text:
What is the term for awareness of or inclusion of real sounds within a dream?
I fell asleep while listening to a podcast, and I am sure I was dreaming but I could also still hear the podcast.
The podcast played an important role in the dream, I was searching for the source of the voice, wondering if others in the dream could hear the same voice. I started to feel a bit panicky and woke up as the podcast also happened to end. I rewound the show and confirmed that it was all there, exactly as I had heard in my dream!
I would like to read more about this type of experience, but I am having trouble finding the right words to search. Is there a name for this phenomenon? Is there anything that contributes to experiences like these? I know it wasn't lucid dreaming, because I wasn't aware of being asleep.

People are voting to close based on personal medical advice... I think that might be overinterpreting that rule a bit, but you could try to rewrite your question to ask about the more general phenomenon rather than your personal experience, that would be better. Incorporation of external stimuli into dreaming is a bit controversial, but you mentioned you have a baby, and disruptions of or lack of sleep can mess with sleep cycles. You aren't directly describing "lucid dreaming" but searching on that topic might interest you.

OK, thanks @BryanKrause! I'm not looking for "personal medical advice" since there's nothing wrong with me. But I've edited the question now!

And also no, it wasn't lucid dreaming, I wasn't aware of being asleep.

Yes that's what I figured, which is why I asked you to edit rather than voting to close. I know you weren't describing lucid dreaming, but I feel like that term is sometimes overused. In the literature you will probably find people talking about it as "influences of external stimuli on the content of dreams" or something similar. However, there is some disagreement on whether people are really conscious of the external stimuli or whether they are actually just waking up a bit. The rest of what you describe just sounds like normal dreaming.

I made some fairly substantial edits to pare down the personal story to the most relevant details which will hopefully encourage people to not vote to close or revert their votes. I'm not sure if there is a name for the phenomenon beyond the suggestions I gave to look into awareness/influence of external stimuli during dreams but maybe someone else will come along with a good answer.

@ZeroOne I've retracted my close vote after you edited.
Thanks. Also, in my personal opinion, I think your baby has very likely trained you to sleep more lightly making you more aware of your surroundings while sleeping.

This phenomenon - of incorporating the sounds we hear into our dreams - is very well known, and has been studied. Of all the senses, the one least likely to reach a level of consciousness during sleep is smell. It seems our olfactory systems are very suppressed during sleep, though one can smell within a dream. For the life of me, though, I can't remember the neurological name for this phenomenon.

I think I found a good expression : "sensory incorporation in dreams"
https://www.psychologytoday.com/blog/dream-factory/201409/sensory-incorporation-in-dreams
It doesn't seem reflected in a Google Scholar search however, and I don't find a consistent terminology in the papers that do seem to be about the subject. That article can be a good starting point though.
EDIT: other good one: "influence of external stimuli on dreams".
https://journals.ub.uni-heidelberg.de/index.php/IJoDR/article/view/15754

Thanks, I'm going to accept this one, as I feel like this one answers my revised question the best. The latter article is actually a good one: from it I found a link to a web forum dedicated to everything about dreaming, so I should get further information from the people over there. :)

A classic of the genre of incorporation of sensation occurred in an 1865 dream of psychologist Louis Alfred Maury that S. Freud recounts at p. 21 of the 3rd. edition (1913) in translation, of his "The Interpretation of Dreams".

He {Maury) was sick, and remained in bed; his mother sat beside
  him. He then dreamed of the reign of terror at the time of
  the Revolution. He took part in terrible scenes of murder.
  and finally he himself was summoned before the Tribunal.
  There he saw Robespierre, Marat, Fouquier-Tinville, and a1l
  the sorry heroes of that cruel epoch; he had to give an account
  of himself, and, after all sort of incidents which did not fix
  themselves in his memory. he was sentenced to death. Accompanied
  by an enormous crowd, he was led to the place of
  execution. He mounted the scaffold, the executioner tied him
  to the board, it tipped, and the knife of. the guillotine fell. He
  felt his head severed from the trunk, and awakened in terrible
  anxiety, only to find that the top piece of the bed. had fallen
  down, and had actually struck his cervical vertebra in the
  same manner as the knife of a guillotine.

There is suspicion that the dream report was a backwards reconstruction from the awakening realization by Maury that he had been struck by the bed-board. From REM awakening studies, it is known that dreams take about as long to act out in real time as they appear to in the dream, so it could not be that the fall of the bed-board triggered the dream.
I think such hallucinoid dreams are not little stories, but pithy statements about the dreamers life at the time. If the dream images/scenes are viewed as letter-analogues, designed to elicit words or phrase in the dream report, to know what meaning to apply to those words one would need to know the true context -- what was on the dreamers mind at the time. The only clue we have is that he was sick in bed and his mother was with him!! My guess at the true context of the words in Maury's dream report, as understood by the cipher method, is:

"What a pain in the neck!"

Whether this refers to his illness, or his mother looking after him, or something else, we cannot know at this distance. The board falling on his neck brought the dream to a particular focus. There are many equivalent ways that such frustration can be vented, so if not that idiom, then another would have appeared in the words of the dream report.
Ken Arenson

For my blog on the cipher method in modern, post-REM dream science, see:

dreamstheciphermethod.wordpress.com

Welcome to Biology SE! Could you edit your answer to make the link with the question more explicit? It is not clear to me that it really contains an answer to the OP. Also, be sure to include some reputable references for your claims to avoid downvotes or deletion of your answer.

Sure. The roots are old: Aristotle's "De somno et vigilia" says sleep and wakefulness result from our ability to feel and comprehend the stimuli of our environment.The questioner added to his original q. "I would like to read more about this type of experience".  Maury's dream is considered a classic of the type. Cipher method is also ancient. e.g. see my Blog, 2nd post - Aristandros used cipher method on a dream of Alexander the Great in 322 BCE. See my Blog post 13, Ella Sharpe 1937 "Dream Analysis: A practical handbook for psychoanalysts", gives a modern version named "Poetic Diction".

rolled back edits because they introduced errors (in addition to fixing some things). Generally, please avoid editing quotes, especially when you change the meaning "(after all sorts of incidents)" vs. "after all, sorts of incidents".

My answer is going to be verily based on my experience and thinking, so don't take it for absolute.
When we are dreaming, at the level of the brain, sensual (meaning from senses) experience is being created by projection in the sensitive cortices (visual, auditive, somatic...) from other zones of the brain. In this way the brain is creating a sensitive environment and experience to the self, which, usually unaware that it is a dream, lives through it, making decisions, solving problems, having experiences, remembering and even learning.
In your case, it seems that, while you were dreaming (creating a sensory experience from the "inside"), you were also being sensually stimulated (meaning form the "outside", through a real sensitive organ - the ear). The input from your audition, though not enough to wake you up, still originated the corresponding projections in your auditive cortex, creating the matching experience of hearing the podcast and overlapping it with the experience that was being generated in the dream. This way, the sound of the podcast was incorporated in the experience created in the dream, affecting it in the process.
I tried to explain this in the most biological (neurological) way I could!

Please add some references to your answer.


text:
Why is extracellular measurement of action potentials so different from intracellular?
I had read in a paper that present a low noise amplifier the following:
"...This level of input signal is larger than both typical action potentials (<500μV) and local field potentials (<5 mV). If a larger input signal is expected, the amplifier’s supply voltage can be increased at the expense of higher power consumption.We verified that our neural amplifier works in a real recording environment by using it to record action potentials in the robust nucleus of the arcopallium (RA) of the anesthesized zebra finch. Data were taken with a carbon fiber electrode (Kation Scientific, Inc.) electrode that had an impedance of approximately 800kHz at 1 KHz. A long extracellular trace and a short extracellular trace recorded from our amplifier (normalized by its gain) are shown in Figure 2. They were found to be identical to that recorded by a commercial neural amplifier (A-M Systems, Model 1800)."
Link:

http://www.rle.mit.edu/acbs/pdfpublications/journal_papers/woradorn_tbcas_neural_amp.pdf

Please, can someone help me to understand how we can measure an action potential as shown in figure 2? We know that action potential amplitude is approximately 70mV as shown in figure 1 but figure 2 shows that is approximately 70μV.Is this possible?
Figure 1

Figure 2

I'm going to mostly duplicate my answer to another question Neural signals amplitude since it's exactly the same as this one, but it has no upvotes so I can't vote as duplicate. Once I get an upvote either place I'll vote to close the other.
In the first figure, those voltages refer to the difference between the inside and outside of the cell (i.e., -70mV means the cell is 70mV more negative than the outside).
You can't possibly measure that potential difference from outside of a cell. When you do extracellular recording, like in the second figure, you are measuring spatial differences in ion concentrations that occur due to ions flowing in and out of cells. For example, when a cell fires an action potential, lots of positive ions flow into the cell; this makes the area just around the cell slightly more negative than an area further away. The magnitude of this potential as measured depends greatly on your recording configuration, the type of signal you are recording (i.e., population activity or just a single cell; synaptic currents versus action potentials), how close your electrode is to the signal you are recording, and where your ground is (or position of both of your electrodes if you are doing a bipolar recording).
Also, in this second recording, either the voltage is reversed (i.e., the electrode near the cell is taken as ground), or it is actually measuring return currents in the dendrites of the cell; otherwise, the action potential would be in the opposite polarity (downward first, then upward) compared to inside the cell.
Although it varies, in most cases the signals you record extracellularly are on the order of microvolts to a couple of volts.
Lastly, in the quote you reference, the line before it was:

The total harmonic distortion (THD) of our amplifier stays
  below 1% for input signals smaller than 7.3 mV peak-to-peak.

That article is describing an amplifier system for recording extracellularly (potentially for a brain-machine interface). They are saying that one type of distorting noise is not a problem in their amplifier at the input voltages you would expect in an extracellular recording of spikes or local field potentials, which indeed would usually be less than 5 mV. This amplifier would not be suitable for recording intracellularly.

