Today I Learned

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Today I learned that cleaning a white hat can be done with bleach cleaner, but it’s important to rinse it before wearing it again. I also discovered that "oyster veneering," a woodworking technique from the late 1600s, is experiencing a minor revival despite its labor-intensive nature. Additionally, I learned that the factorial of 23 (23!) equals 25,852,016,738,884,976,640,000, which interestingly has 23 digits, a unique coincidence among factorials. I found out that medical specialists often spend less than 10 minutes with patients, and that watching TV can contribute to weight gain. Other insights included the fact that a kiss can transfer around 80 million microbes, and that bureaucracy can sometimes hinder employment opportunities. The discussion also touched on various trivia, such as the emotional sensitivity of barn owls and the complexities of gravitational lensing around black holes.
  • #3,851
Keith_McClary said:
No, it was meant to be a nasty trick to play on a cat.
Calling the ASPCA and PETA right now! No, wait PETA says you are already cruel to keep a cat anyway.
 
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  • #3,852
https://www.yahoo.com/news/delta-infections-among-vaccinated-likely-192553854.html
In laboratory experiments, they found that three mutations in Lambda's spike protein, known as RSYLTPGD246-253N, 260 L452Q and F490S, help it resist neutralization by vaccine-induced antibodies. Two additional mutations, T76I and L452Q, help make Lambda highly infectious, they found. In a paper posted on Wednesday on bioRxiv https://bit.ly/3fpi5Fn ahead of peer review, the researchers warn that with Lambda being labeled a "Variant of Interest" by the World Health Organization, rather than a "Variant of Concern," people might not realize it is a serious ongoing threat. Although it is not clear yet whether this variant is more dangerous than the Delta now threatening populations in many countries, senior researcher Kei Sato of the University of Tokyo believes "Lambda can be a potential threat to the human society."

Third mRNA dose may boost antibody quantity, but not quality

Lambda variant shows vaccine resistance in lab :nb):nb):nb)

 
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  • #3,854
kyphysics said:
Lambda variant shows vaccine resistance in lab
It's not a binary thing. It shows more resistance - in the lab. If that transfers to actual infections is an open question, and what exactly that means for the vaccine efficacy is another open question. Does it go down at all? A few percent? More than that?
 
  • #3,855
My guess is Lambda is not a bigger deal than Delta. Both show about the same reduction in antibody effectiveness. For Delta, real world protection from infection could be quite affected (wide range of estimates 40-80%), but protection from severe disease is uniformly quite high about 90% (with many estimates 90+%), though there may be some drop from the very high initial levels (97%). Protection from severe disease is probably due in large part to T cells. So far lab measurements show that T cell responses are negligibly affected by variants. References in https://www.physicsforums.com/threads/lambda-variant-shows-vaccine-resistance.1005754/post-6523453

So everything is the same as before. Get vaccinated when your local health authority offers it. If you are in a vulnerable group, consider still wearing masks (etc) after that is no longer compulsory. Get a booster when the local health authority offers one.

 
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  • #3,856
Interesting. ^^^ I'll monitor that thread. Thanks.
 
  • #3,857
https://www.cnn.com/2021/08/12/us/san-francisco-vaccine-requirement/index.html
(CNN)San Francisco became the the first major US city to mandate proof of full vaccinations for certain indoor activities Thursday.

City residents age 12 and older will now be required to show proof they have been fully vaccinated against Covid-19 in order to enter indoor restaurants, bars, gyms and theaters, as well as large event spaces with at least 1,000 people, according to an announcement from Mayor London Breed.

Wondering if any other major U.S. cities will follow?

About 78% of San Francisco residents are vaccinated, the news release from the city said. Despite that, the city's current Covid-19 test positivity rate is 5.6%, surpassing the rate from the peak of the winter surge, which was 5.2%, the release said.
 
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  • #3,858
TIL our Sun switches magnetic poles every 11 years.

Finding that out is a little like being a biology enthusiast for decades and then one day discovering the existence of rodents.
 
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  • #3,859
DaveC426913 said:
TIL our Sun switches magnetic poles every 11 years.

Finding that out is a little like being a biology enthusiast for decades and then one day discovering the existence of rodents.
My, my... What a coincidence! That is the same period as the Sunspot cycle. Think there might be a connection there? :oldwink::oldwink:
 
  • #3,860
DaveC426913 said:
TIL our Sun switches magnetic poles every 11 years.

