Ragnar {Groot Koerkamp}'s Avatar

Ragnar {Groot Koerkamp}

@curiouscoding.nl

Postdoc on high troughput bioinformatics @ KIT Karlsruhe; IMO, ICPC, Xoogler, Rust, road-cycling, hiking, wild camping, photography

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Latest posts by Ragnar {Groot Koerkamp} @curiouscoding.nl

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Multi-context seeds enable fast and high-accuracy read mapping - Genome Biology A key step in sequence similarity search is to identify shared seeds between a query and a reference sequence. A well-known tradeoff is that longer seeds offer fast searches but reduce sensitivity in ...

1/ Our paper on Multi-Context Seeds is now out, with @tolyan.bsky.social spearheading the work and contributions from Nicolas and @marcelm.net. We introduce a new seeding concept that improves read alignment accuracy while maintaining speed.
link.springer.com/article/10.1...

09.03.2026 12:22 πŸ‘ 15 πŸ” 11 πŸ’¬ 1 πŸ“Œ 0

Als politici zeggen dat ze nog niet weten of de VS en IsraΓ«l het internationaal recht hebben geschonden, ben ik wel benieuwd waarom ze 2 maanden terug, 5 dagen na de operatie tegen Maduro, zeker wisten dat dit recht toen wel was geschonden. Ook D66, VVD en CDA
www.tweedekamer.nl/downloads/do...

08.03.2026 11:54 πŸ‘ 97 πŸ” 35 πŸ’¬ 10 πŸ“Œ 3
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Icefish: Practical zk-SNARKs for Verifiable Genomics Individual genomic data is a uniquely sensitive type of user data. While many papers have considered using Multi-Party Computation (MPC) or Fully Homomorphic Encryption (FHE) to allow collaborators to...

Since it's not on @biorxivpreprint.bsky.social, my normal crowd might not see it, but I'm very excited about this recent work that, actually, started as class project in my graduate genomics class last year: eprint.iacr.org/2026/463 . Zero knowledge proofs for genomics; with algorithms :).

08.03.2026 00:55 πŸ‘ 8 πŸ” 2 πŸ’¬ 0 πŸ“Œ 0

1350 train kms in 16h for 40€ βœ…

06.03.2026 21:15 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
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Excited to share this preprint that describes my latest work on using GPUs to accelerate processing of RNA-seq data.

The title says it all: "RNA-seq analysis in seconds using GPUs" now on biorxiv www.biorxiv.org/content/10.6... and github github.com/pachterlab/k...

Figure 1 shows they key result

06.03.2026 19:32 πŸ‘ 179 πŸ” 85 πŸ’¬ 6 πŸ“Œ 8

Israel is bombarding, literally bombarding, two Middle East capitals, Beirut and Tehran, killing 100s of civilians, and yet the US and UK media continue to portray Iran as the threat to the region.

Israel has nukes, but Iran is the nuclear threat.

We live in Orwellian times.

06.03.2026 13:15 πŸ‘ 7534 πŸ” 2552 πŸ’¬ 179 πŸ“Œ 56

Yeah, ignorance is bliss 🀩
Just in academia that stops working once you want to make a paper

06.03.2026 15:01 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

> The compromised version was live for eight hours before StepSecurity's automated monitoring flagged it

did they publish /exactly/ at the time of the only oncall person's bed time and did they have a super restful night?

(3/3)

06.03.2026 10:32 πŸ‘ 28 πŸ” 1 πŸ’¬ 0 πŸ“Œ 0

What?!? How can one be 200x slower than the other....

Btw, saw it also mentioned on reddit, but what about plotlars?

06.03.2026 09:55 πŸ‘ 0 πŸ” 0 πŸ’¬ 2 πŸ“Œ 0

Tthese separators follow landmarks. Eg the set of bridges over the Rhine is an efficient way to partition Europe into two halves. Or passes over the alps, and so on.

This partitioning does not depend on edge weights, so that it's relatively cheap to recompute paths in case of eg traffic jams.

06.03.2026 01:09 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Basically, we take a set of nodes as the root 'super node' that we turn into a clique, such that the remainder is partitioned into two (or more) connected components. Then we can recurse to get a tree of 'separating sets'.
In practice, these separators are small, giving O(n^{1/3}) queries.

06.03.2026 01:07 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

The tl;dr of CCH: in a binary tree, you can find the distance between any 2 nodes s and t by computing d(s, u) and d(v, t) for all ancestors u of s and ancestors v of t. Then find the LCA and sum the two. So lg(n) query time.

