Dying Hydrangea

Question: I have had this hydrangea for a couple of weeks. When I first got it, it had beautiful, big blue blooms. But, now it seems to be dying.
I'm keeping it in a place where it is shaded for most of the day, except the morning.
What should I do?
Thank you in advance!
Comment: Can you give us some more details. How much water did you put, what type of soil is in the pot, where are you keeping it (inside the house, outside). Have you applied any pesticide, any chemicals in contact. More information, the better.
Comment: I have watered it every day. The soil in the pot is just the normal soil I got in my backyard, I think the pH is between 6.8-7. I am keeping it outdoors. And I havent used any pesticide or chemicals in it. Thank you
Answer: This looks like a 'floral hydrangea'...one that was purchased in a floral shop?  If that is true then what is happening makes sense.  You transplanted into a larger pot (good size, what soil did you use).  Did you purchase this plant already planted in this pot?  If so then the florist transplanted it to be able to charge more, which is fine.
What they should have explained was this hydrangea is not used to being out of doors.  How to acclimate the plant to the out of doors.  These plants are usually only made to be pretty for awhile, short term perishable.
You most certainly can transplant them into larger pots or even out of doors in the garden IF they are acclimated correctly.  If planted in a  pot, use only potting soil.
This plant is not dead at all.  The blooms are dying as they should.  Cut them off without leaving a stump.  If they are completely dry then they can be used for a dried flower arrangement.  If not, put the stem of that flower in a tiny bit of water; 1/2 inch.  As the water dries the flower dries.
I am seeing the results of a lot of salt and/or full sun reaching the leaves beneath those flowers.  Those dried and curling leaf margins are showing this plant has been over fertilized or you are using tap water to water your plant or it has had some bright direct sun that 'burnt' the leaves because the leaves weren't hardened off to full sun first.
Keep this plant in FULL shade.  No direct sun.  I think your plant should be hardened off a bit more to adjust to direct sun then planted in your garden in partial shade.
Do you have other acid loving plants that are doing well such as Rhododendrons, Azaleas, Camellias?  If those plants are healthy that means the pH should be correct for your Hydrangea.
Let us know what you want to do with this plant.  He is a very good looking specimen, honest.  Out of doors is where he belongs and we can help.
Comment: Interesting, you are noticing the correct stuff to notice.  Pink hydrangea means alkaline soil.  Acid soils make blue hydrangea out of the very same plants.  Yours is used to acidic pH.  Those flowers are DONE.  They are only meant to produce seed, babies.  I collected blue and purple hydrangea flowers from my client's shrubs then used them and baby's breath to decorate my Xmas tree, stunning.  Is your pinkish hydrangea a 'mop head' too?  Like the flowers on this hydrangea?  A big round collection of flowers?  Then that means your soil is a bit alkaline...and you might end up having pink flwrs
Comment: Purchase distilled water, if you are able, to water plants in pots.  Our tap waters are so suspect for lots of awful chemistry. Fluoride is industrial waste...seriously, everyone needs to know about this really weird thing our country and others got hoodwinked into doing, into believing so much they give BABIES fluoride tablets.  Not one shred of evidence or tests that show any 'benefit' to humans and animals and plants.  Amazing thing to learn more about.  Causes white spots and brown pits on teeth.  Plus an awful lot more damage to bones and brains.
Comment: Do you have any relatives or friends that live close but have a well for water?  I would get a big water bottle and fill it up with the well water.  Or use distilled, I just hope it is truly distilled.  The only way to get fluoride out of water.  Of course it is in all canned goods, preserved foods, all sodas, all fruity drinks, all bottled water, Cheerios and Fruit Loop cereals.  Our body puts it in our bones and there is accumulates.  Just fyi...great documentaries on this subject...
Comment: Thank you!
I got this as a gift, but I think that it was purchased in a floral shop. It came in a smaller pot, but I changed it into this.
I am using tap water. Should I be using water bought in a store?
I do not have the other plants that you mentioned, but I have another hydrangea (looks the same, but has flowers that change from green to pink). That one seems to be doing fine, but it already had stronger stems when I got it.
Should I cut the flowers now or is there any chance they can regain their color?
Ultimately, I would like to remove it from the pot and plant it in my garden.

Dying Hydrangea


What is the focal length of Nikon 1 lenses mounted on a full frame camera?

Question: If I were to mount a Nikon 1 lens on a full frame camera what would the focal length be? I know that using a crop frame sensor means that the focal length is effectively increased. Are the Nikon 1 lens lengths recorded as full frame equivalent or is the length adjusted for crop frame?
Comment: It seems like a duplicate of [What is crop factor and how does it relate to focal length?](http://photo.stackexchange.com/questions/139/what-is-crop-factor-and-how-does-it-relate-to-focal-length)
Comment: How would you mount the lens/does such an adapter exist? I've seen the Nikon F lens to Nikon 1 body adapters, but never a 1 lens-to-F mount adapter.
Comment: @DanWolfgang Nikon F-mount flange focal distance is 46.5mm; Nikon 1 FFD is 17mm. The adapter would have to *remove* 29.5mm. So no, it's not possible to mount a Nikon 1 to F body (and expect focus to infinity, that is).
Comment: @scottb That was kind of my point. If this is a theoretical question then it doesn't matter, but if the OP intended to actually do it then there are going to be significant limitations.
Answer: 10mm is 10mm. Focal lengths of almost all interchangeable lens camera systems are expressed in the actual focal length of the lens.There are certain technical reasons why this is so, but the simplest is that a lens' focal length is defined as the distance from the film plane needed when the lens is focused at infinity to cast point light sources as a single point on the film plane. This doesn't change with regard to sensor size. What does change with regard to sensor size is the angle of view or field of view (FoV) that a lens of a specific focal length will include in the part of the image circle that falls on the sensor.
Your Nikon 1 camera has a crop factor of 2.7X. what this means is that the 10mm lens made for the Nikon 1 gives the same FoV as a 27mm lens would on a full frame camera. But the optics in the lens still have a focal length of 10mm.
For more about how focal length, sensor size, and FoV are related please see What is crop factor and how does it relate to focal length?
Answer: Focal length is never adjusted for crop factor, since it's a physical property of the lens. It doesn't change just because you put a bigger sensor behind the lens.  So, a 10mm lens on your Nikon 1 would still have a 10mm focal length on full frame.
What would change, if a 10mm Nikon CX lens worked like a Nikon FX 10mm lens, would be the field of view.  Since the CX format has a crop factor of 2.7, that would mean that the field of view of a 10mm lens on full frame would look like a 10/2.7 => 3.7mm lens would on your Nikon 1.
The main problem here, however, is that a CX lens doesn't work like an FX lens--the size of the image circle the lens projects is only big enough to cover a CX sensor, not an FX sensor.  So, if you actually could mount one on an FX camera (which you probably couldn't, because it would have to sit right where the mirrorbox goes) you'd probably only see a circle of the image in a mostly black field, because the FX sensor is so much larger than the image circle the CX lens would project. So, you wouldn't really get the FoV of a wider lens.


What's a good way to practice 8ths in the piano?

Question: I would like to be able to play 8ths (2 same-note chords) fast and without stumbling on the adjacent notes. I think it can add color to some basic songs. Question is: what's a good way of practicing them in the piano? Just play a scale using it instead of the single note?
Answer: Playing 8ths (AKA Octaves)
Creds: I've been a piano teacher of all levels for more than 10 years.
First thing:
If you're just beginning, start off learning 6ths first. 6ths use the exact same arm motion as 8ths, except 8ths are wider, and cause more arm strain. Thus, it's best to learn 6ths before 8ths to get the hang of it. (depending on how big or small your reach is.)
What you need to be able to play good 6ths or 8ths:

Be able to hold the position of a 6th or 8th.  You need to know the distance required and call on it automatically. To do this just play a 6th or 8th, close your eyes and memorize how it feels to play that interval. How does your hand feel? How far apart is it? Then take your hand away from the piano, shake it out, and then set your hand on your lap and stretch your 1 and 5 out to where you think they need to be to hit the 6th or 8th. Now, put it back on the piano and see if it fits. If your hand lands on the 6th or 8th cleanly, great, if not try again until successful. Keep doing this until you've successfully got the 6th and 8th at least 10 times in a row without any mistakes.
Arm motion of arm/hand/finger unit: move from one key to the next accurately. This skill is called by both 6ths and 8ths, so learning 6ths arm motion will also transfer to your 8ths.  Basically the idea is to pick up your hand and move it to the next desired key. You'll want to keep your hand relaxed while you move and play. (Learning to relax takes at least a month or two of dedicated practice time) Keep your motions as small as possible. The smaller you move, the shorter your distances, the better. You'll want to direct your motion sideways and not up and down. When you play C to D, think of skipping a rock across water, stay to the surface and move sideways. A good exercise to understand the arm motions is: Take an invisible salt shaker in your hand, and do small shakes as gentle and fast as you can while you glide your hand left-right across a table, while keeping the distance above the table at about 2-3 inches.   The salt shake motion is like hitting the 6ths or 8ths, and the glide is moving from one key to the next while your arm moves.
Final exercise

Starting on D's (8ths) play each key listed 3-8 times: D D D, D# D# D#, D D D, Db Db Db, D D D, (loop)
Same thing but starting on F's play pattern: F, F#, F, E, F (loop)
Same thing but starting on B's play pattern: B, Bb, B, C, B (loop)
Same thing but starting on F's play pattern: E, F#, E, Eb, E (loop)
Same thing but starting on F's play pattern: C, C#, C, Bb, C (loop)
Once you've done all these patterns, you've done all possible diatonic scale combinations you could encounter.
I also made this video on arpeggios and octaves a long time ago, but there should be a few good tips!
If this answers your question, please mark as answered to keep up with maintenance. I wish you the best. :)
Answer: By 8ths, you probably mean OCTAVES. Usually played with thumb and pinky (unless you're lucky enough to have a large span and can use ring finger!) It's more of a hand movement than finger movement, hingeing from the wrist. Try r.h. going up and down scales and arpeggios. Watch your thumb, and keep the same span, and the octave note above should be played almost automatically. Try 3 or 4 note tunes to start with. It can also be effective to play the lower note a moment before the upper.


