快速导航
学历类
职业资格
公务员
医卫类
建筑工程
外语类
外贸类
计算机类
财会类
技能鉴定
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.
The Importance of Good Communications
Effective communication is essential for all organizations. It links the
activities of the various parts of the organization and ensures that everyone is
working towards a common goal. It is also extremely important for motivating
employees. Staff need to know how they are getting on, what they are doing right
and in which areas they could improve. Working alone can be extremely difficult
and it is much easier if someone takes an interest and provides support.
Employees need to understand why their job is important and how it contributes
to the overall success of the firm. Personal communication should also include
target setting. People usually respond well to goals, provided these are agreed
between the manager and subordinate and not imposed.
However, firms often have communication problems that can undermine their
performance. In many cases,these problems occur because messages are passed on
in an inappropriate way. There are, of course, several ways of conveying
information to others in the organization which include speaking to them
directly, e-mailing, telephoning or sending a memo. The most appropriate method
depends on what exactly it is you are communicating. For example, anything that
is particularly sensitive or confidential, such as an employee's appraisal,
should be done face-to-face.
One of the main problems for senior executives is that they do not have the
time or resources needed to communicate effectively. In large companies, for
example, it is impossible for senior managers to meet and discuss progress with
each employee individually. Obviously this task can be delegated but at the cost
of creating a gap between senior management and staff. As a result, managers are
often forced to use other methods of communication, like memos or notes, even if
they know these are not necessarily the most suitable means of passing on
messages.
The use of technology, such as e-mail, mobile phones and network systems, is
speeding up communication immensely. However, this does not mean that more
investment in technology automatically proves beneficial: systems can become
outdated or employees may lack appropriate training. There are many
communications tools now available but a firm cannot afford all of them. Even if
it could, it does not actually need them all.The potential gains must be weighed
up against the costs, and firms should realize that more communicationdoes not
necessarily mean better communication."
As the number of people involved in an organization increase, the use of
written communication rises even faster. Instead of a quick conversation to sort
something out numerous messages can be passed backwards and forwards. This can
lead to a tremendous amount of paperwork and is often less effective than
face-to-face communication. When you are actually talking to someone you can
discuss things until you are happy that they have understood and feedback is
immediate. With written messages, however, you are never quite sure how it will
be received what you think you have said and what the other person thinks you
have said can be very different.
The amount of written information generated in large organizations today can
lead to communication overload. So much information is gathered that it gets in
the way of making decisions. Take a look at the average manager's desk and you
will see the problem -- it is often covered with letters, reports and memos.
This overload can lead to inefficiencies. For example, managers may not be able
to find the information they want when they need it. Communication is also
becoming more difficult with the changes occurring in employment patterns. With
more people working part-time and working at home, managing communication is
becoming increasingly complex.
1.In the first paragraph the writer recommends that communication with staff
should includeA. some feedback on their job performance.
B. an explanation of how company targets have been set.
C. information on promotion prospects within the company.
D. an indication of which duties they can expect assistance with.areas they
could improve
2.According to the writer, the best way of achieving effective communication
is toA. adapt the message to suit a particular audience.
B. make the content of messages brief and direct.
C. select the most suitable means of conveying a particular message.
D. ensure that information is targeted at the appropriate group of
people.
3.What does the writer say about the communication options available to
senior managers?A. Sending memos to staff is one of the most efficient
methods.
B. It is important to find the time to discuss certain matters with
staff.
C. They should increase the range of options that they use.
D. Getting junior managers to talk to staff can create different
problems.
4.What advice is given about the communication tools made available by
technology?A. Aim to limit staff use of certain communication tools.
B. Evaluate them in terms of the expenditure involved.
C. Select them on the basis of the facilities they offer.
D. Encourage more staff to attend training courses in their use.
5.According to the writer, a problem with written communication is thatA. the
message can be interpreted differently to what was intended.
B. it can be easy for people to ignore the contents of a written message.
C. most people are more comfortable with face-to-face communication.
D. it is possible for correspondence to get lost within a large
organization.
6.According to the article, what is the effect of receiving large amounts of
written information?A. It is counter-productive. "
B. It causes conflict in a company.
C. It leads to changes in work patterns.
D. It makes the main points more difficult to identify.
