Lecture3
Lecture 3语用学课件--北外课件
Reasoning:
Example 6:
A: I do think Mrs Jenkins is an old windbag, don’t you? B: Huh, lovely weather for March, isn’t it?
Implicature:
Mrs. Jenkins is coming, watch out! B’s answer seems to be irrelevant. But B might want to provide some relevant information, relevant in some other sense. So, the implicature.
Some other well-known Oxford philosophers:
Grice’s theory
The Co-operative Principle (合作原理):
Make your contribution such as is required, at the stage at which it occurs, by the accepted purpose or direction of the talk exchange in which you are engaged
The letter explicitly said something about Mr. Jones’s punctuality and his handwriting. But it also implicitly said that the student is not good.
The professor did not say that the student is intelligent, hardworking etc., which are normally required for a recommendation letter. What he said about the student seems to be irrelevant. This cannot be a good reference letter.
Lecture3心理物理方法中文版(精)
非线性差异阈值
• 差异阈值不是恒定的 (随强度而变化) 非线性物理方程 函数是非线性的 • 韦伯法则: 差异阈值与 初始刺激值的比例是恒 定的 ΔI / I = c • 韦伯法则 斜率随强度而变化 只是大约!
感 觉 大 小
刺激强度
阈值测量
• 费克纳的3种方法：
• 恒定刺激法 • 极限法 • 调整法 • 阶梯法 • 恒定刺激法的修正(适应的, 没有标准）
绝对阈值: 观察者可以只是勉强检测的强度
• 绝对阈值以下的强度：检测不到 • 绝对阈值以上的强度：检测
• 差异阈值（又名 最小可觉差（JND ）： 观察者注意到的最小强度差
• 强度变化比差异阈值小：察觉不到 • 强度变化比差异阈值大：察觉得到
阈值
如果假定一个线性关系， 两个值确定一个函数 :
线性物理方程
心理测量函数：差异阈值
Percentage “stronger”
100%
75% 50% 25%
0% PSE
比较刺激的光照强度
•
当观察者看不到差异时，他/她在“更强”或“更弱” 中随机选择;心理测量函数中这对应于50%的主观的对 等点（PSE）
心理测量函数：差异阈值
Percentage “stronger”
测量阈值相当于于50% 的心理测量函数(恒定 刺激法)
+ •
•
测量绝对阈值的限制法
+ 比较刺激的光强 + + + 阈值估计 + 试验 + 比较明朗 - 比较暗 + + + + + + +
• 直到反应比较刺激 的变化强度下降或 者上升 • 阈值估计 : 用标准和 比较刺激之间的强 度差来反应变化 • 取两个方向上的多 个系列求平均结果
Lecture 3 翻译的标准
Lecture 3 翻译的标准翻译标准：目前翻译界普遍接受的，也是作为一般翻译学习者必须努力掌握的标准，简而言之是两条：忠实(Faithfulness) 和流畅(Smoothness)。
外语腔是初学翻译者不知不觉地会在汉语译文中表现出来的一种不当倾向。
翻译时所要表达的内容来自外语原文，原文的词语和结构形式随着内容一起进入到我们的大脑，于是原文的语言形式被带入译文，造成了译文的外语腔。
The only concession he made to the climate was to wear a white dinner jacket.【译文】气候变化，他仅稍稍作了一点变通，赴宴时穿了件白色的短礼服。
翻译标准：忠实和流畅好的译文还必须保持原文的风格包括民族风格、时代风格、语体风格、作者个人的语言风格等。
即：译者不能破坏或改变原文的风格，不能以译者的风格代替原作的风格。
课堂练习：•She couldn't have come at a better time.•She has been a widow only six months.•I believe the speech was needlessly stubborn.•The Englishman feels no less deeply than any other nationality.•From a physical standpoint, there ought to be as many colours as there are different wave lengths.•As a human being, we should demonstrate our intellectual and moral superiority by respecting others for who they are -- instead of rejecting them for who/what they are not.1. 她来得正是时候。
【托福听力资料】托福tpo15听力文本-lecture3
【托福听力资料】托福TPO15 听力文本-Lecture 3众所周知，托福TPO材料是备考托福听力最好的材料。
相信众多备考托福的同学也一直在练习这套材料，那么在以下内容中我们就为大家带来托福TPO听力练习的文本，希望能为大家的备考带来帮助。
TPO 15 Lecture 3 Art HistoryNarrator: Listen to part of a lecture in an art history class.Professor:Now in Europe in the Middle Ages before the invention of printing and theprinting press, all books, all manuscripts were hand-made. And the materialtypically used for the pages was parchment, which is animal skin that’sstretched and dried under tension, so it become s really flat and can be writtenon . During the 1400s, when printing was being developed, paper became thepredominant material for books in Europe, but prior to that, it was parchment.Parchment is durable, much more so than paper, and it could be reused which camein handy since it was a costly material and in short supply, so it wasn ’ tuncommon for the scribes or monks who produced the manuscripts .Ah, remember before printing books were made mainly in monasteries . Well,the scribes often recycled the parchment that’d been used for earliermanuscripts. They simply erased the ink off the parchment and wrote somethingnew in its place A manuscript page that was written on, erased and then usedagain is called a palimpsest.Palimpsests were created, well, we know about two methods that were used forremoving ink from parchment. In the late Middle Ages, it was customary to scrapeaway the surface of the parchment with an abrasive, which completely wiped outany writing that was there. But earlier in the Middle Ages, the original ink was usually removed by washing the used parchment with milk. That removed the ink.But with the passing of time, the original writing might reappear. In fact , it might reappear to the extent that scholars could make out and even decipher the original text.Perhaps, the most famous example is the Archimedes’ palimpsest.Archimedes lived in Greece around 200 BCE, and as you probably know, he’s considered one of the greatest Mathematicians who ever lived, even though many of his writings had been lost , including what many now think to be his most important work called The Method .But in 1998, a book of prayers from the Middle Ages sold in an art auction for a lot of money, more money than anyone would pay for a damaged book from the12th century. Beautiful or not, why? It had been discovered that the book was apalimpsest, and beneath the surface writing of the manuscript laid, guess what?Mathematical theorems and diagrams from Archimedes.Archimedes’ writings were originally done on papyrus scrolls. Then in the 10 th century, a scribe made a copy on parchment of some of his texts and diagrams including, as it turns out, The Method . This was extremely fortunate, since later on, the original papyrus scrolls disappeared. About 200 years later in the12 th century, this parchment manuscript became a palimpsest when a scribe usedthe parchment to make a prayer book. So the pages, the pieces of parchmentthemselves, had been preserved. But the Archimedes’ text was erased and written over, and no one knew it existed.It wasn’t until 1906 that a scholar came across the prayer book in a library and realized it was a palimpsest, and that the underlying layer of texts could only have come from Archimedes. That was when his work The Method was discovered for the first time.Um... the palimpsest then went through some more tough times, but eventually it ended up in an art auction where was bought and then donated to an art museum in Baltimore, for conservation and study. To avoid further damage to the manuscript, the research team at the art museum has had to be extremely selective in the techniques they used to see the original writing. They’ve used ultraviolet light and some other techniques, and if you’re interested in that sort of thing, you can learn more about it in an art conservation class.But actually, it was a physicist who came up with a method that was a breakthrough. He realized that the iron in the ancient ink would display if exposed to a certain X-ray imaging method, and except for small portions of the text that couldn’t be deciphered, this technique’s been very helpful in seeing Archimedes’ texts and drawings through the medieval overwriting.。
Lecture3
Lecture 3外汇市场和汇率国际交易、外汇与汇率•国际交易产生了以货币表示的国与国之间的债权、债务关系，其清偿需要外汇；•外汇（foreign exchange）是以外币表示的支付手段，如银行存款、银行汇票；•例：机械进出口公司从英国某出口商买进一台机器，双方约定以美元支付（实际中，只有机器的跨国境流动，无美元跨国境流动）。
