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Rogue theory of smell gets a boost
1.A controversial theory of how we smell, which claims that our fine sense of
odour depends on quantum mechanics, has been given the thumbs up by a team of
physicists.
2.Calculations by researchers at University College London (UCL) show that
the idea that we smell odour molecules by sensing their molecular vibrations
makes sense in terms of the physics involved.
3.That's still some way from proving that the theory, proposed in the
mid-1990s by biophysicist Luca Turin, is correct.But it should make other
scientists take the idea more seriously.
4."This is a big step forward," says Turin, who has now set up his own
perfume company Flexitral in Virginia.He says that since he published his
theory, "it has been ignored rather than criticized."
5.Most scientists have assumed that our sense of smell depends on receptors
in the nose detecting the shape of incoming molecules, which triggers a signal
to the brain.This molecular 'lock and key' process is thought to lie behind a
wide range of the body's detection systems: it is how some parts of the immune
system recognise invaders, for example, and how the tongue recognizes some
tastes.
6.But Turin argued that smell doesn't seem to fit this picture very
well.Molecules that look almost identical can smell very different — such as
alcohols, which smell like spirits, and thiols, which smell like rotten eggs.And
molecules with very different structures can smell similar.Most strikingly, some
molecules can smell different — to animals, if not necessarily to humans —
simply because they contain different isotopes (atoms that are chemically
identical but have a different mass).
7.Turin's explanation for these smelly facts invokes the idea that the smell
signal in olfactory receptor proteins is triggered not by an odour molecule's
shape, but by its vibrations, which can enourage an electron to jump between two
parts of the receptor in a quantum-mechanical process called tunnelling.This
electron movement could initiate the smell signal being sent to the brain.
8.This would explain why isotopes can smell different: their vibration
frequencies are changed if the atoms are heavier.Turin's mechanism, says
Marshall Stoneham of the UCL team, is more like swipe-card identification than a
key fitting a lock.
9.Vibration-assisted electron tunnelling can undoubtedly occur — it is used
in an experimental technique for measuring molecular vibrations."The question is
whether this is possible in the nose," says Stoneham's colleague, Andrew
Horsfield.
10.Stoneham says that when he first heard about Turin's idea, while Turin was
himself based at UCL, "I didn't believe it".But, he adds, "because it was an
interesting idea, I thought I should prove it couldn't work.I did some simple
calculations, and only then began to feel Luca could be right." Now Stoneham and
his co-workers have done the job more thoroughly, in a paper soon to be
published in Physical Review Letters.
11.The UCL team calculated the rates of electron hopping in a nose receptor
that has an odorant molecule bound to it.This rate depends on various properties
of the biomolecular system that are not known, but the researchers could
estimate these parameters based on typical values for molecules of this
sort.
12.The key issue is whether the hopping rate with the odorant in place is
significantly greater than that without it.The calculations show that it is —
which means that odour identification in this way seems theoretically
possible.
13.But Horsfield stresses that that's different from a proof of Turin's
idea."So far things look plausible, but we need proper experimental
verification.We're beginning to think about what experiments could be
performed."
14.Meanwhile, Turin is pressing ahead with his hypothesis."At Flexitral we
have been designing odorants exclusively on the basis of their computed
vibrations," he says."Our success rate at odorant discovery is two orders of
magnitude better than the competition." At the very least, he is putting his
money where his nose is.
Questions 5-9
Complete the sentences below with words from the passage.Use NO MORE THAN
THREE WORDS for each answer.
5.The hypothesis that we smell by sensing the molecular vibration was made by
______.
6.Turin's company is based in ______.
7.Most scientists believed that our nose works in the same way as our
______.
8.Different isotopes can smell different when ______ weigh differently.
9.According to Audrew Horsfield, it is still to be proved that ______ could
really occur in human nose.
1. A European spacecraft took off today to spearhead the search for another
"Earth" among the stars.
2. The Corot space telescope blasted off aboard a Russian Soyuz rocket from
the Baikonur cosmodrome in Kazakhstan shortly after 2.20pm.
3. Corot, short for convection rotation and planetary transits, is the first
instrument capable of finding small rocky planets beyond the solar system. Any
such planet situated in the right orbit stands a good chance of having liquid
water on its surface, and quite possibly life, although a leading scientist
involved in the project said it was unlikely to find "any little green men".
