Stuart Foster, an associate professor in the Department of Medical Biophysics
at the University of Toronto’s Sunnybrook Health Science Center, says that
ultrasound biomicroscopy allows physicians to examine eye tissue harmlessly
and in detail.

UBM has already been used on around 100 patients. The device allows
doctors to modify their scheme of treatment by monitoring the development
of lesions and tumours, says Charles Pavlin, the co developer of the system.
It resolves images more finely than normal ultrasound, and can even manage
features between 40 and 50 millionths of a metre across. UBM focuses on
areas 4 millimetres square compared with 4 centimetres square for normal
ultrasound.

Because resolution rises in tandem with the frequency of the sound waves
used in ultrasound devices, UBM works in a range between 50 to 100 megahertz,
compared with between 3 and 10 megahertz for conventional devices.

To achieve the desired resolutions, Foster and colleagues had to devise
new transducers for the device. These are 1-millimetre rods coated with
thin films of materials – usually zinc oxide – which focus sound and act
as ‘acoustic lenses’. They resolve better with higher frequencies. The team
at Toronto cracked the problem by coating the transducers with different
materials, either poly(vinylidene fluoride) or lead zirconate titanate.

The penalty for the higher resolution is that the devices can only image
shallow layers of tissue. As resolution increases, penetration of sound
waves into tissue decreases. UBM works to depths of about 4 millimetres,
which is ideal for many ophthalmic applications, but Foster expects improved
electronics and transducers to extend the depth of penetration and the breadth
of applications.

He speculates that UBM might eventually lead to the development of tiny
ultrasound scanning devices to insert into the body on catheters and needle-tip
probes. These, he says, could be used for diagnostic applications inside
blood vessels, bile ducts and the gastric canal.

A Festival of Discovery celebrating science and technology is to be
one of the first big events in Dublin’s year as European City of Culture.
It is the first time that a city has included science as a part of the cultural
programme since the scheme was launched in Athens in 1985.

Part of the reason for the recognition of science as an integral part
of culture may be due to the man in charge of Dublin ’91, Lewis Clohessy,
who is an engineer with a long-standing interest in the arts. It also reflects
the innovation and imagination that the Irish capital has brought to bear
to provide a bit of balance to Glasgow’s £50 million extravaganza
last year. Dublin is also making do with a small budget, 7 per cent of Glasgow’s.

Clohessy originally had £750 000 from National Lottery funds,
topped up with another £250 000 from EC and Dublin City coffers,
to spend. Last October he managed to cadge another £500 000 from the
government, and then doubled his bankroll with corporate sponsorships.

The Festival of Discovery reflects his own ability to combine science
and the arts successfully, and involves every-thing from hands-on exploration
and theatre to academic seminars and a meeting of Nobel prizewinners. Andy
Shearer has coordinated the festival events with the help of a voluntary
committee that includes space scientist Susan McKenna-Lawlor; Charles Mollan,
the Science and Arts Officer of the Royal Dublin Society, and representatives
of Eolas-the government’s science body-and several universities.

‘It will highlight the spirit of enquiry which is shared by the arts
and the sciences. It marks a less celebrated feature of Dublin’s cultural
life,’ says Ireland’s Minister for Science and Technology, Michael Smith.
‘We’re particularly honoured to welcome four Nobel prizewinners to join
Professor Ernest Walton, Ireland’s only Nobel laureate, in a public forum
during the Festival.’

The four (Sir Derek Barton, 1969; Arthur Schawlow, 1981; Sune Bergstrom,
1982; and Jean-Marie Lehn, 1987) will deliver lectures to specialist audiences
and then conduct a public forum on ‘Science and the Future’ at the Abbey
Theatre on 13 April.

Other events are aimed more directly at the general public. The Discovery
Dome, from Britain, is an interactive, travelling science exhibit based
originally on the Ontario Science Center in Canada. It will be erected in
Merrion Square, near the National Gallery and the National History Museum.
Its exhibits range from gravity and magnetism to optical illusions and tornadoes.
‘The Conquest of Form’, from 27 March to 27 April, is a computer art exhibition
by William Latham. It has been a major attraction at both the Natural History
Museum in London and in Bristol.

