داستان و مطالب مفید علمی
I'm Shirley Griffith.
And I'm Ray Freeman. Every week we tell about a person who was important in the history of the United States. This week we
tell about Helen Keller. She was blind and deaf but she became a famous writer and teacher.
VOICE ONE:
The name Helen Keller has had special meaning for millions of people in all parts of the world.
She could not see or hear. Yet Helen Keller was able to do so much with her days and years. Her
success gave others hope. Helen Keller was born June twenty-seventh, eighteen eighty in a small
town in northern Alabama. Her father, Arthur Keller, was a captain in the army of the South
during the American Civil War. Her mother was his second wife. She was much younger than her
husband. Helen was their first child.
Until she was a year-and-one-half old, Helen Keller was just like any other child. She was very
active. She began walking and talking early. Then, nineteen months after she was born, Helen
became very sick. It was a strange sickness that made her completely blind and deaf. The doctor
could not do anything for her. Her bright, happy world now was filled with silence and darkness.
VOICE TWO:
From that time until she was almost seven years old, Helen could communicate only by making signs with her hands. But she
learned how to be active in her silent, dark environment. The young child had strong desires. She knew what she wanted to do. No
one could stop her from doing it. More and more, she wanted to communicate with others. Making simple signs with her hands
was not enough. Something was ready to explode inside of her because she could not make people understand her. She screamed
and struggled when her mother tried to control her.
When Helen was six, her father learned about a doctor in Baltimore, Maryland. The doctor had successfully treated people who
were blind. Helen's parents took her on the train to Baltimore. But the doctor said he could do nothing to help Helen. He suggested
the Kellers get a teacher for the blind who could teach Helen to communicate. A teacher arrived from the Perkins Institution for
the Blind in Boston. Her name was Anne Sullivan.
She herself had once been almost completely blind. But she had regained her sight. At Perkins, she had learned the newest
methods of teaching the blind.
VOICE TWO:
Anne Sullivan began by teaching Helen that everything had a name. The secret to the names was the letters that formed them. The
job was long and difficult. Helen had to learn how to use her hands and fingers to speak for her. But she was not yet ready to
learn. First, she had to be taught how to obey, and how to control her anger. Miss Sullivan was quick to understand this. She wrote
to friends in Boston about her experiences teaching Helen.
VOICE THREE:
“The first night I arrived I gave Helen a doll. As she felt the doll with one hand I slowly formed the letters, d-o-l-l with my fingers
in her other hand. Helen looked in wonder and surprise as she felt my hand. Then she formed the letters in my hand just as I had
done in hers. She was quick to learn, but she was also quick in anger. For seven years, no one had taught her self-control. Instead
of continuing to learn, she picked up the doll and threw it on the floor. She was this way in almost everything she did.
Even at the table, while eating, she did exactly as she pleased. She even put her hands in our plates and ate our food. The second
morning, I would not let her put her hand on my plate. The family became troubled and left the room. I closed the door and
continued to eat. Helen was on the floor, kicking and screaming and trying to pull the chair out from under me.
This continued for half an hour or so. Then she got up from the floor and came to find out what I was doing. Suddenly she hit me.
Every time she did this I hit her hand. After a few minutes of this, she went to her place at the table and began to eat with her
fingers. I gave her a spoon to eat with. She threw it on the floor. I forced her to get out of her chair to pick the spoon up. At last,
after two hours, she sat down and ate like other people. I had to teach her to obey.
Helen Keller
٢
But it was painful to her family to see their deaf and blind child punished. So I asked them to let me move with Helen into a small
one-room house nearby. The first day Helen was away from her family she kicked and screamed most of the time. That night I
could not make her get into bed. We struggled, but I held her down on the bed. Luckily, I was stronger than she. The next morning
I expected more of the same, but to my surprise she was calm, even peaceful.
Two weeks later, she had become a gentle child. She was ready to learn. My job now was pleasant. Helen learned quickly. Now I
could lead and shape her intelligence. We spent all day together. I formed words in her hand, the names of everything we touched.
But she had no idea what the words meant.
As time passed, she learned how to sew clothes and make things. Every day we visited the farm animals and searched for eggs in
the chicken houses. All the time, I was busy forming letters and words in her hand with my fingers. Then one day, about a month
after I arrived, we were walking outside. Something important happened.
