After Effects Circular Image Repeater

Question: Hi I'm trying to create something like this with motion in after effects but I'm unable to find a way to do so. (basically what exists with the shape layer but for images) Any ideas?
Comment: It might be helpful to tell us what kind of motion why want to add. Also, are you asking if things can be duplicated around in a circle? Including a screenshot of what you have now could be helpful as well.
Answer: You definitely need the plug-in from Red Giant Trapcode Echospace, I don't know if it's enough for your project but for sure it will help you to make most of the work.
Answer: As mentioned by Necrodeathify, Trapcode Echospace is the best option for this.
However, If you're on a tight budget and cannot afford Trapcode Echospace, CC Kaleida will help achieve looks that are similar to your examples. Add the effect to your footage layer and play around with Mirroring, Rotation, Center and Size.

Effect > Stylize > CC Kaleida

Hope this helps!
Answer: Without having to use plugins, here's how I would do it.

set the anchor point on the layer you want to repeat so that it's in the right spot (using the pan behind tool y)
add this expression to the rotation property (assuming that the comp only contains the kaleidoscope layers. Precomp if you need to): index/thisComp.numLayers * 360
duplicate the layer as many times as you want.

If your comp has other layers in it you'll need to adjust the expression. If there are, say three other layers below the kaleidoscope layer you'd use index/(thisComp.numLayers-3) * 360, and if there was, say two layers above the kaleidoscope layers and five below you'd use (index-2)/(thisComp.numLayers-7) * 360.
You could also link the anchor points of the layers with an expression, so that you can adjust the centre of all the layers. This allows for easy animation of the whole effect. Do that by using this expression on the anchor point property of all but the first kaleidoscope layer:
thisComp.layer('name of kaleidoscope layer 1').transform.anchorPoint
Rather than typing this it's easier to use the pick-whip.

alt-click on the stop watch to create an expression, then grab the thing that looks like a fire-hose-reel and drag it to the anchor point property of the first kaleidoscope layer. This will fill in the correct path to the property, without you having to type.
Answer: The Spoke script provides a radial layer repeater in After Effects → https://madebyloop.co.uk/products/spoke-radial-layer-repeater-after-effects/

After Effects Circular Image Repeater


How is scalability of walletnotify of the full node wallet

Question: I'm thinking about how large exchanges handles customer deposits, it appears there are two available solutions, one is to use external notification apis, like blockchain.info 's notification api, another is run a full node and use the walletnotify feature. Since the first approach brings dependency to an third party service, also, it does not support testnet notification, which we use during development, so I'm trying to run a full node. My question is how scalable is it? Suppose there are 10,000 users, and platform must support add more addresses for a user, say in average each user generate 10 addresses, that's 100,000 address to watch. If I add those 100,000 address as watch only to the full node and enables walletnotify, is that a good way to handle it? Will there be any technical issues?
Answer: Using walletnotify has proven to work and is used by a lot of scalable apps today. I would not rely on it completely though. walletnotify's job is to execute a shell command every time it receives a wallet transaction. This means data is flowing between processes, which does not make me entirely comfortable as a developer. After all, it only takes one error for someone to be missing their funds.
I would recommend not only using walletnotify, but to also check X blocks after Y minutes. You can keep track of blocks passed and if any transactions were not processed by walletnotify, your cronjob of checking transactions will recover the transaction. You can use listsinceblock RPC command and keep track of the block height each time you check transactions. You could store transactions processed in a DB somewhere.
After all, this is a financial application so I think a backup check is vital.
Answer: Probably there's no technical problems and its highly depending on your server.
if your server is having no issues so nothing to worry about.
I have tried to send 1000 request to bitcoin-core server in the same time with a basic server and everything is worked great.
Also you can get like more than one bitcoin core server and deal the requests to these servers.
Comment: I think wallet notification is different than sending rpc requests, also 1000 is in a different scale factor than 100,000, but if you really handled a bitcoin platform like ecommerce site e.g. an amazon like site or a cryptocurrency exchange I'd trust your answer.
Comment: No, it's not different, RPC meaning Remote_procedure_call so its just passing the request to your app.
so sending commands through RPC is the same.

You could try with like 2000 address and see what will happen.
Answer: Since the time taken to process a given request will be greater than zero milliseconds, there will come a point where enough requests will result in the CPU reaching 100% utilisation, or you might hit I/O or network bounds first, but in whatever case when you find a bottleneck what you will need to do is split the workload up among multiple machines using some sort of load balancing schema.


Quotient topology of $[0,1]$

Question: Is it possible to define an equivalence relation $\sim$ on $[0,1]$ in such a way that $[0,1]/\sim$ is not second countable?
Comment: What is the topology of $[0, 1]$? Is it the standard topology or something you can choose?
Comment: @AymanHourieh The subspace topology of the real line with the topology induced by the metric.
Answer: For $x,y\in[0,1]$ let $x\sim y$ iff $x=y$ or $x,y\in\Bbb Q$, and let $X=[0,1]/\sim$; $X$ is the result of identifying $\Bbb Q\cap[0,1]$ to a point. Let $p$ be the point of $X$ corresponding to the $\sim$-equivalence class $\Bbb Q$, and let $q:[0,1]\to X$ be the quotient map. A set $U\subseteq X$ is an open nbhd of $p$ iff $q^{-1}[U]$ is an open nbhd of $\Bbb Q\cap[0,1]$ in $[0,1]$, which is the case if and only if $[0,1]\setminus q^{-1}[U]$ is a closed subset of $[0,1]\setminus\Bbb Q$.
If $X$ has a countable local base at $p$, there is a countable family $\mathscr{F}=\{F_n:n\in\Bbb N\}$ of closed subsets of $[0,1]\setminus\Bbb Q$ such that if $H$ is any closed subset of $[0,1]\setminus\Bbb Q$, there is an $n\in\Bbb N$ such that $H\subseteq F_n$. (Just take the complements in $[0,1]$ of the sets $q^{-1}[U]$ with $U$ in the countable local base at $p$.) Thus, to show that $X$ has no countable local base at $p$, we need only show that if $\mathscr{F}=\{F_n:n\in\Bbb N\}$ is any countable family of closed subsets of $[0,1]\setminus\Bbb Q$, there is a closed subset $H$ of $[0,1]\setminus\Bbb Q$ such that $H\setminus F_n\ne\varnothing$ for each $n\in\Bbb N$.
Each $F_n$ is closed in $[0,1]$ and disjoint from $\Bbb Q$, so each $F_n$ is a closed, nowhere dense subset of $[0,1]$. $[0,1]$ is a compact Hausdorff space, so by the Baire category theorem it is not the union of countably many closed, nowhere dense subsets. We can therefore choose an irrational $x\in[0,1]\setminus\bigcup\mathscr{F}$ and let $H=\{x\}$; clearly $H\setminus F_n=H\ne\varnothing$ for each $n\in\Bbb N$, as desired.
Answer: Yes.
Consider the equivalence relation $\sim$ obtained by identifying all points of the form $\frac{1}{n}$ (and being just equality on the rest of the unit interval).  Denoting by $*$ the equivalence class of the reciprocals of the natural numbers in $[0,1]/\sim$, I claim that there is no countable basis at $*$.  Note that open neighbourhoods of $*$ essentially look like $$\{ * \} \cup \bigcup_{n=1}^\infty \left( ( \tfrac{1}{n} - \epsilon_n , \tfrac 1n ) \cup ( \tfrac 1n , \tfrac 1n + \epsilon_n ) \right)$$ where $0 < \epsilon_n \leq \frac{1}{n(n+1)}$.  If $\{ V_m \}_{m=1}^\infty$ is any countable collection of such open neighbourhoods, say $$V_m = \{ * \} \cup \bigcup_{n=1}^\infty \left( ( \tfrac{1}{n} - \epsilon_{m,n} , \tfrac 1n ) \cup ( \tfrac 1n , \tfrac 1n + \epsilon_{m,n} ) \right)$$ for each $m$, consider $$U = \{ * \} \cup \bigcup_{n=1}^\infty \left( ( \tfrac{1}{n} - \tfrac{\epsilon_{n,n}}2 , \tfrac 1n ) \cup ( \tfrac 1n , \tfrac 1n + \tfrac{\epsilon_{n,n}}2 ) \right).$$  This is clearly an open neighbourhood of $*$, but $V_m \not\subseteq U$ for all $m$ (meaning that the $\{ V_m \}_{m=1}^\infty$ is not a local base at $*$).  (Note that this shows that $[0,1]/\sim$ is not first-countable.)

Quotient topology of $[0,1]$


Entity Resolution

Question: I ask this question to people in the field of scientific research: I want to know the difference between the two terms "Entity Resolution" and'' Entity matching "in the context of databases.
or if it means the same thing?
Answer: Entity resolution, entity matching, record linkage, duplicate detection, relational clustering, coreference resolution, reference reconciliation, database hardening, entity disambiguation, merge/purge or record matching describe quite similar research problems: the process of identifying groups of records that refer to the same real-world entity. Different research and application areas favour different terms.
However, as far as I can decide, there is a slight difference between resolution and matching.  Entity matching is usually used to describe matching of record/entity pairs, deciding if they refer to the same thing only looking at the given pair. Entity resolution, on the other hand, describes the process of deducing all matchings; eg. if we know that records r1 matches r2 and r2 matches r3, then the whole entity contains r1, r2, r3, including r1 matching r3.
In the context of databases, entity matching is closer to similarity joins between records, while entity resolution is closer to an iterative process of repeated similarity joins.

