to obtain power from the sun
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yds için okuma parçaları, reading comprehensionTRANSCRIPT
To obtain power from the sun’s rays is to use
nuclear power developed at no expense in a
laboratory 93 million miles away. For the radiant
energy of the sun is maintained by nuclear
transformation of chemical elements occurring in
the sun’s interior at temperatures of many million
degrees, and at pressures of many million
atmospheres. The resources of solar power are
enormous. If 100 per cent efficiency could be
secured in the transformation of radiant solar
energy into mechanical work, a horsepower per
square yard of ground surface would be available
under cloudless skies. The expense of collecting
solar energy still prevents its competition with the
usual power sources. Yet, unless the vague promise
of safe thermonuclear power from oceans becomes
realized, solar power must supply the enormous and
growing requirements of posterity within two
centuries. Because the ground sources (coal, oil and
uranium) as they near exhaustion will become more
costly than solar power.
Despite all the attention we give to our hair, and
putting aside the fact that the first synthetic hair
dyes were created in 1907, it has really only been in
the last 50 years or so that hair has been
scientifically studied. Before that, it was deemed too
trivial to be worthy of the attention, but the amount
that scientists can now tell about a person from the
study of their hair, often simply by looking at it
under a microscope, is remarkable. Humans have
around five million body hairs which is as many as
a chimpanzee has, although ours are smaller and
finer. They come in three types. An unborn baby has
a kind of fine down all over its body that begins to
grow about 12 weeks after conception. Normally,
these “lanugo” hairs are shed a few weeks before
birth, although some premature babies are born
with them. After birth and throughout our lives,
humans are covered in short “vellus” hairs just a
centimetre or two long and with little or no pigment.
Finally, the pigmented, thicker hairs that grow in
varying quantities on our heads, groin, armpits,
forearms and legs, and (on men) chests, stomachs
and faces, are “terminal” hairs.
Although the idea of the skyscraper is modern, the
inclination to build upward is not. The Great
Pyramids, with their broad bases, reached heights
unapproached for the next four millennia.But even
the great Gothic cathedrals, crafted of bulky stone
into an aesthetic of lightness and slenderness, are
dwarfed by the steel and reinforced concrete
structures of the 20th century.It was modern
building materials that made the true skyscraper
structurally possible, but it was the mechanical
device of the elevator that made the skyscraper truly
practical.Ironically, it is also the elevator that has
had so much to do with limiting the height of most
tall buildings to about 70 or 80 stories.Above that,
elevator shafts occupy more than 25 percent of the
volume of a tall building, and so the economics of
renting out space argues against investing in greater
height.
Until the early 1960s, the picturesque ruins of
Aphrodisias were scattered in and around the very
pretty village of Geyre, where the houses had been
built largely from remnants of the ancient city. But
the present excavations, which began in 1961, have
now reached such a scale that the village and its
inhabitants have been moved to another site
nearby. Some of the superb sculptures unearthed
are now exhibited in a new museum, which is
located in what was once Geyre’s village square,
while others can be seen around the archaeological
zone, one of the most interesting and beautiful sites
in all of Turkey. Surprisingly, the excavations at
Aphrodisias have unearthed remains of a settlement
dating back to about 5,800 B,C. The site seems to
have been a very ancient shrine of Ishtar, the
fertility goddess of Nineveh and Babylon, who was
one of the predecessors of Aphrodite, the Greek
goddess of love. In fact, the earliest Greek sanctuary
of Aphrodite on this site dates from the sixth
century B,C, and it was from this sanctuary during
the next four centuries that the cult of Aphrodite
spread throughout the Graeco-Roman world.
Strictly speaking the term " avalanche " should be
restricted to falls of snow and ice in mountainous
regions but popular usage has extended its meaning
to cover rock falls and landslips in all environments.
The period of greatest danger from avalanches
proper is during a thaw, when melt-water makes a
good lubricant for the snow and ice banked steeply
against rock faces. The rising cloud of white dust,
the vertical grooves and patches of bare rock formed
by the scouring action, and the dull roar of the
avalanche are all common features of mountains
above the permanent snow line. Rock fragments
may also be carried down, for the recurrent freezing
and thawing of water lodged in joints and crevices
of the rock forms a powerful agent of disintegration.
