What does having temporary HP look like?

Question: I am playing a character who frequently has a pool of temporary HP. Normally when people take damage you can see how they were to how they are to get some idea of how a battle is progressing. But what about people who have temporary HP? How do they appear both before they have lost any, and while they are losing that temporary HP?
Comment: Where do you get "Normally when people take damage you can see how they were to how they are"?
Comment: @Fering Where did you find that you can see how damaged a goblin looks after being hit? Hit points are a game mechanic that includes even things like "luck", it's not a metric the characters can see. A DM can easily describe a 5 damage attack as grazing their shoulder, and then describe the final 1 damage as an arrow hitting them straight in the eye, there are no rules about "seeing damage".
Comment: @Ifusaso You hit a low CR goblin for 5 damage, their going to look almost dead, you hit a high level enemy NPC for 5 damage, and they have a papercut.
Comment: So... are you looking for suggestions or viable homerules or something? There is no RAW (that I'm aware of) of what *any* amount of damage on something looks like. I know some game systems describe it; however, because of they way Pathfinder increases HP it doesn't make as much sense describing how the same sword blow can nearly fell one creature but another shrug it off like a paper cut. Because of this, they leave rules out of it.
Answer: It is up to the narrative style of the GM and players. Here are some ideas:
If the source of the temporary hit points is magical, you could describe them as a visible field, or a barrier visible only when struck.
If the source of the temporary hit points is non-magical then it depends on how you describe normal hit points. Because I think of hit points as a character's physical and metal stamina (and minor injuries), I would describe non-magical temporary HP as vigor and enthusiasm. If a character is struck, but still has some temporary hit points left over, I would probably describe how they defiantly block the blow, and, completely unfazed, raise their sword for the counterattack (or whatever). This is in contrast to losing actual HP: the character brings their shield up just in time, but they're jarred by the blow, and afterwards they look tired, ragged, and bruised.
Answer: ADDENDUM NOTE: In my earlier answer, I did not see, as Shadow Kras mentioned, that the question was based on Pathfinder's system. I had answered based on D&D 5e rules. I went to read Pathfinder's rules online and have changed my answer accordingly.

Still a Great Question!
In reading the Pathfinder rules for Temporary Hit Points...
"Certain effects give a character temporary hit points. These hit points are in addition to the character's current hit point total and any damage taken by the character is subtracted from these hit points first. Any damage in excess of a character's temporary hit points is applied to his current hit points as normal. If the effect that grants the temporary hit points ends or is dispelled, any remaining temporary hit points go away. The damage they sustained is not transferred to the character's current hit points.
When temporary hit points are lost, they cannot be restored as real hit points can be, even by magic." (Source: https://www.d20pfsrd.com)
Also, after reading what Pathfinder said about "Injury and Death" and stabilizing a character, I would adjust my answer to fit Pathfinder this way...
1) How do they appear before they have lost temporary HP?
Since Temporary HP is simply an "invisible barrier" around the character, if you will, that absorbs damage FIRST, until that character receives actual damage to their current or "real" HP, then they would not look any different than they did just prior to receiving the temporary HP.
If they were almost dead then they would still appear in the same condition. If they looked completely strong and uninjured, they would still appear the same. The Temporary HP would simply protect them from receiving damage to their current/real HP total until the Temporary HP were diminished in full. It does not change how they look UNLESS YOU DECIDE IT WILL. For Example: When they receive Temporary HP, a faint blue aura appears about them or the hair on their arms stands up or their eyes turn a violet color. It's up to you.
2) How do they appear while they are losing that Temporary HP? The same holds true. Again, nothing changes from how they looked just prior to receiving the Temporary HP UNLESS you decide you want them to look slightly different. Outside of that, their appearance will only change if and when they start taking damage to their current or "real" HP.
As far as describing what they are experiencing while taking damage and protected by Temporary HP, you can use something similar to the below...
Temporary HP from Magical Means: "As the orc slammed his ax into your chest, a faint rippling of warm energy washes across the area keeping the ax from biting into your armor and the flesh beneath."
Temporary HP from "Natural" Means: "As the Gargoyle's claws slashed across your chest, your natural defenses or rather unnatural defenses saved you once again, keeping them from ripping through your armor and int your flesh beneath."
Hope that is a better answer for your game system than what I provided initially for D&D. And actually the above would still apply to D&D as well.
Comment: While a good answer, you got the wrong game system.
Comment: @ShadowKras this question is really system-interchangeable.
Comment: Though both ShadowKras and MrHitTech are correct, I adjusted my answer to reflect Pathfinder rules. I will have to pay closer attention next time. Thanks!


Structurally mounting to hollow brick

Question: I am replacing an old balcony with these custom designed supports. When I drilled in with 1/2 masonry sleeves it would not grab. Looking at the brick, its hollow. Is there any way to safely secure these brackets without having to put supports on other side of the wall? The top header of the deck meets the floor header of house so I plan on bolting right to it, which will help, but the supports only go into the hollow brick. See pics. enter image description here. I have more pics, but cant find a way to upload more than one here.
Comment: Who designed the supports?
Comment: You didn't provide any dimensions, so its hard to even make a guess at what the pull out load is on the top fasteners.  But figuring on a couple of adults & kids (500-600 lbs) standing near the edge, it's going to be significant.  I agree with those who have said this is a disaster waiting to happen if you try to fasten to the holly brick facade.
Answer: I would never hang a deck off a brick veneer or any finish, you have to attach to something structural.  The pullout force generated by the cantilever is going to be tremendous.  When it fails, it won't be a minor mishap.
Honestly I wouldn't go anywhere near this without putting a lot more thought into it, getting an engineer or architect's stamp on the plan, and getting it inspected.
Comment: I totally agree. This would be an accident waiting to happen. +1
Answer: Those brackets aren't going to work on a hollow brick wall.
What you do is rip up the floor inside those doors and fit pressure treated cantilever floor beams that support the interior floor and are securely attached to the building frame at the far end and where they pass through the wall.
if you don't want to rip up the floor maybe you can rip up the ceiling below instead.
Answer: I own a home with an upper balcony with cantilever floor joists that extend out to support the balcony.
These are TROUBLE with a capital T.  DO NOT go this route.  With mine one of the beam ends is already rotting so my only option is basically to cut the beam off the side of the building and hope that the wood rot hasn't extended into the interior of the house.
Get rid of those custom designed supports and replace the 4 posts that clearly were there before (as you can see the darkening on the side of the building showing there used to be posts there) and quit second guessing the architect.  I've seen some pretty dumb fails in post-construction home modifications, haven't people ever played with Lincoln Logs as kids???
Answer: The brick is no so much a problem as the mortar , it has very little tensile strength. Any significant force ,other than compression, will pull it apart.

Structurally mounting to hollow brick


How can I find current SSH protocol version of the current connection?

Question: I connect to a Linux machine (CentOS 6.4) using PuTTY. Except from fact that I can set PuTTY to only use one type of protocol, how can I find the current SSH connection's version (SSH1 or SSH2)?
Comment: It can help to show what research you've already done
Comment: @DrewKhoury I only tried with google to find an answer to this but no result found regardin this. No one explains how can I see the current connection (in use) protocol (ssh1 or ssh2).
Answer: Once you are in you say:
ssh -v localhost

it will tell you the exact version of the server.
Comment: It doesn't seem that this shows the current connection type.
Answer: An alternative way.
As cstamas suggested, you can use ssh -v localhost. Uou simply ssh to yourself 127.0.0.1 on verbose mode, which will display debugging messages of the progress. Yes, through this process you can look at the top of the communication and you can get the SSH version that you are currently running.
But if you read the ssh man page, you will find the -V option on ssh more useful. Taken out the ssh man page:

-V    Display the version number and exit.
-v    Verbose mode. Causes ssh to print debugging messages about its progress. This is helpful in debugging connection, authentication, and configuration problems. Multiple -v options increase the verbosity. The maximum is 3.

So I think it would be better to simply do ssh -V and get something similar to:
> ssh -V
OpenSSH_6.6.1p1, OpenSSL 1.0.1e-fips 11 Feb 2013

Comment: That's the version of the _program_, not the protocol used for a connection. As a 3-year earlier answer correctly explained, the very same program can support both SSH1 and SSH2 protcols, or not, depending on configuration.
Answer: PuTTY
In Session, Logging, select the "SSH packets and raw data" radio button. Select the log file as putty.log in a location of your choice. Make the connection. You should see:
Event Log: Server version: SSH-2.0-OpenSSH_5.3
Event Log: Using SSH protocol version 2

See below for details on what SSH-2.0 means.
Other Methods
You could also try using the telnet client, but point to port 22:
telnet test1 22

When you connect you will see:

Trying 192.168.144.145...
Connected to test1.
Escape character is '^]'.
SSH-2.0-OpenSSH_5.3

The last line is the one to look for:
SSH-2.0-OpenSSH_5.3

If it says SSH-2.0 then that is good, the SSH server you connected to supports only SSH protocol version 2. It will not support connections from SSH V1 protocol clients.
If however you see:
SSH-1.99-OpenSSH_5.3
Then that means that the server end is still supporting SSH protocol version 1. It has something like this in it's sshd_config file:
Protocol 1,2

Protocol 1 is vulnerable and should not be used.
So to get that straight. If you see SSH-2 when you telnet to port 22 of the remote server then you can only be using SSH protocol version 2 as the server does not support protocol 1.
As per cstamas answer above, the -v flag will show a line:
debug1: Remote protocol version 1.99, remote software version OpenSSH_5.3

or:
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3

You want to see version 2.0 there.
Comment: Re *"...is still supporting SSL protocol..."*: Do you mean *"...is still supporting SSH protocol..."*?
Answer: I like this better:
$ echo ~ | nc localhost 22
SSH-1.99-OpenSSH_3.9p1
Protocol mismatch.
$

The benefit here is that it can be done programatically since the connection isn't held open. For Python, try:
ssh_protocol = float(re.search(r"SSH-(\d.\d+)").group(1))

Answer: You can get this pretty quickly using netcat from your local machine, for example:
$ nc [IP_ADDRESS] 22
SSH-2.0-OpenSSH_5.3

