Kali Linux + Windows-To-Go Multiboot USB?

Question: I just bought a Patriot 256GB USB. I want to run Kali Linux (with encrypted persistence) and Windows To Go (Server 2019 or Windows 10.) I've used YUMI and Sardu for multiple Linux Live USB and Persistence (Casper-RW.) I currently have one with Mint, Ubuntu, Kali, a few Anti-Viruses' and Hiren's boot CD. It works fine. Can I create a single USB with Kali and Server 2019? Or any Windows 10? Kali needs persistence or encrypted persistence. I've tried making Windows To Go before but never had a USB fast enough to run it. It worked but would take hours to start up. I think I created it using Rufus. Or another. And it was Windows 10 not Windows Server. I read about "Ventoy" but I don't know if it will create Windows To Go or just the Windows installer. Does anyone know any ways to install Kali + Windows? Free Software? What about a VHD or VHDX? I have a Server 2019 VM on VMware. Can I copy that to the USB? Partition it? Please reply. Thanks
Comment: What did you end up using?
Answer: Creating a multi-partition GPT style USB drive sounds possible, but complicated to create and maintain. However, depending on what your real world use case is you might try a solution called Easy2Boot.
I've been using Easy2Boot for years as an all-in-one troubleshooting / utility usb stick containing a trove of Linux live ISOs, Windows PE ISOs, and random bootable bios / firmware images. I don't need persistent storage for my needs, but the FAQ suggests that this is supported. The thing that I like most about Easy2Boot is that I can just add or remove ISOs to / from the drive without the need to manage separate partitions or a boot manager.
If running a "real" Windows installation is something that you need, Easy2Boot also appears to support Windows To Go style installations and VHDs (see FAQ / documentation). However, I would take this with a grain of salt as Windows To Go is no longer officially supported by Microsoft, so might not be the best solution. I also don't think Windows Server was ever officially supported by Windows To Go as it was intended for sharing desktop hardware in educational and enterprise environments.
One problem with Easy2Boot is that the website is a bit dated in terms of design and can be difficult to navigate. They have extensive documentation and forums, but locating what you're looking for can take some effort.
For anyone else that is coming here looking for Windows To Go information, I'll add a link to an article from pcmag.com that provides a tutorial for creating a dedicated Windows 10 To Go drive using WinToUSB and / or Rufus.


What are the pros and cons of using a supervised learning approach for building a recommender system compared to traditional approaches?

Question: Pretty much all articles I read about recommender systems use Collaborative Filtering, Content Based Filtering and Hybrid approaches. Virtually no one mentioned about supervised learning approaches. We can use ratings/clicks as the target variable and user attributes and item attributes as features to build a classification/regression model and use the predictions from the model to do recommendations. Are there any particular reasons for such an approach being ignored in the recommender system community?
Answer: As @Tim mentions, supervised learning is widely used in recommender systems. Common recommender systems like Collaborative Filtering, Matrix Factorization, and Neural network based methods rely on the availability of labels provided by the previous interactions between users and items.

We can use ratings/clicks as the target variable and user attributes
and item attributes as features to build a classification/regression
model... Are there any particular reasons for such an approach being
ignored in the recommender system community?

Based on the above part of your question, I assume you're asking about the use of some specific types of supervised learning, i.e., models similar to linear and logistic regression. Below, I provide examples of these types of models (or those that are inspired from such models) that have been proposed for recommender systems. These are well known models.

SLIM: Sparse Linear Methods for Top-N Recommender Systems
Logistic Matrix Factorization (pdf)
Two-Class Collaborative Filtering (pdf)
Comment: Yes, I meant to build a model like Rating = f(user attributions, item attributes, session attributes, .....). CF and MF are only involved with userId and itemId. Normally people don't use IDs as features to build a regular ML model.
Comment: Three links you proposed are quite awkward. Yes, I meant why nobody builds a classification/regression model for Rating = f(user attributions, item attributes, session attributes, .....) and use its predictions to do recommendation.
Comment: @etang A model like you wrote above, where rating is predicted purely based on user and item attributes would not work well for personalization. Not sure if someone has shown this, but I can say that from my experience. The links I provided above are the closest works I know to a linear or logistic regression model. Of course, the features they use and the functions they are optimize are different. But that's because recommender systems are fundamentally different from the task of predicting a number or a class.
Answer:
First of all, supervised learning is commonly used in recommender systems. One of the most popular examples of recommender system model is matrix factorization, where we predict ratings of items by the users (labels!).
Basic models like matrix factorization are often extended by including additional features, such models do not differ very much from any other supervised machine learning model.
Standard machine learning models are sometimes used for this purpose, but they often underperform as compared to the models designed for this purpose.
Comment: @mlwida if you use matrix factorization or similar algorithm you look at the interaction of particular user and item. If you used something like logistic regression instead, you could use something like general features of item etc. When you add the interaction term, it becomes something like matrix factorization.
Comment: Can you provide any sources for the statement, that standard machine models often underperform compared to e.g. matrix factorization ? I like to dive deeper into this topic.


What are apps 10110 & 10109?

Question: On my galaxy S2, the mobile data usage shows two applications 10110 and 10109 consuming a lot of data. Does anyone know what these apps are? Or how I can find out?
I am running jellybean 4.1.2 on Samsung Galaxy S2.
Comment: Can you see those apps in Settings -> App?
Comment: No, I can't  see them there.
Answer: That are most likely not app names, but their "user IDs" (and the system is unable to match a name).
On a rooted device, you could find out more on those by executing
ls -l /data/data | grep 10110

(which should show you the data directory of the app owned by that user, together with some more data). Investigating that directory might give you an idea: its name is the package name, which you could even lookup at Google Play:
https://play.google.com/store/apps/details?id=<package_name>

While that's unlikely to find the app (or your system really is in trouble not being able to match the two), it's at least worth a try. In case nothing is found, you can investigate that directory's content to make a "good guess" what it might be about. Also, the name of the directory itself might already have given you a clue.

I will give you an example (from one of my extracted Nandroid backups). Let's say ls turned up com.motorola.android.fota on a Motorola device. So by the fact it's a Motorola device, and the package name starting with com.motorola.android one can deduce it's a system app build by the manufacturer. Assuming one doesn't connect the fota with anything, in the subdirectory databases one finds two SQLite files. I checked the config.db and saw it has two tables, at least one of them seemingly all about updates (auto_update_interval, auto_update_enable, and more). The second one is fumo.db and seems to hold information about packages. So this is most likely an app responsible for updating apps -- and if you not already know, "FOTA" stands for "Firmware Over The Air update".

However, to do that your device must be rooted (users other than root it won't permit to browse the /data/data directory).

What are apps 10110 & 10109?


Is there any systematic way to pick two colors for a chloropleth showing a candidate's margin of victory

Question: I have a simple 2-color map showing which candidates won in which precinct. Now I want to make one showing margin of victory within a precinct. So if candidate A won by a lot it would be dark green, if candidate A won by a little it would be light green, if candidate B won by a lot it would be dark yellow and if candidate B won by a little it would be light yellow. (These are local elections so red and blue don't make sense). I used color brewer to pick my initial two color scheme. I have zero design sense. How do I go about picking the colors for the margin of victory map?
Comment: You would probably have to standardize your data first so you can define "a lot" or "a little" by a number/ratio/percent. Then you could define your margin of victory upper/lower class breaks and then color your classes accordingly.
Comment: @JasparKatt can you say about the appropriate way to standardize this kind of data. How do I decide what the bins should be?
Answer: If you need to get color dynamically on a website, I would give you the advice of using the excellent chroma.js library. The library is easy to use and implements a scale mechanism which would fit to your needs :
<code>scale = new chroma.ColorScale({
colors: ['#F7E1C5', '#6A000B']
})
scale.getColor(0.23)
</code>

More on chroma.scales in the dedicated wiki page : https://github.com/gka/chroma.js/wiki/Color-Scales
Predefined colors are listed here. 'OrRd' (red ramp) and 'Blues' (blue ramp) could be useful to you. See also 'spectral'.
Answer: There is the ColorBrewer Option in QGIS:
From the Layer Properties > Style > choose Categorized > from Colour Ramp choose New Colour Ramp > Select type Colour Brewer:

Or use the ColorBrewer website: http://colorbrewer2.org/
Pick a diverging colour scheme, maybe 5 data classes, then pick a colour scheme...
You can use those colours in whatever your mapping client is.


Accidently touching adjacent string while playing guitar

Question: While playing basic Chords like A, D , E etc.  my finger-tip touches the adjacent string and thereby the note tone is ruined. So my question is should I continue playing and practicing chords or I should switch over to playing simple children melody of one or two verses or should I switch over to practicing exercises relevant or prescribed for such problem ? I have just started learning guitar for last 15 days. So please guide me in the beginning of my guitar learning path, so there would be a solid and proper foundation.
Comment: Let me take a guess that you are self-learning i.e. without a live teacher. Else, you not ask the question, or perhaps it is time to change the live teacher. OTOH, the issue of notes not being distinct and clear, fingers touching neighbouring strings are all beginner problems, that go away with practise -- but with right technique as well. As the gurus here will tell you, there is "a" right technique (that is equally applicable to everyone), but a technique that is right for "you". Fat-n-stubby fingers, slender fingers, large hand, small hand may require slightly different techniques...
Comment: ... make sure, that you are practising with the right and appropriate technique. Sometimes the student has to discover the technique that best suits them. For instance see this one (which is shown on a Classical Guitar): https://www.youtube.com/watch?time_continue=55&v=cqqVkNoL6wE
Comment: Also watch this one: https://www.youtube.com/watch?v=zo8vF0DBxNE
Comment: Remember that 15 days won't get you yet enough callouses, and you are fingertips are likely to still hurt. And to reduce the hurt, you may be avoiding the right technique. So keep playing, but do not delay ensuring that the technique you use is the right one.
Comment: @icarus74 - callouses? Not usually necessary, and even if one is unfortunate enough to develop them, they certainly won't help with fingers touching other strings.
Answer: First, are you taking lessons?  Do you have a mentor that can view your hand posture and correct it?  A better question might be how do I fix this problem, rather than should I continue.
Practicing "children melodies" will not make chords easier.  If you're 15 days into it you may not have the coordination to play chords very well.  This takes time and practice, and a teacher would help.
You need to make sure you are fingering the chord properly, and before that that you are holding the guitar properly (bad hand posture will create more opportunities for problems).  Then make sure you CAN play the chord without ruining the sound (some cross string touching may not be a bad thing, we do this to create dead strings in chord forms that skip strings).  If you can get get it right once, you can get it right every time.  You just need regular practice forming the chord, playing, then releasing the hand and reforming the chord.  Make sure you are not squeezing the neck too much (or at all for that matter).  Once you can get a chord reliably start transitioning from one to the other, perhaps based on a song with a simple chord pattern.
Finally, there are alternate fingerings for many chords and you may want to look into that.  A good guitar teacher would be familiar with them and be able to give advice based on watching you play.
Answer: Since the guitar is one of only a few instruments on which chords can be played, it's important to be able to play chords!
If you are touching other strings, be very careful pressing down - obviously. Part of your practice regime now should be slowly placing fingertips on strings, pressing down, and checking each string in turn, to hear 5/5 or 6/6.
If your fingers are quite wide, there's an option of using one finger for two strings, which works well for both E and A. On E, your middle finger is probably wide enough to cover strings 5 and 4 (the A and D strings). With open D, you can experiment with different fingerings - there are 12 available. There should be a couple which work for you. Don't always go for the fingering a book or website (or even some teachers) tell you to use. Work out what's best for you.
And play all sorts of things, melodies, riffs, chords are only a start.
Answer: Just keep at it. This happens at the beginning. Your fingers will get stronger and more adept at fingering the chords cleanly. Two things you can practice are smoothly switching between chords and fingering them cleanly and you can practice both at the same time by just going very slowly and deliberately placing the fingers in the correct place.
If you absolutely can't get them to sound cleanly just keep at it. You'll get there.


