I was discussing with a workmate whether user interfaces should be phrased in a positive or a negative manner. I've observed positive sentences are clearer than negative ones to the average user.  I've heard some discussions on this matter and most people seem to agree that phrasing positively yields better results in user experience than negative ones. But is there a UX recommendation on this?  EDIT:  to be clearer: should I notify my user that his/her input data is invalid by saying "input is invalid" or "input is not valid"? Or does it not affect UX at all?  Is it better to negate a positive verb or use a verb that has a negative meaning in itself?
Does the use of words such as 'fail', 'wrong', 'incorrect' and 'invalid' have a sufficiently negative impact on a users frame of mind to warrant the prohibition of their inclusion in the error messages generated by typical web forms?  i.e. Should we rephrase examples like these to just use positive words?  'date entered incorrectly'  or  'failed to complete registration, please see below for invalid field entries'  (PS, the examples are there to show use of the words in an error message, not to serve as examples of error messages I would use or things that need correcting in answers, I'm not looking for advice on how to write form error messages, but for information about the effect of certain words on a users frame of mind)
When do I need to invoke \phantomsection? How many physical degrees of freedom does the $\mathrm{SU(N)}$ Yang-Mills theory have? Fancyhdr does not apply same header/footer on chapter and non-chapter pages Meaning of "kernel" In analysis, there are at least three kinds of "" concepts:   In probability theory, there is a concept called , also called probability kernel, from one measure space $X$ to another $Y$. It is actually a family of measures on $Y$, indexed by members of $X$. It can transform a measure on $X$ to a measure on $Y$, in terms of integration.  A special case is  of probability density function in statistics, where the  is actually a probability kernel. In real/complex analysis, there is a concept called  from a product space $X \times Y$ to $\mathbb{R}$ or $\mathbb{C}$. It can transform some special function: $X \to \mathbb{R}$ or $\mathbb{C}$ to another one:$Y \to \mathbb{R}$ or $\mathbb{C}$. This is used for defining integral transformation In Hilbert space theory, there is concept called , which is a family of bounded mappings for a family of Hilbert spaces. For every two Hilbert spaces $X$ and $Y$ in the family, there are exactly two members of the kernel, one mapping from $X$ to $Y$ and the other from $Y$ to $X$.   I wonder    Are they related concepts, since they seem to share some indescribable similarity? Can they be unified?   In particular, the first two are similar to each other as the kernels induce transformations on measures and on functions in terms of integrals.  It is however not obvious to me how the third one, i.e. the Hilbert space one, is related to the second one. Are they related to the  concepts? Or even to the  concept?   I feel like some insights and references for catching the general ideas shared across as many kinds of "kernels" as possible.  Thanks and regards! How to use aes-encryption in PostgreSQL? I tried aes-encryption by using following statement:  SELECT encrypt('test', 'key', 'aes');   which worked, but I am not able to decrypt the value. I inserted it in a field of datatype bytea but I'm not sure if that was the right way.   SELECT decrypt(pw, 'key', 'aes') FROM table WHERE ID = 1;   gives me the error     ERROR:  function decrypt(bytea, unknown, unknown) does not exist   LINE 1: SELECT decrypt(pw, 'key', 'aes') FROM tabelle WHERE ID = 7;                  ^   HINT:  No function matches the given name and argument types. You might need to add explicit type casts.   Does that really mean that encrypt() is an existing function, but not decrypt()? How else could I retreive aes-encrypted values? What's the meaning "them" here? What kind of material is the Robert Downey Jr. Iron Man's armor supposed to be made from? I know he crafted the prototype from the things he had on hand, but once he was able to build the next one(s) in his own lab, what hi-tech material did he use for the movie armor? My Tier 5 YMS visa is set to start on September 30th, 2016 however, I want to get there earlier.  Can I enter the UK as a tourist, if I explain to border control/immigration that I am entering as a tourist and do not plan to work or do anything really until my Tier 5 visa starts?  I can find no official contact or information source on this with UK Visas Information, the British High Commission, etc. How to create a "heat distortion" effect with a cycles procedural node set up without compositing I know how to do a heat distortion effect in compositing.   What I am looking for is a way to do the same effect with a material set up in cycles.   What would be the best way to create a procedural material that can be placed in front of any object and make it look like heat is rising in front of it (without compositing)?  