I'm using ubuntu 14.04.1. I installed lxde for lubuntu desktop environment. But it's creating a lot of problems for me, so I want to completely remove it now. I read the instructions online and followed them. I've removed all the files by all the ways explained on askubuntu and ubuntuforums. But it's not gone yet. But as explained in question  hasn't work for me. Please suggest, I don't want to re-install my ubuntu.
I installed few environments that I wanted to try out on Ubuntu 12.04, but none of them worked at all. It could be that I installed them all at the same time, meaning the OS didn't get a chance to work everything out, but either way, they didn't work. I would now like to remove them.   The one's that I installed are Xubuntu/Xfce, Lubuntu/LXDE, Kubuntu/KDE, Fluxbox, OpenBox, cinnamon, and MATE. I installed them. Everything seemed to have been working properly until I actually tried to use the shells and nothing loaded at all. Except for Fluxbox, I think that one worked. I want to know of any way to repair or perhaps just remove the packages entirely. I might have already removed them because I did the apt-get remove command on all of them, but they were still in the list on the login screen.
I've recently installed Fedora 19.  is installed. But its own examples don't work. When I enter gedti the output is:  bash: gedti: command not found... Similar command is: 'gedit'   And it works correctly but when I enter powertop, the output is:  bash: powertop: command not found...   With no suggestion about the package. Why? Should I edit some configuration files or update some cache or ... ? Sensor for detecting airsoft bullet I'm trying to make airsoft chronograph/chronometer (a device that measures airsoft bullet speed). The idea is to measure time in which bullet is traveling from point A to point B, and then I can calculate bullet speed. Bullet is shot into plastic pipe with diameter of 32mm. I've tried to put on one side IR LED and on the other side phototransistor (BPW 40), both at the start and end of the tube. Something like this:  Blue circles are phototransistors, red circles are IR LEDs and white circles are airsoft bullets. When bullet passes through area where bullet 2  is drawn (just in between IR LED and phototransistor), everyting works perfectly. But when the bullet passes where bullets 1 and 3 are drawn, it isn't detected. That is expected, but unwanted behavior. So my question is: how can I detect bullets regardlessly of it's position ? I've thought about putting IR LEDs and phototransistors around the pipe (not only in one place), like this:  but this solution isn't cheapest: 5 IR LEDs + 5 BPW 40 = cca $12 times 2 (because I need it on both sides of the pipe) = $24. Is there any cheaper solution ? Is BPW 40 good choice for phototransistor ? I don't know which IR LEDs I'm using (and salesman in the store also doesn't know - he told me these are generic ones for remote controllers, like TV or DVD controller). Diameter of the pipe is 32mm and it will be long about 14cm (sensors will be 10cm apart). Diameter of airsoft bullet is 6mm. EDIT: I'll go for my second idea. I just have one more question: is it better to arrange IR emitters and photo transistors this way:  or this way:  Thanks !! I know that new arXiv papers usually appear in Google Scholar within a few days or weeks. My question is: if someone submits a replacement of his/her arXiv paper, does the new version of the paper also appear in Google Scholar? I am curious about the practical implementation of a binary split in a decision tree - as it relates to levels of a categorical predictor $X{j}$.  Specifically, I often will utilize some sort of sampling scheme (e.g. bagging, oversampling etc) when building a predictive model using a decision tree - in order to improve its predictive accuracy and stability. During these sampling routines, it is possible for a categorical variable to be presented to a tree fitting algorithm with less than the complete level set.  Say a variable X takes on levels {A,B,C,D,E}. In a sample, maybe only levels {A,B,C,D} are present. Then, when the resulting tree is used for prediction, the full set may be present.  Continuing from this example, say a tree splits on X and sends {A,B} to the left and {C,D} to the right. I would expect the logic of the binary split to then say, when faced with new data: "If X has value A or B, send to the left, otherwise, send this case to the right". What seems to happen in some implementations is "if X has value A or B, send to the left, if X has value C or D send to the right". When this case takes on value E, the algorithm breaks down.   