How to get rid of spilled coffee scent?

Question: Thought I managed to clean the coffee spill effectively; however, few days later the scent is still there.
At this stage, what is a suitable way to removed coffee scent off a rugged floor?
Comment: Was it black coffee, or coffee with cream, sugar, etc?
Answer: Dump a box of baking soda on it, wait a few days, vacuum it up.
Comment: Careful! Baking soda is pretty fine stuff. It can clog vacuum filters very quickly.  Borrow a shop vac for the job, and finish with your household one.
Answer: Vinegar can solve the issue as well. Try a 1 to 2 ratio with water.
Comment: Related question:  How do I get rid of vinegar scent?
Comment: I find some coffee grinds take care of the smell.  Time will take care of the smell once it dries.  Or just wipe down with water.
Comment: Also, the vinegar smell will air out. It takes some time, but it goes away completely as it evaporates. I clean my hardwood floors with it (roughly 1/3 cup of vinegar used) and the smell is gone in about 5-6 hours. The mop head however, will need to be washed before it goes away. Hope this is helpful.
Comment: @treeNinja OK, then how do I get rid of... nevermind.
Answer: Most pet stores, these days, sell enzyme mixtures for eliminating pet odors. These will work on many organic odors, IF you haven't already "set" the stain by hitting it with other chemicals. (Even then, they may help. Nothing will ever eliminate all traces of the previous owner's cat from my persian rug, but it's been knocked down to a level that neither I nor my own cats find objectionable. I did have to treat both top and bottom of the rug rather thoughly, though, since the stain had soaked through.)
(By the way, this stuff is great for eliminating sick-room odors as well. Organics are organics.)
Answer: Adding on, you can do the enzyme cleaner already mentioned (and the kind for laundry has always worked just as well for me) then the next day put baking soda & vacuum it off
Source: my ADD medication has a side effect of making me really good at cleaning, so friends & relatives are always hitting me up for problems like this.
Answer: I'd recommend baking soda and water solution. Might it until it's a toothpaste like consistency. Spread it, and then wait a day. Clean it up when dry, picking up as much as you can with your hands and then a vacuum and then water and a rag to get the rest.
If that doesn't do the trick follow up with a 2:1 mixture of water and white vinegar. A tiny bit of alcohol can help, but it's not ideal for carpet and it's usually not necessary.
Repeat those two and you will get there. You can try a tough enzymatic cleaner but some of those are rather nasty and they are hit and miss.

How to get rid of spilled coffee scent?


Chicken smells like eggs

Question: I purchased some fresh chicken a few weeks ago and immediately froze it. Today I took it out and put it into boiling water to start making soup. Before I added anything else, the whole room started to smell like eggs (not rotten per se, but strong).
Is something wrong with the chicken? Should I throw it out?
Comment: Which smell came first, the chicken or the egg?
Comment: Was the chicken an odd colour or slimy at all?
Comment: @ElendilTheTall No. All else seemed normal.
Comment: Did you defrost it for a long time? I find that my chicken, whether in the meatpacker's original packaging or my local grocery store's repackaging, smells a bit if I defrost it much longer than four hours.
Answer: Raw meat should not have a smell to it. When it has an odour to it it is a sure sign that it is starting to spoil. Blood will spoil quicker and some rare conditions causes the smell on the meat. Washing it off helps to reduce the odour but it is best to just toss it out to avoid being made sick by eating it.
Salmonella enterica infected chickens will release hydrogen sulfide gas, which smells like eggs. It is found largely in chicken products and eggs. It is killed by cooking at high temperature, but it is best to avoid using it if the chicken starts to smell like that. Salmonella is the second most common bacterial cause of enterocolitis.
Answer: I have had this happen and have received conflicting answers. Some say the chicken is off. However, when Amazon Fresh (local grocery delivery service) ships chicken, they include a message that the gases used to pack the chicken may smell like sulfur but that this should dissipate quickly. I have had chicken where the smell went away quickly and times when it stuck around. When it stuck around, I got rid of the chicken.
Answer: Usually, chicken's smell isn't good in all cases, but in order to decrease this smell you have had done the following:

Wash the chicken after getting it out of the freezer.
Pass a little amount of vinegar or lemon juice all over it, it will reduce odors.
Rewash it, then put some salt all over it, then boil it or do whatever you want to do;
this makes it even taste better.
upon cooking, try adding some paper laurel to decrease the smell.
Answer: throw it out, smell indicates the chicken is spoiling.

Chicken smells like eggs


Any good free VPN windows apps?

Question: I tried many free vpn like hotspot shield, urban vpn, express vpn none want to connect. I am in latest windows 11 version. Is there something that can work on Windows 11 ?
Answer: I know this isn't a real "app" but if that will work for you I would recommend using Opera, which offers free VPN. Besides, I'm already on Mozilla VPN's waiting list. This is my preference to use VPN as I don't find the free ones reliable.

Any good free VPN windows apps?


Prove a statement about searching in binary search tree

Question: Suppose search $n$ times in  a given binary search tree $T$ with $n$ nodes. each searching have cost $C_i$, and $\sum_{i=1}^{n}C_i=O(n\log n)$. Now the problem is to find height of $T$. I think it be $O(\sqrt{n\log n})$, but after reading this post, what is correct proof to get that result?
Comment: The other post ask for the upper boundary of a tree's height, which is in his case not $O(\log(n))$ (considering a tree with only left/right branches).

Your problem is different, it already gives you the information of the upper boundary of cost for searching every node together, which is $O(n \log n)$, what would be then the upper boundary of cost for searching one single node? And given the upper boundary cost of searching one single node, what would be the upper boundary for tree's height?
Answer: Let $h$ be longest path from root $T$ to leaves. We must read $h+1$ nodes. So searching for root of $T$ we have cost $1$, for child of root we have cost $2$ , and etc. it's sufficient to sum over cost at each nodes on $h$. As a result we have
\begin{gather*}
1+2+3...+h=O(h^2).
\end{gather*}
Now as mentioned in question,
$O(h^2)$ must be $O(n\log n)$. More formally, $O(h^2)=O(n\log n)$ that we can conclude that $h=O(\sqrt{n\log n})$.
For example consider a binary search tree with $n$ nodes such that root have sub tree with height $\sqrt{n\log n}$, and right sub tree of root have height $\log (n-\sqrt{n\log n}).$


Non-deterministic Büchi vs Rabin: Automaton size for LTL->automaton

Question: Is there any general result to show that which automaton is more succinct? I have a set of LTL properties and I would like to know (show) which automaton is more efficient in term of state number and edge number.
Comment: Can you expand the main body of your question to make it independent of the title? Try to be more elaborate.
Comment: Have you checked any small examples?
Comment: @MichaelKlein Yes, Actually Buchi was way better in my examples but I just wanted to know if it is a general argument or not.
Comment: From a discussion with one of my friends for state numbers: "the rule of thumb is determinism costs 2EXP, nondeterminism costs EXP". So can we just recon that Rabin automaton, because it is deterministic, needs more states?
Answer: Consider a nondeterministic Büchi automaton $A = \langle \Sigma, Q, q_0, \delta, \alpha\rangle$. The acceptance condition of $A$ is a subset of states $\alpha\subseteq Q$, and an infinite run $r = q_0, q_1, q_2, \ldots$ over an infinite word $\sigma_1\sigma_2\cdots $ is accepting iff $r$ visits a state in $\alpha$ infinitely many times.
In Rabin automata, the acceptance condition is given by $\alpha = \{\langle \alpha_1, \beta_1 \rangle, \langle \alpha_2, \beta_2 \rangle, \ldots , \langle \alpha_k, \beta_k \rangle \}$, where $ \alpha_i, \beta_i\subseteq Q$, for all $i\in [k]$. An infinite run $r = q_0, q_1, q_2, \ldots$ over an infinite word $\sigma_1\sigma_2\cdots $ is accepting iff for some $i\in [k]$, $r$ visits a state in $\alpha_i$ infinitely many times, and visits the states in $\beta_i$ finitely many times. The number $k$ is the index of the automaton, and is usually taken into account when defining the automaton's size.
Clearly, a Büchi condition $\alpha$ is equivalent to the Rabin condition $\{ \langle \alpha, \emptyset \rangle\}$. Thus, nondeterministic Büchi automata can be translated to nondeterministic Rabin automata with no blowup (they can be thought of as a simple fragment of Rabin automata - although they are equally expressive).
So, nondeterministic Büchi automata cannot be more succinct than nondeterministic Rabin automata. However, a nondeterministic Rabin automaton with $n$ states, $m$ transitions, and index $k$, can be translated to a nondeterministic Büchi automaton with $O(n\cdot k)$ states, and $O(k\cdot m)$ transitions. The later translation is justified by a lower bound. So, nondeterministic Rabin automata are polynomially more succinct than nondeterministic Büchi automata, which is not significant.
A comprehensive overview of the translations can be found here (along with other relevant references).
Note that you can easily translate an LTL formula into a nondeterministic Büchi automaton (see section 6 here), and the translation has a tight exponential bound. However, following your comment, if you're interested in translating the LTL-formula into a deterministic automaton, then you can translate the Büchi automaton to a deterministic Rabin automaton (such determinization construction has a tight bound of $2^{\Theta(n \log n)}$). Also, the double exponential blow-up of translating LTL formulas to deterministic automata cannot be avoided (see theorem 26 here).
Comment: Thanks for the detailed answer! The translation link was very useful and I shared it within our team.
Comment: You're welcome.


