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109 lines
7.0 KiB
Plaintext
109 lines
7.0 KiB
Plaintext
Episode: 4178
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Title: HPR4178: Today I learnt (2024-07-27)
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Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr4178/hpr4178.mp3
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Transcribed: 2025-10-25 20:52:47
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---
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This is Hacker Public Radio Episode 4178 for Wednesday the 7th of August 2024.
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Today's show is entitled, Today on Learn 2024-727.
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It is part of the series today I Learned.
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It is hosted by Dave Morris, and is about 8 minutes long.
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It carries an explicit flag.
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The summary is, a few more things I learned recently.
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Hello, welcome to Hacker Public Radio.
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My name is Dave Morris.
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Today I'm going to do a show with the heading of or in the series of today I learned.
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What I do for me is that as I come across interesting facts or things that seem worth putting
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into such shows, I keep them, keep an eye on them.
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So they're not actually today I learned items a few days ago, a few weeks ago, but bringing
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them all together like this I hope is interesting.
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The first item I've got is about the mass extinctions that have occurred on this planet.
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They've been I think five of these over the history of the planet, and they're various
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theories about what caused them and so forth.
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These are theories that come and go because more information is discovered.
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When I came across recently concerned the movement of the galaxy or movement of the solar
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system within the galaxy.
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So the galaxy is a big sort of disc, not an entirely flat one, but anyway, consider it
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as a disc and the solar system orbits the disc towards the outside I believe, but I'm
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not fully I'm not an astronomer so I don't understand this in a huge amount of detail.
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But as it orbits then it's not in parallel or co-planar with the galaxy.
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So there's points at which the solar system is a little bit above the middle of the galaxy
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and a little bit below.
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So when it's in the plane of the solar system then any gamma ray bursts that occur in the
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galaxy tend to be shielded from the solar system.
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But when it's above or below the plane then it's more vulnerable, we are more vulnerable.
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The period of rotation is the galactic year which is about 255 million years long.
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So the thinking seems to be that when the solar system is less protected the cosmic radiation
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has effects on the life on Earth.
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It does seem to be a correlation between the extinction events and the galactic year and
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the exposure of the solar system.
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But I don't get the message that this is a certainty, it's a theory, it's a hypothesis
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even not even got as far as a theory and of course extinctions may have multiple causes.
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If you look up my first link about extinction events in Wikipedia there's a lot of discussion
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there about how extinction has occurred.
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So it's an interesting area that can be investigated, that's what I think anyway.
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There's no certainty about it again but this was new to me so I thought I'd share it.
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And item is how you express the volume of liquid which is called milliliter, a thousandth
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of a liter.
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Do you write lowercase ml or lowercase m capital L?
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No, I was watching a YouTube channel recently, the guy that's cooking in Canada, I've made
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a pretty link to it and he finishes with the recipe usually either something he's created
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or most often from various old recipe books, that's the show I particularly watch, things
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from the 1920s and before, fascinating what people at, but often in the recipe contains
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measurements like a 540 ml can of tomatoes with the ml is lowercase m capital L.
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Now I did chemistry at school and university, somewhat relaxing the interior image, we
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were taught that the abbreviated form of milliliter is ml in lowercase.
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So I keep looking at this and thinking that can't be right.
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So I went to research it and that the mixed case one is permitted and it's preferred in USA
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Canada and Australia while we in Europe prefer the lowercase ml, didn't know that before.
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If you look at the link I've provided, the various abbreviations for fractions and multiples
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of liters all have a lowercase only and a mixed case version.
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So desiliter is lowercase dl and d capital L desiliter, a hundredth of a liter I guess.
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And I also discovered in the table there's a thing called a quetta liter which is ten
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to the thirty liters.
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So that's cool.
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Not sure where and I will need to know that information, but fun.
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The last one is a bit of sort of human anatomy and physiology and stuff which I do quite
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enjoy finding out about having been a biologist.
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This particular one is about a human gland called the mibumium gland.
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There's multiple of these, it's a type, they're types of sebaceous glands and they're
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in the eyelid.
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Now sebaceous glands are the ones that you get at the base of hair follicles.
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They produce an oily secretion that helps to keep the skin freer bacteria and just generally
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more flexible, not dried out and so forth.
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And the stuff that comes out of sebaceous glands is called sebum and it's from the Latin word
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for talo, the stuff that used to be used to make candles, it's of animal fat stuff.
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I did know about these, the mibumium glands are found on the edge of the eyelid just inside
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of the eyelashes and the oily substance they produce helps prevent the eye surface from
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drying out.
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It sort of seals in the tear liquid that keeps the eye surface moist and it stops it from
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drying.
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And it also helps, I was interested to see, it helps the eyelids to make an airtight seal
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when you close your eyes.
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There are other functions, there are links obviously to, if you want to dig deeper, find
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out more about it.
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I didn't know about these things as a student, but the sort of biology that I did was really
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animal biology and we looked at human anatomy to some extent, so we didn't, I'm not sure
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whether it was that they didn't spend much time on it because they had too many other
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things to do or whether less was known at that particular point.
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The glands have been known about, since 1600, 1700, the German physician called Henrich
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Mibum and that's obviously where the name has come from, from Germany and he was a physician
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and scholar, it says in Wikipedia, there's a link if you want to look.
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I didn't know that the secretions produced by these glands can reduce, as you get older
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and the glands will also be blocked and there's various drugs and other things, hormone
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levels that can affect them.
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The result is, the thing called MGD, Mibomium gland dysfunction, so when I went to see my
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optometrist, he said, you might have this, so you might need to get some treatment for
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your eyes because my eyes are a bit sore and dry sometimes.
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And of course, the name of the secretion of the Mibomium glands, riffing on the fact
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that sebaceous glands produce sebum, the secretion from Mibomium gland is called Mibum.
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Okay, that's the end, thanks very much, bye.
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You have been listening to Hacker Public Radio at Hacker Public Radio, does work.
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Today's show was contributed by a HBR listener like yourself, if you ever thought of recording
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a podcast, you click on our contribute link to find out how easy it really is.
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Hosting for HBR has been kindly provided by an honesthost.com, the internet archive
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and our syncs.net.
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On the Sadois status, today's show is released on our Creative Commons, Attribution 4.0 International
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License.
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