Microwave oven by Ciro Santilli 34 Updated +Created
Video 1.
How Microwaves Work by National MagLab (2017)
Source. A bit meh. Does not mention the word cavity magnetron!
Video 2.
How a Microwave Oven Works by EngineerGuy
. Source. Cool demonstration of the standing waves in the cavity with cheese!
Neon lamp by Ciro Santilli 34 Updated +Created
DT_FLAGS_1 by Ciro Santilli 34 Updated +Created
Seems to be a GNU Binutils extension
Young's interference experiment by Ciro Santilli 34 Updated +Created
List of continents by Ciro Santilli 34 Updated +Created
Wightman axioms by Ciro Santilli 34 Updated +Created
Transmon by Ciro Santilli 34 Updated +Created
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 X in the diagram as per-Ciro's ASCII art circuit diagram notation:
+-------+       +-------+
|       |       |       |
| Q_1() |---X---| Q_2() |
|       |       |       |
+-------+       +-------+
The circuit is then analogous to a LC circuit, with the islands being the capacitor. The Josephson junction functions as a non-linear inductor.
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.
Video 1.
The superconducting transmon qubit as a microwave resonator by Daniel Sank (2021)
Source.
Video 2.
Calibration of Transmon Superconducting Qubits by Stefan Titus (2021)
Source. Possibly this Keysight which would make sense.
SQL REPEATABLE READ isolation level by Ciro Santilli 34 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.
SELECT FOR UPDATE by Ciro Santilli 34 Updated +Created
An example where SELECT FOR UPDATE is a good solution to an use case can be seen at: nodejs/sequelize/raw/parallel_select_and_update.js.
Microwave by Ciro Santilli 34 Updated +Created
Micro means "small wavelength compared to radio waves", not micron-sized.
Microwave production and detection is incredibly important in many modern applications:
Cambridge Quantum Computing by Ciro Santilli 34 Updated +Created
In 2015, they got a 50 million investment from Grupo Arcano, led by Alberto Chang-Rajii, who is a really shady character who fled from justice for 2 years:Merged into Quantinuum later on in 2021.
Pro of superconducting qubits by Ciro Santilli 34 Updated +Created
Create a test user in PostgreSQL by Ciro Santilli 34 Updated +Created
In order to create a test user with password instead of peer authentication, let's create test user:
createuser -P user0
createdb user0
-P makes it prompt for the users password.
Alternatively, to create the password non-interactively stackoverflow.com/questions/42419559/postgres-createuser-with-password-from-terminal:
psql -c "create role NewRole with login password 'secret'"
Can't find a way using the createuser helper.
We can then login with that password with:
psql -U user0 -h localhost
which asks for the password we've just set, because the -h option turns off peer authentication, and turns off password authentication.
The password can be given non-interactively as shown at stackoverflow.com/questions/6405127/how-do-i-specify-a-password-to-psql-non-interactively with the PGPASSWORD environment variable:
PGPASSWORD=a psql -U user0 -h localhost
Now let's create a test database which user0 can access with an existing superuser account:
createdb user0db0
psql -c 'GRANT ALL PRIVILEGES ON DATABASE user0db0 TO user0'
We can check this permission with:
psql -c '\l'
which now contains:
                                  List of databases
   Name    |  Owner   | Encoding |   Collate   |    Ctype    |   Access privileges
-----------+----------+----------+-------------+-------------+-----------------------
 user0db0  | ciro     | UTF8     | en_GB.UTF-8 | en_GB.UTF-8 | =Tc/ciro             +
           |          |          |             |             | ciro=CTc/ciro        +
           |          |          |             |             | user0=CTc/ciro
The permission letters are explained at:
user0 can now do the usual table operations on that table:
PGPASSWORD=a psql -U user0 -h localhost user0db0 -c 'CREATE TABLE table0 (int0 INT, char0 CHAR(16));'
PGPASSWORD=a psql -U user0 -h localhost user0db0 -c "INSERT INTO table0 (int0, char0) VALUES (2, 'two'), (3, 'three'), (5, 'five'), (7, 'seven');"
PGPASSWORD=a psql -U user0 -h localhost user0db0 -c 'SELECT * FROM table0;'

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