Comment: Yep. `"SSH-2.0-OpenSSH_6.0p1 Debian-4+deb7u6"` for an old Raspberry Pi (internal). I also got the exact same result as you for some web hosting ([Red Hat Linux](https://en.wikipedia.org/wiki/Red_Hat_Linux) based?).
Answer: To get more details you can use this:
    rpm -qi openssh

Name        : openssh
Version     : 7.4p1
Release     : 21.el7
Architecture: x86_64
Install Date: Пт 17 янв 2020 12:21:57
Group       : Applications/Internet
Size        : 1991172
License     : BSD
Signature   : RSA/SHA256, Пт 23 авг 2019 00:37:23, Key ID 24c6a8a7f4a80eb5
Source RPM  : openssh-7.4p1-21.el7.src.rpm
Build Date  : Пт 09 авг 2019 04:40:49
Build Host  : x86-01.bsys.centos.org
Relocations : (not relocatable)
Packager    : CentOS BuildSystem <http://bugs.centos.org>
Vendor      : CentOS
URL         : http://www.openssh.com/portable.html
Summary     : An open source implementation of SSH protocol versions 1 and 2

Answer: The only method I am aware of requires that one has sufficient privileges to view the ssh log entries in /var/log/auth.log.
$ echo $SSH_CONNECTION
127.0.0.1 12375 127.0.0.1 22

The first and second fields of the SSH_CONNECTION variable indicate the source IP address and source port of my connection. By grep-ing for those values in /var/log/auth.log, I can find the log entry from when my SSH connection was authenticated.
$ sudo grep -F ' from 127.0.0.1 port 12375 ' /var/log/auth.log | grep ssh
Jun 26 16:29:52 morton sshd[20895]: Accepted keyboard-interactive/pam for jim from 127.0.0.1 port 12375 ssh2

This log entry tells me that my current connection is using the SSH 2 protocol. Of course, if the ssh session has been open for several days, the log entry may be in /var/log/auth.log.0 or some older auth.log file.
Answer: One can try to login using SSH -1 , and shall be rejected if this version is disabled:
$ ssh -1 user@server_name
SSH protocol v.1 is no longer supported

SSH 2 shall be accepted:
$ ssh -2 user@server_name


Bacteria was used treat cancers at one time. Did the manufacturer, Parke Davis, ever patent these cancer treatments called Coley's Toxins?

Question: A Commotion in the Blood.  By Stephen S. Hall.  Page 117 "a further discouragement in terms of the toxins is that without patent protection on a hundred year old treatment, there is little incentive for a drug company to invest upward of $200 million to test the vaccine and find that it works, only to watch competitors stream into the market".
Comment: I think based on the Wikipedia article that Coley used his treatment well before Parke Davis became a distributor. This would suggest that if a patent ever existed it would no have been filed by PD. Why do you ask?
Comment: FYI - also from Wikipedia "There is no evidence that Coley's toxins have any effectiveness in treating cancer, and use of them risks causing serious harm.[4]"
Answer: According to the Wikipedia Article, Coley started using his "toxins" in 1893 and published his results. I searched on patents assigned to Parke Davis and the earliest listed in Google Patents was from 1901 and was not related to Coley's toxins. I highly doubt that Parke Davis ever held a patent on Coley's toxins. I also searched for patents invented by William Coley and couldn't find anything related.
As the Wikipedia article documents, there have been studies done and no scientifically supported evidence of efficacy. Research into the performance of treatments is not limited to private drug companies. The NIH funds a great deal of research. I will also point out that companies regularly manufacture off-patent medicines. It is an enormous business.


How To Fill My Down Time As Support

Question: Whenever I play support I always find myself wandering aimlessly when I'm not either shadowing my ADC or engaged in team fights. What should I do when I'm not doing either of these things?
Comment: Wards win games.
Comment: Is it worth buying wards after I have my sightstone? Even if I can only place 3 on the map?
Comment: You usually just want your Sightstone and even sell your ward trinket for a lens afterwards or upgrade it to a pink one. With your Sightstone you can carry 5 wards of which you can place 3. With an upgraded Warding totem and Your Sightstone you always have 5 normal wards and 1 pink ward.
Comment: @Jutschge Red sightstone and pink trinket is my usual build path. So I only find myself buying wards early game. It's hard to gauge when to buy the sightstone though.
Comment: @maxywb the blue one is a good second item since it provides health and wards while the upgrade can be bought whenever you have spare gold and need more health.
Comment: @maxywb as for build order I usually go : gold item lv1 / sightstone / gold item lv2 / boots. Don't forget that sightstone is a kind of gold item as itself. I leave the sightstone upgrade for a later time.
Comment: @M'vy I usually prefer to get boots asap, imo movement speed is more important than saving gold.
Comment: @maxywb depends the champion you are playing (against?), but sightstone and gold item also bring better sustain. So between gold + sustain versus mobility, I chose the former.
Answer: This depends on what part of the game you're in.
During laning, if your ADC went back to heal or buy and won't make it back to lane in time to kill the current minion wave, then go ahead and last-hit those minions yourself. It's much better than wasting the gold. You can also leave lane briefly to ward nearby brushes and such to make your lane safer.
In the later game, your job is vision control. Make sure that you can see baron and dragon if they're close to coming back up, and that the enemy team can't. If you can, try to get vision a little bit past your safe front, so that you can see what the enemies are up to. Whenever your teammates aren't around to support, your job is to control vision (including denying your opponents' vision) without feeding the enemy team.
Comment: @maxywb: You should leave them to your jungler or carries most of the time. Exceptions are when they're all dead or you only need a few more creep kills for an important item.
Comment: Is it ever worth it to kill some jungle creeps, or should I leave those for others?
Comment: Normally, as a support it will take too long to kill jungle creeps when you should be doing other things (unless you manage to get fed early as an AP support)
Answer: I'm a main support player and I can tell you: there are times where you will seem "useless". But note the word seem. The supporter is arguably the best position in the team for awareness and play making. It's your job to keep an overview of the whole game since you are the one that only comes to action when you're about to kill something. Top/Mid and Adc will have to worry about CS while the jungler has to control his jungletimers and ganks (although the jungler is also very good at awareness).
Note also that there are 2 types of supporters:
As a harrassing supporter like Lulu/Annie/Thresh you will be focussing more on denying the enemy Adc farm or as already mentioned you try to harass him.
As a Passive or PassiveAggressive supporter you will either only safe the hp bar of your adc (Soraka/Sona) or in the case of an PassiveAggressive supporter you will only go in when You're about to make a kill or you gotta save someone (Leona/Blitzcrank/Alistar).
Keeping an eye on the map is of course easiest when playing as an Passive(Aggressive) Supporter, but this also includes the "I'm bored" or "I'm useless" moments.
For when your ADC backs off his lane you can go back aswell and spend your gold on wards/items, you can stay and CS so no creeps get lost or you can Gank other lanes. Since most supporters have really high amount of CC or Utility a gank can be fatal. Especially when combined with your jungler. A triple gank mid with Nocturne, Leona and Brand is really hard to survive unless everyone of these 3 misses their skillshots.
The ganking part can also be applied when your adc is really bad. If you think kills on your Adc will be useless since he can't position himself late just gank mid. Try to figure out who can carry this game.
Oh and last thing of course to do: Ward ward ward. One of your main jobs as a supporter (I don't like it either...)
Comment: Emphasis on the "as well". If you can save him but will die doing it, it's still worth it.
Comment: I've had bad luck abandoning my ADC to gank other lanes. I only play normals, and I don't ever go in with a friend who's ADCing, so ofttimes when I wander off to ward or whatever, my ADC gets rocked. I do my best to show my intent with smart pings and team chat, but it goes to show how important communication is.
Comment: Yeah it's also really important to know when to leave the lane. If  your lane opponend is a Blitzcrank and your Adc is Ashe you should try to stay with her as long as Blitz is on the lane. And by a "bad " Adc I mean someone that dies all the time and if you would try to save him it would just result in your death aswell^^
Comment: If you are going to gank mid as support, mobility boots are probably one of the early items you need to be grabbing.  Btw... Sona is most definitely not a passive support.  Her poke is extremely strong.  She should be harassing a lot.
Comment: You should change `PassiveAggressive` to `All In`. It makes much more sense.
Answer: This will depends the time of game mostly, and the situation.
ADC back, two enemies pushing. In this situation, you won't (most probably) be able to hold the lane alone. So either you hug tower and try to clear the wave as efficiently as possible (fast & with as many last hit as possible), or you can decide to back and leave it to the enemies. This decision should be weighted with the following questions: is the tower full life (can it take a few hits/will it fall no matter what I do?)? will they dive me and get a free kill? Can I clear the wave really quickly? Will I take advantage of shopping now? If you think you will get better advantage from going back home that leaving, do it.
ADC back, opponents back as well. Go shop! This is usually the time to get your items. If you don't have any gold, get the last hit and experience your AD won't have. You can also try to help the jungler if he's around, or getting counter jungled by warding stategic points like dragon, red/blue buff. If you feel confident you can get a decisive advantage, going for another lane and gank is a possibility as well.
If your AD backs with a full pushed lane, you probably want to go back as well, because you are basically a free kill.
The further the game goes, your actions should change. Still keep an eye for objectives, ward red, ward blue and your key spots. If you still have time, why not clear some unattended wave, or jungle camps. They respawn quickly enough not to hinder your jungler. Maybe it's a good time to start damaging blue/red for you carries. Beware of going warding alone, you always risk getting caught and get your team into trouble. Vision is important, but being alive is too. Always weight your decisions.

How To Fill My Down Time As Support


Do electromagnetic waves have endpoints?