Thank you so much mr Bryan Krause for your response. Sorry for my comment but I would to understand one point.You refer that "That article is describing an amplifier system for recording extracellularly "and also "This amplifier would not be suitable for recording intracellularly."Can you help me to understand the difference when amplifier records intracellularly compared with extracellularly ?What changes in neural signals that record? Maybe the difference is the place of implant in brain?Is any of the recording methods better? Thank you in advance.

Read about whole-cell patch clamp (though there are a couple other methods for recording intracellularly). Intracellular recordings are necessary to measure the magnitude of inputs to individual cells. Extracellular recordings can measure outputs from single or multiple cells, and/or field potentials that approximate inputs to populations of cells. It isn't fair to say one is better than the other: they are different, for different purposes.

For long-term recordings (over weeks and months), only extracellular recordings are currently technologically feasible.

Thank you so much, Mr Bryan Krause. I search for this answer for days!

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text:
Why don't mosquitoes target the visible blood vessels under the skin?
We can see numerous veins under our skin. Why don't mosquitoes suck blood from those vessels?
Why don't they use better option?

This is unclear. Where do you think mosquitos get their blood from?

they suck only plane skin but not the skin which is elevated by large vessels underneath it. Large vessels will definitely provide more blood.

Mosquitos suck blood from small capillaries. And they don't suck very much, only about 5 µl.

Why not from large vessels?

large blood vessels have more pressure so in less time mosquito can suck the required amount of blood and would also require less energy, since blood will ooze out unlike capillaries where the mosquito might have to suck actively.

The smart mosquitoes that have been through a phlebotomy course do go after the large veins closest to the surface. However, at times, they mistake an artery for a vein, and blow themselves up. It's a nasty affair. Most mosquitoes who've witnessed this just stick with dermal capillaries.

@anongoodnurse What a sense of humour!

@anongoodnurse how do these mosquito pass on this information to next generation and the other mosquitoes of existing generation?( just for humour)

Related: https://pbs.twimg.com/media/BF_Ua1xCAAAKMYf.jpg :)

Perhaps for the same reason that you can drink from a drinking fountain, but not a fire hose :-)

I don't know where you live, but whenever a mosquito bites me, it's almost always happens at a visible vein. Even if it doesn't seem to be so at first glance.

For a mosquito, there is really no benefit to targeting those visible blood vessels. Mosquitoes take only a small amount of blood, and their proboscis is going to be a limiting factor anyways.
However, mosquitoes also aren't just blinding sticking their proboscis into the extracellular space. They actually do target individual vessels, and scientists have actually been able to video the process. Capillaries are good targets because they are found in all the tissues, so the mosquito doesn't need to find a surface vein.
See the videos with the original paper here: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0050464 (in the "Supporting information" section)
There are also versions on YouTube, like here:
https://www.youtube.com/watch?v=MbXSPacvuak
Choumet, V., Attout, T., Chartier, L., Khun, H., Sautereau, J., Robbe-Vincent, A., ... & Bain, O. (2012). Visualizing non infectious and infectious Anopheles gambiae blood feedings in naive and saliva-immunized mice. PLoS One, 7(12), e50464.

In the video , the mosquito is squeezing blood from capillaries so hard that capillary is collapsed, then why do you think that proboscis is a limiting factor?

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text:
Are the y-axis values informative when performing biolayer interferometry?
I am currently reading  an this article by Alexandra C. Walls et. al.
I would like to ask a question about a graph that is being used in the article and I wanted to know if my analysis was correct.

I was wondering if for the Binding Response versus Time graphs of SARS-CoV-2 (panel A), and SARS-CoV-1 (panel B), can we infer that SARS-CoV-2 was more adept at binding to the human ACE2 because the y-axis has larger numbers than for SARS-CoV-1? If not, why not?

@EnlightenedFunky You cannot assume that a particular user downvoted you. Votes are anonymous and there is basically no obligation for a voter to explain their vote. However, I can understand that it is can be annoying as well as discouraging but it's better to ignore it for your own happiness.

I've tried to clarify what your question is about this figure, and to use an informative question title that makes clear what type of question this is. Please feel free to edit if you think these changes did not capture what you were after.

From the linked article:

We found that hACE2 bound to SARS-CoV-2 SB and SARS-CoV SB with respective equilibrium dissociation constants of 1.2 nM (Figure 2A) and 5.0 nM (Figure 2B).

An equilibrium dissociation constant (commonly called Kd) represents the propensity of a complex to dissociate into its constituent pieces.  A smaller value represents a smaller propensity to break apart, i.e. a stronger interaction.
So, yes, considering only the data presented, domain B from the SARS-CoV-2 spike protein shows a slightly higher affinity for hACE2 than the equivalent domain from SARS-CoV.  Note, however, that the authors are careful with their wording, and state in multiple places that the relative affinities of the homologous domains are comparable.

The SARS-CoV-2 SB engages human ACE2 (hACE2) with comparable affinity to SARS-CoV SB from viral isolates associated with the 2002–2003 epidemic (i.e., binding with high affinity to hACE2).

What's more telling are the binding constants (kon and koff) given in Table 1:

$$\begin{array}{c|c|c|}
\text{} & \text{SARS-CoV-2 S}^{B} & \text{SARS-CoV S}^{B} \\ \hline
\text{K}_{D} \text{ (nM)} & 1.2 ± 0.1 & 5.0 ± 0.1 \\ \hline
\text{k}_{on} \text{ (M}^{-1} \text{s}^{-1}\text{)} & 1.4 × 10^5  (2.3 ± 1.4 × 10^5) & 1.4 × 10^5  (1.7 ± 0.7 × 10^5) \\ \hline
\text{k}_{off} \text{(s}^{-1}\text{)} & 1.6 × 10^{−4}  (1.7 ± 0.8 × 10^{−4}) & 7.1 × 10^{−4} (8.7 ± 5.1 × 10^{−4}) \\ \hline
\end{array}$$
Values reported represent the global fit to the data shown in Figures 2A and 2B and the averages obtained from five (SARS-CoV-2) or four (SARS-CoV) replicates carried out with different protein preparations are shown in parentheses.

Note that Kd is the reciprocal of the association constant, Ka, which is equal to the ratio of the binding constants.
$K_{a} = \frac{k_{on}}{k_{off}}$, $K_{d} = \frac{k_{off}}{k_{on}}$
Since the values given for kon derived from the global fit are the same for SARS-CoV-2 and SARS-CoV, the observed difference in Kd is due to the different values of koff.  So, at equilibrium, SARS-CoV-2 SB and SARS-CoV SB will associate with hACE2 at the same rate, though SARS-CoV SB dissociates faster.

Can you explain how the y-axis values relate to Kd? I'm not sure this answer is correct based on what you've written here (you've explained what is written in the text, but not the figure). I'm also not particularly familiar with this technique, but I'm assuming the Kds come from a parametric fit to some aspect of the curves displayed and would depend on the spacing at different concentrations rather than the Y-axis.

@BryanKrause I understand and agree with your concern. The problem I've encountered in trying to better understand how binding kinetics are derived from the raw Δλ is that the software associated with biolayer interferometry appears to be proprietary.  All the "guides" and literature I find give the sequence of operations in the software GUI without stating what those operations do.  I'll update my answer if and when I find better resources.

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text:
Could p-loop bind fully protonated ATP?
The phosphate tail of ATP binds the p-loop motif, evolutionary conserved, going back to since forever. In the dominant model, the deprotonated hydroxyl groups are complexed with Mg2+, at least two of them.
I was wondering about a hypothetical model (could consider it "fantasy" or just thought experiment, without disclosing if there is any actual credible reason to think about it. )
If the three deprotonated hydroxyl groups were actually protonated, is there still a fit in the p-loop? This would remove the Mg2+, since it is substituted by H+, charge-wise.
That ATP does not actually get protonated like that in the dominant models, is neglected in the question. I am just wondering about fit in the p-loop. To have a way to think of that, imagine the ATP might be slightly modified, or some other input altered, but the p-loop itself is the same, and the phosphate tail except here it is fully protonated.

I’m voting to close this question because it assumes a chemical impossibility, and therefore, as well as having no relevance to biology, it is impossible to answer.

A really simple answer is that hydrogen bonds are stronger when the hydroxyl groups on the phosphates are deprotonated, because hydrogen bonds are like a competition for a proton, but, hydrogen bonds form between hydroxyl groups even when one is not deprotonated.

This gets a bit more interesting if a few facts are considered. The deprotonated group has, relatively speaking, less negative charge. Otherwise, it would be able to hold onto the proton just as well. And since the hydrogen bond acceptor is the group with most negative charge, the deprotonated one would only be favoured because it lacks the proton, not because is has less negative charge in itself. This is a fact but it does not in itself say much. But consider the following.
In a "lock and key" setting with a specific type of fit, the deprotonated group might actually be the hydrogen bond donor. This is very counter-intuitive, but, it relies on the groups being forced close to each other to start with. Then, the combined negative charge of the groups, will actually protonate the deprotonated group, and it will be the donor to the more negatively charged other group. It is a fact that, with added negative charge, the ability to attract a proton increases. And hydrogen bonds rely on physical closeness.
So, the p-loop/ATP complex is acting like a base, using a lock-in-key fit for... protons.


text:
What is the signal that indicates which neurons Schwann cells should myelinate versus which should remain unmyelinated?
Schwann cells are neuroglial cells that produce myelin in the peripheral nervous system.
However, not all axons are myelinated - some will remain unmyelinated.
There must be some signal that indicates which cells are to be myelinated - what is it?

Are you asking what the signal is that makes some neurons remain un-myelinated? "Unable to form" seems to imply that they should be myelinated but somehow fail to be, rather than that some should be myelinated and others should not. Or are you asking why myelination is not necessary for all neurons?

