Is this better to have 2x2gb DDR3 RAM in both of the slot or single 4GB DDR3 RAM in single slot in laptop? Which way is right to increase my laptop perfromances, what should I do for best and fast performances?
I'm building a Core  system which supports dual-channel memory (up to 16&nbsp;GB in four DIMMs), my target is 8&nbsp;GB. From the performance perspective, is it better to have two times 4&nbsp;GB or four times 2&nbsp;GB?
I've noticed in the last couple of days that there have been a few occasions when there's been a sudden surge of questions in the SO "Reopen" review queue.  Normally there's either no questions at all to reopen or at most three or four, and that's still the case, except that for the last couple of days I've gone to the review page and seen about fifty-odd questions in the queue, where just moments before there had been none.  I've gone through the reviews and the questions themselves seem reasonably legitimate (including the occasional audit), so I'm not questioning that... it just seems odd that there would be so many more than usual all of a sudden, and that they'd all appear at once.  Anyone got any insights, or should I just chalk this down as "one of those things"? Double-blind review with four references in a row? I've read a lot of answers here about double-blind reviews and thesis or single articles.  My problem comes from having four self-references in my article. I feel that if I include them all, could be very easy to infer that this is the fifth one (It's a 4-year granted project and I have been collaborating in a number of software components inside a bigger architecture, now it's the time to use them all to interact with other applications) . But if I ommit some of them, I could end being accused of self-plagiarism. The other articles have been published in the proceedings of conferences that didn't require double-blind reviews, this is the first submission I make to a conference that asks for it (Maybe because of being CORE A) Also not worthless to mention that I'm going to send it as a short paper, so actually it'd be very helpful to cite rather than to repeat past texts.  What should I do? Infinite group with only two conjugacy classes Background: I'm giving a presentation to colleagues at work on hypothesis testing, and understand most of it fine but there's one aspect that I'm tying myself up in knots trying to understand as well as explain it to others.  This is what I think I know (please correct if wrong!)   Statistics that would be normal if variance was known, follow a $t$-distribution if the variance is unknown CLT (Central Limit Theorem): The sampling distribution of the sample mean is approximately normal for sufficiently large $n$ (could be $30$, could be up to $300$ for highly skewed distributions) The $t$-distribution can be considered Normal for degrees of freedom $&gt; 30$   You use the $z$-test if:   Population normal and variance known (for any sample size) Population normal, variance unknown and $n&gt;30$ (due to CLT) Population binomial, $np&gt;10$, $nq&gt;10$   You use the $t$-test if:   Population normal, variance unknown and $n&lt;30$ No knowledge about population or variance and $n&lt;30$, but sample data looks normal / passes tests etc so population can be assumed normal   So I'm left with:    For samples $&gt;30$ and $&lt;\approx 300$(?), no knowledge about population and variance known / unknown.   So my questions are:   At what sample size can you assume (where no knowledge about population distribution or variance) that the sampling distribution of the mean is normal (i.e. CLT has kicked in) when the sampling distribution looks non-normal? I know that some distributions need $n&gt;300$, but some resources seem to say use the $z$-test whenever $n&gt;30$... For the cases I'm unsure about, I presume I look at the data for normality. Now, if the sample data does looks normal do I use the $z$-test (since assume population normal, and since $n&gt;30$)? What about where the sample data for cases I'm uncertain about don't look normal? Are there any circumstances where you'd still use a $t$-test or $z$-test or do you always look to transform / use non-parametric tests? I know that, due to CLT, at some value of $n$ the sampling distribution of the mean will approximate to normal but the sample data won't tell me what that value of $n$ is; the sample data could be non-normal whilst the sample mean follows a normal / $t$.  Are there cases where you'd be transforming / using a non-parametric test when in fact the sampling distribution of the mean was normal / $t$ but you couldn't tell? Because I'm still living like it's 2008, I run a website with a .in TLD. The website has nothing to do we India and does not target Indian users.  