Question: When learning about electromagnetic waves at school we never talked about any endpoints as we did with standing waves, so I assumed that light has an endless length, but that doesn't make sense. So my question is, does it make sense for em waves to have specific length? If yes, how does it differ from one to another?
Comment: A rock dropped into a pond. The resulting wave has a start and a dampened end. Two ends.
Answer: Standing waves on a string is just one of many examples of transverse waves! If you have seen pictures showing electric and magnetic fields oscillating perpendicularly, then you might come to the conclusion that they are like vibrating strings. The fact that must be made clear is that, there is no material medium needed for the EM Radiation to exist, unlike strings. This should tell you that, we must look at EM waves as distribution of energy in space rather than something oscillating(like a string), hence rendering the question of endpoints as non-existential. However, you can trap EM radiation in structures called as cavity resonators: http://en.wikipedia.org/wiki/Resonator#Cavity_resonators
or Waveguides: http://en.wikipedia.org/wiki/Waveguide_(electromagnetism)
Comment: Good question! In the classical version of EM theory, there were a few inconsistencies, questions like, what is the potential of an electron by itself(ideally, the theory predicts its infinite, as $r$ is zero, but there can never be infinite energy). To answer these inconsistencies Dirac and others developed a quantum mechanical version of EM Theory assuming that the energy packets of EM Field were photons.
Comment: But aren't photons supposed to be quantised! How are they distributed then?
Comment: The distribution of photons can be understood only quantum mechanically, by considering their bosonic nature. This was how Planck had produced a correct explanation for the blackbody problem
Comment: YOu must understand the difference between the Field version of EM and particle version/quantized version of EM.
Comment: Why would there be 2 versions of the same thing? Now it's very confusing.
Answer: The simple answer is by having a spread of frequencies / wavelengths in the EM field's spectrum it can be confined to a finite region. A perfectly monochromatic wave (i.e. one containing only one wavelength), whose electric field vector varies like $\cos(k\,z-\omega\,t)$ where $k = 2\pi/\lambda$ is the wavenumber and $\omega = 2 \pi f$ is the angular frequency has no "beginning or end" and would hold infinite energy. So the perfectly monochromatic wave is a theoretical abstraction used to simplify discussion.
Actually, this idea holds for all waves, even those standing waves on springs that you have experimented with. You actually have a forwards running and a backwards running wave - a mix of a positive wavelength and a negative one of exactly the same frequency magnitude such that the interference nulls the wave out at its endpoints, which are tethered to the experimental setup showing the standing wave. So a wave bouncing off two endpoints has a forward and backward component and looks the same between the endpoints as an infinite, lone-frequency wave with two components of equal amplitude running in opposite direction would look between the endpoint. So the fact of the nodes lets one kind of "excise" a finite section of the standing wave and keep it running. From the standpoint inside the cavity, there is no difference between the situation with tethered endpoints and one with two infinite waves.
You can do exactly the same thing with light in a resonant cavity. This is indeed what happens in a laser, which sets up a standing wave between two mirrors. You can also see this kind of thing happening if you stand between two mirrors and see a theoretically infinite number of copies of yourself. By dint of the virtual images, there is no difference between the light field making your image between the mirrors to a lightfield of infinite extent bearing an infinite number of images of you!
More generally, you think about how real waves have end points by thinking about Fourier transforms, which you will learn about after high school. But the basic idea is simple enough. First of all, any periodic function $f(t)$ such that $f(t) = f(t + T)$ where $T$ is the period can be "built" as a sum of functions of the form $\cos(2\pi\,n\, t/T)$ and $\sin(2\pi\,n\, t/T)$, where $n = 0, 1, 2, 3, \cdots$. So it can be built of sines and cosines with the same frequency as well as their higher harmonics. This is a Fourier series. To go forward to the Fourier transform, we simply let the period $T$ get bigger and bigger so that in the limit it comprises the whole real line and thus any reasonable function can be built of monochromatic waves with a spread of periods. To build a short pulse, the Fourier transform adds together a wide frequency spread, so that there is strong destructive interference between the monochromatic components aside from near where they are all perfectly lined up in phase, i.e. near the pulse.
The shorter the pulse, the wider the spread of frequencies needed.
This may sound familiar from your quantum mechanics research: it is the underlying mechanism of the uncertainty principle. It turns out that to express a function in momentum co-ordinates, you take the function expressed in position co-ordinates and take its Fourier transform. And contrawise. So if the function is perfectly monochromatic - of the form $\cos(\omega t)$$ - so it has perfectly known momentum, it is uniformly spread over with real line and its location in position co-ordinates is altogether uncertain. The formal statement of the uncertainty principle follows from the "wide spread in frequency means a narrow spread in time/space and contrawise" property of the Fourier transform.
Answer: As pointed out in the other answers, electromagnetic waves can be spatially confined in a variety of ways, but perhaps more fundamental is how electromagnetic waves can be confined temporally.
Electromagnetic radiation is changes in the electromagnetic field propagating through space. If you imagine a point charge emanating electric field lines, then when that point charge moves to another location the electric field lines must now emanate from that location. However, information about the new configuration of the field can only travel at the speed of light, so the motion of the point charge translates into a disturbance in the field that propagates away from the point charge at the speed of light.
This disturbance is an electromagnetic wave, electromagnetic radiation.
Therefore, the endpoints of such a wave are defined by the beginning and the end of the propagating disturbance. If the charge only moves once, the wave will be very short. If the charge is attached to a motor the pushes it back and forth indefinitely, then the wave will have an end point at wherever the wave front of the disturbance is, and it will also have a sort of end point at the charge itself (which produces the wave by constantly moving its location and thus changing the nearby electromagnetic field).


How can you show additional information in a pop up

Question: I'm designing this popup for a mobile website where a single input needs to be added. the user might need some additional information to help them with this input (e.g. the serial number is visible at the bottom of your product). This will be an image and i've come up with the following solution. This might seem slightly unconventional and i'd be grateful if you could suggest a better way of doing this
Answer: As shown in your wireframe, you have a single entry field and a single interaction on that screen.
Without having more details than that, I probably wouldn't hide that "extra information" at all. The user can hardly get lost on this screen, because it is so simple. Just keep the image content simple and the graphic style "non-overwhelming" ;) in terms of coloration and detail.
That would instantly address the rule of not hiding meaningful information from the user, and it would do so without jeopardizing the form's overall usability.
Answer: First, make your Extra info text more clear as to what info it is. You can use a descriptive label to explain what the extra info is. Something like, "Can't find your serial number?" or "Locate your serial number". Then place the help text next to the label.
Then, instead of having the popup slide down at the bottom, you can have it open centered with a close button on the top right. This way, you will capture the attention of users and prevent them from scrolling down.
See mockup:
Comment: Thank you for your answer, but having a popup over a popup isn't a good practice. Looking for a solution without having an additional popup overlaying.
Answer: Don't hide info on mobile or anywhere.
Why cannot you ask serial number without popup? It seems serial number is part of a workflow to complete the process. It is a conditional fields I guess which can be invoked on page the itself by show/hide logic. Isn't it?
If you're still up for popup, 'Extra info section' can be a open section and let user scroll if they want. Make sure you work on copy so that no gibberish information is there.
Lastly, let user scroll  only content section not the complete popup.


From a bare minimum Ubuntu to something like an AWS Ubuntu standard image

Question: If I am given a bare minimum ubuntu machine in a private cloud environment with almost nothing installed on it(not even apt-get and ubuntu repositories configured) and the only user is root, what are the set of commands to run to turn this machine as configured as an ec2 standard ubuntu 12.04 image? One can find these commands here and there but I am looking for something that induces all I need to run to have a properly configuration machine as good as the amazon ubuntu ami.
Comment: Do you have access to the coreutils? wget, and such? what commands are actually available?
Answer: That is a tough one. I can not provide "the set of commands", but describe how I would approach this task.
.deb packages have priority's. Most of the packages have the priority optional, but the ones that are interesting here are the packages with required, important and standard priority. Those are the ones that are usually installed on every system. apt-get is one of them. You could scan the Packages file of the main repository for a list of all packages that are required and important priority, download all the .deb files and install them with dpkg -i. (I sincerely hope you do not have to bootstrap dpkg!) Then you should have a functional apt system. Then you should be able to use aptitude in order to install all standard packages. Done that you could install the task server with tasksel.
Packages file for amd64
Good luck


Where could i find the intended travel for my specific mtb suspension forks

Question: I have a Akela forged CR-MO mtb suspension fork that im trying to find the specs for. I'm building a bicycle for the first time and need forks for it. I have a few forks laying around. I know the amount of travel meant for my bike frame buy I can't find any source on how or where to find out what the travel is on any of my forks to know if they are compatible or not. Any suggestions?
Comment: Can't you just measure the distance between the bottom of the crown and top of the lower?  Might not be 100% accurate, but probably close enough for tolerance
Answer: Measure the fork's axle to crown dimension in uncompressed state, and then in fully compressed state. The difference is the travel.
Usually the practical way of doing this is to measure the length of the exposed stanchion when the fork is uncompressed, and then again when fully compressed. It can be a little clumsy, but you're typically only trying to figure out what travel "class" it falls in, eg 120, 100, 80, etc, so precision doesn't matter much.
Some frame specs use the uncompressed axle to crown as the number, not travel per se. Sometimes this is also known as "fork length."


How to insert the file path as a function parameter in RainTPL template engine

Question: I don't know what can I do it.
I have a structure function as like the following:
Example: (PHP)
function func($file_path){
  // my code
return array;
}

I want to use the previous function in my template file, but the problem in $file_path parameter, I done the following in my template file:
Example (Template File)
{loop name="Pics"}
  {if="$value.pic_id == $picID"}
     {$uploadFolder}/{$value.pic_name | func}
  {/if}
{/loop}

Note:
$uploadFolder is a folder contain files, and value.pic_name is the file name
Now when implement this code occurs the following problem:

failed to open stream: No such file or directory .

As we see the reason behind that problem is the function parameter does not work fine.
I'm sure the problem inside this area.
{$uploadFolder}/{$value.pic_name | func}

Can anybody help me please ?
Answer: You can do it like this. It is simple and read the documentation so that it will becleared to you.
RainTPL::base_url['path'];


How to put a trailer clip in the middle of the main video with FFMPEG?