Finding that out is a little like being a biology enthusiast for decades and then one day discovering the existence of rodents.
What are these rodent things?
 
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  • #3,861
BillTre said:
What are these rodent things?
They're just the great great ... great grandchildren of some fish, don't worry about them.
 
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  • #3,862
Tom.G said:
My, my... What a coincidence! That is the same period as the Sunspot cycle. Think there might be a connection there? :oldwink::oldwink:
Yes. Well aware of the sunspot cycle. Certainly connected. How is unknown though.
 
  • #3,863
DaveC426913 said:
Yes. Well aware of the sunspot cycle. Certainly connected. How is unknown though.
The Sun of full of flux tubes, some gargantuan. Sometimes part of the tube rises through the surface of the Sun due to "magnetic buoyancy." (This subject is called magnetohydrodynamics.) The interior of the tube is colder than its surroundings so it makes a black spot. These spots always come in pairs. The tubes are attracted to poles of the opposite polarity. When they get there they weaken the magnetic field. Eventually it flips.

This doesn't happen in the Earth because the solid inner core resists flipping.
 
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  • #3,864
As far as being embarrassed about not knowing something, for the first sixty years of my life I thought Jupiter wasn't visible to the naked eye.
 
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  • #3,865
 
  • #3,866
Courtesy of a 2am internet rabbit hole, TIL the words heterological (a word that does not describe itself, such as "long", which is actually shorter than short) and autological (a word that does describe itself, such as unhyphenated). I also learned of the Grelling-Nelson paradox: heterological is a paradox because if heterological is heterological then it is autological, while if it is autological then it is heterological. On the other hand autological is a different kind of paradox, because if autological is autological then it is autological, while if it is heterological then it is heterological.

https://en.wikipedia.org/wiki/Grelling–Nelson_paradox
 
  • #3,867
Hornbein said:
As far as being embarrassed about not knowing something, for the first sixty years of my life I thought Jupiter wasn't visible to the naked eye.
I don't think you're alone in that.

Keep in mind that about 120 years ago and before, going back to the dawn of civilization, pretty much everybody with capable eyesight was an astronomer to some degree. There was a lot more walking back then, and using the stars was just something you did to get around after dark. People were keenly aware of the planets (well, Venus, Mars, Jupiter, and Saturn anyway), even if they didn't know what they really were. But they knew that unlike the other "stars," the planets moved around the sky. After the industrial age, with the advent of outdoor, artificial lighting; automobiles; and the corresponding light pollution, things changed; most people don't rely on stars anymore in their day to day lives.

Now I'm always looking up in the sky when I'm out and about. And if I'm loitering around somewhere, and I see something in the sky I find interesting, like one of the planets rising or whatnot, I might point it out to a stranger or acquaintance. On several occasions, the conversation went something like this:
Me: "Look, there's Jupiter," pointing to Jupiter.​
Other: "No it's not."​
Me: "Uh, yeah, that's Jupiter. You can tell it's a planet because it's not twinkling, and..."​
Other: "You can't see Jupiter."​
Me: "Sure you can. People have been tracking Jupiter for many thousands of years..."​
Other: "Jupiter is just something you see in books and sci-fi movies."​
Me: "No really, you can see Jupiter with the naked eye. As a matter of fact, it's one of the brightest objects in the sky actually..."​
Other: "It's the North Star."​
Me: "... ? ... ," muttering to myself, "Where do I even start with that ... That's not even North ..."​

I've met people who grew up in extremely light polluted cities. They were even skeptical of Carl Sagan's "The Cosmos," when Sagan would say something to the effect of, "billions and billions of stars ..." They would say to themselves, "Billions?! What the heck's he talkin' about. There's like eleven of 'em."
 
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  • #3,868
collinsmark said:
I don't think you're alone in that.

Keep in mind that about 120 years ago and before, going back to the dawn of civilization, pretty much everybody with capable eyesight was an astronomer to some degree. There was a lot more walking back then, and using the stars was just something you did to get around after dark. People were keenly aware of the planets (well, Venus, Mars, Jupiter, and Saturn anyway), even if they didn't know what they really were. But they knew that unlike the other "stars," the planets moved around the sky. After the industrial age, with the advent of outdoor, artificial lighting; automobiles; and the corresponding light pollution, things changed; most people don't rely on stars anymore in their day to day lives.

