Daniel Lemire's blog

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Science and Technology links (November 24th 2018)

  1. There is no association between birth order and personality traits:

The results of both within- and between-family research designs revealed no consistent evidence of a link between birth order and the personality traits of extraversion, neuroticism, agreeableness, conscientiousness, and openness.

  1. Most modern cultures use numbers based on a decimal system (base 10). However, in many European languages (e.g., French and Danish) the number 20 is used as a base (eighty in French is four-twenty). We call such system vigesimal. They are common in Africa. The Maya counted in base 20. I am told that the Gauls used a vigesimal system, but I could not find a credible supporting source (the Gauls also used Greek and Latin).
  2. Can you build an airplane with no moving part? It turns out that you can. Researchers built a model airplane that moves the air using an electric field. (credit: degski)
  3. Many of our everyday plastic items (like plastic bottles) contain a chemical called BPA. Our bodies can ingest it, but it is evacuated within hours. There has been an intense lobby to ban it in the spirit of the precautionary principle; it does affect mice (causing genetic mutations in offsprings) but there is no proof that it harms human beings. Should you buy goods that are said to be BPA-free? They are made with alternative chemicals, so the question is whether these alternative chemicals are safer. Horan et al. provide evidence that the alternatives can be harmful.
  4. It is expected that Japan will grow more dependent on coal in the coming decades, it is currently generating a third of its electricity using coal. Germany produces 40% of its electricity using coal.Coal’s popularity can be explained in large part by how nuclear power is failing us.
  5. We subsidize electric cars because we assume that they are more environmentally friendly. They certainly lack an exhaust pipe which is great for people around the car. Electric cars make it easy to “export” pollution: you can keep dense cities or even entire countries cleaner… But the batteries and their toxic chemicals must still end up somewhere.What is the larger picture? If you care only about climate change, then electric cars are slightly beneficial, as long as you are not producing your electricity from coal…

When powered by average European electricity, electric vehicules are found to reduce global warming potential by 20% to 24% compared to gasoline and by 10% to 14% relative to diesel under the base case assumption of a 150,000 km vehicle lifetime. Electric vehicules powered by coal electricity are expected to cause an increase in global warming potential of 17% to 27% compared with diesel and gasoline ICEVs. Hawkins et al., 2012

Yet if you care about other types of environmental impacts, electric cars may be less beneficial…

the acidification, eutrophication, human toxicity, and particulate matter formation caused by Electric vehicles are higher than those caused by internal combustion engines .
(Bicer et Dincer, 2018)

  1. Professors get to spend only a tiny minority of their time on their own research.. The more experience the professor, the less time they have for their own research. PhD students have a lot more time for research.I believe that it is a form of institutional aging.
  2. Older people (age 75 and older) are often out of shape, but it gets worse during hospitalization. Staying in a hospital bed for a long time is bad for you. It seems that the ill effects of hospitalization can be reverse with an exercise routine.
  3. There is no scientific evidence that depression is due to a chemical imbalance:

Thanks in part to the success of direct-to-consumer marketing campaigns by drug companies, the notion that major depression and allied disorders are caused by a chemical imbalance of neurotransmitters, such as serotonin and norepinephrine, has become a virtual truism in the eyes of the public (…) the evidence for the chemical imbalance model is at best slim (…) There is no known optimal level of neurotransmitters in the brain, so it is unclear what would constitute an imbalance. Nor is there evidence for an optimal ratio among different neurotransmitter levels. Moreover, although serotonin reuptake inhibitors, such as fluoxetine (Prozac) and sertraline (Zoloft), appear to alleviate the symptoms of severe depression, there is evidence that at least one serotonin reuptake enhancer, namely tianepine (Stablon), is also efficacious for depression (Akiki, 2014). The fact that two efficacious classes of medications exert opposing effects on serotonin levels raises questions concerning a simplistic chemical imbalance model.

  1. Some Intel processors can run at up to 5 Ghz. That is, they run through 5 cycles per nanosecond. We are not likely to see much faster speeds in the near or medium term.
  2. After rising from about 300$US in mid-2016 to over 20,000$US in early 2018, the price of Bitcoin is currently (as I write this) 4337$US, and falling.