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Dangers Await Babies with Altitude
Women who live in the world’s highest communities tend to give birth to under-weight babies, a new study suggests. These babies may grow into adults with a high risk of heart disease and strokes.1
Research has hinted that newborns in mountain communities are lighter than average. But it wasn’t clear whether this is due to reduced oxygen levels at high altitude or because their mothers are under-nourished — many people who live at high altitudes are relatively poor compared with those living lower down.
To find out more, Dino Giussani and his team at CambridgeUniversitystudied the records of 400 births inBoliviaduring 1997 and 1998. The babies were born in both rich and poor areas of two cities:La PazandSanta Cruz.La Pazis the highest city in the world, at 3.65 kilometers above sea level, whileSanta Cruzis much lower, at 0.44 kilometers.
Sure enough, Giussani found that the average birth weight of babies inLa Pazwas significantly lower than inSanta Cruz. This was true in both high and low-income families. Even babies born to poor families inSanta Cruzwere heavier on average than babies born to wealthy families in loftyLa Paz. “We were very surprised by this result,” says Giussani.
The results suggest that babies born at high altitude are deprived of2 oxygen before birth. “This may trigger the release or suppression of hormones that regulate growth of the unborn child.3 ‘‘ says Giussani.
His team also found that high-altitude babies tended to have relatively larger heads compared with their bodies4. This is probably because a fetus starved of oxygen will send oxygenated blood to the brain in preference to the rest of the body5.
Giussani wants to find out if such babies have a higher risk of disease in later life. People born inLa Pazmight be prone to heart trouble in adulthood, for example. Low birth weight is a risk factor for coronary heart disease. And newborns with a high ratio of head size to body weight are often predisposed to high blood pressure and strokes in later life.
词汇：
altitude /"æltɪtju:d/ n.纬度，(海拔)高度
birthweight /bə:θ weit/ n. 出生体重
underweight /ˌʌndəˈweɪt/adj.体重不足的
hormone /"hɔ:məʊn/ n. 荷尔蒙
stroke /strəʊk/ n.中风
coronary /"kɒrənrɪ/ adj. 冠状的
hint /hɪnt/ / vt.暗示
fetus /"fi:təs/ n. 胚胎
under-nourished adj.营养不足的
注释：
According to the passage, one of the reasons why newborns in mountain communities are underweight is that their mothers are underweight
A:Right B:Wrong C:Not mentioned
Millions of stars are travelling about in space. A few form groups which journey together, but most of them travel alone. And they travel through a universe so large that one star seldom comes near to another.
We believe, however, that some two thousand million years ago, another star wandering through space, happened to come near our sun. Just as the sun and the moon raise tides on the earth, so this star must have raised tides on the surface of the sun. But they were very different from the small tides that are raised in our oceans; a large tidal wave must have travelled over the surface of the sun, at last forming a mountain so high that we cannot imagine it. As the cause of the disturbance (动荡) came nearer, so the mountain rose higher and higher. And before the star began to move away again, its tidal pull had become so powerful that this mountain was torn to pieces and threw off small parts of itself into space. These small pieces have been going round the sun ever since. They are the planets (行星).
A:our earth exists before the sun B:how space formed C:no one knows where the earth comes from D:our earth used to be part of a high mountain on the sun
When the temperature of a liquid is raised enough, the liquid boils. This means that bubbles of vapor, containing millions of molecules, form below the surface. In order for such bubbles to be produced, the pressure of the vapor inside them must be equal to the pressure of the air upon the surface of the liquid. If the air pressure is greater, the bubble will collapse. The boiling point of a liquid, then, is the temperature at which the vapor pressure of the liquid is equal to the atmospheric pressure upon the liquid at the surface.
The pressure of the atmosphere at sea level is about one kilogram per square centimeter. We call this pressure one atmosphere. The boiling point of a liquid, therefore, is the temperature at which its vapor pressure equals one atmosphere. The boiling point of water is 100 Celsius; of ethyl alcohol 78.5 Celsius; of mercury, 356.9 Celsius.
