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Wikipedia:Reference desk/Archives/Science/2021 January 18

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January 18

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Why do heart patients feel numbness in left arm?

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Why do heart paitents feel numbness in left arm? Why specifically left arm ?Rizosome (talk) 02:01, 18 January 2021 (UTC)[reply]

As noted in Myocardial infarction, pain can be felt in various places, including the right arm as well as the left. ←Baseball Bugs What's up, Doc? carrots→ 08:18, 18 January 2021 (UTC)[reply]
See Referred pain as well. MarnetteD|Talk 02:12, 19 January 2021 (UTC)[reply]
The heart is on the left, and the arrangement of the blood vessels coming off of the aorta sends blood more forcefully to the left arm than the right. I recall hearing that it is thought that disturbances in the blood flow caused by the heart laboring prior to, during and after an infarction manifest more on the left due to this positioning of the left subclavian artery. Abductive (reasoning) 11:04, 19 January 2021 (UTC)[reply]
The heart is not on the left in humans, rather it is in the center of the chest, as a visit to Heart will bear out, the left ventricle is larger than the right, so people might think the heart is more to the left, but it is centered between the two lungs:

The largest part of the heart is usually slightly offset to the left side of the chest (though occasionally it may be offset to the right) and is felt to be on the left because the left heart is stronger and larger, since it pumps to all body parts. Because the heart is between the lungs, the left lung is smaller than the right lung and has a cardiac notch in its border to accommodate the heart.[7]

Wevets (talk) 00:50, 24 January 2021 (UTC)[reply]
It's a little curious to me that the OP asked about numbness, but all the responses have been about pain. Numbness is pretty much the opposite of pain.
I am not aware that numbness in the left arm is in fact a symptom of a heart attack. --Trovatore (talk) 02:15, 24 January 2021 (UTC)[reply]

Sydney Harbour Bridge

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Are the names of the steel makers stamped on to the girders? Jacquesviii (talk) 13:50, 18 January 2021 (UTC)[reply]

I have never heard of that being the case. There appears to be no mention of it in our Sydney Harbour Bridge article. Why would they be? Is this a convention among bridge builders? HiLo48 (talk) 02:05, 19 January 2021 (UTC)[reply]
When you say "steel makers", do you mean the guys who manufactured the structural steel used in the bridge? Or maybe just the company name, such as U.S. Steel? ←Baseball Bugs What's up, Doc? carrots→ 02:17, 19 January 2021 (UTC)[reply]
Yes. The bridge was prefabricated by DORMAN LONG in Middlesbrough ENGLAND before being shipped to Sydney. I have seen many examples of DORMAN Long girders and beams that were stamped with that name but am curious to know if that happened to the Sydney Harbour Bridge steelwork. Thanks.82.34.222.35 (talk) 09:50, 19 January 2021 (UTC)[reply]
It seems the answer is "yes". Abductive (reasoning) 11:27, 19 January 2021 (UTC)[reply]
I distinctly remember seeing the name on the bridge when I visited decades ago, as it gave rise to a prolonged piss-take of our Australian hosts, who had previously been outspoken on the supposed inferiority of British weather, food, beer, cricket etc. etc. However, I have failed miserably to find a photograph. Alansplodge (talk) 14:25, 19 January 2021 (UTC)[reply]
The Sydney Harbour Bridge is truly magnificent. Climbing it and seeing 'Dorman-Long Middlesbrough' stamped on the girders made me proud - and furious at the same time. It is incomprehensible that Teesside has failed to let the world know that it originated on Teesside. 82.34.222.35 (talk) 23:51, 19 January 2021 (UTC)[reply]

Diary of Portuguese traveller from 1506.

