Archive for jetlag

back from Japan [flotsam, jetsam, lagan, and derelict]

Posted in Books, Mountains, pictures, Running, Travel with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , , , on August 8, 2026 by xi'an

Our last day in Japan was wrecked by Japan Airlines, as our JAL flight from Sapporo to Tokyo Haneda got delayed by five hours… The worst part was being kept in the dark about the delay till the initial departure time and then more as the actual departure time was only given hours later. An opportunity to find out that EU rules about flight compensations and passenger rights do not have a Japanese equivalent..! The only plus side of spending the day at the airport was enjoying a sashimi meal at the Sapporo airport. The next day, the erupting Krasheninnikov volcano in Kamtchatka caused a slight change of flight on the way (North!) back to Paris but Air France still managed a 45mn gain on the planned arrival time. And hardly any jetlag in the following days, as opposed to the unusually long accustomisation through the nights in Nagoya and Tachikawa.

This was the only major hitch of our trip, besides a rental car delay for missing the official translation of our driving licences. Visiting both the Japanese Alps and the island of Hokkaido was a fantastic opportunity, thanks to ISBA 2026. Along enjoying the views and hikes in both locations, I could not refrain from making a connection between the geographies and histories of the Ainus on Hokkaido and of the Haidas in the Pacific Northwest, as they both got colonised and forcibly integrated at about the same epoch, with salmon canning companies enslaving them. The settlers were demoted Union soldiers in one case and former samurais (tondenhei) in the other. Small towns on Hokkaido had some similarities with those of the American and Canadian West, with one-street layout and plenty of space between houses, except for these spaces being intensely cultivated as all of the valleys I saw during that trip. (But very little wildlife, with a single sorry-looking fox, two fleeing monkeys, a single, inquisitive, squirrel, a few deers and no bear.)

On the mountains (and volcanoes) trails, I was impressed by the involvement and preparedness of most Japanese hikers, often quite senior, in climbing volcanoes and facing bear encounters, which also made me discover a very nice local outdoor brand, Mont Bell. (Also finding out that TNF Japan© is a separate franchise with its own products.) And adopt the hiking uniform of wearing shorts and tights, which proved surprisingly comfortable!

Due to a thrombosis scare, I further had the opportunity to visit (again!) the local hospital in Omachi, Nagoya Prefecture, if getting there by bike rather than by water-ambulance. With hugely efficient processing despite the language barrier (except for the doctor with whom I briefly spoke of Mont-Saint-Michel!). And the conclusion of no thrombosis, phew!

a journal of the COVID²⁵ year

Posted in Books, Statistics, Travel with tags , , , , , , , , , , , , , , , , on September 14, 2025 by xi'an

 Last week, I got COVID for the very first (detected) time! Although it took a while to realise this was COVID and not the common cold. It started with an overnight runny nose that I attributed to swimming outside the previous and cool morn, a minor temperature shock compared with the previous week in Guadeloupe. And did not spot the unusually high heart rate that night… The next afternoon, I was feeling a bit feverish (with no fever!) and definitely tired, but again attributed the feeling to faster bike rides to and from Paris Dauphine and the after-effect of Caribean jetlag. I then had a very long night and definitely felt okay the morning after (with nightly heart rate back to normal). It is only when my wife starting showing the same symptoms that I suspected more than a common cold. With confirmation from a COVID test two days later. By then I had unfortunately contaminated a few other people,  all of whom recovered reasonably fast (phew!). I have since taken back to wear a face mask in any close encounter and warned my students. I wonder if I got it in the plane back or at Dauphine on the opening day. Definitely planning the continuation of my yearly vaccine next November!!!

2023 Workshop in honour of Professors Donald Poskitt and Gael Martin

Posted in Statistics, University life with tags , , , , , , , , , , , , on November 29, 2023 by xi'an

BNP13

Posted in Mountains, pictures, Running, Statistics, Travel with tags , , , , , , , , , , , , , , , , on October 28, 2022 by xi'an

BNP13 is set in this incredible location on a massive lake (almost as large as Lac Saint Jean!) facing several tantalizing snow-capped volcanoes… My trip from Paris to Puerto Varas was quite smooth if relatively longish (but I slept close to 8 hours on the first leg and busied myself with Biometrika submissions the rest of the way). Leaving from Paris at midnight proved a double advantage as this was one of the last flights leaving, with hardly anyone in the airport. On Sunday, I arrived early enough to take a quick dip in Lake Llanquihue which was fairly cold and choppy!

Overall the conference is quite exhilarating as all talks are of interest and often covering on-going research. This may be one of the most engaging meetings I have attended in the past years! Plus a refreshing variety of topics and seniority in the speakers.

To start with a bang!, Sonia Petrone (Bocconi) gave a very nice plenary lecture in the most auspicious manner, covering her recent works on Bayesian prediction as an alternative way to run Bayesian inference (in connection with the incoming Read Paper by Fong et al.). She covered so much ground that I got lost before long (jetlag did not help!). However, an interesting feature underlying her talk is that, under exchangeability, the sequence of predictives converges to a random probability measure, a de Finetti way to construct the prior that is based on predictives. Avoiding in a sense the model and the prior on the parameters of that process. (The parameter is derived from the infinite exchangeable [or conditionally iid] sequence, but the sequence of predictives need be defined.) The drawback is that this approach involves infinite sequences, with practical truncation to a finite horizon being an approximation whose precision / error may prove elusive to characterise. The predictive approach also allows to recover a limiting Normal distribution (not a Bernstein-von Mises type!) and hence credible intervals on parameters and distributions.

While this is indeed a BNP conference (!), I was surprised to see lot of talks paying attention to clustering and even to mixtures, with again a recurrent imprecision on the meaning of a cluster. (Maybe this was already the case for BNP11 in Paris but I may have been too busy helping with catering to notice!) For instance, Brian Trippe (MIT) gave a quick intro on his (AISTATS 2022) work on parallel MCMC with coupling. As unbiased MCMC strongly improving upon naïve parallel MCMC relative to the computing cost. With an interesting example where coupling is agnostic to the labeling of random partitions in clustering problems, involving optimal transport, manageable in O(K³log(K)) time when K is the number of clusters.

Microsoft cares!

Posted in Travel, University life with tags , , , , , on August 2, 2022 by xi'an