What's the functional difference between the NEF and normal ANNs?

Question: Aside from obvious biological plausibility, from a computational standpoint, what's the motivation of using the Neural Engineering Framework (NEF) instead of Artificial Neural Networks (ANNs) for computing functions? From what I can tell, they both approximate functions, have the ability to learn new functions and the ability to create self-organizing networks. What makes the NEF different?
Answer: First, let's take a look at the basic principles of NEF.
The first two principles (Representation and Computation) do seem analogous to trained ANN models. Additionally, with the hPES learning rule that I've described here, they seem to have the same learning (gradient-descent) capabilities.
Where the NEF differentiates itself the most from ANNs is when it starts to describe dynamics (oscillators, attractors). For a description on how it does this and what it accomplishes, check out Terry Stewart's course notes found here.
Describing dynamics is important in the brain, since simple oscillators and integrators seem to be the foundation of many different cognitive abilities such as working memory and motor control.
Comment: When I see ANN I think of individual neurons modeled for simplicity and problem solving, not physiology (so not ion current models based on actual channel kinetics).  Usually the goal is to compute something, not understand neurons - I think that the core definition of ANN is in the goal of the network design, not the type of neurons used.  The two I mostly see in such approaches are integrate-and-fire and firing rate models.  Though I'm no authority here, my research in ion-conductance models.  I know sometimes you can deduce group neuron behavior using ANN's, so there's likely a fuzzy line
Comment: What the NEF does is translate neural coding into the solving of differential equaions (well functions more generally)  You might argue that it's a specific implementation of ANN.
Comment: @KeeganKeplinger When you say "specific implementation" of ANNs, it could be interpreted as saying that they both have the same functional capabilities, but I'm not sure I understand your evidence for this. Could you help me out?
Comment: an ANN is just a network of simple neurons (usually designed in some connective pattern, designed to serve a purpose).  NEF utilizes an ANN to solve differential equations.

So of course, ANN, being the more general term, has more capabilities... but once you choose an instance of an ANN for a specific purpose, you begin to limit the capabilities of the ANN towards your purpose.
Comment: So when you say ANN, you don't mean specifically the back-prop type. You just mean any system that has nodes that are neurons that are then arranged in a manner to imitate neural computation?


How to decide which stroller to buy?

Question: There are so many kinds out there.  What is the most important thing to consider?
That it would be easy to close it or that the child will be facing toward you?
Comment: I'm protecting this, after a spam edit was just introduced (hopefully protect prevents that also?).  This question is the sort of thing that draws spam like a magnet, and while it's been edited to be on topic (back in Jan) I think it should be protected to prevent too much spam from creeping in.
Answer: I bet there are books on "how to choose a stroller";) A short list of important things to consider:

size and type of wheels - a stroller with bike-like large wheels will handle better than a stroller with small plastic wheels. It will also behave better in difficult terrain. Also, the inner tube should be replaceable.
brake - it should have one. It should be impossible to move the stroller with the brake on. Are they easy to operate?
stability/construction - try to shake the stroller when the brakes are on. It should tilt only slightly to the sides and hardly to front and back
modularity - some strollers can be interchanged with car seats or prams. Travel Systems are quite handy.
weight - if you have to go to places not adapted for strollers or disabled people, the weight will be an issue
space it takes - can the stroller be easily disassembled (folded? sorry, struggling with English here) for transport?
rocking - some strollers allow for some degree of rocking in vertical direction - it can be useful. It'd be good if such rocking can be easily enabled or disable

Additionally, I would suggest choosing the stroller in two pahases. First, go to the shop and find those you (and your partner) find acceptable. Then come with your baby and let it have some influence on your decision.
And lastly: take it for a test drive:)
Comment: Here, it is common to buy the stroller before the baby is here. so i can't really take it to a test drive with my baby.
Comment: @ItayLeving a stroller? I'm no native speaker, but didn't you mean a baby carriage?
Comment: @Dariusz In the US at least, Stroller is the more common word, and is used generically for anything you might push a baby/toddler around in.  More precise words (pram/carriage/etc.) might also be used, but stroller is very common.  It's also common not to buy a separate carriage; I didn't have one, for example.  I did have a stroller that held the baby carseat in reverse, when the baby was too small to hold his neck up.
Answer: You almost certainly will need more than one stroller.  Don't try to get just one that is perfect; consider getting two imperfect ones that complement each other.
For example, portability is important; but you can get an umbrella stroller (a super-lightweight one that cost around $20-$30) for the times when you get on the bus or train and want very little space, and then buy a larger stroller that isn't as portable but has better features (big wheels, cup holders, etc.) for times when you don't need the portability.
Answer: It really depends on your usage.  When my child was born, I didn't have a car and was going to college, so something sturdy that collapsed to being small and had a detachable section so that I could put her in a friend's car was important.  For going around to class, I had a sling I held around me that kept her close to me and allowed me to sit in a desk.  Also, because I would spend hours out and about with her in it, it needed to have plenty of storage space for her diapers, change of clothes (never know when something will happen), and other sundries (like a small med kit -- I'm a bit obsessive about planning for everything [though I didn't plan for her throwing up on me twice on the bus on one trip home!]).
So, ask yourself, what is your usage?  Make a detailed list and search online for various strollers so that you can find one that meets your needs... then research complaints from owners by searching for "review stroller_name" or "complaint stroller_name".  Finally, go to the store and check it out yourself.  You'll be well-armed to make a good decision.
Finally, don't settle for price over quality -- they're not one and the same.
Hope that helps!
Answer: I have to say, this caused me a near nervous breakdown because there is just so much choice.
I looked at the practical element, and really struggled because it was nearly impossible to compare, but the key things for us were (in this order):
1) how easy was it to put up or down.
2) Would it fit into the boot of the car (and/or would there be space for shopping if it did)
3) How heavy was it.
4) Storage
HEavyness isn't always a bad thing, a bit of weight gives stability, but too heavy was a no-no, and storage isn't the everything because you can always carry a bag - you did before you had kids right? So for us, the ability to manuver it around when the kid wasn't in it was quite key. Imagine trying to get in or off a bus or in a carpark with the little one screaming. If it took more then 1 minute to collapse, that's a no no.
In the end, we bought a pram for the first year and a half, and swapped to a stroller, after that: for the pram we bought a moderately expensive one, to give protection when she was so small, but for the stroller we opted for a quite cheap, lightweight one that collapses really well. Its easy to push around when collapsed, so we can go into town and she can run but I have this for when she gets tired and we havn't finished shopping.
I don't think there is a perfect 'this stroller is the one everyone should buy', you've got to work out your priorities. You can rule off a bunch of strollers quickly, and narrow it down. Just don't do what I did and have a nervous breakdown over it.

How to decide which stroller to buy?


Only one category per post

Question: How to make each post/page have one and only one category. Categories could have radio box instead of checkbox next to each.
Answer: Actually, I wrote a plugin for exactly that.
http://wordpress.org/extend/plugins/radio-buttons-for-taxonomies/
In the plugin settings you define which taxonomies you'd like to apply this restriction to.
Answer: My prefered solution would be to use Advanced Custom Field with the Taxonomy field.
This way you can add a simple html select field for category, and in the same time hide the default wordpress categories widget.
https://www.advancedcustomfields.com/resources/taxonomy/
Comment: Please correct me if i'm wrong but this method creates another field (posts meta) for storing the term links rather than using the default wordpress method (terms table).  This means the standard wordpress features like the automatic admin column and taxonomy term counts don't work properly.
Comment: I'll definitely second this. The ACF plugin is great in the first place, and this solution is dead simple. Word of notice, I believe the Taxonomy Field Add-On is ACF 3 only, whereas ACF is now 4 and has Taxonomy fields built-in. Just remove your custom Taxonomies via the Screen Options tab.
Comment: ACF is great, but keep in mind that themes always accommodate the default post_meta of category. It's more flexible, but if you're just looking to restrict number categories to one per post type instance, it's not the fastest solution.
Comment: You're totally right, it's all built-in now :)
Comment: That link is broken. Is there an updated link?
Answer: From within the WordPress Admin, I haven't seen anyone modify category selection to force only 1 category. However, a good solution for you might be to use Gravity Forms. Using Gravity forms you can create a "front end posting solution" and in doing this you can set the category selection to use Radio Buttons instead of checkboxes. Alternatively you could also use a dropdown menu, again only allows 1 selection.
Another alternative is to modify the wp-admin area (which you will need to to in order to keep the WYSIWYG portion of the content editor as I don't think the front end solution provides this. I would suggest you remove the standard category meta box, very easily using code from this page:
http://codex.wordpress.org/Function_Reference/remove_meta_box
And then create your own categories metabox using a dropdown value, which you can easily create from this page:
http://codex.wordpress.org/Template_Tags/wp_dropdown_categories

Only one category per post


Is my statement an expression of disbelief?

Question: I was once listening to a ruler of a non muslim nation saying that " I will give the power to the people of this country" And i said to myself that "no you will eat it up all by yourself'. Is this regarded as something that shows support for democracy?and is it regarded as going against the Shariah even though the leader was of a nation that was originally disbelieving.
Comment: First only you can answer if it is regarded as something that shows support for democracy because you said it and know what you mean. Secondly why is showing support for democracy disbelief?
Answer: TL;DR: It seems awfully strict to consider it disbelief.  For it to be disbelief, one would need to be convinced that God's ruling is incorrect, and have an intention of disbelief.

