How to disable lenses in the Dash menu?

Question: How can I disable some lenses in the Dash menu?
Comment: Open terminal: sudo apt-get remove unity-lens-shopping
Answer: There are several ways to do this, though one would think the easiest thing for ubuntu to do would be to have some easy to access configuration options from within the dash, but that's just crazy talk.
If you're confident using the terminal then I recommend option 1, because the behaviour of the software center will be misleading and confusing.
Option 1 - Use the Terminal (Recommended)

Open the terminal Ctrl+Shift+T
To check what scopes and lenses are currently installed, use dpkg with grep. e.g. list all scopes and lens packages
$ dpkg -l | egrep "(unity-lens-|unity-scope-)"
ii  unity-lens-applications     ...     Application lens for unity
ii  unity-lens-files            ...     File lens for unity
ii  unity-lens-gwibber          ...     Gwibber Lens for unity
ii  unity-lens-photos           ...     Unity Photos Lens
ii  unity-lens-shopping         ...     Shopping lens for unity

Notes on 14.04
14.04 has a great many more lenses and scopes than ever before. Some of which can't removed without destroying the system e.g. unity-scope-home.
These are some of the scopes and lenses installed by default in 14.04:
unity-lens-video
unity-lens-friends
unity-scope-audacious
unity-scope-calculator
unity-scope-chromiumbookmarks
unity-scope-clementine
unity-scope-colourlovers
unity-scope-devhelp
unity-scope-firefoxbookmarks
unity-scope-gdrive
unity-scope-gmusicbrowser
unity-scope-gourmet
unity-scope-guayadeque
unity-scope-home
unity-scope-manpages
unity-scope-musicstores
unity-scope-musique
unity-scope-openclipart
unity-scope-texdoc
unity-scope-tomboy
unity-scope-video-remote
unity-scope-virtualbox
unity-scope-yelp
unity-scope-zotero

Scopes and leneses after most of the one's that can be removed have been removed:
$ dpkg -l | egrep "(unity-lens-|unity-scope-)"
ii  unity-lens-applications ... Application lens for unity
ii  unity-lens-files        ... File lens for unity
ii  unity-scope-home        ... Home scope that aggregates results from multiple scopes

What do the various dpkg flags like 'ii' 'rc' mean?

To remove a lens use apt-get remove. e.g. remove the unity shopping lens:
sudo apt-get remove --purge unity-lens-shopping

Option 2 - Use Ubuntu Software Center

Open up Software Center and search for "lens".
Uninstall by selecting the item and clicking "Remove".
IMPORTANT!

You must select Show (count) technical items to show all installed lenses. e.g. The "shopping lens" is a technical item, which personally I think is a little bit cheeky. You know, because you're too dumb to know what that is.
Don't select "Installed" and then search for "lens". This doesn't do what you might expect. It should list any "installed" len's, however it doesn't do that. Probably a bug.

What lenses do I recommend uninstalling?
All of them except for unity-lens-applications and possibly unity-lens-files. Personally I'd be happy a great deal happier without the dash. In place of which was a simple, straight forward, no messing, fast-as-possible, application launcher. I can't belive I'm about to say this, but there's actually something I miss about windows.
Note on 14.04 You can't remove unity-scope-home  without remove the unity-desktop and breaking the entire system.
Additional Information

I have permanent connections to Canonical servers, what are they for?
Comment: I agree. When I first started using Ubuntu, what I loved about it was its simplicity and speed. And If I'm not mistaken Unity is made to provide a straight forward environment in which can get your work done. I think Unity is moving away from its goals. I love the fact that I have a lot of options, but I wouldn't want to sacrifice speed or simplicity in return. I really disliked the "internal error detected" popups in Precise(isn't that one of the reasons people don't like Windows??). And the new ads on Quantal, with terms of service, I don't like this.
Comment: This doesn't seem to work for me on **14.04 Trusty**. I have uninstalled all lenses except for `unity-lens-applications` but they still show up in the dash. Any ideas?
Comment: @nifr Disabling it using the `unity-tweak-tool` still works: http://askubuntu.com/questions/107701/how-to-disable-lenses-in-the-in-the-dash-menu/375953#375953
Comment: @nifr Whar still shows up the dash? There are many more scopes and lenses in 14.04 than what I've described above. What does `dpkg -l | egrep "(lens|scope)"` show? e.g. you can't uninstall the  "home" scope i.e. `unity-scope-home` without uninstalling `unity-desktop`. Also, when removing the one's that you *can* uninstall, purge `apt-get remove --purge `
Comment: @nifr I've updated the answer with some notes on 14.04.
Comment: Thanks for the update :) Sadly it's not possible to disable i.e. the shopping lens by just uninstalling a simple package anymore in 14.04.
Answer: If you're using Ubuntu 13.04 or newer:
sudo apt-get install unity-tweak-tool

In the tweak tool you can use the search tab to modify the relevant settings:

Uncheck "Search online sources"
Uncheck "Show more suggestions"
Uncheck "Enable search of your files"
Answer: Uninstalling the lenses does not work in 14.04.
What works is:

install dconf-editor
remove scopes from the strings in com -> canonical -> unity -> dash. I left only home.scope in there.
logout, login, enjoy.

(From here)

You can also do it without installing dconf-editor. Edit the string with double quotes to your liking:
$ dconf write /com/canonical/unity/dash/scopes "['home.scope', 'applications.scope', 'files.scope']"

(From here)
Answer: Here's a small package I whipped up if you're comfortable with either setsid unity or logging out
Comment: Great tool. Unfortunately I have not found a way to disable the cities scope within the utilities scope as it often crashes on my system (Ubuntu 12.04 AMD64), but the calculator scope is very useful and I want to keep it.
Comment: It doesn't manipulate scopes directly...just lenses
Comment: Thanks for the explanation. Do you know a way to manipulate scopes?
Comment: If you wanted to do that, you'ld have to modify all the lense descriptions or hijack the dbus calls depending on exactly what you wanted to do.  If you want to chat about it...pop in to the chat room
Comment: Thanks for the explanation and offer. But this would take up more time and efforts than I would spend on this issue. Thanks again.
Answer: In Ubuntu 14.04LTS

Press Super-A to bring up the Applications Scope
Scroll until you see the Dash Plugins Header
If not already clicked, click the Show more results button
For each plugin you'd like to disable, click it, then click disable

I prefer this method because it doesn't require super-user privileges, thus, it is less likely to break anything.
Answer: I would imaging that the easiest way of doing this would be to uninstall it, logout and login. It would still be in the cache if you would like to install it again later on.
If you on the other hand do not want to uninstall it and want to just make it go away from the Dash you could just move it out of the /usr/share/unity/lenses folder.
For example let us say you have install the Askubuntu Lense like me.
you would then have a folder inside /usr/share/unity/lenses called extras-unity-lens-askubuntu/. Move that folder somewhere else. Logout. Login.
An example:
cd /usr/share/unity/lenses
sudo mv extras-unity-lens-askubuntu/ ..
This would move the askubuntu lense from the lense folder to the parent folder. If you logout/login, the askubuntu lense will be gone.
UPDATE - As aking1012 points out, typing setsid unity will "refresh" Unity with the changes.
Comment: just a note, if you `setsid unity`, you don't have to log out
Comment: `setsid unity` doesn't work for me. All windows decoration disappeared and the program didn't exit. It force me to `Ctrl+C` and `gnome-session-quit` to logout.
Comment: `setsid unity` removes all window decorations and doesn't exit on **14.04**, too. Any suggestions how to debug this behavior?
Comment: @BornToCode I would guess a bug or misconfiguration. Last time I tested this was a year ago. Maybe you can provide more information about yout system.
Comment: I use Ubuntu 13.04, last updated about less than a month ago. I think this go out of the topic, and I'll be kicked if the discussion go further :D.
Answer: Just open the terminal and exec this (without sudo):
gsettings set com.canonical.Unity.Lenses disabled-scopes "['more_suggestions-amazon.scope', 'more_suggestions-u1ms.scope', 'more_suggestions-populartracks.scope', 'music-musicstore.scope', 'more_suggestions-ebay.scope', 'more_suggestions-ubuntushop.scope', 'more_suggestions-skimlinks.scope']"

How to disable lenses in the Dash menu?


pattern matching

Question: Consider the following rules:
register *
delete *
suppose now if I send a message to the application (via mobile using SMS) that will match the rules

register Leon Eric

now we have two parameter Leon and Eric and the application
 will assign %P1% for Leon and %P2% for Eric , for further use.
it can be more parameters every parameters have its variable %P1% %P2% %P3% .... %Pn%
the application will reply a custom message that can be changed by the user :
Thank you %P1% %P2%  for your register.
since %P1% is Leon and %P2% is Eric
the message will be "Thank you Leon Eric for your register."
my questions :
What is the best technique I should use with this situation is it regular expression?
I tried to use the regular expression to extract the parameters  but how to group every
 parameter  with name %P1% %P2% ….%Pn% for further use.
register.? (.+).?
What is the best technique I should use to replace the message that have an argument with
the parameter that the regular expression assign ?
For example:
Thank you %P1% %P2%  for your register.
"Thank you Leon Eric for your register."
thank you very much
Comment: lol, I can't even read this question
Answer: You don't need any regex here, just use %* to list all parameters:
Thank you %*% for your register.

pattern matching


Which lens is better: Canon 70-300mm 4-5.6 or 50-200mm?

Question: For use on a Canon 600D, primarily for travel, landscapes, macro and subjects in motion.
An additional consideration: if I go with the 50-200mm I could also afford a 50mm lens.
Comment: As per @theSuda's answer, could you be more specific about which 50-200 lens you are referring to?
Comment: This question is not a good fit for this website, especially with the lack of detail and no evidence of effort on your part. See http://blog.stackoverflow.com/2010/11/qa-is-hard-lets-go-shopping/
Comment: What does "better" mean to you?
Answer: This question is one of the 'Which one is better" types and so most probably would be frowned upon by this community. ;)
I had not heard of a 50-200mm lens till I read your question today. I guess you are referring to Sigma 50-200mm f/4-5.6 DC OS HSM Canon mount.
I would only suggest one thing from my personal experience, consider Canon 55-250mm instead of Canon 70-300mm. It is proven to be best of the low price zoom lenses.
I am not aware of anything about 50-200mm other than it is relatively cheap. But looking at your requirement, I think 55-250 is perfect for "travel photography/ landscapes / macro and subjects in motion" because of its sharpness, reach and versatility(to some extent).
Answer: Alone, none of them:

Travel photography - it depends where you are traveling to, but typically for single lens solution you want something that can cover both the wide end and the telephoto end (something like the 18-200 or the 18-135, note those are not the highest quality lenses out there)
Landscape - landscape photography is traditionally done with a wide lens, both lenses are too long.
Macro - both lenses don't do macro at all
Subject in motion - this depends too much on the subject, how you want to  stop/show motion and lighting conditions, can't really comment on this.

