Avm1

Why moderate neutrons in reactors?

I think the explanation of criticality with thermal neutrons on this page is incorrect. It is true that the neutron capture cross-section of U-238 increases at lower neutron energies -- this is why you breed Pu from U-238 in a thermal reactor. But the fission cross-section of U-235 and Pu-239 increases dramatically for thermal neutrons, which more than compensates for the increased capture by U-238. At 1 eV, the fission cross-section for either fissile isotope is near 100 barns, just about two orders of magnitude greater than for unmoderated fission neutrons, and it keeps going up at lower neutron energies. Operating reactors with natural uranium has nothing to do with the variation in capture cross-section by U-238, but hinges on using a moderator such as heavy water or graphite that absorbs fewer neutrons than the hydrogen in light water.Avm1 (talk) 01:03, 18 January 2009 (UTC)

You are clearly right about the fissile cross section going up with moderation, so the article is wrong about that and must be changed to mention both effects. But are you sure about which effect (better fission cross section in U-235 vs. poorer capture one in U-238) is the most important neutron temperature effect? SBHarris 00:34, 8 March 2009 (UTC)

I don't have the data for the change in capture cross-section for U-238 versus neutron energy, but I'm quite confident it's not several orders of magnitude. However, it was inaccurate of me to claim that operating with natural uranium "has nothing to do" with it. Let me know if you think the edit I made on the main page is appropriate; I'm new to this. Also, there should be an external link, for example to [[1]] Avm1 (talk) 00:47, 8 March 2009 (UTC)

Okay, I'll look. Again, welcome. Stay away from the politics of this place and stick with physics (as complicated physics as possible, in order to keep the powerplayers far away) and you'll be fine. Also, http://www. links only need one set of brackets, but usually benefit from a "retrieve date" and article title. I'll see what I can add. SBHarris 01:25, 8 March 2009 (UTC)

File source and copyright licensing problem with File:Sascha on East Summit of Russell.jpg

File Copyright problem

Thanks for uploading File:Sascha on East Summit of Russell.jpg. I noticed that the file's description page currently doesn't specify who created the content, so the copyright status is unclear. If you did not create this file yourself, you will need to specify the owner of the copyright. If you obtained it from a website, then a link to the website from which it was taken, together with a restatement of that website's terms of use of its content, is usually sufficient information. However, if the copyright holder is different from the website's publisher, their copyright should also be acknowledged.

As well as adding the source, we also need to know the terms of the license that the copyright holder has published the file under, usually done by adding a licensing tag. If you created/took the picture, audio, or video then the {{GFDL-self}} tag can be used to release it under the GFDL. If you believe the media meets the criteria at Wikipedia:Non-free content, use a tag such as {{non-free fair use in|article name}} or one of the other tags listed at Wikipedia:Image copyright tags#Fair use. See Wikipedia:Image copyright tags for the full list of copyright tags that you can use.

If you have uploaded other files, consider checking that you have specified their source and tagged them, too. You can find a list of files you have created in your upload log. Unsourced and untagged files may be deleted one week after they have been tagged, as described on criteria for speedy deletion. If the file is copyrighted under a non-free license (per Wikipedia:Fair use) then the file will be deleted 48 hours after 03:04, 6 August 2010 (UTC). If you have any questions please ask them at the Media copyright questions page. Thank you. Eeekster (talk) 03:04, 6 August 2010 (UTC)

Chua K'a

There's no one place where you can view a complete list of all existing categories; rather, if you don't know the appropriate categories then you have a couple of alternatives:

1. One approach is to check out similar or related articles to see where they're categorized. For instance, if you click on the massage link you can see that its categories include Category:Massage, Category:Mind–body interventions, Category:Manipulative therapy and Category:Massage therapy — so you can either use one or more of those, as appropriate, or review their contents to see whether there are more accurate subcategories available.
2. The other approach is to understand that Wikipedia has a whole categorization project of people who work on finding and adding the correct categories for articles, and thus if you're at a loss it's also completely okay to just leave the tag there until somebody else within that team finds and adds the right categories for you. Of course by all means you're welcome to add categories yourself if you know how, but it's just a collaborative maintenance queue that a lot of people participate in — so I just want to make sure you understand that it's not meant to be taken as a personal criticism of you, and you're allowed to just let someone else deal with it too if that's what you feel more comfortable doing.

Hope that helps a bit :-) Bearcat (talk) 18:32, 11 May 2013 (UTC) Thanks, Bearcat! Avm1 (talk) 18:15, 13 May 2013 (UTC)

A page you started (Chua K'a) has been reviewed!

Thanks for creating Chua K'a, Avm1!

Wikipedia editor Jackson Peebles just reviewed your page, and wrote this note for you:

Appropriately sourced, though I feel that this article would benefit from some sort of (unknown to me, as I'm no expert in the field) template on holistic health, additional external links, a better lead, and some images. Great work, though; thanks

To reply, leave a comment on Jackson Peebles's talk page.

Learn more about page curation.

Ways to improve Chua K'a

Hi, I'm Jackson Peebles. Avm1, thanks for creating Chua K'a!

I've just tagged the page, using our page curation tools, as having some issues to fix. This lead is far too short and does not give an overview of the topic.

The tags can be removed by you or another editor once the issues they mention are addressed. If you have questions, you can leave a comment on my talk page. Or, for more editing help, talk to the volunteers at the Teahouse. Jackson Peebles (talk) 06:16, 2 August 2013 (UTC)