Caleb Ellington @probablybots
Scientist @genbioai | PhD @CMUCompBio | Creator/maintainer https://t.co/E3h3NJS6S7 | multi-task learning, graphical models, and personalized medicine calebellington.com San Francisco, CA Joined December 2017-
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We built a joint experimental and computational platform for scalable multi-modal single-cell chemical screens — profiling RNA, protein (including phospho-signaling), and chromatin accessibility responses to thousands of small molecule perturbations in parallel. biorxiv.org/content/10.648…
Like with cybersecurity, I expect the offense is only temporarily at an advantage in science, but ultimately defense will win out with automated peer review like this. I am excited for science to become more and more trustworthy when any paper can be reproduced on-demand.
We also repurposed our agents as very attentive peer reviewers to try reproducing our hand-made results from scratch, and kept updating our manuscript until we ironed out all documentation issues. This should be the standard for reproducibility in all information sciences today.
Before we put this study online, we reproduced it from scratch 3 times with Claude Code and Codex. It took about 6-8 hours each time. There's a higher bar for scientific rigor and reproducibility when you want work to be built on by both human and agent scientists.
Virtual cells are supposed to help drug discovery. Why aren't they evaluated on drug discovery tasks? In our new preprint "Cell-Level Virtual Screening," we investigate this and other fundamental questions about practical applications of virtual cells for drug discovery.
Frontier LLMs are converging on efficient, adaptive reasoning. Opus 4.7 lets the model decide how deeply to reason. GPT-5.5 achieves strong results with fewer reasoning tokens. We study a related but more structural question: what 𝗸𝗶𝗻𝗱 𝗼𝗳 𝗿𝗲𝗮𝘀𝗼𝗻𝗶𝗻𝗴 should we adapt? Last year in SiRA (upper figure), we showed that simulative reasoning (System II), which uses a 𝘄𝗼𝗿𝗹𝗱 𝗺𝗼𝗱𝗲𝗹 to evaluate consequences of actions, yields up to 124% improvement over reactive baselines (System I), and that strong reasoning models (o1, o3-mini) fail as planners without this structure. In our new paper SR²AM (lower figure), we add a learned 𝗰𝗼𝗻𝗳𝗶𝗴𝘂𝗿𝗮𝘁𝗼𝗿 (System III) that self-regulates when to simulate, how far ahead, and when to skip planning entirely. Efficient reasoning is not just shorter reasoning: it is better allocation of simulation.
LLM training is built on fast MatMuls. But many surrounding ops still run as memory-bound kernels. CODA reparameterizes them to hide in the matmul’s shadow, fused into its epilogue before results leave the chip. Bonus: LLMs can write fast CODA kernels too (approaching SoLs).
Last month, we shared research on why LLMs fail at data analysis: even the best models hallucinate answers when reasoning over structured data. Today we're launching what we've built to fix it. Summand is now live at summand.com. What most teams want is simple: plug AI into their data and get answers they trust. Most "chat with your data" tools try to deliver that by translating your question into SQL and hoping for the best. Summand does something harder: it builds up a real understanding of your data. What your columns actually mean, how your tables relate, where the edge cases live. You can contribute to that understanding too, and so can the agent. Under the hood, that understanding is grounded in interpretable ML and a semantic layer purpose-built for structured data. That's what makes the answers trustworthy. Why the name “Summand”? Just like how a summand is a term in a summation, Summand decomposes your data into interpretable reasoning components. By breaking complicated outcomes into simple patterns, Summand makes downstream AI systems reliable and transparent. *What this means to you:* Connect your data to Summand.com, start asking questions immediately, and power your downstream AI applications through Summand’s MCP access. Try it today → summand.com
Huge thanks to the excellent co-authors behind this work: Sohan Addagudi, @JiaqiWang_, @ben_lengerich, and @ericxing. This is the final chapter of my phd, but you'll continue seeing this kind of work reflected at @genbioai in our work on general-purpose biological simulators.
