Would piano or accordion be easier for me as a guitarist?

Question: I want to learn a new instrument and I feel like piano or accordion will really help me with my music theory. The thing is, all of the other instruments I play are "strumming" instruments like guitar and ukulele. Which one would probably be easier for me to learn? (Just for clarification, I'm talking about a piano accordion and I would be teaching myself the instrument.)
Comment: Regarding music theory, I could never see why keyboard instruments would be any more useful for this than guitars. Sure, you can perform more independent voices on organ than on string instruments, but that's not really necessary for theoretical understanding. IMO, theory benefits greatly from seeing the _symmetries_ in harmonic relations, and the standard keyboard layout rather obscures this.
Answer: It's generally considered that keyboard (piano) is the best instrument to use when trying to understand (unravel!) theory. If you mean a piano accordion, then the keyboard part is similar - except it's not as readily see-able as a piano. You've also other issues, like left hand is doing something entirely different, AND you have to keep the thing moving otherwise it goes rather quiet. If it's a button key accordion, it's even more remote. One big advantage is it isn't big, so can be played virtually anywhere. Not the same as a bulky piano.
If room (and THE room) are not issues, go for a piano. Also there are probably more pianos around for you to play once you are proficient. I see more pianos on my travels than accordions. Maybe because they're harder to pack away!
Going back to practice, an electronic piano can be played silently, not so sure with an accordion.
Comment: There are now also electronic accordions available (e.g. Roland V-Accordion). Not as cheap as electron pianos, though.
Answer: I'd recommend chromatic button accordion since its keys are arranged according to chromatic pitch, like those of the guitar, making it better suitable for improvised playing.  The keys of a piano (or piano accordion) instead mimic the note layout in scores: if you are going to do a lot of sightreading, that simplifies things.  Button accordions (particularly for band use) are also smaller in size which makes them more feasible for playing while standing up.
However, those are players' considerations: as a music theory aid, the button accordion is a mixed blessing.  When having one with white and black buttons, at least you can spot the staggering of semitones and see how this maps to scales when moving your hand across for transposition.  It would probably not help more than keys however.
With regard to accordion vs piano: accordion makes it easy to do chord accompaniments since the "standard bass" offers one bass note or one chord per button.  That's very convenient when playing solo; in band context however you are more likely to just use the right hand for playing and the left for bellows control since the rhythm section is usually left to other band members.
For music theory, this simple accompaniment (even though it's arranged in circles of fifths) is essentially useless.  You'd need a free bass or converter in the left hand to have single notes there, and the single notes in the left hand are arranged in chromatic button accordion manner anyway.  So there is little sense in going for the bulkier piano keyboard for the right hand when you are playing single notes in the left: you'll need to learn the system anyway.
Piano is a percussive instrument, accordion is continuous tone.  Percussive instruments are easier to balance out with other instruments (particularly when accompaying singers) for a transparent mix since they have a poignant attack and decay.
Electronic accordions can also produce Midi.  That's particularly useful for continuous-control instruments like wind instruments and bowed strings.  However, if you are carrying a controller in accordion form, the audience expectations will be that you are producing an accordion sound.
There are also "accordion keyboards" which are flat, with either button or piano controls for the right hand.  If you play those, audience expectations will be like with any keyboard instrument.  You lose the bellows for control, however.
Accordions take more effort to lug around than guitars (even though they are nominally smaller) but less than pianos.
Comment: in deed, piano is easier to study chord arrangements and accordion are good to learn about intervals and solo playing
Answer: I play both piano and accordion and I would say piano, because:

There's a huge amount of piano learning material and sheet music for piano. Accordion has some learning material and music but it's not uncommon for there not to be an accordion arrangement of a song you want to play.
Far easier to find a piano teacher than an accordion teacher
Easier to see the piano keyboard. This is helpful while learning theory so that you can sit, look at the keyboard, and think about it.
Your piano skills will transfer well if you ever want to pick up accordion.
Left hand chords in the accordion obscure the actual notes of the chord. E.g. an E diminished chord is a single button and you don't have to know what notes are in it. On piano you have to know all the notes to hit an E dim. So piano is more instructive in that respect.
Answer: You mentioned two goals in your question.  You want to enhance your understanding of music theory but also wonder which of two instruments are easier to play.
I think the other answers have adequately addressed the differences between an accordion and a piano in terms of playability and how they relate to music theory.  And you did not really ask about the versatility or sound or ways you might use an accordion or piano - but you can probably figure that out.
As someone who plays guitar as my primary instrument (as well as ukulele) but plays a tiny bit of piano and keyboard, I would like to address the primary differences between guitar and piano - both in terms of playing as well as grasping how theory relates to the instrument.
A piano style keyboard presents a much more intuitive laterally arranged layout of notes than a guitar.  With piano, when you play an ascending note scale, you know that the next note in the scale will be to the right, if playing a descending scale, the next note will be to the left.  With guitar, the notes go back and forth - unless you play the entire scale on one string.  It's not common to play scales on one guitar string because it would require large shifts in position.  Fret spacing on guitar is much larger than key spacing on piano.
With piano, any given pitch the instrument is capable of playing, is represented by only ONE key on the instrument.  With guitar, there are several different ways to play a given pitch on different strings and frets.  Picking out a melody by ear is far more intuitive on piano because you know which direction to move and about how far, depending if your next note is higher or lower.
As far as seeing applications of various aspects of music theory on the instrument itself - piano keyboard provides a much more logical and identifiable picture.  It's easier to see intervals such as a third or a fifth.  On piano, you basically have to deal with only 12 chromatic keys which simply repeat in different places on the keyboard.  When you learn a 7 note diatonic scale on piano, you can immediately see the sharps/flats because they are the black keys.  Each seven note scale simply repeats multiple times in different octaves on different sections of the keyboards - but the keys are basically the same.  You just imagine that there are a set of 7 keys out of 12 you are going to use - and shift position to play in a different octave.
So for the reasons stated above, I do believe that learning a keyboard instrument such as key based accordion or piano, would help with understanding music theory by allowing you to see the application of the theory in a more logical visual context than on guitar or ukulele.
But as far as being easy to convert to piano from guitar?  -  In my opinion, there is not much that translates from guitar to piano, other than what theory you have already learned.  The muscle memory equation does not translate at all.  There are no chord shapes that are played on guitar that remotely resemble any chord shapes on keyboard.  Your brain must train your fingers to form entirely different shapes altogether.  There is no similarity to learning to combine a specific strumming pattern with your strumming hand while simultaneously fingering chords with your fretting hand with piano.  On piano, either hand may be used to establish the rhythm (or both at the same time).  There is not a strumming hand and fretting hand.  So you learn a different type of coordination between your left and right hand for piano - than you do for guitar.
That does not mean you can't learn piano as easily as anyone else.  And any music theory that managed to sink in from guitar, will help with understanding music theory (such as chord progressions) on piano.  But you may need to know that if you want to become a true pianist - playing both left hand and right hand parts of music written for piano, it might take a larger investment of time than what you have invested in learning guitar.
What I mean is, piano music can be more complex than guitar music.  Because with ten fingers and a foot, there can be so much more going on with the piano.  If you are playing classical guitar and fingerpicking with your picking hand and playing both bass lines and melody lines on the right hand, then you are playing arrangements that are similar to those commonly played on piano.  But of course the finger movements are completely different.
I play rhythm guitar in a band to accompany my singing.  I have another guitar player taking care of the lead guitar part and a bass player playing the bass.  If I played piano, I might be expected to play all three parts on piano.  Perhaps my left hand would be playing some base notes and some chords while my right hand played the melody and some counterpoint or harmonized with the  melody note.  And I might play a solo instrumental with right hand while maintaining a bass/chord harmony with the left hand.
So what I am saying is, that I did not have to get to be an expert on guitar to play on stage and get paid to do it - because a guitarist (other than solo classical or flamenco) is not always required to play anything much more complex than a chord progression with a few fills thrown in.  But a pianist is expected to play multiple parts of a song while maintaining the basic rhythm.
My mother was an accomplished pianist and taught piano.  I always admired what she could do.  I found it much easier to become satisfactorily proficient on guitar than to learn to actually play the piano like a real pianist.  My daughter took piano lessons for 3 years.  I can play better than she does and I never took a lesson.  I have friends who took lessons faithfully for 12 years or more on piano and I would not consider them anything more than an advanced beginner to intermediate pianist.
With either guitar or piano, there is always room to grow and to improve.  But each requires a commitment and large investment of time.  I tried piano before learning guitar.  I still try to learn piano, but for me personally, it would take too much time away from my goal of getting better on guitar - to get even to an intermediate level of proficiency on piano.
You may have the time and desire to become an expert pianist while maintaining or perhaps even continuing to improve your guitar skills.  But - you can learn some basic piano/keyboard skills that will allow you to connect the dots easier on many aspects of music theory - without spending all your free time trying to learn piano -  if your goal is not to become a concert pianist or get paid to play piano (where expectations would be higher).
If you simply want to learn enough keyboard to be able to play for your own enjoyment and be able to see how certain aspects of theory relate to a keyboard, then read this on Music Stack Exchange Learn Piano if you don't have enough extra time
Also Alternate Learning Methods for Piano  may be helpful as well.
Finally - this answer to a closed question may still show up in this link Learning Piano and Guitar in parallel  It details some ideas about how to learn both guitar and piano at the same time.
Comment: The comparison was piano v. accordion rather than piano v. guitar, although you make some valid points.
Comment: @Tim -  You are correct - but since he framed the question around guitar (.... "easier for me as a guitarist?) and which would be the easier to transition to from guitar -  I chose to address the transition from guitar to keys.  There is an implied assumption that 1) keys would help with music theory - I addressed that in my answer.  Also, I think many folk believe that it is easier to learn keys, if you already play guitar.  So since the question revolved around going from guitar to keys, I chose to address that as well.
Answer: I like your questions and very good answers. I can play a bit of piano accordion. I have a few pic's with a 48 bass. 96 bass is quite large and makes your shoulders tired. My answer is, surely you can play a tune on organ or piano keys. Borrow a instrument somewhere and just try it. Sitting with it is not a good idea as it may damage the "book", or airbag on the bottom. Standing at first like a Giraffe long neck looking at the keys. In the center of the bass knobs, C is "hollow" to feel it, with G and F below and above it. Play your first song in C,F and G. Playing a song in G, D and C is below and above the G. You can follow a little pattern similar to Guitar chords. In fact playing a guitar strumming just chords on a sing along around a camp fire is great with a piano accordion as well! Just play base knobs with chords on the keys, add a few guitars to it, and I promise a splendid sing along around a camp fire!
Answer: Not being a musician but trying to play for years on the accordion.  Here's my two cents worth having played a guitar in my teen years (strumming chords was much easier than plucking the correct string all the time).  With a regular piano or piano accordion, you will need to make what seems like huge stretches at times of your hand.  Ex. play a G7 and start on F and end on D.  It would be impossible (?) to start on a B, bypass the F and try to reach the next F up the keyboard.  On the guitar as on the chromatic accordion, there are a number of ways to do what would be impossible on a piano keyboard (at least without using two hands).  You are also used to following a number of chord patterns up and down the guitar keyboard.  On the piano keyboard, there will be four different fingerings for the more common major chord patterns: CEG/DF#A/BbDF/BD#F#.  Now add three times four for the different inversions.  On a chromatic keyboard, you can stick with one finger pattern and just move your whole hand up, down, sideways, etc.  Of course, you can also add more inversions, but the pattern movements stay the same adding only three as opposed to 12 different patterns.  Want to do a diminished chord (more fingered chord patterns on a piano).  Go for minors and 7ths.  Then maybe augmented…  It becomes astronomical!  Highly simplified with a chromatic keyboard!  Wished I had started off with one instead of wasting time on a piano keyboard accordion.  Then again as I said, I'm not a musician.  You'll also find the chromatic to be faster without huge finger stretches, unless you want to play a note 2, 3 or, maybe, 4 octaves higher or lower than the root chord (impossible on a piano accordion keyboard).  I believe since you are used to the chromatic nature (ok, some will argue about my use of the word chromatic, be kind), I believe you will learn faster with more accuracy and still learn music theory with a chromatic keyboard.  I would not go with anything less than 5 rows of buttons on the right hand.  I have a Balkan or Yugoslavian model with 6 rows of buttons on the right hand.  Russians love the B system, whereas most (?) in the US go for the C system (find out from and accordion retailer if interested).  The patterns are just flipped, but the B is more common for technical work whereas the C is more common for melodic music (ok, let me have it from you B system players).  And, you can forget for learning purposes the left hand.  There are a number of YouTube accordionists who do not even play the left keyboard.  Course, it adds an element that is really filling in a song.  And, there are reedless and totally electronic chromatic accordions (Roland, Musictech, Crucianelli, etc., etc.).  And if you go with reeds, most 5 row chromatics have anywhere from 5 – 15 shifts which throw into play anywhere from 3 – 5 treble reed blocks on the right hand.  Most will have 5 reed blocks on the left hand.  You can sound very close to wind instruments like clarinets, oboes, etc. or the beautiful, full sound of a continental French musette accordion, where three clarinet reeds play at the same time, each slightly detuned from the other.  Or, throw all of how many you have in at the same time.  The left hand offers combinations too, but usually not detuned.  Most accordions are tuned A440 or slightly above.  Oh, Crucianelli used to and may still make an electronic chromatic keyboard laid flat like a piano, but with the superior layout of a chromatic keyboard.  Good luck.  I love the accordion!!!  Neil.
Answer: In my twenties,I played a guitar, three chord trick style and accompanied myself singing, but found finger picking to be very difficult.
I have no notation skills whatever and play entirely by ear.
I picked up an eight base piano accordion and very quickly began vamping three chord trick.
Everyone is different, but I would try Accordion.
The very best instrument to get is a Hohner 48 base student.
This size is easy on the back and shoulders, whereas some of the big 120's are like iron lungs!
The Accordion is gaining in popularity and players like Richard Galiano are bringing to life such gems as the remarkable Tango music of Astor Piazzola.
Galiano plays a Victoria "Quint Converter" button accordion.
The beauty of all squeeze box reed instruments is there portability.
If you are used to ensemble work, you can join other players in modern Jazz or Folk.