I m asking that why schwann cells donot form myelin sheath around axon in non myelinated neurons?

Are you asking what the signal is that makes some neurons remain un-myelinated, or are you asking why myelination is not necessary for all neurons?

Yes I m asking what the signal is that makes some neurons unmyelinated?


text:
Odd bugs in terrarium. Harmful?
I noticed these bugs in my terrarium, there is a springtail in the photo for size reference.
I've seen 3 or 4 so far, I'm worried about it out-competing my springtails or possibly being a parasite that will spread to other tanks.  It is shaped like a tick. It's really hard to see but I think it has 6 legs and 2 antennas.
I live in Central Illinois.
I have an African Bullfrog who I occasionally feed live mice, but he is on the other side of the room.
I was thinking that it was probably a mite of some sort. According to an article by the IDPH, the only pest mite in Illinois would be the Clover Mite.  It doesn't look like a Clover Mite, but it does look similar to a predatory mite, like the Amblyseius Cucumeris.

Shaped like a tick; it'll be a mite (also in the Acari with ticks). Which mite would take microscopic examination, unless it were the red velvet mite, which are quite obviously red usually.

Do you have birds or rodents in or nearby the terrarium? Even perhaps outside a nearby window?

@theforestecologist: I have an African Bullfrog who I occasionally feed live mice, but he is on the other side of the room. To bob1: I was also thinking that it was probably a mite of some sort. According to an [article] (https://dph.illinois.gov/topics-services/environmental-health-protection/structural-pest-control/occasional-invaders.html) by the IDPH, the only pest mite in Illinois would be the Clover Mite. It doesn't look like a Clover Mite, but it does look similar to a predatory mite, like the Amblyseius Cucumeris.

Welcome to the site; in the SE model, the answer box is only for answers, this isn't a "forum" site where posts make a long chain from oldest-to-newest or vice-versa. The best way to respond to comments asking for clarification is to [edit] your post to include it.

It's definitely a mite. My questions were trying to determine if it was a bird mite or related. Without better picture and more info, it's unlikely you'll get an accurate and more precise answer


text:
How many times has SARS-CoV-2 mutated?
According to
Coronavirus has mutated at least once

The novel coronavirus that has infected thousands of people across the
  world may have mutated at least once — meaning there may be two
  different types of the virus causing illnesses, a new study conducted
  by Chinese scientists suggests.
Scientists with Peking University’s School of Life Sciences and the
  Institut Pasteur of Shanghai in a preliminary study found that one
  strain — type “L” —  of the virus was more aggressive and accounted
  for about 70 percent of the strains analyzed. The second — type “S” —
  was less aggressive and accounted for about 30 percent of analyzed
  strains.

But also several webpages theorized the virus has mutated before passing from animals to humans.
This page What we know about the Wuhan virus says

This virus belongs to a family of viruses known as coronaviruses.
  Named for the crown-like spikes on their surfaces, they infect mostly
  bats, pigs and small mammals. But they mutate easily and can jump from
  animals to humans

and

Where did the new coronavirus come from? The new virus likely came
  originally from bats, scientists say. It isn’t known exactly where or
  how it jumped to humans, though. Viruses from bats often infect
  another mammal first and then mutate to become more transmissible to
  humans.

though

Coronaviruses can also jump directly to humans, without mutating or
  passing through an intermediate species.

Is something more known about this? Is it possible the virus has mutated twice in a period of time of months?

How many times has the virus mutated? As many times as it has replicated in a host. Viruses mutate every generation. Most of these mutations are "neutral" in the sense that they do not confer new evolutionary advantages or disadvantages. They likely do not even give a different phenotype. But they are mutations nonetheless.

This coronavirus is a RNA and tries to replicates lots of times with lots of bad replications. Is it any wonder that some successes are  mutations?

Can we please start calling it Covid-19 instead of corona? Corona is a family. SARS, MERS, Covid, all coronas. Questions like this are going to be a pain with the next outbreak in a few years.

@Mast I'm not sure it will be too much of a problem in the future. The media have locked onto this being called "Corona" and so I think it probably is appropriate to use "Corana" as this allows the majority of people to immediately know what is being discussed. Using "Covid-19" as well wouldn't hurt though.  And if a new outbreak occurs in the future the media may well call it "Corona" again or they may  latch onto a new term for the new outbreak.

@Mast If you want to be technical, the name of the virus is SARS-CoV-2; COVID-19 is the name of the disease caused by that virus.

@Charles Fine with me, as long as we stop with the corona-this, corona-that.

Unfortunately, the answer is "too many times."

This question makes a number of incorrect assumptions and I don't have time to correct them. The short answer is that the virus has mutated probably hundreds of times since it entered humans in late 2019.
The lower figure on the NextStrain.org ncov page, "Diversity", shows the known mutations that have been identified so far. As I look at it now, there are maybe 100-200 shown there, but that will change daily and I can't be bothered to count them.
Is it possible the virus has mutated twice in a period of time of months? Of course it is. That's what we expect from coronaviruses. It would be shocking if it did not.
The default assumption (based on a vast amount of experience with coronaviruses and many other viruses) is that these mutations are neutral and do not affect the virus in terms of fitness, virulence, or transmissibility in any way; they are occasionally useful in tracking sources, but unless you have spent a lot of time looking at virus phylogenetic trees for several years, your interpretations of these mutations are almost certainly wrong.
An example of people making claims based on unfamiliarity with virus evolution is the "two different types of the virus" claim. That claim is addressed by MacLean and colleagues in their Response to “On the origin and continuing evolution of SARS-CoV-2”. Summary:

Two of the key claims made by this paper appear to have been reached by misunderstanding and over-interpretation of the SARS-CoV-2 data, with an additional analysis suffering from methodological limitations

MacLean et al.'s "Response" to Tang et al.'s paper gives this stronger summary: "Given these flaws, we believe that Tang et al. should retract their paper, as the claims made in it are clearly unfounded and risk spreading dangerous misinformation at a crucial time in the outbreak."

The default assumption as described here The default assumption (based on a vast amount of experience with coronaviruses and many other viruses) is that these mutations are neutral and do not affect the virus in terms of fitness, virulence, or transmissibility in any way has been proven wrong at least three times by SARS-CoV-2: The mutation D614G, the Alpha variant, and the Delta variant came with significantly improved fitness and show an ongoing adaption to the new human host of the virus.

I don't think you understand what "default assumption" means.

I added this as a caveat for the readers. And probably in the case of a zoonotic virus hitting mankind rather recently, this default assumption is profoundly wrong, as the virus is still in the process of adaption to its new host. At least, the huge increases in transmissibility have caught leading virologists such as C. Drosten as bad surprises.


text:
Can we say that the better memory relation with pupil dilation is connected to sympathetic nervous system?
A research at Arlington       University, United states says that students with high performance and better memory are observed with their pupil dilated
https://www.uta.edu/news/news-releases/2024/04/22/eye-opener-pupils-enlarge-when-people-focus-on-tasks
Can we say that this all is occurring due to activation of sympathetic nervous system which releases  adrenaline and nor adrenaline from nerves
And according to this site:
"Sympathetic Nervous System - an overview | ScienceDirect Topics" https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/sympathetic-nervous-system
A complex mechanism is activated in brain which also includes amyglada (from limbic system) and it leads to storage of memories
I am just trying to decode it so that could be or not the mechanism?

I would say what is accurate in this context is that pupil dilation is being used as a marker of sympathetic activation. Here's a review article about autonomic control of the pupil:
McDougal, D. H., & Gamlin, P. D. (2015). Autonomic control of the eye. Comprehensive physiology, 5(1), 439.
The specific mechanism for the association with memory is not being tested in this study, it's only a correlative result.

“Can we say that this is occurring due to activation of sympathetic nervous system which releases adrenaline and noradrenaline from nerves?”
Of course not!
All one has is an external observation. One can formulate various hypotheses as to the mechanism responsible, but the essence of scientific logic is that the hypotheses need testing by experiments that address them directly.


text:
Is the axon part of a Schwann cell or no?
Whenever I see diagrams of a neuron, it always shows the Shwann cells around the axon, but it doesn't seem as though anything distinguishes whether the axon is a component of the Schwann cells or not, or whether it's a component of the cell body itself (whatever that's called).

Your question isn't very clear, I think you have a bit of confusion in your use of terminology.
The axon is a part of a neuron, it's membrane is continuous with that of the cell body (also referred to as the 'soma'). Schwann cells are not neurons, they are a type of glial cell found in the peripheral nervous system. Schwann cells wrap their membrane around the outside of the axon to insulate it; this process or the presence of this insulation is called "myelination" and allows for faster transmission via saltatory conduction.
Cells that provide a similar function in the brain and spinal cord are called oligodendrocytes.

I think the fact that you just answered my question in detail proves it was clear enough. I asked if the axon is part of the Schwann cell, you clearly indicated "no" by explaining that the Schwann cell merely wraps around it and that the axon itself is an extension of the neuron. But despite that misunderstanding, thank you.


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What is the mechanism of aspirin as an anticoagulant?
I understand that aspirin prevents blood clots from forming by interfering with the clotting action. I want to know at which stage aspirin interferes with clot forming and what really happens in the process. I've used google to understand this but did not find a satisfactory answer.
For example, here I found:

How can aspirin prevent a heart attack?
Aspirin interferes with your blood's clotting action. When you bleed, your blood's clotting cells, called platelets, build up at the site of your wound. The platelets help form a plug that seals the opening in your blood vessel to stop bleeding.

But this clotting can also happen within the vessels that supply your heart with blood. If your blood vessels are already narrowed from atherosclerosis — the buildup of fatty deposits in your arteries — a fatty deposit in your vessel lining can burst.

Then, a blood clot can quickly form and block the artery. This prevents blood flow to the heart and causes a heart attack. Aspirin therapy reduces the clumping action of platelets — possibly preventing a heart attack.

