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Transcript
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针对 2015 年 5 月 24 日阅读新加 6 套题
[因为 2015.5.16 加场考试全部命中 2014.5.11 大陆题,特此针对 5 月 26 日加 6 套 2014
年大陆机经]
——新东方北美研发中心
2014 年 4 月 12 日
第一篇:
机经:Venus 和地球的联系,区别和不同
解析:这套题是天文主题。了解部分背景知识对解题有提速作用。
另,阅读涉及区别和联系的文章,需对相关逻辑关系词有较好把握。
Venus compared with the Earth
Venus is often named as Earth's twin because both worlds share a similar size,
surface composition and have an atmosphere with a complex weather system.
The figure on the right compares Venus and Earth spacecraft images. The surface
of Venus is shown in orange as radar images while the atmosphere is reproduced
on near true colors as it would be seen by the human eye. The upper clouds are
brightest in the blue and ultraviolet wavelengths making Venus a white-blue
colour planet. Both planets have almost the same size and density and Venus
is only a 30% closer to the Sun than Earth. Both share an interesting geological
evolution with old volcanoes in Venus and some of them could still be active.
One of the biggest misteries of Venus is why its surface is so young on geological
time-scales. It is interesting to remark that there is almost no water on Venus'
atmosphere.
There are many more differences between both planets.
Whereas Earth rotates in about 24 hours Venus rotates in the contrary sense
(retrograde rotation) in 243 days. The orbital period of Venus is 225 days so
that a Venus year takes less than a full day. The combination of these two periods
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results in the Sun appearing from the West and dissapearing over the East with
a day-night cycle of 117 days.
The atmosphere of Venus is 90 times more dense than that on Earth and it is
made of 96.5% of CO2 and a 3% of nitrogen. This means that both planets have
the same amount of Nitrogen on their atmospheres. Surprinsingly the CO2 on Earth
is stored on calcite type rocks and if we would convert the CO2 on these rocks
into atmospheric CO2 it would amount to the same amount of CO2 that there is
on Venus' atmosphere.
Because of the denser atmosphere and the chemical composition Venus experiences
an inmense green-house effect that raises the temperature over the surface to
more than 470.
The figure on the right illustrates the basics of the greenhouse effect on Venus.
Long-wave radiation from the Sun is mainly reflected at the upper cloud deck
and partially absorbed by the atmosphere but part of it reaches the surface
and heats the lowest atmosphere. The hot surface cools down emitting short-wave
radiation that is absorbed and re-emitted by the green-house gases of the
atmosphere impeding cooling of the planet and originating the high temperatures
at the surface. Figure extracted from here.
Clouds are common on Earth but they cover completely Venus' atmosphere. They
are made of sulfuric acid droplets at 50-70 km above the surface and at
temperatures comparables to Earth's surface temperatures. They are extremely
reflective making Venus the most reflecting body in the Solar System.
第二篇:
机经: 美索不达米亚地区灌溉系统 灌溉系统发展导致洪水和盐碱地 洪水盐碱地的治
理方式 及梯田的开发,水土保持。
解析:涉及考古和历史类的文章,需对时间顺序有较强把握。按时间链走的文章,部
分段落的主题信息比较容易分散在段落中,而不是在第一句中整体体现。所以进行整
段概括的同时,需要关注是否有转折信息。
Mesopotamia: Canals on the Plain
Irrigation has been an important base for agriculture in Mesopotamia (what is
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now Iraq and part of Iran) for 6000 years. But Mesopotamia is very different
from Egypt. Mesopotamia has low rainfall, and is supplied with surface water
by only two major rivers, the Tigris and the Euphrates. Although they are much
smaller than of the Nile, they have much more dramatic spring floods, from
snowmelt in the highlands of Anatolia, and they carry more silt. Furthermore,
the plains of Mesopotamia are very flat, and poorly drained, so that the region
has always had persistent problems with poor soil, drought, catastrophic
flooding, silting, and soil salinity.
Mesopotamian engineers had to worry about water storage and flood control as
well as irrigation. Silt built up quickly in the canals, threatening to choke
them. This could be overcome by constant dredging as long as organization and
manpower were available. The other problem was more insidious, and could not
be overcome by the engineering available at the time. It was difficult to drain
water off the fields, and there was always a tendency for salt to build up in
the soil.
Although the plain of Mesopotamia is very flat, the bed of the Euphrates is
higher than that of the Tigris; in fact, Euphrates floods sometimes found their
way across country into the Tigris. Engineers used this gradient as soon as
irrigation schemes became large enough, using the Euphrates water as the supply,
and the Tigris channel as a drain.
Mesopotamia has had times of successful irrigation, and times of silt and
salinity crises: the latter around 2000 BC, 1100 BC, and after 1200 AD. The
first crisis may have been caused by water politics. In any irrigation system,
the farmers most downstream are those most likely to be short of water in a
dry year, or to receive the most polluted water. In Sumeria, the city of Lagash
was rather far downstream in the canal system based on the Euphrates. Apparently
Entemanna of Lagash decided that he would instead cut a canal to tap Tigris
water, but the addition of poor-quality water led to rapid salinization of the
soil.
Sumeria
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The earliest city-states of Mesopotamia, those of Sumeria, lay in the lowest,
most water-rich areas of what is now southern Iraq. Irrigation could be fairly
simple in this region, with each city-state probably building one irrigation
system. The cities may have originally been administrative centers, marketing
centers, and defensive centers related to local irrigation schemes: in other
words, they were "irrigation cities".
From time to time catastrophic floods overwhelmed the region. At Ur there is
a well-known band of 1.5 m of clay between two layers of pottery. This is evidence
of a major flood, and this event was probably the basis for the flood story
in the Sumerian Epic of Gilgamesh and for the much later Biblical story of the
Flood.
Mesopotamian engineers built very large weirs and diversion dams, to create
reservoirs and to supply canals that carried water considerable distances
across the flat countryside. The scale of their irrigation was larger than in
Egypt, and Mesopotamian irrigation was interventionist and active. Almost
certainly the idea of diversion dams was brought to Mesopotamia from the hills,
since the rivers are mostly perennial. Mesopotamian tradition suggests so:
Sargon of Assyria, probably learned it from the ancient nation of Urartu. The
scale and ambition of early Iron Age Mesopotamian projects was matched only
in China and Egypt.
The Abassids
After the wave of Moslem expansion broke over Mesopotamia, the Abassid Caliphate
was based on Baghdad from 762 AD until its demise in 1258. Existing irrigation
schemes were renovated and greatly extended in very large projects. Abassid
engineers drew water from the Euphrates at five separate points, and led it
in parallel canals across the plains, watering a huge area south of Baghdad.
This system provided the basis for the enormously rich culture of Baghdad, which
is still remembered in legend (Scheherezade, the Caliph of Baghdad, and the
Arabian Nights) as well as history. But it required a lot of physical maintenance,
and there was a lot of salinization in the south. As central government began
to fail in the 12th century (mostly from extravagant overspending), the canals
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became silt-choked, the irrigation system deteriorated, and the lands became
more salinized. The deathblow to the system was natural: massive floods about
1200 AD shifted the courses of both the Tigris and the Euphrates, cutting off
most of the water supply to the Nahrwan Canal and wrecking the whole system.
The Abbasids were too weak (or bankrupt) by now to institute repairs, and the
agricultural system collapsed. By the time the Mongols under Hulagu devastated
Iraq and Baghdad in 1258 AD, they were finishing off a society that was already
a wasteland. Iraq has remained a desert for more than 600 years.
第三篇:
机经:
太平洋地区 火山地质活动形成的岛上的物种的传播 鸟风浪传播 及影响分布的 4 个原
因
分析:生物多样性是一个很经典的主题。这篇文章相当于一篇较多主题综合的文章。
但由于背景知识的简单性,所以不会对考生造成太多干扰。
相关背景:
What is Island Biodiversity?
An explanation of island biodiversity should start with a definition of islands.
Yet this definition is elusive. Although we can all agree that an island,
strictly speaking, is a piece of land surrounded by water, beyond this
stiupulation, there is no single accepted definition. The Millennium Ecosystem
Assessment, for example, defines islands as “lands isolated by surrounding
water and with a high proportion of coast to hinterland”; stipulates that they
must be populated, separated from the mainland by a distance of at least two
kilometres, and measure between 0.15 square kilometres and the size of Greenland
(2.2 million square kilometres). Islands located within seas can be categorized
in many ways, including by their area; by their altitude into high and low-lying
islands; by a combination of the size of the land area, and political and
demographic criteria to identify small island developing States; by their
distance from the nearest continent; whether there are inhabited or not; the
number of inhabitants; or whether they are continental (land areas that used
to be connected to the mainland) or oceanic (those that rose from the sea as
a result of coral deposits, volcanic activity or tectonic forces) islands. At
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the SCBD, work on island biodiversity emphasizes oceanic islands and
particularly small island developing States (SIDS) because these systems are
often perceived to be the most at risk.
In terms of biodiversity, the issue is clearer: islands boast a truly unique
assemblage of life. Species become island dwellers either by drifting on islands,
like castaways, as they break off from larger landmasses (in the case of
continental islands) or by dispersing across the ocean to islands newly emerged
from the ocean floor (oceanic islands). Henceforth they are confined to small,
isolated areas located some distance from other large landmasses. Over time,
this isolation exerts unique evolutionary forces that result in the development
of a distinct genetic reservoir and the emergence of highly specialized species
with entirely new characteristics and the occurrence of unusual adaptations,
such as gigantism, dwarfism, flightlessness, and loss of dispersability and
defence mechanisms. Genetic diversity and population sizes tend to be limited,
and species often become concentrated in small confined areas.
The legacy of a unique evolutionary history, many island species are
endemic—found nowhere else on Earth. Islands harbour higher concentrations
of endemic species than do continents, and the number and proportion of endemics
rises with increasing isolation, island size and topographic variety. For
example, over 90% of Hawaiian island species are endemic. In Mauritius, some
50% of all higher plants, mammals, birds, reptiles and amphibians are endemic,
and the Seychelles has the highest level of amphibian endemism in the world.
The island of Cuba is home to 18 endemic mammals, while mainland Guatemala and
Honduras, both nearby, have only three each. Madagascar is home to more than
8000 endemic species, making it the nation with the highest number of endemic
species in sub-Saharan Africa.
It has often been remarked that islands make a contribution to global
biodiversity that is out of proportion to their land area. In this sense, they
can be thought of collectively as biodiversity “hot spots”, containing some
of the richest reservoirs of plants and animals on Earth.
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第二套:
第一篇:Origins of writing
机经版本一:
先说 writing 的材料,主要讲了一个中东地区的 S 民族,这个民族发明了一种 Clay,
非常耐用,适合长期保存。
同时说了,Egypt 也有自己的发展, 叫什么 reed 做的东西,这种东西有缺点,就是
像现在的纸一样容易碎。(有题,问为什么说埃及人用这种材料)
然后讲 Clay 的好处,说是传遍地中海,全都使用这种材料。后来这个 S 被他国占领了,
语言也被别的国家抢去了,word 和 sound 都变了意义。但是 literature 没变。 就像
Latin 语,罗马帝国退去,Latin 的文字形式还是保存下来。但是这种东西很难学,需
要 train,只有少数 S 族几个人会(这些都是考题)。
然后讲 people 用 writing 干什么,就是一个 evolution 过程,最开始是记一些东西的
数量,后来变成了记载国家大事,商业帐本,之类的比较琐碎的日常东西。
再讲 clay 这个东西经久耐用,现在出土的问题都保存得比较好,所以学者们都很喜欢
这些东西,因为要研究。Clay 这个东西经常能挖出来。
词汇题:key, virtue, now and then
机经版本二:
这篇文章里有好多学术词,实在不记得了。有两种人,A。。。S。。。埃及人刚开始在一
种叫做 papyrus 的材料写字,这种材料有个缺点就是 fragile,especially 容易 be
destroyed by fires. 所以后来开始使用 S 人创造的一种材料,埃及人给这种材料创
造了 sounds 和 words.
解析:苏美尔是常考主题。由于涉及时间,读文章时一定要有主观意识去自行概括主
题。
The Sumerians were one of the earliest urban societies to emerge in the world,
in Southern Mesopotamia more than 5000 years ago. They developed a writing
system whose wedge-shaped strokes would influence the style of scripts in the
same geographical area for the next 3000 years. Eventually, all of these diverse
writing systems, which encompass both logophonetic, consonantal alphabetic,
and syllabic systems, became known as cuneiform.
It is actually possible to trace the long road of the invention of the Sumerian
writing system. For 5000 years before the appearance of writing in Mesopotamia,
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there were small clay objects in abstract shapes, called clay tokens, which
were apparently used for counting agricultural and manufactured goods. As time
went by, the ancient Mesopotamians realized that they needed a way to keep all
the clay tokens securely together (to prevent loss, theft, etc), so they started
putting multiple clay tokens into a large, hollow clay container which they
then sealed up. However, once sealed, the problem of remembering how many tokens
were inside the container arose. To solve this problem, the Mesopotamians
started impressing pictures of the clay tokens on the surface of the clay
container with a stylus. Also, if there were five clay tokens inside, they would
impress the picture of the token five times, and so problem of what and how
many inside the container was solved.
Subsequently, the ancient Mesopotamians stopped using clay tokens altogether,
and simply impressed the symbol of the clay tokens on wet clay surfaces. In
addition to symbols derived from clay tokens, they also added other symbols
that were more pictographic in nature, i.e. they resemble the natural object
they represent. Moreover, instead of repeating the same picture over and over
again to represent multiple objects of the same type, they used diferent kinds
of small marks to "count" the number of objects, thus adding a system for
enumerating objects to their incipient system of symbols. Examples of this early
system represents some of the earliest texts found in the Sumerian cities of
Uruk and Jamdat Nasr around 3300 BCE, such as the one below.
The Sumerian writing system during the early periods was constantly in flux.
