How do I link text boxes in iBooks Author?

Question: I've been trying out iBooks author, and one thing i want to be able to do is to allow text overflow from one custom text box to another. In pages this is done either by clicking the blue little symbol in the lower-right part of a text box with too much text, and link it to another, or by going to the menu format->text box->add linked text box. In iBooks Author, however, this last option is greyed out for no apparent reason, and the blue link symbol never appears. Any suggestions?
Comment: Hmm. I have never use that before, But I got it to work on  one of the text boxes by resizing it and the blue handle appeared. But can not get it to do it on others?
Answer: Using the Botany sample, the text boxes seem to work as expected with the caveat that you have to intentionally click on one of the four corner handles of the text box to make the blue linking triangles appear.
I took a small video showing the controls reacting to mouse events.
From there, linking works as expected from the perspective of Pages.
Comment: I found out that (to me) it only works if I use the already existing text boxes, by resizing them and creating new through them. This works for me, so problem solved. I had originally created a new text box with the tool visible at the tool field, and then linking won't work, for some reason.
Answer: This is very difficult to find. When you create the text box after Enable: Editable on pages using this layout you should use the tag body, when a text box has the tag body will show the connection lines.
Comment: This is the answer that solved this for me. As an additional note, iBA will alert you if you have another frame tagged with "body" already on the page somewhere.
Answer: I have found that it is necesary to give some special properties to the text boxes inside of layout column, for example:

Select the view menu on the top bar
Select Show layouts
Select a textbox
Open layout inspector
Enable: Editable on pages using this layout

Then in format menu: Format > Text box > Show connection lines
The arrows and blue lines appear when toggling the menu item Show connection lines
When use the same layout to create a page or section, the textbox must contain tne blue arrows and connection lines to.
I found that this solution is not applicable to all the textboxes, it seems to deppend on the text style or something.
Comment: I cannot find the fifth step in the layout inspector. All I can choose is column width and number of columns?
Comment: This one gave me what I needed.  I didn't even know where the layout editor was previously.  Thanks!
Answer: To summarise:

You have to be in layout mode. So select View menu on the top bar, and ensure that Show layouts is enabled.
use the Text Box icon on the top menu bar to create a text box
Select the text box and open the inspector, go to the Layout inspector and enable "Editable on pages using this layout" and ensure that the Tag is set to "body"
the link handles should now be visible. Click on them to create additional linked text boxes.

Note: you can only use one body tag per layout


Prove that a circle can be inscribed in the hexagon

Question: Given a convex hexagon $ABCDEF$. All its sides are equal (it can be irregular). Furthermore, $AD = BE = CF$. How can I prove that a circle can be inscribed in this hexagon?
Answer: Let $O$ be the intersection point of diagonals $AD$ and $BE$ (see diagram below) and set $a=OB$, $b=OD$, $d=AD=AE$, $\theta=\angle AOB=\angle DOE$. Then by the cosine rule we have:
$$
a^2+(d-b)^2-2a(d-b)\cos\theta=b^2+(d-a)^2-2b(d-a)\cos\theta,
$$
which simplified gives:
$$
(b-a)(1-\cos\theta)=0,
\quad\hbox{that is:}\quad
a=b.
$$
It follows that $OBC\cong ODC$ and $OAF\cong OEF$, so that
$\angle COB\cong \angle COD\cong \angle AOF\cong (\pi-\theta)/2$
and points $COF$ are aligned.
By repeating the same argument given above for diagonals $AD$ and $CF$ we get  $OF=a$, $OC=d-a$. It follows that all six triangles in the diagram are congruent between them and in particular they all have the same altitude from their common vertex $O$. A circle of center $O$ and having that common altitude as radius will therefore touch all six red sides of the hexagon.
Notice that if $a\ne d/2$ the hexagon is NOT regular. All six angles with vertex at $O$ are however congruent and they thus measure 60°.

EDIT.
One could prove that $a=b$ even without trigonometry. Triangles $ABO$ and $EDO$ have congruent between them the angles of vertex $O$ and the sides opposite to them. In addition, the other two sides of each triangle have the same difference.
It is well known that if two triangles have the same base $PQ$ and the angles opposite to $PQ$ both congruent, then the third vertex of both triangles lies on the arc of a well defined circle having $PQ$ as a chord.
Moreover, if the difference of the distances of the third vertex from $P$ and $Q$ is the same for both triangles, then the third vertex must also belong to a well defined hyperbola having $P$ and $Q$ as foci. This third vertex is then one of the two intersections between circle arc and hyperbola, and both possible triangles are congruent between them.
Comment: But if $AD$=$BE$ and $AB$=$DE$, then $AB$ and $DE$ must be parallel and $AOB$ and $DOE$ are isosceles triangles.
Comment: @TLDavis How do you infer that $AB$ and $DE$ are parallel? As you can see from the diagram, angles $\angle BAO$ and $\angle EDO$ are not congruent, in general.
Comment: You're right, I was wrong.
Answer: Lemma. (1) Diagonal $BE$ is the angle bisector of both angles $\angle \, ABC$ and $\angle \, DEF$;
(2) Diagonal $CF$ is the angle bisector of both angles $\angle \, BCD$ and $\angle \, EFA$;
(3) Diagonal $AD$ is the angle bisector of both angles $\angle \, FAB$ and $\angle \, CDE$;
Finally, the three diagonals $AD, \, BE$ and $CF$ intersect at a common point I.
Proof. Look at quadrilateral $ACDF$. Reflect point $A$ in the line $DF$ and let $A^*$ be the symmetric image of $A$ with respect to $DF$. Then $$ \angle \, DA^*F = \angle \, DAF $$ as well as $FA^* = FA = CD$ and $A^*D = AD = CF$. Since $A^*D = CF$ and $FA^*=CD$ the quad $FCDA^*$ is a parallelogram and thus $$\angle \,DCF = \angle \, DA^*F =  \angle \, DAF$$ Therefore quad $ACDF$ is inscribed in a circle and since $FA = CD$, the quad $ACDF$ is in fact an isosceles trapezoid with $AC$ parallel to $DF$. For that reason, the parallel segments $AC$ and $DF$ have a common orthogonal bisector and since $BA = BC$ and $ED =EF$, the points $B$ and $E$ must lie on that orthogonal bisector, i.e. the line $EF$ is the orthogonal bisector of segments $AC$ and $DF$ simultaneously. However, since triangles $ABC$ and $DEF$ are isosceles, the orthogonal bisector $BE$ is at the same time the angle bisector of both angles $\angle \, ABC$ and $\angle \, DEF$. Observe that since the line $BE$ is the orthogonal bisector of the two parallel sides $AC$ and $DF$ of the isosceles trapezoid $ACDF$ its two diagonals $AD$ and $CF$ intersect in a common point which lies on $BE$. The rest of the lemma follows analogously.
$$ $$
Completing the proof: Observe that by the Lemma, the lines $AD, \, BE,$ and $CF$ all meet at a common point, we denote by $I$. Consequently, by the Lemma, $I$ is the common intersection point of all angle bisectors of the angles at the vertices of the hexagon $ABCDEF$. Therefore, there is a circle inscribed in the hexagon with point $I$ the incenter. As a consequence we get that $IA=IC=IE$ and $IB = ID=IF$.


How to stop malicious files (XSS files) upload even for admin users who have full permissions to site collection

Question: Hi In SharePoint how to stop malicious files (XSS files) upload even for admin users who have full permissions to site collection.
For example, in a custom list or document library, no one can upload malicious files who has permissions to this list or library, what are the recommended approaches to prevent this.
Answer: Go to Central Admin site - > Security -> Click on the Define Blocked File Types under the General Security section -> Now we will see the list of blocked file types box - include the .xss in that box. -> Click on Ok button.
Note:

This file security works on the web application level - so you need to repeat the same configuration for all the web applications you want.

Updated Answer:
How to prevent users to prevent to upload infected documents in SharePoint?
For this, we need to configure the "Configure Antivirus Settings And Features" in SharePoint CA.
Below are the steps to configure the security and use their features in SharePoint:

Open SharePoint Central Administrator with administrator rights
Central Administrator page will be displayed at browser page, here we
need to select a security option from left side of the page.
Once you have clicked on security page, it will redirect us to
security wizard where many options will be available. Here we need to
select Manage Antivirus option from General security; shown below,
Once you have clicked there, we will get Antivirus page where we need
to do configuration and settings for the same,
We can see there will many options available on this page, below I
have described each one,

Antivirus settings
will specify the behavior while uploading documents in the list or Library. Following option will be available for those.
Scan documents on upload
by selecting this setting to scan uploaded documents. This helps prevent users with infected documents from allocating them to other users in the farm.
The above solution applies to SharePoint 2013 & 2016
For details refer to the below article:
Configure Antivirus Settings And Features
What happens when an infected file is uploaded to SharePoint Online?

A user uploads a file to SharePoint Online.
SharePoint Online determines whether the file meets the criteria for a scan.
The virus detection engine scans the file.
If a virus is found, the virus engine sets a property on the file indicating that it's infected.

For details refer to the below MSDN article:
What happens when an infected file is uploaded to SharePoint Online?
Comment: I believe the questioner is referring to cross-site scripting (XSS) and not specifically .xss files.
Comment: yes it is not specific to .xss file even any malicious files authenticated user should not upload
Comment: I think for this we need to configure the "Configure Antivirus Settings And Features" in SharePoint CA, please refer to the updated answer it might help you.


"which" refers to which one?

Question: In the sentence:
"Great helm was worn with a hauberk which also covered the neck and the head of warrior."
The word "which" refers to great helm or hauberk?
Comment: That "which" clearly refers to the hauberk.
Comment: Welcome to ELU! *Great helm* and warrior also need articles, probably *the*.
Comment: A hauberk is a mail shirt. Presumably needed to provide padding under the great helm.
Answer: I would suggest that due to the structure of the sentence and where the "which" is placed it seems to point to the "Hauberk"
Answer:
The hat was worn with a hairnet which also covered her hair.