•汇率：以一种货币表示另一种货币的价格（即两种货币的交换比率）如：6.83 Ұ/$•汇率的两种表示方法–直接标价法：6.83 Ұ/$–间接标价法：0.15 $/Ұ•汇率与相对价格：汇率使我们可以计算以不同货币计价的商品的相对价格（？要~）•例：某学生要决定是购买一条国产牛仔裤还是一件美国产毛衣，其价格分别为150元人民币和75美元，设汇率为6.83Ұ/$，则美国产毛衣的相对价格为75* 6.83 /150=3.42（国际贸易中只有相对价格才是重要的）•汇率的变动：贬值与升值•例：如果人民币升值到6.00Ұ/$，则美国产毛衣的相对价格为3.00•普遍原则：其他条件不变时，一国货币升值使进口商品的相对价格（相对于？）下降；使出口商品的相对价格上升。
•因为汇率对净出口和其它宏观变量有重要影响，所以汇率是开放经济中最重要的变量之一。
汇率对进出口的重要性取决于它在多大程度上影响相对价格。
•基本汇率和套算汇率（152种货币、11476种汇率）例：SF/$=2.000JҰ/$=120.000JҰ/SF=60•电汇、信汇汇率；现汇价、现钞价.•汇率是在何处、如何决定的？外汇市场•外汇市场的参与者–商业银行–从事国际贸易的公司、个人–非银行金融机构–中央银行–外汇经纪人•外汇市场的组织–批发市场（银行间市场）–零售市场（店头市场）•通常所说的汇率是在批发市场上决定的。
•批发市场中的做市商与经纪人（后者自身不持有外汇头寸）。
•经纪人的特殊作用•外汇市场的特征–外汇市场为分散化的市场–外汇市场交易量巨大且主要是交易商间交易–外汇市场交易的透明度低•批发市场中的做市商（大型商业银行）不仅在国内银行间市场上进行外汇交易，而且通过其海外的代理、分支机构在海外的银行间市场上进行交易，形成全球一体化的外汇市场。
lecture3
Me
Wojtkowski, JOC 1971, 1790.
Shanghai, China
• Base-induced Reactions
Aldol-type reactions:
O R N2
LDA is the optimal base for lithiation
Shanghai, China
§ 4-1 Some Reactions of Nitro Compounds
Stabilized carbanion Transformation of the -NO2 group
NO2 R
Other reactions
-NO2 as a Leaving Group
Me O
Me O
Me
Smith, JACS, 1981, 2009.
Me
Rearrangement:
OO N2
BF3 OEt 2
O N2
N2
O
R
Mander, Aust. J. Chem. 1979, 1975.
OBF 3 R
R
O
Shanghai, China
• Ring Expansion Reactions:
Shanghai, China
• Nucleophilic Addition
OH O R NO 2 + H R R3N EtOH NO 2 R
+ n
R R
O
R NO 2
H2N(CH 2)2NMe 2 Benzene, 80oC
NO 2
n NO 2
+ H2N(CH 2)2NMe 2 Benzene, 80oC
lecture 3--跨文化交际
Similarities:
Meeting: shake hands Goodbye: waving hands Displeasure: frown Dislike, disgust, disapproval: wrinkling nose Yes: nodding No: shake heads Displeasure, bad humor, resentment: pouting Approval: a pat on the back of a man Anger, fury, determination: gritting one’s teeth
Exercise: 1. What may the OK sign mean
1. in Brazil 2. in Russia 3. in France 4. in Japan
a. something vulgar粗俗，下流 b. rudeness c. something worthless d. money
8
2. Importance of NC
Nonverbal behavior is significant area of
communication study. communication is NC. There’re three main reasons for its significance:
7
1.
Part 2 Nonverbal Communication
1. Definition of NC
Nonverbal communication is the interaction
that is carried out by our bodies, gestures, and tones of voices, in other words, everything except the actual words we apply in our communication, such as the look on our face, the way we speak, the movements of our hands, the wink of our eyes. They all send messages to those we are thinking to.
英语语言学lecture 3 Phonetics
fricatives
When the obstruction is partial and the air is forced through a narrow passage in the mouth so as to cause definite local friction at the point.[f][v][s][z]…(p.53)
Classification of English speech sounds:
Vowels (20):
the sounds are produced when the air-streams meet no
obstruction of any kind in the throat, the nose, or the
Stops:or plosive consonants:
When the obstruction created by the speech organ is total or complete, the speech sound produced with the obstruction audibly released and the air passing out again is called a stop or a plosive: [p][b][t][d][k][g]
There are two kinds of transcription: narrow transcription and broad transcription. A narrow transcription records as many features of an utterance as possible. This is the transcription needed and used by the phoneticians in their study of speech sounds. A broad transcription omits many of the irrelevant and predictable details of pronunciation . This is the transcription normally used in dictionaries and textbook for general purposes.
