Explanation : Latching Relay Circuit

Question: I need to understand the flow of this circuit well. The objective of this circuit is to switch the latching relay "OFF" or "ON" (in two states) depending on the state of the I/O's of the MCU. I need to understand how this works. The relay is a 9VDC, 60A, 250VAC relay, and the bridge gives an output of 12Vdc. Thanks!
Comment: Is it me, or is the whole circuit backwards?
Answer: This looks very similar to a half bridge.
When both the IOs are at the same level, both the left and right circuits are providing the same potential to the relay.
When one of the IOs changes, the potential provided at that side of the relay changes.
The difference in these two potentials is what switches the latching relay.  It's just like driving a motor in forward/reverse.
Let's take a closer look at the right-hand side of the circuit.
When the IO pin is low, what is happening?
Well, Q4 and Q6 both have their bases pulled low.  This switches them off.  In doing so the pull-up resistor R2 pulls up the base of Q3, switching it on.  Thus, the power from the +12V rail is allowed to flow to the relay.
If the IO is set to high, what then?
Well, Q4 and Q6 are both switched on.  This connects their collectors to ground.  Q4 links the relay to ground, and Q6 links the base of Q3 to ground, switching it off.  This isolates the +12V from the relay so you don't get a nasty short.  so that side of the relay is now at ground potential.
Combine that with the same thing happening to the left side of the relay, and you can see how different combinations of IO can give different potentials at the relay terminals.
<code>A | B || L | R | Vdiff
======================
0 | 0 || + | + |   0v    Nothing happens
0 | 1 || + | G | +12V    Relay switches to one position
1 | 0 || G | + | -12V    Relay switches to other position
1 | 1 || G | G |   0v    Nothing happens
</code>
Comment: Thanks for the explanation! But I want to know if there is a peculiar need for using 3 transistors each, because I want to believe that 2 transistors can do exactly the same. From the data sheet, Q5 and Q6, are switching transistor, and it seems like Q1 - Q4 are amplifying transistors. So is there any form of amplification in the circuit?
Comment: All the transistors are switching.  The purpose of Q5 and Q6 is to invert the signal, so either Q1 or Q2 is on but not both - the same for Q3 and Q4.  This routes either +12V or GND to the relay pin, but never both.  You could replace Q5 and Q6 with an inverter logic gate to get the same effect.
Answer: It's an H-bridge. I'll explain for the left half, the right half is identical.
If the control line is high Q1 and Q5 are conducting, and by pulling Q2's base low Q5 shuts it off. As a result this relay pin is switched to ground by Q1.
If the control line is low Q1 and Q5 are not conducting, and Q2 is conducting; R1 feeds the base. Via Q2 the relay pin is switched to V+.
You switch the relay on or off by placing opposite signals to the control pins. Since it's a latching relay you can remove the voltage across the coil after it's switched by making both relay pins the same voltage.
Answer: As said this is a H-Bridge.
Q5 and Q6 work as inverters.
Q1 and Q2 are never on at the same time. The same is true with Q3 and Q4.
So if current is going through the relais it is either that way (Q2 and Q4 on)
<code>   V
   |
   +--R--+
         |
         V
</code>
or this way (Q1 and Q3 on)
<code>         V
         |
   +--R--+
   |
   V
</code>
All transistors are just used a switches.
Still I think you really need 2x3 transistors (unless you want to use more control lines or other devices (e.g. inverters from IC))

Explanation : Latching Relay Circuit


sql connection pool

Question: I am making multiple queries to a database over a short period continiously.
In the past I have always closed the connection and reopened when I needed to talk to sqlserver again - this served me well. But now when I try to do this over a very short period I get no connections availible messages. I then thought I would just try and keep the connection open for the life of the application, so far so good I haven't run into any problems. I am just wondering what others think of this approch...am I on a short road to disaster?
One other thing I have nocied that I really don't have to call connection open() method, the connection just seem to work without the call - what's the deal with that?
<code>void main()
{
SqlConnection cn = new SqlConnection();
cn.ConnectionString = <connection>;
tmr.interval=100;
tmr.Elapsed += new System.Timers.ElapsedEventHandler(tmr_Elapsed);
}

void tmr_elapsed()
{
tmr.Enabled = false;
SqlDataAdapter da = new SqlDataAdapter(query, cn);
da.Fill(dt);
tmr.Enabled = true;
}
</code>
C#, sql-server 2000, .net 2.0
Answer:
The connection object associated with the SELECT statement must be valid, but it does not need to be open. If the connection is closed before Fill is called, it is opened to retrieve data, then closed. If the connection is open before Fill is called, it remains open.

For more information look at this question.
Answer: You really shouldn't keep this connection open and then reuse it.  Granted, your timer is very fast (every 100 ms) but at the same time, you are keeping that connection open for quite a long time.
Rather, you should open the connection and Dispose of it properly when you are done in the event handler for the timer.  If you use a using statement for your connection you should be fine and not worry about resource exhaustion.
As for not having to open the connection, the SqlDataAdapter does it for you, opening and closing the connection as needed.  It will leave the connection in the state it was in when you passed it in after it does its work (it will keep it open if it was open, or open then close it if it was closed).

sql connection pool


How to select wifi channel with windows 7 adhoc?

Question: I made an adhoc network with Windows 7. Now I would like to change the wifi channel it is using. How to do this?
Answer: The ability to change the channel is a function of the wifi adapter driver.  Some can, some can't.
If yours can, you'll find it in the wifi adapter properties.

Press the Windows logo and "R" keys simultaneously to display the "Run" dialog box. Type "devmgmt.msc" without quotation marks into the
  box and press "Enter." The Windows device manager will appear.
Double-click "Network Adapters" to expand the category.
Right-click your wireless network adapter and click "Properties."
Click the "Advanced" tab, then click "Ad Hoc Channel 802.11" under "Property" on the left side of the window.
Use the arrows on the right side of the window to change the channel. Make sure that you and your ad hoc networking partner select
  the same channel.
Click "OK" to save the change, then close the device manager.

source
Comment: Thanks for quick reply. This confirms the issue. Clearly Atheros AR9285 drivers can't change it.
Answer: When installing the Windows drivers for the Atheros device, the INF file may not have included Ad Hoc channel selection capability even though the wifi card is capable.
Look for 'defaultIbssChannel' examples in the INF file.
You can then add this new parameter by using 'regedit' and add to the existing parameters that are available to the wifi card.
Look in:
HKEY_LOCAL_MACHINE/SYSTEM/ControlSet 001/Class/.....NDI/params
Eventually, you may want to modify the INF file and re-install the driver.
I had the same problem with the AR9280 chipset and was able to set the Ad Hoc channel by tinkering as above.
Comment: Hi glenn; I did follow your instructions and found the inf file and created the defaultIbssChannel values in the registry in 'CurrentControlSet', 'ControlSet 001', 'ControlSet 002'; the option to change the channel is added now to the advanced properties of the driver but changing the channel doesn't take effect; Any thought?
Comment: reset the wifi card (disable/enable the interface).  the change should take effect immediately.  Also, be aware that there is a thing called IBSS merge.  If you are connecting to an existing ad hoc network, your wifi card will change its channel to the established network's channel.  However, if you're the first one up, your wifi card should pick the default channel you selected.
Answer: I have worked out how to change the channel used by the Microsoft Virtual Miniport Adapter, which is used by 3rd party routers and Ad-hoc connections.
A full description can be downloaded here:
http://www.necon.co.za/xx/WiFi_Router.pdf

Connect to a sample Wi-Fi network running on the s
  ame channel as that required (e.g. channel 6)
Run the router software so that it adopts the same
  channel (e.g. channel 6)
Comment: Welcome to Super User! Please quote the essential parts of the answer from the reference link(s), as the answer can become invalid if the linked page(s) change.


Open up iPhone 5s to turn it off

Question: My iPhone 5s screen is blacked out and I can't turn it off by using the screen and buttons.  How do I open the phone so I can remove the battery to turn it off?
Answer: Do not open your iPhone unless you are an experienced with phone repair person . Better take it to an Apple Store or any cellphone repair shop. Otherwise, use iFix guideline.
https://www.ifixit.com/Device/iPhone_5s
Answer: Some faults on iPhones can be solved by manually disconnecting the battery. In order to do this you'll need to remove the LCD screen (which may void your warranty where applicable). If your device is out of warranty and more importantly you have the right tools then there is no harm. First check a video guide (i suggest Jerry Rig on Youtube).
This way you familiarise yourself with the process first.

The bottom two screws need to be removed with a pentalobe screw driver.
Once they're out use either a suction cup or a plastic pry tool to lift up the lcd screen. The battery connector is underneath a small metal shield with 3 Phillips screws.
Once they have also been removed, use your pry tool to remove the battery connector flex cable from the board connector. This will completely (soft) reset the device. After a few seconds reattach the battery connector and power on the iPhone.

Hopefully your device will power up as normal..... othwerise there may be faults which  need further investigation.

Open up iPhone 5s to turn it off


RHELP on a Raspberry Pi 4 Model B

Question: Is it possible to install Red Hat Enterprise Linux on a Raspberry Pi 4 Model B? The model B's OS is on an SD Card. Can I just take this out and install the RHEL on a new SD card? Has anyone done this? Any issues? Thank you in advance!
Answer: Closest I know of is a Centos port that's a bit of AltArch amongst other bits :-) It's not clean or RedHat and I have not seen any move to port to the Pi 4
Have a look at the SIG at centos.org if you have a 3B+ handy.