1. Al-Azhar University prepared The Response (pdf, URL), which discusses a fatwa in relation to this topic:

A question was asked about the rulings that contradict [the
  meanings of] God's Revelation.

They summarize Shaykh Al-Fawzan: The Religion of Tawhid, 116, as:

Changing God's Revelation with other rulings [that are not derived from revelation] constitutes an act of disbelief. This act evicts one from the fold of Islam.

And respond to it as follows:

... the person who does this is not to be accused of disbelief, unless s/he is convinced that God's ruling is incorrect and his ruling is correct.

2. In the Open Letter to Al-Baghdadi, a large number of scholars worldwide endorsed a document in response to ISIS leader Al-Baghdadi's behavior.  They write:

... disbelief requires the intention of disbelief, and not just absentminded words or deeds

They derive this from Qur'an 63:1 where the mere actions of belief by hypocrites were insufficient to render someone a believer:

When the hypocrites come to you, [O Muhammad], they say, "We testify that you are the Messenger of Allah." And Allah knows that you are His Messenger, and Allah testifies that the hypocrites are liars.

From this, they surmise that mere actions of disbelief would be insufficient to render someone a disbeliever.


How to receive email notifications of newly accepted papers in a specified set of journals?

Question: Is there some way of arranging that I receive emails whenever selected academic economics journals of interest to me, perhaps published by different publishers, post online a newly accepted paper?
Comment: I posted this question in the economics site because, as far as I know, the answer to this question is very different from discipline to discipline. As far as I understand, computer scientists are, for example, in this respect much better organized than economists.
Answer: I have never heard of that. But you can setup an alert on Google scholar and get notifications when publications appear that match your search query or keywords.
Answer: Most journal offer an email alert service for new issues/accepted papers. A couple of examples :

https://www.aeaweb.org/notify/
http://onlinelibrary.wiley.com/journal/10.1111/%28ISSN%291468-0262 (see "Get new content alert")
http://www.journals.elsevier.com/journal-of-economic-theory/ (see "Stay up to date")
Comment: All of ACM.org offers RSS feeds, which you can instrument with IFTTT
Answer: Some publishers have a page introducing the ways by which their readers can be informed whenever a new issue of the journal is published, or a new paper is published in a journal. You should seek each journal for such email subscriptions.
Also, some websites of the journals provide RSS links for their users. You can copy the RSS link (news feed) of the journal you want to read in your RSS reader software or related online account. Every time an update (may be a newly published paper or a new journal issue) is posted on the publisher's/ journal's website, you will receive it's news on your RSS account.
As an example, the following links are for email subscription and RSS news feature which is available in arXiv for their readers.

To Subscribe to the E-Mail Alerting Service
RSS news feeds for arXiv updates


Action, pickup to string distance, and bridge setup for a Gibson Flying V

Question: I received a Gibson Flying V in 2010. Ive never been very good at the tweaking of guitars, but recently I've been getting some fret buzz. Most noticeably the seventh fret of the low E, (B), and when I pluck the open G string hard enough. I was reading about action and a lot of other specifications and I realized I've never adjusted these things and over the course of the years it could have gotten out of whack. I'm not an idiot and I know how to raise and lower the bridge on my guitar, so I'd rather not take this to a shop and pay a ton of money for something I can easily do at home if that is an option. The problem is I don't know the exact measurements everything should be, like the action, bridge height, pickup to string distance, etc. If anyone knows a general range these things should be it would be greatly appreciated. My bridge is easily adjustable. If I need to send pictures for any reason to clarify some things let me know.
Comment: It shouldn't be a "ton" of money to get a professional action adjustment. I taught myself to do action adjustments on an old guitar that I no longer cared about, because I wanted to make sure my main guitar was always in good shape. Even after learning all that I still take my main axes to pros maybe once a year or every other year. It's worth it. If you're willing to learn on your main guitar, you should be able to get the factory specs with a web search.
Answer: If you would like to do this yourself, Dan Erlewine has a couple of great books on guitar setup and maintenance:

How to Make Your Electric Guitar Play Great
The Guitar Player Repair Guide

These books include good general measurements for common guitars. Gibson also has a basic guitar setup guide on their website with recommended action and pickup heights.
Guitar setup is one of the least expensive services you can get at a guitar shop – probably $40–100 depending on the shop and how much work your guitar needs. Some technicians will walk you through the setup and teach you basic maintenance as part of the service, so be sure to ask if you do go to a shop.


Android: Traffic stats (daily unique user, monthly unique user) for applications using app id

Question: How can I find daily unique user, monthly unique user, weekly unique user for app using app id ?
Answer: Android Market only tracks number of downloads and active installations, which apparently also counts any updates installed. To track unique users you should probably build this into your app with a pingback to your own servers. Here's a post on how to count devices reliably.
Answer: One way is doing like Peter said, and building you own infrastructure. This is the best one if you need to know your user data at a very grained level.
Another solution (cheaper) is to use the Google Analytics SDK for Android. It's a hack supported by google that allows to use the GoogleAnalytics platform to track mobile apps data, but its cheap and fast to implement (and scale).


What does quantum gate fidelity mean?

Question: The formal definition states that it's the distance between two quantum states. What does that mean experimentally? Does distance here mean the distance between two states on the Bloch Sphere? I am a little confused about the meaning of gate fidelity.
Comment: There are many non-unique ways to define gate fidelity, can you add a reference and the relevant details? In general, fidelity (of states) is a measure of their distinguishability: $F=1$ means that the states are identical, while $F=0$ means that a single measurement can distinguish them perfectly. Since many gate fidelities borrow the definition of state-fidelity, they tend to have a similar meaning.
Answer: Very briefly, gate fidelity refers to a way to compare how "close" two gates, or more generally operations, are to each other.
As discussed e.g. in (Magesan et al. 2012), if one wants to compare the action of an operation $\mathcal E$ and a gate $\mathcal U$ on a given state $\rho$, one can define their "gate fidelity" as the quantum state fidelity between $\mathcal E(\rho)$ and $\mathcal U\rho\mathcal U^\dagger$.
A related notion is that of average gate fidelity, which is defined as the above but averaging over all states $\rho$, and thus gives a better quantifier of how similar the operations themselves are (as opposed to just comparing their action on a single input state). See the paper above for more details.
Comment: @quest errors of what? Regarding the gate fidelity and Kraus operators, there is a direct relation between *average* gate fidelity and Kraus operators, see e.g. https://quantumcomputing.stackexchange.com/q/16074/55 and https://arxiv.org/abs/quant-ph/0205035
Comment: does the gate fidelity tells something about the errors? Is there any direct link between kraus operators and the gate fidelity
Answer: Fidelity is a distance measure between quantum states. The gate fidelity uses fidelity to decide how noisy a quantum gate is.
Take two copies of a state, apply your implementation of a gate on one copy and apply the ideal gate on another copy (this can be done on paper, not in a lab) and compute the fidelity between the two outputs. This is the gate fidelity. There are some subtleties on what state you should use in this comparison but this should be made clear by the author.
See the discussion in Section 4 of this paper.
Answer: I find the above answers correct and sophisticated. My explanation would give you just a very general understanding.
In order to understand gate fidelity, you have to know the difference between a physical gate and a software-visible (logical) gate.  Due to the current hardware-technology limitations, physical gates (those that are implemented physically on the real quantum devices) do not precisely map to (implement) the logical gates.
The difference between an ideal gate (a logical gate) and what the corresponding physical gate that a quantum hardware offers is called gate infidelity.

What does quantum gate fidelity mean?


Entering Russia on visa-exempt St Petersburg ferry: can I leave the city?

Question: If I enter Russia by taking a no-visa-needed Helsinki-St Petersburg ferry, can I take a day trip to Moscow, or do I have to stay in St Petersburg for my entire stay?
Comment: I can't find documentation to prove it, but having been there myself on a cruise, I'm quite certain you'll not be allowed to leave the city. You'll also need to book a transfer into the city from the ferry for the visa to be valid, and if you're on a ferry, not a cruise, to have pre-booked accommodation in St. Petersburg. A train trip to Moscow without a proper visa could land you in jail.
Comment: Those day excursions to Moscow from Peter are uniformly demanding in terms of stamina and endurance.  Take care that you're well rested and fit.
Comment: Two nearly-four-hour train rides does seem like it'd make for a long day, but I'd be willing to tough it out if it's allowed - not sure when I'll be in Russia next!
Comment: Related: https://travel.stackexchange.com/questions/26909/options-for-a-cruise-from-helsinki-to-st-petersburg
Answer: Here's the actual legal basis for visa-free travel: http://base.garant.ru/195505 . It says you can stay for 72 hours, have to leave by the same port where you entered, and most importantly (point #6) it says you may only be located on the territory declared in the "official tourist program" filed by your cruise line with the Russian government.
There may be some "official tourist programs" that include other cities like Moscow (see e.g. the article at http://www.rostourunion.ru/ob_rst/novosti/news_archive/pervyyi_bezvizovyyi_parom.html )
Some articles online imply that this requirement is just a formality. For example, this article ( http://www.myestonia.ru/publ/72_chasa_bezvizovogo_schastja/13-1-0-572 ) implies you can go to other cities as long as you still pay for your St. Petersburg "official" hotel. However, the legality of this is very questionable. I would strongly recommend getting an actual Russian visa if you want to do any real exploring, especially given the current tense political situation.
Comment: Thanks. None of the tours offered on the St Peter Line website (at least on my travel dates) go to Moscow, so I guess I'm staying in St Petersburg.


