Andy York, Author at New Ů��С��Ƶ

Risky business

Andy York — Sat, 07 Nov 1998 00:00:00 +0000

ACTORS are tempting fate whenever they use their traditional “break a leg”
message of good luck. Today, on average, almost half the performers in each
production in London’s West End succumb to work-related injuries.

Randolph Evans, a neurologist at the University of Texas at Houston, and
psychologist Richard Evans of the University of Houston surveyed 269 actors and
dancers in 20 West End musicals and plays. Behind the glitzy scenes of many
productions lay a story of high stress and occupational injury. Forty-six per
cent of all performers had sustained at least one injury in their current
production, the researchers report in Occupational and Environmental
Medicine (vol 55, p 585).

Most of the injuries were sprains and strains and did not threaten people’s
careers. Injuries to ankles, feet, knees and lower legs were most common, but
back and neck injuries were frequent, too. The most dangerous show was
Starlight Express, with an average number of 2.95 injuries per performer
against a West End average of 0.87.

Women were more likely to suffer injuries than men, presumably because they
often wear high-heeled shoes. Sixty-one per cent of performers thought their
injuries were avoidable, and believed sets were too dangerous.

One big problem is raked or sloping stages which are designed with the
audience, not the performers, in mind. “It’s like standing at the top of a ski
slope,” explains Evans. “You have to put your weight back to stand on it.” Some
West End stages have a slope of 10 per cent.

The West End study follows a similar survey carried out by the same
researchers on Broadway in New York. After that research, the Actors’ Equity
Association of the United States—the union of professional actors and
stage managers—introduced guidelines recommending a maximum stage rake of
7.5 per cent. The new survey has already led to guidelines that oblige West End
producers using raked stages to employ a “rake specialist”—usually a
physiotherapist—to help performers work safely.

It’s what the best movie stars will be wearing

Andy York — Sat, 31 Oct 1998 00:00:00 +0000

ANIMATED movies are about become more lifelike thanks to new software that
models the physics of fabrics. Existing computer animation packages work well
for simple substances such as jelly, rubber or liquids, but clothing doesn’t
behave naturally. This doesn’t matter if the characters are plastic toys, as in
Small Soldiers, but it makes it hard to create more convincing
characters.

The problem arises because animation software does not contain any
mathematical description of clothing’s mechanical properties. Instead it uses
“spring-like” algorithms to describe the movement of a character’s clothes in
relation to their body. “If you drop a piece of cloth, in reality it would pile
up, but using conventional techniques it would fall and look like a puddle,”
says Chris Ford of software house Alias/Wavefront in Toronto. So the company has
developed a package called Maya Cloth that describes the bending and shear
forces of different fabrics, allowing animators to dress their characters in
realistic cotton, velvet, leather or linens.

Maya Cloth can also describe the way that fabric collides with itself and
with the wearer. “If you drop a ball bearing in the pocket of a shirt, it will
pull down the pocket according to the weight of the bearing,” says Ford. The
computerised clothes even react in a lifelike manner to the folding effects of
wind and the splashing of rain.

Winning numbers

Lila Guterman — Fri, 23 Oct 1998 23:00:00 +0000

THESE days, many chemists sit down in front of a computer before they move to the lab bench. That’s because programs running the equations of quantum chemistry have the power to predict what will happen in a reaction, analyse the peaks in a spectrum, or explain the physical properties of a substance. For this we can thank Walter Kohn and John Pople, who share this year’s Nobel Prize in Chemistry.

The father of quantum theory, Erwin Schrödinger, showed that the motion of an electron can be described by an equation called its wave function. That’s fine for hydrogen, which has one electron, but what about bigger atoms and molecules?

“An electron, like everything else, exists in three-dimensional space,” explains Kohn, a physicist at the University of California, Santa Barbara. Many molecules have thousands of electrons. This creates an equation with thousands of dimensions, three for each electron. “Everybody can visualise three dimensions,” says Kohn. “Some people, like Einstein, can visualise four. But nobody can visualise hundreds of thousands of dimensions.”