Which, who, and (often) that are relative pronouns used to link to another word in the sentence (very often the one directly preceding it) to add information about that word.
Which adds the information also covered her hair to hairnet.

"which" refers to which one?


Changing Multiple Colours at Once

Question: Ok so I was wondering if it was possible to add a red tinge to all of these colours, but I don't won't to go into the node editor and change each one individually to have a red tinge. Is there a way that I can add a red tinge to all of the materials in one go? Essentially have some sort of master control over these 3 colours, so that if I add a colour to one of the materials it will also effect the others.
Answer: This is best done with node groups. Add a "main color" group that outputs a color to tint with. Incorporate that into the material nodes. Then, whenever you change the group, all of the nodes get the new color update.

As far as automatically adding the groups, it would be much harder (although not impossible), and it would require a good bit of python programming.
Answer: Just an idea, don't know if it's workable for your blend: set-up a light/lamp and give it a red colour.
If there are objects in the scene you don't want a red 'tinge' to, then I believe it's possible to make those objects ignore the light.
This would then be a 'global' overlay on top of all materials that receive the light.
Comment: Interesting idea, but this isn't a very usable solution. Lamps *add*. They don't just *color*.
Comment: Yes, I was aware I was 'being creative'. Ambient light levels would need adjusting, and of course cast shadows would need to be off, though there would still be areas unlikely to receive the coloured light, I presume. I wasn't expecting an 'accept' on this.

Changing Multiple Colours at Once


Is it possible to prevent Xcode from listing build errors in a separate window?

Question: I don't like the way Xcode displays compile errors and highlights source code in a separate floating Build Results window. It's easy to end up with 3 text editors on screen, all showing the same source code! I just want it to jump to my error in the main text editor like Visual Studio would. Is there a way around this, or is it any different in Xcode 4?
Answer: Yes, select the "All in one" layout in XCode General Preferences.
Answer: Yes, Xcode 4 is all one window, and builds constantly so errors appear almost immediately. I think you'll like it much better, especially if you're accustomed to Visual Studio (it's not the same as VS, mind you, but more similar than Xcode 3).
Answer: No way mate, I was a .net developer before I switched to mac. It's very hard to get use to Xcode and Objective C, it's not as intuitive as Visual Studio , or C sharp.
However the latest version of Xcode brings some improvements , so it doesn't show you the compiler errors in a separate window. It shows you the errors in the left side and the code in the editor. you should upgrade it's a bit more intuitive.


Towers of Providence problem

Question: The Towers of Providence is a variation of the classical Towers of Hanoi problem. There are four pegs, denoted A, B, C, and D, and N disks of different sizes. Originally, all the disks are on peg A, stacked in decreasing size from bottom to top. Our goal is to transfer all the disks to peg D, and the rules are that we can only move one disk at a time, and no disk can be moved onto a smaller one. We can solve this problem with a recursive method: If N = 1, move this disk directly to peg D, and we are done. Otherwise (N > 1), perform the following steps:
(a) transfer the top N-2 disks on peg A to peg B applying the method recursively;
(b) move the second largest disk from peg A to peg C;
(c) move the largest disk from peg A to peg D;
(d) move the second largest disk from peg C to peg D;
(e) fill in this step
Comment: He is looking for the step e.
Comment: Have you tried writing out the steps to move the disks (perhaps only a stack of 2 or 3) by hand, and then seeing if there is a pattern to what will happen in step e?
Comment: You may want to check out: http://stackoverflow.com/questions/1834143/towers-of-hanoi-like-problem
Answer: Step e: Transfer N-2 pegs from B to D by applying the method recursively.

Towers of Providence problem


Any type of Rebel support available?

Question: I find some of the missions in military bases quite hard. Apart from getting a Rebel Drop, is there any other way to call the Rebels for help?
Comment: I can't answer your question, but my strategy was to try and hack any SAMs first, then get destructive. The game only resets soldiers and vehicles (not destroyed chaos objects or hacked SAMs), so you can chip away between respawns. Once all chaos objects are gone, the enemies despawn.
Comment: Ah, so you can hack SAMs. I destroy them but they respawn after my death, making get rid of them a Sysyphean task. Your suggestion is very useful.
Comment: Any _hacked_ SAM doesn't respawn, but any _destroyed_ SAM will respawn as an enemy SAM.  I've found that by _far_ the easiest way to take out a base is with a tank (even the lowliest one is awesome).  They're mostly immune to small arms fire, and there aren't any ant-tank defenses in a base (unlike SAMs vs. helicopters).  It's a bit less dramatic than some other ways of liberating a base, but I've found it to be by far the easiest.
Answer: While liberating a base big enough, Annika might tell you that she is sending in rebel support. She will tell you to do a task, like hack all the SAMs for air support. You cannot call in rebels, but she will usually offer this support for big bases once you destroy about 1 to 2/4ths of a base. The rebels won't destroy chaos objects, but they will attack any form of militia, giving you cover.

Any type of Rebel support available?


nice renice and ionice

Question: I've read about nice renice and ionice to control the scheduling priority of running processes. However, I still don't understand when and how are they useful for. For instance doing something like:
nice -n 13 pico myfile.txt

Answer: With regards to pico it's unlikely to ever be much cause for concern so it's not the kind of command you would normally nice/renice or ionice.  However your command would execute pico niced to +13.  Which would mean it would get significantly less time allocated to it.  For example, following on from your pico line.  Normally pico executed looks like this:
UID   PID  PPID        F CPU PRI NI       SZ    RSS WCHAN     S     ADDR TTY           TIME CMD
501 20118 20117     4006   0  31  0  2435548   1068 -      S     eb577e0 ttys000    0:00.03 -bash
501 20136 20118     4006   0  31  0  2434992    772 -      S+    85eed20 ttys000    0:00.00 pico

Where NI is the nice level.  If I run pico with your command it looks like this:
UID   PID  PPID        F CPU PRI NI       SZ    RSS WCHAN     S     ADDR TTY           TIME CMD
501 20118 20117     4006   0  31  0  2435548   1068 -      S     eb577e0 ttys000    0:00.03 -bash
501 20179 20118     4006   0  18 13  2434992    904 -      SN+   85eed20 ttys000    0:00.01 pico

OK so that demonstrates the command line you run is effective, but what does it actually do?  OK let's say you have a system that is quite busy but not obscenely so.  It's pretty busy all around the clock, at midnight an essential maintenance task starts.  It's mysql command line running a script to generate some daily stats.  There's a lot of processing so it hits the CPU hard and the users complain about this.  Vehemently, as they do.  What can you do about it?
  It's not essential how long this script takes so you prepend 'nice -n 13' to the command and the next time it runs it doesn't affect the users so bad but takes a bit longer to complete.  The owner of the MySQL script doesn't care as he only wants the stats when he gets in the next day.  Everyone is happy.
Stories aside these tools can let you exert some control over how the system prioritises the CPU (possibly IO in the case of ionice) time allocated to tasks.  They will only have an effect when the system is loaded, before that everyone tasks are being allocated all the time they need.
The renice command works in a very similar way but it allows you to alter the priority of processes that are already running.  So in the above anecdote you could use renice to alter the priority of the mysql command without restarting it.  The following command would renice all running tasks named 'mysql' to +13, a much lower priority:
renice -n 13 -p `pidof mysql`

As for ionice I cannot comment but would guess it lets you do similar things with IO.  Influencing how much io certain tasks get to perform, e.g. disk read/writes.  Could be useful in throttling backup process if necessary?
Answer: ionice is an interface to the IO scheduler subsystem of the Linux kernel, it allows for setting IO priorities on a per process basis. The use-case of that would be something like reducing the priority of the updatedb command that builds the database for the locate command in a way that other IO is running undisturbed as updatedb only gets to do IO when no other IOs are currently running.
Answer: nice is to start a program with adjusted niceness level which is basically the CPU scheduler. Niceness values range from -20 (most favorable to the process) to 19 (least favorable to the process). Default value is 10 and only root can use negative adjustments to have more favorable priorities.
renice does the same as above only to already running processes by specifying process ids (option -p), process group ids (option -g) or usernames or user ids (option -u).
ionice sets or adjusts the I/O scheduler niceness of programs and processes for access to "disk" devices. The priority lies within one of three schedule classes: 1 or realtime (tries to give priority no matter what's already going on), 2 or best-effort (normal scheduling, see also reference link), 3 or idle (scheduled only when no other process is accessing disks).
For example, you can run a fstrim command at boot on rc.local with such a snippet in order to have your job done with little burden to the whole system.
(
  sleep 15s #1
  /usr/bin/fstrim -a -v &> /var/log/fstrim.log & #2
  pid=$! #3
  ionice -c 3 -p $pid #4
  renice -n +19 -p $pid #5
) &> /dev/null & #6

It waits for 15 seconds before proceeding to avoid overloading the system immediately (so it can finish its boot up sequence faster).
It starts the fstrim command in the background with its output in a log file and
it records its PID number.
It adjusts the process I/O scheduler to the idle class and
set it to the lowest CPU scheduling priority.
The whole snippet is started in the background to let the boot process go on.

References.

nice
renice
ionice

nice renice and ionice


prove that f(x)=[x] is upperly semicontinuous in R

Question: I want to prove that the function
$f(x)=[x]$  is upperly semicontinuos in $R$.  Upper semicontinuity on my textbook has the following definition:
$f: X \to R$ is upperly semicontinous in a point $x_0$ if $$\displaystyle\overline{\lim_{x \to xo}}f(x)\le f(x_0)$$
So far I wrote:
$\forall \epsilon > 0 ~ \exists ~\delta $ s.t $~~~$$ |x-x_0| < \delta $ $\to $
$[x]-[x_0]<\epsilon$
using the fact that the definition of upperly semicontinuos implies that
$f(x)-f(x_0)< \epsilon$ in a neightborhood of $x_0$.
Now I'm stack since I can't find a proper $\delta$ that satisfies the last disequation. It must be really obvious (observing the graph of the function I guess it has something to do with the fact that the function whole side has discontinuitis regularly and always of the same module) but I'm not able to write it down, nor to obtain it algebrically somehow. Could someone please clarify this last step to me?
Answer: If a in R - N, then $f^{-1}(-\infty,a) = (-\infty, [a]+1)$ is open.
If a in N, then $f^{-1}(-\infty,a) = (-\infty,a)$ is open.
Thus f is upper semicontinuous.


