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David Rousseau

@dhpmrou

Particle Physicist at IJCLab-Orsay, ATLAS experiment at CERN. Higgs Boson and AI. #ML competitions and open datasets Higgsml, TrackML, and now Fair Universe Higgsml Uncertainties #ai4science

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10.10.2023
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Latest posts by David Rousseau @dhpmrou

Malacca is underrated, I had no idea until recently that crossing from Indian Ocean to Pacific Ocean was non trivial

11.03.2026 10:47 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Volkswagen dieselgate vibes

10.03.2026 04:34 πŸ‘ 2 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

So when I hear people building β€œsociety of AI agents” …
Don’t we already know how hard it is to make a society work? Don't we see the evidence every day? 6/6

09.03.2026 21:37 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

They kept the best parts of object orientation, especially interfaces, but clearly separated: Algorithms (and later Tools) that do things and Data that flows between them. 5/6

09.03.2026 21:37 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Thankfully, visionaries like Markus Frank and Pere Mato at CERN went against the trend. They introduced Algorithm / Data separation, which became the foundation of the Gaudi/Athena framework still used today by the ATLAS and LHCb experiments at the LHC. 4/6

09.03.2026 21:37 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

My takeaway at the time: emergent complexity is a science of its own. How do ants build nests without an architect?
I even put a picture of an ant cemetery in my Habilitation.
How can you be confident you'll be able to specify small-object interaction rules and achieve what you want? 3/6

09.03.2026 21:37 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

For particle physics:
Calorimeter cells were supposed to organise themselves into well‑calibrated clusters.
Tracking hits were supposed to assemble into well‑fitted tracks.
And properly identified photons and electrons emerge.
In practice, prototypes failed spectacularly.
2/6

09.03.2026 21:37 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

#AgenticAI reminds me of the object‑oriented programming craze of the 2000s. Trained in Fortran/C, I dutifully attended two week-long OOP courses.
The mantra was: β€œThere should be no God object”. No SomethingManager. Complex behaviour should emerge from the interaction of many small objects 1/6

09.03.2026 21:37 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
A slightly blurry photo of a Jack Snipe in a swampy area among twigs. The picture was taken by holding a phone up to binoculars, and the phone focused on the twigs rather than the bird.

A slightly blurry photo of a Jack Snipe in a swampy area among twigs. The picture was taken by holding a phone up to binoculars, and the phone focused on the twigs rather than the bird.

This blurry bird is a Jack Snipe. A notoriously hard bird to spot, it only flushes when you’re almost stepping on it, it’s called the β€œdeaf” Snipe in French.
Detected with a thermal monocular, which is very effective for these cryptic birds.
First one spotted this spring in Paris region.
#birds

07.03.2026 18:42 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Yes but my gripe is that this is the one which was chosen for the olympics, to be compared to Olympic triathlon which is a ~2 hour effort.

27.02.2026 22:09 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

This ski-mountaineering event at the #winterOlympics #olympics is completely ridiculous.
These athletes have insane fitness, but it all comes down to how fast they can put on/take off their gear and handle their equipment.
Fine for a 2-hour triathlon, but for a 3-minute event? Come on.

19.02.2026 13:29 πŸ‘ 2 πŸ” 1 πŸ’¬ 1 πŸ“Œ 0

What’s great since the advent of LLMs is that now when I write a review, I don’t bother polishing my style, on the contrary, to show that this is 100% homemade, handcrafted review, folks.
Like leaving a few lumps in the mashed potatoes
#academiclife

19.02.2026 09:36 πŸ‘ 3 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Aha, to the gallon !! Glad you made it work…

27.01.2026 06:13 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Can’t wait for predatory journals to start using AI seriously.

I’m so done being invited to resubmit my "AI for Particle Physics" paper to the "Journal of Advances in Civil and Mechanical Engineering"

#AcademicLife

23.01.2026 10:21 πŸ‘ 2 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Note that the paper is about applicants, only some will be successful and they will be very welcome, but it is a tiny fraction of what would be needed to compensate the loss

21.01.2026 14:07 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

No they are not. Already not enough positions for the talented who graduated here

21.01.2026 00:47 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
Preview
(PDF) Post-fledging habitat selection of a Purple Heron Ardea purpurea revealed by GPS/GSM telemetry PDF | The Purple Heron is a species of conservation concern in Europe, mainly threatened by the progressive degradation and reduction of wetlands. For... | Find, read and cite all the research you nee...