Kohn’s insight, gained from studies on metal alloys in the mid-1960s, was to realise that simply describing the density of electrons in an atom or molecule in three dimensions was equivalent to calculating each and every electron’s wave function. That brought the problem back down to three dimensions. “It was a revolutionary suggestion,” says William Goddard, a computational chemist at the California Institute of Technology in Pasadena.

Using Kohn’s density functional theory, chemists can calculate not only the average number of electrons at any point in space around atomic nuclei but also the overall energy of a molecule—even huge molecules that are beyond the scope of conventional methods based on wave functions. “With traditional methods, accurate calculations in chemistry stop at molecules that contain about ten atoms,” says Kohn. “With density functional theory, people have now obtained good results for molecules containing up to about a thousand atoms.”

The contribution of Pople, now at Northwestern University in Evanston, Illinois, was to make quantum methods a practical tool that rank-and-file chemists could use. “In the early days, people thought you could only solve very simple problems, where you already knew the answers,” he says. He refined calculations based on wave function methods and density functional theory, and in 1970 released the Gaussian computer program which made them easily accessible to non-experts and not too demanding of computer time. “He had the vision that this stuff would have an impact if you could make it accurate and available to everyone,” says Goddard. “It’s really brought quantum chemistry into the mainstream,” says Goddard.

Today, researchers use quantum calculations in many different areas—to predict which molecules exist in deep space, for example, or to design new drugs. Tom Zeigler at the University of Calgary in Canada uses density functional theory to predict which catalysts will be efficient at making polymers. “It is very costly to do this by experimentation and luck, so design is very important,” he says. Pople points out: “These are really all the same problem, insofar as the fundamental equations of quantum mechanics are universal.”

No one in chemistry will question the Nobel committee’s decision to honour Pople and Kohn, says Goddard. “They are the two people who have had the most impact in the area of quantum chemistry. I couldn’t imagine a better choice.”

Dangerous liaisons

Andy York — Fri, 23 Oct 1998 23:00:00 +0000

THE antics of unscrupulous operators of shark-diving tours could end in tragedy, say conservationists. They are worried by practices which may lead great white sharks to associate food with items such as surfboards or children’s toys. Any resulting attacks could undermine years of effort to save these endangered marine predators.

In South Africa, people pay for a face-to-face meeting with the great white shark, one of the ultimate predators of the seas. Tourists go diving in cages that are supposed to protect them. But as interest has grown, five or more boats at a time have sometimes jockeyed for position in the narrow channel at Dyer Island near Cape Town, a magnet for great whites thanks to a breeding colony of seals, their favourite prey.

If the dive operators all acted responsibly, this melee might be harmless, say conservationists. But some use rusty cages that other operators have scrapped. “Guaranteed there will be a death or bad injury,” says Craig Ferreira of the White Shark Research Institute in Cape Town, which itself runs carefully regulated shark-diving tours. Worse still, in addition to attracting sharks with food, some companies have been seen putting surfboards or children’s toys into the water. Sharks are naturally curious and mouth objects floating on the surface.

“The sharks are getting the opportunity to find out that every time they see a surfboard there might be food around,” says George Burgess, a shark expert at the Florida Museum of Natural History in Gainesville. “One day they will find out there is a human on the other side of the sandwich.”

There has been an increase in the number of shark attacks off the coast of South Africa this year. Most are by species other than great whites—indeed, there have been only 46 unprovoked great white attacks in South African waters since 1960. But if the activities of the dive operators are not curtailed, biologists fear that tourism-linked great white attacks are inevitable.

The experience of other shark tourism operations shows that sharks readily learn to associate boats with food. In the Caribbean, shark tour operators have for years conducted circus-like shows with black-tip and reef sharks, handing them fish. “The boat handlers even gun their engines to `call in their babies’ upon arrival at the dive sites,” says Burgess. Years after the tourist boats have moved on to other sites, the sharks continue to react to boat engines—which can prevent other divers and water sports enthusiasts using the areas.

Sarah Fowler of the Shark Trust in Newbury, Berkshire, argues that tourism can be harnessed to promote the conservation of sharks. “Done the right way, shark-dive tourism is very important for the future of sharks,” she says. But just one fatal great white attack on a tourist could undermine conservationists’ efforts, re-establishing the image of the sharks as cold-blooded killers and playing into the hands of those who would wish to slaughter them.