SD card "damaged" after every reboot / power off

Question: When I turn off my phone, next time it says SD card is damaged and all data is gone, I can only reformat it. The phone is "gionee iq275" (also known as "Fly" in Russia), Android version is 2.3.4. What can be the source of problem? How can I get rid of it? I know, the phone is crap, but at the moment just throwing it away and buying another is not a solution.
Answer: Not sure why that happened, but I got rid of the problem by making 2 things:

Performed full format of the SD card, and
Safely eject SD card before reboot of poweroff (not sure if it's necessary)

After that, I didn't see this problem again for now.
Update
That crappy phone sometimes damages SD card content regardless of whether the techniques written above are used... it seems to be a device-specific problem. So, my advice (if anyone else reads this) - don't buy "no-name" Chinese phones! :D
Comment: This is a problem for Samsung phones and Moto Gs as far as I have seen, so it's not restricted to certain brands. Format & safe eject does not work for me unfortunately.
Answer: Adding my answer, in case someone else is having similar problem, even after a decade of original answer to question.
One way of early prevention is, format SD card into exFAT. I never used my sd card as "internal" or RAM extension, so your usage could be different. exFAT SD cards no longer have issues, whenever my phone reboots(due to update or whatever reason).
I faced this issue in Nokia and Xiaomi devices, so I put blames on Android OS way of handling external SD cards(From Android 9.0 to 14.0).
In case of recovery, easeus recovery tool has SD card option, but not free/freemium.


That's another story vs That's a different story

Question: That's another story. That's a different story.
They seem the same to me. But I hear they have different meanings. What's the difference?
Answer: If there is a difference, it is a very subtle one and may easily be ignored. "That's another story" might suggest a closer relationship between the subject being discussed and the subject being postponed. Maybe the "story" involves the same people or events. "That's a different story" could suggest a less related subject.
Again, this difference is subtle. For the most part the two expressions are interchangeable, especially for a non-native speaker.
In actual usage, "that's another story" is more common but both are found in modern English.
Answer: There may be no difference between the exact phrases in the question.
However, a difference can be more obviously detected if the sentences are rephrased.

1. Tell me another story.

A parent has just finished telling a child one story, and the child is now asking to have a second story told to them.
In other words:

→ Tell me [one more] story.

2. Tell me a different story.

The same parent has suggested a particular story be told, but the child doesn't like it and, instead, wants a different one.
In other words:

→ Tell me [a replacement] story.

The same difference in meaning between another and a different can be given in the original phrasing too, although it may not be as obvious. In both cases, however, either interpretation is possible. Normally, the overall context will determine which meaning is meant.

That’s another story vs That’s a different story


variance formula

Question: I wonder how the LHS equation changes to the RHS, because I think there should be no "n" in the denominator on the LHS, so why on the RHS there will be a variance in the numerator?
      ->
Answer: If the variance estimate is biased (e.g. MLE), then $$\hat\sigma^2=\frac{1}{n}\sum_{i=1}^n (x_i-\hat\mu)^2$$
If you substitute this into your equation, you get the RHS.
Answer: Your formula is wrong:
$$\hat{\sigma}^2 = \frac{1}{n-1}\sum_{i=1}^n (x_i-\hat{\mu})^2 \quad\Rightarrow\quad\sum_{i=1}^n(x_i-\hat{\mu})^2 = (n-1)\hat{\sigma}^2$$
and not $n\hat{\sigma}^2$. Of course, this depends on the estimator used for $\sigma^2$, but usually the unbiased estimator is used ($n-1$ in the denominator, not $n$).

variance formula


"Isotopes" in a molecule?

Question: I just learned that atoms of the same element can have different mass because of they are isotopes. If there are two isotopes in which each reacts to form the same thing. Would the mass differ in each of the two reactions? Is there a term for compounds just like the term isotope is for the atoms?
Comment: @Poutnik Sorry to say, but I actually did some google searches before. I did searched: "isotopes of molecule",
"can the same molecule differs in mass", and many others. Please stop making assumptions.
Comment: These molecule are called isotopologues.
Comment: see:[kinetic isotope effect](https://en.wikipedia.org/wiki/Kinetic_isotope_effect)
Comment: The "quick questions" without explicitly expressed solving effort are not very welcome. That may lead to hesitation to answer or even to closing a question.  If a question is asked on Chemistry SE site, the site policy expects authors to elaborate the question, e.g. by searching in textbook+online resources, writing what has been found, understood or tried and what is the stumble stone for the answer to be found. SE network aims for a  collection of  high quality answers AND questions.
Comment: It means that "I have just learnt that..." is wrong approach, implying you have not even thought about it much yet nor spent time to search for answers.
Comment: There is no term for that; we just say _"molecules with such-and-such isotopic composition"_.
Comment: @HilbertDJ Show then assumptions were wrong by what you have found. It is a basic topic in textbooks and there is plenty of available articles across Internet. Search rather by keyword set than by expressions that may not be used. For scientific topic, add "Wikipedia" keyword while searching, as it may bring you faster to  the topic. [Wikipedia](https://en.wikipedia.org) is full of articles, like [Isotope](https://en.wikipedia.org/wiki/Isotope) or [Isotopic labeling](https://en.wikipedia.org/wiki/Isotopic_labeling).  [Isotopologues](https://en.wikipedia.org/wiki/Isotopologue) were  mentioned.
Comment: OK, I stand corrected, there is a term, after all. Now, I vaguely recall having heard that those little plastic or metal pieces wrapped around the ends of shoelaces also have a name, but I don't remember that either.
Comment: @IvanNeretin I have never heard about isotopologues until today either. :-)
Comment: It's kinda sad to see that a legitimate question is being downvoted.
Answer: If 2 molecules have different isotopes of some element their masses will differ. In this respect there are 2 different terms:

Molecular mass a.k.a. molecular weight (MW) - is an average mass of a molecule. If we take many molecules (a mole of molecules) of the same substance: some of them will have isotope A, others - isotope B. Their average is going to be MW*. It's used in calculations e.g. when we want to know the mass (in grams) of N moles of some substances. Or vice versa - given the mass (in grams) we'd like to calculate how many moles of there are.
Exact molecular weight - the mass of the molecule with isotope A or isotope B. These are the masses that will differ.