Unfortunately, when I go to Google Webmaster Tools I see that Google have locked my geotargeting status to India:    On the , Google state that:     Sites with country-coded top-level domains (such as .ie) are already associated with a geographic region, in this case Ireland. In this case, you won't be able to specify a geographic location.   This seems implausibly inflexible, so I want to know if there are any sneaky ways of removing auto-geotargeting, or changing it to a more appropriate region? Mute conversations on Skype I'm in a conversation and I don't really want to leave because the people there keep adding me back so it's just whatever. But I would like to mute the conversation or something like I do on Facebook so I won't take notifications or anything from there unless I press on the group and see what's going on. Because for now I have my Skype having a new notifications every half a second.  Any solutions to that? Ordered N-Tuples as Cartesian Products of Indexed Families In Introduction to Topology, Mendelson defines the Cartesian Product of an Indexed Family as follows:     DEFINITION  Let $\{X_\alpha\}_{\alpha \in I}$ be an indexed family of sets. The product  of the sets $\{X_\alpha\}_{\alpha \in I}$,    written  $\prod_{x\in I}X_\alpha$ consists of all functions $x$ with domain the indexing set $I$ having the property that for each $\alpha \in I$, $x(\alpha)\in X_\alpha$.    Halmos, in Naive Set Theory, makes the following observation about this sort of product:     Ordered triples, ordered quadruples, etc., may be defined as families whose index sets are unordered triples, quadruples, etc.   However, it is not immediately apparent to me why this is true. It makes sense if we understand the prior assertions in Halmos that $\prod_{i \in I} X_i = X_i$ and that $\prod_{i \in I} X_i = X_a \times X_b$ when $I = \{a, b\}$, but these already pose difficulty for me.  Let $I = \{0, 1\}$, let $X_0 = \{A, B\}$, and let $X_1 = \{C, D\}$. Then by Mendelson's (and Halmos's) definitions, it would seem to me that . . .  $$\prod_{i \in I} X_ i = \{\{(0, A), (1, C)\}, \{(0, A), (1, D)\}, \{(0, B), (1, C)\}, \{(0, B), (1, D)\}\}$$  This would appear to me to be the set of all functions matching the definition given, but it is not equal to $X_0 \times X_1$. Moreover, extending this to a case where the index set $I$ is a triple, we would not end up with ordered triples, but with each subset of the product containing three ordered pairs.  When Halmos posits the equalities he does, the idea seems easy to grasp, but the peculiar wording of Mendelson's definition suggests something different to me. Proof that $\suṃ̣_{k=1}^{n}k {n \choose k}$ for $n \in \mathbb N$ is equal to $n2^{n-1}$.  As a hint I got that $k {n \choose k} = n {n-1\choose k-1} $.  I tried solving this by induction but, in the inductive step I'm not arriving to the correct result. One of the achievements for the Thieves Guild says "Restore the Thieves Guild to its former glory."  Brynjolf doesn't say anything to me, I can't seem to find Karliah, and as far as I can tell, I am finished with the plotline quests for the Thieves Guild. All I have left available are repeatable quests from Vex and Delvin.  How can I get this achievement? Today, we had a math class, where we had to show, that $a_{100} &gt; 14$ for  $$a_0 = 1;\qquad a_{n+1} = a_n + a_n^{-1}$$  Apart from this task, I asked myself: Is there a closed form for this sequence? Since I didn't find an answer by myself, can somebody tell me, whether such a closed form exists, and if yes what it is? 2 GROUP BY WITH DISTINCT , SUM , COUNT : PHP MYQL Ref :   I got answer (thanks coytech ) but i need one more column in its :  as per :  id | mid | pid | owgh | nwgh | 1    3      12    1.5    0.6 2    3      12    1.5    0.3 3    3      14    0.6    0.4 4    3      15    1.2    1.1 5    4      16    1.5    1.0 6    4      17    2.4    1.2  7    3      19    3.0    1.4   i got answer      Select mid ,          COUNT(distinct pid) as cpid  ,          SUM(nwgh) as totalnwgh  from test  GROUP BY mid   sqlfiddle :   mid  cpid       totalnwgh 3      4          3.8 4      2          2.2    But above i need one more column that's as below : totowgh  mid cpid        totalnwgh  totowgh 3      4          3.8        6.3 (DISTINCT value as per pid column) 4      2          2.2        3.9   where totowgh = 6.3 come by DISTINCT value of owgh column  as per distinct pid column  mid = 3 has count 5 but distinct pid  = 4 for mid=3 same way "distinct" owgh = 6.3 for mid=3 and distinct pid.  