Text message archive?

Question: Occasionally my ex and i will have texting conversations.  I would like to be able to save these digitally for my records.  Is there a way to save these conversations as a text file?  Right now I only know how to send myself an email with a singular text.  Not useful for a 50 text back and forth conversation about our kids.  I have an iphone 6
Comment: Do you, by any chance, have a Mac?
Comment: What device (e.g. iPhone) do you each use for texting.
Answer: Depending on what you need to use it for and if you have a Mac or PC, there are multiple solutions:
On a Mac: for example use http://www.ecamm.com/mac/phoneview/, can also Google for alternatives
On a PC: the PC counterpart is http://www.copytrans.net/download.php
Since you mention your ex and your son, you might need these for legal purposes (hope not for you!).
In this case screenshots might be your best bet, as your lawyer might want to see those if things get rough (still your iPhone will be the best resource, so don't delete them there):
Scroll to the top of the messages you need

If timestamps are of value, swipe in from right side of screen to
show them
Press the power button (top right of iPhone) and the Home button
at the same time for ~1.5 secs and release
Scroll down so the last sentence which you just screenshotted is
shown at the top (thus the order of messages can easily be deducted)
Repeat steps 2 and 3 as often as needed

Good luck!

Text message archive?


Can I cancel a transaction?

Question: I sent a transfer but the transaction is still in the transaction pool. Can I cancel it?
Comment: the transaction will be flushed from the mempool after roughly 3 days. you can rebroadcast the transaction again after
Answer: No, not really. If you didn't include a big enough fee or something it will fall out of the mempool after a day or so, but there's no way to ask all the nodes that have your TX in their mempool to kindly forget about it, afaik.
Answer: Edit: Not working from at least v0.15.0.4. I am getting the following error:
"Couldnt send the money: transaction  was rejected by daemon with status: . Reason: double spend".

tl;dr: Reset wallet to make coins spendable again.
Quickest way to free up coins again, is just deleting the wallet .keys file. Then it will force resync, and then the coins are spendable again.
Though you will have two transactions in the mempool, the new transaction will make the older one unusable, once the new one is in a block.
Comment: This is very poor advice to recommend deleting a wallets keys. Depending on the source of the issue, the local tx pool can be flushed and/or the wallet can be made to rescan.

Can I cancel a transaction?


Einstein Bot Rules not Executing

Question: I have created a simple chat bot.  I am asking if the customer wants to continue.  I have created a new variable called Yes_No of type Boolean to store the answer from the question.  I have then created a rule to check the answer.  If answer No, but the dialog continues to the next set and not direct to the other dialog as expected.
Any thoughts will be most appreciated
I have provided screen shots below
Clear down the variables before starting

Ask the question and save the answer to the boolean variable Yes No

Show result for debugging purposes.  And the rule. If False then go to another dialog

Result on the chat bot.  Show that it is continuing and not going to the other dialog
Answer: Resolved, I was using Call Dialog not Redirect to Dialog, doh

Einstein Bot Rules not Executing


Area enclosed by 2-dimensional random curve

Question: Consider a 2-dimensional Wiener process $(W_t)_{t \in [0,1]}$. Color every area which is enclosed by the line parametrised by $W_t$ (this means that, when the Wiener process  makes a loop and intersects itself you color the points of the plane inside the loop). What is the expectation value of the area colored in that way?
Comment: Have you considered running a simulation of this to observe the empirical result?
Answer: @Danra suggested running a simulation - so that's what I did.

Simulation of the Brownian motion: Since a 2-dimensional Brownian motions consists of two independent 1-dimensional Brownian motions, it suffices to simulate paths of a 1-dim. Brownian motion. To this end, I implemented the following algorithm (in R):

(Lévy-Ciesielski) Let $J \geq 1$ the order of refinement. Initialize $b_0 := 0$. Generate $b_1 \stackrel{s}{\sim} N(0,1)$.
  $\quad$ For $j=0$ to $J-1$:
  $\quad \quad$For $\ell=0$ to $2^j-1:$
  $\quad \quad \quad$ Generate $y \stackrel{s}{\sim} N(0,1)$. Set $$b_{(2\ell+1)/2^{j+1}} = \frac{1}{2} (b_{\ell/2^j} + b_{(\ell+1)/2^j})+2^{- \left( \frac{j}{2}+1 \right)} \cdot y$$

(René L. Schilling/Lothar Partzsch: Brownian Motion - An Introduction to Stochastic Processes, p. 320)
Calculation of the enclosed area: First, I calculated the selfintersection-points of the given path. From this, we can determine polygons enclosed by the curve and approximately calculate the area of these polygons. (I did this part in Matlab, the tools "Fast and Robust Curve Intersections" and "Fast points-in-polygon test" were quite helpful.)

Here are some examples:
The area colored in red is the area detected as enclosed by the curve.
Altogether, I did 2000 simulations and obtained the following histogram and empirical cumulative distribution function:

Somehow, it looks a bit like an exponential distribution, but it doesn't fit properly. The average of the enclosed area is equal to $$0,0026$$
Comment: How many subdivisions are there in $2^{nd}$ graph? Is there a drift term in your random walk? The upper left corner of the $2^{nd}$ curve looks a little bit too straight for a zero drift Brownian motion...
Comment: @achillehui I took $J=10$, i.e. there are $2^{10}$ subdivisions (for all simulations). There isn't a drift term. It would look "less straight" if one would choose a larger $J$. Perhaps, I could try this. (I had used the inpolygon-test implemented in Matlab (and this one is really slow if the polygons have a lot of vertices) before I found the faster implementation I mentioned above.)
Answer: The probability that a point $x$ is enclosed by the Brownian path starting at $0$ at time $1$ depends only on the distance between $x$ and $0$. Call this probability $p(\|x\|)$, then the expected area $A$ enclosed by the Brownian path is $2\pi$ times the integral of $r\mapsto rp(r)$.
The Brownian path starting at distance $r$ from the origin and running during a time interval of length $1$ is the scaled version of the Brownian path starting at distance $1$ from the origin and running during a time interval of length $1/r^2$ hence $p(r)=\mathbb P(T\leqslant1/r^2)$, where $T$ denotes the first time the Brownian path starting from $1$ encloses the origin. Thus,
$$
A=2\pi\int_0^{+\infty}\mathbb P(T\leqslant1/r^2)r\mathrm dr=\pi\cdot\mathbb E\left(\frac1T\right).
$$
A skew-product representation of the planar Brownian motion indicates that the process of its angular component may be represented as $(B(U_t))_t$ where $(B(t))_t$ is a standard (linear) Brownian motion starting at $0$ and $U_t=\inf\{u\mid\int\limits_0^u\mathrm e^{2\beta}\geqslant t\}$ where $\beta$ is another (linear) Brownian motion starting from $0$ and independent of $B$.
Thus, that $T\leqslant t$ implies that $|B|$ reaches $2\pi$ before time $U_t$, that is, that $\int\limits_0^\tau\mathrm e^{2\beta}\leqslant t$ where $\tau$ is the first hitting time of $2\pi$ by $|B|$.
In other words, $T\geqslant\int\limits_0^\tau\mathrm e^{2\beta}$ where $\tau$ is independent of $\beta$ and the distribution of $\tau$ is known. These observations might allow to deduce an upper bound of the value of $A$.
Comment: $T \le t$ is not equivalent to |B| reaching $2*\pi$ before time $U_t$ because the latter doesn't imply that the Brownian motion is self-intersecting. Consider for example a Brownian motion in the form of a spiral which winds several times around the origin without intersecting itself, thus enclosing no area.
Comment: @Dominik Indeed. Post modified. Sorry about this (stupid) mistake and thanks for the correction.


Installing GRUB on a VirtualBox guest - does it affect the host MBR?

Question: I am in the process of installing the latest debian stable on VirtualBox (3.1.4), and got to an installation step asking to installing GRUB to the MBR of the disk.  I assume that since this is a "virtual" disk created by VirtualBox, that the MBR for it is isolated from the MBR of the primary disk on the host.  Is this correct?  I had previously been under the (possibly incorrect?) impression that there was 1 MBR per physical primary disk.
Answer: Quoted from http://www.virtualbox.org/manual/ch05.html#vdidetails

Disk image files reside on the host
  system and are seen by the guest
  systems as hard disks of a certain
  geometry. When a guest operating
  system reads from or writes to a hard
  disk, VirtualBox redirects the request
  to the image file.

So it does not affect the host MBR. Only the disk image file.
Answer: uhm I think that you can't make changes because you're in a virtual space on your computer, so it can't affect the HDD/SSD, because it's in a closed environment in your laptop.
Comment: You can map the raw HDD into the VM and overwrite it.


What is the core differences between constraints like PK vs Indexes

Question: What is the core differences between a table that is created with constraints like PK vs a table created or added indexes created on it only (that don't have PK) when it comes which route would anyone prefer to implement when creating a table? I have work on them but I am just curious to know what separate them Thank you
Answer: They are quite different.
Constraints check the data that is being inserted and updated meet some criteria (for example "not null"). If the data does not meet the criteria, the INSERT or UPDATE is rejected, and fails. Constraints help you to maintain the quality of the data.
Indexes improve (most of the time) the speed of a query, and are usually beneficial to SELECT, UPDATE, and DELETE operations. Indexes improve database performance.
Comment: Thank you for your clarifications helped a lot.
Answer: An index has no effect on how a query behaves nor the schema definition. It only effects performance. Although some SQL servers implement features using indexes, particularly the unique constraint. The SQL standard doesn't even mention them because they're considered an implementation issue.
A primary key constraint very much does have an effect on behavior and schema definition. It says this column must be unique and not null. Most databases also happen to index it for obvious performance reasons.
Declaring primary key rather than manually saying unique not null also lets the person reading your schema know that this is the primary key. They will know what its purpose it. It also lets the database know this is the primary key which might allow it to do some extra optimizations.
Comment: "...The SQL standard doesn't even mention them [indexes] because they're considered an implementation issue..." -- That is so true, and I forgot to mention it. Upvoting.
Comment: Thank you for your clarifications helped a lot
Comment: @TheImpaler I was very surprised, and a little indignant, when I found out myself.


Will Leaving a tenure track position after one year for a postdoctoral position at a better location hurt my future academic career?