*Note that in atmosphere the isotopes may come in different ratios. E.g. $Cl$ comes as 2 isotopes ($^{35}Cl$ and $^{37}Cl$) - their ratio is 3:1. So MW is not the average of $35$ and $37$, it needs to take the abundance into consideration: $\frac{0.75\times35 + 0.25\times37}{2}$

"Isotopes" in a molecule?


How do I change my site time to test my recurring payments?

Question: I am testing the recurring framework in Drupal commerce on my local mamp environment and I want to test the recurring payments. How to I trick my Drupal site into thinking it's a day later so it will trigger the recurring payment?
Comment: What about changing system date and running cron?
Comment: Why not change the interval the recurring payments happen at? Say set them to an hour or a minute. That's usually my go to for testing rules scheduling.
Comment: Not directly an answer, but might help - check out [Commerce Dunning](https://drupal.org/project/commerce_dunning) which will allow you to test failure of recurring payments. Other than that, I agree with @tunic.
Comment: @Dominic Woodman the lowest interval in 1 day in the module I am using.
Answer: If you are working with 5.3+ you can do a trick with namespaces: implementing a new time() function inside your current namespace and create a shared resource where you set the return value in your tests.
You can found a complete description in this blog post:
PHP: "Mocking" built-in functions like time() in Unit Tests
Answer: Change the time of your system/server and run cron manually. PHP reads the time from your system settings and cron is what executes the recurring product functions at the required time.
Answer: i think you can change the PHP time zone to force a time zone then change your local machine to a day later it may help
Answer: Using PHP timezone function change the timezone first.
See the links for more detail about timezone.
https://php.net/manual/en/timezones.php and https://php.net/manual/en/timezones.africa.php
Calculate day later time using
<code>date_default_timezone_set('America/Los_Angeles');
$new_date = date('Y-m-d H:i:s', strtotime('+1 day', $current_date);
</code>
similar functions. which will help you to test the recurring system by setting manual time to drupal.
Drupal provide default time zone functions just so you can setting timezone and calculate the time in your hook_cron(). while trigger will get fired Cron processing will work based on your condition.
Hope it will help.


RPi can't boot up from battery, needs to be connected to USB-c then while the battery is connected disconnect power supply USB-c

Question: I have noticed that my Pi will not boot from a battery (supplying 5.26v Raspberry Pi 4 Model B) unless I first start it up from the USB-c power supply and then connect the battery power supply. My multimeter tells me I am giving it 5.26 volts and it draws 500 milliamps as per specification. Very confused, thanks.
Comment: NOTE you stated you are using 2400mAH cells (detail which belongs in the Question) which are only suitable for 250mA load.
Answer: The Pi4 needs more than 500mA to boot.  It probably needs at least an amp.  Once booted it can presumably idle at 500mA.
Comment: How do I let it draw more amps? My battery supply has virtually no IR. It's 6 NiMH 1.2v 2400 mAH batteries in series with 10 awg connectors with a step down buck converter to 5.26
Comment: It would help a lot if you would give us the full specifications for the converter it might help. If the converter only handles 0.5 amps you might need a different converter.
Answer:
it draws 500 milliamps as per specification

If you mean the Pi 4, you are referring to a minimum that it draws while idle.  Electronic gadgets, especially computers, do not draw a steady fixed amount of current like a light bulb.   Their draw depends on their activity.  If your battery is failing at boot, it will fail at other times when the system is sufficiently stressed.

How do I let it draw more amps?

You attach a sufficient power supply.  There's no special setting whereby you can tell to not draw the power it needs, and hence, change that to "let it draw more".
If the Pi does boot successfully using a normal wall supply but does not with a battery, it is probably not the Pi that is that is the problem, it's the battery.
Answer: It's the battery. Unless you've got a massive* battery power source, you are asking (actually begging) for trouble with your RPi. Your comment to @joan's answer suggests that you don't appreciate the fact that a battery's instantaneous capacity to supply current has very little to do with it's energy storage rating. Power is an instantaneous measure; energy is power over a period of time; 2.4 A-hr is a cumulative measure of energy storage - not instantaneous power delivery.
From your question, it seems you've already proven this to yourself, but you haven't acknowledged it yet: <code>"I first start it up from the usb c power supply and then connect the battery power supply."</code> Your multimeter measurements contribute to your confusion because a multimeter is incapable of capturing the instantaneous - it is an averaging instrument. You'll need an oscilloscope to capture transients.


What is the optimal role for a mystic theurge?

Question: I realize that a mystic theurge is basically 2 casters 3lvls lower than my character in one body. a mix or arcane and divine, but I think the possibilities are still intruiging. I am currently wondering what role a mystic theurge would be best at filling. In each role the theurge would have weaker spells, but notably more spells. Which role can take the best advantage of this? A buffer, debuffer, blaster, or some other role I'm not thinking of. (I would really rather not be a heal bot)
Comment: This seems quite incredibly broad. A question like this might be answerable for, say, a Fighter, where there are only a few possibilities, but for a Mystic Theurge?
Comment: A Mystic Theurge is versatile; In fact, that's the whole point of the prestige class. There are *by definition* so many ways in which one could play a Mystic Theurge that it's impossible to point to a single one and say "*That* is the optimum."
Answer: Support spellcaster – buffs, debuffs, battlefield control. Which is mostly what a wizard already is.
The mystic theurge has poor BAB, as does wizard, and having arcane spellcasting makes the use of armor difficult despite your proficiency. As such, self-buffing and going into melee, as a cleric might, is pretty much out. That's a shame, because most of the particularly-good spells that the cleric gets and the wizard doesn't, fall into that category.
So that means you fall into a support role, which the cleric is of course perfectly good at, and the wizard is absolutely superb at. The cleric spellcasting adds a few buffs, but nothing amazing, and healing, which mostly sucks until you get heal itself, but that spell itself is quite good. But you get it much later than a cleric would, and of course your wizardly spellcasting is similarly behind.
You will have access to stuff like remove disease or restoration, which are definitely nice, but only if your party lacks other ways to access them. They aren't every-day needs, so most of the time it's safe to have relatively-inefficient access to them.
This is the real problem with mystic theurge: you lose a massive amount of power, because of the delayed spellcasting, but in theory that's part of the deal of a prestige class, there's a trade-off. Leaving aside the issue that three spellcasting levels is an absurd amount of power that is almost impossible to find an equitable trade for, the things that mystic theurge offers are just... more of the same, or more of the things you would be able to do if you'd been single-classed. You don't really get much that a single-classed wizard wouldn't (more-or-less) have anyway (aside from heal), while compared to a cleric, you give up any real opportunity to use your unique effects (aside from heal) and get a shoddy version of the wizard's forté in return.
So it's never a good trade, relatively speaking. The heal spell just isn't worth it, and it really is just about the only thing that

you wouldn't have if you weren't a mystic theurge,
is actually really good, and
you can still use while also being a wizard.

But with that said, a mystic theurge is still a phenomenally powerful character. Choosing to sacrifice power is, in this case, a quite-valid option: clerics and wizards have power to spare. I wouldn't do it in a game with other high-power classes, but in a low-power game, especially one in which there are no other spellcasters, it could be quite safely powerful enough to have fun, and could even be convenient (get to play with wizard spells, but also have the party's occasional restoration available). This convenience is not, optimally speaking, worth the cost, but if you enjoy the concept, the party could use it, and you are playing in a low-power game, it can probably work.
Answer: Optimal Way for a Mystic Theurge is to utilize metamagic feats in conjunction with his class features:

Combined Spells (Su): A mystic theurge can prepare and cast spells from one of his spellcasting classes using the available
  slots from any of his other spellcasting classes.

Example of Application: Lower Level debuffs from arcane spells can be meta-magicked using higher level divine spells slots. For example, Casting a Quickened Ray of Enfeeblement would  count as a 6th level Cleric spell, and would allow you to use another debuff in the same round, such as Touch of Idiocy. Going up against another spellcaster could render his strength way below 10, and possibly encumbering him. While the penalty to his mental scores could seriously cause him to have a bad day.

Spell Synthesis (Su): At 10th level, a mystic theurge can cast two spells, one from each of his spellcasting
  classes, using one action.

Example of Application: If you chose Druid and Wizard, you could cast Sirocco twice in the same round, at the same time as one action, and could still utilize a swift action, and a move action. Doing this spell twice would make the opponents exhausted which is a tremendous advantage to your party, and deal a decent amount of damage, while possibly knocking them all prone.

Since you won't necessarily have 'show-stoppers' as far as spells, you could very well have many 'crowd-pleasers.'