Entity Resolution


A group that has a $\frac{3}{2}$-transitive subgroup

Question: Do you know a group that has a $\frac{3}{2}$-transitive subgroup and it is not  $\frac{3}{2}$-transitive itself?
Answer: I found this group using GAP.
Let
$$ \begin{align*}
a &= (29)(36)(48)(57)\\
b &= (136)(247)(589) \\
c &= (192)(354)(687).
\end{align*}$$
And let $H=\langle a,b,c\rangle$.  This is a $\frac{3}{2}$-transitive subgroup of $S_9$ (it is a Frobenius group, with kernel $\langle b,c\rangle$). It is contained in a larger group $G$, generated by $H$ and the two elements
$$ \begin{align*}
d &= (129) \\
e &= (12)(45)(78).
\end{align*}$$
This group, just like $H$, is transitive.  But the point stabilizer of $1$ only permutes $2$ and $9$ amongst themselves, while transitively moving the other $6$ points amongst themselves.  In other words, it is not $\frac{3}{2}$-transitive.
To clarify my search, I simply looked for transitive, but not primitive, subgroups of a symmetric group (I chose $S_9$ because neither $9$ nor $9-1$ is prime). I then looked in those groups for subgroups that were Frobenius (as all $\frac{3}{2}$-transitive groups are either Frobenius or primitive).
Comment: Magic $9$. $S_9$ was chosen cleverly. +1


Stream cipher -- Are all random bit generators suitable for stream cipher?

Question: I learned the stream cipher using LFSR in the book. I wonder whether all random bit generators (i.e. BBS, Rabin generator) are suitable for stream cipher. I search using keywords "stream cipher" and "BBS", and there are few results.
Comment: FYI, BBS is a theoretical toy, not actually fit for use in any practical application.  You can get orders of magnitude better performance at higher security from something like ChaCha instead.  It may be tempting to say that BBS is based on a known hard problem, but actually either way you are relying on an unproven conjecture—BBS just relies on a hard problem that is _much easier_ than the hard problem of ChaCha, because it is highly structured and already known to admit powerful attacks like ECM and NFS.
Comment: No, because some RNG:s have requirements incompatible with stream ciphers. The primary requirement of a stream cipher is that it is indistinguishable from random, but some RNG:s are expected to produce numbers within certain ranges or with chosen patterns or to prohibit repetition, etc. In these cases, even if they have sufficient randomness, their outputs could not be securely used for a stream cipher without some form of "whitening", another algorithm to scramble the output to hide the patterns.
Answer: The requirements for cryptographically secure pseudo random number generator and those for a stream cipher are essentially the same.
Obvious not all PRNG are secure, LFSR and mersenne-twister to name a few aren't suitable for any cryptographic task.
In some cases a PRNG will be not practical for use as a cipher. If you look at it in the pure form of a seed generating a stream of random bits than we are OK, random bits are random and knowing some won't help me know the others. But if you look at the full system, PRNGs require some entropy collection and this can make it unpractical when you want to make it a keyed cipher, some PRNGs may for instance have a huge seed which you will not want to use as a key.


Can a cream cheese cake be left out and for how long?

Question: I have an awesome cream cheese and blueberry pound cake recipe that I love to bake. Can it be left on the counter and for how long?
Answer: If you have a true pound cake, it should be good at room temperature for 2-3 days, well wrapped.

The title of your question made it sound like you have a cheese cake, perhaps with a pound cake base.  If that is the case:
Cheesecake is essentially a custard of cream cheese, eggs, and dairy.
None of these foods should normally be left at room temperature for an extended period of time, as they are all quite perishable.
I would recommend leaving a cheesecake out for no more than 2 hours or so, the same as any other perishable food.
See also:  How do I know if food left at room temperature is still safe to eat?
Comment: It's a cream cheese *pound cake* (http://www.marthastewart.com/315556/cream-cheese-pound-cakes), not a cheesecake.
Comment: A lot of cheesecakes have pound cake cases...  but will update.
Answer: Pound cake is good for a day or two on the counter, a week or so in the fridge, and indefinitely in the freezer...they freeze really well due to their high density. The addition of cream cheese doesn't make a notable difference in texture, though if you're using a frosting that will change things.
I tend to make mine in job lots, and freeze them...Stick 'em in a freezer bag, press out the air, and you're good to go. Best to eat it inside a couple of months, or it'll dry out a bit.


What's the difference between "untersuchen" and "analysieren"?

Question: What is the difference between analysieren and untersuchen?

Ich untersuche den Fall Nicole Smith.
Ich analysiere den Fall Nicole Smith.
Answer: Analysieren means a methodical inspection/investigation: an analysis. Untersuchen is a broader, more general term and means looking into an issue.
An Untersuchung can well lead to findings and results that will then have to be analysiert, of course.
Answer: Depending on context both "analysieren", and "untersuchen" may be used as synonyms but this is by far not always the case.
To get a grasp of the subtle differences in meaning and usage it helps to look at the etymology of "Analyse":

"resolution of anything complex into simple elements" (opposite of synthesis), from Medieval Latin analysis (15c.), from Greek ἀνάλυσις "a breaking up, a loosening, releasing," Online Etymology Dictionary

This implies that whenever we look at dissected details of anything on examination  ("Untersuchung") we may use the verb "analysieren".
This usage is the same in German than in English and can e.g. be the case of a laboratory analysis, a forensic analysis, or other any other analysis of single aspects. Then we may use both, "untersuchen", or "analysieren", but we do not use "analysieren" in the case where we look at something as a whole.
Answer: I think there is only a subtle difference in that "analysieren" tends to be usable only when mainly mental work is done.
It would sound funny if you say:
Ich analysiere das defekte Getriebe.

Also, use:
Der Doktor untersuchte mich. Er nahm mir Blut ab, das im Labor analysiert wurde.

But in your case, you can use both forms.
If you are unsure, prefer "untersuchen", it is always valid, while "analysieren" is not.
Comment: "untersuchen" is the only valid word when you're seeing your doctor. In (pretty most) other cases both words are equally valid but sometimes *untersuchen* sounds better and sometimes *analysieren*. In respect to OPs question *untersuchen* is the word we're looking for.
Answer: They're both the same, semantically. At least, I'd be hard pressed to find examples where you couldn't technically use one for the other.
The difference is that »untersuchen« is easily understood by anybody whereas »analysieren« is Greek and so sounds more "scientific" and "important" and may not be understood by all children.
I think the best translation for »untersuchen« is »investigate«, and literally »underseek« (never seen that in English, but there's »onderzoeken« in Dutch). So it's seek and search, if boiled down to simple verbs.
»Analyze«, on the other hand, is »dissolve« in Latin (and English), and the proper German translation is »auflösen«, like »Zucker in Wasser auflösen« oder »ein Geheimnis/Rätsel/Mysterium auflösen« (oder auch »lösen«).
So, »untersuchen« is more down-to-earch, and »analysieren« is more like in a chemical lab, if you look at what kind of attitude the word conveys.
Regarding your example: »einen Fall untersuchen« is better, no question about it. Einen Fall untersuchen. Eine Probe untersuchen (Bodenprobe, Gewebeprobe, Blutprobe).
Answer: "Untersuchen" refers to gathering information relative to the case, or Fall.
"Analysieren" refers to making sense out of the information you have gathered, or "untersucht."
The two are complementary.
Answer: There is no general answer to this question. It always depends on the context.
Both words can describe an action very specifically:

Wir untersuchen die Funktion f(x)=sin(x).
Wir analysieren das Gedicht.

Both words can describe an action in a broad sense:

Wir untersuchen die Gründe für den Wahlsieg der CDU.
Wir analysieren die Gründe für den Wahlsieg der CDU.

Sometimes, both words are (a little bit) different: first pair of examples. Sometimes, both words are synonymous with different connotation: second pair of examples.
Sometimes, both words are exactly synonymous:

Wir untersuchen das Spurenmaterial des Täters.
Wir analysieren das Spurenmaterial des Täters.

Sometimes, only one of the two words can be used.

Der Doktor untersucht den Patienten.
Comment: Und doch seh ich einen Unterschied beim Spurenmaterial. "Untersuchen" suggeriert mir, dass die Sachen vor allen Dingen betrachtet werden, bei "analysieren" denke ich an ein Labor und chemische Analyse.
Comment: @Em1 Zeig mir den Forensiker, der Spurenmaterial lediglich von außen betrachtet. Wenn der `untersuchen` sagt, meint er genau dasselbe wie `analysieren`.


Does evolution only give rise to traits that confer fitness?

Question: Does evolution only give rise to traits that confer fitness? In other words, does the existence of a trait imply it's conferring of fitness? If not, what are some counter examples?
Comment: I think there's a very important sense in which your question is exactly backwards.  "Fitness" is not really something that is a priori measurable.  Instead, it's measured by an organism surviving to pass on its genes to future generations.  So everything which lives to reproduce is, by definition, "fit".
Answer: I'll try to beat @Remi.b to the suggestion that you review Understanding Evolution as a general overview of evolutionary topics.
For a quick answer: no.
Sometimes people confuse the great importance of natural selection in evolution with an equivalency between natural selection and evolution. However, there are many many contributors to evolution, many of which do not involve fitness.
I'll list just a couple examples:
Genetic drift is random change in allele frequency because of random sampling of reproductive organisms.
Founder effect is a somewhat related concept, referring to the change in allele frequency in a population that becomes isolated from the rest of the individuals of a species: that population has a selection of traits that might differ from the species as a whole, and lead to future speciation.
There are many more.
Answer: Rephrasing the question

Does evolution only give rise to traits that confer fitness?

The phrasing is actually a little nonsensical, but it is easy to understand what you mean. The reason is that "fitness" is not a characteristic of individuals but a measure (a variable if you wish) of a characteristic. Imagine you are talking about Shaquille O'Neal and you say "He is height!" instead of "He is tall!". Allow me to rephrase the question correctly. Note that because "high fitness" is a statement relative to the fitness of the others (just like being tall is relative to the average height), I highlighted in my rephrasing of the question this relativity.

Does evolution only give rise to trait variants that are associated with higher fitness than other variants?

Short answer
No!
Examples
Very simple examples include all the genetic diseases.
Reasons
In short, evolution is much more than natural selection. All of the following are reasons for why there are low fitness variants in nature.

genetic drift (incl. bottleneck or founder effect),
spatial variation in the environment and gene flow (hence migration load)
changing environment (incl. the biotic environment and the social environment) and non-equilibrium conditions in general
local peaks in fitness (and the concept of pseudo-species; fitness landscape)
trade-offs
genomic conflicts

and many others...
For more information on the "why" part of the question, you should start with an intro course to evolutionary biology such as Understanding Evolution by UC Berkeley for example.
Comment: I saw you posted this as I was typing my own answer; since I already had the bit about beating @Remi.b in my answer I decided to submit it even though it's basically identical to yours.
Comment: Thanks, the counter example of genetic diseases is brilliant.
Comment: Just a follow up question: why was my phrasing incorrect, i.e. what is the difference between "trait variants that are associated with higher fitness than other variants" than "traits that confer fitness"? Thank you!
Comment: @HuiWang Good follow-up question. I edited my post to add more info. Let me know if this clear things up for you.