We heard someone pumping water. I put Helen's hand under the cool water and formed the word w-a-t-e-r in her other hand. W-at-
e-r, w-a-t-e-r. I formed the word again and again in her hand. Helen looked straight up at the sky as if a lost memory or thought
of some kind was coming back to her.
Suddenly, the whole mystery of language seemed clear to her. I could see that the word w-a-t-e-r meant something wonderful and
cool that flowed over her hand. The word became alive for her. It awakened her spirit, gave it light and hope. She ran toward the
house. I ran after her. One by one she touched things and asked their name. I told her. She went on asking for names and more
names.”
VOICE ONE:
From that time on Helen left the house each day, searching for things to learn. Each new name brought new thoughts. Everything
she touched seemed alive. One day, Helen remembered a doll she had broken. She searched everywhere for the pieces. She tried
to put the pieces together but could not. She understood what she had done and was not happy. Miss Sullivan taught Helen many
things -- to read and write, and even to use a typewriter. But most important, she taught Helen how to think.
VOICE TWO:
For the next three years, Helen learned more and more new words. All day Miss Sullivan kept touching Helen's hand, spelling
words that gave Helen a language. In time, Helen showed she could learn foreign languages. She learned Latin, Greek, French and
German. Helen was able to learn many things, not just languages.
She was never willing to leave a problem unfinished, even difficult problems in mathematics. One time, Miss Sullivan suggested
leaving a problem to solve until the next day. But Helen wanted to keep trying. She said, "I think it will make my mind stronger to
do it now.”
VOICE ONE:
Helen traveled a lot with her family or alone with Miss Sullivan. In eighteen eighty-eight, Helen, her mother and Miss Sullivan
went to Boston, Massachusetts. They visited the Perkins Institution where Miss Sullivan had learned to teach. They stayed for
most of the summer at the home of family friends near the Atlantic Ocean. In Helen's first experience with the ocean, she was
caught by a wave and pulled under the water. Miss Sullivan rescued her. When Helen recovered, she demanded, "Who put salt in
the water? "
VOICE TWO:
Three years after Helen started to communicate with her hands, she began to learn to speak as other people did. She never forgot
these days. Later in life, she wrote: "No deaf child can ever forget the excitement of his first word. Only one who is deaf can
understand the loving way I talked to my dolls, to the stones, to birds and animals. Only the deaf can understand how I felt when
my dog obeyed my spoken command. " Those first days when Helen Keller developed the ability to talk were wonderful. But they
proved to be just the beginning of her many successes.
VOICE ONE:
You have been listening to the first part of the story of Helen Keller. It was written by Katherine Clarke. Your narrators were
Sarah Long, Ray Freeman and Shirley Griffith. Listen again next week at this time to People in America, a program in Special
English on the Voice of America.
----------------------------------------------------------------------------------------------------------------------------------------------------------SCIENCE IN THE NEWS - Time -- One of the Great Mysteries of Our Universe
Broadcast date: 12-29-2009 / Written by Marilyn ChristianoFrom http://www.unsv.com/voanews/specialenglish/
HOST:
This is SCIENCE IN THE NEWS, in VOA Special English. I'm Steve
Ember. This week our program is about a mystery as old as time.
Bob Doughty and Sarah Long tell about the mystery of time.
(THEME)
VOICE ONE:
If you can read a clock, you can know the time of day. But no one
knows what time itself is. We cannot see it. We cannot touch it. We
cannot hear it. We know it only by the way we mark its passing.
For all our success in measuring the smallest parts of time, time
remains one of the great mysteries of the universe.
VOICE TWO:
One way to think about time is to imagine a world without time. There could be no movement,
because time and movement cannot be separated.
A world without time could exist only as long as there were no changes. For time and change are
linked. We know that time has passed when something changes.
VOICE ONE:
In the real world -- the world with time -- changes never stop. Some changes happen only once in a
while, like an eclipse of the moon. Others happen repeatedly, like the rising and setting of the sun.
Humans always have noted natural events that repeat themselves. When people began to count
such events, they began to measure time.
In early human history, the only changes that seemed to repeat themselves evenly were the
movements of objects in the sky. The most easily seen result of these movements was the
difference between light and darkness.