Quoting text that omits Oxford commas in a paper that includes Oxford commas

Question: I'm writing a paper, and I quote several lists from a source that doesn't use Oxford commas. Sic seems way too strong for the situation, since there's no real error in the quotes, just a different convention. I could change my own paper to be consistent with the quotations, but then what would I do if I had to quote a source that did use Oxford commas? I could sneak the commas into the quotes. Finally, I could just leave the quotes inconsistent with the rest of the paper. What's the correct way, if any, to address this?
Comment: @FumbleFingers You mean you'd ***[sic]*** your lawyers on them?
Comment: Do you have an initial position telling you that using the (optional) final comma is somehow "incorrect"? Why? Just reproduce the text *as originally written* and put your silly prejudices aside.
Comment: It's quote, include the quote *verbatim*.
Comment: Sic is definitely not appropriate.  Quote the quotations exactly, and use the comma convention you prefer (or the one your style guide dictates) when you are not quoting.
Comment: What @ab2 said. If ***I*** were a writer, and someone had the cheek to add ***[sic]*** after my Oxford comma in a cite, I'd be looking to see if I could sue them for defamation.
Comment: @FumbleFingers - Amen.  I've answered, citing myself (*ex cathedra*) as authority. ;-)
Answer: This is what I tell my students in similar circumstances.

If you quote, reproduce the author's text exactly. If the author's text  not follow your punctuation conventions, the matter hangs over his or her head, not yours.

Unless the quoted passage contains an egregious error, do not call attention to it with "sic."
Some editors will enforce conformity on quoted text.  If so, the sin is theirs.
Comment: Absolutely. But you need to carefully read the end result in case by quoting too little you remove context that would be necessary to avoid ambiguity. A rather artificial example: "My parents were Jim and Ann. Is like to dedicate this award to my parents, Ayn Rand and God". The second sentence is a common example, the sentence I added before it is a rather clumsy attempt to fix the ambiguity without the Oxford comma.


How can I avoid a C Ionian theme when I am playing in Aeolian?

Question: I am a beginner in music theory and want to compose something in A Aeolian, but I just noticed that the same notes are used for C Ionian.
A Aeolian is supposed to be melancholic while C Ionian is likely a happy mood. Isn't that right?
Comment: I have bad news for you regarding D Dorian, E Phrygian, F Lydian, G Mixolydian, and B Locrian... :)
Comment: Are you composing a choral in Gregorian modes or writing a song in classical or popstyle? Are you identifying  C ionian with C major? And … alla Turca (Mozart) is in minor - is this a melancholic tune?
Comment: As mentioned elsewhere, I'd suggest letting go of the "Aeolian = say, Ionian = happy" concept. The saddest song in the musical *Hamilton* is written in a major (Ionian) key..
Answer: There are two principle idea you need to learn about.

The tonic as the center of tonality in music.
The difference between keys in the major/minor system, key signatures, and modes.

The tonic is usually described as the "home" tone of a scale/key/tonality. If you are in the key of C major the tone C is the tonic.
The second idea is a bit more complex. But it's probably best to start with saying key, key signature, and modes are not synonymous ideas. The term keys is used for the major/minor system.
This isn't the place to go into a long description of "key", but briefly, keys have major or minor triad tonic chords with a dominant chord that uses a major third, that dominant's third being the leading tone of the key, which is also the scale degree one half step below the tonic scale degree.
Modes are similar to keys, but the treatment of harmony and scale degree is a little different in modal music compared to major/minor keys. Also, there are two main uses of the term modal. One being the system of music in the Middle Ages and Renaissance, and the other for more modern folk/jazz/pop styles. In both styles you can make a very broad generalization that modal harmony is not primarily about tonic/dominant chords. A tonic/dominant harmony focus is the hallmark of the major/minor system.
And finally, key signatures only define a collection of tones, but do not define a tonic. So, if given a key signature, like for example two sharps, we only know the collection of tones is C# D E F# G A B, but we don't know the tonic, so we don't know if the key signature means key D major, or key B minor, or mode A mixolydian, etc. etc.
Some people will say that your two modes C ionian and A aeolian are the same as keys C major and A minor. That is true only in the superficial sense that the key signatures of C major and C ionian and A minor and A aeolian are the same. But in terms of harmony, and the stylistic differences between major/minor keys and modal harmony, those pairs are not the same.

How to avoid C Ionian theme when I am playing in A aeolic?

You will avoid that by proper handling of the tonic for each mode. How to do that is beyond the scope of this question. You need a lot of study to get a good understanding. But a simple rule of thumb you can try is emphasize the tones of the tonic chord to establish the mode. So, for example in A aeolian, write a melody that emphasizes the tones A, C, E, especially at the beginning and ending of the music. Traditionally, the melody will start and end on tone A.

And A aeolic its supposed to be melancolic while C Ionian is likely an happy mood isn't that right?

Yes, that is the general idea. But don't take that idea too far. There are plenty of examples of music that do not fit that simplistic notion of mode and mood.
Technically we want to understand it's the third scale degree that is primarily responsible for the differing mood. In aeolian the third scale degree is a minor third above the tonic, while in ionian the third scale degree is a major third above the tonic. The differing major/minor quality of the third scale degree creates that difference in mood, or "color" as it is sometimes, and less subjectively, described.
You can consider other possible moods. Minor doesn't necessarily feel sad. It can be dramatic or confident. Major isn't necessarily happy. It can be stately or majestic. Many, many moods are possible. In addition to mode, rhythm and tempo are hugely important factors for creating moods.
Comment: The OP said they were a beginner so I tried to avoid anything about form. I was thinking of a single line, something on the scale of Three Blind Mice.
Comment: I think the most useful part of this answer is "So, for example in A aeolian, write a melody that emphasizes the tones A, C, E, especially at the beginning and ending of the music.", except I would say "especially at the beginning **or** ending of **melodic phrases**". If you want to establish a minor mode before the very end of a piece, you can do it within a melodic period or sentence. I see it as analogous to language. Where one can say "I went to play football..." and that's neither happy nor sad until it's completed with "but it was rained out" or "and we won!"
Comment: IMO, rhythm and form are essential tools in setting the mentioned _emphasis_ to certain notes. But talking about how to use rhythm and form is more difficult than talking about which notes to emphasize... On this site, I guess we are constrained to talking about those aspects of music that _can_ easily be talked about. :)
Comment: Yes, rhythm and form are essential. But let's not get the cart in front of the horse. The answer needs to be a summary, with some caveats about key/mode, and then the OP needs to spend some time with fundamentals of music texts, some sight singing or solfege, and simple analysis *before* trying to compose. Then composition can be done at an appropriate level to _extend_ what they've studied in texts and real scores.
Answer: There are in fact many pieces which move in and out of C Ionian and A Aeolian. It's the way music sometimes works. And one of the reasons the key signatures are the same.
We tend to define the key of a piece using the note/chord that occurs at a place, usually the end of a phrase or line (the cadence) that feels like 'home' - a place where the piece has come to rest, and could end there. A piece said to be in C Ionian will have C as its resting note, and/or CEG as that chord.
A piece said to be in A Aeolian (A minor) will have that tendency towards A or ACE. Two of those chord notes are the same, which makes recognition that much more difficult.
To emphasise that 'home' chord, that cadence helps a lot. Particularly the perfect cadence - G>C, or e>a. G>C works particularly well, as there's a leading note (B). Sadly, (sic), there isn't such a mechanism in Am, while just using the Aeolian notes. There's no leading note, as G♮ is a tone below the tonic. That's why a lot of times, that cadence is E>a, using G♯ in the E chord.
You can still do that, which leaves you in key A minor, quite acceptable, as there actually isn't a key A Aeolian - only a mode - a set of notes taken from the parent C major.
So, in order to keep the feel away from C Ionian, avoid G>C, but use e>a, or E>a lots, especially at cadence points.
As far a 'melancholy' or 'happy' is concerned, they're maybe not the most apposite terms to use, as Albrecht points out.
Answer: Yes, the 2 modes contain the same tones. But the structure of the melodies in C compared with Am and the functions of the homechord are quite different.
Like Tim says it seems you ask how to differentiate C major from A minor (C Ionian and A Aeolian.
They have a different homechord and homenote. This means in C the first and final motif will fit to the CEG triad and A minor will contain the ACE triad. The final note will be A respectively A.
If theres an upbeat this might be G - C in the melody (= C) or E - A (= Am)
Mind that the leading tone in minor (even in A aeolian) may be altered to G#. The best indication is really the finalis (= final note, respectively last chord = hometone/home chord)
So you will have more intervals like the minor third G-E and the tone G will appear more often because it is the root note of the dominante while in Am the dominant (V) is E.
An interesting example is Obladi Oblada by the Beatles. The first 2 phrases could as well be in Am but the final phrase ,is leading to the root tone of C. Finally the Refrain makes sure this is C major.
I have overlooked the head of your question: (apologize!)

How to avoid C Ionian theme when I am playing in A aeolic?