Every site I visited had descriptions like this (mostly concentrated on the medicinal side). I want to know what aspirin does that prevents blood clotting at the chemical level, which I haven't been able to find.

I found another question and answer here that already seems to answer your question, so I've marked it as a duplicate. There's no penalty for a duplicate question, it will help people who see your question first in search find the answer they want and helps us keep things orderly.

thank you very much. stay safe


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What is the maximum altitude where humans can survive?
What is the highest altitude that a human can survive without being pressurized?  Let's assume that oxygen and heat/insulation are not the limiting factors?
Why I asked.

An interesting question. If you've done any of your own research into this could you share it. I wouldn't want to see this question get closed for "homework" reasons.

The sequence in which the surviving crewman in 2001: A Space Odyssey space-walks from the pod to the airlock of the spaceship, manually opening the outside door, entering, closing the door, and pressurizing the airlock raised the question: Is it possible?
The answer was: Yes, barely. A few more seconds and the character, if actually experiencing the transfer as acted, would have lost consciousness.

Air pressure drops by half for each three miles of altitude.

Short answer
Between 62,000 and 63,500 feet (18,900 and 19,350 meters) blood begins to boil at body temperature. This altitude, referred to as the Armstrong limit, is generally considered to be the absolute limit compatible with life. At this point, humans cannot survive without pressurization measures.
Background
Atmospheric pressure drops at higher altitudes. As you go higher into the atmosphere, gases start to expand due to the lower atmospheric pressure. This is what causes your ears to pop when driving up in the mountains or when an airjet lifts off. At altitudes higher than 10,000 feet (3.5 km) people unaccustomed to the reduced atmospheric pressure may become short of breath or experience dizziness. At altitudes above 20,000 ft (6.1 km) supplemental oxygen is required to support life and at 34,000 ft (10.4 km), 100% oxygen is necessary to equal the partial pressure of oxygen in sea level air. Above 40,000 ft (12.2 km), 100% oxygen must be administered pressurized (NASA).
Altitudes above 50,000 ft (15.2 km) are considered near-space and man requires a pressurized suit to be safe. At 55,000 ft (16.8 km), atmospheric pressure is so low that water vapor in the body starts to boil at ambient temperatures, causing the skin to inflate. At 63,000 ft (19.2 km) blood at normal body temperature (98 F / 37oC) starts to boil. At altitudes above 65,000 ft atmospheric pressure approaches that of space, i.e., a vacuum (NASA).
Between 62,000 and 63,500 ft (18.9 - 19.4 km), blood at body temperature (37oC) begins to boil. This is the point beyond which humans absolutely cannot survive in an unpressurized environment. This point is named the Armstrong limit, after Harry George Armstrong, who founded the U.S. Air Force’s Department of Space Medicine in 1947. On Earth, the Armstrong limit is somewhere between 62,000 and 63,500 feet (18.9 and 19,4 km), or about 12 miles.
As a reference, the highest point on earth is the peak of the Mt. Everest at 29,000 ft (8,8 km).
Above the Armstrong limit, water in the soft tissues of your body vaporizes, causing gross swelling, though the tight seal of your skin would prevent you from actually bursting apart. Your eyes, likewise, would refrain from exploding, but continued escape of gas and water vapor leads to rapid cooling of the mouth and airways (Goslin, 2008).
Water and dissolved gas in the blood forms bubbles in the major veins, which travel throughout the circulatory system and block blood flow. After about one minute circulation effectively stops. The lack of oxygen to the brain renders you unconscious in less than 15 seconds, eventually killing you. When the pressure gets very low there is just not enough oxygen, which is thought to be the first and most important concern (Goslin, 2008).
Note that under conditions of near-vacuum, death is not instantaneous. At one three-hundred-eightieth of atmospheric pressure at sea level, dogs were shown to survive up to 90 seconds. During their exposure they weren't in a great state (the dogs were bloated, ice covered their tongue, and many more horrible facts to be read in (Goslin, 2008)). Monkeys were even shown to cope for 3.5 minutes under these conditions.
Reference
- Goslin, Sci Am February 2008

Excellent answer, comprehensive and well-sourced.


text:
Jungle blindness?
Can people who live in green scenic areas like a jungle be more exposed to green light causing them to not be able to perceive green light as well as someone who may live in a desert void of color? Similar to snow blindness can strong color also blind a person to a spectrum of light but over a longer period of time?

Photokeratitis (snow blindness) is essentially a sunburn of the eye — it is caused by UV damage to the cornea.
Green wavelengths (no matter how vivid they might seem) don't have the same energy as UV wavelengths and are thus cannot cause the same kind of damage. (Which is not to say that you couldn't be blinded by a green laser, but that isn't a "natural" phenomenon.)
In addition, the amount of UV reflected from plants is typically very low:

Generally, 85–95% of the UV-B radiation is absorbed by the leaf1.

This suggests that any sort of jungle blindness one might experience is highly unlikely to be related to what happens in photokeratitis — especially since any given photon will likely have been transmitted through and/or reflected by one or more leaves in any dense plant community.
I can't rule out some sort of psychological effect, but I have seen no evidence of that either in the literature or anecdotally.
Reference:
1: Suchar, V. A., & Robberecht, R. (2015). Integration and scaling of UV‐B radiation effects on plants: from DNA to leaf. Ecology and evolution, 5(13), 2544-2555.


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Self Grown Organs
Could a viable organ be partially grown in a test tube then be hooked up to the host in some way until it is large enough to swap it with the bad organ?
For example: Could a smaller replacement heart have a tiny pacemaker to keep a separate heart rhythm and grown in a different part of the body cavity like the appendix?
Then when the organ is mature, remove the organ from the appendix and then transplant to another person or on oneself?

Speculative questions like this are not good for Biology.SE; unfortunately, because of the bounty I cannot currently vote to close.

I don't understand your comment.

@BryanKrause I noticed that you have to wait 2 days before a bounty can be placed. If a question goes unnoticed it could be locked in by a bounty. If the time limit is extended the bad question could be closed with less rush.

I don't think questions are closed with rush, they should be closed quickly, and also it is important to note that questions that are voted to be closed are initially put on hold; they have several days to be improved and brought back if the improvements solve the problems that led to close votes. However, this is a discussion for Meta.

While the specific hypothesis on potential implementation (given as example) is very speculative, it is not needed to answer the core question.

Could a viable organ be partially grown in a test tube then be hooked up to the host in some way until it is large enough to swap it with the bad organ?

Yes. This conceptual possibility already is a reality for one organ, namely the skin.
For an example see the following story in a good scientific journal: https://www.sciencemag.org/news/2017/11/boy-rare-disease-gets-new-skin-thanks-gene-corrected-stem-cells
Unfortunately this doesn’t yet mean that conceptually homologous procedures could already be performed for most organs.


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Why do living things go belly up as they die?
I have seen birds, lizards, frogs, fish, etc in various places on their back dead. May be insecticides cause them to flip over but I do not believe every upside down creature died by poison as stated in this question's answer: Why do cockroaches flip over when they die? and the roach question only covers roaches and insecticides. My question covers all animals not affected by poison that are belly up.
Other than poisoning is there any other reasons like DNA programming on behavior or muscle spasms that cause this?

Related: https://biology.stackexchange.com/questions/64333/if-an-insect-becomes-upside-down-do-they-have-mechanisms-to-turn-themselves-rig

@Muze This is just speculaion but it could also be partly due to confirmation bias. I've seen a lot of dead ladybirds on their front - even if organisms have a 50/50 chance of facing up or down, you might notice the upside down ones more, since its what you're looking out for. A lot of insects might simply be blown over onto their backs when dead. But also, some organisms could be flipped over by a predator, if the predator finds it easier to eat the organism from its underside (e.g. if there is a thinner shell around the organism's belly).

Possible duplicate of Why do cockroaches flip over when they die?

@Muze I did, and I still think the questions are the same. Others are free to disagree with me. That's how it works.

@kmm you are correct.

Can you back up the claim that "living things go belly up as they die"? I've been dead animals in other positions as well... Otherwise, this is just an unfounded/anecdotal claim.

@fileunderwater that is why I'm asking, but if you want I can find pictures online of animals dead on there back.

limbs are light weight compared to bodies, if you knock an animal around (and it has no active correction AKA is not alive) it will tend to end up on its back just due to where its center of gravity is.


text:
What is a lethal dose of THC?
With the oil form of THC being stronger then ever. What would happen if one was to take a stomach full of THC oil?

According to the abstract from this paper, the intragastric LD50 of $\Delta^9THC$ (tetrahydrocannabinol) in sesame oil using Fischer rats was 1270 mg/kg. Assuming rats and humans are identical (they're not), for an average-sized adult human weighing 70 kg (~155 lb.), the median lethal dose would be 88.9 grams, or about 3.1 oz.
Keep in mind that's 3.1 oz. of pure THC. That's a lot of weed.


text:
Where does the human brain drain to?
When a brain has a aneurysm and the patient survives untreated then   where does that blood drain to or how is it absorbed? How is the pain perceived?

if you mean the pain in brain during the operation, It doesnt, because there is no nocireceptors in brain. I actually doubt about the aneyrysm survivel without threatmeant, and i hope someone is going to answer that part soon.


text:
Can a person survive on blood in place of water?
This question: Can you get enough water by eating only fish? asks if a person could survive on fish alone. Can a person survive on fish and/ or blood alone of any species if stuck at sea or animal blood as a last resort where there is no water or fire?
Obviously if it was a fresh water fish there is water, but there are fresh water mud skippers that can breathe air and the water to tainted to drink in that case a fresh water fish blood maybe safer than the water. https://chemistry.stackexchange.com/questions/115901/what-can-i-eat-that-will-help-metabolize-blood
Desalination would be the best way to process the blood but this is in emergency situation scenario.
From @PTwr Comment's Link: If you drink blood regularly, over a long period of time the buildup of iron in your system can cause iron overload. This syndrome, which sometimes affects people who have repeated blood transfusions, is one of the few conditions for which the correct treatment is bloodletting. https://what-if.xkcd.com/98/

What level of processing is allowed?