The action is the same as that which leads to burst
pipes. Freezing causes expansion of the water in the
spaces of a joint and produces a pressure sufficient
to break the rock.
The immediate cause of obesity is the prolonged
consumption of a diet containing more calories than
are needed to provide for the body’s tissue repair,
vital functions and physical activities. In modern
society, food has become very plentiful and
attractive, and the physical effort demanded by
many occupations has diminished. Most people in
civilized communities eat more than they require,
and it is surprising that obesity is not more common
than it is. It is difficult to escape the conclusion that
there exists some unknown mechanism by which
the body is enabled to get rid of the surplus calories
which would otherwise be stored as fat. If there were
not such a mechanism, obesity would be much
more common.
During the past few decades four East Asian
economies – South Korea, Taiwan, Singapore and
Hong Kong – have achieved the fastest rates of
economic growth the world has ever seen. In 1962
Taiwan stood between Zaire and the Congo on the
global ranking of income per head: by 1986 its
neighbours were Greece and Malta. In 1962 South
Korea was poorer than Sudan: by 1986 it was richer
than Argentina. Today the four “dragons” account
for 10 per cent of manufactured exports worldwide,
not far short of America’s 12 per cent.
Understanding this miracle is the most urgent task
in development economics. But most economists are
content to cite the dragons as proof of their favourite
theories – whatever those theories may be. Free
marketers point to the dragons’ reliance on private
enterprise, markets and relatively undistorted trade
regimes. Interventionists point with equal
assurance to clever bureaucracies, non-market
allocation of resources and highly distorted trade
regimes.
A growing percentage of the American economy and of
other advanced industrial economies in Europe and Asia
depends on imports and exports. Foreign trade, both
exports and imports, accounts for a little over 25 per cent
of the goods and services produced in the United States,
and even more in countries such as Japan and Germany.
This percentage will grow in the future. The success of
firms today and in the future depends on their ability to
operate globally. Globalization of the world’s industrial
economies greatly enhances the value of information to the
firm and offers new opportunities to businesses. Today,
information systems provide the communication and
analytic power that firms need for conducting trade and
managing businesses on a global scale. Controlling the far-
flung global corporation, which includes communicating
with distributors and suppliers, operating 24 hours a day
in different national environments and servicing local as
well as international reporting needs, is a major business
challenge that requires powerful information system
responses. Globalization and information technology also
bring new threats to domestic business firms; because of
global communication and management systems,
customers now can shop in a worldwide marketplace,
obtaining price and quality information reliably, 24 hours
a day. This phenomenon heightens competition and forces
firms to play in open, unprotected worldwide markets. To
become effective and profitable participants in
international markets, firms need powerful information
and communication systems.
The acronym ‘radar’, for radio detection and
ranging, has been credited to the US Navy, which
used it officially towards the end of 1940, but the
concept of radar is somewhat older. Hertz showed
that metals would reflect electromagnetic waves and
Tesla is said to have suggested using this
phenomenon in a radar-like manner in 1899. A few
years later a German, Christian Hulsmeyer,
received patents for a ship's anti-collision device.
Also many radio engineers and experimenters
observed that passing aircraft or ships interfered
with their experiments. Although these features are
all suggestive of radar, none was actually radar
unless the term is very loosely defined. In the 1930s,
however, several of the major powers became aware
of the military possibilities of radar and work on it
started immediately in the USA, Britain, France,
Germany, Italy, Japan and the Soviet Union. By the
end of World War II, military radar, and military
radio navigation aids too, were well developed.