Those lenses can work well in a two lens kit with a wide lens (but not the 50mm, on a crop sensor that's also too long, you need 35mm or wider).
Answer: It is not clear from your question exactly which two lenses you are referring to. Canon currently sells or has sold in the recent past: EF 70-300mm f/4-5.6 IS USM, EF 70-300mm f/4-5.6 DO IS USM, EF 70-300mm f/4-5.6L IS USM, EF 55-200mm f/4-5.6 II USM, EF-S 55-250mm f/4-5.6 IS, and EF-S 55-250mm f/4-5.6 IS II. Additionally, Canon has offered several versions of the 75-300mm f/4-5.6 lens. Sigma once made a 50-200mm F4-5.6 DC OS HSM. The Nikon mount is still readily available, but the Canon version is getting a little harder to come by. Some of these lenses are significantly different than others.
Assuming you want to compare the EF 70-300mm f/4-5.6 IS USM to the EF-S 55-250mm f/4-5.6 IS II, for your 600D I would recommend the 55-250. Following is part of my answer to another question that applies here.

The difference between EF and EF-S lenses. AN EF lens must project an image circle large enough to cover a "full frame" sensor or film negative (roughly 36X24MM). An EF-S lens must only project an image circle large enough to cover the Canon APS-C sized sensors that are approximately 22.5X15mm. Since the APS-C image circle is only about 40% the area of an EF image circle, this allows the lens design to be smaller and lighter. Another benefit is that some of the lens elements themselves can be smaller, and thus use smaller amounts of the expensive materials used in modern lens design. In the case of these two lenses, the 55-250 can use smaller amounts of higher quality materials and still be manufactured for a very reasonable cost. The 55-250, while not outstanding, performs much better optically than the 75-300. It is much more comparable to the more expensive EF 70-300mm f/4-5.6 IS USM in terms of optics.

You will get roughly the same optical performance and a more usable focal length range for your 600D in a smaller, lighter lens at a lower price.


Other users can edit my questions?

Question: I'm pretty new to Ubuntu, and to these forums and one thing that I have found to be a bit disturbing is that other people (including myself which is more oddness) can edit other peoples questions.
Is this true? Why?
Isn't that a super terrible idea? Not to mention, how is it that I have to have 50 rep to comment on a question but apparently I need 0 rep to edit someone else's question. Doesn't that also seem terribly backwards?
Comment: This is clearly spelled out in the FAQ's, in the section called '[Other people can edit my posts!?](http://askubuntu.com/faq#editing)' Have a look at all the FAQs, they are well-written and for your benefit.
Comment: Why do you think it's a bad idea? What drawbacks can you think of?
Comment: Haven't been on the meta for a while. I can think of some pretty obvious drawbacks: what protection do I have that an editor won't "edit" the fundamental basis of my question and thereby invalidate my entire purpose for asking it? I guess more broadly, to be cliche, who shall watch the watchers?
As someone pointed out below edits can, and do, lead to positive results but wouldn't the opposite be far more common and likely?
Comment: Also, I can see editing *answers* for accuracy and validity, but neither is necessary for a question.
Answer: You need a minimum of 1 reputation to suggest an edit. When an edit is suggested, what happens is this:

it goes into a review queue where it takes 2 trusted community members to agree that it is a good edit. A trusted community member is someone who has managed to earn more than 2,000 reputation (this is not to be confused with the "trusted user" status you can earn at 20,000).

Also, your content here is under a Creative Commons license, so you don't really have a choice. Everyone needs to be able to edit your questions and answers to fulfill the letter of the license. For more information, take a look at the FAQ.
https://askubuntu.com/faq#editing
Lastly, edits are designed to be used for the purposes of updating, fixing invalid information, improving formatting for readability - and that is what it is used for.
Comment: @Flimm I meant the original poster by "you" - the writer doesn't have a choice, their content is (by the license that they submitted it under) editable.
Comment: @ObsessiveSSOℲ Suggesting an edit doesn't *use up* any reputation. Just as [15 rep](http://askubuntu.com/privileges/vote-up) is required to upvote but upvoting doesn't cost any rep, we say 1 reputation is required to suggest edits. Since all users (even unregistered users, whose edit suggestions are submitted anonymously) have at least 1 reputation, this is just a way of saying that anyone who can use the site can suggest edits.
Comment: I do not think StackExchange is obliged to provide wiki functionality just because the content is licensed under CC-BY-SA. CC-BY-SA means people can copy and modify the content keeping the same license, but it doesn't mean anyone is obliged to allow users to modify content hosted on their servers.
Comment: I've never seen the behavior of investing one rep to suggest an edit. Is this new? Or long-gone?
Comment: @EliahKagan Oh, I see now. I was reading it incorrectly.
Answer: Some people Downvote for silly reasons, it may be an offhand comment in the question (funny but otherwise not essential to the question) or something else...
By editing we can make it easier to read and less likely to offend, clear up mistakes or parts that people would confuse, like in @jrg's answer http://meta.askubuntu.com/posts/5681/revisions , many times a simple edit can turn around a question, and impact it positively.

Other users can edit my questions?


Combining two Google Analytics scripts

Question: I´m trying to combine two Google Analytics scripts, _trackEvent and _trackPageview.
My questions is, how do I write this in one single script?
This works fine
<a href="www.link.com" onClick="_gaq.push(['_trackEvent', 'Button', 'Category', 'Product']);"Text

Now I need to add following script below:
Text

Does anyone have a working solution for this?
Thanks in advance!

See my code below, an event is created correctly in Google Analytics, also a content page is created, example "/virtual/products/abc", but it dosen´t effect goal tracking in GA at all, which is odd.
If I remove _trackEvent code, the _trackPageview works, so I guess Im still struggling how to combine this two Analytics events with HTML correctly.
Link text

Thanx in advance,
/Fredrik
Answer: One Push, Multiple Commands
_gaq.push(['_trackEvent', 'Button', 'Category', 'Product'],['_trackPageview', '/virtual/page/productA']);

Combining two Google Analytics scripts


Did not detect Micromax MMX353G netsetter

Question: I had Micromax MMX353G net setter, but it did not detecting on Ubuntu 12.04 onwards versions even in Ubuntu 13.04. And also I try to connect with Sakis3G  (http://www.sakis3g.org/) script run through Terminal. Please help which version Ubuntu OS is best all over ?
Answer: Open terminal using Ctrl+Alt+T and write this code:-
sudo gedit /etc/modules

Press Enter
It will ask for your password, put it and press Enter then write these
usbserial

press Enter
option

press Enter
Now restart your system. After it open terminal and write
sudo modprobe usbserial

press Enter, give your password, press Enter then type
sudo modprobe option

press Enter. close the terminal. now connect your modem with the usb port. Wait for few second, and now you are done.


How much is the world population expected to grow in the next decades?

Question: What does science say about the expected growth of the human population in the next decades?
Answer: Currently we have over 7.7 billion people in the world (data from April 2019). In 2010 the UN made several projections for world population growth.

World population estimates from 1800 to 2100, based on "high", "medium" and "low" United Nations projections in 2010 (source wikipedia).
The worst case scenario (red line) is that the world population will continue to grow and we'll have about 10.5 billion people in 2050. The best case scenario (green line) is that the population will stop growing soon and we'll have a peak of 8 billion people somewhere around 2045.
The UN scenario that is generally thought to be the most plausible is that the world population will continue to grow to around 9.3 in 2050 and 10.1 billion people at the end of the 21st century and then remain stable (the yellow line).
However the 2012 revision of these figures changed these 'most likely' numbers to 9.6 billion in 2050 and 10.9 billion in 2100, and in the 2015 revision the numbers were raised to 9.7 and 11.2 respectively. In the 2017 and 2019 revisions the numbers changed slightly (see table below).
<code>                   2050    2100
--------------------------------
1994 revision  |   9.8
2000 revision  |   9.3
2002 revision  |   8.9
2010 revision  |   9.306  10.125
2012 revision  |   9.551  10.854
2015 revision  |   9.725  11.213
2017 revision  |   9.772  11.184
2019 revision  |   9.7    10.9
</code>
Table 1: UN (medium) projections of the expected world population in billions of people
A statistical study published in 2014 says that the UN projections are inaccurate and claims that

There is an 80% probability that world population, now 7.2 billion people, will increase to between 9.6 billion and 12.3 billion in 2100

On the other hand, critics on this new study say that it doesn't take improvements to female education in Africa into account, which is a key driver in (slowing) population growth.
Sources:

1994 https://books.google.nl/books?hl=nl&id=85zBAAAAIAAJ
2000 http://www.un.org/esa/population/publications/wpp2000/highlights.pdf
2002 http://www.un.org/esa/population/publications/wpp2002/WPP2002-HIGHLIGHTSrev1.PDF
2010 https://www.un.org/en/development/desa/population/publications/pdf/trends/WPP2010/WPP2010_Volume-I_Comprehensive-Tables.pdf
2012 https://population.un.org/wpp/Publications/Files/WPP2012_HIGHLIGHTS.pdf
2015 https://population.un.org/wpp/Publications/Files/Key_Findings_WPP_2015.pdf
2017 https://population.un.org/wpp/Publications/Files/WPP2017_KeyFindings.pdf
2019 https://population.un.org/wpp/Publications/Files/WPP2019_10KeyFindings.pdf
Comment: Would be cool to include some older UN predictions in this (e.g. from the 80s or 90s) to see how they've panned out, and to compare the assumptions to the current projections.
Comment: The two extreme projections say essentially nothing, and are probably impossible. If numbers keep increasing, things are not looking good. How can we make the green line actually happen?
Comment: @naught101 I've been able to find data for 1994, 2000 and 2002 and added those to table 1


Citadels Bell Tower and end game conditions

Question: Can I put the bell tower card down if I don't have seven district's but another player does? I'm asking because I just played for the first time and I made this move and ended the game without wanting to be the winner by points.
Answer: If you can pay for the district card (and don't already have it in your city), yes, you can build it. You can do this whether or not you have seven districts and whether or not another player has 7 districts.
When you do, you MAY announce that the game will end at seven districts (but you don't have to).
Card text (from Dark City expansion version in 2008), emphasis added :

Bell Tower
  Purple - Cost 5
  When you place the Bell Tower in your city,
  you may announce that the game will end after the round in which a
  player first places his seventh district. You may do this even if the
  Bell Tower is your seventh district. If the Bell Tower is later
  destroyed, the game end conditions return to normal.

