This technique has managed to determine protein 3D structures for proteins that people were not able to crystallize for X-ray crystallography.

It is said however that cryoEM is even fiddlier than X-ray crystallography, so it is mostly attempted if crystallization attempts fail.

By looking at Figure 1. "A cryoEM image", you can easily understand the basics of cryoEM.

We just put a gazillion copies of our molecule of interest in a solution, and then image all of them in the frozen water.

Each one of them appears in the image in a random rotated view, so given enough of those point of view images, we can deduce the entire 3D structure of the molecule.

Ciro Santilli once watched a talk by Richard Henderson about cryoEM circa 2020, where he mentioned that he witnessed some students in the 1980's going to Germany, and coming into contact with early cryoEM. And when they came back, they just told their principal investigator: "I'm going to drop my PhD theme and focus exclusively on cryoEM". That's how hot the cryo thing was! So cool.

XPath kind of died with the rise of CSS selectors around the beginnning of the 2010's. But that is a shame. XPath is a good standard, and was generally more powerful than CSS selectors for many many years.

One of its main applications is to determine the 3D structure of proteins.

Sometimes you are not able to crystallize the proteins however, and the method cannot be used.

Crystallizing is not simple because:

Cryogenic electron microscopy can sometimes determine the structures of proteins that failed crystallization.

Often used as a synonym for X-ray crystallography, or to refer more specifically to the diffraction part of the experiment (exluding therefore sample preparation and data processing).

Base machinery of the nervous system.

Basically the same remarks as for university, just 10 times more useless, see also: Section "Motivation".

This actually happens in Winter. But they are so fucking euphemistic that winter has to be removed from the calendar.

This actually happens in spring. But because they are so euphemistic winter had to be removed from the calendar, it gets shifted a left.

Login walls. Lol.

Good Portuguese overview: www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-11172017000300301&lng=pt&tlng=pt

A fantastic sounding full time 4-year course that any student could transfer to called that teaches various natural science topics, notably mathematics, physics, chemistry and molecular biology.

Many past students Ciro talked to however share a common frustration with the course: in the first 2 years at least, the "basic cycle", you have infinitely many courses, and no time to study, and no choice of what to study, it is only in the latter 2 years (the advanced cycle) that you get the choices.

Also, if you get low grades in a single subject, your out. And exams are useless of course.

Here's a Quora question in Portuguese about the course: pt.quora.com/Como-funciona-o-tal-do-curso-secreto-da-USP, the only decent answer so far being: pt.quora.com/Como-funciona-o-tal-do-curso-secreto-da-USP/answer/Victor-Soares-31. Very disappointing to hear.

On the advanced cycle, you have a lot of academic freedom. You are basically supposed to pick a research project with an advisor and go for it, with a small amount of mandatory course hours. Ciro was told in 2022 that you can even have advisors from other universities or industry, and that it is perfectly feasible to take courses in another university and validate the course hours later on. Fantastic!!!

Students from the entire University of São Paulo can apply to transfer to it only after joining the university, with the guarantee that they can go back to their original courses if they don't adapt to the new course, which is great!

Not doing it is one of Ciro Santilli's regrets in life, see also: don't be a pussy.

Around 2007, they were in a really shady building of the University, but when Ciro checked in 2021, they had apparently moved to a shiny new entrepreneurship-focused building. Fantastic news!!!

This place has one of the best changes of spawning the first Brazilian Nobel Prize or unicorn.

One of the Brazilians who came to École Polytechnique together with Ciro was from this course. The fact that he is one of the most intelligent people Ciro knows gave further credit to that course in his eyes.

The fundamental intuition about capacitors is that they never let electrons through.

They can only absorb electrons up to a certain point, but then the pushback becomes too strong, and current stops.

Therefore, they cannot conduct direct current long term.

For alternating current however, things are different, because in alternating current, electrons are just jiggling back and forward a little bit around a center point. So you can send alternating current power across a capacitor.

The key equation that relates Voltage to electric current in the capacitor is:So if a voltage Heavyside step function is applied what happens is:More realistically, one may consider the behavior or the series RC circuit to see what happens without infinities when a capacitor is involved as in the step response of the series RC circuit.