How can I run a placebo medication pills study? Practical advice needed

Question: I am a lab manager looking to design a placebo experiment in a behavioral lab with a medical doctor. I believe our study needs to be credible and professional. I'd appreciate any recommendations on details of placebo manufacturer or retailer, type of pill bottle to use, how to create brochures of information about the purported effect of the placebo pill. Info on points of methodology is also appreciated.
Answer: Ethical procedures are specific to your country and even differ between universities and sometimes even per department. Of course you know everything about the Declaration of Helsinki, being immersed in the city of its origins (you seem to (have) be(en) affiliated to the University of Helsinki). You seem to be located in NY now, but I'm unsure to your affiliation. So I started wandering on the sites of the uni of Helsinki and the New York University for some information. But note you should look into the local requirements yourself (although your study has likely long since started :-)
First, you need to find out the IRB (or here for NY) you will be dealing with, often operating under a university, or affiliated hospital. These folks can tell you anything you need to know. Here is a site of the IRB with all the specifics you need to submit an IRB proposal to NY Uni. Note that the best thing is for specifics such as pill bottles and placebos is to talk to the IRB, or try to find investigators that have done such a thing recently in your neighborhood.  For example, there's a study from Segal et al (2017):
Randomised, double-blind, placebo-controlled trial with azithromycin selects for anti-inflammatory microbial metabolites in the emphysematous lung,
that was conducted by the New York University School of Medicine and by the looks of it it is exactly the thing you are planning to do. These guys can likely help you out, and reading the papers and related ones may help you as well. For example the linked paper says in the Methods:

Both placebo and AZM were prepared in an opaque capsule by the NYU pharmacy...

Hence, the NYU pharmacy, apparently, assists in these kinds of matters - the place to go!
Reference
- Segal et al., Thorax (2017); 72 :13-22
Answer: This might seem a bit random at the moment, but if you run a 15 minutes personality test on a placebo group you'll be to have a better understanding how it works, so it might help with the methodology and overall conclusion.It might also help the process: a person is likely to cooperate if they believe that you genuinely care. Doing and analyzing test for each subject might come handy for gaining that trust.
I strongly believe that people who have trust in authority are likely to be treated successfully with the placebo. Just like faith healing, but 'modern' one. (No data to back it up, unfortunately.)
Comment: How is this related to placebo pills production/presentation?


Repeatedly Clogged Printrbot Simple Extruder

Question: I have a Printrbot Simple Metal. The extruder is getting clogged all the time. I went through the process demonstrated here multiple times already. Heatting the extruder and pushing different tools all the way through to make sure it is completely clear.
Every time I get a clear flow of PLA, and after a few minutes the extruder motor starts clicking again. At that point, it is even hard to push in the filament by hand.
I replaced the tip already, but this didn't make any difference. I also tried few different filaments, all of them worked perfectly before.
It feels like stopping the flow even for about 30 seconds would cause it to jam.
Comment: Hi, Ron. Could you be using a too long retraction settings? To long retraction can make the hot filament cool down and fasten too far up inside the hotend when either not printing or printing an area with frequent retractions.
Comment: Which version of the Ubis hot end do you have? Do you have a fan blowing at the heat sink? Assuming you have a version with a PTFE tube, have you checked the condition of the PTFE tube?
Comment: @TormodHaugene This happens even with no retraction at all. I just extrude (from the control in OctoPrint) then stop for about 30 seconds and try again and it will be stuck already
Comment: What temperature is your hotend at?
Comment: @TomvanderZanden I was experimenting with 195-210C
Comment: @RonHarlev Have you tried increasing your hotend temp. A lot of people go as high as 225C
Comment: @tbm0115 yes. That was one of the suggestions in the answers below. It didn't solve the problem :(
Comment: I noticed that your question has a few answers available and has been open for a while, just curious if any of the available answers was able to help. If not, then what questions do you still have?
Comment: @tbm0115 I ended up just buying a new hot end :(
Comment: I'm sorry to hear that! I might suggest adding your own answer, explaining that your solution was to buy a new hotend and how you came to that conclusion. Just so there is a bit of closure for others with similar issues.
Answer: I had a similar issue on my Printrbot Simple Metal. I believe my problem was initially caused by clogged nozzle which I replaced, however the jamming persisted. I can't say for sure that it was acting exactly as you describe but I think it may have been similar. I noticed that the little red insulating sleeve was pushed up higher than it was when I got it from Printrbot. When I lowered this my problem seemed to go away.
Answer: I'm not sure if this is particularly the issue for you right now, but I have encountered the tension on my drive gear being too high.
Before I upgraded my extruder to the spring loaded mechanism, my extruder used a Delrin plunger to provide tension against the filament towards the drive gear. This plunger used copper washers to help adjust the tension required. Many people ended up upgrading their assemblies to the spring loaded mechanism as the plunger would either put too much or too little tension against the drive gear. Too little and the filament will not be driven into the hotend. Too much and the filament will grind against the drive gear and the drive gear may begin to "eat" away at the filament (especially when the filament becomes hotter). Obviously, if the drive gear is no longer able to catch on the filament, the nozzle will get clogged.
However, even with a spring mechanism, your tension can become too high. Most of these mechanisms allow you to adjust the tension by tightening/loosening the screw holding down the spring. The "sweet spot" for me is just past when the filament can be successfully driven into the hotend. You can test this if you have control over your extrusion motor by removing the extrusion motor from its mount, leaving the spring mechanism installed on the face of the motor. Then, turn your motor on and try feeding the filament through the mechanism. Starting with no tension on the spring, begin slowly increasing tension by tightening the screw on your mechanism until the drive gear is successfully able to guide the filament through. I might even complete another half turn on the screw to account for varying diameters and plasticity states of the filament as it becomes hot.
Hopefully this helps and please keep us updated on anything else you find.
Comment: Thanks for the info. But this is not the issue I have. As I mentioned, the filament will flow just fine, until it has a short while (about 30 seconds) to be idle. Then it will get stuck again
Answer: This used to happen to me and my Simple Metal often.
The jam was always caused by one of the following:

Feed rate too high (especially on solid layers or long lines)
Temperature too low
Nozzle pushing into previous layer, causing back pressure
Variance in filament diameter

Personally, I have never printed at 195c. I'm always about 225 or 230.
That may seem high for PLA, but then I have stopped having the issues after slowing the print and raising the temperature from 200.
You want to strike the right balance between speed and temp. The slower the feed rate, the lower you can afford to lower the temperature. I think you should start by raising the temperature to 215 and slightly lowering the feedrate.
Also, I have directed a fan at my extruder motor and filament as it enters the nozzle. Keeps the motor very cool and stops the filament softening too early.
Is there a foreign object blocking the nozzle, or does it seem like the filament isn't heating up enough?
Comment: I replaced the nozzle tip with a new one, which didn't help. So it is probably not the problem. I also put a metal object under the detector when the print started, to make sure it is working "in free air" and not pushing into the surface, while I was testing it.
I will try the temp/speed idea and will let you know. Thanks!
Comment: Taking the temp to 230 seemed to help at first, as the filament was flowing easier at the first few moments. But then when I stopped the extrusion for a few seconds it got stuck again :(
Comment: I actually had a jam yesterday after moving my printer. Long story short, I accidentally reversed the extruder motor connector and pulled out all the filament from the nozzle because the motor was reversed. I didn't notice at first and the nozzle jammed because a small string of plastic was left being charred in the chamber.
Answer: I found a solution to my problem, which is very similar to your!
Ok, so first, this clog has nothing to do with the flow rate! speed, retraction, or acceleration!
why? because if it under extrusion or over extrusion, the nozzle would spill more or less filament, but it would not make the extruder clog. To make it clog, there must be something that block the path which make the step driver couldn't push the filament through right? even using your hand.
This problem is call "heat creep", especially if you print small detail things. This is because small details make the filament stay inside the nozzle longer, which the heat eventually make the filament swole up and block the path.
To find out if your problem is cause by "heat creep" or not, try to print something small but tall and print something large overall. If it is heat creep, then the small but tall print would immediately clog your nozzle and make the step driver create click sound. If both print ( small and big ) take the same amount of time to clog your nozzle, then it may not cause by "heat creep".
SO HERE the solution for "heat creep." First and the most important, replace your thermal barrier tube. Second, lower the temperature. Third, check the filament guide components such as the drive gear, bearing, and spring. For example, check the drive gear if it securely screw into the stepper motor. Lastly, check the fan, if it possible, install another fan to cool down the thermal barrier tube. In conclusion, replace your thermal barrier before doing anything else.
I hope this help for you and for many other people!
Alopicaso!
Comment: Thanks for info. For flexible filament is this still the advice regarding cooling? IE I read I thought for flexible it is better to turn the fan off?  Having said that I'm having hot end blockages with flexible...


x88 Max+ Android Hide On Screen Keyboard

Question: This little box is so close to replacing my PC but it has a number of frustrating issues that I would like to fix (it's running Android 9.0).
The on screen keyboard won't go away. I have show virtual keyboard turned off in physical keyboard settings but it still appears.
The enter key enters the currently selected key on the physical keyboard instead of enter. I know how to fix this by rooting the device but I don't know how to root the device (and I'd rather not root the device if I can avoid it).
The cursor keys control the selected key on the on screen keyboard instead of the cursor position on the screen.
Selecting a suggested search term in Google Chrome with the mouse while typing in the URL/Search bar doesn't work (does nothing).
If I can fix the on screen keyboard issues this box will be good enough to replace my PC! Any help appreciated.
Answer: You can use External Keyboard Helper Pro app to do this on the T95Q, I assume on the X88 MAX Plus too (I got rid of mine as it cannot do VPN over Ethernet).


