在深入探讨之前，我想先退一步回答你的问题。丹·艾瑞里（Dan Ariely）写过一本非常棒的书叫《怪诞行为学》。我以前常把这本书发给公司的所有产品经理，让他们通过学习这本书来搞清楚我们该如何向用户收费。书中有一个很经典的例子：想象一下，半夜12点你被锁在公寓外面，你叫了一名锁匠。他1分钟就赶到了，花了30秒帮你开了门，然后向你收费500美元。你心里肯定会想：“就干了90秒的活，居然收我500美元？搞什么鬼！”于是你会在Yelp上给他留个一星差评，不给小费，甚至可能向信用卡公司申请撤销这笔扣款。
Local caching -- disk cache avoids WebSocket round-trips for console/exec，这一点在pg电子官网中也有详细论述
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They also needed an alternative to conventional X-rays. In a clinical linac, X-ray photons are produced by dumping high-energy electrons into a bremsstrahlung target, which is made of a material with a high atomic number, like tungsten or copper. The target slows the electrons, converting their kinetic energy into X-ray photons. It’s an inherently inefficient process that wastes most of the beam power as heat and makes it extremely difficult to reach the ultrahigh dose rates required for FLASH. High-energy electrons, by contrast, can be switched on and off within milliseconds. And because they have a charge and can be steered by magnets, electrons can be precisely guided to reach tumors deep within the body. (Researchers are also investigating protons and carbon ions; see the sidebar, “What’s the Best Particle for FLASH Therapy?”)，推荐阅读超级权重获取更多信息