MSCRM 2011 SiteMinder ADFS

Question: I am new to MSCRM trying to adopt its security model and integrate with our existing applications. Need a clear understanding with respect to integration between MSCRM system and our existing applications.
Our current application is uses SiteMinder for authentication, business need is to integrate MSCRM from this application without login challenge again. After going through the claim based authenticaiton, ADFS 2.0, ADFS with SiteMinder documentation, some basic questions,
--> can MSCRM work if federated with ADFS SiteMinder ?
--> If so, how the user setup will work in MSCRM ?
Can any body done these MSCRM - ADFS - SiteMinder integration ? i could find the disjoint documentation ADFS - Siteminder, MSCRM - ADFS, but not so sure if relying application (MSCRM) will work with SiteMinder tokens.
Any suggestions appretiated.
Answer: The big question would be if what SAML Defaults your Siteminder is providing.
Setup would be simliar to ADFS 2.0 install the certificate from siteminder on the CRM Server to make him beable to proof the token and tell CRM where it can download the federationmetadata file from siteminder.

MSCRM 2011 SiteMinder ADFS


Many Snow Leopard Server Managed Preference settings do not take effect

Question: I am managing 20 or so Apple computers running 10.6.4 with a Mac Mini Snow Leopard Server (also 10.6.4). I am using the built-in OpenDirectory in addition to Kerberos to bind the clients to the server. Users have networked homefolders (stored on the server) that they can access by logging into any of the computers (much like a lab environment). Using the Workgroup Manager utility I have been applying Managed Preferences to the machines. Many of the preferences work, I can get the dock on the left, auto-create the logged in user's iChat account and auth via Kerberos, etc. However, it has been increasingly apparent that many of the settings just do not work. None of the settings under Media Access not work at all, though mcxquery shows them as being enabled. Additionally, Bluetooth disabling, auto-importing iCal accounts, and providing a predefined set of Safari bookmarks all do not take effect even though, as before, mcxquery shows what I would expect to see with the settings enabled. I've stumbled over a number of forum posts with problems similar to what I am experiencing, all without resolution. Any insight is appreciated.
Comment: If, logged in as the user in question, you go to System Profiler and choose "Managed Client" under Software, do you see the settings you expect, as via mcxquery?
Comment: Yes.Managed client shows the same settings as mcxquery.
Answer: If this is at a school, give Apple support a call.  They offer free support to public schools in the US at 800-800-2775.  When asked for the product that you're calling about, say "XServe" or "Mac OS X Server" to get to the department that you want.
Answer: I don't know if you're still trying to solve this or not, but a thought just hit me.
Some MCX settings can be overridden.  For example, if you turn something on at the workgroup level and turn it off at the computer or user level, it will then therefore be off.
Also, there is a "guest computer account" which can have settings applied to it.  Any computers not specifically listed under the "Computers" tab will have these settings instead.
I don't think that these issues are happening in your case, as you have the data in mcxquery telling you that the MCX settings are active.  However, pointing this out may help you make some connection that neither of us made before now.
Good luck.


Why do parsing HTML with regex questions come up so often?

Question: I mean is it really such a common desire/requirement? Or is someone out there trolling SO on a huge scale?
Comment: @badp The NPR login page? Does SO automatically rewrite SE beta links if you don't have access to them?
Comment: @Josh: http://stackmobile.com/site.php?site=programmers.stackexchange
Comment: [Related](http://programmers.stackexchange.com/)
Comment: @Michael - yes (my fault for copy pasting the rewritten link).
Comment: @badp now that's just cruel to those of us who weren't invited!
Comment: @Josh, I didn't [commit to the (public) proposal](http://area51.stackexchange.com/proposals/3352/not-programming-related) either :)
Comment: There must be some kind of conspiracy going on...
Comment: `Or is someone out there trolling SO on a huge scale?` Is ***this*** a trolling question?
Answer: Wanting to parse HTML is common.  People think it should be easy.  And they know a little bit about RegEx.  And it just seems like the perfect fit because they've used it for smaller input.  Regular languages isn't in their vocabulary.  They don't understand what that means.  They just know that HTML is a language, so clearly it should work!
Comment: You're incorrectly assuming people try to solve their own problems before asking someone else.  They pop up so often because parsing HTML is common.  It's that simple.  There are a ton of questions across the wide spectrum of SE sites that could *just* be answered by searching.
Comment: This doesn't explain why they pop up so damn often. I mean every single one of these people has failed to Google [parse html regex](http://www.google.com/search?client=ubuntu&channel=fs&q=parse+html+regex&ie=utf-8&oe=utf-8) and read the first result...
Answer: Because when a developer first starts to figure out the power of Regular Expressions, they can get a little over excited. I certainly went through a phase where I wanted to write my own parsers for everything.
But I think "why do they come up so often" isn't as important as "what should we do about them."
A comment made by @bgould on the question Big Regular expression help struck a chord with me:

He's not asking for a diatribe on why he shouldn't.

A lot of these questions are directed to the ever-popular RegEx match open tags except XHTML self-contained tags but that question-answer isn't useful to an OP because it's more of a cultural phenomenon than an answer. I'm not saying there isn't useful information there; I'm saying that most OPs directed that way - who are new enough to not know that they shouldn't parse (X)HTML with RegEx - won't see the answer through the fun and the horror. Then they don't get the answer they should get and that affects SO's raison d'être.
Additionally, those users who find that question while checking if their question would be a duplicate may just ask again if they don't understand it, or it doesn't offer as concise an answer as they need.
So I think we need to answer these questions or find a better answer to direct them to, which focuses on communicating the point as opposed to the use of poetry and Unicode.
Comment: Great answer.  The only thing more tiresome than the question coming up repeatedly are the knee-jerk "don't ever try to do that" answers that get posted as a result.  There are plenty of simple things you can parse out of HTML with regular expressions, and that's often all anyone is trying to do.  Automatically linking to @bobince's answer just shows that people either aren't reading the question, or they don't really understand the issue to begin with.
Comment: The worst thing about that question is that there is no useful information for the user, at least not without digging through it.  All the poor user sees is a wall of text that makes no sense whatsoever.  That answer is only funny to those of us who understand why HTML parsing with regexes is hard.
Comment: Mental note: start a band and call it "Poetry and Unicode"
Comment: @Bill the Lizard - Well, I still agree that one shouldn't ever try to do that, but it merits better justification than is provided by most users.
Comment: @BilltheLizard There seems to be no way to get people to stop linking to bobince's amusing but hopelessly unhelpful answer, since locking doesn't block that. And we'd need dev help to even delete it, since it has all those dupes now. Part of why people uses regexes for HTML snippets is because they use regexes in their text editors for both simple searches and for search-and-replace operations, but this is very rarely pointed out.
Answer: Because processing HTML is a common need, and normally people parse strings using regular expressions, so they naturally try to do the same with HTML. Then they run into problems, for obvious reasons
Answer: Is someone trolling out there on a huge scale? No
However, the most viewed question on stackoverflow is on this topic - with 1.1 million views (8-1-14):
RegEx match open tags except XHTML self-contained tags
Why is this the most viewed question? Well for different reasons.
Wanting to parse HTML is common because if you know a little bit about both, it seems like a good match at first.
That doesn't justify the amount of traffic generated in relation to this topic - I believe the real reason is because of the embellished accepted answer on the top viewed question.
It - like many things on the internet - has taken on a life of its own.
It's become a joke... an internet fad.
I asked my co worker a few weeks ago if I could parse HTML with regex. At first he couldn't tell that I was trolling him - he became very animated and laughed at me - and then continued to tell me how bad of an idea it was.
Has he ever even needed to parse HTML? No - he works primary with python and R.
The point is that people LOVE showing that they know something that others don't - and people also love a spectacle. For some reason this internet fad has an element of both.
Answer: I was going to rant on stackoverflow, but being the better man I chose meta stackoverflow.

Why do parsing HTML with regex questions come up so often?

The answer is because the FUD of being unable to parse html with regex is circulated around by computer science experts/programming noobs all over the internet which leads to such monumental confusion as to causing people to go on stackoverflow and ask for random internet n00b opinions on the subject of the matter even if they know better.
Now I get what they are saying, at least what the computer science experts are saying, in that regular expressions are not a good match for parsing hierarchically structured languages, but when extracting data, most of the time you aren't parsing hierarchical structures, you are indeed matching a repeating pattern in a piece of text with parts that contain your target data.
CSS/Xpath parsing does have its advantages in that it can sometimes be even simpler than regex parsing. I even wrote a sample C++11 web crawler that uses curl to crawl pages while storing sessions and utilizes the beautiful hcxselect library to parse the html pages visited using css.
The whole point of regex is being able to validate a subcategory of domain specific language texts or extract useful information from said texts using subgroups of repetitive patterns. The latter being ubiquitous in data science and API building. [citation not needed for anyone with enough parsing experience]
Seriously, I have no idea why computer scientists are being such nerds and programming noobs are being such bitches on this subject. The longer and more specific your regular expression is, the lower the chance of mis-extracting useful information from hierarchic data, which shows up in your goddamn tests anyway. It's not like you're gonna go "duuh I'm not getting some of the data with regex, it's too complicated for me, uh well, it compiles so ship it".
And don't even get me started on the amount of bugs you can accrue with xpath and css parsing, not to mention what an API change (ie. when a pointy haired boss gets tired of how the company website looks) will do to your neatly hierarchical code which could have been Flat and Maintainable.
And what time have you lost trying to parse your data with regex? Just the time to write those regexes and test them, which, frankly is not that long if you are good at them, are using good test data representative of the real task and are using the correct tools that highlight your matches and show matched regex groups anyway.
So yeah, for many cases you don't need "the html noob pack" or the "nokogiri xpath css matcher" which will give you an exact match for your groups and subgroups of data, you can simply extract it from flat expressions.
So if possible, use a clever regex and match subgroups to extract your goddamn data. And yes, the turkish guy with bajillion-times-upvoted stackoverflow answer is hilarious, but apparently in that post he doesn't appreciate fine vocabulary or thoughtfulness more than creating internet memes.
Comment: Filtering out the rant, there's actually a simple message here and it's "you _can_ parse simple/known-structure/with-limitations html with a regex". It's a message that is chastised because, if handed out indiscriminately, it does not help the OP in the long term when they try to scale up their "extract all .foo links from a page" regex to something a bit less trivial. That said the canonical question doesn't help much either because the top-voted answer surely reads like a mis-formatted "I wonder why I was linked here" mess to novice programmers.
Comment: "the turkish guy with bajillion-times-upvoted stackoverflow answer is hilarious, but apparently in that post he doesn't appreciate fine vocabulary or thoughtfulness more than creating internet memes"

Jelly?
Answer: My honest opinion is that people take what they know about coding (string searching functions, RegEx, etc.) and try to find a way to parse HTML.
It definitely is not recommended, time consuming and HTML is never guaranteed to be valid (tag wise). I would recommend using the HTML agility pack


Can a non-Jewish slave convert and exit slavery this way?