IDE for C, Ubuntu

Question: Looking for a recommendation for IDE. I'm learning to program in C, using Ubuntu. Is Eclipse good enough? or are there better IDE's for C?
Comment: To be honest, it;'s a matter of personal taste, so you should probably try them all & see which you prefer.  Btw, this is a ***very** poorly asked question, probably because your are new.  When you just ask for a C IDE, you may as well Google If you tell us what you want to use it for, what features it must have, we can help you, but, as it stands, you may as well Goole. Garbage In, Garbage Out - no offence intended, but you really ought to read [ask]
Comment: Did you ever choose an IDE? If you did, please either accept one of the answers or post your own answer. Doing so will help others in future. We helped you, please help others.
Answer: I have been a profession embedded programmer for "a few" decades.
Eclipse is what I have always used, in industry, when developing under Linux.
There are probably others, some may even be "better" - if you list some requirements - but Eclipse has been "good enough" for every company I have ever worked for.
Comment: Indeed, Eclipse is one of the biggest, most feature-laden [IDE](https://en.wikipedia.org/wiki/Integrated_development_environment) tools ever made. Though not my favorite, as it has a "designed by committee" feel.
Answer: CLion
CLion is an IDE for C and C++.
Has countless features. Designed to be "ergonomic", meaning wisely designed to be highly productive and useful for daily use by professional developers.
Built by one of the finest creators of programming tools, JetBrains, most famous for their industry-leading IDE for Java (IntelliJ).
Comment: Upvote++ JetBrains are, without a doubt, the best IDEs. Alas, they are not generally free. From memory, CLiion is about $50? But that's ***per annum***.  I use Eclipse for C/C++, AngularJs and PHP. But for Python I use JetBrains' excellent and free - even fr commercial use - PyCharm. They make the best IDEs - if yo are willing to pay (and it's only the price of a beer or coffee a week)
Answer: NetBeans
The NetBeans IDE was originally built for Java, like Eclipse. But now offers C and C++ development as well.
NetBeans is a huge tool, like Eclipse and CLion/IntelliJ, with more features than you'll ever know. Open-source and free-of-cost. Formerly owned by Oracle, now donated to the Apache Foundation.
Comment: Upvote. Although I switched to Eclipse for home coding a few years back. I can't remember why  (probably trying to configure the debugger for PHP); there is certainly nothing wrong with NetBeans. The OP should probably try it and Eclipse & decide for themselves. Despite your "designed bu committee" comment about Eclipse, I prefer its look & feel, but that might just be familiarity.
Answer: Visual Studio Code
It's an open-source editor from Microsoft and is the most popular software for development in the Stack Overflow 2019 Developer Survey. It has extensive add-on support for any languages that you can imagine, with special extensions for non-code files like CSV, JSON, Markdown... files too. You can even debug Linux WSL processes remotely from Windows

Visual Studio Code is a source-code editor developed by Microsoft for Windows, Linux and macOS. It includes support for debugging, embedded Git control and GitHub, syntax highlighting, intelligent code completion, snippets, and code refactoring. It is highly customizable, allowing users to change the theme, keyboard shortcuts, preferences, and install extensions that add additional functionality. The source code is free and open source and released under the permissive MIT License. The compiled binaries are freeware and free for private or commercial use.
https://en.wikipedia.org/wiki/Visual_Studio_Code
Answer: Just to round out the collections, a lot of people use Code::Blocks

Code::Blocks is a free C, C++ and Fortran IDE built to meet the most demanding needs of its users. It is designed to be very extensible and fully configurable.
Finally, an IDE with all the features you need, having a consistent look, feel and operation across platforms.
Built around a plugin framework, Code::Blocks can be extended with plugins. Any kind of functionality can be added by installing/coding a plugin. For instance, compiling and debugging functionality is already provided by plugins!

To be honest, it's not my favo(u)rite, but I have used it, with Cygwin under Windows, when I had a new laptop with nothing else installed & needed something quickly to compete a pre-interview home coding test. It performed well enough, so the OP should probably try it. It does run under Linux
Answer: If you use KDE as your desktop, with  I think is not the default for Ubuntu, you should check out KDevelop - A cross-platform IDE for C, C++, Python, QML/JavaScript and PHP  (Otoh, it does run under Gnome - see "cross platform" - it just needs a little more disk space)

Built on modern open source technology, the KDevelop IDE offers a seamless development environment to programmers that work on projects of any size. It helps you get the job done while staying out of your way.
At the core of KDevelop lies the combination of an advanced editor with semantic code analysis, which delivers an enriched programming experience thanks to a deep understanding of your project. Additionally, KDevelop offers different workflows to assist the coder during the development process. It helps improve the code's quality, verify its functionality and then deploy it anywhere.
Free of Charge, Open Source
KDevelop is available free of charge and is licensed under the GNU GPL

IDE for C, Ubuntu


Easy way to use hardware mixing?

Question: My sound card supports hardware mixing. What's the easiest way to use this feature (rather than on an app-by-app basis, hopefully)?
Answer: I am afraid there is no easy way. It is probably easier to just use pulse audio for this.
Pulse audio does software mixing, but on current machines doing hardware mixing does not really provide advantages.
I you really want to use hardware mixing you have to look up some .asoundrc options and then use some alsa-pseudo-devices in your programs.

Easy way to use hardware mixing?


How to prevent minced chicken from sticking and forming a single lump?

Question: I am not an expert in cooking, so I would like to ask for advice on how to cook minced chicken so that it doesn't stick together. What I want is separated minced chicken as small particles that I can spoon and use for pasta sauce or other dishes.
Thanks!
Comment: Hi dracc, we don't answer very general questions like "how to cook X", because there are too many answers. It turns out that you had a specific problem this time, and asking for a concrete solution, which is exactly the type of question we do. So I changed your title to reflect the exact content of the question, else other users may have cast closing votes thinking that your question is of the general kind.
Comment: related : http://cooking.stackexchange.com/q/32212/67
Answer: The water method works (it keeps the pan from getting above 100°C), but the more generic solution is just to cook it over lower heat, and keep it moving around as it's cooking. (and this works for any ground meat product).
If you let one lump brown too much and form a crust, it'll fuse that bit together.  You then need to break up that bit (I like a spatulas, so just flip over the lump so the browned side is up, and then either squish it or chop at it 'til it's broken down to a smaller size.  Reducing the heat while you're cooking will give you more time to break up lumps before they've fused together.
I generally turn the stove to medium heat, and then add the meat before it's fully pre-heated.  I give it a couple of seconds to brown, then flip the whole blob over and break it up so it's spread throughout the pan ... wait a bit for the bottom to brown again, and then continue flipping and breaking it up.
If you're going to be standing right over the dish, you can use a higher heat, but I generally tend to be doing something else nearby (eg, chopping vegetables) while this is going on, so adjust the heat so it's cooking at a rate where I can get back to it easily.
If you're going to be adding some other chunky item to the minced meat (eg, chopped onion) that won't be impacted from extra cooking time, go ahead and add it after the meat's only partially cooked, as the meat won't stick as well to it as it would to other meat, making it less likely to clump up (or at least easier to break apart should it clump up)
Answer: While the chicken is still cold, add a bit of water (perhaps about 1/4 cup, 125ml per pound of meat). Use your fastidiously clean fingers to break up the chicken pieces in the water. Put it on the flame and stir while the water evaporates. After the water is gone, continue to stir while the chicken browns.
Answer: Add a little oil to your pan then add the minced chicken. Using a wooden fork break it up into large chunks and let them cook a little turning them so to firm them up, you can now start breaking the large chunks up into smaller pieces. They wont stick to each other because they should be almost cooked. Continue the process until all the chicken is cooked through and is in small pieces.
This will also mean your chicken retains it's flavour and texture.
Adding water will give you a rather sludgy concoction!
If you want the mince even finer, you could use a stick blender or a food processor AFTER you have done the above.
Comment: actually, the water boils off ... it's not a problem.  It can make for a different texture, but I wouldn't describe it as 'sludgy'.  (compare Coney Island style chilli vs. Cincinnati style chili)


Possible to take a snapshot of a hard disc and use it in a Virtual Machine?

Question: A bit of a silly question really - but I was wondering would it be possible to take a snapshot of a OS you are running on a computer, the convert it or so it can be run as a virtual machine in VMware or VirtualBox?
Answer: VMware should have tools to convert a physical PC to a virtual machine, making changes in the configuration so that the OS uses the virtual hardware and drivers instead. At work, we migrated several physical computers (servers and desktops) to virtual machines in order to consolidate our computing power. Usually this is done as old hardware is disposed, and replaced by a virtual computer, with a thin client on the user's desk, or to reduce the costs of new hardware in a data centre.
Answer: I'm going to assume from the fact that you don't mention what OS you are talking about that you mean Windows.
This is possible to do, though it is a bit glitchy and there is a good deal of luck involved. I was able to do it myself with Windows 7, with many reboots and a downloaded installation disk image. I used the guide here to do it. I would like to warn you that it is a very difficult task requiring hex editors, lots of experimentation with how VirtualBox images work, knowledge of partition tables, and a ton of free time. I think it took me an entire weekend to make it work...
tl;dr Though possible, it is not a journey for the faint of heart.
Edit: If you're talking about Linux, it is much easier. Though, due to the absence of Licensing issues, I would recommend that you just do a new install inside a virutal machine.
Answer: You can use VMware's VMConverter to take a snapshot of a physical disk and make a VM that is runnable under both VMPlayer and ESX servers.
Answer: Yes, it's possible. The following are 2 articles that show you how to do that:

Turn Your Old Mission-Critical PC Into A VM Before It Dies
Create A Virtual Machine Clone of Your Existing (Windows) Hard Drive

The idea is (as others mentioned) to download VMware vCenter Converter (free of charge, as of the time of writing this message) and use that tool to do this magic as painlessly as possible.
Answer: To add-on to Shannon's point when you are using VMWare Converter...please pay attention to the disk layout. If you need to limit the disk size on the VM you can do a file level copy instead of a block level copy.
For example,
you have a 200 GB Physical Disk. But, you need your VM to be 50 GB only. Under the disks tab of VMWare Converter you can specify the disk value so this way you don't have extra large growable disks.