The South African government is aware of the problem, and in August imposed a temporary moratorium on cage diving in the Dyer Island channel. But Ferreira doubts that regulations proposed to control shark tourism will curb the worst excesses. “The authorities will continue to put commercial ventures first,” he says.

Knock on wood

Andy York — Fri, 16 Oct 1998 23:00:00 +0000

AN ELECTRONIC woodpecker that can identify trees with hidden rot could save
healthy trees from being damaged or felled.

Foresters looking for rot normally have to drill a hole in the trunk and take
a core sample. This damages the tree, so Geoff Lawday of Buckinghamshire
Chilterns University College near London wanted to find a less invasive and
harmful method.

Woodpeckers search for grubs and nesting sites by tapping a tree trunk and
assessing the sound it makes—and Lawday’s technique works in a similar
way. It involves hitting a tree with an ordinary hammer and then analysing the
stress waves that emerge from the opposite side. A piezoelectric crystal sensor
picks up these waves and converts them into an electrical signal that can be
downloaded onto a PC to be analysed.

“Rotting and healthy wood have different moisture contents, affecting the
vibrations of the waves differently,” says Lawday.

Tree analysis is often complicated by the presence of bark or damaged wood
which has repaired itself. With current methods, these are often mistaken for
rot, so healthy trees are cut down as a result. “Using our technique a clear
signature for rot can be obtained, and these are distinguishable from the other
abnormalities,” Lawday says.

Keep it up

Andy York — Fri, 02 Oct 1998 23:00:00 +0000

TINY magnetic particles could help to prevent buildings and bridges toppling
during earthquakes or hurricanes, say engineers at the University of Notre Dame
in Indiana. The particles form part of a switchable magnetic damping system that
cuts in before any damage is done.

Construction engineers incorporate dampers into their designs to absorb some
of the energy from external forces, prolonging a structure’s life and preventing
collapse during catastrophic events. Damping methods currently used in buildings
include rubber-like materials built into the structure, and flexible mechanisms
that isolate the building’s base from its superstructure. But the problem with
such methods is that the building has the same stiffness all the time.

Now Bill Spencer and Michael Sain at Notre Dame have developed a magnetic
device which can control the level of stiffness, for example as a building
begins to move in an earthquake. The pair felt that damping should increase
during a quake to dissipate energy that would otherwise be released
destructively in the structure. Under ordinary conditions, on the other hand, a
certain degree of flexibility is essential as it has to give a little in the
wind, for instance.

The Notre Dame devices sit on the basement floors of a building
(see Diagram)
and consist of a piston in a “magneto-rheological” fluid made up of tiny iron
particles suspended in oil. Normally the piston is able to move freely, but when
movement sensors in the building detect an acceleration above a preprogrammed
level, a computer switches on an electric current that powers a series of
electromagnets. The resultant magnetic field causes the iron particles to align
themselves vertically in the fluid, like little bar magnets, which stiffens the
fluid against sideways motion. According to the researchers, this added
stiffness resists the movement of the damping piston attached to the wall,
preventing the building swaying.

A 20-tonne prototype has been tested in a model three-storey building, with
forces equivalent to an earthquake measuring 6.9 on the Richter scale. The
dampers reduced the horizontal displacement of the top floor by 75 per cent.
“These dampers could extend the life of bridges and make buildings safe from
high winds and earthquakes,” says Shih-Chi Liu, programme manager at the
National Science Foundation, which funded the work.

Edmund Booth, visiting professor in the department of engineering science at
Oxford University, says: “These devices require low power input, and provided
they can be made fail-safe they have tremendous potential.”

Set in stone

Andy York — Fri, 18 Sep 1998 23:00:00 +0000

MEDUSA, the snake-haired monster of Greek myth whose looks turned people to
stone, is alive and well in the form of bacteria that turn mud to rock in a
geological twinkling of an eye. In doing so, these medusa bacteria may rapidly
fossilise the remains of mud-dwelling animals.