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I'm trying to find out about the earliest record of European contact with chimpanzees, and one of the pieces of information I keep finding, is that "The diary of Portuguese explorer Duarte Pacheco Pereira (1506), preserved in the Portuguese National Archive, is probably the first European document to acknowledge that chimpanzees built their own rudimentary tools." And everywhere I look I just keep finding that same sentence, probably originally from Wikipedia, without giving any source. Is there anywhere that would provide an actual source, or an extract of the diary that explains this comment, because it seems a fairly remarkable claim, given that this is what Jane Goodall became known for over 400 years later. Thanks.

Having nothing better to do, I scanned through an English translation of Esmeraldo, but the only possible description of an ape is in Chapter 33 which is about Sierra Leone and where Pereira says:
"Here, as well, are wild men whom the Ancients called satyrs. They are covered with hairs almost as coarse as the bristles of a pig; they seem human and lie with their wives after our fashion, but instead of speaking they shout when they are hurt. As they dwell in the fastnesses of this Serra they can rarely be captured except when very young. I omit many other things concerning them in order to avoid prolixity".
The editor has a footnote saying that this has been taken as referring to gorillas, however these are not found in Sierra Leone. Alansplodge (talk) 14:05, 19 January 2021 (UTC)[reply]
(ec) The supposed reference to chimpanzees is almost certainly to this brief passage, translated by George H. T. Kimble as: Here, as well, are wild men, whom the ancients called satyrs. They are covered with hairs almost as coarse as the bristles of a pig; they seem human and lie with their wives after our fashion, but instead of speaking they shout when they are hurt. As they dwell in the fastnesses of this Serra they can rarely be captured except when very young. Most scholars of the text have interpreted these "wild men" covered with coarse hair, incapable of speech, as being chimpanzees. There is no mention of the use or making of tools, though; someone must have made that up, or must have misinterpreted what someone else wrote, after which this kept being copied.  --Lambiam 14:11, 19 January 2021 (UTC)[reply]
Yes, its a bit suspicious that nearly every reference starts with an identical formula: "The diary of Portuguese explorer Duarte Pacheco Pereira (1506)..." Alansplodge (talk) 14:19, 19 January 2021 (UTC)[reply]
I've added a [dubious – discuss] tag to the claim in our Duarte Pacheco Pereira article. Alansplodge (talk) 16:20, 19 January 2021 (UTC)[reply]
You may also be interested in Man's Place in Nature (1863) by Thomas Henry Huxley, which discusses the early descriptions of apes in Chapter I: ON THE NATURAL HISTORY OF THE MAN-LIKE APES. Alansplodge (talk) 14:50, 19 January 2021 (UTC)[reply]

What laying position is more likely to cause nocturnal emission, prone or supine positions?

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What laying position is more likely to cause nocturnal emission, prone or supine positions? I'm looking for scientific references for it. (n.b. I know there are different causes, but I'm asking specifically about the influence of those 2 sleeping positions) --ThePupil (talk) 22:17, 18 January 2021 (UTC)[reply]

Neither is more likely to cause it, because it's caused by other factors entirely.
The bulk of ejaculate comprises seminal fluid, which is produced by the seminal vesicles fairly continuously to replenish what may be ejaculated via intercourse or masturbation. If the latter occur sufficiently infrequently that the vesicles reach their capacity, a nocturnal emission will occur (in a healthy individual) regardless of sleeping position.
All humans necessarily dream, usually several times per night (though dreams are usually remembered only if the individual wakes during or shortly after dreaming), and in healthy males this is usually accompanied by penile erection regardless of the dream content (which is only sexual about 10% of the time).
Not surprisingly, nocturnal emissions usually (though not invariably) occur during penile erection and hence dreaming, and the associated sensations may influence the subject matter of the dream (with sexual or urinatory images), and may also induce the sleeping dreamer to adopt a posture reinforcing the sensations, which may more often be prone since this places pressure on the penis – however, the position is at most a result of the process, not its cause. {The poster formerly known as 87.81.230.195} 90.200.40.9 (talk) 01:12, 20 January 2021 (UTC)[reply]
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