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形形色色(3)  

2009-10-17 22:21:19|  分类: 默认分类 |  标签: |举报 |字号 订阅

  下载LOFTER 我的照片书  |

1、男生理科成绩比女生好么?

我在最近几年改变了对女生从事理科的看法。有很长一段时间我觉得男性更适合从事科学研究,从我个人的观察以及阅读H. Georgi的ppt,我觉得女生如果表面上看起来理科不如男生,那也是因为社会和心理的因素。H. Georgi在哈佛带出了不少杰出的女物理学家,最出名的就是Lisa Randall。

上面给的链接介绍了最近一篇研究论文。我摘一段这篇博文:

从实际的学习成绩来看,似乎男生更好些。在全世界范围的调查发现,男中学生的理科成绩比女生好。但不同国家理科成绩的男女差异的差别很大。比如在一项国际 数学和科学学习趋势 报告中(Trends in International Mathematics and Science Study, TIMSS),在所研究的34个国家中有3个国家的女生的理科成绩显著高于男生。这似乎说明一些社会文化因素会影响男女生在理科成绩上的差异。 另一个因素是心理上的,即人们对性别-学科关系的看法。如果人们认为男性更适合理科而女性更适合文科,那么男生可能就会更有兴趣学习理科,从而导致成绩更 好。那么,男女生理科成绩的差异是由人们对性别-学科刻板印象造成的么?最近一篇发表在PNAS的文章研究了这个问题。

2、睡眠睡眠

还是睡眠。我老了,总是觉得缺乏睡眠对白天工作的影响是很大的,这里有两篇继续谈睡眠的文章:

The Why of Sleep

Sleep Gone Awry

充足的睡眠有很多好处,但为什么人需要睡眠?还有很多争论。睡眠的好处之一是

Others agree that sleep plays an important role in regulating the immune system. In fact, sleep may have evolved to improve the immune system’s ability to fight off parasites, argue Patrick McNamara of Boston University and his colleagues in the Jan. 9 BMC Evolutionary Biology.

Species of animals that spend more time sleeping each day tend to have higher counts of infection-fighting white blood cells, a database analysis revealed. The more sleep on average a species gets, the fewer parasites plague its members, and the parasites that do infect longer-sleeping species are not as prevalent in their populations as parasites that sicken shorter-sleeping species.

3、超颖材料与黑洞

最近几年超颖材料(metamaterials)越来越热,从隐形斗篷到模拟引力场如黑洞。最近,中国的崔铁军等人根据Evgenii Narimanov和Alexander Kildishev的理论建议做出了模拟黑洞的超颖材料(微波波段)

First black hole for light created on Earth

摘要

A theoretical design for a table-top black hole to trap light was proposed in a paper published earlier this year by Evgenii Narimanov and Alexander Kildishev of Purdue University in West Lafayette, Indiana. Their idea was to mimic the properties of a cosmological black hole, whose intense gravity bends the surrounding space-time, causing any nearby matter or radiation to follow the warped space-time and spiral inwards.

……

Now Tie Jun Cui and Qiang Cheng at the Southeast University in Nanjing, China, have turned Narimanov and Kildishev’s theory into practice, and built a “black hole” for microwave frequencies. It is made of 60 annular strips of so-called “meta-materials”, which have previously been used to make invisibility cloaks.

科学网的介绍:崔铁军等打造人造黑洞 有望用于太阳能发电

我们下个礼拜将放出一篇文章,建议用超颖材料研究宇宙学。我们计算了de Sitter时空中的光子场的Casimir energy,得到类似全息暗能量的结果。如果能造出超颖材料,就可以验证我们的预言。敬请大家期待这篇文章。

4、Quantum computers could tackle enormous linear equations

摘要

The new quantum algorithm is “head-smackingly good,” says computer scientist Daniel Spielman of Yale University. “It is both very powerful, and very natural. I read the abstract and said, ‘Why didn’t I think of that?’”

In the new study, Aram Harrow of the University of Bristol in England along with Avinatan Hassidim and Seth Lloyd, both of MIT, propose that large datasets of linear equations could be encoded in quantum forms, such as the spins of nuclei, individual atoms or photons. Such a system would allow quantum computers to handily solve problems made up of billions or even trillions of variables (such as the x’s, y’s and z’s that plague algebra students).

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