lecture3《大学》英译赏析
The Appreciation of the English Translation of Da Xue
背景介绍
Background Information
?大学?原为?礼记?中的一篇，相传为曾参〔前505－前432〕所撰， 为唐人韩愈、李翱所竭力推崇。宋代程颐程颢兄弟对其进展了系 统地整理和深入研究，使其初具独立成经的地位。
Psalm 94:1: “O LORD, the God who avenges, O God who avenges, shine forth.〞(耶和华啊，你是伸冤的神；伸冤的神啊，求你发出 光来！)
“小学〞VS.“大学〞
?礼记·学记?：“古之教者，家有塾，党有庠，术 有序，国有学。比年入学，中年考校。一年视离 经辨志，三年视敬业乐群，五年视博习亲师，七 年视论学取友，谓之小成。九年知类通达，强立 而不反，谓之大成。夫然后足以化民易俗，近者 说服而远者怀之，此大学之道也。〞
Only when one comes to understand this point of rest can one reach a state of unwavering stability. Having reached this unwavering state, one can then enjoy an unruffled quietude; having attained this state of quietude, one can then achieve an inner calm; once one has achieved this inner calm, one is then in a position to exercise one’s capacity to deliberate clearly. And it is the capacity of deliberation that provide the basis for all moral attainment.
Lecture 3
glottis
Vocal cords
Vocal cords
vocal cords glottis
Vocal cords closed
The mouth
nasal cavity 齿龈alveolar ridge upper teeth upper lip lower lip lower teeth 下颌 mandible hard palate硬腭 soft palate (velum) 软腭 uvula小舌
3.3.1 Segments and divergences
When we produce the word “fish” slowly, we can perceive the different segments ( 音 段 ) in this word, /f/, /i/ and /ʃ/. The reason for the divergence is that there are more sounds in English than the letters can represent. For this reason, we have to turn to phonetic transcription to make sure of the correct pronunciation of a word.
• Its main principles were that – there should be a separate letter for each distinctive sound, and – that the same symbol should be used for that sound in any language in which it appears. – The alphabet was to consist of as many Roman alphabet letters as possible, using new letters and diacritics only when absolutely necessary. • These principles continue to be followed today.
托福听力TPO18原文Lecture3
托福听力TPO18原文Lecture3下面就让小编来为大家介绍一下托福听力TPO18原文中Lecture3的文本内容吧，大家要好好把握，这些都是非常有价值的材料，同时，大家也可以登录前程百利论坛进行TPO练习辅导，希望能够给准备托福听力的同学带来帮助。
TPO18Lecture3European HistoryProfessor：In order to really study the social history of the Middle Ages,you have to understand the role of spices.Now,this might sound a little spurring,even a little strange.But what seem like little things now were back then actually rather big things. So first let’s define what a spice is.Technically speaking,a spice is part of an aromatic plant that is not a leaf or herb.Spices can come from tree bark like cinnamon,plant roots like ginger,flower buds like cloves.And in the Middle Ages.Europeans were familiar with lots of different spices,most important being pepper,cloves,ginger,cinnamon,maize and nutmeg.These spices literarily dominated the way Europeans lived for centuries,how they traded and even how they used their imaginations.So why this medieval fascination with spices?We can boil it down to there general ideas briefly.One was cost and rarity.Uh two was exotic taste and fragrance.And third,mysterious origins and kinds of mythical status.Now for cost and rarity,spices aren’t native to Europe and they had to be imported. Spices only grew in the East Indies and of course transportation costs were incredibly valuable even from the very beginning.Here is an example.In408AD,the Gothic General who captured Rome demanded payment.He wanted5000pounds of gold among other things but he also wanted3000pounds of pepper.Maybe that would give you an idea of exactly where pepper stood at the time.By the Middle Ages,spices were regarded as so important and expensive they were used in diplomacy,as gifts by heads of state and ambassadors.Now for the taste.The diet then was relatively bland,compared to today’s.There wasn’t much variety.Especially the aristocracy who tended to eat a lot of meat,they were always looking for new ways to prepare it,new sources,new tastes and this is where spices came in.Now,this is a good point to mention one of the biggest myths about spices.It’s commonly said that medieval Europeans wanted spices to cover up the taste of spoiled meat.But thisisn’t really true.Anyone who had to worry about spoiled meat couldn’t afford spices in the first place.If you could afford spices,you could definitely afford fresh meat.We also have evidence that various medieval markets employed a kind of police to make sure that people did not sell spoiled food,and if you were caught doing it,you were subject to various fines,humiliating public punishments.So what actually was true