Question: I'm leaving a tenure track position after one year, I have a tenure track offer and a postdoctoral offer. The postdoc position is in the very nice city and I like the research projects there. But the school is not that high ranked. Will going down to postdocs hurt my future transition to faculty position?
Comment: I do not think this is answerable because so few people have done that.  Scrutinize your personal preferences.
Comment: I know of a case who went from a TT in a small, unknown place to a postdoc in a very famous one to boost their career. No idea if it worked, I didn't follow it.
Answer: Not necessarily. BUT, is it worth the risk?
Whether a post doc now will help or hurt depends on many things, such as, even, why you are leaving a TT position now and what your trajectory is. A perfect in every way post doc might help, but I'd think that anything less is leaving you on a treadmill without a sure path to progress. And you don't describe this offer as perfect. And, the "very nice city" aspect doesn't contribute to your career and is temporary in any case.
The goal is to get a permanent faculty position. You have an offer of a TT position which puts you closer to the goal. If it is in a place where you would be happy starting your career then take the TT offer.
Comment: Living in a nice city may not directly help your career, but if you hate where you live and are miserable for it, that's not a great career boost either. Plus, there's more to life than work.


How are views counted?

Question: When I see that a question has, say, 100 views, how should I understand it? Is it the number of distinct users that viewed the question or the number of distinct views regardless of the viewers? Are my views counted?
Comment: Oh, as usual, I have read your question wrongly! So, I am deleting my comment!
Answer: Here's a question on MSO that explains how views are counted:
How does Stack Overflow calculate the number of views in a question?
While there are no SE employees on the thread, Jeff Atwood has closed some questions as dupes of that one (e.g.), so presumably it is not too far off from the truth.

How are views counted?


Visa category for attending workshop (Turkish Visa)

Question: I am currently a student in India and I am planning to attend workshop in Turkey for nearly 14 days. I have received acceptance letter from the organizing place. I am confused which Visa category should I apply. Is it Student Visa or any other type which fits my situation?
Comment: Could you please add information on the workshop, what it's for, and the name of the organizer? That will help to tell whether participants are eligible for a student, or other, visa.
Answer: The Republic of Turkey Ministry of Foreign Affairs (MFA) outlines two categories which match with your plans, Tourist and Student.
Among the activities permitted on a Tourist visa are conference, seminar, meeting; a two-week workshop fits within that category. The Student-Education visa has a more rigorous process, such as a letter of enrollment from the relevant higher education institution, proof of funds for a living in Turkey (bank account, scholarship document), etc.
Another key difference: an e-visa is available for tourists, students requires consular application and interview. Absent additional information from you, whether the two-week workshop is organized by a university of which you are a student or intern, it is more likely that you would want a Tourist visa.
Again, the MFA describes what to do:

Visa Information For Foreigners
• The Electronic Visa (e-Visa) Application System was launched on 17 April 2013 by the Ministry of Foreign Affairs of the Republic of Turkey. This system allows visitors travelling to Turkey to easily obtain their e-Visas online (www.evisa.gov.tr), in approximately three minutes.
Applicants just need to log on to www.evisa.gov.tr, provide the requested information, (after the application is approved) make online payment and download their e-Visa.
• Please note that e-visa is only valid when the purpose of travel is tourism or commerce. Other purposes, such as work and study, require regular visa given by Embassies or Consulates.


How to disable Microsoft Authenticator notification

Question: I keep on getting ads in the Windows 10 Notification Center to sign up for Microsoft Authenticator. I keep on suppressing the ads but they keep on coming back. Is there a way to permanently disable these ads?
Comment: I suspect if you disable `Get tips, tricks, and suggestions as you use Windows` within `Notifications & actions`.  If that works for you I will submit an answer, I have it enabled, but I never get that suggestion so I am not entirely sure that will prevent the notification.  I also don't know if you are actually getting a notification or not.
Answer: Here's what worked for me, though it does turn off a little more than just that notification.
After getting the notification, don't click on the cross or remove it.

Open the notification drawer
You should see the suggestion under a title of "Suggestions"
Right click on the title "Suggestions" and select "Turn off notifications for Suggestions"
Answer: The Microsoft Authenticator prompt is maybe coming up because you turned on
Two-step verification.
Try this from the article
Turning two-step verification on or off for your Microsoft account :

Go to Security settings and sign in
  with your Microsoft account.
Under the Two-step verification section choose ... Turn off two-step verification to turn it off.
Follow the instructions.
Comment: I'm logged in using a Local Account (not a linked to a Microsoft Account) so I don't think this applies in my case. Further, I checked my Microsoft Account and it seems to have two-step verification disabled.
Comment: Can you add to your post a screenshot of this message?
Comment: I will, the next time it comes up.
Comment: Like @Gili I'm also using a Local Account with 2-step off and get the Authenticator notifications.
Answer: You should go to PC Settings -> System -> Notifications & actions. "Suggested" switch can found at the bottom. Here you'll find all applications that have the ability to pop-up notifications and the switches to turn the authorization on or off.
Answer: I use the registry to disable notifications, the specific steps are as follows:

Press the WINDOWS+R key on the desktop, and then open the Run menu window and enter "regedit" to open Registry Editor.

After entering Windows Registry Editor, we navigate to the HKEY_CURRENT_USER\Software\Policies\Microsoft\Windows project, double-click on the item on the left and open them.

After we find the last Windows subkey, we right-click the subkey and select the New->key menu.

In the pop-up menu, name the item "Explorer", then right-click on the new Explorer item, select New-Dword (32-bit), and then type "DisableNotificationCenter" in the Open page.

Double-click to establish the DisableNotificationCenter subkey item, open it and set the value data to "1", and then click the OK button.

Save the change settings for the registry, and then right-click in the taskbar on the desktop and select Open Task Manager. Locate the Windows Explorer in Task Manager, and then Restart the Explorer program.

Tip: If you want to restore the list of WIN10 notification bar programs, you only need to delete the Explorer items in the HKEY_CURRENT_USER\Software\Policies\Microsoft\Windows directory in the registry. Then restart the Windows Explorer.
Comment: I don't want to disable all notifications, just this specific one.
Comment: Anyway this trick doesn't disable the Authenticator notification, it just disables the notification center icon on the system tray, so this is a useless solution.


Searching multiple custom post types and pages

Question: I'm using bainternet's method for searching custom post_types and it works great. However, I've recently been requested to return more than one "specific" post type and perhaps individual pages for a support section on our site.
I thought adding additional hidden fields would do it, but that didn't work. And I have no clue how this will work with pages.
Any help would be appreciated!

In the template:
<form action="http://apollo.website.net/" id="searchform" method="get" role="search">

Search for:
    <input type="text" id="s" name="s" value="">
    <input type="submit" value="Search" id="searchsubmit">

    <input type="hidden" name="post_type" value="software" />

</form>

In functions.php:
/* Custom Search Queries */
function SearchFilter($query) {
$post_type = $_GET['post_type'];
if (!$post_type) {
    $post_type = 'any';
}
if ($query->is_search) {
    $query->set('post_type', $post_type);
};
return $query;
}

Answer: change
<input type="hidden" name="post_type" value="software" />

to
<input type="hidden" name="post_type[]" value="software" />
<input type="hidden" name="post_type[]" value="books" />

i have to run but this should work , just add as many hidden fields as you need for each post type
Comment: Works great, thanks! Is there a way to get it to return related pages as well?
Comment: Arrayed input values won't work with the `GET` method, i'd be surprised if that code is actually doing what you think it is..
Comment: My mistake, it works when used alongside the filter from the user's previous question, disregard above comment.
Answer: You could do it like this to switch between a singular set type and any..
<input type="hidden" name="post_type" value="software" />
Search all
<input type="checkbox" name="post_type" value="any" />

Unchecked searches your specific type, checked sets the post type to any..
Comment: This is just an additional tip to compliment Bainternet's answer. ;)
Answer: To me works that solution (same as Bainternet's, but without "[]" after "post_type"):
  <input type="hidden" name="post_type" value="photo">
  <input type="hidden" name="post_type" value="video">

And to get a specific template for search results based on the post type(s) (on functions.php):
function search_template_chooser($template) {
  global $wp_query;
  $post_type = get_query_var('post_type');
  if( $wp_query->is_search && $post_type == 'photo' || $wp_query->is_search && $post_type == 'video' ) {
    return locate_template('search-media.php');
  }
  return $template;
}

add_filter('template_include', 'search_template_chooser');


Add keys to ssh-agent

Question: I have three SSH key pairs that I want to have added to the SSH agent every time I start a shell. After restarting I always have to manually add them again by using ssh-add <path_to_private_key>.
How can I do this?
Answer: It depends.
If you log in through SSH, you can use SSH agent forwarding, by way of the -A option to ssh (alternatively, you can set an option in your ~/.ssh/config). Doing this will allow you to copy SSH keys from the server to your locally-running ssh-agent.
If you log in through an X session, you should have a single, central ssh-agent running, set up by your distribution. If not, make sure your ~/.xsession (or whatever you use to start your X session) contains something like this:
ssh-agent awesome

(on the assumption that you're like me and love the awesome window manager).
If all else fails, you could use your ~/.bash_profile. In there, add something along the following lines (near the top of that file):
if [ -z "$SSH_AGENT_PID" ]
then
    exec ssh-agent bash
fi
ssh-add ...

this checks if you've already got an agent running; if not, it starts one anew, which then starts a shell. If you do, it adds your keys to it.
(There is another option where you run eval ssh-agent without passing it a command to run. Don't do this; it is less secure)
Answer: After starting the agent save the commands to set the SSH_AUTH_SOCK and SSH_AGENT_PID to a file.  Then execute these commands instead of starting the agent again.  This will leave you with one shared agent for all your shells.  Building this functionality in your .profile or .bash_profile file will make this easier.
If you are working in an X-Windows environment, you could just start the agent as part of the X-Windows initialization.  Your shells should then inherit the existing agent settings.
When using this solution, I add the keys with a relatively short timeout.  The default can be set when starting ssh-agent by using the -t option.
Comment: having a shared agent for shells who don't share a parent is a bad idea, and there's a simpler solution.
Comment: @WouterVerhelst As it is trivial to steal access to an ssh-agent running as the same user on the same server, I don't see any additional risk.

Add keys to ssh-agent


What does "perfect love casts out fear mean?

