Archive for the Books Category

40th anniversary of the abolition of death penalty

Posted in Books, Kids, pictures with tags , , , , , , , on September 18, 2021 by xi'an

quantum computing reproducibility crisis?

Posted in Books, Statistics, Travel, University life with tags , , , , , , , , on September 16, 2021 by xi'an

While standing in a train to my mother’s house in Brittany, I was catching up on earlier Nature issues and came upon this April issue where, following the retraction of a Nature paper on the topic, Sergey Frolov casts doubt on the possible detection of a new type of quantum particle, the Majorana fermion, whose existence still remains inconclusive. The criticism concentrates on the data analysis of signals where the appearance of a narrow peak should support the hypothesised existence. The article is interesting (to me) as a reflection of someone having published positive, then negative articles on the topic, upon the tendency for authors in the field to cherry-pick experiments where some peaks occur. Among dozens or hundred of experiments where they did not. And calling for open data and more stringent review(er)s on the matter (and others). The arguments in the opinion tribune sound most reasonable but I wonder whether or not other particle physicists share the same concern.

and it only gets worse

Posted in Books, Kids, Travel with tags , , , , , , , , , , , on September 15, 2021 by xi'an

“The law, known as Senate Bill 8, amounts to a nearly complete ban on abortion in Texas, one that will further fuel legal and political battles over the future of Roe v. Wade, the 1973 decision that established a constitutional right to abortion. The law makes no exceptions for pregnancies resulting from incest or rape.” NYT, Sept. 1

“The [Supreme] Court’s order is stunning,” Justice Sonia Sotomayor wrote in her dissent. “Presented with an application to enjoin a flagrantly unconstitutional law engineered to prohibit women from exercising their constitutional rights and evade judicial scrutiny, a majority of justices have opted to bury their heads in the sand.” NYT, Sept. 2

“A judge in Ohio ordered a hospital to treat a Covid-19 patient with ivermectin, despite warnings from experts that the anti-parasitic drug has not proved effective against the virus and can be dangerous in large doses.” The Guardian, Aug. 31

“More than half of the world’s people have no social protections, the United Nations has warned, even after the pandemic pushed many governments to offer services to their populations.” The Guardian, Sept. 1

words on the wall [jatp]

Posted in Books, Kids, pictures, Travel with tags , , , , , , on September 12, 2021 by xi'an

mixed feelings

Posted in Books, Kids, Statistics with tags , , , , on September 9, 2021 by xi'an

Two recent questions on X validated about mixtures:

  1. One on the potential negative explosion of the E function in the EM algorithm for a mixture of components with different supports:  “I was hoping to use the EM algorithm to fit a mixture model in which the mixture components can have differing support. I’ve run into a problem during the M step because the expected log-likelihood can be [minus] infinite” Which mistake is based on a confusion between the current parameter estimate and the free parameter to optimise.
  2. Another one on the Gibbs sampler apparently failing for a two-component mixture with only the weights unknown, when the components are close to one another:  “The algorithm works fine if σ is far from 1 but it does not work anymore for σ close to 1.” Which did not see a wide posterior as a possible posterior when both components are similar and hence delicate to distinguish from one another.