pujjad
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1 year ago
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on: Could this startup's compact nuclear reactors revolutionize cancer detection?
And yes you're right, it's a neutron generator. They don't claim to ever achieving break even, or even power surplus. No fusion startup will ever do in my view. Combining that neutron generator with active material, now we're talking. That's a sub critical ultra compact hybrid reactor, which becomes super critical by pressing a button. And sub critical again with another press. That's the future and the reason why some folks at NASA want to get hold of one for their future space mission
pujjad
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1 year ago
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on: Could this startup's compact nuclear reactors revolutionize cancer detection?
Huge difference. Fusors are just Inertial electrostatic confinement fusion devices. This one here adds lattice confinement fusion to it (see NASA Glenn Research two Phys Rev C papers in 2023), ie you reach fuel densities 6 to 8 orders of magnitudes higher than in a plasma as you exploit electron screening in your metal lattice, plus binary packing in specific metal alloys. Anyone can build a fusor in a kitchen, but these guys combine two entirely different fusion mechanisms (IEC+LFC) which hasn't been done before. That way you get minimum 1E11 DT neutrons/s at source, and even higher fluxes once you start optimising the materials involved. A hard 14 MeV DT neutron generator with that high flux? A golden opportunity for testing future materialsand electronics in a harsh fusion environment.
A fusor does 1E6 n/s at best, and that'd be 2.45 MeV DD neutrons only, because obtaining a Tritium license is not trivial.
pujjad
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3 years ago
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on: Open source and the future of nuclear physics
pujjad
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3 years ago
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on: Open source and the future of nuclear physics
The article mmentions Moose, MFEM, OpenMC, but the really good stuff relevant for us nuclear physicist I would expect being talked about aren't mentioned: Bison, Transuranus, Marmot, Serpent, Vasp, Rattlesnake, Fispact.
On the open source open access side I'm missing Lammps or Geant4.
pujjad
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3 years ago
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on: Strange new phase of matter acts like it has two time dimensions
It's an argument pro two-time scales and against two dimensional time just by looking at what math says about partially ordered sets. R^2 is clearly not partially ordered as opposed to R^1.
pujjad
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3 years ago
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on: Strange new phase of matter acts like it has two time dimensions
In a world with two time dimensions there would be no such thing as causality: with a, b \in R^2 (the field of real numbers), a<b doesn't make sense, because two events can have the same distance from (0,0) but different angle \phi (modulo orientation of chosen frame of reference), and therefore I wouldn't be able to distinguish between past and future events in general. Causality breaks down.
Propagating along a 1D trajectory (ie flow of time) would then be along a 2D "trajectory" through which I would experience indefinitively many events at once, unclear which one impacts on which others. But clearly I perceive me writing this post "right now", and am about to push the send button..
pujjad
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5 years ago
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on: Treaty to ban nuclear weapons made official with 50th UN signatory
That is, in 90 days!
pujjad
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5 years ago
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on: Treaty to ban nuclear weapons made official with 50th UN signatory
Fantastic news! Been waiting for this since I've been with the CTBTO 13 years ago.. No testing on land of the pacific nations anymore! Hopefully the 5 big nuclear weapon states will ratify the CTBT in my lifetime as well...
pujjad
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5 years ago
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on: Why does organic milk last so much longer than regular milk? (2008)
In Germany, the consumer demand for UHT is low as well. Fresh milk is prefered over that, UHT tastes weird for most. No idea where the article gets the idea from that Europeans care less about UHT.
pujjad
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5 years ago
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on: Declining eyesight improved by looking at deep red light
Extracted from the accepted manusscript:
"670nm light devices were based on simple commercial DC torches with ten 670nm LEDs mounted behind a light diffuser embedded in a tube that was 4cm in diameter. Energies at the cornea were approximately 40mW/cm² which often resulted in a mild green after image for approximately 5-10 seconds. Participants were asked to use the light to illuminate their dominant eye every morning for 3 minutes and to repeat this daily for 2 weeks. These metrics were selected because they fell within the range used in a large number of animal experiments. 670nm illumination was largely confined to the central retina comprising the peaks in rod and cone density."
pujjad
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5 years ago
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on: Declining eyesight improved by looking at deep red light
Maybe have them shine on to a neutral surface with some distance.
pujjad
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5 years ago
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on: Declining eyesight improved by looking at deep red light
What a great idea, thanks!
pujjad
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5 years ago
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on: Declining eyesight improved by looking at deep red light
What's the best way to make them red torches?
pujjad
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5 years ago
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on: Programming at the REPL (2018)
pujjad
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5 years ago
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on: Hacker News Upvote
Hacker News Comment
$7.50
"We recommend buying at least one comment with each post, in order to shape opinions from the get-go. Anchoring is a powerful psychological weapon."
https://upvotes.club/buy/hacker-news-comment/
Well, this anchor is for free - buying HN upvotes/ comments seems unfair and distorting.
pujjad
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5 years ago
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on: 4D Toys: how objects bounce and roll in 4D – paper accepted to SIGGRAPH 2020
If there were 4 spatial dimensions + 1 time dimension we would end up in an unstable universe.
Ehrenfest (1917/1920) studied the hydrogen in n dimensions and concluded for n> 3 that neither classical atoms nor planetary orbits can be stable, because the inverse square law of electrostatic and gravity becomes an inverse cube law. When n > 3 there are no stable orbits to the two body problem: an incoming light body attracted by a heavy one would either escape to infinity or get sucked into collision.
For n = 3 we get stable elliptic orbits or non-bound parabolic and hyperbolic orbits.
Collision only occurs when the lighter body heads directly towards the heavy body within 2R (R being the heavier body's radius), ie. the impact parameter is zero [2]
[1] https://doi.org/10.1002/andp.19203660503
[2] https://en.wikipedia.org/wiki/Impact_parameter
edit: grammar
pujjad
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6 years ago
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on: Pandemic Ventilator Project
Someone dear to me needs a ventilator per tracheostomy (Trilogy 100). Her Consultant Aenesthesist who was in Italy four weeks ago and works on an Intensive Care Unit told me that 6 out 10 Covid-19 affected ITU patients require an ECMO (
https://en.m.wikipedia.org/wiki/Extracorporeal_membrane_oxyg...). This is very bad. I could sense his unease, these are machines you don't come by easily. His ITU is preparing for war, Brexit and the conservative's austerity program has put the NHS to breaking point.
pujjad
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6 years ago
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on: KDE Connect
Been using it to control my projector from my sofa when watching stuff: the remote control allows me to pause, skip intro or choose a different film altogether.
pujjad
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6 years ago
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on: German banks are hoarding so many euros they need more vaults
Yep I get that, but the artist playing at our charity festival have complaint every time about having to deal with cheques both I (treasurer) and the other finance officer have to sign. Why is it that in the 21st century we can't have a digital online two-signature policy yet have to sign a paper which signatures one easily can forge. That's backwards. We got cryptocurrencies but no way to implement a digital two-signature policy? Odd.
pujjad
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6 years ago
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on: German banks are hoarding so many euros they need more vaults
But in the UK we do. You can set up a bank accounts which requires two signatures, then only cheque payments are possible. Very quiant, annoying and backwards.
