Archive for video

Les Grandes Jorasses, from 342 to 2 hours

Posted in Mountains with tags , , , , , , , , , , on September 7, 2018 by xi'an

Last month Dani Arnold, a Swiss climber, climbed the classic Cassin route of Les Grandes Jorasses [in my dreams!] in two hours (and obviously completely free-solo, with no protection whatsoever). This route was opened by Cassin, Esposito and Tizzoni, 1938, is part of the three great north walls of the Alps, with Eiger and Matterhorn, and is graded TD+/ED1, IV, 5c/6a, A1, for a vertical climb of 1200m. It is an extremely challenging and engaged climb, with almost no possibility to escape once started, and climbing parties often take more than a day to complete the climb. On his way up, Arnold passed nine groups of climbers. Here is another video of his in Scotland, when repeating for the first time Anubis, a mixed climbing route on Ben Nevis. (The title of the post is relating to Desmaison’s 342 heures dans les Grandes Jorasses.)

my next vacations location [with no bike]

Posted in Statistics with tags , , , , , , , on July 2, 2017 by xi'an

musical break

Posted in Books, Kids with tags , , , , , on January 4, 2015 by xi'an

During the Yule break, I listened mostly two CDs, the 2013  If you wait, by London Grammar, and The shape of a broken heart, by Imany. Both were unexpected discoveries, brought to me by family members, but I enjoyed those tremendously!

Banff workshop [BIRS 12w5105 meeting [#2]]

Posted in Mountains, pictures, Statistics, Travel, University life with tags , , , , , , , , , on March 21, 2012 by xi'an

Today the program of 12w5105 was more on the theoretical side with adaptive MCMC in the morning and ABC in the afternoon. Éric Moulines and Gersende Fort shared a talk on two papers, one on adaptive tempering and the other one on equi-energy sampling, then Nando de Freitas spoke first about Gaussian process approximation for Bayesian optimisation, then about an adaptive Hamiltonian technique called Sardonics. And Jeff Rosenthal concluded the morning with a review of the results ensuring convergence for adaptive MCMC (with a delightful counter-example called Stairways to Heaven that reminded me of an ice climb in Utah!). After my talk, where Scott Sisson made an interesting comment on the difficulty to extend our framework to a large collection of models (since then the summary statistics have to differ), François Perron discussed in highly interesting details several approximation techniques for the Bayesian estimation of copulas and Scott Sisson presented his recent arXiv paper where a rough estimate of the joint posterior is obtained regression-adjustment ABC, and then estimates of each marginal posterior distribution are separately obtained in a lower-dimensional analysis, all this being connected with Bayes linear analysis. (I do not completely get the way summary statistics are selected for each marginal there, which seems to be done by hand. While I understand why using a lower-dimensional statistic helps in improving the approximation of the marginal posteriors and fights the curse of dimensionality, the fact that the joint posterior sample is based on different summary statistics for the different components makes an interesting statistical puzzle. Maybe the copula approach by François in the previous talk could be used at the final stage.) The final talk by Zhiqiang Tan on comparative performances of resampling and subsampling strategies generated a very animated discussion. (All talks being recorded, mine is available as an mp4 video but watch at your own peril!)

Introducing R on video

Posted in R, Statistics, University life with tags , on March 10, 2010 by xi'an

Darren Wraith pointed out to me this site proposing a whole series of videos introducing to R. (Unfortunately in a Windows environment.) This can be handy when facing students with no R background…