Ciro Santilli @cirosantilli 37

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Eukaryotic ribosome Updated 2025-07-16

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Gaupol Updated 2025-07-16

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github.com/otsaloma/gaupol

Good shortcuts and user experience.

No waveform viewer: github.com/otsaloma/gaupol/issues/49 so unusable.

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Mass renormalization Updated 2025-07-16

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Modular trapped ion quantum computer Updated 2025-07-16

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Trapped ion people acknowledge that they can't put a million qubits in on chip (TODO why) so they are already thinking of ways to entangle separate chips. Thinking is maybe the key word here. One of the propoesd approaches inolves optical links. Universal Quantum for example explicitly rejects that idea in favor of electric field link modularity.

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Oak Ridge supercomputer Updated 2025-07-16

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Orbital approximation Updated 2025-07-16

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Just ignore the electron electron interactions.

Bibliography:

chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Book%3A_Quantum_States_of_Atoms_and_Molecules_(Zielinksi_et_al)/10%3A_Theories_of_Electronic_Molecular_Structure/10.02%3A_The_Orbital_Approximation_and_Orbital_Configurations

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Raspberry Pi 1 Updated 2025-07-16

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Saint Peter Updated 2025-07-16

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Brother of andrew the Apostle, called by Jesus in fishers of men. Born Simon, but Jesus renamed him to Peter, thus the weird "Simon called Peter" way he is referred to as in some versions of the Bible.

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Sandy Lerner nude photo Updated 2025-07-16

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She posed naked on horseback for Forbes to promote animal rights in 1997.

A ultra low resolution reproduction of the image can be found at: rohitnair.wordpress.com/2011/12/13/cisco-history-cisco-systems-history-and-trivia-brand-history-and-trivia/

She's kind of lying on top of the horse's back, and you can't see much, just some tastefully light erotica. It's not like she's fucking the horse or anything.

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Sequoia Capital Updated 2025-07-16

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Video 1.

Target Big Markets by Don Valentine (2010)

Source.

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Term symbols for carbon ground state Updated 2025-07-16

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This example covered for example at Video 1. "Term Symbols Example 1 by TMP Chem (2015)".

Carbon has electronic structure 1s2 2s2 2p2.

For term symbols we only care about unfilled layers, because in every filled layer the total z angular momentum is 0, as one electron necessarily cancels out each other:

magnetic quantum number varies from -l to +l, each with z angular momentum $- l ℏ$ to $+ l ℏ$ and so each cancels the other out
spin quantum number is either + or minus half, and so each pair of electron cancels the other out

So in this case, we only care about the 2 electrons in 2p2. Let's list out all possible ways in which the 2p2 electrons can be.

There are 3 p orbitals, with three different magnetic quantum numbers, each representing a different possible z quantum angular momentum.

We are going to distribute 2 electrons with 2 different spins across them. All the possible distributions that don't violate the Pauli exclusion principle are:

m_l  +1  0 -1  m_L  m_S
     u_ u_ __    1    1
     u_ __ u_    0    1
     __ u_ u_   -1    1
     d_ d_ __    1   -1
     d_ __ d_    0   -1
     __ d_ d_   -1   -1
     u_ d_ __    1    0
     d_ u_ __    1    0
     u_ __ d_    0    0
     d_ __ u_    0    0
     __ u_ d_   -1    0
     __ d_ u_   -1    0
     ud __ __    2    0
     __ ud __    0    0
     __ __ ud   -2    0

where:

m_l is $m_{l}$ , the magnetic quantum number of each electron. Remember that this gives a orbital (non-spin) quantum angular momentum of $m_{l} ℏ$ to each such electron
m_L with a capital L is the sum of the $m_{l}$ of each electron
m_S with a capital S is the sum of the spin angular momentum of each electron

For example, on the first line:

m_l  +1  0 -1  m_L  m_S
     u_ u_ __    1    1

we have:

one electron with $m_{l} = + 1$ , and so angular momentum $ℏ$
one electron with $m_{l} = + 0$ , and so angular momentum 0

and so the sum of them has angular momentum

0 + 1ℏ = 1ℏ

. So the value of

m_{L}

is 1, we just omit the

ℏ

TODO now I don't understand the logic behind the next steps... I understand how to mechanically do them, but what do they mean? Can you determine the term symbol for individual microstates at all? Or do you have to group them to get the answer? Since there are multiple choices in some steps, it appears that you can't assign a specific term symbol to an individual microstate. And it has something to do with the Slater determinant. The previous lecture mentions it: www.youtube.com/watch?v=7_8n1TS-8Y0 more precisely youtu.be/7_8n1TS-8Y0?t=2268 about carbon.