Ah it might be a data artefact, as if the location is sent much less frequently at some point.
Just found this paper, from this author, which seems to be for this study (this is really not my area of expertise)

www.researchgate.net/publication/...

08.01.2026 21:57 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

βš›οΈ @kylecranmer.bsky.social , have you seen this brewing ?

08.01.2026 17:29 πŸ‘ 2 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
Preview
Resummation of the C-Parameter Sudakov Shoulder Using Effective Field Theory The C-parameter distribution in $e^+e^-$ annihilation exhibits a kinematic shoulder at $C = 3/4$, where three-parton final states reach their maximum and a fourth parton is required to exceed it. This...

arxiv.org/abs/2601.02484

Yes, it's that Schwartz -- QFT textbook author -- writing a paper wherein "All calculations, numerical analysis, and manuscript preparation were performed by Claude, an AI assistant developed by Anthropic, working under physicist supervision."

08.01.2026 04:21 πŸ‘ 6 πŸ” 2 πŸ’¬ 1 πŸ“Œ 1
Map of Africa and Europe, with purple dots mapping the migration  trajectories of purple herons over serveral year. Beppe's trajectory is dark blue.

Map of Africa and Europe, with purple dots mapping the migration trajectories of purple herons over serveral year. Beppe's trajectory is dark blue.

Incredible !
I see that there is no data beyond data 2024. What are they up to ?

08.01.2026 13:31 πŸ‘ 2 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

My phantom bird, seen only once many years ago in Marais Poitevin, west of France. It is not really rare in France but rather elusive.
And so many grey herons of similar size and silhouette and even pattern if far away

07.01.2026 23:10 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Sounds like a crazy idea, but I was almost convinced after reading the full post.

07.01.2026 05:37 πŸ‘ 2 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

This πŸ‘‡ !!!

02.01.2026 23:26 πŸ‘ 4 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

2025 France Lifer tally: 5 this year, bringing me to 289.
Four mentioned above, plus Wood Warbler in Fontainebleau Forest.
300 is in reach!

7/7

01.01.2026 17:54 πŸ‘ 2 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Top 1 2025 #birds
Little Bustard at last!
Distant views, rain pouring, but after 20–30 years of hoping, I finally got it.
The longer the search, the greater the joy of the tick, of course
bsky.app/profile/dhpm...

6/7

01.01.2026 17:54 πŸ‘ 3 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Top 2 2025 #birds
The double lifer in 15 minutes!
One on a tip‑off (White‑winged Tern), the second self‑found (Grey Phalarope).
bsky.app/profile/dhpm...

5/7

01.01.2026 17:54 πŸ‘ 4 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Top 3 2025 #birds
Exceptional morning of the four european harriers, even if none was a lifer

bsky.app/profile/dhpm...

4/7

01.01.2026 17:54 πŸ‘ 4 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Top 4 2025 #birds
Horned Larks on Île Madame.
Typically, only a handful are seen in France wintering on the northern dunes, but last winter a pair was exceptionally recorded south in Charente‑Maritime. I could easily find them

bsky.app/profile/davi...

3/7

01.01.2026 17:54 πŸ‘ 5 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Top 5 2025 #birds
Watching a pair of Eurasian Golden Orioles chase each other just meters away, the male’s vibrant yellow and the female’s rich green.
Often heard in summer, rarely glimpsed in dense foliage, but this was a full-on show!
2/7

01.01.2026 17:54 πŸ‘ 2 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
A map of France localising bird ticks for 2025, with a patch around Essonne and another one around Deux-Sèvres

A map of France localising bird ticks for 2025, with a patch around Essonne and another one around Deux-Sèvres

#Birding2025 Recap 181 species, my 2nd best year since 2014, even without trips to Brittany, Provence, Jura, or Corsica!
Made the most of local patches and Niort (my home town)
A few puzzling misses: Fieldfare and Red Kite.
Highlights of the year:
#birds
1/7

01.01.2026 17:54 πŸ‘ 5 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0