What are disadvantages if increasing the gain Kd for a PD(Proportional Plus Derivative ) controller

Question: What are disadvantages if I increase the gain Kd  for a PD(Proportional Plus Derivative) controller, someone told me larger gain for derivative error for will reduce the stability margin, while the text books said increase the Kd could increase the damping ratio and high damping ratio means more stability margin.
Comment: at least for second order system, increasing kd does increase the damping. There is app  at [SimulationOfFeedbackControlSystemWithControllerAndSecondOrde](https://demonstrations.wolfram.com/SimulationOfFeedbackControlSystemWithControllerAndSecondOrde/) which you can use to try and see.
Comment: How did you conclude that high damping ratio means high stability margin? What is the system being controlled? Take an example (a fourth order system would be good) and increase KD; you will notice that the stability margins will reduce with increase in KD (after some point)
Comment: @Nasser - cool app! But wouldn't Kd would improve phase margin at first, then after some point, push the crossover frequency high enough that additional real-world poles would become significant, thus degrading it again?
Answer: Depending on the plant, a reduction in phase margin could happen. Here is a theoretical example. Consider a plant with a double integrator and an additional pole:
$$\frac{K_1}{s^2(1+s/\omega_P)}$$
Now let's have a PD controller, which could be written either
$[K_P(1+{K_D}s)]$  , or as $[K_P + {K_D}s]$ . For convenience, both of these could be re-written in the form
$$K_0(1+s/\omega_Z)$$
The loop's stability can then be analyzed by looking at the product of the gains going around the loop -- i.e. controller and plant. We have two poles at the origin, a zero at $\omega_Z$ and a pole at $\omega_P$.
An hand-drawn Bode plot is below, followed by an Octave plot of essentially the same thing. Each graph shows two different values of $\omega_Z$, corresponding to two different values of $K_D$.

For completeness, here are the corresponding closed loop bode plots and closed loop step responses

Hopefully it's possible to see from first bode plots (the ones looking at around-the-loop), that reducing $\omega_Z$ (i.e. increased $K_D$), by 10x in this example, moves the first breakpoint left by 10x. This then lifts the section of the line with the -20dB/decade slope up by 20dB, causing it to intersect the horizontal axis about 10x further to the right, meaning the loop has about a 10x higher bandwidth.
The movement of the gain crossover frequency also results in a different phase margin. In the example shown, it reduces phase margin  from something like 80 degrees for line (1), to 50 degrees for line (2).
However, if the overall gain were smaller, the opposite could also be the case -- if the gain crossover started out to the left of the "peak" in the phase plot, then the phase margin would increase at first, but then decrease again after the gaincrossover frequency passes the peak in the phase plot.


Laravel FileManager on 000Webhost - i can't upload files/images

Question: This is my first time when i post ask here, but it's not the first time when i see any solutions.
I have a real problem with my laravel project and my website where host on 000Webhost.
I explain the problem :
I have create laravel project like another developper can create it, i created controllers/migrations/models/views/routes, also i uses Framework CSS and Templates...
I would like to create some News like lot of website, with title, description, and article and some images. To do this, i have search any solution laravel can have. At the begining i choose elFinder WebManager, it's a good webmanager but i've meet lot problem with it, so i change to Laravel FileManager last week, and i prefer it for interface and configuration.
Alright my project works locally with wamp server 64, no problem with Laravel or Laravel File Manager, i can upload, create folder etc... So i put my project on my 000webhost site, i change configuration for it, and i see what's works and what's doesn't works.
All project works good, the routes are the same, views are goods and authentication too. But not the upload of Laravel FileManager. I can create folder, i can choose images from my project uploaded initilialy but i can't upload images from my pc to my website. When i try to upload, error message spawn and said "File failed to upload. Error code: 6".
I'm very frustred, because it's the only problem do i have on this project with at this moment, no good solutions.
I search what is problem on forums or on the net, i see guys who are problem with permissions on 000Webhost, so i try to change my permissions of my folders where laravel filemanager are installed. All my folders in my website are on 777 permissions and nothing works. I need to find a solution it's important for me but i see nobody's search an solution for this problem or i have skip it by inadvertence (so i'm sorry for this subject).
I search any others solutions or others anwsers to enable achievement my project.
If you want any informations, i can send it here.
I'm present for any questions if you needed..
Thank's you for reading and if you have answered it in advance.
Cordially,
Answer: Error code 6 indicates that a tmp directory has not been specified. You'll need to provide a tmp directory in your php.ini using the upload_tmp_dir directive.


Can't load CartoDB Map Academy files

Question: I've been trying to do the very intro CartoDB Map Academy course, but when I try to load the example files – e.g., http://acdmy.org/d/counties.zip – I get a screen that says "Downloading file" forever and eventually it just fails and I later get an email telling me that it couldn't import my table, without any more details. Any idea what's going on here?
Comment: Are you importing the zip file without unzipping it?
Answer: I've just tried just copying and pasting the http://acdmy.org/d/counties.zip URL into CartoDB and it imported fine the us_counties table. I also downloaded locally the zip file and imported it without problems (no need to unzip, CartoDB unzips automatically, also being a Shapefile it is a requirement to use a zipped file).
Maybe was a temporal file download issue... If still happens to you please provide as many details as possible to try to pinpoint or reproduce it.

Can't load CartoDB Map Academy files


Why is $U_n^+(A)/U_n^+(A)_0\simeq U_n(A^+)/U_n(A^+)_0$ for a unital C*-algebra $A$?

Question: Was reading Wegge-Olsen's K-theory and C*-algebras and in chapter 4 they state that $U_n^+(A)/U_n^+(A)_0\simeq U_n(A^+)/U_n(A^+)_0$, to show that he says that $(a_{ij})+1_n$ is invertible (unitary) if and only if $(a_{ij})$ is invertible (unitary). Given the product in $A^+$ that doesn't even follow for $n=1$, is he already using the isomorphism there is between $A^+$ and $A\oplus \mathbb{C}$? If that's the case, how would the argument above translate to the usual product in $A^+$?
Answer: If $A$ is unital, the isomorphic between $A^+$ and $A\oplus \mathbb{C}$ is
$$(a,c)\mapsto(a{\color{red}{+c1_A}})\oplus c.$$
Where the element in $A^+$ is of form $(a,c)(a\in A,c\in\mathbb{C})$ and the product is $(a,c)(a',c')=(aa'+ac'+ca',cc')$; the element in $A\oplus \mathbb{C}$ is of form $a\oplus c(a\in A,c\in\mathbb{C})$ and the product is $(a\oplus c)(a'\oplus c')=aa'\oplus cc'$.


How is thesis evaluated in pure mathematics for PhD?

Question: I am a Ph.D. student in pure mathematics with a few published works in my field. I would like to know how Ph.D. students are evaluated by the examiners before the defense. What are essential points to be careful about when writing a thesis? I would also like to know how much time is usually taken from submission to defense.
Comment: Have you asked your adviser these questions?
Comment: What country are you studying in?
Comment: It will range from "read all proofs closely" to "do not even open."
Comment: @AnonymousM Yes I have asked him but still, I would like to know from other people's perspectives.
Comment: @Buffy I am studying in India
Comment: Also, possibly significantly, by "with few published works", do you mean "_A_ few published works..."? In contemporary U.S. English that would mean that you have 3 or 5 papers, or more. To say you have "few published papers" (without the article "a") would mean that you have perhaps just 2, or 1, or none. Yes, this is a volatile aspect of contemporary U.S. English... but/and can you clarify?
Comment: @paulgarrett I did not know the difference. Thank you. I have 2 accepted and 3 published research papers.
Answer: I don't know if this is applicable to India, but, since you want a general answer, I can say a few things.
Generally, at least in the US, the expectation is that the thesis is publishable work. In other words it makes a significant and novel contribution to mathematical knowledge. You don't have to solve a famous unsolved problem, but you need to make a definite contribution.
Your thesis needs to show that you have some deep insight into a narrow part of mathematics and that you have the capability to do more, perhaps in collaboration with others.
It should also demonstrate that you can write and express things clearly and correctly.
However, your thesis can be your first significant work, not the most important work of your career, assuming you stay in academia. So, the Riemann Hypothesis is out.

I have no idea about timing. Your committee will need time to do a review, hopefully more complete than a cursory reading. Most of my committee (long long ago) couldn't understand everything in my dissertation, as they were from different specialties, but they could sort of grasp its importance. The latter was partly due to the assurance given by my advisor to them, as he was well respected.
Comment: "However, your thesis should be your first work" is simply wrong (but true for most students).
Comment: How about "can be your first significant work", then, @MoisheKohan. That was my intent.
Comment: Much better.....
Comment: Examples I had in mind were Milnor's paper "On the total curvature of knots" (not a part of his thesis, 121 citations on MathSciNet), or John Pardon's undergraduate work, or Drinfeld's HS work...
Comment: @MoisheKohan, my "first work" was more than 60 years ago in secondary school. It was published (part of a book) only recently. It won an award back then, but wouldn't have been publishable as a stand-alone (then or now). But it was "insight revealing" and so has pedagogical value for those learning math.
Comment: ... yes, let's not be tooooo pedantic in use-of-words here... :)


jQuery flot with ASP.NET MVC and DateTime properties

Question: I have an object with an integer property, and a DateTime property, I would like to plot a collection of these objects using jQuery flot, however I've tried googling around looking for examples but have had no look, so I was wondering if anyone could point me in the right direction for converting the collection of objects into an array that jQuery flot will understand, I also understand you need to convert the DateTime into Javascript Date. Any help in heading in the right direction will be greatly appreciated.
Comment: So your X-axis is dates and your values are integers?
Comment: Yep, dates (DD/MM/YYYY) along the X-Axis, and the integers as the Y-Axis values.
Comment: should be pretty straightforward. Are you passing values from server-side code? How are you passing them, using JSON?
Comment: I'm not passing anything yet, although it will be returning a JsonResult, the converting DateTime to javascript dates is what confused me.
Comment: Did you look at this webpage: http://weblogs.asp.net/rachit/archive/2010/01/26/jquery-flot-charts-with-time-series.aspx
Answer: I create my as an extension method to convert my datatime to a javascript datetime. It looks like:
private static long ToJavascriptTimestamp( this DateTime input )
{
  TimeSpan span = new TimeSpan( new DateTime( 1970, 1, 1, 0, 0, 0 ).Ticks );
  DateTime time = input.Subtract( span );
  return ( long )( time.Ticks / 10000 );
}

