Lets say that you have a connected car battery. If you remove the negative lead first and then touched it would the current go through you to the earth (GND)?  What is i then attached a wire which is touching the ground to the negative battery terminal?
First, if you have a better suggestion for title I'm really opened to suggestions, but it is the best I came up with.  If I touch an electric line and the earth, I will get electrocuted.  However, if I touch the positive of a car battery, people told me the same thing won't happen...why is it?  It seems I need to touch the battery positive and the battery ground.
The dissolve tool (vector>geoprocessing tools>dissolve) renders some artifacts on shapes with high number of polygons. I’m using a  with 3222 polygons and I’m trying to dissolve it using the field “municipio”, but when the dissolve tool ends calculating the new shape has some artifacts     Does anyone had a similar problem? How to work around it?  I’ve also used v.dissolve from GRASS and the dissolve polygon from SAGA, but the problem persists. I’ve used the same shapefile on ArcGIS 9.3 with the dissolve tool. None artifact/error was produced.  Edit 1  I'm trying to use the v.clean tool as sugested by WhiteboxDev. However I'm getting this error:     An error has occured while executing Python code:      Traceback (most recent call last):   File   "C:/PROGRA~1/QGISCH~1/apps/qgis/./python/plugins\processing\gui\ProcessingToolbox.py",   line 181, in executeAlgorithm   File   "C:/PROGRA~1/QGISCH~1/apps/qgis/./python/plugins\processing\algs\grass7\Grass7Algorithm.py",   line 511, in checkBeforeOpeningParametersDialog   File   "C:/PROGRA~1/QGISCH~1/apps/qgis/./python/plugins\processing\algs\grass7\Grass7Utils.py",   line 361, in checkGrass7IsInstalled   File   "C:\PROGRA~1\QGISCH~1\apps\Python27\lib\ntpath.py", line 96, in join   TypeError: object of type 'NoneType' has no len()      Python version:   2.7.4 (default, Apr  6 2013, 19:54:46) [MSC v.1500 32 bit (Intel)]      QGIS version:   2.4.0-Chugiak Chugiak, 8fdd08a      Python path:   ['C:/PROGRA~1/QGISCH~1/apps/qgis/./python/plugins\processing',   'C:/PROGRA~1/QGISCH~1/apps/qgis/./python',   u'C:/Users/CERCOTRICHAS/.qgis2/python',   u'C:/Users/CERCOTRICHAS/.qgis2/python/plugins',   'C:/PROGRA~1/QGISCH~1/apps/qgis/./python/plugins',   'C:\PROGRA~1\QGISCH~1\bin\python27.zip',   'C:\PROGRA~1\QGISCH~1\apps\Python27\DLLs',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\plat-win',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\lib-tk',   'C:\PROGRA~1\QGISCH~1\bin',   'C:\PROGRA~1\QGISCH~1\apps\Python27',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\GDAL-1.11.0-py2.7-win32.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\PIL',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\jinja2-2.7.2-py2.7.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\markupsafe-0.23-py2.7-win32.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\python_dateutil-2.2-py2.7.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\pytz-2014.2-py2.7.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\win32',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\win32\lib',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\Pythonwin',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\Shapely-1.2.18-py2.7-win32.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\six-1.6.1-py2.7.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\wx-2.8-msw-unicode',   'C:\PROGRA~1\QGISCH~1\apps\qgis\python\plugins\fTools\tools',   'C:\Program Files\SpiderOak\shell_extension_lib\shared.zip']   Not entirely sure if this error is QGIS related... Any idea why I'm getting this error and how can I solve it? I am creating a type of adventure map. Once you enter the map, you step on some pressure plates that are supposed to seamlessly close the wall behind you. For some reason this command does not work when in a command block or just in text. Here is the command:  /fill -17 4 -109 -18 5 109 minecraft:light_gray_concrete   The output it gives me is "That position is not loaded". I am on a singleplayer superflat world in 1.14.3. Any help would be very appreciated! My ceiling fixture has all of a sudden stopped working properly. Half the diodes are dark and the others are blinking. Oddly, the same exact ones on each strip work and don't work. I have included a picture to show which ones are blinking and which ones don't work. I am wondering if it is something that I can fix? Maybe replace that driver? And if so, is there a good guide online to walk me through that process? Thanks in advance. I noticed that the locked message still references the FAQ. See :  locked by  yesterday This question exists because it has historical significance, but it is not considered a good, on-topic question for this site, so please do not use it as evidence that you can ask similar questions here. This question and its answers are frozen and cannot be changed. More info: .  Since the FAQ has been replaced by the , this message should provide a link there instead. Currently, the link actually takes you to the ; even if it doesn't link to the help center, the text should probably be something like &quot;More info: &quot;. Move files from multiple folders all into parent directory with command prompt I have multiple .rar files in multiple folders like this:    C:\Docs\Folder1\rarfile1-1.rar C:\Docs\Folder1\rarfile1-2.rar C:\Docs\Folder1\rarfile1-3.rar    C:\Docs\Folder2\rarfile2-1.rar C:\Docs\Folder2\rarfile2-2.rar C:\Docs\Folder2\rarfile2-3.rar    C:\Docs\Folder3\rarfile3-1.rar C:\Docs\Folder3\rarfile3-2.rar C:\Docs\Folder3\rarfile3-3.rar     I want to move all of the .rar files to the parent directory 'C:\Docs'. I have a lot more than 3 folders, so I was thinking of making a batch file or something. What would be the commands to do this? Thanks I often end up issuing complex commands over ssh; these commands involve piping to awk or perl one-lines, and as a result contain single quotes and $'s.  