The sun rises in the eastern sky, producing light. It moves across the sky and sinks in the west,
causing darkness. The appearance and disappearance of the sun was even and unfailing. The
periods of light and darkness it created were the first accepted periods of time. We have named
each period of light and darkness -- one day.
VOICE TWO:
People saw the sun rise higher in the sky during the summer than in winter. They counted the days
that passed from the sun's highest position until it returned to that position. They counted three
hundred sixty-five days. We now know that is the time Earth takes to move once around the sun.
We call this period of time a year.
VOICE ONE:
Early humans also noted changes in the moon. As it moved across the night sky, they must have
wondered. Why did it look different every night? Why did it disappear? Where did it go?
Even before they learned the answers to these questions, they developed a way to use the changing
faces of the moon to tell time.
The moon was "full" when its face was bright and round. The early humans counted the number of
times the sun appeared between full moons. They learned that this number always remained the
same -- about twenty-nine suns. Twenty-nine suns equaled one moon. We now know this period of
time as one month.
(MUSIC)
VOICE TWO:
Early humans hunted animals and gathered wild plants. They moved in groups or tribes from place
to place in search of food. Then, people learned to plant seeds and grow crops. They learned to use
animals to help them work, and for food.
They found they no longer needed to move from one place to another to survive.
As hunters, people did not need a way to measure time. As farmers, however, they had to plant
crops in time to harvest them before winter. They had to know when the seasons would change. So,
they developed calendars.
No one knows when the first calendar was developed. But it seems possible that it was based on
moons, or lunar months.
When people started farming, the wise men of the tribes became very important. They studied the
sky. They gathered enough information so they could know when the seasons would change. They
announced when it was time to plant crops.
(MUSIC)
VOICE ONE:
The divisions of time we use today were developed in ancient Babylonia four thousand years ago.
Babylonian astronomers believed the sun moved around the Earth every three hundred sixty-five
days. They divided the trip into twelve equal parts, or months. Each month was thirty days. Then,
they divided each day into twenty-four equal parts, or hours. They divided each hour into sixty
minutes, and each minute into sixty seconds.
VOICE TWO:
Humans have used many devices to measure time. The sundial was
one of the earliest and simplest.
A sundial measures the movement of the sun across the sky each
day. It has a stick or other object that rises above a flat surface.
The stick, blocking sunlight, creates a shadow. As the sun moves, so
does the shadow of the stick across the flat surface. Marks on the
surface show the passing of hours, and perhaps, minutes.
The sundial works well only when the sun is shining. So, other ways
were invented to measure the passing of time.
VOICE ONE:
One device is the hourglass. It uses a thin stream of falling sand to measure time. The hourglass is
shaped like the number eight --- wide at the top and bottom, but very thin in the middle. In a true
"hour" glass, it takes exactly one hour for all the sand to drop from the top to the bottom through aSundial
very small opening in the middle. When the hourglass is turned with the upside down, it begins to
mark the passing of another hour.
By the eighteenth century, people had developed mechanical clocks and watches. And today, many
of our clocks and watches are electronic.
VOICE TWO:
So, we have devices to mark the passing of time. But what time is it
now? Clocks in different parts of the world do not show the same
time at the same time. This is because time on Earth is set by the
sun's position in the sky above.
We all have a twelve o'clock noon each day. Noon is the time the sun
is highest in the sky. But when it is twelve o'clock noon where I am,
it may be ten o'clock at night where you are.
VOICE ONE:
As international communications and travel increased, it became
clear that it would be necessary to establish a common time for all
parts of the world.
In eighteen eighty-four, an international conference divided the world into twenty-four time areas, or
zones. Each zone represents one hour. The astronomical observatory in Greenwich, England, was
chosen as the starting point for the time zones. Twelve zones are west of Greenwich. Twelve are
east.
The time at Greenwich -- as measured by the sun -- is called Universal Time. For many years it was
called Greenwich Mean Time.
VOICE TWO:
Some scientists say time is governed by the movement of matter in our universe. They say time
flows forward because the universe is expanding. Some say it will stop expanding some day and will
begin to move in the opposite direction, to grow smaller. Some believe time will also begin to flow in
the opposite direction -- from the future to the past. Can time move backward?
