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Paul Medvedev

@pashadag.bsky.social
1.9K followers 160 following 92 posts

Algorithmic Bioinformatics Researcher and Teacher. Posts about research results and educational/mentorship topics (for details, see bit.ly/380vX22).

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Reposted by Paul Medvedev
Roland Faure @rfaure.bsky.social · 09/10/2026
(Thread) New Logan preprint 🥳 www.biorxiv.org/content/10.6...! We sketched all the metagenomes of Logan1.0 and released the sketches. These sketches allow quick content comparison with any/all metagenomes of Logan. Cool applications in the paper and hopefully many others we did not foresee yet 😀
biorxiv.org
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Reposted by Paul Medvedev
haonanwu.bsky.social @haonanwu.bsky.social · 11/07/2026
Our #ISMB2026 paper is now online! I’m excited to present it at HiTSeq on July 13. Many thanks to my advisor @pashadag.bsky.social. I’m also grateful to @iscb.bsky.social for awarding me the Conference Fellowship. If you’ll be at ISMB, feel free to stop by my talk and say hi. I’d love to connect!
academic.oup.com
The gift of novelty: repeat-robust k-mer-based estimators of mutation rates
AbstractMotivation. Estimating mutation rates between evolutionarily related sequences is a central problem in molecular evolution. Due to the rapid expans
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Paul Medvedev @pashadag.bsky.social · 07/05/2026
Weird, the doi link worked / works for me. Anyhow, thanks Igor, the direct GR link fixes this
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Paul Medvedev @pashadag.bsky.social · 05/05/2026
This is now published in Genome Research (doi.org/10.1101/gr.2...). Thank you everyone for your feedback and also the anonymous reviewers who helped to greatly improve the paper. I hope this becomes a useful resource for the community.
doi.org
Hash functions in nucleotide sequence analysis
Randomness is a powerful tool in the design and analysis of algorithms and data structures for nucleotide sequence data. Nucleotide sequences are not themselves random but are often randomized using hash functions. Despite their widespread use in genomics, there is no comprehensive review of the types of hash functions used and their various applications. In this survey intended for bioinformatic methods developers, we divide hash functions into four categories: scattering hash functions, permutations, minimum perfect hash functions, and locality-sensitive hash functions. For each category, we provide examples of both general-use hash functions that have been applied in nucleotide sequence analysis and hash functions that have been designed specifically for nucleotide sequence analysis. We highlight their salient properties, commonalities, differences, and application areas.
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Paul Medvedev @pashadag.bsky.social · 25/04/2026
i'm thinking of returning it....the lack of the curve on the monitor turns can be felt
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Paul Medvedev @pashadag.bsky.social · 22/04/2026
Oh man we just handed it the proofs for our Genome Research hash survey paper, where it would have been good to mention this!
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Paul Medvedev @pashadag.bsky.social · 17/04/2026
I just had the innoca delivered. It seems good, and I haven't encountered any problems so far. I also noticed it has less USB ports than the Dell, which is not great. Its also not curved, and I now understand why curved is slightly preferable. But for me at least its the right choice, given the cost
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Paul Medvedev @pashadag.bsky.social · 15/04/2026
good to know!
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Paul Medvedev @pashadag.bsky.social · 14/04/2026
Thanks Rob. The biggest worry is the fact that its non-curved. At that size, people are saying its a problem.
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Paul Medvedev @pashadag.bsky.social · 13/04/2026
I am shopping for the same thing! Do you knowing anything by the INNOCN option? Never heard of this brand, but its about 1 third of the price of the dell/LG options. Is it just crap or is it good enought?
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Kristoffer Sahlin @ksahlin.bsky.social · 16/03/2026
𝗣𝗼𝘀𝘁𝗱𝗼𝗰 𝗮𝗻𝗱 𝗣𝗵𝗗 𝗽𝗼𝘀𝗶𝘁𝗶𝗼𝗻𝘀 𝗶𝗻 𝗖𝗼𝗺𝗽𝘂𝘁𝗮𝘁𝗶𝗼𝗻𝗮𝗹 𝗚𝗲𝗻𝗼𝗺𝗶𝗰𝘀 / 𝗔𝗹𝗴𝗼𝗿𝗶𝘁𝗵𝗺𝗶𝗰 𝗕𝗶𝗼𝗶𝗻𝗳𝗼𝗿𝗺𝗮𝘁𝗶𝗰𝘀 I am currently recruiting for both: 🔹 Postdoc position su.varbi.com/what:job/job... 🔹 PhD position su.varbi.com/en/what:job/... Please share with anyone who might be interested!