Question: First timer here, seems like a great community and glad to be here.  I was hoping to get different ways to explain this scripture in 1John 4:18.  Thank you!
H
Comment: Welcome to BH. If you are looking for different interpretations of the text or for the ways in which various organisations view the text, the other site, SE-Christianity, would be more appropriate. Here, it is the hermeneutical analysis of the actual wording that is the focus.
Comment: Hello, Hector.  Found a similar question asked on Bible Hermeneutics (in 2012) which may help you: https://hermeneutics.stackexchange.com/questions/1676/perfect-love-in-1-john?rq=1
Answer:
NWT 1 John 4:18  "there is no fear in love, but perfect love casts fear out, because fear restrains us. Indeed, the one who is fearful has not been made perfect in love."

When one has true love for Jehovah God we have no fear of persecution or to preach, refuse to go to war, refuse to deny our faith etc. etc., even if we my die for doing so, it would be the greatest honor to die for doing what God wants to be done, just like Jesus did:-

NWT 1 Peter 2:19, 20  "For it is agreeable when someone endures hardship and suffers unjustly because of conscience toward God. 20 For what merit is there if you are beaten for sinning and you endure it? But if you endure suffering because of doing good, this is an agreeable thing to God."
Answer: Peace,
Love is made "perfect"….that is, made complete….when we have love for one another.
We show forth that we know and love God when we keep His commandments.  We are to have love for one another no matter what…even love for our enemies. This shows that we love God by the keeping of His commandment to have love for one another.
Our love is especially made complete when the Son of God comes to give us an understanding so that we may show forth that we know Him who is true by having love for another.
He sends out His servants….fellow brothers…to speak His words of knowledge.  They are words of spirit and life as the Lord opens up the Scriptures to our hearing ears (hear what the Spirit says to the churches) and were to be found of Him doing His commandment to have love for another....even when we do not particularly agree with what a brother has to say.

1 John 5:20 KJV (20)  And we know that the Son of God is come, and
  hath given us an understanding, that we may know him that is true, and
  we are in him that is true, even in his Son Jesus Christ. This is the
  true God, and eternal life.

The "Day of Judgment" comes when a "stranger" (a brother) comes along speaking the Lord's words to our hearing ears.  His words will not conform to the various private interpretations of men who currently wrest the Scriptures to their own destruction.
We don't know the day nor hour when someone comes along to speak His words to our ears….so we must be "awake"…be ready….at all times to do good toward all people…even "strangers" who come speaking things that we have never heard before and may sound "strange" as compared to what they have always heard being preached.
The Son of man comes along on a day nor hour we are expecting as we shall hear His voice from Heaven speaking through those whom He will send out….and so we are to always stay "awake" to His righteousness by letting brotherly love continue and not be forgetful to "entertain strangers" and their words.

Hebrews 13:1-2 KJV (1)  Let brotherly love continue. (2)  Be not
  forgetful to entertain strangers: for thereby some have entertained
  angels unawares.

Do it faithfully to the brothers….and to "strangers"...by having love for them.  Diotrephes was not found letting brotherly love continue as he rejected the brothers and prevented others from receiving them.
3 John 1:5 KJV
(5)  Beloved, thou doest faithfully whatsoever thou doest to the brethren, and to strangers;
Strive not with a man without cause….if he has done you no harm.  Those who are found "asleep" will not remember to have brotherly love and will contend in wrath towards those whom the Lord will send out and are in danger of the Judgment.    They will strive  with them about with the meaning of words and will call them "fools" for what they preach.  We must remember to have brotherly love…always....even when we may not agree with them. Let your "yes" be "yes" and your "no" be "no" towards what one may hear.  Everything else (such as calling them a "fool"..."raca"....unintelligent) is evil.

Proverbs 3:30 KJV (30)  Strive not with a man without cause, if he
  have done thee no harm.

We are to remember to always have brotherly love….even towards a "stranger" who comes along to speak His words.  That is how we show forth that we know and love God.  Our love is made complete by doing so.  By doing it, we will have boldness in the Day of Judgment at the hearing of His voice that opens up the Scriptures (the "books" are opened up).  Perfect love casts out fear.

1 John 4:17-18 KJV (17)  Herein is our love made perfect, that we may
  have boldness in the day of judgment: because as he is, so are we in
  this world.

Fear has "torment"…punishment…in the Day of Judgment.

(18)  There is no fear in love; but perfect love casteth out fear:
  because fear hath torment. He that feareth is not made perfect in
  love.

Those who are found "asleep" …..being forgetful to letting brotherly love continue…. are to be warned to "awake" to His righteousness and cast off the works of darkness (the wrath, the envy, the strife, the slandering, the contentions, etc) and put on Christ….especially in the Day we hear His voice from Heaven speaking to us via the Spirit through those sent out by Him to speak His words.   Those who will hate that brother sent out by Him are still in "darkness" and still abides in death. They will have fear in their awaiting for His judgment upon them.

Romans 13:10-14 KJV (10)  Love worketh no ill to his neighbour:
  therefore love is the fulfilling of the law. (11)  And that, knowing
  the time, that now it is high time to awake out of sleep: for now is
  our salvation nearer than when we believed. (12)  The night is far
  spent, the day is at hand: let us therefore cast off the works of
  darkness, and let us put on the armour of light. (13)  Let us walk
  honestly, as in the day; not in rioting and drunkenness, not in
  chambering and wantonness, not in strife and envying. (14)  But put ye
  on the Lord Jesus Christ, and make not provision for the flesh, to
  fulfil the lusts thereof.

If we continue to sin willfully after we have received the full knowledge (epignosis) of the Truth, there remains no more sacrifice for sins and those who do such things will have a certain "fearful" looking for of Judgment and fiery indignation which shall devour the adversaries.
There will be no way out of the Judgment as there will be no more sacrifice of the Lord available for their willful sins after having been warned (warned 3 times….for 3 sins and for 4). They will have fear as they await His impending Judgment upon them.

Hebrews 10:  (26)  For if we sin wilfully after that we have received
  the knowledge of the truth, there remaineth no more sacrifice for
  sins, (27)  But a certain fearful looking for of judgment and fiery
  indignation, which shall devour the adversaries. (28)  He that
  despised Moses' law died without mercy under two or three witnesses:

They will have rejected what they hear (the Word of Truth) as spoken by those brothers sent out by Him in the Spirit of grace. Because of God's love for us and His grace,  the Son of God comes to give us an understanding (by the opening up of the Scriptures to our minds) and they (those who contend with it) were thought worthy to hear it.
They are found being contentious in their evil words and will trodden the Son of God under their "foot" (with their evil speaking tongues of what they hear) and count the blood of the covenant…..the brotherly love covenant….as "unholy"  thing (a common thing easy to break in their own thoughts and ways).

(29)  Of how much sorer punishment, suppose ye, shall he be thought
  worthy, who hath trodden under foot the Son of God, and hath counted
  the blood of the covenant, wherewith he was sanctified, an unholy
  thing, and hath done despite unto the Spirit of grace? (30)  For we
  know him that hath said, Vengeance belongeth unto me, I will
  recompense, saith the Lord. And again, The Lord shall judge his
  people.

It is a fearful thing to fall in the hands of the living God.  Fear will grip those who will not show love for their brothers....after having been warned to do the holy covenant to have brotherly love.

(31)  It is a fearful thing to fall into the hands of the living God.

But those who will be found practicing the holy covenant of brotherly love are made complete in His love.

1 John 4:12 KJV (12)  No man hath seen God at any time. If we love one
  another, God dwelleth in us, and his love is perfected in us.

There will be no more sacrifice for those who continue to sin willfully (for 3 transgressions and for 4, His punishment will not be turned away) as they forget to do the brotherly covenant (letting brotherly love continue).
These are those who will harden their hearts  ("Tyrus" = "rock" = a hardened heart) in the hearing of His voice and will not practice the holy covenant of having brotherly love (as Jesus loved us and died for us, we are to have love for each other) after having been reminded 3 times to do so.

Amos 1:9-10 KJV (9)  Thus saith the LORD; For three transgressions of
  Tyrus, and for four, I will not turn away the punishment thereof;
  because they delivered up the whole captivity to Edom, and remembered
  not the brotherly covenant:

They will have a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries.

(10)  But I will send a fire on the wall of Tyrus, which shall devour
  the palaces thereof.

"Tyrus" (meaning "rock) signifies those who will hear His voice and be found hardening (Tyrus) their hearts through the deceitfulness of sin (their evil speaking).

Hebrews 3:12-15 KJV (12)  Take heed, brethren, lest there be in any of
  you an evil heart of unbelief, in departing from the living God. (13)
  But exhort one another daily, while it is called To day; lest any of
  you be hardened through the deceitfulness of sin. (14)  For we are
  made partakers of Christ, if we hold the beginning of our confidence
  stedfast unto the end; (15)  While it is said, To day if ye will hear
  his voice, harden not your hearts, as in the provocation.

For 3 transgressions of Edom (those who are "red" in their wrath towards what they hear) and for 4, His Judgment will not be turned away (as there will be no more sacrifice for their continued willful sins).
These are people who will not remember to let brotherly love continue and will instead continue to pursue their "brother" in their wrath (Edom = red =wrath) with the "sword"….that is, the tongue that will speak angry, slanderous evil words against a brother sent out by the Lord to speak His words of life and spirit to their hearing ears.

Amos 1:11-12 KJV (11)  Thus saith the LORD; For three transgressions
  of Edom, and for four, I will not turn away the punishment thereof;
  because he did pursue his brother with the sword, and did cast off all
  pity, and his anger did tear perpetually, and he kept his wrath for
  ever: (12)  But I will send a fire upon Teman, which shall devour the
  palaces of Bozrah.

We must be found abiding in Him so that we may have confidence before Him when He comes to speak His words in the Spirit of Truth. Everyone found doing righteousness before Him is born of Him.  The children of the devil manifest themselves by not remembering to do His righteousness.

1 John 2:28-29 KJV (28)  And now, little children, abide in him; that,
  when he shall appear, we may have confidence, and not be ashamed
  before him at his coming. (29)  If ye know that he is righteous, ye
  know that every one that doeth righteousness is born of him.

For those who will be found still "sleeping" even after having been warned (for 3 transgressions and for 4), sudden fear shall grip them as it is a fearful thing to fall into the hands of the living God in the Judgment.
Instead of giving His Spirit rest within them when they hear His voice in the Spirit of Truth (the revealed Word of Truth), they are found contending with evil, wrathful words instead of having a "poor and contrite" spirit….breath.

