This is quite in-depth, pretty good.
Unrelated to the Khan Academy.
It is hard to say if this channel is good because of the awesome information, or if because of the absolute cutness of that British presenter. Maybe it is both.
Experimental verification of the Maxwell-Boltzmann distribution Updated 2024-12-23 +Created 1970-01-01
Most applications of the Maxwell-Boltzmann distribution confirm the theory, but don't give a very direct proof of its curve.
Here we will try to gather some that do.
Like everything else in Lie group theory, you should first look at the matrix version of this operation: the matrix exponential.
The exponential map links small transformations around the origin (infinitely small) back to larger finite transformations, and small transformations around the origin are something we can deal with a Lie algebra, so this map links the two worlds.
The idea is that we can decompose a finite transformation into infinitely arbitrarily small around the origin, and proceed just like the product definition of the exponential function.
The definition of the exponential map is simply the same as that of the regular exponential function as given at Taylor expansion definition of the exponential function, except that the argument can now be an operator instead of just a number.
en.wikipedia.org/wiki/Logarithm_of_a_matrix#Existence mentions it always exists for all invertible complex matrices. But the real condition is more complicated. Notable counter example: -1 cannot be reached by any real .
The Lie algebra exponential covering problem can be seen as a generalized version of this problem, because
- Lie algebra of is just the entire
- we can immediately exclude non-invertible matrices from being the result of the exponential, because has inverse , so we already know that non-invertible matrices are not reachable
In special relativity, it is impossible to travel faster than light.
One argument of why, is that if you could travel faster than light, then you could send a message to a point in Spacetime that is spacelike-separated from the present. But then since the target is spacelike separated, there exists a inertial frame of reference in which that event happens before the present, which would be hard to make sense of.
Even worse, it would be possible to travel back in time:
Does not require entangled particles, unlike E91 which does.
en.wikipedia.org/w/index.php?title=Quantum_key_distribution&oldid=1079513227#BB84_protocol:_Charles_H._Bennett_and_Gilles_Brassard_(1984) explains it well. Basically:
- Alice and Bob randomly select a measurement basis of either 90 degrees and 45 degrees for each photon
- Alice measures each photon. There are two possible results to either measurement basis: parallel or perpendicular, representing values 0 or 1. TODO understand better: weren't the possible results supposed to be pass or non-pass? She writes down the results, and sends the (now collapsed) photons forward to Bob.
- Bob measures the photons and writes down the results
- Alice and Bob communicate to one another their randomly chosen measurement bases over the unencrypted classic channel.This channel must be authenticated to prevent man-in-the-middle. The only way to do this authentication that makes sense is to use a pre-shared key to create message authentication codes. Using public-key cryptography for a digital signature would be pointless, since the only advantage of QKD is to avoid using public-key cryptography in the first place.
- they drop all photons for which they picked different basis. The measurements of those which were in the same basis are the key. Because they are in the same basis, their results must always be the same in an ideal system.
- if there is an eavesdropper on the line, the results of measurements on the same basis can differ.Unfortunately, this can also happen due to imperfections in the system.Alice and Bob must decide what level of error is above the system's imperfections and implies that an attacker is listening.
Used e.g. in the Sycamore processor.
The most basic type of transmon is in Ciro's ASCII art circuit diagram notation, an LC circuit e.g. as mentioned at youtu.be/cb_f9KpYipk?t=180 from Video "The transmon qubit by Leo Di Carlo (2018)":
+----------+
| Island 1 |
+----------+
| |
X C
| |
+----------+
| Island 2 |
+----------+youtu.be/eZJjQGu85Ps?t=2443 from Video "Superconducting Qubits I Part 1 by Zlatko Minev (2020)" describes a (possibly simplified) physical model of it, as two superconducting metal islands linked up by a Josephson junction marked as The circuit is then analogous to a LC circuit, with the islands being the capacitor. The Josephson junction functions as a non-linear inductor.
X in the diagram as per-Ciro's ASCII art circuit diagram notation:+-------+ +-------+
| | | |
| Q_1() |---X---| Q_2() |
| | | |
+-------+ +-------+Others define it with a SQUID device instead: youtu.be/cb_f9KpYipk?t=328 from Video "The transmon qubit by Leo Di Carlo (2018)". He mentions that this allows tuning the inductive element without creating a new device.
The superconducting transmon qubit as a microwave resonator by Daniel Sank (2021)
Source. GitHub is for newbs.
- 50002f38a40aeca96f7d03ceac1c62fc233b44207af99df8f1daddf03f6ef61c via cryptograffiti.info contains a Python script that starts with:
#!/usr/bin/env python3 # # This file is placed in the public domain. # # CryptoGraffiti tool # # Requires python-bitcoinlib-v0.2.1 # # https://github.com/petertodd/python-bitcoinlib # # pip install python-bitcoinlib - 209c9106c7261582f5d0907819c6e10dea670c273133047d911be41f8a42d86f via cryptograffiti.info contains a Base64 encoded Python script starting in:Some related ones:
#!/usr/bin/env python # brainwallet "base58" # v2015-05-18, fixed Tor DNS problem import binascii import hashlib- 25658f625c8f3964593b9e3c632040cb69aea9cf24403af33ab173d7cba7c42f
- 7d188bd499137b5a0d68271ef8a4f3c4dc2f2b38bd03dfc913cb2b0be15b1e0d
- medium.com/@chain.info1/the-mystery-behind-satoshi-tribute-donations-cf4ce28c56a1 The Mystery Behind "Satoshi Tribute" Donations by Chain.Info (2020)
Because Ciro's a software engineer, and he's done enough staring in computers for a lifetime already, and he believes in the power of Git, he didn't pay much attention to this part ;-)
According to the eLife paper, the code appears to have been uploaded to: github.com/d-j-k/puntseq. TODO at least mention the key algorithms used more precisely.