Now I'm always looking up in the sky when I'm out and about. And if I'm loitering around somewhere, and I see something in the sky I find interesting, like one of the planets rising or whatnot, I might point it out to a stranger or acquaintance. On several occasions, the conversation went something like this:
Me: "Look, there's Jupiter," pointing to Jupiter.​
Other: "No it's not."​
Me: "Uh, yeah, that's Jupiter. You can tell it's a planet because it's not twinkling, and..."​
Other: "You can't see Jupiter."​
Me: "Sure you can. People have been tracking Jupiter for many thousands of years..."​
Other: "Jupiter is just something you see in books and sci-fi movies."​
Me: "No really, you can see Jupiter with the naked eye. As a matter of fact, it's one of the brightest objects in the sky actually..."​
Other: "It's the North Star."​
Me: "... ? ... ," muttering to myself, "Where do I even start with that ... That's not even North ..."​

I've met people who grew up in extremely light polluted cities. They were even skeptical of Carl Sagan's "The Cosmos," when Sagan would say something to the effect of, "billions and billions of stars ..." They would say to themselves, "Billions?! What the heck's he talkin' about. There's like eleven of 'em."
Well then I'm not alone. I wonder how the Jupiter belief arose.

I live in Tokyo. It's a regency, not a city, with a governor instead of a mayor. It's really a bunch of towns that grew together and still have an identity. They all have community centers, some expensive ones with full-sized theaters. Some of them have planetaria. I always figured it was to show the children what the night sky really looked like.
 
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  • #3,869
TIL that it's the 100th anniversary of "", aka "The Coefficient of Determination", aka "R Squared".
I joked on Facebook today that it's a "math nerd number telling you how straight the line is".

According to wiki; "Wright, Sewall (January 1921). "Correlation and causation". Journal of Agricultural Research."

Not willing to rely too heavily on wiki, I found the same information elsewhere. I also pulled out my "Annotated Instructor's Edition of a First Course in Statistics", where the authors didn't mention the history, but did dedicate the book thusly:

To Those Who Open This Book with Dismay

It gave me a bit of a chuckle.
 
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  • #3,870
We lost a national treasure yesterday. :frown:

 
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  • #3,871
Stumbling around the internet, I blundered upon Cell Cakes!

Here are some of the best:

Screen Shot 2021-08-19 at 10.51.53 AM.png


Screen Shot 2021-08-19 at 10.50.51 AM.png


Screen Shot 2021-08-19 at 10.50.10 AM.png


Screen Shot 2021-08-19 at 10.49.43 AM.png
 
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  • #3,872
Here's something else I stumbled upon:

Screen Shot 2021-08-19 at 11.23.07 AM.png
 
  • #3,873
TIL: why we found helium - a noble gas that won't combine with anything and is buoyant in the atmo - in the Earth. I've always just sort of wondered why it wouldn't just float up and out of the atmo.

Well, I never connected it with the ongoing production of alpha particles (i.e. helium nuclei) that radioactive ores are constantly giving off.

Two things I knew about but never quite connected. :slaps forehead:

Like different sections of a jigsaw puzzle you've worked on, but you don't know are actually connected.
1629406289224.png


Thanks The Disappearing Spoon - And Other True Tales of Madness, Love, and the History of the World from the Periodic Table of the Elements by Sam Kean
 
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  • #3,874
TIL about another famous member of the 27 club: Robert Leroy Johnson.
(Btw. not listed on Wikipedia)
 
  • #3,875
:Google's 27 Club in a fit of FOMO. Is not at all a club to be part of. One star. Would not recommend:
 
  • #3,876
TIL has has been a recent improvement for the traveling salesman problem (find the shortest route visiting a given set of places). Finding the exact shortest path has an unreasonable runtime once there are many places to visit. In 1976 people found an approximation that guarantees a path that's no longer than 1.5 times the shortest path in metric spaces[/size] while having a more reasonable runtime. In 2020 the paper A (Slightly) Improved Approximation Algorithm for Metric TSP found an algorithm that guarantees a path no longer than 1.49999999999999999999999999999999999 times the shortest path. Slightly improved, indeed.
While no one will use the algorithm in practice, it shows that 1.5 is not a hard limit.
 
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  • #3,877
mfb said:
1.5 is not a hard limit
Isn't 1.5 not a hard limit, by definition? The hard limit is 1, right?