Obligatory XKCD reference.

@PTwr good find . I have included some of it into the question. Thanks

Note fish blood contains a lot less hemoglobin. some fish lack it entirely.

You'd have no problem substituting blood for water, provided:

You allowed it to coagulate first, and
You prevented it from evaporating

Fresh blood has a high concentration of protein, certainly, but it's not a homogeneous fluid.  If you decanted the blood into a container and let it sit, it would soon coagulate, causing the majority of the cellular and protein components to precipitate and stratify.
The plasma fraction (approximately 55% in healthy mammals, and not radically different in most species with hemoglobin) forms a supernatant (the top, easily accessible layer) which is 95% pure water by volume and about 5% protein.
The sodium salt concentration of plasma is about 140 mEq/L, or 3.2 g per L (mEq = mg / atomic weight * valence, Online Calculator).  Since healthy kidneys can concentrate salt to 4-5X osmolality (and since the source material is physiologic blood), you'd have no problem drinking the top, liquid portion.  You would also avoid most of the long term iron issues as the hemoglobin is found in the erythrocyte (deposited) fraction.
Thirsty vampires will be disappointed that plasma appears amber, not "blood red"

@Jan, total osmolality for blood plasma is 275-300 mOsm/kg - see https://www.sciencedirect.com/topics/medicine-and-dentistry/plasma-osmolality for a reference.  This encompasses salts, glucose and soluble proteins.

@Jan, not clear what you mean by net water.  If you take a 1 L blood volume, 55% of that (the plasma) is 550 mL.  Is that what you mean?

@Jan - I'm not sure the back and forth is helpful, but I think you're missing that the kidneys serve to actively concentrate fluid.  Remember, your kidneys are actively concentrating your entire blood plasma volume about 60 times per day (which just like the orally consumed plasma is about 300 mOsm/L).  Kidney input is 300 mOsm/L, and output can go to 1500 mOsm/L.  For example, the original WHO Oral Rehydration Solution was 311 mOsm/L WHO ORS and rehydrates.  Also the "protein" in plasma is predominantly urea already.

@Kvohte, urea needs to be removed from the blood by urine. Consumption of 25 g protein (5% of protein in 500 mL of plasma) will result in 25 x 8 = 200 mL of urine, because 1 gram of protein results in the amount of urea that needs 8 mL of water to be excreted  ( nap.edu/read/10925/chapter/6#135 ). This means that by drinking 500 mL of water from plasma, you get only 300 mL of net water because the urea will force 200 mL of it out into the urine. Do you agree with this? So, plasma would be still hydrating, but not as much as it seems. I need to think about sodium effect a bit more.

Blood is not a good source of water.
1 liter of blood contains about 800 mL of water, 170 grams of protein and 2 grams of sodium (calculated from the composition of lamb blood).
When metabolized, 170 grams of protein yields the amount of urea that requires 1,360 mL of water to be excreted in urine (calculated from here); 2 grams of sodium requires about 140 mL of water to be excreted (from here).
This means that drinking 1 liter of blood, which contains 800 mL of water, will result in 1,500 mL of water loss through the kidneys, which will leave you with 700 mL of negative water balance.
Fish blood can contain less protein, for example, trout (check Table 1) contains about 120 g of protein (plasma protein + hemoglobin) per liter of blood. Using the same calculation as above (1 g protein results in the excretion of 8 mL of urine), drinking of 1 liter of trout blood, which contains about 880 mL of water, will result in 960 mL of urine, so in 80 mL of negative water balance.
Turtle blood can contain about 80 g of protein (plasma protein + hemoglobin) and 3.4 g of sodium per liter. Drinking 1 liter of turtle blood, which contains about 920 mL of water, will result in 80 x 8 mL = 640 mL loss of urine due to protein, and ~240 mL due to sodium, which is 880 mL of urine in total. This leaves you with 40 mL of positive water balance (to get 2 liters of water per day you would need to drink 50 liters of turtle blood, which isn't realistic.
In various stories (The Atlantic, The Diplomat, The Telegraph), according to which people have survived by drinking turtle blood, they have also drunk rainwater, so we can't conclude it was turtle blood that helped them. I'm not aware of any story that would provide a convincing evidence that the blood of turtle or any other animal is hydrating.

I think this answer addresses the main reasons. The iron issue may be a long term problem but most single foods will cause long term problems if one tries to feed on them exclusivley.

Assuming a sufficient supply, could you drink a lot of blood and eventually get to a point where the protein is no longer metabolized?

Normally, protein does not accumulate in your body, so it is metabolized even if you consume it in excess. Excessive protein is mainly converted to body fat.

Wouldn't a dehydrated body stop even picking up the protein from the small intestine and only absorb water? (just a guess) This also doesn't get rid of the sodium problem, but that is not so severe..

Protein absorption would stop only in severe dehydration. As long the water is absorbed, the protein will likely be absorbed too.

Question revised.

Blood of what, not all blood is the same. fish blood can vary quite a lot in protein composition.however it is true that all the reported cases of drinking fish blood for survival also included capturing rain water, fish blood being used to stretch water not as a complete replacement.

You can drink blood of course to a minimalistic amount (eg- a few teaspoons ) and also if blood is free from pathogens. But it should always be in very small amounts and from suitable donor. Here's why

The strange fact is, blood, when drank, is toxic. When confined to places where blood is supposed to be — such as the heart, vessels, and so on — it is essential for life. But when ingested it's a very different story.

Now why is it even harmful?

Haemochromatosis- this is a disease where your body has excess iron/ iron overdose which gets deposited in organs such as heart, liver , pancreas etc. This happens because blood is very much rich in iron but our body doesn't have any suitable mechanism to excrete the excess iron.
(There is some doubt with the actual cause of Haemochromatosis. It is a disease related to iron overdose but its not sure whether the main cause is genetic or it can be anything related to diet as well.)
Blood related disorders, eg :- AIDS, Hepatitis B etc - If blood is not taken from a suitable donor or the equipments you use to take it in are not sterilised properly, you'll probably contract one of these disorders, which are absolutely life threatening.
Malnutrition- Although blood contains 93% proteins and 1% carbs , blood is terribly low in minerals and vitamins.

So basically blood taken in small amounts will have no harm on you, but you surely can't survive on blood.
For the sources, visit - https://www.livescience.com/15899-drinking-blood-safe.html
https://www.sciencefocus.com/the-human-body/could-i-live-as-a-vampire-by-just-drinking-blood/
https://medicalxpress.com/news/2018-04-bad-blood.html

Could you please cite your references? Who made the  statement you're quoting?

@Arsak This whole answer has been taken from multiple sources, but the one i quoted is from https://www.livescience.com/15899-drinking-blood-safe.html

You should add this and the other sources to your post. It would surely improve your answer.

@Arsak thankyou so much for the suggestion, I have added the sources.

Haemochromatosis is a genetic disorder found in those of European descent, and common among those with Irish descent. It has nothing to do with drinking blood, but involves a variant chemistry for white blood cells.

@PieterGeerkens Please check out this link https://www.livescience.com/15899-drinking-blood-safe.html  I also checked onto this, and the defination is coming the same you are referring to. But maybe there are two sides to this, or maybe I am wrong. Anyways, please check onto this link and let me know about what's right.

@Ishi: The author is a writer and editor, not a scientist: "Benjamin Radford is deputy editor of Skeptical Inquirer science magazine and author of six books including Scientific Paranormal Investigation: How to Solve Unexplained Mysteries." Absence actual scientific evidence, this article is not worth the paper it was written on.

@PieterGeerkens thankyou so much for giving me the correct information, I'll immediately remove it from the answer as I don't want any ambiguity in the OP's mind.

@PieterGeerkens I'm pretty sure haemochromatosis is too much iron, regardless of the cause.  The genetic disorder is just the common cause, but it's still called haemochromatosis if it's dietary.

@JMac: Haemochromatosis is specifically too much ferritin, a particular iron compound used by the body to dispose of iron. This disposition is done through elimination of the white blood cells that create ferritin. Thinking that haemochromatosis is too much iron kills people - like my dad, whose physician refused to listen to experts such as Paul Adams: Honorary Fellowship for Distinction - Royal College of Physicians of Ireland 2013. You are thinking of iron overload, the generic syndrome.

@PieterGeerkens It seems like the definitions are themselves highly inconsistent.  Some places refer to hereditary haemochromatosis as just haemochromatosis, where you will find other sources which consider iron overload to be a form of haemochromatosis that is non-hereditary.

It's very difficult to be infected by HIV orally.

#2 and #3 don't seem particularly relevant. Yes, you can contract blood-borne diseases by drinking blood, but you can also contract water-borne diseases by drinking water. The fact that some blood is infected with disease doesn't make it an unsuitable replacement for water. And water contains no vitamins, and single-digit %DV of many minerals, depending on the source - I don't see how you could become malnourished by replacing part of your diet that has marginal nutritional value to begin with.

@PieterGeerkens Seems like they're not much of an editor, either, saying "when drank" rather than "when drunk".

@forest And usually more fun than drinking blood. Well. Depends on one's inclinations, I suppose.

sorry to -1, but the few teaspoons are too far off the mark. Upper Daily Intake, i.e. daily iron intake that is tolerable long term for healthy people without being likely to lead to health issues according to NIH (https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/) is about 45 mg. Calculating with 500 mg Fe/l blood (http://www.jbc.org/content/104/1/157.full.pdf - that's human, didn't find fish info) and 15 - 35 % absorption (https://academic.oup.com/ajcn/article/91/5/1461S/4597424) means that UDI is reached somewhere between 250 and 600 ml blood per day. That's 50 - 120 teaspoons.