Question: I have two videos of the same format encoded with the same codecs. I want trailer.mkv to be played after n minutes in the middle of main.mkv. After playing trailer.mkv, the rest of the main.mkv will continue playing. How can I concatenate them?
Answer: I know how to do it in three steps.
Separate your main video.
Step 1. Trim the end.
ffmpeg -i main.mkv -c copy -t 00:02:00 main-intro.mkv
Step 2. Trim the start.
ffmpeg -i main.mkv -c copy -ss 00:02:00 main-outro.mkv
Step 3. Concatenate them with your trailer file.
ffmpeg -safe 0 -i "concat:main-intro.mkv|trailer.mkv|main-outro.mkv" -c copy output.mkv
You can write script and you will have opportunity to do it in one click.


What is the temperature inside a Black Hole?

Question:
Is it insanely hot? Cause of so much gravity?
Is it close to absolute zero? Cause the matter is so closely packed, there is hardly any space for particles to move?
Is it room temperature? Cause Cooper didn't die in Interstellar when he went into a Black Hole?
Comment: 1) We don't know anything about what's in a black hole. 2) Don't think that everything in *Interstellar* is scientifically correct or even plausible.
Comment: Interstellar reference was a joke!!
Comment: Inside ... we don't know. But we might be able to assign a temp to the event horizon using "black hole thermodynamics" http://en.wikipedia.org/wiki/Black_hole_thermodynamics
Comment: It might depend where inside the black hole.  It's possible that after falling inside a supermassive black hole you wouldn't even notice the event horizon and the inside might be similar to empty space.   It's also possible that the massive gravity stretches and tears space time so much that there's some exotic things going on.   It's also possible that inside the black hole is an infinitely dense singularity.   Densely packed particles tend to be hotter not colder, but packed into a singularity, temperature doesn't make sense.   I think, "we don't know" is the best answer.  Fun question.
Comment: @userLTK Thank you for the explanation, sir/madam.
Answer: The temperature of a black hole as seen from the outside is the temperature of the Hawking radiation, which @jyoti has discussed.
The temperature you would experience as you fell freely through the event horizon, is a different question. I think the answer depends on what else is falling into the black hole at the same time. From its own viewpoint, everything that falls into a black hole reaches the singularity in a fixed maximum time (a few days for the very largest supermassive black holes) so you could only exchange energy with things that fell in around the same time as you did. If there was very little such stuff, then I don't think you'd notice anything out of the ordinary -- you'd be exposed to the cold of space, just as you were before (assuming the black hole is big enough that you haven't been heated up the tides of the black hole distorting you. On the other hand if lots of stuff was falling into the black hole with you then the whole lot would get churned up, and you'd be falling in as part of a mass of very hot plasma. Eventually, at least in a non-spinning black hole, you'd approach the singularity and be ripped apart by tides.
Answer: The temperature of radiation emitted by a static black hole (without an accretion disc) is from pair production.  The black hole loses mass when a virtual (negative-energy) particle-antiparticle pair forms exactly on the event horizon.  One of the virtual particles falls into the black hole, separating the pair.  The other particle becomes real and is emitted as positive mass-energy, and the particle that falls into the singularity remains virtual as negative mass-energy.  The net result is that mass-energy conservation is preserved, and the black hole loses mass-energy by emitting a real particle.  Since the escape velocity below the event horizon is beyond the speed of light, any particles created inside the black hole (real or otherwise) would always immediately fall into the singularity.  So if you were able to safely cross the event horizon (which is speculative—some recent studies have hypothesized that there many be "wall of fire" at the event horizon), I would think that you should only be able to register absolute zero, with the exception of any incoming radiation raining down from above you.  The virtual negative-mass component of Hawking radiation should presumably be undetectable, and even if it was, it would register as being below absolute zero, in violation of thermodynamics (and energy conservation).  Note though that the "temperature" of the singularity itself can be thought of as being measured in Planck temperatures (10^32 kelvins), since spacetime breaks down at that point (the Planck scale of M-theory, where one Planck temperature is the equivalent of one Planck energy, or the Planck mass).
Comment: https://www.quantamagazine.org/black-hole-echoes-would-reveal-break-with-einsteins-theory-20180322/
Comment: https://www.quantamagazine.org/black-hole-firewalls-confound-theoretical-physicists-20121221/
Comment: https://en.wikipedia.org/wiki/Firewall_(physics)
Answer: Temperature of a black hole is determined by 'black body radiation temperature' of radiation which comes from it (if something is hot enough to give off bright blue light,it is hotter than something that is merely a dim red hot.) For black holes the mass of Sun, radiation emitted from it is so weak and so cool that temperature is only one-millionth of a degree above absolute zero. some black holes are thought to weigh a billion times as much as the Sun and they would be a billion times colder, far colder than what scientists have achieved on Earth.
Even though these things are very cold, they can be surrounded by very hot material. As they pull gas and stars down into their gravity wells, material rubs against itself at a good fraction of speed of light. this heats it up to hundreds of millions of degrees. Radiation from this hot, in-falling material is what high-energy astronomers study.
A black hole behaves as though its horizon has a temperature and that temperature is inversely proportional to the hole's mass: T = (6 x 10^-8)M. Here M is in units of solar mass (2 x 1033 grams). Temperature is in degrees Kelvin.
This means that a hole recently formed by gravitational collapse of a star (which has to have a mass larger than about 2 suns) has a temperature less than 3 x 10^-8 centigrade above absolute zero which is very cold.
Mass with a finite temperature radiated energy. Anything which radiates energy is also losing mass.As black hole loses mass, emission of energy from black hole increases and its temperature increases and thus rate of mass loss increases.As mass of black hole gets small,one has unstable 'runaway effect'. Black hole gets hotter and hotter which causes M to decrease rapidly.When the hole is reduced to a fraction of the size of an atomic nucleus, it will be trillions of degrees. Hole will burn up and disappear. Lifetime of a black hole is greater than age of the universe.
Comment: The question was: What is the temperature _inside_ a Black Hole?
Comment: Googling for "For black holes the mass of Sun, radiation emitted from it is so weak and so cool that temperature is only one-millionth of a degree above absolute zero" yields a boatload of other hits. Care to name your source for proper attribution?
Comment: I agree with Christian. Could you please cite your sources? Thanks.
Comment: The nucleus of an atom is not a black hole, which suggests that a black hole that evaporates to the mass of a nucleus of an atom would cease to be a black hole.
Answer:
What is the temperature inside a Black Hole?

Absolute zero. That's because of the infinite gravitational time dilation. Temperature is a measure of motion of sorts. Gravitational time dilation means things are moving slower. When the gravitational time dilation goes infinite there is no motion, and so no temperature. This is why the black hole was originally known as the frozen star. See the 1939 paper by Robert Oppenheimer and Hartland Snyder on continued gravitational contraction. People often say this is outdated, see for example Brown's mathpages article the formation and growth of black holes, but I don't think it is. I say that because I've read the Einstein digital papers, and I like to think I know how gravity works.
Regardless of that, in 1972 Stephen Hawking, Brandon Carter, and Jim Bardeen wrote a paper and said "the effective temperature of a black hole is absolute zero". Robert Wald said much the same in black hole physics: "κ has nothing whatever to do with the physical temperature of a black hole, which is absolute zero by any reasonable criteria".  Note that Hawking radiation is nothing to do with the temperature inside a black hole.

Is it insanely hot? Cause of so much gravity?

No. Or should I say I don't think so. I don't actually know for certain.

Is it close to absolute zero? Cause the matter is so closely packed, there is hardly any space for particles to move?

Yes AFAIK it's close to absolute zero. Or it's actually absolute zero. But not because matter is so closely packed. In fact there might not even be any particles inside a black hole.

Is it room temperature? Cause Cooper didn't die in Interstellar when he went into a Black Hole?

No, it isn't room temperature. Interstellar is just science fiction I'm afraid, even though it was portrayed as science fact.
Comment: Time dilation is relative.    I'll admit that the time dilation inside a black hole makes my head hurt when thinking about it, but time feels normal from any individual's perspective, so time dilation won't change local temperature.    There's always going to be motion at the local level, whether that motion is at 100% time dilation relative to outside doesn't make the temperature absolute zero from the local perspective.
Comment: @userLTK : If there was motion at the local level your gedanken observer could point his torch upwards and turn it on. But the black hole is black, so there's clearly an issue with that. IMHO the best way to think about it is that there isn't any local perspective when time dilation goes infinite.
Comment: Sure, from the outside, but this question is about theoretical temperature on the inside.   But that's not really the point.   Are we discussing temperature and shouldn't temperature be measured locally?   Locally the "infinite time dilation" is irrelevant.


Restful_authentication vs. Authlogic

Question: what do you recommend?
Authlogic or restful_authentication?
Is it hard, to build the email-activation-step into authlogic
(as far as I know, Authlogic hasn't this feature included).
Answer: Actually I'd disagree with fig-gnuton.  There are a couple of things that you could do.  If you want a basic solution try restful auth but be aware that the generator based approach has significant shortcomings.  The main shortcoming is that you are squirting a large gob of code into your application.  So when there's an issue you have to patch the code manually or blow away any customisations you've made.  Recent versions of restful auth are much better than earlier versions which spewed code left, right and centre but my advice would be where possible leave the user and session code generated by restful auth well alone.  For example  if you want properties on your User make another object like Person and link the two.
I prefer authlogic because:

It feels like you're more in control.
I appreciate the extent to which authlogic is documented and their example app is pretty useful as a guide too.
Also I've had bother with testing restful_auth apps, not so with authlogic.
Extensions like forgotten password resets, API keys and the like are much less custom code than restful_auth.
Answer: And don't forget Clearance, the other kid in the block.
Answer: Restful Authentication is crap. It's the kind of thing that gives Rails generators a bad name.
What do I mean by that? The generators that come with Rails are (IMHO) good. They generate a very minimalistic skeletal structure. What they generate is small, easily understood, and easy added to/replaced by your own code as you go. All the complex gnarly pieces are in the Rails libraries, where they belong, not in the generated code.
Restful Authentication, on the other hand, comes with generators that spew out massive amounts of generated code that's hard to work with and hard to maintain. Functionality that should be in a nice library where it can be easily upgrade with each new version of the framework is instead spewed out in generated model and controller code where it'll end up intermixed with your code. It's not scaffolding, it's a mass one way dump of autogenerated code.
Stay away... stay far away....
Answer: You're better off with authlogic.
take a look at my reasoning here
http://blog.platform45.com/2009/09/30/user-authentication-with-authlogic
Answer: Restful_Auth is a drop-in solution.
Authlogic is great and can do anything restful_auth can do (and more, afaik), but Authlogic is geared to customization, it therefore lacks the generator aspect (by design rather than oversight).
Bottom line, if you're a newbie (sounds like you might be), I'd start with restful_auth.