The original direction of writing was from top to bottom, but for reasons unknown,
it changed to left-to-right very early on (perhaps around 3000 BCE). This also
affected the orientation of the signs by rotating all of them 90°
counterclockwise. Another change in this early system involved the "style" of
the signs. The early signs were more "linear" in that the strokes making up
the signs were lines and curves. But starting after 3000 BCE these strokes
started to evolve into wedges, thus changing the visual style of the signs from
linear to "cuneiform".
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第二篇:The Commercial Revolution
机经版本一:
中世纪欧洲贸易。银币,后来人们使用新的贸易方式,信用记帐等,对资本主义产生
很大刺激。还讲了一个人从德国小镇开始的冒险之旅。
机经版本二:
第一方面:商业的发展带来了交通的发展。correspondence or transportation
第二方面:the transaction and mutual trust increase the development of credit
or acounting financial system
第三方面:promote the urbanization from rural characteristics
解析:历史题材是一个非常大的考点。对于这种类型文章不熟悉的同学,应该多做一
些该类型文章的精读训练,尽可能的抵消学科恐惧感。
相关背景知识:
The history of capitalism can be traced back to early forms of merchant
capitalism practiced in Western Europe during theMiddle Ages.[1] It began to
develop into its modern form during the Early Modern period in the Protestant
countries of North-Western Europe, especially the Netherlands and England.
Traders in Amsterdam and London created the first chartered joint-stock
companies driving up commerce and trade, and the first stock exchanges and
banking and insurance institutions were established.[2]
Over the course of the past five hundred years, capital has been accumulated
by a variety of different methods, in a variety of scales, and associated with
a great deal of variation in the concentration of economic power and wealth.[3]
Much of the history of the past five hundred years is concerned with the
development of capitalism in its various forms.
Crisis of the 14th century
According to some historians, the modern capitalist system has its origin in
the "crisis of the fourteenth century," a conflict between the land-owning
aristocracy and the agricultural producers, the serfs. Manorial arrangements
inhibited the development of capitalism in a number of ways. Because serfs were
forced to produce for lords, they had no interest in technological innovation;
because serfs produced to sustain their own families, they had no interest in
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co-operating with one another. Because lords owned the land, they relied on
force to guarantee that they were provided with sufficient food. Because lords
were not producing to sell on the market, there was no competitive pressure
for them to innovate. Finally, because lords expanded their power and wealth
through military means, they spent their wealth on military equipment or
onconspicuous consumption that helped foster alliances with other lords; they
had no incentive to invest in developing new productive technologies.[5]
This arrangement was shaken by the demographic crisis of the 14th century. This
crisis had several causes: agricultural productivity reached its technological
limitations and stopped growing; bad weather led to the Great Famine of 1315–
1317; the Black Death in 1348–1350 led to a population crash. These factors
led to a decline in agricultural production. In response feudal lords sought
to expand agricultural production by expanding their domains through warfare;
they therefore demanded more tribute from their serfs to pay for military
expenses. In England, many serfs rebelled. Some moved to towns, some purchased
land, and some entered into favorable contracts to rent lands from lords who
needed to repopulate their estates.[6]
The collapse of the manorial system in England created a class of tenant-farmers
with more freedom to market their goods and thus more incentive to invest in
new technologies. Lords who did not want to rely on rents could buy out or evict
tenant farmers, but then had to hire free-labor to work their estates – giving
them an incentive to invest in two very different kinds of commodity owners;
on the one hand, the owners of money, means of production, means of subsistence,
who are eager to valorize the sum of value they have appropriated by buying
the labour power of others; on the other hand, free workers, the sellers of
their own labor-power, and, Free workers, in the double sense that they neither
form part of the means of production nor do they own the means of production
that transformed land and even money into what we now call "capital."[7] Marx
labeled this period the "pre-history of capitalism".[8]
It was, in effect, feudalism that began to lay some of the foundations necessary
for the development of mercantilism, a precursor to capitalism. Feudalism took
place mostly in Europe and lasted from the medieval period up through the 16th
century. Feudal manors were almost entirely self-sufficient, and therefore
limited the role of the market. This stifled the growth of capitalism. However,
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the relatively sudden emergence of new technologies and discoveries,
particularly in the industries of agriculture[9] and exploration, revitalized
the growth of capitalism. The most important development at the end of Feudalism
was the emergence of "the dichotomy between wage earners and capitalist
merchants".[10] With mercantilism, the competitive nature means there are
always winners and losers, and this is clearly evident as feudalism transitions
into mercantilism, an economic system characterized by private or corporate
ownership of capital goods, by investments that are determined by private
decision, and by prices, production, and the distribution of goods that are
determined mainly by competition in a free market.
Rise of towns
The transition from the feudal organization of society to early forms of
capitalism happened in periods differing from country to country. According
to Cambridge political philosopher and historian Quentin Skinner, the towns
of North Italy were the first urbanised parts of Europe from the 12th century.
German bishop Otto of Freising recorded the growth of town life there, the
loyalty of landed nobility to town authorities, and the emergence of
republicanism and belief in civic liberty.[11]
Agrarian capitalism and enclosure
Decaying hedges mark the lines of the straight field boundaries created by a
Parliamentary Act of Enclosure.
England in the sixteenth century was already a centralized state, in which much
of the feudal order of Medieval Europe had been swept away. This centralization
was strengthened by a good system of roads and a disproportionately large
capital city,London. The capital acted as a central market hub for the entire
country, creating a very large internal market for goods, instead of the
fragmented feudal holdings that prevailed in most parts of the Continent. The
economic foundations of the agricultural system were also beginning to diverge
substantially; the manorial system had broken down by this time, and land began
to be concentrated in the hands of fewer landlords with increasingly large
estates. Instead of a serf-based system of labour, workers were being employed
as part of a broader and expanding money economy. The system put pressure on
both the landlords and the tenants to increase the productivity of the
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agriculture to make profit; the weakened coercive power of the aristocracy to
extract peasant surpluses encouraged them to try out better methods, and the
tenants also had incentive to improve their methods, in order to flourish in
an increasingly competitive labour market. Terms of rent for the land were
becoming subject to economic market forces rather than the previous stagnant
system of custom and feudal obligation.[12]
An important aspect of this process was the enclosure[13] of the common land
held in the open field system where peasants had traditional rights, such as
mowing meadows for hay and grazing livestock. Once enclosed, these uses of the
land became restricted to the owner, and it ceased to be land for commons. The
process of enclosure began to be a widespread feature of the English
agricultural landscape during the 16th century. By the 19th century, unenclosed
commons had become largely restricted to rough pasture in mountainous areas
and to relatively small parts of the lowlands.
Marxist and neo-Marxist historians argue that rich landowners used their
control of state processes to appropriate public land for their private benefit.
This created a landlessworking class that provided the labour required in the
new industries developing in the north of England. For example: "In agriculture
the years between 1760 and 1820 are the years of wholesale enclosure in which,
in village after village, common rights are lost".[14] "Enclosure (when all
the sophistications are allowed for) was a plain enough case of class
robbery".[15]
Other scholars[16] argue that the better-off members of the European peasantry
encouraged and participated actively in enclosure, seeking to end the perpetual
poverty ofsubsistence farming. "We should be careful not to ascribe to
[enclosure] developments that were the consequence of a much broader and more
complex process of historical change."[17] "[T]he impact of eighteenth and
nineteenth century enclosure has been grossly exaggerated...."
第三篇:The stability of ecosystem
机经版本一:生物多样性对整个生态圈的影响。讲了一个在明尼苏达的 grassland 实
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验,成为了 diversity 让 ecosystem stable 的 evidence。然后又开始老套路不
sufficient 啊还需要更多 research 啊 blablabla。很简单。
机经版本二: 主要讲 the relationship between diversity of species with the
stability of ecosystem. 主要表达了 the lost of one species can destroy the
entire system.
解析:这篇文章难度不大。主题是大家所熟悉的生物多样性。建议阅读相关 OG 文章:
The Long-Term Stability of Ecosystems.
背景资料:
Ecological effects of biodiversity
The diversity of species and genes in ecological communities affects the
functioning of these communities. These ecological effects of biodiversity in
turn affect both climate change through enhanced greenhouse gases, aerosols
and loss of land cover, and biological diversity, causing a rapid loss of
ecosystems and extinctions of species and local populations. The current rate
of extinction is sometimes considered a mass extinction, with current species
extinction rates on the order of 100 to 1000 times as high as in the past.
The two main areas where the effects of biodiversity on ecosystem function have
been studied are the relationship between diversity and productivity, and the
relationship between diversity and community stability. More biologically
diverse communities appear to be more productive (in terms of biomass production)
than are less diverse communities, and they appear to be more stable in the
face of perturbations. Also animals that inhabit an area may alter the surviving
conditions by factors assimilated by climate.
In order to understand the effects that changes in biodiversity will have on
ecosystem functioning, it is important to define some terms. Biodiversity is
not easily defined, but may be thought of as the number and/or evenness of genes,
species, and ecosystems in a region. This definition includes genetic diversity,
or the diversity of genes within a species, species diversity, or the diversity
of species within a habitat or region, and ecosystem diversity, or the diversity
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of habitats within a region.
Two things commonly measured in relation to changes in diversity are
productivity and stability. Productivity is a measure of ecosystem function.
It is generally measured by taking the total aboveground biomass of all plants
in an area. Many assume that it can be used as a general indicator of ecosystem
function and that total resource use and other indicators of ecosystem function
are correlated with productivity.
Stability is much more difficult to define, but can be generally thought of
in two ways. General stability of a population is a measure that assumes
stability is higher if there is less of a chance of extinction. This kind of
stability is generally measured by measuring the variability of aggregate
community properties, like total biomass, over time. The other definition of
stability is a measure of resilience and resistance, where an ecosystem that
returns quickly to an equilibrium after a perturbation or resists invasion is
thought of as more stable than one that doesn't.
Review of data
Field experiments to test the degree to which diversity affects community
productivity have had variable results, but many long term studies in grassland
ecosystems have found that diversity does indeed enhance the productivity of
ecosystems. Additionally, evidence of this relationship has also been found
in grassland microcosms. The differing results between studies may partially
be attributable to their reliance on samples with equal species diversities
rather than species diversities that mirror those observed in the environment.
A 2006 experiment utilizing a realistic variation in species composition for
its grassland samples found a positive correlation between increased diversity
and increased production.
However, these studies have come to different conclusions as to whether the
cause was due more to diversity or to species composition. Specifically, a
diversity in the functional roles of the species may be a more important quality
for predicting productivity than the diversity in species number. Recent
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mathematical models have highlighted the importance of ecological context in
unraveling this problem. Some models have indicated the importance of
disturbance rates and spatial heterogeneity of the environment, others have
indicated that the time since disturbance and the habitat's carrying capacity
can cause differing relationships. Each ecological context should yield not
only a different relationship, but a different contribution to the relationship
due to diversity and to composition. The current consensus holds at least that
certain combinations of species provide increased community productivity.
Future research
In order to correctly identify the consequences of diversity on productivity
and other ecosystem processes, many things must happen. First, it is imperative
that scientists stop looking for a single relationship. It is obvious now from
the models, the data, and the theory that there is no one overarching effect
of diversity on productivity. Scientists must try to quantify the differences
between composition effect and diversity effects, as many experiments never
quantify the final realized species diversity (instead only counting numbers
of species of seeds planted) and confound a sampling effect for facilitators
(a compositional factor) with diversity effects.
Relative amounts of overyielding (or how much more a species grows when grown
with other species than it does in monoculture) should be used rather than
absolute amounts as relative overyielding can give clues as to the mechanism
by which diversity is influencing productivity, however if experimental
protocols are incomplete, one may be able to indicate the existence of a
complementary or facilitative effect in the experiment, but not be able to
recognize its cause. Experimenters should know what the goal of their experiment
is, that is, whether it is meant to inform natural or managed ecosystems, as
the sampling effect may only be a real effect of diversity in natural ecosystems
(managed ecosystems are composed to maximize complementarity and facilitation
regardless of species number). By knowing this, they should be able to choose
spatial and temporal scales that are appropriate for their experiment. Lastly,
to resolve the diversity-function debate, it is advisable that experiments be
done with large amounts of spatial and resource heterogeneity and environmental
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fluctuation over time, as these types of experiments should be able to
demonstrate the diversity-function relationship more easily.
Biodiversity (Experiment E120)
Experiment 120 Data
Introduction
This experiment (often called the "Big" Biodiversity Experiment; the "small"
experiment is no longer maintained) determines effects of plant species numbers
and functional traits on community and ecosystem dynamics and functioning. It
manipulates the number of plant species in 168 plots, each 9 m x 9 m, by imposing
plant species numbers of 1, 2, 4, 8, or 16 perennial grassland species. The
species planted in a plot were randomly chosen from a pool of 18 species (4
species, each, of C4 grasses, C3 grasses, legumes, non-legume forbs; 2 species
of woody plants). Its high replication (about 35 plots at each level of diversity)
and large plots allow observation of responses of herbivorous, parasitoid and
predator insects and allow additional treatments to be nested within plots.
Planted in 1994, it has been annually sampled since 1996 for plant aboveground
biomass and plant species abundances and for insect diversity and species
abundances. Root mass, soil nitrate, light interception, biomass of invading
plant species, and C and N levels in soils, roots, and aboveground biomass have
been determined periodically. In addition, soil microbial processes and
abundances of mycorrhizal fungi, soil bacteria and other fungi, N
mineralization rates, patterns of N uptake by various species, and invading
plant species, have been periodically measured in subprojects in the
Biodiversity Experiment.
Key Results
Plant biomass production increased with diversity (Fig 1) because of
complementary interactions among species and not because of selection (sampling)
effects (Figs 2 Tilman et al. 2001b, Pacala and Tilman 2002, Hille Ris Lambers
et al. 2004; Fargione et al. in prep.).