If you do announce it, then yes, the Bell Tower in play and another player having 7 districts will end the game, yes.
If you don't intend to end the game at this time, though, you're free not to announce the change to 7.
EDIT: Regarding the "MAY" indicating that the effect is optional (see comments, where it was suggested that "not announcing would be so you could pull it out as a surprise, not that not announcing meant it didn't happen."):
Yes, not announcing it means not changing it. Otherwise it wouldn't be worded with "may announce" at all, but rather with something like: " The game will end after the round...seventh district. If the Bell Tower is destroyed, ... return to normal." (This would also run counter to every other district: there are no hidden effects. "play from the table, not from your chair" as the hustlers say.)
If you want to get really lawyery with the text, you could wrangle out that there's no change at all even if you do announce: the text allows you to announce but has no text saying that the rules actually change. (although it does have text that will "return to normal" from this non-change). No one but lawyers would believe that line of reasoning, of course, but it does help illustrate the effect of the text as written.
The only other place I could find that addressed the question (either in agreement with "optional" or not) is this post on BGG , which agrees:

The fact that the text says "may" indicates that using the district's
  ability is optional; however the fact that it says "When you place
  ..." indicates (to me) that you can only do this whan the district is
  built - if you don't do it then you have passed on the card's ability
  forever (well, for the duration of that game).
Comment: Yes, not announcing it means not changing it. If it worked as you say, then it wouldn't me worded with "announce" at all.  I'll edit my answer for more...
Comment: Does not announcing it change anything? I always assumed not announcing would be so you could pull it out as a surprise, not that not announcing meant it didn't happen.


What type of tenants' rights does a student renting from privately-independently owned student halls have?

Question: Suppose a private student housing company maintains student halls for students to book into and live in, but they only accept bookings from university students, though they will accept  students from any university and are not  specifically associated with any one university in particular. Suppose that Alice, a student at the university of Leeds, decides to rent an accommodation from them. What type of tenancy would she have and what statutory terms and protections to it would apply?
Answer: They have a common law tenancy. Generally, in most cases where they don't live with a landlord, this means that a court order will be required to evict them.


About double negative sentences problem

Question: 'This is a not uncommon mistake.'
'This is not an uncommon mistake.'
Are those sentences above both means 'This is somewhat common mistake.' ?
or could they have different meanings?
Comment: Changing word order in such a minimal way (moving the article) doesn't change the sentence meaning. They mean exactly the same thing. And, yes, your correct (kind of). Somewhat common is probably more common than not uncommon. I would estimate that common > somewhat common > not uncommon > uncommon.
Comment: From memory, I've noticed 'uncommon' only in contra-distinction…

Is that common?

Not really, but it's not uncommon
Answer: This is a way of saying that "it" could be described as common or of average frequency/supply, but that the only thing they can say with confidence is that the the frequency at which something occurs, or the amount of something that exists, is not below average.
These statements have to do with the fact that its not so black and white. Things are not all either common or uncommon. Sometimes the amount of something is not notable at all (it is not oddly plentiful or oddly rare). Common generally means notably more than average, uncommon generally means notably less than average. The averages in question are usually largely contextual. And, of course, things can only be common or uncommon relative to their rarity in other areas.
It's a way of saying "I wouldn't say they are common, but I definitely would not say they're notably infrequent or rare". Another way of saying it: "you might regard the mistake as common, but I don't feel that safe calling it common. I would not call it uncommon, either, however."
Hes basically saying "the frequency with which it occurs is not noteworthy to me" or that he does not know much about the frequency, but that he does feel he knows enough to say that it would not generally be perceived as being uncommon. He does not personally think of it as particularly rare OR abundant (either because he thinks its average or because he simply doesnt know enough about it) but he believes it wouldn't be too much of a stretch to call it common.

About double negative sentences problem


How many generations to breed a goat that would be strong enough to carry the weight of a man

Question: How many generations or years would it take to create a ridable goat? What about sheep or rams, etc?
Comment: You have probably already been told, but repetita juvant: science based tag cannot be used alone. That apart, some context is missing here.
Comment: The large-ish (such as the [musk ox](https://en.wikipedia.org/wiki/Muskox) *Ovibox moschatus*) and small-ish (such as sheep and goats) lineages of the Caprinae family diverged some 20 million years ago, in the early Miocene. No better estimation is possible, unless somebody actually puts in the work and actually trieds to do it. I am not sure why you would believe that it would be possible to estimate the necessary time span without actually doing the experiment.
Comment: P.S. Humans have been selectively breeding dogs for some 15,000 years, and the largest dogs are still nowhere near large enough to serve as mounts.
Comment: @AlexP - [Are you sure?](https://www.youtube.com/watch?v=OYiKVVny_3E)
Comment: Do breeders have access to DNA-sequencing technologies or not? And if they do, how much knowledge about the animals' genomes do they have?
Comment: There's a lot of missing information. Tech available, knowledge on breeding and evolution, how much "help" in evolution do you expect... It's possible to answer, but it'll most probably leave you unsatisfied :/.
Answer: Well, since no one tried it, this question does not have an exact answer. So let's guesstimate!
As of now, the goats in our world does not fit for riding. This means we need to introduce all kinds of changes to the goats' bodies - wider backs, stronger skeleton and muscles.
For this guesstimate, we'll assume no gene-editing - just picking the fittest male & female in hope that their offspring will be even more fit for human riding.
According to the wiki, goats reach puberty between three and 15 months of age. So let's say a new generation each year.
If I understand this article correctly, it took humans about 1,500 years to ride horses - but their bodies were already adjusted to that. On the other hand, they didn't know anything about evolution and their knowledge about selective breeding was far from ours.
So my guesstimate is that if people know what they are doing, this journey will take about 2,000-3,000 years. If they don't know, it'll be much longer.
If they use CRISPR and other advanced gene-editing techniques, probably much faster.
Comment: One could use knowledge of genetics to speed up selective breeding without resorting to genetic modifications. If we know which genes and alleles we need to reach the desired effect, we can test all animals for these genes and use them for breeding. We repeat this selection until we have a population that reliably has needed genes.
Answer: Goats can carry men today!
From my personal experience with goats, they can weigh up to 300 pounds, and carry about a third of their weight. So, they could carry a 100 pound man.
I wouldn't want to ride a goat. They're noisy, rude, and they are not really bred for carrying people, so you'd need a very good harness to distribute the weight well.
You'd need to find larger goat breeds, and selectively breed them with the best pack goats to get a better weight ratios, but within five or so generations you should be able to get some improvements.


Are conformal, Killing and homothetic vector fields the same in pseudo-riemannian manifolds?

Question: I work in the Lorentzian manifolds, more generally in pseudo Riemannian manifolds and applications to general relativity.
I know the definitions of conformal, Killing and homothetic vector fields in Riemannian hypersurfaces. Are these quantities defined in the same way in pseudo riemannian hypersurfaces? What is the physical significance of these quantities?
Comment: Killing fields are definitely described the same way, and are physically deeply important, as much of the physics of a spacetime is governed by the symmetry of that spacetime, so a great many theorems will be dependent on the presence of a Killing field satisfying various properties.
Comment: thank youvery much I arrive to understand some of them, thank you again.
Answer: The definitions work for arbitrary Riemannian manifolds (not just hypersurfaces) and generalize to the pseudo-Riemannian case - after all, they are pretty general statements about the Lie derivative of some tensor field.
In general relativity, there are many interesting vector fields (sometimes called collineations), considered infinitesimal symmetries of geometric structure or physical quantities like metric, curvature and energy-momentum tensors, geodesics and light cones.
They might be interesting for physical reasons, or just technical ones to make the equations more manageable.
Assuming I did not mess up (no promises), we get the following map where the sets of vector fields are related by inclusion:
<code>         Killing
            |
      +-----+-----+
      |           |
      v           v
   matter     homothetic
                  |
            +-----+-----+
            |           |
            v           v
          affine    conformal
            |
      +-----+-----+
      |           |
      v           v
 projective   curvature
                  |
            +-----+-----+
            |           |
            v           v
         Ricci        Weyl
</code>
Killing vector fields preserve the metric and all derived structure, including the energy-momentum tensor assuming the Einstein field equations hold. A physical application would be the definition of Komar mass for spacetimes with a time-like Killing vector field.
A matter collineation is a vector field that preserves energy-momentum, but not necessarily any geometry.
Conformal symmetries preserves angles and in the pseudo-Riemannian case in particular the sign of scalar products, which is relevant for the light-cone structure and thus causality.
Affine vector fields preserve geodesics including their affine parameter (multiples of proper time), whereas projective vector fields don't necessarily preserve the latter.
Curvature collineations preserve the Riemann tensor, whereas Ricci and Weyl collineation only preserve Ricci and Weyl tensor, respectively.
I'll leave particular applications to people more knowledgeable than myself.
Comment: thank you friend you gave me more that I hope, than you again I hope that we will keep us in contact


Can the Doctor's daughter regenerate?