Importing Objects as Empties

Question: That may sound weird, but I want to import all the objects from an .OBJ file as dummies centered where the object's center would be for a little experiment involving game modding.
I have no experience with scripting, so I'm asking if it'd be hard to make a script that executes the operations I just described.
Answer: Use the importer provided
Would simply import with the provided importer then replace each with an empty.
Import the obj file. Add an empty with the same transform as each imported object. Remove the originals.  (Note doesn't keep parenting)
Modify the filepath to where your obj file is on your computer.
import bpy

context = bpy.context

# some path to your obj file
filepath = "/home/batfinger/Desktop/xxxx.obj"

# import it
bpy.ops.import_scene.obj(
        filepath=filepath
        )

# the imported objects.
imported_objs = context.selected_objects

# add an empty for each imported object
for o in imported_objs:
    bpy.ops.object.empty_add()
    mt = context.object
    mt.name = o.name
    mt.matrix_world = o.matrix_world

# delete imported objects
bpy.ops.object.delete(
        {"selected_objects" : imported_objs}
        )

Answer: For starting blender-python-programming it can be helpfull to check out the info tab and copy out the listed commands to your script.

here is the script you want, wich keeps the original objects name.
Import your objects by hand, select the ones you want to empty out and run script from text editor.
comments are marked with #, so you can understand whats going on.
This way you could easily create other macros as well.
works only on 2.8
#import blender namespace
import bpy
#get all selected objects
selection_names = bpy.context.selected_objects

#loop trough all "selection_names"
for i in selection_names:
    #for every object "i":
    #set active object as "i"
    bpy.context.view_layer.objects.active = i

    #go to edit mode of "i"
    bpy.ops.object.editmode_toggle()
    #select all
    bpy.ops.mesh.select_all(action='SELECT')
    #delete all verts
    bpy.ops.mesh.delete(type='VERT')
    #go back to object mode
    bpy.ops.object.editmode_toggle()
    #repeat for next object in "selection_names" till none left

Importing Objects as Empties


In the network or on the network

Question: In my conclusion of my experiments I want to say that "some event occurs everywhere in the network". The network refers to computer networks but not necessarily Internet here. I know that "on the Internet" is a set phrase, but I feel that "some event occurs everywhere on  the network" sounds wired as I think the events are occurs "insides the network". What proposition should I use in my sentence? Any suggestion will be appreciated.
Comment: I don't think this is a duplicate,  because a generic network can be referred to differently than the Internet.
Comment: Not sure if you meant "some events occur".
Comment: I am sorry I didn't explain it clearly. I mean some particular event. But not some any arbitrary events. Maybe I should say "The event A occurs everywhere on the network".
Comment: possible duplicate of [Over the Internet or On the Internet?](http://ell.stackexchange.com/questions/15626/over-the-internet-or-on-the-internet)
Comment: This recent post might be helpful: http://ell.stackexchange.com/a/41013/8758
Comment: What kind of events are you talking about?
Answer: There is a choice of prepositions here.
Normally, you would say that a computer is on a network or on the Internet.
However, if you are a network engineer, you might be responsible for administering a firewall, in which case you might be concerned about the distinction between inside the network and outside the network that you operate.
A worm might propagate on/over/through a computer network.
In US-style healthcare, a health insurance plan will cover your treatment only if you go to certain doctors or hospitals.  In that case, the plan will speak of in-network coverage and out-of-network coverage.
Answer: In a computer network, I would say:

Some event occurs everywhere on the network.

It is the same as with a telephone:

I was talking on the telephone.

Basically you are connected to/interacting with a communications medium.
Refer to this definition of on sense 16b:

16b) through the medium of  ⇒ "on the phone, to act on TV"

(AmE disclaimer, this may vary by locale.)
Comment: A little more about "in the network" and "on the network"? Please. It always makes me confused.
Comment: It is by definition. I edited my answer so please check it.
Answer: throughout the network is another idiomatic possibility.
Answer: Both are meaningful, and they shape the way you think of "the network."
If something is "on" a network, it is not part of the network itself.  If something is "in" a network, it is part of it.
We, as humans, use both wordings.  "On the network" isolates the network from what you are talking about.  This makes the network simpler, and has it interacting with the outside environment.  This wording would be used along side concrete statements about network behavior such as "guaranteed end-to-end latency of less than 11us" or "100Mb/s packet switching."
"In the network" embeds what you're talking about in to the network.  This makes the network much more complicated, because it has to describe all of the computers connected to it as well.  However, there are times where the effect you are describing is found in the interactions between computers.  In this case, it is easier to show the interactions if you just treat it as one monolithic body.
As an example, there is a rule of thumb that you should avoid using both TCP/IP and UDP packets in the same game engine.  You do this because TCP/IP will try to throttle its bandwidth as high as it can go, and disrupt the UDP packets in unpredictable ways.  In this case, you note that I talk about the TCP/IP socket, the UDP socket, the computer, and the network all in one big group.  In this case, "in the network" is probably the right term.
Answer: Simply put, a person is 'on the network' while a computer or resource is 'in the network'.
"a client system processes information pertinent to a single user on the network while the server processes data relevant to every client in the network"

In the network or on the network


how to design a policy enforcement system, that prevents dictionary attack on forget password flow?

Question: Use case is to prevent any dictionary attack on forget password flow, where attacker can trigger any no. of emails using forget password flow.
Comment: What kind of forget password system is it? Do you have to answer a secret question? Or do you just get an email with the reset code? What is it that would be brute forced with a dictionary?
Answer: A user selecting the 'Forgot Password' button should only be able to enter a valid user email address and be required to then only interact with the system to reset the password via the link provided in an email to that address.
Furthermore, the link provided needs to have a time-out value assigned to it so it is only valid for perhaps 30min at the most. If an attacker already has compromised a valid users email that is used to login there isn't a lot that could be done and that person would not need to brute-force the login.
But, to stop brute-force logins just put in a limit of failed attempts before the IP address is no longer permitted to attempt a login


Yamaha SV-250/255 Silent Violins: usable without the control box?

Question: Can these violins be used without their control box, i.e. just plug the violin directly into my amp/pre-amp pedalboard (just like the YEVs)?
Comment: As Alphonso's answer suggests, so long as you have proper impedance matching, any preamp is acceptable.
Answer: The control box for the Yamaha appears to be a pre-amp with EQ, DI, and headphone amp. To be honest, it looks like a pretty good addition to the instrument.
To answer your question, The instrument has two piezo pickups in it and the output signal should be the pickups sent through a blend circuit, which would let you plug it into any amp, pre-amp, or effects unit built to take instrument input.
There are other manufacturers of D.I. and EQ units designed for Piezo pickups, and you can build a completely different tone to the instrument using different combinations of pre-amp and effects.
I have a cheap electric violin that I found sounded much better when the built in pre-amp and EQ unit failed and I wired the pickup out direct.
Answer: You surely can, however as the control box is acting a D.I. the sound will be better with the control box (and equalized, as a bonus)…
Answer: The cable from SV-250 is actually supply voltage and mono signal together in a stereo cable, and I am not sure if any amp/preamp can handle this.
However it is pretty easy to get a signal out of it without modifying the violin itself, just by peeling and connecting some wires.
Pin out of SV-250

T(Tip)

Supply voltage for the piezo pickup, with the control box under battery I measured DC 9.8V when connected to the violin, or 10V when unplugged.
draws ~0.5 mA
Seems to be able to drive the piezo just with a 9V battery, so you may be able to avoid voltage regulators.

R(Ring)

Output signal
Around +/- 1V when driven by the default 9.8V supply voltage. This is about line level but a bit quiter than the control box cranked full.

S(sleeve)

Ground

Bypassing the control box
This can be cheaply done by buying a 3.5mm(1/8") stereo cable and a 9V battery box.
Cut and stripe the stereo cable and connect it as follows:

The sleeve is ground so they stay connected in addition to the battery negative terminal. Since the output is mono signal, R is also connected to ground. you can also just get a mono connector for the output.
The positive terminal is connected to T of the violin end to power the piezo pickups. You can also add a switch in between, or just unplugging the violin should also be enough when not in use.
Violin end R connects to T of the amp end for ouput signal.
Note:

I'm not sure if there's any risk of driving the violin with 9V instead of 9.8V. probably fine but use at your own risk.
The audio quality is worse, but good enough for me for practicing.
You should check the pins of the cable before connecting them. My ultra cheap cable had its T and R crossed.
You can sholve all the components into the violin chin rest, but the power switch probably require drilling some holes. I'd expect the battery to last quite some time so opening up the chin rest once in a while won't be too troublesome.
I'm able to make my violin wireless by hooking this into a wireless guitar dongle. The battery fits nicely between the violin and shoulder rest. If you want to go further you probably can draw power from the wireless dongle by hacking it too.


Humble and losing ALL abilities: Does this affect creatures with equipped artifacts?

Question: Humble causes a creature to become 0/1 and lose all abilities.  If the target creature has an artifact equipped, giving it +1/+1, before this instant is played, does the target lose any benefits applied from the artifact?
Answer: Short Answer
The creature will be a 1/2.
Long Answer
The Comprehensive Rules define a layer system. When multiple effects need to be applied, the layer system describes the order in which they happen. Humble sets the base power and toughness to 0/1 in layer 7b.

613.3b Layer 7b: Effects that set power and/or toughness to a specific number or value are applied.

Since the equipment modifies the power and toughness by giving the creature +1/+1, we know that it applies in layer 7c*.

613.3c Layer 7c: Effects that modify power and/or toughness (but don't set power and/or toughness to a specific number or value) are applied.