Isaiah 66:1-6 KJV (1)  Thus saith the LORD, The heaven is my throne,
  and the earth is my footstool: where is the house that ye build unto
  me? and where is the place of my rest? (2)  For all those things hath
  mine hand made, and all those things have been, saith the LORD: but to
  this man will I look, even to him that is poor and of a contrite
  spirit, and trembleth at my word.

They "kill an ox"…a brother sent out to speak His words to their ears.  Those who kill an ox is as those who slew a man….as the haters are murderers.  There will be no more sacrifice (of the Lamb) for those who continue to do such things…in their continued willful sinning as they delight in the "killing "of the messenger of His Word of Truth.

(3)  He that killeth an ox is as if he slew a man; he that sacrificeth
  a lamb, as if he cut off a dog's neck; he that offereth an oblation,
  as if he offered swine's blood; he that burneth incense, as if he
  blessed an idol. Yea, they have chosen their own ways, and their soul
  delighteth in their abominations.

He will bring fears upon them as they did not answer when He did call them and did not hear when He spoke His revealed Word to their hearing ears.  Instead, they will choose to do evil before His eyes and choose that in which He does not delight.

(4)  I also will choose their delusions, and will bring their fears
  upon them; because when I called, none did answer; when I spake, they
  did not hear: but they did evil before mine eyes, and chose that in
  which I delighted not. (5)  Hear the word of the LORD, ye that tremble
  at his word; Your brethren that hated you, that cast you out for my
  name's sake, said, Let the LORD be glorified: but he shall appear to
  your joy, and they shall be ashamed. (6)  A voice of noise from the
  city, a voice from the temple, a voice of the LORD that rendereth
  recompence to his enemies.

In the same way, voice of the LORD God walks in the garden in the "cool" (that is, Spirit) of the Day of Judgment. Out of fear, Adam and his wife did hide themselves.  Their love was not found complete.  They had sown fig leaves....words...together to cover themselves.  As we know, saying "Lord, Lord" will not cover us when we do not bring forth fruits of righteousness. Leaves are not enough as we must bring forth fruits of His righteousness at the hearing of His voice.

Genesis 3:8-11 KJV (8)  And they heard the voice of the LORD God
  walking in the garden in the cool of the day: and Adam and his wife
  hid themselves from the presence of the LORD God amongst the trees of
  the garden.

Faith alone is not enough as we must show forth that we know and love God by bringing forth good fruit towards the hearing of His voice.  Where is the faith? Where are the good works (the fruit) that are evidence of our faith? Saying "Lord, Lord" (the fig leaves of words only) will not save us but the doing of His will (bearing fruit).

(9)  And the LORD God called unto Adam, and said unto him, Where art
  thou? (10)  And he said, I heard thy voice in the garden, and I was
  afraid, because I was naked; and I hid myself. (11)  And he said, Who
  told thee that thou wast naked? Hast thou eaten of the tree, whereof I
  commanded thee that thou shouldest not eat?

It is impossible for those who were once enlightened and have tasted of the heavenly gift and were made partakers of the Holy Spirit and have tasted the good word of God (as we hear His voice speaking His Word of Truth to our ears) and the powers of the age to come, if they should fall away in their unbelief of what they hear, to renew them again unto repentance seeing they crucify themselves the Son of God (who comes to give them an understanding as He opens up the Scriptures to their hearing ears) afresh.

Hebrews 6:4-12 KJV (4)  For it is impossible for those who were once
  enlightened, and have tasted of the heavenly gift, and were made
  partakers of the Holy Ghost, (5)  And have tasted the good word of
  God, and the powers of the world to come, (6)  If they shall fall
  away, to renew them again unto repentance; seeing they crucify to
  themselves the Son of God afresh, and put him to an open shame.

Instead of drinking in His revealed Word into their hearts (the earth) and bringing forth fruits of righteousness towards those sent out by Him to speak His revealed Word, they are found rejecting it with their evil words as they "kill the messenger" of His words of life and spirit. They put the messengers to an open shame by publicly berating them.
*> (7)  For the earth which drinketh in the rain that cometh oft upon it,

and bringeth forth herbs meet for them by whom it is dressed,
  receiveth blessing from God: (8)  But that which beareth thorns and
  briers is rejected, and is nigh unto cursing; whose end is to be
  burned. (9)  But, beloved, we are persuaded better things of you, and
  things that accompany salvation, though we thus speak. (10)  For God
  is not unrighteous to forget your work and labour of love, which ye
  have shewed toward his name, in that ye have ministered to the saints,
  and do minister. (11)  And we desire that every one of you do shew the
  same diligence to the full assurance of hope unto the end: (12)  That
  ye be not slothful, but followers of them who through faith and
  patience inherit the promises*

Thanks for reading this long post.


is it worth to implement a firewall on a web server you control?

Question: I see the main reasons for a firewall on a web server to be defense in depth and extra cushion for a possible admin error of running an unnecessary daemon. I'm trying to see if I am overlooking something. I am thinking that in a situation where you have a small infrastructure (a few servers) that you control it's not feasible to deploy a firewall.
Answer: As you've implied, security is about layers.  Systems get attacked and they get breached in a myriad of ways.  By layering our security solutions, we prevent our systems from being subject to a single point of security failure.  Sometimes people put firewall devices off-box and sometimes they also put them on-box.  Sometimes they do both for just the reason you state: to protect against configuration errors -- a very real, well-defined, and exploitable human condition.
However, from reading your question, it almost sounds like you do not have the infrastructure to support a firewall off-box.  So if it comes down to NOT having a firewall and having a firewall -- albeit on your web server -- then put the firewall on your server. The firewall prevents more than just connections to other services. It can prevent certain types of flooding attacks, it can prevent odd and malicious packets from entering the system, it can protect against operating system weaknesses, it can protect against mapping your network and it can protect against data being exfiltrated from your system.
Answer: In addition to logicalscope's excellent answer, it's worth bearing in mind that in most cases, a firewall implemented in the OS introduces significantly less latency than one on a separate device. OTOH, OS firewalls vary in the amount of the system they expose before filtering is applied.

in a situation where you have a small infrastructure (a few servers) that you control it's not feasible to deploy a firewall.

That's not a good reason for not having a seperate firewall. Even the most basic of routers currently available provide some firewall functionality. And since you're going to need some sort of routing (i.e. you've got a latency overhead anyway) it's downright reckless not to apply both ingress and egress filtering.
Answer: It isn't just the risk of an admin issue, having a firewall on a separate device reduces your risk of attack:

A device which just runs as a firewall has a much smaller attack surface than a web server, which will have a large number of services running.
A firewall device will, in most cases, have considerably lower latency than one implemented on a server which is also running other things

However, the main attacks you are going to see will not target the firewall anyway, but will be aimed at the web server, so a normal firewall will just let that traffic on port 80 or 443 through, so in a small, cost-constrained environment if you can at least add some filtering or an access control list on your router and then have a firewall running on your server you are at least reducing yours risks in a cost effective way.
Comment: Maybe this should be a separate question, but how would your firewall setup be different in a cloud environment? Unless you're a big client, I don't think they'll give you a rounter. I'm guessing you'd implement the firewall on your loadbalancing machine.
Comment: @m33lky - Often a cloud provider will let you use a virtual firewall machine, or if not, you should be able to define an ACL for the router which provides your connection. You can virtualise every part of your environment if necessary. Loadbalancers are generally a bad place to install firewalls - they have a high enough load anyway.


Is there any way to get a key I no longer have access to deleted from the keyserver?

Question: The file was overwritten when I reformatted my hard drive. There are now 2 keys under my name registered on the site. I can prove I had access to the key, but I need to know where to ask for removal, or even if it's possible.
Answer: There is no way to delete keys from key servers. You could revoke it with a revocation certificate created in advance or access to the private key (to create such one), but never delete a key.
Well, theoretically you could, but you'd have to convince each single administrator of one of the hundreds of OpenPGP key servers to do so, and if somebody uploads it again it will reappear and redistribute. Most of these administrators will refuse anyway.

To prevent loosing access to your key, do following:

Regularly backup your computer (important anyway).
Create an offline copy of your private keys.
Create a revocation certificate immediately after creating a primary key. Store it both in a digital way and print it on a piece of paper (I recommend something like gpg --gen-revoke | qrencode to be able to scan the certificate without the hassles of OCR).
Create a second copy and hand it to somebody you trust. He cannot do anything but revoke your keys with it (never gain access!), but you always have a fall-back in worst case scenarios (house burned, robbery, ...).


My 7 yr old cant stay asleep beyond 5 or 6 hours?

Question: My 7 year old falls asleep straight away at bedtime, which is any time between 7 & 8 pm, but then wakes any time from as early as midnight onwards, then cant go back to sleep ?
Comment: Welcome to the site! Admittedly, I don't have a suggestion right now, but you could significantly improve your question with more details: What have you and your child tried so far, how is your usual routine, how long has this been going on and did you notice any effects on his / her daytime behaviour? Is this a consistent or occasional pattern, does he / she nap during the day? Any major changes in the child's life? Just waking up and feeling awake or waking from bad dreams? Any other symptoms... (You may edit your own question any time, no special reputation required.)
Comment: Have you tried keeping your child awake an hour longer to see if that will help?  Do you have a bedtime ritual?  What have you tried to help your child go back to sleep after waking?
Answer: There are a number of options you could try, I'm sure you must have tried some of these already but here goes:

Extend the bedtime to 9 p.m.
Ensure that she has some physical activity in the evening i.e. tire her out a bit.
Does she nap in the afternoon? If so then perhaps reduce the amount of nap time or stop it all together depending on what she's comfortable with.
Environmental factors: Is it something in the room that's bothering her? Try changing things up a bit.. different pillows/bed position/night light/comforter/room temperature etc. Try letting her sleep in a different room or a night or two.
Lastly if this is a recent occurrence there could be something bothering her which causes her to stay awake. Probe a bit and see if there is something you can help with? A class at school which she dreads, an after school activity she is not looking forward to (if this happens only on some days of the week).


Killing Lie algebra action on Lie algebra valued forms

Question: Let $G$ be a Lie group with Lie algebra $\mathfrak{g}$. Let and $P$ a $G$-bundle with a Riemannian base space $(M,g)$. Denote $\mathfrak{h}$ the Lie subalgebra formed by the Killing vector fields within the vector fields of $M$. This subalgebra acts on the space of vector fields via the adjoint representation. I would like to know if there is natural representation of $\mathfrak{h}$ over the space $\Omega^1(M, \mathfrak{g})$ of Lie algebra valued forms.
Answer: Sure: the entire Lie algebra of vector fields acts on forms and so vector-valued forms and, in particular, $\mathfrak{g}$-valued forms.  Now restrict this action to $\mathfrak{h}$.
However, yr principal bundle $P$ plays absolutely no role at all in this so I suspect I am not answering the question you really meant to ask.
Comment: Perhaps by $\Omega^1(M,\mathfrak{g})$ the OP means $\Omega^1(M,\operatorname{ad}P)$?
Comment: Perhaps, José.  But then the answer to the question is surely no unless $P$ is somehow tied to the Riemannian structure of the base...