Question: Once entered into slavery, they have a semi-conversion whereupon they must keep a certain set of limited rules. Can they choose to fully convert and then be freed at the appropriate time of Shmita and Yovel?
Comment: An eved kna'ani finishes his conversion by being released. There's nothing else to do but wait.
Comment: is there not tevila leshem shichrur (yebamot 47b) בד"א שלא קבלה עליה אבל קבלה עליה מטבילה ומותר בה מיד ר"ש בן אלעזר אומר אע"פ שלא קבלה עליה כופה ומטבילה     לשם שפחות וחוזר ומטבילה לשם שחרור ומשחררה   this is the view of Rabbi Shim'on Ben El'azar, but it seems that tevila is needed for every opinion
Answer: They might be able to fully convert at the original time. Once they have entered into slavery, however, all the laws of עבד כנעני apply. They cannot escape that status voluntarily.
In any case, no slave regains his freedom at Shmita. All slaves (except a Canaanite) regain their freedom at Yovel, but the only ones whose freedom is bound only to Yovel is (a) the עבד נרצע, a Jewish manservant whose six years (not Shmita!) have expired but chooses to remain by having his ear punctured, and (b) the נמכר לעכום, one who has sold himself to a non-Jew. (Actually, the latter can also buy his freedom, either himself or through a relative.)
Comment: sources would greatly improve this answer


Can I combine multiple Feats if they all require a standard attack?

Question: I have a Ranger with Pinpoint Targeting, Deadly Aim, Focused Shot, and Vital Strike.  Can I make 1 standard attack action and use all of them together?
Comment: [Related](http://rpg.stackexchange.com/q/80152/8610).
Answer: So far as I know, when you take a feat, or any other ability/feature, that requires a specific action, you can't combine other actions that utilize the same action.

Pinpoint Targeting: Standard Action
Focused Shot: Standard Action
Vital Strike: During an Attack Action
Deadly Aim: Before you make an Attack Roll [Like Power Attack]

Thus, you can only choose to either Pinpoint Targeting, Vital Strike or Focused Shot for a Standard Action (Which includes Attack Actions).
You can however use Deadly Aim with any of those, as they are basically added during the rolling, and not tied to an 'Action'
A relevant quote from d20pfsrd.com:

Some combat options (such as using the Cleave feat) are standard actions that allow you to make an attack, but don't count as the attack action. These options can't be combined with other standard actions or options that modify only attack actions (such as Vital Strike). Source: PPC:MTT

Another relevant quote from Paizo.com: (provided by Hey I Can Chan)

Vital Strike: Can I use this with Spring Attack, or on a charge?
No. Vital Strike can only be used as part of an attack action, which is a specific kind of standard action. Spring Attack is a special kind of full-round action that includes the ability to make one melee attack, not one attack action. Charging uses similar language and can also not be used in combination with Vital Strike.
Answer: Pinpoint Targeting, Focused Shot, and Vital Strike typically can't be combined with each other, but any one of those can be combined with Deadly Aim
When a description says that a creature can take a standard action to do something, it means that the creature must take a separate, discrete standard action to do it. The creature can't put a bunch of things in a pile that all take standard actions to use then do them all using the same standard action. (Anyway, the ranger wouldn't want this to work like that: If it did, a wizard could cast all of his spells that have a casting time of 1 standard action in the same 1 standard action, and the ranger would die a lot.)
Anyway, here's a rundown of how these are phrased:

The feat Pinpoint Targeting says, "As a standard action, make a single ranged attack."
The feat Focused Shot says, "As a standard action, you may make an attack with a bow or crossbow and add your Intelligence modifier on the damage roll."
The feat Vital Strike says, "When you use the attack action, you can make one attack at your highest base attack bonus that deals additional damage," and the FAQ says that a creature must take a standard action to realize this feat's benefit.

But, because it has no associated action, the feat Deadly Aim can be combined with pretty much anything if the creature's willing to suffer the penalties.
Comment: @Pethrax What's the difference between casting simultaneously two different spells and, as the question supposes, attacking simultaneously in two different ways?
Comment: I wasn't sure but I had a feeling they had to be separate.  As to the wizard, that comparison doesn't actually line up, because in my case they all say one attack, they just modify that one attack, each spell cast is clearly a different action for each, as they would have different verbal, somatic, and possibly component requirements, unless you are able to speak multiple words at once, have 6 arms, and pouches upon pouches of components.
Answer:
Vital strike
Prerequisites: Base attack bonus +6.
Benefit: When you use the attack action, you can make one attack at
your highest base attack bonus that deals additional damage. Roll the
weapon's damage dice for the attack twice and add the results together
before adding bonuses from Strength, weapon abilities (such as
flaming), precision-based damage, and other damage bonuses. These
extra weapon damage dice are not multiplied on a critical hit, but are
added to the total.

This one works wherever you take the attack action. A specific type of standard action.

Pinpoint Targeting
Prerequisites: Dex 19, Improved Precise Shot, Point-Blank Shot, Precise Shot, base attack bonus +16.
Benefit: As a Prerequisites: Dex 13, base attack bonus +1.
Benefit: As a standard action, make a single ranged attack. The target does not gain any armor, natural armor, or shield bonuses to its Armor Class. You do not gain the benefit of this feat if you move this round.

This one denotes a special action specifically for this feat.

Deadly Aim
Prerequisites: Dex 13, base attack bonus +1.
Benefit: You can choose to take a –1 penalty on all ranged attack rolls to gain a +2 bonus on all ranged damage rolls. When your base attack bonus reaches +4, and every +4 thereafter, the penalty increases by –1 and the bonus to damage increases by +2. You must choose to use this feat before making an attack roll and its effects last until your next turn. The bonus damage does not apply to touch attacks or effects that do not deal hit point damage.

This one works whenever you make a ranged attack.

Focused shot
Benefit: As a standard action, you may make an attack with a bow or crossbow and add your Intelligence modifier on the damage roll. You must be within 30 feet of your target to deal this extra damage. Creatures immune to critical hits and sneak attacks are immune to this extra damage.

This one also is activated as a standard action.
Deadly Aim is the only one that is able to be combined with any of the other feats. Vital strike triggers whenever you make the attack action, so it has the largest potential to be combined. The other two require their own standard actions to activate so they are unable to combine with each other or vital strike.


Video with lower bitrate resulting from joining two video files

Question: I had a 595mb .MP4 video (data rate: 510 kbps, Total bitrate 638 kbps). And I joined it with another .MP4 youtube video with a lower quality(only the end part).. The resulting video file has a data rate of 389kbps and Total bitrate of 517 kbps.. The size is also significantly smaller; 494mb.. I used a program called Video Combiner.. And side by side I can see the original one is better quality looking.. so what am i doing wrong? any suggestions? I just wanna join 2 video files without loss of total quality.
Answer: Your program probably re-encoded the resulting video file from scratch and used whatever setting it considered okay.
If you want to have more control about the process and/or do not want it to re-encode the video at all (if both are of the same format), then I strongly suggest looking into ffmpeg for this.
For reference, https://trac.ffmpeg.org/wiki/Concatenate - the concat demuxer is what you want.
As the most simple example, copy both your video files (let's call them videoA.mp4 and videoB.mp4) into the same folder. Create a videos.txt file with just this content:
file videoA.mp4
file videoB.mp4

Now run ffmpeg with this command:
ffmpeg -f concat -i videos.txt -c copy videoOut.mp4

If all goes well this gives you a new file with both videos in one file, with the original encoding intact.
Comment: thank u ...this is absolutely what i was looking for.. but couldnt express properly to Google..   But ffmpeg is a big program, that can do many things which i will never use.. i dont suppose i would be able to find a smaller program that can do that using a GUI??
Comment: Hmm, maybe try this one https://ffqueue.bruchhaus.dk/Screenshots.aspx
I haven't used it myself but judging from the 9th picture it appears to have the concat functionality built into the GUI.
Comment: ok..       ✌    Thank u


How to discuss about my vacation plan to my future manager without creating any bad impression?