The hygiene hypothesis was first described in 1989
by David P. Strachan, a British epidemiologist, who
noticed that the more children in a family, the lower
the rates of allergies and eczema.Children in large
families tend to exchange colds and other infections
more often than children with fewer siblings, and
this increased exposure to pathogens perhaps
protected these children from allergies. That same
year, Erika von Mutius, an epidemiologist at Munich
University, was looking into the effect of hygiene on
asthma. Children from dirtier East Germany, she
was shocked to find, had dramatically less asthma
than their West German counterparts living in
cleaner, more modern circumstances.The East
German children had likely been exposed to many
more viruses and bacteria.According to the hygiene
hypothesis, exposure in early childhood to
infectious agents programs the immune system to
mount defences against disease-causing viruses,
bacteria and parasites.Better sanitary conditions
deprive the immune system of this training, so the
body fights against harmless particles as if they
were deadly threats. The resulting allergic reaction
leads to the classic signs of asthma. However,
although much data supports the hygiene
hypothesis for allergies, the same cannot be said for
asthma. Contrary to expectations, asthma rates
have increased drastically in urban areas in the US
that are not particularly clean.
Sir Philip Sydney was a 16th-century English poet
and critic.His Defence of Poesy is the only major
work of literary criticism in sixteenth-century
England, a period during which Italy and France
produced large numbers of critical treatises,
heavily influenced by Aristotle’s Poetics.By
contrast, Sydney’s text is highly eclectic, drawing
together aesthetic principles from several traditions
and emphasizing especially those principles that
are of primary importance to the Elizabethans:
ideal imitation, moral teaching and
decorum.Looking back to Aristotle, Sidney defines
poetry as an imitation of nature, but links that
imitation to his view of the poet as maker.The poet
imitates not the real nature we see but rather he
imitates an ideal nature.Sydney also makes large
claims for the didactic role of poetry, following
Horace’s idea that poetry teaches by delighting.
With their magnificent architecture and
sophisticated knowledge of astronomy, and
mathematics, the Maya boasted one of the great
cultures of the ancient world. Although they had not
discovered the wheel and were without metal tools,
the Maya constructed massive pyramids, temples
and monuments of stone both in large cities and in
smaller ceremonial centers throughout the lowlands
of the Yucatan Peninsula, which covers parts of
what are now southern Mexico and Guatemala and
essentially all of Belize. From celestial observatories,
they tracked the progress, for example, of Venus
and developed, a calendar based on a solar year of
365 days. They created their own system of
mathematics, using a base number of 20 with a
concept of zero. And they developed a hieroglyphic
scheme for writing, one that used hundreds of
elaborate signs.
Weeds are plants out of place, either as the wrong
plant in cultivated ground, or as any plant where
none should be. They can cause considerable
financial loss through the cost of their control and
the damage they do to crops. Plants which become
really troublesome as weeds are those which persist
despite man’s efforts to control them. Such
persistency is due to several factors of which
perhaps the most important are prolific seed
production, coupled with the often remarkably long
periods of dormancy of the seed, and the ability of
vegetative parts of some plants to survive
mechanical damage and adverse conditions and to
set up new plants. Weeds may be controlled by
hand, by cultivation and other mechanical means,
by biological means and by chemical weedkillers.
Chemical weedkillers are widely used, either to give
a total kill and suppress all vegetation or to control
weeds selectively in crops.
Morphine, which is given as a painkiller to many
people with cancer, might stimulate the growth of
tumours, say researchers in the US. Their worrying
findings have been questioned by others in the field,
but all agree that further studies are urgently
needed to settle the issue. In test-tube experiments
and in mice, Kalpna Gupta and her colleagues
found that morphine encourages the growth of
blood vessels, known as angiogenesis. The
increased blood supply accelerated the growth of
breast tumours in mice. Although the researchers
have not yet looked for this effect in people, Gupta
warns that morphine could be harmful for patients
with any form of solid tumour that depends on a
healthy blood supply. She stresses that nobody
should yet consider altering their use of morphine
because of her findings. “But clinical studies must
be done,” she says.
Unlike the older forms of occultism, such as magic
and astrology, organized occultism is a modern
phenomenon. Few of the various organized occult
movements have existed for more than 150 years;
some were formed as a belated countermovement to
the Enlightenment, when people began to follow
rational schools of thought. Today’s occult views are
based on the idea that there are events within
nature, as well as within one’s spiritual life, which
seem mysterious and cannot be explained by
science. Examples include extrasensory perceptions
such as telepathy and telekinesis, and haunted
places or people. Believers maintain that these
phenomena stem from unknown powers that can
often be accessed only by some people with special
abilities.
