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1 There's a dimmer switch inside the sun that causes its brightness to rise
and fall on timescales of around 100,000 years - exactly the same period as
between ice ages on Earth. So says a physicist who has created a computer model
of our star's core.
2 Robert Ehrlich of George Mason University in Fairfax, Virginia, modelled
the effect of temperature fluctuations in the sun's interior. According to the
standard view, the temperature of the sun's core is held constant by the
opposing pressures of gravity and nuclear fusion. However, Ehrlich believed that
slight variations should be possible.
3 He took as his starting point the work of Attila Grandpierre of the Konkoly
Observatory of the Hungarian Academy of Sciences. In 2005, Grandpierre and a
collaborator, Gábor ágoston, calculated that magnetic fields in the sun's core
could produce small instabilities in the solar plasma. These instabilities would
induce localised oscillations in temperature.
4 Ehrlich's model shows that whilst most of these oscillations cancel each
other out, some reinforce one another and become long-lived temperature
variations. The favoured frequencies allow the sun's core temperature to
oscillate around its average temperature of 13.6 million kelvin in cycles
lasting either 100,000 or 41,000 years. Ehrlich says that random interactions
within the sun's magnetic field could flip the fluctuations from one cycle
length to the other.
5 These two timescales are instantly recognisable to anyone familiar with
Earth's ice ages: for the past million years, ice ages have occurred roughly
every 100,000 years. Before that, they occurred roughly every 41,000 years.
6 Most scientists believe that the ice ages are the result of subtle changes
in Earth's orbit, known as the Milankovitch cycles. One such cycle describes the
way Earth's orbit gradually changes shape from a circle to a slight ellipse and
back again roughly every 100,000 years. The theory says this alters the amount
of solar radiation that Earth receives, triggering the ice ages. However, a
persistent problem with this theory has been its inability to explain why the
ice ages changed frequency a million years ago.
7 "In Milankovitch, there is certainly no good idea why the frequency should
change from one to another," says Neil Edwards, a climatologist at the Open
University in Milton Keynes, UK. Nor is the transition problem the only one the
Milankovitch theory faces. Ehrlich and other critics claim that the temperature
variations caused by Milankovitch cycles are simply not big enough to drive ice
ages.
8 However, Edwards believes the small changes in solar heating produced by
Milankovitch cycles are then amplified by feedback mechanisms on Earth. For
example, if sea ice begins to form because of a slight cooling, carbon dioxide
that would otherwise have found its way into the atmosphere as part of the
carbon cycle is locked into the ice. That weakens the greenhouse effect and
Earth grows even colder.
9 According to Edwards, there is no lack of such mechanisms. "If you add
their effects together, there is more than enough feedback to make Milankovitch
work," he says. "The problem now is identifying which mechanisms are at work."
This is why scientists like Edwards are not yet ready to give up on the current
theory. "Milankovitch cycles give us ice ages roughly when we observe them to
happen. We can calculate where we are in the cycle and compare it with
observation," he says. "I can't see any way of testing [Ehrlich's] idea to see
where we are in the temperature oscillation."
10 Ehrlich concedes this. "If there is a way to test this theory on the sun,
I can't think of one that is practical," he says. That's because variation over
41,000 to 100,000 years is too gradual to be observed. However, there may be a
way to test it in other stars: red dwarfs. Their cores are much smaller than
that of the sun, and so Ehrlich believes that the oscillation periods could be
short enough to be observed. He has yet to calculate the precise period or the
extent of variation in brightness to be expected.
11 Nigel Weiss, a solar physicist at the University of Cambridge, is far from
convinced. He describes Ehrlich's claims as "utterly implausible". Ehrlich
counters that Weiss's opinion is based on the standard solar model, which fails
to take into account the magnetic instabilities that cause the temperature
fluctuations.
Questions 1-4
Complete each of the following statements with One or Two names of the
scientists from the box below.
Write the appropriate letters A-E in boxes 1-4 on your answer sheet.
A. Attila Grandpierre
B. Gábor ágoston
C. Neil Edwards
D. Nigel Weiss
E. Robert Ehrlich
1. ...claims there a dimmer switch inside the sun that causes its brightness
to rise and fall in periods as long as those between ice ages on Earth.
2. ...calculated that the internal solar magnetic fields could produce
instabilities in the solar plasma.
3. ...holds that Milankovitch cycles can induce changes in solar heating on
Earth and the changes are amplified on Earth.
4. ...doesn't believe in Ehrlich's viewpoints at all.
Questions 5-9
Do the following statements agree with the information given in the reading
passage?
In boxes 5-9 on your answer sheet write
TRUE if the statement is true according to the passage
FALSE if the statement is false according to the passage
NOT GIVEN if the information is not given in the passage
5. The ice ages changed frequency from 100,000 to 41,000 years a million
years ago.