Foliar fungal disease incidence decreased at higher diversity because of
greater distance between individuals of a species, and resultant lower rates
of disease spread (Mitchell et al. 2002).
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Greater plant diversity led to greater diversity of herbivorous insects, and
this effect continued up the food web to predator and parasitoid insects (Haddad
et al. 2001).
Fewer novel plant species invaded higher diversity treatments because of their
lower soil NO3 levels, greater neighborhood crowding and competition, and
greater chance that functionally similar species would occur in a given
neighborhood (Figs 3; Naeem et al. 2000, Kennedy et al. 2002, Fargione et al.
2003, Fargione and Tilman 2005a, 2005b).
Greater plant species numbers led to greater ecosystem stability (lower
year-to-year variation in total plant biomass) but to lower species stability
(greater year-to-year variation in abundances of individual species), with the
stabilizing effect of diversity mainly attributable to statistical averaging
effects and overyielding effects (Fig 4; Tilman et al, submitted).
Data gathered this past field season shows that soil total C has now become
an increasing function of plant species numbers (Fig 5).
Our results have helped resolve a debate about why plant diversity affects
ecosystem functioning. Such resolution was accomplished by a Paris symposium
in which we made CDR biodiversity data available so others could test their
alternative hypotheses; by a paper by 12 ecologists with divergent views that
explored areas of agreement and articulated areas in need of 10 further testing
(Loreau et al. 2001); and by our analyses of alternative hypotheses using
results of the CDR biodiversity experiment (Tilman et al. 2001b).
第二 套的词汇题:key, colossal, significant, radically, redundance
2014 年 4 月 19 日
第一篇:
2012.12.2ML 宇宙理论
版本 1:
一个 big bang theory,一个 ss theory。 Big bang 有 beginning,密度越来越小,ss
无 beginning 无 end,但有 creation matter, 密度不变。
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版本 2:宇宙的两个理论,一个说物质会变化但总量不变,一个是会膨胀,最后说一个
遥远的恒星的发现说明后一个理论更正确;
版本 3:讲的是 universe expanding 的两种理论,一个是 density 在变小。
另一种是 density 不变。因为不断 new creation 补充变大的空间,然后发现了
一种 q.它表明前一种理论更可信。
词汇:
expansion 膨胀
star 恒星
universe 宇宙
density 密度
creation 创造
space 空间
相关背景:
a. Big Bang
The Big Bang theory is the prevailing cosmological model for the early
development of the universe. According to the theory, the Big Bang occurred
approximately 13.82 billion years ago, which is thus considered the age of
the universe. At this time, the universe was in an extremely hot and dense
state and was expanding rapidly. After the initial expansion, the universe
cooled sufficiently to allow the formation of subatomic particles, including
protons, neutrons, and electrons. Though simple atomic nuclei formed within
the first three minutes after the Big Bang, thousands of years passed before
the first electrically neutral atoms formed. The majority of atoms that were
produced by the Big Bang are hydrogen, along with helium and traces of lithium.
Giant clouds of these primordial elements later coalesced through gravity
to form stars and galaxies, and the heavier elements were synthesized either
within stars or during supernovae.
b. The steady state universe theory
In cosmology, the Steady State theory is a now-obsolete theory and model
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alternative to the Big Bang theory of the universe's origin (the standard
cosmological model). In steady state views, new matter is continuously
created as the universe expands, thus adhering to the perfect cosmological
principle.
While the steady state model enjoyed some popularity in the first half of
the 20th century, it is now rejected by the vast majority of professional
cosmologists and other scientists, as the observational evidence points to
a Big Bang-type cosmology and a finite age of the universe.
c. Big Bang or Steady State?
Creation of the Elements
The 1930s was more a decade of consolidation than of revolutionary
advance in cosmology. And in the early 1940s, world war limited cosmological
advance. But the war that temporarily absorbed scientific resources also
promoted technologies that would lead to fundamental scientific advances.
Advances in nuclear physics helped transform cosmological speculations
into quantitative calculations. This line of investigation, begun in the late
1940s, was at first pursued mainly by physicists, not astronomers. In the
1930s Georges Lemaître had suggested that the universe might have originated
when a primeval "cosmic egg" exploded in a spectacular fireworks, creating
an expanding universe. Now physicists found plausible numbers for the cosmic
abundances of different elements that would be created in an initial cosmic
explosion. But the theory of an initial cosmic explosion was soon challenged
by a new hypothesis—that the universe might be in a steady state after all.
In 1946 the Ukrainian-born American physicist George Gamow considered
how the early stage of an expanding universe would be a superhot stew of
particles, and began to calculate what amounts of various chemical elements
might be created under these conditions. Gamow was joined by Ralph Alpher,
a graduate student at George Washington University, where Gamow taught, and
by Robert Herman, an employee at the Johns Hopkins Applied Physics Laboratory,
where Gamow consulted. Both Alpher and Herman were American-born sons of
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émigré Russian Jews.
Gamow assumed expansion and cooling of a universe from an initial state
of nearly infinite density and temperature. In that state all matter would
have been protons, neutrons, and electrons merging in an ocean of high energy
radiation. Gamow and Alpher called this hypothetical mixture "Ylem" (from
a medieval word for matter). Alpher made detailed calculations of nuclear
processes in this early universe. For his calculations he used some of the
first electronic digital computers—developed during the war for computing,
among other things, conditions inside a nuclear bomb blast. It seemed that
elements could be built up as a particle captured neutrons one by one, in
a sort of "nuclear cooking."
The contribution of this theory was not to set forth a final solution
but, no less important, to set forth a grand problem—what determined the
cosmic abundance of the elements? Could the observed abundances be matched
by calculations that applied the laws of physics to an early extremely hot
dense phase of an expanding universe? Gamow did succeed in explaining the
relative abundances of hydrogen and helium. Calculations roughly agreed with
observations of stars—helium accounted for about a quarter of the mass of
the universe and hydrogen accounted for nearly all the rest. However,
attempts to make calculations for other elements failed to get a sensible
answer for any element beyond helium. It seemed that piling more neutrons
onto helium would hardly ever get you stable elements. Gamow joked that his
theory should nevertheless be considered a success, since it did account for
99% of the matter in the universe.
Indeed his theory was not wrong but only incomplete. Astrophysicists soon
realized that if the heavier elements were not formed during the hot origin
of the universe, they might be formed later on, in the interiors of stars.
The theory depended on a special property of carbon, which British astronomer
Fred Hoyle measured and found as predicted. Cosmology had entered the
laboratory.
The Steady-State Theory
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Hoyle's triumph in explaining how most elements could be created in stellar
interiors fell outside the theory in which elements were created at the very
start. It was interpreted as favoring a rival theory. And Hoyle did favor
a rival theory, which he had played a large part in inventing and developing.
In this theory the universe had always looked much as it does now. There never
had been a "big bang"—a phrase that Hoyle invented in 1950, intending the
nickname as pejorative.
There is a charming story, not taken seriously by all historians, about how
steady state theory began. The idea came in 1947, Hoyle claimed, when he and
his fellow scientists Hermann Bondi and Tommy Gold went to a movie. The three
knew each other from shared research on radar during World War II. Hoyle was
versatile, undisciplined and intuitive; Bondi had a sharp and orderly
mathematical mind; Gold's daring physical imagination opened new
perspectives. The movie was a ghost story that ended the same way it started.
This got the three scientists thinking about a universe that was unchanging
yet dynamic. According to Hoyle, "One tends to think of unchanging situations
as being necessarily static. What the ghost-story film did sharply for all
three of us was to remove this wrong notion. One can have unchanging
situations that are dynamic, as for instance a smoothly flowing river." But
how could the universe always look the same if it was always expanding? It
did not take them long to see a possible answer—matter was continuously being
created. Thus new stars and galaxies could form to fill the space left behind
as the old ones moved apart. (You can read Gamow's verse about this idea here.)
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Drawings of an early and a later stage for two different models of an expanding
universe. The left model obeys the cosmological principle, according to which
the universe is homogenous and appears the same to an observer anywhere in
the universe. The right model obeys the perfect cosmological principle, which
adds to the cosmological principle the additional requirement that the
universe be unchanged over time—new galaxies emerge continually within the
expanding space.
To many philosophical minds, the steady-state universe proposed by Hoyle,
Bondi and Gold had a major advantage over the big-bang expanding universe.
In their universe the overall density was kept always the same by the
continuous creation of matter. In the big-bang universe with its radically
changing density, various physical laws might not apply the same way at all
times. It would be impossible to extrapolate with confidence from the present
back to the super-dense origin of the universe.
Steady-state theory also had an observational advantage over big-bang theory
in 1948. The rate of expansion then observed, when calculated backward to
an initial big bang, gave an age for the universe of only a few billion
years—well below the known age of the solar system! That was certainly an
embarrassment for the big bang theory.
For some time cosmologists had measured ideas against a "cosmological
principle," which asserted that the large-scale properties of the universe
are independent of the location of the observer. In other words, any theory
that put we humans at some special place (like the center of the universe)
could be rejected out of hand. Bondi and Gold insisted that the universe is
not only homogenous in space but also in time—it looks the same at any place
and at any time. They grandly called this the "perfect cosmological
principle," and insisted that theory should be deduced from the axiom that
we are not at any special place in either space or time.
Hoyle was less insistent that the perfect cosmological principle was a
fundamental axiom. He preferred to have theory follow from a modification
he proposed to Einstein's relativistic universe, adding the creation of
matter. The two different steady-state theories had enough in common, however,
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to be considered one for most purposes.
Much of the later development of steady-state theory came in response to
criticism. In Great Britain, especially, scientists gave considerable
attention to elaborating the theory. Their arguments were largely of a
philosophical nature, with little appeal to observation.
The cosmological debate acquired religious and political aspects. Pope
Pious XII announced in 1952 that big-bang cosmology affirmed the notion of
a transcendental creator and was in harmony with Christian dogma.
Steady-state theory, denying any beginning or end to time, was in some minds
loosely associated with atheism. Gamow even suggested steady-state theory
was attached to the Communist Party line, although in fact Soviet astronomers
rejected both steady-state and big-bang cosmologies as "idealistic" and
unsound. Hoyle himself associated steady state theory with personal freedom
and anti-communism.
Astronomers in the United States found the steady-state theory attractive,
but they took a pragmatic approach. The rival claims of big-bang and
steady-state theory must be settled by observational tests. One test involved
the ages of galaxies. In a steady state, with continuous creation of matter,
there would be a mixture of young and old galaxies throughout the universe.
In a big bang, with only an initial creation, galaxies would age with time.
And astronomers could look back in time by looking at more distant galaxies,
for observing a galaxy a billion light-years away meant seeing it in light
that had left it a billion years ago. Observations reported in 1948 purported
to find that more distant galaxies were indeed older. Score one for the big
bang. Bondi and Gold reviewed the data carefully, and in 1954 they showed
that the reported effect was spurious. Score one for steady state. The age
test might be able to distinguish between the rival theories in principle,
but in practice it could not.
Another possible test involved the rate of expansion of the universe. In
a big bang, the expansion rate would slow; in a steady state universe it would
remain constant. Data from the Mount Wilson Observatory seemed to favor the
big bang, but not certainly enough to constitute a crucial test.
Meanwhile there was a solution to the embarrassing calculation that put the
age of a big-bang universe less than the age of the solar system. Walter Baade
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showed that estimates of the distances to galaxies had mixed together two
different types of stars (as explained here). As a result, the size of the
universe had been underestimated by about a factor of two. If galaxies were
twice as distant as previously thought, then calculation with the observed
rate of expansion gave an age of the universe twice as great as previously
calculated — safely greater than the age of the solar system. That argument
against the big-bang universe thus dissolved.
The most serious challenge to steady-state theory came from the new science
of radio astronomy. Fundamental knowledge in the techniques of detecting
faint radio astronomy signals advanced greatly during World War II,
especially with research on radar and especially in England. After the war,
research programs at Cambridge, at Manchester, and at Sydney, Australia,
built radio telescopes to detect signals from outer space. They dominated
radio astronomy for the next decade.
The program at Cambridge was led by Martin Ryle, who in 1974 would receive
the Nobel Prize in physics for his overall contributions to radio astronomy.
In 1951 Ryle believed that radio sources were located within our galaxy, and
hence were of no cosmological interest. But over the next few years he became
convinced that most of the radio sources he was detecting were extragalactic.
His observations, then, could be used to test cosmological models. Ryle
argued that his survey of almost 2,000 radio sources, completed in 1955,
contradicted steady-state theory, because more distant/older sources seemed
to be distributed differently from nearby ones. But he overstated the
significance of his initial data. Only after more years of work would radio
observations argue strongly against steady-state theory.
第二篇:
版本一:水藻在海中的分布,作用以及影响水藻横纵分布的因素,主要讲一个颜色纵
向分布。
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版本二:Seaweeds,红 algae 深,绿 algae 浅。有个证据证明了红 algae 不能证明绿
algae。
相关背景:
Seaweed, any red, green, or brown marine algae that grow on seashores. They
are anchored to the sea bottom or to some solid structure by rootlike holdfasts
that perform the sole function of attachment and do not extract nutrients as
do the roots of higher plants.
Seaweeds often form dense growths on rocky shores or accumulations in shallow
water. Many show a well-established zonation along the margins of the seas,
where the depth of the water is 50 metres (about 165 feet) or less. The types
of seaweed growing near the high-water mark, where plants are often exposed
to air, differ from those growing at lower levels, where there is little or
no exposure. Fucus, Macrocystis, Nereocystis, and Laminaria are widely
distributed in colder zones and are absent from tropical waters.
Brown algae commonly found as seaweeds include kelps and Fucus. Among the
kelps are the largest algae; certain species of Macrocystis and Nereocystis of
the Pacific and Antarctic regions exceed 33 metres (100 feet) in
length. Laminaria, another kelp, is abundant along both Pacific and Atlantic
coasts. Gulfweed (Sargassum;) is common as free-floating masses in the Gulf
Stream and the Sargasso Sea.
