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标题: 【揽瓜阁3.0】Day9 2020.07.28【自然科学-宇宙】【自然科学-环境】 [打印本页]
作者: 妥妥 时间: 2020-7-27 22:21
标题: 【揽瓜阁3.0】Day9 2020.07.28【自然科学-宇宙】【自然科学-环境】
揽瓜阁俱乐部第三期
Day9 2020.07.28
【自然科学-宇宙】
How Exploding Stars May Have Shaped Earth's History
（931字 精读 必做篇）
The aftermath of a star's death can rival the events of a creation myth. When a star explodes in a supernova, hurling pieces of itself into the cosmos, it seeds new stars and new worlds with the raw materials required for life. In death, stars are reborn. But like all creation tales, this one has a dark side. Supernovae can rain radiation and death onto living worlds that already exist. And they might be able to change the course of natural history.
One such change might have happened on Earth sometime between 1.7 and 3.2 million years ago. A star about nine times the mass of the sun blew up, and the night sky glowed a bright blue for weeks, during which the supernova outshone the full moon. Long after the darkness returned, lightning set off by cosmic rays would have arced from the sky to the ground, and the planet's climate may have changed. Animals on land and in the shallow sea would have been doused with waves of radiation. Over time, the influx of particles could have sparked mutations in DNA, making small alterations that could have shifted the course of evolution.
From our vantage point on Earth, supernovae appear suddenly; their name comes from the word for “new star.” Their brilliant, visible shine fades away within a few days or weeks, but they continue firing a stupendous surge of x-rays, gamma rays and speedy, energetic particles for much longer. Only recently have astronomers brought these supernovae down to Earth, by wondering how they might have interfered with the planet's climate, and the evolutionary processes that were playing out on its surface.
Adrian Melott, a physicist at the University of Kansas, wondered about the timing of the more recent supernova. Its date range includes the timeline of a minor extinction event at the endstart of the Pleistocene, about 2.59 million years ago, one that was long thought to be caused, in part, by a cooling climate and dramatic regional changes in Africa and central America. Melott and others had wondered whether a supernova could shower enough particles and radiation on Earth to cause mass extinctions. Thanks to the new research on supernova history, they could now look into it in earnest.
Melott ran computer simulations that suggested that even mild star-explosions would shower Earth with radiation for hundreds of thousands of years, provided they were local. They would also ionize the atmosphere to a level eight times higher than normal, which would trigger an increase in cloud-to-ground lightning.
“I really expected to conclude that there wasn't much chance of an effect, because of the distance, but it turned out to be more substantial than I expected,” Melott says.
While Melott and his coauthors were working on this paper, which appears today in The Astrophysical Journal Letters, another supernova archaeology team was refining the most recent research on the two local supernovae from 1.5 and 3.2 million and 6.5 to 8.7 million years ago. Brian Fields, Brian Fry and John Ellis argue that those supernovae were closer than scientists thought — maybe only 150 light years distant, not 325. If that's true, the radiation effect would be even stronger, Melott says.
The immediate radiation dose wouldn't be terrible, roughly comparable to the amount you'd receive in a CT scan. But it wouldn't be a one-shot deal. Instead, the radiation would rain down for hundreds of thousands of years. Melott says the particles would largely include muons, which are a sister particle of the electron and have more energy, so they can penetrate deeper, including into the oceans. They would also add up to a bigger effect on large animals, like mammoths, maybe, or humans. All told, supernova radiation could triple the everyday background radiation from cosmic rays.
“It would trivially increase your chances of cancer, but if you do it to every organism on Earth, for hundreds of thousands of years, there might be something you could see,” Melott says. “If you could have good enough statistics to look for bone cancer in fossils, for instance, you might be able to do that.” Melott said he had worked on research into whether this was actually possible.
Radiation is known to cause mutations in DNA in living organisms and in their sex cells, which leads to mutations and possible physical changes in later generations. A tweak in DNA here, a shift in chromosomes there can add up to substantive changes over time, altering the process of evolution.
To Melott, the real surprise was the increase in lightning. A major spike in atmospheric ionization would increase cloud-to-ground lightning, which might affect the weather, or at the very least might spark more wildfires. “That is one of the things we want to investigate, whether there is any evidence of increase in wildfire in the geological record,” he says. But he notes he's not a climatologist, and it would be up to climate scientists to study how ionizing the atmosphere would affect the climate.
Of course, it would take a great deal of substantial evidence to tie a specific supernova to climate changes and mass extinction. That's why it's the modeling work that's most interesting about this research. If a medium-sized explosion a few hundred light-years away would almost certainly do something—what, then, of huge explosions?
