The Weight of a Cell
69 points
5 hours ago
| 8 comments
| asimov.press
| HN
atombender
4 hours ago
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> A typical kitchen scale has a sensitivity of 0.1 grams

As someone who's been looking for a good kitchen scale, your typical kitchen scale is actually precise to then nearest gram at best, and in terms of precision it's probably not very precise at all. 0.1g is rare, and these usually cost more, especially if they're actually reliable.

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mlinhares
3 hours ago
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They're not even that expensive anymore, you can find pretty reasonably priced ones: https://www.amazon.com/dp/B0D66X8B5B/ref=sspa_dk_detail_2?pd...

I have the ooni one that i use for my baking and to measure yeast and it was one of the best investments i made.

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atombender
2 hours ago
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Probably fine, but I've had some poor experiences with those kinds of Chinese drop-shipped electronics that floods Amazon these days.
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nulld3v
2 hours ago
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Most of the budget scales I've seen are accurate to <0.1g. If in doubt, grab a cheap set of calibration weights for $20, I have 2 sets from China and both are accurate to <0.01g on all the weights from 1g up to 200g.

Obviously if you have the money, you can buy actual certified ASTM weights, but they are insanely expensive.

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nxpnsv
2 hours ago
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Coffee specific scales typically are around 0.1g accurate. They are a little more expensive, but certainly not unobtainable.
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madcaptenor
4 hours ago
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I hadn't thought about this, but this is probably why in baking recipes where amounts of flour, sugar, etc. are specified by weight, baking powder and any spices will be specified by volume.

Of course this is all false precision once you start adding eggs.

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duped
3 hours ago
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imo the reason to bake by weight is because the ratios of the major ingredients (flour, fat, sugar, and water) determines the properties of the dough, and it's impossible to measure by volume reliably (especially flour, which is the largest ingredient by weight in most recipes). Meanwhile you don't have to be precise with baking soda or yeast. Mix-ins like herbs are completely to taste. Salt could go either way.

Recipes absolutely adjust for the weight of the eggs and some rules of thumb for water and fat content. But that said, a chicken egg is like 55g with 10% tolerance (at least the eggs I buy, and I do everything by weight). 5g of mostly water one way or the other doesn't have a massive amount of impact on the dough, and you can always adjust based on feel after mixing.

At scale everything is measured by weight fairly precisely. But you really don't care about accuracy, since it's the ratios of ingredients that make the product and not the raw amounts.

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Metacelsus
5 hours ago
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Very cool. I wonder how the accuracy of weighing a single cell would compare to counting a huge number of cells (let's say 10^9) and doing a bulk weight measurement. The problem would shift to being able to accurately count cells, and being able to exclude the effects of liquid trapped in between the cells.
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Scene_Cast2
3 hours ago
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I've built a scale with a kHz sampling rate and gram precision at +/-100kg range.

One thing I found out is that getting calibrated accuracy beyond 0.1% is hard and expensive despite having all that precision.

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rolph
52 minutes ago
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SeanSullivan86
3 hours ago
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What happens when something is put on the scale while it's sampling? Does the curve depend on properties of the scale, or just properties of the object and the manner in which it was put on the scale?
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Scene_Cast2
3 hours ago
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It's the latter. The scale is meant for real-time monitoring of rapidly varying force (the primary application is about monitoring the force derivative and repeatable max force logging). It uses an aluminum load cell if you're familiar with those, there's a tad of a multi-kHz resonance that is typically overshadowed by the object properties.
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ridgeguy
4 hours ago
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Cool results and methods, but I'll disagree with one of the article's statements.

In talking about the work done on e. coli, a non spherical cell, it says the methods had to be changed due to "turbulence" attendant to the e. coli's departure from sphericity of the earlier tested yeast cells.

My rough calcs show a Reynolds number in the range of 1e-6. The onset of turbulence happens at Reynolds numbers of ~2300 for pure water. The 1% sugar solution would have a negligibly higher turbulence onset Reynolds number.

I expect the need for different methodology wasn't turbulence, but the difference in drag presented by an elongated e. coli compared to a spherical yeast cell.

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franciscop
4 hours ago
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Some surprising science fact that many people don't know, an animal egg (chicken, birds, etc) is a single cell, so there's a huge variability in the weight of a cell.
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btilly
4 hours ago
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I found this claim unbelievable, but it is mostly true. It isn't quite the whole egg, it is just the yolk. But that's still a very large cell!

http://cnet.com/home/kitchen-and-household/appliance-science... verifies this.

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madcaptenor
4 hours ago
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It's analogous to the mammalian egg, but a lot bigger. (And IIRC the egg is the largest cell in humans.)
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IAmBroom
1 hour ago
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And the smallest is the sperm.

Which, ironically, are both only haploid.

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Davidzheng
3 hours ago
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i guess if it's fertilized then it will soon have more cells
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MinimalAction
2 hours ago
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This seems like the non-Substack link: https://press.asimov.com/articles/cell-weight.
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shauniel
5 hours ago
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Asimov really is a breath of fresh air. Love their content
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lblume
5 hours ago
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> Cells are physical objects

This might sound trivial, but in me sparks a much larger point: which kinds of experimental designs and tests might we miss when engaging in a special science? In establishing dedicated methods I think it's highly likely for there to be low-hanging fruits of experimental setups not considered due to prevalence of these very specific frameworks.

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jcims
54 seconds ago
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Not sure I am tracking your point entirely, but any time I start digging into a new domain I regularly find that the language peculiar to that topic can hide concepts that are broadly familiar and, in part, exacerbate the problem that (I think) you are describing.
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