Red alga seaweeds include dulse (Rhodymenia), Gelidium,
Chondrus, and laver (Porphyra). Various species of Chondrus (see Irish moss)
carpet the lower half of the zone exposed at low tide along rocky coasts of
the Atlantic.
Ulva species, commonly called sea lettuce, are among the relatively few green
algal seaweeds.
Structure
Seaweeds' appearance somewhat resembles non-arboreal terrestrial plants.

thallus: the algal body
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
lamina or blade: a flattened structure that is somewhat leaf-like

sorus: a spore cluster

on Fucus, air bladder: a floatation-assisting organ on the blade

on kelp, float: a floatation-assisting organ between the lamina and
stipe

stipe: a stem-like structure, may be absent

holdfast: a specialized basal structure providing attachment to a surface,
often a rock or another alga

haptera: a finger-like extension of the holdfast anchoring to a benthic
substrate
The stipe and blade are collectively known as the frond.
Ecology
Two specific environmental requirements dominate seaweed ecology. These are
the presence of seawater (or at least brackish water) and the presence of light
sufficient to drive photosynthesis. Another common requirement is a firm
attachment point. As a result, seaweeds most commonly inhabit the littoral zone
and within that zone more frequently on rocky shores than on sand or shingle.
Seaweeds occupy a wide range of ecological niches. The highest elevation is
only wetted by the tops of sea spray, the lowest is several meters deep. In
some areas, littoral seaweeds can extend several miles out to sea. The limiting
factor in such cases is sunlight availability. The deepest living seaweeds are
some species of red algae.
A number of species such as Sargassum have adapted to a fully planktonic niche
and are free-floating, depending on gas-filled sacs to maintain an acceptable
depth.
Others have adapted to live in tidal rock pools. In this habitat seaweeds must
withstand rapidly changing temperature andsalinity and even occasional drying.
附:本篇相关机经:Characteristics of seaweed plants
海草
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第一段大概就在说这个海里面的东东和陆地植物有点不一样,但还是有叶绿素的,貌
似还有其他神马的。
。
第二段有图, 就讲这些东东要领队在在诸如石头啊什么的东西上面。说他们的类似于
stem 一类的东西可以达到 35metres,(这里有题)还说因为这种植物不需要通过根部
transportation,从 ground 里面吸收营养和水分,所以这个根部 roots 和一般的陆地
植物根部不一样的(有题,问为什么他们不一样,有个选项是:因为他们不需要像 leaves
一样有运送水分和营养的功能,还有个选项说这个植物不需要 ground 的水分和营养)。
。
第三段讲如果植物遇到 storm 的话,他们貌似会抓得更紧(有题:问遇到 storm 的时
候这个哪门)。然后又讲说这个植物在某种情况下会 die。
第四段说这个植物在海里的情况,说有三种颜色:green, blue, 和 red。说是按深浅
来的,只要在某 Z 的区域内,阳光都能照到,然后都可以活。
第五段讲这种植物可以给很多生物提供 shelter。然后可以作为很多动物的 food,还
有一个功能,我也记不清了。然后下面有一道题问下列哪个不是这个植物可以为其他
生物做的(有个选项貌似说是提供 construction materials。我就选的这个。)
题目:
海草为什么会被 植物学家特别划分出来?因为它有叶绿素会进行光合作用;
为什么 storm 有可能造成海草死亡,因为它的根脱落。
海草跟陆上植物叶子或根作用有何不同?海草的叶子不储存水分(不确定)。
海草的根不吸收水份及营养。
第三篇:
版本一:第三篇是鸟类的集群效应,他们怎么通过集群来保护自己的子嗣和其他的一
些集体行为
版本二:Bird colony,提到 parasite, cap 鸟...
版本三:鸟把巢建在一起
有很多好处,例如某种鸟这样做的很成功:
1. 巢群建在岛上乱石中,防止哺乳动物来吃
2. 天敌来袭时集体抗争
3. 废弃的巢和在用的巢建在一起,以假乱真。还有利于后代存活,后代们一起被孵化,
超过了天敌的需求,因此得以保存,还可以互相照看孩子。例如有种美洲的燕子,頟
自到不同地方找食物,找不到的回来跟着找到的去,实现了信息共享。也有弊端,巢
群外沿易受攻击,所以大家都往里面建巢,所以中心很拥挤,食物消耗也大,容易滋
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生寄生虫和疾病。
相关背景:
Bird colony
A bird colony is a large congregation of individuals of one or more species
of bird that nest or roost in proximity at a particular location. Many kinds
of birds are known to congregate in groups of varying size; a congregation of
nesting birds is called a breeding colony. Colonial nesting birds include
seabirds such as auks and albatrosses; wetland species such as herons; and a
few passerines such as weaverbirds, certain blackbirds, and some swallows. A
group of birds congregating for rest is called a communal roost. Evidence of
colonial nesting has been found in non-neornithine birds (Enantiornithes), in
sediments from the Late Cretaceous (Maastrichtian) of Romania.
Ecological functions
The habit of nesting in groups is believed to provide better survival against
predators in several ways. Many colonies are situated in locations that are
naturally free of predators. In other cases, the presence of many birds means
there are more individuals available for defense. Also, synchronized breeding
leads to such an abundance of offspring as to satiate predators.
For seabirds, colonies on islands have an obvious advantage over mainland
colonies when it comes to protection from terrestrial predators. Other
situations can also be found where bird colonies avoid predation. A study of
Yellow-rumped Caciques in Peru found that the birds, which build enclosed,
pouch-like nests in colonies of up to one hundred active nests, situate
themselves near wasp nests, which provide some protection from tree-dwelling
predators such as monkeys. When other birds came to rob the nests, the caciques
would cooperatively defend the colony by mobbing the invader. Mobbing, clearly
a group effort, is well-known behavior, not limited to colonial species; the
more birds participating in the mobbing, the more effective it is at driving
off the predator. Therefore, it has been theorized that the larger number of
individuals available for vigilance and defense makes the colony a safer place
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for the individual birds nesting there. More pairs of eyes and ears are available
to raise the alarm and rise to the occasion.
Another suggestion is that colonies act as information centers and birds that
have not found good foraging sites are able to follow others, who have fared
better, to find food. This makes sense for foragers because the food source
is one that can be locally abundant. This hypothesis would explain why the Lesser
Kestrel, which feeds on insects, breeds in colonies, while the related Common
Kestrel, which feeds on larger prey, is not.
Colonial behavior has its costs as well. It has been noted that parasitism by
haematozoa is higher in colonial birds and it has been suggested that blood
parasites might have shaped adaptations such as larger organs in the immune
system and life-history traits. Other costs include brood parasitism and
competition for food and territory. Colony size is a factor in the ecological
function of colony nesting. In a larger colony, increased competition for food
can make it harder for parents to feed their chicks.
The benefits and drawbacks for birds of nesting in groups seem to be highly
situational. Although scientists have hypothesized about the advantages of
group nesting in terms of enabling group defensive behavior, escape from
predation by being surrounded by neighbors (called the selfish herd hypothesis),
as well as escaping predators through sheer numbers, in reality, each of these
functions evidently depends on a number of factors. Clearly, there can be safety
in numbers, but there is some doubt about whether it balances out against the
tendency for conspicuous breeding colonies to attract predators, and some
suggest that colonial breeding can actually make birds more vulnerable. At a
Common Tern colony in Minnesota, a study of Spotted Sandpipers observed to nest
near the tern colony showed that the sandpipers that nested nearest the colony
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seemed to gain some protection from mammalian predators, but avian predators
were apparently attracted to the colony and the sandpipers nesting there were
actually more vulnerable. In a study of a Least Tern colony in Connecticut,
nocturnal avian predators in the form of Black-crowned Night Herons and Great
Horned Owls were observed to repeatedly invade a colony, flying into the middle
of the colony and meeting no resistance.
For seabirds, the location of colonies on islands, which are inaccessible to
terrestrial predators, is an obvious advantage. Islands where terrestrial
predators have arrived in the form of rats, cats, foxes, etc., have devastated
island seabird colonies. One well-studied case of this phenomenon has been the
effect on Common Murre colonies on islands in Alaska, where foxes were
introduced for fur farming
2014 年 4 月 27 日
第一篇
版本一:
19 世纪美国城市发展。全文讲了几个原因及其影响!主要有交通运输发展,经济发展,
domes 什么影响
版本二:
美国的城市规划。第二段有讲到 Washington DC
版本三:
关于美国的“urban planning”的政策,对人们生活的影响的好与坏
解析:
重复 2011 年 11 月 26 日题,涉及到美国 19 世纪美国城镇发展的三个因素,economic,
demographic 和 transportation,还涉及到人们进城打工等因素,后文分别讨论三种
因素发挥的作用以及城市化带来的影响,本文是原因和影响混合型文章。因果型文章
结构在托福中非常常见,学生在阅读的时候重点要关注原因或影响是什么,以及原因
是如何发挥作用,影响体现在什么方面等,最后一题一般都直接对应原因或影响。
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近几年的托福考试中,城市化话题涉及到建设、发展和特点,考到伦敦、芝加哥、日
本、法国和中国等,但是,话题重复意味着词汇的重复,建议学生在备考中积累学科
词汇,提升英语实力,以不变应万变。
参考阅读:
Urbanization occurs as individual, commercial, social and governmental efforts
reduce time and expense in commuting and transportation and improve
opportunities for jobs, education, housing, and transportation. Living in
cities permits the advantages of the opportunities of proximity, diversity,
and marketplace competition. However, the advantages of urbanization are
weighed against alienation issues, stress, increased daily life costs, and
negative social aspects that result from mass marginalization.
Cities are known to be places where money, services, wealth and opportunities
are centralized. Many rural inhabitants come to the city for reasons of seeking
fortunes and social mobility. Businesses, which provide jobs and exchange
capital are more concentrated in urban areas. Whether the source is trade or
tourism, it is also through the ports or banking systems that foreign money
flows into a country, commonly located in cities.
Economic opportunities are just one reason people move into cities, though they
do not go to fully explain why urbanization rates have exploded only recently
in places like China and India. Rural flight is a contributing factor to
urbanization. In rural areas, often on small family farms or collective farms
in villages, it has traditionally been difficult to access manufactured goods,
though overall quality of life is very subjective, and may certainly surpass
that of the city. Farm living has always been susceptible to unpredictable
environmental conditions, and in times of drought, flood or pestilence,
survival may become extremely problematic.
Cities offer a larger variety of services, such as specialist services that
aren't found in rural areas. Supporting the provision of these services requires
workers, resulting in more numerous and varied job opportunities. Elderly
individuals may be forced to move to cities where there are doctors and hospitals
that can cater for their health needs. Varied and high quality educational
opportunities are another factor in urban migration, as well as the opportunity
to join, develop, and seek out social communities.
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Urbanization can be planned urbanization or organic. Planned urbanization, i.e.:
planned community or the garden city movement, is based on an advance plan,
which can be prepared for military, aesthetic, economic or urban design reasons.
Examples can be seen in many ancient cities; although with exploration came
the collision of nations, which meant that many invaded cities took on the
desired planned characteristics of their occupiers. Many ancient organic cities
experienced redevelopment for military and economic purposes, new roads carved
through the cities, and new parcels of land were cordoned off serving various
planned purposes giving cities distinctive geometric designs. UN agencies
prefer to see urban infrastructure installed before urbanization occurs.
Landscape planners are responsible for landscape infrastructure (public parks,
sustainable urban drainage systems, greenways etc.)which can be planned before
urbanization takes place, or afterward to revitalize an area and create greater
livability within a region. Concepts of control of the urban expansion are
considered in the American Institute of Planners.
第二篇
版本一:
讲的是日本气候,主要有三种类型从日本海下来的东部风对日本北部农业影响,主要
有农作物种植时间变短,不利于种植,都跑到南部去种植,导致了 agricultural risk
还有就是从南部来的风最后一个是来自太平洋的风
版本二:
日本的气候 讲了西伯利亚冷空气和哪里来的空气造成了日本气候循环,很多降雨使得
很多洪涝,有的地方适合耕种,还有一种 effect 就是说会让气温降低到粮食可成熟的
温度之下造成粮食缩减„„
解析:
本文涉及到日本气候及其影响,疑似重复 2013 年 01 月 26 日及 2013 年 03 月 30 日阅
读,背景知识与高中地理重复较大,所以理解难度降低,学生需要避免的是在解题时
过度使用背景知识,而应该依据文章给到的内容来判断选项。
参考阅读:
Japan is generally a rainy country with high humidity. Because of its wide range
of latitude, Japan has a variety of climates, with a range often compared to
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that of the east coast of North America, from Nova Scotia to Georgia. Tokyo
is at about 36 north latitude, comparable to that of Tehran, Athens, or Los
Angeles. The generally humid, temperate climate exhibits marked seasonal
variation celebrated in art and literature, as well as regional variations
ranging from cool in Hokkaido to subtropical in Kyushu. Climate also varies
with altitude and with location on the Pacific Ocean or on the Sea of Japan.
Northern Japan has warm summers but long, cold winters with heavy snow. Central
Japan has hot, humid summers and short winters, and southwestern Japan has long,
hot, humid summers and mild winters.
Two primary factors influence Japan's climate: a location near the Asian
continent and the existence of major oceanic currents. The climate from June
to September is marked by hot, wet weather brought by tropical airflows from
the Pacific Ocean and Southeast Asia. These airflows are full of moisture and
deposit substantial amounts of rain when they reach land. There is a marked
rainy season, beginning in early June and continuing for about a month. It is
followed by hot, sticky weather. Five or six typhoons pass over or near Japan
every year from early August to early September, sometimes resulting in
significant damage. Annual precipitation, which averages between 100 and 200
centimeters, is concentrated in the period between June and September. In fact,
70 to 80 percent of the annual precipitation falls during this period. In winter,
a high-pressure area develops over Siberia, and a low-pressure area develops
over the northern Pacific Ocean. The result is a flow of cold air eastward across
Japan that brings freezing temperatures and heavy snowfalls to the central
mountain ranges facing the Sea of Japan, but clear skies to areas fronting on
the Pacific.