What is the "right" way for a binary split to be handled? It seems the much more robust way is implemented often, but not always (see Rpart below).  Here are a couple examples:  Rpart fails, the others are ok.  #test trees and missing values  summary(solder) table(solder$PadType)  # create train and validation set.seed(12345) t_rows&lt;-sample(1:nrow(solder),size=360, replace=FALSE) train_solder&lt;-solder[t_rows,] val_solder&lt;-solder[-t_rows,]  #look at PadType table(train_solder$PadType) table(val_solder$PadType) #set a bunch to missing levels(train_solder$PadType)[train_solder$PadType %in% c('L8','L9','W4','W9')] &lt;- 'MISSING'   #Fit several trees, may have to play with the parameters to get them to split on the variable  ####RPART mod_rpart&lt;-rpart(Solder~PadType,data=train_solder) predict(mod_rpart,val_solder) #Error in model.frame.default(Terms, newdata, na.action = na.action, xlev = attr(object,  :  #factor 'PadType' has new level(s) D6, L6, L7, L8, L9, W4  ####TREE mod_tree&lt;-tree(Solder~PadType,data=train_solder,split="gini") predict(mod_tree,val_solder) #works fine  ####ctree mod_ctree&lt;-ctree(Solder~PadType,data=train_solder,control = ctree_control(mincriterion = 0.05)) predict(mod_ctree,val_solder) #works fine Redefining "cited on" string (and others) in biblatex I'm trying to modify the strings biblatex uses to set the "cited on" string used in the bibliography to identify the pages where a given references has been cited.    What I gather from the biblatex documentation (e.g., § 4.9.2.16) is that something like   \renewbibmacro{backrefpage}{&lt;newtext&gt;} \renewbibmacro{backrefpages}{&lt;newtext&gt;}   ought to work, but they have no effect for me (I'd also like to get this working for the "visited on" string, urlseen).  My MWE is unchanged from , with the addition of these (and related lines) just about anywhere. UK Visa has been refused for false document I applied for a marriage visitor visa, to get married to my boyfriend of 2 years.   We met while we were students in the UK and have had vacations together in the two years but not in the U.K.   With the application I had attached an offer letter from a company stating that I have a job offer open starting 3 months later.   This however has been tagged as non genuine, although the company is registered and is run by someone I know.  How can I appeal to this? How can you convert a byte array to a hexadecimal string, and vice versa? Let $\left| {{a_{ii}}} \right| > \sum\limits_{i \ne j} {\left| {{a_{ij}}} \right|} $.Why does $A$ is nonsingular? . Is there a set of lines in $\mathbb{R}^3$ such that their union is equal to the set of points with not all coordinates rational? Does there exist a set L of pairwise disjoint lines, each line in an axis direction, in $\mathbb{R}^3$ such that their union is equal equal to $\{ x : x \text{ has at least one irrational coordinate}\}$? Why could the pictures and paintings in Hogwarts talk and the photos of Harry's parents couldn't? Combinatorics identity question I encountered this particular combinatorial identity :$$\begin{align}&amp;1\dbinom{n-1}{r-1}+2\dbinom{n-2}{r-1}+\cdots+(n+1-r)\dbinom{r-1}{r-1}\\=&amp;\dbinom{n}{r}+\dbinom{n-1}{r}+\cdots+\dbinom{r}{r}\\=&amp; \dbinom{n+1}{r+1}\end{align}$$How does one figure it out? Proof that every metric space is normal Difference between == and === in JavaScript Installing PHP 5.3 in Ubuntu 14.04 Where does the damage of relocated dashes land? The end location of a dash or jump can be changed by an ability that pushes () or pulls () you. So for example I try to  on the adc, but a Blitzcrank pulls me, preventing me from landing on my chosen spot.  Will I deal my AoE damage around the adc, where I tried to land, or around the Blitzcrank, where I ended up landing? I have always argued adamantly, as long as the issue has been around, that gift should never be used as a verb. However, someone whose English knowledge I quite respect disagrees.  I’ve done some searching and I haven’t found a consensus; should gifting be shunned? List all columns for a specified table Is a diode needed for this simple mini solenoid circuit? Ubuntu 12.04 boots to TTY1 PDF of a sum of exponential random variables Let $X_i$ for $i=1,2,...$ be a sequence of i.i.d exponential random variables with common parameter $\lambda$. Let $N$ be a geometric random variable with parameter $p$ that is independent of the sequence $X_i$. What is the pdf of the random variable $Y=\Sigma_{i=1}^N X_i$.