If the pressure on the surface of the water is reduced, the boiling point will be lower. Now the higher up we go from sea level, the lower the atmospheric pressure becomes, since there is less air to press upon us. Hence, while water boils at sea level at a temperature of 100 Celsius, its boiling point on a mountain three kilometers high is only 90 Celsius. Since the temperature of water does not rise as a result of boiling, it would take you longer to cook potatoes or carrots in boiling water on the mountain than it would at sea level.
A:The boiling point of water on a mountain three kilometers high is only 90 Celsius. B:It would take you longer to cook potatoes in boiling water on the mountain than it would at sea level. C:When the temperature of a liquid is raised enough, the liquid boils. D:The boiling point of water on a mountain six kilometers high is 95 Celsius.
Millions of stars are traveling about in space. A few form groups which journey together, but most of them travel alone. And they travel through a universe so large that one star seldom comes near to another.
We believe, however, that some two thousand million years ago, another star wandering through space, happened to come near our sun. Just as the sun and the moon raise tides on the earth, so this star must have raised tides on the surface of the sun. But they were very different from the small tides that are raised in our oceans; a large tidal wave’ must have travelled over the surface of the sun, at last forming a mountain so high that we cannot imagine it. As the cause of the disturbance (动荡) came nearer, so the mountain rose higher and higher. And before the star began to move away again, its tidal pull had become so powerful that this mountain was torn to pieces and threw off small parts of itself into space. These small pieces have been going round the sun ever since. They are the planets (行星).
The article suggests that______.
A:our earth exists before the sun B:how space formed C:no one knows where the earth comes from D:our earth used to be part of a high mountain on the sun
Passage One
By midday, the small party of boys, led by their schoolmaster, had reached a height of 2,500 feet. At this point the party had to stop climbing because one of the boys became seriously ill. The only thing the master could do was to return to the mountain hut where they ha& spent the night. From there, he telephoned the police. As no rescue party could reach the boy quickly enough, the Royal Air Force Rescue Center sent a helicopter (直升飞机) with a policeman and a doctor on board. The helicopter soon arrived on the scene, but the sides of the mountain were so steep that it could not land. A helicopter usually lands on four wheels, but it can land on two. However, the slope was too steep even for that. The pilot, there fore, kept the helicopter in the air with only one wheel touching the mountain side while the party carried the boy on board.
A:the mountain was too high B:the mountain-sides were too steep C:the runway was too narrow D:the weather was very bad
Millions of stars are traveling about in space. A few form groups which journey together, but most of them travel alone. And they travel through a universe so large that one star seldom comes near to another.
We believe, however, that some two thousand million years ago, another star wandering through space, happened to come near our sun. Just as the sun and the moon raise tides on the earth, so this star must have raised tides on the surface of the sun. But they were very different from the small tides that are raised in our oceans; a large tidal wave’ must have travelled over the surface of the sun, at last forming a mountain so high that we cannot imagine it. As the cause of the disturbance (动荡) came nearer, so the mountain rose higher and higher. And before the star began to move away again, its tidal pull had become so powerful that this mountain was torn to pieces and threw off small parts of itself into space. These small pieces have been going round the sun ever since. They are the planets (行星).
The article suggests that______.
A:our earth exists before the sun B:how space formed C:no one knows where the earth comes from D:our earth used to be part of a high mountain on the sun
Passage Four
| Millions of stars are traveling about
in space. A few form groups which journey together, but most of them travel
alone. And they travel through a universe so large that one star seldom
comes near to another. We believe, however, that some two thousand million years ago, another star wandering through space, happened to come near our sun. Just as the sun and the moon raise tides on the earth, so this star must have raised tides on the surface of the sun. But they were very different from the small tides that are raised in our oceans; a large tidal wave’ must have travelled over the surface of the sun, at last forming a mountain so high that we cannot imagine it. As the cause of the disturbance (动荡) came nearer, so the mountain rose higher and higher. And before the star began to move away again, its tidal pull had become so powerful that this mountain was torn to pieces and threw off small parts of itself into space. These small pieces have been going round the sun ever since. They are the planets (行星). |
A:our earth exists before the sun B:how space formed C:no one knows where the earth comes from D:our earth used to be part of a high mountain on the sun