Two major ocean currents affect this climatic pattern: the warm Kuroshio Current
(Black Current; also known as the Japan Current); and the cold Oyashio Current
(Parent Current; also known as the Okhotsk Current). The Kuroshio Current flows
northward on the Pacific side of Japan and warms areas as far north as Tokyo;
a small branch, the Tsushima Current, flows up the Sea of Japan side. The Oyashio
Current, which abounds in plankton beneficial to coldwater fish, flows
southward along the northern Pacific, cooling adjacent coastal areas. The
meeting point of these currents at 36 north latitude is a bountiful fishing
ground.
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第三篇
版本一:
14 世纪欧洲城市的发展(原谅我的记忆力全部沉浸在听力的悲伤中)!有几个原因,
climate 改变,人口激增不能满足食物的供应,政治因素导致农民失去土地,最后是说
农民的居民都跑到城市来找工作了导致城市变大
版本二:
欧洲 19 世纪经济锐减的原因。气候变冷,新上位的政府切断了本来和亚洲贸易的路线,
还有一点好像是很多租地的农民因为气温下降没有更多的钱付租金 然后负债,然后说
很多国家当时都负债累累,举了英国两大银行为例。其他记不清了
版本三:
欧洲 14 世纪的经济危机(由于气候变化对农业有很大影响倒是对经济的 adverse
effect)
解析:
本文涉及到 14 世纪欧洲经济危机,疑似重复 20121019NA 题,主要内容涉及到欧洲经
济危机产生的原因,同第一篇,还是因果型文章,在阅读时重点关注原因是什么以及
如何发挥作用的。
参考阅读:
Some scholars contend that at the beginning of the 14th century, Europe had
become overpopulated. By the 14th century frontiers had ceased to expand and
internal colonization was coming to an end, but population levels remained high.
The Medieval Warm Period ended sometime towards the end of the 13th century,
bringing the "Little Ice Age" and harsher winters with reduced harvests. In
Northern Europe, new technological innovations such as the heavy plough and
the three-field system were not as effective in clearing new fields for harvest
as they were in the Mediterranean because the north had poor, clay-like soil.[8]
Food shortages and rapidly inflating prices were a fact of life for as much
as a century before the plague. Wheat, oats, hay and consequently livestock,
were all in short supply. Their scarcity resulted in malnutrition, which
increases susceptibility to infections due to weakened immunity. In the autumn
of 1314, heavy rains began to fall, which were the start of several years of
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cold and wet winters.[8] The already weak harvests of the north suffered and
the seven-year famine ensued. In the years 1315 to 1317 a catastrophic famine,
known as the Great Famine, struck much of North West Europe. It was arguably
the worst in European history, perhaps reducing the population by more than
10%.
Most governments instituted measures that prohibited exports of foodstuffs,
condemned black market speculators, set price controls on grain and outlawed
large-scale fishing. At best, they proved mostly unenforceable and at worst
they contributed to a continent-wide downward spiral. The hardest hit lands,
like England, were unable to buy grain abroad: from France because of the
prohibition, and from most of the rest of the grain producers because of crop
failures from shortage of labour. Any grain that could be shipped was eventually
taken by pirates or looters to be sold on the black market. Meanwhile, many
of the largest countries, most notably England and Scotland, had been at war,
using up much of their treasury and exacerbating inflation. In 1337, on the
eve of the first wave of the Black Death, England and France went to war in
what became known as the Hundred Years' War. This situation was worsened when
landowners and monarchs such as Edward III of England (r. 1327–1377) and Philip
VI of France (r. 1328–1350), raised the fines and rents of their tenants out
of a fear that their comparatively high standard of living would decline.
The European economy entered a vicious circle in which hunger and chronic,
low-level debilitating disease reduced the productivity of labourers, and so
the grain output was reduced, causing grain prices to increase. Standards of
living fell drastically, diets grew more limited, and Europeans as a whole
experienced more health problems.
When a typhoid epidemic emerged, many thousands died in populated urban centres,
most significantly Ypres (now in Belgium). In 1318 a pestilence of unknown
origin, sometimes identified as anthrax, targeted the animals of Europe,
notably sheep and cattle, further reducing the food supply and income of the
peasantry.
词汇题
striking
considerable-significantly
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cluster-group
account for-explain
plague-cause trouble
abrupt-sudden
susceptible
exceedingly
2014 年 5 月 17 日
第一篇:动物迁徙
版本 1:
第一篇讲动物迁徙,根据 cognitive map,举了几个例子。一种灰鲸靠海岸
线,还有一种 monarch butterfly,在夏季的迁徙地产卵并死去,其后代直接飞回来。
还有就是靠太阳或者月亮,还讲了鸽子迁徙靠地磁。
版本 2:说鸟有不同的导航方式,然后有的鸟用 sun,有的用 star,用 star 的鸟就有
不同的生物钟,因为他们不需要配合太阳的变化。还有一些鸟的体内有铁元素,他们
可以用来导航。
版本 3: 文章主题是动物如何在迁移中判断方向的。作者举了一个灰鲸的例子,它们
会利用海岸线的形状来判断迁徙的方向。还举了帝皇蝶的例子。还有的用内在的基因
程序。
词汇:animal migration 动物迁徙
cognitive map
认知地图
genetic programme 基因程序
monarch butterfly 黑脉金斑蝶、帝王蝶
解析:本文围绕动物在迁徙的过程中依靠什么来进行定位为主题展开论证。文章举了
关于动物迁徙的例子包括鸟、蝴蝶和鲸,具体描述对应的动物是如何依靠海岸线的形
状、太阳与星星等等为标志物在迁徙的过程中判断方向的。从以往的经验看,关于以
动物行为为背景的文章考查的频率非常高。同学们备考的时候需要准备一些与动物行
为相关的背景词汇,这样在阅读的过程中可以降低由于词汇不熟悉产生的时间浪费。
TPO 中 , 与 本 文 在 题 材 与 结 构 都 非 常 相 似 的 文 章 是 TPO11 的 Orientation and
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Navigation。
相关背景:
Animal migration
Mexican free-tailed bats on their long aerial migration
Animal migration is the relatively long-distance movement of individuals,
usually on a seasonal basis. It is found in all major animal groups,
including birds, mammals, fish, reptiles, amphibians, insects,
and crustaceans.[1] The trigger for the migration may be local climate, local
availability of food, the season of the year or for mating reasons.[2] To be
counted as a true migration, and not just a local dispersal or irruption, the
movement of the animals should be an annual or seasonal occurrence, such
as birds migrating south for the winter; wildebeest migrating annually for
seasonal grazing; or a major habitat change as part of their life, such as
young Atlantic salmon leaving the river of their birth when they have reached
a few inches in size.[3]
Definition[edit]
Migration can take very different forms in different species and as such, there
is no simple accepted definition of migration. One of the most commonly used
definitions, proposed by Kennedy[4] is
Migratory behavior is persistent and straightened out movement effected by the
animal’s own locomotory exertions or by its active embarkation upon a vehicle.
It depends on some temporary inhibition of station keeping responses but
promotes their eventual disinhibition and recurrence.
Migration has also been described as a term that describes the four related
concepts:[1]
persistent, straight, movement behavior
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relocation of an individual on a greater scale (both spatially and temporally)
than its normal daily activities
seasonal ‘to-and-fro’ movement of a population between two areas
movement leading to the redistribution of individuals within a population
Migration Types[edit]
A Christmas Island red crab on its migration.
Migration
can
be
either obligate,
meaning
individuals
must
migrate,
or facultative, meaning individuals can choose to migrate or not.
Within a migratory species or even within a single population, often not all
individuals
migrate. Complete
migration is
when
all
individuals
migrate, partial migration is when some individuals migrate while others do
not, and differential migration is when the difference between migratory and
non-migratory individuals is based on age or sex (for example).[1]
While most migratory movements occur on an annual cycle, some daily movements
are also referred to as migration. For example, many aquatic animals make a
vertical migration (Diel vertical migration), travelling a few hundred metres
up and down the water column.[5]Similarly, some jellyfish make daily horizontal
migrations, traveling a few hundred metres across a lake.[6]
Irregular (non-cyclical) migrations such as irruptions can occur under
pressure of famine, overpopulation of a locality, or some more obscure
influence.[7]
Multiple generation migration[edit]
Further information: Lepidoptera migration
In some insect species, such as the monarch butterfly and the painted lady
butterfly, the whole migration is not carried out by one individual. Instead
the butterflies mate and reproduce on the journey, and successive generations
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travel the next stage of the migration.[8]
In culture[edit]
Before the phenomenon of animal migration was understood, various folklore and
erroneous explanations sprang up to account for the disappearance or sudden
arrival of birds in an area. In Ancient Greece, Aristotle proposed that robins
turned into redstarts when summer arrived.[9] The barnacle goose was explained
in European Medieval bestiaries and manuscripts as either growing like fruit
on
trees,
or
developing
from goose
barnacles on
pieces
of
driftwood.[10] Another example is the swallow, which at various times was
suggested to hibernate either underwater, buried in muddy riverbanks, or in
hollow trees.
第二篇:针孔摄像机
版本一:第二篇是讲摄影暗盒技术 obscura,一个叫 hockney 的英国当代画家研究了
400 个画家来证明中世纪的人用暗盒来辅助画画,以维米尔为例子。讲了他的画如何被
认为是使用了该技术,后面提到了一些画家都使用过,还总结了一幅画中使用了该技
术的特征,最后说了这个技术并不能抹杀画家本身的实力。
版本二:一开始说了相机成的像是倒置的(标题旁边图 类似小孔成像)。后面通过实
验研究发现用镜子可以改变倒置的像。接着说了对艺术家的影响,具体举了一个画家
的例子,说他的画可能就是受了相机的影响。但是由于没有对此的记录,作者觉得大
概是这个画家不想让大家知道他受了相机的影响。接着又说到了很多画家也可能受到
了相机的影响。最后一段说即使相机出现 但是画家还是要有自己在画画上的造诣 并
把这些与相机的特点结合起来。
版本三: 有些画家没节操,用小孔成像技术画画还不让别人知道,然后他举了个例子
说有个荷兰的画家,叫 VIE 神马的(达芬奇?),画画不让人家看也不收徒弟,可能就
是因为它利用了这个技术。不过作者后来又说,其实有时候这个技术没啥用,因为最
后还得看个人。
词汇:camera obscura n.针孔摄像机
解析:本文围绕针孔摄像机的发明对于油画艺术的主要影响主题为展开论证。文章从
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三个角度切入,探讨针孔摄像机对于油画艺术的影响,这三个角度恰恰是最后一题文
章总结题的三个答案。每个观点独立成段且每段有清晰的主题句的可能性非常大。TPO
中,与本文在题材与结构都非常相似的文章是 TPO22 的 The Birth of Photography.
这篇文章的第二段第二句提到了 camera obscura。
相关背景:
Camera obscura
This article is about an optical device. For other uses, see Camera obscura
(disambiguation).
A drawing of a camera obscura
Camerae
obscurae
forDaguerreotype called
"Grand
by Charles Chevalier (Musée des Arts et Métiers)
Photographe"
produced
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A projection of an image of the New Royal Palace in Prague Castlecreated with
a camera obscura
The camera obscura (Latin; camera for "vaulted chamber/room", obscura for
"dark", together "darkened chamber/room"; plural: camera obscuras or camerae
obscurae) is an optical device that projects an image of its surroundings on
a screen. It is used in drawing and for entertainment, and was one of the
inventions that led to photography and the camera. The device consists of a
box or room with a hole in one side. Light from an external scene passes through
the hole and strikes a surface inside, where it is reproduced, rotated 180
degrees (thus upside-down), but with color and perspective preserved. The
image can be projected onto paper, and can then be traced to produce a highly
accurate representation.The largest camera obscura in the world is on
Constitution Hill in Aberystwyth, Wales.[1]
Using mirrors, as in the 18th-century overhead version (illustrated in
the History section below), it is possible to project a right-side-up image.
Another more portable type is a box with an angled mirror projecting
onto tracing paper placed on the glass top, the image being upright as viewed
from the back.
As the pinhole is made smaller, the image gets sharper, but the projected image
becomes dimmer. With too small a pinhole, however, the sharpness worsens, due
to diffraction. Some practical camera obscuras use a lens rather than a pinhole
because it allows a largeraperture, giving a usable brightness while
maintaining focus. (See pinhole camera for construction information.)
History[edit]
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Camera obscura in Encyclopédie, ou dictionnaire raisonné des sciences, des arts
et des métiers
The camera obscura has been known to scholars since the time
of Mozi and Aristotle.[2] The first surviving mention of the principles behind
the pinhole camera or camera obscura belongs to Mozi (470 to 390 BCE), a Chinese
philosopher and the founder of Mohism. Mozi correctly asserted that the image
in a camera obscura is flipped upside down because light travels in straight
lines from its source. His disciples developed this into a minor theory
of optics.[3][note 1]
The Greek philosopher Aristotle (384 to 322 BCE) understood the optical
principle of the pinhole camera.[4] He viewed the crescent shape of a partially
eclipsed sun projected on the ground through the holes in a sieve and through
the gaps between the leaves of a plane tree. In the 4th century
BCE, Aristotle noted that "sunlight travelling through small openings between
the leaves of a tree, the holes of a sieve, the openings wickerwork, and even
interlaced fingers will create circular patches of light on the
ground." Euclid's Optics(ca 300 BCE) presupposed the camera obscura as a
demonstration
that
light
travels
in
straight
lines.[5] In
the
4th
century, Greekscholar Theon of Alexandria observed that "candlelight passing
through a pinhole will create an illuminated spot on a screen that is directly
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in line with the aperture and the center of the candle."
