Archive for London

a day of travel

Posted in pictures, Running, Travel with tags , , , , , , on September 1, 2014 by xi'an

Bham2I had quite a special day today as I travelled through Birmingham, made a twenty minutes stop in Coventry to drop my bag in my office, went down to London to collect a most kindly loaned city-bike and took the train back to Coventry with the said bike… On my way from Bristol to Warwick, I decided to spend the night in downtown Birmingham as it was both easier and cheaper than to find accommodation on Warwick campus. However, while the studio I rented was well-designed and brand-new, my next door neighbours were not so well-designed in that I could hear them and the TV through the wall, despite top-quality ear-plugs! After a request of mine, they took the TV off but kept to the same decibel level for their uninteresting exchanges. In the morning I tried to go running in the centre of Birmingham but, as I could not find the canals, I quickly got bored and gave up. As Mark had proposed to lend me a city bike for my commuting in [and not to] Warwick, I then decided to take the opportunity of a free Sunday to travel down to London to pick the bike, change the pedals in a nearby shop, add an anti-theft device, and head back to Coventry. Which gave me the opportunity to bike in London by Abbey Road, Regent Park, and Hampstead, before [easily] boarding a fast train back to Coventry and biking up to the University of Warwick campus. (Sadly to discover that all convenience stores had closed by then… )

in the time of cholera

Posted in Books, Kids, pictures, Travel with tags , , , , , , , , , on April 6, 2014 by xi'an

when we were orphans

Posted in Books, Kids, Travel with tags , , , , on February 9, 2014 by xi'an

Kazuo Ishiguro’s The Remains of the Day is one of my favourite novels for its bittersweet depiction of the growing realisation that the main character has wasted his life. This other novel has the same thread of backward perspectives and of missed opportunities, however the main character (Banks) is of a very different nature. The way When we were orphans is written, one starts thinking this is all about an English detective trying to uncover the truth behind a very personal  tragedy, the disappearance of both his parents in Shanghai when he was a child. But progressively the narrative gets fractured and incoherent and we progressively doubt the author’s story, then his sanity. By the end of the book, it is just impossible to sift reality from imagination, daydreaming from life accomplishments. For instance, Banks presents himself as a detective with a certain degree of fame in London circles. However, there is no description whatsoever of his methods or of specific cases. The closest to a description is a child murder (and worse?) where a local constable pleads for the detective to hit at the heart of evil, in a completely incoherent discourse. The storytelling qualities of Ishiguro are so perfect that the character remains a mystery till the end. It is not even sure that he has at all left the acting as a detective he used to indulge in with his Japanese neighbour in Shanghai! The most disturbing section occurs when he revisits Shanghai at the time of the Japanese invasion and thinks he can link his parents’ disappearance with the said invasion and solve both of them at once. It is only when he enters a battle zone in the slums of the city that reality seems to reassert itself, but even then the reunification of Banks and the Japanese friend from his childhood is so unrealistic that the most likely interpretation is that Banks is in a permanent denial and that the Japanese officer he rescued plays the game to stay alive. Still, the story is told in such a way that one can never be sure of any of these interpretations and this is what makes it such a great book, more complex than The Remains of the Day in its construction, if less compelling because of the unfocussed nature of most characters, which we can never grasp hard enough…

waterline (book review)

Posted in Books with tags , , , , , , , on September 1, 2013 by xi'an

Another book I received as a bedside gift at The Hospital, this one a gift from Magali. Waterline by Ross Raisin is the story of a Glaswegian former shipyard worker falling into a mental abyss of denial and grief after her wife died. She died from asbestos-related cancer, whose fibres were brought from the shipyard in Mick’s clothes. Mick seeks solitude and shuns contact with former colleagues and friends, seeing their return to a normal life as an aggression against his wife’s memory. When Mick cannot stay longer in his rented council  house in Glasgow, fearing eviction and with no money left, he moves to London where he first finds a job as a dishwasher that alienates him even further into a bubble where he can cut others out. He is fired after a while for taking a very passive part in a local union and within a few weeks he spirals down into homelessness. The second part of the book sees him getting out very slowly and very reluctantly out of this state, with no clear sign of any return to (whatever we could call) normality…

This is a far from perfect book and the second part feels contrived, with a sort of “happy ending” out of the bottom end of Mick’s life. Still, Waterline is a strong book that marked me because it left me with a strong impression that the same fall could happen to any of us, under the right (or rather wrong) … Raisin has a highly convincing way of describing the inner mental paths taken by Mick to stop seeing others, including his children, for not returning to his uncertain cab driver job, and for giving up too readily looking for jobs, shelters, or help. The homeless-ness pages are terrifying in their somehow warped version of normality, when the “lives” of Mick and of his (leading) companion of misfortune Brian follow some kind of predestined pattern, from avoiding security guards by moving around to finding accessible toilets, to stealing food from  delivery trucks, to tracking protected places to sleep away from the rough weather. At times, this feels like too much and too long, but I would support the idea that this is “exactly” (given my total lack of expertise in the matter…) reflecting the experience of those homeless men, with no future further than the next night or the next meal. The second part of the book also shows how hard it is to reconcile with a “normal” life, incl. a poignant chapter on Mike reuniting with his son uncomprehending why his father had not called for help.  A highly recommended read, if not exactly on the brightest side of life…

London herons (just for one day)

Posted in pictures, Running, Travel with tags , , , , , on June 25, 2013 by xi'an

heron in Regent Park, June 20, 2013. (You can be herons, just for one day!, to borrow from David Bowie's song and the Courants de La Liberté motto)IMG_0147