Most people have no trouble agreeing that time moves forward. We see people born and then grow
old. We remember the past, but we do not know the future. We know a film is moving forward if it
shows a glass falling off a table and breaking into many pieces. If the film were moving backward,
the pieces would re-join to form a glass and jump back up onto the table. No one has ever seen this
happen. Except in a film.
VOICE ONE:
Some scientists believe there is one reason why time only moves forward. It is a well-known
scientific law -- the second law of thermodynamics. That law says disorder increases with time. In
fact, there are more conditions of disorder than of order.
For example, there are many ways a glass can break into pieces. That is disorder. But there is only
one way the broken pieces can be organized to make a glass. That is order. If time moved
backward, the broken pieces could come together in a great many ways. Only one of these many
ways, however, would re-form the glass. It is almost impossible to believe this would happen.
VOICE TWO:
Not all scientists believe time is governed by the second law of thermodynamics. They do not agree
that time must always move forward. The debate will continue about the nature of time. And timeClock
will remain a mystery.
(THEME)
HOST:
Our program was written by Marilyn Christiano and read by Sarah Long and Bob Doughty. I'm Steve
Ember. Listen again next week for Science in the News, in VOA Special English.
---------------------------------------------------------------------------------------------
(MUSIC)
VOICE
|
|
|
|
This is SCIENCE IN THE NEWS, in VOA Special English. I'm Barbara Klein.
VOICE TWO:
And I'm Bob Doughty. On our program today, we tell about aspirin. It is one of the most widely used medicines in the world. We also tell about some recent studies involving aspirin.
(MUSIC)
VOICE ONE:
More than two thousand years ago, the Greek doctor Hippocrates advised his patients about a way to ease pain. He told them to bite, or chew, on the bark of the willow tree. The outer covering of the tree contains a chemical called salicylic acid.
By the seventeen hundreds, people used willow bark to reduce high body temperatures. In eighteen ninety-seven, a research scientist at the Bayer Company in Germany created acetyl salicylic acid. The company called the product aspirin, from the spirea plant, which also contains the chemical.
VOICE TWO:
Aspirin has been sold for more than a century as a treatment for high body temperatures, headaches and muscle pain. In nineteen eighty-two, a British scientist shared the Nobel Prize in Medicine in part for discovering how aspirin works. Sir John Vane found that aspirin blocks the body from making natural substances called prostaglandins. Prostaglandins have several effects on the body. Some cause pain and the expansion, or swelling, of damaged tissue. Others protect the lining of the stomach and small intestine.
Prostaglandins also make the heart, kidneys, and blood vessels work well. But there is a problem. Aspirin works against all prostaglandins, good and bad.
VOICE ONE:
Scientists learned how aspirin interferes with an enzyme. One form of this enzyme makes the prostaglandin that causes pain and swelling. Another form of the enzyme creates the protective effect. So aspirin can reduce pain and swelling in damaged tissues. But it can also harm the inside of the stomach and small intestine.
Today, aspirin competes with a lot of other pain medicines. Many people like to take acetaminophen instead. This is the active substance in products like Tylenol. Still, experts say aspirin does some things that the others cannot.
(MUSIC)
VOICE TWO:
Many people take aspirin to reduce the risk of a heart attack. Scientists say aspirin prevents blood cells called platelets from sticking together to form clots. Clots can block the flow of blood to the heart or the brain. This can cause heart attacks or strokes.
The use of aspirin to reduce the risk of heart disease has grown in recent years. One doctor first noted this effect in the nineteen-fifties.
VOICE ONE:
The doctor was Lawrence Craven. He observed unusual bleeding among children who chewed on aspirin gum to ease pain after a throat operation. Doctor Craven believed they were bleeding because aspirin prevented the blood from thickening. He decided that aspirin might help prevent heart attacks caused by blood clots.
So Doctor Craven examined medical records of about eight thousand people. He found no heart attacks or strokes among those who often used aspirin. Doctor Craven invited other scientists to test his ideas. But it was many years before large studies took place.