‘The Frontiers of Chaos’, the other major set piece, began on 7 March
and continues until 28 March. A display of computer graphics, the exhibition
is based on work from mathematicians and physicists at the University of
Bremen, Germany, and attempts to explain, mathematically, the unpredictable
nature of the Universe.

The National Museum is mounting a small display of scientific instruments
from its own collection starting 6 April.

The Molecule Theatre of Science from London will perform Gremlins in
the Works, a play for children about electricity and telecommunications
from 9 April to 13 April, while Lord Dynamite, an outdoor theatre piece
on the life of Alfred Nobel by Welfare State International has its world
premiere on 12 April at the Royal Hospital Kilmainham.

Other events include: a display by the Institution of Engineers of Ireland,
‘The Culture of Engineering’; ‘The Beauty of Physics’, the result of an
annual photographic competition organised by the Institute of Physics; and
‘Dance of the Universe/Cosmos’, two French exhibits from GLACS (Liaison
Group for Scientific Cultural Action), looking at the world of small particle
physics. There will also be programmes organised by the Irish Conservation
Organisation for Youth, the Irish Wildlife Federation, and a lecture on
‘Women in Irish Science and Technology’, .

Doug Payne is a science writer based in County Wicklow.

Letourneau and his colleagues studied ‘average’ Canadians, who ate a
typical ‘southern’ diet. They found that they absorbed about 100 per cent
of the caesium they ingested. On the other hand, the northern people ‘appeared
to absorb no more than 20 per cent of the ingested radiocaesium’, Letourneau
says. He presented his results at the annual meeting of the World Federation
for Nuclear Medicine and Biology held in Montreal.

Letourneau and his colleagues began their study in 1986 after tests
in Scandinavia revealed high levels of radioactivity in reindeer. They wished
to determine whether Canadian caribou – whose meat is a food staple in the
north – were similarly affected.

Caesium-137 disappears from the food chain fairly rapidly in temperate
climates because plants grow and die quickly. But in northern climates,
the isotope remains for some time on the surface of slow-growing lichen.
These form a major part of the caribou’s diet. ‘There was concern that northern
residents would accumulate fairly high doses of radioactivity from caribou
meat,’ says Letourneau.

The current study used baseline data obtained between 1965 and 1969,
when nuclear testing in the atmosphere was still being carried out. During
that period, the average dose people experienced was 0.8 millisieverts per
year (mSv/yr), with a maximum of 4.5 mSv/yr. (By comparison, a single chest
X-ray produces a reading of 0.1 mSv). During the latest study, the average
dose rate had declined to 0.08 mSv/yr, with a maximum of 0.25 mSv/yr. This
represents a decline from the previous study period.

The researchers collected samples of caribou meat throughout the Canadian
arctic over a two-year period. They also determined a mathematical formula
which related a person’s radiation dose to their consumption of the meat.

According to Letourneau, there is a fairly straightforward correlation
between a person’s intake of caribou and the caesium-137 in their body.
But an unexpected discovery was that the absorption of the isotope was nowhere
near as high as was first thought. ‘What we’re finding is that the way the
body handles radioactivity is dependent on the kind of lifestyle you have,’
says Letourneau.

Letourneau says that residents of northern Canada, especially the natives,
appear to be more active, and expend more energy. So caesium passes through
their bodies more quickly.

Hanrahan won his case against the American company Merck Sharpe &
Dohme two years ago, in the longest civil action in Irish history. The action
began in June 1976, when the company, the world’s second largest manufacturer
of drugs, opened a factory in Ballydine, near Carrick-on-Suir, County Tipperary,
to produce sulindac (then the world’s fourth largest selling drug) and Indocid
(then the sixth).

The company’s arrival in the quiet valley was widely welcomed. But within
two years the Hanrahan family was complaining of noxious odours, burning
skin, blisters in their mouths, running eyes and racking coughs. By the
early 1980s, 150 of their prize cattle and all the children’s pets had died.
Hanrahan’s cattle had more than the usual incidence of stillbirths and many
calves had horrible deformities; cows already in calf were coming on heat;
good milkers suddenly went dry. During 1985, Hanrahan’s vet recorded 300
calls to the farm.