su.varbi.com
Postdoktor i Beräkningsbiologi
Matematiska institutionen består av cirka 120 forskare, lärare och administrativ personal och är organiserad i tre huvudsakliga avdelningar: Matematik, Matematisk statistik och Beräkningsmatematik
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Rob Patro @robp.bsky.social · 17/02/2026
How would you design a *multithreaded*, *concurrent* & *dynamic* hash table if you are focused specifically on common k-mer workloads, where streaming query & insertion are common? Jamshed, Prashant and I explore this in kache-hash, a cache-friendly k-mer hash table! www.biorxiv.org/content/10.6...
biorxiv.org
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Reposted by Paul Medvedev
Rob Patro @robp.bsky.social · 16/02/2026
I feel it quite possible that those relying on AI from the very start may form a different skill set that will accelerate some software, but result in key regressions (without the expertise to address them) in other types. combine-lab.github.io/blog/2026/02... see the caveats section here…
combine-lab.github.io
COMBINE-lab - The skeptic’s guide to generative AI assisted coding
An easy-to-use, flexible website template for labs, with automatic citations, GitHub tag imports, pre-built components, and more.
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Paul Medvedev @pashadag.bsky.social · 12/02/2026
CVs are broadly distributed across the department. Evaluations are kept to people on the hiring committee (though there is some flexibility around that). I don't know if there are any formal restrictions on the statements, but in practice they are typically shared with people who express interest
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Paul Medvedev @pashadag.bsky.social · 11/02/2026
depends on the materials (letters are treated more confidentially than research statements than CVs)
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Sam Horsfield @samuelhorsfield.bsky.social · 07/02/2026
At long last, my final PhD chapter is out: we developed a novel evolutionary simulator of bacterial pangenomes, Pansim, fitting it to data from >600K genomes using a likelihood-free framework, PopPUNK-mod, to explore neutral and adaptive pangenome dynamics www.biorxiv.org/content/10.6...
biorxiv.org
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RECOMB Conference Series @recombconf.bsky.social · 05/02/2026
🚨UPCOMING DEADLINES🚨 RECOMB-CG: 13 February RECOMB-RSG: 15 February RECOMB-Privacy: 9 March RECOMB-Seq: 12 March (abstract registration) RECOMB-Arch: 12 March (abstract registration) RECOMB-Genetics: 13 March #RECOMB2026 #deadlines
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Paul Medvedev @pashadag.bsky.social · 07/02/2026
There is still many Amish villages around where Penn State is. Local farmer markets often carry their produce. I think they speak some form of Germanic, IIRC. But its not rare in the US that states used to speak the language of the colonizers (cali->spanish, louisiana->french)
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Adam Phillippy @aphillippy.bsky.social · 02/02/2026
Time for a thread on our Christmas preprint “Origin and evolution of acrocentric chromosomes in human and great apes”. I had so much fun with this project and paper. It will be hard to summarize in a thread, but I’ll try www.biorxiv.org/content/10.6... [1/21]
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Antoine Limasset @npmalfoy.bsky.social · 04/02/2026
Preprint alert! arxiv.org/abs/2602.03525 TLDR: ZOR filters are STATIC filters with false positives. -Almost memory optimal: <1% overhead over the theoretical lower bound (!!!) -Fast queries: ~100 ns -Construction cannot fail A thread:
arxiv.org
ZOR filters: fast and smaller than fuse filters
Probabilistic membership filters support fast approximate membership queries with a controlled false-positive probability $\varepsilon$ and are widely used across storage, analytics, networking, and b...
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Michael Baym @baym.lol · 15/01/2026
If you are an Israeli PhD student and are interested in a postdoc at Harvard Medical (my lab included!), I strongly recommend looking into the Kalaniyot fellowship program, providing 2-3 years of full support: globalprograms.hms.harvard.edu/kalaniyot-hm...
globalprograms.hms.harvard.edu
Programs
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Reposted by Paul Medvedev
Giulio Ermanno Pibiri @jermp.bsky.social · 10/12/2025
The 12th edition of the 2-days workshop “Data Structures in Bioinformatics” (DSB) will take place in Venice (Italy) on February 18-19th, 2026: dsb-meeting.github.io/DSB2026/
dsb-meeting.github.io
DSB 2026 Venice - February 18-19
Workshop Data Structures in Bioinformatics
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Paul Medvedev @pashadag.bsky.social · 03/12/2025
This thread gives really interesting and relevant history!
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Reposted by Paul Medvedev
Ben Langmead @benlangmead.bsky.social · 03/12/2025
Kraken 2 (K2) community: we are giving more attention to our new `k2` wrapper, and a NEW functionality since 2.17.0 is: you can build several component K2 indexes, e.g. each covering a different Refseq database, and then query them all at once... github.com/DerrickWood/... 1/6
github.com
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Antoine Limasset @npmalfoy.bsky.social · 02/12/2025
Preprint alert! We introduce new ideas to revisit the notion of sampling with window guarantees, also known as minimizers. A thread:
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Yaron Orenstein @yaronorenstein.bsky.social · 10/11/2025
Interested in a post-doc in Israel? The deadline for the Azrieli International Postdoctoral Fellowship is November 19. The fellowship offers generous funding for postdocs to conduct research in any academic discipline at eligible Israeli institutions: azrielifoundation.org/fellows/inte...
azrielifoundation.org
International Postdoctoral Fellowship - The Azrieli Foundation
The Azrieli Fellows Program is an elite group of academics who cultivate a network of leading professionals in Israel and around the world.