VOICE TWO:
Charles Hennekens of the Harvard Medical School led one of the studies. In nineteen eighty-three, he began to study more than twenty-two thousand healthy male doctors over forty years of age. Half the doctors in the study took an aspirin every other day. The other half took what they thought was aspirin, but was just a harmless substance, or placebo.
Five years later, Doctor Hennekens reported that the men who took aspirin reduced their chances of a heart attack. However, the men who took aspirin also had a higher risk of bleeding in the brain.
VOICE ONE:
In recent years, a group of American medical experts examined studies on aspirin for the Department of Health and Human Services. The experts said people who have an increased risk of a heart attack should take a small amount of aspirin every day.
People who are most likely to suffer a heart attack include men over the age of forty and women over the age of fifty. People who weigh too much or smoke cigarettes also are at greater risk. So are people with diabetes, heart disease, high blood pressure or high levels of cholesterol in the blood.
VOICE TWO:
A major study in two thousand five confirmed that aspirin can also help women. Julie Buring of Brigham and Women’s Hospital in Boston, Massachusetts, led the study. She said that among apparently health people, aspirin reduces the risk of heart attack in men. But for women it appears to reduce the risk of stroke.
The New England Journal of Medicine reported the findings. The study lasted ten years. It involved forty thousand women age forty-five and older. Those who received aspirin took one hundred milligrams every other day. The others took a placebo.
The study found that the women who took aspirin were seventeen percent less likely to have a stroke than the other women. The aspirin group also had a twenty-four percent lower risk for the most common form of stroke. This is caused by a clot in a blood vessel that carries blood to the brain.
The study found that aspirin had an even greater effect in women sixty-five years of age and older. Those who took aspirin were thirty percent less likely to have a stroke caused by a blood clot. They were also less likely to suffer a heart attack than those given a placebo.
(MUSIC)
VOICE ONE:
Aspirin may help someone who is having a heart attack caused by a blockage in the flow of blood to the heart. Aspirin thins the blood. This can permit blood to flow past the blockage in the artery.
But heart experts say people should seek emergency help immediately. They say an aspirin is no substitute for treatment. Some people should not take aspirin. These include people who take other blood thinners or have bleeding disorders.
VOICE TWO:
Like other medicines, aspirin can cause problems, especially if taken in large amounts. Acid in the drug may damage the tissue of the stomach or intestines. Aspirin can also interfere with the healing of cells. Some people develop severe bleeding.
Yet other studies have found that aspirin may help prevent cancers of the stomach, intestines and colon. Studies in the past twenty years showed that people who take aspirin have unusually low rates of such cancers. For example, a study published in two thousand five showed that long-term use of aspirin helps reduce the risk of colon cancer. However, the amount of aspirin required for this protective effect also could cause serious bleeding in the stomach or intestines.
VOICE ONE:
Another recent report about aspirin involves the most common form of breast cancer. In two thousand four, researchers announced findings from a study of almost three thousand women in New York City. The Journal of the American Medical Association published the findings.
The study compared women who took aspirin several times a week to women who did not. Scientists from Columbia University said the aspirin users had a twenty-five percent lower rate of breast cancer.
One doctor involved in the study said aspirin appeared to reduce the production of the female hormone estrogen. Estrogen is linked to up to seventy percent of all cases of breast cancer. But the scientists said they were not ready to advise women to take aspirin in hopes of protection against breast cancer.
VOICE TWO:
Doctors often do advise aspirin for patients at risk of diseases that result from blood clots, such as a heart attack. However, in two thousand four, a Harvard Medical School publication said that some people get little or no protection from aspirin.
In any case, medical experts say no one should take aspirin for disease prevention without first asking a doctor. Aspirin is sold in different strengths. It can interfere with other drugs. It also is not safe for everyone. Most pregnant women are told to avoid aspirin. Children who take aspirin can suffer from a disease called Reye’s syndrome. Yet even with its problems, aspirin, remains one of the oldest, least costly and most widely used drugs in the world.
(MUSIC)
VOICE ONE:
This SCIENCE IN THE NEWS program was written by George Grow and produced by Cynthia Kirk. I’m Barbara Klein.
VOICE TWO:
And I’m Bob Doughty. Join us again next week for more news about science in VOA Special English.
-------------------------------------------------------------------------------------------------------------
ارائه ی مطالبی مفید برای شما دوست گرامی