Then I just passed it back as a Json result.
If you want to make it a column chart then the bar width is also based on ticks so if you want it to be an hour the width would be: 60 * 60 * 1000 (ticks * seconds * min)
Your object could be something like:
public class GraphData
{
  public int Value {get; set;}
  public long Date {get; set;}
}

Then just create a list of GraphData and in your controller use something like:
return Json(myGraphDataList, "application/json", Encoding.Default);

Then in your javascript on you might have some $.Ajax call to get the data and on the success response that where you set it like:
$.ajax({
  url: "/someUrl",
  type: 'POST',
  dataType: 'json',
  success: function (result) {

    var graphData = [{
        data: result.Data,
        lines: {
            show: true
        },
        points: {
            radius: 3
        }
    }];

    var graphOptions = {
        grid: {
            hoverable: true,
            borderWidth: 1
        },
        yaxis: {
            axisLabel: "Title",
            axisLabelUseCanvas: true,
            axisLabelFontSizePixels: 12,
            min: 0
        },
        xaxis: {
            axisLabel: "Time",
            axisLabelUseCanvas: true,
            axisLabelFontSizePixels: 12,
            mode: "time",
            timeformat: "%H:%M",
            tickSize: 1000 * 60 * 60
        }
    };

     $.plot($("#tag"), data, options);
  }
});

Comment: Thanks! Now I just need to work out how to construct the object to return with Json() in my controller.
Comment: Thanks for the answer, the X-axis should be by day (i.e. "19/02/2011 20/02/2011") was wondering how you would change the timeformat and tick size for that?
Comment: Thanks Simon, do you know why this hover circle thing seems to be off from the actual points in this image - http://s2.kimag.es/share/41110232.png


Personality traits associated with finishing other people's sentences?

Question: I read in a North American undergrad psychology textbook, that people who tend to finish another's sentences tend to be emotionally intense. I think "emotionally intense" is the wording that they used. The impression that was given is that the type of person tends to swing moods more often or to a larger degree; they're more emotional.
Can someone cite the study? And does anyone know any other traits of people who like to finish another's thoughts?
Comment: I doubt that any one could finish another's thoughts. Unless you hold that thoughts are synonymous with sentences, which I don't as there are no thoughts, only sentences.
Comment: @Dan D., I understand your argument and I considered this when I used the term "thoughts" to replace "sentences". I erred towards using the more general term "thought" in case there were cases that I did not consider, like nonverbal communication. If you have a better term to cover such things, please suggest it. Maybe messages? Expressions?
Comment: I have a friend that does this to me, he has just done it twice - hence me being here!!  he tries to finish with the words he thinks I'm going to say... I sit and watch his mouth trying to form the words he thinks are going to come out of my mouth... It is driving me nuts as I've only noticed this over the last few months and I've known him 10 years plus!!
Comment: I also experience this at work with a direct report. This is a newer associate who is in the learning phase of his position. His progress is not exactly where we would like it to be, though he's not failing as a whole. He has a tendency to finish or speak in sync with the person speaking to him. I believe it is in an attempt to convey that he "gets it" -- a way to reassure his trainer that he's understanding, yet we're finding this is not necessarily the case when it comes time to apply that knowledge. So in summary, I suppose I'm saying it can also be tied to insecurity?
Answer: Several factors may influence a person to finish off other peopla's sentences.
- The person may be stressed (and some people stress more often than others, thus stress may cause some people to do this more often)
- ADHD is said to cause an impatience, making the clients finish off other people's sentences:
http://www.healthline.com/health/adult-adhd
- A person may have a lot of energy, spending a bit of this energy on finishing off other's sentences.
- The speaker and the listener might ble close to eachother, and know eachother very well, maybe the listener was "just thinking of just the same thing"..
Whether or not I can find sources on "emotionally intense" people doing this, depends on how one defines being "emotionally intense". You could probably call any of the above examples emotionally intense people...


Path taken by electron returning to ground state

Question: Sometimes electrons are excited and return to their ground state in one step, while sometimes they take multiple jumps. What determines the path they take?
Comment: @CuriousOne Yet if I hold a photon detector next to an excited atom, some times I get three photons of one energy unit each, and some times I get one photon of one energy unit and one photon of two energy units.
Comment: @CuriousOne well, in this case, the fact that the question suggests that the word "path" should be interpreted as "set of states occupied by an electron as it goes from an excited state to the ground state". Note the use of the word "step" and expression "multiple jumps" in the question text. Perhaps you only read the title?
Comment: may be it is incoming new photon which collide with the excited atom that determines
or also the the excitation star of atom.
Comment: That is just a matter of chance. No particular path is preferred over the other, but someone more experienced than me will be able to elaborate.
Comment: Electrons don't take any paths, at all. Atoms change state trough the emission (better creation in a field theory terminology) of one or multiple photons. Which process happens depends on the symmetries of the initial and final state (and intermediate states if they exist) and the form of the interaction Hamiltonian.
Comment: @DanielSank: What does a multi-photon process have to do with paths????
Comment: @DanielSank: So it's an English question, then? You are right, I am not an English major. :-)
Comment: @CuriousOne I estimate roughly 75% of confusion in life comes from imperfect communication. Physics is no exception. We shouldn't laugh it off. Getting the terms right matters a *lot*.
Comment: @DanielSank: You don't have to tell me... just look at some of the other questions like the one about the "purity of energy". Physics starts with such simple definitions and almost nobody takes the time to read them... sigh.
Answer: 'Path' is perhaps a misleading word to use here. Path typically means a physical path through space - a trajectory. You can use path in the context of a path through a sequence of energy states, talking about which energy states an electron is in in which order, but you have to establish the context to use the word like that before hand.
Back to the actual question: what determines how many photons are emitted? It is random.
Consider a simple system where an electron can have three energy states, the lowest being $E_{0}$, then $E_{1}$ and $E_{2}$. An electron in state $E_{2}$ can either transition directly to $E_{0}$ emitting a photon where $h\nu=E_{2}-E_{0}$, or it can transition to $E_{1}$ and then $E_{0}$, emitting two photons (of energy $E_{2}-E_{1}$ and $E_{1}-E_{0}$).
It is possible to calculate transition probabilities per unit time for each possible transition. So in any given time period there will be a certain probabilty $p_{20}$ that the electron drops to state $E_{0}$ and a probability $p_{21}$ that the electron drops to state $E_{1}$. And of course, a probability that it remains in its current state.
Once those probabilities have been calculated, you can figure out how often an electron will return to the ground state via emitting a single photon, vs two photons (in our simple system). But there is nothing deterministic to say which path will be taken (see, now we can use path without anyone arguing about what it means... :) ). It is entirely random. All we can do is figure out the probabilties involved.
Answer: It might not take a particular path at all.
Some transitions might be strongly forbidden based on the difference of angular momentum of the states. But you can also have double photon transitions directly between two states, or have multiple transitions that have the final state of one transition be the starting state of the other.
And if you take that last approach, you could have a series of transitions between A and D through state B and another series of transitions between A and D through C and in addition to doing one series or the other series there could be a superposition of both.
In fact, a similar thing happens in photosynthesis where different ways to collect energy from sunlight can constructively interfere and be more efficient together than the sum of the two approaches alone would be.
Answer: In general, electronic relaxation of an excited atom is nothing but a quantum mechanical transition from an initial to a final state. Therefore probabilities for different transitions (what you called paths) is determined by the rules of quantum mechanics.
The particular "law" that applies here is called Fermi's Golden Rule. In the related Hyperphysics page is says

In general conceptual terms, a transition rate depends upon the strength of the coupling between the initial and final state of a system and upon the number of ways the transition can happen (i.e., the density of the final states). In many physical situations the transition probability is of the form

Answer: OK my previous answer was not cited correctly. I am trying to give you a good guess on what is going on when an electron returns to ground state. This is cited from another site, as I said I would just like to help you with clearing up this process with electron excitation.
http://chem.libretexts.org/Core/Physical_and_Theoretical_Chemistry/Spectroscopy/Electronic_Spectroscopy/Electronic_Spectroscopy%3A_Theory
You are asking specifically what determines whether they go 'straight' to ground state or step-by-step.

"A molecule that is excited can return to the ground state by several combinations of mechanical steps (see the picture). The deactivation process of fluorescence and phosphorescence involve an emission of a photon radiation. The wiggly arrows are deactivation processes without the use of radiation. The favored deactivation process is the route that is most rapid and spends less time in the excited state.If the rate constant for fluorescence is more favorable in the radiationless path, the fluorescence will be less intense or absent."

Here are the different types of deactivation (how the electron goes back to ground state on the picture):

This is here a citation from the original page just for your info:

"Vibrational Relaxation: A molecule maybe to promoted to several vibrational levels during the electronic excitation process.Collision of molecules with the excited species and solvent leads to rapid energy transfer and a slight increase in temperature of the solvent.
  Internal Conversion: Internal conversion is an intermolecular process of molecule that passes to a lower electronic state without the emission of radiation.
  External Conversion: Deactivation of the excited electronic state may also involve the interaction and energy transfer between the excited state and the solvent or solute in a process called external conversion.
  Intersystem Crossing: Intersystem crossing is a process where there is a crossover between electronic states of different multiplicity the singlet state to a triplet state (S1 to T1).
  Phosphorescence: Deactivation of the electronic excited state is also involved in phosphorescence. After the molecule transitions through intersystem crossing to the triplet state, further deactivation occurs through internal or external fluorescence or phosphorescence. A triplet-to-singlet transition is more probable than a singlet-to-singlet internal crossing. In phosphorescence, the excited state lifetime is inversely proportional to the probability that the molecule will transition back to the ground state. Since the lifetime of the molecule in the triplet state is large (10-4 to 10 second or more), transition is less probable which suggest that it will persist for some time even after irradiation has stopped. Since the external and internal conversion compete so effectively with phosphorescence, the molecule has to be observed at lower temperature in highly viscous media to protect the triplet state."
Comment: I talked to ACuriousMind, he told me it is technically OK. I really want to just help these people with the information, since I see they did not get a full answer.


