Arjun Raj

Arjun Raj

@arjunraj.bsky.social

Just another LLM. Tweets do not necessarily reflect the views of people in my lab or even my own views last week. http://rajlab.seas.upenn.edu https://rajlaboratory.blogspot.com

6,556 Followers 1,019 Following 401 Posts Joined Jul 2023
1 month ago

A moment of introspection on how much the world has changed during the time between the initial submission and this (hopefully final) revision:
"This paper seems so quaint now"
"Let's think of it as having contributed an important bit of high-quality training data to Opus 4.7"

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1 month ago

Claude Code demo, planning another with more details.

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1 month ago

Ran an AI coding workshop with the lab. There was a palpable sense of sadness realizing that skills some of us have spent our lives developing (myself included) are a lot less important now. I see the future 100%, but I do think it's important to acknowledge this sense of loss.

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1 month ago
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ft. Sam Reffsin, Margaret Dunagin, Yael Heyman, @arjunraj.bsky.social (Bioeng), Jesse Miller, Kasirajan Ayyanathan, Sara Cherry (@pennpathlabmed.bsky.social), @naveen-jain.bsky.social (@cambupenn.bsky.social) & David Schultz (BioBio) @penngenetics.bsky.social www.sciencedirect.com/science/arti...

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1 month ago

The TIG1-high state exists in human lung club and ciliated cells, enriched in IPF patients and tobacco users. Different viruses target different states. Influenza A prefers KRT8-high cells. Arjun Raj @cp-cell.bsky.social
doi.org/10.1016/j.ce... 🧪
3/3

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1 month ago

Reffsin, Miller, Cherry & Raj et al. discover that intrinsic cell states determine which cells become infected with SARS-CoV-2. Using single-cell clone tracing, they identified a TIG1-high state marking highly susceptible cells. What makes these cells vulnerable? 👇🏻
1/3

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1 month ago
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Chance favors the (theoretically) prepared mind In defense of the role of theory in innovation

Data and experiments move faster, but theory is what gives discovery direction, via @arjunraj.bsky.social
arjunrajlab.substack.com/p/chance-fav...

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2 months ago

We spend a lot of energy choosing the right research project. But an equally important skill is knowing when to walk away.

Quitting isn’t failure: It’s how you make room for better science, via @arjunraj.bsky.social

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2 months ago
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Liberty Puzzles | Wooden Jigsaw Puzzles The original wooden jigsaw puzzle maker. Established in 2005, all of our 1000+ puzzles are handmade in Boulder, CO with exquisite quality & craftsmanship. Full of odd-shaped "whimsy" pieces, our woode...

libertypuzzles.com these are very nice

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2 months ago
My left hand with Avagadro’s Constant

Anyone have a thought about this weird mol on my hand?

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2 months ago

Where do you get your groceries? Where are your retirement funds invested? Etc.

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2 months ago

I gotta say… it’s just less fun here. I want it to work, but…

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2 months ago

Congratulations!!

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8 months ago
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I am happy to share that I’ve been awarded tenure here at Columbia University. Alhamdulillah. I thank my wife, parents, mentors, colleagues, friends, and family. I thank my lab members, present and past, for entrusting their careers in my hands and making this a thrilling journey.

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2 months ago

I can say that the discussion on X are definitely more interesting. Here, it’s like AI isn’t even happening.

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2 months ago

Both, and things in between. It’s highly variable as to how much it can do autonomously in both cases. Probably depends on how much training data there is.

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2 months ago

Both. General purpose non-coding agent ;).

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2 months ago

Huh. I think the scope it can handle probably depends on the nature of the challenge (how much it is in distribution) and on the planning and amount of testing you have in place. I have found it able to do some pretty remarkable features, one-shotting a lot of non-trivial boilerplate.

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2 months ago

Haven't run into trouble yet! But I've been sadly too busy to code as much as I have wanted.

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2 months ago

What I have not explored but should is non-coding uses.

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2 months ago

Much to say, but to summarize: 🤯

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2 months ago

I think that’s the first sign of the apocalypse, no?

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2 months ago

AI is awesome, and is most definitely a transformative technology.

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2 months ago

To me, the mean loud position here ranges between ignoring the ai and wishing to fully ban it. The latter won't happen (I don't think even regulation is technically feasible), the former is massively unproductive. If scientists refuse to participate in the discussion,it will just be driven by others

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2 months ago

So… Bluesky for science and X for Claude Code?

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2 months ago
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Chance favors the (theoretically) prepared mind In defense of the role of theory in innovation

Blog post: Chance favors the (theoretically) prepared mind
Data is big, machines are learning, so what good is theory anyway? Isn't most discovery driven by serendipity anyway, with theory mostly a "post-mortem"? I argue that this view discounts the value of theory.
open.substack.com/pub/arjunraj...

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2 months ago

Beautiful - recommended! Here, @sasolla.bsky.social recaps her decades-long journey from physics to neural networks (working with LeCun & Hopfield) to motor cortex, & and from industry (including Bell Labs) to academia, all driven by curiosity and awe (which flows from her voice). Inspiring!

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2 months ago

i've re-implemented PoPE from scratch as part of a model overhaul (w/ Claude Code). i don't have clean ablations yet but it's working. took about two hours to re-write my entire model

i think the PoPE idea is really cool and a great fit for scientific data

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2 months ago

Congratulations on tenure!

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2 months ago

2025 was the year we stopped debating whether paying peer reviewers might work and started showing that it does.

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