RHELP on a Raspberry Pi 4 Model B


inexpensive bike for Wahoo Kickr

Question: I bought a Wahoo Kickr trainer in 2020 and have been using it almost daily with my Trek Madone 4.5. But I also ride the bike 3x times per week and I am getting tired of taking the rear tire on and off to mount it on the trainer. So I thought I could get a cheep second bike and just leave it on the trainer permanently. First I thought I would find a used bike in my size (60 cm), but the few that I saw were either very old, or too expensive for what I want the bike for. Does anyone have a recommendation for a cheep department store (Walmart/Amazon) bike that would be compatible with the Wahoo trainer? I think that I can get something with a 7 speed Shimano cassette and mount that on the Kickr with a spacer?
Comment: Sorry we don't really do shopping questions like this - they're considered off topic because of limited long term use.
Comment: Any old shitter will do. Think less, pedal more
Answer: Any bike should work on your trainer, as long as the rear axle mounts up the same way, probably a QR skewer.
Ideally the trainer-bike would duplicate your existing bike fit, so have the same stack and reach and similar saddle and handlebars.
You're right, any size cassette will work in terms of gearing, but it may be worth having at least the same number of rear cogs and about the same intervals as your road bike for muscle memory. That way you don't need to have spare 10 speed and 7 speed chain and so on. Likewise it would be good if the rear wheel was about the same width as your existing bike, to "use up" the tail-end of the tread in your road bike tyres.
Ideally the trainer bike would have the same kind of pedals as your road bike, and similar crank arm lengths and Q factors.
Good luck with searching locally for a suitable second bike.
Comment: "Likewise it would be good if the rear wheel was about the same width as your existing bike, to "use up" the tail-end of the tread in your road bike tyres." I think OP has a direct drive trainer i.e. the chain directly connects to a cassette mounted on the trainer and not with the rear wheel pressed against a drum.
Comment: The Kickr (even in 2020) came with various endcaps for 135 mm QR axles, 10 x 142 mm thru axles, and10 x 148 mm thru axles. I bet you coulkd buy superboost end caps too.
Comment: A 2020 Kickr (Vx or Core) must be direct drive, the Rollr (well...) and Snap (wheel-on) were introduced way later. Depending on your indoor riding, gearing might not even matter so much - you can reduce trainer difficulty so that the Alpè is ridable with a 25t cassette and when you mostly do workouts, just choose the cog you want to wear down this season and never shift the rear for the next 4 months like I do...^^
Comment: @PaulH good point - that's worth being an answer of its own.   OP might only have caps to suit one kind of rear axle, which could limit the kind of bikes that can be used.

inexpensive bike for Wahoo Kickr


Should I put tempo change markers only on midi track in this case drums or on master track?

Question: How will recording other instruments be affected by where I put the tempo changing markers? I'm using Mixcraft Studio Pro 8
Comment: What software are you using?
Comment: mixcraft studio pro 8
Answer: Master track. Tempo changes are pretty much a master track kind of thing.  Didn't see the other part of the question until now.  It really shouldn't affect the instruments or the way you record them, other than whatever notes entered will be played back at the speed you set the tempo to.  What DAW are you using?  I think the principles are going to carry over to every DAW, but you never know until you check.  If you make a tempo change and want to live record midi into that section, it should play back exactly how you recorded on any track in the project.  The other tracks or instruments are slaves to the master track, so they all follow whatever the master track is set to.
Comment: This doesn't answer the important part of this question - which is how it will affect other instruments...


How to Flash Android 5.1 in Moto E XT1022

Question: I've update my Motorola Moto E with Android 5.0.2 in Soak Test. Here's my S/W version. . Somehow I was unable to got Android 5.1 update. thus I've decided to install it manually.
I've found Moto E 5.1 Stock ROM Here! But, my problem is how to follow these steps mentioned in website.  I mean what is Custom Recovery (TWRP), what is Factory Reset (System, Data, Cache, Dalvik)* and How to Flash ROM?. How to do this?.Thanks in advanced for any kind of suggestions, help or tutorial link etc...
Comment: Please refer to XDA for such tutorials. They are dime-a-dozen.
Comment: Thanks @TamoghnaChowdhury. but, can you please provide me a perfect link. I'm confused b/w lots of tutorials.
Answer: A custom recovery is a replacement recovery software for your device. It basically has a backup feature and a system for installing unsigned updates (flashable zips).
Factory reset is a wipe of your user data and cache partitions. It does not affect other partitions, and can be done via stock recovery.
Flashing a ROM can be done in two ways: fastboot or some flash tool for stock ROMs, and for custom ones, by flashing a ROM zip through a custom recovery. For the installation of a custom ROM, not one of its updates, these partitions should be wiped: system, data, cache (app data cache), and dalvik cache (app code cache). Further information depends on the particular variant of the device you are on.


Use chown to set the ownership of all a folder's subfolders and files?

Question: How can I use the chown command to change the ownership of all a folder's subfolders and files?
Comment: `chown -R your_username:your_group folder`
Comment: `chown -R` should work for you.
Comment: Will any of these answers work if the files inside a folder are owned by someone else and only have user read/write permission?
Answer: From chown --help:
Usage: chown [OPTION]... [OWNER][:[GROUP]] FILE...
  or:  chown [OPTION]... --reference=RFILE FILE...
Change the owner and/or group of each FILE to OWNER and/or GROUP.

[...]

  -R, --recursive        operate on files and directories recursively

[...]

So you need to run (probably with sudo):
chown -R USERNAME:GROUPNAME /PATH/TO/FILE

Or, if the group shall be the specified user's primary group (usually same name), you can also omit the GROUPNAME and just give the USERNAME: with a colon (no space before it!). It will be set implicitly:
chown -R USERNAME: /PATH/TO/FILE

To only change the user and leave the group as it is, just specify USERNAME and no group name and no colon:
chown -R USERNAME /PATH/TO/FILE

To only change the group and leave the owner user as it is, just specify :GROUPNAME with a leading colon:
chown -R :GROUPNAME /PATH/TO/FILE

Answer: My username is timo and I did this to take ownership to all my files and folders on home directory (transferred from another account):
~$ sudo chown -R timo /home/timo/*

Comment: Worked for me. Thanks.
Answer: chown -R <username>:<groupname> <folder>

This is how I normally do it, and I usually do this one folder at a time. Doesn't take but a few moments to work through each folder.
Answer: I prefer:
    chown -hR :
This will also change ownership of symlinks instead of just the destination files that the symlinks point to.
Comment: "chown -hR root /u" mean change the owner of /u and subfiles to "root".
Answer: man chown
chown options user:group files/folders

Not sure why other answers did not cover one dot. : And . are interchangeable, so you can use one dot for instance
chown -R user.group files/folders

Answer: Either get to the terminal display mode as described elsewhere or do a ssh login from another computer. Usually the account is intact and it will be accessible via ssh.
You may also have an account on the same machine without the login loop problem. If you do, then login to that account (assuming it will let you sudo).
Once in, open a terminal and find the directory under which you can see the username directories. i.e. /home/username1 /home/username2
Run ls -l
if any of the user directories is owned by root change it by running:
sudo chown -R username:username /home/username

This example is based on an architecture where the user directories are under /home/
Run ls -l again to confirm the directory is owned by the user.
This was tested on Ubuntu 20.04


How do I send available_apps in context to a view that is outside the admin panel in Django?

Question: How can I get an application list like in get_app_list method in classy AdminSite?
I try to do it this way, but then I get an empty list.
from django.contrib.admin.sites import AdminSite

    def change_view(self, request):
        ...

        context = {
            ...
            'available_apps': AdminSite().get_app_list(request)
        }
        return render(request, 'parts/part_form.html', context=context)

I need this to display the admin side menu outside the admin panel.
Answer: You're calling AdminSite, I'm not sure but that might be incorrect according to docs.
Does AdminSite.get_app_list(request) work?
Answer: Try this:
from django.apps import apps

for app in apps.get_app_configs():
    print(app.verbose_name)

Answer: This one works:
from django.contrib import admin

app_list = admin.site.get_app_list(request)

for app in app_list:
    print("App name:", app['name'])
    print("App models:")
    for model in app['models']:
        print(f"  - {model['name']} ({model['object_name']})")


No render output node in scene

Question: I am new to using blender and have been watching youtube videos on how to use it. I copied the steps of how to create cracks in a surface. I can see what it looks like if it gets rendered but then when I go to render it I get the message "no render output node in scene". It's not an animation, it's just a single image. Here is a screenshot of all my nodes and the error after trying to get it to render.
Comment: Pretty sure this is because you removed the composite output in the compositing node tree accidentally. I'll write up an answer with more detail.
Comment: You just beat me to it. i am sure that is what it is.
Comment: @shaunify Glad to help. I hate to ask this, but if my answer solved your issue, could you please accept it? Thanks :)
Answer: The issue is most likely that you removed the composite node accidentally in the composite node tree.

Select the composite node tree button (highlighted left).
At this point, we should take a step back, and make sure that what I think is happening, is happening.
There are two signs that I'm wrong:

Use Nodes isn't enabled
There is a composite node

If both of those aren't true, then continue.
Now there are two ways you could solve this.
#1
You could disable Use Nodes. When this is disabled, anything in the compositing node tree is ignored.
#2
Or you could add in a composite node, and attach it to the Render Layers node.
ShiftA output -> composite.

And then attaching the render layers node to it.
Comment: To add to TARDIS Maker, sometimes the problem is that you don't have a Material Output node in your material. Add one: `Shift+A >> Output >> Material Output`
Comment: Also try unchecking "Sequencer" in Output Properties >> Post Processing. Worked for me.

No render output node in scene


How can I access my Windows 10 computer from my Raspberry Pi 3?