was this:In order to have meat for the winter,people would preserve it in salt,not a spice.Spices actually aren’t very effective as preservatives.And throughout winter,they would eat salted meat,but the taste of the stuff could grow really boring and depressing after a while.So the cook started looking for new ways to improve the taste and spices were the answer, which brings us to mysterious origins and mythical status.Now the ancient Romans had a thriving spice trade and they sent their ships to the east and back.But when Rome collapsed in the fifth century and the Middle Ages began,direct trade stopped,and so did that kind of hands-on knowledge of travel and geography.Spices now came by way of the trade routes with lots of intermediaries between the producer and the consumer.So these spices took on an air of mystery.Their origins were shrouded in exotic travels.They had the allure of the unknown,of wild places.Myths grew up of fantasy lands,magical faraway places made entirely of food and spices.And to that,spices themselves had always been considered special or magical not just for eating and this was already true in the ancient world where legends about spices were abundant.Spices inspired the medieval imagination.They were used as medicines to ward off diseases,and mixed into perfumes,incent.They were used in religious rituals for thousands of years.They took on a life of their own and they inspired the medieval imagination,spurred on the age of discovery in the145th and16th centuries.When famous explorers like Columbus and da Gama and Magellan left Europe in their ships,they weren’t looking for a new world.;they were looking for spices.And we know what important historical repercussions some of those voyages had.教授：同学们，要理解中世纪的社会发展历史，你们必须要理解香料的重要作用。
托福听力TPO11原文 Lecture 3-智课教育旗下智课教育
智 课 网 托 福 备 考 资 料托福听力TPO11原文 Lecture 3-智课教育旗下智课教育以下是小编为大家整理的托福听力TPO11原文中Lecture 3的文本内容，希望大家能够认真阅读，不懂的地方可以参考翻译，相信会有所收获。
下面就让小编来为大家介绍一下托福听力TPO11原文中Lecture 3的文本内容吧，大家要好好把握，这些都是非常有价值的材料，同时，大家也可以登录智课教育论坛进行TPO练习辅导，希望能够给准备托福听力的同学带来帮助。
TPO11 Lecture 3 Environmental scienceProfessor：When land gets develop for human use, the landscape changes. We don’t see as many types of vegetation, trees, grasses and so forth. This in turn leads to other losses: the loss of animal that once lived there. Err…but these are the obvious changes, but there are also less obvious changes like the climate.One interesting case of this…of…of changes in the local land use causing changes in climate, specifically the temperature is in Florida. Now what comes to mind when you think of the state of Florida?Student A：Sunshine, beaches.Student B：Warm weather, oranges…Professor：Yes, exactly. Florida has long had a great citric industry; large growth of oranges, lemons and the like. Florida’s winter is very mild; the temperature doesn’t often get below freezing. But there are some areas in Florida that do freeze. So in the early 1900s, farmers moved even further south in Florida, to areas that were even less likely to freeze. Obviously, freezing temperatures are danger to the crops. A bad barrier of cold weather, a long spell of frosts could ruin a farm and the entire crop, anyway, before these citric growers moved south, much of the land in south Florida, was what we called wetlands.Wetlands are areas of marshy, swampy land, areas where water covers thesoil, or is present either at or near the surface of the soil for large part of the year. Wetlands have their own unique ecosystem, with plants and animals with special an interesting adaptation. Very exciting, but it’s not what we are talking about today. Emm…where was I?Student A：Farmers moved south?Professor：Oh, yes. Farmers moved south. But the land was not suitable for farming. You can’t grow orange in wetland, so farmers had to transform the wetlands into lands suitable for farming. To do that, you have to drain the water from theland,move the water elsewhere, and divert to the water sources such as rivers. Hundreds of miles of drainage canals were built in the wetlands. Now these areas, the new areas the farmers moved to, used to be warm and unlikely to freeze, however, recently the area has become susceptible to freezes. And we are trying to understand why.Student B：Is it some global temperature change or weather pattern like El Ni?o or something?Professor：Well, there are two theories. One idea is as you suggested that major weather patterns, something like El Ni?o, are