Running a server when all computers have the same WAN ip

Question: I want to run a server on my machine so that anyone in the Internet may connect to it. But my Broadband internet provider issues the same WAN ip to all the customers while each of them has a different LAN ip. How can I run a server then?
Comment: That's no programming question. Maybe you have more luck when asking this on superuser. As far as I can tell there will be no way to solve this.
Answer: You mention LAN IP, so I'm assuming you have a router or switch in between your PCs and the WAN. In order to setup a single server, for example  web server, to be identified as the sole system for WAN facing services you can either:

Set the system as the DMZ machine, which means that the server is default place for all non routed requests to go to
Use port forwarding

How to go about it depends on what type of router/switch you are using.
Answer: I take it you mean that you have a 'private' IP assigned to you by your broadband ISP (which you see allocated on your Server network interface). Meanwhile, if you try to identify your external IP, its different (which you refer as your WAN IP).
Setting up a server that can receive incoming connections from the Internet requires things like NAT provided from your ISP.
Simply put, someone on the Internet would try to connect to your 'WAN' IP on some port number (say 8081/tcp), and this NAT on the ISP would convert that to your 'private' IP and port 80/tcp (say).
However, if you really want to run a server on such a network, your ISP usually would provide you with a static public IP address rather than the private IP you are seeing now. You will need to talk with him on this and get your subscription modified likewise.
Usually, broadband ISPs give out public IP allocations which might change each time you reconnect. That is an easier thing to handle since you can then get a domain registered and use things like OpenDNS to make your server easily accessible on the Internet.
Answer: Configure port forwarding at your broadband-router.

              .--------.
[PC 1]--------+        |
              |        |
[PC 2]--------+ router +---- DSL/cable
...           :        :
[PC n]--------+        |
              '--------'

(Assuming the computers are connected to the typical built-in switch-ports of a typical consumer broadband router, which provides NAT and internal DHCP service)
The router's WAN (i.e. Internet) IP address is used externally for all PC 1, PC 2 ... (i.e. NAT applies)
If PC 2 is the "server" and has DHCP reservation 192.168.1.2, configure port forwarding at the router so that Internet traffic for port 80 is forwarded to port 80 at 192.168.1.2
Answer: I'm assuming that you are on a standard home internet connection.  If this is a business grade question it may be bit different because of how your ISP handles your WAN IP.
Most likely, your WAN IP is actually dynamic.  For instance, right now my WAN IP may be 188.8.131.52.  In another hour my WAN IP may be reset to a new IP within my ISPs range, so it may change to 184.108.40.206.
The other answers to this question are perfectly correct, in that you will need to set up some port forwarding.  Port forwarding will tell your router (the device that passes your internet connection to various connected devices) to send everything on port x (80?) to a specific LAN IP.  To handle the changing IP provided by your ISP, however, you will also need to use a dynamic dns service like dyndns.  This service will install a client on your server, and do a check every few minutes to see if your WAN IP has changed.
dyndns is easily the most popular service to handle this kind of thing, but there are many more free options.


Example of open source project that has had legal problems with contributors claiming any kind of right over their contribution?

Question: I'm doing some research about Contributor Licensing Agreements (CLAs) and I was wondering if they are not an overkill. I will probably end up using them in the project I work with because I prefer to be safe than sorry, but I would like to know about examples of projects that have had any kind of legal problem with contributors claiming rights over their contribution.
Comment: whoever voted down this question should post a comment at least. CLAs are a complex topic and there are no bad questions about CLAs when you start a project and consider a CLA.
Answer: Vaguely related because Apache contributors are under a CLA, a long time ago there was some feud between JBoss and Apache Geronimo, ... a very long time ago...http://www.theserverside.com/news/thread.tss?thread_id=22337
But these are very rare events and IMHO a CLA is a strong deterrent to contributions. As an anecdote, I was asked once by Google to submit a CLA for a 2 characters documentation typo patch: that was quite ridiculous.
Avoid a CLA if you can. Some licenses such as Apache 2.0 have the CLA baked in.
Or use a simpler approach like Linux and http://developercertificate.org/
No need for a complex CLA process in most cases.


what does this history napoleon quote mean?

Question: What the peoples of Germany desire most impatiently is that talented commoners should have the same right to your esteem and to public employments as the nobles, that any trace of serfdom and of an intermediate hierarchy between the sovereign and the lowers class of people should be completely abolished. The benefits of the Napoleonic code, the publicity of judicial procedure, the creation of juries must be so many distinguishing marks of your monarchy
Comment: Could you provide a source? I don't believe you've copied it quite correctly.
Comment: The statement describes Germans' desire for a 'meritocracy'--rewards and promotions based on merit rather than class distinctions.
Answer: He is saying that the lower, working class people of Germany desire freedom to gain as much, and to have the same respect as the noble or upper class.
Comment: I disagree with your use of the term *working class*. In Napoleon's time Europe did not exactly have a *working class* in the way we conceive it today. The Industrial Revolution had not happened. Pre-industrial society is characterised by an aristocracy and peasants. But the thing Europe did have was a rapidly growing urban middle class. These were the intended and ultimately the actual beneficiaries of the FR and Napoleon. But it would take nearly another half century to the Revolutions of 1848 for it to be realised.
Answer: You would do better to ask this question on the history site, but I will address it briefly.
What you have here is some of the ideology of the French Revolution. Napoleon's campaigns in Europe were ostensibly to carry this to all peoples of Europe, most notably to the German states.
Many will argue Napoleon was simply an imperialist and scavenger. But it was the crescendo of Aux armes citoyens (take up your weapons, citizens), in the anthem La Marseillaise which accompanied the hooves of the French cavalry, at Jena, Austerlitz and elsewhere.
And he put the fear of God into the aristocracies of Europe, including in Britain.


How is the Antim Sanskar of unmarried hindu Women done?

Question: What is the procedure of Antim Sanskar when a unmarried women dies? Does she dress like a bride? Who gives the agni to her pyre?
Comment: Are u asking for married women or unmarried women? I answered the Q for the title it had .. now user Aby changed it totally
Comment: @Rickross in title unmarried and in body married. Mismatch... unclear
Comment: @RaunakThakar clear your question on what you want. Married or unmarried.  Title unmarried and body married. I have rolled back it to your original to clear this doubt because if you want unmarried then body has to be changed!
Comment: Yes I checked the title of the original and answered @AkshayS
Comment: @Rickross I have rolled back to original. What if OP wants unmarried? So the change in title to married becomes mistake in that case!
Answer: The title of your question is asking for unmarried girls. And my answer is for that query.
If you are asking about married ladies then your question is an exact duplicate of :Who should do Antim Sanskar (funeral rites) of married woman?
For Unmarried girls:
According to Baudhayana such women should NOT be cremated. But at the same time it also says that some people do perform last rites for such women.
See the following verses:

Among people belonging to the same ancestry, the relationship based on
  common ancestry extends to the seventh generation. 3
Only a bath is prescribed when a child dies before it is seven months
  old or before teething. 4 When a child dies before it is 3 years old
  or before teething, no offerings of food or water are prescribed, and
  it should not be cremated.
5 The same is true when unmarried girls die.
6 Some do perform these rites for married women, 7but they do it
  just to curry favour with people; ritual formulas are thought not to
  apply to women.
Baudhayana Dharma Sutras 220.127.116.11-7

And, should not be cremated means they have to be buried.
For married women:

Having cremated a becoming wife, dead before, with the fire of the
  vessel, one should get himself re-married without delay [and
  consecrate the Fire again]. (5)
A twice-born person, who is conversant with religious laws, should
  cremate a good-charactered wife of the same caste, who dies before,
  with the sacrificial vessel according to the Agnihotra- method. (6)
One who, having his first wife living, cremates the second wife with
  the Vaitanika is equal to the destroyer of a Brahmana. (7)
Katyayana Smriti Chapter 20

So, for married ladies their husbands should do the final rites. In husband's absence it is the sons who should do it.


Appropriateness of a "Best April Fools Day IT pranks" question

Question: April Fools' day is coming up soon and it's been a few years since I've pulled any pranks off at my company. I'd like to get some ideas from the general populous, but I have a feeling it would get closed pretty quick. So I figured I'd ask here first. While we can twist the FAQ wording around to make it on topic, it's definitely not a productive question. What do the meta spirits think?
Comment: You should probably just ask this in the chat.
Comment: http://www.thinkgeek.com/product/b278/
Comment: http://www.reddit.com/comments/gfy1l/my_version_of_the_voice_activated_printer_april/
Comment: In the company I work atm, they pulled a nice one 2y ago: They sent out a mail telling about a spray that protects you from the dangers of WiFi-signals. You can use the spray to pretect your bedroom, the children's room, ... They also added a nicely photoshopped folder/flyer :)
Comment: Thank you @GroundZero that's awesome. Definitely going on our to-do list for this year
Answer: this would probably fall into the same vein as the "Server Names" question - "bad subjective" because there's no real way to decide what's the "best" prank ever pulled - it would wind up being a list-of-things rather than something of constructive use (though I suppose you could argue that coming up with a creative new way to scare the pants off your employees has some constructive merit it would be a little hard to say it's "professional" :-)

Of course nothing stops you from hopping into chat to talk about pranks - you've got 10 days left to plan!
Comment: K, Makes sense. I figured as much considering a search for April Fools brought up no relevant results. I can't be the first one to have considered asking.
Answer: This sounds like the sort of thing I'd love to read on some forum such as Spcierowks or Rettid.
As a professional Q&A site, this sort of question is completely into the opinionated, would lead to extended discussions, and is strongly discouraged these days. (Note that you can still find a few similar ancient examples in SF's early history, though most all of them should be closed by now.)
Answer: ServerFault is meant to be Q&A about problems and solutions to those problems, not for opinions.
In the strict interpretation of what's on-topic, I'd say this is firmly on the "opinion-based" side of things. After all, it's impossible to have an actual "answer" to this question since there are no right or wrong answers and everything would be based on a subjective basis rather than being backed up by facts.
So, to answer your question: No, I do not believe even a well-written question about this topic would be appropriate here.


