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tobychev boosted

When Biden said "the US is back", evidently he meant "back at its old tricks":

"The United States 🇺🇲 objected to the outcome of the Transitional Committee meeting on . [...]

The United States further demanded that financial contributions from developed countries to the Loss and Damage Fund be voluntary, thereby removing any mandatory obligation for these nations to provide assistance to developing countries.

twitter.com/harjeet11/status/1"

@rhizome
the entire joke is that economics is a subset of sociology :)
@philipncohen

tobychev boosted

Update on my
mastodon.social/@franco_vazza/
it has been peer-reviewed 😄 and some of the numbers I gave were based on outdated references and my wrong estimate of current uncertainties in photon diffusion in the Sun.
This means that the actual best escape time of photons from the Sun is on the lower limit of my quoted values (~180,000 years).

A more updated reference for this is arxiv.org/abs/1402.5482, suggested by @RauscherThomas 🙏

Tooting outside of own comfort zone is a good way to learn!

tobychev boosted

All right, I've just learned that it was my #Fediversary yesterday and I have a new paper out on arxiv today, so let's celebrate all that with an #astrodon 🧵 on magnetized accretion, and it's surprising connections with turbulence in ... pipes !

arxiv.org/abs/2311.00034

Magnetorotational dynamo can generate large-scale vertical magnetic fields in 3D GRMHD simulations of accreting black holes

Jetted astrophysical phenomena with black hole (BH) engines, including binary mergers, jetted tidal disruption events, and X-ray binaries, require a large-scale vertical magnetic field for efficient jet formation. However, a dynamo mechanism that could generate these crucial large-scale magnetic fields has not been identified and characterized. We have employed 3D global general relativistic magnetohydrodynamical (MHD) simulations of accretion disks to quantify, for the first time, a dynamo mechanism that generates large-scale magnetic fields. This dynamo mechanism primarily arises from the nonlinear evolution of the magnetorotational instability (MRI). In this mechanism, large non-axisymmetric MRI-amplified shearing wave modes, mediated by the axisymmetric azimuthal magnetic field, generate and sustain the large-scale vertical magnetic field through their nonlinear interactions. We identify the advection of magnetic loops as a crucial feature, transporting the large-scale vertical magnetic field from the outer regions to the inner regions of the accretion disk. This leads to a larger characteristic size of the, now advected, magnetic field when compared to the local disk height. We characterize the complete dynamo mechanism with two timescales: one for the local magnetic field generation, $t_{\rm g}$, and one for the large-scale scale advection, $t_{\rm adv}$. Whereas the dynamo we describe is nonlinear, we explore the potential of linear mean field models to replicate its core features. Our findings indicate that traditional $α$-dynamo models, often computed in stratified shearing box simulations, are inadequate and that the effective large-scale dynamics is better described by the shear current effects or stochastic $α$-dynamos.

arxiv.org

"Austerity — public spending cuts to reduce government debt — is associated with severe economic costs through lowering GDP, employment, private investment, and wages.

But the effects of public spending cuts on extreme party' vote shares have been badly-understood. This is now starting to change.

In a recent study, three academics, Ricardo Duque Gabriel, Mathias Klein and Ana Sofia Pessoa, have been able to convincingly show that austerity measures have been a significant driver of political extremism across Europe."

euobserver.com/green-economy/1

@telescoper
Are you sayin you could have done it all with a bunch of well trained fireflies and heat coils on a big dome, for half the cost and in a fraction of the time?

@kevinrothrock
Honestly, if the source had been any of the parties I'd assumed they would be lying and really it was about helping the DPRK with its ballistic missiles.

But if the South Koreans are saying it is for a "space program", that sure sounds like Russia is trading civilian expertise in exchange for military goods... I guess Kim feels the DPRK is strong enough to part with some significant military resources?

tobychev boosted

At a fascinating Santa Fe Institute meeting on Accelerating Science. Chiara Franzoni gave a fascinating talk about what it takes to fund high risk science, and it left me thinking.

When we evaluate grant proposals for an NSF or NIH panel, several panel members evaluate each proposal — and this sets up the classic sort of preference aggregation problem that is the bread and butter of public choice theory.

Yet we typically ignore the preference aggregation issue.

tobychev boosted

Physicist William Higinbotham was born OTD in 1910. During the Manhattan Project he was the Electronics Group leader at Los Alamos.

In 1958, while working at Brookhaven Lab, he invented one of the first video games: “Tennis for Two.” It ran on an oscilloscope.

Image: Brookhaven

@paparatti
I really wonder at what meaning Hill is putting into "World war 3" here, there's not much explanation in the text and it's hard for me to see what criteria are being satisfied: Ukraine sees only two regular armies fighting, and doesn't even have both! Just one of them providing air support.

If these are enough to earn the label WW3 one wonders why the War on Terror didn't take that cake first
@joannekelly @clew@octodon.social

tobychev boosted

@aliide @Loukas @kevinrothrock What’s missing from the discussion about corruption generally is that Ukrainian journalists were reporting on it for ages before the administration did anything – the detail about eggs is one that I remember from last year – but most people didn’t see that until the US reporters picked up in it, and as Ukraine’s EU bid progressed. It did and does matter to the people whose loved ones were getting crap winter gear.

@aliide
Geopolitics has always been central to western interest in the war, you can ask the people of Myanmar or Tigray how well they have been served by their suffering being the only cause for western interest.
@kevinrothrock @kallekn

@PaulGrahamRaven
As far as I know PostNord stocks are owned only by the Swedish and Danish states, so I think this is more the case of a neoliberal project that didn't reach all the way to the "enrich the private capital lobby" and just sort of stalled in a weird transition phase.

tobychev boosted
tobychev boosted

@kevinrothrock It's a good article, and it has already been extensively discussed in Ukraine. Ukrainska Pravda has a complete translation, NV.ua has a summary. Some of the sources have been questioned, however, especially when it comes to "commanders refusing direct presidential orders". People in the know especially question the assertion that there would have been an order to "retake Horlivka".

@stevenjgibbons
Very cool, clearly you need to get out more to find more examples!

I once saw a slope by a road where a few bits of gravel launched from the passing cars had hit the slope in such a way they picked up snow and had formed disks standing on their edge after rolling some distance down the slope!

Sadly my phone did not have a camera at the time...

@franco_vazza
I'm confused, are you saying optical telescopes observe the CMB? Or do you mean things like COBE and Plank when you say ~ m**2 areas?

@briankoberlein
Do they explain how they know the jet precession follows the motion of the BH rotation axis?

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