Archive for France

Nature squeakbits [26 February 2026]

Posted in Books, pictures, Running, Travel with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , on April 16, 2026 by xi'an

In this issue of Nature, uncovering the fundamental (and Ig-Nobel worth) reason why basketball shoes are squeaking, the reason being a shockwave travelling through the sole!, two tribunes against nuclear testing and “must & should” towards a successor to the START treaty… While we should ask & act for a global and if not unilateral nuclear disarmament! This alas coïncides with France announcing the increase of its nuclear arsenal and the extension of its “umbrella” to several EU countries…

And another coverage of the deplorable Trump administration dismantling the biodefense and pandemic preparedness branches of the US NIAID, presumably a late under-the-belt jab at the national institute Anthony Fauci directed for 38 years. Meaning one of the forefronts for pandemic research and vaccine development has been dismantled. Plus the US EPA revoking the 2009 statement that climate change is endangering the US population and removing greenhouse-gas emission rules. In tune with the Drill, baby, drill! motto of the Trump supporters more interested in their short-term profits than in the long-term (no-)future of the country. Paradoxically sitting in the same issue as a comment calling for a policy-making assessment of avoidable climate-change risks. Illustrated by London’s drownin’ below

And a summary of their conclusions from 23 of the 27 members (from 27 countries) of the Scientific Advisory Group for the Origin of Novel Pathogens for the WHO. After 3.5 years of debate on the origin of COVID-19! Four hypotheses are examined and other hoaxes and conspiracies are debunked.

Another political entry about the EU and its Horizon Europe programme (that is funding my ERC Synergy grant) baring (researchers from) Chinese research organisations from applying for its grants in sensitive methodologies, in order to prevent “the undesired transfer of IP”. Following similar and earlier actions in the US with the (newspeak!) China Initiative launched by Trump 1.0 that turned into a witch hunt.

An exciting 228 metres of rock and mud providing a window on the past 23 million year weather. Obtained from the West Antarctica Ice Sheet.

incoming mostly Monte Carlo [14 April, PariSanté campus]

Posted in pictures, Statistics, University life with tags , , , , , , , , , , , , , , , on April 9, 2026 by xi'an

The next Mostly Monte Carlo seminar will be this very Friday, 10/04/26, at PariSanté Campus. With Shiva Darshan and Pierre Monmarché speaking on the following topics:
15h: Shiva Darshan Maximal-reflection couplings on manifolds: some specific examples
Explicit Markovian couplings can be used to build Markov Chain Monte Carlo methods such unbiased MCMC or coupling based control variates. For sampling from probability measures supported on Euclidean space, one typically uses a synchronous coupling, a maximal-reflection coupling (also known as a discrete-time sticky coupling), or some variant of the two. For probability measures supported on Riemannian manifolds, the situation is less clear cut. While the Kendall-Cranston coupling of Brownian motions on manifolds has been successfully applied in theoretical works, it is ill-suited for building explicit algorithms. In this talk, we will discuss some of the obstacles to extending Euclidean maximal-reflection couplings to manifolds and present some special cases for which these obstacles can be easily overcome. With applications to Stereographic MCMC in mind, we detail particular couplings of random walks on the sphere.
16h: Pierre Monmarché A post-sampling reweighting method for multi-modal target measures
Even when the modes are identified and sampled locally with MCMC methods, a difficulty to sample multi-modal measures is to correctly estimate the relative probabilities of each of these modes, which requires to observe many transitions between them (which are rare events). We will present an approach based on variational inference which exploits the local samples, aiming only at estimating the relative weights between them. When the modes are well separated, this amount to some entropy estimations.

under wraps, if not enough for Nature

Posted in Books, Mountains, pictures, Travel, University life with tags , , , , , , , , , , , , , , , , , , , , , , on March 21, 2026 by xi'an

In its 01 January 2026 issue, Nature covers a current exhibit at the Musée de l’Homme, Paris, on mummies (or momies in French), incl. an Assassin’s Creed interactive device! With a complaint that the exhibit discloses too much about the individuals behind (or before?) the mummies, incl. age, cause of death and sometimes a scan… I find the complaint rather weird in that the individuals have been mummified for hundreds or thousands of years, mostly from cultures that have themselves vanished. (Note: As an atheist, I do not believe in an absolute “sanctity” of corpses and hope my dead body will be put to use for organ donations and medical student practice. The more so because people often have less concern for the living, just like anti-abortion activists rarely care about the children born from mothers denied a right to abortion.) Part of the article message is actually about de-colonising museums, even though transferring mummies back to where they were found does not include time travel to recreate the conditions the (hopefully) dead individuals were processed. (Note: As a universalist, I do not see much rationale in deeming multiple generation descendants (which ones?) or related ethnic groups having more say about handling these remains.) Which also bring to mind a puzzling, caricatural, “Perspective” Nature article in the 07 January 2026 issue arguing that conservation (towards protecting endangered species) is driven by “Western science”, colonialist, racist and marginalizing indigenous communities. Acknowledged as inspired by the Black Lives Matter movement and submitted in 2021, I am surprised the article ever got accepted given its focus on ideology rather than (universal) science, e.g., when referring to Michel Foucault’s theories as essential to conservation theory and practice or in opposing trophy hunting bans as providing income for communities. The nadir being the play on RACE (for rights, agency, challenge, and education) as the acronym for the supported model for conservation. (Note: As a frequent traveller, I do realise the tension between conservation of endangered animal populations and the survival needs of local communities. During our last trip to India, we had a hugely educative conversation with a Kerala farmer family, where they complained about the damages from and the dangers of local elephants on crops, as well as monkeys on their cocoa plantation, to the point they were considering giving up that crop.)

three golds for French biathlon!

Posted in Mountains, pictures, Running with tags , , , , , , , on February 20, 2026 by xi'an

journée de la laïcité (120yo)

Posted in Kids, pictures with tags , , , , , , , , , on December 9, 2025 by xi'an