Today I Learned

[gmax137]

I usually search the thread before posting

Maybe you missed it, searching on "platypus" vs. @Orodruin 's "platypi."

TIL: Platypi

 

[symbolipoint]

Watch for a misspelling. Looking into the wikipedia article about Platypus, those spurs on rear fin are VENOMOUS. To tell in the post that they are "venous" seems a misspelling.

 

[Ivan Seeking]

I put together a curve-fitting program for a control system, using the least squares method for typically 100-1000 data points. The math gets a little crazy. In order to maintain five significant figures in my results, I had to go to seventeen significant figures in the calculations. A subtraction operation zeroed out the first twelve significant figures for real data having five sig figs. ACK!

 

[OmCheeto]

Actually seeing the results on TV can be very convincing, and it wasn't trash TV, it was a serious documentary on a serious channel with a serious Chilean biologist who discovered found that plant.

Well, your posts sent me on quite a rabbit-hole of a trip.

Boquila trifoliolata mimics leaves of an artificial plastic host plant {pmc.ncbi.nlm.nih.gov}
2021

"...Here, we demonstrate that plant vision possibly via plant-specific ocelli is a plausible hypothesis. A simple experiment by placing an artificial vine model above the living plants has shown that these will attempt to mimic the artificial leaves..."​

Vision in Plants via Plant-Specific Ocelli? {sciencedirect.com}
2016

"...Although plants are sessile organisms, almost all of their organs move in space and thus require plant-specific senses to find their proper place with respect to their neighbours. Here we discuss recent studies suggesting that plants are able to sense shapes and colours via plant-specific ocelli. ..."​

And a more 'pop-sci' synopsis with other interesting facts(plant vision was hypothesized back in 1905!)
Can this Plant /Actually/ See? {youtube, SciShow channel, with host Hank Green}

Needless to say, TIL a lot.
And should I ever return to growing plants in my living room, I'll be sure and put some clothes on before walking by them.

 

[Ivan Seeking]

Hey, pssssst, you all know about [Windows Key + G]?

 

[DaveC426913]

Do now!

 

[Ivan Seeking]

Maybe you missed it, searching on "platypus" vs. @Orodruin 's "platypi."

1 Platypi = 3.14 platypuses.

 

[sbrothy]

Watch for a misspelling. Looking into the wikipedia article about Platypus, those spurs on rear fin are VENOMOUS. To tell in the post that they are "venous" seems a misspelling.

Did I make myself guilty of that?! I hate it when I don’t catch my errors, although they are legion and it’s comparable to the charge of the light brigade in hopelessness.

EDIT: Although didn’t the light brigade actually succeed? Gotta read up on history…

EDIT2: Nope. I remembered correctly there at least.

 

[jtbell]

TIL that avocado scanners are a thing.

 

[collinsmark]

I put together a curve-fitting program for a control system, using the least squares method for typically 100-1000 data points. The math gets a little crazy. In order to maintain five significant figures in my results, I had to go to seventeen significant figures in the calculations. A subtraction operation zeroed out the first twelve significant figures for real data having five sig figs. ACK!

Yep, fitting algorithms can sometimes push precision limits.

But beware of overfitting. Not only does overfitting waste computational resources, it can lead to erroneous conclusions -- and as possibly applied here: suboptimal control systems.

 

[DrGreg]

I put together a curve-fitting program for a control system, using the least squares method for typically 100-1000 data points. The math gets a little crazy. In order to maintain five significant figures in my results, I had to go to seventeen significant figures in the calculations. A subtraction operation zeroed out the first twelve significant figures for real data having five sig figs. ACK!

Yep, fitting algorithms can sometimes push precision limits.

But beware of overfitting. Not only does overfitting waste computational resources, it can lead to erroneous conclusions -- and as possibly applied here: suboptimal control systems.

It's also worth mentioning that, although $\Sigma x_n - \Sigma y_n$ and $\Sigma( x_n - y_n )$ are mathematically identical, computationally they could be significantly different when working with limited precision.

 

[sbrothy]

... that according to Wikipedia the Bullet Ant (Paraponera cavata) is so called because its sting is comparable to being shot! Now, Wiki being Wiki, I thought this might be hyperbole and looking at a more serious paper, for which I'm afraid I don't have full access, I'm given a more measured comparison:

The stings, however, were equal to a bad wasp sting [sic].