We curated DDR-Bench and DTR-Bench to validate virtual cells on practical drug discovery tasks and enable hill-climbing on useful hills. We make one contribution to cell-level screening with CellVS-Net, but the ceiling is still quite far away! Pre-print: biorxiv.org/content/10.648…
Virtual cells are supposed to help drug discovery. Why aren't they evaluated on drug discovery tasks? In our new preprint "Cell-Level Virtual Screening," we investigate this and other fundamental questions about practical applications of virtual cells for drug discovery.
Han Guo @HanGuo97
4K Followers 4K Following PhD Student @MIT_CSAIL | Past: @togethercompute @LTIatCMU @MITIBMLab @UNCNLP, @SFResearch, @BaiduResearch | Machine Learning, NLP.
April @sciApril
610 Followers 902 Following computational biology PhD candidate @CMUPittCompBio | dog lover but has cats | 🎥 science YouTuber (@thebiozone) | she/her
Anshul Kundaje @anshulkundaje
31K Followers 3K Following Federally funded academic research is the innovation engine of the US economy. Reform is welcome. Destruction will have long term consequences.
Manolis Kellis @manoliskellis
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Ben Lengerich @ben_lengerich
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Hongyi Wang @HongyiWang10
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Mingkai Deng @mdeng34
726 Followers 331 Following PhD student @LTIatCMU | MSML @MLDCMU | BA Math-Stats + CS @Columbia | World models and agent models
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Jacob Schreiber @jmschreiber91
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DataQuant Consulting @DataQuantAI
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오창명 @changmyung1981
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Andrew Natenshon @Natenshon
243 Followers 4K Following Working with AI to improve drug development and more. Ex-Moderna
Ravi Pandya @ravinpandya
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Lled @dbsngdjdbdk
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Withans @Vannthies
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Scott Gleim @sgleim
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Mohit Nihalani @MohitNihalani9
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Steph Suddell @stephsuddell
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Aoyang Chen @aoyangchen
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Nikhil Maturi @MaturiNikh50601
2 Followers 96 Following AI + Science for a better world and random musings. Aspiring Kardashev Climber. https://t.co/lGjBf8uZHu
Andres F Vallejo 🧬... @afvallejop
321 Followers 710 Following Associate Professor in Computational Biology and Transcriptomics University of Southampton
TAO e/acc @hacher33919
432 Followers 7K Following The future smart economy will not be controlled by centralized companies, but will be run by open model networks.
Derek Croote @DerekCroote
548 Followers 1K Following Co-founder & CTO of clinical-stage antibody therapeutics co @IgGenix | Following trials with @trialinference | Previously @Stanford bioengineering PhD
Professor Oak @Prof_Oak_
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Philip Marais @fijnmin
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Omar Arias-Gaguancela... @omar_arias_g
77 Followers 552 Following Passionate about Protein Modeling Frameworks
Angelica Parente (in ... @draparente
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AI Deeply @AiDeeply
519 Followers 7K Following AI is reshaping the world. Visit https://t.co/aZgAXUcZbe to learn more about the people and companies driving the change.
Kabir H Biswas, PhD @kabirhbiswas
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Edmund Miller @E_Miller88
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Voice of Novice @voiceofnovice
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xtwirer.account @xtwirer
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Jian Ma @jmuiuc
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Eric Xing @ericxing
9K Followers 22 Following Researcher, educator, entrepreneur, and administrator in computer science, artificial intelligence, and healthcare.
Han Guo @HanGuo97
4K Followers 4K Following PhD Student @MIT_CSAIL | Past: @togethercompute @LTIatCMU @MITIBMLab @UNCNLP, @SFResearch, @BaiduResearch | Machine Learning, NLP.
April @sciApril
610 Followers 902 Following computational biology PhD candidate @CMUPittCompBio | dog lover but has cats | 🎥 science YouTuber (@thebiozone) | she/her
Anshul Kundaje @anshulkundaje
31K Followers 3K Following Federally funded academic research is the innovation engine of the US economy. Reform is welcome. Destruction will have long term consequences.