Any ideas would be greatly appreciated. Do I cast the result of malloc? In , someone suggested in a  that I should not cast the result of malloc. i.e., I should do this: int *sieve = malloc(sizeof(int) * length);  rather than: int *sieve = (int *) malloc(sizeof(int) * length);  Why would this be the case? What is the white smoke-like fog called? It's not really fog, mist or haze. I used to think that it's mist, but from what I've read here, it turns out that it isn't.  It's the white smoke-like fog that is close to the ground. I've seen it recently above a couple of small ponds (and ground) in a damp forest. It was almost as white as smoke, you can barely see through it, but it is close to the ground, from 20cm to a meter or so.  Since it isn't fog (which is a cloud that you can see, say from a mountaintop, and if it's not mist (which is more like 'rain'), then what is it? This question is prompted by:  and .  Basically, some diamond moderators don't always want to diamond-hammer close questions.  A workaround is to create a new account, , then cast regular close votes from that account.  Question: May a diamond moderator utilize a second, non-diamond account e.g. to cast regular close votes?     It is not a problem to have multiple accounts, as long as they aren't voting for each other and doing other sockpuppet-y things.      I worry this might be considered "sockpuppet-y".  The diamond close hammer is sometimes excessive, particularly  where moderators are . Statistics module doesn't show the "Enable access log" checkbox I dont know what to do to show "Enable access log" option.  I activated logging all messages and checked all statistics permissions.  Thanks. As teenager Tom Riddle is speaking to Harry Potter in the Chamber of Secrets, both he and Harry are refering to the real Voldemort in the third person. If Tom Riddle had succeeded in sucking all the life energy out of Ginny and had come back alive, wouldn't that have meant there were two Voldemorts in the world? The wraith one which had lived in Quirrell, and the newly constituted one?  This Tom Riddle clearly doesn't have the memories of the wraith version.   As a bonus: If they both existed, would they have competed against each other? How to append something to an array? How can we disable triggers, Validation Rules and workflow rules in salesforce org. [on off - switch] How can we disable triggers, Validation Rules and workflow rules in salesforce org.  This becomes really needed and important when we are doing data migration(data imports) in salesforce.  The way I handled this is create a custom label and include it in workflow and validation rule logic.   example - Custom label 'Disable workflow' = True then do not fire workflows.            if its False then fire workflow  But wanted to understand if there is any more efficient way to handle these scenarios. Polynomial rings in infinitely indeterminants How can we prove that (the set of all polynomials in infinitely non commutative indeterminants over $k$) is a ring, where $k$ is a ring with unity?   Adding two polynomials is a polynomial, but for commutativity  How can we show the following: $ax_1+bx_2=bx_2+ax_1$ (commutativity of addition) If we have finite number of variable it is easy to prove it, (we take the $n-1$ variables...), but what about the infinite number of variables?  Can someone give me a hint? population and subsamples : mean equality? I want to perform a two sample test, to see whether theirs means are equals. One of the sample is rather big (#60000 values) and represents the scores of a whole population. This population is partitioned in small classes of less that 1000 people. The other sample of the test is a subsamble of the former. It corresponds to people of the same class. So, each time, there is less than 1000 values in it. I have no idea about the variances, so I'd think of using Welch's t-test.  But I'm concerned regarding the independence hypothesis: can it be valid, considering that the second sample is negligible when compared to the overall population? Don't include SE site in SE search filter? I couldn't find this question here, but I would like to be able to search all sites in the SE network except some sites. In my case, I want to remove the thousands of results from SO on a popular project for devs so I can see the handful of results on other sites from admins and users.  The current form only allows all sites or listed sites.  The answer linked does not tell me how to use the information in the answer. It is a poor answer for an average user.  As @Laurel describes in the comment below, the answer at  no longer works. Can a mangaka continue another mangaka's manga? There are plenty of manga that never had an ending for many reasons. For example, High School of the Dead's mangaka, Daisuke Satou, . Some mangaka also cannot continue their work because of health problems, as well as other reasons. Say the original mangaka either prepared or did not prepare an ending himself/herself, can another mangaka continue their work? Has this ever happened before?