Restful_authentication vs. Authlogic


Adobe Photoshop - How do you arithmetically add two images?

Question: For example, if two grayscale images, one with a intensity and the other with b intensity, are added the resultant image should be of a + b intensity.
Comment: @joojaa, the only clean add operation is linear dodge. Linear light does add, but also subtracts, which is why it's grouped with "Overlay". You can see an important use of linear light blending here: http://creativepro.com/article/frequency-separation-retouching-photoshop
Comment: linear light is an add operation
Comment: What about the `Screen` or `Multiply` blending modes does not fit your needs?
Comment: @AlanGilbertson Ah sorry yes remembered wrong dodge it is, now that i have ps in front of me
Comment: @joojaa I've never done that (ha! I wish...). It was a coincidence that I'd written that linked article just last week. Frequency separation retouching is the only technique I've come across that explicitly requires Linear Light, so it was fresh in my mind.
Comment: @AlanGilbertson yes that's because light is a additive process you can also sue this to add 2 different lighting conditions of a photo shoot together and recolor lights in PS. Frequency separation is one good use tough. But thst what signal processing is for.
Comment: To be clear: if you were combining a pixel that's 50% gray with another pixel that's 50% gray, you'd want the result to be white?  And you'd want a white pixel combined with anything else to result in a white pixel?
Answer: As with almost anything in Photoshop, there are several ways to do this, depending on what fits your needs and your workflow.
Among the Blend modes, Add is called "Linear Dodge". It says that, in fact, right in the menu. You can, therefore, place your images one above the other and apply Linear Dodge to the upper one. All of the "Lighten" Blend Mode group are variations of Add, but Linear Dodge is a straight arithmetic operation. All of the calculations involved in the different blend modes are documented here.
If you are specifically looking for grayscale output, Calculations (Image > Calculations) has been around since the Pharaohs, or thereabouts. This allows you to (among many other things) Add two channels to create either a new channel or a new grayscale document. This works across images, not just with layers. The two images must have exactly the same size pixel dimensions.
Calculations is unique in that it can take the gray values of an RGB image and blend them with the gray values of another RGB image to produce a grayscale output.
Another that's been around since Noah is Apply Image. Once again, Image > Apply Image can be used with two channels in one document, a channel with the RGB composite "channel" of the same document, or either of those across two documents of the same dimensions. It's different from Calculations because it does not create a new channel or document, and its output will be in a color mode if applied to a color composite.
Comment: You can also do this with masks etc. but i think 3 ways is good enough.
Comment: The rest, as they say, is left as an exercise for the reader... (Calculations or Apply Image rock for creating masks.)
Comment: @AlanGilbertson this is what I needed. Thanks.
Answer: If you have two grayscale images, then multiply will do the trick. Except you should understand, that there is a limit to that. Max intensity is 255, so if on first layer intensity is 150 and on second the same, resulting intensity will be only 255, not 300, because it's technically impossible.
Comment: Multiply is a multiplication operation, not addition. When image values are added, the image becomes lighter. Multiply *always* results in a darker image unless the layer is pure white or pure black.
Comment: Um, no. The question is "how do you arithmetically add two images". Intensity could have a variety of meanings in this context, but since the OP is a Stack Overflow and SU user, he's probably a developer. I'm willing to bet he means exactly what the question says.
Comment: Intensity could mean highlights, contrast, shadows, or gamma depending on what you're trying to achieve.
Comment: @mrserge you mean addition result more than 255 truncating to 255? I know that. :) Thanks.
Comment: Question was about calculating sum of two image intensity, in this case multiply is the best choice.
Comment: Tell me more than one meaning for intensity in case of two grayscale images? What else than amount of gray can be ment as intensity? Not bulling, I really can't understand your point.
Comment: @AlabGilbertson Yup, I am a developer. Nice guess. :3
Comment: @mserge I wanted clean add operation. Multiply wouldn't do the trick.
Comment: Good. Still don't forget that math with 255 shades apply to you also with this operator.


Not planned work emerges during the sprint from management?

Question: I believe that most of us have encountered this situation. What is the best approach when higher management or client is forcing the PO to include some new functionality in the middle of the sprint, something that is not planned and team did on commit on that?
Answer: Just make sure to create a story for the ad hoc work and assign points to it before adopting it into the current sprint as an expedite issue. This way you will maintain velocity. If you had other sprint goals, these will just move to the next sprint.
There is not really a problem here. You can push back a bit though and let them explain why this cannot wait until the next sprint, tell them that it would be more convenient to make it a regular sprint item because you are in the middle of something and these panic assignments are a bit disruptive. Why was this not anticipated? Was someone taken by surprise? If so, why? Can we help to prevent this in the future? Good stuff for the next review/retro/demo.
Comment: @DarkKnightSM Can't you just say "will do" and smile and put it on the backlog for the next sprint? The questions I raised are all for you to ask your stake holders. Reserving time in the sprint for ad hoc work is not right. That is not planning. You should plan for proper stories only and if something breaks the sprint, so be it.
Comment: yes, we try to push it back but the problem lies in the fact that i don't think our clients are familiar with scrum framework and its guidelines. For the question regarding why this is not anticipated, we leave buffer on the sprint planning for this moments, however this conflicts with our goal and with the team atmosphere.
Comment: @DarkKnightSM: *"i don't think our clients are familiar with scrum framework and its guidelines"* - yes, and you should not expect them to get familiar with it. Don't use Scrum terms when talking to the client - translate them to a language they understand. For example, don't ask why this "cannot wait until the next sprint", ask them "why this cannot wait for the next two weeks" (or whatever your timeframe is here).
Answer: In the simplest terms possible, when new work is added to the sprint, some work already in the sprint needs to be taken out. Take the work that was added, do your best to give it an appropriate amount of story points, and then remove that amount of story points from the sprint backlog.
Depending on the size of the request, this can probably happen without too much disruption: just take one story card off of the board and replace it with the new one. However, if they are asking you to make very big changes may require cancelling the sprint and starting over with a new sprint planning session. This has a pretty big cost associated with it, so it's not something you should normally do.
The Scrum Guide has this to say about cancelling a sprint:

A Sprint can be cancelled before the Sprint time-box is over. Only the Product Owner has the authority to cancel the Sprint, although he or she may do so under influence from the stakeholders, the Development Team, or the Scrum Master.
A Sprint would be cancelled if the Sprint Goal becomes obsolete. This might occur if the company changes direction or if market or technology conditions change. In general, a Sprint should be cancelled if it no longer makes sense given the circumstances. But, due to the short duration of Sprints, cancellation rarely makes sense.
Comment: @ThomasOwens: I agree. That's part of why I mentioned big costs associated with cancelling a sprint. For a team working in isolation it might be a minor headache, for a product team made up of many interdependent teams working toward a common release date it could be catastrophic.
Comment: The only thing that I'd note is that cancelling Sprints may not make sense in situations where there are multiple teams. A good practice is to reduce dependencies between teams, this isn't always possible. If one team is dependent on another team, a canceled Sprint could have ripple effects. It may be better to continue on cadence and ensure a stable product at the end of the Sprint rather than abnormal termination.
Comment: This is the answer which makes most sense to me. However, one should add that "cancelling a sprint" does not necessarily mean to throw away the work which was already done during the current sprint. Instead, the current work can stay in source control (in some unmerged branches) or in source (hidden behind some feature toggle), so the team can continue with that version of the code in a new sprint after the "top-priority feature" sprint is completed. So instead of "cancelling" a sprint, I would suggest to use the term "freeze" instead.
Answer: The contents of a Sprint are not necessarily fixed at the end of Sprint Planning. Based on what the team knows about their capacity and ability to do the work, they have selected items and chosen a Sprint Goal that the Development Team feels is achievable and the Product Owner feels is appropriate to deliver at or before the end of the Sprint timebox.
In an ideal world, the Sprint contents are fixed. However, as you're experiencing now, the world isn't ideal.
If the Sprint Goal has become entirely obsolete due to changing circumstances, Scrum allows for the cancellation of a Sprint. However, this is often a last-resort effort. In addition, in a scaled environment with multiple teams, one team cancelling their Sprint is often not an option.
If the Sprint Goal is generally intact still, the Product Owner and the Development Team can work together to assess the size and scope of the proposed changes and determine if it can be done in the Sprint. Perhaps work that is not yet started can be swapped out for the new work and the work can be delivered at the end of the Sprint. Or perhaps it's too late in the Sprint and the proposed work can become part of the next Sprint.
If the work does become part of the next Sprint, the team can produce an increment at any point in the Sprint and may produce multiple product increments. The only requirement is that, at the end of the timebox and going into the Sprint Review and Sprint Retrospective events, the team has a product increment that meets the team's Definition of Done.
More broadly speaking, the Scrum Master should be coaching not only the team, but other stakeholders, on the principles and practices of Scrum. If the issue is not truly urgent, then it should be possible to wait one or two Sprints to get it. If that's too long, then there may be other things to look at, such as the length of the Sprint with respect to delivering value to stakeholders.
Comment: @DarkKnightSM Scrum is a product development and delivery framework. Ideally, each Scrum Team is focused on a single product. If that's not the case, then Scrum may not be the best fit for you. But that doesn't mean that you can't take elements of Scrum to help build a good methodology for your team and organization.
Comment: thanks, Thomas. I agree, we need to look after over Sprint Goal and decide if something that needs to be done in the sprint has the common value of our goal. So, what you are saying is that team needs to deliver product increment, if not, we are not doing our job properly?
Comment: @DarkKnightSM If you aren't delivering a working [increment](https://www.scrumguides.org/scrum-guide.html#artifacts-increment) at least at the end of the Sprint, you aren't doing Scrum. Your increment could reach a "done" state before the end of the Sprint, or you could have multiple increments. But the "done" increment is a key component of Scrum.
Comment: yes, of course. What worries me is that my team is working on multiple projects, so ''done'' increment is sometimes a bug fix on production, sometimes is something that team develops during the sprint, it's a mix of different things, not one project, unfortunately.
Comment: Thomas, can Scrumban be a better solution? I read about it, it feels like a better solution, mix of kanban and scrum, did you encounter it?
Comment: @DarkKnightSM Without understanding your organization and its constraints, I can't recommend a framework as a starting point. But many of the frameworks are centered around the idea of products and dedicated teams, so if you have a single team supporting multiple products, you'll have to do a lot of learning on your own.
Comment: yes, thanks Thomas for your feedback.
Answer: Highlight the downside.

