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Scientists Explain Why Taxing Mental Work Wears You Out_我的网站

新白娘子传奇

一 | A team of scientists has discovered a likely explanation for why one may feel exhausted after engaging in intense cognitive work.,In their study, published in the Current Biology last week, the researchers argue that intense cognitive work, when it lasts for several hours, results in the buildup of potentially toxic byproducts in the prefrontal cortex part of the human brain, which then affects a person’s behavior.,“Influential theories suggested that fatigue is a sort of illusion cooked up by the brain to make us stop whatever we are doing and turn to a more gratifying activity,” Mathias Pessiglione of Pitié-Salpêtrière University in Paris, said as quoted in a news release by Cell Press. “But our findings show that cognitive work results in a true functional alteration—accumulation of noxious substances—so fatigue would indeed be a signal that makes us stop working but for a different purpose: to preserve the integrity of brain functioning.”,During the course of their research, the team employed magnetic resonance spectroscopy to monitor the brain chemistry of two groups of people during a workday, with one group performing easy cognitive tasks while the other engaged in more complex mental activities.,Only the latter group ended up exhibiting signs of fatigue, as well as a tendency to favor “options proposing rewards at short delay with little effort,” as the news release put it.,AmericasChild Survives After 7 Minutes Without Blood Flow to Brain During Surgery, US Cardiologist Reveals11 August, 16:41 GMT,Furthermore, members of that group had higher levels of glutamate in the synapses of the prefrontal cortex, leading the researchers to suggest that the accumulation of glutamate “makes further activation of the prefrontal cortex more costly,” and thus a mentally exhaustive workday makes cognitive control more difficult.,Unfortunately, there seems to be no fancy way to deal with this problem other than the tried and tested method that is probably as old as history itself.,“I would employ good old recipes: rest and sleep!” Pessiglione remarked. “There is good evidence that glutamate is eliminated from synapses during sleep.”。

周二拜登宣布向180亿美元中国商品，包括电动汽车、半导体、太阳能和电池，加征关税。

经过测算，这些关税大约会使得美国的通胀同比增长一个基点，也就是0.01个百分点，对GDP的拖累也同样是一个基点，都可以忽略不计。因为4月通胀下行，市场预期9月降息，美股创出新高。

二 | 影响不大的主要原因就是之前对中国电动汽车征收的25%的关税，使得原本中国对美国出口就很少。去年中国向美国出口了大约3.7亿美元的电动车，欧盟向美国出口了近 75 亿美元。中国仅占美国进口电动汽车的2%。德国、韩国和日本的占比分别为22%、21%和18%。采取加征关税减少竞争的方法来保护电动汽车，只会让美国汽车制造商进步缓慢。而且美国现在严重依赖中国生产的电池，加征关税只会使得整车成本更贵，美国想买电动车的老百姓就只能支付更高价格了。在海外市场，中国电动车都可以凭借价格和技术取胜。美国车将一步步被边缘化，美国新能源产业会越来越落后。2020年大选，拜登猛烈抨击特朗普向中国3000亿美元进口商品的征税，严重伤害了美国，因为95%以上的关税都是由美国企业和家庭承担的。