exchemist

Your logic looks right to me, certainly (well done for allowing for the decrease in free oxygen), though I don't pretend to do this sort of thing every day. You probably have a lot more practice at doing problems like this than I do. I seem to recall you have asked for confirmation of your answers before and they were OK then. I have a feeling you may be quite good at this - unless I'm mixing you up with someone else.

Haven't you forgotten to square some things in ( b )? P.S. Oh I see, it looks as if you have squared them but not shown you are doing so in the fraction you wrote down.

I trust, then, that your video makes clear the paper is not claiming to have solved the riddle of how the first replicator arose. Leaving aside the silly hype in sections of the lay press, do you have anything to say about the content of the paper?

Yes of course replication is essential for evolution. However the purpose of this research was not to demonstrate the development of self-replication, nor does it claim any such thing. The title is: "Evolutionary transition from a single RNA replicator to a multiple replicator network". The paper does demonstrate that. Have you actually read the paper?

That's a bit silly, frankly. As both you and I have pointed out, that is not what the paper is about. It's just a typical pop-sci headline: eye-catching but misleading. So why waste time on that? It would be far more interesting if you can build on my brief summary of what it seemed to me the paper actually is about, as per post 2.

Well it's 2235 in London, now and I'm tired after a 2hr choir rehearsal (performing Haydn's Creation on Saturday) so I'm off to bed. I think you've got the idea by the look of it now, so hope you manage to work the rest of it out.

In post 2 of this thread I made the same point and provided both a link to the paper and a synopsis of the research, last Tuesday. All without making a video, too! 😀

You seem to be another one whose hovercraft is full of eels.

Yes. And if, like an earthworm, it does not have very elastic skin, it will go pop eventually. But apparently (I did not know this) ragworms have elastic skin and can stretch without being damaged. Also it seems they can tolerate quite a significant dilution of their body fluids and still function. Does that explanation fit the data you have been given?

Here's the paper: https://www.nature.com/articles/s41467-022-29113-x Seems the researchers started off with a strand of RNA that included the code for a replicase, i.e. an enzyme enabling it to replicate from nutrients supplied. So it was already self-replicating when they started. Thus, self-replication was not something acquired during the experiment, so that part of the puzzle of abiogenesis is not addressed. What was interesting is that during the course of the experiment, different lineages of RNA appeared, due to mutations during the replication process. These competed with one another in a Darwinian manner and eventually several "won" and became established as the main successful types. However something else also happened, which is that some cooperation developed between them. In some cases the replicase code became lost due to mutation, but then RNA lacking this code still could reproduce, by using the replicase created by other strands which still retained this capability. So the final ecosystem of RNA was more subtle than might have been expected. At least, that is how I read it, skimming rather quickly.

Exactly. Water will flow to the more concentrated side from the more dilute side. So if the membrane is the skin of a worm, and the ionic strength on the inside is approximately that of seawater, what will happen to the worm if it is placed in a solution with lower ion concentration?

Aha, so it's seawater equivalent , i.e. in ionic strength, not real seawater. Regarding the burst earthworms - and your expanding ragworms - If you have a more concentrated solution and a weaker one, either side of a membrane that allows water molecules to pass through, but not the ions, what tends to happen?

How can you have 125% seawater? But, to give you a clue about what may be going on, it is common to see burst earthworms after heavy rain. Why do you think that might be?

What does 125% water mean?

Think what you are now proposing: to add an energy storage system, as well all the other stuff I have itemised. If you are going to do all that you might as well run a static EC engine somewhere, convert the energy to a convenient form and put that in your on-board storage system. In short, run a generator and store the energy electrically in a battery.

And indeed, if, as in a steam locomotive, you use an open cycle steam engine to avoid the bulk of a condenser, you exhaust the working fluid and need to replenish that as well. So you need a water tank, as you had in the tender of a railway engine.

In principle any kind of external combustion (EC) engine could do what you propose. There is no magic about steam as a working fluid in this respect. In fact something like the Stirling engine would probably be more compact and just as efficient. The big snag, it seems to me, about an EC engine burning biomass for transport, is that the combustion can't be turned on and off in accordance with the variations of power demand. So you will intrinsically waste a huge amount of energy by keeping the heat source burning all the time, even though you only use the full heat output sporadically. When you add in the exhaust control measures needed to prevent pollution from straw burning, not to mention the inconvenience of needing to store five times the volume of fuel, and the need for getting rid of considerable amounts of solid ash at intervals, it becomes fairly plain why this idea is not going to fly. EC heat engines make a lot more sense in fixed installations such as power plants, where these issues can be managed without the overriding need to keep everything compact and lightweight, and where energy demand from the system is fairly constant rather than intermittent.

Generally not, I would have thought. The technologies involved are so different. But I seem to recall reading there are therapies that can "mark" a tissue for destruction, by an agent that is introduced subsequently and which acts selectively on the tissue that has been marked. This could be considered, superficially at least, a bit like the illumination of a military target by a laser. Maybe someone with medical knowledge can comment on whether my recollection has any basis in fact.

Search me. But he did. There are some things that have made it into Christianity that come from St Paul and are mentioned nowhere in the gospels. A classic example is the Christian disapproval of anything to do with sex.

I have, once, on foot, been invited to cross ahead of a car turning into a side road, when I stopped to let it go by. I was a bit surprised but then remembered this change. I doubt it will make much difference, especially since there seems to have been zero by way of a campaign to alert anyone to the changes. The trouble with these rules is that they will be observed fastidiously by the sort of person who is any case a careful road user. Yer average white van man, i.e. the sort of person actually likely to knock you over, won't give a toss, just as he never has in the past. It's a bit like voluntary covid mask-wearing: the people likely to be infectious won't be the ones who will bother with a mask.

Didn't stop him making up stuff Jesus never said, though, did it?

Who determined that?

This site may give you some ideas to verify for yourself (I don't vouch for the reliability of the site): https://treehozz.com/are-marine-invertebrates-osmoconformers I would guess that a salmon will be a euryhaline osmoregulator, since it migrates from salt to fresh water without any trouble, while many other fish will be stenohaline since they can't do that. As for a stenohaline osmoconformer, what about a sea anemone or jellyfish? But since these are terms that I have only learnt the meaning of as a result of your query, (ten minutes ago), do not treat me as an authority!

So if Jesus is the only teacher, why do Christians quote the Epistles of Ss Peter and Paul as well, as if they also have authority?

Thanks, I'm feeling a bit better already. By all means come back here if you are still stuck.