American nuclear weapons program Updated +Created
Nuclear weapon detonation Updated +Created
Double pendulum Updated +Created
Documentation generator Updated +Created
Nuclear magnetic resonance spectroscopy Updated +Created
Used to identify organic compounds.
Seems to be based on the effects that electrons around the nuclei (shielding electrons) have on the outcome of NMR.
So it is a bit unlike MRI where you are interested in the position of certain nuclei in space (of course, these being atoms, you can't see their positions in space).
Video 1.
What's Nuclear Magnetic Resonance by Bruker Corporation (2020)
Source. Good 3D animations showing the structure of the NMR machine. We understand that it is very bulky largely due to the cryogenic system. It then talks a bit about organic compound identification by talking about ethanol, i.e. this is NMR spectroscopy, but it is a bit too much to follow closely. Basically the electron configuration alters the nuclear response somehow, and allows identifying functional groups.
TempleOS Updated +Created
The OS that the Gods ordered be made.
One is reminded of Ulillillia, see also: www.youtube.com/watch?v=9-79yOZ13qg The Story of Ulillillia by Atrocity Guide (2019)
Video 1.
I like elephants and God likes elephants
. Source.
How to become a good programmer? Updated +Created
Or: how to learn X.
This pops up on Reddit every week.
The right question is: what is the most awesome project I can do to improve the world?
Then, once you decide to try one, if that involves programming, only then learn to program to achieve that goal. And don't stop learning what's needed until you either get the thing done, or decide that it is actually not a good idea, or not possible, or that there is something else more important to be done first.
But if doesn't involve programming, then don't learn to program, and learn whatever you actually need to reach that goal instead.
Having that goal is the only way to be motivated to do something.
This is the essence of backward design.
Systems biology Updated +Created
Studies biology from a more global point of view, if putting all little pieces of an organism make up the final biological function.
Derivative Updated +Created
The derivative of a function gives its slope at a point.
More precisely, it give sthe inclination of a tangent line that passes through that point.
Motorola Moto G6 Play (2018) Updated +Created
Circa 2020, a bowl fell on it from about 25 cm height and broke the screen. £159.99.
2023-10: unable to connect to Giffgaff. "Network unavailable". Same SIM works in other phones. So annoying. Update APN to match: www.giffgaff.com/help/articles/internet-apn-settings-guide. Went next to a tower and then got signal. So the receiver is much worse than the pixel one. Vibration appears to be broken.
Authy sync worked: 2023.
Analytic function Updated +Created
Fourier series Updated +Created
Approximates an original function by sines. If the function is "well behaved enough", the approximation is to arbitrary precision.
Fourier's original motivation, and a key application, is solving partial differential equations with the Fourier series.
The Fourier series behaves really nicely in , where it always exists and converges pointwise to the function: Carleson's theorem.
Video 1.
But what is a Fourier series? by 3Blue1Brown (2019)
Source. Amazing 2D visualization of the decomposition of complex functions.
Backpacks Updated +Created
2024-04: got two backpacks "for free" with the Lenovo reward points from buying the Lenovo ThinkPad P14s gen4 amd, not bad, that was already cheap and now I got some extra swag:
The sport backpack has a fatal flaw: no strap to hold laptop in place, wo it just tumbles back and forth as you walk.
Neither of them have very good padding below the laptop, but at least the Elite one has a slightly elevated inner bag which woudl likely help a lot in case of a drop.
Ciro Santilli's knowledge hoarding Updated +Created
Ciro Santilli is a collector at heart. But a collector of knowledge.
His uncle, which Ciro rassembles in many ways, was like that. But he collected physical objects such as wines and stamps. Or even worse, objects that were meant to be collected such Panini soccer sticker Albums! This Ciro looks down on.
With computers, knowledge takes no physical space and can be immediately shared with the hole world, and there is great beauty to that, as you can just keep collecting forever without filling up your house.
But of course, physical or not, all attachments futile.
Like other types collecting, once Ciro decides that "he must know everything about a given subject", he will keep coming back to that subject over and over. Not in a systematic way of course, since Ciro is a lazy bastard, but he will keep coming back for a very long time, and eventually become an expert at it.
This compulsive hoarding, together with Ciro Santilli's bad old event memory, are the fundamental reasons for OurBigBook.com.
Massive open online course Updated +Created
MOOCs are a bad idea. We don't want to simply map the pre-computer classroom to the Internet. The Internet allows, and requires, fundamentally new ways to do things. More like Stack Overflow/Wikipedia. More like OurBigBook.com.
SQL 2D histogram Updated +Created
Let's try it on SQLite 3.40.1, Ubuntu 23.04. Data setup:
sqlite3 tmp.sqlite 'create table t(x integer, y integer)'
sqlite3 tmp.sqlite <<EOF
insert into t values
  (0, 0),
  (1, 1),
  (2, 2),
  (3, 3),
  (4, 4),
  (5, 5),
  (6, 6),
  (7, 7),
  (8, 8),
  (9, 9),
  (10, 10),
  (11, 11),
  (12, 12),
  (13, 13),
  (14, 14),
  (15, 15),
  (16, 16),
  (17, 17),
  (18, 18),
  (19, 19),

  (2, 18)
EOF
sqlite3 tmp.sqlite 'create index txy on t(x, y)'
For a bin size of 5 ignoring empty ranges we can:
sqlite3 tmp.sqlite <<EOF
select
  floor(x/5)*5 as x,
  floor(y/5)*5 as y,
  count(*) as cnt
from t
group by 1, 2
order by 1, 2
EOF
which produces the desired:
0|0|5
0|15|1
5|5|5
10|10|5
15|15|5
And to consider empty ranges we can use SQL genenerate_series + as per stackoverflow.com/questions/72367652/populating-empty-bins-in-a-histogram-generated-using-sql:
sqlite3 tmp.sqlite <<EOF
select x, y, sum(cnt) from (
  select
      floor(x/5)*5 as x,
      floor(y/5)*5 as y,
      count(*) as cnt
    from t
    group by 1, 2
  union
  select *, 0 as cnt from generate_series(0, 15, 5) inner join (select * from generate_series(0, 15, 5))
)
group by x, y
EOF
which outputs the desired:
0|0|5
0|5|0
0|10|0
0|15|1
5|0|0
5|5|5
5|10|0
5|15|0
10|0|0
10|5|0
10|10|5
10|15|0
15|0|0
15|5|0
15|10|0
15|15|5
Let students learn by teaching Updated +Created
Tell students to:
  • make suggestions to the course material themselves, since you have used text and published your source.Review their suggestions, and accept the best ones.
  • answer the questions of other students on your online forum. Let them work instead of you.
Praise those that do this very highly, and give them better grades if you have that superpower.
This is part of a larger concept Ciro Santilli holds dear: don't just consume, but also produce.
Whatever you do, even if it is playing video games: if you manage to produce related content that will interest other people, and possibly allow you to get paid, it will much much fun to do that thing.
Self-adjoint operator Updated +Created
DokuWiki Updated +Created

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