Ask HN: Teach me something new

Come on, who do you think you are talking with? I have read many papers about C.elegans and my claims are backed up: "the inability to reliably identify all neurons within whole-brain recordings has precluded a full picture with circuit-level details."

"we expect our work to aid in these endeavors (Bargmann and Marder, 2013; Brennan and Proekt, 2019; Kaplan et al., 2020; Kato et al., 2015). A richer set of network responses, even for simple chemosensory inputs, has broad relevance in understanding sensorimotor processing"

"The application of NeuroPAL to whole-nervous-system activity recording is mainly limited by nuclear localization of the GCaMP activity sensor, as this may fail to capture highly localized events in axodendritic compartments. This limitation, combined with potentially incomplete or variable anatomical synaptic annotations, may have contributed to the lack of correlation we observed between functional activity and synaptic connectivity."

Neuropal is an extremely recent advance (2021) https://www.cell.com/cell/fulltext/S0092-8674(20)31682-2?_re... it is the first to allow a complete mapping of GABA receptors (except mitochondria GABA translocator) however complete maps for other receptors, such as mGLURs, NMDA, kainate, ampa, etc are LACKING, as I said. Let alone realtime data that take into account the individual variances over multiple worms. (they should study genetic clones btw) real time data are rare, nowhere near big-data https://www.youtube.com/watch?app=desktop&v=B4gNamS8Ars and when they exist, they lack the complete information (receptor locations, precise neurostransmitter density per axon, etc) C.elegans might be trivial to understand, without a complete map of axons and recpetors, it would still appear generally un-studiable.

As for the 150-300 neurons it is a matter of debate. IIRC the paper I linked refer to ~150 neurons in the head, the rest would be the PNS, not the CNS. But I'm not sure of the exact CNS/PNS ratio besides this paper.

30 W of Neutrinos pass you all the time. However due to how little they interact that doesn't actually heat you up almost at all.

Always has been. BTW homoiconicity matters in artificial intelligence research https://en.wikipedia.org/wiki/Homoiconicity

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Arithmetic with Roman numerals.

You often hear that it was next to impossible to calculate with Roman numerals. That's not true at all. People developed a very ingenious scheme to do additions and multiplications using pebbles. Since the word for pebble in Latin is calculus, we now call calculus calculus.

How did it go? You represented the digits of a number by a pebble. You drew some lines in the sand, some rows and columns. The rows represented the digit magnitude (I, V, X, etc). The columns were for the operands. Two columns for a number. Why two? Because Roman numerals sometimes use negative digits.

Let's see a concrete example. You want to do the addition 28+44. That is XXVIII + XLIV.

You first draw the lines and put the pebbles in the corresponding squares. Note that XLIV has two negative digits (44 = XLIV = -10 + 50 -1 + 5). So the pebble for 10 and the one for 1 are put on the left side.

The first number does not have any negative digits, so no pebbles in its left column.

  ———————————————————————————————
  L    |        ||       |  o
  X    |   oo   ||   o   |
  ——————————————————————————————— 
  V    |    o   ||       |  o 
  I    |  ooo   ||   o   |
  ———————————————————————————————

So, now that we set the pebbles, we need to do the calculation. We can do it in many ways. Let's start by first canceling the digits that can be canceled: a positive 10 pebble with a negative 10 pebble, and a positive 1 pebble with a negative 1 pebble. The table looks now like this:

  ——————————————————————————————— 
  L   |        ||       |  o
  X   |   o    ||       |
  ——————————————————————————————— 
  V   |    o   ||       |  o 
  I   |   oo   ||       |
  ———————————————————————————————

At this point we reduced the initial addition 28 + 44 (XXVIII + XLIV) to the equivalent one XVII + LV ( 17 + 55).

Now we just move the pebbles from the fourth column to the second column.

  ——————————————————————————————— 
  L   |   o    ||       |   
  X   |   o    ||       |
  ——————————————————————————————— 
  V   |   oo   ||       |   
  I   |   oo   ||       |
  ———————————————————————————————

We are almost done. We got the result as LXVVII. But this is not a valid Roman numeral, we need to do the simplification VV = X. We remove the two 5-pebbles and add a 10-pebble. Oh, and let's get rid of the last 2 columns.

  ————————————————
  L  |   o      || 
  X  |   oo     ||  
  ————————————————
  V  |          ||   
  I  |   oo     ||   
  ————————————————

So now our final result, in correct form, is LXXII, or 72.

Multiplication can be also performed, and it's quite a lot of fun. I'll explain it in the post below.