We know that 7b applies before 7c because of rule 613.3.

613.3. Within layer 7, apply effects in a series of sublayers in the order described [...]

7b comes before 7c. Therefore, the example creature is first set to 0/1, then modified to 1/2.
Trivia
In the Magic 2015 Update Bulletin, the word "base" was added to cards like Humble. This was supposed to make it clear to players that it applies before other effects that might modify power and toughness. Prior to Magic 2015, cards like Humble still worked the same way, but it was less obvious. In other words, it was a nonfunctional change aimed solely at improving clarity.
*The phrase "Equipped creature gets +1/+1" is an ability of the equipment, not an ability granted to the creature. If the equipment said "Equipped creature gains 'This creature gets +1/+1'", then it would actually be applied in Layer 6 instead.
Comment: It may be useful to state that "Equipped creature gets +1/+1" is not an ability granted to the creature, since that is actually why it ends up being a 1/2. If it were an ability granted to the equipped creature it would have been removed in Layer 6.
Comment: It is an ability of the equipment granting a P/T boost to the equipped creature as a Continuous Effect. For it to grant the equipped creature an ability it would have to be worded something like "Equipped creature gains 'This creature gets +1/+1'" or something equally awkward.
Comment: @diego Thanks for helping. I made it a footnote so that it would interfere less with the flow.
Answer: The artifact still gives the equipped creature its +1/+1 bonus, because of the order in which power and toughness are calculated:
a) characteristics (the creature itself)
b) effects that set power/toughness to specific numbers (such as Humble)
c) effects that adjust power/toughness but don't set them to specific numbers (+/- effects such as equipment and enchantments)
d) counters (+1/+1 or -1/-1)
e) effects that switch power and toughness
So after Humble resolves, the creature will be a 1/2.
Comment: Welcome to Board and Card Games!


What is appositive and modifier?

Question: I always get stuck between appositive and modifier. As first learner in writing, I need to distinguish them. What should I do?
Answer: The appositive is a noun or noun phrase that modifies another noun. The appositive follows directly after the noun, with a comma separating them. It is similar in placement and intent to the reflexive.
Examples:

The tree, an oak, cast a long shadow at sunset.
The tree, an old oak, cast a long shadow at sunset.
The tree, an old knotted oak, cast a long shadow at sunset

Opposite the appositive, modifiers tend to come before the noun(s) they modify. Let's use the above example:

The old knotted oak tree cast a long shadow at sunset.
Comment: An appositive is not a modifier at all. It is a clarification of the noun to its left.
Answer: Appositive and Modifiers are two completely different elements that function in very different ways. Modifiers can occur in phrase structure, or they can be used to modify clauses. But an Appositive can never occur in Phrase structure, except in some cases where there is no comma before it.
Here is an example of an Appositive:

Yesterday I watched the opera 'Carmen'.

In most cases the Appositive is detached from a phrase with a comma:

My cat, Tom, is very naughty.

Here notice that my cat and Tom both refer to the same entity. And you can use either Tom or my cat without changing the meaning of the sentence.

My cat is very naughty = Tom is very naughty.

Here Tom is the Appositive.
Now consider the following sentence:

[The alarming fact that the ice is melting rapidly] is a cause of concern for the scientists.

The bracketed element – the alarming fact that the ice is melting rapidly – is a Noun Phrase (NP) that functions as the Subject (Complement) of the clause.
Let's analyze the NP structure. The head noun here is fact.  The (WORD-CLASS: determinative) is a Determiner, and alarming (WORD-CLASS: adjective) is a Modifier. We can omit Modifiers like alarming without making the sentence ungrammatical in most cases. But of course the meaning might be affected.
The Complement of the head noun is that the ice is melting rapidly and in most cases it can't be omitted without making the sentence ungrammatical.  Likewise, we can't omit the Determiner the because fact is a count noun.
Comment: I edited this answer somewhat.  I think the first paragraph still needs editing, because in H&P's theoretical framework Appositive dependents are actually a specific kind of Modifier and can occur in NP structure (see CGEL p.447), although they are rather different from non-appositive Modifiers.

What is appositive and modifier?


Is there a rule of thumb when it comes to the "name" attribute?

Question: Since there is things like BEM in naming conventions for HTML class attributes, does the name attribute have anything of that sort?
Comment: See https://google.github.io/styleguide/htmlcssguide.html#Capitalization
Comment: Thanks bud :) I appreciate it! Can you respond as an answer so we can close this thread lol.
Answer: Name is a CDATA type so the following applies:

ID and NAME tokens must begin with a letter ([A-Za-z]) and may be followed by any number of letters, digits ([0-9]), hyphens ("-"), underscores ("_"), colons (":"), and periods (".").

Despite that there are cautions offered by StackExchange users:
StackOverflow Question: "HTML input - name vs. id", in answer from Kumar Akarsh:

According to specs is case sensitive, but most modern browsers don't seem to follow this.

w3schools - "HTML Forms" cautions:

The Name Attribute
Each input field must have a name attribute to be submitted.
If the name attribute is omitted, the data of that input field will not be sent at all.

Mozilla's documentation (if you drill down from): "MDN web docs - HTML attribute reference" to "MDN web docs Moz://a - <form>" says:

name - The name of the form. In HTML 4, its use is deprecated (id should be used instead). It must be unique among the forms in a document and not just an empty string in HTML 5.

Mozilla.Org also refers you to: HTML - Living Standard — Last Updated 21 August 2018

"The name attribute represents the form's name within the forms collection. The value must not be the empty string, and the value must be unique amongst the form elements in the forms collection that it is in, if any.".

So ...
You probably want all lowercase with each word (if there's more than one) separated by a dash (rather than camelCase).
Answer: There is no such naming convention in HTML for name attribute as well as for other attributes also. But you should follow the following rules.

Use lowercase Latin letters.
Separate different words by a hyphen.
Do not use periods as well as numbers at the beginning of the name.


skip columns while using LOAD command mysql

Question: I have a csv file having 5 columns and i want to load only one out of that, is there a way i can do it. I want to use LOAD statement of MySQL 5.5
Any pointers are welcomed, help would be much appreciated
Comment: This is covered in the [documentation](http://dev.mysql.com/doc/refman/5.5/en/load-data.html)
Answer: From the documentation:

You can also discard an input value by assigning it to a user variable
  and not assigning the variable to a table column:

LOAD DATA INFILE 'file.txt'
  INTO TABLE t1
  (column1, @dummy, column2, @dummy, column3);

Comment: I have gone through the documentation, but i have a csv file say - 46,94,43,12 now i want to discard the third column,  LOAD DATA INFILE 'file.txt'
  INTO TABLE t1("WHAT SHOULD I WRITTE HERE?? THE COLUMN NAMES??)... Thanks for your time Phil..
Comment: `LOAD DATA INFILE 'file.txt'
  INTO TABLE t1
  (column1, column2, @discard3, column4);`
Answer: you can save the csv field value to a variable and assign the variable to the table field.
load data infile 'filelocation../file.csv' into
    table myTable columns terminated by ',' optionally enclosed by '"'
    escaped by '"' lines terminated by '\n'(@value1,@value2,@discardValue,@value4)
    set f1=@value1 ,f2=@value2,f3=@value4;

Comment: Seems identical to Phil's suggestion, only this longer syntax makes you introduce more variables.


What is the packet of stuff inside a package of ground turkey?

Question: When I buy ground turkey from Publix, under the ground turkey in the package there is a packet of something pinkish colored than isn't mentioned on the label, what is it? Is it maybe something from the turkey used for flavoring a broth or something?
Comment: I've seen those and they are placed under most meats and, *i believe* are there to absorb the liquid in the meat. If you look closely at this item is is not much more than some sort of sponge.
Comment: Welcome! Can you please include a photo? It's almost certainly something that belongs to the packaging, but to be sure we need more information.
Comment: Is there anything written on the "packet of stuff", such as **Do not eat**?
Answer: Where I live most prepackaged meats come with a kind of fluids sponge or mat.
Those can be part of the packaging, can be clearly recognizable mats between the meat and the packaging, or it can be a bag shaped package which looks like it could contain something edible.
As it is something made to contain the liquids drained out of the meat and hold it, I do not think you should use it or anything coming out of it, as you can not know what they put in to hold the liquids. (Although it should be food safe as it is in contact with the meat.)
I see that @Tetsujin in a comment calls it a meat diaper, which seems to fit the bag and mat types.
Answer: Quite likely it's an oxygen absorber.
Comment: or 'meat diaper'.


When you delete a 'label' from your Google Contacts

Question: When you delete a label from your google Contacts, (Delete label but keep contact info) where does the contact info reside now?  I assumed it would go to the main Google "contact"  list, but they did not.  Help please.
Answer: If they're not in your main "Contacts" list, look in "Other Contacts". (Scroll down the left navbar to near the bottom.)
"Other Contacts" are...

People you've interacted with in Google products, as well as any contacts you've hidden from your list. These contacts appear as autocomplete suggestions to help you communicate and share. Go to your Google Account to control how these contacts are saved.


So my email keeps popping up on iMessage instead of my number why?