You should avoid the line So-Fa-Mi-Re-Do and So-La-Ti-Do bcause this
is the  "key"-melody to tonicize the root tone of the ionian mode and the triad do mi so, while the melodic line mi so la and mi re do ti la is confirming the root note LA of the minor mode.
Answer: All the other answers give excellent information on solidifying the Aeolian mode, but there is one thing they don't mention.
Your biggest challenge will be to avoid accidentally slipping into C Ionian.  So do everything the other answers suggest, use cadences on A, and emphasize the pitch A on strong beats of your melody.  But here is the magic trick.
Whatever you do, don't emphasize the notes B and F.. If you use them at the same time in a chord they will point most certainly to C and you will use your Aeolian feel.  If you inadvertently place these two notes too close together in your melody it will draw your ear back to C.  If you use two consecutive chords with those notes, like F-A-C and E-G-B or G-B-D, boom.  You will end up in C.  You'll know you're in trouble when you try to cadence on A and it sounds unfinished.
Why?. These two chords form an interval of a diminished fifth, and it is an incredibly powerful interval that gives sort of a magnetic attraction to C.  In fact, the diminished fifth is one of the reasons that using G# at a cadence helps.  That notes creates a powerful pull to A because it is a diminished fifth away from D.
Answer: We already have good answers, and an accepted one, but it's a good question that's asked often in different ways, so I'll add one more perspective.
Many modes like C Ionian, A Aeolian, and D Dorian share the same set of pitches, but the difference is the center of harmony, the tonic. The center of harmony is not established by making an intellectual declaration such as saying to the audience "this is in F Lydian because I say so", the center is established in the listener's mind, upon hearing sounds. If the pitch set is C, D, E, F, G, A, B and the center of harmony feels like being C, then you say that the mode is C Ionian. But if A feels like the center of harmony, you say the mode is A Aeolian. Your own feelings decide what the mode is to you.
Believe it or not, but two people can listen to the exact same music and perceive a different harmonic center.
Your question is like asking, "how can I move around and keep my center of balance in the same place and not fall over?" If a person does not have the capability to stay upright in balance without falling over, you cannot really explain it to them in intellectual means and have them "understand" how to stay in balance so that they can actually do it. It's a complicated skill of coordination, and even though it can be explained and reasoned about by using physical terminology, you cannot learn to do it by sitting on physics classes. You learn it by doing. Teachers can give you hints and coaching, but you have to learn it yourself.
It's the same with harmonic balance.
In my opinion, the most important factor in placing the center of balance on a particular pitch is rhythm, including pulse and overall form. Another factor is, what the bass note is.
Use a pedal point
One quick and dirty fix for placing the tonic is to play a low pedal point. Play a constant low A bass note or bass rhythm pattern, and it will almost certainly lock the mode to A Aeolian, if all the other notes are from the appropriate scale. Play a constant low C bass, and it will lock your ear to C Ionian. You can compare this to a ship's anchor, it restricts motion.
But a pedal point is a brutal tool for placing the tonic - a good player should be able to place a tonic even by melodic notes alone, without a bass. However, I've noticed that the bass note can help as a guide for melodic experimentation, for developing a sensibility for moving the tonal center. Use a pedal point as a learning aid.
Rhythm affects perception of tonal center
Rhythmic form is an essential tool. What kind of rhythmic pulse do you sense in your mind? Is there a meter where pulses are grouped to measures, or some larger form? Where do notes land relative to the pulse, meter and form? This affects which notes are perceived as having emphasis. And actually, everything affects everything interdependently - whatever notes or other sounds are heard, affects the sense of pulse, meter, and form. And if a sense of pulse, meter and form has been established, all other notes are sensed relative to that.
Example
Two people arrive at different times to a place where this constantly repeating sequence is playing:

How do they perceive the harmonic center? Is it C, D, E, F, G, A or B? Try it: can you make it sound like it's in D Dorian? Play a 4/4 drum beat that starts from the D-F-A chord - does it sound like D Dorian now? How about if you start the beat from the C-E-G chord, does it sound like C Ionian then?
Comment: @AlbrechtHügli Yes, I think harmonic balance is very much comparable to physical body balance. That's how it intuitively feels to me, and how it should be taught and learned IMO. You learn to feel where the balance is, walk and jump around and gradually you learn to sense and control your balance, like a child learns how to walk or ride a bicycle. Like they say, walking is controlled falling. It's not possible to learn physical or musical balance control by reading books and reasoning. I added a remark of a pedal point being like a ship's anchor, that's a good analogy too.
Comment: +1 for the comparing melodical/harmonical with physical balance and the hint *pedalpoint*
Answer: I'm not sure about modern modal uses but the problem of having a minor key composition drift into the relative major has been known for some time (maybe 500 years or so). There are some techniques for alleviating the problem. The biggest ambiguity between a minor key and its relative major is having a VII-III chord sequence in a minor key. Example: in A minor, playing a G major chord followed by a C major chord is aurally equivalent to an authentic cadence in the key of C major. The reverse iii-vi (E minor to A minor) doesn't sound so much like the key of A minor as the chord on E is usually major; it's a bit more complicated the chords sequence v-i is often used throughout a minor key but the same piece may use V-i (E major to A minor) at important parts (cadences at the end of sections.)
Another way to emphasize the minor key is to make sure that VII-III occurs in some sort of sequence (like a cycle of fifths.) (Using lower case for minor and upper case for major chords, 7 for dominant sevenths, and 0 for diminished chords), a section like a-d-G-C-F-b0-e-a will tend to sound like it's in A minor as the sequential nature of the pattern dominates the sound. Even more powerfully indicating A minor would be to replace the e-a chord pattern with E-a or E7-a the last time the pattern appears.
Other methods include using the "raised" version of scale steps 6 and 7 in ascending melodic passages and the "lower" form in descending. That is E-F#-G#-A going up and A-G-F-E going down. (Or E-F-G#-A going up.) I've written more extensively about this here (and on Quora). You can search for questions on minor-key harmony and the like.
The problem of the major key slipping into its relative minor doesn't occur as often (probably because of the lack of an "accidental" authentic cadence in the relative minor.)
Answer: If you're composing or improvising music in A minor, one way to break the relationship to the relative major is to slip out of that natural minor mode into the melodic and harmonic minor. Consider that in the A melodic minor, the run of notes starting on C (C, D, E, F#, G#) form a whole note scale. The ear might perceive a do-re-mi for the first three three, but after that it bears no relation.  The cadences involving the G# leading tone resolving to A will firmly tend to anchor the music to the minor mood.
Which mood is perceived by the listener is a complicated result from numerous factors. For instance, try this: (all 16th notes with ---- indicating a quarter):
C-D-E-F E-D-C-B A-G-A-B A----
G-A-B-C D-C-B-A G-A-B-G A----
To me it sounds grounded in the mood of the A minor scale, in spite of the phrases beginning with do-re-mi-fa tetrachords rooted on C and G; that is, exactly some of what you say you're trying to avoid). This is probably a combination of

Past exposure to hearing these kinds of phrases together with a harmonic interpretation in more complex pieces of music featuring chords and counterpoint.

Emphasis on the ending note A, which leaves a stronger impression than the starting notes, probably because it is longer and more recent. Also, the previous beat before the longer A contains only two different notes A and G, and A is repeated. It is already signaling a convergence on the A.

In the first phrase, the emphasized notes (first notes of each quadruplet) are C, E and A, belonging to the Am triad.

The second phrase after the first fits a known pattern: the music shifts to the G, which the deceptive dominant in the G-Am cadence. So that is to say, Am music sometimes goes to a higher energy point centered on G (rather than, say, E), which falls back to A. We perceive the second melodic line as the "G response" to the "A call", and therefore that it fits together and continues in that mood.

If you have an accurate intuition for this sort of thing that think you can trust, then all you have to do is generate melodies and judge whether they have the effect you want. If not, replace them by something else until it works. If the music is going to be harmonized, it's not necessary for the melody alone to set the mood. Melodies that are "ambiguous" in some sense can acquire their "direction" from other notes.


How can I analyze the impact of each browser extension on Gmail loading time?

Question: I use a couple of Google Chrome Extensions to improve Gmail Web interface (Fix Compose for Gmail, Streak, etc). Is there any way to analyze the impact of each browser extension on Gmail loading time? (without having to uninstall extensions)
Answer: There are a few programs that can track the loading time for pages for you.  Programs like Benchmarking Extension have many options to play with.
There is also a Chrome Extension called Page load time which measures page load time after you load a page. All the events are displayed with their individual load time.
Additional Solution:
GMAIL takes time to load the emails. It could be considered as a download. There are many plug-ins and options to track downloads. Setting a timer is easy.
It is a Chrome extension used by developers. It may be a little complicated to use. I haven't played with it so it may not wait for extensions to load on page. There's many options.
Disabling all extensions and loading one separately would give you some idea.
Either way, you could check how big an extension is and count the number of loops.
A small efficient script with a lot of loops will take as long to load as one with many definitions and resources.
There are many duplicates to this question : I have run the following search terms -> chrome with extensions loading time.


How to get bone meal effectively by composter?

Question: I need bone meal to fasten the growth of trees because I live in a survival island. I have grown many crops and what crops should I put in the composter to earn bone meal effectively?
Answer: The wiki lists all the things you can put into a composter and their probability to increase the fill level inside here (archive). Carrots, beetroot, wheat, potatoes, pumpkins and melons each have a 65% chance, but cooked potatoes have an 85% chance to increase the level. Melon slices have a 50% chance, so putting in full melons isn't worth it. It's also very easy to build a cactus farm, cacti have a 50% chance as well.
But I would not recommend using a composter to get bonemeal. If you build a mob farm, you get many more useful resources (bones, gunpowder, string, ender pearls, occasionally redstone, bottles, glowstone, …, if manual killing also weapons and armour, …) and it runs without any manual activity (you just have to be within 128 blocks) and without needing to sacrifice your crops. In my most active Survival world I almost filled two double chests with bone blocks, just from standing at a skeleton spawner farm for XP.
Of course this does not work if you're playing in "Peaceful" difficulty.
Comment: How can you not have the resources for a mob farm? In the simplest case you just need solid blocks and trapdoors.
Comment: I do not have resources to create mob farm and I never go out at night
Answer: It's been quite a while, but this Insane Ilmango bone mela farm design is very good
Comment: While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference.  Link-only answers can become invalid if the linked page changes. - [From Review](/review/late-answers/321606)
Answer: A miniature mob Farm would consist of nothing more than maybe 4-6 stacks of stone, a few redstone materials as well as maybe half a stack of iron. (So definetly in your budget)
You would just build one spawning platform over the ocean which gets flushed with water in regular intervalls, triggered by a a clock of your choosing ( hopper clock for example).
Mobs fall into a permantly flushed field and get pushed onto a single magma block und which you position your hopper minecart.
This is definetly not the best farm but it works fine and is scalable by increasing the number of plattforms.
Do not forget to build a roof over the plattform which needs to consist of lower half slabs