How many Swaminarayan sects/subsects are currently active?

Question: someone says in Quora

Entire Swaminarayan Smapraday is divided into around 45+ different sects.

Is that correct?
Answer: Yes. Multiple subsets have emerged

New Swaminarayan Sects
As it happened, the greatest schism in the Swaminarayan movement was
prompted not by outsiders but came from within. In 1906 a sādhu, Swami
Yagnapurushdas, left the Vadtal temple. In 1907 he established the
first new Swaminarayan sect, the Bochasanwasi Shri Akshar Purushottam
Swaminarayan Sanstha (BAPS). Headquartered in Ahmedabad, Gujarat, BAPS
claims over one million followers worldwide including both laity and
ascetics.
.....
More so than the original sect, BAPS is a global movement
and, early on, it embraced new technologies to support its
transnational growth. It runs a large...
...
The wealthy BAPS
organization is criticized by dam opponents for acting to protect its
class interests, including those of its land holding members. In
response, BAPS followers who are familiar with the Narmada controversy
point to the various village relocation and community rehabilitation
projects voluntarily instigated and funded by BAPS.
In addition to BAPS's break from the original Swaminarayan satsaṅg,
other schisms have occurred. In 1966 a handful of East African BAPS
followers broke away and founded the Yogi Divine Society.
Additionally, sādhus from the original movement have left to form
their own institutions that sometimes (e.g., Swaminarayan Gurukuls)
but not always (e.g., Swaminarayan Gadi) retain an affiliation with
their gāddī.

Kim, Hanna H. (2005), "Swaminarayan Movement", in Jones, Lindsay
(ed.), Encyclopedia of Religion: 15-Volume Set, vol. 13 (2nd ed.),
Detroit, Mi: MacMillan

So, indeed there are multiple subsects, a perfect count of which currently might be unfeasible, as such which are many.


What is the electric field outside a cylindrical solenoid?

Question: What is the electric field outside a cylindrical solenoid when inside is turned on a magnetic field? The question is related to the question aharonov-bohm-effect-electricity-generation
Comment: Note that experimental tests of the Aharanov-Bohm effect have used the vector potential generated by electrically neutral ferromagnets (an [iron whisker](http://dx.doi.org/10.1103/PhysRevLett.5.3), a [shielded](http://dx.doi.org/10.1103/PhysRevLett.56.792) [toroid](http://dx.doi.org/10.1103/PhysRevA.34.815)), to which the answers below about resistive solenoids don't apply.
Answer: The magnetic field inside of a cylindrical solenoid of radius $R$ is given by
$$
\textbf{B} = \mu_0 n I \hat{z},
$$
where n is the turn density in turns/m and I is the current. The field everywhere outside the solenoid is zero. Let's assume that the current $I(t)$ is linearly increasing, so
$$
I(t) = at .
$$
For a cylinder of radius $r \ge R$, the flux through its center is
$$
\Phi(t) = \int_{S} \textbf{B} \cdot d\textbf{A} = (\mu_0 n at)(\pi R^2).
$$
We can apply Faraday's law to find the electric field,
$$
\int_{\partial S} \textbf{E} \cdot d\textbf{r} = -\frac{d}{dt} \int_S \textbf{B} \cdot d\textbf{A},
$$
and use the cylindrical symmetry to assume that $\textbf{E}$ is constant along the circular boundary. Thus,
$$
\textbf{E}(r, t) = - \hat{\phi} \frac{1}{2 \pi r} \frac{d}{dt} (\mu_0 \pi R^2 n a t) = - \frac{\mu_0 na R^2}{2r} \hat{\phi}.
$$
In this problem, all distances are measured from the center of the solenoid ($r = 0$). Unlike the magnetic field, the electric field is everywhere nonzero. For the more general problem, where $I(t)$ is an arbitrary function, the solution is
$$
\textbf{E}(r, t) = - \frac{\mu_0 n R^2}{2r} \frac{dI}{dt} \hat{\phi}.
$$
Comment: I think there's an inconsistency in your equations - the capital $R$ should be a lowercase $r$ (not a constant).  If you're evaluating the flux at a particular $r$ then the line integral for $E$ needs to be evaluated there as well...
Comment: The other issue is the flux. JUST outside the solenoid, the flux is $(\mu_0 n a t)(\pi R^2)$.  Inside, replace R with r.  Outside (beyond R) the flux will actually start falling off... but definitely won't increase.
Comment: Thanks @user3814483, fixed the mistakes. Complete oversight on my part. Should have paid more attention to how I defined r and R. Thanks!
Answer: For what it's worth, it is stated in http://arxiv.org/abs/1407.4826 and references therein in the context of the Aharonov-Bohm effect that even a constant-current solenoid has outside electric fields: "always there is an electric field outside stationary resistive conductor carrying constant current. In such ohmic conductor there are quasistatic surface charges that generate not only the electric field inside the wire driving the current, but also a static electric field outside it...These fields are well-known in electrical engineering." Sorry, I have not checked that, but it sounds plausible.
EDIT (07/25/2014) Seems there is a confirmation here: http://www.astrophysik.uni-kiel.de/~hhaertel/PUB/voltage_IRL.pdf , see, especially, Fig.4 therein.
Comment: Not sure why this was accepted.  One must consider the relative strength of this effect to that of Faraday's law in the specific geometry.  That is, this is not the all-encompassing answer; this is an effect that may or may not be important relative to the EMF induced by Faraday's law.  Note that the OP asked about a change in magnetic field, so this doesn't even apply.
Comment: @user3814483: Of course, only the original poster can explain why my answer was accepted, but I cannot agree that the answer "doesn't even apply". English is not my native language, but the OP is about the electric field when the magnetic field "is turned on", not "is being turned on". No "change" in OP. I believe my interpretation of the question is at least reasonable, the more so as it is the relative phase (between the cases where the magnetic field is turned on and turned off) that is important for the Aharonov-Bohm effect (which is explicitly mentioned in the question).
Comment: I interpret "when inside is turned on a magnetic field" to mean a change in magnetic field.  My point is, knowing nothing about what the poster knows, it should be pointed out that the AB effect could be minute and irrelevant if you do indeed interpret the question as I do.
Comment: @user3814483: I offered some arguments to explain why I interpreted the question the way I did. You offered no arguments to support your interpretation, so why should I interpret the question the way you do? I insist that my answer is fully applicable to the question. I could agree that my answer "is not the all-encompassing answer" as, for example, I did not estimate the magnitude of the effect that I referred to, but I hope you'll agree that answers do not have to be "all or nothing".
Comment: You shouldn't and you clearly didn't. I'm justifying my earlier comment about the relevance of the answer.
Comment: So we disagree on the relevance of my answer.
Comment: I suppose this mechanism doesn't matter if the solenoid is electrically shielded?


backup the difference with sql server express between 2 timestamps

Question: I am newbie to sql and have sql server express edition installed on my PC and contains
a database 'Jdatabase' on 1sept and took a backup(by right clicking on database -> tasks->backup using 'sql server management studio') of it and backup is 20GB
after 1 month , I took the backup  for the same database and it increased to 35GB.
Likewise saving the backup is going to be huge after certain time and is a problem for me.
If I want to backup only the difference ie., 15GB that has grown in 1 month time.
what is the best way to do it using SQL server express.
Comment: Perhaps you appended to the same backup file, so it now contains more than one backup? Check using RESTORE HEADERONLY FROM DISK = 'C:\temp\backupfile.bak'
Answer: My guess is that you ran this:
BACKUP DATABASE foo TO DISK = 'c:\backup\foo.bak';

... wait a week ...

BACKUP DATABASE foo TO DISK = 'c:\backup\foo.bak';

The result of this is that your backup file contains two backups, so the file itself will increase in size, whether that delay is a week or a minute.
To avoid this, you can choose one of two options:

You can reinitialize the file to remove any old backups and replace them with the new one:
BACKUP DATABASE foo TO DISK = 'c:\backup\foo.bak' WITH INIT;

This may or may not be desirable, since you only ever have a single backup, and if something should go wrong in between reinitialization and backup completion, you have zero backups.
You can write to a new file each time, typically people put a timestamp on the file or write to a folder made for that day.
BACKUP DATABASE foo TO DISK = 'c:\backup\foo201811010843.bak';

You can use a variable for the destination filename, so you can construct that based on GETDATE() as opposed to hard-coding it.
DECLARE @fn varchar(32) = 'c:\backup\' + CONVERT(char(8), GETDATE(), 112)
  + REPLACE(CONVERT(char(5), GETDATE(), 108),':','') + '.bak';

BACKUP DATABASE foo TO DISK = @fn;

The upside is that you don't have to be tied to a single backup file (and hence single point of failure). The downside is that you will have multiple files to manage... you may want some kind of cleanup task that automatically deletes everything except, say, the last two backups.

Now, there are a couple of issues that are tangential that I have to mention:

Are you only taking full backups? If so, then realize you will never be able to restore your database to a specific point in time, only to the point in time the last successful backup started. If that is a problem, you should use full recovery, not simple recovery, and determine a proper log backup schedule that meets your business requirements for how much data you can lose (RPO) and how long you can wait to get back up and running (RTO) in the event of a disaster.
If you are going to continue using simple recovery, you do have an option to take a backup of only deltas since the last backup, e.g.
BACKUP DATABASE foo TO DISK = 'c:\backup\foodiffwhatever.bak' WITH DIFFERENTIAL;

You'll need to manage files here, too, because all the differentials in the world are useless without the original full backup they reference. For more info, see Differential Backups.
If you are worried about your database growing to 35 GB but not having enough room to store a backup of that database, stop what you're doing right now and go find more disk space. You should not be making a decision between having data and being able to back it up and, frankly, you should not be storing your backups on the same disk as the database anyway (that kind of defeats the purpose). It's like keeping your car key in a jacket pocket and keeping the extra key (you know, in case you lose your jacket) in the other jacket pocket.
Answer:
If I want to backup only the difference ie., 15GB that has grown in 1 month time. what is the best way to do it using SQL server express.

