VOA慢速英语2013 曾经生存在洛杉矶的大型猫科动物

 

AS IT IS 2013-11-07 Big Cats Once Lived in L.A. 曾经生存在洛杉矶的大型猫科动物

Hello again, and welcome.  I’m Jim Tedder¹ in Washington.  Today we take you to a very, very busy place in one of America’s largest cities.  There we will find scientists down on their hands and knees looking for unusual creatures from the distant past. 

Then Steve Ember comes by to talk about a subject that nearly everyone loves …photography.  Today we will hear about an effort to save some early pictures from being destroyed by time. 

So relax and listen carefully, as you learn and improve your English with As It Is, on VOA.

Creatures such as fierce-looking saber toothed cats once lived in what is now the second largest city in the United States.  The animals’ ancient remains² are still being found at the La Brea Tar³ Pits in Los Angeles, California, a century after scientists first began their digging.  Today, scientists from all over the world are examining some of these fossils for clues about climate change.

Tall buildings and traffic in the heart of Los Angeles surround pools of thick, gooey tar.  Scientists come there to unearth⁴ animal remains under the bubbling material.

Shelley Cox praises the chance to work with these fossils.  To her, they are treasure.

“I get excited about a mouse toe!”

Shelley Cox cleans the fossils in a laboratory called the Fish Bowl.  It is in the George C. Page Museum in Los Angeles, which houses fossils of animals and plants trapped and preserved by the tar at the La Brea Tar Pits.  Some of the remains are more than 40 thousand years old.

“We have such a variety of fossils that there is almost something for everyone preserved right here.”

These ancient remains are the reason why paleontologists from around the world come to study the discoveries.  Chief Curator John Harris says even saber tooth cats and mammoths could save themselves from the thick, sticky material that caught them in a death-hold.

“They got stuck in asphalt, stuck likes flies on fly paper.  If they were lucky, they succumbed⁵ to hunger and thirst after about a week.  If they were unlucky, they were torn apart by wandering predators⁶ and scavengers.”

In the past, paleontologists centered their work on large mammals.  But the remains of smaller creatures such as snails⁷ or insects are now getting more attention.  These microfossils give scientists a better picture of the ancient ecosystem⁸.  They also tell the scientists how climate change affects organisms.

The large mammals are extinct, gone forever.  The “young” creatures that developed from them do not necessarily live in the same area as their ancestors.

“Well, if we have some idea of how life changes when we have changes in climate, then we can take steps when we are actually experiencing those same climatic changes ourselves.”

Scientists say the plants and animals preserved in tar can tell them how global warming in the past affected⁹ ancient organisms.  The experts say the creatures and plants can help show which species may face the most danger as the modern Earth gets warmer.

Smile for the Camera

If you ever get have the opportunity to visit Los Angeles, and the Le Brea Tar Pits, you will probably see many tourists taking photographs of the scientists at work.  Photography today is so easy, now that we can make pictures digitally.  But in the early days, using a camera was not something that just anyone knew how to do.  Steve Ember joins us now with information about picture taking over 150 years ago. 

The invention of the daguerreotype¹⁰ in the 19th century led to modern photography. With daguerreotypes, people could sit for just a few minutes while their image was captured in what is now known as a photograph. Before that, people had to sit long hours for an artist to paint a picture.

America’s Smithsonian Institution is now working with the Argonne National Laboratory near Chicago to study daguerreotypes. Scientists say these early photos are in danger of being lost forever.

The young woman in one daguerreotype they’re working on was most likely a teenager or in her early 20s when the picture was made. Her image was captured on a copper¹¹ plate with finely polished, shining silver in the middle of the 19th century.

“It was the first time you could go into a studio and have your photograph taken, and you could put it up somewhere and show it off.”

That’s Daniel Weinberg. He works at the Abraham Lincoln Book Shop in Chicago. He has studied many daguerreotypes. He says they are popular with collectors and historians alike.

“They’re luminous¹², and they’re almost three dimensional, and you almost want to step into one.”

He also says daguerreotypes were one of a kind, not meant to be reproduced like current photographs. Louis Daguerre of France was the inventor of this first photographic process. The technology was very popular in the United States in the middle of the 1800s.

“It spread like wildfire in the United States. There were hundreds of thousands of daguerreotypes made over a 20-year span.”

Ed Vicenzi is a researcher with the Smithsonian Institution. Many of the most important daguerreotypes are now stored at the Smithsonian and in the collections of the United States Library of Congress.

The images include the mysterious young woman we spoke¹³ of earlier. Ed Vicenzi calls her “Clara,” although her real name is unknown.

“We don’t know her name, her family, the state she’s from.”

What he does know is that the image is in danger of being lost in the future unless something is done to stop the breakdown¹⁴ of its chemical makeup¹⁵.

“Daguerreotypes are actually made up of a bunch of nanoparticles on the surface that scatter¹⁶ the light and this is in some ways similar to the way high technology devices are made today, so we’re also interested in what did 19th century photographers know about nanotechnology unwittingly.”

“They were made at a time when the concept of nanotechnology, even the word at that time didn’t exist.”

Physicist¹⁷ Volker Rose is working with Ed Vicenzi at the Argonne National Laboratory. They are using the laboratory’s Advanced Photon Source to learn more about the daguerreotype.

“The technology that’s available at the Advanced Photon Source will allow me to study the very earliest stages of degradation¹⁸ of daguerreotype plates. They corrode¹⁹ over time, not quickly necessarily, but we need to learn the chemical mechanisms²⁰ in order to understand how we can preserve these objects for the future.”

Ed Vicenzi hopes his efforts at Argonne will provide the answers historians and collectors need to save these images of the past. He says this will make it possible for future generations to study, understand and appreciate what life was like in the 19th century.

