fluorescent voltage indicators
(GEVIs) that allow researchers to watch the sparks
directly in a live animal.
As reported last August in the journal Cell, their
"ArcLight" also allows researchers to see electrical
activity in portions of the brain that were previously
inaccessible. So far, the indicators have been used only
in fruit flies, but the paper suggests that ArcLight and
other GEVIs may prove useful in many ways for
mapping brain cell activity in both normal and diseased
animals, including us humans. ▲
■ The ArcLight protein provides a look at
brain cell activity in a fruit fly.
A Boost for Low Carbon Vehicles
Despite considerable promotion and a slew of available tax incentives, the Electric Drive
Transportation Association ( www.electricdrive.org)
reports that hybrid, plug-in hybrid, and all-electric cars
still account for less than four percent of the US
market, with total cumulative sales only recently
passing 115,000. Their drawbacks are no secret: high
purchase price, limited range, and (in the case of
all-electrics) long charging times. Fortunately, a recent
development at Britain's National Physical Laboratory
( www.npl.co.uk) could be a significant step toward
solving some of those problems.
The power conversion and management systems
in automotive power electronics depend not only on
the characteristics of the batteries, but also on
capacitors which provide energy bursts for climbing
hills, and can absorb energy otherwise wasted on
braking. Because typical capacitors lose capacitance
at high temperatures, automotive power electronics
require quite a bit of cooling which adds to vehicle
weight. NPL notes, for example, that barium titanate
caps can lose as much as 85 percent of their
capacitance at working voltage.
The lab has developed a new ceramic capacitor
dielectric material — dubbed HITECA — that offers a
higher energy density and operates with stable
capacitance at temperatures as high as 200°C (392°F).
With its high permittivity and reduced capacitance
loss, caps based on it could enable smaller electronic
devices and improve vehicle performance.
In addition, "HITECA capacitors could improve
high temperature electronics in the aerospace, power,
oil, and gas sectors, and in high energy applications
such as pulsed power where energy is stored over a
period of time before being released as a high power
■ New high temperature, high capacitance device
may improve EV performance.
■ BY JEFF ECKERT TECHKNOWLEDGEY 2013
Go to www.nutsvolts.com/index.php?/
to post comments about these topics.
8 October 2013