Question: In the episode The Doctor's Daughter, Jenny was named as The Doctor's "daughter". She was the progenation of The Doctor, a direct descendent. Is it possible then for Jenny to be able to regenerate? The show doesn't say it outright in the episode. Does it say it somewhere else? Would it be safe to assume otherwise?
Comment: Unless I am much mistaken, she did regenerate.  What with the being dead and then being alive again.  Or do you mean take a new form?
Comment: I mean take a new form, but both, really if they are in fact one in the same. [This question](http://scifi.stackexchange.com/questions/7995/how-did-jenny-come-back-to-life-without-regenerating?rq=1) should do the trick about her regeneration.
Comment: She appears in a bunch of EU novels, audiobooks and comics. At no point does she regenerate.
Answer: Who knows? The mechanic's rules aren't explicit, but they are definitely changing.
In Old Who, regeneration was implied/outright stated (depending on your admission of novelizations to your own personal canon and your interpretation of certain lines in the show) to be a biotechnological ability, not an inherent feature of Gallifreyan biology. It was granted to Gallifreyans upon proving their worth (passing tests) and was part of becoming a Time Lord. (That Time Lords were a Gallifreyan (bio)technologically-privileged upper class was undeniably stated in the show.)
During this time, the specific mechanics of regeneration weren't made clear but based on what we saw it consisted of a complete biological revision/reshuffling; if you regenerated, you got a new body, and that was the way it was. The original concept (never stated onscreen) was that regeneration returned the Time Lord to a younger version of himself. At any rate, the biological revision was the healing process, not something that happened after it fixed your existing body.
(Also, control over the process --that is, deciding what you looked like-- was implied to be possible if you triggered regeneration deliberately but not if it was an automatic response to lethal trauma.)
In New Who, we've seen additions to the concept such as (spoilers!):

 - A Time Lord continues to heal damage sustained during the post-regeneration afterglow --including the regrowth of lost body parts-- without further biological revision, not unlike a D&D 3.5 troll's regeneration ability.
 - The regeneration process can be redirected into a suitable receptacle after allowing it to heal the triggering damage but before it makes any revisions to the subject's biology.
 - A regeneration can affect non-Gallifreyans by proximity.
 - A part-near-human clone of a Time Lord can revive from death through the use of automatic regeneration-like powers without changing her appearance --despite the lack of a suitable receptacle to shunt the energy into, which was Ten's excuse, and despite the fact that the Doctor has repeatedly said (in New and Old Who both) that sudden death is still permanent death: regeneration needs a window of opportunity to function in. (We'll let The Movie sit by itself on that one and pretend that the "anesthetic" handwave provides justification for an awesome scene.)
 - Regeneration can have a physically violent effect on the immediate environment.
 - A human conceived in the TARDIS while in motion through the Time Vortex can have full Gallifreyan DNA (seriously?) and this means she also has the full regeneration features including healing, body alteration, and afterglow immunity --as well as at least some control over her appearance even when the process was triggered automatically.

So... who knows what the Doctor's Daughter (whose DNA is part near-human as well as part Gallifreyan) is capable of? The rules for regeneration (both how it works and how it's acquired) were never made clear and are now being changed in ways that definitively contradict what was previously stated.
Doctor Who was never attached to a firm canon anyway, although it does delight in making continuity references. While Old Who's internal consistency was maintained --as much as it was-- largely thanks to its being content to simply wave its hands and move on, New Who is much more inclined to try explaining things, and that gets it into trouble.
Comment: "New Who is much more inclined to try explaining things, and that gets it into trouble" So very true!
Answer: I would says she could definitely regenerate because at the end of the episode you see regeneration energy flow out her mouth, like it did after the 9th Doctor regenerated into the 10th Doctor.
Comment: Is there evidence to suggest the regeneration energy is something only those that can regenerate can have flow out of their mouths?
Answer: Possibly. I mean though Martha said she probably couldn't, it's still a possibility. When she came back to life at the end of the episode, it wasn't really a regeneration, because she would've let out all that golden energy, and change her face (I think it was something to with the Source). After all, Time Lords can't regenerate when they're dead. This is demonstrated by both the Master and the Doctor.
Answer: I guess we just don't know.
At the end of the episode she did not regenerate, she was brought back to life by the Terraforming process which was also rejuvenating Messaline.
My first opinion would be that she can, as she is his Daughter, but the episode seems to show that she cannot.
Maybe being exposed to Artron Energy might help wake up her Regenerative abilities.
Maybe her Regeneration Energy is like dormant at first.

Can the Doctor's daughter regenerate?


Conditional Formatting of maximum value in each row of many

Question: I have a spreadsheet with 250+ rows of data and need to find the largest value in each row. I tried to use Conditional Formatting, however I need the same rule for each row so can't highlight all the data, and trying to copy and paste it would be too cumbersome.
Is there a faster way of applying the same rule to each row separately?
Answer: Please select he relevant columns (say A:H) and HOME > Styles - Conditional Formatting, New Rule..., Use a formula to determine which cells to format and Format values where this formula is true::
<code>=A1=MAX($A1:$H1)
</code>
Format..., select your choice of formatting, OK, OK.
If you want the formatting to stop when there are no values in the row adjust to:
<code> =AND(COUNT($A1:$H1)<>0,A1=MAX($A1:$H1))
</code>
Answer: Formula: =A1=MAX(A:A)  (don't use $)
Applies To: =$A:$D

To shift columns, change the starting point of the formula AND the "Applies To" range.
Formula: =C1=MAX(C:C)  (don't use $)
Applies To: =$C:$F

Formula: =A2=MAX(2:2)  (don't use $)
Applies To: =$2:$11
*Shift first row down to adjust for header row

Finally, as pnuts shows in the post above, to correct for cell overflow into blanks cells/rows/columns (shown here)

Use the following variation:
(the same for rows/columns and MIN/MAX)
Formula: =AND(COUNT(C:C)<>0,C1=MAX(C:C))  (don't use $)
Applies To: =$C:$F


Historic flight date from 2001

Question: I am trying to find details of an Uzbekistan Airways flight from Tashkent to London on September 11th 2001. I believe it took off in the morning and landed in the afternoon but I need to know the flight number, departure and arrival times, type of plane, terminal it landed and whether it was delayed.
Do you know where I can find this information?
Thanks,
Toby
Comment: Is this related to some "weird fact" or "mystical story" about 9/11? If you could say this this would maybe make the question easier.
Comment: Flight stats only goes back to 2006
Comment: Not a weird fact! Simply that I am working on a book project that involves the US response to 9/11 and I want to describe exactly where the main characters were that day. One told me he was on this flight and therefore was in the air when the attacks in New York and DC happened.
Answer: This might be better-suited to Aviation.SE or even History.SE as it does not seem to pertain to the needs of a current traveler, but I will say it will take non-trivial effort to confirm flight information from as long ago as 2001.
OAG, the database company that powers almost all airline schedule and flight status information in the world, only has historical flight data going back to 2004. Even aggregated FAA statistics on flight delays and cancellations are only available from 2003, much less for an individual flight.
Historical flight schedules will probably be easiest to locate, even without an OAG subscription. In that era, airlines still published paper timetables, and there are many people around the world who collect them now as memorabilia, and who post scans or photographs of them online. If a PDF timetable was available, someone probably has a copy of it as well. The timetable will usually provide flight numbers, scheduled departure and arrival times, stopover points, equipment types, and meals served.
You might similarly be able to identify the aircraft used because planespotters may have recorded the tail number, although this is obviously very hit-and-miss, especially for smaller airports and smaller airlines.
You can probably make an educated guess as to which terminal the flight operated from based on historical information about the flight and about the airport itself.
But as to whether a specific flight operated and whether or not it was on time, and whether it operated with its normally scheduled crew and aircraft from its normally scheduled terminals, is another matter. You may have few options except to contact the airline itself and ask if it can look up this information for you, or perhaps hope to get in touch with a crew member, airport worker, or other passenger who might have recorded such information in a personal journal and thus be somewhat more reliable than one person's memory.

Historic flight date from 2001


How do miners profit post-PoS, if at all, how will new miners get their start, and who will execute the EVM byte code (and why)?

Question: I've been following the release of Casper/PoS closely, and I'm curious about a few details.

How will miners make money (even if GPUs are less valuable)? Are spare compute resources (say RAM, CPU) still somehow "usable" to create value by securing the block chain in a PoS world?
How will miners new to Ethereum gain a foothold if they start with no stake and have no ability to mine their first ETH coin?
If spare computing power isn't the resource that drives mining, who will be incentivized to participate? Will the mining/consensus system be entirely driven by users of the network, who hold ETH for other reasons entirely (e.g. users of ETH-powered contracts)? And if so, how can they simultaneously use their ETH to power contracts, collateralize contracts (potentially), and simultaneously serve as a "deposit" for Casper?
Who will execute the contracts/EVM bytecode?
Does PoS make computing power no longer "redeemable" for financial value using the Ethereum block chain?

Thanks very much, and looking forward to the next gen of Ethereum!
Comment: The 5 parts of his questions are so closely related and are different aspects of the same thing that I doesn't make me feel bad to see it in a single question. So I won't recommand splitting.
Comment: Welcome to Ethereum Stack Exchange! It is preferred if you can post separate questions instead of combining your questions into one. That way, it helps the people answering your question and also others hunting for at least one of your questions. Thanks!
Comment: I read but not clear. After POS, how to create new blocks and who will do it when all miners to stakers?
Comment: Will someone staking say 100 - 200 ETH have any incentive under this system? Or will it only be worth while to those holding thousands or tens of thousands? Once all ETH has been released/mined, where will the ETH come from to reward those staking under PoS? Thanks in advance for clarifying
Answer:
Miners will receive transaction fees, along with (potentially) a small block subsidy. GPUs will no longer be useful, and CPU/RAM will be useful in that stakers will need to have close to perfect uptime and fast servers in order to make money.
They will have to buy ETH, and stake it.
The stakers will have to put down a deposit(stake), that cannot be used for other purposes while it is staked. Stakers will likely be professionals, much like how mining pools are now.
Similar to today, the miners/stakers  will execute the contracts and build the blocks, and each node will verify the computation in order to be sure the block is valid.
Essentially, yes, although fast servers are needed for processing transactions at the higher rate that Casper allows.
Comment: 4. except there is no need for nonce anymore is it. and THAT, saves the planet.
Answer: EDIT: This answer is a bit old. Now we know much more about PoS and validation details, but don't hesitate to ask new questions on a new thread.
Also, meanwhile Golem Network appeared and is a pretty way to recycle GPUs power (see the end of my answer where I express fear about GPU recycling). GPUs would then be used for what they were built for: rendering and massive calculation. Many other projects may appear and I'm happy that my prediction about people being creative were true ;)

TL,DR: I may look pessimistic about POS but there is a huge chance that people creativity makes something good of it. However there will be a huge amount of GPU to recycle, so we have to find a solution now.

