Category Archives: ressources

Good optics

Here are collected pictures from the vendor exhibition at the SPIE Optics+Photonics 2019 conference in San Diego, CA.
I always find these exhibitions strangely fascinating, and I wanted to capture why. Enjoy!

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The New Yorker and the current times

Since I arrived in the US about six years ago, I’ve been interested in learning about the culture of my new country. An obvious way is to read the magazines and learn what people are talking about. Alas, the free press is usually not very interesting. Some magazines are standing out; I’ve been subscribed to The Atlantic, the Pacific StandardWired and Rolling Stones, and I’ve read GQ, Vanity Fair, The Economist (though British), but while there’s a bunch of good articles, they are plagued by terrible layouts, dull advertisement, and I can’t find any thing that matches some of my favorite French magazines, such as Les Inrocks or Le Nouveau Magazine Litteraire, though I must say I now realize they often feature subjects that have been thoroughly digested by US magazines.
There is however a publication which is consistently good, entertaining, frequent (every week) and almost free of advertisement: The New Yorker, which contrary to its name suggests doesn’t delve too much on the (otherwise great) city of New York.

“He tells it like it is.” August 18, 2016


Not only the quality and the length of the articles, which are often sheltered from the ceaseless stream of news, allows go deep into some subjects (some arcane but always interesting), but they do make an impact.
For witness:
It is quite remarkable for a journal to be able to uncover so many stories. Maybe the times are ripe for that and comes the reckoning…


The publication has a tremendous legacy, with writers such as Hannah Arendt (who published her series on the banality of evil there), James Baldwin who covered the civil rights movement and Susan Sontag who mused on various topics (see her collected articles in Against Interpretation and On Photography.)

I am speaking as a member of a certain democracy and a very complex country that insists on being very narrow-minded. Simplicity is taken to be a great American virtue along with sincerity. One of the results of this is that immaturity is taken to be a great virtue, too. – James Baldwin


There are many contributors to the magazine, but there are three I am particularly fond of, maybe because I can relate and they write things I don’t even know to express. Jia Tolentino covers Millenial generation with great nuance, and how we navigate the navigate the culture rift; Adam Gopnik often writes about culture in the broad sense, often threading from his experience in France (he has a very acute knowledge of France culture and how it differs from US culture); Louis Menand writes excellent book reviews.
It is interesting to see that both Gopnik and Tolentino released books in the past month (“A thousand small sanities” and “Trick Mirror”), which both deal with the current, heavy, atmosphere that lingers over the country as a whole, not complaining, but trying to find an outlet.

Open access – redux

Wow the levy is about to break on Open Access!

I’ve written a few times on Open Access (here, and here), and things have been changing at an incredible pace.

A quick explanation about the topic: scientists share their research by publishing into very specialized journals. These journals then either charge a fee (>$10) for any reader to read a specific article, or as is more often the case, collect a subscription for an institution so that all of the people who work for this institution get complete access to a journal or a set of journal. The problem here is that the research submitted by the authors is often funded by public entities, which do not have the right to read the publications of other group freely (open access.) And the subscription fees have skyrocketed (e.g. in the order of $10 million for UC Berkeley.)

But now, large entities are rebelling.

The first salvo came from funding agencies, which require the papers to be made freely available, either by sharing the pre-prints (e.g. on arxiv) or by publishing in an Open Access journal (journals where the authors pay (usually $1000!) to get published, and where anyone can read.)

Then came Germany, which reached an impass with the academic publisher Elsevier (one of the leading actors, together with Springer and Wiley) and decided not to pay for the racket (projekt DEAL). The issue has not been resolved yet and German researchers still do not have access to publications such as Cell (they can however directly contact the authors of the papers to get the papers — which actually sound like a good way to start off collaborations!)

Next is the University of California (the whole UC system, with UC Berkeley, Los Angeles, … including Lawrance Berkeley National Lab and Los Alamos), who decided not reneged a deal with Elsevier. That’s a lot of people, for the most important public university system in the world. The impact can be quite dramatic…

And soon will be the turn of Europe as a whole, with Plan S, starting next year…

I can’t wait to see the science literature being unshackled!

Still, don’t expect much changes in the conduct of science… “Authors do not publish to get read, they publish to get reviewed.”


Kolmogorov Access

Back in undergrad, I remember being fascinated by the notion of Kolmogorov complexity in computer science.

Put simply, the Kolmogorov complexity is the minimal length (number of lines) of the code needed to generate a signal, would it be a mathematical sequence (such as one listed in the OEIS) or an image, irrespective to the size needed to store it. It bears deep relations with the notion of entropy (a great book on the topic is Information Theory, Inference, and Learning Algorithms by the late David MacKay.)

For example, a series of eight billion ones in a row would require 1GB of memory, but can be written in a few lines of code:

for i in 1:1e9; print 1; end

(To some extent, this is why computer science is often problematic, since one of the goal of a good code is sometimes to reduce its Kolmogorov complexity, but the final code does not show all the lines that have been erased to get there…)

In the field of arts, culture and science, this description seems naive: can you really generate a book based on a script, or has it infinite entropy?