“This is not a major event as far as the Earth is concerned. Such a thing should come along on average every couple of million years,” Melott says. “But it means that the really nearby ones, that come along every couple hundred million years, could be quite devastating.”
Source: The Atlantic
【自然科学-环境】
Forests Getting Younger and Shorter
（311字 2分22秒 精听 必做篇）
先做精听再核对原文哦~
[attach]251774[/attach]
They give us paper and fuel, as well as vital ecological services—like cleaning the air, storing carbon and providing habitat. We’re talking about trees, of course. But changes in the environment largely caused by humans appear to be causing profound transformations in trees around the world.
In a new study, scientists reviewed global research on trends in tree birth, growth and death. They combined those data with an analysis of deforestation. And they found that worldwide, older trees are dying at a higher rate than in the past due to factors like rising air temperature, wildfires, drought and pathogens.
“And most of the drivers of that decrease in large, old trees are increasing themselves, such as temperature going up, droughts are more severe, wildfires, windstorms and deforestation are all—although variable across the globe—they’re generally increasing. And so both the loss has already occurred, but we expect more continued loss of big, old trees.”
Nate McDowell, an earth scientist at Pacific Northwest National Lab, who was one of the study’s authors.
“So if we have an increasing rate of death, particularly of the larger, older trees, what’s left are the younger trees. So that’s why, on average, through the loss of bigger, older trees, our forests are becoming inherently younger and shorter.”
This trend is a problem, because old trees are vitally important.
“For sure, the increase in death does limit the carbon storage of an ecosystem and can force the system to become a carbon source to the atmosphere. The second reason we care is from a biodiversity perspective: old growth trees tend to house a higher biodiversity than young forests do. And the third reason is aesthetic: As a society, we care about these trees. We have national parks named after these big trees. So there’s a personal reason for people to care about this as well.”
Source: Scientific American
【笔记格式要求】
精读笔记格式要求：
1.总结文章中心大意
2.总结分论点或每段段落大意
3.摘抄印象深刻或者觉得优美的句子
4.总结文章中的生词
5.记录阅读时间、总结时间、总时间
精听笔记格式要求：
1.逐句听写整篇文章
2.对照原文修改听写稿，标记出错原因
3.总结文章中心大意
4.总结精听过程中的生词
5.记录听写时间、总结时间、总时间
这里也给大家两点学习小建议哦~
精读：如遇到读不懂的复杂句，建议找出句子主干，分析句子成分，也可以尝试翻译句子来帮助理解~
精听：建议每句不要反复纠结听，如果听 5 遍都没听出来，那就跳过，等完成后再回听总结原因，时间宝贵，不要过于执着哦~
作者: 妥妥 时间: 2020-7-27 22:22