The formation of sedimentary rocks is usually an excrutiatingly slow
process, taking millions of years. But the two bacteria, discovered by a
research team led by Max Coleman, a sedimentologist at the University of
Reading, do the job in as little as six months.

While digging survey trenches in Norfolk salt marshes, Coleman noticed
strange stony nodules buried in the mud. “We found rocky lumps in what was
otherwise soft,” he says. Some were as large as footballs.

Coleman has established that a pair of bacteria join forces to create the
nodules. The first, a species of Desulfobacter, gets its energy by consuming
sulphates in seawater and reducing them to hydrogen sulphide. The second,
Desulfovibrio desulfuricans, can also perform the same chemical reaction. But
when its environment contains too much hydrogen sulphide, it switches to
reducing iron compounds, converting Fe³⁺ ions to Fe²⁺. The latter react with
the hydrogen sulphide and other salts to create stony deposits of iron sulphide
and iron carbonate.

These reactions do not seem to run in reverse. But if the nodules are exposed
to air, the iron at the surface can be oxidised once more, to form a layer of
rust.

Coleman believes the nodules could be a rich source of fossils. Because the
rock forms so quickly, he says, dead organisms might be preserved before they
can rot.

It’s gruesome work, but it’ll help put killers behind bars

Andy York — Fri, 18 Sep 1998 23:00:00 +0000

BY TRANSFORMING the analysis of stab wounds from crude guesswork into a
quantitative science, forensic engineers in Wales hope to produce a new tool for
solving murder cases. Working with Home Office pathologists, they are developing
a database that should tell the courts exactly how much force was used to
inflict a victim’s wounds.

The analysis of stab wounds has lagged behind the powerful techniques
developed for analysing events such as fires, car crashes and bombings. Forensic
scientists are often asked to comment on the force that would have been required
to inflict a wound—which can be important in determining whether someone
accused of murder intended to kill, or whether they had the strength to inflict
the fatal injury. But at present, expert witnesses can usually give only a
subjective assessment.

Leonard Nokes, Mike Jones and their colleagues at the University of Wales,
Cardiff, are collecting data by attempting to reproduce stab wounds on the
actual murder victims. “We get the permission of the authorities and the
relatives of the deceased before we carry out any testing,” Nokes stresses.
Already, data from some of the team’s tests have been presented as evidence in
court.

The goal, however, is to remove the need to conduct such gruesome
experiments. By compiling a database of the characteristics of wounds created
with different implements and degrees of force, the Cardiff team aims to create
a computer system that can accurately determine the force needed to inflict a
victim’s wounds.

“Eventually, this research will allow us to build up a computer model so we
can analyse wounds without resorting to bodies,” Nokes says. The researchers are
also developing clay-like materials that mimic the mechanical properties of
human flesh. Nokes told the BA that they expect to complete their database in
two years’ time. Their research may also help companies working to improve the
design of stab-proof body armour.

Termites are a rainforest’s best friend

Andy York — Fri, 11 Sep 1998 23:00:00 +0000

THE popular image of termites as timber-munching pests or builders of
towering nest mounds is badly in need of a makeover.

In tropical forests, the vast majority of termites conform to neither
stereotype, say researchers at the Natural History Museum in London. Instead,
most termites eat rotting vegetation in the soil and nest underground. They may
be as important to the survival of tropical forests as earthworms are to the
health of your garden.

Over the past five years, Paul Eggleton and his colleagues have been
measuring the biomass and biodiversity of organisms in soils in Cameroon, west
Africa. Soil-dwelling termites, many from species new to science, accounted for
more biomass than any other animal group. The total mass of the world’s termites
may be three times that of its human population, Eggleton told the BA. “Until
now nobody was aware of the enormous weight of termites underground, since they
are less obvious than their mound-building cousins,” says Richard Davies, a
member of the team.

These subterranean species dig intricate networks of tunnels, shifting the
soil and improving its aeration. By consuming rotting vegetation, they help to
recycle nutrients taken from the soil by trees and other plants. “Termites can
quite accurately be described as the earthworms of tropical soils,” says
Eggleton.

Davies hopes the new findings will rid termites of their reputation as pests.
“Only a few species feed on wood,” he says.