Now the long talk.
As I can see it, POS transition was primarily started to lower the ethereum network power consumption and be more ecological. But the drawback is that tons of GPU will be left useless (even if there is still some POW coins out there, but come on, mining LiteCoin to convert it to ether?) and trashed if not sold. I really mean tons. Really ecological? One may do the math but I don't have the figures to put in the formula. Also POW mining looks to be a more accessible, decentralized and incentive way to be part of a network you care about. Will you be really a part of something ruled by a bunch of big firms that hold ( or hodl) a lot of ether? I think this is the opposite of what ethereum was build for first. But, answering your questions:
1- as I understood it, what we call miners today will be validators. They will exist in limited number as POS is described for now but this may change. So not every people having a node will be rewarded. Only a few big corporations with a lot of stake to participate in POS will be able to be rewarded. The more you have, the more you gain... All our rigs will be useless even for being recycled into POS servers as the need is really different and don't expect to build a high availability powerful server on an Asus btc motherboard. So except if you want to mine some other coins or sell your rig, this is good to trash. (Note that selling rigs and GPU will be nearly impossible when POS will be there due to the gigantic gpu offering opposed to the tiny demand as none will want POW hardware anymore)
2- new miners will have some way to get ether. First one is to buy some at an exchange using fiat currency. This is how most of non miners do today and this is how I stared before being a mining addict :D.
They will also be able to change other coins like BTC or LTC they already have into Ether using an exchange or the now famous and beautiful ShapeShift (I love you guys even if all this hack thing is not completely clear to me... But this is another thread subject).
Note that if a miner don't want to use fiat currency at all, he can mine LTC for instance and then change it to ether. But this is not really efficient, I admit.
There's some other way though. Some can sell goods or services for ether. I already saw a young designer offering logo creation on Reddit for ether.
Gamblers will also be able to win some ether by playing online games like poker. Even if they'll have to put some at first, they will be able to win or loose a lot.
Finally (but not so finally as I may have not thought about anything), you could be rewarded in ether by watching ads or solving captchas for hackers, this is called faucets and I hope it will be eradicated.
3- mining, or may I write validating, will be the only way to create ether from void. So in order to keep the network ether creation rate, POS will have to be attractive. This will be done by giving a few people the ability to invest ether at a really good reward rate (most classical investment in old world won't be able to compete with POS rates). The more they stake, the more they get. As staking ether will lock it for some times, it will probably be people who owns a lot or people who don't want to use it (Holders). But people who have just some ether and use it won't be part of it even if the network works because of them and they create the ether value by using it and using Dapps and contracts. But they are de facto excluded form the reward.
So yes, you will be able to stake and hold and use it if you have enough ether.
4- as I understood it, validators with their huge servers will process all. Full nodes that some people will run will only validate blocks integrity but won't run any EVM code or create new blocks. This is what happens today with full nodes in POW. Only mining nodes run the network. I don't know how light nodes will play in this game. They may only have a read and write access but no integrity validating power at all. Read the light protocol paper for more details.
5- computing power will still be redeemable but not as it is today. GPU power will be almost zero value. But computing power on super servers or on big arrays, grids clusters will be very valuable.
Now the optimistic point:
By that I mean that what would be a more available computer than some standard computers joining together to make a big one always on? This may be the future POS pools. People will join their CPU power using some networked clustering tool and each one will stake some ether in a common wallet contract or some forms of DAO. They will then apply to become a validator as one could be and they will be represented by the contract. The contract will receive rewards and distribute it proportionally to the computing power delivered and by the staked amount of each people as it's done in pools with hashrate.
This is the best scenario I see to avoid power centralisation of the ethereum network.
And the pessimistic message for the end.
But all our GPUs will go to trash anyway.
Comment: "We can't switch over to cars - what will we do with all these buggy whips?"
Comment: They're already made and purchased. Changing to a system that doesn't require them doesn't waste any resources that weren't already wasted - and it prevents further waste. Unless you thought that nobody else will ever add any more processing power than there is now?
Comment: @farinspace Yes it's exactly what I wrote in my answer if you read after "the optimistic point"
Comment: Cars and buggy are not planned to be planet friendly as I now. Here, the question of the waste generated by POS is a real matter in order to build a better decentralized world. This should not be done with a huge ecological depth.
Comment: And by the way whips are only wood and leather... GPU are highly toxic materials with a very long life and recycling them costs a lot of energy and generates a lot of polution in mainly poor countries as India or China. So if you don't care, I do.
Comment: Yes but even it they are already made, if none needs it, they will be trashed. When they are running in your rigs, they are not creating more pollution in the river nearby the recycling zone in a poor country. Building them already generated a lot of wastes, so we should not let them generate more...
Comment: ... (sequel fo my previous comment) and when you say that they are already built, you just ignore the fact that a huge part of the cards were built because of the mining demand. Otherwise do you think AMD would have built so much cards only for gamers ? Do you think they are so bad in calculating gamers GPU market needs  that they built 50 times more GPU than necessary ? Come on...
Comment: And I don't say that we should not move to POS, I just say that we have to do it the right way by taking the miners and existing hardware in account not to generate too much pollution and deceived people.
Comment: They'll still be built, but they won't be consuming electricity. Why do you assume that the only cost is manufacturing? And how could inventing some make-work for the cards to do, again consuming electricity, possibly be better than not using them at all? They won't get any less toxic if you throw them away in 3 years when they're obsolete than if you sell them on to gamers now.
Comment: Do you really think miners who owns dozens of cars will only keep them in a box not to pollute ? Do you think the gaming used GPU market is ready to absorb such a quantity of cards ? Do you think gamers will buy cards that where OC and reached 70°C 24/7 ? I don't. It's however interesting that you talk about a make work project. Do you have any clues on what it could be ? If we could find a way to make something big and useful with all these GPUs this would be nice. This would be a nice way to buy back GPUs (with Ether) and make miners happy.
Comment: Perhaps you can clarify why having them hang around consuming electricity for a few more years before being disposed of anyway is an improvement, then?
Comment: First I'm not saying we have to keep POW and let all those cards running and consume electricity. POS is nice and clearly needed. I only say that we have to care about what all these cards will become. That's all.
Comment: Then I don't understand your point. The cards already purchased are a sunk cost. Inventing some way for them to do something won't reduce their environmental impact - it'll increase it.
Comment: Yes, exactly. We agree on this. Don't try to make me look like I don't agree with you, I do ! But throwing them to trash would be an even more disaster and selling them is not realistic. Keeping them in a box at home is not an option as people need spaces (perhaps for a regular heater, now that they don't have their rig to heat the house). What should we do ? You Google guys should have nice ideas about this environmental problems don't you ?
Comment: I am new to all this but .. What about the possibility of POS pools? It is a risk locking up x number of ETH with a centralized pool. Perhaps POS works with smart contracts, where the ETH get locked in a contract for specific amounts of time, the contracts are what is submitted to a pool. A pool is made up of may contracts all with a variable time rates. Each contract earning percentage of reward.
Comment: NMassart, indeed, sorry about that, lol ... at least, it feels good that my thinking is along the lines of the experts!
Comment: NMassart, your thoughts on creating a decentralized AWS like GPU focused arrays/clusters with pricing rewards for those running nodes? ... so as not to have GPUs going into the trash
Comment: @farinspace Sorry if I misunderstood your comment, I'm not an English native. But in my answer I write about CPU array, not GPU. We all agree that GPU power consumption and heat are both things we have to get rid of. And by the way I'm far from being an expert... really.
Answer: PoS will be the saving force behind decentralization. Currently the wastage is too large to be sustainable. It is currently being driven by speculation.
The idea of mining was to secure the network and it has become a delicate business involving much risk. As an investor into mining technology you should be aware of the implications of PoS.
Bitcoin and all decentralized tech is not about mining it is about the application and usage of that technology and any saving in efficiency can only help it along. "Mining" will now have to shift toward providing more resources to the network and less towards security as the security issues (in theory) are taken care of with PoS, mining will make a lot more sense.


Is this a new form of renewable energy? (sand)

Question: Can we make a machine that takes a mass of sand from the top of a sand dune keeps it in a box.
 Then moves it horizontally until it is hovering above the lowest point near the slipface of the dune.
 Then lets the box containing that sand fall under gravitation while it's kinetic energy is used to run an electric generator.
Next step once it reaches the ground the box opens from below and the let go of the sand in it.
Now raise the empty box up and start again, is such a machine going to turn the gravitational potential energy into electrical current?
Comment: Yes, until you run out of sand dunes, because this machine uses up the sand dunes and makes them flat.
Answer: It's a cute concept, but rather impractical. Yes, you could convert the sand's potential energy to electricity, but there are numerous technical difficulties and inefficiencies. Due to friction, it takes energy to scoop the sand into your box, and it takes some energy to move the box horizontally to the release point, and even the very best generators have losses so they cannot convert all of the potential energy to electrical energy.
This system is only renewable if you do it in a region of active sand dunes, that is, where the wind is rebuilding the dunes at least as fast as your dune machine is demolishing them. And that means there's a lot of wind blowing around a lot of sand. That's not a pleasant environment to work in, and the wind-blown sand will abrade your machinery, and have a tendency to bury it. And your machinery has to deal with the fact that when it wants to move this way, the wind may try to blow it that way. I wouldn't even try to build a standard design wind farm in such an area because there'd be so much wear and tear on the equipment.

