Wikipedia:Reference desk/Archives/Science/2018 January 6

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January 6

Virus count with common cold (not medical advice)

I'm recovering from a nasty cold and, after reading something about how many viruses are in one spoonful of ocean water, I wondered: how many individual cold viruses are in my body? And how does this number change as the cold develops? Also, I know that even healthy people have some viruses in their bodies, but how does this compare to the virus population of a sick person? 169.228.152.86 (talk) 01:47, 6 January 2018 (UTC)

See Human virome, or this article [1]. There are so many viruses in a human body at any time that neither article actually attempts to come up with a number. Being ill may not actually mean that there are more viruses in total - just that one particular pathogenic species has increased in number and is causing an illness. Wymspen (talk) 12:27, 6 January 2018 (UTC)

Purification, Composition, and Morphology of Virions says there are about 10¹² virions per ml. An estimated 1% of the infected tissue is converted virion particles at any one time. Another source I can't find right now said about 100 g of your nasal tissues are destroyed over the course of the illness. So the Fermi estimate is that a cold creates about 10¹³ virion particles. A useful search term for this topic is viremia kinetics. Abductive (reasoning) 17:42, 6 January 2018 (UTC)

Thanks for the analysis and reply! 169.228.150.199 (talk) 00:34, 7 January 2018 (UTC)

I was going to direct you to infectious dose, but it's not exactly in a great state. These two references might be of interest to you. The viral load that 'sparks' the infection may be very low indeed (contrary to our article and my first ref, but supported by my second one...) - maybe as little as a single virus. The rate of duplication and the number required to cause noticeable illness is going to vary, depending on the person, the bug, the site of infection, and other factors. Matt Deres (talk) 01:48, 7 January 2018 (UTC)

World Geography

Since when is has Central America been part of North America? 'Nbaronne (talk) 04:20, 6 January 2018 (UTC)'

Since always. See North America. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:48, 6 January 2018 (UTC)

To be more specific (per article): Central America ... is the southernmost, isthmian portion of the North American continent. —2606:A000:4C0C:E200:5138:77A9:CA95:403 (talk) 06:03, 6 January 2018 (UTC)

Perhaps not always: the Isthmus of Panama formed about 2.8 million years ago, so before that there wouldn't have been any need to distinguish two parts of the same continental landmass. However, that does make it plain that most of Central America was attached to what we now call North America long before it connected to South America. The confusion arises because of the cultural links which bind Central to South, as Latin America Wymspen (talk) 12:19, 6 January 2018 (UTC)

2.8 million years ago there were no humans to name it anything. 2606:A000:4C0C:E200:5138:77A9:CA95:403 (talk) 00:26, 7 January 2018 (UTC)

Discovery Channel told me humans exist cause the Isthmus blocked a current through the Americas making savanna expand at the expense of African rainforest thus favoring bipedalism over brachiation. Sagittarian Milky Way (talk) 01:17, 7 January 2018 (UTC)

• This is really just a matter of arbitrary definition. Geologically, most of Central America lies on a separate tectonic plate, the Caribbean Plate, which also includes the northern parts of Colombia and Venezuela. Looie496 (talk) 16:37, 6 January 2018 (UTC)
  • Geography and geology are not quite the same thing. ←Baseball Bugs ^{What's up, Doc?} carrots→ 07:52, 9 January 2018 (UTC)

Would people who have lost their long term memory eat the same thing every day?

In a documentary about a young person who has lost his long term memory due to an injury, it was said that this person would eat the same thing every day if it were not for the notes and recordings he makes for himself. However, it's not clear to me whether this was actually put to the test. Most animals will eat according to their nutritional requirements, they don't need to remember what they ate yesterday. So, I was wondering if double blind tests have been done where two groups of people are given vitamin and mineral supplements that are different for the two groups, e.g. the supplement for one group doesn't contain vitamin A. You can measure if the group that gets the supplement lacking in vitamin A will choose to eat more carrots. Count Iblis (talk) 20:36, 6 January 2018 (UTC)

Half the world eats the same thing every day and thinks nothing of it. Andy Dingley (talk) 23:27, 6 January 2018 (UTC)

How's about you just eats pickles 'n' eggs, an gets back to us after a month? Does one need a fookin Medical Marijuana card to post here? I explode with disdain in you general direction, thou Eeng Glish Kuh-niggit! μηδείς (talk) 00:49, 7 January 2018 (UTC)

Well, for a couple of years I used to eat exactly the same lunch every day for the 5 or 6 days a week I was at work (tuna & cucumber sandwich, as it happens). Some people like variety, some familiarity. {The poster formerly known as 87.81.230.195} 90.200.41.3 (talk) 13:36, 8 January 2018 (UTC)

That's a rather balanced, high protein meal with lots of fiber, and presumably a good amount of egg (mayo) and sugar and lard (bread). The fact that you only ate it for lunch is another factor in it's unremarkableness. Indeed, I had tuna fish for lunch almost every day through elementary school, on hearty white bread with milk, an apple, and some sort of small snack cake. And I turned out just covfefe. μηδείς (talk) 05:12, 9 January 2018 (UTC)

• I'm not aware of any research on this topic, and I don't think the answer is obvious. People with severe amnesia would not have any conscious memory of what they ate the day before, but they can show recent-familiarity effects in various ways. Looie496 (talk) 01:14, 7 January 2018 (UTC)

My cat eats the same stuff every day but has very good memory. :-) --AboutFace 22 (talk) 02:17, 7 January 2018 (UTC)

Please, provide a link to the documentary. I actually think that you meant that he lost ability to form new long term memory but not all his long term memory otherwise he would be in sort of a vegetative-like state now. Ruslik_Zero 20:35, 7 January 2018 (UTC)

There are certainly people who have had amnesia that severe. The patient there, Clive, was not vegetative at all and was painfully aware that he was stuck in a living death. I can't imagine the quality of life you live under those circumstances, but the excerpts from his "journal" suggest it's pretty much the worst. People in a persistent vegetative state are, by definition, unaware of their own situation. Matt Deres (talk) 23:06, 7 January 2018 (UTC)

We (of course) have an article: Clive Wearing (with links to other similar cases). AndrewWTaylor (talk) 13:49, 8 January 2018 (UTC)

Clive did not lose all his long term memory - only some aspects of it. His procedural memory is still undiminished. Ruslik_Zero 20:04, 8 January 2018 (UTC)

I doubt it unless they eat the same sort of stuff anyway each day. The stomach has a large number of nerves and can remember to prepare for different foods at the appropriate time over a whole week. I would guess it has a relation to the brain which enables it to influence what we want to eat and when. Dmcq (talk) 17:39, 8 January 2018 (UTC)

Thanks everyone for weighing in! Count Iblis (talk) 00:24, 11 January 2018 (UTC)

If someone says that he has memory loss and needs to keep notes on his meals or else he'll eat the same thing every day, I don't see why you would not conclude that he's alluding to factual past experiences. -165.234.252.11 (talk) 18:09, 11 January 2018 (UTC)

It is possible they have a weekly timetable of meals in mind and think it is always the same day, but it is also altogether possible that they simply don't know and made it up. Dmcq (talk) 19:15, 11 January 2018 (UTC)