Question:
 So I just recently noticed that my iMessages we're going in as my email instead of my number why is that?  I just want somebody to help me figure out how can I get  it to change into my number instead of my email  I tried turning it off and doesn't work I try resetting my phone doesn't work and every time I try to click where it says my number it's all Gray with a little  has a a loading icon on the left.
Answer: There have been some quirks with this from time to time. As you can imagine, where it says "START NEW CONVERSATIONS FROM" should have your phone number listed as an option.
Try to get it to show up by doing the following, go to "Settings -> Messages" and go to "Send as SMS" and toggle that on. This will shut off iMessages and force your phone to only send SMS messages using phone number.
Try sending a message or two before coming back, then toggle "Send as SMS" off and go back to "Settings -> Messages -> Send & Receive" and your phone number should be listed under "START NEW CONVERSATIONS FROM"


Alchemy Websocket Sub with Filter on Arbitrum Returns No Messages

Question: The following sub with filter is not resulting in an error and no messages are received for newly mined txns:
'{"jsonrpc": "2.0", "id": 1, "method": "eth_subscribe", "params": ["alchemy_minedTransactions", {"addresses": [{"to": "0xb87a436B93fFE9D75c5cFA7bAcFff96430b09868"}], "includeRemoved": false, "hashesOnly": false}]}'

The websocket seems to work fine (receiving messages) for non-filtered subscriptions:
{"jsonrpc":"2.0","id": 2, "method": "eth_subscribe", "params": ["alchemy_minedTransactions"]}

Using wscat -c wss://arb-mainnet.g.alchemy.com/v2/API_KEY to subscribe. API docs
Anyone else seeing this issues or any ideas how to solve? Am I missing something in the filtered sub message or have the docs changed? Thanks for any help.
Answer: All address chars need to be lowercase:
0xb87a436B93fFE9D75c5cFA7bAcFff96430b09868 should be 0xb87a436b93ffe9d75c5cfa7bacfff96430b09868


Etymology of 'Space' as applied to inter-planetary or inter-galactic separation

Question: The word 'space' literally means 'emptiness' or 'expanse'.
When did the term begin to be used to the emptiness between planets/stars/galaxies?
Comment: https://www.etymonline.com/search?q=space
Comment: I would suggest that 'space', used astronomically, means that which _contains_ the items in the universe rather than that which separates them. Many theories suggest, and it is logical to accept the general hypothesis, that 'space' (the astronomical term) is a construct, not a vacancy and is the medium _which communicates light_, rather than the emptiness through which it travels.
Answer: From 1582:

Consider the huge substance of the earth, so heauie and great as it is: How could it so stand stably in the space as it doth, if GODS goodnesse reserued it not so for vs to trauell on?

That citation is from The Second Book of Homilies, sermon 17 (text) (Wikipedia).  It is the oldest citation in the OED under the eighth sense:

8. The expanse in which celestial objects are situated; the physical universe (excluding celestial objects) beyond the earth's atmosphere, consisting of near vacuum with small amounts of gas and dust. Frequently with modifying word.

If you look through the text of the sermons in The Second Book, you'll see that space usually refers to time, as in this quote from the 7th sermon:

there fell no rain vpon the earth for the space of three yeares

In fact, the first branch of the OED's definitions, and the earliest citations contained therein, refer to "space" meaning time, although the word had also been used to mean physical distance as early as circa 1350.
Outer space doesn't come until much later, first appearing in 1842 in Emmeline Charlotte E . Stuart Wortley's poem The Maiden of Moscow:

All Earth in madness moved,—o'erthrown, To outer space—driven—racked—undone!


Using definition queries in GeoMedia Professional?

Question: Does anyone know if GeoMedia 6.1 Professional has a selection feature that is equivalent to ESRI's ArcMap Definition Query function or anything similar to it?
Answer: I had to Google Definition Query, and I understand it is a way to filter or mask certain objects from a feature class that has already been added to a map. (But maybe I am mistaken?)
As far as my knowledge goes there is not a tool that does exactly that in GeoMedia, although you can do pretty much the same by using Analysis / Attribute Query on your desired feature class, define your criteria using SQL and then add the result of that query to the legend.
You can then use Analysis / Queries to go back and edit the query as you like. The queries are dynamic, so the result is reflected instantly in the map window.
Answer: Yes.  Geomedia is great for querying.  The whole platform is built around querying really - even geoprocessing results are queries so as the source layer is updated the processing results (such as buffers) are also updated until they are output to a separate feature class.  This is great for drafting, and because geoprocessing queries can essentially be built into a chain which update dynamically there is no need to re-run processes when the source layer changes, or if you want to change the size of a buffer zone; you just edit the query.  In my opinion Geomedia does these basic things like querying, print layouts and feature styling a lot better than Arc - unfortunately I haven't used it deeply enough to know if it the same depth of tools.  I do however know that the basic tools that I think most users will use day to day are much more flexible and better organised.  Geomedia is an incredibly well thought out program, clearly designed and built from the top down compared to the sprawling mess that is Arc.


What can I use instead of a corkscrew?

Question: When travelling, we may want to obtain some wine, but I don't want to have to bring a corkscrew with me. What can I use instead?
Comment: Normally I have a Swiss army knife with me when I travel. In the baggage when I fly but still
Comment: I missed this question while travelling. It's really not directly related to travel - if we accepted it, we'd have to take any 'what can I use instead of' - splints, chairs, stoves, knives, etc etc. Discussing first with other moderators as it's been left open a while, and they may have had a reason for doing so.
Answer: My preferred method, because it requires no special equipment:

Wrap the bottom of the bottle in a towel, or place a phone book against a wall or tree.
Hit the bottom of the bottle firmly and evenly against a reasonably flat, vertical surface (such as the wall, or a tree). The pressure of the wine against the cork will gradually nudge the cork out.
As an alternative, you can hold the bottle upside-down between your knees and strike the bottom of the bottle with a shoe.
Once the cork is partially out, remove it with your hands or pliers. Alternatively, you can continue hitting the bottle rhythmically until the entire cork comes out. If you are trying to open a carbonated beverage (e.g., champagne or lambic), let the bottle sit for 10-15 minutes before removing the cork.

Found the steps on WikiHow, complete with video, and several alternate methods.
Comment: Depending on how many wine snobs there are around you, you may get some funny looks for banging a wine bottle. But it isn't a bad idear.
Comment: Definitely will outrage the purists, but check this shoe-as-cushion-against-hard-wall technique: http://www.youtube.com/watch?v=YAx2TXt1v_I
Answer: Simply push the cork down into the bottle and pour.
Comment: i can't believe this answer is so undervoted. This is wine purist approved, btw (as long as you clean the exposed part of the cork, so that dust/lacquer doesn't get into your wine). Even if you get cork bits in your wine, you can filter/decant it (again, wine purist approved).
Answer: A small, but incredibly useful device is the CO2 cork remover. Basically it has a needle you stab through the cork, and then you press the trigger to pump CO2 into the bottle, forcing the cork out.
It weighs about the same as a corkscrew though, so your better bet may be:
Buy wine bottles with screw tops!
Comment: No offense, but in some places, such as Tuscany, one might call that blasphemy ;)
Comment: Screw tops aren't a bad suggestion, but it's not always possible (if you want a specific bottle of wine), and doesn't really answer the question. :)
Comment: Heh - I know, but it's the way of the future.
Comment: +1 for just buying wine with screw tops. I just got back from South Africa, and almost every bottle I encountered was screw top. There are wine traditionalists who probably abhor that, but it's definitely becoming more common.
Comment: Would it have to go in checked luggage?
Answer: It depends on how, um, elegant you want to be about opening the bottle.
When I was living in India, I took a trip to Paris, and I brought a couple bottles of wine back with me. I totally forgot that I didn't have a corkscrew with me, and I had no idea where I could go to find one.
What did I use? A regular table knife.
I chipped away at the cork until I'd scraped out about half of it, then used the blunt end of the knife to push the rest of the cork into the bottle.
It's not classy, and you might get some cork crumbs in your wine, but it works. :)
(Note: this method probably doesn't work on plastic corks - they need to be actual cork so you can break off chunks.)
Answer: Have you considered bringing a swiss army knife that has a corkscrew. I would highly recommend tossing one in your checked bags. If you don't check bags, then buy a cheap corkscrew in your destination. I have successfully used a paperclip, but it took forever. I drilled it into the sides of the cork to loosen it and then I pushed it all the way through the center, wiggling it to make the whole wider than the paperclip. Once that was done, I pulled it out, cut off half an inch of the paperclip and tied this to a piece of string. I pushed the small piece of paperclip with the string through the hole in the cork and pulled up on that hard. The cork came out, but it was a project. Corkscrew is easier.
Comment: I said that above... "If you don't check bags, then buy a cheap corkscrew in your destination."
Comment: These types of devices often aren't allowed in carry-on luggage. And it would be a shame to check a bag just so you can open a bottle of wine later.
Answer: If you are in a big city, walk into a hotel that has a hotel bar (even better if it is your own hotel).  Act like you are a guest at the hotel and kindly ask the bartender to open the bottle for you.  It's nice to give them a tip, but that would likely be the price of a cheap corkscrew anyway.

What can I use instead of a corkscrew?


Is sodium acetate strong or a weak electrolyte?

Question: Since it is formed of a strong base and a weak acid it should be a strong electrolyte but a chemistry teacher said that it is a weak electrolyte.....
Answer: Sodium acetate is a strong electrolyte in water.  The status of sodium hydroxide as a strong base triumphs; it makes even a weak acid such as acetic acid dissociate essesitally 100% into ions (by stealing the protons).  And when something is essentially 100% dissociated into ions, by definition it's a strong electrolyte.
Answer: A misconception, I feel, that maybe some other students have made after tackling equilibria for the first time. Let me explain by first giving the equilibrium expressions regarding acetic acid and its conjugate base:
\begin{align}
  \ce{CH3COOH + H2O &<=> CH3COO^- + H3O+}&
  \mathrm{p}K_\mathrm{a} &= 4.76\\
  \ce{CH3COO^- + H2O &<=> CH3COOH + OH-}&
  \mathrm{p}K_\mathrm{b} &= 9.24
\end{align}
I essentially deduced that since both equilibria constants were quite small that both acetic acid and, hence, sodium acetate would constitute weak electrolytes. I have since found out that though my reasoning was correct for acetic acid it wasn't so for sodium acetate.
The reason why is because, in an acetic acid solution, acetic acid is the sole electrolyte, and, hence, the equilibrium expression dictates its dissociation into ions (since it is low there will be slight dissociation). However, as for the sodium acetate solution, the equilibrium expression considers acetate ions completely dissociative from their cations, i.e. it assumes 100% dissociation of the salt. This is indicative of the sodium acetate constituting a strong electrolyte.
Answer: Strong or weak electrolytes will depend on the hydration enthalpy of products in water. That's why any salt like $\ce{NaCl}$ will completely dissolve in the water, though $\ce{NaCl}$ has high bond energy in powder form. In the above case, the hydration of the $\ce{Na+}$ ion will be so dominating that the salt will dissociate (hydrated) completely despite less hydration enthalpy of the anion.
So, as a rule of thumb strong acid/base salts will have more hydration enthalpy but it is just a correlation and will depend on the solvent. The reason for partial or full dissociation is in hydration enthalpy and entropy change.


