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There is also the quite simple aspect that many restriction enzymes bind as dimers, and each half recognizes the sequence on the opposite strand resulting in a palindromic recognition site. There are thermodynamic aspects to it, too, in terms how the enzyme bends the strand but that has a bit more to do with how the enzymes bend the DNA while nicking (I am hazy on details though).

https://arstechnica.com/science/2020/05/the-ars-covid-19-vaccine-primer-100-plus-in-the-works-8-in-clinical-trials/

I may have to brush my knowledge about tRNA splicing, but could you elaborate what you mean by : I have been trying to find if SEN (TSEN in humans) tRNA splicing endonucleases actually cuts the opposite strand, but so far I have not found that they do: It definitely doesn't seem palindromic though. From quickly scanning these few articles it seems that for tRNA splicing there are two catalytic (TSEN2, TSEN34) subunits and two structural (TSEN15, TSEN 34). The last article (sci-hub link) shows this through mutating SEN (non-human version) 2 and 34 (see last picture). Please note that I have included the first article because it shows the structure of the complex quite nicely (I think), but that article is about specific mutations that cause pontocerebellar hypoplasia. Hope this is of interest/relevant to you! Articles (hopefully in order of the pictures): https://www.nature.com/articles/ng.204? http://www.genesilico.pl/rnapathwaysdb/Pathway/step/72/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4090602/ sci-hub.tw/10.1007/s00018-008-7393-y

Welcome, sorry I couldn't be of more help though. Is an interesting question. Don't know if the types that do select palindromes, whether they are simply nonspecific in terms of direction or if there a physical reason like you suggest.

Wiki mentions some types do act on non-palindromic sequences. https://en.wikipedia.org/wiki/Restriction_enzyme#Types

There is no difference between the mathematician's definition of 'compact' and the physicist's. Indeed this is explicitly stated at the beginning of your link. note the sentence which begins "the methods of compactification are various....." Here you are talking about compactifying a group. Nothing wrong with that , not all sets are groups though mathematically the meaning is the same. But mathematically 'compact' and 'compactification' is about sets. We like compact because it allows us to use general theorems like the Heine-Borel theorem as justification for the mathematics of our functions and operations on them eg calculus. We like compact surfaces and manifolds as they keep sets and their coverings under control. The same ideas are also used by Engineers, as this extract from "Introduction to Differential Geometry for Engineers by Doolin and Martin" shows. Note their comment about research papers!

How about we interpret it to mean that "we do not understand how this works or which country built it, but it is clear from the G-forces that it is an unmanned craft." Correct. So here is your choice. 1. It is something built by humans and is more advanced than what humans have previously built (we've seen humans build more advanced things millions of times), or... 2. it was built by aliens (we've seen aliens build exactly zero things, and in fact have no evidence of alien life anywhere in the universe.) "Common sense" does not tell you that option two is the simplest explanation.