Developmental genetics Updated +Created
How genes form bodies.
Video 1.
Developmental Genetics 1 by Joseph Ross (2020)
Source. Talks about homeobox genes.
Differentiable manifold Updated +Created
TODO find a concrete numerical example of doing calculus on a differentiable manifold and visualizing it. Likely start with a boring circle. That would be sweet...
Hive mind Updated +Created
SMIC Updated +Created
Video 1.
SMIC, Explained by Asianometry (2021)
Source.
Suwu herding sheep Updated +Created
www.ibiblio.org/chinese-music/html/traditional.html contains an amazing orchestral version for di flute TODO identify! When attempting to upload to YouTube, it identifies as "Su Wu Tending the Sheep" and give a name "Chen Tao", but no further information. Chen Tao is presumably this dude: www.barduschinamusic.org/chen-tao-dizi | www.melodyofdragon.org/chentao.html 陈涛
baike.baidu.com/item/苏武牧羊/5532#11_2 mentions that it comes from an erhu concerto composed by Peng Xiuwen
The sadness of the erhu perfectly fits the role and mood of the story! Brilliant!
Video 1.
Suwu herding sheep played by Song Fei (2017)
Source.
Sycamore processor Updated +Created
This is a good read: quantumai.google/hardware/datasheet/weber.pdf May 14, 2021. Their topology is so weird, not just a rectangle, one wonders why! You get different error rates in different qubits, it's mad.
Figure 1.
Google Sycamore Weber quantum computer connectivity graph
. Weber is a specific processor of the Sycamore family. From this we see it clearly that qubits are connected to at most 4 other qubits, and that the full topology is not just a simple rectangle.
Sylvester's law of inertia Updated +Created
The theorem states that the number of 0, 1 and -1 in the metric signature is the same for two symmetric matrices that are congruent matrices.
For example, consider:
The eigenvalues of are and , and the associated eigenvectors are:
symPy code:
A = Matrix([[2, sqrt(2)], [sqrt(2), 3]])
A.eigenvects()
and from the eigendecomposition of a real symmetric matrix we know that:
Now, instead of , we could use , where is an arbitrary diagonal matrix of type:
With this, would reach a new matrix :
Therefore, with this congruence, we are able to multiply the eigenvalues of by any positive number and . Since we are multiplying by two arbitrary positive numbers, we cannot change the signs of the original eigenvalues, and so the metric signature is maintained, but respecting that any value can be reached.
Note that the matrix congruence relation looks a bit like the eigendecomposition of a matrix:
but note that does not have to contain eigenvalues, unlike the eigendecomposition of a matrix. This is because here is not fixed to having eigenvectors in its columns.
But because the matrix is symmetric however, we could always choose to actually diagonalize as mentioned at eigendecomposition of a real symmetric matrix. Therefore, the metric signature can be seen directly from eigenvalues.
Also, because is a diagonal matrix, and thus symmetric, it must be that:
What this does represent, is a general change of basis that maintains the matrix a symmetric matrix.
Symmetric bilinear map Updated +Created
Subcase of symmetric multilinear map:
Requires the two inputs and to be in the same vector space of course.
The most important example is the dot product, which is also a positive definite symmetric bilinear form.
Dirac Lagrangian Updated +Created
where:
Remember that is a 4-vetor, gamma matrices are 4x4 matrices, so the whole thing comes down to a dot product of two 4-vectors, with a modified by matrix multiplication/derivatives, and the result is a scalar, as expected for a Lagrangian.
Like any other Lagrangian, you can then recover the Dirac equation, which is the corresponding equations of motion, by applying the Euler-Lagrange equation to the Lagrangian.
TSMC Updated +Created
One of the companies that has fabs, which buys machines from companies such as ASML and puts them together in so called "silicon fabs" to make the chips
As the quintessential fabless fab, there is on thing TSMC can never ever do: sell their own design! It must forever remain a fab-only company, that will never compete with its customers. This is highlighted e.g. at youtu.be/TRZqE6H-dww?t=936 from Video "How Nvidia Won Graphics Cards by Asianometry (2021)".
Video 1.
How Taiwan Created TSMC by Asianometry (2020)
Source. Some points:
  • UCM failed because it focused too much on the internal market, and was shielded from external competition, so it didn't become world leading
  • one of TSMC's great advances was the fabless business model approach.
  • they managed to do large technology transfers from the West to kickstart things off
  • one of their main victories was investing early in CMOS, before it became huge, and winning that market
Erdős' conjecture on powers of 2 Updated +Created
Described at: arxiv.org/pdf/2107.12475.pdf where a relation to the Busy beaver scale is proven, and the intuitive relation to the Collatz conjecture described. Perhaps more directly: demonstrations.wolfram.com/CollatzSequenceComputedByATuringMachine/
The Bibites Updated +Created
Unknown real developer name, claims to be from Canada on YouTube channel about: www.youtube.com/@TheBibitesDigitalLife/about, likely because he's a software developer and wants to keep his employer's claws away from his side project.
Appears to be closed source unfortunately, so not suitable for research.
Video 1. "What will happen after 100h of evolution? by The Bibites (2022)" mentions it was started five years ago, so circa 2017.
Appears to be Unity-based, if you download and extract for Linux you get files named UnityPlayer.so.
Was not very Linux compatible: www.reddit.com/r/TheBibites/comments/vqk6ac/program_stalls_at_a_blue_screen/ Trying to run 0.5.0 leads to a blank screen after you click "start simulation".
Video 1.
What will happen after 100h of evolution? by The Bibites (2022)
Source.
Discretization Updated +Created
Division algebra Updated +Created
DNA amplification Updated +Created
DNA amplification is one of the key DNA technologies:
DNA methylation Updated +Created
The first found and most important known epigenetic marker.
Happens only on adenine and cytosine. Adenine methylation is much less common in mammal than cytosine methylation, when people say "methylation" they often mean just cytosine methylation.
It often happens on promoters, where it inhibits transcription.
SQL REPEATABLE READ isolation level Updated +Created
nodejs/sequelize/raw/parallel_create_delete_empty_tag.js is an example which experimentally seems to be solved by REAPEATABLE READ, although we are not sure that this is truly the case and why. What is clear is that that example is not solved by the SQL READ COMMITTED isolation level.
In PostgreSQL, this is the first isolation level which can lead to postgreSQL serialization failures, this does not happen to SQL READ COMMITTED isolation level in that DBMS. You then have to retry the transaction.

Unlisted articles are being shown, click here to show only listed articles.