Question: I have a PC running windows 10 and a raspberry pi 3. I do a lot of music recording, and I cannot reach my computer from where I am positioned (depending on which instrument I am doing at the time). I would also like to use the raspberry pi touchscreen to edit the fader positions of the tracks. My question is: How can I wirelessly connect the raspberry pi to the computer so that I will be able to remotely access the windows 10 machine from the raspberry pi 3?
Comment: Accessing is one thing, controlling Windows applications from Raspberry Pi with a touchscreen connected to the Pi is orders of magnitude more complex. Most likely undoable.
Comment: Some kind of remote desktop utility maybe. VNC? from Pi to Windows? Never really tried that one.. I have noted and will try and see how easy it is to do it that way round. Touchscreen.. yea.. I suppose if VNC supports mouse redirection then touch screen clicks will also work via this Remote Desktop Protocol
Comment: You're going to have a pretty miserable time of it trying to adjust levels like that. I tinkered with teamviewer and android gizmos for a while for the same task, but the latency and small screens is a killer. You might want to consider using an arduino or ESP8266 to build something with physical controls (rotary encoders/flying faders) that talk over midi and identify as a USB device, then looking into using the pi as a wireless USB transmitter.
Comment: @goobering Good idea, I'll try that.
Comment: Note that to RDP into Windows it must be at Professional Edition, it won't work on Home.
Answer: If you need access remotely to MS Windows, you can use Remote Desktop Protocol (RDP). There are many application that implement it.
For example this one.
https://www.weaved.com/weaved-with-windows-remote-desktop-rdp-raspberry-pi/


Hiding objects from search

Question: I have a group of objects with several pieces that need to be separately positioned so I cannot join the meshes, but it creates a lot of clutter in the object search panels. I don't need to have them visible in the object selector panels at all, is there any way to hide them or at least group them in a way that they show up as a single object in search? I need to still see them in viewport and renders.
Comment: group them into a collection?
Comment: I did test this, it indeed works when I do:
box.prop_search(context.scene.LayoutHelper, "compass_object", context.collection, "objects"
In my case I need the list to display regardless of collection so I'm trying my luck using something else, but this definitely put me in the right path, although the solution would be restricted to my own custom panels. Thanks!
Answer: I'm not sure if it's what you want, but you can add restrictions in the outliner so only visible objects will be visible in the outliner.
Comment: Thanks, I need the objects to be hidden not in the view layer list but in object search panels, I assumed there would be a solution in Blender default UI but for now I'm just OK with having this in my custom panels, and this did give an idea to have an array of objects according to the "selectability" status. I'm not trying to store the object pointer array in my custom class but ran into a few problems but I'll post here if I can get it to work.
Answer: Took a while, I tried making a CollectionProperty containing objects that met my criteria and doing a prop search on it but prop search was not accepting to display those objects. An enumeration based solution seemed like too much of a hack and an overkill. Instead I stumbled upon a solution which lead me to be able to filter objects based on arbitrary criteria, simply by "poll" on a PointerProperty with a type bpy.types.Object, I could have gone with a custom property but to keep it intuitive I used the selectable state of the object.
 compass_object: PointerProperty(
     type=bpy.types.Object,
     name="Target Object",
     description="Select an object to Target",
     poll=selectable_filter
     )

and the filter for the poll was simply:
def selectable_filter(self, object):
    return not object.hide_select

I didn't know poll could be used right in the PointerProperty that you stored the reference to the single object itself. It's counter-intuitive for me but I can understand the design decision now. This doesn't save the clutter from default Blender Panels but at least it gives me a way to filter out unnecessary things in my custom panel.

Hiding objects from search


Piano - Reaching arpeggios in Beethoven's Pathetique 3rd movement measure 107

Question: If I start the piece from a neutral position in relation to my left hand I find that when I get to the arpeggios in measure 107 I can't comfortably reach them with my right hand. If I start the piece seated further to the left then parts of the beginning movement place uncomfortable stress on my left wrist in certain places (measure 3 for example). How do people deal with staying neutral with the wrist when the piece moves all over the keyboard like this?
Comment: Assuming you are an adult and don't have extremely short arms - you are sitting the wrong distance from the keyboard - either too close so that your body is in the way of your right arm, or too far so that your right arm can't reach those notes.
Answer: Body position
Sitting so that your body is (more or less) centered on the keyboard is best. I cheat very slightly to the right, because that's comfortable for me.
To play the passage in mm. 107-108, I lean out quite far to the left (lean, but not shift where I'm seated) and step my left foot out to help keep my balance. I keep my body square to the keyboard (no twisting), so stepping out is essential for me.
Hand position #1
My right-hand thumb is placed near the leading edge of the key, while my right-hand pinky is closer to the fall board. This allows me to keep my arm/wrist position fairly straight. It's also important to let the hand (the thumb, in particular) contract as the arpeggio is played — don't try to keep all the fingers on their respective notes.

Another option is to play the initial right-hand Gs with the thumb of the left hand. That allows the right hand to be in a more relaxed position to play the other notes of the arpeggio. Note also the wrist is a bit straighter in this position.

Hand position #2
A variation on the above (playing the G octave with the left hand, and the remaining three arpeggio notes with the right) is to change the right-hand fingering from 1 2 5 to 2 3 5. This allows for a hand position that stays on the wide part of the white keys, rather than placing the fingers toward the fall board, between the black and white keys. It also allows for the straightest arm/wrist alignment.
Comment: I can't play between the keys at all so that position won't work for me. My fingers don't fit between the keys and drag down the surrounding keys when I try.
Comment: @Saemund I've added an alternative to keep your fingers on the wide part of the white keys.


What's the opposite word of "fluent"?

Question: I have searched and found "influent" and "unfluent", but I cannot find both of them in Merriam-Webster Dictionary and Collins. Or maybe there isn't a word adding a prefix to fluent that is the opposite at all? Which words can be alternates then?
Answer: If you are speaking about fluency in a language, we would not likely say 'unfluent'.
Antonyms of words usually take something to a negative degree, rather than a reduced one. For example, 'unsafe' can actually mean something is dangerous, so you wouldn't use it to simply mean something didn't have the highest degree of safety.
Someone who has some grasp of a language might not be "fluent", but we would probably just say they were "not fluent" or, if they were progressing, "not yet fluent".
Other terms do exist for language spoken in a non-fluent way, such as "broken [language]", eg "they speak broken English". Sometimes the word "conversational" is used to describe a level of language competence at which you can hold a conversation with a native speaker, so you could say "I speak English but I am not yet conversational". Borrowing from the name of this site, you could also say "I'm learning English" to indicate you might not yet be fluent.
Comment: If someone's spoken command of a language is decidely not fluent, we can say that it is [halting](https://dictionary.cambridge.org/dictionary/english/halting)
Comment: That should be `decidedly`
Comment: Actually, you use one possibility in your answer: **non-fluent**, which [we use with some frequency right here at ELL](https://www.google.com/search?q=%22non-fluent%22+site%3Aell.stackexchange.com).

What's the opposite word of "fluent"？


Causative verbs: Can we say "She went into the kitchen to have got dinner ready"?

Question: Can we use 'have got something done/adjective'. I understand this sentence: 'She went to the kitchen to get dinner ready'. But 'to have got dinner ready' seems strange for me.
Comment: The title of your question asks about causative verbs. A version of your sentence using "_have_" causatively moves "_got_" one place to the right: _She went into the kitchen to have dinner got ready_. This is feasible if she is the manager of a hotel and wants her chefs to start preparing dinner.
Comment: I see you're using single quotation marks, which is indicative of British English, so is your use of 'got'. In British English, there is no word 'gotten'. 'Gotten' is an Americanism. Brits say 'got' where Yanks say 'gotten'. So answerers to this question should be versed in British English, or, ideally, be actual Brits.
Answer: No, we can't say that, because it would mean "She went into the kitchen in order to have [already] prepared dinner", which makes no sense.
However, we could say "She was glad to have got her work done early, because it meant that she had plenty of time to get ready to go out." (This is speaking of her thoughts after doing the work.)
Comment: Or *she* could say ***I want / intend / plan / hope** to have got dinner ready by 6 o'clock [so I can watch TV for an hour before we eat at 7]*. That's still speaking of her thoughts ***before*** doing the work.


How to Buy Schladerer Kirschwasser in Frankfurt, Germany?

Question: I will visit Frankfurt (Germany) in this August and I want to buy two bottles of Schladerer Kirschwasser (alcohol, cherry brandy) near Frankfurt Main. Since I plan to go back to my country from Italy, I have no chance visiting the duty-free store which sells Schladerer in Frankfurt airport. Is there any store sales Schladerer Kirschwasser in Frankfurt?
Comment: You probably already know this but just in case: Kirschwasser is a common type of fruit brandy in South Germany/Switzerland/Austria/Alsace. You can find cheap ones in every supermarket and various premium brands in many wine shops, delicatessen (in the European sense) or upscale department stores. Not sure how you would track down products from a specific distillery (call them?), does it need to be Schladerer's?
Comment: Alternatively, if you are staying long enough in Germany or already have an address there, you can easily order online.
Comment: @Relaxed
Thanks a lot for your introducing. For using in cocktail, I prefer Schladerer's Kirschwasser. I'd appreciate it if you recommend other brands. It's a pity that I can only find the pre-order service from the duty-free store in Frankfurt airport. I will keep searching the location of the supermarkets in Frankfurt and check if there is Schladerer's Kirschwasser.
Comment: @PedisonKao I don't know Schladerer so I wouldn't know what to recommend. I personally like [Etter](http://www.etter-distillerie.ch/) for cocktails because their Kirsch is somewhat more fruity with less of a bitter burning aftertaste than most others I have tried, without being sweet (it's still a cherry brandy, not a liqueur). I doubt you would find either in supermarkets.
Answer: Since you are looking for products from a specific distillery or possibly advice on premium brandy, I don't think you would be well-served by supermarkets like Hit, Marktkauf, Real or Rewe. You need to track down a specialist shop.
Searches for "Kirschwasser" or "Obstbrände" (fruit brandy) did not yield anything useful but looking for "Spirituose" on gelbeseiten.de returns a few promising results (I can't personally vouch for any of them).
Alternatively, you might also try a large upscale department store. I don't know Frankfurt very well so I might forget a local institution like KaDeWe in Berlin but I would try Karstadt or Galeria Kaufhof.
Following a comment by @GayotFow: There is also a permanent market called the Kleinmarkthalle where some merchants offer various fruit brandies.
In all cases, your odds of finding Schladerer products do not seem very high but you should at least find some other premium cherry brandy and, with a bit of luck, someone who could advise you on the best substitution. If you are feeling adventurous and since you plan to buy two bottles, you could even try two different distilleries!
Comment: +1, but honestly...  Please add Kleinmarkthalle.  That's what a native of Frankfurt (am Main) would instantly say...  All those kiosks of specialty schnapps and liquors and what-not make it an unquestioned favourite!
Comment: @Relaxed
Sincerely thank you for your assistance. With your advices, I have a clear direction to find them. I will share the good news if any one of store replying me that it is in stock there. :)
Comment: @GayotFow
Maybe I will be able to find not only Kirschwasser, but also other liquor and spices which are useful for bartender haha. Sincerely thanks!