Email Template related record not available

Question: I'm building an email template, and I want to use merge fields from either a Lead or Contact but I also want to use a related record.
I copy the desired merge fields into my template in the web-ui editor, however, when I go to send a test, I select a Contact, but in the drop-down for related records, I don't see the custom object I'm looking for as an available record type to search on. I do see other custom types that I have but don't want to use...?
Also...
If I want to build a dynamic URL for a link in the email body with the html editor, and this link is based on some of the merge fields how do I enter them? The html body of the email shows the HTML in the merge fields in the WSIWYG editor for HTML templates. It has a weblink editor - but I'm not sure where to merge the un-encoded email with merge fields, like so...ok I think I found this in the email template in the IDE...!
{!sObject.Name}

Comment: Great questions, but they're unrelated -- I recommend splitting the merge field question into its own question (and checking whether Peter's answer addresses part 1)
Answer: Check the 'Allow Activities' checkbox under the Optional Features section on the custom Object's edit page.  If you do not have that checked then the Object won't come up in the Related to Record picklist.  I don't recall in which documentation I read that, but I just verified it in my DE.  My quick search found this knowledge article.
Answer: Regarding your 2nd question, please check my blog post titled 'Dynamically populating custom HTML email template content in Force.com with custom dynamic data using Apex' which uses custom HTML email templates to send email with data populated from both standard object and dynamically computed data. The code referenced in this article uses SingleEmailMessage to send emails. It can take both email addresses of the recipients or the Salesforce Ids (if it's Salesforce user) which doesn't count against the daily limits.
Comment: If you specify a Contact, doesn't that still count against your daily limit?
Comment: If you email to contact from the Accounts / Contact page, it is not counted against the limits. But I'm not sure if that will apply to the apex code. I'll edit my reply to remove it. Thanks Phil for catching it.
Comment: I thought it did count if it was from Apex is all, I could of course be wrong.


Kernel dies or proses stuck when making LR prediction on dataframe using apply

Question: I'm trying to making predictions with a simple model.
model=LogisticRegression()
model.fit(X_train,y_train)

After fitting, i try to make predictions. A sample X_test value and the code is below.
X_train[41626]

array([-0.53668182,  0.57287544, -1.48834257, -0.6080626 , -0.86691148,
    0.24336571,  0.        ,  0.53303864, -0.05081621,  0.17409271,
   -0.21513622, -1.15424615,  0.74731522,  1.47161341])

The model fits in like 5 seconds. After below code is executed, when it gets to %5 or %6 it stops for a long time (the last stop point was 39938/326232). Sometimes kernel dies, sometimes it just stops. It stops at random row btw.
test['Predicted'] = test.progress_apply(lambda x: model.predict(X_train) ,axis=1)

I have updated all python libraries and try this code on both a windows and mac m1 machine. The result is the same.
What is the problem? I cant figure it out.
Comment: Full traceback, full model please
Answer: Try this:
test['Predicted'] = test.apply(lambda x: model.predict(x.values.reshape(-1, len(test.columns))), axis=1)


Unable to sign into my Samsung Galaxy Tab A

Question: I forgot my password and have tried to log back in I never saw anything to reset my password and now every time I try to sign in it states try in 60 minutes. I tried holding down the power and the volume button and I do not see anything to bypass the lock. How can I get back into my Samsung Galaxy Tab A
Answer: If you have Android Device Manager installed or Logged in to Samsung account these links may help you Android device manager and try resetting the password or
Samsung find my mobile do this both from any other device.


What is fTestnetToBeDeprecatedFieldRPC seen in chainparams.cpp?

Question: fTestnetToBeDeprecatedFieldRPC is a bool type variable set to some values in the main, testnet and regtestin chainparams.cpp. What is the use of this value ?
Answer: The field corresponds to false for mainnet, true for testnet, and false for regtest. You can think of it as a flag that tells you whether the current network is testnet.
Why's it named like that?
To get people to not use it, and because getinfo and getmininginfo still use it:

jtimon commented:
Yeah, comparing to the testnet id was very readable so it's the new flag. The difference is that when people see "NetworkID() == something" they think they can use that too, while FlagWithLongNameIncludingTheWordDeprecated() is not as likely to be used or that's my hope.
@laanwj explained the deprecation thing, but basically, RPCs can just use bip70's networkidstring()
For the string, I was going to create another flag but @laanwj wants to keep chainparams clean of GUI-related things. Of course comparing to an enumerator is better than comparing to a string, again, the goal is that people don't see the comparation to the enumeration and think they can call CChainParams::NetworkID(), hopefully the comparison with a string will make people use that approach less, but we need the string for BIP70 anyway.

(Source.)


How to do a count of attached opportunites

Question: As above, we have a custom style of Organisation (Adviser) that can be can be linked to opportunities via a lookup function on the opportunity itself.
 Currently in the adviser org we have a manual field to enter 'number of opps generated', i want to change this so it will be a count of all Opps which have are attached to the Adviser.
Am i correct in thinking it will be a rollup function? I could do this on excel pretty easily but i am new to salesforce . .
Any help appreciated, Thank you
Answer: You cannot use a roll-up summary field with a lookup relationship. You will need to have some code (most likely a trigger) that counts the total number of opportunities related to the adviser.
Roll-up summary fields are only available on master-detail relationship types. Abhinav Guptas has a pretty handy solution for this that you can use for development (or can ask a developer to utilise) and there is another similar solution which you can setup and use from here.


MPlayer synchronized network playback issues

Question: My team is trying to play different videos on slave machines. Each video is different but they are supposed to be synchronized in their play time. This is achieved by having a master machine that sends its play time data to the slaves.
Each machine currently runs two instances of MPlayer, which would not work normally, because two instances cannot listen to the same UDP port, but we have used Samplicator, which forwards UDP datagrams to multiple ports. Additionally, we have written our own tool that allows us to forward the datagrams of one port to another.
Both of these approaches have not been ideal so far. When using only one slave instance per machine, the synchronization works as intended. However, with two instances, the playback can get really choppy at times.
Is there any other way to get two MPlayer instances synchronize on one machine?
Our Master Command:
<code>-udp-master -udp-ip {_networkIp} -udp-port {_masterPort} -nogui -cache 1024 -framedrop video.mp4
</code>
Our Slave Commands:
<code>-udp-slave -udp-port {MasterPort} -xy 1920 -geometry 0:0 -noborder -cache 1024 -framedrop video1.mp4
-udp-slave -udp-port {MasterPort} -xy 1920 -geometry 0:0 -noborder -cache 1024 -framedrop video2.mp4
</code>
Answer: We solved our issue by using just one video with a resolution of 3840x1080. This way we dont need a second instance.


Show all mail rules on Office 365 web admin interface

Question: As by subject: is it possible, and how, to show all mail rules (especially incoming/forwarding rules) from the Office 365 admin interface locate at https://portal.office.com ?
I know that the Exchange Admin panel shows any transport related rules. However, I can not find where user-defined rules are reported/summarized.
I also know that it is possible to use powershell to retrieve these information, but I feel I am missing something on the web admin interface.
Answer: shodanshok,
This functionality is available in the O365 security portal.
Here's the documentation link.
For what it's worth, alerting of new forwarding rules were automatically turned on over the past couple of weeks by Microsoft, via an update.
PS - Fully aware that this is a year old, but others may end up here.


What is the fastest animation on the iPad

Question: What is the fastest animation on the iPad? There are multiple flipping types, what is the fastest one?
Answer: It's not really clear what you mean by fastest. If you want a speedier animation, you can always change the duration with <code>[UIView setAnimationDuration:(NSTimeInterval)duration];</code>
If you're talking about performance, on the other hand - It's really not an issue if you're managing your network calls etc. on another thread. The UI updating always happens on the primary thread, so all you have to do is detach your network calls and heavy processing.
If the heavy processing is  too heavy for multithreading to save you, then you can always look at Core Animation. It's much lower level, and faster.
Answer: You are limited by the hardware display refresh to a maximum of 60 fps.
You can do any of OpenGL, CG drawing in a drawRect, manual CALayer animation frame swaps, or use Core Animation at that frame rate if you are very very careful about how much you do on the UI thread during each frame time.


Does a bulb glow brighter if kept closer to the battery?

Question: If the surface charges propagate an electric field to cause the electrons around the bulb in the wire flow(which is why it will light up even if the circuit is as long as 3*10^8 km, if the battery and bulb are close although at lower intensity), then if the bulb is closer to the battery, this field will be stronger and the bulb at the end should go glow brighter, while if it is far away, we can say that the poynting vectors that arise directly from the battery towards the bulb will be almost 0 and at some point the bulb will reach a minimum brightness, assuming the circuit has no resistance? Or will it maintain a constant brightness. Also doesn't this mean that a broken circuit will still light up an LED at it's end?
Answer: For your hypothetical case of 0 resistance circuit, and lets assume also no inductive of capacitive effects, then in the steady state I think the bulb will be just as bright no matter how far it is from the battery. However this is not at all realistic or representative of the real world. In reality resistive losses would build up over the length of your circuit, though the effect may be minimal, it would result in a less bright bulb further from the battery I believe.


Reason behind conversion of acid to acid bromide in Hell-Volhard-Zelinsky reaction

Question: Why in Hell-Volhard-Zelinsky (HVZ) reaction the acid is first converted to acid bromide by using $\ce{PBr3}$ and then alpha halogenation is carried out?
Comment: How do you think the alpha-bromine is incorporated into the acyl bromide? Homework???
Comment: Google is your friend!
Answer: The $\alpha$ halogenation occurs through the enol form.
The formation of the acyl halide is key because carboxylic acids do not form enols readily since carboxylic acid proton is removed before the $\alpha$ hydrogen. Acyl halides lack the carboxylic acid hydrogen.
The phosphorus halides form the acyl halides readily because phosphorus has a huge affinity for oxygen.
Sometimes, phosphorus tribromide is not enough to form the acyl halide but, since there is also bromine in the media, phosphorus pentabromide is formed which can form acyl halides even of solid acids.
The halogenation is performed by the $\ce{X2}$, either bromine or chlorine.
When $\ce{PBr3}$ and $\ce{Cl2}$ is used, the alpha-chloro acid is obtained and not the bromo acid.
Comment: This was a question where AJ needed to make some effort in offering a solution.
Comment: @user55119 Understood. However, I hope it will serve others as well.


Arrival at Schipol airport at 6 am from close to Kronenburg tram stop?

