Network switch Updated 2025-07-16
A switch is a box with a bunch of Ethernet wires coming into it:
+--------------------+
| +-+  +-+  +-+  +-+ |
| |1|  |2|  |3|  |4| |
| +-+  +-+  +-+  +-+ |
+--------------------+
Except that it doesn't have to be Ethernet, e.g. it would also be a Wi-Fi.
What the switch does is:
  • an Ethernet request came in from wire 1
  • decide which wire to send it out on, e.g. wire 2, 3, 4, 5, etc. You likely don't want to send it back through 1 where it came from.
After the destination is found, a confirmation is somehow sent back to the switch, which then learns which wire to send each MAC address to.
A switch is a bit like a router but it is a bit dumber/operates at a lower level: it basically operates only on MAC addresses, not on IP addresses.
The Internet service provider boxes most people have at home combines a switch for the local network and a router for the ISP communication.
Server (computing) Updated 2025-07-16
Video 1.
Unpacking 200 servers by Play with Junk (2021)
Source.
Video 2.
Visiting Hetzner in Falkenstein by der8auer (2022)
Source.
Neuron Updated 2025-07-16
Spinal cord Updated 2025-07-16
GenBank Updated 2025-07-16
FFmpeg Updated 2025-07-16
FFmpeg is the assembler of audio and video.
As a result, Ciro Santilli who likes "lower level stuff", has had many many hours if image manipulation fun with this software, see e.g.:
As older Ciro grows, the more he notices that FFmpeg can do basically any lower level audio video task. It is just an amazing piece of software, the immediate go-to for any low level operation.
FFmpeg was created by Fabrice Bellard, which Ciro deeply respects.
Resize a video: superuser.com/questions/624563/how-to-resize-a-video-to-make-it-smaller-with-ffmpeg:
ffmpeg -i input.avi -filter:v scale=720:-1 -c:a copy output.mkv
Unlike every other convention under the sun, the height in scale is the first number.
ImageMagick Updated 2025-07-16
Crop 20 pixels from the bottom of the image:
convert image.png -gravity East -chop 20x0 result.png
Developmental biology Updated 2025-07-16
Video 1.
Where is Anatomy Encoded in Living Systems? by Michael Levin (2022)
Source.
  • we are very far from full understanding. End game is a design system where you draw the body and it compiles the DNA for you.
  • some cool mentions of regeneration
The simplest multicellular species Updated 2025-07-16
One of the simplest known seems to be: en.wikipedia.org/wiki/Trichoplax
www.u-tokyo.ac.jp/focus/en/articles/a_00220.html "The simplest multicellular organism unveiled" from 2013 mentions Tetrabaena socialis.
Then of course: Caenorhabditis elegans is a relatively simple and widely studied model organism.
Video 1.
Nicole King (UC Berkeley, HHMI) 1: The origin of animal multicellularity by iBiology (2015)
Source.
Colony (biology) Updated 2025-07-16
It is hard to distinguish between colonies of unicellular organism and multicellular organism as there is a continuum between both depending on how well integrated they cells are.
Multicellularity is polyphyletic Updated 2025-07-16
From Wikipedia:
Multicellularity has evolved independently at least 25 times in eukaryotes
and:
Complex multicellular organisms evolved only in six eukaryotic groups: animals, symbiomycotan fungi, brown algae, red algae, green algae, and land plants.
Flow cytometry Updated 2025-07-16
Video 1.
Flow Cytometry Animation by StarCellBio (2015)
Source.
Staining Updated 2025-07-16

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