4. Developed by the French space agency, CNES, and partnered by the European
Space Agency (ESA), Austria, Belgium, Germany, Brazil and Spain, Corot will
monitor around 120,000 stars with its 27cm telescope from a polar orbit 514
miles above the Earth. Over two and a half years, it will focus on five to six
different areas of the sky, measuring the brightness of about 10,000 stars every
512 seconds.
5. "At the present moment we are hoping to find out more about the nature of
planets around stars which are potential habitats. We are looking at habitable
planets, not inhabited planets. We are not going to find any little green men,"
Professor Ian Roxburgh, an ESA scientist who has been involved with Corot since
its inception, told the BBC Radio 4 Today programme.
6. Prof Roxburgh said it was hoped Corot would find "rocky planets that could
develop an atmosphere and, if they are the right distance from their parent
star, they could have water".
7. To search for planets, the telescope will look for the dimming of
starlight caused when an object passes in front of a star, known as a "transit".
Although it will take more sophisticated space telescopes planned in the next 10
years to confirm the presence of an Earth-like planet with oxygen and liquid
water, Corot will let scientists know where to point their lenses.
8. Measurements of minute changes in brightness will enable scientists to
detect giant Jupiter-like gas planets as well as small rocky ones. It is the
rocky planets - that could be no bigger than about twice the size of the Earth -
which will cause the most excitement. Scientists expect to find between 10 and
40 of these smaller planets.
9. Corot will also probe into stellar interiors by studying the acoustic
waves that ripple across the surface of stars, a technique called
"asteroseismology".
10. The nature of the ripples allows astronomers to calculate a star’s
precise mass, age and chemical composition.
11. "A planet passing in front of a star can be detected by the fall in light
from that star. Small oscillations of the star also produce changes in the light
emitted, which reveal what the star is made of and how they are structured
internally. This data will provide a major boost to our understanding of how
stars form and evolve," Prof Roxburgh said.
12. Since the discovery in 1995 of the first "exoplanet" - a planet orbiting
a star other than the Sun - more than 200 others have been found by ground-based
observatories.
13. Until now the usual method of finding exoplanets has been to detect the
"wobble" their gravity imparts on parent stars. But only giant gaseous planets
bigger than Jupiter can be found this way, and they are unlikely to harbour
life.
14. In the 2010s, ESA plans to launch Darwin, a fleet of four or five
interlinked space telescopes that will not only spot small rocky planets, but
analyse their atmospheres for signs of biological activity.
15. At around the same time, the US space agency, Nasa, will launch
Terrestrial Planet Finder, another space telescope designed to locate Earth-like
planets.
Choose the appropriate letter from A-D for question 1.
1. Corot is an instrument which
(A) can help to search for certain planets
(B) is used to find planets in the orbit
(C) can locate planets with human beings
(D) can spot any planets with water.
Do the following statements agree with the information given in the reading
passage? For questions 2-5 write
TRUE if the statement agrees with the information
FALSE if the statement contraicts the information
NOT GIVEN if there is no information on this in the passage
2. Scientists are trying to find out about the planets that can be
inhabited.
3. BBC Radio 4 recently focuses on the broadcasting of Corot.
4. Passing objects might cause a fall in light.
5. Corot can tell whether there is another Earth-like planet.
Based on your reading of the passage, complete the sentences below with words
taken from the passage. Use NO MORE THAN THREE WORDS for each answer.
With measurements, scientists will be able to search for some gaseous and
rocky planets. They will be extremely excited if they can discover some small 6.
__________, the expected number of which could be up to 7. __________ .
Corot will enable scientists to study the 8. __________ of stars. In this
way, a star’s mass, age and chemical composition can be calculated.
According to Prof Roxburgh, changes in light can be caused by passing planets
or star 9. __________. The related statistics can gain us a better 10.
__________ of the star formation and evolvement.
Observatories have found many exoplanets, which are 11. __________ other
stars than the Sun. The common way used in finding exoplanets can only detect
huge gas planets, which do not 12. ___________ .
With the launching of Darwin, astronomers will be able to analyse whether
those rocky planets have 13. __________ for life.