In the 6th century, the Byzantine-Greek mathematician and architect Anthemius
of Tralles (most famous for designing the Hagia Sophia), used a type of camera
obscura in his experiments.[6]
In the 9th century, Al-Kindi (Alkindus) demonstrated that "light from the right
side of the flame will pass through the aperture and end up on the left side
of the screen, while light from the left side of the flame will pass through
the aperture and end up on the right side of the screen."
Alhazen (Ibn al-Haytham) also gave the first clear description[7] and early
analysis[8] and invented the camera obscura and pinhole camera. While
Aristotle, Theon
of
Alexandria, Al-Kindi (Alkindus)
and Chinese
philosopher Mozi had earlier described the effects of a single light passing
through a pinhole, none of them suggested that what is being projected onto
the screen is an image of everything on the other side of the aperture. Alhazen
was the first to demonstrate this with his lamp experiment where several
different light sources are arranged across a large area. He was thus the first
to successfully project an entire image from outdoors onto a screen indoors
with the camera obscura.
The Song Dynasty Chinese scientist Shen Kuo (1031–1095) experimented with a
camera
obscura,
and
was
the
first
to
apply geometrical andquantitative attributes to it in his book of 1088 AD,
the Dream Pool Essays.[9][verification needed] However, Shen Kuo alluded to
the fact that the Miscellaneous Morsels from Youyang written in about 840 AD
by Duan Chengshi (d. 863) during the Tang Dynasty (618–907) mentioned
inverting the image of a Chinese pagoda tower beside a seashore.[9] In fact,
Shen makes no assertion that he was the first to experiment with such a
device.[9] Shen wrote of Cheng's book: "[Miscellaneous Morsels from Youyang]
said that the image of the pagoda is inverted because it is beside the sea,
and that the sea has that effect. This is nonsense. It is a normal principle
that the image is inverted after passing through the small hole."[9]
In 13th-century England, Roger Bacon described the use of a camera obscura for
the safe observation of solar eclipses.[10] At the end of the 13th
century, Arnaldus de Villa Nova is credited with using a camera obscura to
project live performances for entertainment.[11] [12] Its potential as a
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drawing aid may have been familiar to artists by as early as the 15th
century; Leonardo da Vinci (1452–1519 AD) described the camera obscura
in Codex Atlanticus. Johann Zahn's "Oculus Artificialis Teledioptricus Sive
Telescopium, which was published in 1685, contains many descriptions and
diagrams, illustrations and sketches of both the camera obscura and of the magic
lantern.
Giambattista della Porta is said to have perfected camera obscura. He described
it as having a convex lens in later editions of his Magia Naturalis (1558-1589),
the popularity of which helped spread knowledge of it. He compared the shape
of the human eye to the lens in his camera obscura, and provided an easily
understandable example of how light could bring images into the eye. One chapter
in the Conte Algarotti's Saggio sopra Pittura (1764) is dedicated to the use
of a camera ottica ("optic chamber") in painting.[13]
Camera obscura, from a manuscript of military designs. 17th century, possibly
Italian.
The 17th century Dutch Masters, such as Johannes Vermeer, were known for their
magnificent attention to detail. It has been widely speculated that they made
use of such a camera, but the extent of their use by artists at this period
remains a matter of considerable controversy, recently revived by the Hockney–
Falco thesis.
The
term
"camera
obscura"
itself
was
first
used
by
the
German
astronomer Johannes Kepler in 1604.[14] The English physician and author
Sir Thomas Browne speculated upon the interrelated workings of optics and the
camera obscura in his 1658 discourse The Garden of Cyrus thus:
For at the eye the Pyramidal rayes from the object, receive a decussation, and
so strike a second base upon the Retina or hinder coat, the proper organ of
Vision; wherein the pictures from objects are represented, answerable to the
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paper, or wall in the dark chamber; after the decussation of the rayes at the
hole of the hornycoat, and their refraction upon the Christalline humour,
answering the foramen of the window, and the convex or burning-glasses, which
refract the rayes that enter it.
Four drawings by Canaletto, representing Campo San Giovanni e Paolo in Venice,
obtained with a camera obscura (Venice, Gallerie dell'Accademia)
Early models were large; comprising either a whole darkened room or a tent (as
employed by Johannes Kepler). By the 18th century, following developments
by Robert Boyle and Robert Hooke, more easily portable models became available.
These were extensively used by amateur artists while on their travels, but they
were
also
employed
by
professionals,
including Paul
Sandby, Canaletto and Joshua Reynolds, whose camera (disguised as a book) is
now in the Science Museum (London). Such cameras were later adapted by Joseph
Nicephore Niepce, Louis Daguerre and William Fox Talbot for creating the first
photographs.
第三篇:栖息地选择
版本一:一个叫 Sale 的科学家总结总结出了栖息地的寻找和选择是因为多种 cue 综合
形成一个应激发应,他驳斥了固有模式的说法。举了一个鱼类实验的例子,然后还提
到这种说法无法解释为何一种鸟会根据日照时间来选择栖息地,最后说这种模式目前
还有待研究。
版本二: 第三篇讲动物靠什么选择栖息地 某理论说 动物感知器官收集信息然后反馈
神经系统 后又说其他理论一个是找更多食物,另一个原因是躲避被捕食,最后说还需
要进一步研究什么真正影响,更细节记不得了„
版本三:第三篇是选择栖息地。说有的是到了 suitable 的地方就停下,有的是先有 mind
然后再找什么的。其他的忘了〒_〒
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解析:本文围绕动物如何选择栖息地这个主题展开论证。做题时需注意记录笔记,对
于结构化阅读及最后一题的解答有很大好处。动物行为主题是托福阅读常见考点,结
构不难理解。需注意各例证和主题的支撑关系。由于条理清晰,最后一题尽量考虑从
正面选出,排除为辅。
相关背景:
Habitat selection
Habitat selection is the process or behavior that an animal uses to select or
choose a habitat in which to live; correspondingly, plants and fungi engage
in habitat selection, even though their inherent mobility is different from
animals. To live in a habitat an animal must first have access to the habitat.
Once the animal has access to the habitat it must be able to tolerate the
conditions of the habitat and find the resources that it needs to survive in
that habitat. Animals must be able to tolerate at least two kinds of factors
in the habitat. These factors are abiotic factors and biotic factors. Abiotic
factors are non-biological factors such astemperature, humidity, salinity
and pH to name a few. Biotic factors are biological factors such
ascompetition, predation, and disease. If both abiotic and biotic factors can
be tolerated the animal must also be able to find the resources that it needs
to survive. These resources include food, shelter from abiotic and biotic
factors, and a mate. If an animal can not tolerate abiotic and biotic factors
in a habitat or if it does not find food, shelter or a mate in that habitat,
it is likely that the habitat will not be selected and the animal will leave
the habitat. Habitats that are suitable for animals will often times have many
animals of the same species there. This can lead to intraspecific
competition.
All of these things have an impact on the ecology of the animal
(its distribution and abundance).
One way to determine if a habitat is suitable for an animal is to conduct a
transplant experiment. In a transplant experiment animals of interest are
transplanted or brought to a habitat to test that habitat for suitability. If
the animal survives and reproduces in the habitat, it is concluded that the
habitat was unoccupied because the animal was unable to get there or because
it did not have access to the habitat. If the animal does not stay, survive,
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or reproduce in the habitat, it is concluded that it could be due to a lack
of resources or because certain biotic and or abiotic factors are present and
it can not tolerate them. A habitat that is suitable can become unsuitable if
the animal's resources and or biotic and abitoic factors change. This is what
often happens when we develop areas that are currently undeveloped. This causes
us to see animals that we never saw in our environments before. It also can
lead to a decline in the number of these animals.
2014 年 5 月 24 日
阅读词汇题:
Remarkable
Wealthy of
Devoid
Coincide with
Diffusion
Propagate
Subsequence
Initiate
Chronological
第一篇:
苏美尔人的居住地土地贫瘠,但是每年的洪水泛滥留下了肥沃的淤泥
用来耕作,由此产生了统治阶层。而统治阶层在管理时为了记录则导
致了楔形文字的产生,后来文字应用到了社会生活中。
解析:苏美尔人(也译作苏默),是历史上两河流域(底格里斯河和
幼发拉底河中下游)早期的定居民族,他们所建立的苏美尔文明是整
个美索不达米亚文明中最早,同时也是全世界最早产生的文明。苏美
尔文明主要位于美索不达米亚的南部,通过放射性碳十四的断代测
试,表明苏美尔文明的开端可以追溯至公元前 4000 年。约结束在公
元前 2000 年,被闪米特人(闪族人)建立的巴比伦所代替。这里发
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现的含有楔形文字前文字的最古老的石板(这是目前公认的最早的文
字记录)可以被定期为约前 36 世纪。
背景知识:
Sumerian Agriculture and hunting
The Sumerians adopted an agricultural mode of life as by perhaps as early as
c. 5000 - 4500 BC the region demonstrated a number of core agricultural
techniques, including organized irrigation, large-scale intensive cultivation
of land, mono-cropping involving the use of plough agriculture, and the use
of an agricultural specialized labour force under bureaucratic control. The
necessity to manage temple accounts with this organization led to the
development of writing (c. 3500 BC).
From the royal tombs of Ur, made of lapis lazuli and shell, shows peacetime
In the early Sumerian Uruk period, the primitive pictograms suggest
that sheep, goats, cattle, and pigs were domesticated. They used oxen as
their primary beasts of burden and donkeys or equids as their primary
transport animal and "woollen clothing as well as rugs were made from the wool
or hair of the animals. ... By the side of the house was an enclosed garden
planted with trees and other plants; wheat and probably other cereals were sown
in the fields, and the shaduf was already employed for the purpose of irrigation.
Plants were also grown in pots or vases."http://en.wikipedia.org/wiki/Sumer
- cite_note-Sayce-33
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An account of barley rations issued monthly to adults and children written
in cuneiformon clay tablet, written in year 4 of King Urukagina, circa 2350
BC
The Sumerians practiced similar irrigation techniques as those used in
Egypt. American anthropologist Robert McCormick Adams says that irrigation
development was associated with urbanization, and that 89% of the population
lived in the cities.
They
grew barley, chickpeas, lentils, wheat, dates, onions, garlic, lettuce, le
eks and mustard. Sumerians caught many fish and hunted fowl and gazelle.
Sumerian agriculture depended heavily on irrigation. The irrigation was
accomplished
by
the
use
of shaduf, canals, channels,dykes, weirs,
and reservoirs. The frequent violent floods of the Tigris, and less so, of
the Euphrates, meant that canals required frequent repair and continual removal
of silt, and survey markers and boundary stones needed to be continually
replaced. The government required individuals to work on the canals in a corvee,
although the rich were able to exempt themselves.
As is known from the "Sumerian Farmer's Almanac", after the flood season and
after the Spring Equinox and the Akitu or New Year Festival, using the canals,
farmers would flood their fields and then drain the water. Next they let oxen
stomp the ground and kill weeds. They then dragged the fields with pickaxes.
After drying, they plowed, harrowed, and raked the ground three times, and
pulverized it with a mattock, before planting seed. Unfortunately the high
evaporation rate resulted in a gradual increase in the salinity of the fields.
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By the Ur III period, farmers had switched from wheat to the more
salt-tolerant barley as their principal crop.
Sumerians harvested during the spring in three-person teams consisting of
a reaper, a binder, and a sheaf handler.http://en.wikipedia.org/wiki/Sumer cite_note-44 The farmers would use threshing wagons, driven by oxen, to
separate the cereal heads from the stalks and then use threshing sleds to
disengage the grain. They then winnowed the grain/chaff mixture.
Language and writing
Main articles: Sumerian language and Cuneiform
Early writing tablet recording the allocation of beer, 3100-3000 BC
The most important archaeological discoveries in Sumer are a large number
of tablets written in cuneiform. Sumerian writing is the oldest example of
writing on earth. Although pictures - that is, hieroglyphs - were first used,
symbols were later made to represent syllables. Triangular or wedge-shaped
reeds were used to write on moist clay. A large body of hundreds of thousands
of texts in the Sumerian language have survived, such as personal or business
letters, receipts, lexical lists, laws, hymns, prayers, stories, daily records,
and even libraries full of clay tablets. Monumental inscriptions and texts on
different objects like statues or bricks are also very common. Many texts
survive in multiple copies because they were repeatedly transcribed by
scribes-in-training. Sumerian continued to be the language of religion and law
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in Mesopotamia long after Semitic speakers had become dominant.
The
Sumerian
language
is
generally
regarded
as
a language
isolate in linguistics because it belongs to no known language family;
Akkadian, by contrast, belongs to the Semitic branch of the Afro-Asiatic
languages. There have been many failed attempts to connect Sumerian to
other language
groups.
It
is
an agglutinative
language;
in
other
words, morphemes ("units of meaning") are added together to create words,
unlike analytic languages where morphemes are purely added together to create
sentences.
Understanding Sumerian texts today can be problematic even for experts. Most
difficult are the earliest texts, which in many cases do not give the full
grammatical structure of the language.
During the 3rd millennium BC a cultural symbiosis developed between the
Sumerians and the Akkadians, which included widespread bilingualism. The
influences between Sumerian on Akkadian are evident in all areas including
lexical borrowing on a massive scale--and syntactic, morphological, and
phonological convergence. This mutual influence has prompted scholars to refer
to Sumerian and Akkadian of the 3rd millennium BC as asprachbund.
Akkadian gradually replaced Sumerian as a spoken language somewhere around the
turn of the 3rd and the 2nd millennium BC, but Sumerian continued to be used
as
a
sacred,
ceremonial,
literary,
and
scientific
in Babylonia and Assyria until the 1st century AD.