Observer Effect

Question: The standard explanation for the observer effect is that a small amount of energy from the observer causes the wave function of lets say an electron to break down and for it to develop determinate characteristics rather than probabilities. However why doesn't this happen anyway baring in mind that until its observed it has a probability field spanning the entire universe. It is therefore literally in contact with that energy the observer imparts in the act of observation anyway along with everything else, and yet that doesn't magically cause the probability field to break down. Why only when there is someone who can know things at the other end of this magic energy does an electron take on specific characteristics that (by massive coincidence) can be known?
Answer: The concept you're looking for is decoherence. Indeed, it happens whether or not an observer is looking. For quantum computer builders this is unfortunate: it would be so much easier if all they had to do to prevent wave function collapse was to avoid looking.
The connection with observation is that observers are incoherent physical systems: decoherence is a necessary feature of the coupling of the observer to the observed. But many other incoherent physical systems exist, and interaction with any of them will produce decoherence. Coherent quantum behavior is only seen in systems isolated from such interactions.
Comment: @mmesser314 On the basis of many experiments and observations, we know that decoherence is a reasonable model for what we see in reality. But whether parallel worlds exist is a vacuous question scientifically: there is no experiment that can test this hypothesis.
Comment: It is objectively ridiculous to posit an infinitely splitting multiverse to answer why quantum measurement is weird. Whether such a notion appeals to you for some reason or not, it is not   possible to settle empirically and thus it is not a scientific question. Worse yet, it might be the most abuse that Occam's Razor has ever gotten.
Comment: Veritasium has a good explanation of decoherence in the context of Schrodinger's Cat. It is part of his explanation of the "Many Worlds" interpretation of quantum mechanics. [Parallel Worlds Probably Exist. Here's Why](https://www.youtube.com/watch?v=kTXTPe3wahc)
Comment: True. I was trying to say that it is a good explanation of decoherence wrapped in other things that are not part of what is being asked. Never the less, it is a good explanation of decoherence.
Comment: @mmesser314 It is not true. Decoherence is never complete, so a small remnant could (in theory) always be measured. Besides there are many other examples of things that we cannot see where we still don't think that  their existence is a "vacuous" question. This is simply an overly polite attitude towards people who refuse to believe QM. (OK, if your thesis advisor is one of those, it could be wise of course...)
Answer:
The standard explanation for the observer effect is that a small amount of energy from the observer causes the wave function of lets say an electron to break down and for it to develop determinate characteristics rather than probabilities.

There isn't a standard explanation. Interpretations that involve wavefunction collapse say nothing about the mechanism by which the collapse happens, or propagates through spacetime. It's simply asserted, as an axiom. Interpretations that don't involve wavefunction collapse, like the 'Many Worlds' or Everett Interpretation, do offer an explanation, but neither the interpretation nor the explanation are universally accepted by physicists.
For a brief, hand-waving explanation of how the Everett Interpretation deals with the question, see here. It's not specifically a contribution of energy that triggers the split, but interaction. The observer can provide energy to the system, or absorb energy from the system, or interact in some way that leaves the energy the same. Briefly, if the system observed is in a superposition of orthogonal states, and the observer interacts with it, then after sufficient interaction time the observer shifts to a similar superposition of orthogonal states. 'Orthogonal' means the states do not interact, and thus cannot perceive one another.
The step to classical probabilities hasn't been fully worked out yet - the following is another hand-waving explanation of roughly how we think the argument will go. When the observer system is big and complex, and has zillions of possible states, the split is into a multitude of orthogonal states. In some fraction of them, one outcome is observed, in the rest, the other outcome is seen. By Pythagoras, the squared length of a multidimensional vector is the sum of squares of the individual amplitudes, so if we assume that the total magnitude is conserved, and the individual components are of roughly equal magnitude, then the fraction of the zillions of observer states seeing each outcome will conform to the squared amplitudes of each component of the system's superposition, and will behave like classical probabilities. This is called "decoherence".

However why doesn't this happen anyway baring in mind that until its observed it has a probability field spanning the entire universe. It is therefore literally in contact with that energy the observer imparts in the act of observation anyway along with everything else, and yet that doesn't magically cause the probability field to break down.

For collapse-based interpretations, the wavefunction does collapse, but it collapses to a state virtually identical to the original. The difference between a wavefunction that extends to infinity with an exponentially small probability around the observer, and a wavefunction extending to infinity that is zero close to the observer is imperceptible. The probability field breaks down to zero near the observer, and jumps up slightly by an imperceptible amount everywhere else. It makes no difference to the experimental predictions, so we commonly ignore it, or pretend it doesn't happen.
It can make a difference if the probability is high enough. Imagine a radioactive atom surrounded by detection screens at various ranges. The atom decays and pings off an electron whose wavefunction makes a spherical wave. It hits the closest screen, and immediately collapses to either a detection - where the rest of the spherical wave abruptly vanishes - or a non-detection - where the wave vanishes over the closest screen and abruptly strengthens everywhere else. As the sperical wave passes each detector, it collapses again and again, until the electron is detected. It has to happen this way to guarantee that there will be exactly one detection. The electron cannot be observed at two places at once, and it cannot disappear entirely. And if the detector screens are far enough apart, there is no time for the 'collapse signal' from one detector to reach any of the others in time to tell them what to do.
That is to say, a non-detection (with no exchange of energy) can collapse the wavefunction just as much as a detection does.
In no-collapse interpretations, the split into the superposition of mutually-invisible orthogonal states happens, but one of the components is much smaller than the others. It looks the same to observers.

Why only when there is someone who can know things at the other end of this magic energy does an electron take on specific characteristics that (by massive coincidence) can be known?

The idea that conscious awareness of the outcome is needed to trigger wavefunction collapse was (I think) part of the early development of quantum mechanics, but I think is mostly rejected nowadays.
Collapse-based interpretations are pretty vague about exactly what triggers a collapse. Decoherence is widely thought to play some role - but how you can get non-linear behaviour from still-linear equations is mysterious. Or there are explicitly non-linear theories of collapse, which are in theory testable, but which currently are pure speculation with no evidence for them.
The Everett Interpretation holds that when an observer interacts with a system in superposition, that particular observer enters the same sort of superposition, but other observers don't. So if two electrons interact, then that constitutes observation of one electron by the other, and the electron sees only one outcome, but we as an outside observer see both electrons in entangled superposition.
The appearance of "collapse" - seeing only one possible outcome, picked at random - only happens when you are in a superposition of orthogonal states. Only observers perceive the collapse. To everyone else, the system and its observers are still in superposition, and they will only perceive the collapse when they make an observation on the observers.
It's essentially the same question as asking whether a single electron passing through one slit of the double-slit experiment "sees itself" simultaneously passing through the other. If they did, they would repel electrostatically, and that would change the interference pattern. Since there is no change to the interference pattern, the electron passing through one slit does not "see" the alternatives, and thus as far as each component of the electron's wavefunction is concerned there is only one outcome and the wavefunction has already collapsed. However, this is an illusion caused by being inside the superposition. The component orthogonal states are mutually invisible.
The Everett Interpretation works by taking the linear, local, realist, deterministic, reversible evolution of the wavefunction that everybody accepts applies at the microscopic level in the absence of observation, and points out that if we ask what it would look like from the inside, we predict the appearance of classical physics. So there is no need to posit wavefunction collapse as an axiom. The observations it is meant to explain are already explained. However, since the alternative components of the superposition are forever unobservable, we have no way of proving they don't magically disappear. Thus, this is an 'interpretation' and metaphysics. In the absence of evidence, do you prefer zillions of forever-unobservable alternative 'worlds', or mathematically ugly and forever-unobservable mechanisms to make them disappear? There is no experiment we can do to distinguish them. Which you prefer is down to aesthetics and utility.

Observer Effect


OFDM with beamforming

Question: I'm trying to compute the the interference that one OFDM user with beamforming causes to another user. The two systems are fully overlapped in frequency and time. I know how to generate an OFDM signal in MATLAB and compute its BER in AWGN and fading channels, I just don't know how to implement beamforming. The beamform is a circular sinc, I believe I need multiply my signal with the gain of the main lobe of the sinc function. I don't know how to calculate the interference caused on the other user. I'm not asking for anyone to provide me with a code, I'm just hoping that someone here can provide some directions on how to approach this or if there are any other resources that I can check.
Comment: Beamforming describes the distribution of transmit power in space so I think there should at least one spatial dimension be involved.
Answer: The interference you cause to the other user is determined by:

The total transmit power of your transmitter
The gain of your beampattern in the direction of the other user
The path loss to the other user
If the other user uses receive beamforming, then also by the gain of its beampattern in the direction of the transmitter

So if you transmit with a power of 10dBm, have a gain in the users direction of -20dB and a pathloss of 60dB, the other user receives -70dBm of interference power from the transmitter. Whether or not this is bad then depends also on how powerful the useful signal of the other user is.
More information is required here for a more detailled answer.
Comment: Thanks for the answer. The scenario I have is 3 users located within range of each other. Users 1 and 2 are communicating with each other, user 1 is the transmitter and user 2 is the receiver. These two users will cause interference to user 3, all are using the same frequency resources. Of course if user 1 is using an omnidirectional antenna, the interference caused will be high. I want to compute the interference at user 3 when user 1 is transmitting with a beamforming antenna for different angles of the beam. I'm particularly interested in evaluating the performance under different ante

OFDM with beamforming


correct 2 pole breaker to use with a 200 amp transfer switch

Question: I have a Generac 26K generator with a 200 amp transfer switch I have a 200 amp main service. I want to be able to power my entire house in case of a power outage.  What size 2 pole breaker do I need to put in the main service panel for the transfer switch.
Comment: Have you considered what it might take to power your *entire* house?
Comment: To get a good answer, provide more details: transfer switch model, how mains and generator are connected to your home, etc. I recommend derating your generator by 30%, that means you will have 18KW/75A of useable clean/reliable power.
Answer:
I want to be able to power my entire house in case of a power outage.