Science is organized knowledge. Wisdom is organized life.
– Immanuel Kant

In the age of the Internet, can we do better?

update 6/10/2019: I’ve seen recently on Twitter the embodiment of these ideas, see Nicole R.‘s thread. Way to go!

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The wonders of West Berkeley

I do love Berkeley, with its wonderful atmosphere and its people, daring to live on a different beat!

The spring and the fall are the most notably beautiful, and walking in the street is always an amazement.

Berkeley in the spring

In the winter, you get the magnolia; in the spring come the fragrant wisteria and the gentle jasmine; the summer has the river flowing to the sea, and the fall, oh the fall with the ginkgo glowing gold on Russell street!

Berkeley in the fall

I’ve seen a few friends moving nearby, and they seem to enjoy every bit of it.

Here’s a few places to check out:

  • Skates to get a drink right at sunset
  • Casa Latina for the best tacos of the East Bay
  • Berkeley Bowl West is such a paradise for the grocery shopper
  • Cal Sailing Club lets you sail and windsurf for less than a dollar a day
  • Bette’s Diner has some amazing brunch
  • Market Hall Foods on 4th street has the best cheese selection I know, plus a hundred of other delicacies
  • Albatross is the oldest pub of Berkeley, with a great selection of beer, darts and pool
  • Ashkenaz has a great music programming; don’t miss Stu Allen’s Grateful Dead!
  • Sola Lucy is the only place to go for thrift shop

For the news, check out and the East Bay Express (free, out every Wednesday.) There’s also a lot of other places closer to downtown which are unique: the Back Room, the Pacific Film Archive, Yoga to the people, Half Price Book, Café Panisse, the Strawberry canyon pool, the Skyline boulevard, the Butcher’s son restaurant, the Melo Melo kava bar, and so many other things!

How I unlocked my Verizon Moto G6 and ditched my iPhone 6 because it was too slow

Recently, I bought a phone for my family visiting, because roaming costs are so incredibly high for no good reason, and because it becomes hard to navigate the world without the internet (booking, GPS, etc.) I bought at $99, and paid a $50 data plan from Verizon (good deal given that the phone the MSRP is $249, that it’s a very decent phone, and that you can use it anywhere with any carrier — it has GSM, CDMA and everything you need.)

On the back of the box, it was mentioned that the phone could be unlocked after $50 had been made. I had just bought $50 of credit for 1 month of 4G with Verizon.

When my parents left, I tried to unlock it. It was a bit confusing, but it did work!

You can find solace in successfully going through automated customer service

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Mr Musk is having a hard time, and even though I have great appreciation for his making engineering look cool again, I won’t relent  as I believe his efforts are misguided.

Nothing can be so amusingly arrogant as a young man who has just discovered an old idea and thinks it is his own. – Sidney J. Harris

Today, I’ll talk about Hyperloop.

edit 12/18/2018: Hyperloop startup Arrivo is shutting down -The Verge — lol

edit 10/10/2019: Was the Ocean Cleanup Just a Pipe Dream? – Outside online
Jenny Allen: “Male privilege in science is a 24 year old guy with no formal training being called a ‘boy genius’, receiving millions of dollars in funding, and referring to qualified female oceanographers as ‘Ms’ instead of ‘Dr.’ when they critique his project.”

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Hi there!

Preparing for the new generation of synchrotron light source, I’ve just started (Diffraction-Limited Storage Ring), and created relevant articles on Wikipedia (entries for (Diffraction-Limited Storage Ring  and Beijing’s High Energy Photon Source.)

The goal is to have platform to share knowledge and ideas in a format more flexible than conferences and papers (it takes inspiration from Rüdiger Paschotta’s momentous Encyclopedia of Laser Physics and Technology, though it does not aim to be as comprehensive!)

Let me know if you’re interested in contributing!

Confédération des Associations Centrale-Supéléc – San Francisco

(Dear English reader, this post relates to an association of French Alumni in the Bay Area.)Depuis quelques temps, j’aide à organiser le réseau des Centraliens dans la Baie de San Francisco, faisant suite à la réunion des Centraliens a San Diego l’an passé où j’ai fait de très belles rencontres. Cela nous à donné l’envie de renforcer le réseau en l’étendant à toutes les Écoles Centrales, en particulier celles de Pékin, Casablanca et Hyderabad, afin de permettre aux jeunes diplômés et entrepreneurs attirés par la baie de rencontrer des personnes susceptibles de les aider à s’intégrer, leur fournir de bons conseils et à comprendre l’état des affaires (il y de centraliens au sein de nombreuses grandes entreprises comme Apple, Lyft, Google, Uber, Airbnb, Sony or Western Digital.)

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How to retrieve and handle x-ray data

A bit wonky, but here’s where you can get x-ray data, how to use it in python, and some common conversion.

Here are two important database to know:

CXRO database

NIST database

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