Manolis Kellis @manoliskellis
46K Followers 4K Following Dissecting disease mechanism. Single-cell, Epigenomics, Regulatory Genomics, Disease Genetics, Brain, Cancer, Metabolism. @MIT Prof, @MIT_CSAIL, @BroadInstitute
Fabian Theis @fabian_theis
37K Followers 429 Following Computational biologist @HelmholtzMunich, prof @TU_Muenchen & associate PI @sangerinstitute. Dad of 4 and mountain lover. Department news, see @CompHealthMuc
Ben Lengerich @ben_lengerich
1K Followers 393 Following Asst Prof @UWMadison Stats, CS, Biomedicine. Research group: @AdaptInferLab. Founder: @IntelligibleAI Personal: Christian, husband, father.
Hongyi Wang @HongyiWang10
2K Followers 2K Following Assist. Prof. @RutgersCS; Head of Infra @genbioai; Ex @mldcmu @WisconsinCS
Mingkai Deng @mdeng34
726 Followers 331 Following PhD student @LTIatCMU | MSML @MLDCMU | BA Math-Stats + CS @Columbia | World models and agent models
Michael Schatz @mike_schatz
16K Followers 1K Following Bloomberg Distinguished Professor of Computer Science and Biology at Johns Hopkins University
@BaDoiPhan.bsky.socia... @BadoiPhan
334 Followers 412 Following Anesthesia resident, physician scientist genomics & addiction neurobiology 🌈 &🐱 dad
Jacob Schreiber @jmschreiber91
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Zachary Lipton @zacharylipton
66K Followers 2K Following Professor: CMU/@acmi_lab, Cofounder: @AbridgeHQ, Creator: @d2l_ai & https://t.co/QQt98VNLUp, Relapsing 🎷
Maruan Al-Shedivat @alshedivat
1K Followers 510 Following ML Research @genesismolai | Ex-@OpenAI, Ex-@GoogleAI | PhD in ML from @CarnegieMellon (@mldcmu)
spencer hong @spencersunoo
376 Followers 394 Following making agents do some cool stuff @intelligenceco | formerly genai @capitalone phd @amarallab cheme @cornell @clancygroup
Josh Welch @LabWelch
2K Followers 545 Following Computational Biologist, Associate Professor at U. Michigan
Mechanize @MechanizeWork
14K Followers 1 Following We build environments and evals for training and evaluating frontier coding agents.
Zack Ellington @zack_ellington
1 Followers 0 Following
Ian Quigley @allmeasures
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Professor Oak @Prof_Oak_
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David Garfield (@daga... @dagarfield
2K Followers 1K Following AI for Life Sciences at Anthropic. Former drug target hunter at Genentech and Bayer. Recovering marine biologist. Always an evolutionist. Views are my own.
SemiAnalysis @SemiAnalysis_
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Chris Hayduk @ChrisHayduk
8K Followers 3K Following FDE, Life Sciences @OpenAI | Cross-disciplinary writing on AI & where we're going at https://t.co/gmBIh9hlZI | ex MLE @Meta, Drug Discovery Lead @Deloitte
black_box @blackbox_pi
137 Followers 904 Following Tweeting about #AI and #genomics | interpretable ML models | perturbation models | transcription factors | cis-regulatory elements | motifs | gene regulation
dough though @domenjemec
23 Followers 249 Following Bio, ML, building fun things. | Founder @gptomics Opinions expressed are my own.
Phil Fradkin @phil_fradkin
676 Followers 828 Following Born too late to explore the Earth Too early explore the Galaxy Just in time to study comp bio and climb some rocks PhD VectorInst & UofT CoFounder @BlankBio_
ClaudeDevs @ClaudeDevs
466K Followers 3 Following Official updates for developers building with @ClaudeAI
SLIME MOLD TIME MOLD @mold_time
13K Followers 418 Following "If one does not expect it, one will not find out the unexpected; It is not to be tracked down and no path leads us to it." // https://t.co/YLVd6o5tdr
Markov's Chainsaw @markovschainsaw
287 Followers 3K Following once and future quant. A/B jester. cultivating nobility. approximating posterior.
David van Dijk @david_van_dijk
6K Followers 4K Following Yale Professor | Founder & CEO @CellTypeInc (YC W26) | AI + Drug Discovery
Hao AI Lab @haoailab
6K Followers 370 Following Hao AI Lab at UCSD. Our mission is to democratize large machine learning models, algorithms, and their underlying systems.