Do you have to use all four accounts right away for Xbox Live Gold family memberships?

Question: I checked Microsoft's FAQ for the Xbox live gold family pack, and browsed on here for a  little while, but can't seem to find the answer to my question.  My wife and I both have Xbox consoles, and I was wondering if I bought the family pack, do I have to add four different accounts right away, or if my wife and I could both use two memberships. So we would both have 24 months total.  I know this is probably not the case because Microsoft probably would not allow that, but I just thought I'd ask.
Comment: Can you please edit the description to clarify the "or if I we could" part, and elaborate on your question about using two memberships?
Comment: sorry about the typo... I just meant could I double up on two of the memberships. Like could I use two and my wife use two.  Like 24 months right away.  But I guess they all start counting down right away.  So by the time I needed the other membership it would already be expired.
Answer: The memberships in the gold pack all start on the date of purchase. You don't have to assign them all at once, but the timer is ticking as soon as you buy.
Unfortunately, the only place that they tell you this is one small line on the this page:

Note Your Gold Family Pack membership starts on date of your purchase. Your credit card is charged immediately, after any discounts are applied

If you need to add somebody after the fact, this page should help you out. Even if you only need two of the memberships, it's still a better deal than buying them full price, but the unique billing system for them might make it worth just buying two of them.
Comment: OK thank you very much. That was very helpful because I couldn't find that info anywhere on Microsoft's website... go figure.  Any way I'll probably just wait until I find a 12 month membership on sale for $40.  They do that every couple of months.


Transporting fragile ceramics in carry-on with Ryanair

Question: I have 16 Ceramics plates and Ceramics drinking set (9.5 kg), can I carry  them from Belgium to France as hand-luggage on a flight? I am flying with Ryanair. Below are a few pictures of the items.
Comment: Um, that's a statement, not a question. What do you want to ask?
Comment: Probably but wouldn't taking a train be easier and less risky?
Comment: Thanks, for your answers. I will probably flight with Ryanair (10 kg 55cm x 40cm x 20cm, plus 1 small bag 35 x 20 x 20). Ryanair Baggage policy (https://goo.gl/t5FCqR). @TheMathemagician: I had think about, but it is way more expensive and longer. I will go to southern France.
Comment: When you book early, train in France are not that expensive and when you go over the weight/size limits with Ryanair you pay quite a bit more than the basic ticket. Left is the time. Check out how long it takes, including the time needed to travel to and from the airports, you might be surprised.
Comment: Can I carry 16 Ceramics plates and Ceramics drinking set (9.5 kg) from Belgium to France by hand-luggage during a flight ?
Comment: x @Michael: Probably -- if you have a bag that you're comfortable with transporting them in, and it fits within the size limit for cabin baggage. I'm not aware of any airline that applies other rules to ceramics than they do to other items in cabin baggage.
Comment: 9.5 kg might be over your hand luggage allowance though. You should check that first, if not you might be forced to check them in at the gate.
Comment: Who are you flying with?
Comment: I have transported ceramics during flights, also in the last few years. And yes, in hand luggage. The number of items should not be a problem, but the whole set might make your hand luggage overweight.
Answer: Prohibited Items? Probably Not.
Ceramic dishes shouldn't qualify as forbidden items, according to Ryanair's Terms and Conditions, which state:

Q: What items are prohibited onboard a Ryanair flight?
You cannot bring the following items onboard a Ryanair flight or in airport security restricted areas in the airport:

Guns, Firearms or similar weapons
Pointed/edged Weapons & Sharp Objects
Blunt Instruments: any blunt instrument capable of causing injury, this includes some sporting equipment such as tennis rackets and baseball bats
Explosives and flammable substances: any explosive or highly combustible substance which poses a risk to the health of passengers and crew or the security/safety of aircraft or property.
Chemical and Toxic Substances: any chemical or toxic substances which pose a risk to the health of passengers and crew or the security/ safety of aircraft or property

The carriage of liquids, aerosols and gels into the security restricted area of an airport and onboard aircraft is controlled in accordance with current EU Security Requirements.

More details on items prohibited onboard Ryanair flights can be found on the Terms and Conditions webpage here.
How about Carry-On Size and Weight?
Your real worry should be the size and weight of your carry-on luggage. According to Ryanair Terms and Conditions:

Q: What cabin baggage can I carry?
You can carry one cabin bag weighing up to 10 kg with maximum dimensions of 55cm x 40cm x 20cm, plus 1 small bag up to 35 x 20 x 20 onboard the aircraft.
Due to cabin space limitations only 90 large cabin bags (55 x 40 x 20 cms) can be carried in the cabin, any bags remaining will be carried free of charge in the aircraft hold.
Passengers who have purchased Priority Boarding will not be asked to place their cabin bag in the aircraft hold, unless necessary due to operational reasons.

All the information you need is in the quoted text above. You have an allowance of 55cm x 40cm x 20cm in which you can fit a maximum of 10kg. In terms of size you should be fine, provided you pack the dishes as compactly as possible. The real question is the weight. You mention the whole set weighing 9.5kg which leaves you 0.5kg for padding and bubble-wrap. That might be on the short side, depending on how fragile these dishes really are.
Finally, you'll want to minimise the chances of having your hand luggage placed in the cargo hold upon boarding. Ideally you'd want to pay extra for Priority Boarding, as suggested in the T&C quoted above, and make sure you are one of the first to board the aircraft. The assumption is that, if only 90 pieces of large hand-luggage are allowed on board, you'll want to avoid being the 91st in line for boarding the plane.
Book an Extra Seat
Since we are talking about fragile items you don't wish to pack in the cargo hold, you could think of booking an extra seat for them. Indeed Ryanair allows its passengers to do so:

8.7 Unchecked baggage
[...]
8.7.2  Objects which we deem unsuitable for carriage in the aircraft hold (such as delicate but small musical instruments, wedding dresses, hat boxes, etc.), and which do not meet the requirements set out in Article 8.7.1 above, may nevertheless be accepted for carriage in the cabin if they can be safely and conveniently secured into an extra seat which you have purchased for the specific purpose of same. To book an extra seat for such an item the word "ITEM SEAT" must be entered as the last name and "EXTRA" entered as the first name. EXTRA ITEM SEAT will then be displayed both in the reservation and on the on-line Boarding Pass. The accompanying passenger's travel document details must be entered during the on-line check-in process. There is no checked or cabin baggage allowance associated with the purchase of an extra seat.

This solution is likely to be the most expensive, although this really depends on the value of the fragile items you are carrying.


Why does Moses speak in first person in Deuteronomy?

Question: The Book of Genesis does not mention Moses but in the middle 3 books Moses as the main protagonist and prophet is referred to in third person. In Deuteronomy however Moses speaks in first person mainly. Why the switch?
Comment: Interesting observation and question. For Genesis: because Moses was (just) compilator/redactor/editor. For Deutoronomy: ?
Answer: Technically, Deuteronomy is written in third person.

The first five verses are in third person, ending with "Moses began to expound this law, saying:"
Moses speaks from chapter 2 through chapter 30, and the main narration begins again with chapter 31 with occasional dialogue
Moses recites a poem/song in chapter 32:1-43, and then the narration begins again in verse 44
In chapter 33, Moses blesses each tribe of Israel, and each blessing has a narrative, third person header.
Chapter 34 is all third person narration

So, to sum up, Deuteronomy is technically written in third person, but it seems like first person because it records Moses' last words.
Comment: My point wasn't to find exceptions to the first person, but rather that Deuteronomy is 3rd person narrative, but about 80%--90% or so of that narrative records Moses speaking to Israel.  By contrast, Nehemiah would be a book that is actually written in first person.  Parts of Daniel are also first person narrative.  There is a difference between recorded dialogue (even if it's one-sided) and first person narrative.
Comment: I agree with yoou that there are large sections of Deuteronomy in 3rd person. However the vast majority is still first person which is not the case by the other books. But you make a good point that there is no narrative in the middle which might be the beginnings of answer
Answer: Deutoronomy or Debarim (The Words) is, what Moses spoke to Israel towards the end of their travels through the wildernis and deserts of Arabia, and it were his final words to them before he died and before they entered the land.
So much of it is direct speech it would have been unnatural, had he spoken of himself in third person after all these (almost 40 years). Moses - I believe - was not in danger anymore that he would transgress by exalting himself the way it had happened when he and Aaron had exalted themselves before Israel at Meriba.
Answer: I don't agree with all the statements in the question, and I don't believe that there is a big switch.
First of all, consider this example as a starting point. Let's imagine that we are researching Martin Luther King's famous "I have a dream" speech. We can easily imagine different renditions of the speech:

I have a dream... We might read the exact words that King spoke, if we had access to his sermon notes. They are in the first person because of course King himself wrote them for his own use.
Yesterday Reverend King preached a magnificent sermon on racial justice. Here's the complete text of his speech: "I have a dream..." We might be reading a pamphlet handed out by King's supporters to reinforce his message. Here the pamphlet is in the 3rd person, but within that is the exact text, set in the 1st person because it's quoting King who was of course speaking in the 1st person.
Yesterday Reverend King preached a passionate sermon at the Washington monument, in which he spoke of the dream he had for a home in which his children were able to experience true racial equality... We might read words like this in a newspaper report. The report doesn't quote King's words, but gives a general summary of the speech and its contents. Here King's message is in the 3rd person because it's part of the overall report set in the 3rd person. (King spoke and said that he had a dream...)