6. The sole problem that the Milankovitch theory can not solve is to explain
why the ice age frequency should shift from one to another.
7. Carbon dioxide can be locked artificially into sea ice to eliminate the
greenhouse effect.
8. Some scientists are not ready to give up the Milankovitch theory though
they haven't figured out which mechanisms amplify the changes in solar
heating.
9. Both Edwards and Ehrlich believe that there is no practical way to test
when the solar temperature oscillation begins and when ends.
Questions 10-14
Complete the notes below.
Choose one suitable word from the Reading Passage above for each answer.
Write your answers in boxes 10-14 on your answer sheet.
The standard view assumes that the opposing pressures of gravity and nuclear
fusions hold the temperature ...10...in the sun's interior, but the slight
changes in the earth's ...11... alter the temperature on the earth and cause ice
ages every 100,000 years. A British scientist, however, challenges this view by
claiming that the internal solar magnetic ...12... can induce the temperature
oscillations in the sun's interior. The sun's core temperature oscillates around
its average temperature in ...13... lasting either 100,000 or 41,000 years. And
the ...14... interactions within the sun's magnetic field could flip the
fluctuations from one cycle length to the other, which explains why the ice ages
changed frequency a million years ago.
Trouble with Teamwork
Mary Owen examines the role and efficiency of teams
Recruiters say that candidates who can give examples ofwork they have done as
members of a successful team are in asstrong a position as those who can point
to significant individualachievement. Indeed, too much of the latter may suggest
thatthe person concerned is not a 'team player' - one of the moreserious
failings in the book of management.
The importance of being a team player is a side effect of the increasing
interaction acrossdepartments and functional divides. Instead of pushing
reports, paperwork and decisions aroundthe organisation, 'teams provide a
dynamic meeting place where ideas can be shared and expertisemore carefully
targeted at important business issues,' says Steve Gardner, in his book
KeyManagement Concepts. He adds, 'Globalisation has added a further dimension to
teamwork.Multinational teams now study policy decisions in the light of their
impact on the local market.'
But is teamworking being overdone? 'Some managers are on as many as seven or
eightdifferent teams', says Dr Cathy Bandy, a psychologist who recently ran a
conference on thesubject. 'They take up so much time that managers can't get on
with core tasks.' Forming teamsand having meetings has, she says, become an end
in itself, almost regardless of purpose. There isalso the danger of an unhealthy
desire to keep the team going after the work has been done. 'People feel the
need to belong, and team membership can provide a kind of
psychologicalsupport.'
The idea behind teamworking is that, when the right group of people is
brought together, a'force' develops which is greater than the sum of their
individual talents. This is often true in sport,where good players can reach
unexpected heights as members of an international team.However,few business
situations have as clear a set of objectives, or as clear criteria of success
orfailure, as winning a match.
'In business, everyone needs to be clear about what the challenge is and
whether a team isthe right way of approaching it', says Steve Gardner.
'Unfortunately, people focus instead on whothe members of the team should be and
what roles they are to play' Dr Bandy agrees. 'There isalways a danger that
teams can turn into committees,' she says. 'In a lot of situations, one or
twoindividuals would be much more effective.'
So what makes a successful team? There are some general qualities that have
been identified.Steve Gardnerrecommends that in every team there should be
someone who is good atresearching ideas and another who is good at shooting down
impractical ones. There should bethose who can resolve the tensions that
naturally occur in a team and others who are focused ongetting the job done.
Also, providing a clear and achievable target at the outset is the best way
ofensuring that the team will move on to greater things.
13、 What point does the writer make about teamworking at the beginning of the
article?
A It is the most successful form of management.
B It has changed the recruitment procedure in companies.
C Well-run teams still allow individuals to demonstrate their talents.
D Being a team player is now considered an essential management skill.
14 、According to the article, teamwork developed within companies as a
response to
A modern office design.
B changing work practices.
C a reduction in administrative tasks.
D the expansion of international business.
15 、In the third paragraph, Dr Bandy suggests that
A many employees do not enjoy working in teams.
B some managers are not very effective team leaders.
C some teams are created unnecessarily.
D few teams are well organised.
16 、According to the writer, teamwork is more effective in the field of sport
because the players
A know what they want to achieve.
B are more competitive by nature.
C have more individual talent.
D can be driven by national pride.
17 、Steve Gardner and Dr Bandy agree that when a business team is created
people do notpay enough attention to
A the structure of the team.
B alternatives to the team.
C selecting the team members.
D directing the team's activities.
18、 What is Steve Gardner's advice on operating a successful team?
A Maintain a flexible approach to membership.
B Allow personalities to develop within the team.
C Select people who fit naturally into certain roles.
D Make every effort to avoid conflict between members.