Your entire house? In case someone wants to run a dryer load?  Keep that hot tub hot? Charge that EV anyway? No compromises?
NEC 702.5(B)(2) says the generator "shall be capable of supplying the full load that is transferred".  That means you'll need to do a NEC Article 220 Load Calculation on the service, such as 220.82 here, and make the generator that big.
Your generator is only good for about 110 amps, so you'd need to have a fairly light Load Calculation, or deploy some alternatives.
First option is automatic load shed devices. These attach to an appliance circuit and monitor it for voltage or frequency sag, the hallmark of a generator bogging, and drop out their load when that happens.  A load thus protected can be removed from the Load Calculation.
Second option is a critical loads subpanel so you just don't have the "too much" loads on the generator at all.  Now in a case like yours, it's too much work to move dozens of small circuits out of your main panel into a subpanel.  It's a lot easier to remove 2-3 loads and put them on a non-backed-up panel.
You can put a "trailer/ranch panel" with thru lugs between your meter and your existing main... and put your non-critical loads in the 8 spaces in the ranch panel.  You come off the thru lugs to the transfer switch then onward to your "main" panel.
They even make trailer panels with built-in electric meters, but I'm not a fan of these because of changes coming in electric cars and vehicle-to-home.
The trailer panel is also a great place for surge, solar, geneartor interlock for a smaller generator, etc.


Generate email from an user's own mailbox on Power Automate

Question: I have created a workflow via Power Automate to send an email to a list of people when an announcement is created on SharePoint. It works fine if I would like to be the person who appears as a sender of that email. However, this workflow will be used by a few users in another department, and I would like these automated emails be generated with these users who become the sender. At present, if someone else posted an announcement, the automated email will be sent as if I posted it myself. Is there a way for the email to be sent from whoever logged onto Office 365 at the time? Thanks.
Answer: You can use "From (Send as)" for emails sending from Power Automate to appear have been sent from the user's account who created the item. However, for that to work, users creating items should have "Delegation" permission on the email account of the user running the flow. You can find more info on that here.
Comment: Hi, thanks for this. Is there another way to do this without delegating?  I am hoping the users can run the flow using their own account instead of going through me.
Comment: I'm afraid that you don't have any other option as your flow is triggered when item is created. There's a "Run as" option, but that is applicable for **manually** triggered flow. You can read more about that [here](https://www.serverlessnotes.com/docs/sharing-flows-as-owners-and-run-only-users)


Can I grab the Social Accounts and Contacts Images?

Question: I've enabled Social Accounts and Contacts in our org, and now I'd like to grab that image from Salesforce via API to display on our external website. I'm particularly interested in the Twitter image. Is this possible?
Answer: Take a look at this answer:
Is it possible to connect a social networking profile to a custom object record?
The gist of it is that you can't query for that object via SOQL right now, so you unfortunately can't pull any of that data for your own use.


Why participating in open source helps freelancing?

Question: I read lots of posts here that suggest participating in open source project, I just wonder how does this help to improve freelancing?
Answer: Assuming you're a programmer...

It shows you have hobbies or interests you are willing to work on in your "down time". People with hobbies tend to be really excited when they get to also get paid for doing what they love. If you show you love programming for free (or to improve the world through software you love using...), then you'll love whatever project the client may throw at you.
It shows your coding styles. Not everyone follows the same convention, even though everyone tries. I have my own style that works for me, and it's a mish-mash of many coding standards. I never grew up learning coding styles, so I invented my own. If the client wants to see your work, it's easy to see if it's what they are expecting, or if there will be a large learning curve for you.
It shows you work well with a team. If you have 2 contributors (yourself included), that is not quite as impressive of a feat as working with 300 contributors. If you can work with others, that's a great feature if the client is looking for either a team, or to pass code on from programmer to programmer to programmer during the program's life.

Those are my top three reasons to contribute to Open-Source Software Projects on my portfolio; I don't have any contributors except myself, but that's because programming is far, far, FAR down my list of what I want to do for Freelance work right now.
Answer: For me, as a freelance, an important thing is to build a network, working on open source project helps you build your network. on top of what Canadian Luke has said, I'd add :

Working on project you will "meet" people (not physically), they will contact you to add a feature on the project or they have a bug. Knowing those people can help you get job at their company specially if they have interest in the project you're working on.
If by chance you get to work on open source project that gets hype, the project might already be used by potential clients, it might help you as contributor of the project to get a deal with those companies
You learn a lot and you learn from others. if your project gets some visibility, others will see and you might receive pull request, you'll end up working on things you did not know before and you improve your skills a lot
Answer: Being a freelance developer, participating in open source projects (or FLOSS projects) can provide a pretty good reputation for yourself:

Your software abilities are well-known
Open Source projects generally have the source code available to anyone, and many hosting services, such as GitHub, have the ability to show the quality and amount of contributions you make to projects. This means that people have the ability to see what you contribute: be it entire revisions to source files, or simple patches to nasty bugs. This has the added benefit in that it directly shows what you know, your abilities and competences as well. If you can program in multiple languages, it shows. If you can find a nasty bug, it shows. If you can rewrite an entire script, it shows.
You show that you can collaborate
Collaboration isn't just talking with Friends together in a cafe. People all over the world contribute, and maintain open source projects. Since you're online, you've got to act professional, and you need to be nice. Taking GitHub again as an example, you need to show that you are able to raise issues, feature requests, and notices while coming across as respectful.
If you are the maintainer/owner of a project, there comes an added bonus. As you would be responsible for accepting pull requests, it is important that you accept and reject calmly, and most notably with messages that specifically describe why you follow such an action. As you make the decisions for your projects future, it's important that you discuss with end users and show that you care.
You show that you've got an interest
Open Source development is best when you don't have much experience working on a job. Entry-level programmers that don't normally have much work experience, and those who are unemployed and self-employed, often participate in open source projects to show that they are still committed. No one likes looking at a CV (Resume) to show large periods of inactivity. Participating means that you still retain skills, whether they be programming related or not. I'm not a professional programmer myself: I'm still a 15 year old person in school. But I still make projects, post it on GitHub, and place good licenses on them: to show that I have an interest, and in a bid to further develop the skills that I already have.

These are just a few points. Obviously, you'd want to let prospective people know what you do, so make sure that you make known your contributions to the software community as well. Good luck!


Why would John Hammond build the visitor center out of glass?

Question: While reading the book Jurassic Park, I read that the visitor center was made almost entirely of glass with a black metal frame. Apparently, this made the building look 'very modern and hi-tech'. While this would give the building a nice aesthetic, my question is, why would John Hammond build the visitor center, arguably the most important and vital structure on Isla Nublar, out of glass? This seems like a really bad idea, especially since Isla Nublar is full of dinosaurs. In-universe explanations only.
Comment: Why not? The visitor centre helps sell the park, so if the structure is strong enough, aesthetics are a major consideration in the design.
Comment: If they're looking in the visitor centre you're probably already in deep trouble.
Comment: it still seems like a bad idea. I mean it IS an island full of dinosaurs....
Comment: @Michael is right - if the Visitor Center is threatened by dinosaurs, you shouldn't be in the Visitor Center. You should be leaving the island.
Comment: Well they were so careful keeping the park a secret and spent a long time trying to prevent an accident, (funny how the contract Dr Grant signed had a code in it that was hard to decode, but got there entire computer system hacked by a fat guy with shaving cream), so they didn't plan for dinosaurs to actually escape and go to the visitor center
Answer: Hammond's sin is hubris. He doesn't see the animals in the park as a major threat, hence there's no need to give the visitors (in the Visitor Centre or elsewhere in the park) any more protection than is specifically needed to keep the animals in their pens, physically separated from the human accessible areas.

"Let's not start on the velociraptors," Hammond said. "I'm sick of hearing about the velociraptors. How they're the most vicious creatures anyone has ever seen."
"They are," Muldoon said, in a low voice. "They should all be destroyed."
"You wanted to fit them with radio collars," Hammond said. "And I agreed."
"Yes. And they promptly chewed the collars off. But even if the raptors never get free," Arnold said, "I think we have to accept that Jurassic Park is inherently hazardous."
"Oh balls, " Hammond said. "Whose side are you on, anyway?
Jurassic Park

Admittedly it takes a nested series of unlikely failures before the dinosaurs get to the visitor centre at all; the removal of the electric fences, a disgruntled employee actively subverting their security systems, an unseasonable storm, consistent underfeeding of the T-Rex and a set of poor assumptions about how the dinos will react, etc etc. to get things to the point where the safety of the visitor centre is even an issue.

For the record, This glass and steel confection is the visitor centre at the Lincoln Park Zoo where they host a variety of creatures that could easily kill a human (especially a child) if they escaped.
Comment: don't forget a disgruntled employee to make it all happen
Comment: @OldNoName Wasn't it a disgruntled IT guy? These are even more dangerous.
Comment: Really? Dennis Nedry is the f**ing hero of this story if you ask me. A single guy to run all the techops of the entire facility? Clearly working extra hours and completely underpaid to the point it's starting to affect his health (he's dealing with overweight due to anxiety and stress). And when he goes for a f***inf second to the bathroom and there's a crisis the first thing is to pull him out?? Really? No backup? What happens at night? Does he also get woken up??? In my opinion they did all got what they deserved and the only thing I'd change is the tragic death of the hero.
Comment: Well the zoo has big cats, Jurassic Park, has friggen dinosaurs, soooooooo
Answer: First of all, it's construction grade glass, that stuff is more durable than we give it credit. Hammond was a much more shrewd business type person in the novel. In the movie, Spielberg portrays him more like Andrew Carnagie, more sincere but still business acumen.
Concept art depicted the facility with elevated and separate array, inspired by John Lautner's architecture.