Bin Shao @ShaoBin_phy
738 Followers 1K Following Broadie. deep learning; synthetic biology; single cell genomics; non-linear dynamics. opinions are my own.
Claude @claudeai
1.4M Followers 2 Following Claude is an AI assistant built by @anthropicai to be safe, accurate, and secure. Talk to Claude on https://t.co/ZhTwG8d1e5 or download the app.
CellType @celltypeinc
2K Followers 4 Following We're building the agentic drug company. Foundation models + AI agents that simulate human biology to discover drugs. Backed by Y Combinator (W26).
Emma Lundberg @Prof_Lundberg
3K Followers 830 Following Assoc Prof. of #bioengineering and #pathology at @Stanford and @KTHUniversity, Director of the HPA Cell Atlas. Interested in cells, imaging and AI.
Aviv Bick @avivbick
634 Followers 22 Following CS PhD @ CMU https://t.co/tCKYiUbOdr | https://t.co/zdDNelFVJO
Dylan Reid @dreidco
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Coefficient Bio @CoefficientBio
416 Followers 5 Following
muni @muni_bio
210 Followers 3 Following An agentic platform for scientific discovery, connecting computational exploration with experimental validation
Yun S. Song @yun_s_song
4K Followers 247 Following Professor of EECS and Statistics @UCBerkeley. Mathematical and computational biologist. bsky handle: https://t.co/bW59tUBr8m
Patrick Kidger @PatrickKidger
11K Followers 241 Following 🚀 Doing something new. Curing uncured diseases. 🧪 antibodies+AI, neural ODEs, open-source JAX ecosystem. 👨💻 ex-{Cradle, Google, Oxford}.
Caltrain @Caltrain
115K Followers 472 Following The Official X account for Caltrain. Follow @CaltrainAlerts for service updates, login is required to view information.
Jérémie Kalfon @jkobject
570 Followers 2K Following Doing a Ph.D. AI in Bio. | Ex @WhiteLabGx @BroadInstitute @MIT | Built @PiPleteam | ML, Cancer, Genomics, Data Sci, Entrepreneur, FullStack Dev | All Views Mine
Euxhen Hasanaj @EuxhenH
78 Followers 127 Following Research Scientist @genbioai | PhD, Machine Learning @mldcmu, AI x Biotech
Joseph Suarez 🐡 @jsuarez
29K Followers 123 Following I build sane open-source RL tools. MIT PhD, creator of Neural MMO and founder of PufferAI. DM for business: non-LLM sim engineering, RL R&D, infra & support.
Chaitanya K. Joshi @chaitjo
10K Followers 1K Following AI researcher excited about biomolecule design 🧬 Postdoc @Stanford @RDasLab PhD student @Cambridge_Uni Prev. FAIR @AIatMeta @PrescientDesign @MRC_LMB
Lazar Atanackovic @lazar_atan
686 Followers 999 Following Building generative models for biology. Asst Prof @UAlberta · Fellow @AmiiThinks · ex-@broadinstitute @UofT
Ari Wagen @AriWagen
1K Followers 693 Following building the arsenal of discovery for drugs & materials @RowanSci, anti-gnostic
Marine Schimel @marineschimel
285 Followers 300 Following Postdoctoral Researcher in Computational Neuroscience @ Stanford | Previously PhD student @ Cambridge CBL


