Question: I am from Asia and currently a grad student in USA. Every year I used to take vacation for 3 weeks to 4 weeks between December and January to visit my parents in Asia. As a student it is not a problem as my adviser at school has been fine with my vacation plan. However, I am going to finish my grad studies and going to join a big company (CA, USA) within a couple of months. According to the company's policy, every employee can get 3 weeks "accrued" vacation days per year (monthly 1.5 days). I am going to join the company in August.01.2013. I am planning to take a vacation of 3 weeks from Dec. 15. 2013 to visit my parents. However, by December.15.2013, I would get only one week accrued vacation days. Therefore I would like to discuss this with my future manager. The company already provided the details of my future manager. What are the things I should be careful while discussing my vacation plan with my future manager? Does it create any bad impression on me?
Comment: Related: http://workplace.stackexchange.com/questions/11723/how-do-i-ask-for-a-longer-break-from-my-job?rq=1
Comment: [This](http://workplace.stackexchange.com/a/11481/2322) may be of interest for you.
Comment: You don't state the nature of your new job, but is it possible that you could do your work remotely for some portion of the three weeks?
Comment: Dupe? http://workplace.stackexchange.com/q/1330/325
Answer: The way to avoid creating a bad impression is by being open and honest, and being willing to consider alternatives.  I've had this problem when switching jobs before.  The way that I have handled it is to ask my new manager this question: "I have a vacation scheduled from June 1 through June 20.  How shall we handle this?"  (In this particular case, I already had all of my travel booked, and was willing to start the position after I returned from my holiday.)  Then you have the opportunity to discuss it.  Options can include letting you borrow against future vacation time, working on holidays (Labor Day, Thanksgiving) to bank some time off, or taking some or all of the time off without pay.  You will create a bad impression if you demand that you take off this amount of time, or if you demand that you get paid vacation for all of it, or if you are inflexible about the needs of your company and your project versus your personal desire to take this vacation.  You should also consider what you will do in the worst-case scenario, which is that your manager says that you cannot have any extra time off at all, and thus you will be limited to one week.
Going forward, you might want to reconsider this annual plan.  You're likely to only ever get three weeks of vacation while working in the US, and you need to consider whether you want to use all of it every year to visit your family.  Your original plan worked well when you were in grad school, but might not be appropriate for you as you begin your career.  You might want to take a summer vacation to Europe, which is incompatible with spending all of your vacation time on your annual visit to your family.
Answer: Making the request shouldn't create a bad impression-- managers that deal with employees that have family out of the country are generally accustomed to employees taking longer, less frequent vacations.  As with any request, however, you need to be prepared to compromise or even have your request turned down.  And you'll want to think through the concerns your manager and the company are likely to have.
If you are getting three weeks of vacation as a new graduate in the United States, for example, it is very likely that this is a combination of vacation time, sick leave, and other forms of paid time-off.  If that's the case, your plans would require going two weeks negative in your accrued time off at the beginning of the year which would basically prevent you from taking a sick day for the first year of your employment.  It's pretty unlikely that anyone can guarantee that you won't get sick for a year.  That may make your manager concerned about when you would be able to get back to a 0 balance and whether that will involve you coming in to work when you're sick and infecting everyone else in the group.
The company may also have policies that prevent you from going too far into the negative on your accrued vacation.  They may also have policies about how long a single vacation can be (and three weeks would likely be pushing the envelope).  The company may be willing to let you go a day or two negative.  But going two weeks negative may create issues for HR.  If someone leaves the company with a huge negative balance, that almost certainly creates headaches for the company which is why they generally try to avoid the situation.
Is there something about this year that is particularly special?  If there is a special reason that you want to be home this year, it may be easier for the company to deal with you having a one-time negative vacation balance.  If your intention is to take a long vacation home every year, meaning that you would end up spending the first 8 months of every year getting back to a 0 balance, that is likely to be much more problematic.  Companies are really wary of people that are continuously at a negative balance with no expectation that they'll ever be accruing their vacation time before they use it.
Depending on the type of job, there may also be political considerations.  If, for example, your group is responsible for supporting a production process, it's likely that someone has to be working during the holidays to take care of issues as they come up.  It so, it would be common for things like seniority to come into play where the more senior members of the group get the first choice of holidays and the newer employees have to work the days nobody else wants like Christmas or New Year's Day.  There may also be projects that require work over the holiday period (the end of the year can be a popular time to install new software if that is a relatively slow period for the company.  Or Christmas may be a key period for the company and they may want to minimize the time off people take in the lead-up to that holiday.
Comment: It's not accurate that three weeks of vacation as a new grad is likely to be combination of vacation, sick time, and other forms of paid time off.  For software engineers in Silicon Valley, 3 weeks of vacation is pretty standard, plus 2 weeks of sick time, plus paid days off (New Year's Day, Memorial Day, etc: the number of these days off depend on the company), and perhaps a handful of "personal days".
Comment: @nadyne - I did say "likely", not "certainly".  I don't see anything in the question that indicates that the original poster is a software engineer or that they're going to be in Silicon Valley rather than somewhere else in California.
Comment: Position is software engineer and indeed in Silicon Valley.
Answer: Get used to not having the time you had in the past to take vacations when and of whatever duration you like. That's life as an employee (and as a business owners it's worse, while in theory you can take whatever time off you want in reality you can take hardly any at all).
So rather than than try to get a month off when you've only worked there a quarter, AND don't have anywhere near the hours saved up, AND no doubt haven't yet read the employee rulebook (many companies have limits to the length of vacations), adjust your plans. Either make it a short trip over Christmas, or see if you can invite your parents over to the US (they'll have to fend for themselves while you're at at work, but you'll have the evenings and weekends together still).
Comment: @bharal and what about next year? This is not terrible advice at all.
Comment: @enderland "give up" is generally not considered great advice.
Comment: @Bharal - Not all companies allow for negative vacation time and most companies that do limit the amount you can go negative.  That said I agree that "give up" is not good advice for how to solve the problem.  And just because it worked one time with one company does not mean it will work everytime with every company.
Comment: This answer seems to lack a signifigant understanding of the problem.  I do not think it rises anywhere near the level of expert advice and am not sure it even meets the minimum standards for the Workplace.  Instead of being condecending and saying what the answer is, you should explain why it is that way and how the OP can deal with the situation.
Comment: terrible advice. Just ask to go negative on your accrued vacation.
Comment: @bharal in this case and cases like it, it's the only thing you can do. You have x credits, if you spend more than that you're in debt. Do so long enough and that debt becomes insurmountable. Even worse, the company isn't going to grant him that extension anyway, certainly not on his first few months of employment, and he'll damage what reputation he'll be able to build in that time. In fact, he's likely to find himself out of a job when he tries to get that time off, be told "of course you can take that vacation, just don't come back after".
Comment: "...as a business owners it's worse, while in theory you can take whatever time off you want in reality you can take hardly any at all" - I have heard some business owners say that and observed it to be true for some. I also worked for one who took six to eight weeks of vacation per year, long weekends at least once per month, and played golf about 1/3 of the time they were there - those golf matches were with clients and subordinates, so (he said) it counted as "work".  Meanwhile his workers got one week of vacation under such convoluted rules that they usually lost it.
Comment: well, the solution i gave utterly worked for me in my first job ~ a bank, IT ~ i think i only requested to be 8 days in debt, but there you are. Nobody minded at all... who minds about someone taking vacation? If *that* is the office culture, get out fast
Comment: I told him how he can deal with it: get used to having limited days off. Until his attitude of being able to take time off whenever he wants changes, he'll remain running into situations like this. It's an extra 2 weeks now, next year he'll discover in november he has no time left at all because he used 2 of the 3 weeks he had for that year to buy this year's vacation and took another 2 weeks of various days off, now wants to buy 3 more weeks to visit family, putting him even deeper in the red. And then when he's refused he'll complain how inhuman his HR department is?
Comment: http://en.wikipedia.org/wiki/Straw_man
Comment: "those golf matches were with clients and subordinates, so (he said) it counted as "work"" you worked for Obama? :)
Answer: You didn't mention at which level you are joining your new employer. Also, what does your contract say about such a situation ?

What are the things I should be careful while discussing my vacation plan with my future manager?

Without knowing your contractual obligations to your future employer, there really are only 2 possible out comes. One is that you will be allowed to take your yearly vacation and the payment for the days that you havent accrued will be docked.
Second is to postpone this vacation to next year.
You have to also keep in mind a few other things :
I am assuming you will either be working on your OPT or a work visa. Figure out if you can be allowed to work remotely. This can be proposed at some point in time during your discussion once you know the company policies and the law around your status in US. Also be prepared to not go on your yearly vacation this year. You are not a student any more! If this turns out to be the case, just make sure you know how many of these accrued leaves can be carried over to the next year.

Does it create any bad impression on me?

This may create a bad impression if you are joining at a very low level of the organization chain. In my opinion it would be best for you to not talk about it till you can get a feel for the culture of the organization. Although, as it happened in the case of my work buddy, if you indeed have a situation where you have to go home, then most employers will accommodate by docking your pay. Very important point is to have all this communication in an email so you can explain things to USCIS if situation arises.
Comment: @happybudha: Thank you. My offer letter only "lists" about the 3 weeks accrued vacation per year. Although, I am joining as a senior developer, this is somewhat an entry level as I am just out of the school. Yes, I am on working visa.
Answer: Ugh.
Just tell the employer that you've made plans, and that if possible could there be a work around?
Nobody cares about this stuff - they will either:
a. dock your pay for the excess amount
or:
b. have you accrue negative leave.
Given that it is for your family, you are in the US and not Asia, i don't see how people will mind. But first tell them you already have the plans! Then ask how to go forward!
Comment: I would mind...having non-local family is no reason to have a different set of rules applied.
Comment: ? a different set of rules isn't being applied. It is a work-around, and not uncommon.
Comment: If it is a 'work-around' then that means you are using rules NOT in the handbook...otherwise this wouldnt be an issue.  I'm not saying he can't have some work-around applied...I'm saying I would personally take issue with someone getting rules significantly bent to overcome this particular situation.


is there a safe way to login to my gmail account from a public pc?

