Blaise Pascal (1972) Updated +Created
California Updated +Created
Cultured meat Updated +Created
This is something worth investigating!
Video 1.
Inside the Quest to Make Lab Grown Meat by WIRED (2018)
Source.
Interviews with a few startups in the area, most of the time with Eat Just.
youtu.be/QO9SS1NS6MM?t=217 taught Ciro Santilli something he really appreciated: uncanny valley.
Year 1 of the physics course of the University of Oxford Updated +Created
GroupNames Updated +Created
How to report Ubuntu crashes Updated +Created
Their crash system does not have an amazing user interface.
Tested on Ubuntu 21.10.
After something crashes, look under /var/crash for a crash file, which helps to determine which package to report under on Launchpad.
E.g. a file /var/crash/_usr_sbin_gdm3.0.crash makes you want to file the bug under gdm at: bugs.launchpad.net/ubuntu/+source/gdm/+filebug
Then, while reporting the bug, you want to give the developpers access to that .crash file. But you can't publicly upload it because it contains memory dumps and could contain secret information. The way to do it is to look at the ID under:
sudo cat /var/crash/_usr_sbin_gdm3.0.uploaded
Ubuntu's crash report system has already uploaded the .crash for you, so you just have to confirm it and give the ID on the ticket.
You can view a list of all your uploaded errors at:
xdg-open https://errors.ubuntu.com/user/$(sudo cat /var/lib/whoopsie/whoopsie-id)
and each of those contain a link to:
https://errors.ubuntu.com/oops/<.uloaded error id>
which you yourself cannot see.
Running:
sudo apport-unpack /var/crash/_usr_sbin_gdm3.0.crash /tmp/app
splits it up into a few files, but does not make any major improvements.
apport-retrace
sudo apt install apport-retrace
sudo chmod 666 /var/crash/_usr_sbin_gdm3.0.crash
apport-retrace -g /var/crash/_usr_sbin_gdm3.0.crash
opens GDB with the core dump. Debug symbols are supplied as separate packages, which is a really cool idea: so you should be able to download them after the crash to see symbols. askubuntu.com/questions/487222/how-to-install-debug-symbols-for-installed-packages mentions how to install them. Official docs at: wiki.ubuntu.com/DebuggingProgramCrash#Debug_Symbol_Packages
Tried:
echo "deb http://ddebs.ubuntu.com $(lsb_release -cs) main restricted universe multiverse" | sudo tee -a /etc/apt/sources.list.d/ddebs.list
echo -e "deb http://ddebs.ubuntu.com $(lsb_release -cs)-updates main restricted universe multiverse\ndeb http://ddebs.ubuntu.com $(lsb_release -cs)-proposed main restricted universe multiverse" | sudo tee -a /etc/apt/sources.list.d/ddebs.list
sudo apt install ubuntu-dbgsym-keyring
but then sudo apt update fails with:
E: The repository 'http://ddebs.ubuntu.com impish-security Release' does not have a Release file.
Mathieu group Updated +Created
Contains the first sporadic groups discovered by far: 11 and 12 in 1861, and 22, 23 and 24 in 1973. And therefore presumably the simplest! The next sporadic ones discovered were the Janko groups, only in 1965!
Each is a permutation group on elements. There isn't an obvious algorithmic relationship between and the actual group.
TODO initial motivation? Why did Mathieu care about k-transitive groups?
Their; k-transitive group properties seem to be the main characterization, according to Wikipedia:
Looking at the classification of k-transitive groups we see that the Mathieu groups are the only families of 4 and 5 transitive groups other than symmetric groups and alternating groups. 3-transitive is not as nice, so let's just say it is the stabilizer of and be done with it.
Video 1.
Mathieu group section of Why Do Sporadic Groups Exist? by Another Roof (2023)
Source. Only discusses Mathieu group but is very good at that.
Minnesota Updated +Created
Video 1.
How To Talk Minnesotan by PBS (1993)
Source.
Namecoin Updated +Created
AlphaZero Updated +Created
www.quora.com/Which-chess-engine-would-be-stronger-Alpha-Zero-or-Stockfish-12/answer/Felix-Zaslavskiy explains that it beat Stockfish 8. But then Stockfish was developed further and would start to beat it. We know this because although AlphaZero was closed source, they released the trained artificial neural network, so it was possible to replay AlphaZero at its particular stage of training.
Blockchain Updated +Created
Born rule Updated +Created
Boundary value problem Updated +Created
x86 Paging Tutorial / PAE and PSE page table schemes Updated +Created
If either PAE and PSE are active, different paging level schemes are used:
  • no PAE and no PSE: 10 | 10 | 12
  • no PAE and PSE: 10 | 22.
    22 is the offset within the 4Mb page, since 22 bits address 4Mb.
  • PAE and no PSE: 2 | 9 | 9 | 12
    The design reason why 9 is used twice instead of 10 is that now entries cannot fit anymore into 32 bits, which were all filled up by 20 address bits and 12 meaningful or reserved flag bits.
    The reason is that 20 bits are not enough anymore to represent the address of page tables: 24 bits are now needed because of the 4 extra wires added to the processor.
    Therefore, the designers decided to increase entry size to 64 bits, and to make them fit into a single page table it is necessary reduce the number of entries to 2^9 instead of 2^10.
    The starting 2 is a new Page level called Page Directory Pointer Table (PDPT), since it points to page directories and fill in the 32 bit linear address. PDPTs are also 64 bits wide.
    cr3 now points to PDPTs which must be on the fist four 4GB of memory and aligned on 32 bit multiples for addressing efficiency. This means that now cr3 has 27 significative bits instead of 20: 2^5 for the 32 multiples * 2^27 to complete the 2^32 of the first 4GB.
  • PAE and PSE: 2 | 9 | 21
    Designers decided to keep a 9 bit wide field to make it fit into a single page.
    This leaves 23 bits. Leaving 2 for the PDPT to keep things uniform with the PAE case without PSE leaves 21 for offset, meaning that pages are 2M wide instead of 4M.
1973 Nobel Prize in Physics Updated +Created
1987 Nobel Prize in Physics Updated +Created
This was so hot (no pun intended) and reproducible that the prize was awarded one year after discovery. Quite rare in those days already.
BookStack Updated +Created
Video 1.
10k GitHub Stars by BookStack (2022)
Source. Answering to an AMA unfortunately :-) But some OK small bits of information trickled through.
Boston Dynamics Updated +Created

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