揽瓜阁俱乐部，自「language」一词谐音而来，是一个为帮助大家提升英语语言能力而建立的学习小团队。在这里，我们将定时发布涵盖各类话题的外刊语料，供大家练习听、读。同时还设置了严格的打卡机制，督促大家克服懒惰坚持学习。
同时我们也招募volunteer协助维护团队，确保学习活动顺利开展~大家一起营造积极向上的学习氛围~
想要提升英语能力的小伙伴，快快添加微信（theTOEFL）报名加入吧，大家一起观尽天下新鲜事，览遍四海热议瓜～
作者: shuzijun 时间: 2020-7-28 08:26
DAY 9 打卡
作者: 木辛青 时间: 2020-7-28 09:53
阅读笔记
总结：29min 阅读：9min 总：38min
恒星爆炸如何塑造了地球的历史
1.恒星死亡的后果比得上创造神话的事件，碎片会创造出新的恒星和新的世界，恒星爆炸会产生辐射影响其上活着的生命，它会改变自然历史的原因
2.1.7-3.2百万年前地球就经历了一次巨变，气候由于太阳活动而发生改变，地球上活着的生命受到了辐射的影响，生命体也发生了进化
3.受到辐射的影响，新星影响了气候，研究它是如何在其表面发生进化的
4.教授研究了最近的新星，大约2.59百万年前，发生在美国和非洲的气候变冷及急剧的原始变化，研究者们想知道辐射是如何影响了大灭绝，好在研究了新星的历史让其可以继续深入
5.研究结果显示出乎意料的多
6.如果另一组的研究是真实的，那么辐射影响会更加严重
7.但是最近的辐射并没有很糟糕，其程度大概和照了CT一样，但是辐射消失要耗费上百年到上千年的时间
8.很有可能会提高患癌症的几率
9.众所周知辐射会改变我们的DNA会影响我们的性别细胞会对我们后代产生影响，影响染色体进而影响人类的进化
10.气候性的变化源于影响太阳到地球的光线，进而对天气造成影响，同时也很有可能引起山火，但是他不是气候学家，还需要气候学家研究大气层如何对天气产生影响
11.当然理想化的状态是将新星与气候变化和大型灭绝相连接
12.但是这不是考虑地球而考虑的主要事件，这样的情况每几百万年就会发生一次
aftermath 后果
supernova超新星
been doused with 被浇灭
stupendous惊人的
interfered 插手
trivially 琐细的
chromosomes 染色体
devastating 摧毁
听力笔记
时间：28min 总结：25min
树能够给我们带来很多好处，包括提供纸张和燃料，并且有重要的经济价值，但是最近随着采伐树木的发展，树的年龄越来越年轻且体格越来越小了
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作者: lucin 时间: 2020-7-28 11:39
Day9
作者: ChloeSolo 时间: 2020-7-28 14:53
Day 9
作者: Amaranth- 时间: 2020-7-28 15:05
day9
作者: Dannibiubiubiu 时间: 2020-7-28 15:37
day9
作者: cynwis 时间: 2020-7-28 19:42
DAY 9
作者: ppxstar 时间: 2020-7-28 21:04
Day 9
作者: Dovis 时间: 2020-7-28 21:05
揽瓜阁 Day 9
精读 How Exploding Stars May Have Shaped Earth's History
一 文章大意
恒星的爆炸会带来新生命需要的物质，也会给现存生物造成辐射和死亡，从而改变生物历史进程。有研究人员认为，超新星与气候变化和大规模灭绝有联系，并利用电脑模拟描述了爆炸带来的后果。但该联系仍需要大量的实质证据。
二 段落总结
- 总概括：恒星的死亡可以给孵化新星，给新生物带来物质；同时，它也会对现有生物造成辐射和死亡，从而改变自然历史进程。
- 总概括：在170—320万年前，地球发生过恒星爆炸。造成地球气候变更，生物辐射，引发DNA突变。
- 提出问题：直至最近，天文学家怀疑这些
- 进一步提出问题：一位物理学家想知道超新星最近出现的时间，并怀疑是超新星粒子散落造成了生物大灭绝。
- 模拟论证：他所做的电脑模拟展示了超新星爆炸如何影响地球辐射和大气。
- 模拟论证：该物理学家所做的模拟结果超出了他的预期。
- 另一项证据：有另外两位考古学家认为最近出现的两个超新星比预计的距离更近。因此辐射力度更强。
- 描述结果：辐射虽然强度和CT扫描类似，但爆炸的辐射会经年累月地散发，而且能渗透到大型动物身体内部，产生更大影响。
- 描述结果：这种辐射轻而易举地增加患癌症的机会，并推测化石中有患骨癌的现象。
- 描述结果：已知辐射会引起活生物体及其性细胞中DNA的突变，影响生物进化过程。
- Melott发现超新星爆炸会引发雷电增加，推测爆炸可能会影响天气或引发更多野火。
- 总结：将特定的超新星与气候变化和大规模灭绝联系起来需要大量的实质证据。
三 生词摘录
aftermath (战争、事故、不快事情的) 后果，创伤;
supernova 超新星
hurl 猛扔; 猛投; 猛摔; 大声说出(辱骂或斥责等); 呕吐
cosmos (尤指被视为有序体系时的) 宇宙
outshine 比…做得好; 使逊色; 高人一筹
douse 浇灭(火); 熄(灯); 往…上泼水; 把…浸在液体里
influx (人、资金或事物的) 涌入，流入
vantage 有利
stupendous 极大的; 令人惊叹的; 了不起的;
chromosomes 染色体
tweak 扭; 拧; 扯; 稍稍调整(机器、系统等)
spike 用尖物刺入(或扎破); 在…中偷偷掺入(烈酒、毒药或毒品); 拒绝发表; 阻止…传播; 阻挠
devastating 破坏性极大的; 毁灭性的; 令人震惊的; 骇人的; 给人印象深刻的; 令人钦佩的; 强有力的
四 句子摘抄
Only recently have astronomers brought these supernovae down to Earth, by wondering how they might have interfered with the planet's climate, and the evolutionary processes that were playing out on its surface.