Sweden maintained a position of neutrality during
both World Wars and this, in part at least, enabled
her to build up an elaborate structure of welfare
legislation that many larger nations were later to
imitate. The first major step was the establishment,
in 1911, of old-age pensions. Economic prosperity
based on its neutralist policy enabled Sweden,
together with Norway, to pioneer in public health,
housing, and job security programs. Forty-four
years of Socialist government were ended in 1976
with the election of a conservative coalition.
Presently, the Socialists were again returned to
power, only to be ousted in September 1991. The
new coalition of four conservative parties promised
to reduce taxes and cut back on the welfare state
but not alter Sweden’s traditional neutrality. Under
them, in a 1994 referendum, voters approved
joining the European Union. Although supportive of
a European monetary union, Sweden decided not to
adopt the euro when it first appeared in 1999.
During our visit in the summer of 1994 to the
Chernobyl Exclusion Zone, a region within a 30 km
radius of the Chernobyl Nuclear Power Plant, we
were amazed by the diversity of mammals living in
the shadow of the ruined reactor only eight years
after the meltdown. During our excursion through
the woods, we trapped some of the local mice for
examination in a makeshift laboratory. We were
surprised to find that, although each mouse
registered unprecedented levels of radiation in its
bones and muscles, all the animals seemed
physically normal, and many of the females were
carrying normal-looking embryos. We found that
the mice did not have any obvious chromosomal
damage. We wondered whether the absence of
injury could be explained by some sort of adaptive
change, perhaps a more efficient DNA-repair
mechanism, after many prior generations had been
exposed to radiation. But when we transplanted
wild mice from uncontaminated regions into cages
in the Exclusion Zone and then examined their
chromosomes, they were likewise unaffected by the
radiation. In at least this respect, the mice seemed
to have a natural "immunity" to harm from
radiation.
Autism, from the Greek word for “self,” was first
identified as a disorder in 1943. Initially, it was
thought to be a psychological disorder brought on
by cold or unemotional mothers, and curable by
intensive sessions of psychotherapy. During the
1960s, specialists realized that autistics frequently
had epilepsy and abnormal brain scans, which led
to the condition being recognized as a brain disorder
by the 1970s. Autism is now known to be a
hereditary neurological condition, about three times
more common in boys than girls. Usually, autistics
lack the ability to relate normally to other people
and have an anxious desire to maintain a routine,
which evolves with age into intense interests or
obsessions. Many autistic people deliver
monologues on topics while unaware of other
people’s comments or possible discomfort. There are
several related, but different, forms of autism.
Depending on the severity, symptoms can
sometimes be alleviated with carefully controlled
antidepressants, although sufferers typically find it
difficult to function normally in society.
The First World War could be called the War of the
Ottoman Succession. It was, in part, a struggle
between Austria and Russia for domination in the
areas in the Balkans once ruled by the Ottoman
Empire. Its first shots were fired in the former
Ottoman city of Sarajevo. Throughout the summer
and autumn of 1914, as the European powers were
locked in battle, the Ottoman government hesitated.
Finally, at the end of October, against the wishers of
his colleagues, Enver Pasha decided to attack
Russian targets with the new warships in the Black
Sea. His decision led to war across Europe, the
collapse of the Ottoman Empire and the end of
stability in the Middle East. Initially, the alliance
between the Ottoman Empire and the Central
Powers worked well. In the first half of the 20th
century, Germany was not the source of horror that
it later became. Britain, France and Russia were the
enemies to be feared and resented. By comparison,
Germany appeared friendly. The Ottoman
government calculated that its alliance with the
Central Powers would restore the glory of the
empire, help it recover some of the islands lost to
Greece in 1913, and perhaps lead to an extension of
territory in Turkish-speaking central Asia.