第二篇:
机经:
小行星对恐龙灭绝的影响。一个科学家发现土层中里有很多 Ir 元素,
而 Ir 元素在地球上少见,因此推断是小行星导致了恐龙灭绝。后面
又说了小行星使得气温降低,空气化学组成改变等等也导致恐龙的灭
绝,但是一些小的啮齿类动物则存活了下来。
language
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解析:在恐龙绝灭假说中,小行星撞击说最为流行。此说认为,小行星(后有学者认
为彗星的可能性更大)才是杀死恐龙的罪魁祸首。小行星撞击说是 1979 年由美国物理
学家阿尔瓦雷斯等人提出的。他们认为,6500 万年前的一颗直径约为 10 公里的小行星
与地球相撞,发生猛烈大爆炸,大量尘埃抛入大气层中,致使数月之内阳光被遮挡,
大地一片黑暗寒冷,植物枯死,食物链中断,包括恐龙在内的很多动物绝灭。
参考文章:Meteorite Impact and Dinosaur Extinction
Extinction of the Dinosaurs
Mass Extinctions
背景知识:
Impact event
Biospheric effects
The effect of impact events on the biosphere has been the subject of scientific
debate. Several theories of impact related mass extinction have been developed.
In the past 500 million years there have been five generally accepted,
major mass extinctions that on average extinguished half of all species. One
of the largest mass extinction to have affected life on Earth was in
the Permian-Triassic, which ended the Permian period 250 million years ago and
killed off 90% of all species; life on Earth took 30 million years to
recover. The cause of the Permian-Triassic extinction is still matter of debate
with the age and origin of proposed impact craters, i.e. the Bedout High
structure, hypothesized to be associated with it are still controversial. The
last such mass extinction led to the demise of the dinosaurs and coincided with
a large meteorite impact; this is the Cretaceous–Paleogene extinction
event (also known as the K–T or K–Pg extinction event); This occurred 66
million years ago. There is no definitive evidence of impacts leading to the
three other major mass extinctions.
In 1980, physicist Luis Alvarez; his son, geologist Walter Alvarez; and nuclear
chemists Frank Asaro and Helen V. Michael from the University of California,
Berkeley discovered unusually high concentrations of iridium in a specific
layer of rock strata in the Earth's crust. Iridium is an element that is rare
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on Earth but relatively abundant in many meteorites. From the amount and
distribution of iridium present in the 65-million-year-old "iridium layer",
the Alvarez team later estimated that an asteroid of 10 to 14 km (6 to 9 mi)
must have collided with the earth. This iridium layer at the Cretaceous–
Paleogene boundary has been found worldwide at 100 different sites.
Multidirectionally shocked quartz (coesite), which is only known to form as
the result of large impacts or atomic bomb explosions, has also been found in
the same layer at more than 30 sites. Soot and ash at levels tens of thousands
times normal levels were found with the above.
Anomalies in chromium isotopic ratios found within the K-T boundary layer
strongly support the impact theory. Chromium isotopic ratios are homogeneous
within the earth, therefore these isotopic anomalies exclude a volcanic origin
which was also proposed as a cause for the iridium enrichment. Furthermore the
chromium isotopic ratios measured in the K-T boundary are similar to the
chromium isotopic ratios found in carbonaceous chondrites. Thus a probable
candidate for the impactor is a carbonaceous asteroid but also a comet is
possible because comets are assumed to consist of material similar to
carbonaceous chondrites.
Probably the most convincing evidence for a worldwide catastrophe was the
discovery of the crater which has since been named Chicxulub Crater. This crater
is centered on the Yucatán Peninsula of Mexico and was discovered by Tony Camargo
and Glen Pentfield while working as geophysicists for the Mexican oil
companyPEMEX. What they reported as a circular feature later turned out to be
a crater estimated to be 180 km (110 mi) in diameter. Other researchers would
later find that the end-Cretaceous extinction event that wiped out the
dinosaurs had lasted for thousands of years instead of millions of years as
had previously been thought. This convinced the vast majority of scientists
that this extinction resulted from a point event that is most probably an
extraterrestrial impact and not from increased volcanism and climate change
(which would spread its main effect over a much longer time period).
Recently, several proposed craters around the world have been dated to
approximately the same age as Chicxulub — for example, the Silverpit crater in
the United Kingdom, the Boltysh crater in Ukraine and the Shiva crater near
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India. This has led to the suggestion that the Chicxulub impact was one of
several that occurred almost simultaneously, perhaps due to a
disrupted comet impacting the Earth in a similar manner to the collision
of Comet Shoemaker-Levy 9 with Jupiter in 1994; however, the uncertain age and
provenance of these structures leaves the hypothesis without widespread
support.
It was the lack of high concentrations of iridium and shocked quartz which has
prevented the acceptance of the idea that the Permian extinction was also caused
by an impact. During the late Permian all the continents were combined into
one supercontinent named Pangaea and all the oceans formed one superocean,
Panthalassa. If an impact occurred in the ocean and not on land at all, then
there would be little shocked quartz released (since oceanic crust has
relatively little silica) and much less material.
Although there is now general agreement that there was a huge impact at the
end of the Cretaceous that led to the iridium enrichment of the K-T boundary
layer, remnants have been found of other, smaller impacts, some nearing half
the size of the Chicxulub crater, which did not result in any mass extinctions,
and there is no clear linkage between an impact and any other incident of mass
extinction.
Paleontologists David M. Raup and Jack Sepkoski have proposed that an excess
of extinction events occurs roughly every 26 million years (though many are
relatively minor). This led physicist Richard A. Muller to suggest that these
extinctions could be due to a hypothetical companion star to the Sun
calledNemesis periodically disrupting the orbits of comets in the Oort cloud,
and leading to a large increase in the number of comets reaching the inner solar
system where they might hit Earth. Physicist Adrian Melott and
paleontologist Richard Bambach have more recently verified the Raup and
Sepkoski finding, but argue that it is not consistent with the characteristics
expected of a Nemesis-style periodicity.
第三篇:
机经:
冰河时期形成原因
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第一段:地球周期一直被人们观测。但直到科学家 M,才提出是地球
的 orbit 三个因素共同发生造成的。Eccentric, tilt and orbit.。
第二段:三个理论。【好长一段】
第三段:三个角度变化要好多年。周期不能解释。
第四段:还有好多其他解释,有人说火山,有人说„有人说„
解析:冰期 地球表面覆盖有大规模冰川的地质时期。又称为冰川时期。两次冰期之间
唯一相对温暖时期,称为间冰期。地球历史上曾发生过多次冰期,最近一次是第四纪
冰期。 地球在 40 多亿年的历史中,曾出现过多次显著降温变冷,形成冰期。特别是
在前寒武纪晚期、石炭纪至二叠纪和新生代的冰期都是持续时间很长的地质事件,通
常称为大冰期。大冰期的时间尺度至少数百万年。大冰期内又有多次大幅度的气候冷
暖交替和冰盖规模的扩展或退缩时期,这种扩展和退缩时期即为冰期和间冰期。
学者们提出过种种解释,但至今没有得到令人感到满意的答案。归纳起来,主要有天
文学和地球物理学成因说。
天文学成因说
天文学成因说主要考虑太阳、其他行星与地球间的相互关系。①太阳光度的周期变
化影响地球的气候。太阳光度处于弱变化时,辐射量减少,地球变冷,乃至出现冰期
气候。米兰科维奇认为,夏半年太阳辐射量的减少是导致冰期发生的可能因素。②地
球黄赤交角的周期变化导致气温的变化。黄赤交角指黄道与天赤道的交角,它的变化
主要受行星摄动的影响。当黄赤交角大时,冬夏差别增大,年平均日射率最小,使低
纬地区处于寒冷时期,有利于冰川生成。
地球物理学成因说
地球物理学成因说影响因素较多,有大气物理方面的,也有地理地质方面的。①大
气透明度的影响。频繁的火山活动等使大气层饱含着火山灰,透明度低,减少了太阳
辐射量,导致地球变冷。②构造运动的影响。构造运动造成陆地升降、陆块位移、视
极移动,改变了海陆分布和环流型式,可使地球变冷。云量、蒸发和冰雪反射的反馈
作用,进一步使地球变冷,促使冰期来临。③大气中 CO2 的屏蔽作用。CO2 能阻止或减
低地表热量的损失。
如果大气中 CO2 含量增加到今天的 2~3 倍,则极地气温将上升 8~9℃;
如果今日大气中的 CO2 含量减少 55~60%,则中纬地带气温将下降 4~5℃。在地质时期
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火山活动和生物活动使大气圈中 CO2 含量有很大变化,当 CO2 屏蔽作用减少到一定程
度,则可能出现冰期。
背景知识:
An ice age is a period of long-term reduction in the temperature of the Earth's
surface and atmosphere, resulting in the presence or expansion of continental
and polar ice sheets and alpine glaciers. Within a long-term ice age,
individual pulses of cold climate are termed "glacial periods" (or
alternatively "glacials" or "glaciations" or colloquially as "ice age"), and
intermittent warm periods are called "interglacials".Glaciologically, ice
age implies the presence of extensive ice sheets in the northern and southern
hemispheres. By this definition, we are in an interglacial period the holocene, of the ice age that began 2.6 million years ago at the start of
the Pleistocene epoch, because the Greenland, Arctic, and Antarctic ice
sheets still exist.
Variations in Earth's orbit (Milankovitch cycles)
The Milankovitch cycles are a set of cyclic variations in characteristics of
the Earth's orbit around the Sun. Each cycle has a different length, so at some
times their effects reinforce each other and at other times they (partially)
cancel each other.
Past and future of daily average insolation at top of the atmosphere on the
day of the summer solstice, at 65 N latitude.
There is strong evidence that the Milankovitch cycles affect the occurrence
of glacial and interglacial periods within an ice age. The present ice age is
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the most studied and best understood, particularly the last 400,000 years, since
this is the period covered by ice cores that record atmospheric composition
and proxies for temperature and ice volume. Within this period, the match of
glacial/interglacial frequencies to the Milanković orbital forcing periods is
so close that orbital forcing is generally accepted. The combined effects of
the changing distance to the Sun, the precession of the Earth's axis, and the
changing tilt of the Earth's axis redistribute the sunlight received by the
Earth. Of particular importance are changes in the tilt of the Earth's axis,
which affect the intensity of seasons. For example, the amount of solar influx
in July at 65 degrees north latitude varies by as much as 22% (from 450 W/m²
to 550 W/m²). It is widely believed that ice sheets advance when summers become
too cool to melt all of the accumulated snowfall from the previous winter. Some
workers believe that the strength of the orbital forcing is too small to trigger
glaciations, but feedback mechanisms like CO
2 may explain this mismatch.
While Milankovitch forcing predicts that cyclic changes in the Earth's orbital
elements can be expressed in the glaciation record, additional explanations
are necessary to explain which cycles are observed to be most important in the
timing of glacial–interglacial periods. In particular, during the last 800,000
years, the dominant period of glacial–interglacial oscillation has been
100,000
years,
which
corresponds
to changes in
Earth's orbital
eccentricity and orbitalinclination. Yet this is by far the weakest of the three
frequencies predicted by Milankovitch. During the period 3.0–0.8 million years
ago, the dominant pattern of glaciation corresponded to the 41,000-year period
of changes in Earth's obliquity (tilt of the axis). The reasons for dominance
of one frequency versus another are poorly understood and an active area of
current research, but the answer probably relates to some form of resonance
in the Earth's climate system.
The "traditional" Milankovitch explanation struggles to explain the dominance
of the 100,000-year cycle over the last 8 cycles. Richard A. Muller, Gordon
J. F. MacDonald, and others have pointed out that those calculations are for
a two-dimensional orbit of Earth but the three-dimensional orbit also has a
100,000-year cycle of orbital inclination. They proposed that these variations
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in orbital inclination lead to variations in insolation, as the Earth moves
in and out of known dust bands in the solar system. Although this is a different
mechanism to the traditional view, the "predicted" periods over the last 400,000
years are nearly the same. The Muller and MacDonald theory, in turn, has been
challenged by Jose Antonio Rial.
Another worker, William Ruddiman, has suggested a model that explains the
100,000-year cycle by the modulating effect of eccentricity (weak 100,000-year
cycle) on precession (26,000-year cycle) combined with greenhouse gas feedbacks
in the 41,000- and 26,000-year cycles. Yet another theory has been advanced
by Peter Huybers who argued that the 41,000-year cycle has always been dominant,
but that the Earth has entered a mode of climate behavior where only the second
or third cycle triggers an ice age. This would imply that the 100,000-year
periodicity is really an illusion created by averaging together cycles lasting
80,000 and 120,000 years. This theory is consistent with a simple empirical
multi-state model proposed by Didier Paillard. Paillard suggests that the late
Pleistocene glacial cycles can be seen as jumps between three quasi-stable
climate states. The jumps are induced by the orbital forcing, while in the early
Pleistocene the 41,000-year glacial cycles resulted from jumps between only
two climate states. A dynamical model explaining this behavior was proposed
by Peter Ditlevsen. This is in support of the suggestion that the
late Pleistocene glacial cycles are not due to the weak 100,000-year
eccentricity cycle, but a non-linear response to mainly the 41,000-year
obliquity cycle.
Changes in Earth's atmosphere
There is considerable evidence that over the very recent period of the last
100–1000 years, the sharp increases in human activity, especially the burning
of fossil fuels, has caused the parallel sharp and accelerating increase in
atmospheric greenhouse gases which trap the sun's heat. The consensus theory
of the scientific community is that the resulting greenhouse effect is a
principal cause of the increase in global warming which has occurred over the
same period, and a chief contributor to the accelerated melting of the
remaining glaciers and polar ice. A 2012 investigation finds that dinosaurs
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released methane through digestion in a similar amount to humanity's current
methane release, which "could have been a key factor" to the very warm climate
150 million years ago.
There is evidence that greenhouse gas levels fell at the start of ice ages and
rose during the retreat of the ice sheets, but it is difficult to establish
cause and effect (see the notes above on the role of weathering). Greenhouse
gas levels may also have been affected by other factors which have been proposed
as causes of ice ages, such as the movement of continents and volcanism.