As pid=12 , column owgh value 1.5 is twice ...hence its is count 1 time hence,  1.5 + 0.6 + 1.2 + 3 = 6.3 ( please not this is as per DISTINCT value of pid )  Please note : i need distinct owgh value as per distinct pid or group by pid .. because if i replace value of owgh 0.6 with 1.5 then it will be 5.7 instead of 7.2 but value of owgh 0.6 belong to pid = 14 and not pid = 12 hence totalcount of owgh change ...but i need is 7.2  SEE WHAT I MEANS   : Restrict certain mods to certain worlds Let $A,B,C$ be sets, and $B \cap C=\emptyset$. Show $|A^{B \cup C}|=|A^B \times A^C|$ Let $A,B,C$ be sets, and $B \cap C=\emptyset$. Show $|A^{B \cup C}|=|A^B \times A^C|$ by defining a bijection $f:A^{B \cup C} \rightarrow A^B \times A^C$.  Any hints on this one?  Thank you! I'm not sure how to remove the line that represents the 180th meridian (international dateline) on my polygon. I have the "Russia Country Boundary 2017" feature layer added from the Living Atlas. My Projected Coordinate System is set to "Asia North Albers Equal Area Conic". I've tried to google this question, but I haven't come across an answer I can fully understand. I'm a student and very new to all this!  The line is actually a gap between the polygons.   Using ArcGIS Pro 2.3.1  ANSWER:  It turns out I was not projecting correctly, which was creating issues down the line when editing polygons. Here's what I did...  1. Start a blank project in ArcGIS. Insert new map, go into its     properties, change the Coordinate System to "Asia North Albers Equal     Area Conic".  2. Add "World Countries (Generalized)" from the Living     Atlas. Select Russia and Export Features to new feature class layer.  3. Search and select the Project tool from Analysis>Geoprocessing>Tools.   4. Select the Russia layer for input. Select "Current Map" for Output Coordinate System. Run.  5.Now edit the polygons to close the gap and merge to remove any lines. All done!  The only thing that bothers me with this fix is the addition of shape area (484,914.49674 m²) and shape length (4.59 m) to the original Russia polygon. These numbers could be different depending on how you close the gap, and possibly affect data projections depending on your use of this map? Is being a Cauchy sequence equivalent to $ \lim_{n\to+\infty}d(x_{n+k},x_n)=0$ for every $k$? Is this statement true?      In a metric spase $(E,d)$, a sequence $(x_n)$ is Cauchy if and only if $  \forall k\in \mathbb{N}, \lim_{n\rightarrow+\infty}d(x_{n+k},x_n)=0$   I proved that $\Rightarrow$ is true,indeed if $(x_n)$ is Cauchy then for all $\varepsilon&gt;0,\exists n_0\in\mathbb{N}, \forall p,q\geq n, d(x_p,x_q)&lt;\varepsilon$ it still right for all $ n\geq n_0$ and $m=n+k&gt;n\geq n_0$   But I don't know if $\Leftarrow$ is true ? By integration by parts and the substitution $x = \sin t$ we can easily calculate the integral $\int_{0}^{1} \ln (x+ \sqrt{1-x^2})dx$ which equals to $\sqrt{2} \ln (\sqrt{2} +1) -1.$ I’ve tried to use the same substitution $x = \sin t$ to calculate the integral $ \int_{0}^{1} \frac {\ln (x+ \sqrt{1-x^2})}{x}dx,$ which becomes $$ \int_{0}^{\frac {\pi}{2}} \frac {\ln \sin (t+ \frac {\pi}{4})}{\sin t}dt$$ It seems difficult to solve the particular integral. Any help? Delete all but the most recent n file for each group of files that share the same prefix in a directory My question is a bit different from some older questions simply asking for "deleting all but the most recent n files in a directory".  I have a directory that contains different 'groups' of files where each group of files share some arbitrary prefix and each group has at least one file. I do not know these prefixes in advance and I do not know how many groups there are.  EDIT: actually, I know something about the file names, that is they all follow the pattern prefix-some_digits-some_digits.tar.bz2. The only thing matters here is the prefix part, and we can assume that within each prefix there is no digit or dash.  I want to do the following in a bash script:   Go through the given directory, identify all existing 'groups', and for each group of files, delete all but the most recent n files of the group only. If there are less than n files for a group, do nothing for that group, i.e. do not delete any file for that group.   What is a robust and safe way of doing the above in bash? Could you please explain the commands step-by-step? Ok. I was playing mcpe and I noticed that mossy cobblestone isn't in the crafting table. And I wanted to make a house that looks old. So if its possible to get mossy cobblestone without mods, how can I get it on survival? If it is possible can somebody please leave a step by step guide. Thank you. Does deleting iCloud photos affect them on devices? If I delete a photo from my iCloud will it also be removed from my devices that are connected to my account? I have a question:     Suppose $f$ is continuous and even on $[-a,a]$, $a&gt;0$ then prove that   $$\int\limits_{-a}^a \frac{f(x)}{1+e^{x}} \mathrm dx = \int\limits_0^a f(x) \mathrm dx$$   How can I do this? Don't know how to start.