Acute trouble from too much iron occurs at > 20 mg/kg body weight (NIH). That would be around 8 l blood. And then, that trouble is mainly gastro-instestinal, not iron-storage/ferritin related. (I'm assuming that anyone with hereditary hematochromatosis will immediately discard the "solution" in OPs question. Just as anyone with fish allergy would.)

Also, note that (cow/zebu) blood is a major part of traditional Maasai diet (https://en.wikipedia.org/wiki/Maasai_people#Diet) - which is just one ethnicity among many who eat blood (and liver) sausages (https://en.wikipedia.org/wiki/Blood_sausage). Coming from a blood and liver sausage region, I can say that a serving blood sausage in a hot main meal (lunch/dinner) may be ≈ 150 - 200 g or 50 - 130 g blood ≈ 25 - 60 mg Fe (liver: 15 mg/serving). Main health concern here is usually not iron intake but lipids. (Anyways these traditional meals that are not eaten daily)

@cbeleites don't they drink water and have any other food? Because i'm here exclusively talking about "surviving on blood"

Ishi: of course they do (so do the "vampires" in your links). As @Jan's answer points out everyone has to: the protein content alone means that humans (and many carnivores) need additional water. Any amount of blood does increase thirst instead of quenching it. I should have been more precise and stated that my comments are concerned with your point 1 (2 and 3 already being taken care of by Nuclear Wang). Thus, I consider your answer to give 3 bad reasons against drinking blood while omitting the relevant one.

@cbeleites some fish lack hemoglobin entirely so iron levels are very low.

Bonus question?

Here is a specific account of a person surviving at sea drinking turtle blood, while eating some fish and drinking some rain water.
Several peoples have a habit of drinking raw animal blood, at least for ritual purposes; here is a recent account. They probably drink more than a few spoons full so that the Lifescience article quoted by Ishi appears alarmist.

It is very unlikely that blood from any animal, including turtles, will be hydrating and we can't just rely on a story.

@Jan Well, obviously it depends on how much water you ingest from other sources, and perhaps even on the food (because there is metabolic water). The body will also adapt to not having enough water (perhaps even by using stress metabolic pathways, like excreting uric acid?); the numbers found are surely the optimal, healthy ones. Apparently, blood is a net water drain under normal conditions, but whether that holds if there is little water overall is not immediately clear to me.

@Jan I also find refuting concrete evidence with "we can't just rely on a story" unsatisfying. What is science if not the collection and interpretation of stories? Of course ideally stories which have been intentionally and carefully produced, but stories nonetheless.

The first source you linked says that "We're not sure just how long you can survive off turtle blood, but Ivan did say that he was also drinking rainwater." We do not know the amount of rainwater he drank, so we cannot conclude that drinking turtle's blood helped. We can rely on stories and learn from them, when they clearly say what exactly happened, but we do not know this here.

Very informative and the answer could then be yes indefinitely.

@Muze Careful (that's why I didn't agree with your edit): I think Jan has a point. While blood is nutritious (which may have helped the survivor) it may indeed remove water from the body when it metabolizes the protein. That water must be ingested in addition to the minimum amount without blood. But it's also possible that when dehydrated the body can metabolize the protein through different pathways, or with less water, or simply excretes excess protein, but I could not find anything about it.

In the intestine, macronutrients (carbohydrates, fats and proteins) are usually completely or nearly completely absorbed. You can't hope your intestine will filter out protein and absorb only water. It is possible that intestine does not absorb all the protein when ingested in great amounts - in this case it will trigger diarrhea with a great loss of water.

@Jan That makes sense; but perhaps it could be removed from the blood (and be excreted) without metabolizing it? I read that it is a sign of kidney desease to have protein in the urine, but that would make sense under dehydration which stresses the kidneys. It could even be a sign for damage (due to dehydration) but still lead to more available water.

Excessive protein (amino acids) enters the cells, where it is converted mainly to fat - this process yields nitrogen, which is removed from the body via urine in the form of urea, which drags some water with it. So, it is exactly this "protein removal" that causes dehydration. In healthy people, unmetabolized protein is not excreted into the urine or otherwise and, in short-term, cannot be stored somewhere in the body in great amounts.

@Jan comments are temporary and these comments would be relevant in your answer.


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Why does my eyes see a red spot when over exposed to light?
When I looked into my projector when it was on the blue screen it left a red spot in my vision. I should not have tried it but all the colors left a red spot. Why not a blue or yellow spot was left?

Did looking at a bright red light also leave a red after-image? Usually if you expose your eyes to a color, the eye becomes less sensitive to that color, and then shortly thereafter things will look more like the inverse of that color. If we're talking long-term damage, maybe it has something to do with the inside of the eye being red.

Without more details this is nothing more than an anecdotal report and your perception may have had nothing to do with that beamer in the first place. Personally, I would close this Q on the basis of that, but since your Q has received so many upvotes apparently it is appreciated by others.

You are describing the phenomenon of negative afterimages, a type of physiological afterimage, which is a result of how the cells in the retina work. Specifically, it is a result of the adaptation of photoreceptors.

According to the opponent process theory of color vision, our
  perception of color is controlled by two opposing systems: a
  magenta-green system and a blue-yellow system. For example, the color
  red serves as an antagonistic to the color green so that when you
  stare too long at a magenta image you will then see a green
  afterimage. The magenta color fatigues the magenta photoreceptors so
  that they produce a weaker signal. Since magenta's opposing color is
  green, we then interpret the afterimage as green.

There is a well-known illusion, called the negative photo illusion, which exploits exactly that. It is required not to move the eyes, because you need to bleach the photoreceptors in an exact place on your retina. This is why you have to fixate on a dot in the middle of a picture, otherwise the bleaching will not occur.
EDIT: I mention a two-axis (magenta-green system, blue-yellow) system, but the exact color system - which would predict which afterimage you would see - is most likely a trichromatic system, which includes red, green and blue channels, based on the principle of the three types of retinal cone cells. It is important to remember that this is a phenomenon in perception, and thus may, in some cases, not be reducible to the fact that there are three types of cone cells, or that bleaching of a photoreceptor has occurred. Please see the comment thread below for some clarification.

So OP should've seen a yellow afterimage. They, reportedly, didn't.

Of course you don't need to. I provided a detailed explanation as a comment under your answer. Would you prefer me to remove my downvote just to earn bounty points? That wouldn't be right in the spirit of science. @AliceD If the blue bleaching light was lighter, slightly green or cyan, it's opponent color would be red, as observed. See this illumination circle for reference

Of course a green light would have a red afterimage, but that's not what the question says.

Hi there. I'm sorry if I incorrectly interpret your comments as smug or highly pedantic. I'm not sure why such unnecessary and spiteful comments are being left, especially by a mod. The question states, why a red afterimage? to which my response, which happens to be scientifically accurate and concise, was because of cyan photobleaching and the opponent color phenomenon in visual perception. The question Why not blue or yellow? is well addressed. Demystifyingly, the questioner stared directly at a projector lamp giving off a light blue hue of light, which is common with projectors.

No need to feel offended. I do not support the answer, as the opponent system has two axes, namely a blue-yellow and a red-green axis. The answer suggests the existence of a blue-red axis. That's not conform the Herring Theory of opponent vision.

That's clear then. The phenomenon really seems to be based on an opponent color phenomenon. Whether it is the Herring two-axis theory, or a trichromatic one (the Young–Helmholtz theory, which better captures the triadic nature of retinal cone cells) is a more detailed discussion, I'm sure you'll agree. I would explain it simply though: if you bleach blue/green photoreceptors in the fovea, the negative image is based on the immediate and relative hyperactivity of red cone cells. It's possible OP confused red for orange in the afterimage, which would be the opponent color of blue. Cheers!


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Can 2 people give rise to billions? Adam and Eve 2.0
With with the advancement of GMOs the idea of giving rise to humans from 2 people is possible making questions like this invalid?
How many people are required to maintain genetic diversity?
With constant genome engineering to create genetic diversity on each generation of humans before conception how many generations can come from two people with ideal DNA? It is not inbreeding if the DNA is changed enough?

all this is just speculation and I don't think we can provide you an answer on this Stack Exchange website atleast. And I don't even understand what you mean when you say "How many generations of human can come from two people"? We are all descendants of the very first individuals in the homo sapien species.

Also, the picture is really really not in anyway helpful for the post.

I think the question deserves to be close. Yet, I felt like I would attempt to give you some help. I did not down vote but I don't think this is of any importance in the discussion. I don't really understand why this is unfair. In any case, don't worry too much. I wrote bad questions and bad answers before. Sometimes I did not agree with the bad reception I got. Nobody remember those. It is the same for you, people will associate you with your best posts only. And down votes really won't affect your reputation mutation (1 point loss per down vote and you get 2 points from accepting an answer).

@Remi.b how can it be made better?

@Remi.b I didn't down vote either.

The question involves genetics, ecology, sociology and is fundamentally untestable. I do not think it can be edited to become better, it is quite fundamentally not a question that one can give a scientific answer to. Also, "Can genetic diversity be created with technology?" is really broad and really different from the other question, who itself is already quite broad.

Would you feel better if I delete my answer so that you can delete your post (I am not sure you will be allowed to delete your post but maybe...)?

@Remi.b no, the answer is good but feel free to edit my question to fit better.