responsible. But the other idea and this is the one that I personally subscribe to, is of the changes in the temperature pattern had been brought about by the loss of wetlands.Student A：Well, how would the loss of wetlands make a difference?Professor：Well, think about what we’ve been studying so far. We discussed the impact of landscapes on temperature, right? What affects does the body of water have on an area?Student A：Oh, yeah. Bodies of water tend to absorb the heat during the day, and then they release the heat at night.Professor：Yes, exactly. What you just said is what I want you all to understand. Bodies of water release heat and moisture backinto the environment. So places near large bodies of water are generally milder, err...slightly warmer than those without water. And what I, another think is that the loss of the wetlands has created the situation where the local temperatures in the area are not slightly different, slightly colder than they were 100 years ago, before the wetland were drained.Student B：Emm…do we know what the temperature was like back then?Professor：Well, we were able to estimate this. We have data about South Florida’s current landscape, emm…the plant cover. And we were able to reconstruct data about the landscape prior to 1900. Then we enter those data, information about what the landscape look like before and after the wetlands weredrained.We enter the data into a computer weather model. This model can predict temperatures. And when all the data were entered, an overall cooling trend was predicted by the model.Student B：How much colder does it get now?Professor：Well, actually the model shows a drop of only a few degrees Celsius. But this is enough to cause dramatic damage to crops. If temperatures over night are already very close to the freezing point, then this drop of just a few degrees can take the temperature below freezing. And freezing causes frosts, which kill crops. These damaging frosts wouldn’t happen if the wetlands were still in existence, just as the tiny temperature difference can have major consequences.《环境科学》教授：当土地发展到适应人类使用，景色就发生了变化。
托福tpo22 lecture3
托福TPO22 LECTURE3
4. What point does the professor make when she discusses the
maclura tree? A. The feeding habits of large animals could help revive some diminishing plant species. B. The climate has changed in North America since the Pleistocene epoch C. Mass extinctions of animals are generally preceded by mass extinctions of plants. D. The maclura tree has changed very little since the Ice Age.
解析：A（3’42”）定位句：Many types of maclura used to grow in North American, but today, just one variety remains and it is found in only two states. In the distant past, large herbivores like mastodons dispersed maclura seeds, each the size of an orange in their droppings
解析：B（2’40”）定位句：We believe it played a pivotal role in the evolution of the pronghorn antelope, the antelope’s amazing speed, to be exact, because natural selection would favor those antelope that could outrun a cheetah. let’s take the now extinct American cheetah, for instance.
Lecture 3
Exercise
a) Choose between WILL+INF. and WILL BE+- ING: 1. A: I am going to Switzerland next week. B: You are lucky. The wild flowers just ___(come) out. 2. It ___ (be) very late when she gets home, and her parents ___ (wonder) what’s happened. 3. He ___ (come) if you ask him. 4. A: I wonder what I ___ (do) this time next year. B: I expect you ___ (work) at the same office. 5. A: I ___ (get) you some cigarettes if you like. The shops still ___ (be) open. B: No, don’t bother. The office boy ___ (go) out in a minute to post the letters; I ___ (ask) him to buy me some.
3.1.2 Uses of present future time 1) will /shall do We shall have a meeting tomorrow. The crisis will soon come to an end. 2) will /shall be doing (1) He will be playing football at three tomorrow afternoon. (2) I will be writing to Peter
lecture 3 古希腊罗马神话 英文版 教学课件
Eros (Cupid) and Psyche (
• He commonly carried bow and arrows, and caused gods and men to fall deeply in love by shooting arrows of desire into their hearts. • A person shot with one of his gold-tipped arrows fall in love, and shot with his leadtipped arrows hate love affairs. • Psyche was the daughter of a king, who was so beautiful that people turned to worshiping her instead of Venus, goddess of beauty. • Venus became angry and sent her son Eros (Cupid) to make Psyche fall in love with the ugliest man in the world.