I hope the algorithm is interesting (or fast) because the difference between 1.5 and 1.49999999999999999999999999999999999 is underwhelming to engineers like me.
 
  • #3,878
1 is an obvious lower limit, but 1.5 might have been a limit for this type of much faster approximation. We now know it is not.

No one will implement the new algorithm for actual problems because its improvement is negligible (and it's more complicated).
 
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  • #3,880
mfb said:
its improvement is negligible (and it's more complicated).
And it is probably only an improvement if n>10^1000 .
 
  • #3,881
TIL, if you can't find your dog, go to the kitchen, open the refrigerator door, turn around and the dog will be right behind you.

Our dog responds to the sound of the microwave being open/closed, sounds of food preparation in the kitchen, and/or sounds of food wrappers being opened. I assume she associates the sounds with cheese and sliced meat.
 
  • #3,882
Astronuc said:
TIL, if you can't find your dog, go to the kitchen, open the refrigerator door, turn around and the dog will be right behind you.

Yeah, they're hard to find when they're in the refrigerator. . . . :oldlaugh: . :oldtongue:
Lol. . . . j/k

.
 
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  • #3,883
OCR said:
Yeah, they're hard to find when they're in the refrigerator. . .
That is true. I was thinking more along the lines of turning one's head and looking over one's shoulder. In my case, the dog comes to the kitchen and sits quietly while waiting for something. Her nails are long enough to hear her coming to the kitchen. One of our cats on the other hand is very quite, and sometimes, I'll step back from the refrigerator or counter, and she'll be right behind me. So, I've learned to look behind me before I move.
 
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  • #3,884
Astronuc said:
So, I've learned to look behind me before I move.

Lol. . . I'll bet that learning experience required just one loud lesson. . . . :wink:

.
 
  • #3,885
TIL that a 12m
Astronuc said:
In my case, the dog comes to the kitchen and sits quietly while waiting for something. Her nails are long enough to hear her coming to the kitchen.
Yup. My grand-fur-baby does that when she's not expecting food except by luck.
Astronuc said:
So, I've learned to look behind me before I move.
I am training her to lie down in the far corner of the kitchen so as not to get stepped on.
 
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  • #3,886
Today I learned
1) The actor that played Vic Fontaine in Deep Space Nine also played Dr. Tony Newman in The Time Tunnel.
2) Rhode Island and Providence Plantations became Rhode Island in 2020
3) Chubby Checker's name is an allusion to Fats Domino.

(OK: I learned the last of those yesterday.)
 
  • #3,887
Fewmet said:
Today I learned
1) The actor that played Vic Fontaine in Deep Space Nine also played Dr. Tony Newman in The Time Tunnel.
2) Rhode Island and Providence Plantations became Rhode Island in 2020
3) Chubby Checker's name is an allusion to Fats Domino.

(OK: I learned the last of those yesterday.)
RIL that the old TV show Here Come the Brides, was based on real events - The Mercer Girls or Mercer Maids.

The Mercer Girls or Mercer Maids were women who chose to move from the east coast of the United States to the Seattle area in the 1860s at the invitation of Asa Mercer. Mercer, an American who lived in Seattle, wanted to "import" women to the Pacific Northwest to balance the gender ratio. The women were drawn by the prospect of moving to a boomtown with a surplus of bachelors.[1] These events formed the basis of the television series Here Come the Brides.[2]
https://en.wikipedia.org/wiki/Mercer_Girls

I've always been fond of imports. :rolleyes:
 
  • #3,888
DaveC426913 said:
grand-fur-baby
My neighbor has a cat from her kids (because reasons). Is there a name for that?
 
  • #3,889
Reverse Feline Inheritance (RFI)
 
  • #3,890
Ivan Seeking said:
RIL that the old TV show Here Come the Brides, was based on real events - The Mercer Girls or Mercer Maids.

The Mercer Girls or Mercer Maids were women who chose to move from the east coast of the United States to the Seattle area in the 1860s at the invitation of Asa Mercer. Mercer, an American who lived in Seattle, wanted to "import" women to the Pacific Northwest to balance the gender ratio. The women were drawn by the prospect of moving to a boomtown with a surplus of bachelors.[1] These events formed the basis of the television series Here Come the Brides.[2]
https://en.wikipedia.org/wiki/Mercer_Girls

I've always been fond of imports. :rolleyes:
This is literally how the French Canadian population was established with the filles du roi. It's part of every history class in Québec high school:

https://en.wikipedia.org/wiki/King%27s_Daughters said:
New France, at its start, was mostly populated by men: soldiers, fur traders, and priests. The colony became more agricultural and by the mid-17th century there was a severe imbalance between single men and women in New France. The small number of female immigrants had to pay their own passage, and few single women wanted to leave home to move and settle in the harsh climate and conditions of New France. The population growth of the competing English colonies awakened concern among some officials about France's ability to maintain its claim in the New World.