How to use Tall Goat and other rewards?

Question: When I get the trophy rewards, like tall goat, how do I actually activate it and become tall? Thanks.
Comment: You need to go back to the main menu and add it as a 'modifier' or something, I forget the exact labels.  I'll let somebody else answer in more detail.
Comment: Found it! I had to start a 'custom game', then select modifiers from there. Thanks much!
Answer: It depends what platform you're on. In mobile, you click the goat symbol in-game on the top left. From there, scroll, and you will see your goats. For others... well, I don't know. But here's a funny use for Tall Goat:
Lick people and toss them in the river. It's very easy because Tall Goat is a giraffe and the body is so high off the ground, giving you a lot of control.
Answer: You need to go back to the main menu and start a Custom Game.
From there you can add Modifiers, which change stuff in the game.  As you unlock new goats, you can add them as Modifiers to change your goat appearance.  This is how you activate most of the unlockable stuff.
To change your Modifiers, you will have to go back to the menu and start a new Custom Game.

How to use Tall Goat and other rewards?


Will Apple Music work with iPod Classic and iPod Nano?

Question: Will I be able to sync offline Apple Music to non-internet Apple devices e.g. iPod Nano and iPod Classic?
Answer: Apple Music is not available on iPod nano and iPod shuffle.
See footnote 3: http://www.apple.com/uk/music/
Comment: I saw this same footnote, but I still wonder if offline tracks could be synced.
Comment: Yeah I am going to check
Answer: Offline tracks obtained through apple music do not sync across to ipod.
Its a shame really, they could easily put a timer on the songs, so if the ipod is not plugged into registered device every so often, the songs will become locked.
Comment: Missing features like this tend to come down to the actual definition of "easily". :)
Answer: I recently bought an iPod Nano, and I am very happy with it! The only downside is that Apple Music is not available for it. Which frankly is a new low for Apple, but I'm pretty sure they're gonna fix it up later. Although it might be a huge way for people to abuse the system. They could download a gazillion tracks into the iPod and never connect it to a computer again. For now Apple Music is not available in devices such as iPod Nano, iPod Classic or iPod Shuffle. Apple will find a way to find a way, but for now all we can do is... wait.
Answer: No. Unlike iPhone,iPad or iPod touch 5/6, iPod nano and iPod shuffle don't have Wi-Fi compatibility which means they won't be able to support Apple Music. But there are speculation saying that you can sync Apple Music tracks to iPod nono with iTunes and Apple Music Converter.
Answer: Get AirPlay Recorder and download copies that can be transferred.
;)


Instead of warping spacetime, can gravity be represented by locally varying time rates?

Question: Instead of thinking of gravity as mass warping spacetime, could it be thought of as mass warping only time, whereby time would advance at faster rates at locations where more mass is present?
Comment: Doesn't the Lorentz transformation 'mix' the space and time coordinates?
Answer: No. This kind of proposal can "control" at most one independent component of the Riemann curvature tensor (through a rate parameter), and we routinely meet metrics in gravitational theory that have pure spatial curvature as well as time components to the curvature tensor.
Witness, as an example, the FLRW metric wherefor:
$$\begin{array}{lcl}R_{tt}& =& - 3 \frac{\ddot{a}}{a}\\
R_{rr} &=&\frac{c^{-2}(a(t)\ddot{a}(t) + 2\dot{a}^2(t)) + 2k}{1 - kr^2}\\
R_{\theta\theta} &=& r^2(c^{-2}(a(t)\ddot{a}(t) + 2\dot{a}^2(t)) + 2k)\\
R_{\phi\phi} &=&r^2(c^{-2}(a(t)\ddot{a}(t) + 2\dot{a}^2(t)) + 2k)\sin^2(\theta)\end{array}$$
where one has two independent parameters, the scale factor $a(t)$ (which could be construed as the "control knob" in the OP's proposal) and the spatial curvature. It's true that one can normalize the equations, but you're still left with three fundamentally distinct possibilities $k=\pm1$ and $k=0$. Furthermore, one can of course find much more complicated, inhomogeneous metrics as valid solutions to the Einstein field equations.
Comment: Hi Rod, this answers my questions. Thanks so much!!!
Answer: It is difficult to answer your question for all possible configurations of gravity, but within Schwarzschild metric it is easy to show that gravity may not only be represented as curved spacetime but - exactly as you suppose - also as gravitational time dilation in flat space.
The Schwarzschild metric is the most basic description of the spacetime curvature by gravity, it is
$$ \mathrm ds^2 = -\left(1 - \frac{2GM}{c^2 r}\right) c^2~\mathrm dt^2 + \frac{1}{1 - \frac{2GM}{c^2 r} }~\mathrm dr^2 + r^2 \left(\mathrm d\Theta^2 + \sin^2 \Theta ~\mathrm d\Phi^2\right)$$
In contrast, the corresponding Minkowski metric (with flat spacetime) is
$$ \mathrm ds^2 = -~ c^2~\mathrm dt^2 + \mathrm dr^2 + r^2 \left(\mathrm d\Theta^2 + \sin^2 \Theta~\mathrm d\Phi^2\right)$$
where $\mathrm dt$ is uncurved time and $\mathrm dr$ is uncurved radial displacement.
Comparing both, you find that in the Schwarzschild metric, time $\mathrm dt$ is multiplied by the constant
$$ \sqrt{1 - \frac{2GM}{c^2 r}}$$
and space $\mathrm dr$ is divided by the same constant. It is exactly this factor which represents the spacetime curvature. The constant is gravitational time dilation.
If we set the constant = $C$, we can write Schwarzschild metric shorter in the following way:
$$ \mathrm ds^2 = -~c^2 (C~\mathrm dt)^2 + {\left(\frac {\mathrm dr}{C}\right)}^2 + r^2 \left(\mathrm d\Theta^2 + \sin^2 \Theta~\mathrm d\Phi^2\right)$$
Comparing this short form with the equation above of Minkowski metric, the Schwarzschild metric differs from uncurved Minkowski metric only by one coefficient $C$ which is identic with gravitational time dilation. That means that the curved spacetime of Schwarzschild metric may also be described in terms of gravitational time dilation - in absolute, flat space!
Curved spacetime and gravitational time dilation in flat space are two equivalent models. For the latter, gravitation is expressed by the tendency of particles to maximize their own gravitational time dilation.
Edit 1:
The Schwarzschild metric even provides a simpler answer to your question: in the Schwarzschild equation, the displacement coordinates dt and dr (as well as dΘ and dΦ) are not curved! As you see, the metric ds is the result of a multiplication of dt by C and the division of dr by C, providing a warped metric. However, the terms on the right side dt and dr are not distorted and not warped, they are flat polar coordinates, and the polar coordinate system may be transcribed into the corresponding Cartesian coordinate system of flat space.
Edit 2:
Your question may be of high importance. If what I showed for the Schwarzschild metric would be true in general (e.g. Kerr metric etc.) this would mean that gravity may be described exclusively in terms of time modulation in flat space. This could be crucial with regard to the fact that the time parameter in quantum mechanics is no operator, it is classical. In my personal opinion, here could exist a path permitting to conciliate gravity and quantum mechanics.
Comment: Hi Moonraker, thanks for presenting this thorough explanation!! I wasn't aware of the Schwarzschild metric, so it's good to know that it can be described in terms of gravitational time dilation in flat space. Cheers!
Comment: Not only is your $C$ not a constant, as it depends on $r$, an easily rectified mistake, but your identification of $C$ with time dilation is ill motivated. If it was a constant then it would be equivalent to a coordinate change, and even though it is not, in what way can you identify it with gravitational time dilation? The fact that it appears before $dt^2$ just means that the time coordinate is not normalized.
Comment: We may theoretically be able to find $C$ through investigating time dilation, but only by using our knowledge of the Schwarzschild solution can we reconstruct the entire line element. In this way it becomes circular: using our knowledge of the curvature to reconstruct it.
Comment: @ Erik Jörgenfelt: Thank you for the feedback, you are right, the word "constant" may hurt. Naturally, it is not observer-invariant but it corresponds to the gravitational time dilation (τ/t) from the point of view of a far-away observer.
Comment: See my edit of the article and my [question](https://physics.stackexchange.com/questions/367871/are-the-space-and-time-axes-of-schwarzschild-metric-uncurved/367875#367875) (thank you for the hint you gave me). No circularity, the logic goes from the right to the left side: It is the metric ds (not the coordinates r and t) which is curved. On the right side you find the uncurved coordinates (!) t and r. On the left the curved metric, which corresponds to the Minkowski metric, however t and r are distorted by gravitational time dilation, and as a result you get the curved metric ds.
Comment: @Moonraker coordinates are just coordinates: they are neither curved nor un-curved. Indeed it is the manifold, or some submanifold thereof which exhibits curvature. It is an intrinsic property linked to the connection on the tangent bundle. Because general relativity assumes the Levi-Civita connection, this curvature can be found from the line element, but it is non-trivial to do so without the proper tools. This will be my last comment since what you are suggesting is meaningless.
Answer: Before we answer this question, I think it is proper to discuss what is asked. As Rod explains, there are certainly solutions to the Einstein Field equations that cannot be explained by a single parameter. However, the question as framed seems to suppose there is some universal way of defining how quickly time passes. What is meant by time dilation is that the proper time along two different timelike curves connecting two events differ. This can happen in Minkowski spacetime, where the universal reference frame makes things easier for us, and it can happen in curved spacetimes. In this view, the quesion should perhaps be reframed as:

Can the effects of spacetime curvature be reconstructed from knowledge of time dilation along all different timelike paths? Possibly by introducing new dynamic equations which link time dilation to other observable effects.