Now let's consider Moses' story. I think we can without too much trouble see how this basic idea applies.

First person:

This form of writing doesn't apply in any of the first five books.

Third person incorporating first person quotes:

Clearly this describes Deuteronomy. No matter what opinion we have about the authorship of the Torah, in its final form Deuteronomy is a writing where Moses' words are quoted in the first person but set in a third person framework. James Dunn in his answer gives a good outline of that framework.
But it's important to see that exactly the same writing style is used elsewhere. It's not limited to Deuteronomy. Consider for example Exodus 20, which records preparations for receiving the Law. Overall it is written as a third person account. But many of the spoken parts are recorded as direct first person speech. God's words in particular are all expressed in the first person. (See verses 3-6, 9-13, 21-2, 24.) And of course, the 10 commands follow the same pattern: A third person framework for the first person commands.

Third person reporting:

Throughout the Torah, we see this pattern, where for example Moses' words are not quoted directly but are summarised. This too happens in Exodus 20: See for example verses 20-25:

The Lord calls Moses to the top of the mountain. Actual words not recorded.
God tells Moses to prepare the people. Actual words are stated.
Moses reminds God the people cannot come up the mountain because it is holy. Actual words spoken. (Perhaps as a signal of the importance of those words about God's holiness.)
God sends Moses down the mountain to prepare the people (v24). Actual words spoken.
Moses went down and told the people. Here that single word is third person reporting. Its meaning is defined entirely by the quoted words of God in the previous verses.

So: Is there a switch from the earlier books when we get to Deuteronomy? I don't believe so. It's certainly true that the first person language is more extensive than in other books, but that's only because Moses' sermon is more extensive. There are more words.
As a final picture of the similarities, read the parallel versions of the 10 commandments in Exodus 20 and Deuteronomy 5. You will see clearly that while some details are different, the overall structure is identical. In Exodus there is a narrator who quotes what God said, and those words are first person. In Deuteronomy there is another level, because the narrator quotes Moses quoting God. but other that that, the commands themselves are all in the first person. The only changes are those necessary to reflect the slightly different perspective of the storyline.
Answer: Well there are parts in Deuteronomy where moses explicitly says "I" not just his last words. Here is an example; Deuteronomy 10:10: "I, moreover, stayed on the mountain forty days and forty nights like the first time, and the Lord listened to me that time also; the Lord was not willing to destroy you."
Comment: Welcome to Biblical Hermeneutics! and thank you for your contribution. While true, this doesn't actually explain **why** Moses spoke in the first person.
 When you get a chance, please take the [tour] to understand how the site works and [how it is different than others](https://hermeneutics.meta.stackexchange.com/questions/653/how-can-we-educate-new-users-about-our-site-distinctives/803#803).
Answer: Most of Deuteronomy is spoken in first person. It appears to me that Deuteronomy is a series of writings written directly by Moses in first person.
Since I base my understanding solely on the scriptures themselves, I admittedly need to do a lot of research.
The first of these writings would be from 1:6 to 4:40, (note the natural beginning and ending). Then scribes interjected introductions and brief narratives between the writings of Moses.
I've always been taught with no debate (or evidence either way) that Moses wrote the Pentateuch in its entirety. Some of this Moses wrote directly, some he also recited to the people (5:1b -5:33), while some he possibly spoke and the words were recorded.
My very rough writer-outline would be as follows;

Deuteronomy
writer

1:1 to 1:5
scribe

1:6 to 4:40
Moses

4:41 to 5:1a
scribe

5:1b to 5:33
Moses (written by and recited by Moses to the people)

6:1 to 26:19
Moses

27:1 to 27:11
scribe (as stenographer to Moses and elders)

27:12 to 28:69
Moses

29:1 to 29:2a
scribe

29:2b to 30:20
Moses

31:1  to 31:2a
scribe

31:2b to 31:30
scribe (as stenographer Moses)

After these, there are the song and blessing which Moses wrote himself but without the introductions to them. And then the narration of Moses' death and burial.
I don't think the fact that the scribes may have written the introductory words in Deuteronomy takes away the inerrancy of God's holy Word at all.
Comment: Welcome to Biblical Hermeneutics! and thank you for your contribution. When you get a chance, please take the [tour] to understand how the site works and [how it is different than others](https://hermeneutics.meta.stackexchange.com/questions/653/how-can-we-educate-new-users-about-our-site-distinctives/803#803). I also recommend going through the [Help Center's](https://hermeneutics.stackexchange.com/help) sections on both asking and answering questions.
Answer: The traditional explanation for the change of voice in Deuteronomy is that it is a "second telling" of the Torah, this time in the first person. According to the ESV Study Bible:

Deuteronomy, the final book in the Pentateuch, contains Moses' last
three sermons and two prophetic poems about Israel's future.
Reflecting on the nation's past mistakes, Moses urges the people not
to repeat those errors when they enter the Promised Land. Possessing
Canaan will fulfill the promises made to the patriarchs, but if the
people fall into idolatry or fail to keep the law, they will be
exiled.

Critical scholarship, on the other hand, sees the change of voice as resulting from a new author. According the the Bible Study published by Yale Divinity School:

The book of Deuteronomy was written much later than the time of Moses.
There are many parallels between the wording and content found in
Deuteronomy's laws and 2 Kings. According to 2 Kings, a book of God's
law was "rediscovered" in the temple early during the reign of King
Josiah. The young king then "tears his clothes," laments that the
Israelites had not been keeping these laws, and begins to tear down
all the "high places" as his first act of reform.

The editors of the New American Bible Revised Edition, published by the U.S. Council of Catholic Bishops, take a similar stance:

The book was probably composed over the course of three centuries,
from the eighth century to the exile and beyond. It bears some
relation to "the Book of the Law" discovered in the Jerusalem Temple
around 622 B.C. during the reign of King Josiah (2 Kgs 22:8–13). It
gives evidence of later editing: cf. the references to exile in
4:1–40; 28:63–68; 29:21–28; 30:1–10.

Conclusion: the two most widely accepted explanations for the switch to the first person singular in the Book of Deuteronomy are: 1) here it is Moses who, nearing the end of his life, narrates and preaches from his own perspective or 2) Deuteronomy comes from a different author than the previous books.


How can I add insulation above my finished ceiling?

Question: What is the cheapest option for adding insulation above a finished ceiling? There has never been any in the spot that I need it. Should I take the roof off or have it sprayed in? The space is 20 feet long and 9 feet 9 inches wide.
Comment: It is somewhat unlikely that taking off the roof will be the least expensive option.
Comment: Please add more details so we can better answer your question. Do you not have attic access to add more insulation?
Answer: Depends on construction details. if it's merely "the contractor was too cheap to provide attic access" (a very typical issue of cheesy contractors), you cut a hole and put in access, then apply insulation as you like. If it's a cathedral ceiling sort of arrangement (roof deck on one side of rafters, ceiling on the other) then some sort of spray/blown insulation (might be foam, might be cellulose, might be fiberglass but I would not go there based on published research results) is the most likely option, though not the only option. If you are considering "taking off the roof" then it's usually more cost-effective (labor cost, mostly) to leave it in place & build on top of the current roof with a layer of insulation, for instance.
Comment: The "cheapest way to insulate" is essentially never "taking the roof off." Blown-in cellulose will be far more cost effective in the current space.
Comment: this room was a garages an I made it into a family room  its a two story house  an this is the part that's on first floor with just the roof I also put a fireplace in though that roof an there's no insolation in it  I loss all my heat so I wanted to put insolation in I do need a roof in the next few years so I think I will just take the roof off an sheeting an do it that way in stand of blowing it in  I just wanted to know if that was the cheeps way .....


CV and/or resume for PhD Student with industry experience?

Question: I spent 10+ years in industry before going back to grad school to pursue a PhD, and therefore I have extensive industry experience, as well as ongoing academic work.
Is there a good way to represent this on my CV? Does anyone know a good CV format or template that would allow me to show this?
Comment: I have a section titled "Other Experience" for my non-academic work (both pre-PhD and after) that is substantively related to my field of study, but not actually academic work
Comment: what type of work did you do in industry? Was it R&D, production, sales & marketing? Also, what field is this?
Comment: @Burak the industry was marine engineering, specifically in operations. I also have a pre-grad school academic career, also in marine engineering.
Comment: It depends what you're applying for - for industry jobs, you probably want reverse-chronological order so the PhD would get top billing followed by the job, with some specifics related to the PhD later on.  For an academic CV the old job would be much less important and would probably fall off the first page.
Answer: I would say there are a couple ways to attack this. You could list academic experience as a separate section to industry experience, this would show that you consider them very separate.
You could also make a section titled " (Relevant) Experience" and list everything you have in chronological order. This would give the impression to whoever is reading it that you consider all of your experience relevant in the position that you are applying to.
In either case, make sure you highlight the relevant portions of your background to the position you are applying.
Comment: That's a useful suggestion, thank you very much for your input.
Answer: In a standard C.V., there is a section where you list all of the professional positions that you have held, typically newest to oldest.  You can simply include your industry work in that section.
If you feel that your work experience is particularly relevant to your aims in graduate school, I would recommend highlighting it strongly in other parts of your application outside of your C.V.  For example, you may discuss it in your research statement, one of your references may be one of your supervisors, etc.