The Snowball Earth hypothesis maintains that the severe freezing in the
late Proterozoic was ended by an increase in CO2 levels in the atmosphere, and
some supporters of Snowball Earth argue that it was caused by a reduction in
atmospheric CO2. The hypothesis also warns of future Snowball Earths.
In 2009, further evidence was provided that changes in solar insolation provide
the initial trigger for the Earth to warm after an Ice Age, with secondary
factors like increases in greenhouse gases accounting for the magnitude of the
change.
William Ruddiman has proposed the early anthropocene hypothesis, according to
which the anthropocene era, as some people call the most recent period in the
Earth's history when the activities of the human species first began to have
a significant global impact on the Earth's climate and ecosystems, did not begin
in the 18th century with the advent of the Industrial Era, but dates back to
8,000 years ago, due to intense farming activities of our early agrarian
ancestors. It was at that time that atmospheric greenhouse gas concentrations
stopped following the periodic pattern of the Milankovitch cycles. In
his overdue-glaciationhypothesis Ruddiman states that an incipient glacial
would probably have begun several thousand years ago, but the arrival of that
scheduled glacial was forestalled by the activities of early farmers.
At a meeting of the American Geophysical Union (December 17, 2008), scientists
detailed evidence in support of the controversial idea that the introduction
of large-scale rice agriculture in Asia, coupled with extensive deforestation
in Europe began to alter world climate by pumping significant amounts of
greenhouse gases into the atmosphere over the last 1,000 years. In turn, a warmer
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atmosphere heated the oceans making them much less efficient storehouses of
carbon dioxide and reinforcing global warming, possibly forestalling the onset
of a new glacial age.
2014 年 5 月 25 日
(1)人类的活动和动物的灭绝
将 overhunting,中间一个个科学家说不对,其实是 climate change 导致了,讲人类
人前北美很多大型动物,但是人类出现以后大型动物都挂了,主要原因是人类的过度
捕猎。接着说气候也是一个潜在原因,而且一些大型动物挂了,认识 rodent 并没有灭
绝。有举例,在人类出现以后很短的时间内动物数量急剧下降,虽然这个事实被捕鱼
大丰收的情况所 disguise,一个明显的证据就是一种特殊的鱼到了食物链底端。
解析:本篇文章讲解了动物的灭绝的原因。相似的话题可以参考 tpo 中文章 mass
extinction,文章的理解重点是要把握好解释灭绝的原因,以及相对应所举的例子。
按照不同的灭绝的原因梳理文章的结构。相应的背景请参考下文:
As long as species have been evolving, species have been going extinct. It
is estimated that over 99.9% of all species that ever lived are extinct. The
average life-span of a species is 10 million years[citation needed], although
this varies widely between taxa. There are a variety of causes that can
contribute directly or indirectly to the extinction of a species or group of
species. "Just as each species is unique", write Beverly and Stephen C. Stearns,
"so is each extinction ... the causes for each are varied—some subtle and
complex, others obvious and simple". Most simply, any species that cannot
survive and reproduce in its environment and cannot move to a new environment
where it can do so, dies out and becomes extinct. Extinction of a species may
come suddenly when an otherwise healthy species is wiped out completely, as
when toxic pollution renders its entire habitat unliveable; or may occur
gradually over thousands or millions of years, such as when a species gradually
loses out in competition for food to better adapted competitors. Extinction
may occur a long time after the events that set it in motion, a phenomenon known
as extinction debt.
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Habitat degradation
Habitat degradation is currently the main anthropogenic cause of species
extinctions. The main cause of habitat degradation worldwide is agriculture,
with urban sprawl, logging, mining and some fishing practices close behind.
The degradation of a species' habitat may alter the fitness landscape to such
an extent that the species is no longer able to survive and becomes extinct.
This may occur by direct effects, such as the environment becoming toxic, or
indirectly, by limiting a species' ability to compete effectively for
diminished resources or against new competitor species.
Habitat degradation through toxicity can kill off a species very rapidly, by
killing all living members through contamination or sterilizing them. It can
also occur over longer periods at lower toxicity levels by affecting life span,
reproductive capacity, or competitiveness.
Habitat degradation can also take the form of a physical destruction of niche
habitats. The widespread destruction of tropical rainforests and replacement
with open pastureland is widely cited as an example of this; elimination of
the dense forest eliminated the infrastructure needed by many species to survive.
For example, a fern that depends on dense shade for protection from direct
sunlight can no longer survive without forest to shelter it. Another example
is the destruction of ocean floors by bottom trawling.
Diminished resources or introduction of new competitor species also often
accompany habitat degradation. Global warming has allowed some species to
expand their range, bringing unwelcome competition to other species that
previously occupied that area. Sometimes these new competitors are predators
and directly affect prey species, while at other times they may merely
outcompete vulnerable species for limited resources. Vital resources including
water and food can also be limited during habitat degradation, leading to
extinction.
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Predation, competition, and disease
In the natural course of events, species become extinct for a number of reasons,
including but not limited to: extinction of a necessary host, prey or pollinator,
inter-species competition, inability to deal with evolving diseases and
changing environmental conditions (particularly sudden changes) which can act
to introduce novel predators, or to remove prey. Recently in geological time,
humans have become an additional cause of extinction (many people would say
premature extinction) of some species, either as a new mega-predator or by
transporting animals and plants from one part of the world to another. Such
introductions have been occurring for thousands of years, sometimes
intentionally (e.g. livestock released by sailors on islands as a future source
of food) and sometimes accidentally (e.g. rats escaping from boats). In most
cases, the introductions are unsuccessful, but when an invasive alien species
does become established, the consequences can be catastrophic. Invasive alien
species can affect native species directly by eating them, competing with them,
and introducing pathogens or parasites that sicken or kill them; or indirectly
by destroying or degrading their habitat. Human populations may themselves act
as invasive predators. According to the "overkill hypothesis", the swift
extinction of the megafauna in areas such as Australia (40,000 years before
present), North and South America (12,000 years before present), Madagascar,
Hawaii (300-1000 CE), and New Zealand (1300-1500 CE), resulted from the sudden
introduction of human beings to environments full of animals that had never
seen them before, and were therefore completely unadapted to their predation
techniques.
Climate change
Extinction as a result of climate change has been confirmed by fossil studies.
Particularly, the extinction of amphibians during the Carboniferous Rainforest
Collapse, 305 million years ago. A 2003 review across 14 biodiversity research
centers predicted that, because of climate change, 15–37% of land species would
be "committed to extinction" by 2050. The ecologically rich areas that would
potentially suffer the heaviest losses include the Cape Floristic Region, and
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the Caribbean Basin. These areas might see a doubling of present carbon dioxide
levels and rising temperatures that could eliminate 56,000 plant and 3,700
animal species.
(2) 讲得是 pest 的问题,如何处理害虫。。
先讲了一个例子好像是美国西南部,具体记不清了,其实是为了引出 chemical 方法 ,
就是杀虫剂 pesticide,而且还讲了杀虫剂的负作用,会对 native 的一些物种造成预
想不到的损伤。同时 pest 产生耐药性的时间大约 5 年,远短于研制出新的 pesticide
所需要的时间。
(就是说这方法有明显缺陷,好引出下面的方法,你们懂得!!
!肯定有
题的嘛...)
然后就讲了 biological 方法,引进 pest 的天敌,因为多数顽固的 pest 其实是外来物
种,之所以成为 pest 就是没有天敌。这里举了中国古代的一个例子,知道例子的功能
就好。 (有题)然后这提到了一些不足,细节记不太清楚了。
最后来到了终极大招,一个叫 IPM 的方法让害虫们明白!!!其实就是一种 integrated
的什么方法,综合考虑各种因素,什么经济啊,生物学啊,如果不得不用杀虫剂要控
制剂量啊等等(有排除题)。其实我觉得不算新方法,但是就是综合考虑,然后就有了
IPM 这样一个酷炫的名字。
解析:本篇文章讲解了处理害虫的不同方法。理解文章时按照不同的处理方法梳理文
章的结构,不同的方法要把握住作者关于其优点和缺点的介绍,不同的方法的不同特
点为文章出题的题点。
Insects become resistant to chemical insecticides very rapidly—it can happen
in as few as five generations.
This is natural selection at work.
The problem is that an insecticide never kills all of its intended victims.
If even a few insects survive, they will reproduce. These surviving insects
will produce two types of young—those that are resistant to the spray, and
those that are not. The non-resistant insects will be killed in the next spraying,
but those that are left reproduce. At each generation, the number of naturally
resistant insects in the population increases.
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An individual insect does not become resistant during its lifetime. It is born
either resistant or non-resistant, and it is the population as a whole that
gradually becomes resistant to the pesticide over time. The Bt toxins become
ineffective, and the benefits of using them (less toxicity to non-target species)
disappear.
As this occurs, a new pesticide must be developed. Over time, populations of
insects can become resistant to more and more pesticides. As a result, humans
need to make different pesticides that are generally stronger.
Organic farmers have used Bt on their crops for a number of years. They are
concerned that the increased use of the Bt toxin could speed up the development
of resistant insect populations.
Entomologists know that controlled, laboratory experiments with generations
of insects cannot be easily reproduced in the field. How the resistant insects
breed with refuge insects, and over what time frames, will determine the success
of this technology.
These concerns are balanced by concerns that existing pesticide practices can
be much more dangerous for non-target insect species than insect-resistant
crops. Conventional non-selective pesticides kill many non-target insects. By
reducing the number of sprays needed, insect-resistant crops help to preserve
beneficial predator insects and simplify management decisions.
(3) 讲的是动物、昆虫的发声的问题
最开始怎么说的记不清楚了,第一层应该就是 rain forest 里面的小东东怎么让声音
传播。热带雨林里面这么吵,要让同类听到自己还是很不容易的,尤其对于那些小昆
虫什么的,而且很多小东西通过发声来求偶交配嘛,你们都懂的!!!Rain forest 这里
举了一个树蛙的例子,就是这小青蛙用的一种招数,它一般会进到有水的树洞, 身体
一部分没入水中,然后开始发声,找到与大树能共鸣的频率,这不就能传的更高更远
嘛。(有排除题)
咨询电话:010-82611818
下面一层应该是讲 birds,同时提到了它们叫的时间一般是在早上和黄昏,那个时候声
音能传得更远, 但是有些时候也会让天敌们发现之类的(没记错的话,最少有俩道题)
最后一层应该是提到了不同物种的发声频率不同,这能让它们被分辨出来。还有一个
教授,把声音录下来回去分析,发现每个雨林的声音还不太一样,也是 unique 的,甚
至可以像人类的指纹一样去分辨树林的独特声音什么的(有题)
解析:本篇文章讲解了雨林中不同动物不同的传递信息的方式。属于生物学中典型的
话题,请大家理解文章时重点关注生物传递信息的方式与雨林环境的适应性的体现。
相应背景请参考下文:
The daytime quality of light in forests varies with the density of the
vegetation, the angle of the Sun, and the amount of cloud in the sky. Both animals
and plants have different appearances in these various lighting conditions.
A color or pattern that is relatively indistinct in one kind of light may be
quite conspicuous in another.
In the varied and constantly changing light environment of the forest, an
animal must be able to send visual signals to members of its own species and
at the same time avoid being detected by predators. An animal can hide from
predators by choosing the light environment in which its pattern is least
visible. This may require moving to different parts of the forest at different
times of the day or under different weather conditions, or it may be achieved
by changing color according to the changing light conditions. Many species of
amphibians (frogs and toads) and reptiles (lizards and snakes) are able to
change their color patterns to camouflage themselves. Some also signal by
changing color. The chameleon lizard has the most striking ability to do this.
Some chameleon species can change from a rather dull appearance to a full riot
of carnival colors in seconds. By this means, they signal their level of
aggression or readiness to mate.
Other species take into account the changing conditions of light by
performing their visual displays only when the light is favorable. A male bird
of paradise may put himself in the limelight by displaying his spectacular
plumage in the best stage setting to attract a female. Certain butterflies move
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into spots of sunlight that have penetrated to the forest floor and display
by opening and closing their beautifully patterned wings in the bright
spotlights. They also compete with each other for the best spot of sunlight.
Very little light filters through the canopy of leaves and branches in a
rain forest to reach ground level—or close to the ground—and at those levels
the yellow-to-green wavelength predominate. A signal might be most easily seen
if it is maximally bright. In the green-to-yellow lighting conditions of the
lowest levels of the forest, yellow and green would be the brightest colors,
but when an animal is signaling, these colors would not be very visible if the
animal was sitting in an area with a yellowish or greenish background. The best
signal depends not only on its brightness but also on how well it contrasts
with the background against which it must be seen. In this part of the rain
forest, therefore, red and orange are the best colors for signaling, and they
are the colors used in signals by the ground-walking Australian brush turkey.
This species, which lives in the rain forests and scrublands of the east coast
of Australia, has a brown-to-black plumage with bare, bright-red skin on the
head and a neck collar of orange-yellow loosely hanging skin. During courtship
and aggressive displays, the turkey enlarges its colored neck collar by
inflating sacs in the neck region and then flings about a pendulous part of
the colored signaling apparatus as it utters calls designed to attract or repel.
This impressive display is clearly visible in the light spectrum illuminating
the forest floor.
Less colorful birds and animals that inhabit the rain forest tend to rely
on forms of signaling other than the visual, particularly over long distances.
The piercing cries of the rhinoceros hornbill characterize the Southeast Asian
rain forest, as do the unmistakable calls of the gibbons. In densely wooded
environments, sound is the best means of communication over distance because
in comparison with light, it travels with little impediment from trees and other
vegetation. In forests, visual signals can be seen only at short distances,
where they are not obstructed by trees. The male riflebird exploits both of
these modes of signaling simultaneously in his courtship display. The sounds
made as each wing is opened carry extremely well over distance and advertise
his presence widely. The ritualized visual display communicates in close
quarters when a female has approached.