Bayes 250

Posted in Books, pictures, Statistics, Travel, University life with tags , , , , , on June 21, 2013 by xi'an

IMG_0116While I left Paris under a thunderstorm, the weather in London was warm and sunny, and I enjoyed a nice walk to the RSS. With a Betsey Trotwood pub on the way that obviously delighted the David Copperfield fan in me! The Bayes 250 meeting started with the videoed interview of Dennis Lindley by and thanks to Tony O’Hagan in his Devonshire home. I hope the video gets on-line soon as it is remarkable in rendering Dennis’ view on Bayesian statistics, being full of humour and unremitting in his defence of the Bayesian approach. (And as I missed a few points due to an imperfect sound system.) “Coherence is all” could best summarise this interview. And the sincere regret that Bayesianism has not taken over…

IMG_0119The talks started with Gareth Roberts explaining why MCMC was possible in infinite dimension despite the dimensionality curse. (Starting his talk with a Rev. Bayes meets Newton, Markov and Metropolis diaporama.) Then, after a lunch break where some participants eloped to Bayes’ tomb next door (!), Sylvia Richardson presented a broad vision of Bayesian biostatistics, answering in my opinion some of Dennis’ worries that Bayes had not taken off widely-enough (my rephrasing). Dennis Prangle also chose to give an overview of ABC, rejoining my perspective that it is more of a new kind of inference with Bayesian justifications than a mere computational tool, Michael Jordan talked about Kingman’s paintbox (in relation with Tamara Broderick’s talk I had enjoyed so much in Kyoto) before rushing back to Paris, Phil Dawid gave a somehow a-Bayesian talk about the frequentist (in)validation of predictors, in connection with his calibration talk in Padova a few months ago, Iain Murray explained his NADE modelling tool, mixing neural nets with mixtures, and YeeWhye Teh concluded the talks of the day with a presentation of his Gibbs sampler for jump processes that I found most interesting (I later realised this was a paper I had missed in Bayes 250 in Edinburgh by leaving early!). The day ended with a few posters, including one by Maria Lomelli Garcia and YeeWhye Teh on alpha-stable processes that provided a new auxiliary variable representation of clear appeal. (The day actually ended for good with a light and enjoyable dinner in this most improbable Renaissance Hotel that literally stands at the end of the tracks of St Pancras…)

St Pancras. London, Jan. 26, 2012The second day was just as rich: after [a run in Regent's Park and] a welcome from the current RSS president (John Pullinger, who happens to live in Turnbridge Wells, of all places!), Michael Goldstein gave a spirited defence of Bayesian statistics as a projection device (putting expectation forward of probability as in deFinetti and Hartigan), Andrew Golightly discussed particle filter approximations based on discretised diffusions and fighting degeneracy via bridging, Nicky Best managed to give three talks in one (!) around Bayesian epidemiology, beginning with a Rev. Bayes meets Dr. Snow (who started spatial epidemiology with his famous cholera map). Then Christophe Andrieu presented what were new & exciting results for me, showing by Peskun and convex orderings that using more unbiased estimates of the likelihood function was theoretically as well as practically improving the performances of the associated Exact Approximation MCMC algorithm. This was followed by Ben Calderhead, who summarised his recently arXived paper with Mark Girolami and co-authors on using Bayesian analysis to evaluate the uncertainty associated with the numerical resolution of differential equations, connecting with the older paper by Persi Diaconis on the topic (paper I remember discussing with George Casella in an Ithaca café while we were waiting for his car to be fixed…). I wonder whether the approach could be used to handle the constant estimation paradox raised by Larry Wasserman (and discussed on the ‘Og as well)… Under the title of  “the misspecified Bayesian”, Stephen Walker sketched an on-going work with Chris Holmes, work that resonated deeply with some of my current musings about the nature of Bayesian inference on intractable problems. Hence giving me new prospects on ABC validation and extension. More precisely, he showed us a way to handle problems where only some aspect of the model is of interest and where a pseudo-model that (asymptotically) manages this aspect can be found. The paper should soon be arXived and I will certainly discuss it more at length then! Simon Wilson did a “Rev. Bayes meets Dr. Linnaeus” introduction and talked about the estimation of the number of newly discoveries of (unknown) species, a problem that I find fascinating even though I find the current solutions of an essentially hypergeometric model somehow oversimplifying. Chris Yau introduced us to his current work on cancer analysis and to his way of managing the complexity of the mutation process by hierarchical models, and Peter Green ended the presentations with a survey or survol of his work on doing inference on decomposable graphs, with online exhibits.

RSS wineThe meeting concluded with Adrian Smith giving a personal reminiscence of the (poor) state of Bayesian statistics in the 60’s and 70’s, paying tribute to his advisor Dennis Lindley for keeping the faith against strong opposition and for ensuring the survival of the field onto the next generation. (And linking once again with John Kingman.) As hopefully shown by my summary, the field is definitely alive nowadays and has accomplished much by managing the computational hurdles. (As shown further by our Statistical Science incoming vignettes, there are many cases where Bayesian analysis looks like the only available answer.) However, the new challenges raised by Big Data may well jeopardise this revival of a 250 year old principle by moving to quick-and-dirty (and less principled) inference techniques. What really made this meeting so successful in my opinion is that a lot of the talks we heard in Errol Street over those two days were exposing progress being made towards handling the new challenges. Hence, there still is hope for Bayesian techniques in the coming century!

London pubs

Posted in pictures, Statistics, Travel, University life, Wines with tags , , , , on June 20, 2013 by xi'an

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