Many thanks to my friend, colleague, and …by the way…excellent photographer Steve Ember for that information.  I’m Jim Tedder in Washington.  More Learning English programs are just ahead.  And there is world news at the beginning of the hour on VOA. 

1 tedder   

n.（干草）翻晒者，翻晒机

参考例句：

• Jim Tedder has more. 吉姆？特德将给我们做更多的介绍。 来自互联网
• Jim Tedder tells us more. 吉姆？泰德给我们带来更详细的报道。 来自互联网

2 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

3 tar   

n.柏油，焦油；vt.涂或浇柏油/焦油于

参考例句：

• The roof was covered with tar.屋顶涂抹了一层沥青。
• We use tar to make roads.我们用沥青铺路。

4 unearth   

v.发掘，掘出，从洞中赶出

参考例句：

• Most of the unearth relics remain intact.大多数出土文物仍保持完整无损。
• More human remains have been unearthed in the north.北部又挖掘出了更多的人体遗骸。

5 succumbed   

不再抵抗（诱惑、疾病、攻击等）( succumb的过去式和过去分词 )； 屈从； 被压垮； 死

参考例句：

• The town succumbed after a short siege. 该城被围困不久即告失守。
• After an artillery bombardment lasting several days the town finally succumbed. 在持续炮轰数日后，该城终于屈服了。

6 predators   

n.食肉动物( predator的名词复数 )；奴役他人者（尤指在财务或性关系方面）

参考例句：

• birds and their earthbound predators 鸟和地面上捕食它们的动物
• The eyes of predators are highly sensitive to the slightest movement. 捕食性动物的眼睛能感觉到最细小的动静。 来自《简明英汉词典》

7 snails   

n.蜗牛；迟钝的人；蜗牛( snail的名词复数 )

参考例句：

• I think I'll try the snails for lunch—I'm feeling adventurous today. 我想我午餐要尝一下蜗牛——我今天很想冒险。 来自《简明英汉词典》
• Most snails have shells on their backs. 大多数蜗牛背上有壳。 来自《简明英汉词典》

8 ecosystem   

n.生态系统

参考例句：

• This destroyed the ecosystem of the island.这样破坏了岛上的生态系统。
• We all have an interest in maintaining the integrity of the ecosystem.维持生态系统的完整是我们共同的利益。

9 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

10 daguerreotype   

n.银板照相

参考例句：

• The inventor of the daguerreotype is a French artist.银版照相的发明者是位法国艺术家。
• The image was taken by louis daguerre who invented the daguerreotype-one of the earliest methods of photography.这张照片是由路易斯达盖尔拍摄，他发明了银版照相法-摄影的最早方法之一。

11 copper   

n.铜；铜币；铜器；adj.铜(制)的；(紫)铜色的

参考例句：

• The students are asked to prove the purity of copper.要求学生们检验铜的纯度。
• Copper is a good medium for the conduction of heat and electricity.铜是热和电的良导体。

12 luminous   

adj.发光的，发亮的；光明的；明白易懂的；有启发的

参考例句：

• There are luminous knobs on all the doors in my house.我家所有门上都安有夜光把手。
• Most clocks and watches in this shop are in luminous paint.这家商店出售的大多数钟表都涂了发光漆。

13 spoke   

n.（车轮的）辐条；轮辐；破坏某人的计划；阻挠某人的行动 v.讲，谈（speak的过去式）；说；演说；从某种观点来说

参考例句：

• They sourced the spoke nuts from our company.他们的轮辐螺帽是从我们公司获得的。
• The spokes of a wheel are the bars that connect the outer ring to the centre.辐条是轮子上连接外圈与中心的条棒。

14 breakdown   

n.垮，衰竭；损坏，故障，倒塌

参考例句：

• She suffered a nervous breakdown.她患神经衰弱。
• The plane had a breakdown in the air,but it was fortunately removed by the ace pilot.飞机在空中发生了故障，但幸运的是被王牌驾驶员排除了。

15 makeup   

n.组织；性格；化装品

参考例句：

• Those who failed the exam take a makeup exam.这次考试不及格的人必须参加补考。
• Do you think her beauty could makeup for her stupidity?你认为她的美丽能弥补她的愚蠢吗？

16 scatter   

vt.撒，驱散，散开；散布/播；vi.分散，消散

参考例句：

• You pile everything up and scatter things around.你把东西乱堆乱放。
• Small villages scatter at the foot of the mountain.村庄零零落落地散布在山脚下。

17 physicist   

n.物理学家，研究物理学的人

参考例句：

• He is a physicist of the first rank.他是一流的物理学家。
• The successful physicist never puts on airs.这位卓有成就的物理学家从不摆架子。

18 degradation   

n.降级；低落；退化；陵削；降解；衰变

参考例句：

• There are serious problems of land degradation in some arid zones.在一些干旱地带存在严重的土地退化问题。
• Gambling is always coupled with degradation.赌博总是与堕落相联系。

19 corrode   

v.使腐蚀，侵蚀，破害；v.腐蚀，被侵蚀

参考例句：

• The tools will corrode with rust if never used.这些工具如长期不用会长铁锈而损坏。
• It will pollute people's aesthetic taste and corrode social spirit.它污染人们的审美趣味，腐蚀社会精神。

20 mechanisms   

n.机械( mechanism的名词复数 )；机械装置；[生物学] 机制；机械作用

参考例句：

• The research will provide direct insight into molecular mechanisms. 这项研究将使人能够直接地了解分子的机理。 来自《简明英汉词典》
• He explained how the two mechanisms worked. 他解释这两台机械装置是如何工作的。 来自《简明英汉词典》