I have neither been able to figure out a hard and fast rule to do the quoting properly, nor found a good reference for it.  For instance, consider the following:  # what I'd run locally: CMD='pgrep -fl java | grep -i datanode | awk '{print $1}' # this works with ssh $host "$CMD": CMD='pgrep -fl java | grep -i datanode | awk '"'"'{print $1}'"'"   (Note the extra quotes in the awk statement.)  But how do I get this to work with, e.g. ssh $host "sudo su user -c '$CMD'"?  Is there a general recipe for managing quotes in such scenarios?.. What would be the right position of "substantially" in the following:     1). Before verb: These optimal values substantially contribute to the success of the methodology.      2). After verb: These optimal values contribute substantially to the success of the methodology.   Here is my issue:  Fact1: When I use Google Ngram, I get , 0 occurrence of option 1.  Fact2: I found an excellent Grammar book that discusses Adverbs, their types and prefered positions. The author defines some rules that I'll summarize as follows:   Connecting adverbs, eg: however, then,..., Position: Beginning of clause. Indefinite frequency, eg: always, usually,..., Position: Mid position (after auxilary verb, before other verbs) sometimes beginning of clause. Focusing adverbs, eg: mainly, only,..., Position: Mid position. Adverb of certainty, eg: clearly, obviously, Position: Mid position. Adverb of completeness, eg: almost, nearly,..., Position: Mid position. Adverb of manner, eg: fast, slowly, nicely,..., Position: End clause, mid and beginning. Adverb of place, eg: upstairs, around, Position: End clause, sometimes beginning. Adverb of time, eg: daily, weekly, ... Position: Mostly end clause, sometimes beginning and mid position.   I think that "substantially" is an adverb of completeness. Therefore, the right position is before the verb "contribute" (option 1). However, Google Ngam indicates that option 1 is not widely used.  What do you think? Any suggestions? I want to build a flow to trigger an email when a date in one of the fields is nearing. I have a field named Payment due date. is it possible to trigger an email 2 days prior to the Payment due date. So that I don't miss the payment due date and payment is not delayed. Any kind of assistance is appreciated. Thank you very much in advance! Ignoring somebody screws up the avatar list When I ignore a user, the avatar list looks weird.    The blank line beneath the row with the avatar of the ignoree is quite annoying.    I use Google Chrome on OS X.  There was a  tagged  but it still looks weird. Arduino-controlled slot cars - alternative to MOSFETs for speed control? I'm attempting to control the speed of two slot cars in a set using Arduino.    Each car is controlled by a controller with a variable resistor that looks like this:    They're wired in parallel to the same 17V DC power supply:    Simplified:    For Arduino control, I experimented with manipulating a single car's speed using a MOSFET. It worked really well. Using a PWM output on the Arduino, I was able to pulse the MOSFET on and off to throttle the current and change the car's speed. The behavior of the MOSFET seemed to be exactly the same as the variable resistor controller; the resistance, voltage, and current fluctuated the same way on various parts of the circuit.  Enter car B. I added a MOSFET to the setup and mimicked the MOSFET wiring for car A, grounding them both to the Arduino ground. The result looks like this:    Here's a sketch:    Close up, MOSFET A:    MOSFET B:    At first, all seemed well. I sent signals to MOSFET A and successfully changed Car A's speed. I stopped Car A and pulsed MOSFET B, and I was able to control Car B's speed just fine.  Then, I turned Car B to a constant speed, and sent a signal to MOSFET A while Car B was still running. Car A started, but Car B's speed immediately dropped as a result of running Car A.  I hooked a multimeter up across the rails of Car B and watched its voltage while it ran on its own. Then, sure enough, when Car A started running alongside it, Car B's voltage dropped dramatically.  I figured this was because of my wiring configuration, so I left the multimeter on Car B, and made one change. I replaced MOSFET A with the original slot car controller:    I started running Car B again using its MOSFET. The multimeter showed a steady voltage, so I began to squeeze Car A's controller (the variable resistor), and Car A's speed increased. This time, however, unlike using a MOSFET to control Car A, the variable resistor did not affect Car B's voltage at all. Car B remained at a steady speed the whole time.  Any idea why this happens? The MOSFET seemed to function the same as the variable resistor (empirically) with a single car, but had totally different behavior with two cars in parallel. Is it because the MOSFET is not really changing resistance to current, but just switching it on and off, so it opens up another path for current to flow fully every time it closes? Is there an Arduino-controllable alternative to a MOSFET that would fluctuate actual resistance like the variable resistor? Digital potentiometer? Servo hooked up to a potentiometer? ;) I'm really curious what the difference is and what causes the major differences in behavior. Does Wolfram Mathworld make a mistake describing a discrete probability distribution with a probability density function? Tips for getting really good answers on SO The following integral should be doable using the residue theorum:     $$\frac1{2\pi}\int_{0}^{2\pi}e^{\cos\theta}\cos(n\theta) \,d\theta$$ I'm looking for a source/spec that can tell me what CSS properties can applied to which HTML elements.  