Something else is being delayed
If work already started on that thing then there will be lost time/wasted effort.

But then look at what your are asking from the business

Changes can't be implemented untill at least 1 sprint after they are thought of.
That means 2 sprints before delivery on even a 'small' task.

If the stakeholders like to tweak stuff its not really feasible to have a sprint longer than 1 week.
People accept "we can start than next week and have it to you at the end of that week"
But "we can start that next month and give you it a month after that" is basically a no.
Comment: Ok, so you propose that if we a lot of things coming during the sprint, we should maybe consider a one week sprint?
Comment: no. I suggest _always_ doing 1 week sprints.
Answer:
Do the work. Management and/or the client pay the bills, so the bottom line is they get to decide what to do.
In the retrospective, note that you didn't hit your sprint goals because of the unplanned changes.
If this happens on more than one sprint, escalate the issue.

Note that you can't just as a development team say "we're doing sprints now" - you have to have buy-in from your customers. If you don't have that buy-in, you either need to get it or work with your customers to create a development process they are happy with.
Comment: yes, they pay the bills, so we need to do the work. But, does that mean when that happens, we need to remove something from the sprint? And if that happens too often, how would you escalate it? Thanks!
Comment: @DarkKnightSM I too would do the work, but have a conversation with the person changing the priority. Make them decide what's NOT getting done because the team is working on this new thing. Team capacity to do work doesn't change just because the priority has changed.
Comment: @DarkKnightSM  Without knowing more, I assume that the unplanned work is of the scope creep variety (as opposed to fixing a showstopper bug).  Yes, you will need to drop something from the current sprint (postpone that until the next sprint).  Ask your customers to choose what they are willing to drop from current sprint.  Explain to them that changing priorities in the middle of a sprint is disruptive for your team.  If this become a pattern (they force scope creep in the middle of every other sprint) then wait until QBR and raise the price.
Comment: thank you for the answers. Yes, i am trying to communicate with the team and management that we need to drop something due to scope change in the middle of the sprint. However, i still don't know how to maintain team's spirit during the sprint because this is frustrating when you need to do this every single sprint. Maybe scrum is not for us, maybe Kanban?
Answer: One of the big benefits of scrum is

transparency (cost and time when features will be done)
keeping the developteam productivity (aka velocity) high by protecting it from interuptions in the current sprint like "we should add this unplanned feature as soon as possible" This would become a "add this new feature in the next sprint"

If a feature is so important that it cannot wait until next sprint you loose some of the scrum benefits (transparency and/or productivity)
possible strategies:

estimate new feature
replace not-started-yet-ticket from current sprint which has similar effort as the new one if possible
if not possible stop current sprint immediately and start a new sprintplanning and donot forget to estimate the extra costs/delays caused by interruptions and later-resume

Management has to learn that ad-hoc changes come at a cost.
One of the beauties of scrum is that waiting for the next sprint has no additional costs.


how can i run cakephp website without app name in url?

Question: I have two app in cakephp2.1.3 vesion, one is admin and second is web, I want to run my website without my app name  like without 'web', current website url is 'http://localhost/cakephp2.1.3/web/customers/index' but i need to access using 'http://localhost/cakephp2.1.3/customers/index'.
My current .htaccess is
<IfModule mod_rewrite.c>
    RewriteEngine on
    RewriteRule ^admin/$ admin/webroot/ [L]
    RewriteRule ^$ web/webroot/ [L]
    RewriteRule (.*) web/webroot/$1 [L]
</IfModule>

and i have just change outer index.php
define('APP_DIR', 'web');

When i try to access 'http://localhost/cakephp2.1.3/customers/index' it gives error
Error: Cakephp-2.1.3Controller could not be found.
Error: Create the class Cakephp-2.1.3Controller below in file: web\Controller\Cakephp-2.1.3Controller.php

Answer: Assuming you cannot add a new domain and a new VirtualHost, look into apache's mod_alias that can map a url to a (different) filesystem location.
In your case you'll need something like this:
Alias /cakephp2.1.3 /cakephp2.1.3/web/

Comment: thats fine, but i also need it, when i go for live on my particular domain. then how can i run my website without 'web'?
Comment: You can configure apache the same way (assuming you're using apache there too).


How can I turn ON the power to a utility pump if water is sensed?

Question: I have a utility pump I leave on the floor of an area that sometimes gets a few inches of water. Right now I have to turn it on manually. I'm looking far a sensor that will turn the power ON when water is detected. There are plenty that will turn power off but that's not what I need. Thanks.
Comment: A float type switch should work.  Water raises float to on position and off when water drops.  Most sump pumps come with this type of switch, so they are automatic.
Comment: Do a search for "sump float switch".
Answer: They make pre-made consumer products specifically for this, that are approved as a complete package, and work reliably, and don't require any kitbuilding or hardware hacking.  They are called sump pumps.
The key to success of a sump pump is to have what you should have anyway: a sump.  A small hole at the lowest point where water tends to collect.   The sump can also have drain pipes added to collect water from other areas of the floor and piped into the sump.
The hole will have some depth of water in it before the floor has any depth of water.   That gives the sump pump an advantage, as it can wait until there is some depth of water before starting up, i.e. making it worth running for.
The sump only needs to be large enough to fit the sump pump inlet and float. However, the larger and deeper it is, the less often the sump pump will run.
Answer: I bought a utility from either Home Depot or Lowes, I do not remember which store but they both sell similar products, that will turn on at about 1-3/8" and turn off at 1/4" of water. The pump is a Utilitech model 0435062. It also has hook-ups to  different size hoses. Check it out. This may be what you are looking for.
Comment: Just what I needed. Thanks for the lead. This specific model is no longer available but I found this one that looks pretty good: Wayne 57729-WYN1 EEAUP250 1/4 HP Automatic ON/OFF Electric Water Removal Pump


Why is the internal energy discontinuous in a first-order phase transition?

Question: Using the Ehernfest classification where first order phase transitions are those where the 1st derivative of the free energy has a discontinuity, I can follow why the entropy and volume are discontinuous $S=-\frac{\partial G}{\partial T}$ & ${V}=\frac{\partial {G}}{\partial P}$. However it is not to clear to me what relationship results in the discontinuity for the internal energy.
Comment: Please clarify what type of explanation you're looking for. It takes energy (termed latent heat) to break bonds. All of this energy needs to supplied essentially in lumped form to turn the lower-temperature phase into the higher-temperature phase. Is this what you're asking about?
Comment: I'm confused on how the condition that the first derivatives of the Gibbs free energy are discontinuous leads to the result that the internal energy is also discontinuous.
Answer: Once we have a closed thermodynamic system having a discontinuity of the first derivatives of the Gibbs free energy $G$ as a function of temperature and pressure, the discontinuity of the internal energy $U$ as a function of the same variables is a trivial consequence of the relation between $G$ and $U$:
$$
U(T,p)=G(T,p)+TS(T,p)-pV(T,p)
$$
$G(T,p)$ is a continuous function of the variables $T$ and $p$ (it is a consequence of its concavity). Therefore, the discontinuities of $S$ and $V$ imply the discontinuity of $U(T, p)$.
Notice that the functional dependence on $p$ and $T$ is essential. The internal energy, as a function of $S$ and $V$, is continuous. A  rarely stressed side remark on Ehrenfest classification is that it is based on the order of derivatives of a thermodynamic potential as a function of the intensive variables only.


How to relocate boxer dog from Europe (Belgrade,Serbia) to US (Atlanta, Georgia)?

Question: I might be moving to US Atlanta Georgia with my boxer dog. I am trying to prepare and learn the risks as she will have to travel in the cargo area. Found some articles about Lufthansa being one of most caring companies, but I was hoping to hear experiences, positive or negative, if this can be done?
Comment: Please rephrase and repost your question. 1) It belongs on [expatriates.se]. 2) Do not ask for *experiences, positive or negative*. That is too broad and opinion based. What is the *specific question* that you have that is not already answered in the *some articles about Lufthansa*?
Comment: I don't know your sources but based on 2 intercontinental LH moves [Europe-Asia] both with 2 dogs [one in cargo; she has a "long nose", though], strongly recommend LH [I have no other relationship with LH than being their customer. Made Stop-over in FRA just to get LH]. Maybe since LH is used to dogs, but [quote from my earlier comment on a similar question, about the dog in cargo]: "The cabin crew was professional about dog travel! On board before taxing they told me they checked the she was aboard. During the flight they frequently went to check that she was fine, and kept me up-to-date"
Answer: I can't comment on the service but I can confirm that dogs weighing more than 8 KG including the transport container can be transported in the cargo hold under certain conditions:

Dogs and cats that weigh more than 8 kg including their transport container, as well as hares and rabbits, may be transported under certain conditions as excess baggage in the aircraft's air-conditioned cargo hold.

(Source)


Sending a Bitcoin (BTC) to a Bitcoin Cash (BCH, aka BCC) address in Kraken exch. without receiving the private key?