Are you sure you have SQL Server express edition. The data file of express edition is limited to 10 GB for SQl Server 2008 R2 and above. Yes log file has no such limitation, anyways you cannot backup just the "difference". When you backup a database it will backup complete data not the difference and there is no way that you backup only the data changed after certain days using TSQL as well.
You can move out the data to new table if you have some column to identify data which was added after certain date like datetime column.


Computing Fisher's Exact Test for rxc tables

Question: I need to implement Fisher's Exact Test in R for rxc tables (c > 2). I know there already is fisher.test to compute such a thing but I need to get it done step by step so I can have custom requirements for p-value computing.
I have tried to first get the 'standard' results of the FET. I found in this article the generalization of a table probability computing using a multiple hypergeometric law :
$$ P = \frac{\prod_i{n_{i.}!}\prod_j{n_{.j}!}}{n!\prod_{ij}{n_{ij}!}} $$
As the tables I will be working on are 2x16 with values ranging from 0 to 20-30, $n!$ is too much for R to compute as is, so I used a natural log transformation so that I could compute the probability using lfactorial instead of factorial. I got the following equation :
$$ ln(P) = \sum_i\ln (n_{i.}!) + \sum_j\ln (n_{.j}!) - \ln (n!) - \sum_{ij}\ln (n_{ij}!) $$
I use r2dtable to get a set number of random table with given marginals (as simulations should be enough and a good compromise), compute the probability for all those tables and sum the probability lesser than my observed table's. I then end up with the following code.
set.seed(42)

# Dummy matrix at real dimensions
test1 <- matrix(floor(runif(32)*20), nrow = 2)

# Dummy 2x2 matrix
test2 <- matrix(floor(runif(4)*20), nrow = 2)

# Function to compute the probability of a table
get.tableP <- function(test){
  col.fact <- sum(lfactorial(colSums(test)))
  row.fact <- sum(lfactorial(rowSums(test)))
  cell.fact <- sum(lfactorial(as.vector(test)))
  tot.fact <- lfactorial(sum(test))

  lP <- col.fact + row.fact - cell.fact - tot.fact
}

# Computing the "cut-off" probability
ref.P <- get.tableP(test1)

# Computing a set number of random matrix with given marginals
p.values <- sapply(r2dtable(1000, rowSums(test1), colSums(test1)), get.tableP)

# Computing p-value
sum(exp(p.values[p.values < ref.P])) + exp(ref.P)

# Results given by R standard function
fisher.test(test1, simulate.p.value=T, B=1000)

# Same with 2x2 table

ref.P <- get.tableP(test2)
p.values <- sapply(r2dtable(1000, rowSums(test2), colSums(test2)), get.tableP)

sum(exp(p.values[p.values < ref.P])) + exp(ref.P)
fisher.test(test2, simulate.p.value=T, B=1000)

My problem is that when comparing my results to those returned by fisher.testI get huge differences when working on my 2x16 tables whereas the 2x2 tables are closer.
Is there anything I got wrong with the math or is it a problem with my implementation ?
Thanks !
Answer: Ok, the problem was that r2dtable generates random tables with replacement so when I was trying to test 1000 tables I was really testing about 60 unique tables. That's why such a gap was observed I think.
So the next question is how to make sure to have 1000 unique tables without having to generate 1e8 tables and filter out duplicates ?
Thanks for your help


How is ground path formed between EMT and painted metal boxes? Is the paint conductive?

Question: If metal pipe is attached to a painted metal box with a metal locknut how is the ground path achieved between the box and the pipe?  Is the paint conductive?  Or do we rely on the locknut to pierce the paint?  Surely the latter would be hit and miss.
Answer:
Surely the latter would be hit and miss.

Not at all. If properly tightened, it's guaranteed.
Since data can be fun: My multimeter reads open circuit/infinite resistance (more than 2 Mega-Ohms, I forget what the top of its range is, could be more than 20MΩ) for any distance between probes on the painted breaker box surface. It reads less than 1 Ohm between a galvanized cover screw on the painted breaker box and a junction box cover connected to a (galvanized) junction box connected to a fitting connected to EMT connected to a fitting connected to the main panel. The fitting in the main panel painted box was simply installed and tightened, no paint-scraping or the like.
Comment: Yep.  This is also why those locknuts have ridges on the box side, to scrape off any paint or rust as it tightens, ensuring a good electrical connection.
Comment: The paint is not conductive.
Comment: "properly tightened" : ***with a hammer and a slotted screwdriver.*** They make an actual tool for that but it still isn't going to be as good as *properly tightened*, +1. - I've never seen a lock nut that *wasn't* "designed so as to make such removal unnecessary."
Comment: Hey @JACK if you make your comment an answer I'll accept it since it's the closest thing here to a definitive answer to my question.    All the rest kind of skirt around what I've concluded: grounding is not an automatic feature of box connectors over paint, you have to be intentional about it and a pro will develop a rehearsed technique that will work reliably.
Answer: You're supposed to scrape the paint around the KO.  The National Electrical Code is pretty clear:

250.12 Clean Surfaces. Nonconductive coatings (such as
paint, lacquer, and enamel) on equipment to be grounded
shall be removed from threads and other contact surfaces
to ensure good electrical continuity or be connected by
means of fittings designed so as to make such removal
unnecessary.

See also
https://www.nfpa.org/NEC/About-the-NEC/Grounding-and-bonding

In grounded systems, it is important to bond the equipment grounding conductors to the system grounded conductor to complete the EGFCP back to the source of electricity. The conductivity of the EGFCP is critical for protective devices to work properly. This speaks to why we scrape the paint from contact surfaces of metallic enclosures to make our electrical system bonding connections. Removing the paint, as required in Section 250.12, provides for a better connection and conductivity path.

In my experience, most locknuts do not reliably remove enough paint to ensure bonding.  If the fitting (which is unpainted) is touching the edge of the knockout when the locknut is tightened, you still get electrical continuity, but it's best to scrape the paint and get really solid reliable contact.
Comment: I'm guessing the "or be connected by means of fittings designed so as to make such removal unnecessary" part is the main difference between this answer and the other -- in my experience, the locknuts generally have ridges that do a good job scraping away enough paint to make good electrical contact, but it's possible that not all of them do, and in that case, scraping the paint manually would be required.
Comment: I have tested it pretty thoroughly and although some styles of locknuts are better than others, none of the commonly available types reliably get through a coat of paint.
Comment: I came back here to select a best answer and I'm a bit distraught by @ NateS. comment "generally .... but it's possible that not all" along with @ mazura comment above re "properly tightened".   In my unprofessional opinion this is basically what I said in the question ... it's hit and miss.  Yikes.  I think the best answer was from @JACK who commented "The paint is not conductive".  The rest comes down to technique.  Scrape, tighten, test with a meter .... and I suppose a pro ends up using consistent brands along with practiced technique that becomes reliable.
Answer: To answer the question, the paint is not conductive.


Jenkins + Make + xcodebuild or Jenkins + sh + xcodebuild

Question: I saw this tutorial and I was wondering what were the advantages of using Make to setup targets for building and testing vs using sh scripts or event separate Jenkin jobs for build and test? I'm new to CI and scripting in general so sorry if this is kind of a silly question.
Answer: You should choose the best language for your needs.  First start with what you know, if it is make files use them.  If your project already uses make files, then you should utilize them.
Other projects use different things, ruby has rake.
sh scripts are if you already have a working knowledge of them and need to run some tasks inside jenkins.  It could just as easily be a ruby or a php script.


Milvus 2 Node.js SDK error: "TypeError: Class extends value undefined is not a constructor or null"

Question: I'm working on my Nuxt.js app. For the database, I have chosen Milvus. I want to do a similarity search, but I encountered an error in the browser console.
I have the following code:
app.vue
// Other code

package.json
{
  "name": "nuxt-app",
  "private": true,
  "type": "module",
  "scripts": {
    "build": "nuxt build",
    "dev": "nuxt dev",
    "generate": "nuxt generate",
    "preview": "nuxt preview",
    "postinstall": "nuxt prepare"
  },
  "devDependencies": {
    "autoprefixer": "^10.4.16",
    "nuxt": "^3.9.3",
    "postcss": "^8.4.33",
    "tailwindcss": "^3.4.1",
    "vue": "^3.4.6",
    "vue-router": "^4.2.5"
  },
  "dependencies": {
    "@nuxt/ui": "^2.10.0",
    "@zilliz/milvus2-sdk-node": "^2.3.5",
    "nuxt-security": "^1.1.0"
  }
}

As you can see in app.vue above, I'm using the Milvus 2 Node.js SDK, but I'm getting the following error in the browser console:
TypeError: Class extends value undefined is not a constructor or null
    at node_modules/@grpc/grpc-js/build/src/call.js (@zilliz_milvus2-sdk-node.js?v=bfe1cc22:10658:54)
    at __require (chunk-PIXRU2QS.js?v=bfe1cc22:10:50)
    at node_modules/@grpc/grpc-js/build/src/client.js (@zilliz_milvus2-sdk-node.js?v=bfe1cc22:11182:18)
    at __require (chunk-PIXRU2QS.js?v=bfe1cc22:10:50)
    at node_modules/@grpc/grpc-js/build/src/make-client.js (@zilliz_milvus2-sdk-node.js?v=bfe1cc22:11562:20)
    at __require (chunk-PIXRU2QS.js?v=bfe1cc22:10:50)
    at node_modules/@grpc/grpc-js/build/src/channelz.js (@zilliz_milvus2-sdk-node.js?v=bfe1cc22:11663:25)
    at __require (chunk-PIXRU2QS.js?v=bfe1cc22:10:50)
    at node_modules/@grpc/grpc-js/build/src/subchannel.js (@zilliz_milvus2-sdk-node.js?v=bfe1cc22:12227:22)
    at __require (chunk-PIXRU2QS.js?v=bfe1cc22:10:50)

I've searched this error in general and found multiple answers on StackOverflow saying that this is probably caused by circular dependency. I used dpdm to find potential circular dependency.
I ran the following command:
dpdm app.vue

But no circular dependency was found:
✔ [0/0] Analyze done!
• Dependencies Tree
  - 0) app.vue

• Circular Dependencies
  ✅ Congratulations, no circular dependency was found in your project.