Question: We are staying very close to the Kronenburg tram stop (Amstelveen) and we need to be at the airport around 06:00 for an international flight. Would it be possible to catch a bus that early? And if so, where?
Comment: What day of the week? If I recall correctly, things start up at around 5 on weekdays, 6 on Saturdays, and 7 on Sundays.
Comment: a weekday. I thought things didn't start up until 0600 but I guess they start up earlier.
Comment: Amstelveen is in the city area for Amsterdam and there are night services in the area, besides, a lot of people working shifts in factories and at the airport change shift at 6 AM.
Answer: You can get travel information in all of the Netherlands on this 9292 site.
At this time I can not get the English version to work but the Dutch version did deliver results.
On a normal weekday this schedule will work.
Leave the Metro/tram stop at 5:29, metro 51, to metro/tram stop Oranjebaan, walk to bus stop Oranjebaan and take bus 300 to Schiphol. You should arrive just before 6 AM.
From this time of day onward there are regular metro's, trams and buses, overal travel times run from 22 to 35 minutes. (About 4 different connections will get you at Schiphol before 6:30.)
Earlier connections are by night bus and run about once per hour.
Weekends you are longer dependent on night buses. But those on Sunday morning seem to run every 15 minutes or so and take the same amount of time.
If there are several of you, look into a taxi, that might work out cheap enough. Pre-booked taxis are also available.
Comment: OK I will go this site. Dutch will work Thank you.


Login block is missing from my theme

Question: The default login block is not listed in my theme's blocks, if I switch to Garland, it's there and if I type the direct path to the block I can access it, but I can't seem to save it to my block page... does anyone know how to resolve this issue?
Answer:
Go to /admin/structure/block
Go to your theme (top tabs)
Move your login Block
WIN!
Comment: But the login block isn't listed anywhere on my theme block page, it's not in the disabled section or anywhere else.
Comment: are you on your admin theme or on your public website theme?
Comment: I am not sure what you mean, I use Garland as my admin theme, but the block list displays in my custom theme...
Answer: If your login block is missing from your blocks then

from the Structure->Blocks view click on a tab that has another
theme, different from your custom theme, preferrably Bartik or some
other default theme.
Now locate the user login block there and click configure.
Set it to whatever region you want it to appear in your custom theme.
Navigate back to your theme using the tabs in Structure->Blocks

Login block is missing from my theme


Can one give a professional lecture on Sabbath?

Question: Would it be okay to give a professional conference lecture on Sabbath? Someone told me it would be okay as long as the speaker doesn't touch the microphone or the slides computer, but that doesn't seem right. Wouldn't there be a problem with the lecture itself?
Comment: Assuming that you're not doing any specific *melacha* (Shabbat "work") such as travelling to get there, I can't envision any problem. It sounds no different than a rav giving a speech or shiur on Shabbat, in that you're talking. Two problems, PERHAPS - 1) It may not be in Shabbat spirit to discuss secular subjects or to give a secular lecture and 2) If Jews are attending your lecture, the fact that you are giving this lecture may be encouraging them to write notes and / or to travel. R. Feinstein was against the idea of a "beginners" minyan in a shul that would cause people to drive on Shabbat
Comment: Remember that even if it would be theoretically permissible, would it be in the "spirit of Shabbos"?
Comment: @DanF "V'daber Davar" is assur d'oraisa according to many. This would most probably fall under that category
Comment: @Ezra A bit subjective, but I personally think no.
Answer: (Of course, for any practical ruling, please consult your local Orthodox Rabbi)
Assuming that all technical prohibitions are avoided (which is in itself quite difficult; even if, using your example, you don't change the slides on the computer, it might be forbidden to have a non-Jew move through the slides on your behalf as you speak. But the details of that are beyond the scope of this answer), this would likely still be forbidden.
There are a number of "catch-all" prohibitions on Shabbos that prohibit one from doing actions that, while no Melachos are being violated, is forbidden for being not in the "Spirit of Shabbos". This is learnt out from the verse in Isaiah 58:13

If thou turn away thy foot because of the sabbath, from pursuing thy business on My holy day; and call the sabbath a delight, and the holy of the LORD honourable; and shalt honour it, not doing thy wonted ways, nor pursuing thy business, nor speaking thereof;

One of the things we learn from that verse is that one is forbidden from speaking about business related matters on Shabbos. Presumably, your example would fall under the general umbrella of speech that is forbidden on Shabbos.
See Shulchan Aruch Orach Chaim Siman 306 for a more detailed treatment of the prohibition of forbidden speech on Shabbos.
Comment: Yes, I think I remembered that verse in Isaiah. That's why I thought there was a problem with the lecture. This would be a professional lecture, as in, for the benefit of a specific industry or professional community. In other words, business related.
Comment: "No business of man" is the phrase I was taught.
Comment: I'm going to give a select for now, but it'd be great if you quoted a prominent rabbi. I can't be the first person to wonder this specific thing.
Comment: "I can't be the first person " - You definitely aren't. A close friend of mine frequently attended podiatry lectures on Shabbat, and was allowed by his rav to do so. I don't know if he gave any lectures, though. The prohibition, above, applies to performing non-Shabbat matters of all sorts, not just "speaking" with the mouth (or hands, etc.) I'll see if I can get some details on the practical applications of attending or giving a secular lecture. Apparently, there are leniencies, but I don't know the details.
Answer: The interdict "nor pursuing thy business, nor speaking thereof" (trans. from @Salmononius2) is indeed a general umbrella. For example, business-related documents are forbidden to read on Sabbath (TB Sab. 149a). The reason for this is of dispute; some apply the aforementioned interdict (Rosh, Sab. 23:1) while others forbid it as a precaution so one does not mistakenly feel it's weekday and erase [writing] (Rambam, Sab., 23:19). Some even advance that it is only forbidden to orally read such material (Mordechai, Sab., §254), yet, most authorities side with the Shulchan Aruch that even not orally is forbidden (OC 307:13).
However, IMHO a lecture would fall into more defined parameters. SA (ibid. 307:17) advances an opinion that it is forbidden to learn anything -including educational material- except Torah on Sabbath and holidays. Then, he cites a dissenting opinion which allows such study. The Mishneh Berurah (loc. cit. 65) notes that the lenient view is more prevalent.
Furthermore, OP indicated in a comment that the topic of this lecture would be medical-related. The study of such material is even considered by some to be a mitzvah (as it can enable one to save a life; cf. Rashba 1:415, Chazon Ovadiah, Shabbat vol. 3 pg. 32). R. Yitzchok Zilberstien permits one to partake in a medical lecture provided the technical issues are taken care of/avoided (Shiurei Torah LeRof'im, vol. 1 pg. 103). Rabbi Dr. Abraham (Lev Avraham vol. 2 pg. 58) also permits one to partake in such a lecture (though advises not to ask a non-Jew, on Sabbath, to take notes for him). R. Elchanan Prins (Avnei Derech vol. 8 314) discusses a question where a rabbi was giving a medical lecture at a seminar on Sabbath and during summation noticed a [Jewish] member in the audience taking notes. The rabbi was posed with the question how to proceed. R. Prins cites numerous personal correspondence that he conducted with rabbis (containing different suggestions) while none raised an issue with having the lecture.
Comment: Thank you for the detailed response (even more detailed and complete than mine; take my upvote! :) . I didn't see the OP mention anywhere that this conference was medical (perhaps that specific comment was deleted). I agree that the Halacha is more lenient for Mitzvah related matters, and that medical issues could very easily fall under that category.
Comment: @Salmononius2 You're too kind. I had inquired (IRC after you posted your answer, therefore you didn't see it) of OP in which he indicated so in a comment. I now see both comments were deleted.


Block Disposable Emails on Woocommerce Registration

Question: Is there any way to block disposable emails on Woocommerce registration? I used this plugin with a list of disposable email domains, but it would only block on regular registration - not Woocommerce registration. Any ideas?
Comment: https://github.com/Ipstenu/ban-hammer/wiki#woocommerce
Answer: Hi just add this code in your theme functions.php
<code>add_action('init', 'mydomain_plugin_checks');

function mydomain_plugin_checks(){
    if ( class_exists('BanHammer') ) {
        add_filter('woocommerce_registration_errors', 'woocommerce_banhammer_validation', 10, 3 );
    }
}

function woocommerce_banhammer_validation( $validation_errors, $username, $email ) {
    if( (new BanHammer)->banhammer_drop( $username, $email, $validation_errors ) )
        return new WP_Error( 'registration-error-bad-email', (new BanHammer)->options['message'] );
    return $validation_errors;
}
</code>
Answer: If I am right, are you asking a WordPress plugin which can validate emails from Woocommerce Registration? If so, there is some WordPress plugin that are capable to solve your problem.
Basically those plugins will get the emails inputted from Woocommerce, validate it and return the result back to the form. Some of the plugin will require you to sign up the API key before use.
Currently I am using MailboxValidator Email Validator, which did a great job on protecting my website from disposable email address.


Can I flip my worn chain to extend it's life?