Difference between linking to specific page or folder

Question: Is there a difference between linking to www.example.com/site/index.html and www.example.com/site/ since it'll point to the same page?
I point everything i can to a folder on my website, i just think it looks better when the browser doesn't display the name of the file.
Is this wrong, right, good or bad?
Answer: It's better to link to the folder

If sometimes you link to www.example.com/site/index.html and other times to www.example.com/site/ you will end up with a spitted pagerank

If you link to a page instead of a folder

It's harder to remember. (was it www.example.com/contact or www.example.com/contactUs.html?)
It looks ugly as hell
You are exposing the technology behind the page (index.php, index.asp, etc) and if later you decide to switch you will have a hell of a time mapping the old urls to the new ones
Comment: Thanks. My usage was only based on what you specified as "ugly as hell", and i share definitely that thought!
I just didn't know if perhaps on a SEO point of view it was a bad practice. Any thoughts on that?
Comment: With the spited pagerang I was referring to the SEO. For the user it will be the same. But for the crawlers, they're two different pages.
Comment: Well here's my question: Say your page uses URL parameters. Couldn't it be considered more ugly to use a file-less URL in those cases? For example, site.com/blog/?id=123 Looks a lot worse to me than site.com/blog/index.php?id=123 (That might just be because I'm conditioned to seeing a file go along with parameters.)
Comment: You always can do site.com/blog/123
Answer:
www.example.com/site/index.html and www.example.com/site/

Pointing to the bare directory, without the directory index, is prefered.
Although the same content might be displayed on your server, these are different URLs. Search engines will see these two URLs as different and might perceive this as duplicate content if both these URLs are used on your site, or in-bound links go to both. Only "www.example.com/site/" should be used (it's cleaner) and ".../index.html" should redirect to ".../". The actual file returned when you request "www.example.com/site/" is dependent on your server and the value of the DirectoryIndex directive (Apache). It could be anything you like, not necessarily "index.html".
From an SEO point of view it is only "bad" if you mix the two and both are accessible.
Comment: So you're saying i should redirect /index.html to / ? Wouldn't that create some sort of bug since / finds the index of the folder automatically? If i should redirect, where, on .htaccess?
Comment: As an update, index.html is definitely accessible, but i never link to it.
Comment: Yes, you certainly have to be careful about a redirect loop in this instance. See my answer on this thread for example code: http://webmasters.stackexchange.com/a/35099/1243


What is the unit of the current in a square barrier model?

Question: In Quantum Mechanics textbooks, the equation for a electron tunneling through a barrier is
$$-\frac{\hbar ^{2}}{2m}\frac{d^{2}}{dx^{2}}\psi \left( x\right) +U\psi \left(x\right) =E\psi \left( x\right).$$
In numerical computations, we choose $E_{0}=\hbar ^{2}/2ma^{2}$ as a reduced energy, then these parameters change into: $\overline{x}\rightarrow x/a$, $\overline{E}\rightarrow E/E_{0}$, $\overline{U}\rightarrow U/E_{0}$, and the corresponding equation becomes
$$-\frac{d^{2}}{d\overline{x}^{2}}\psi \left( \overline{x}\right) +\overline{U}\psi \left( \overline{x}\right) =\overline{E}\psi \left( \overline{x}\right).$$
After we obtain the wave function $\psi \left(x \right)$, the current density can be calculated by
$$J=\frac{-i\hbar }{2m}\left[ \psi ^{\ast }\nabla \psi -\psi \nabla \psi^{\ast }\right].$$
If we plot the curve of current density and $x$, what is the unit of the current density?
Comment: Welcome to Physics.SE!  Because of the question-and-answer format of the board, it's best to avoid asking multiple questions in the same post.  I would recommend that you split out your question about the bias voltage and ask it as its own separate question.
Comment: AFAIK current is measured in Ampères, or mA etc
Comment: In experiments that is exactly the truth. What about theoritical models?
Answer: In standard units, the quantity $\hat{\mathbf{J}} = \frac{1}{2m} (\psi^* \hat{\mathbf{p}} \psi - \psi \hat{\mathbf{p}} \psi^*)$ is a probability current, which has the same units as a number flux.  Its units depend on the number of dimensions you're working in, since you need to integrate it over a closed surface to obtain something with the units of $\text{s}^{-1}$ (i.e., particles per unit of time.)  In general, if you're working in a $D$-dimensional problem, then the units will be $\text{s}^{-1} \text{m}^{-(D-1)}$.
Note that if you multiply the probability/number current by the charge on each carrier, you will obtain the charge current density.  If the carrier charge is expressed in coulombs, then this will have units of $\text{C/(s} \cdot \text{m}^{D-1}) = \text{A/m}^{D-1}$, as expected.
Comment: Thank you for your answer! I get your point. Basically the units of current and voltage are Ampere $\mathbf{A}$ and Volt $V$, respectively, and the magnitudes differ under different conditions. But in a theoretical model or a numerical simulation, if one wants to plot the curve of current-voltage characteristics, the data may be handled, and the units should be stated. So, how can we write down the explicit expression of the units based on the above equation with different reduced quantities? I mean, how can we know the specific dependence of the current on a certain reduced quantity?


4x400 m relay race

Question: For 4x100 m and 4x200 m races, the respective lanes for teams are fixed. It was seen during the heats of 4x400 m in Tokyo 2020 olympics that in few cases, there was lot of confusion during change of baton. Few racers had to run a little wider to avoid jostling and that costs time. It can easily be resolved if the lanes are fixed for each team. Why has it not been considered?
Answer: Your question is based on a false premise. This has of course been considered, and rejected for a very good reason: the outer lanes are longer than the inner lanes.
For the 4x100m, this isn't an issue - the difference isn't that big when running one lap of the track, and the same distance is used for a regular 400m race anyway.
For the 4x200m, the stagger has to be doubled, and you're already in a state when the outer lane has to pretty much start at the end of the first bend in order to equalise the distances. This already makes it hard for spectators to get a good idea of which team is actually leading at any point due to the large spatial distances between teams when they handover.
If you now tried the same for the 4x400m, you'd have to double the stagger again and you'd end up with the team in the outer lane starting somewhere around about the start of the second bend (i.e. what is the end of the back straight for the team in the inner lane). This would be getting silly, so instead teams break after the first 500m.

4x400 m relay race


How can I transfer my World of Goo save file from Android to PC?

Question: I've been playing World of Goo lately on Android, and have gotten OCD on most of the maps. I'd like to finish off the rest of the maps on Steam so I can unlock the achievements there.
How can I transfer my World of Goo save file from Android to PC?
Answer: You can't unfortunately. Sorry about that.
Comment: @Russ Whitchurch if this is the answer your looking for please accept it or tell me what I can do to make it better.
Answer: Actually, you most likely can do that. I managed to move the savegame the other way around (from linux to android) and it went well. You might need to have root access though.
I wrote this guide on transferring the linux savegame to android, but I imagne you can do it the other way around as long as you have the right folders in place and whatnot:

Here's a short guide on how I did the transfer:

First of all, find your savefile on your computer. Detailed instructions on where you can find your savefile are in this link:
  http://goofans.com/developers/game-file-formats/profile-file-format
Once you've found your savefile (which is named pers2.dat), copy it anywhere to your android phone.
Make a backup of your existing savefile just in case things goes haywire, its located on the phone at this folder:

/datadata/com.twodboy.worldofgoofull/files/pers2.dat
Though the phones console, I did the backup through these commands
cd /datadata/com.twodboy.worldofgoofull/files/ mv pers2.dat
  pers2.dat.backup

Copy your desktop savegame into /datadata/com.twodboy.worldofgoofull/files/ and make sure its named
  pers2.dat (mind the lowercase).

I did a transfer from my linux native world of goo savegame into the
  phone and it worked fine, no need to change permissions, Ipad
  decryption or anything. My phone is rooted and I did this whole thing
  through webkeys web interface - however I doubt that rooting is
  required in order to do this. This is one way of doing it and I'm sure
  you will find an easier way.

The whole thread is located here:
http://goofans.com/forum/world-of-goo/general-discussion/3142
Do note that it was written five years ago, and that I can't help you more than whats written there :-)


What is Spell DC?

Question: My group is new to table top RPGs, and one thing we haven't figured out is Spell DC.
One player was a cleric, and channel energy does force the undead monsters to make a saving throw, but I don't think that is Spell DC. So what is Spell DC, and what does it do? Does it mean the enemy can do a saving throw against the DC to determine whether the spell hits? If that's the case, does melee or ranged attacks have a similar DC?
I did a simple search that told me Spell DC is calculated by spell level + 1/2  class level + WIS for cleric or INT for wizard. Is that right?
Comment: No, there is not DC for melee/ranged attacks. Generally, each attack/spell gets one d20 roll. Either by the attacker to hit a target number (melee, range, & touch attacks/spells) or the defender to resist the effects of the attack (saving throws against spells and abilities).
Comment: Welcome to RPG.SE! Good question! I fixed some of your formatting (line breaks not showing) and removed Pathfinder from the title, since putting it in the tags is good enough.
Answer: Spell DC is a property of all spells, but usually only comes into play when the spell has a saving throw. You see saving throws mostly on spells that do not have an attack roll. These spells usually automatically hit, but give the target a chance to overcome some or all of the spells effects by making a saving throw. The DC of the spell is the target number for the saving throw.
To calculate the Spell DC:

10 + spell level + ability modifier (e.g. Wizards use INT, Clerics use WIS, Bards use CHA)

Spell DC differs from the DC related to Ex (extraordinary) and Su (supernatural) abilities, like the Cleric's channel energy ability. To calculate the DC for these abilities use the formula:

10 + 1/2 level + ability modifier
Comment: It should be noted that the Spell DC is only relevant for spells that have a Saving Throw. This will be in the stat block for the spell. See http://www.d20pfsrd.com/magic#TOC-Saving-Throw
Comment: @TREE, that is not completely true. See the section about making concentration checks after being affected by a spell: http://www.d20pfsrd.com/magic#TOC-Concentration
Answer: DC stands for difficulty class. Anytime your character performs an action that doesn't have a guaranteed success, you need to check (usually skill) for success. The result of the check has to be equal to or greater than the DC of the action being performed to succeed.
The calculation for a spell is 10 + spell level + ability modifier. To clarify for spell use - This is what establishes the DC for the save of the spell. This is what the target of the spell has to meet or exceed to qualify for any saves (Such as half damage or similar).
Comment: I'd just add: in relation to this question, not only your character, any character, and not just checks (saves are not checks)
Answer: DC Stands for Difficulty Class, and it represents the difficulty in either resisting, avoiding, or succumbing to the effects of a spell. When a spell lists in its descriptions that it requires a "Reflex Save for half" or a "Fort Negates" it means that a Save against the Spells DC must be rolled to avoid the effects of the spell.
In the case of "Reflex Halves" if a character succeeds in a reflex save against the Spell DC, he takes half damage from the spell effects as he's able to avoid the explosion, only get hit by part of the lightning bolt, etc.
If the case is "Fort Negates" it means that the effects of the spell are negated by a successful Fortitude save against the Spell DC. Spells like Poison have effects which you must shrug off with your body instead of your feet.
To calculate your Spell DC use the following Formula:

Spell DC = 10 + Spell Level + Primary Casting modifier ( INT for Psions and Wizards, CHA for Sorcerer's and Bards, WIS for Druids and Clerics )

An interesting thing to note is that you can use the feat Heighten Spell to prepare a spell in a higher level spell slot, which will in turn Increase the Spell DC. For example, with a spell like Glitterdust which is a second level spell, you could prepare it as a 5th level spell to increase the spell DC to make the effects harder to resist.
Alongside spells are also Spell-like abilities which have the (Ex) denoting Extraordinary abilities, or (Su) which indicates a supernatural ability.
The formula for the DC of those spells is slightly different, and is calculated with your level instead of the spells level.

Ex / Su Ability DC = 10 + 1/2 Level + Specified Ability Modifier ( For clerics Channel energy, this is CHA )

The Specified ability modifier can often be found in the ability description of the ability, such as the one for Channel Energy.
Comment: I know this is around 8 years old, but in case anyone else finds this I thought I'd make a correction for posterity's sake.
Extraordinary and Supernatural abilities are not Spell-like abilities.  Spell-like abilities are denoted with the (Sp) notation and are abilities that specifically replicate and act like spells.
Comment: (Su) abilities are supernatural, considered magical (and thus are affected by things such as an Anti-Magic Field), but specifically do NOT act like spells and are not subject to the same rules as (Sp) abilities such as spell resistance and dispelling normally.  (Ex) abilities are extraordinary and are considered non-magical abilities regardless of their effects, they are not affected by things that target or affect magic in any way shape or form.

What is Spell DC?


How are Django channels different than celery?

Question: Recently I came to know about Django channels.
Can somebody tell me the difference between channels and celery, as well as where to use celery and channels.
Answer: Channels in Django are meant for asynchronous handling of requests.

The standard model Django uses is Request-Response but that has significant limitations. We cannot do anything outside the restrictions of that model.

Channels came about to allow Web Socket support and building complex applications around Web Sockets, so that we can send multiple messages, manage sessions, etc.

Celery is a completely different thing, it is an asynchronous task queue/job queue based on distributed message passing. It is primarily for queuing tasks and scheduling them to run at specific intervals.

Simply put Channels are used when you need asynchronous data communication like a chat application, and Celery is for scheduling tasks and events like a server scraping the web for a certain type of news at fixed intervals.
Comment: Django channels does support background processing. I think the question is more on, how django channels background processing is different from celery workers.
Comment: You said "Celery is a completely different thing". I think from high level perspective they are not completely different. What happens? Input, Processing, Output :-)  See: https://en.wikipedia.org/wiki/IPO_model
Comment: Lets say I want to generate some file that takes 30 seconds, should I use Celery or Channels?
Comment: @johan Celery would be the better for that.
Comment: @Johan but if you wanted to tail a logfile long term and feed it to your webbrowser client(s) channels is the right way.
Answer:
Channels in Django is for WebSocket, long-poll HTTP.
Celery is for background task, queue.
Answer: Django Channels:

beyond HTTP - to handle WebSockets, chat protocols, IoT protocols, and
  more.

Passes messages between client and server (Full duplex connection)
Handle HTTP and Web-sockets requests
Asynchronous

Example :

Real time chat application
Update social feeds
Multiplayer game
Sending Notifications

Celery :

It's a task queue with focus on real-time processing, while also supporting task scheduling.

Perform long running background tasks
Perform periodic tasks
Asynchronous

Example :

Processing Videos/images
Sending bulk emails

Further reading
Example of Celery and Django Channels
Asynchronous vs Synchronous
Answer: Channels is a project that takes Django and extends its abilities beyond HTTP - to handle Web-sockets, chat protocols, IoT protocols, and more. It's built on a Python specification called ASGI.
Channels changes Django to weave asynchronous code underneath and through Django's synchronous core, allowing Django projects to handle not only HTTP, but protocols that require long-running connections too - WebSockets, MQTT, chatbots, amateur radio, and more.
It does this while preserving Django's synchronous and easy-to-use nature, allowing you to choose how you write your code - synchronous in a style like Django views, fully asynchronous, or a mixture of both. On top of this, it provides integrations with Django's auth system, session system, and more, making it easier than ever to extend your HTTP-only project to other protocols.
It also bundles this event-driven architecture with channel layers, a system that allows you to easily communicate between processes, and separate your project into different processes.
Celery is an asynchronous task queue based on distributed message passing. It provides functionalities to run real-time operations and schedule some tasks to be executed later. These tasks can be executed asynchronous or synchronous, this means you may prefer to run them at the background or chain them to make one task to be fulfilled after the successful execution of an another task.
Answer: Other answers, greatly explained the diff, but in facts Channels & Celery can both do asynchronous pooled tasks in common.
Channels and Celery both use a backend for messages and worker daemon(s). So the same kind of thing could be implemented with both.
But keep in mind that Celery is primary made for and can handle most issue of task pooling (retries, result backend, etc) as it was based on RabbitMQ features, where Channels is absolutely not made for.
Answer: Django channels gives to Django the ability to handle more than just plain HTTP requests, including Websockets and HTTP2. Think of this as 2 way duplex communication that happens asynchronously
No browser refreshing. Multiple clients can send and receive data via websocket and django channels orchestrates this intercommunication example a group chat with simultaneously clients accessing at the same time. You can achieve background processing of long running code simliar to that of a celery to a certain extent, but the application of channels is different to that of celery.
Celery is an asynchronous task queue/job queue based on distributed message passing. As well as scheduling. In layman's terms, I want to fire and run a task in the background or I want to have a periodical task that fires and runs in the back on a set interval. You can also fire task in a synchronous way as well fire and wait until complete and continue.
So the key difference is in the use case they serve and objectives of the frameworks


Translation of Soccer term: disarm

Question: I'm looking for the translation of the soccer term that in Portuguese we use as "disarm". It is the action of taking the ball from the opponent player or when the player with the ball attempts to trick the opponent and loses the ball.
Comment: I'm thinking about accepting Bill's answer as I'm looking more for a noun or adjective rather than a verb (sorry for not mentioning this before). I'm looking for a way to express the **ability** of someone to steal the ball, so I could classify the player in a chart, like "strength = high, speed = low, dribble = high, **tackle** = high"... I'm interested in the differences between UK and USA, I mentioned soccer because I was afraid of someone thinking about American football.
Comment: Challenge could also be what you're looking for. http://www.coachingsoccer101.com/glossary.htm
Comment: @Roberto You may want to consider using *gerunds* to describe the ability: **dribbling**, **tackling**, etc.
Answer: The action of attempting to take the ball from the opponent player is called "tackling".  However, I do not know of any single word describing losing the ball, except for "losing the ball".
Comment: +1 – Using your feet to steal the ball from the opponent is called "tackling". It could be a successful tackle or unsuccessful one. Or a particularly bad one that causes a foul. :)
Comment: Note that the word "tackle" is used in other sports like Aussie Rules and Rugby and, while the aim of the tackle is to "take possession of the ball", it often results in the opponent losing possession of the ball to a penalty or another player.
Answer: "Steal" would be the most appropriate word based on the context you are using it in.
Merriam-Webster's Dictionary lists the following definition when using "steal" as a transitive verb:

a : to seize, gain, or win by trickery, skill, or daring
  b of a base runner : to reach (a base) safely solely by running and usually catching the opposing team off guard

For soccer purposes: "Kaka stole the ball from Beckham and is streaking up field!"
How Kaka came to gain possession of the ball - whether Beckham had lost it while attempting to make a fancy play or if Kaka had simply run up to Beckham and kicked the ball out from under his feet - the result is the same. Beckham had the ball until Kaka took it from him.
Answer: "Steal" is used in American English (which might be what you're after as you asked about "soccer"). In British English, dispossess would be more common.

deprive (a player) of the ball

There is also the phrase "caught in possession", but that describes a player with the ball that didn't notice an approaching opponent who then dispossessed him.
Comment: Your answer is a few seconds younger than my similar one.  Perhaps you could combine the two and then I will delete mine?
Comment: I think "steal" would be more common than "dispossess" in UK as well.
Comment: @Colin I don't agree, it's one of the commentators' favourite words.  It's in the BNC: "Pearce intelligent ball for Phillips back in it goes to Collimore and a header down drops to Crosby Thomson arrives to dispossess him and knocks it first time for Jochim. Good work by Chettle. "
Comment: @z7sg: I'm not a devotee of sports writing (or sports) so I withdraw from the discussion.

Translation of Soccer term: disarm


How do electrons receive energy when a body is heated?