youtu.be/DAgEmLWpYjs?t=2675 mentions that

^{3} D

is not allowed because it would imply

L = 2, S = 1

, which would be a state uu __ __ which violates the Pauli exclusion principle, and so was not listed on our list of 15 states.

He then goes for

^{1} D

and mentions:

S = 1 so $m_{S}$ can only be 0
L = 2 (D) so $m_{L}$ ranges in -2, -1, 0, 1, 2

and so that corresponds to states on our list:

ud __ __    2    0
u_ d_ __    1    0
u_ __ d_    0    0
__ u_ d_   -1    0
__ __ ud   -2    0

Note that for some we had a two choices, so we just pick any one of them and tick them off off from the table, which now looks like:

 +1  0 -1  m_L  m_S
 u_ u_ __    1    1
 u_ __ u_    0    1
 __ u_ u_   -1    1
 d_ d_ __    1   -1
 d_ __ d_    0   -1
 __ d_ d_   -1   -1
 d_ u_ __    1    0
 d_ __ u_    0    0
 __ d_ u_   -1    0
 __ ud __    0    0

Then for

^{3} P

the choices are:

S = 2 so $m_{S}$ is either -1, 0 or 1
L = 1 (P) so $m_{L}$ ranges in -1, 0, 1

so we have 9 possibilities for both together. We again verify that 9 such states are left matching those criteria, and tick them off, and so on.

For the

m_{S}

, we have two electrons with spin up. The angular momentum of each electron is

1/2ℏ

, and so given that we have two, the total is

1ℏ

, so again we omit

ℏ

and

m_{S}

is 1.

Video 1.

Term Symbols Example 1 by TMP Chem (2015)

Source. Carbon atom.

Bibliography:

youtu.be/DAgEmLWpYjs?t=1962 from Video "Atomic Term Symbols by T. Daniel Crawford (2016)"

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Exchange-traded fund Updated 2025-07-16

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nodejs/sequelize/raw/parallel_update_async.js Updated 2025-07-16

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../../../nodejs/sequelize/raw/parallel_update_worker_threads.js contains a base example that can be used to test what can happen when queries are being run in parallel. But it is broken due to a sqlite3 Node.js package bug: github.com/mapbox/node-sqlite3/issues/1381...

../../../nodejs/sequelize/raw/parallel_update_async.js is an async version of it. It should be just parallel enough to allow observing the same effects.

This is an example of a transaction where the SQL READ COMMITTED isolation level if sufficient.

These examples run queries of type:

UPDATE "MyInt" SET i = i + 1

Sample execution:

node --unhandled-rejections=strict ./parallel_update_async.js p 10 100

which does:

PostgreSQL, see other databases options at SQL example
10 threads
100 increments on each thread

The fear then is that of a classic read-modify-write failure.

But as www.postgresql.org/docs/14/transaction-iso.html page makes very clear, including with an explicit example of type UPDATE accounts SET balance = balance + 100.00 WHERE acctnum = 12345;, that the default isolation level, SQL READ COMMITTED isolation level, already prevents any problems with this, as the update always re-reads selected rows in case they were previously modified.

If the first updater commits, the second updater will ignore the row if the first updater deleted it, otherwise it will attempt to apply its operation to the updated version of the row

Since in PostgreSQL "Read uncommitted" appears to be effectively the same as "Read committed", we won't be able to observe any failures on that database system for this example.

nodejs/sequelize/raw/parallel_create_delete_empty_tag.js contains an example where things can actually blow up in read committed.

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Initial public offering Updated 2025-07-16

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Isomorphic JavaScript Updated 2025-07-16

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Prokaryotic ribosome Updated 2025-07-16

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Romantic Warrior by Return to Forever (1976) Updated 2025-07-16

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Special unitary of degree 2 Updated 2025-07-16

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