Developing markets, historically the domain of
hyperinflation and political manipulation, now
enjoy high surpluses, thanks to record commodity
prices and severe fiscal discipline. Since 2001 these
economies have achieved three times the average
annual per-capita economic growth of their
developed counterparts and now represent a
quarter of global output. Stocks in emerging
markets are causing much excitement among
investors. However, too much excitement invites
peril. Emerging markets have undeniably changed
in the past decade, but lately they are looking
overgrown, and even a minor crisis could send them
tumbling. And while the potential triggers for a fall
have changed, they are still there. As economies in
the developing world get stronger, governments are
getting more assertive and meddling with both
companies and neighbouring countries, increasing
political risk.
The amount of engineering and exertion required to
do work in space came as a surprise in the early
days of the manned space program. For instance,
when the astronauts Eugene Cernan and Thomas
Stafford launched into space aboard Gemini 9 on
June 3rd, 1966, they had no way of knowing that a
nightmare would begin as soon as Cernan began a
space walk. From the moment he emerged from the
capsule, everything Cernan did was much harder
than he had expected. Every weightless movement
triggered an equal, opposite reaction, and he found
himself repeatedly flying out to the end of the
umbilical cord connecting him to the Gemini
capsule and then rebounding in an unexpected
direction. Stafford finally ordered Cernan to forget
about the 10-million-dollar backpack and return to
the capsule. Doing so turned out to be the most
alarming part of the space walk, as Cernan
discovered that his pressurized suit wouldn’t flex
enough to allow him back inside so that operation
alone took him thirty laborious minutes. Then the
struggle to close the hatch was so prolonged and
difficult that Stafford decided he needed to lie, so
the ground crew would not panic. “Coming in, no
problem,” he fibbed as he and Cernan improvized a
lever to force the latch into position. It finally closed.
Haemorrhage is an escape of blood from the vessels
through which it normally circulates. The quantity
lost may be microscopic, or may amount to quite a
large quantity; large haemorrhages usually arise
from a large artery or vein, while bleeding from a
capillary may be shown only by a minute red spot
in the skin. Many haemorrhages are trivial and
require no specific treatment. Examples of these are
such common domestic accidents as cut fingers and
nose bleeds. Others form some of the major
emergencies of medicine.The principles of treatment
are to arrest haemorrhage, to combat shock by
restoring normal blood volume, and to keep the
patient quiet, comfortable and confident.
Narva is a quiet northeastern Estonian town bathed
in sea breezes. Though small, with a population of
just over 72,000, it occupies a large place in Russian
history. It was here in 1700 that, by attacking the
Swedes, who were then in control of much of the
Baltic coast, Russia launched its final campaign in
a centuries-long quest to become a European power.
The battle ended in defeat for the Russians, but the
war did not; by 1721 Russia had conquered the
Baltic territories as far southwest as Riga, the
capital of present-day Latvia, and had built a new
capital, Saint Petersburg, on the Gulf of Finland.
Later in that century, Russia, through a partition
agreement with Austria and Prussia, gained control
of the rest of the Baltics, and would retain them
until the fall of the Soviet Union in 1991.
Which European country has the worst record for
shoplifting?. The answer is Britain and she holds
the record now for the second year running,
according to a survey released on September 19th.
Britons not only steal more than their continental
counterparts, they are also less competent
employees on the shop floor, resulting in Britain
having the worst overall rate of retail “ shrinkage ” -
a measure of losses by retailers from theft,
mispricing and other wastage. Continental
Europeans are actually not much better. Shrinkage
is increasing alarmingly in some countries and is
generally on the rise. Denmark is a notable example.
According to one survey, shrinkage there is 9% up
on last year. Shrinkage costs the European
economy a surprisingly large amount, in fact, the
total annual cost has been estimated at around £30
billion which is equivalent to a shocking £80 per
person in the region. That is more than the costs of
the much-higher-profile car crime or domestic
burglary.
On 31 October 1994, a turboprop airliner heading
for Chicago, Illinois, crashed into a soybean field at
Roselawn in Indiana. All 68 people aboard died.
Although the weather was cold and damp that day,
no one could believe it when investigators revealed
that the crash was caused by a buildup of ice on the
wings. Not only did this modern plane have a fully
functional deicing system, but according to US
Federal Aviation Administration (FAA) standards,
the Frenchbuilt ATR72 should have had no
problems flying in the cold, damp conditions. The
pilots even knew their craft was icing up and
attempted to clear it, following deicing procedures
exactly.
