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Nicolae Sapoval

@nsapoval.bsky.social
61 followers 144 following 19 posts

Lost in between mathematics, computer science and biology. Hoping to find myself one day. nsapoval.github.io

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Nicolae Sapoval @nsapoval.bsky.social · 13/03/2026
On real gut metagenomes from the IBD patients and healthy controls (portal.microbiome-bioactives.org) we see that the spectral energy offers better separation between condition and control samples that the standard taxonomy-only entropy.
portal.microbiome-bioactives.org
Human Microbiome Bioactives Resource (HMBR) Portal
The data portal for data generated from the Human Microbiome Bioactives Resource
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Nicolae Sapoval @nsapoval.bsky.social · 13/03/2026
Our simulated HGT and genome rearrangement data indicate that our measure is sensitive to these events by design. Thus, in presence of SVs and HGTs we can see differences between samples even if the relative abundance stays nearly identical.
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Nicolae Sapoval @nsapoval.bsky.social · 13/03/2026
Within the new framework based on the spectral energy of the graph sheaf Laplacian we account for both taxonomic composition (albeit not relative abundance yet) and genome architecture of the sample.
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Nicolae Sapoval @nsapoval.bsky.social · 13/03/2026
Metagenome graphs are sensitive to HGTs and SVs. Advait Balaji and I worked on some of these ideas before + Marko Tanevski helped with scaling things up (see: pubmed.ncbi.nlm.nih.gov/35832621/, pmc.ncbi.nlm.nih.gov/articles/PMC...). However, these prior analyses were taxonomy oblivious by design.
sciencedirect.com
KOMB: K-core based de novo characterization of copy number variation in microbiomes
Characterizing metagenomes via kmer-based, database-dependent taxonomic classification has yielded key insights into underlying microbiome dynamics. H…
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Nicolae Sapoval @nsapoval.bsky.social · 13/03/2026
The idea was inspired by a recent preprint about sheaves on graphs and their potential use for classical ecological diversity indices (see: arxiv.org/abs/2601.17466). The literature on sheaves on graphs is very exciting in itself, but the key idea we use is quite simple.
arxiv.org
$β$-diversity and Graph Sheaf Laplacians
We suggest a new approach to $β$-diversity in ecological systems, based on the energy of the graph sheaf Laplacian associated with the sample data. This scalar quantity is easily computable using meth...
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Nicolae Sapoval @nsapoval.bsky.social · 13/03/2026
Our new preprint on quantifying microbial sample diversity/complexity in a way that accounts for both metagenome architecture and taxonomic composition is now live on bioRxiv: www.biorxiv.org/content/10.6... #metagenomics #bioinformatics #dataanalysis #graphdata
biorxiv.org
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Nicolae Sapoval @nsapoval.bsky.social · 22/02/2026
Our new preprint on the inconsistency of the combined gene tree parsimony costs is now live on bioRxiv: www.biorxiv.org/content/10.6...
biorxiv.org
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Nicolae Sapoval @nsapoval.bsky.social · 28/11/2025
[4/4] Our approach is by design a meta-method: you can use it with your favorite single-cell RNA-based GRN inference tool, and squeeze more insights out of your data! Check us out GitHub: github.com/aliaaz99/GRN.... #singlecell #GRN #LLM
github.com
GitHub - aliaaz99/GRNITE
Contribute to aliaaz99/GRNITE development by creating an account on GitHub.
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Nicolae Sapoval @nsapoval.bsky.social · 28/11/2025
[3/4] We use these embeddings to construct a prior graph and then further refine it with some known TF-target interactions as pre-training targets. Finally, we use this augmented prior graph jointly with a GRN inferred by *any* other method, in order to produce a final prediction.
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Nicolae Sapoval @nsapoval.bsky.social · 28/11/2025
[2/4] We use gene descriptions from NCBI Gene database and embed them into a high-dimensional space with a LLM (Qwen3-8B). This idea was inspired by GenePT (pubmed.ncbi.nlm.nih.gov/37905130/) and a great study on gene embeddings from @vyao.bsky.social's group (www.biorxiv.org/content/10.1...).
pubmed.ncbi.nlm.nih.gov
GenePT: A Simple But Effective Foundation Model for Genes and Cells Built From ChatGPT - PubMed
There has been significant recent progress in leveraging large-scale gene expression data to develop foundation models for single-cell biology. Models such as Geneformer and scGPT implicitly learn gene and cellular functions from the gene expression profiles of millions of cells, which requires exte …