For instance, the css property; "overflow".  I know I can apply this to div, p, textarea but what other elements can I apply this too?  Is there a spec somewhere I can reference? ACPI error when trying to make dual boot with Ubuntu 18.04 and Windows 10 What noun or adjective would one give to a person that is intolerant of stupidity? A person that becomes annoyed, angry, or of very short temper when conversing or interacting with people of a lower intelligence?  For example:       The man is very xyzxyz; his son can't do multiplication very well.     or     She is a(n) xyzxyz. She gets very frustrated when people forget things.   I'm looking almost for a scientific/medical/psychological term. One that would fall into the same kind of group as words like haemophiliac, masochist, nihilist, etc. When choosing cards for a deck, one of the most important things to consider is the number of land you put in. The biggest issue is mana curve, of course. What shortcuts are best for determining the proper amount of land with a given mana curve? How to insert text into a root-owned file using sudo? Why is my starting gravity low? In the fall of 2011 I made the leap from extract/partial kits to all-grain kits. I'm enjoying AG, but my SG is continuously below the expected. I have brewed 5 AG kits and 4 have had a low SG.   My assumption is my sugar extraction during mashing (or sparging) isn't optimal. I heat my mash water to 165 and mash the grains for 60 minutes. Mashing levels out at 152. For Lautering I heat the water to 175-180. After I drain the initial mash I add the lautering water and let that soak for 10 minutes. the temperature levels out around 170-172. Then I drain into the kettle and being the boil.  I aim for a gentle boil just enough to break the surface tension. I boil for 60 minutes, chill, rack, take a reading and pitch yeast.  Here are some of the numbers  type            expected     actual  kit st paul porter  1.052        1.039   http://www.northernbrewer.com/shop/st-paul-porter-all-grain-kit.html belgium strong  1.067        1.055   http://www.midwestsupplies.com/superior-strong-ale-all-grain-kit.html troegs hop back 1.063        1.049   http://www.byo.com/stories/recipeindex/article/recipes/90-american-amber-a-pale-ale/2196-troeegs-hopback-amber-ale-clone   The fuorth was the Phat Tyre kit from Northern Brewer. Can't remember the SG though. It was low. They taste great, but the numbers weren't "right". What can I adjust so the numbers are more inline with the recipe?   Update Thank you for all the feedback. There are a number of factors for me to review and adjust. Given my current setup I will follow @mdma advice and recirculate the wort once and extend lautering to 30 minutes.  It will be a week or two before I can attempt this, so it will be awhile before I report back again.  Update #2 I now have some awesome local contacts who are helping me out with technique and trouble shooting. Another (major) issue I could be experiencing is draining the wort way too fast. According to my friend. The drain should be low and slow after cycling a gallon or 2 of wort. sparging should take ~2 hours. for each gallon drained plato/brix should drop 3 points and go no lower than 3-5 points at the end.  the second recommendation is to heat up 3-5 gallons of water to 180 and poor it in prior to/while sparging.  my first attempt using this technique proved successful with the gravity being a lot closer to the anticipated OG. I had some temp issues with the batch, but I was so focused on sparging that I ignored the temp. My guess is I would have been right on if my temp didn't fall so low.  Update #3 I had the chance to brew with my mentor this weekend and he pointed out 2 glaring problems with my mashing technique.   Starting mash temp is too low. I was heating my water to 10-12 degrees above target temp. He recommends 17 degrees. between grain absorption &amp; the tun itself most of the heat dissipates within the first few minutes. This does go against what I originally said. That I was hitting my temp marks. Looking back I was hasty with my readings. I should not dump my sparge water (or lauter?) into the tun while draining the wort. The idea is to compact the liquid into the bottom of the tun thus compacting the sugars. I am stirring up the mash when I dump all sparge water in. We kept our sparge water 1-2 inches above the grain bed and our final results we excellent.   A 3rd recommendation he made was to lower the pH of the water. tap water is ~7 and the ideal mash pH is 5.2. He added a solvent, which I cannot remember the name of, which did this for us. I'll be picking up some of that this weekend.  Thanks to all who helped me out with this problem. Can you add a separate discussion site? Sometimes you just want to let out some steam, and troll about some technology or software. You are not looking for any answers, but for users with similar experiences and interesting stories. So why not create a separate discussion site (trolling.stackoverflow.com?), where you could ask questions like "why do you hate technology X" or "What are the stupidest bugs you encountered in X"?