How many permutations are there in the word "arrangement" that have exactly two of the following consecutive letters in them: aa,ee,rr,nn? For example: "aarrngement"
What does distinct permutations mean and how many distinct permutations can be formed from all the letters of word TOFFEE?
How to filter features in a layer? I am trying to display certain features in a shapefile-based layer using QGIS. I have found the subset function in the properties panel, which does exactly what i want, but is too tedious given that I have to manually sift through a large number of features. Is there a quicker way to do this?  I am using both shapefiles and postGIS best,  dietmar Why does a bigger sensor lead to a shallower depth of field? It has been mentioned at    that a larger sensor results in images with a shallower depth of field. Example image:          I understand how sensor size would relate to, for example, field of view, but the relationship with depth of field does not seem straightforward.  It actually seems contradictory - I have more wells on my sensor, and I am able to focus on less number of points.  What is the reason for this effect? How do I check whether a file exists without exceptions? Suppose I have a dataframe consisting of six time series. In this dataframe, some observations are missing, meaning at some timepoints all time series contain a NA-value. In R, one possible imputation package that can be used to impute time series data is Amelia. However, this package does not work for observations that are completely missing. Are there other ways to impute my data? For what it's worth, the amount of missing observations is less than 20% of all observations. How do electric currents make light? In an incandescent light bulb, electrons flow through wires to the bulb, where is passes through a filament, and the filament lights up.  Does this work because of several high energy electrons losing some of their energy to disturb the electromagnetic field, creating photons? The electrons just leave the filament afterward and are replaced by more high-energy electrons from the negative terminal. Or does it work differently?  As a secondary question, is there a type of light bulb that directly converts electron flow to photons? Sometimes a suggested edit is  because of a concurrent direct edit that takes precedence.  Since this is no fault of the edit suggestor, such rejections should not count against the suggestor when counting .  Here are some examples where it happened: In Minecraft, I know you can breed animals. In fact, in recent updates it's required for the player who just can't start their mornings without bacon and eggs!  I've tried pulling two pigs together in a single pen, but all they do is snort at me. And the chickens? Well, there's plenty of eggs, but no hatching.  How do I get them to make more bacon and eggs? How do I create a dynamic key to be added to a JavaScript object variable Keyboard macro to change default audio device Windows 7, Logitech G110 keyboard  2 audio devices (headphones and speakers)  I am hoping to find a quick way to macro a key to switch to headphones, and a key to switch to speakers.  Anyone have a good program or anything of that nature?  EDIT:  Using AHK to try and get this task working as hoped is sadly not doing the trick.  I have included a screenshot of my audio set, as well as a screenshot of my script as it sits now.    I have also tried to uncheck "show disabled devices" and modified the script to be Down 1, and Up 1 respectively.  It will work for one device, but it refuses to switch to the secondary. How do I technobabble without sounding like technobabble? On occasion, I've had reason to describe obviously fictional technical processes in-character. I'd like to be able to describe on these occasions without sounding like I'm saying utter gibberish. But it's not straightforward to do, particularly if I have to make stuff up on the spot.   How do I do it? Why do I have to press Ctrl+D twice to close stdin? I have a map a at the link below:    I added one of my GeoServer WMS layers to the map, now I try to add the attributes window pop up on click. I found to examples on the OpenLayers 3 homepage, but I cannot put together a working code...      Is there any chance to have a working sample somewhere? What is wrong with this substitution? How can I pad an integer with zeros on the left? Rosewill RNX-N600UBE Connectivity issue on Ubuntu 17.04 In $Sets$, the initial object is $0 = \emptyset$. We have $C \times \emptyset = \emptyset$ for any set $C$. As there are no maps to the empty set, we don't get much of the universal property of the product.  I am now wondering what is special about arbitrary categories $\mathscr{C}$ with $C \times 0 \cong 0$ for all objects $C$ of $\mathscr{C}$, where $0$ is the initial object of $\mathscr{C}$.   From Sheaves in Geometry and Logic by MacLane (p.194), in any topos $\mathscr{C}$, any arrow $k:C \to 0$ is an isomorphism. The universal property of the product would then also not yield very much.   Are there any categories of higher interest? Maximum power transfer and Thevenin I am trying to find the thevenin resistance value and the Vth for maximum power transfer. I have tried to find Rth by calculating R3 and R2 as parallel resistance and same for R4 and R5 and then adding them with R1 but I am not sure if I have done it the right way. For Vth I have tried using KVL but I think I have calculated wrong current values using current divider rule. I calculated the total current by diving V1 and R1. I hope someone can help. I have attached the picture of the circuit. $|e^a-e^b| \leq |a-b|$ for complex numbers with non-positive real parts Example of modules that are projective but not free; torsion-free but not free Uninstall Kali Linux from triple boot