Why buses bunch up

Queues are a fact of everyday life and understanding what makes the length of lines vary and how to minimize wait times is of course an important factor for any establishment that has to deal with customers. One of the things that fascinated me in my first statistics course was queuing theory that dealt with this very question. I remember one particular insight. If you look at any train or subway station that has three escalators that carry people between the platform and the street, you will find that it is almost always the case that two of them are going from the platform to the street level and only one the other way. This does not matter if the street level is above or below the platform, nor does it depend on the time of day. The reason is quite simple. People coming to catch a train arrive at random times and thus can be accommodated with a single escalator but when a train arrives at a station, it disgorges a whole bunch of people at once and this requires more exit capability. The 2-1 arrangement is designed to take care of that.
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How fat cells work

I have long been curious about what happens to the body when we gain and lose weight. People talk about ‘fat cells’ but I was not clear as to whether we have a relatively fixed number of such cells and weight fluctuations simply consist of the size of these cells changing, or whether the number of cells also changed. David Prologo, a professor of radiology and imaging sciences at Emory University, has a nice article explaining what is going on when we gain and lose weight.
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What drives the ‘Flat Earth’ belief?

When I was a young boy in Sri Lanka, there was a Jesuit priest-in-training named Basil, a friend of the parents of a friend of mine, who liked to argue with us that the Earth was flat. We of course believed that it was round but as anyone who has argued with a flat-Earther knows, they have quite an array of arguments that they can drop on you to counter your objections and it is a good example of how almost any proposition can be defended if one is allowed to make ad hoc assumptions. We suspected that Basil did not really believe what he was saying but was using the formidable argumentative skills that Jesuits learn to mess with our young minds and show how hard it is to defend even what seem to be obvious truths.
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The Stanford prison experiment is not what it seemed

Many of you will have heard of the famous Stanford prison experiment in 1971 when Philip Zimbardo, a psychology professor at Stanford University, randomly assigned one group of students to be inmates and the other group to be guards who had total power over the prisoners for two weeks. The setting was a mock prison (actually the basement of a university building). But after six days the experiment had to be called off because, as claimed by Zimbardo, the ‘guards’ used such sadistic methods against the ‘inmates’ that the latter were on the verge of breakdowns. The experiment has been cited numerous times to warn of the dangers of giving people unchecked power over others and the need for prison reform.
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How a child can have DNA from three people

Jennifer Barfield, a professor of assisted reproductive technologies at Colorado State University, clearly explains how it can come about and what led to the development of the technology that has made it possible. The key point is that in addition to the DNA that comes from the father and the mother, the fertilized egg also contains mitochondrial DNA (mtDNA) that plays a vital role in producing energy.
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Einstein’s controversial views on race

Albert Einstein’s travel diaries that he maintained on his travels in China and Japan and Sri Lanka (then Ceylon) in 1922-1923 have just been published and they contain descriptions of what he saw that are deeply at odds with the enlightened views we normally associate with him. He makes statements that can at best are described as xenophobic and at worst as racist.
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The curious Cuba-China-Russia conspiracy theory promoted by the New York Times

Readers may recall my post from back in February about the mysterious sounds that were causing headaches (literally) to US embassy personnel in Cuba. It led to all manner of speculations about the Cubans themselves unleashing, or allowing some other nation to unleash, some high tech Cold War-type sonar devices on them. The fact that the evidence produced was highly vague and that the Cubans had no motive for doing such things did not stop the wild speculations.
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The awesome beauty and power of a tornado

This video of a tornado touching down in Laramie, Wyoming last week is awe-inspiring. I had thought that tornados start in the clouds and then touch down on the ground but in this video at the 18-second mark you see that there is also a bottom-up element, a sliver that starts on the ground and joins to the larger part coming from the top. The tightness of the funnel cloud is indicative of the massive destructive power that it can unleash for anyone and anything that has the misfortune to lie in its narrow path.