Question: Assuming my chain is showing that it's worn and getting close to needing replacement due to chain 'stretch'. I know you can flip single speed chainrings to extend their life when they become worn. Can I flip the chain around to extend it's useful life? I  doubt it would double it due to some overlap in wear on rollers, but possibly extend it a bit by putting load on the opposite side of the pins.
Comment: (Keep in mind that when the chain is in use the front sprocket is bearing on the opposite side of the pins than the rear sprocket.  The wear is about as symmetrical as can possibly be imagined.)
Comment: No.  As others have said, the main "wear" that a chain experiences is in the plate joints, resulting in "chain stretch" that will be identical either direction.  And when you use, eg, a chain stretch gauge you're inherently measuring both sides.
Comment: Chain wear indicator measures distance between 2 points. And distance is simetrical function: dist(A,B) == dist(B,A)
Comment: I guess the big test would be to take my chain wear indicator and see if the measurement differs directionally.
Comment: I would be measuring different sides of the pins/rollers to see if the wear varied by side. It would not be measuring the same 2 points.
Comment: Chains are cheap - buy a new one.... "If in doubt, throw it out"
Comment: Try this: Rotate your chain 90 degrees and see if it works any better :-P
Answer: I would say that this won't have any effect.
Flipping the chainring on a single speed makes sense as you use the other side of the teeth on the chainring which have not been used before. But with the chain it's a different story: The stretch is independent of directions so reversing its direction won't change anything. Also on the small "rolls" in the chain links on which the chain lies on the chainring I wouldn't expect any effect as they aren't fixed in the links but can rotate and therefore should wear out equally all around their circumference.
Comment: The rollers would likely wear relatively evenly, but I wonder about the pins and plates that the rollers rub against under load.
Comment: @Benzo: A majority of the load (therefore wear) is on the first couple of links going onto the cog - when the chain is virtually straight. Therefore flipping it would not make any difference.
Answer: buy a new chain if the gauge indicates excessive stretch- just as you should. if you are a fanatic about extending your drivetrain's longevity- keep everything clean and lubed to the highest degree you find practical. and if you flip it over (there are FOUR different ways to fit a symmetrical chain)- remember- edges on the links will have to go thru the break-in process (link edges rounding off) regarding the left side of the larger chain ring (or chain rings if a triple) all over again- more so in a conventional crankset, as opposed to one featuring ramps and pins. i don't want to install my chain differently in any case- i mark it with a bread-bag tie before removal to assure proper orientation upon re-install. i ride my roadie only on the paved roads within my ranch- when i see dark sludge on my cog/chain ring teeth- its time for a cleaning/lube. after 4 years (>2K) of riding i have yet to detect any measurable stretch (love shimano chains). think about it- if you flip the chain over on the gauge- do you think it would measure differently?.....happy pedaling!
Comment: But that doesn't make sense.  The part of the bike chain that engages with the teeth of the cog - the rollers - well, they _roll_.  So there is no "edges" or "side" to them.  You could perhaps flip the chain rings around, but then the ramps won't be facing the right way and that doesn't extend the life of the _chain_.  Could you maybe include some pictures to show what you're describing?
Comment: when i switched to a super-narrow, hyperglide chain i experienced slippery upshifting on my triple crankset. all the techs i talked to (except one) said i used the wrong chain and to 'live with it or get a wider chain'. the one exception (tony at alpine rides) said to stick with it and re-install it the same way each time. he was right- now my chain climbs right up my 32-42-52 chain rings. all it took was the breaking-in (rounding) of the link edges. he told me this and i was ultimately rewarded for believing him- can't believe he's a substitute bike tech!


outlook rules not working automatically

Question: I am using outlook 2007 and am using wsus to install all the updates to the client.I have created the rules and alerts in outlook 2007 but some of the mails are not getting delivered to the concerned folder.Please give suggestion?
Answer: Maybe this Microsoft Support article can help:
After you configure one or more client-only message rules in Outlook, other message rules do not take effect
The thread Outlook 2007 - rules do not run automatically contains some more advice :

Turning off Use Cached Exchange Mode
Export, delete and re-import the rules, restarting Outlook at every step

The thread Microsoft Outlook 2007 Rules not working help claims that all email addresses should be defined as contacts before the rule is created.
Apparently, making Outlook rules work is somewhat of a black art.
Comment: I have one rule created and got some server error. I cannot open / edit / delete the rule after. And I don't see the rule in webmail either. I tried the 2nd approach: "Export, delete and re-import the rules, restarting Outlook at every step". After I re-import the rules, all my rules are not working anymore. Now I have to re-create my 50 rules from scrath again.
Comment: The links provided were not any help in my case. I followed the steps in the MS article even with empty rules and just adding server side catigory rules they would not work.  Im using 2010 though I see the same in all versions of office.
Answer: As a long suffering Outlook user who has finally persuaded his company to go Google, just forget about using Outlook rules unless they are server based, they just don't work without constant supervision.

outlook rules not working automatically


electric field outside two parallel conducting plates

Question:
Hi, I'm confused about this question. I watched a video, and it said that the electric field in region 1 equals the electric field in region 5, and I wanted to know why. Is it just a property of two parallel conducting plates that the electric field outside either plate is the same? I would understand that if the two metal slabs were 4 non-conducting sheets of charge, the fields in regions 1 and 5 would be equal since the fields from each sheet are additive and don't depend on distance; however, the question says that they are slabs of metal, so you have to use properties of conductors, and you don't find out until later that the charge densities on the outside surface of each plate is the same. Any help is appreciated. Thanks!
Comment: The problem statement does not include a "question" so it is not clear exactly what "question" you are trying to answer.
Answer: Revised Answer
The field in regions 1 and 5 has the same constant magnitude (opposite in direction), independent of distance from the plates (provided this distance is small compared with the width of the plates). This occurs because the plates are parallel and the electric field from each is uniform, independent of distance from the plate. It is true for any number of parallel planes of uniform charge density, and does not depend on them being conductors/insulators.
The electric field from each face of the plates is uniform and points away from that face. Suppose the charge on each face is +ve. Then in regions 1 and 5 the electric fields are all equal and constant, and all pointing in the same direction (all up in region 1, all down in region 5), so they add up to the same value in region 1 as in region 5.
The fact that the plates are conductors makes no difference. The excess charge will be distributed evenly over each face, probably with a different surface charge density on each. Each conducting plate is then equivalent to 2 infinitely thin planes of charged insulating material.
Comment: For the Gaussian Surface you are describing, the conclusion would be that the electric field given off by both inner surfaces is equal. How would you know that the electric fields in regions 1 and 5 (facing the outer surfaces of the plates) are equal though?  If you use Gauss's law for a surface surrounding both plates, you would get that flux = E1A + E5A = 3Q/epsilon, but how do you know E1 and E5 are equal?
Answer: Actually, you are quite right in worrying, why the magnitude of the electric field is the same in areas 1 and 5.  To show that unambiguously, additional assumption of no "external electric field" is required.  That is, in the analysis in the previous answer, if som external field is present, it will add positive flux through one of the bases of the Gaussian Surface cylinder, and negative flux of equal magnitude through the other base, leaving the Gauss theorem unchanged.  If you assume that there is no external field (and that is quite often an implicit assumption in most of the electrostatic problems), then you'll get to the conclusion that was given in the video.


References about the theory of linear regression or regression in general

Question: I am looking for references about the theory of linear regression or regression in general. More specifically, I am interested in knowing under what circumstances an estimated regressor is going to give accurate solutions with certain probabiltiy. For now, I am looking for the basic classical results, nothing too fancy or modern.
Answer: A classic reference for the theory of general linear models is Searle: Linear Models
@article{searle1971linear,
  title={Linear models},
  author={Searle, SR},
  year={1971},
  publisher={Wiley Series in Probability and Mathematical Statistics}
}
Answer: If your looking for basic statistics I recommend Khan Academy, they have an excellent series on the theory of regression lines. You can alson check out this thread about free statistical textbooks.


Is there anyway to overcome thef potassium sorbate in apple cider to make it ferment

Question: I have 5 gallons of apple cider that I an trying to ferment with 10 lbs.of clover honey 3.5 lbs. brown sugar to make cyser.the OG is 1.172 PH 3.6 and I can't get to ferment!I found out there is potassium sorbate in it.Is there anyway to get it to ferment I have put a lot of money in it .Can anyone help me?
Comment: The 3.6pH probably isn't helping much either.
Comment: How much yeast have you added?  You need a lot of very active yeast to get something like this moving.
Comment: @brewchez 3.6pH isn't terrible for mead. That potassium sorbate, however, will definitely keep it from taking off (OP can get around this, as you posted in your answer). Also, the extremely high OG is enough by itself to stall most yeasts without a strong starter.
Answer: You need to get that monster on a very active pitch of yeast.  I'd recommend getting a couple packages of yeast going in a gallon of wort.  Once its at its peak of activity I'd pitch it into this cider bomb.  If there is preservatives in your cider source, you can over come the preservative to an extent with a large pitch of ACTIVE yeast.
If you have a batch of beer that's done fermenting then rack the cider onto that cake and keep it warm 70-72F.
Comment: Fun fact, you can use this same technique to make wine from Mountain Dew (or any soda, really): https://www.homebrewsupply.com/learn/brew-the-dew-mountain-dew-wine.html
Answer: If you have a stuck fermentation,  EC-1118 is your friend.  Like Brewchez suggested, get that stuff roaring, then toss it in.  EC-1118 will chew through damn near anything and will do it in a big damn hurry, too.  What you're left with will be dry and subtle flavors might not be as present as they'd be with a less vigorous fermentation, but it'll work, which is more than can be said about some of the other yeast strains that are usually great for cysers.


Is there any way to restart the Tiny Death Star Holiday Decoration Event?

Question: The Holiday Decoration Event may have started a month ago, but, it only showed up yesterday in my game.  And, it says there are 0 days left. The app was updated as soon as it was released, but there was no sign of it in-game. Is this a bug? If so, are there any fixes that I can apply?
Answer: Did you update your app when the decoration event was first started about a month ago? That may have caused the issue that you are experiencing.
Comment: This answer should be a comment. But, you are correct. The issue is most likely a lack of updating the app.
Comment: Thanks guys. The app was updated when the update came out. And I checked the re checked it a week later, so it's not that..
Answer: I don't believe there is anything you can do about this.  The event has ended, and there doesn't appear to be any way to reactivate it.
The only recourse you might have:  email Disney customer support and explain the bug to them.  firstname.lastname@example.com
If you click on the menu button and choose the wrench, and then click the help tab you will see long string of numbers.  If you include this set of numbers, they may be able to help you.


Syntenic gene browser

Question: I found that there is a Syntenic gene browser at GEvo. Do anyone know where could I find a similar browser for a local installation?
Answer: The UCSC genome browser supports local mirrors. You could make a local mirror that has the "TransMap Alignments" cross-species gene track. From the track description page:

These tracks contain cDNA and gene alignments produced by the TransMap cross-species alignment algorithm from other vertebrate species in the UCSC Genome Browser. For closer evolutionary distances, the alignments are created using syntenically filtered LASTZ or BLASTZ alignment chains, resulting in a prediction of the orthologous genes in human. For more distant organisms, reciprocal best alignments are used.

They provide a helpful tutorial on setting up a local installation here.

Syntenic gene browser


Loading data from shapefiles into specific feature classes

Question: I am trying to bulk load a collection of shapefiles into empty feature classes in ArcMap 10.2.  The issue here is that the names of the shapefiles and the feature classes need to match up.  Is there any way to make this happen in Model Builder or arcpy?
Answer: Take a look at this tool Feature Class To Feature Class (Conversion), the help section contains sample scripts if you want to go the arcpy path.
Right clicking on the tool reveals a "batch" option, you can set the names how you want.
Comment: Wow I can't believe I missed that.  I was overthinking the problem trying to use model builder to figure something out.  Thanks a lot, that was a bit of a rookie mistake.