Question: Sometimes i need to use a public pc to access my gmail account, is there a safe way to login and keep my password safe in case there was a keylogger or a trojan on that pc? are there tools that could help in that case?
Answer: Enable two factor authentication.  Consider the remembered password compromised to any user of the public computer.
EDIT: My answer dealt with how to prevent your password from being keylogged.  With two-factor authentication your password is now the combination of a randomly generated one-time use code (obtained via cell phone or pre-obtained list) as well as the remembered password; hence a keylogger doesn't give an attacker the ability to log in as you for a future attack.
However, I definitely agree with TomLeek and Nic that in a real-time attack (not a keylogger looked at after the fact) that captures your random session token (that indicates to gmail you are signed in before you do any action), an attacker can fully use your gmail account (send emails as you; search through emails sent to you; delete your emails; etc).  Granted, once you logout your session token will become invalidated and will kick them out of your account.  Granted a clever attacker could write a browser plugin to collect your session tokens, send it to them, and then redirect the logout page to not actually invalidate your token.  Though you could always login to gmail again, view the link for "Last account activity [Details]" and sign everyone else out.
Comment: No, the gmail account is not safe. Using a One Time Password (two-factor) only protects the authentication phase. You are still vulnerable to session hijacking.
Comment: +1 for mentioning password exposure. the gmail account will be safe but the password won't be.
Comment: I'll vote up Dr. Jimbob's response here. I like what he said, I think that there are some other tips, that are of good advice, but the tip provided here is most practical. I would just add that you can keep tabs on your account activity by logging in to your gmail, scrolling to the bottom of your account, to the bottom right there is "Last Account Activity" and a details link, which will show you where you are logged on from and give you the ability to sign out of all other sessions.
Comment: If M has full control of the public PC, M can play the man in the middle and prevent your session from closing. If M needs significant time to incur damage, a temporary password will help. A temporary password is a password that is valid a limited amount of time after first use.
Answer: I access my gmail from my phone, but occasionally need to get to an email from a public computer.  An example would be printing tickets from a hotel business center.
I keep a separate gmail "dropbox" account for this purpose... I just forward the relevant email using my phone to my "dropbox" email account and then access that account from a public computer.

email@example.com = my real gmail acount
email@example.com = my gmail dropbox account

I don't fret about exposing the password for my dropbox email account since its almost always empty.
... But I still use google's 2-factor authentication for my main account.
Answer: Stricto sensu, the only way to keep your private data private while accessing it on a potentially compromised public PC is to pray. If the PC is indeed compromised, then the villain who controls it now knows everything you typed and saw and downloaded and uploaded through that PC, and that includes, of course, your password. You will be safe only if the attacker, through laziness or incompetence, elects not to bother with your account. Gmail's two-step verification, which dr jimbob mentions, will somehow contain the damage in that the stolen password will not be sufficient to easily connect again on Gmail; but for the duration of your session, your Gmail account was nonetheless a free-for-all fair.
Also, if you can use Gmail's two-step verification, then you have a phone -- make that a smartphone and you will be able to access your emails from the phone alone, totally bypassing the PC of dubious cleanliness.
Comment: I do wonder how exposed that leaves you when the smartphone is lost/stolen :).  OTOH, that may be a more well-understood threat (by users as well as service providers).
Answer: Logging into email (or any other service) from a public PC is risky. Of course you need to use strong authentication. But also, you need to consider whether the host is a trustworthy actor. When you authenticate yourself, you are effectively delegating access to the host you're using. Consider these attacks made possible on an untrusted host.

The list of trusted certificate authorities could be modified to allow man-in-the-middle attacks against common websites like gmail.com.
Malware in the browser could intercept your browsing and perform extra actions on your behalf, such as creating mail rules and/or exfiltrating mail messages.

So what can you do about a public PC that can't be trusted? You need to decide which parts of the system you can trust. You can probably trust the CPU and memory in a public PC as much as you can trust your own personal computer. But the operating system and browser are much easier to attack, so you trust them less. Here are some ways to mitigate the common risks.

Install Portable Firefox on a USB drive so you know that the list of certificate authorities has not been tampered with. (Bonus points if the USB drive can be made read-only with a hardware switch).
Bring your own bootable CD-ROM or USB drive with something like a Linux LiveCD or Windows To Go.

And for bonus points, here are some things that developers can do to improve application security.

Allow users to generate single-use passwords for limited access to the service. For example, this could be used for read-only access, or time-limited duration. Basically, use alternate authentication that applies more strict access controls.
Force users to re-authenticate for privileged actions. (Gmail already does this for some actions.)
Comment: good advice, but this mostly doesn't consider hardware keyloggers that can be built into the keyboard or subtly inserted.  And most public PCs probably do not look too kindly to booting up into another OS or running a random program from a thumbdrive.
Answer: There are some inherent risks to consider, even if you can use a one-time password.  Google Accounts is big and important, so there's a risk that Google may be targeted specifically.
I expect that a compromised system could change your GMail settings to forward a copy of every mail you receive from then on.  (As well as reading all your old email while you're logged in there).  It would then be able to gain access to other accounts e.g. facebook (I think), or a blog account.  By using the "forgot my password" feature to request the other account to send a new password to the registered email address.  Which the attacker could then read.
I expect they could even change your GMail settings to define a filter, which deletes the "here is your new password" emails after they've been forwarded, so you wouldn't notice those emails.  (You would only notice when you tried to log in to the other account, your original password didn't work, and you're not able to use the "forgot my password" feature because the "here is your new password" emails are still being filtered).
The "forgot my password" attack is probably not a huge issue.  It's probably going to be spamming, like the facebook/yahoo account hacks that happen, and the pain is more from having to clean up the mess, rather than any significant harm.
Google might mitigate this as well.  E.g. for the more stealthy variant:  If a user changes their forwarding settings while logged in from a new computer/browser (or perhaps even an old one), then the next login on each other computer/browser(s) could tell the user about the forwarding changes.
Comment: +1 Regardless of whether you're using strong authentication, the untrusted host can still act on your behalf.
Answer: If you turn on the 2-step authentication you can use a backup code, which is basically a one time use password.
Answer: If you are using public wifi you may consider VPN like Anonymizer. Refer to this link for more information: http://arstechnica.com/security/2011/01/stay-safe-at-a-public-wi-fi-hotspot/
Comment: Won't help (and hopefully you'll not even e able to install it on  a public PC) if the local computer/browser is compromised.
Answer: My solution to this problem at university where the computers were constantly becoming infected with flash driver viruses and trojans. Was not to use the installed system. When you have put hundreds of hours into your projects you can't take a chance the the computer you are connecting to is just going to corrupt and destroy all that work.
I would carry a boot able live cd / or usb drive of one of the thousands of Linux operating systems. I would boot into a working Linux operating system and do what ever I need to do with out mounting / using the infected / compromised internal hard drive. This limited my exposure to the malware that could potential be found on the internal disks.
You may need to ask for permission to do this at a internet cafe, or library. It should not be that difficult to do. Most live disks give you a web browser, Libra of Open office for reading an writing most office documents. On bootable usb drives you can install software and have it there the next time you boot up.
One of the only post configuration issues I had at university was setting up the network connectivity so I could browse the internet. The university had set up a proxy server that all the computers used to access the internet. You will need to find which of these settings apply to the public computer systems you are trying to access. It would probably be helpful if you use the same public computers systems over and over to save these types of settings in text file on a flash drive that you carry with you. Bootable flash drives give you some control over which settings you want to save to your disk. I currently use the ubuntu 12.04 lts bootable usb drive.
http://www.ubuntu.com/download/help/create-a-usb-stick-on-windows
http://www.ubuntu.com/download/help/create-a-usb-stick-on-mac-osx
http://www.ubuntu.com/download/help/create-a-usb-stick-on-ubuntu
http://en.wikipedia.org/wiki/Live_CD
Answer:
Use Chrome Incognito Window <Ctrl>+<Shift>+N,
or Firefox Private Browsing <Ctrl>+<Shift>+P,
or god forbid you need to use IE InPrivate Browsing <Ctrl>+<Shift>+P,
or Safari Private Browsing Make your own shortcut
etc
Comment: Mmmm, just saw the part about the keylogger, sorry.
Comment: Good (practical) idea, if you bear in mind the caveats on other answers.  For a "sometimes" thing, it might be easier to remember the menu location though.  Rather than keyboard shortcuts, on an unfamiliar browser.
Comment: -1 This is private browsing not safe browsing. Remember that with an extension you can store all kinds of information.
Comment: @RTOSKit private browsing disables extensions for this very reason, at least in Firefox and Chrome
Comment: @sourcejedi absolutely not true! You may have also enabled extensions in private mode. besides that also a baby SK could have a recompiled version of any gecko or webkit open source, and make fake your private environment.


Melting point-general chemistry

Question: This one has stumped me for a few days.  What is the specific name of the general chemistry principle that is responsible for the difference in melting points of pure and impure solids.  I have exhausted all other resources available and a precise principle name eludes me.
Comment: So far as i can remember there isn't a specific name like Charles's Law for gases. It is just known as "melting point depression." https://en.wikipedia.org/wiki/Melting-point_depression
Comment: related http://chemistry.stackexchange.com/questions/30/why-do-impurities-lower-the-melting-point-of-an-isolated-substance
Comment: Eutectic mixtures?
Answer: This is discussed pretty thoroughly in materials engineering textbooks when melting and freezing of (mostly) metals in general is considered. A good reference is Gaskell's "Introduction to thermodynamics of materials". But you will find helpful explnations to fill in the gaps of what uou know by reading up on undercooling in Wikipedia etc. Feezing and melting are related.
And if you read my answer to highest melting point materials, I mention some related issues.
One issue is that you cannot consider materials as "pure" or "impure": a pure material of any amount large enough to test is in practice almost impossible to make. In fact any real world material is impure once you consider a large enough scale: which is on the order of anything bigger than (say) millions of atoms. You cannot actually make a "pure" material of appreciable size, but can only approach it once you get larger than a relatively small size of sample. In addition, a lot of materials have only been made as thin coatings, or as individual small crystals. And their behaviour is not the same as larger amounts of what you might think is the same material. A single crystal behaves very differently from a polycrystalline mass, and the surface of any material is very different from its interior, so a thin film is dominated by surface effects, as are very fine particles.
So you are looking at degrees of impurity, in terms of orders of magnitude. And the general effect of purity level is not linear but more like exponential in terms of its effect on material behaviour.
A related concept is to look at the theoretical strength of a material. From a theoretical point, a pure and defect free material would be incredibly strong, but in practice this is impossible to achieve, you can only approach it.