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Nicolae Sapoval @nsapoval.bsky.social · 28/11/2025
Check out our new preprint on improving gene regulatory network inference by incorporating a prior from plain-text gene descriptions. It's a simple idea, but we show that it proves to be quite powerful and adaptable. [1/4] www.biorxiv.org/content/10.1...
biorxiv.org
GRNITE: Gene Regulatory Network Inference with Text Embeddings
Gene regulatory networks (GRNs) capture complex regulatory relationships that govern gene expression in cells. Inference of GRNs from single-cell RNA-seq (scRNA-seq) data has been an active topic of r...
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Reposted by Nicolae Sapoval
Sina Majidian @sinamajidian.bsky.social · 06/11/2025
Nicolae Sapoval @nsapoval.bsky.social presented "Theoretical and empirical performance of pseudo-likelihood- based Bayesian inference of species trees under the multispecies coalescent" A fantastic theory talk, offering intuitive insights! Paper: doi.org/10.1101/2025.01.28.635282
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Nicolae Sapoval @nsapoval.bsky.social · 02/02/2025
As the next step, we aim to develop rigorous corrections to the pseudo-likelihood-based credibility intervals in order to further improve scalability and applicability of Baeysian phylogenomic inference.
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Nicolae Sapoval @nsapoval.bsky.social · 02/02/2025
In our work we explore suitability of pseudo-likelihood for Bayesian phylogenomic inference. We show that using pseudo-likelihood greatly reduces the computational burden of the Bayesian inference. However, the inferred credibility intervals are overconfident.
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Nicolae Sapoval @nsapoval.bsky.social · 02/02/2025
Likelihood-based phylogenomic inference is common, but it faces scalability issues. Hence, pseudo-likelihood has been previously proposed as a statistically consistent (for topology estimation) and scalable alternative: doi.org/10.1186/1471...
doi.org
A maximum pseudo-likelihood approach for estimating species trees under the coalescent model - BMC Ecology and Evolution
Background Several phylogenetic approaches have been developed to estimate species trees from collections of gene trees. However, maximum likelihood approaches for estimating species trees under the c...
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Nicolae Sapoval @nsapoval.bsky.social · 02/02/2025
Our preprint on using pseudo-likelihood for Bayesian inference of species trees from gene tree data under the multispecies coalescent is now online: doi.org/10.1101/2025... [1/n]
doi.org
Theoretical and Empirical Performance of Pseudo-likelihood-based Bayesian Inference of Species Trees under the Multispecies Coalescent
Likelihood-based inference under the multispecies coalescent provides accurate estimates of species trees. However, maximum likelihood and Bayesian inference are both computationally very demanding. P...
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Nicolae Sapoval @nsapoval.bsky.social · 01/01/2025
In case if you lose the URL (it’s not pretty), I have linked this on my website (nsapoval.github.io) as well.
nsapoval.github.io
Nicolae Sapoval
A simple, whitespace theme for academics. Based on [*folio](https://github.com/bogoli/-folio) design.
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Nicolae Sapoval @nsapoval.bsky.social · 01/01/2025
This is aimed primarily at the people who are just starting their thesis-based masters or a PhD. However, it’s also an evolving document, so suggestions and ideas are welcome!
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Nicolae Sapoval @nsapoval.bsky.social · 01/01/2025
It’s that time of the year when I get some writing done. Here are some notes on how I work with academic literature: plume-lifeboat-00b.notion.site/How-I-find-o...
plume-lifeboat-00b.notion.site
How I find, organize, and read papers | Notion
Introduction
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Nicolae Sapoval @nsapoval.bsky.social · 05/12/2024
I just completed "Ceres Search" - Day 4 - Advent of Code 2024 #AdventOfCode adventofcode.com/2024/day/4 (A little bit behind the schedule this year, but gotta keep it going)
adventofcode.com
Day 4 - Advent of Code 2024
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Reposted by Nicolae Sapoval
Todd J. Treangen @treangen.bsky.social · 14/11/2023
I was waiting for a great topic for my first Bluesky post, and I cannot thing of a better one: I’m thrilled to be hosting @aphillippy.bsky.social at Rice University today and looking forward to his talk at 4pm! events.rice.edu/event/345896...
events.rice.edu
Distinguished Lecture: Dr. Adam Phillippy
A Ken Kennedy Institute Distinguished Lecture by Dr. Adam Phillippy, Senior Investigator at National Human Genome Research Institute, National Inst...
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