Question: Why cant Kraken simply receive full access to Alice account which she is willing to give. Kraken does not have to give Alice the private key. Kraken can create a wallet if that is really necessary or use a wallet that is already created which they have full access too, send the bitcoin to the wallet and then send it from the wallet to Alice BTC deposit account, give the Admin of Alice's Kraken account back to Alice's, therefore, No private key was given to Alice, security is still fully secure, Alice has the Bitcoin in her BTC account now. Alice pays Kraken for there services. Kraken is happy, Alice is happy. Why is this plan difficult?
Comment: Your question is very unclear. Can you please make it easier to read and understand what you are actually asking? What service is kraken providing? For what coin?
Comment: This question is referring to if you send a bitcoin from your wallet, accidentally to your BCH/BCC deposit address instead of your BTC deposit address in your Kraken account. how can you get Kraken to help you retrieve it without having them to give you the private key?
Answer: Basically they don't have enough staff with security clearance to handle manual cross-chain recoveries. So only substantial amount will be considered.

It is Kraken's policy not to engage in efforts of recovery where BCH
  is sent to an XBT address or XBT is sent to a BCH address. Our last
  three blog posts have emphasized this point. Also, as you said,
  recovering your XBT funds will require manually handling the private
  keys associated to your BCH deposit address. Kraken has extensive
  security policies and procedures in place to ensure the safety of our
  customers' and our own funds. This means that the access to any
  private keys associated with any funds is extremely limited.

Source: https://www.reddit.com/r/btc/comments/6vpuy5/14_of_my_btc_held_in_limbo_at_kraken/


save prevision data in the database on theme activation

Question: I developed a theme for my client. Theme have predefined posts, pages and sliders etc. when some one activate the theme, theme does the following steps on theme activation action hook.
1:- Empty the current WordPress database to avoid any duplicate data entry issue.
2:- Inserts predefined data in the WordPress core tables and creates some other required custom tables with data.
Everything is working fine accept one issue and that is my theme removes all the previous data in the database. so that client lost his all previous data.
i need any idea or help to tackle this issue. User just want to add new theme using theme zip file and all the posts and pages each and everything should be done automatically.
Any help or idea will be highly appreciated.
Answer: Never change content without the user's specific manual request, and never ever delete anything from the DB that you haven't created.
So the only question left is how to create you sample content. The cleanest way is to provide an exported sample that can be imported into WP. The only problem with this approach is that it requires the installation of the wordpress importer plugin. The other possible approach is to write a code that will generate the sample content, but this also needs to be triggered by a manual action by the user.
If your user is not very bright (as most users are ;) ) you can show a short message about the existence of the option to import/generate a sample after theme's activation.
Comment: Appreciate your response. But i have to do this in same manners.  I tried generating xml using WordPress exporter plugin and then import it using the WordPress importer plugin but client rejected it as he does not want to do such kind of activity, after that i wrote a function for importing data in the database on the the theme activation hook. So any idea?
Comment: I am deleting the user data only because of the primary key duplication constraint. Let say i have a post with the id of 3 in sample data and in the users database the id 3 is already occupied. so what should i do in that case?
Comment: Why should you care what is the ID of the post?
Comment: because i have to insert the sample data in the database with the theme activation. And if the post id is already filled with some other post then it shows the duplication error. and if let say in any case i managed to inserted it on the same id then i lost the old data.... same issue again


Which reflects more sunlight energy, aluminum or silver mirrors?

Question: I am building a solar oven.
I intend to use mirrors.
however I am uncertain how to determine which will reflect more sunlight, Aluminum or Silver mirrors. How to go about this?
Comment: Related/duplicate: https://physics.stackexchange.com/q/116452
Answer: At the infrared wavelengths where you will get most energy there is very little difference in reflectivity.
Aluminium mirrors are generally cheaper and will last longer. Silver mirrors quickly tarnish unless they are protective over-coated.
Answer: The use of silver as the reflective layer is claimed to lead to higher efficiency levels, because it is the most reflective metal.
https://en.wikipedia.org/wiki/Solar_mirror


Can You Dual Wield Pistols if One of Them Has Loading But Not the Other?

Question: I am making a character who uses pistols as their ranged weapons. If an effect like the artificer's Repeating Shot infusion got rid of the loading effect on one pistols, could they dual wield pistols?
Answer: Unfortunately, this does not work
Repeating Shot says:

If you load no ammunition in the weapon, it produces its own, automatically creating one piece of magic ammunition when you make a ranged attack with it.

That means you will never need to load your infused pistol, and need no free hand for that. What about your normal pistol?
Pistols have the ammunition property and that says (PH p. 146f):

Drawing the ammunition from a quiver, case, or other container is part of the attack (you need a free hand to load a one-handed weapon).

The emphasized part was added in clarifying errata. Your pistol is a one-handed weapon. This means once your pistol has fired, you will need a free hand to load your pistol, and will not be able to do so, when you hold an infused pistol in your other hand.
In addition, two-weapon fighting is only available for melee weapons (PH, 195):

When you take the Attack action and attack with a light melee weapon that you're holding in one hand, you can use a bonus action to attack with a different light melee weapon that you're holding in the other hand.

Not even the Dual Wielder feat changes that:

You can use two-weapon fighting even when the one-handed melee weapons you are wielding aren't light.

So dual wielding guns is not supported by the rules. Talk to you DM to see if they are willing to make it happen for you and find a way to balance it. Its a cool trope, after all.
PS. The loading property is not relevant for dual wielding. All it does is limiting you to one attack per round with a weapon. The infusion allows you to ignore that limitation if you have extra attacks for the infused pistol. Even if you could dual wield however, you use your bonus action to attack with your other hand, and you only have one bonus action per turn for that anyways.
PSS. There is a way to try and get to dual wielding with hand crossbows, which is somewhat more feasible due to the Crossbow Expert feat, but even with that, due to needing free hands to reload, you cannot quite get there: Can you dual wield two hand crossbows?
Comment: @SeriousBri Nothing stops you from holding a pistol in your other hand, but there is no rule that allows you to make a bonus action shot with it, as its not a melee weapon. You could look cool and fire them on alternate rounds.
Comment: Technically could you dual wield until you ran out of ammo on the pistol that needs loading? Without the fears (which don't work as you explain) it doesn't do anything more than just using one pistol, but you get to look cool for a bit.


Homeomorphism groups as topological groups

Question: As is well known, the homeomorphism group of a compact Hausdorff space is a topological group. The same is true for locally compact locally connected Hausdorff spaces, but it is false in general. Now what if the space is compactly generated and weak Hausdorff and the homeomorphism group carries the compactly generated topology stemming from the CO topology? Is it necessarily a topological group?
Answer: I've been thinking about this question recently, and came across this post.  Here is a partial answer.
If $X$ is a locally compact Hausdorff space, then Arens' 1946 $g$-topology on the group $\mathrm{Homeo}(X)$ is an admissible group topology.  Therein, it turns out to be the restriction of Fox's 1945 compact-open topology on $\mathrm{Homeo}(X^+)$ to $\mathrm{Homeo}(X)$, where $X^+$ is the one-point compactification.  The $g$-topology is finer than the compact-open topology on $\mathrm{Homeo}(X)$.
Admissible means that the evaluation function $\mathrm{Homeo}(X) \times X \to X ~;~ (f,x) \mapsto f(x)$ is continuous.  Group topology on a group $G$ means that the fraction function $G \times G \to G ~;~ (a,b) \mapsto a^{-1} b$ is continuous.  If the locally compact space $X$ is not compact, then the compact-open topology (called $k$-topology within Arens' paper) on $\mathrm{Homeo}(X)$ is an admissible monoid topology, but inversion is not guaranteed to be continuous.  This is remedied by Arens' $g$-topology refining it.
Now, suppose more generally that $X$ is a compactly generated Hausdorff space, as surveyed in Steenrod's 1967 paper, "A convenient category of topological spaces."  Endow $\mathrm{Homeo}(X)$ with the compactly generated topology induced from the compact-open topology.  It follows from methods of that paper, especially from Section 5, that $\mathrm{Homeo}(X)$ becomes a group object in the category $CGHaus$ of compactly generated Hausdorff spaces, which is a retract of the category $Haus$ of Hausdorff spaces.  However, they possess different products.  So I don't know if the topology you specified makes $\mathrm{Homeo}(X)$ into a group object in $Haus$.
Culturally speaking, $CGHaus$ is preferred by most algebraic topologists, whereas $Haus$ or $Top$ is preferred by most general topologists.
In categorical language, a topological group ends up being a group object in the category $Top$ of all topological spaces and continuous functions, just like an algebraic group is a group object in the category of all algebraic varieties (over a given field) and regular functions.


Understanding swing rhythm

Question: It's my first time trying to learn something with a swing rhythm. I believe I understand how to play four consecutive 16th notes with swing, but how am I supposed to play the highlighted parts in measure 7? My current guess is that I perceive the 8th notes as two connected 16th notes and swing it as I would four distinct 16th notes (which is what the other hand is doing in both cases). I'm not completely sure though because I've been playing the highlighted part in measure 5 without any swing since that sounded natural to me. But maybe I really should be swinging that too? Is there a general rule of thumb to apply here?
Answer: Take a good listen at this video of "Raindrop Flower" from MapleStory, especially at 0.5x speed (so the 16th-note swing is more apparent):

Yes, treat the central 8th notes as if they are tied swing 16th notes in the exact same positions. The original/video version plays all those central 8th notes that way (i.e. 4 16th notes in a row are ooone e aaand a, 16th note-8th note-16th note in one beat are ooone e-aaand a).
Answer: There are many ways of playing and interpreting swing. However, swing in its most basic form is a way of applying a triplet feel to straight notes. Instead of playing two evenly spaced notes you play 2+1 of a triplet in the same time frame. The most common are 8th notes but 16th notes are also widely used. Here is the progression and subdivision of the rhythm in question, a 16th-8th-16th in one beat with a swing feel instruction. The blue numbers under the measures indicate the occurrence and durations of each note:

It starts with 6 triplet 16th notes

The swing 16th feel comes from playing notes 1,3,4,6

Notes 3 and 4 are tied, leaving you with notes 1,3,6.