Remember this novel was written in the 80's, back then steel and glass was corporate chic....
Comment: that concept art is for the movie, the book is the source of the question
Answer: It might be ineffective to design a visitor's center that looked strong enough to hold out dinosaurs but wasn't that strong.  It is possible that a building actually strong enough to keep out really large dinosaurs would be too expensive to build.
It seems to me that a visitor center that looked strong enough to you might not actually be strong enough to keep out the larger dinosaurs.
For example, I once read of a parade of circus elephants that stampeded in a US town.  One elephant smashed in through the front wall of a wooden frame building, through the interior walls, and out through the back wall of the building.
I have read a Victorian era article which mentioned a big bull elephant chasing all the villagers out of a village in India and then picking up and tossing the houses (presumably tiny one room shacks) hard enough that they splintered when they hit the ground.
I have read an online article mentioning that a man in India was injured by a flying brick when an elephant broke a hole in the wall of his house and reached in to grab a bag of rice.
In India, elephants are used to demolish buildings erected by squatters in a wildlife preserve.
Years ago I read of elephants being used to demolish illegal buildings in cities in India. Animal rights groups objected, fearing that the elephants might be injured by falling concrete and other construction materials.
I once read an account of two bull circus elephants fighting during winter quarters. The fight ended when the winner pushed the loser through the wall of the elephant barn, which was made of bricks and 14 inches thick.  Neither elephant was seriously injured.
So I find it easy to believe that a building might look like it could keep out even the largest dinosaur, and yet be easy for a large dinosaur to break into.


Are there examples of classes with students publishing their reports instead of just turning them into TA & Professor?

Question: Am interested in learning more about student publishing. Is there a list of courses where students are publishing their work instead of just turning them into their TA and professor?
Comment: In the U.S., it would be legally problematic to make publishing anything a requirement to pass a class. Can't imagine a professor who would go there. However, some professors assign writing on Wikipedia, either as voluntary, extra credit-type assignments (to avoid the legal issues I mentioned) or in such a way that the writing is required but the publishing is optional. I have done this myself, and discussed it on another answer here at some point - will try to find the link later and post it here.
Comment: It mathematics it often takes over 1 year to publish an article...
Comment: Are you asking about publishing something akin to research? If so, most professors who encourage it still require everything be turned in to them as an assignment, but then also encourage interested students to extend into publishable research if they are so inclined.
Comment: [Here](http://academia.stackexchange.com/q/69456/40589) is the link to the question I mentioned discussing Wikipedia writing assignments.
Comment: @DanRomik While I agree that it's a bad idea, I'm curious what _legal_ problems you think a publication requirement would create.
Comment: @JeffE off the top of my head, I think it could be reasonably claimed to be a FERPA violation (similarly to a professor insisting on publicly posting a student's final exam), and to raise copyright issues. Not sure if actual case law exists that makes any of this specific, so what I'm saying is speculative, and of course IANAL. Basically forcing students to publish things seems like a major invitation for trouble, legal and otherwise.
Answer: Disclaimer: As I've only been a graduate student at the university I'm currently attending (USA) I can only comment on my individual experience at this university in my particular field (computer science) and the classes that accompany it.
Experience: I have a publication currently accepted that is the direct result of a course I took.
Throughout my time as a graduate student I've observed several class formats as far as expected work goes, typically involving some combination of homework, exams, and projects. Those involving projects, particularly when greater emphasis is placed on the project, are those rife with opportunity for publication. An additional indication of this is if the faculty member is teaching the project-based course in his/her area of research.
If your intent is to take a class with the hope of turning your work into a publication I would recommend taking a course where the above align (project-emphasized course work being taught by a faculty member whose research area is the same as that of the topic being taught).  Additionally, I would recommend:
1) Choosing a class that aligns with your own interests and research.
2) Speak with the professor prior to the start of the class about your intention of turning the project into a publication. The professor should be able to comment on whether their project is a good opportunity for such an endeavor and perhaps be able to provide you with advice on how to be successful in completing the project and turning it into a publication.
3) In discussing with the class instructor, it would also be a good idea to discuss project expectations, particularly as they relate to (a) working with other class members and (b) the criteria that will be used to grade your work. Regarding (a), not all class members may be interested in going the extra mile to turn a project into a publication. Having this discussion with the professor up front will mitigate the chance of encountering "snags" related to this (e.g., you be given an exception to work on the project by yourself). Regarding (b), the criteria used to grade your project may be slightly different than what it takes to make a publication. Granted your intent, and what will almost certainly entail a greater amount of work, some leeway may be granted to you if tasks to create a publication and those needed to earn full marks on the project don't line up entirely. This, of course, depends on the instructor.
4) Getting [at least] some preliminary idea of the course material and ongoing research in the area of the topic of the course, prior to its start, will help. Furthermore, having some project idea (i.e., research idea) in mind, would be ideal. This can also be discussed with the professor.
I'm sure there are points and recommendation that could be made here, as well as other scenarios, which may vary by field and university, but for me, in my own unique experience, these were the highlights that led to my course-based publication. Best of luck!
Answer: Although this might not be exactly what you are looking for, I recently learned that a course at my institution publishes student work in a free online journal, found here.
Certainly, publication in this format does not have the same prestige or distribution of a typical journal, but the studies are original even if they are not ground breaking. The works are reviewed by several faculty members and give the students an opportunity to produce a professionally formatted research paper, and give them a citation they can use to demonstrate their research/writing ability as they move forward in their careers.
Personally, I think this sort of approach is excellent experience for undergraduates. I don't think the level of work that you can expect students to put into a course could ever be expected to result in a publication in a mainstream journal (in a large enough sample size there could be exceptions, of course), though work produced in a course could certainly motivate a project that is publishable in the future after appropriate elaboration.

Disclaimer: I have no affiliation with the course I link to, though I am an employee at the university.


Customize page numbering in plain TeX (not LaTeX)

Question: I would like to change the page numbering from the default 1, 2, ... to the corresponding symbols in my native language. I have the fonts and typesetting ready and just want to replace the page numberings. How would I go about it ?
Comment: Welcome to TeX.SX! Can you give some more clues? Are just the symbols different from Arabic digits, but the numbering system is decimal? Where are the symbols in the font?
Comment: how you typeset numbers depends on your native tongue: Roman is not Arabic. What exactly do you want to do?
Comment: Hi, I am the original poster. (just registered in TeX stackexchange. Cannot figure out how to edit my guest post) The number system is decimal. Following the lead given by Henri Menke below, I did the following which worked : \footline={\centerline{\od \folio}}. \od refers to the fonts I am using. Thanks everyone for the quick response.
Comment: you can ask for moderator help to merge accounts.  see [Help Center > My Account](http://tex.stackexchange.com/help/merging-accounts)
Answer: The page number is typeset by adding it to the token list \footline.  By default the page number is preprocessed by the macro \folio, which outputs a roman numeral if the page number is negative.  Below you can find the default definitions of plain TeX.
\footline={\hss\tenrm\folio\hss}
\def\folio{\ifnum\pageno<0 \romannumeral-\pageno \else\number\pageno \fi}
Text
\bye


Am I liable if I know about copyright enfrigement of software my collegue is copying?

Question: If I know about a colleague who is copying public available code into our software stack, infringing copyright law on purpose, too which extent am I liable under German law? Can I refuse working on the same files/project that include these copied lines of code?
Answer: I assume "our" software stack is owned by some company. And "public available code" usually comes with a license.
You are not saying which license. If the code was published under the GPL license for example, adding it to your code is legal. Distributing it without following the terms of the license is copyright infringement. That copyright infringement would likely be committed by your company.
However, if your company loses a court case and has to pay huge damages for this, or has their reputation destroyed, or is not able to sell the software, because you allowed this to happen, you would be likely to lose your job and possibly be sued for damages. Your colleague obviously even more so.
I would strongly recommend that you go to your management and inform them. Any company I've worked for would put an immediate stop to it (I never worked for companies creating open source software). In the unlikely case that they are Ok with it, best visit workplace.stackexchange.
Comment: I have not investigated this further, but I am assuming exclusive copyright, especially if this includes copying code from stack overflow. The point on GPL is also a good one as all copied and modified code will be GPL and therefore has direct implications on myself.


Low pass filter for ADC signal input

Question: I want to put a low pass filter infront of my ADC. The ADC's sampling rate is 10MHz. I want to sample a signal with a maximum frequency of 50 kHz. So my cutoff frequency for this low pass should be slightly higher than 50 kHz, right?
Answer: Correct and the closer to 50 kHz (but above) the easier it is to make an effective anti-alias filter. But no need to go crazy about it. A 2nd order low-pass filter set at 100 kHz will provide 40 dB attenuation at 1 MHz and 80 dB attenuation at 10 MHz and, those aliased artefacts that might sneak through could easily become lower in amplitude than the resolution of your ADC.
You need to concern yourself with the parts of the spectrum that pose a threat and if there's nothing expected above 5 MHz (half the sample rate) then why bother? But if there are things happening above 5 MHz, what amplitude do they have? If they are already 40 dB down in amplitude then the filter has an easier life reducing them to an amplitude below where they might cause problems.
Comment: Then it isn't a square wave any more. A square wave is composed of a fundamental and odd harmonics so, if the fundamental is 50 kHz then there are significant "wanted" harmonics at 150 kHz, 250 kHz, 350 kHz etc.. Of course, if you don't care about preserving those harmonics then you can have the low-pass filter set just above 50 kHz but, what you then get in the digital domain is neither a sinewave nor a square wave but something halfway between.
Comment: Ok thanks let say I have a square wave of 50 kHz. I thought about using a low pass filter with a cut off frequency of 5MHz (100*50kHz). Or should I go lower like 1MHz or even 500 kHz?