Melting point-general chemistry


1971 D615MH Coleman Furnace,

Question: I have a Coleman D615MH furnace.  It will not kick off.  I have to turn both breakers off.  I just replaced the thermostat, thinking that was it.  I turned the breakers on & it was still running.  I turned the thermostat off & it continued to run.  So I have turned the breakers off again.  Any ideals on what it is.  The furnace works, so when it reaches the temp I want I just kick the breakers off.  When it gets chilly I turn the breakers back on.  Any help would be appreciated..
Answer: Sounds like a stuck relay or a bad control board at the furnace end; or a short in your thermostat wiring. You could try disconnecting the thermostat wiring at the furnace end. If it still runs with the thermostat disconnected entirely, you're looking at a stuck relay or bad control board.
If it doesn't run with the thermostat disconnected, check for shorts in the thermostat wiring between the furnace and the thermostat. You could do this with a multimeter. If you don't have a multimeter, try removing the thermostat from the wall and connecting the thermostat to the furnace with short length of wire. If the system behaves properly with the short length of wire, then you've isolated the problem to the thermostat wiring between the furnace and the thermostat installation.
Answer: If your system is that old, you probably only have two wires hooked up to the thermostat.  Pull the thermostat from the wall and if it shuts off, then the problem is wiring from the thermostat, or the thermostat itself.  A newer furnace with all new wiring is safer and tons more efficient that old pig you have in basement. It's cheaper now to replace then later.

1971 D615MH Coleman Furnace,


Version settings in Custom list. No Code

Question: I have created custom list and have applied versioning enable but i dont want to maintain change history for all fields, by default version history displays the history for all fields. Is it possible to select fields in order to maintain change history?
Answer: Well, kinda "yes" and "no".
Every field in SharePoint has "ShowInVersionHistory" property. By this property, SharePoint decides the result field set to be shown in list item versions list.
Yes, SharePoint does tracking for all the fields, that's true.
But result set, which is shown in list item versions list.
This property could be changed by Power Shell/c# code. I'm not sure about SharePoint Designer.
Answer: No, it's not.  SharePoint will track all fields in it's version history.


What makes a good mid-lane hero?

Question: Reading various guides and doing my first multiplayer bot games, I've seen that there are champions more suited to mid-laning(usually solo).
What characteristics should have a good mid-laner?
Is their role relevant?(carry, tank...)
Is it better to do the mid lane solo or is it just an option?
Comment: possible duplicate of [Why do some heroes fit some lanes better than others?](http://gaming.stackexchange.com/questions/57862/why-do-some-heroes-fit-some-lanes-better-than-others)
Answer: First of all we need to see the advantages of going mid-lane solo:

Faster XP gain
Easy to gank either top or bottom lane
Easy to get the runes (+bottle efficiency)
Better lane protection (this means the enemy doesn't really have so much space to chase you on lane as they would have top/bottom so it's harder to be killed.)

It is good to go solo mostly because of the faster XP gain which is a huge factor.
Considering the facts listed above, we can follow-up with the 2 following reasons to go mid-lane:

You are a carry hero. Being a carry hero requires fast leveling/farming and the mid lane  offers this to any decent player. If you can't farm that well, still you will level faster anyway.
Now, 80% of cases are in the first category. This means you need a carry oriented hero which preferably can also farm/deny. This means most will be ranged, but there are some good melee heroes too. In what follows I will give some examples of some good range/melee heroes for mid:

Riki is my personal choice, but if you are a beginner do not take him as he is a little hard to manage. Riki is one of the best carries in the game due to high damage and smoke screen which is just imba (imbalanced). You will have difficulties in farming especially if you are up against ranged heroes. Early smoke will help out a lot. Blink/smoke farm will get you easily to lvl 6. Then go gank or keep farming like a boss if your opponent is a noob and doesn't yet have wards.
Shadow Fiend is a great carry, one of the easiest farmers there are in the game, has good ulti with blink dagger or lothar's and generally good at harassing. This will definitely be in the top choices for mid heroes.
Bloodseeker Passive for regen from creeps is just great. With axe for 32% damage vs creeps you will probably never need to go fountain for regen. When you hit 6 you can easily gank.

You have a good ganker hero. This means you have for instance Pudge or Mirana which after quickly achieving level 5-6 can go fast top/bottom for gank and get kill 100% sure if they get hook/arrow. Also take Tiny for example. Getting fast lvl 7-8 when all the other players are level 5 will get you easiest kill ever with avalanche/toss combo. Bane falls easily in this category with level 6. Lion due to ultimate of course, but arguably better as support/roamer. Tinker has so much burst damage at level 7-8, leveling him fast is a good idea as he can easily get some early game kills.
You are a good harasser. This means you can really slow down the enemy's mid hero leveling/farming. Most of the time you won't see this happening but I've seen this in some games.

This doesn't cover all heroes but hopefully will give you a good idea to start with.
Comment: Isn't Riki mid easy to shut down with a nuker ?
Comment: yea, riki will get eaten alive by any sort of ranged mid
Comment: @BlueTrin You are right! Getting Riki mid is really dependent on the enemy mid hero and I wouldn't advise unless you really know your Dota and it's meta.
Answer: Mid is most suited for level dependent heroes (heroes with good nuke abilities),most of those heroes will be able defeat their mid opponent without problems once they reach level 6.
Suitable mid heroes: Pudge, Boodseeker, Lion, Lina, Shadow Fiend, Tinker, Doom, Puck, Storm Spirit...

Carry heroes are often seen on mid since they need extra gold.If
   there is no better mid hero they are reasonable choice but they are
   preferred to be in woods or babysitted by a support hero.
Tanks usually lack the damage to kill mid opponent,and since they are melee they often get underfed with opponent denies.Tanks are better off helping other heroes in group fights.
Support heroes are self explanatory,simply there is no one to be supported on mid.

Mid is best soloed since you will mostly have someone level dependent there and with someone you will lose part of the experience.
However there are cases of hero picks,that you could send 3 heroes mid lane to get easy first blood and destroy the first mid tower quickly...it will allow 2 of your players to get solo experience and give them that quick tower gold...it could also ruin opponents mid hero role.
Answer: Mid is for heroes who can take advantage of RUNES because runes spawn either in between mid/bot or mid/top.
In competitive games runes are fiercely contested because they can literally turn fights around(DD)/force people out of mid(regen)/create unescapable deaths(haste)/create temporarily uncontestable advantages (DD)/cause mass paranoia (illusion/invis).
A rune resets a bottle which total gives something like 405 life and 225 mana.
Wisp + anything is incredibly scary middle (mostly seen in serious business games) because Wisp's tether allows his hp/mana regen to effect his ally and essentially double the bottle resets. Many more vulnerable mids (SF, Storm, Invoker) absolutely cannot do anything but die to a CK + wisp that knows what they are doing for instance.
Runes are made for aggression. The mid hero(es), their job is normally to help the rest of their team win their lanes (99% of the time in unorganized play. More likely to have more customized plans in organized but this is boiler plate and it works fairly well).
Heroes that snowball either themselves or their teams are generally a good choice (Wisp snowballs his team extremely hard). For example, Earth Spirit is over powered (cannot contest his runes, his spells are extremely mana efficient) but better now after nerfs. He is a good mid. TA is extremely good mid because she starts 1 or 2 hit killing people if she gets ahead too much and has 0 down time because her traps are always up.
Lion is not as good because his spells are mana inefficient and his Finger has a lot of down time.
Storm is very good because he theoretically has 0 down time if the player is good enough with mana management/lucky with runes. Also his first item is an Orchid which is an extremely aggressive and powerful item before people have Linkens/BKB.
Puck is like a safer more AoE version of Storm.
Dragon Knight is actually not bad because he snowballs his team by forcing tower fights/slowly beating them to death. He is basically invulnerable against most of the cast for most of the game if he gets a large gold advantage since he buys hybrid defense/offense items like BKB, Halberd, Cuirass, Satanic.
Invoker used to be popular mid but he dies to everything at lv 1/2, has 280 base ms and can't contest/use runes well and needs too many levels to get useful. Most mids get much more useful at 6.
Shadow Shaman is not bad despite being mana inefficient. Many heroes can't prevent the mid tower from falling when he hits 6. He gets extremely scary if he can start taking towers and working towards his Aghanims early in the game.
Pudge is fun but somewhat risky. He runs slow for one thing and is useless if he can't land good hooks.
Tinker is often times better left alone in the jungle to quickly farm his BoT. Mirana is good if paired with a BANE for guaranteed 5 second arrows, so no solo.
Map control heroes like NS and BS are actually usually better placed in a side lane since they often times can't effectively deal with bottle spam + nuke wave + get all the runes play that Puck/SF/DK/etc. can use against them. They're wasting the lane if they can't contest runes because they are always at tower.

What makes a good mid-lane hero?


How can I enable mod_rewrite in apache on Ubuntu?

Question: How do you enable mod_rewrite with Apache in Ubuntu 10.04?
I tried copying rewrite.load from /etc/apache2/mods-available to etc/apache2/mods-enabled but that didn't work.
Answer: Try this: sudo a2enmod rewrite, and then restart apache.
Answer: Obsidian's answer to use a2enmod is the proper solution. andol's method would work, but could break on upgrade.  What a2enmod does is simply create a symbolic link, so the following two are the same, both proper, solution:
  ln -s /etc/apache2/mods-available/rewrite.load /etc/apache2/mods-enabled/

or
  a2enmod rewrite

However, a2enmod will look for other types of files, some have .conf and possibly others.  There's no reason not to learn this command, though it's important to know what is going on in the background.
Copying the file would make any future admin very unpleased with you. :)
Comment: Well, it's just for local testing, so not a big deal. But ya, `a2enmod` is just easier anyway.
Answer: Actually, while being the kind of wrong solution, copying rewrite.load from ./mods-available/ to ./mods-enabled/ should have worked. Did you remember to restart your apache afterwards?
In any case, ./mods-enabled/ should usually contain symlinks to corresponding files in ./mods-available/. This is, as mentioned by Obsidian, easiest handled by the commands a2enmod and a2dismod.
Apart from enabling the module, you will also have to activate the rewriting. Before you can write your RewriteCond:s and RewriteRule:s there has to be a "RewriteEngine On" in that configuration context.
Comment: That works too. Just remember to set the right permissions on the symlinks in mods-enabled... or you will be pulling your hair out.


is PERT/CPM still being used?