---- The Sting of the Ant, Paraponera clavata


As I don't have access to the full paper it might go on to specify differences based on geography and family. Another source has this to say:

Spruce wrote of a sting by Paraponera: “I was in agonies, and had much to do to keep from throwing myself on the ground and rolling about as I had seen the Indians do when suffering from the stings of this ant. I can only liken the pain to that of a hundred thousand nettle stings. My feet and sometimes my hands trembled as though I had the palsy, and for some time the perspiration ran down my face from the pain”. Further biology of these ants and their venom is detailed in Schmidt. A multitude of clinical presentations have been reported with most highlighting the “waves” of muscular contractions and the intense and unceasing pain.

---- A reexamination of poneratoxin from the venom of the bullet ant Paraponera clavata (Citations removed by me).

Again it's behind a paywall, but I'm not altogether convinced that the name isn't apt....

(Now, I did actually search the forum for both it's common and Latin names but came up short. I hope it isn't a double.)

 

[collinsmark]

... that according to Wikipedia the Bullet Ant (Paraponera cavata) is so called because its sting is comparable to being shot! Now, Wiki being Wiki, I thought this might be hyperbole and looking at a more serious paper, for which I'm afraid I don't have full access, I'm given a more measured comparison:


---- The Sting of the Ant, Paraponera clavata


As I don't have access to the full paper it might go on to specify differences based on geography and family. Another source has this to say:


---- A reexamination of poneratoxin from the venom of the bullet ant Paraponera clavata (Citations removed by me).

Again it's behind a paywall, but I'm not altogether convinced that the name isn't apt....

(Now, I did actually search the forum for both it's common and Latin names but came up short. I hope it isn't a double.)

Here's a related video by Matt Parker's Stand-up Maths. (Most people on PF are familiar with Matt Parker from his semi-comedic, math videos [he's also been on Numberphile several times]). This video is about pain scales, but it features the "bullet ant."

 

[pinball1970]

T.I.L. That Jackie Lee sang backing vocals on Hendrix's "Hey Joe."

This was after getting all nostalgic reading the three months summer break thread. Jackie Lee sang "White Horses," which all 1960s/70s Brit kids remember.
Anyway she is still going 89.

 

[sbrothy]

Here's a related video by Matt Parker's Stand-up Maths. (Most people on PF are familiar with Matt Parker from his semi-comedic, math videos [he's also been on Numberphile several times]). This video is about pain scales, but it features the "bullet ant."

Hahaaa funny. “Stand-up Mathematician”?! Hmmm
But yeah. Definitely ouch!

EDIT: But not as bad as I’d expected though

 

[sbrothy]

… that a male blue whale ejaculates on average 20 litres!

I really wish I could unread that. The next best thing being sharing the pain with you. That may sound a little thin given the name of the site where I read it:

https://baleinesendirect.org/en/how-much-sperm-does-a-blue-whale-ejaculate/

 

[Hornbein]

… that a male blue whale ejaculates on average 20 litres!

I really wish I could unread that. The next best thing being sharing the pain with you. That may sound a little thin given the name of the site where I read it:

https://baleinesendirect.org/en/how-much-sperm-does-a-blue-whale-ejaculate/

Think big, dude.

 

[fresh_42]

TIL about waves in the Milky Way.

A gigantic wave runs through the Milky Way, causing countless stars to rise or fall considerable distances. A research group discovered this using data from ESA's Gaia space telescope. It resembles a pond whose surface has been set vibrating by a stone, except that the gigantic wave in the Milky Way extends across large parts of the outer disk of the galaxy. Its cause is completely unclear, but it's conceivable that it stems from a collision with a dwarf galaxy, the research group writes. It's also possible that it's connected to a much smaller, wave-like gas structure dubbed the "Radcliffe wave." Both of these, however, still need to be investigated.

