Archive for Highlands

Eilean Donan Castle [jatp]

Posted in Statistics with tags , , , , , on August 13, 2017 by xi'an

Old Man of Storr [jatp]

Posted in Mountains, pictures, Running, Travel with tags , , , , , , on August 11, 2017 by xi'an

sunset on Skye [jatp]

Posted in Mountains, pictures, Running, Travel with tags , , , , , , , , on July 31, 2017 by xi'an

Glencoe skyline: my dream race!

Posted in Mountains, pictures, Running, Travel with tags , , , , , , , , , , on September 26, 2015 by xi'an

I came upon the news by mere chance: the first Salomon Glencoe skyline mountain race took place last month, on Aug. 22, in one of my favourite mountaineering spots, the Valley of Glencoe. I have hiked and climbed in this valley six or seven times, and “bagged” seven of the nine local Munroes, mostly in Winter conditions. The race includes all of them in a 53km route with a 4,256m total ascent (and descent!), with a scramble of Buachaille Etive Mor via the classic Curved Ridge route and the west-to-east traverse of the Aonach Eagach. Absolutely awesome!

The winners completed the route in 7:36 for Joe Symmons and 7:44 for Emelie Forsberg, with the last runner finishing in 14 hours. I really wish I could enter this race but the organisers screen quite thoroughly entrances based on past experience, insisting on previous mountain races, and so this must remain a dream..!

from top of Stob Choire down towards northern plateau, Glencoe, Apr. 21, 2012

icefalls on Ben Nevis

Posted in Mountains, pictures, Travel with tags , , , , , , , on January 31, 2015 by xi'an


benThe seminar invitation to Edinburgh gave me the opportunity and the excuse for a quick dash to Fort William for a day of ice-climbing on Ben alNevis. The ice conditions were perfect but there was alas too much snowdrift to attempt Point Five Gully, one of the mythical routes on the Ben. (Last time, the ice was not in good conditions.) Instead, we did three pitches on three different routes, one iced rock-face near the CIC hut, the first pitch of Waterfall Gully on Carn Dearg Buttress, and the first pitch of The Curtain, again on Carn Dearg Buttress.

The most difficult climb was the first one, grading about V.5 in Scottish grade, mCICaybe above that as the ice was rather rotten, forcing my guide Ali to place many screws. And forcing me to unscrew them! Then the difficulty got much lower, except for the V.5 start of the Waterfall, where I had to climb with hands an ice pillar as the ice-picks would not get a good grip. Breaking another large pillar in the process, fortunately mostly avoiding being hit. The final climb was quite easy, more of a snow steep slope than a true ice-climb. Too bad the second part of the route was blocked by two fellows who could not move! Anyway, it was another of those rare days on the ice, with enough choice to worry about sharing with other teams, and a terrific guide! And a reasonable dawaterfally for Scotland with little snow, no rain, plenty of wind and not that cold (except when belaying!).

icicles on the Ben

Posted in Mountains, pictures, Travel with tags , , , on January 25, 2015 by xi'an


computational methods for statistical mechanics [day #4]

Posted in Mountains, pictures, Running, Statistics, Travel, University life with tags , , , , , , , , , , , , , , , , on June 7, 2014 by xi'an

Arthur Seat, Edinburgh, Sep. 7, 2011

My last day at this ICMS workshop on molecular simulation started [with a double loop of Arthur’s Seat thankfully avoiding the heavy rains of the previous night and then] Chris Chipot‘s magistral entry to molecular simulation for proteins with impressive slides and simulation movies, even though I could not follow the details to really understand the simulation challenges therein, just catching a few connections with earlier talks. A typical example of a cross-disciplinary gap, where the other discipline always seems to be stressing the ‘wrong” aspects. Although this is perfectly unrealistic, it would immensely to prepare talks in pairs for such interdisciplinary workshops! Then Gersende Fort presented results about convergence and efficiency for the Wang-Landau algorithm. The idea is to find the optimal rate for updating the weights of the elements of the partition towards reaching the flat histogram in minimal time. Showing massive gains on toy examples. The next talk went back to molecular biology with Jérôme Hénin‘s presentation on improved adaptive biased sampling. With an exciting notion of orthogonality aiming at finding the slowest directions in the target and putting the computational effort. He also discussed the tension between long single simulations and short repeated ones, echoing a long-going debate in the MCMC community. (He also had a slide with a picture of my first 1983 Apple IIe computer!) Then Antonietta Mira gave a broad perspective on delayed rejection and zero variance estimates. With impressive variance reductions (although some physicists then asked for reduction of order 10¹⁰!). Johannes Zimmer gave a beautiful maths talk on the connection between particle and diffusion limits (PDEs) and Wasserstein geometry and large deviations. (I did not get most of the talk, but it was nonetheless beautiful!) Bert Kappen concluded the day (and the workshop for me) by a nice introduction to control theory. Making connection between optimal control and optimal importance sampling. Which made me idly think of the following problem: what if control cannot be completely… controlled and hence involves a stochastic part? Presumably of little interest as the control would then be on the parameters of the distribution of the control.

“The alanine dipeptide is the fruit fly of molecular simulation.”

The example of this alanine dipeptide molecule was so recurrent during the talks that it justified the above quote by Michael Allen. Not that I am more proficient in the point of studying this protein or using it as a benchmark. Or in identifying the specifics of the challenges of molecular dynamics simulation. Not a criticism of the ICMS workshop obviously, but rather of my congenital difficulty with continuous time processes!!! So I do not return from Edinburgh with a new research collaborative project in molecular dynamics (if with more traditional prospects), albeit with the perception that a minimal effort could bring me to breach the vocabulary barrier. And maybe consider ABC ventures in those (new) domains. (Although I fear my talk on ABC did not impact most of the audience!)