If this was the case, one could say that spacetime curvature could be entirely explained only by considering time dilation. Now, proper time along a curve, $\gamma$, is found by integrating the metric along the curve
$$\Delta\tau = \int_\gamma d\tau = \int_\gamma\sqrt{g_{ab}dx^adx^b},$$
where we supposed units such that $c = 1$ and timelike signature, $(+---)$. This would in principle allow us to reconstruct the primitive of the metric components along our timelike curves, and the curvature is given by a rather lengthy expression involving second derivatives of the metric.
However, promising as this may look, the fact that we can only consider timelike curves, means that we have no way of investigating the dependency of metric components along spacelike or null curves (through time dilation). In slightly more mathematical language: we can only know the derivatives of the metric components with respect to timelike coordinates, and of those only the "timelike components:" If we choose coordinates $(t,x^1,x^2,x^3)$ such that $x^i$ ($i \in \{1,2,3\}$) are constant along a curve then
$$\Delta\tau = \int_\gamma\sqrt{g_{tt}}dt,$$
and we may in principle reconstruct the primitive of $\sqrt{g_{tt}}$ with respect to $t$ only. And this is certainly not enough to reconstruct the curvature tensor, in any spacetime, even if all possible timelike coordinates are investigated.
Comment: Hi Erik, thanks for rephrasing my question and providing more details on the validity and limits of only considering time dilation!
Comment: @Erik Jörgenfelt: You want to check the question in any possible frame, but this is not required. It would be sufficient if the answer could be "yes" in one single frame (or better: one kind of frame, i.e. the frame of the far-away observer). - The question of Betvin Géant is excellent without need for correction, see edit 2 of my answer.
Comment: @Moonraker The point is that *even* if we somehow attain knowledge of every possible frame, it is not sufficient.  So it is rather the opposite of what you imagine.


How do I stop the second floor of my house from being so hot in the summer and so cold in the winter

Question: I have a window AC upstairs in the summer but it is not enough I can fell the heat coming off of the ceiling in the summer and in the winter it is way to cold that my kids have to sleep downstairs please help
Answer: Sounds like your problem is insufficient attic insulation. In the summer, your attic gets hot, and that heat radiates down into the second floor. In the winter, your attic gets cold, and sucks heat out of your house, aided by the stack effect. Improving the insulation on your attic flow will help both of those problems. The typical approach is to blow cellulose into the attic floor. But be careful! If your house is old and there's already any blown insulation, it might be asbestos-laden vermiculite. You might want to consult a pro. Often it's barely more expensive to hire this job out than to do it yourself.
Comment: In my case, most of the cost of having a pro both do this and air-seal my place (which is arguably the single most cost-effective energy conservation you can take) was covered by my utility company. Check what rebates you might be eligible for.
Comment: True, although air sealing comes with more complication since the better you do it, the more you need a mechanical ventilation system to be added, which is another kettle of fish.


Depth Shading / Portal Effect

Question: I'm trying to recreate a "Portal" effect which is similar to a Depth Shader used inside of Unity. I've seen many tutorials for doing something similar on Blender, although it seems most of these tutorials involve cutting out a hole in a plane and just using some camera tricks to achieve this illusion. Are there any other, more flexible solutions out there?
Comment: https://blender.stackexchange.com/a/214311/2214
Comment: What tutorial you used and what kind of more flexibility do you expect? From your image I'm not sure what I'm looking at ... What 0/1 means?
Comment: I just want to achieve this result without using a hole in the wall Approach . I want to achieve it using one object that could for example be moved around, seen from different angles, etc
Comment: I think the effect you're going for is related to _Interior Mapping_ which, although is technically possible in blender, it can be a real pain to pull off.
Answer: By Camera trick you probably mean ...
version Parallax Cube Mapping
it works like a magic for interior faked on plane with cube texture mapping

Easily faked with Mask texture, but illusion becomes broken when observed in animation, because space behind the rift is cubish and doesn't follow rift edges.

Here you can find a node group nicely organised.
version Parallax Occlusion Mapping
In your case you should use a POM (parallax Occlusion Mapping) nodetree using a depth texture to layerevector into depth steps ... simle example of technique ...
Here used only depth pass for the rift ... 32 layers

If I checked right reference ... Unity does the same ... with some specific amount of "layers" you affect just distance between them.
For the sword part technically hiden behind the plane is used Parallax CubeMap technique with shifted left right sides to center and textured by baked material.

64 layers ...

Texture on upper part of sword is not seamless, because  baked in separately (at home machine) ... sorry. And since sword texture in shader is just a plane it has not a thickness.

Anyway as conclusion - it seems to me much easier and precise just grab rift texture and use it as a transparency mask for a wall shader with Texture coordinates set to sword.
version Transparent Mask
First drag&drop rift image into 3D view (as Empty Image), search for Trace GP to generate PG object from texture, W > Convert to Curve (than extrude curve or convert to mesh and extrude in edit mode).

Wall (Plane material)
Than use the same texture as Factor for Mix Shader of Transparent and Diffuse node with Texture Coordinates > Object > Empty ...

Parent all needed objects (rift object, sword, green light) to Empty.

Final result ...

Blend file on Dropbox (skip Sign-in).
Comment: Thanks! Yeah, parallax mapping is definitely the first part of the equation here. But iit's the sword object that I could find no tutorial on. It is placed outside of the plane. I would be interested in seeing your example
Comment: Appreciate you taking the time to put this together. So, do you think it would be possible to combine your approach with interior mapping? I'd like to avoid the extruded geometry and keep the floor plane flat
Comment: I did not succeed ... and even I would it would be too visible that hole doesn't match the edges of the rift. Answer extended parallax version with an example of a way it is used usually (sure smaller distance between layers smoother result).
Comment: after some more searching I think this may be the answer: https://www.youtube.com/watch?v=txUCkthVriw
Comment: Hm ... if that would be solution for you great ... it seams we targeted to different thing :) Please post it as answer to help others :) It is quite interesting topic ... BTW  I got working sword layer for parallax thing and for hole extended to 64 layers could be working with some limits I will update A when I merge those together.
Answer: After researching the topic a bit more, my preferred solution was to use:

a holdout shader which renders everything behind it to be completely transparent

a multi-layer compositing process, where the objects to hide are separated from other objects in the background.

Depth Shading / Portal Effect


How would you call someone who is a party pooper who doesn't want to do anything

Question: For instance, someone goes to a hotel as a gateway and enjoy but they rather go to the store instead of eating a breakfast in the hotel because is too expensive and the other one gets dissapointed or someone is too excited to do something but he says mmm idk maybe we could do someone else less complicated
Answer: That kind of sounds like me from time to time, so "Andrew"?  :D
Seriously though:  "Party pooper" is the slang expression that comes to mind, but here are some related slang expressions:

grinch: Someone who generally dislikes merriment and fun, especially Christmas-related activities (from the famous Dr. Seuss story "How the Grinch Stole Christmas")
killjoy: literally "someone who kills the joy", (slightly dated)
sourpuss: "puss" is slang for "face" so someone whose face is wrinkled up like they're eating something sour, and has a similar expression when asked to do something they don't want to do. (slightly dated)
spoilsport: someone who "spoils" the "sport" (fun) in an activity (slightly dated).
stick-in-the-mud: someone who doesn't like to try new things, as if they are "stuck" in one place (slightly dated)
wet blanket: You can throw a wet blanket onto a fire to put it out, in the same way this person douses all the excitement and fun of an activity (dated)
buzzkill:  A "buzz" is the "high" you get from some intoxicant, in the same way the feeling from some exciting activity.  This person "kills" the "buzz".

My generation would be likely to use "buzzkill", but I couldn't tell you what the current generation would use.  Maybe just "boring".
Comment: It's surprising how many of those you've labeled as "dated" or "slightly dated".
Comment: @J.R.  It based on how uncomfortable I imagine I'd feel using them, if I was a teenager.  There must be some new slang for these that the kids are using.
Answer: "girlfriend"?
Seriously though, the example about breakfast is more like skinflint or penny-pinching.

How would you call someone who is a party pooper who doesn’t want to do anything


Why do apps like WhatsApp, Facebook run background services in android even though their apps on iOS without backgroung services

Question: What is the reason for apps like WhatsApp running background services in andrioid even though in iOS they work smoothly without any background service
Answer: Because they can.
In Android you can create background services and do a lot with them, whereas in iOS Apple does not allow you to do this. Both use push notifications to get your new messages when the app is closed, so the main functionality of the app works fine regardless, however the apps may be doing more processing or monitoring, or whatever Facebook wants it to do in the background while you're not using it.


How to change Data Source in Power Query for Pivot Data? (Browse Button missing)

Question: Ok, short explanation what I did: I created a Report in a Workbook ("Main File") linked with Power Query to another Workbook ("Source") which contains my data source. I have multiple Queries, 8 of them are just links and one loads the data to the Pivot Table which is the base of my report.
The Source will be updated once a month (not prepared by me) and so I need to change the data source of my Main File. Quite easy so far, I use the way described in the two picture below and it worked for the last three months perfectly fine from my PC. ([Ribbon]Data -> [Dropdown]New Query -> Data Source Settings... -> Change Source... -> Browse... --> Update the Query)
Step 1
Step 2
But now the problem starts. I uploaded the file to the server folder and wanted to show my college how to do it. Everything worked fine but when it came to the point to select the new data source there was no "Browse" Button and when he changed the path to source data by hand it just gave back an error that the path doesn't exist.
Both workbooks lie on the same server, we both have full access rights to the server and we both run Office 365 ProPlus with the newest update (he just has another update channel than me).
I would be happy about any suggestion how to solve that problem!
Answer: Ok, it turned out that I now works manually and the problem in the was just the path itself. There is still no Browse Button, but he will survive that I guess.