To increase the French population and the number of families, the Intendant of New France, Jean Talon, proposed that the king sponsor passage of at least 500 women. The king agreed, and eventually nearly twice the number were recruited.
 
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  • #3,891
Keith_McClary said:
My neighbor has a cat from her kids (because reasons). Is there a name for that?
That's a grand-fur-baby too!

This dog is my son's.

Got two sons, one has given us a grand-fur-baby, the other has given us a grand-skin-baby.
 
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  • #3,892
TIL that there are crew-less ships, to go with driver-less cars.
CNN story.
Screen Shot 2021-08-25 at 10.13.25 AM.png


The first one, a few years ago, was a ferry (in 2018), so I guess that one could carry driver-less cars.
 
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  • #3,893
BillTre said:
... I guess that one could carry driver-less cars.
... and thus, less driver cars. :wink:
 
  • #3,894
TIL that the CO2 levels in my home have been nearly constantly way above healthy levels, and that high levels of C02 can cause major cognitive impairment, lethargy, and other problems.

https://onlinelibrary.wiley.com/doi/abs/10.1111/ina.12706

It took about 1 hour leaving all of the windows open for the C02 levels go below the "acceptable" 1000ppm threshold, and about 2 hours to get to better levels of about 500 (which is still less than optimal). The only problem is that leaving the windows open let's in the smoke, and in the summer let's in the heat, and in the winter let's out the heat.

Looking for a solution, I'm now trying to figure out if indoor algae tanks marketed as CO2 reducers/O2 generators could be a viable solution.
 
  • #3,895
Jarvis323 said:
TIL that the CO2 levels in my home have been nearly constantly way above healthy levels, and that high levels of C02 can cause major cognitive impairment, lethargy, and other problems.

https://onlinelibrary.wiley.com/doi/abs/10.1111/ina.12706

It took about 1 hour leaving all of the windows open for the C02 levels go below the "acceptable" 1000ppm threshold, and about 2 hours to get to better levels of about 500 (which is still less than optimal). The only problem is that leaving the windows open let's in the smoke, and in the summer let's in the heat, and in the winter let's out the heat.

Looking for a solution, I'm now trying to figure out if indoor algae tanks marketed as CO2 reducers/O2 generators could be a viable solution.
Do you know the source of the CO2? What is the level indoors versus outdoors?
 
  • #3,896
berkeman said:
Do you know the source of the CO2? What is the level indoors versus outdoors?
I think it's just me, because it's a small studio apartment with no ventilation system. I'm not sure what the outdoor levels are exactly, but so far at least 1000ppm lower than inside based on the drop I see after leaving the windows open for a long time.
 
  • #3,897
You might look around to see if any gas appliances have their outdoor exhaust vents blocked (bird or mouse nests, tree leaves). Actually any flame (incense, etc) will add a bit of CO2.

Just normal infiltration in most houses will be a few air changes per hour(ACH); that is unless it is a newer building in an area with significant climate extremes, those get sealed rather well and need forced air exchanges.

Cheers,
Tom
 
  • #3,898
Jarvis323 said:
I think it's just me, because it's a small studio apartment with no ventilation system. I'm not sure what the outdoor levels are exactly, but so far at least 1000ppm lower than inside based on the drop I see after leaving the windows open for a long time.
Do you have a way to measure CO levels too? I don't know what can cause an elevated CO2 level in your home...
 
  • #3,900
berkeman said:
It looks like it might be just you, if the air circulation is not very good...

https://learn.kaiterra.com/en/air-academy/tips-for-reducing-co2
Yeah, it seems like a common problem I guess. There is a gas water heater; maybe it could be a factor?

I bought an Awair air quality sensor which measures C02, TVOC, PPM2.5, temp, and humidity and I can connect it to smart plugs so that I can control my air purifier and possibly a humdifier/dehumidifier. But it turns out C02 is the biggest problem and there doesn't seem to be any practical solution.
 
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