This is the true swing subdivision of that rhythm. It is definitely different from the straight version of this rhythm, which has a subdivision of 4 and is played on notes 1,2,4.
Comment: A picture paints a thousand words - here, it does exactly that. +1.
Answer: While Tim provided the correct way to notate the rhythm in question (assuming triplet swing realization), I'd like to address this:

I've been playing the highlighted part in measure 5 without any swing since that sounded natural to me

It is common at high tempi to play more shallow swing, i.e. more similar to a straight division. This is not the case in the recording quoted by Dekkadeci, but it's not surprising that less swing may feel natural to you.
Comment: It is true that the line between swing and straight rhythm can become more blurred as the tempo increases. I actually meant to mention that in my answer but didn't get around to it. Glad you did.
Comment: 'Twasn't I, 'twas John. Can't take credit where it's not due!
Answer: Swing notation is peculiar. The correct, or at least approximate, notation would be the 1st and 3rd of a triplet … which is hard to write and read with all those pauses in between.
Now, if you do it by hand, the result looks like two consecutive eighth notes. So convention is to put the keyword "swing" and play them as above's triplet, to make notation simpler. // Preview: So the first measure plays 4 triplet of swing AND has 8 of them (where 4 are just silent).
In your case the reference are 16th notes, i.e. 2 of them are a triplet by the definition of swing. I understand the highlighted parts as this instruction:

play 3 notes in the time period of 2 triplets
distribute them "uniformly"

To solve this puzzle expand them into 2 triplets with all 6 notes, and delete 3 of them. Then you see where they are intended to be in time:
<code>1 2 3 1 2 3 // 2 expanded triplets
1 . 2 . 3 . // keeping 3 of them equally distributed in time
</code>
So you could describe it as a swing triplet followed by its inverse (exchanging beats for pauses and vice versa).
When practicing I made good experience to go through all 8 combinations of playing 0, 1, 2 or 3 notes of a triplet. Then none of the above remains a problem while playing. // This may be useful for the bass clef notes in meas. 5, for example.

Understanding swing rhythm


Removing ASP.net Session calls from business logic

Question: I've inherited an asp.net web solution, which has business logic and data calls as seperate assemblies. In the business layer there are a small number of calls to get/set HttpContext session values. I've looked around for an example that will allow me to abstract this away from the business logic as I'd like to be able to reuse these assemblies in non-web projects, could anyone please give me an example of the best way to do this. I was thinking of some sort of session factory that will obtain values from some sort of persistant store depending on the usage scenario but I'm new to architecture really and would appreciate a pointer or two.
Comment: What kinds of values is it that is stored in the session state?
Comment: Right now just a complex type containing user details and their data permissions as a list of Guid.
Answer: The simpliest way in my opinion is to create an ISessionProvider interface, with a Dictionary<string, object> {get; }. Then create a public class HttpSessionProvider : ISessionProvider that returns the actual session bag contents.
At least, instantiate this object in your web app and give it to backend class, either by specifyng it manually or by using any IOC pattern.
[Edit] after a small reflexion, it's not a clean way. You won't have dependency to the asp.net framwork, but you will still have the "asp.net" content of the session accessible.
In this case, keep the Interface, but either add specific properties (string customer, int userID, etc.) or return a dictionary only with actual business data
Answer: I have done something like this on some projects:
public interface IAppContext {
    string SomeVariable {
        set;
        get;
    }
}
public class HttpContextAppContext : IAppContext {

    public static readonly string CONTEXT_PREFIX = "appcontext_";

    public string SomeVariable {
        set { HttpContext.Current.Session[CONTEXT_PREFIX + "SomeVariable"] = value; }
        get { return (string)HttpContext.Current.Session[CONTEXT_PREFIX + "SomeVariable"]; }
    }
}

Answer: What business has the business layer got with Session? To understand that statement a little more, think of it this way: why does the business layer need to persist user related info, ever?
The business layer needs to work with and process user related data, but not store it. This means the data that is currently stored should be injected, i.e. it should be passed in as a parameter to the functions that need it. Doing it this way is forming an architectural contract, it is saying "hey, i need that user info to do my job" in a very explicit way - you are not performing some magic under the hood with some random previously stored values. It is fine for the business layer to authenticate or authorise the user in some way using that data, but it should discard the authentication results after it has finished with them. If the values are being persisted to save a call or two to the database, then you have a problem with the efficiency of your database calls, because database calls for simple things like that are quick.
So my suggestion is to remove any references to Session from your business layer, and change your function signatures to include the user data you need passed.
Comment: On reflection you are correct, I don't want to store the values in that layer, I simply want the layer to be able to use data that is currently persisted in Session. In this instance the list of Guid stored in Session is directly reflected in the database so I can retrieve it from there if needs be.
I guess what I really wanted was to hand off the request for this data to a 3rd party (session factory) that would return me the list from the most suitable place, which I think would be Session in being called from UI and the database if not.
Comment: Awesome... i'm not against down votes where warranted, but i would LOVE to be educated in my mistakes from the person who down voted this one. I don't miss the 2 rep points, it's simply a matter of principle.


Autocorrelation of sound in liquids vs gas

Question: This is just a curiosity and you need to bear with me as my math skills were always sub-par and so is my English academic language. My specialty is Electronics but I have always been a programmer.
Years ago I was working on my diploma paper that dealt with locating leaks using auto-correlation.
Basically you have several sound sensors along a pipe which record the sound wave. If a leak appears then you get a peak in the autocorrelation function. Then you perform a  'triangulation' from two or more sound sensors and you can locate the leak pretty accurately. Anyway, my task was mostly to help a PHD student with transposing her algorithms into Matlab.
We have succeeded doing this with air but as soon as we switched to water I could not use any kind of windowing and/or transformation to get relevant peaks. At some point I just hunted blindly for some Matlab functions that would give me a relevant peak somewhere that would correlate with the distance to the leak, but failed.
I cannot to this day understand why we were not able to succeed, though I do assume that is has to do with water's turbulence. The setup was a running tap routed through metal pipes (about 10cm diameter), with about 5 very sensitive sound sensors (going to about 100kHz) placed about 3 meters apart and some taps along the way that simulate leaks. Everything was placed in a phonic-insulated basement, signals were truncated taken to stabilize against footsteps/vibrations so measurements were pretty good.
The multiple question is: what could have been done to achieve the goal or at least get closer to it? Is it really achievable (probably not in real life where you have trucks running above)?
Some variables that could influence but for which I lack the knowledge to explain: pipe diameter, water debit rate, tap/leak rate and diameter, choice of liquid, pipe material, sound spectrum and possible frequency filtering.
Answer: Did you see the experimental setup?
I believe that a leak in a gas pipeline generally makes a whistling sound whereas leaking liquid will be very quiet. Without sound, the autocorrelation approach doesn't make sense.
To find the leak in a pipeline for liquids,
one could use a marker to find the leak (e.g. add some color). Or one could seal segments of the pipe using inflatable pistons and measure the flow through them. When less flows out than you pump in, you have a leak in the segment.
Comment: I had a water (copper pipe) leakage in my house about 20 years
ago. Because that pipe was located in some wall or below floor,
the plumber did some detecting first.
The pipe was separated from the rest of piping and then **air**
pressure was applied. Under this condition the likely place of
the pipe was followed with a special microphone for solids.
The sound to hear was as You would expect from a hole where
air and water droplets "spit and sizzle" out.
Comment: @Georg: excelent setup, did not thought of that. #whoplisp: I did see the setup, it is like I described it - 10-15m of metal pipe about 10-15cm diameter. The issue here however is: detecting the location without having to walk up to it and measure. Think about buried water utility pipes, you can have some monitoring on some computer which will detect the leak in time and also its location. I don't know if audible range for humans is really the place to scan, this was part of my question.
Answer: Without being able to see the data, I can only suggest two things that worked for me in a project about turbulence in water.  The first is, if turbulence is a significant factor, it will show up in the auto-correlation function as violent oscillations getting worse and worse in the graph, basically exceeding the accuracy of the software to calculate it after a certain point.  If you did not see that in the autocorrelation function, then turbulnece was not your problem.
To deal with it, we just pre-whitened the data and this got rid of that noise so we could detect the relevant peaks, up to a point and within a certain range (high enough it still got out of control, but the pre-whitening improved it).


Custom Post Type admin screen in Network Admin

Question: I am working on a project where I need to add table for custom post type. Please see this image: http://puu.sh/bOvtP/401d0f2f46.png
I have picked up a half-done project, and the client is willing not to see the WP interface. So, they already have it customized to a vast extent.
I have successfully created the admin pages in the back-end for three different custom post, for all three of them I need to create the table as shown int the image above.
The fourth column in the table in the above image is for "Region", which is actually name of states(which are sub-sites in the Multi-site network), I don't know how will I know to which sub-site the custom post is posted in.
The images shows that this is like admin screen of a custom post. But, the client don't want to use the default display of post in List tables in WordPress.
My problem is that I am not able to get the "custom posts" at that screen, and don't know how will I identify to which sub-site the custom post is posted too?
Please, view and suggest something. Thanks.
Comment: It was resolved.
Answer: It was resolved. This question was specific to some particular project and it's requirements. And, it was fulfilled at that time with a multisite function for WordPress.
What I did:
The task was done using a sub-class of WP_Query named WP_Query_Multisite. This class provides us arguments to use for which site to grab the info from.
What I used is:
<code>    if( ($taxonomy != '') AND ( $taxonomy_term_slug != '' ) ) {
        $is_taxonomy_query = TRUE;
        // This is a call with taxonomy so set those args
        $args = array(
            'post_type'     => $post_type,
            'post_status'   => array( 'pending', 'draft', 'future' ),
            $taxonomy       => $taxonomy_term_slug
        );
    }
    else {
        $args = array(
            'post_type'     => $post_type,
            'post_status'   => array( 'pending', 'draft', 'future' )
        );
    }

    // Run Our MultiSite Query
    $query = new WP_Query_Multisite( $args );
</code>
And, then using the global variable blog_id in the loop:
<code>    global $blog_id;
    echo get_blog_details( $blog_id )->blogname;
</code>
Comment: This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post - you can always comment on your own posts, and once you have sufficient [reputation](http://wordpress.stackexchange.com/help/whats-reputation) you will be able to [comment on any post](http://wordpress.stackexchange.com/help/privileges/comment).
Comment: Answer added properly.