If the mean of a random process is constant, does it imply the process is first order stationary?

Question: If a random process is first order stationary, its mean is constant. However, if a random process has a constant mean say $3$ and an autocorrelation equal to $9 + 15e^{|-\tau|}$. The process is clearly wide sense stationary. Is the process first order stationary?
Comment: What is _your_ understanding of the term "first-order stationary"? Be as specific as you can.
Comment: @Dilip By first-order stationarity, I mean the first order density function is independent of absolute time.
Answer: In the usual sense of the term, first-order stationarity means that the first-order distribution of all the random variables is the same: each $X_t$ has the same CDF, and so the same pdf (or pmf) too if the random variables are continuous (or discrete). If the random variables have a mean, then they all have the same mean. But, a sequence of independent
identically distributed Cauchy random variables is a first-order stationary process (as well as a strictly stationary process for that matter) but it cannot be said to have constant mean because none of the variables have a mean at all.
Since your response to my query on the problem statement is that your definition of first-order stationarity is the  standard one, then the answer to the question in the title of your question, viz.

If the mean of a random process is constant, does it imply that the
  process is first-order stationary?

is NO, and an example of a process that has constant mean but is not
first-order stationary is a sequence of constant-mean random variables whose variances depend on time.
The answer to the question in the text, viz.

Is a WSS process necessarily first-order stationary?

ia also NO.  Consider the random process
$\{X(t)\colon X(t)= \cos (t + \Theta), -\infty < t < \infty\}$
where $\Theta$ takes on four equally likely values $0, \pi/2, \pi$ and $3\pi/2$ and so $X(t)$ takes on four equally likely values
$\cos(t)$, $\cos(t+\frac{\pi}{2}) = -\sin(t)$,
$\cos(t+\pi) = -\cos(t)$, and
$\cos(t+\frac{3\pi}{2}) = \sin(t)$.
  It is easy to see that in general $X(t)$ and $X(s)$ have different distributions and so the process is not first-order stationary. On the other hand, $E[X(t)] = 0$ for all $t$ while
\begin{align}
E[X(t)X(s)]&= \left.\left.\frac 14\right[2\cos(t)\cos(s) + 2\cos(t+\pi/2)\cos(s+\pi/2)\right]\\
&= \left.\left.\frac 12\right[\cos(t)\cos(s) + \sin(t)\sin(s)\right]\\
&= \frac 12 \cos(t-s)
\end{align}
and so the process is wide sense stationary, but its first-order distribution does depend the choice of $t$ and so the process is not
first-order stationary.

Note: the above proof uses a very commonly accepted definition of wide sense stationarity as found in numerous books, online resources, Wikipedia etc, viz. a random process $\{X(t)\}$ is called a wide sense stationary (WSS) process if

$E[X(t)]$ is a constant, and
$R_{X}(t,s) = E[X(t)X(s)]$ depends only on the difference $t-s$ of the two arguments and not on the individual arguments $t$ and $s$.
Comment: Ok I've checked all of the (engineering) books in my library on stochastic processes and it seems that the definition of WSS random process agrees with your statement; a process with a constant mean and lag dependent ACF... I've deleted my answer.
Comment: @Dilip Sarwate "but its first-order distribution does depend the choice of t and so the process is not first-order stationary" Is that a typo? Doesn't it depend only on the difference t−s ?
Comment: @VMMF There is no typo. The first-order _distribution_  tells us the values that the random variable $X(t)$ takes on, and these are $\pm \cos t$ and $\pm \sin t$, _very obviously_ different for different choices of $t$. On the other hand, the _autocorrelation function_ $R_X(t-s) = E[X(t)X(s)]$ is a function of $t-s$ which is why the process that I give as an example is _wide-sense stationary_ but _not_ first-order stationary.
Comment: @Dilip Sarwate So as the phase takes 4 different distribution values the first-order density function is not independent of time origin, hence the process is not first-order stationary even though the conditions for wide sense stationarity are present?
Comment: @VMMF You got it!


Up to which rating is my strategy in the opening is applicable?

Question: I don't want to waste time on opening preparation. By this, I mean that I don't want to have to understand/memorize the moves or the typical plans in the middlegame. I just want to develop my pieces, castle the king, and connect the rooks. From there, I wish to wing it, try not to blunder anything, and look out for tactics. Is this enough to reach 2000ELO?
Comment: I think this question has somewhat wrong assumptions. If you play enough and train enough to get 2000 you will automatically learn something about the openings you play. Now, can you get to 2000 without specifically learning openings? I think so, but just because even without focusing on it, by just playing you will still learn something about them.
Comment: True sort of,   but can you get to 2000 without learning openings?  We have a chicken & egg question here.   I f  the OPer would learn tactics, strategy, positional play, and other non openings that he wont learn then he could do it the way you posit.  So in the end he learns openings in spite of himself -- *IF* he makes it to 2000.
Answer: This is an opinion based question as there is no way to know.
For Bobby Fischer it might have been, but I met Bobby and know that he memorized all the openings.
Would it work for you?
My tournament experience says no.
These days there are too many people memorizing everything along with all the better training for tactics than when I learned.
Your more likely ceiling would be 1500, with possibly 1700 IF you were really good.
After that, positional play would start to be a factor and by 2000  most players would beat  you with traps, better/deeper tactics, or positional play.
And since they do know the openings they would come out of most of them with an edge in position as well as the initiative.  So just routine play would give them the edge to win if they were at 2000 already.  And if they do not beat you in the middle game with strategy then they will win in the endgame because they are far better than lower rated players at endgames.
If you want to make even uscf 2000 let alone ELO 2000 you will have to specialize in ONE opening for white and one for black and become so familiar with them that you do not need to memorize them as the moves will be obvious because you do understand them.  And you will have to be totally fluent with ALL tactical motifs and recognize them in different game settings.
Comment: I think you're underestimating the variability in potential of new players. I've known people who made it to 1800 just by grinding tactics. If there's any kind of normal-ish distribution of genetic potential I would be surprised if there aren't some people out of 7 billion who can make 2000, 2200, or even 2400 that way.
Comment: Then I would think you are overestimating the accuracy of ratings when there is insufficiently widespread competition to avoid pockets of  over rated and under rated players.  Tactics might get you to 1800 but  end games and positional play will beat you if you try to get higher without learning openings, strategy, end games, and positional play.
Answer: Whereas the question is very opinionated, I assure you this might strongly depend on the player type. (See the recent book of Müller/Engel.) I had a peak ELO of 2350, clobbering a lot of grandmasters on a good day, and this without any concrete opening knowledge. (Sometimes I even invented a new line ten years before it was played in GM praxis, but those ganeffs never give me any credit :-) Your minimum needs: a good intuition and keen tactics. But woe, in the time of computer outpreparation, it probably doesn't work anymore. Especially if you "don't want to know the plans". You won't get away with that. (Imagine just trading all pieces in the Ruy Lopez Exchange.)
Comment: Did you do it without knowing end games, strategy, positional play, as well as mastering tactics?  I agree that if you know those then you do not need to memorize openings.
Answer: It is not enough. I think you have to respond to your opponent's play. Try to prevent what they are trying to do is the best way, even though you do not have a plan.
Comment: Perhaps at 1600+/-  but  if you always respond to the opponent you will be losing more than winning.   Initiative driving your opponents responses leads to better positions that win material or have a winning end game advantage.
Answer: Personally, I am 1845 ELO and I have not deeply studied any particular openings. Regarding my middle game, I know some basic tactics (grab any hanging pieces, look for weaknesses, gain space, keep your pieces safe etc) and nothing too complex. however, I would recommend doing only 1 opening i all your games and master that opening to the point where you could create your own traps. However, I would not go as far as to say that you should spend time learning particular traps.
Answer: It really depends on whether you're really able to not blunder anything. Surprisingly, it is not so straightforward as it seems. Yet, if you really manage to play like this, I believe 2000 elo is possible.
Comment: I would disagree.  If you do not know endgames then you will lose whenever your opponent did not blunder away material earlier.  And if you do not know strategy or positional play they will get an advantage to ensure they do win the endgame.  You need a lot more than the OPer hopes is needed for ELO 2000.
Comment: Based on my experience ELO 2000  is way beyond not blundering pieces.  I have played GMs in US,  and played internationally too.  You need a lot more than not blundering pieces to beat people at 2000 and up.
Comment: I believe you underestimate the ability of not blundering pieces. 2000 elo is doing this is right and left, due to various reasons. Do you maybe mean the the OP would not be able to convert that advantage?


What are the options for kayak self-rescue without a paddle float?

Question: In a standard kayaking class, you're taught solo self-rescues using a paddle float and assisted rescues using another kayak. Then there are eskimo rolls. But I've also heard about other self-rescue techniques after a wet exit without a paddle float (ladder, cowboy, scramble). What options are there for kayak self-rescues without a paddle float or a friend, and in what conditions would each be used?
Comment: Just a comment that this is a great question because the chances of losing your kayak float somewhere in the process (on the trip, in the cold-fingered moment) are not zero
Answer: Being without a sold "roll", partner, or paddle float can make it quite challenging for a novice to re-enter their kayak after a capsize. However there are techniques which will make it easier to get back in your boat safely.