Is "to hide gold" used with meaning of "to hide one's talents or money"?

Question: In Brazil, the expression "to hide the gold" (Portuguese: "esconder o ouro") is used to express that someone is hiding his/her own talents or wealth, for modesty or because he/she doesn't want to be bothered because of those talents or wealth. Is the same expression used in English with the same meaning? If not, which's an equivalent expression?
Answer: You could say, they're trying to blend in with the crowd (go unnoticed).
Alternately, the expression keep a low profile might fit the bill.

keep a low profile: to stay out of public notice, avoid attracting attention to oneself. This expression alludes to profile in the sense of "a visible contour," a usage dating from the 1600s. [Late 1900s]
  The American Heritage® Dictionary of Idioms by Christine Ammer
It's therefore interesting to note that those individuals who achieve
  fame and success on a long-term basis are those who have managed to
  live life with a great deal of humility and more importantly, to blend
  in with the crowd. They understand the abovementioned dangers and thus
  have often made efforts to steer clear of them by remaining humble.
  It's quite an irony when you think about it because humble people
  usually keep a low profile when they communicate and thus they should
  have a lower chance of securing success for themselves, as compared to
  a more vocal individual who flaunt their strengths whenever
  opportunities arise Writing for Maximum Impact

EDIT:
In light of your comments below, consider using keep one's cards close to the vest/chest to fit your examples.

play one's cards close to one's chest and play one's cards close to one's vest; keep one's cards close to one's chest; keep one's cards close to one's vest
Fig. to keep to oneself or be very cautious in one's dealing with people. (As if one were playing cards and not permitting anyone to see any of the cards.) He is very cautious. He plays his cards close to his chest. You seem to be playing your cards close to your vest. McGraw-Hill Dictionary of American Idioms and Phrasal Verbs
Comment: @LeonardoCastro 3. Miguel Reale Jr. and his wife, a wealthy Brazilian couple, love taking a vacation to France every year. When they visit, they usually stay at exclusive hotels, but prefer to travel across the country in a plain Renault Clio rental to avoid calling attention to themselves. Actually, they could afford an upper scale car (no doubt about that), but they prefer to go with a plain compact so as to "blend in with the crowd," either because they are humble people, or they just don't want to stick out and be bothered about their wealth.
Comment: Interesting! The expression "blend in with the crowd" gives me the impression that it is only applied to celebrities (Miguel Reale Jr. is kind of a celebrity although not even in Brazil [maybe less in Brazil] very known by the general population). On the other hand, "hiding the gold" could apply even to a hodman hiding his dessert from his coworkers. Is "to blend in with the crowd" usable by anyone? Or is "hiding the gold", and accusing other of doing so, a distinctive feature of Brazilian behavior?
Comment: @LeonardoCastro As an aside, the expression "blend in with the crowd" is not only applied to celebrities. For example, if I were to go on a walk through the favela Santa Marta in RJ, I guess I would avoid wearing things or behaving in a way that might call attention to myself. Instead, I would keep a low profile and have simple, casual clothes on to blend in with the crowd/surroundings.
Comment: @LeonardoCastro Not necessarily. Consider a bourgeois urbanite moving to a small Wisconsin town. They might feel the need to go with a new style of clothing, trade their Jaguar for a more modest car, etc., in order to blend in with the crowd/their new settings. If they didn't do so, they might well attract attention to themselves, or worse, get the evil eye ("olho gordo") from the locals...
Comment: Those expressions seem very similar. I would like to know if they would apply to these situations like Brazilian "hide the gold":

1. Carl is a student. He is very good at drawing. He has a group homework to do that include making a lot of drawing. He doesn't mention his ability to the other students of his group because he doesn't want to make all drawings himself. Finally, they note that his drawing are really better than other students' ones, so one of the other student say to him: "So, you were hiding the gold! From now on, you make all drawings!"
Comment: 2. John is from a very wealthy family and very probably the richest student in his class. As he doesn't want to be pointed out as the "rich boy" by the other students, he doesn't tell anyone how rich he is. Then, James, a classmate, ends up going to John's house and sees with his own eyes how rich he is because of his house. So, James says to him: "You were hiding the gold. You have a large swimming pool, a butler, many video game consoles, etc. And you had never called me here. Don't be that selfsih..."
Comment: I just noted you had edited your answer before my last comment. I think "keep one's cards close to the vest/chest" is very similar to Brazilian "esconder o ouro".
Comment: Is it used only when you're not in your "customary environment", so to speak? Or could you "blend in with the crowd" in your own neighbourhood?
Answer: I've never heard "hide the gold" in English.  I think I'd say "hide one's talents."  But we do sometimes use the expression "hide your light under a bushel," a reference to Matthew 5:15.  "Bushel" here means "container," not the unit of volume.
Answer: From Matthew 5.15: to hide one's lamp [or light] under a bushel. The expression is applied more to the modest concealment of extraordinary abilities than of wealth, though, and often with a hint of reproach.
This is attested (and glossed) as a common expression in British English at Cambridge, and in American English as well via Free Dictionary citing McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
Answer: "To hide gold" is not an idiomatic expression in the English language, though talent (originally a unit of weight for gold) has long been used to mean aptitude by reference to the parable of the talents, as discussed above. It may be that some of the sense of the Brazilian idiom could be captured by the phrase "still waters run deep" -- but the overlap is at most partial, and there may be no overlap at all.


ADK DemoKit - RT-ADK connection Trouble ... USB disconnected

Question: I'm trying to test the Android ADK using the DemoKit app and the RT-ADK board. The DemoKit works about one minute long. However, after that, the run loop of the DemoKit stops. At that time, the program put
the message, "D/vold(117): USB disconnected" to the logCat, and the TX LED of the arduino board
(RT-ADK) flashes twice.
After that, when I click the "back" button of the android terminal, lying android picture appears
short time on the terminal and perhaps, it says, the USB is disconnected.
Did anyone experience the similar situation?  and I'm glad if some one show me how to fix this situation.
I'm using the XPERIA SO-01C, android 2.3.4.
Regards,
Answer: I'm not sure, it is the right solution, but when I provided power from USB AC adopter to the Arduino board, istead of providing power from PC USB connector, the usb resetting has not occured more than several minutes. The page http://arduino.cc/en/Main/ArduinoBoardADK may say the reason.
wrong?:   [android-terminal] --- usb-cable --- [arduino-mega-adk] --- usb-cable --- [PC]
right?:   [android-terminal] --- usb-cable --- [arduino-maga-adk] --- usb-cable --- [AC adopter]
Answer: I experienced a similar situation trying to drive a normal servo using code derived from DemoKit running on Arduino Mega ADK.  When on Arduino USB power, like you, it would disconnect for no apparent reason.  I tried powering off of a 9V battery and it worked better but the symptoms eventually returned so badly that if I put a torque on the servo the USB would disconnect. I checked the voltage of the battery and while connected underload it had sagged to 4.8V, and with no load it was reading 7.2V. I then went to a 7.7V (2S) 1300 mAHr (25C) battery and it has worked fine so far.  It looks like USB circuitry is sensitive to under-voltage during high current draw when servo is moving at high rate or high torque/load.  It looks like enough to trigger USB disconnect logic without more catastrophic effects on Arduino and Android ADK.


How do I get my NPC back into my house from down a cave?

Question: My merchant is stuck a long way down in a cave and I'd like to get him back into my house. I can't make a track back up because it would take an extremely long time. Any ideas?
Comment: I left during the night and decided to kill slime since it was the holiday season and I wanted presents to drop, and when I came back minutes later, he was back in his room.
Answer: +1 to Havatra, however his answer is incomplete.
The NPC will only teleport back to its house when night falls. So when the sun is setting, leave your house, or if you do not have good enough weapons to survive the monsters, go out during the day and build a small shack to protect you. Dirt will work fine. An easy way to do this is to dig 3 blocks down and then place a roof on top. This leaves you with no room to move (unless you dig), but it is the easiest way to build a safe place for the night.
Another way to do this is to use a king/queen statue and wiring. A king statue will teleport a random male NPC, whereas a queen statue will teleport a female one. They will do this when they are activated by an active wire. This method however requires you to have progressed a fair bit into the game, by which time you will have many NPCs and the chance of teleporting the merchant is quite small.
Answer: As long as your NPC is a part of a suitable housing, the NPC will magically despawn and respawn in his/her house when you are not looking. With other words, just move far enough away from the housing, and do something else meanwhile. Most likely, the next time you go back to the house, he'll be there.
Answer: That happened to me aswell. I play the console version of terraria and my guide fell down a cave! I left for a bit and destroyed my house, built it back and left to go mining, when I came back he had moved in to the new house! Hope this works for you.
Comment: But you didn't had to destroy/rebuild the house, only the "go mining" part was useful in your solution.
Comment: Ya maybe for u but me he wouldn't come back up Anton so I tried to rebuild my house and he finally came back/re spawned
Answer: The NPC can teleport to the house if he wandered off too far, but what you can do if you want to do it the fun way take advantage of his AI.
He moves left and right. Make a staircase so he can jump up out then place blocks so he can walk back home. Or you could get a new one by killing a guide voodoo doll (Put stuff in chest first, as this will summon the wall of flesh!) Also this method requires you to make it to hell.