五 用时记录
通读 9.5min 总结 44min 共计55min
作者: はな 时间: 2020-7-28 21:06
DAY9
作者: 殺G成功 时间: 2020-7-28 21:10
打卡
作者: Carlisler 时间: 2020-7-28 21:45
Day 9 打卡
[attach]252212[/attach][attach]252214[/attach][attach]252213[/attach][attach]252211[/attach][attach]252210[/attach]
作者: N0ire 时间: 2020-7-28 21:51
Day 9打卡
作者: 啊哒 时间: 2020-7-28 22:16
打卡
作者: wanglu1994143 时间: 2020-7-28 22:18
打卡
作者: YLEmily 时间: 2020-7-28 22:21
DAY 9
作者: micahlan 时间: 2020-7-28 22:25
Day9打卡
[attach]252221[/attach]
作者: cgvmc 时间: 2020-7-28 22:28
DAY9
作者: KLYnn 时间: 2020-7-28 22:31
打卡～
作者: 龙驾马 时间: 2020-7-28 22:38
阅读笔记
中心大意
科学家正在观察超新星爆发，其对地球的影响可能出乎原来的意料，不止是其辐射带来的直接影响，更可能其辐射会对大气层产生影响，进而对地球气候造成影响。
段落大意
1-2 段 总论-（开头兼背景知识） 超新星爆发在地球早期曾经近距离爆发过，其粒子曾来到过地球
3-7段 分论点1 超新星爆发的影响 超新星爆发其实可能给地球带来不小的影响，不止是辐射，还能对气候产生影响。
8-10段 分论点2 辐射计量不会大到对人类健康产生影响
11-13段 分论点3 超新星爆发可能对气候产生难以预计的影响。
句子摘抄
When a star explodes in a supernova, hurling pieces of itself into the cosmos, it seeds new stars and new worlds with the raw materials required for life. I
Their brilliant, visible shine fades away within a few days or weeks, but they continue firing a stupendous surge of x-rays, gamma rays and speedy, energetic particles for much longer.
Its date range includes the timeline of a minor extinction event at the endstart of the Pleistocene, about 2.59 million years ago, one that was long thought to be caused, in part, by a cooling climate and dramatic regional changes in Africa and central America.
单词摘抄
supernovae n.超新星
Astrophysical n.天体物理学
chromosomes n.染色体
extinction n.灭绝
ionizing n.电离子化
用时
阅读用时13分钟 总结40分钟 共计 53分钟
听力笔记
[attach]252228[/attach][attach]252229[/attach]
中心大意
树木是我们重要的自然资源，科学家研究树木近年来的寿命后发现，发现树木的死亡率正在增加，或者说寿命正在降低。原因可能是气温升高，也可能是其他环境不稳定因素（比如野火）的增加。
生词摘抄
ecological a.生态的，生态学的
deforestation n.毁林
inherently adv.内在地
biodiversity n.生物多样性
用时
听写22分钟 总结39分钟 共计61分钟
作者: Garfieldsu 时间: 2020-7-28 22:42
day 9 打卡
作者: Dovis 时间: 2020-7-28 22:46
精听 Forests Getting Younger and Shorter
一 文章大意
在一项新研究中，科学家回顾了有关树木出生，生长和死亡趋势的全球研究。他们将这些数据与森林砍伐分析结合在一起发现，在全球范围内，由于气温升高，野火，干旱和病原体等因素，老树的死亡率比过去更高，这值得人们重视。
二 生词摘录
deforestation 毁林; 滥伐森林; 烧林
pathogen 病原体
Aesthetic 审美的; 有审美观点的; 美学的; 美的; 艺术的
三 用时记录
听力 5min 听写 25min 总结 4min 共计37min
作者: 猫小痕77 时间: 2020-7-28 22:47
day9
作者: ste蔡 时间: 2020-7-28 23:26
day9
作者: Lingli_Here 时间: 2020-7-29 00:00
DAY 9:
精读笔记格式要求：
1. The radiation exploded from the star can effect the living.
2. Supernova can rain radiation and death onto living worlds that already exist.
2-1. The influx of particles could have sparked mutations in DNA, making small alterations that could have shifted the course of evolution.
2-2. From our vantage point on Earth, supernovae appear suddenly
2-3. New technology helped physicist to look into it in earnest, find the immediate radiation dose wouldn't be terrible
2-4. It would take a great deal of substantial evidence to tie a specific supernova to climate changes and mass extinction, and it is every couple of million years.
3&4:
the influx 涌入 of particles
gamma rays
It would trivially 微不足道 increase your chances of cancer
a shift in chromosomes 染色体
atmospheric ionization 离子化
ionizing the atmosphere
5:
10:00/ 25min/ 35min
精听笔记格式要求：
2&4
vital 必不可少 ecological services
profound 巨大 transformations
an analysis of deforestation 砍伐森林
For sure, the increase in death does limit the carbon storage of an ecosystem and can force the system to become a carbon source to the atmosphere. The second reason we care is from a biodiversity perspective: old growth trees tend to house a higher biodiversity than young forests do. And the third reason is aesthetic: As a society, we care about these trees. We have national parks named after these big trees
3. on average, through the loss of bigger, older trees, our forests are becoming inherently younger and shorter
5.
3min/ 20min/ 23min
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