Note: All of these should first be practiced in mildly shallow water, in flat water. Don't practice in rough water until you can achieve these in flat water. However no self rescue can be called confident until you can reliably perform it in conditions rougher than you like to paddle in. You are most likely to capsize in rough conditions, not flat water, so work up to the challenging stuff. With a partner or group.
Second note: No amount of reading or self study is substitute for a good teacher, and practical experience. Don't think that because you read this article that you now are competent in self rescue. You can only get that from practice. Join a paddle club, and get face to face assistance.
Now that's out of the way...
From easiest to most challenging...
Note: All except the wet entrance and roll should be attempted with a partially empty boat. Do this by tipping the boat from the bow with your body weight and using a quick flip.
Ladder Crawl
Beginning from the back of the boat:

Stow your paddle in the deck rigging, to get it out of your way, and prevent losing it.
Orient so that bow is perpendicular to the prevailing direction of the waves.
Holding the stern, use your body weight to bring the stern under the surface.
Wait for a swell to raise the boat bow further, then make a quick kick with your feet, and launch your torso on top of the stern decking.
Keep your body low, and your legs wide in the water.
Slowly work forward to the cockpit, staying low.
Drop your butt into the cockpit
Kick your legs over the cockpit combing and into the boat.
Pump out remaining water, and reapply the spray skirt.

Rodeo

Same as above, store your paddle in the deck rigging, try to make it perpendicular to the boat.
Orient the boat so that the bow and stern are in line with the direction of prevailing waves.
Approach the stern of the boat perpendicularly and grab onto the safety lines, not bungees along the sides of the boat.
Wait for a wave to raise the bow, then launch your torso onto the stern deck.
Kick one leg over the stern and orient with your head towards the bow.
Follow steps 4-8 above in "The Ladder"

Side-entry without float

Insert paddle into rigging, behind cockpit, and twist to lock into place.

Orient with paddle blade face, "Feathered" against the water. (Increases resistance after weighting, lowering roll chances)
2.Place leg on top of paddle, grab cock pit combing, and kick opposite leg up and into the cock pit.
You will end up face down, looking toward the stern of the boat.

Bring other leg into cock pit (quickly), and twist body to orient towards the bow (slowly).
Remove paddle from rigging.
Pump out remaining water and re-apply spray skirt.

Re-entry and Roll
Note: This is a move usually only achievable by someone with a semi-consistent roll. Also, do not worry about the water in the cockpit unless it is completely full. Water can actually help, because the boat will sit lower in the water.

Leave the boat turned upside down. (Do not flip right side up!)
Orient the boat so that the bow and stern are perpendicular to the direction of travel of the waves.

Waves should be washing over the side of the boat. (Usually a bad thing)

Align yourself along the side of the boat, and grab the cockpit combing with your inside hand.
Slide your legs into the cockpit partially.
Take a breath and slide your legs all the way into the cock pit while submerging your body under the water.
Take your paddle, align it parallel to the boat so that your lead hand (strong) is forward.
In a fast but consistent motion make a 180 degree arc.

Use the weak hand as a fulcrum.
Let the strong hand break the surface of the water.
At 90 degrees drive lead hand underwater by arcing your back and plunging your body deeper under water.
Complete the motion, and finish with your back near the stern of the boat.

Your boat (with any practice and luck) will be on top of the water right side up.
Empty the boat of water, and re-apply the spray skirt.

Next time paddle with a buddy, and a paddle float.
Please see these excellent videos

Self rescue - The Ladder
Self rescue - The Sweep Roll
Comment: Please clarify your note on partially emptying the boat. Maybe you mean either lift the bow up while kicking the legs, or push the stern down with body weight.
Comment: I see no difference in your Ladder Crawl and Rodeo methods.
Comment: Your "Side-entry without float" description is very unclear!
Comment: http://www.users.on.net/~pcarter/rescues.html advocates the reentry and roll, but cautions that high-volume-cockpits are unsafe -- If your kayak isn't stable enough to paddle while full of water, then the rescues set you up for repeated failure in conditions dire enough to need a rescue.
Answer: You can usually lay the paddle across the kayak as if you had a paddle float and use it for stability to climb in. It's not as stable as a paddle float, but it's better than nothing. If there is another kayaker with you, they can pull up along side you and hold the floatless end of your paddle on their cockpit.
You can also climb in over the side without anything for stability if you grab the far side of the cockpit and are careful.

Pull yourself up, perpendicular to the kayak, while you kick yourself out of the water.
End up lying across the kayak, perpendicular to it.
Roll over on your back, lower your rear into the seat, and spin around 90 degrees.
Cram in your legs and you're done.
Comment: Two comments:  One, a Greenland paddle, being slightly buoyant, helps with this.  Two, the critical moment in my experience is getting the butt into the seat.  You can paddle for a bit like that to get stable and properly reoriented to waves then pick an opportune moment to get your legs inside.
Answer: If you are confident and not out of breath, reattach the skirt before the roll after upside-down re-entry (re-entry and roll mentioned above). It takes a lot of effort and maybe a nose plug. But if you can do it, it saves a lot of pumping effort.
Answer: One more piece of gear worth considering, if you plan to do solo trips or group trips in conditions that might separate the group, are inflatable sponsons—-long narrow inflatable tubes stowed compactly alongside the cockpit rim, secured in advance to the hull or rigging.  You can inflate these in an emergency from inside or alongside your boat, making the boat much more stable for any of the reentry methods you mention.  I wouldn't use this instead of a paddle float (as cheap and compact a piece of gear as that is, not much downside to carrying one) but the sponsons are a nice backup in that they are secured to the boat and can't be left in camp, lost in the surf, or lost to wind while attaching to the paddle.


Different Esperanto Dictionaries

Question: There have been many references to different Esperanto dictionaries here such as LaTex, ReVo, etc.  I would like to understand the origin of these and why people rely on one more than the other.  Is there a general consensus as to which is better?  Is one better for one type of vocabulary than another?  Basically, I'd like to understand the differences- strengths and weaknesses of each summarized.
Comment: FWIW, you can conveniently reach PIV, ReVo, and Vikivortaro (and Sonja) from my webpage of Esperanto links: http://www.public-domain-materials.com/folder-esperanto.html
Comment: What do you mean by LaTeX dictionary?
Comment: I mistakenly thought that that was a reference to a dictionary.  It is instead, a type of font.  Please see the answer below.
Comment: To clarify, LaTeX is not a type of font, it's a document preparation system, an alternative to word processors such as Word or Pages.
Comment: Thanks for the clarification, @Miztli
Answer: I believe the two main dictionaries for definitions in Esperanto are PIV and ReVo.
PIV
PIV is the Plena Ilustrita Vortaro de Esperanto. Traditionally it is sold as a very large book but recently its contents can be found online at vortaro.net. It is created by SAT and is generally considered an authoritative source on Esperanto vocabulary. Restricting yourself to only words and usages that appear in PIV is generally a good way to avoid controversy in an Esperanto text.
ReVo
ReVo on the other hand is a collaborative project that can be edited by almost anyone much like Wikipedia. Unlike PIV, the content is freely usable under the GPL license. It was originally based on a very early version of the Plena Vortaro which fell out of copyright, but it has since diverged quite a lot. Due to how it is edited, it tends to be more up-to-date than PIV and more often describes how the language is actually used rather than trying to dictate correct usage. For example, it has articles on neologisms such as ri and iĉ. It is also the source of data for the PReVo and Praktika Vortaro applications. Additionally, it includes translations into many other languages. These can be very useful but it is missing a lot of words and sometimes the translations are misleading.
You might argue that a wiki-style dictionary would be less reliable than PIV, but in practice personally I find ReVo to be a very useful source. Because of it being digital-only, there is a lot more room for detailed definitions and often there are long "remarks" which give very good advice on how the word is used.
John Wells
There is a highly respected dictionary for translation to and from English by John Wells. However, of course, bilingual dictionaries are more useful as a learning aid rather than being an authoritative source on the meaning of a word.
LaTeX
As far as I know, LaTex is not a dictionary, rather it is an unrelated piece of software for typesetting documents.
Comment: I consent. The strength of ReVo as an on-line dictionary is also its weakness: Trends and personal opinions, which may be visible on the Internet, but hardly rooted in the overall speech community, are likely to go in too early, pretending more diffusion than they actually have. _ri_ is a good example. And because ReVo is based on PV from 1930, it misses the evolution having occured since, unless someone supplemented it. So, in case of doubt I would stick with PIV, if there is no very good reason not to do so. It is really not ideal, but still the most professional dictionary we have.
Answer: To Neil Roberts's excellent list I'd like to add Wiktionary, both the Esperanto one, and the English one, which has a surprising amount of Esperanto definitions, for example mojosa. Sometimes, Wiktionary is the only way to find a contested word, such as the rare neologism knufli (not in ReVo). (Of course, like ReVo, W. is a collaborative effort, so use it with care.)

Different Esperanto Dictionaries


Which single-board computer can I use elementary OS with?

Question: I'm looking for a cheap board like Raspberry Pi (which sadly, is not compatible with elementary OS) that is powerful enough to use elementary OS, play 1080p 60hz videos and movies without a lag, and surf the web properly. I will not play any games or do anything else except for these. So, I don't want to build an expensive PC. I've been searching for a board for a while but am unable to find one that is capable of running elementary OS. I'd appreciate some suggestions.
Comment: elementaryOS only makes 64bit images, so no ARM or x86 support, just so you know..
Comment: Is there any info if Juno will support ARM and x86? And when will it be released?
Comment: I don't think so - x86 was supported before but has been dropped due to high maintenance / low user base. About ARM, elementaryOS explicitly focuses on the desktop experience and has no plans to go mobile, afaik, so I don't think they are gonna support mobile processors like ARM. Ubuntu however supports both, so you can look at some of its flavours.
Answer: In short - any 64bit board that's supported by Ubuntu.