Road graphs are not trees, but we can 'contract' them into one.

06.03.2026 01:05 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

The EU road network used for testing has 18M nodes and 42M edges. Dijkstra between two random nodes on this graph takes around a second.
The existing C++ implementations of CCH take only ~100us, which is already insane.

With some SIMD tricks, mine brings it down to ~40us.

06.03.2026 01:02 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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Customizable Contraction Hierarchies -- A Survey This work establishes the technical fundamentals of a well-tuned Customizable Contraction Hierarchies (CCH) implementation that is simple and elegant. We give a detailed overview of the state of the a...

I got nerd-sniped into writing some code for Customizable Contraction Hierarchies, which is an insanely cool and super simple data structure for fast route planning.

Nice survey paper by Michael ZΓΌndorf et al: arxiv.org/abs/2502.10519

My unpolished implementation nodes: curiouscoding.nl/posts/cch/

06.03.2026 01:00 πŸ‘ 3 πŸ” 1 πŸ’¬ 1 πŸ“Œ 0
NordVPN refund dark patterns Tl;dr: if you want to refund your NordVPN payment, go to my.nordaccount.com/billing/billing-history?intent_rf=true. The last part, ?intent_rf=true, is the important bit. (If that doesn’t work, you’ll ...

If you ever need to get a refund on NordVPN auto-renewal, you just need to add ?intent_rf=true to the URL of the billing page and suddenly a 'refund' button will appear...
(Took way too long of browsing reddit to figure that out.)

curiouscoding.nl/posts/nordvp...

06.03.2026 00:57 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Oh cool πŸ₯°

06.03.2026 00:52 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
start-history.com graph of A*PA github stars, with bumps at time of preprint and publication, and steady growth since then.

start-history.com graph of A*PA github stars, with bumps at time of preprint and publication, and steady growth since then.

Are people actually using A*PA?
It suddenly got 4 stars in the last 2 days and appears to be growing steadily either way, but I'm getting issues maybe twice a year, which can either mean nobody uses it, or that it just works (but the UX is really not so great).

06.03.2026 00:15 πŸ‘ 2 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Broke a leg playing table tennis. Got some titanium goodies now :)

05.03.2026 21:03 πŸ‘ 2 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

[T]::array_windows is stable!!!

05.03.2026 21:02 πŸ‘ 8 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

I'm afraid I don't know most of those words; will check it out :)

05.03.2026 10:11 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Yey for sans serif!

04.03.2026 19:04 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Time for the rise of super small and efficient STPD-index based aligners!

04.03.2026 16:30 πŸ‘ 2 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

What?! do they think it's 2016 still??

Can barely have a human genome in memory?!

04.03.2026 16:22 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Mostly specializing all the transpose, collect and dedup functions for it. Idk how easy that is (/how similar it is to other arches)

04.03.2026 07:48 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

The main simd-mini issue was basically that building for 32bit targets means that usize is not 64 bits and this was implicitly assumed in a few places.

And there was a silly build error for all non-simd target unrelated to that. Although I guess proper simd support for wasm would be cool.

03.03.2026 21:25 πŸ‘ 2 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

When someone says β€žScientists do not want you to knowβ€œ you can dismiss everything from there on. Scientists want you to know. They are desperate that you know. They can’t shut up about what they found out and want you to know.

03.03.2026 12:10 πŸ‘ 9505 πŸ” 4132 πŸ’¬ 77 πŸ“Œ 165

@fingels.bsky.social sounds familiar

03.03.2026 20:14 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
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Mer de Glace from Signal Forbes
1890 | 2013 | 2021 | 2024

Strong acceleration of the demise of the largest French glacier over last few years! 🧊πŸ”₯

03.03.2026 12:08 πŸ‘ 72 πŸ” 48 πŸ’¬ 2 πŸ“Œ 3
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Deacon can now run in the browser using WebAssembly. Sequence data never leaves your machine. It currently supports FASTA/Q filtering using indexes up to 1GB in size.

Demo: bede.im/deacon

03.03.2026 14:30 πŸ‘ 29 πŸ” 10 πŸ’¬ 1 πŸ“Œ 1

soms weet ik zelf ook niet zeker of ik een tv-recensie of een speld-artikel aan het schrijven ben

03.03.2026 10:51 πŸ‘ 149 πŸ” 6 πŸ’¬ 11 πŸ“Œ 0