Technology

DOGS that moo, lawn mowers thatsound like fax modems and redfluffy clouds in a clear blue sky are all components of a virtual reality (VR) game that could be used to explore the cognitive problems of people with schizophrenia.

At the Medicine Meets Virtual Reality conference in Long Beach,California, next week, computerscientist Daphna Weinshall of theHebrew University of Jerusalem

in Israel will describe a VRexperiment in which volunteerswearing a head-mounted display navigated through simulated streets, shopping malls and a market. They were asked to flag up “incoherencies” such as objectsthat were the wrong colour or inthe wrong position – a street signat ground level, for instance – ormaking the wrong noise. While all the healthy volunteers spotted at least 87 per cent of the incoherencies, only six of the 43 volunteers with schizophreniascored in this normal range.

As yet, the differences are not clear-cut enough for VR to replaceestablished diagnostic methods, in which psychiatrists interviewand observe patients to determine which of a checklist of symptomsthey have. But the results suggest that VR simulations could berefined to produce diagnostic

tests that provide a more detailed assessment of brain function , says Avi Peled, a psychiatrist at the Technion-Israel Instituteof Technology in Haifa whoco-developed the simulation.

Peled is also interested in using VR to study the details

of what goes wrong in the brains of people with schizophrenia.For example, while it is already possible to probe cognitive abilityusing pen-and-paper tests, inVR more information can bepresented using several senses simultaneously. “Why do we need this fancy technology? Becausewe can control vision and hearingin parallel,” says Peled.

Peter Yellowlees, a psychiatrist at the University of California atDavis who developed a simulationof schizophrenia symptoms inthe virtual world Second Life,suggests imaging patients’ brains while they play a VR game. That might reveal abnormalities inneural activity that underpin cognitive difficulties. “That is the winning combination,” says Peled. “It is surely the next step.”

Simulations could also allowdoctors to test for cognitive problems that may affect treatment. Matthew Kurtzof Wesleyan University in Middletown, Connecticut, foundthat people with schizophrenia who were asked to take pills at a certain time in a VR apartment often took the wrong number at the wrong time (SchizophreniaBulletin, DOI: 10.1093/schbul/sbl039). Peter Aldhous ●

HERE’S something residents of cloudy

northern Europe should appreciate: a

way of using rain to generate power.

Jean-Jacques Chaillout and

colleagues at the Atomic Energy

Commission (CEA) in Grenoble,

France, have shown that piezoelectric

materials , which generate voltage in

response to mechanical force, can be

made to produce useful amounts of

electrical power when hit by falling

rain. “We thought of raindrops

because they are one of the still-

unexploited energy sources in

nature,” Chaillout says.

His team started by looking up

data on different types of rainfall.

Drizzle, they found, produces

droplets of about 1 millimetre in

diameter which have an impact

energy of around 2 microjoules,

while droplets from a downpour

were typically 5 millimetres

across and gave 1 millijoule

of impact energy.

The team then used computer

simulations to see how different-

sized drops hit surfaces and

concluded that a 25-micrometre-

thick piezoelectric material wouldk

be the most efficient at harvesting

energy from a range of raindrop

sizes. To put this to the test, they

mounted a 10-centimetre-long strip

of polyvinylidene fluoride, a piezo

plastic, on a rig and suspended a

pipette above it that could be

adjusted to create different size

water droplets that fell at realistic

rainfall speeds. When the drops

pounded the piezo plastic, they

found that it produced between

1 nanojoule and 25 microjoules of s

energy per drop, depending on the

size of the drop (Smart Materials and ((

Structures, DOI: 10.1088/0964-

1726/17/01/015039). That translates to

about one microwatt of power for

the smallest drops, which is enough

to transmit a digital bit of

information 10 metres of air.

Although the output is puny

compared with that of solar panels,

rain power has the advantage of

working in the dark and could be

used to supplement solar-

powered devices.

The first application, the

researchers say, could be inside the

cooling towers of nuclear power

stations, where a build-up of

limescale reduces their efficiency.

The team plans to create a wireless

limescale sensor that will be powered

by the falling droplets that form

when the steam vented up the

chimney condenses. Other

applications might include a self-

powered rain detector for a car’s

windshield wipers or wireless air-

quality sensors that beam back

readings to a pollution data centre.

Environmental sensors that

“scavenge” their own energy make

good sense, says Peter Tavner, head

of engineering at Durham University

in the UK. “We use far too much

energy in simply exchanging

information between devices. I think

self-powering them is the future.”

However, Stephen Roberts of

Perpetuum, a company in

Southampton, UK, that builds devices

which capture energy from vibrating

machinery and bridges , points out

that rain-powered piezoelectric

sensors provide only intermittent

power and fears that they may wear

out quickly. Paul Marks ●

“VR combined with brain imaging could reveal neural abnormalities”

–Feel the power–

Schizophreniaexplored with virtual reality

Making every shower an electric storm

JEAN

-LUC

MAN

AUD/

RAPH

O/CA

MER

APRE

SS

30 | NewScientist | 26 January 2008 www.newscientist.com