Eros (Cupid) and Psyche
• Psyche was heartbroken and wandered throughout the world in search of him. • Finally, she arrived at the palace where Aphrodite (Venus) was living, and asked the goddess to forgive her, who made her slave and gave her some nearly impossible tasks to fulfill. • The first was to sort out before nightfall an enormous heap of various kinds of grain. • But the ants took pity on her, came in large numbers and did the job for her. • The last was to go down to the Underworld and fetch a box filled with the beauty of Persephone, the queen of the
托福听力TPO21原文 Lecture 3
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TPO21 Lecture3 Biology(Snake Evolution)Professor：Probably back in some previous biology course you learned that snakes evolved from lizards, and that the first snakes weren’t venomous and then along came more advanced snakes, the venomous snakes. Ok, venomous snakes are the ones that secrete poisonous substances or venom, like the snakes of the viper family or cobras. Then there is non-venomous snakes like constrictors and pythons. Another family of snakes, the colubrids, don’t really fit neatly into either category though. Colubrids, and you probably learned this too, although they are often classified as venomous snakes, they are actually generally non-venomous. They are classified as venomous snakes because they resemble them, their advanced features more than the other non-venomous snakes.Now, what if I told you that there is a good chance that most everything I just said is wrong? Well, everything except the part about snakes evolving from lizards. See, the basic theory about snake evolution has been challenged by a recent study that revealed a whole new understanding of evolutionary relationship for reptiles, you know, which reptiles descended from which ancestors. The researchers study the proteins in the venom genes of various species of colubrids. Emm... snake venom is a mixture of proteins, some toxic, poisonous, and some not. By analyzing the DNA, the genetic material of the proteins, the researchers could focus on the toxic genes and use them to trace the evolution of snake venom, and from this, the evolution ofsnakes.Traditionally, to understanding evolutionary relationships, we looked at various easily observed physical characteristics of animals, their skeleton, the size of their brain, and... and then classify them based on similarities and differences. The problem with this method is that characteristics that appear similar may actually have developed in quite different ways. For example, some venoms are chemical-based, and others are bacteria-based, so they clearly had to have developed along different routes and may not be as closely related as we thought.Now, and not everyone will agree about this. The classification based on DNA seems to be much more reliable. Ok, back to the research. The researchers found that venom evolved before snakes even existed, about a hundred million years before. Now, a couple of venomous lizards were included in this study.And the researchers found some of the same DNA in their venom as in the snakes’ venom. This suggested that the common ancestor of all snakes was actually venomous lizard, which means that actually, according to this research, anyway, in terms of the snakes’ ancestry, there is no such thing as a non-venomous snake, not even colubrids. What separates colubrids from other snakes we have been classifying is venomous, is not the lack of venom, but the lack of an effective way to deliver the venom into its prey. In most venomous snakes, like vipers and cobras, the venom is used to catch and inmoblize the prey; but in colubrids, venom drips onto the prey only after the prey is in the snake’s mouth. So for colubrids, the venom must serve some other purpose, maybe linked to digesting prey. As the different families of venomous snakes evolved, the teeth moved forward, becoming larger, and the venom becoming stronger, so the evolution of the obvious venomous snakes, like cobras and vipers, is about the evolution of an efficient delivery system, not so much the evolution of the venom itself. So, if there are no truly non-venomous snakes, were the so-called non-venomous snakes, like constrictors and pythons, were they venomous at some point in their evolution? Well, that’s not clear at this point. Constrictors have evolved to kill their prey by crushing, but perhaps they once were venomous, and then at some point their venom-producing apparatu s4 wasn’t needed anymore, so it gradually disappeared. There’s one species of snake, the brown tree snake, that uses both constriction and venom, depending on its prey. So, well, it is possible.So, we have these new concepts of snakes’ evolution and a n ew DNA database, all these information on the genetic makeup of snake venom. And what we have learned from this has led researchers to believe that venom proteins may have some exciting applications in the field of medical research. You see, venom alters biological functions in the same way certain drugs do, and the big benefit of drugs made from snakes venom would be that they target only certain cells, so maybe that’ll create fewer side effects. Now, it sounds far-fetched5, venom is the basis for human drugs. So far, only one protein has been targeted for study as a potential drug, but who knows, maybe someday.教授：可能在之前的生物课上你们学习到蛇是由蜥蜴进化而来，而且起初的蛇是没有毒的，后来才出现了更高级的蛇，也就是毒蛇。
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English teaching
6-10 hours per week in addition to class
General Physics I
1
Today’s topics
My Laws of Motion!