You do not need any 'editing', in theory it is possible for two people to give rise to 8 billions people. Early generations would suffer from some inbreeding depression but if you somehow get rid of it through 'editing', then you do not even have this trouble for the very first generation but you will have it for the successive generations. It is impossible to tell how important it will be and whether that will prevent this tiny population to survive though. There are ecological and sociological problems that are probably of great importance too. To make it short, it is not easy to survive alone!
For non-recombining DNA, it is necessarily true that we all currently living copies descent from a single individual (see coalescent theory although it will likely be too an advanced topic for you). This is the case of the Y chromosome (excluding the PAR) and of the mtDNA. We refer to these MRCA as Eve-mtDNA (biblical reference) and Y-MRCA, respectively.
Of course, these two individuals did not live alone, did not live together and did not live at the same time or same place. Also, none of these two individual is in anyway a good turning point for considering him/her the first individual of a new species. Y-MRCA is just the MRCA of all modern Y chromosomes and Eve-mtDNA is the MRCA of all modern mtDNA. The reality for the rest of the genome is more complex due to recombination. For your information, Y chromosome and mtDNA put together represent about $\frac{1}{50}$ of the entire genome.

I doubt this answer end up being of much help to you. You should probably just have a look at an intro course to evolutionary biology such as for example evo101.

No this is great. Sometimes just knowing it could be done by today's technology is great. We in theory could start over with less people then it states here. https://worldbuilding.stackexchange.com/questions/3/what-is-the-minimum-human-population-necessary-for-a-sustainable-colony Thanks

Never have I talked about technology in my answer. I just mean to say that there is not fundamental barrier to it. Also, I highlighted that two individuals might not be enough to ensure their own survival but it is impossible to answer this question more precisely in scientific terms because there is no way to empirically test such questions. I think you have misunderstand my answer. Also, you seem to misunderstand the scope of questions that is open to scientific enquiries.

I don't think we should understate the problem of inbreeding depression; sure, once the deleterious genes get selected out it would no longer be a problem, but what are the odds of the population surviving those early generations? If every couple has 20 children it's one thing, if they have two or three it's another. I also don't think we should understate the risks of that level of inbreeding to a population's survival. How many generations would it take to build the genetic diversity back to a point where the whole population doesn't get wiped out by the first epidemic? Thousands, surely?

2 people could give rise to billions?

To be clear the typical pathway for speciation in real biology is not via a 2-member founding group (even if it isn't fully biologically impossible). That's a religious story only.

@BryanKrause Indeed. And, yet again, the two ancestors I mentionned (Y-MRCA and Eve-mtDNA) did not live alone and did not live at the same time or same place and are in no way a good turning point for considering them the first of a new species.

Yeah, I caught the nuance in your answer, but I don't think OP is catching it.


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Why is HPV vaccines targeted for preteens?
Why is human papillomavirus products targeted to children before sexual activeness? Could all ages benefit from this vaccine even if they may have or have not contracted a form of HPV to prevent other forms of HPV?
https://okinawa.stripes.com/community-news/preteens-teens-target-audience-hpv-vaccine
I could not find anything where it says it is more effective on younger people vs older people.

What has your research told you? The Biology.SE community has agreed that questions that show little or no prior research effort are off-topic on this site unless you have shown your attempt at an answer. Please [edit] your question and tell us where you've looked for answers, what you do know about the topic, and where exactly you still have questions. Unresearched questions may be subject to down-voting and closure.

@BryanKrause I did could not find if there were a reason other than just to get it before you have HPV.

Well, if you have to get vaccinated before you get infected, why isn't that a good enough reason?

A lot of sexually active adults carry one or another strain of HPV but most do not develop cancer. You can carry HPV — and spread it to others — without showing any symptoms yourself:

HPV infections are so common that nearly all men and women will get at least one type of HPV at some point in their lives. Most people never know that they have been infected and may give HPV to a sex partner without knowing it. Nearly 80 million Americans are currently infected with some type of HPV. About 14 million people in the United States become newly infected each year.

There is less reason to give a vaccine to someone older, generally, who is almost certain to be infected with some form of HPV. A vaccination is not a broad cure, though it can provide some protection against infection from strains of HPV that someone is not already infected with:

But the vaccine also offers some protection for HPV-positive women, reducing cervical lesions by 17% and genital warts by 35%. HPV-positive women usually aren't infected with all four of the targeted strains. In clinical trials, those infected with one or more of these strains before vaccination were protected against the remaining ones.

Pre-teens are unlikely to be infected with any forms of HPV, having no or much less sexual contact, and so they are the best candidates for being administered the vaccine.
This cohort will get the most protection from those strains that the vaccine protects against, strains which are most likely to cause relevant cancers.

From presentations made by oncologists at a cancer survivors support group at MDAnderson ; chances are very high the young people will get some HPV by age 20. The upside is that of the 50+ strains of HPV only a few cause cancers : but why take any chance on cancer ?  Another upside is there is now data that the vaccine works : It took time to show results because the HPV cancers don't develop until over age 40 and usually older ( I was 70). Unfortunately the vaccine was only given to girls at first , it is now recommended for boys and girls . The support group is for Dysphagia/swallow problems which are basically" head and neck  cancers" so mostly from HPV which is why it has been discussed. As these are informal oral presentations I can't site sources but I am certain the information can be found in medical journals.


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Could a strong magnet field repel the body before damaging it?
Could a magnetic field be strong enough to damage the body or erase the brain?
Blood is slightly diamagnetic, so if the field was strong enough, could it repel a body evenly?
Could a diamagnetic material go through electrolysis with water then ingested to give the body more diamagnetic properties?

A strong magnet can repel a body, but the effect is due to small diamagnetism of every atom.
You can see a picture of a levitating frog and a video here. And a very good explanation and more videos here.

Just to show how strong the magnetic field is: This was filmed with a telescopic camera pointed at a mirror above the container with this tiny frog. Any other setup would ruin their cameras.

While mammalian blood is characterized by diamagnetism (as demonstrated here), as far as I know, the human body as a whole is more or less electrically neutral—that is, with all of its summed components the negative and positive charges balance each other out or there are extremely insignificant differences.
If you want to get strict though, it's theoretically possible to use a super strong magnet to repel or attract someone's entire body to a meaningful degree as long as it's not electrically neutral at a given point in time. But even in the video linked above, the guy is using a super strong magnet to observe its repulsive effects on blood and the blood is just barely moving away; definitely not forceful enough to where someone wouldn't be able to resist moving with just their body weight alone.
So to answer your question: can someone be repulsed or attracted by a magnet practically? No. Can someone be repulsed or attracted by a magnet theoretically? Yes.


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What plants use the green spectrum?
What if the only light provided to a plant was from the green spectrum would plants adapt or starve?

Green is pretty much the last color that you'd want for a plant. Thinking logically, a plant is green because it reflects green light, and hence, plants do not absorb green light for photosynthesis.
Let's take a look at the spectral absorbance of the various pigments in plants:

You can see that all the pigments show very very poor absorption when it comes to green. Plants tend to absorb light at violet, blue, and at red colors predominantly.

To answer your second question: what would happen if the sun spectrum changed to green?
For all the "what if" questions, we cannot give a definitive answer, and all of what I say will be purely speculations. Let's see what could actually happen:
Possibility 1: Plants will evolve to develop different pigments that absorb wavelengths that correspond to green light. Since the sun itself is green, and hence the entire surroundings will be green. Plants absorb all of the light that the sun is capable of absorbing, and hence will appear to be black to the human eye.
Possibility 2: Plants will die out, due to the sudden change in the sun's spectrum, which will cause the rest of the life forms that depend on plants to die out as well.


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What kind of owl does this moth look like?
I found this moth and I noticed that it looked like an owl to me and remembered something about how some moths camouflages look like predictors?  What kind of moth this is and what owl does this moth resemble? Would this moth be a newer species than other moths because it came after the owl? The wing span is 5.5 inches across. The eyes of the wing are transparent allowing light to pass through like reflecting eyes.

North American Great Horned Owl

First of all what a nice foto!
I think this is Antheraea polyphemus. According to Wikipedia, the moth has an average of 15 cm (6 in).

The purplish eyespots on hind wings give its name - from the Greek myth of the Cyclops Polyphemus.

And about the defence strategy it's quite interesting. As a green caterpillar, it is camouflaged by its color. However, if it's noticed then it starts to do pose like Sfinx to look less like a caterpillar, if it's still attacked by threat then it is started to make a clicking noise with its mandibles - sometimes as a prelude to or accompanied by defensive regurgitation of distasteful fluids.

When threatened, adult Polyphemus flip the front wings forward and also often flap the wings exposing the large hind wing eyespots - possibly to startle potential predators. The eyespots are possibly to protect an adult from Blue Jay.

The pattern on the hind wings of the polyphemus moth resembles that on the head of the great horned owl (Bubo virginianus).

I hope it is enough. I add that owl too.

I like it.....+`1


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Why does the wavelength in curly hair differ?
Different people and animals have different wavelengths in the curls in their hair. I understand what purposes hair serves in protecting the skin from light and bugs. I am wondering about the eventual physiological consequences of curly vs straight hairs.
Do the curls help in cooling, blocking light or catching wind over flat hair? Does the wavelength in curly hair have intrinsic properties that physically would give an animal advantages in climates where straight hair would not?
I will be happy to accept another answer.

http://physics.stackexchange.com/questions/261308/why-does-the-wave-lenght-in-curly-hair-differ

My hypothesis when the curls are left ungroomed they will form knots. These knots form a barrier that works similar to woven wool. Unlike strait hair the mat of knots (dreadlocks) collect dirt and form denser material that insulates against direct light and mosquitoes better than strait material. The wave length does play a part as well. The smaller the wavelength the tighter the knot. The tightest knots are commonly found in places that have the most sun light per year.
Strait hair tends to keep heat in more and ice builds up less on it.


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How many strains of influenza can occupy a person at one time?
Could a person's immune system be built eventually to be able to inject all the known strains with in to stay immune?

Your premise is wrong to begin with. It's absolutely not true that everybody eventually catches the flu.

Please edit your title so that it gives a better indication of what aspect of influenza it concerns. This saves people time and, unless this question is removed (as being hypothetical), is more useful for indexing.

@David revised...

