E. Coli whole cell simulation Updated 2025-07-16
Ethnic minorities in China Updated 2025-07-16
These minorities actually had different legal statuses, e.g. they were exempt from the One Child Policy.
Exif tag Updated 2025-07-16
Human essential amino acid Updated 2025-07-16
Number of elements of an elliptic curve over a finite field Updated 2025-07-16
AGI-complete Updated 2025-07-16
Gaussian function Updated 2025-07-16
Kibble balance Updated 2025-07-16
The Kibble balance is so precise and reproducible that it was responsible for the 2019 redefinition of the Kilogram.
NIST-4 Kibble balance
. Source. 
It relies rely on not one, but three macroscopic quantum mechanical effects:How cool is that! As usual, the advantage of those effects is that they are discrete, and have very fixed values that don't depend either:One downside of using some quantum mechanical effects is that you have to cool everything down to 5K. But that's OK, we've got liquid helium!
- atomic spectra: basis for the caesium standard which produces precise time and frequency
- Josephson effect: basis for the Josephson voltage standard, which produces precise voltage
- quantum Hall effect: basis for the quantum Hall effect, which produces precise electrical resistance
- on the physical dimensions of any apparatus (otherwise fabrication precision would be an issue)
- small variations of temperature, magnetic field and so on
The operating principle is something along:Then, based on all this, you can determine how much the object weights.
- generate a precise frequency with a signal generator, ultimately calibrated by the Caesium standard
- use that precise frequency to generate a precise voltage with a Josephson voltage standard
- convert that precise voltage into a precise electric current by using the quantum Hall effect, which produces a very precise electrical resistance
- use that precise current to generate a precise force on the object your weighing, pushing it against gravity
- then you precisely measure both:
- local gravity with a gravimeter
- the displacement acceleration of the object with a laser setup
- youtu.be/ZfNygYuuVAE?t=854: they don't actually use the Quantum Hall effect device during operation, they only use it to calibrate other non-quantum resistors
Once more unto the breach Updated 2025-07-16
On the Law of Distribution of Energy in the Normal Spectrum Updated 2025-07-16
The Planck's law paper.
Ain't Nobody Got Time For That Updated 2025-07-16
ffplay multiple input files Updated 2025-07-16
TODO possible? superuser.com/questions/559768/ffplay-how-to-play-together-separate-video-and-audio-files
For synthesized streams like but it does not seem to accept multiple fails with:
sine we can do it e.g.ffplay -autoexit -nodisp -f lavfi -i '
sine=frequency=500[a];
sine=frequency=1000[b];
[a][b]amerge, atrim=end=2
'-i for some reason. So is there a way to open a file from some filter? E.g.:ffplay -i tmp.wav -i tmp.mkv -filter_complex "[0:a]atrim=end=2[a];[1:v]trim=end=2[v]" -map '[a]' -map '[v]'Argument 'tmp.mkv' provided as input filename, but 'tmp.wav' was already specified. Fractional quantum Hall effect for Updated 2025-07-16
Fractional quantum Hall effect for Updated 2025-07-16
Matrix exponential Updated 2025-07-16
Is the solution to a system of linear ordinary differential equations, the exponential function is just a 1-dimensional subcase.
Note that more generally, the matrix exponential can be defined on any ring.
The matrix exponential is of particular interest in the study of Lie groups, because in the case of the Lie algebra of a matrix Lie group, it provides the correct exponential map.
Raga by time of the day Updated 2025-07-16
Robert Noyce: The Man Behind the Microchip by Leslie Berlin (2006) Updated 2025-07-16
Borrow from the Internet Archive for free: archive.org/details/manbehindmicroc000berl/page/n445/mode/2up
Algebraic equation Updated 2025-07-16
Algebraic number Updated 2025-07-16
China Central Television Updated 2025-07-16
There are unlisted articles, also show them or only show them.