Question: When an object is heated, energy is absorbed by vibration, translation, and rotation of molecules. How does this heating apply to electrons?
Answer: Heating applies to the whole system (nuclei and electrons). However, due to the large difference of mass between nuclei and electrons (larger than 1800), and taking into account that the correct description of the dynamics at atomic level is provided by quantum mechanics (QM), the way a gain of total energy is distributed among different internal degrees of freedom is quite complex.
If translations, rotations and vibrations of molecules could be well approximated by the classical limit of QM, equipartition theorem ensures that at equilibrium the average  energy associated with these motions would be the same for each individual degree of freedom. Already for more complex kind of motions (diffusion, motion of defects) things are more complicated, even at level of classical mechanics.
In the case of electrons, but, in some regime also for vibrations and rotations, QM provides the only correct description of the system. Quantum mechanics allows some sharing of the increment of energy also among quantum degrees of freedom. However in a more constrained way than classical mechanics. Details are system dependent. Just to give an example, in the case of a simple metal like the alkalis, part of the electrons closely follow the ionic motion, thus their presence can be absorbed into an increase of the effective ionic mass. The remaining ones (valence electrons) behave very closely like an ideal Fermi gas: most of them are inert to an increase of energy, but those whose energy is close to the Fermi energy by a few $k_BT$.
Answer: Electrons do play a key role in how heat energy flows across a material, especially the free and mobile electrons in metals where they contributes to the high heat conductivity. When a body without free electrons is heated, the heat energy is transferred from atoms to atoms primarily by mere vibration of the particles within their sphere of freedom, and the intensity of the vibration depends on how much energy is absorbed. The heating also causes the electrons in orbit around nucleuses that gained heat energy to rise to an higher energy level, and as the atoms cool, these electrons return to their ground state, releasing photons in the process in the form of infrared radiation off the material.
In materials with free electrons zooming around, the story is taken a few steps further. The transfer of energy is enhanced and accelerated by these free electrons gaining energy and transferring it farther than just atomic vibration would because there have a limitless sphere of freedom they can explore in the lattice, so they actually transport the energy. Electrons also tend to move away from a region of higher energy to a region of lower energy (like virtually all things do), and this helps orient their direction of motion towards the colder region of the material, thus speeding up the heat transfer.
Answer: In a solid there exist collective vibrations called phonons. There are acoustic phonons in which atoms move as a whole so the density varies. Then there are optical phonons in which valence electrons move in opposite direction to their ions. One can distinguish longitudinal and transverse optical phonons. For reasonable temperatures, that is below melting, it is the phonons that are involved in heating of the solid. Single atomic excitations are relevant to a much higher temperature range.
Comment: You are excluding from your "resonable temperatures" the whole realm of low temperature physics!
Comment: @GiorgioP That is included in "below melting". The point is that atomic degrees of freedom only kick in at temperatures above melting.
Answer: Atomic collisions certainly cause a definite force on the orbitals. If there is a force, then there is a change in parameters, and if there is a change in parameters, there can be an exciting of the orbital.
Comment: The concept of "force on orbitals" is not a clean QM concept. Excitation of orbitals is a completely wrong concept. In a one-particle approximation orbitals are fixed and electrons can be excited.


How much of a PDA can a program control

Question: How much of a PDA is under the control of its owner program? For example, could the program block the account from signing certain instructions on transactions? Or could the program add a fee to every transaction a PDA signs? Whats the limit of control over PDAs and how can you access all features of them on Anchor
Answer: a PDA is limited to how much the program offers in controllability.
To elaborate. Let's say your program has a single instruction initialize that initializes a pda account. In that case, your program cannot change the PDA after it's initialized.
You add an update instruction that updates the PDA data to a certain way. This will offer you the ability to use that instruction to update it. But only in that certain way.
This is great for security because you don't have to worry that a pda might be initialized in a malicious way or it has unvalid data. The pda will only follow the rules of the program. It cannot be updated outside of the program.
Answer: PDA can store DATA and also sign for CPI(Cross program Invocations) for example you have an escrow and you have created a tokenAccount whose authority is a PDA then only the PDA can control the transfer of tokens from that TokenAccount.
Answer: A program only has explicit signing authority over its PDAs, so its control is limited to everything that it can sign.
After that, if your program creates an account at a PDA, then it can control that account as much as any other account that it owns.
Feel free to read through the official documentation on program-derived addresses at https://docs.solana.com/developing/programming-model/calling-between-programs#program-derived-addresses and on account ownership at https://docs.solana.com/developing/programming-model/accounts#ownership-and-assignment-to-programs

How much of a PDA can a program control


how to link a 2.4 blender file to the 2.7 blender version?

Question: I have tried linking older blender files to the newest version of blender and I get a warning saying that it is too old and it will not work with the recent version.
Comment: When I tried appending and linking from a ~.blend file created with version 2.45, I got a slightly different warning message than you relate: "Linking or appending from a very old blend file format (2.45.0), no animation conversion will be done! You may want to re-save your lib file with current Blender". No warning is generated if I open the old version file with the current version of Blender. So that's what I'd do, and then save the file with a new name.
Answer: Have you tried to Save the old blender files into a new blender file?
Try and open a new file in your newest version of blender. Then, just append every file from the Old blender file( of which you have problems linking) to the new blender file. Save that new file, and that should do it! It should work...


When do non-real roots of polynomials P(x) and R(x) have a real component in common?

Question: If $P(x)$ and $R(x)$ have integer coefficients and are irreducible over $\mathbb{Q}$, is there any way to tell if any of their non-real roots share a real part in common, i.e. that a root of one is $a + ib$ and the root of the other is $a + ic$ where $a \ne 0$?
One anecdotal observation that I made while constructing such polynomials was that if $a$ was rational then a factor of the $P'(x)$ and $R'(x)$ was $(x - a)$. But the existence of such a rational factor in the derivative doesn't guarantee that the polynomial has a root with that real part, e.g. $4x^4 - 4x^3 + 8x + 44$ has a factor of 1 in its derivative but has no complex root with a real part of 1. (So could it be that if there is no factor in common between the derivatives that there is no common real part among the non-real roots of the two polynomials?)
It seems like one way we could answer in the negative is to align the two polynomials in some way, e.g. on the values of the roots of their respective $(n-1)$st derivatives, $d_1$ and $d_2$, find the radius of the circles, $C_1(x)$ and $C_2(x)$, which contain the roots of $P(x-d_1)$ and $R(x - d_2)$. If these circles do not overlap when moved to $C_1(x + d_1)$ and $C_2(x + d_2)$ then the roots can't share a common real part. Why this choice of alignment? Because we know that the roots of all higher order derivatives of a polynomial lie within the convex hull that contains the roots of the polynomial (if I read Lemma 2 of Hubbard, Schleicher and Sutherland's 2001 paper correctly). And we know that the $(n-1)$st derivative will always exist and be real so it is a convenient reference point. The root of the $(n-1)$st derivative is $x = -b/(n a)$ where $n$ is the degree of the polynomial, $a$ is the coefficient of $x^n$ and $b$ is the coefficient of $x^{n-1}$ (which might be 0).
The motivation for this question is the desire to sort complex roots by real and imaginary part, e.g. $[a - iA, a + iA, a - iB, a + iB, b - iB, b + iB]$ where $a < b$ and $A < B$. All that is known are polynomial(s) and the rectangles in the complex plane that contains the roots for each polynomial (as generated by the Collins-Krandick algorithm of 2000). If two rectangles are not disjoint then refinement might lead to them being distinguishable in real component (as when the roots have real parts $a$ and $b$)...or may not (as when they share a common real part). It would be nice to know whether the real parts are distinct before attempting iterative refinement.

Here is an implementation of the solution suggested by @dxiv using SymPy
<code>def samere(p, r):
  def res(p):
    a, b = var('a b', real=True)
    p1a, p1b = p.subs(x, a + I*b).as_real_imag()
    return Poly(p1a, b).resultant(Poly(p1b, b))
  g = Poly(res(p)).gcd(Poly(res(r)))
  if g.degree() > 0:
    return set(g.real_roots())

>>> p
x**4 - 8*x**3 + 26*x**2 - 40*x + 13
>>> r
x**4 - 8*x**3 + 30*x**2 - 56*x + 29
>>> samere(p, r)
{2}
>>> [i.n(2) for i in Poly(p).all_roots()]
[0.43, 3.6, 2.0 - 2.1*I, 2.0 + 2.1*I]
>>> [i.n(2) for i in Poly(r).all_roots()]
[0.79, 3.2, 2.0 - 2.7*I, 2.0 + 2.7*I]
</code>
Answer: The following outlines the steps to determine whether roots with the same real part exist, but it is computationally intensive and would require a CAS to work out in all but the most trivial cases.
Let $\,P(a+ib)=p_1(a,b) \,+\, i \,p_2(a,b)\,$ where $\,p_1,p_2\,$ are bivariate polynomials in $\,a,b\,$ with real (in fact, integer) coefficients. Then $\,P(a+ib) = 0 \iff p_1(a,b) = p_2(a,b) = 0\,$. Eliminating $\,b\,$ between the latter using polynomial resultants gives the polynomial $\,P_1(a) = \operatorname{res}_b (p_1,p_2)\,$ that $\,a\,$ must satisfy $\,P_1(a)=0\,$. Repeating the procedure for $\,R(a+ib)\,$ gives in the end a similar equation $\,R_1(a)=0\,$. Those two equations have a common real root $\,a\,$ iff $\,\gcd(P_1,R_1)\,$ has degree at least $\,1\,$ and has real roots. What still remains to be verified is that any such common root $\,a\,$ corresponds to $\,b \ne 0\,$ non-real complex roots of $\,P,R\,$.
Comment: In fact, this question arises from a CAS context (SymPy) and your approach was easy to implement using existing tools. Thanks!
Comment: Nicely done, thank you for the followup.