Jump to content

John Cuthber

Resident Experts
  • Posts

  • Joined

  • Last visited

  • Days Won


Everything posted by John Cuthber

  1. That's debatable at best. https://www.cbc.ca/news/canada/edmonton/the-science-says-there-s-no-difference-between-a-dry-or-a-wet-cold-sorry-1.6268564
  2. Possibly because the reason why that area is misty is because it is cold. Why else would there be mist there, but not elsewhere? Because it's over a thousand times denser. Water vapour has a higher heat capacity than air, but a lower thermal conductivity. If it's cold enough that you are not sweating (significantly) then the rate of evaporation is irrelevant to heat transfer. At 10C that probably applies. It's well known that "other people's houses" feel colder for the same temperature- simply because you learn to avoid the drafts in your own house.
  3. It's complicated but for most people (unless they are doing a lot of physical work, 10 degrees will be too cold. And that will be the case regardless of humidity. If you just heat up the air the relative humidity will fall and that will also add to comfort. The "wasted" energy from a dehumidifier will warm the room and be beneficial anyway. But a heater is cheaper to buy. There are books about this. https://en.wikipedia.org/wiki/Thermal_comfort
  4. For plenty of animals "red is ripe but green isn't" is relevant.
  5. Colour is not the same as wavelength: discuss. In the meantime , here is some music...
  6. There are plenty of Left wing votes. The current government only got about 40% and you can assume they included pretty much all the Right wing. The problem is our electoral system. The biggest minority becomes an elected dictatorship.
  7. Are you talking about this sort of thing? https://en.wikipedia.org/wiki/Voltage_multiplier
  8. Apparently the problem is that you don't understand a hypothetical situation. But yes, it does explain a lot
  9. At that point I called the local hospital and had myself admitted to diagnose the mental health issue.
  10. Thanks for letting me know that the microscopes I worked on in which electrons tunnelled giving a map of the surface electron fermi potential were not electron microscopes. I'm not going to build a tunnelling proton microscope. It's possible, but much easier to use electrons. Which is why scanning tunnelling electron microscopes are, in fact, electron microscopes. (Wiki is not God) These are electron microscopes too. https://en.wikipedia.org/wiki/Field-emission_microscopy They don't have electron guns (in the definition Sensei posted) But they are tunnelling microscopes. The field emission relies on tunnelling. Somehow, I think the folk who designed scanning electron microscopes where pretty much the only "moving part" was an electron beam, knew what they were doing.
  11. I wasn't aware that anyone had said that STM and SEM were the same. Can you point out where they did so? I obviously know they are different, you may recall that I pointed out that you can run one of them under water and that it doesn't have an electron gun. The OP just said "electron microscopes". That term includes TEM, STEM PEEM and SEM. If I was an amateur trying to build an electron microscope, It'd build a tunneling one. (No high voltages, no vacuum chamber and also past experience of helping rebuild one about 1990)
  12. Is that a reference to this? Thankfully, not all electron microscopes use an electron gun. The requirement for a vacuum is last century's technology. https://www.sciencedirect.com/science/article/abs/pii/0006291X91910328 Calling the newbies "silly" is a nice example of this. But to be fair this is correct; just like I said.
  13. I'm sorry you expressed yourself so badly. The answer to your question is "it depends". There's several types of electron microscope and they use a variety of methods to form an image. If you haven't figured out how to see that then I'm right. You haven't figured everything else out.
  14. If you think the shape of the electrons matters, then I very much doubt you have figured everything else out.
  15. It's not a bad bet that the original apples were similar to what we call crab apples. If they always bred true then they would still be crab apples. It's important to distinguish the level of "sameness" that people seem to want in apples from that which they would get in nature. For a lot of things, plants which are effectively siblings are close enough, but for our apples we want identical twins. There's a half-way house where we grow F1 hybrids for use. So, for millennia our ancestors chose the biggest sweetest apples and in due course those apples' seeds were "planted" near human habitations (and well fertilised too). So the treed that grew from them were biased in favour of big sweet apples and the offspring were subject to the same sort of pressure. No need for Adam or Eve to understand genetics. Once we started farming, we deliberately chose seed from plants that we liked. But we discovered that apples don't breed true and they take ages to grow so it's a slow process to take pot-luck. We found it's much more efficient to clone them.
  16. Here's a list of varieties produced from Cox's orange pippin which were obtained by breeding them with other varieties. https://en.wikipedia.org/wiki/Cox's_Orange_Pippin#Descendant_cultivars One example is Allington Pippin (Cox's Orange Pippin × King of the Pippins) But it's important to realise that, if you fertilised flowers of one with the pollen of the other and grew the pips there's still no guarantee that the seeds would grow into anything like the Allington Pippin for essentially the same reason that you and your brother or sister are not identical. Apples (and a lot of related fruit) are self-incompatible. You can't get seed from a Cox's orange Pippin without crossing it with another variety. So you can't raise them from seed. If native varieties all bred true there wouldn't be any cultivated varieties. If you are growing commercial apple trees there are no generations. There are no seeds; it's all cloning. And that's where we get the word "clone" from from Greek klōn ‘meaning twig’.
  17. I can believe you, or I can believe wiki " while fruit varieties such as apples have been propagated over the centuries through grafts and cuttings. " And I know that fruit trees won't "breed true".
  18. Mary had a little lamb. Her father shot it; dead. But still it goes to school with her Between two bits of bread.
  19. I don't see why it couldn't work. They commonly use quince stocks for pears https://www.orangepippintrees.co.uk/articles/fruit-tree-gardening/rootstocks-for-pear-trees
  20. The root stocks are also propagated from cuttings- for the same reasons as the top bits. I gather that you can graft pears, apples and quinces onto the same tree. I'd like to know if you can do it with these fairly closely related plants https://en.wikipedia.org/wiki/Buddleja_davidii and https://en.wikipedia.org/wiki/Buddleja_globosa Because the clash between the orange and purple flowers would be hideous.
  21. Those trees are almost certainly grown from cuttings. The word "heirloom" in this context means that they are a very old variety. https://en.wikipedia.org/wiki/Heirloom_plant
  22. I think it was assessed here And the consensus was that it's crazy. I don't think there has been any improvement since.
  23. To a good approximation, weigh the jack. Find jacks of similar design on the net and then look for one that weighs the same.
  24. I'm pretty sure someone has the maths for things with a smooth change in refractive index. https://en.wikipedia.org/wiki/Gradient-index_optics
  25. I did not say that no effect exists. I said that if there was a big effect, we would know about it.
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.