@TimonG. - Your comment is incorrect. Eventually, indeed, most people will catch the flu (Influenza A or B). It is the rare individual who will have never, ever contracted any strain of influenza. Up to 30% of the infected are assymptomatic, and the odds of being infected any given year are from about 1:10. (Range: 1:20 to 1:5.) If you live 20 years, your odds of never having gotten the flu are about 2 in 100. What are your numbers?

That what I initially thought I had. I changed it because if an answer. I am talking about intentionally on a safely way of taking all the strains numbers aside.

Hypothetical questions are often sub-par due to the absence of information on the part of th OP. However, the worst part of this question is "Could my blood be used to help others recover or would it be lethal?" Why in heaven's name would it be lethal? Are you dead from it?

@assymptomatic because I would be asymptomatic and contagious and not immune.

@anongoodnurse You are mistaking the notion that everybody catches the flu eventually with the concept that the average person gets the flu eventually. The latter is correct, the former is not. Even your choice of numbers (which I did check and are approximately in the right ball park but you are ignoring re-infections in your calculation) yield millions and millions of people who will never get the flu. I want to note that OP edited his comment to "most" people only now after my comment. OP originally stated flat out that everybody gets it and that is false even acc. to your numbers.

We seem to also disagree on what it means to have the flu. Being exposed to the influenza virus is being exposed to the influenza virus. Flu is the label for the disease which is caused by the influenza virus, not a label for the influenza virus itself. If a person has the influenza virus in their bodies but absolutely no symptoms, I consider it confused and incorrect to state that they have the flu. Diseases are sets of conditions and symptoms, not the mere presence of a pathogen that your immune system is fighting off. This is similar to the distinction between being HIV+ and having AIDS.

@TimonG. - I never said everybody catches the flu. Read more carefully both my statement and the OP's. Also, if you are asymptomatically infected with influenza virus, you have caught the flu. Again, where are your numbers?

OP literally said "Eventually you will catch the flu." in the first version of his question, check his edit history. That was what I originally replied to. OP then edited his question after my comment to instead say "Eventually most will catch the flu.". That is a completely different claim and I already explained this in the previous comments. It doesn't do you any good to be confrontational and accuse me of not reading when you yourself haven't done so.

It's perfectly fine to edit your question to be more clear, @Muze. There is nothing wrong with that. Perhaps in the future a small edit note at the bottom will help people.

where do i find a list of influenza strain weak to worst?

@Muze - if you try ordering some of the bad strains of influenza, you'll very quickly find yourself being visited by large, serious men with bad haircuts and suits. This is not a good idea to follow up.

The question is whether being exposed "to all strains of influenza" would make one immune to all strains of influenza. No, and it's not possible to expose oneself to all strains of influenza in the first place.
It might be technically possible to expose yourself to all subtypes of influenza, if you limited to the hemagglutinin subtypes, of which there are 18. But subtypes are not strains; a strain is an antigenic variant of a subtype, and there are tens of thousands of such variants. Even if you somehow managed to expose yourself to every known strain, presumably by injecting yourself every few hours for years (you probably don't want to literally expose yourself to all the strains of flu, because some of them have mortality rates well over 50%, so you'd be dead before you were immune), new strains arise literally every minute of every day.
And because of vagaries of the immune system that are too complex to get into here, immunity to some strains prevents immunity to some others (one review is Immune history and influenza virus susceptibility), so it's either very difficult, or perhaps intrinsically impossible, to get complete immunity.
There's work being done on overcoming these problems with "universal" influenza vaccines, and your best bet is to wait until some of these are available.

I had no idea that immunity to some strains can prevent immunity to others! Nice to learn something new!


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Potato Power. Self sustaining medium using a living potato plant possible?
The second picture are potatoes wired in parallel. I understand that the potato is the medium for a chemical reaction between the copper and zinc.
That aside, would wire and in soil potato plant continue to grow replenishing the medium(nutrients and water) regardless of having a current in the potato?
Or
Will the plant react to the physical damage or be depleted of nutrients/water needed to weakening the current or plant?
Maybe the current can be intermittent to allow the plant to recover?
Can the current be low enough not inhibit plant growth?
I would ask chemistry if I was interested how a potato clock works, but I am more interested in the plant health and connections.

I have seen many potato experiments online but none where the potato plant was intact in the soil producing power.

Yes, the potato clock will work when still in the ground, but it won't work any better than a potato removed from the ground.
Potato batteries are awesome and cool projects, but they often convey the wrong concept. The energy produced from a potato battery is not from the substance, nutrients, or sugars of the potato, but rather via the galvanic action of the two metals inserted into the potato.
The simple counter to this mental model is to point out that you can make a battery out of salt water, which clearly doesn't have any organic, energetic molecules in it. However, I'll talk a bit more about what's actually causing this effect and why it doesn't work in the way you imagine it might.

The above image is an example of a "potato battery" made without the potato. Identical setup and the energy obtained is identical given everything else the same.
Potato power- er, metal power?
This experiment is supposed to demonstrate the concept of an electrochemical cell. Electrochemical cells obtain their energy from the reduction-oxidation reactions that happen between two metals with different reduction potentials. When two metals - such as copper and zinc - are placed in a medium that permits the exchange of electrons and ions, an electrical gradient is produced as electrons move from one metal to the other and ions move the other direction. This gradient can then be captured and used to do work such as powering a lightbulb or an AI.
In the potato powered example, the power comes from zinc and copper. If you want a more powerful battery, use more zinc and more copper- not a bigger potato. If that is not good enough, try replacing the zinc with something like lithium- this is what we've done with modern, rechargeable batteries.
In truth, the potato battery would be better described as a normal battery that just happens to be inserted into a potato. You'll make a better battery if you use copper pennies and aluminum foil in vinegar.
I do not mean to shoot down your idea, and I am glad you are looking into renewable energy sources- but you may be better served by a class on electricity and batteries than by asking questions on biology.SE!
EDIT: I would assume that the electrical potential of this kind would also kill the plant, given that you're essentially electrocuting it. However, I was unable to find any information on the resistance of potato plants to electrocution.

@Muze I think you're still misunderstanding what happens here. The only thing doing the work is the strips of metal, which aren't alive. The potato could be alive, dead, or something in between- it's irrelevant to the chemistry. Batteries eventually stop working because the electrical potential is "used up", not because they run out of nutrients or life force. Your live potato battery would likewise need to be serviced, with new metals inserted regularly.

I'll direct you to this website: https://www.thenakedscientists.com/articles/questions/can-you-electrocute-plants and this article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2141166/ both of which may provide information for you

While that edit does indeed clarify the essence of your question, it’s not the medium that needs to be sustained to keep the battery functional. It’s the electrochemical gradient created by the metals that needs to be sustained, and that’s independent of the medium.

your answer is very good I don't know why I asked a dup. if you edit it. I'll up vote it

Placing copper on one side of the potato and zinc on the other will not "suck the energy out of the potato".
the energy in the potato NEVER gets converted into electricity. The metals do all the work, just using the potato as a wet sponge.
Now, it would probably kill the potato though, because of all the ions that are there that shouldn't be there (zn and cu), the ~1 volt current screwing up the electrochemical gradients, etc.
So, yes, it would probably die, but not because anything gets stolen from the potato and it starves. Just because the voltage would interfere with cell functions.
The only real way to know is to experiment on a living plant though


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Why do wild animals not eat in captivity?
I have rescued possums before but this is the first full grown opossum I took in. She was skinny unlike the one I have now for 3 years and healthy. I would not normally take in a grown animal like this, but she looks like she hasn't eaten for a while.
I have put all the recommended foods in a cage for her, but she won't eat. I understand that they eat everything so why the hunger strike? Will she starve or eventually eat for self preservation?
Where I live if you can hunt them you can breed them for livestock or what ever. Some places have no regulation unless the species is endangered which this one is not.
https://www.youtube.com/watch?v=YEVL0xuJuPQ Possum Snuggle.

Please do not try to keep a wild animal as a pet as someone untrained.

"But while possums thrive in the wild, examples of these creatures surviving in captivity are rare. Another point is that it is illegal to keep possums without a wildlife rehabilitation permit. [...] Vets don’t have the experience to deal with their health issues." https://www.animalwised.com/possums-as-pets-general-guidelines-and-tips-1401.html

@BryanKrause revised.

note there is no state in the US that does not have some regulations concerning keeping opossums as pets.

I'm voting to close this question as off-topic because the frame for this question makes it seem like it is about how to care for a wild opossum or predict a specific animal's behavior. If you can edit this to make it clear it the title is the actual question (why do wild animals not eat in captivity), and include your research, I will retract my close vote.

Could possibly be closed as personal (veterinary) medical question as well (as it is currently framed)

@Muze The legality in your jurisdiction doesn't have much influence on my suggestion not to keep a wild animal as a pet or livestock if you are not trained to do so. I'm far from an "animal rights activist," but I believe in a basic respect for especially vertebrate animals, which every farmer I have ever met has, along with sufficient training to care for them.

@BryanKrause I let the possum out of her cage. Now she is eating and wandering the house. I do have experience raising them. I would not have taken her in, but she looked emaciated.

Many wild animals will not eat in captivity because they are under stress, few mammals react well to captivity. weird smells and sounds, restricted movement, inability to hide, there are dozens of stressful aspects to captivity that trigger the flight or fight response for small mammals. Lack of appetite is a common stress response in mammals and even when very hungry they are often more focused on escape than feeding. This is one reason keeping wild mammals as pets is regulated in every US state, and is highly discouraged, you are basically killing the animals slowly.
In opossums and many mammals lack of appetite is also one of the early signs of rabies infection, so yet another reason laypersons are discouraged from trying to keep wild opossums as pets.
Source 1
Source 2

If it doesn't answer your question then I have no idea what you are trying to ask, If you are asking for a specific diagnosis for one individual that is very off topic.