Low pass filter for ADC signal input


Write and read problem while interfacing 93LC46B EEPROM through SPI

Question: I try to save and read data from 93LC46B EEPROM using SPI with Arduino UNO.
I'm following this article https://www.arduino.cc/en/Tutorial/SPIEEPROM .
So far I have correctly connected EEPROM pinout (as shown in 93LC46B EEPROM datasheet) with arduino MISO, MOSI, SS, CLK, I copied the code from link and here is the problem, I cant save data to EEPROM, it should be filled with buffer but it is not, whats more everytime I try to read data there are different values on same addresses. How can i solve this problem ? Thanks in advance
Comment: Post your circuit and the relevant code and what you see going wrong and what you expect.
Answer: The quick answer is that 93LC46B is not compatible with AT25HP512. You can not use that tutorial. There are many differences.
Have a look at this blog instead: http://owlsan.blogspot.com/2012/10/accessing-93c4693c46n-serial-eeprom.html


KDE and gnome canvas

Question: Is gnome canvas supported by KDE ? Etherape Crashes when opened within KDE and complains that gnome canvas isnt supported. If this is true is there a way of importing "gnome canvas".
Or are there any other known workarounds ?
Comment: Please provide more information on the crash screnario. Generally, it is possible to use Gnome Canvas in KDE Plasma environments, yes.
Answer: From https://etherape.sourceforge.io/ - Overview of changes in EtherApe 0.9.18 (Sunday, June 3, 2018): EtherApe now is a pure GTK 3 application, with canvas supplied by GooCanvas.
Install GooCanvas, then install "Shutter" and reboot - works for me.

KDE and gnome canvas


How can planes land on a rotating Earth?

Question: If the earth is rotating (e.g. at 1000km per hour, at the equator), how can planes safely land on a moving runway?
Comment: In the same way you safely land when you jump.
Comment: It's 1667 km/h actually.
Comment: Related: http://physics.stackexchange.com/q/1193/2451 and links therein.
Answer: It is the relative velocity between the plane and the Earth which is important.
When the plane is at rest on the runway it is moving at 0 km/hr relative to the ground but also it is moving at 1000 km/hr due to the rotation of the Earth.
So if the plane is coming it to land at 150 km/hr that is 150 km/hr relative to the ground.
If a plane needs to travel due North then it does have to compensate for the rotation of the Earth and so must fly on a heading which is West of due North to arrive at a location where the speed of the Earth's rotation is less than 1000 km/hr.
Comment: While you are correct, but the rotating air plays an important role in maintaining that relative velocity.
Comment: While a plane may have to compensate for strong atmospheric winds indirectly caused by the rotation of the planet, if there were no wind and a plane traveled north from Africa, it would *not* have to compensate in order to not land in North America.
Comment: @Neil Assume no atmosphere. On the Equator the plane and the Earth have a velocity of 1000 km/hr due East.  As the plane travels North the Earth underneath it rotates at less than 1000 km/hr due East.
Comment: @Farcher Yes, but so does *the plane*.  Everything rotates, not just the planet.  You maintain the same rotation velocity as the planet when you take off.  Why should the plane compensate?
Comment: @Farcher You think that if the planet didn't have an atmosphere and you jumped at the equator, you'd land several hundred meters away?
Comment: @Neil Where is the force that decreases the easterly speed of the plane as it moves further North so that the plane had the same lower rotational speed of the Earth?  With no atmosphere if you dropped an object from a tower it would reach the ground a small distance East of the tower due to this effect.
Comment: @Farcher If you were in space moving at 1000km/hour and you let go of a bowling ball, would that ball move away from you in the opposite direction that you're moving?  Absolutely not (at least not without a purposeful push).  Add gravity to the equation and it's just the same problem with an irrelevant force vector.  There's no invisible "friction" force being applied if it isn't attached to the rotating earth.  If planes compensate for anything, it's headwind.
Comment: Perhaps what I am trying to explain might be clearer.  if the plane started at the North Pole and set off due South.  The plane having started at the North Pole will not have a component of velocity at right angles to its motion due South.  If you look out of the window of the plane what do you "see".? You see the Earth rotating in a direction at right angles to the motion of the plane.  When the plane reaches the Equator it will arrive at a point which is West of the point which was originally due South of the plane when at the North Pole.
Comment: @Farcher Ah ok, I see what you meant.  Yes, that does make sense, actually.
Comment: @Neil I did not want to mention the fact before that this acceleration in a rotating frame (the Earth) is related to the Coriolis force.  https://en.m.wikipedia.org/wiki/Coriolis_force
Answer: The air, and the planes in the air, are rotating together with the Earth.
Everything is rotating!
Comment: I'm not sur eI understand how the air rotates with the earth? How is it connected to it? If I throw a ball through the air, it moves through the air and independently of it
Comment: Imagine that you're running with a ball in your hand and while running you throw it in the air and then catch again. In those few seconds, while out of your hands, it continues to move alongside you, right? Even though it's not connected to you. It has velocity, so it keeps moving. So it is with air. It has velocity, so it keeps moving. Why does it have (roughly) the same velocity as things on the ground and earth itself? Friction with things on earth (like your face or a mountain) causes low air to get to the same speed, and friction with low air speeds up higher air if necessary, and so on.
Comment: @tmccar think of it this way, if the air didn't move with the ground beneath it, standing at the equator you would experience winds 1667 km/h as you pass through the 'still' air. The air is moving relative to the ground.
Answer: The fact that the Earth is rotating means that it is rotating around its own axis relatively to the surrounding space. The Earth's atmosphere – even though not opaque like the rocky planet's surface itself – is just the outmost layer of the planet. It is not a nonchalant part of the outer space.
When the Earth orbits the Sun, it does not shed the atmosphere into the empty space all along the orbit, because the atmospheric layer belongs to the Earth.
Take Jupiter, a gas planet: There wouldn't really be any tangible surface to land onto. Basically all you can see from outside is gas, yet all of that moves along with the planet, as one unit.
A hypothetical but impossible example: If only the Earth rotated at 1667 km/h but the surrounding atmosphere*  didn't, the velocity is a relative one: While standing on the Earth's surface, you should basically be standing amidst a raging storm wind of 1667km/h, which isn't happening. Do not mix this hypothetical example with the weather system, which is an entirely different concept happening for other reasons.
*(which isn't a void vacuum, but a composition of gasses, therefore, matter which can interact with other matter. Colliding into gas molecules slowly doesn't feel like anything, but the bigger the velocity of collision, the more dramatic violence you can have mundane seeming particles cause: Still air can turn into house-tearing hurricanes when moving fast enough relatively to the houses.)
If you're traveling in a train and you jump, you land back where you were just like you hadn't even been in a moving train, because the air inside the train is traveling with it.
If the train has no walls, it isn't carrying a portion of still air, but is slashing relatively very fast through the surrounding air. If you jump up now, the passing air will hit you hard and you'll fly far backwards relative to the train's floor.
The Earth with its atmosphere is like the closed train that has walls.
Landing onto a rotating Earth seriously is a concern when astronauts return from space, because space is an airless zone and when you enter the Earth's atmosphere, the rotation of the planet suddenly starts to affect you. Similarly, when you launch a rocket to space, you can't just point it wherever you like, but you have to consider the Earth's rotating and orbiting factors. A bit like being in a moving train, opening the window and trying to throw a ball into a bucket that's sitting still next to the railway track.

But the train travels with a linear motion. So, as regarding the earth's rotational motion - if the train was shaped like a sphere (for example), and its motion was to rotate around its own centre (axis), would passengers not sense some sort of centrifugal force? – tmccar

Newton's laws of motion state that "When viewed in an inertial reference frame, an object either remains at rest of continues to move at a constant velocity, unless acted upon by a force". When you're in a fast carousel, you feel like you're being pushed outwards from its center. This feeling of pressure happens because according to classical mechanics, once set to motion into one direction, you'd really want to continue going that way in a straight line, but the supporting physical obstacles – the carousel's structure itself – blocks you from following that natural path, reflecting you back towards the carousel's center. You're getting a fight of two forces.
When you roll a ball at a straight wall in a diagonal angle, it will reflect back away in the identical but mirrored angle. You can observe that one reflection. Inside a circle, you'd want to just go straight out but your trajectory is being reflected back inwards at an extremely subtle angle at a time, and because the obstacle is curved, the moving object barely gets to travel on its newly reflected path at all when it already hits the circle wall again and is reflected time and time again, resulting to travel in what appears to be a circular path.
If you had a rotating sphere full of air, the air molecules near the edges would be more likely to occasionally collide with the wall, so there could be some turbulence there, but the air in the middle of the sphere would remain more untouched. If you were to have two spheres nested so that there's an outer shell sphere, and an inner smaller sphere which contains air – if the outer sphere rotates around its axis but the inner one that is in contact with the air inside doesn't, the inside remains fully intact and ambivalent of what's happening outside. If the space between the two sphere shells is a vacuum, there is no matter that could transfer the outer sphere's kinetic energy to the inner sphere.
When a normal shaped train with air inside is in motion, the inside walls themselves are not moving relative to the air inside, so no air bouncing occurs. However, if you're standing on a train platform where the air is standing still and suddenly a train passes by, its walls hit the air molecules, causing a blast of wind.
Comment: But the train travels with a linear motion. So, as regarding the earth's rotational motion - if the train was shaped like a sphere (for example), and its motion was to rotate around its own centre (axis), would passengers not sense some sort of centrifugal force?
Comment: @tmccar I updated my answer to address your new follow-up question. Comments don't allow that many characters.


Run one app on multiple elastic beanstalk instances

Question: I have one Flask app which handles a number of things which are common to a number of elastic beanstalk applications: logging, database/ORM, error handling, are all handled by Flask, and similar across elastic beanstalk instances.
I have four eb applications, which each do different jobs, demand different docker images, and so on.
One approach would be have each eb app target its own unique endpoint on the Flask App and follow its own unique code path, while sharing common resources, such as the ORM and error handling.
Is this possible?  The big limitation seems to be one Dockerfile per project, which has a fixed name, and sets the image.  I would rather be able to specify the Dockerfile-path at deploy-time.
Is this even a reasonable approach to take?
Answer: You've got three options:
Run multiple services in one container: Treat containers like VMs; run both your Flask app and your other services in one container. You could then have the Flask app built as a base container and build your other 4 applications off that base.
Run an internal service on another instance: Put the Flask app on a 5th EB machine, one that's internal-facing, and direct the other 4 to talk to it.
Don't use Elastic Beanstalk: Provision your own instance and run it the way you like.
Of these, I'd strongly consider the last. Once you find yourself trying to work around the limitations of EB, you've probably outgrown it.