RNA polymerase Updated 2025-07-16
Converts DNA to RNA.
Operon Updated 2025-07-16
Sequence of genes under a single promoter. For an example, see E. Coli K-12 MG1655 operon thrLABC.
A single operon may produce multiple different transcription units depending on certain conditions, see: operon vs transcription unit.
SendGrid Updated 2025-07-16
The first one Ciro Santilli managed to get working in 2022, and which has a free plan.
You can either verify your sending domain by adding 3 DNS records.
Saw the email on Gmail, but Microsoft Outlook did put it into junk though. Yahoo mail also worked fine.
100 emails a day is not insane, but it is forever and appropriate for a test, I'm happy with that.
Tor Browser Updated 2025-07-16
Onion service Updated 2025-07-16
This is a way to host a server that actually hide the IP of the server from the client, just like Tor hides the IP of the client from the server. Amazing tecnology!
This is why it enables hosting illegal things like the Silk Road: law enforcement is not able find where the server is hosted, and take it down or identify the owner.
Considering e.g. Newton's laws of motion, you take a system that is a function of time , e.g. the position of many point particles, and then you reverse the speeds of all particles, then is a solution to that.
Transversal time dilation Updated 2025-07-16
Light watch transverse to direction of motion. This case is interesting because it separates length contraction from time dilation completely.
Of course, as usual in special relativity, calling something "time dilation" leads us to mind boggling ideas of "symmetry breaking": if both frames have a light watch, how can both possibly observe the other to be time dilated?
And the answer to this, is the usual: in special relativity time and space are interwoven in a fucked up way, everything is just a spacetime event.
In this case, there are three spacetime events of interest: both clocks start at same position, your beam hits up at x=0, moving frame hits up at x>0.
Those two mentioned events are spacelike-separated events, and therefore even though they seem simultaneous to you, they are not going to be simultaneous to the moving observer!
If little clock one meter away from you tells you that at the time of some event (your light beam hit up) the moving light watch was only 50% up, this is just a number given by your one meter away watch!
By looking at this more general point of view, we could ask ourselves what happens to the group if instead of the dot product we took a more general bilinear form, e.g.:
The answers to those questions are given by the Sylvester's law of inertia at Section "All indefinite orthogonal groups of matrices of equal metric signature are isomorphic".

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