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Reposted by Paul Medvedev
Sina Majidian @sinamajidian.bsky.social · 06/11/2025
Haonan Wu gives a talk on "A k-mer-based estimator of the substitution rate between repetitive sequences" www.biorxiv.org/content/10.1... This work tackles the issue of Mash which ignores repeats in the genome, providing better distance estimation #GI2025
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Andre Kahles @akkah21.bsky.social · 08/10/2025
After years of research and continuous refinement, we’re thrilled to share that our paper on the MetaGraph framework — enabling Petabase-scale search across sequencing data — has been published today in Nature (www.nature.com/articles/s41...)
nature.com
Efficient and accurate search in petabase-scale sequence repositories - Nature
MetaGraph enables scalable indexing of large sets of DNA, RNA or protein sequences using annotated de Bruijn graphs.
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Rob Patro @robp.bsky.social · 08/10/2025
And it's posted! If you're interested and eligible, please consider applying through the UMD portal: umd.wd1.myworkdayjobs.com/en-US/UMCP/j.... If you're a PI working in algorithmic genomics (& you can recommend my lab to your top graduating students ;P), please let them know!
umd.wd1.myworkdayjobs.com
Postdoctoral Associate
Job Description Summary Organization's Summary Statement: The postdoctoral research associate is responsible for developing novel computational methodology for high-throughput sequence genomics tasks,...
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Reposted by Paul Medvedev
Ben Langmead @benlangmead.bsky.social · 07/10/2025
I've added 7 videos to my Burrows-Wheeler indexing playlist (www.youtube.com/playlist?lis...), rounding out the r-index series and adding a 5-part series on the move structure. Now 27 videos in that playlist. I aim to add videos on prefix-free parsing, PBWT, Wheeler languages/automata in the future.
youtube.com
Burrows-Wheeler Indexing - YouTube
Videos on : (a) the Burrows-Wheeler Transform (BWT), (b) the FM Index, which uses the BWT to construct a full-text index, (c) Wheeler graphs, (d) r-index, an...
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Paul Medvedev @pashadag.bsky.social · 07/10/2025
Sounds like someone is trying to solve a bidirected flow problem..
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Paul Medvedev @pashadag.bsky.social · 03/10/2025
i've let the person in charge know
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Paul Medvedev @pashadag.bsky.social · 03/10/2025
There seems to be a self-contradiction within the CFP, since it also says: "Submissions to peer-reviewed journals other than the partnering ones are also allowed.."
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Roland Faure @rfaure.bsky.social · 03/10/2025
Our preprint on our new metagenomic HiFi assembler Alice is out 🥳 Based on a *new sketching method* (🧵1/6) 👉 Preprint www.biorxiv.org/content/10.1... 👉 Github github.com/rolandfaure/...
biorxiv.org
Alice: fast and haplotype-aware assembly of high-fidelity reads based on MSR sketching
We introduce Mapping-friendly Sequence Reduction (MSR) sketches, a sketching method for high-fidelity (HiFi) long reads, and Alice, an assembler that operates directly on these sketches. MSR produces ...
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bioRxiv Bioinfo @biorxiv-bioinfo.bsky.social · 01/10/2025
Alice: fast and haplotype-aware assembly of high-fidelity reads based on MSR sketching www.biorxiv.org/content/10.1101/202…
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Paul Medvedev @pashadag.bsky.social · 28/09/2025
It could be. Or it could be that the decision process is not consistent? Hard to tell...
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Paul Medvedev @pashadag.bsky.social · 26/09/2025
I see. Do you know if the list of papers that are posted there get disseminated somehow through mail lists or social media?
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Paul Medvedev @pashadag.bsky.social · 26/09/2025
They do, but they did not accept our paper. From what we understood, it was because it was a review paper and not novel research
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RECOMB Conference Series @recombconf.bsky.social · 26/09/2025
#RECOMB2026 will be in Thessaloniki, Greece on May 26-29, 2026. Satellites on May 24-25. Save the date! Το συνέδριο #RECOMB2026 θα πραγματοποιηθεί στη Θεσσαλονίκη, στις 26-29 Μαΐου 2026. Οι δορυφορικές εκδηλώσεις θα διεξαχθούν στις 24-25 Μαΐου 2026. Σημειώστε την ημερομηνία!