But how much energy are we talking about here? Here are some very rough calculations that ignore friction and all the other practical difficulties. Assume each dune is an isoceles triangular prism of uniform density, so the the cross section through a series of dunes looks like this: <code>/\/\/\</code>. Seif dunes are approximately of this form.
Let the width of the base of each isoceles triangle equal $2b$, the height equal $H$, and the length of a dune equal $L$. For most of this analysis we can ignore $L$. Let the base angle of the triangle equal $\theta$, so $H = b \tan \theta$. The maximum value of $\theta$ that a given substance can be piled up is known as the angle of repose. For dry sand that's about 34°, real dunes will generally be much less steep than that, but let's be generous and use $\theta = 34$°.
If we completely flatten the dunes, our triangle of height $H$ and base $2b$ becomes a rectangle of height $h$ and base $2b$. The area is preserved (assuming we don't change the packing density of the sand), so $h = H / 2$. The change in potential energy is equal to the weight of the sand times $y$, the change in the height of the centre of mass. For the triangle the centre of mass is $H / 3$, for the rectangle it's $h / 2$, so $y = H/3 - H/4 = H/12$.
The volume of a dune is $bHL$, so its weight is $bHL\rho g$, where $\rho$ is the density, and $g$ the acceleration due to gravity. Hence the energy available from flattening a dune is
$$\begin{align}E & = LybH\rho g\\
& = LbH^2\rho g/12\\
E & = Lb^3\tan^2\theta \rho g/12\end{align}$$
According to the Coastal Engineering Manual dry dune sand density ranges from $\rho = 1610 kg/m^3$ for loose sand through to $\rho = 1760 kg/m^3$ for packed sand.
Letting $L=b=1$ metre and plugging these numbers, along with $g=9.81m/s^2$ and $\theta = 34$° into Google Calculator we get
Loose: 598.809267 joules
Packed: 654.59895 joules
So if our dunes have a base of $2b = 20$ metres, and hence a height of $\approx 6.75$ metres, if we can flatten $L=1$ metre of dune per second, then we get around 600 kilowatts of power. But of course, then we have to take all of the losses due to friction etc into account. The real available power would be far less. By way of comparison, a typical modern wind turbine has a generating capacity of 1.5 megawatts.
Answer: To be renewable you need to keep renewing the source of the sand at the top.
That is, the sand has to somehow return to the top.  That won't work (as it requires at least as much energy as the fall generated).  If you don't do that you need to fetch sand from further and further away and sooner or later that will cost more energy than it generates.
Note that if you compare this to a water wheel you see that the water wheel relies on the environment to circulate water by evaporation and rainfall which is the "free renewable" part of how a water wheel works.
Your system has the additional problem that the sand will pile up.  If you never move it (which costs energy) it will reduce the amount of energy gained by the fall until such time as the fall is zero height.
Comment: I'd say the environment also creates the dune in the first place and will do it again if the conditions remain. A bid disadvantage of the setup is the time scale involved in the dune buildup.
Comment: @stafusa The problem with that is the environment may move the sand, but it won't naturally move sand to the place you want (or need).  It's relatively easy to control the flow of water from a river or stream (e.g. you can divert it for a low one-off cost) but you can't do anything like this with a dune.  It's where it is and where the sand is ultimately deposited is more random - you may get a "replacement" dune, but it could be anywhere.
Comment: Yes, at least in general you're right, but I wonder if there are some dunes that would be rebuilt in the same place if excavated due to the local geographical configuration.
Comment: @stafusa From an engineering point of view if there was enough energy (=wind) to move enough sand around consistently, we could just build a wind-driven power generator in the first place.  The kind of dune engineering you're describing implies we could create a very reliable wind system I think.
Comment: Certainly. I have no hope OP's idea could be a good solution, I was just trying to find situations where it might be less unfeasible.


Service banner checking for vulnerabilities offline

Question: Has anybody seen a tool where you can collect Service banners from something like nmap, output them to a file, the vuln vulnerability checks offline?
Answer: Your proposed tool would perform a lookup of the version numbers against a database of known vulnerable versions. That could be scripted by hand and checked against something like metasploit, NSE, or exploit-db.com (if by 'offline', you mean 'away from the targets').
This would be very cursory in nature, so I doubt a tool pre-exists, but can easily be done by hand.


Is business logic in constructors a good idea?

Question: I'm currently rebuilding a specialised ticket system at work (mainly used to support people with faults in remote sensing hardware...). Anyway, I was wondering whether doing lots of workflow type activity in an object's constructor is a good idea.
For example, there is currently this:
$ticket = new SupportTicket(
    $customer,
    $title,
    $start_ticket_now,
    $mail_customer
);

as soon as the object is created, it'll put a row into a database, go and mail the customer a confirmation e-mail, possibly send a text message to the nearest technician, etc..
Should a constructor be firing off all that work, or something more like the following?
$ticket = new SupportTicket($customer, $title);
$customer->confirmTicketMailed($ticket);
$helpdesk->alertNewTicket($ticket);

If it helps, the objects are all based on the ActiveRecord style.
I guess it may be a matter of opinion, but what do you think is the best thing to do?
Answer: If the constructor does all that work then the constructor knows about many other domain objects.  This creates a dependency problem.  Should the ticket really know about the Customer and the HelpDesk?  When new features are added, isn't it likely that new domain objects will be added to the workflow, and doesn't that mean that our poor ticket will have to know about an ever increasing population of domain objects?
The problem with spiderwebs of dependency like this is that a source code change to any one of the domain object will have an impact upon our poor ticket.  The ticket will have so much knowledge of the system that no matter what happens, the ticket will be involved.  You will find nasty if statements gathering inside that constructor, checking the configuration database, and the session state, and so many other things.  The ticket will grow to become a god class.
Another reason I dislike constructors that do things is that it makes the objects around them very hard to test.  I like to write lots of mock objects.  When I write a test against the customer I want to pass it a mocked out ticket.  If the constructor of ticket controls the workflow, and the dance between customer and other domain objects, then it is unlikely that I will be able to mock it out to test the customer.
I suggest you read The SOLID Principles, a paper I wrote several years back about managing dependencies in object oriented designs.
Comment: God spoke directly to you, feel blessed. Robert C. Martin replied your answer :O
Answer: Split things up. Really, you don't want a ticket to know how it should send e-mail etc. That is the work of a service like class.
[Update] I don't think the suggested factory patterns are good for this. A factory is useful if you want to create different implementations of tickets without putting this logic in the ticket itself (via overloaded constructors for instance).
Take a look at the Service concept proposed in Domain-Driven Design.

Services: When an operation does not conceptually belong to any object. Following the natural contours of the problem, you can implement these operations in services. The Service concept is called "Pure Fabrication" in GRASP.
Answer: The problem, from an OO design perspective, is not so much whether that functionality should be implemented in a constructor (as opposed to within other methods on that class), but whether the SupportTicket class should know how to do all of those things.
In a nutshell, the SupportTicket class should be modelling a support ticket, and only a support ticket. Creating an email, knowing how to send that email to the customer, queueing the ticket for processing, etc. are all lumps of functionality that you should move from your SupportTicket class and encapsulate elsewhere. The benfits of doing this include lower coupling, higher cohesion, and improved testability.
Have a look at the Single Responsibility Principle, which explains the benefits of doing this. In particular, this blog is a good place to read up on SRP and the other keystone principles of good OO design.
Comment: this hits the nail on the head. Whether you use a factory (as other posts mention) or not is irrelevant.
Answer: Actually I've never been happy with any of the available answers, but let's look at them. Choices are built around two evaluation questions:
E1. Where does the knowledge belong of the business logic?
E2. Where will the next reader of the code look? (Screechingly Obvious Code)
Some choices:

In the client code (the object that does "new SupportTicket"). It probably doesn't / shouldn't know the business logic, evidently, or else you wouldn't be wanting to create that fancy constructor. If it IS the right place for the business logic, then it should say:
$ticket = new SupportTicket($customer, $title);

handleNewSupportTicket($ticket, ...other parameters...)

where, in order to protect E2, "handlenewSupportTicket" is the place where that business logic is defined (and the next programmer can easily find it).
In the support ticket object, as a separate business call. Personally, I'm not really happy with this, because it's two calls from the client code, where the mental thought is 1 thing.
$ticket = new SupportTicket($customer, $title);

$ticket -> handleNewSupportTicket(...other parameters...)

In the class of support tickets. Here it is expected that the business logic resides in the Support Ticket area, but since new support tickets absolutely need to be handled immediately and not later, this important task can't be left to anyone's imagination or mistyping, i.e., specifically not to the client code. I only know how to code class methods in Smalltalk, but I'll take a stab at pseudo-code:
$ticket = SupportTicket.createAndHandleNewSupportTicket(...other parameters...)

Assuming that the client code needs the handle to the new ticket for other purposes (otherwise the "$ticket =" would vanish).
I'm not awfully fond of this, because other programmers don't find it so natural to look for business logic in class or static methods. But it's the third choice.
The only fourth choice is if there is another place the business logic happily resides and other programmers will naturally look for it, in which case it goes into a class/static function there.
$ticket = SupportTicketBusinessLogic.createAndHandleNewSupportTicket(...other params...)

where that class/static function does the multiple calls needed. (But now we once again have the possibility that tickets can be constructed and not handled properly :(.
Answer: The short answer is no.
In hardware design, we used to have a saying, "Don't put a gate on the clock or the reset line - it obscures the logic." The same applies here for the same reason.
The longer answer will have to wait, but see "Screetchingly Obvious Code".
Comment: Based on the context here, user "Alistair" is most likely [Alistair Cockburn](https://en.wikipedia.org/wiki/Alistair_Cockburn).


Purpose of Badges?

Question: I've received quite a number of badges, but although I've searched in meta and in the main English site, I couldn't find what the point of badges is.
Comment: See at MSE, e.g. *[Why are badges motivating?](https://meta.stackexchange.com/questions/61729)* There are also relevant questions at [communitybuilding.SE], e.g. *[Do badges (gamification) produce positive results in a professional community?](https://communitybuilding.stackexchange.com/questions/929)*
Comment: https://english.meta.stackexchange.com/help You need to read this
Comment: It's gamifying. Like a gold sticker you mom gives you when you are 5 for years old for brushing your teeth every day of the week, the badge is reward for good work done. Such rewards may be connected to functional things (like with a particular kind of badge you can then close some questions with a single vote), or it can just be another sign of reputation that others can see.
Comment: OK, so it looks like they don't increase you reputation points.
Comment: Don't the badges come with a brief description for what they are awarded?
Comment: @Mari-LouA:  what they're given for isn't the same as the ultimate purpose.  But all the responses here have answered my question.
Answer: Badges reward good behavior
The blog post that first announced badges describes their purpose thusly:

Our goal with the badges is to encourage people to a) have fun and b) use the Stack Overflow website in ways that make sense.