Pop Science Article: https://www.heise.de/news/Ursache-u...e-laeuft-eine-gigantische-Welle-10690112.html
Science Article: https://www.aanda.org/articles/aa/full_html/2025/07/aa51668-24/aa51668-24.html

 

[sbrothy]

I know they’re been mentioned before on the site. Still, the story bears repeating for it’s “horrificy” alone. It’s no secret that the Curies faired badly digging thru tons of radioactive ore in search of the radium they discovered. The following “radium-craze” (toothpaste with radium and whatnot) is also no secret. I hadn’t heard of the

Radium Girls

though. The concept of “radium jaw” was also new to me.

Truly horrific! Especially as it could so easily have been avoided.

EDIT:

Here’s a perhaps better (YMMV) link:

Radium Girls (Cult of Weird)

 

[BillTre]

Truly horrific! Especially as it could so easily have been avoided.

Knowledge is a good preventative.

 

[sbrothy]

Knowledge is a good preventative.

Yeah well, ironically the knowledge was there. Too bad the women never asked themselves why the scientists, and others "in the know", never visited the factory floor.

 

[BillTre]

Yeah well, ironically the knowledge was there. Too bad the women never asked themselves why the scientists, and others "in the know", never visited the factory floor.

Well I guess they didn't know then.

 

[sbrothy]

Well I guess they didn't know then.

Hah! Right you are! I guess the moral is that who knows is perhaps as important as knowing in the first place?

 

[gleem]

Not much was know about radiation effects at the turn of the century. They knew excess exposure caused severe tissue injury early on. Based on that radiation in particular from Radium was used to treat and cure cancers. But it was an impirical science. Ion chamber were used to measure x-rays ability to ionize air and the Roentgen was defined. But Radium's emission included alpha and beta radiation which was not appreciated and probably not measured with those early instruments so they most like underestimate the radiation effects.

It wasn'tuntil the 30's that any signifcant work on biological effect of radiation was begun.

For quantifying radiation effects you need absorbed dose (today the Gray measured in Joules/Kg) which did not occure until the early 50's.

The early sucess of Radium in cancer treatment probably led people to believe it could be healthy in small amounts. `But formal drug trials are really something fairly recent post 1940 so if you want to find out how good a medicine was well give to patients and see what happens. Drug safety testing did not occur until 1938 when a sulfanilamide elixer killed 100 persons leading to the Federal Food, Drug, and Cosmetic Act.

 

[sbrothy]

But formal drug trials are really something fairly recent post 1940 so if you want to find out how good a medicine was well give to patients and see what happens. Drug safety testing did not occur until 1938 when a sulfanilamide elixer killed 100 persons leading to the Federal Food, Drug, and Cosmetic Act

Yes. Formal drug trials. Those are effective. A control group is sometimes impractical though. These occurred simultaneously with project Manhattan (EDIT: oops and later):

https://ahf.nuclearmuseum.org/ahf/history/human-radiation-experiments/

EDIT: Nah, I'm sorry. I'm tired, cynical and a little inebriated. cya tomorrow.

 

[sbrothy]

..., while reading about "solderless breadboards", the wonderful term parasitic capacitance.

 

[symbolipoint]

What I did not yet realize was the correct spelling and the easy connection to very directly translatability, but still confused about the actual suffixes.

T.I.L. that Feniculi Fenicula (I need to learn how to put in the accents at the ends) , the song, as title means, "Fenicular up, Fenicular down".

note: this might not paste correctly but supposed to show back-slanted segments above both last syllable vowels: funiculì, funiculà

 

[sbrothy]

Didn't exactly learn this today but bumbed into it again. It's still breathtaking:

The enormous clouds of material known as the eRosita and Fermi bubbles extend above and below the galactic plane of the Milky Way. NASA/KAREN YANG/MATEUSZ RUSZKOWSKI/ELLEN ZWEIBEL

---- https://www.physics.wisc.edu/2022/0...-milky-way-caused-by-supermassive-black-hole/

The Double-Episode Jet Genesis of the eROSITA and Fermi Bubbles (arXiv)

 

[Hornbein]

---- https://www.physics.wisc.edu/2022/0...-milky-way-caused-by-supermassive-black-hole/

Astronomer Ellen Zweibel. Zweibel is German for onion.

 

[symbolipoint]

Astronomer Ellen Zweibel. Zweibel is German for onion.

One of those sounds good as a surname or family name and the other not so much.