Ciro can however see that it does present interesting problems!
Because it was necessary to wait for 2 days to get our data, the workshop first reused sample data from previous collections done earlier in the year to illustrate the software.
First there is some signal processing/machine learning required to do the base calling, which is not trivial in the Oxford Nanopore, since neighbouring bases can affect the signal of each other. This is mostly handled by Oxford Nanopore itself, or by hardcore programmers in the field however.
After the base calling was done, the data was analyzed using computer programs that match the sequenced 16S sequences to a database of known sequenced species.
This is of course not just a simple direct string matching problem, since like any in experiment, the DNA reads have some errors, so the program has to find the best match even though it is not exact.
The PuntSeq team would later upload the data to well known open databases so that it will be preserved forever! When ready, a link to the data would be uploaded to: www.puntseq.co.uk/data
@cirosantilli/_file/nodejs/sequelize/raw/nodejs/sequelize/raw/parallel_select_and_update.js Updated 2024-12-23 +Created 1970-01-01
This example is similar to nodejs/sequelize/raw/parallel_update_async.js, but now we are doing a separate SELECT, later followed by an update:
SELECT FROMto get i- update on Js code
newI = i + 1 UPDATE SETthenewI
Although this specific example is useless in itself, as we could just use
UPDATE "MyInt" SET i = i + 1 as in nodejs/sequelize/raw/parallel_update_async.js, which automatically solves any concurrency issue, this kind of code could be required for example if the update was a complex function not suitably implemented in SQL, or if the update depends on some external data source.Sample execution:which does:
node --unhandled-rejections=strict ./parallel_select_and_update.js p 2 10 'READ COMMITTED'- PostgreSQL, see other databases options at SQL example
- 2 threads
- 10 increments on each thread
Another one:this will run SELECT FOR UPDATE rather than just SELECT
node --unhandled-rejections=strict ./parallel_select_and_update.js p 2 10 'READ COMMITTED' 'FOR UPDATE'Observed behaviour under different SQL transaction isolation levels:
READ COMMITTED: fails. Nothing in this case prevents:- thread 1: SELECT, obtains i = 0
- thread 2: SELECT, obtains i = 0
- thread 2: newI = 1
- thread 2: UPDATE i = 1
- thread 1: newI = 1
- thread 1: UPDATE i = 1
REPEATABLE READ: works. the manual mentions that if multiple concurrent updates would happen, only the first commit succeeds, and the following ones fail and rollback and retry, therefore preventing the loss of an update.READ COMMITTED+SELECT FOR UPDATE: works. And does not do rollbacks, which probably makes it faster. Withp 10 100,REPEATABLE READwas about 4.2s andREAD COMMITTED+SELECT FOR UPDATE3.2s on Lenovo ThinkPad P51 (2017).SELECT FOR UPDATEshould be enough as mentioned at: www.postgresql.org/docs/13/explicit-locking.html#LOCKING-ROWSFOR UPDATE causes the rows retrieved by the SELECT statement to be locked as though for update. This prevents them from being locked, modified or deleted by other transactions until the current transaction ends. That is, other transactions that attempt UPDATE, DELETE, SELECT FOR UPDATE, SELECT FOR NO KEY UPDATE, SELECT FOR SHARE or SELECT FOR KEY SHARE of these rows will be blocked until the current transaction ends; conversely, SELECT FOR UPDATE will wait for a concurrent transaction that has run any of those commands on the same row, and will then lock and return the updated row (or no row, if the row was deleted). Within a REPEATABLE READ or SERIALIZABLE transaction, however, an error will be thrown if a row to be locked has changed since the transaction started. For further discussion see Section 13.4.
A non-raw version of this example can be seen at: nodejs/sequelize/parallel_select_and_update.js.
Ciro Santilli supports full legalization of all drugs, because he feels that it would be better overall for the world to have cheaper drugs and more drug addicts, but way, way less organized crime.
These should be extremely controlled of course, with extremely high taxes that puts their price just below the current illegal market, and a complete ban on any positive advertising.
Ciro believes that maybe the government could even go as far as giving free drugs to drug addicts so they don't have to rob to get a fix.
This is notably considering that drug-led organized crime completely dominates and corrupts the politics of many production and trafficking zones, which are already generally poor fucked up places to start with:Ciro's experiences in Brazil such as mentioned at São Remo, the favela next to USP, although much less extreme than the above, also come to mind.
Drug traffic corrupts everything. It prevents development of honest people. It is a cancer, which we have failed time and time a gain to cure. The only cure is to accept the other less insidious of addiction.
Bibliography:
- How to Fix a Drug Scandal (2020) gives a good sense of the relentlessness of the drug war, and how it affects people who are already poor the most
Domain list only, no IPs and no dates. We haven't been able to extract anything of interest from this source so far.
Domain hit count when we were at 69 hits: only 9, some of which had been since reused. Likely their data collection did not cover the dates of interest.
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