A second blog post about badges says something along the same lines:

Badges exist to reward and encourage the kind of positive behavior we want in our community.

Badges help indicate participation
Although it's not mentioned in the aforementioned blog posts (due to changes that happened in 2015 after those blog posts were written), there is another place badge count... counts. The "Candidate Score", which is shown for each person running during each moderator election, is based on a combination of reputation and certain badges:

1 point for each 1000 reputation up to 20,000 reputation for a maximum of 20 points.
1 point each for Moderation badges - Civic Duty, Cleanup, Deputy, Electorate, Marshal, Reviewer, Sportsmanship, Steward - for a maximum of 8 points.
1 point each for Editing badges - Copy Editor, Explainer, Organizer, Refiner, Strunk and White, Tag Editor - for a maximum of 6 points.
1 point each for Participation badges - Constituent, Convention, Enthusiast, Investor, Quorum, Yearling - for a maximum of 6 points.

For badges that can be awarded multiple times only 1 point is granted for each badge type, thus ensuring a maximum score of 40 points.

People of course are free to vote however they want, but higher scores look better.

On sites where users leave "welcome" comments for new users, it is often suggested (for example here) to only suggest a new user take the tour if they don't have the "informed" badge (which is given for taking the tour).

Badges also give a quick indication how much a user has participated on meta, which doesn't have its own (visible) reputation system.
Answer: They are akin to getting "achievements" in computer/console games. Badges are one of many ways that Stack Exchange games you to participate more in it, as are points, privileges and the like.

Purpose of Badges?


Is there a way to bake a model's normal map in chunks?

Question: I'm very new to texturing in Blender. When baking the normal map of my model, it is unable to render correctly because my model has too many varied spacing lengths between geometry to have a "ray distance" setting that bakes cleanly. Is there a way for me to bake the model in chunks, so that I can avoid this problem? If I have to go as far as breaking my model into smaller objects, how should I go about piecing the resulting renders into a single normal map?
Comment: If you need variable ray distance, you can use a cage. Blending together parts of bakes is difficult, but probably doable so long as you keep the exact same UV layout and be careful of seams.
Answer: If you uncheck Clear Image checkbox in the Bake/Output you will be able to bake from different chunks sequently to the same image. You may want to lower the Margin distance so that the margin wont overwrite previous bakes.
Another way of dealing with this type of problems is to (copy and) move different parts together with their high-poly counterparts so they will be baked all at ones but without intersecting with each other.
Or, as previous suggested, create a cage mesh so you can control the ray length in detail.


Want to permanently mount Kernel-Driver into System

Question: I wrote my own kernel driver for a usb-device. After I compile it with make, I have the kernelobejct file usbdriver.ko and with sudo insmod usbdriver.ko I can install and then use it.
But if I restart my Debian, I need to do do insmod again to use it ...
How can i mount/install that driver permanently into the system, so that it loads when the os is starting? And how can I also grant other users than only root to access the asscoiated device-files under /dev/usbdriver0?
Answer:
Copy your driver to /lib/modules/$(uname -r)/kernel/drivers/ and add it to /etc/modules: http://www.cyberciti.biz/tips/compiling-linux-kernel-module.html.
I don't know but I think it's in the source code somewhere.
Comment: ok so I can autoload it at startup, but cant manage rights that way. I read something about putting a file in /etc/udev/rules.d but i dont know how to write such a file ... :(
Comment: Ok i found a working solution: created the file /etc/udev/rules.d/10-usbdriver.rules with this line
SYSFS{idVendor}=="1337", SYSFS{idProduct}=="4242", MODE="0660",GROUP="developer"


Mitsubishi Canter will not go into 4th gear

Question: 2013 Mitsubishi Canter 6500kg GVM 5 speed tip truck.  Recently had a new clutch installed.  Drives fine until the engine warms up.  Then will not go into 4th gear.  All other gears work fine.
Answer: The external shift linkage probably had to be removed and reinstalled when the clutch was changed, and may have been re-installed or re-adjusted incorrectly. If that isn't the problem, then there's an internal fault in the gearbox.
The linkage is probably easier to get to, and — if the gearbox worked correctly before the clutch R&R was done — more likely the cause of the problem. I don't think the problem is the clutch itself, as the gearbox can be shifted and the other gears work correctly.
Have a competent mechanic inspect/adjust/repair the linkage. If that doesn't do it, the gearbox will have to be opened up.


Update Manager issues

Question: I am still getting used to dual running Ubuntu on my Windows 7 machine using Wubi. I currently have Ubuntu 12.01 and want to upgrade to 13.04. According to the instructions here :http://www.ubuntu.com/download/desktop/upgrade
I first need to launch the dash and search for an "Upgrade Manager". I do that but the only option I get is a software updater.
Any help?
PS, I am still getting used to using a terminal so I would really appreciate not using the terminal quite yet till I am more familiar with it (if at all possible).
Answer: First, open your terminal [Ctrl + Alt + T] and type this command
<code>sudo apt-get install update-manager
</code>
after installed, search from dash update manager and run it, now click on check button, if there update available, update it, after update you can upgrade your system for newer version
Answer: The Update Manager (note, not Upgrade Manager) is called Software Updater in Ubuntu 12.10. So run that. It will tell you that there is a new release available and give you the option to upgrade to it.
Make sure you have 3 GB free space before attempting to upgrade. Consider backing up your important data first. Also consider whether it's a good idea to upgrade a Wubi install, or rather switch to a normal dual boot.
Answer: Ubuntu is longer supporting wubi so I recommend you upgrade to a full install. Before you do this you should backup all of your files and important data. Then follow the installation instructions here.
Answer: In some cases it's much easier to use the terminal esecially when getting used to Unity or any new desktop environment. You also say 12.01, so i'm assuming you mean 12.10? If you mean 12.04 then you will need to do a upgrade twice.
Open Terminal:
Sudo apt-get update
Sudo apt-get upgrade

Update Manager issues


How to describe a setting but without making it too cliche?

Question: There is this one author technique that I find a bit cliche, which is matching the mood to the setting. This means that for example, when one character is upset, the skies are grey to match the mood of the character. I wanted to add this technique to my story, but I don't want it to seem too cliche. Every time a character is upset, the skies are not always gloomy. How can I use this technique without making it too cliche?
Answer: The secret behind this is that we never perceive things neutrally, but always through the lens of our mood, our experiences, and our emotions. Coloring the descriptions can be powerful way to put the reader in the head of the POV character, and to make a more immersive experience.
With that said, your moods aren't actually affecting the weather unless you're some kind of demigod or nature spirit. So the key as a writer is not to change the setting to match the mood, but rather to change the way the setting is described. Here's a sunny day described by someone in a grim mood: "The sun was a merciless, reproachful eye, staring at me out of a pitilessly blue sky, one lacking the grace of even a single cloud." Now, here's a rainstorm described by someone in a great mood: "Electricity charged the air, and the rain hitting my skin made me feel invigorated and alive."
It's not the dull, factual details of the setting that convey the mood. It's the way the POV character experiences them.
Comment: I agree with this. When in a decent mood I actually quite enjoy the rain. When I'm in an already sour mood, I'm internally grumbling about my wet clothes. Similarly when it's sunny and I'm happy, I mostly notice the comfort and warmth whereas when I'm sad I'd notice feelings of sweatiness and unpleasant glare from shiny surfaces.
Answer: This technique can feel cliché when it's used clumsily for effect rather than fitting the story.
In a solid, working story, everything should fit together seamlessly, the story, the characters, the setting, the dialogue, almost as if the reader is watching you piece together a puzzle right in front of their eyes and when they see the final picture, everything is just as it should be and creates a wonderful 'ahh' moment.
If you draw in a moody sky just because the character is gloomy, but it doesn't fit the rest of the story, it'll look wrong in the final picture and the reader will see that you shoehorned it in there for effect.
Whereas, if you read a story like Hills Like White Elephants, for example, the sadness of the female character isn't conveyed by a gloomy sky (that would have been cliché). Instead, Hemingway uses a bright sunny day. Even though the weather doesn't match her mood, the heat conveys the pressure the man is putting her under (there's no shade). The sun like a spotlight on her, hounding her to make a decision. And in the far distance - the future after she makes the decision - there's a single cloud.
Of course, Hemingway is a genius and less is always more when you're starting out. Better to tell a good story plainly, and then, when you have a feel for your story and know such techniques will add rather than detract, go back in a future draft and pepper them in carefully with a fine brush.
Answer: Just don't.
The weather (or other elements of the setting) can have an effect on the characters, but the character's mood has no effect on the weather.
A gray, overcast day might pull your character's mood down but the depression your character feels can't make clouds appear.
Look at real life, for Pete's sake.  Funerals happen on bright, sunny days and people get married when it is pouring rain outside.
Coincidences happen - sometimes funerals do take place on cold, rainy, nasty days.  My wife and I got married (over twenty years ago) on a beautiful late summer day.
Making the weather always match the character's mood is just a bad idea, though.  That stretches coincidence beyond belief and into cliché territory.
A funeral in October (in the northern hemisphere) can realistically be expected to take place on a nasty day.  A funeral in mid-summer can reallistically be expected to take place on a sunny day - with maybe an afternoon thunderstorm.
The weather can contribute to the setting and the characters' mood.  Bad weather can make a bad time seem worse.
Conversely, a bad mood can cause a character to perceive the weather as worse than it really is. If you are already feeling down, then a rainy afternoon that postpones a planned event can be a total bummer - it'll be perceived as a totally crappy day, when it really isn't.
Avoid the cliché, or subvert it.
Have a depressed character wonder how life can be so shitty on such a beautiful day - a funeral on a summer's day when other people are going to the beach.
Have a happy character note the contrast of their good mood with the grumpy people stomping through the rainy streets.

If you must make the setting fit the character's mood, try to make it believable.  Make it look like the character's mood just coincidentally matches the setting rather than having the setting follow the character's mood.

Of course, a fantasy setting can turn that on its head.  A fantasy story may well have a character whose mood really does influence the weather - but that needs to be a part of the story and the fantasy world.
Comment: "Isn't it Ironic.  Like rain on your wedding day" Me:  No, that's coincidence, not Irony!  We've been laughing at you for the better part of 30 years for this!