General Physics I
Force is exerted on an object by other objects, either physically touched or at a distance. Force is a vector with both a magnitude and a direction.
y x
a
General Physics I
11
Mass
The mass of a body is an intrinsic characteristic that relates a force exerted on the body to the resulting acceleration.
General Physics I
6
Newton’s Epitaph by Pope
“Nature and Nature’s laws lay hid in night: God said, Let Newton be! And all was light.”
---- Alexander Pope
Magnitude:
Fg mg
Direction: points towards the center of Earth Weight: The weight W of a body is equal to the magnitude of the gravitational force on the body.
a
General Physics I
10
Inertial Reference Frame
A reference frame at rest or with constant velocity is an inertial frame, or is it?
Ground is usually assumed as an inertial frame, neglecting Earth’s astronomical motion.
At very large speeds (an appreciable fraction of the speed of light c), Newtonian mechanics must be replaced by Einstein’s special theory of relativity. If objects under study are very small (at atomic scale, ~10-10 or 10-9 m), Newtonian mechanics must be replaced by quantum mechanics.
Mass is a scalar. It is a measurement of an object’s inertia. The greater an object’s mass, the more the object resists being accelerated.
General Physics I
General Physics I
16
Solution FA FB FC m(0) 0 FB FA FC
Force components in x-axis:
FBX FAX FCX FB cos( 90 ) FA cos133 FC cos 0 ( 220 N) (cos133 ) (170 N) cos
( 220 N ) (cos 133 ) 1 cos 28.04 170 N
General Physics I
17
Force components in y-axis:
FBy FAy FCy FB sin ( 90 ) FA sin 133 FC sin , FB (220 N) (sin133 ) (170 N) sin 28.04
When a body presses against a surface, the surface (even a seemingly rigid surface) deforms and pushes on the body with a normal force that is perpendicular to the surface.
General Physics I
8
Newton’s First Law: Law of Inertial
General Physics I
9
Inertial Reference Frame
An inertial reference frame is one in which Newton's laws hold. An accelerating train is a non-inertial frame.
General Physics I
13
Unit of Force
In SI, the force unit is newton.
1 N (1 kg) (1 m / s ) 1 kg m / s
2
2
General Physics I
14
Free-Body Diagram (F.B.D.)
25
General Physics I
Newton’s Third Law
When two bodies interact, the forces on the bodies from each other are always equal in magnitude and opposite in direction.
General Physics I
27
Applying Newton’s Laws
Objects stuck together, Objects connected through cord over pulley, Objects on an inclined plane, Scale reading in an elevator, ...
12
Newton’s Second Law
The net force on a body is equal to the product of the body's mass and the acceleration of the body.
Fnet ma (Newton' s second law) .
General Physics I
15
Sample Problem
In a two-dimensional tug-of-war, Alex, Betty, and Charles pull horizontally on an automobile tire at the angles shown in the overhead view of the figure.
2
Force and Motion
Q: What is the cause for the change of motion status (acceleration) of an object?
A: Force
General Physics I
3
Force
Force causes acceleration of an object.
General Physics I
7
Newtonian Mechanics
Newtonian Mechanics describes the relation between force and motion based on the laws by Isaac Newton (16421727).
General Physics I
20
Einstein Asks…
General Physics I
21
The Gravitational Force
Newtonian Mechanics
General Physics I
Einstein’s General Relativity
22
The Normal Force
Third-law force pair:
FBC FCB
General Physics I
26
Conceptual Question
How dose a horse try to use physics to escape work!
A horse refuses to pull a cart. He reasons:“According to Newton’s third law, whatever force I exert on the cart, it will exert an equal and opposite force on me, so the net force will be zero and I will have no change of accelerating the cart.”
General Physics I
4
Force is Vector
principle of superposition fI
5
Net Force Net force is the sum of all forces on a body. It is an effect, NOT a real force. In the case Fnet = 0, the forces cancel one another. But each individual force still exists. Only the net effect on the body is like no forces on it at all.