The causes of schizophrenia are unknown, although
the disease has a strong genetic component. Studies
of identical twins show that if one twin has
schizophrenia, there is a 50% chance that the other
twin will have it, too. Since identical twins share
identical genes, this indicates that schizophrenia
has an equally strong environmental component,
the nature of which has not been identified. Current
treatments for schizophrenia focus on brain
pathways that use dopamine as a neurotransmitter.
Despite their ability to alleviate symptoms, many of
the drugs used to treat schizophrenia have such
negative side effects that patients frequently stop
taking them. Now that the human genome has been
sequenced, there is a vigorous effort under way to
find the mutant genes that predispose a person to
the disease. This effort includes sequencing DNA
from families with a high incidence of
schizophrenia.
In the last third of the 19th century, new
technologies transformed the face of manufacturing
in Europe, leading to new levels of economic growth
and complex realignments among industry, labour
and national governments. Like Europe’s first
industrial revolution, which began in the late 18th
century and centred on coal, steam and iron, this
“second” industrial revolution relied on innovation
in three key areas: steel, electricity, and chemicals.
For instance, steel, which was harder, stronger and
more malleable than iron, had long been used as a
construction material. But until the mid-nineteenth
century, producing steel cheaply and in large
quantities was impossible. That changed between
the 1850s and 1870s, as new and different
processes for refining and mass-producing alloy
steel revolutionized the metallurgical industry.
Although iron did not disappear overnight, it was
soon eclipsed by soaring steel production. So, steel
began to be used for various purposes. In Britain,
for example, shipbuilders made a quick and
profitable switch to steel construction, and thus
kept their lead in the industry. Germany and the
US, however, dominated the rest of the steel
industry. By 1901, Germany was producing almost
half as much steel as Britain and was able to build
a massive national and industrial infrastructure.
George Vancouver was a British naval explorer who
served as a seaman on Captain Cook’s second
voyage round the world (1772-75) and as a
midshipman on his third voyage (1776-80). He then
saw service in the West Indies. In 1791 he was
placed in charge of an expedition to the northwest
coast of North America to seek for a passage to the
interior of the continent which was rumoured to
exist in those parts. On the outward voyage by the
Cape of Good Hope, a portion of the southwest
coastline of Australia was examined, and Tasmania,
New Zealand and Hawaii were visited. Vancouver
spent three years in carefully surveying portions of
the west coast of North America. He was the first to
circumnavigate Vancouver Island, to which his
name was given by the Spaniards to commemorate
his achievement. The standard of his survey was
exceptionally high and worthy of his old captain,
James Cook; and his voyage practically disproved
the existence of a water-passage to the interior along
these coasts.
The Wireless Museum has several of the earliest
crystal wireless sets from the 1920s which ran on
electromagnetic waves with no external power
source, and were easily made at home. Valve radios,
which came along in the 1930s, needed electricity to
heat up the valves and the museum has both mains
and battery-powered valve radios on display. The
collection also has some rare wartime civilian
receivers — the only type of valve radio
manufactured during the Second World War. This
was by order of the government, because at this time
most manufacturing was focused on the war effort.
There are also plenty of modern day transistor
radios including a collection of novelty radios dating
from the sixties and seventies.
For humans to be able to hear a sound, it must be
both loud enough and within the right frequency
range – as measured by the number of vibrations
per second, or hertz (Hz).The average person is most
sensitive to sounds in the 1,000-5,000 Hz range,
and most lose the ability to hear very high
frequencies (above around 20,000 Hz) with age.Even
so a sizeable proportion of the population do seem
to remain sensitive to the very low frequency
“infrasound”.High-frequency sounds have more
than just audible effects as teenagers in Swindon
discovered in 2006.Tired of having crowds of
youngsters collecting around the town theatre, the
owners installed the Mosquito, a device that emits
sonic energy at very high frequencies.Only the
teenagers could hear it and it forced them to meet
elsewhere.