Question: I wonder whether PERT/CPM is still being used, or, is it an ancient methodology for the world of today? Thanks.
Answer: Although I had never heard of  CPM (Critical Path Method) and PERT (Programme Evaluation Review Technique) and thought you were asking about an old operating system it appears that these techniques are still in use or at least still taught.
Doing and advanced search on Google and limiting the query to the last year resolved to 731,000 results.
I also noticed that there are a great number of software options, including methods to make office produce the required charts and documents.
The only restriction I found was that it is generally not used for very large projects as the graphs tend to get too large to be easily printed.
Hope this helps.
Answer: Microsoft Project (and a variety of other project management tools) offer Gantt charts, which as far as I can tell are equivalent to PERT charts.
I use them on 6-12 month tasks building complex software systems.  We usually define several hundred tasks, that do have many order dependencies.
This is a completely different perspective than another poster's answer who says "for the software part of the project, ... there aren't any order dependencies".   His world is sure different than mine.
Answer: I find PERT pretty silly for the software part of a project, because there aren't any order dependencies.  You can develop use cases in any order without affecting the total development cost by any measurable amount.  I would even argue that use of PERT charts for software projects is a project smell pointing to a counterproductive project organization.

is PERT/CPM still being used?


Generate texture on image in C#

Question: I have a bitmap image of one color (say green). I want to generate textures on this image. The rendered image will be then saved.
I have tried using convolution matrix but it is not generating any effect as the image is of single color.
Any help or method would be appreciated.
Thanks
Answer: You could just use an image editing app to create the effect that you want.  Then just pull that file into whatever you're writing and use it from there.

Generate texture on image in C#


Examples from the Nikkor Micro 105mm f/2.8 on a full frame camera

Question: This is more of a request than a question. I'm considering getting the aforementioned lens but I'm a bit afraid that it may not allow me to produce as much magnification as I would hope for. That's why I would like to ask users of this lens to post pictures or links to pictures taken with this lens and a full frame camera. Show me how "big" it can go.
Answer: Here are many samples:
Pbase.com
Out of the 16k photos there, I'm sure some are with a d700.  A bit hard to narrow down the search there, but still, a good way to get some impressions.
For what it's worth, Bjørn Rørslett did not particularly like this lens in comparison with the 200mm or the 60mm, while Thom Hogan doesn't understand the point of a 60mm, since the 1:1 focal distance is so close to the front element that most bugs will be spooked by it.  I find both of those reviewers to give very thorough, detailed critiques of lenses, and coupled with the samples on pbase, I have a much better idea of what to expect.
Answer: It's a 1:1 lens, so that means that the size of the subject will be the same size on the sensor. Meaning, for example, a 10mm x 10mm square will project exactly 10mm x 10mm on the sensor at the 1:1 focus point. To go beyond that, you need extension tubes or multipliers.
Anyways, reviews on the lens rate it very high. Like most macro lenses, it's razor sharp.


How do you define a new language specification for color syntax highlighting in Xcode 4?

Question: For Xcode 3 there is plenty of information available about how to define a syntax highlighting specification for a language not already supported in Xcode.  But there doesn't seem to be any information on how to do it for Xcode 4.  For example, I would like syntax highlighting for Common Lisp, Forth, and other languages not appearing in the "file type" drop down in Xcode 4.
Answer: It appears that this just isn't possible yet.  According to this answer the API's that supported this in Xcode 3.0 were outdated even for that version, and have been completely removed in 4+.
There is a project called solarize that may do what you're looking for, but I didn't see any of the languages you listed and support for Xcode 4 is still limited.  I personally use Xcode only for Objective-C programming, and then use eclipse or TextWrangler for the rest

Eclipse for Mac OS X

Eclipse is great for the more intensive projects, that have multiple classes, and are actual projects.  It's mainly developed for Java, but also supports Python, C/C++, PHP, and Lisp (probably even more)

TextWrangler

TextWrangler is great for small edits or files.  Things that I need to pull up quick, and make smaller edits to and supports tons of languages as well.

It appears that Xcode can even open external editors when the files are associated to that editor.  While this isn't the perfect solution, it appears to be the only one for now.


Is celibacy intrinsic to Buddhism?

Question: I was reading about Buddhism in Wiki and I just am not able to make out if celibacy is a must for Buddhists?
Comment: In practice, some schools seem to allow non-celibate monks and nuns. I've known a few soto-zen monk/nun couples...
Comment: What kind of Buddhism? As I have to keep reminding question askers, Buddhism isn't a monolithic single thing with a central body for deciding doctrine. Also, within a sort of Buddhism, do you mean lay or monastic? You used the tag five-precepts, which normally means lay Buddhist who in no tradition that I no of obliges lay Buddhists to be celibate.
Answer: Is celibacy intrinsic to Buddhism?
The answer depends as follows:

As a householder, no, celibacy is not required. It is only required to abstain from improper sexual conduct. And what is improper sexual conduct?

He gets sexually involved with those who are protected by their
  mothers, their fathers, their brothers, their sisters, their
  relatives, or their Dhamma; those with husbands, those who entail
  punishments, or even those crowned with flowers by another man.
-AN 10.176, To Cunda the Silversmith (Cunda Kammaraputta Sutta)

As a monastic, yes, celibacy is required. You can get a better understanding of monastic celibacy by reading this discourse (AN 7.50, which is at the bottom of the linked page).

This distinction, however, is not "set in stone" or "black & white" since householders are encouraged to be celibate if they feel inclined to do so.
Comment: The referred discourse (AN 7.50) in the answer above is now a 404 link.
Comment: @Troll Updated.
Answer: If you choose a way of a monk - you have to keep your vows so celibacy is a must for you.
If you choose to be a lay Buddhist, you should undertake 5 precepts and one of those is avoiding sexual misconduct. When two people love and respect each other they can generate lots of happiness through sex. In tantric Buddhism giving sexual pleasure is actually seen as a form of generosity.
One of the most important practices in Vajrayana Buddhism is meditating on Yidams (Buddha forms). Some of the forms represent male and female Buddhas in union. If Buddhas do it, there must be nothing intrinsically impure in sex.
Answer: It would be ideal if a question like this were framed as either an inquiry into personal experiences and views or as relating specifically to the precepts of specific schools of Buddhism.

am not able to make out if celibacy is a must for Buddhists?

The answer I would give is no. Only one Buddhist ever was required to practice celibacy: that was Shakyamuni; and he required it of himself by "marrying himself to the Earth." In an allegorical sense this marriage is indicated by the story of Shakyamuni's final struggle with Mara (the devilish nature of delusion integral to all beings; an innate part of consciousness); when challenged by Mara to produce any person who could testify that he, Shakyamuni, was qualified to become the Tathagata, the Teacher to all living beings, Shakyamuni placed his hand, palm upon the ground and said "The Earth is my witness" (it is said that when he did this, the ground trembled in many directions, scattering the followers of Mara, who fled in terror).
Vinaya, the codified rules of monastic conduct, do not apply outside the school which claims them. So the Vinaya of Theravadan Buddhists cannot be applied to those answering from a Mahayana perspective (as informed readers will no doubt deduce that I am).
I have been celibate for more than a dozen years as I write this. I am in my 50s and am a male American person. It has some great aspects.  However, everything is like a blade that has two edges.
Comment: (+1) for some decentness in your answer which I like much (without being sure I'll share everything while I'm thinking over it)
Answer: a delicious cake is displayed in a cake shop showcase and a male  and female ,both are tempted to eat it .they go inside, order it, eat it together with joy. now nobody will think it as immoral,etc etc. There is no guilt associated with it. but as regards to sensuality ,eating is attached with guilt,immorality etc etc. It is this attached guilt is hindrance in any kind of spirituality be it hinduism,buddhism,christianity,islam and lot many. this associated taboo has its roots in the early primordial humans living in tribes,groups. The desire of sensual pleasure makes the women vulnerable and vica versa .to protect it the taboo might have been got associated. we cannot help it now ,since this taboo is coming from thousands of years . even the small children are taught to refrain from touching their private parts and hence how they will also come out of this taboo. the cycle goes on repeating . the taboo is not associated with wearing nice clothes,eating delicious food,enjoying good movie. if the guilt of being immoral is absent then there is no need to give so much importance to this taboo. whole religions are whirling on this aspect only. so listening/following to those are also filled with ego of maintaining celibacy .On the contrary the ego or "i " is to dissolved,ruptured. So it is upto the individual what to follow. celibacy making the "i' still stronger or tabooless,guiltless non celibacy.
Answer: Something which is intrinsic to Buddhism applies to it regardless of its levels of practice or cultural variation. Insofar as the 8-Fold Path is definitive for Buddhism as a stipulated formula of practical application interpreted according to insight received in meditation, there is no part of it which clearly requires celibacy.
It would be far more helpful to talk about monasticism, the extremes to which it tends to aim, and whether celibacy is intrinsic to Buddhist monasticism, or indeed monasticism of every other kind. The justification for it being essential and important to monasticism is in part what also sets up the contextual Indian framework of the Four Stages of Life (Student, Householder, Forest-Dweller, and Renunciate): that the energetic focus and interest wanes from or turns aside from conventions, reproduction, and the drama of emotional co-dependence, and shifts toward cohabited placidness, the peace attractive to those with spiritual values, and the equipoise available to those set upon Nirvana.
Answer: Originally, in the 1st sermon, it was made quite clear the Noble Eightfold Path was a celibate path.

Thus have I heard. On one occasion the Blessed One was dwelling at Baraṇasi in the Deer Park at Isipatana. There the Blessed One
  addressed the bhikkhus of the group of five thus:
Bhikkhus, these two extremes should not be followed by one who has gone forth into homelessness. What two? The pursuit of sensual
  happiness in sensual pleasures, which is low, vulgar, the way of
  worldlings, ignoble, unbeneficial; and the pursuit of
  self-mortification, which is painful, ignoble, unbeneficial. Without
  veering towards either of these extremes, the Tathagata has awakened
  to the middle way, which gives rise to vision, which gives rise to
  knowledge, which leads to peace, to direct knowledge, to
  enlightenment, to Nibbāna.
And what, bhikkhus, is that middle way awakened to by the Tathagata,
  which gives rise to vision … which leads to Nibbāna? It is this Noble
  Eightfold Path; that is, right view, right intention, right speech,
  right action, right livelihood, right effort, right mindfulness, right
  concentration. This, bhikkhus, is that middle way awakened to by the
  Tathagata, which gives rise to vision, which gives rise to knowledge,
  which leads to peace, to direct knowledge, to enlightenment, to
  Nibbāna.
SN 56.11

Is celibacy intrinsic to Buddhism?