• Warnings

I've been trying for quite some time, following official examples, but I'm not able to solve this error.
Answer: The library @grpc/grpc-js doesn't work on the browser, it only works on Node.js. It looks like you are getting it as a transitive dependency of the Milvus 2 Node.js SDK, which also states in its README that it requires Node.js.


Best way to set up a shared drive for a company using Linux (eg. Ubuntu Server)?

Question: I am trying to find out the best way to set up a shared drive for a company which has 50+ users in 3 office locations in different cities.
They basically need a drive with a common folder to store company documents (eg. /home/company-docs/) plus a personal folder for each user (eg. /home/username/mydocs/). They will mainly access the drive from Windows 7 machines and few Ubuntu machines.
They cannot use an external application such as Dropbox, Google Drive and so on (for regulatory and compliance reasons).
I am currently using Ubuntu server 14.04 with ProFTPD, and the machines access the server drive using WinSCP or Filezilla. For permissions I am using ACL.
The tricky part is the folder structure so everyone can see the common folder (/home/company-docs) and the personal folder (/home/username/mydocs) in their home directory.
Using ProFTPD I can chroot jail the users to their home directory and there mydocs/ folder is created (using skel).
But how can I give them access to the company folder which is located outside their home folder (path is /home/company-docs)???
My first option is to mount /home/company-docs/ in the user home:
<code>mount --bind /home/company-docs/ /home/user_name/company-docs
</code>
And then make this configuration permanent by editing /etc/fstab:
<code>/var/www/dev  /home/user_name/www_dev    none    bind    0       0
</code>
But the above solution works for just 1 particular user, how can I make this work for every user in the system and make it permanent for every user? and also how to set it up automatically when a new user is created?
Please let me know if you have any idea on how to accomplish this or any other better way you may think on doing it.
Answer: The Windows machines should be able to use Samba to mount their drives.  The Samba documentation covers this scenario in detail.
For linux machines you can use NFS to mount the required shares.  I use automount rules to mount home directories.
Both these options should work over VPN for traveling users.


The meaning of the word until - exclusive or inclusive

Question: So I realize now that I probably should have clarified this at the time, but in my divorce agreement, I am obligated to make a payment monthly, "until September 1, 2021". I read this as "up to but not including September 1", meaning that my last payment would be in August, where September 1 is the first day that I am no longer obligated to make monthly payments. However, in plain english, this might be ambiguous. I would think that there's a definitive answer for this when speaking legally.
Comment: Even if we restrict to English speaking countries, I suspect that both the opinion about the ambiguity itself and the way to resolve such a possible ambiguity may depend on jurisdiction, so I suggest to add that yours
Answer: The default meaning is exclusive, but this can be overridden if a contrary intent of the parties is evident. However, the actual textual context (of the agreement) is not irrelevant, e.g. the actual sentence that it appears in. Additionally, there are obscure dialect difference that could be relevant, so I assume standard US or UK English.
Given the full sentence in which "until" appears, the intended meaning (over-elaborated) is "However, if the Husband vacates the apartment prior to September 1, 2021 he shall be obligated to pay to the Wife only the monthly rent which is owed for the period prior to September 1, 2021". The recurring obligation is for occupancy of the apartment, so if you have moved before the 1st, the obligation is finished with the last month's payment, presumably remitted in August. Clearly, you do not have to keep paying monthly rent every day up to Sept. 1, so "until" refers to the termination of the rent obligation.
Comment: Other possible contextual clues: If rent for occupancy from Aug 1 to Aug 31 was due on September 1, I might interpret this as meaning that the September 1 payment is included.  If paying rent on September 1 resulted in exactly 13 (or 1 more than a multiple of 12) post-divorce payments, I'd probably assume payment on September 1 was not required.  If paying rent on September 1 resulted in exactly 12 (or other multiple of 12) post-divorce payments, I'd probably assume that payment on September 1 was required.
Comment: The full sentence is, "However, if the Husband vacates the apartment prior to September 1, 2021 he shall be obligated to pay the Wife the monthly rent until September 1, 2021."
Comment: That this payment is conditioned upon the husband leaving "prior to" September 1, 2021, I would think that user6726's answer is correct for your case, i.e., the payments continue up to but not including September 1. If instead of "prior to" it had read "on or before", for instance, that might change my mind.
Comment: I would interpret "rent until September 1, 2021" that rent is to be paid for Sept 1st, but not Sept. 2nd until Sept. 30th, so one day's rent, about 1/30th of the monthly rent. So the removal van comes on Aug 31st, the wife spends Sept 1st. to check out the rooms, throw out things left behind etc. and cannot use the rooms, so rent is due for that day.


Why didn't the antimatter spread affect the Borg Cube?

Question: In "The Best of Both Worlds, Part II," the Enterprise fires a burst of antimatter at the Borg Cube, apparently to no major effect. Why didn't the antimatter tear through the Cube?
Answer: The Borg had already adapted to the potential threat of the antimatter beam because they knew it was coming and altered their shields accordingly.

More importantly, the antimatter spread was merely a diversion to allow the Enterprise crew to recover Picard.

In the opening sequence, Locutus of Borg (Jean Luc Picard) quietly reports:

"The knowledge and experience of the Human, Picard, is part of us now. It has prepared us for all possible course of action. Your resistance is hopeless, Number 1."

Once Captain Picard was absorbed into the Collective, all of his knowledge, his battle strategies, anything the Federation could know or do, became available to them. This would allow them to know exactly how to defend against any conventional attack.

Borg ships are ridiculously powerful, with engines and powerplants scattered throughout the cube. With the right information regarding frequencies, energy profiles and technological specification, they would be invincible against an enemy whom they have absorbed into the collective.
Comment: 1 cube > whole fleet...  the borg in tng are sick overpowered. considering they send 1-3 cubes total in the whole show and the fed destroys 1 for sure in first contact only because picard knows exactly where to hit it. Thankfully by the end of voyager we see the fed has the tech to keep ahead of the borg.


Opening a bank account in China

Question: I'm trying to open a account with any of the major banks in China, but I live in the US. Is this possible and how would I go about doing this? I would also like to be able to transfer money between my accounts in the US and the account in China. Whats the cheapest way to do this?
Answer: Find a Bank of China branch in the United States.  They have them in Canada!
This link is to the Bank of China website, along with branch locations.  They are in New York and L.A.
http://www.boc.cn/en/aboutboc/ab6/200812/t20081216_494260.html
And the Bank of China USA website:  http://www.bocusa.com/portal
There are a number of Bank of China Branches in Canada due to the high numbers of Chinese people.  I'm sure a phone call or an email to them will help.

Opening a bank account in China


Joomla web service module

Question: I am looking for a Joomla web service module to allow users to create a user login and add posts and comments.
I am writing a standalone mobile version of my joomla site and I need it to call these web service functions.
Answer: Joomla has an XML-RPC interface. However, it will be removed in Joomla1.6 btw.
Also take a look at:
http://extensions.joomla.org/extensions/news-production/
And :
http://extensions.joomla.org/extensions/news-production/blog/3831

Joomla web service module


Does Open-stack supports heterogeneous servers as infrastructure

Question: My company uses Apache cloud stack, but we are planing on upgrading our on premise cluster, and change our IAAS from Cloud-Stack to Open-stack my question is, can we use different servers generations, CPUs. I found services online that offer heterogeneous support as a sale point while they are based on Open-Stack.
Note: Open-Stack NOVA / Magnum solutions
Comment: OpenStack contains a [wide variety of more or less related software components](https://www.openstack.org/software/). Some are more suitable for a heterogeneous infrastructure than others. It might be helpful to know which components you intend to use.
Comment: Okay, I would say NOVA / Magnum because we have a web application. as for storage; we only using one unit currently for the cluster, but in production projects we will go with one storage method/protocol. i'm not sure about networking.
Answer: The whole basis of OpenStack is that you can run it on any hardware you have available, it doesn't have to be homogeneous. That being said, it is helpful for some components to be identical.
Regarding Nova instances, for example, if you want to do live migrations of virtual machines from host to host the CPU has to be identical. If you don't need that, or you emulate the same CPU on all hosts regardless of what CPU is built into them, you should have no problems.
Regarding containers controlled with Magnum: Live migrations are not done here, you just start and stop the containers on any host available. As long as no specific CPU flags are needed by your application there is no problem here either with differing hosts.


Load PostGIS Layer with BLOB and use the form widget for binary fields (QGIS 3.6) not working

Question: I have tried to load a PostGIS layer containing a binary data field (BLOB, bytea) and then use the new form widget for binary fields (https://qgis.org/en/site/forusers/visualchangelog36/index.html#feature-new-form-widget-for-binary-blob-fields). The problem is, that the binary field will not be in the layers attribute table, so the widget can not be used/activated. In the QGIS database manager the field is visible in the table preview. Does anybody knows what is going wrong or what I am missing?
Answer: QGIS (as of version 3.8.0) has no support for binary/bytea fields from Postgres sources. As of version 3.8, they are only supported for disk-based vector layers and in-memory scratch layers.
Answer: This is possible in QGIS 3.16 (not tested on previous versions).
You can add a bytea column to your layer and QGIS is able to insert and retrieve the BLOB (if using PostgreSQL).
In the following use case, I added a photo bytea column to my layer to store images.
To configure the feature form, please follow the answer to create either and HTML Widget or QML Widget to see your picture.
Your bytea field will became a Binary Widget and you can use it to upload your binary data.
If you use images, add an HTML Widget or QML Widget to the feature form to display the image, as shown below.

If you use other types of binary data, you have to customize the widgets.
Tested with Geopackage and PostgreSQL providers.
Comment: Also works with MS SQL.


Do isotones share any similarities?

Question: A trivial research in atoms and their basic theories led me to this term: "isotones"
Nuclides sharing the same number of neutrons but different atomic numbers.
A simple request or shall I say, quest:
please indicate me to any feasible similarities existing between isotones and please, DO NOT use jargon.
Answer: Chemistry is determined entirely by electron interactions. Since the number of electrons in an atom is determined by the number of protons in the nucleus, the atomic number (number of protons) is what defines the chemical behavior of a given element. This means that in terms of chemical properties, isotones would have no similarities unless they happened to be in the same group (column) of the periodic table, but that would be a coincidence and would have nothing to do with the number of neutrons.
As DavePhD and ron said, the nuclear stability could be similar, since nuclear stability has a lot to do with the total number of nucleons (neutrons + protons) as well as the relative proportion of protons to neutrons. The wikipedia article on isotones discusses stability in a little more detail.
Answer: I suspect that having the same number of neutrons may mean something at the nuclear chemistry and nuclear physics level, but in terms of general chemistry, including inorganic, organic and biochemistry, it's all about the number of electrons and protons.  So I don't think that isotones would show any differences in terms of (non-nuclear) reaction chemistry.
Answer: In chemistry, if an atom has a closed valence electron shell, as do the noble gases, it is particularly stable.
Similarly, there is a shell model of the nucleus.
Certain numbers of neutrons (and also protons) are referred to as magic numbers: 2,8,20,28,50,82,126, all even numbers, because nuclei with these numbers of neutrons (or protons) are particularly stable.
The similarity between isotones is that stability of a nucleus is somewhat correlated with the number of neutrons.