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Paul Medvedev @pashadag.bsky.social · 25/09/2025
Hi Gaurav, I'm not sure what you mean. (But it sounds like you are asking for a library with all these implemented in one place? That would be quite an undertaking! As these things are always evolving, I'd guess it would also not age well.
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Paul Medvedev @pashadag.bsky.social · 25/09/2025
I guess that if all one wants is to just have a doi for the pdf, there are various options (zenodo, HAL). But if one is looking to have the title "advertised" broadly (as happens with a biorxiv or arxiv preprint), then that's the hard part
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Paul Medvedev @pashadag.bsky.social · 25/09/2025
This might be an option, though I'm very confused by how it works. For example, I see a recent paper there: hal.science/hal-04764426v1 but when I open it, its headers indicate it is a biorxiv preprint. Why is it duplicating it? In another exmpl, hal.science/pasteur-0327... I can't find a pdf
hal.science
Conway–Bromage–Lyndon (CBL): an exact, dynamic representation of k -mer sets
Abstract Summary In this article, we introduce the Conway–Bromage–Lyndon (CBL) structure, a compressed, dynamic and exact method for representing k-mer sets. Originating from Conway and Bromage’s concept, CBL innovatively employs the smallest cyclic rotations of k-mers, akin to Lyndon words, to leverage lexicographic redundancies. In order to support dynamic operations and set operations, we propose a dynamic bit vector structure that draws a parallel with Elias-Fano’s scheme. This structure is encapsulated in a Rust library, demonstrating a balanced blend of construction efficiency, cache locality, and compression. Our findings suggest that CBL outperforms existing dynamic k-mer set methods. Unique to this work, CBL stands out as the only known exact k-mer structure offering in-place set operations. Its different combined abilities position it as a flexible Swiss knife structure for k-mer set management. Availability and implementation https://github.com/imartayan/CBL.
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Paul Medvedev @pashadag.bsky.social · 25/09/2025
I've seen it used for storing datasets but I haven't seen it used for pre-prints. If you have any examples, let me know!
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Paul Medvedev @pashadag.bsky.social · 25/09/2025
I hadn't heard of it before, but looking at their webpage: "Effective 8/25/2025, we will be suspending submissions to this generalist server hosted by OSF Preprints."
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Paul Medvedev @pashadag.bsky.social · 25/09/2025
I can appreciate the perspective of bioRxiv about not taking reviews (arXiv is not transparent about their policy). But in the end of the day, the community needs some way to disseminate pre-print reviews that are not just putting them in a shared dropbox folder :(
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Paul Medvedev @pashadag.bsky.social · 25/09/2025
If you're wondering why we're hosting the pre-print via dropbox, its because arXiv (and bioRxiv) did not accept it (because it is a review). Its a bit disconcerting, because a review is precisely the type of paper that would benefit a lot from pre-publication dissemination and feedback.
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Paul Medvedev @pashadag.bsky.social · 25/09/2025
Thank you folks for your feedback on our survey about Hash functions in genomic sequence analysis. We've updated the paper and you can see the new version here: tinyurl.com/4kk9ccmt.
tinyurl.com
Dropbox
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Paul Medvedev @pashadag.bsky.social · 23/09/2025
Are you referring to the randomness of the *location*? If yes, you could plot the distribution of distances between adjacent errors and overlay it with what would be expected under a Poisson model
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Sina Majidian @sinamajidian.bsky.social · 21/09/2025
Excited to share our EvANI benchmarking workflow, published in Briefings in Bioinformatics doi.org/10.1093/bib/... Computing average nucleotide identity (ANI) is neither conceptually nor computationally trivial. Its definition has evolved over years, with different meanings and assumptions (1/5)
Figure 1(A) ANI quantifies the similarity between two genomes. ANI can be defined as the number of aligned positions where the two aligned bases are identical, divided by the total number of aligned bases. Historically, ANI was calculated using a single gene family for multiple sequence alignment. Another approach finds orthologous genes between two genomes and reports the average similarity between their CDSs. This method was later extended to whole-genome alignment by identifying local alignments and excluding supplementary alignments with lower similarity. (B) Different ANI tools employ various approaches in calculating ANI values. ANIm, OrthoANI, and FastANI use aligners to identify homologous regions, whereas Mash uses k-mer hashing to estimate similarities. Only alignments with higher similarity represented by green arrows are included in ANI calculations, while red arrows, corresponding to paralogs, are excluded. (C) The proposed benchmarking method evaluates the performance of different tools using both real and simulated data. It assumes that more distantly related species on the phylogenetic tree should have lower ANI similarities. This is measured by calculating the statistics of Spearman rank correlation. We expect a negative correlation between ANI and the tree distance (scatter plot on the right).
https://academic.oup.com/bib/article/doi/10.1093/bib/bbaf267/8160681
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