Sorry, Sorry... The rain on the wedding day line triggers.  :P

Seriously, I'll point to the Buffy episode "The Body" which takes place in a very bright and sunny southern california day and the subject matter of the episode doesn't fit the mood of the day (there's one part where you can hear laughing children in the background which makes the tragedy hit harder.).
Answer: It's not always necessary to match the weather and general atmosphere to the mood of your main characters. In many books, scenes where the character is upset often are bright and sunny. The contrast effect gives you a lot of opportunities to talk about your character's feelings.
And it's also not wrong to have gloomy weather during sad scenes. Just make sure you focus more on your plot and story, and try not to lose the reader's attention with lengthy descriptions. It can get repetitive when you start talking about rain and grey skies.


How would multiple mana doublers stack?

Question: If I have zendikar resurgent, mirari's wake, and mana reflection on the field, how would they stack?
Answer: If you have all of those together and you tap a land for mana, Mana Reflection doubles the amount of mana produced by the land's ability, and then Zendikar Resurgent and Mirari's Wake each have an ability that produces 1 more mana, for a total of 4 mana with most simple lands.
Mana Reflection's ability says

If you tap a permanent for mana, it produces twice as much of that mana instead.

This directly modifies the mana produced by the land's ability.
On the other hand, Zendikar Resurgent and Mirari's Wake both have abilities that say

Whenever you tap a land for mana, add one mana of any type that land produced.

These are triggered abilities that triggers from activating and resolving the land's ability. These abilities produce mana separately from the land's ability, so they are not modified by Mana Reflection.
Comment: Mana reflection stacks multiplicatively with itself, though, so one land with two mana reflections produces 4 mana
Comment: There's also a comparison to be made to Anointed Procession (replacement effect) and Panharmonicon (triggered ability).
Comment: I'm not following that comparison. Those cards just do different things. Annointed Procession has a replacement effect that modifies token creation, and Panharmonicon has an effect (of unclear kind) that modifies triggered abilities triggering. The fact that Anointed Procession is multiplicative and Panharmonicon is additive is not the same kind of difference as in these question; that depends more on the technical details of the events each one is modifying.

How would multiple mana doublers stack?


RMA'ed device configuration

Question: Just wondering what are the methods that you use when re-configuring an RMA'ed device.
Do you manually configured all the script that runs on the device or is there any efficient ways configuring the device without manually configuring it.
Comment: All depends on the  kind of device, no?
Comment: ... and your device management (where you might just need to reassign the config).
Answer: After you power up the new device and update any soft/firmware, you can simply upload a backup of the device configuration.  You do have a backup of the configuration, don't you?
Answer: I'm going to assume you either mean 'What do you do before you RMA a device' or 'What do you do when you purchase a refurbished/used device':
For the first one, if it is in working condition enough to do so, simply set it to factory default or delete the configuration before returning it.
For the second, basically the same. Factory reset and then update any firmware or software before beginning initial setup and testing.
Comment: ... and don't forget the required certificates including private keys. Commonly, those aren't exported with a config backup but need to be either reimported or regenerated.

RMA'ed device configuration


what is kvm over ip?

Question: what is kvm over ip?  can someone explain?
Answer: Keyboard-Video-Mouse over IP.
It can be implemented in a KVM appliance that has the ability to forward console sessions to a remote computer, usually in a web browser -- you browse to the KVM, click on the server you want, and you have remote control of the console.  True console, in that you can interact with the computer while it is booting exactly as if you were in front of the machine.
More recently, some Lights-out-management cards built into enterprise-class computers sometimes come with a KVM-over-IP implementation built in, so you don't need a separate appliance to get true remote control.  HP offers the iLO (although usually the KVM functionality is a increased-cost option) and some Sun X series have the iLOM (I am thinking of the X2200-M2, of which I have a dozen or so).
Of the two (appliance or built-in management card) I prefer the latter, because usually they come with remote power controls as well so you can power cycle a computer remotely even if it is totally hung, then interact with the BIOS or RAID cards or whatever on the way up.
Personally I'm getting spoiled -- my attitude is that if I have to go down and touch hardware, something better be physically broken.
Comment: Real hackers are lazy: they use tools to do their job for them.
Answer: To complete David's answer (that is very clear by the way), here is a solution commonly used on x86 servers: IPMI
Comment: @David Mackintosh: You can do KVM - we have a bunch of supermicro boards all with either an extra IPMI card or IPMI onboard, and it offers SOL and KVM over IP, and even Image Mounting (ie you provide on your client a disk/cd image and it gets mounted)
Comment: Can you do KVM-over-IPMI?  I thought that IPMI was a way of interacting with a BMC (baseboard management controller) -- and while a card which can do KVM-over-IP can almost always do IPMI, the reverse was not true.
Comment: Since the bios and operating systems are able to display on serial and that classical BMC include a serial bus, you can do Keyboard-Video (altought not graphical but text-based display) over IPMI (I believe it is nearly impossible to get a mouse?)

There are also specific applicance/hardware that implement KVM over IPMI for multiple computer, such as Aten KH98...
Answer: You can also build your own wireless IPKVM, if you're really keen :)
http://www.anchor.com.au/blog/tag/ipkvm/
Answer: The other answers are already good, to throw some more systems into the room: Dell uses iDrac (as far as I remember it is just an IPMI clone) and Intel has with vPro/AMT also the possibility to do kvm (from AMT version 6 there is an vnc server that allows you to manage the machine - but beware: from my experience the AMT is (to say it mildly) a PITA.
My experience with the IPMI and Dell system are positive, they do their job and work more or less out of the box.

what is kvm over ip?


Single Pole Motion Sensing Light Switch

Question: Attempting to install GE single pole motion light switch.  The existing switch controls two lights in a small hallway.  Can the single pole motion switch be wired for 2 lights?
Comment: If the motion sensor only takes two wires (no white neutral wire) it might not work with LED or CFL bulbs.  LED bulbs can glow with these types of switches even when off, so check the specs of the switch in detail.
Answer: TL;DR Yes
Full answer: Normally the only restriction is the amount of power. An ordinary switch will be rated for the full power of the circuit - e.g., 1875 W for a 15 A circuit. However, a smart switch, dimmer, motion switch, etc. is much more complex and will typically be rated for less total power. That helps save money as the electronic components don't need to be designed to transmit, switch, dim, etc. as much power or to dissipate as much heat.
The good news is that with CFL and now LED lights - which you should be using pretty much everywhere now as the power savings pay for the bulbs very quickly - the power ratings of switches are typically far more than ordinary residential needs. For example, if you have 2 3-bulb fixtures, in the old days (incandescent), that could easily be 6 x 60 W = 360 W. With typical CFL bulbs, the power used is 13 - 16 W, and with typical LED bulbs 9 - 10 W, for a total of 54 - 96 W.
Just check the rating on the new switch and compare it with your existing bulbs & fixtures. There may be different ratings depending on the type of bulb, but 2 fixtures in a small hallway is unlikely to be a problem.

Single Pole Motion Sensing Light Switch


What is the location of the CG on the T-38?

Question: Is the Northrop T-38 Talon's CG forward or aft of the center of lift (like the F-16)?
Answer: Unlike conventional aircraft (and older fighters), the CG location of the F-16 makes the airplane unstable (making the aircraft more nimble), requiring fly-by-wire and a flight control computer to stabilize the aircraft.
Since the T-38 was designed prior to fly-by-wire technology, I would expect it to have been designed with a CG location that makes the aircraft inherently stable.
If the T-38 does have fly-by-wire, then my answer will get lots of down-votes, but I don't think that is the case looking at this:
https://mitindia.edu/images/pdf/avionics_ppt/stability%20and%20agumentation.pdf
Comment: I hate to play grammar police, but double negatives just drive me crazy. They introduce a level of confusion that is just unnecessary. Recommended text:  "I would expect it to have been designed with a CG location that makes the aircraft inherently stable."
Comment: @Gerry  Done!  Thanks
Comment: The T-38 most certainly was NOT a fly-by-wire aircraft!  Its flight controls are entirely hydraulically powered, but those hydraulics are controlled by the pilot through conventional stick-and-rudders (with essentially a yaw damper to help out with the rudders a bit) -- no fancy computer fly-by-wire used, nor necessary.  Sub-sonic, the plane is nimble but not at all unstable; supersonic, it's very stable.  It's also much older than fly-by-wire technology; in fact it's a good example of how "inherent stability" is what the F-16 could leave behind with FBW and what you gain for doing so.


What did the water's edge look like on the Pacific coast of the Laurentide Ice Sheet?

Question: I have seen news reports saying that in recent years many more scientists think that humans first arrived in the Americas by boat, along coast of Alaska and Canada (before they were able to come through the Bering Strait land route). They would have done this ocean journey during the last ice age. Would this coast have been an ice cliff at that time? If so, such a long journey along such a coast must have been quite difficult. In other words, would early humans have had to follow along a coast that looked something like this picture below? Thank you in advance for any thoughts you can share on this.
Comment: I think you can't speak of one single journey. This probably was rather a matter of generations and centuries, maybe even millenia. Some tribes ventured along the coast in Eastern Russia, found some place to settle, it got crowded, some of them ventured further east, maybe only for the summer, etc, pp. (Source: My own logic understanding of how humanity spread).
Answer:
There is no pacific coast to the The Laurentide Ice Sheet, you are thinking of the Cordilleran Ice Sheet.

You are making a mistake in thinking the ice wall would be continuous. At its maximum it would look like that, but 25,000 years ago it was under retreat and would have been large patches of normal coastline with a few interspaced glaciers. It extended back out to the ocean later around 13,000 years ago.

What would it look like when humans crossed it, sections like picture A and sections like picture B.

https://faculty.washington.edu/dbooth/Ch_02_INQUA_volume.pdf
Answer: West of the Continental Divide it is the Cordilleran ice sheet.
I think the blue line here would have been ice shelves where it is in deep water. It also shows some ice-free land (note, sea level was 125 m lower).
Answer: The West coast of Greenland facing onto the Davis Straight would probably be your best approximation today. Note that although there are extensive glaciers reaching the sea, the Eskimos can move around in the area with a degree of facility, living mostly on marine resources.
Don't forget that at glacial maximum, sea level was around 100m lower, so you'd need to adjust your mapping/ modelling to that different sea level.