Do isotones share any similarities?


What is the textual origin of the quote attributed to Goethe starting "The heights charm us, but the steps do not"

Question: The full quote is

The heights charm us, but the steps do not; with the mountain in our
view we love to walk the plains.

I remembered reading it several years ago, most likely in quotation, but a search failed to find the original context.
Answer: Wilhelm Meister's Wanderjahre (Wilhelm Meister's Apprenticeship)
Book VII Chapter IX

Art is long, life short, judgment difficult, opportunity transient. To act is easy, to think is hard; to act according to our thought is troublesome. Every beginning is cheerful: the threshold is the place of expectation. The boy stands astonished, his impressions guide him: he learns sportfully, seriousness comes on him by surprise. Imitation is born with us: what should be imitated is not easy to discover. The excellent is rarely found, more rarely valued. The height charms us, the steps to it do not: with the summit in our eye, we love to walk along the plain. It is but a part of art that can be taught: the artist needs it all. Who knows it half, speaks much, and is always wrong: who knows it wholly, inclines to act, and speaks seldom or late. The former have no secrets and no force : the instruction they can give is like baked bread, savory and satisfying for a single day; but flour cannot be sown, and seed-corn ought not to be ground. Words are good, but they are not the best. The best is not to be explained by words. The spirit in which we act is the highest matter. Action can be understood and again represented by the spirit alone. No one knows what he is doing while he acts aright, but of what is wrong we are always conscious. Whoever works with symbols only is a pedant, a hypocrite, or a bungler. There are many such, and they like to be together. Their babbling detains the scholar: their obstinate mediocrity vexes even the best. The instruction which the true artist gives us opens the mind; for, where words fail him, deeds speak. The true scholar learns from the known to unfold the unknown, and approaches more and more to being a master.


SG300 Load balancing / distribution configuration

Question: I have a SG300-28p switch I want to connect 18 devices, but want to balance or distribute evenly the traffic between groups of six ports (1-6, 7-12, 13-18). I was hoping to have DHCP enabled for all ports (if configuring for VLAN 100,101,102 to the ports respectively).  Any advice for this configuration?  I'm hitting a brick wall (as I'm a newbie). (Background - want to connect multiple Raspberry PI's for data analysis - so will consume lots of traffic).
Comment: The traffic distribution will be dependent on the MAC address of the destination.  If all your traffic goes to one MAC address, it all goes to one port.  There's nothing to configure.
Comment: Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
Answer: Switch Generally does not provide Load balancing capability for one single mac address. Switch find destination based on mac address. Device can have only one mac address or only ip address,
but switch provide ether channel. Ether channel is link aggregation or port channel architecture is being used.
But device have to have multiple interfaces. when you use ether channel it will create one logical interface combining multiple physical ports. You can use 2-8 ports in ether channel.
for more details click Here


How to deal with favoritism in the lab?

Question: I've observed that many PIs are especially prone to having favorite students in their research group, and will treat these students differently than others. Most of the time, this isn't so obvious and doesn't cause problems. However, from time to time, this will be made extremely clear as the time spent on the "favorites" are orders of magnitude more than other students in the lab. This also includes assignments of better projects etc. Of course, I realize that as humans, everyone has favorites, and it is unrealistic to expect manager figures to treat everyone equally. However, I have noticed that in the few groups I've worked in, some PIs will make it embarrassingly clear. For instance, it will often lead to hurt feelings and lost productivity when something essential is not done for one student's project (i.e. read over drafts, provide necessary components of experiments) while the advisor runs to help another student with mundane aspects of their experiment (i.e. actually helping them do the experiments, or spending a lot of time talking with them while telling others they are busy). This is of course common in all workplaces, but I do feel that the advisor/trainee relationship is different in that in many ways the success of the student is very much dependent on the advisor.
Comment: Focus on getting what _you_ need from your advisor, and don't get caught up in what other students are doing. (Different students have different needs, different abilities, etc.)
Comment: I'd argue the concepts here apply not just in the academic setting, but in life in general. To some extent, that's the nature of office politics -- for better or worse, it's unavoidable. That being said, there's a difference between basic office politics and actual nepotism -- and as you pointed out, with the highly personal nature of the adviser-advisee relationship, the line gets blurred much faster (in my opinion).
Answer: An anecdote: my advisor was extremely hands-off for me; we met pretty infrequently and when we met, it was mostly spent on talking about small side issues that came up in my projects. Another student of my advisor had a very different experience. He met extensively with my advisor, he found projects for him to work on (I proposed my own, and my advisor didn't know much of my project until I wrote my thesis). The tension for me reached its climax when my defense date drew near; he told me that he was busy with the other student's thesis and that he will sign mine after he is finished with editing the other student's thesis. He ended up reading my thesis only a couple of days before my defense.
Although this seemed like favoritism, in the end it wasn't. He must have judged me to be an independent and competent researcher, because I got more and better job offers afterwards.
So, there really isn't anything you can do. You should just focus on your own projects, and hopefully your advisor is there when you really can't solve the problem on your own. But if you treat each time that your advisor isn't there as an opportunity to show your competence (whether you think your advisor noticed it or not... it does accumulate!) you'll walk out having become independent, which is an important quality to possess in academia.
Comment: Same experience. It is typically the weaker students who receive more "attention". And honestly, even if the PI had a favourite student, and lavished them with attention, so what? PIs are only human, and as long as you are getting what you need from them, there's no harm done.
Comment: I once saw a case where everyone else thought Student X was the favourite. The truth was that Student X had known the PI for the longest, and they already had a warmly friendly and productive relationship by the time everyone else met the PI and got to know them. It's easy for time offset to look like favouritism.
Answer: Your description reminds me of siblings' experiences of sibling rivalry in families.
Different people need different things.  Different people need different amounts of things.  Keeping this in mind can help prevent hurt feelings and resentments.
I suggest you focus on what you can do to make things better for you and for your group.  Here are a couple of ways that might be done.  These might not all be a good fit for you and your group -- I am just brainstorming.  But I'd like you to do some brainstorming about this too.

Make an objective assessment of what you need help with and what you're able to do without help.
Assert yourself to get the help you need.
Make yourself available to help others in your group.

And don't forget to make plans for how you will do things better when you are a PI.
Answer: Personal effort to win the teacher's attention may not be what you want to attempt. The nature of your teacher's favoriticism sounds detrimental. A good teacher should know the difference between explaining things to a student and teaching the student how to decipher the meaning of things by themselves. You can't fix this part of your teacher. However, certain acts of the teacher (as described by you) are unjust and something needs to be done about it.
Anything you do in this regard has to be group effort. A hostile or challenging attitude migh do more harm. Maybe the best people who can approach the teacher regarding this issue in a non-hostile manner will be the favorite students themselves.
It all depends on What kind of a person the favorite student is. I used to be a favorite student in most classes, but I never reserved any private time with any teacher. When the other students had any issue with the teacher focussing too much on me, they used to express their disapproval directly to me.
.
Comment: I am sorry if it sounded broad, but I was only talking about the necessity of group effort in dealing with this specific situation, not her education and career in general which I know nothing about.
Comment: The advisor is providing harmful attention to their favourite students. You don't want your advisor to babysit you through PhD. Also, I see no indication that OP wants to become a favourite. My comment was just a cautionary analysis claiming that the incompetence of the teacher is more fundamental than it appears.
Comment: Helping students with mundane aspects of the experiments or actually helping them do the experiments sound harmful to me. Of course every student should be closely supervised. I have never said otherwise. It is the nature of supervision I am worried about. That kind of supervision will do more harm than good. Attention should be divided based on the merits of students.

How to deal with favoritism in the lab?


How do I use EXIF tags to determine the length of an object in focus?

Question: I have an image with EXIF information encoded into it. What I need to know is what information I can use to determine the length of a certain object. For example, are there tags that hold the camera opening angle and distance from the object in focus? (from which I could calculate distance using trig). Are there other approaches?
Comment: You should know also the size of the object projection on the sensor and the distance from sensor to the focal center of the lens.
Comment: We've had nearly countless similar questions here. What question do you have that they do not answer?
Comment: [Can we measure size of an object using EXIF data from a photo?](https://photo.stackexchange.com/q/23414/15871) and [Estimate object size](https://photo.stackexchange.com/q/82718/15871) and [How to automatically measure subject dimensions (width/height/distance) without physically measuring?](https://photo.stackexchange.com/q/39986/15871), etc.
Comment: This is a very open-ended question, that is highly dependent upon many specifics. As asked, without more specific information, we have existing questions that address this question.
Answer: You need:

The sensors size/definition (or "pixel size"), so that when you measure the size in pixels you can transform that to millimetres on the sensor. This is found on the Exif (Focal plane resolution) but can also be deduced from cameras specs, it won't vary between shots.
The focal length of the lens. This is also part of the Exif (Focal length), but this is the "nominal" focal length, if you focus on something close it will be somewhat different (on my lens the front lens extends when focusing close), but the various EXIF that report the focal length remain the same (at least as far as I can tell, with my camera(*)).
The focusing distance. This is also part of the Exif, but not very accurate, the purpose of the camera being to be in focus, not measuring distance. To give you an idea, shooting at an object exactly one metre from the front lens the focusing distance is reported to be 1.10m-1.40m. Shooting something across the street, the focusing distance is reported as being 8.4m-infinity. Needless to say, this is not terribly accurate.

And of course you can only evaluate the size of things that are strictly perpendicular to the camera axis (so, for heights, the camera need to be horizontal). Otherwise you have to factor in the angle, but you have to obtain it using external cues.
Sot it all depends how accurate you want/need to be....
(*) Canon EOS 70D + Canon EF 50mm f/1.8