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标题: 9.19下午场，RC部分放狗 [打印本页]

作者: kaworu_zhang 时间: 2017-9-19 17:49
标题: 9.19下午场，RC部分放狗
RC部分放狗
1. 交通拥堵的书评，有东京，和加拿大城市（好像是渥太华？）问题highlight 最后“a such city”有什么特征

2. recession
3. 制造业和航空业对比的那个

4. 树的年轮

P1科学家通过树的年轮来判断过去气候变化情况，然而普通树的年轮有可能因为气候的剧烈变化难以分辨。然后科学家又去用沉淀物中碳的同位素测定，然而这个只能预测几百年。而通过年轮可以探测几百万年。
P2这个时候一个科学家使用X光扫描一种特定树的时候，发现钙元素也会被树木吸收，形成看不见的年轮，然后说具体说明了年轮是怎么形成的。
P3然而这个方法有两个问题，一个是说钙的年轮是几种特殊的热带树木自己的特征，还是说是一个能广泛应用的方法。另一个是他对于气候变化究竟能有多大的反应？后面还有一点记不太清了。

感觉数学高分裤部分的题真的好难，很费时间…答完Q心态崩了，再答Vpace就把握不好了，有一道题想了4分钟犯了大忌…已经三战了，感觉自己好败家，唉调整心情了…

作者: apolloinzurich 时间: 2017-9-19 18:44
LZ你说的树的年轮是不是跟这篇比较接近呀？

Tropic trees tell an age-old story

You can tell how old a tree is simply by counting its rings, which reflect the changing seasons. However, things are less straightforward when it comes to tropical trees, since there are no summers and winters to mark the passage of time. Now scientists have worked out a simple way to tell the age of trees from the tropics, according to Nature.

Currently, factors such as the width of tree rings in temperate zones are used to provide a detailed record of climate conditions for the past 1 000 years or so. But only a few types of trees in the tropics have visible rings: the variances between wet and dry seasons are too slight to leave a distinguishable mark.
Until now, scientists have depended on measurements of oxygen and carbon isotypes to determine their age, but Pascale Poussart, a geochemist at Princeton University in New Jersey, and her colleagues, have shown that an apparently ringless Miliusa velutina tree from Thailand does have rings... they're just invisible.

Using X-ray beams focused on wood samples, the researchers looked at calcium, a mineral that trees take up during their main growing season. They revealed annual peaks dating back to 1909.

Although the results were in line with carbon isotope measurements, the calcium method is much quicker. "It took us just one afternoon in the synchrotron to produce the record," says Poussart. "The isotope record cost four months of lab time."

The team doesn't yet know whether seasonal calcium cycles are common, or if the feature is specific to just a few types of trees. And it is unclear whether periods of drought, or the modest and patchy dry seasons that feature in some areas of the tropics, will make the signal undecipherable.

In search of answers, Poussart will be working with scientists at the Smithsonian Tropical Research Institute's Center for Tropical Forest Science, who run long-term forest monitoring programmes in Africa, Asia and Latin America.

At the moment, much about tropical systems is a mystery, so anything that helps measure time will make an important contribution to the understanding of tropical forest dynamics.

作者: kaworu_zhang 时间: 2017-9-19 20:02

apolloinzurich 发表于 2017-9-19 18:44
LZ你说的树的年轮是不是跟这篇比较接近呀？

Tropic trees tell an age-old story

同意！

作者: kaworu_zhang 时间: 2017-9-19 20:04

apolloinzurich 发表于 2017-9-19 18:44
LZ你说的树的年轮是不是跟这篇比较接近呀？

Tropic trees tell an age-old story

同意！

作者: apolloinzurich 时间: 2017-9-19 20:18

kaworu_zhang 发表于 2017-9-19 20:04
同意！

多谢确认楼主不要灰心加油加油！

作者: GodPlzzzz 时间: 2017-9-19 20:59
楼主加油！下次一定考好成绩！

作者: gar_bbbbb 时间: 2017-9-20 02:12

kaworu_zhang 发表于 2017-9-19 20:04
同意！

lz，求问原文有难的单词吗？？

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