Hanrahan lost his case in the High Court in 1980. But a Supreme Court
appeal began in late 1987. By this time his case had attracted international
attention and had been bolstered by a group of international scientific
advisors.

The Supreme Court’s ruling was momentous: ‘It is enough,’ the Justice
declared, ‘if it could be said that a reasonable person in the circumstances
of the Hanrahan family should not be expected to tolerate (such effects)
without the chemical company having to make financial amends.’ In other
words, the burden of proof in future cases would be lighter on those seeking
to show ill-effects from industrial processes.

The court also found that among the likely sources of the pollution
was ‘an incinerator for burning waste chemicals and solvents which, for
significant periods, was run at below its design temperature and at a heat
inadequate to destroy the chemicals’.

Merck expressed ‘great disappointment’ with the Supreme Court ruling,
but made efforts to reassure local people that the decision would not force
them out of the area.

The Supreme Court’s ruling was not the end of the case. Hanrahan had
to lodge his claim for 1.8 million Pounds, the world’s largest personal
claim related to an environmental issue, with the High Court. For the past
two-and-a-half years the company has held up proceedings by demanding that
Hanrahan must produce more documentation on the damage caused to his farm
and family before they will settle. The company has now agreed that all
the papers are in order, and Hanrahan can proceed with this claim. All he
is waiting for now is a date at the High Court.

The ruling, and the resulting public awareness of the environmental
issues involved, has already had an impact on the Irish chemicals industry.
(Six of the world’s top ten pharmaceuticals companies have factories in
the Republic.)

Since the ruling, Merrell Dow, another major pharmaceuticals company,
ran into a storm of protest in Cork when it announced plans to build there.
As a result, it withdrew its application for planning permission. A second
company, Sandoz, also faced strong public protests. Unlike Merrell Dow,
it persevered and has agreed to a strict range of environmental controls
imposed by the local authority.

Michael Coey, a professor at Trinity College Dublin, says that the new
material, an alloy of iron, samarium and nitrogen, is easily bonded with
plastic, rubber or polymers to make mass-produced magnets of any shape.
It can also work at a much higher temperature than current magnets.

The Japanese currently dominate the world market for permanent magnets,
estimated to be worth more than 500 million Pounds a year. The magnets with
the best properties, which are used in everything from industrial electric
motors to stereo loudspeakers, are made of a complex iron-boron-neodymium
alloy developed in Japan in 1983.

A European initiative to develop an alternative was launched five years
ago. The project, know as Concerted European Action on Magnets, or CEAM,
involves both industrial and academic research at more than 60 centres.

To make the new magnet, Coey’s group takes the compound Sm₂Fe₁₇ and
exposes it to nitrogen gas at several hundred °Celsius. The nitrogen
diffuses into the lattice to produce a new compound, Sm₂Fe₁₇Nx, with x being
about 2.5. The new compound retains its magnetic properties up to 475 °C,
165 degrees higher than Nd₂Fe₁₄B, the previous record holder.

‘Improved temperature stability will allow our magnets to be used in
a much wider range of motors, for example, where heat builds up,’ says Coey.

The new material also has a much stronger anisotrophy than its predecessors.
This means that its magnetic structure is more strongly aligned in one direction
so it retains its magnetism better.

To mass produce magnetic components it is usually easier to bond magnetic
particles into a plastic or polymer, which is easier to mould, rather than
use the solid alloy which is often brittle and corrosive. Producing the
necessary flakes of alloy from existing magnets is a complicated and expensive
process called melt spinning. Molten alloy is sprayed onto a spinning drum
where it cools.

However, the magnetic orientation in the flakes is in random directions
so the resulting magetisation of the original magnetic material.

The milling processes being developed for the new material produce powder
with aligned magnetisation so they may be able to achieve an energy product,
which is a measure of the amount of magnetic energy, four times that of
other bonded magnets.

Several research centres are now working with the new material and Coey
expects it to appear in commerical products within 12 to 18 months. Siemens
is one of many companies who have joined in the research and has achieve
significant progress with a mechanical alloying process.