Nota bene Updated +Created
Agarose gel electrophoresis Updated +Created
OpenShot Updated +Created
Ubuntu 20.10 crash...:
  exceptions:ERROR Unhandled Exception
Traceback (most recent call last):
  File "/usr/bin/openshot-qt", line 11, in <module>
    load_entry_point('openshot-qt==2.5.1', 'gui_scripts', 'openshot-qt')()
  File "/usr/lib/python3/dist-packages/openshot_qt/launch.py", line 97, in main
    app = OpenShotApp(argv)
  File "/usr/lib/python3/dist-packages/openshot_qt/classes/app.py", line 218, in __init__
    from windows.main_window import MainWindow
  File "/usr/lib/python3/dist-packages/openshot_qt/windows/main_window.py", line 45, in <module>
    from windows.views.timeline_webview import TimelineWebView
  File "/usr/lib/python3/dist-packages/openshot_qt/windows/views/timeline_webview.py", line 42, in <module>
    from PyQt5.QtWebKitWidgets import QWebView
ImportError: /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5: undefined symbol: _ZN4QRhi10newSamplerEN11QRhiSampler6FilterES1_S1_NS0_11AddressModeES2_, version Qt_5_PRIVATE_API
vmpk Updated +Created
VMPK is a virtual device that replicates what you would get by connecting a physical MIDI keyboard to your computer. It is not a software synthesizer on its own. But it does connect to a working synthesizer by default (Sonivox EAS) which makes it produce sounds out-of-the box.
TODO: then I messed with my sound settings, and then it stopped working by default on the default "MIDI Connection" > "MIDI Out Driver" > "Network". But it still works on "SonivoxEAS".
A hello world of actually connecting it to a specific software synthesizer manually on Advanced Linux Sound Architecture with aconnect can be found at: askubuntu.com/questions/34391/virtual-midi-piano-keyboard-setup/1298026#1298026
Reasonable default key mappings to keyboard covering 2 octaves.
3 multiple simultaneous keys did not work (tested "ZQI"). This might just be a limitation of my keyboard however.
Quantum control systems use FPGAs Updated +Created
It seems that all/almost all of them do. Quite cool.
Video 1.
FPGA Architecture of the Quantum Control System by Keysight (2022)
Source. They actually have a dedicated quantum team! Cool.
Video 2.
FPGA based servo system by Atoms & Laser (2018)
Source. The Indian lady is hardcore.
Quantum threshold theorem Updated +Created
This theorem roughly states that states that for every quantum algorithm, once we reach a certain level of physical error rate small enough (where small enough is algorithm dependant), then we can perfectly error correct.
This algorithm provides the conceptual division between noisy intermediate-scale quantum era and post-NISQ.
Radio receiver Updated +Created
As well put by Wikipedia, a radio receiver has to perform three functions on the signal from the antenna:
  • filtering, so you can tune the station you care about. This filters based on the frequency of the carrier wave you want. I.e. you use a bandpass filter.
  • amplification: otherwise you won't be able to hear anything if the emitter is too far away
  • demodulation: this means decoding the signal based on whatever way it was encoded, notably e.g. AM/FM
A First, a Blue, and a spouse Updated +Created
It is said that you leave Oxford with either
Age of the universe Updated +Created
Surely You're Joking, Mr. Feynman chapter An Offer You Must Refuse (a play on words on The Godfather (1972)) has an interesting historical mention from the early 1950s while at Caltech:
The next day, I had the greatest luck in making a decision. God must have set it up to help me decide. I was walking to my office, and a guy came running up to me and said, "Hey, Feynman! Did you hear what happened? Baade found that there are two different populations of stars! All the measurements we had been making of the distances to the galaxies had been based on Cephid variables of one type, but there's another type, so the universe is twice, or three, or even four times as old as we thought!"
I knew the problem. In those days, the earth appeared to be older than the universe. The earth was four and a half billion, and the universe was only a couple, or three billion years old. It was a great puzzle. And this discovery resolved all that: The universe was now demonstrably older than was previously thought. And I got this information right away - the guy came running up to me to tell me all this.
Aggressively filter your social media follows Updated +Created
Ciro Santilli very aggressively aggressively people in social media.
There are basically 3 categories:
  • are you Ciro's parents or children or brothers: OK, keep following, unless you are truly truly very noise.
  • does Ciro really really like or respect you? OK, he can take some useless (i.e. non-technical/scientific) posts
  • otherwise: one bad post and unfollow
OAuth Updated +Created
The fatal flaw of OAuth is that websites have to enable specific providers, they can't just automatically select the correct OAuth for a given email domain. This means that the vast majority of websites will only provide the most widely popular providers such as Google, and the like, which means people won't have decent privacy.
So you are just better off with password logins and a decent password manager.
Number of elements of an elliptic curve over a finite field Updated +Created
How to mine Monero Updated +Created
Ubuntu 20.10 as per xmrig.com/docs/miner/build/ubuntu:
sudo apt install git build-essential cmake libuv1-dev libssl-dev libhwloc-dev
git clone https://github.com/xmrig/xmrig.git
mkdir xmrig/build && cd xmrig/build
cmake ..
make -j$(nproc)
At minexmr.com/#getting_started we see that all you then need is a single CLI command:
xmrig -o pool.minexmr.com:4444 -u <your-monero-address>
Seems simple, well done devs!
Benchmark on Lenovo ThinkPad P51 (2017) as per xmrig.com/docs/miner/benchmark:
./xmrig --bench=1M
gives:
948.1 h/s
which according to the minexmr.com mining pool would generate 0.0005 XMR/day, which at the February 2021 rate of 140 USD/XMR is 0.07 USD/day. The minimum payout in that pool is 0.004 XMR so it would take 8 days to reach that.
So clearly, application-specific integrated circuit mining is the only viable way of doing this.
www.makeuseof.com/cryptos-you-can-mine-at-home/ is a completely full of bullshit article that says otherwise. How can someone publish that!
NP (complexity) Updated +Created
AGI-complete Updated +Created
Term invented by Ciro Santilli to refer to problems that can only be solved once we have AGI.
It is somewhat of a flawed analogy to NP-complete.
Kibble balance Updated +Created
The Kibble balance is so precise and reproducible that it was responsible for the 2019 redefinition of the Kilogram.
Figure 1.
NIST-4 Kibble balance
. Source.
It relies rely on not one, but three macroscopic quantum mechanical effects:
How cool is that! As usual, the advantage of those effects is that they are discrete, and have very fixed values that don't depend either:
  • on the physical dimensions of any apparatus (otherwise fabrication precision would be an issue)
  • small variations of temperature, magnetic field and so on
One downside of using some quantum mechanical effects is that you have to cool everything down to 5K. But that's OK, we've got liquid helium!
The operating principle is something along:
Then, based on all this, you can determine how much the object weights.
Video 1.
How We're Redefining the kg by Veritasium
. Source.
Video 2.
The Kibble Balance, realizing the Kilogram from fundamental constants of nature by Richard Green
. Source. Presented in 2022 for a CENAM seminar, the Mexican metrology institute. The speaker is from the Canadian metrology institute
Video 3.
The Watt balance and redefining the kilogram by National Physical Laboratory
. Source. Nothing much, but fun to hear Kibble talking about his balance in beautiful English before he passed.

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