Creating Black & White Transparent PNG's

Question: I'm trying to strip all background colour (white in my instance) from an image in order to save out as a transparent PNG so we can upload the images to a webpage with a changing background colour. The desired effect can be seen here - http://thegentlewoman.co.uk/library, if you save image to desktop / open in PS you can see there is no background colour. Any ideas?
Comment: Hi, welcome to gd.SE! this is a very basic Photoshop operation, have you tried searching for tutorials on that?
Answer: Hum. Those images are not striped of a background. The photo itself is just a black square and the alpha channel is the image.

Select your image. Copy it to the clipboard.

Make a new layer. Make the layer black.

Add a mask to that layer. Alt click into the little icon of the layer.

Paste your image on this mask.

You probably need to invert the image. Use the curves.

Remove the background. Done.

Additional steps: You probably need to adjust the levels to make it more contrasted.
Answer: The simplest way to do this is through: Select->Color range - here try to select as much of background as you can; then when you are satisfied with the selection just delete it and save it as png
Answer: You don't need to use a png to achieve what you want nowadays, but it is still doable as you ask for.
Right, now... my real advice is you to play with blend modes within CSS. You can actually make your regular JPG overlay a coloured background, and not just overlay, there are many modes available. Here is a link for a great tutorial, since it has tons of options and it would take lot of guessing to find the one you fancy at the end. Tutorial and CodePen
If you want the "PNG" version, you just need a Photoshop action which is older than many in here xD . I got it in 1999 from a site called ActionXchange, which later Adobe bought and morphed it into AdobeXchange, which is now what you know as Creative Cloud.  It works like a charm: You can download it from here.
It is my personal cloud server and it's a direct download so feel free.
Just remember, to make it work properly your file has to be completely flattened.
EDIT: Forgot also, your Photoshop needs to be in english, when you flatten your file the background layer is named "Background" and its directly related to the action, if you have your PS in spanish or other language, the layer name would change when flattened to something different and the action wouldn't work. (old school, but hey... it works!)
Answer: You can also use the Magic Wand to select your background, delete it, and then save as .PNG and it will preserve the transparency.
Comment: I don't think the magic wand tool is the right tool for the job at all. Did you take a look at the link in the original post?


Has anyone done any work specific to experimenting/creating formulaic math evaluations for the purpose of defining musical patterns?

Question: I realize the question may sound too broad or unclear but specifically, I was recently thinking that you could take a certain genre of music, or a certain composers' works, and mathematically define the reoccuring patterns within the music.
For example, I appreciate Steve Reich's ability to incorporate math into music. You hear just a few notes but it is still a very complex equation. He invokes this sense of floating in a vast sea of numbers, (for me), in a very fluid linear system of playing. His goal seems to be creating a sonic architecture and math as music. Those same experiments in sound, if applied in a visual sense could be turned into plans for extravagant buildings... right?
Comment: This may interest you: http://tones.wolfram.com/generate/
Comment: You might be interested in "computational musicology"; also in the music of Iannis Xenakis.
Answer: Yes! What I find fascinating is you can find mathematical thinking is many different music styles.
Two books that examine 'classical' style:
The Math Behind the Music (Outlooks)
by Leon Harkleroad
Link: http://amzn.com/0521009359
A Geometry of Music: Harmony and Counterpoint in the Extended Common Practice (Oxford Studies in Music Theory)
by Dmitri Tymoczko
Link: http://amzn.com/0195336674
Answer: You may want to look into the music and theoretical writings of George Perle. Generally the search fro patterns in music is going to be style specific so it depends what style you're talking about. It's also difficult because repetition in music isn't always exact so it can be difficult to quantify. In earlier classical musical styles you could look into Robert Gjerdingen's book "Music in the Galant Style" which talks about commonplace patterns in classical music, but is not very mathematical in its approach.


Can I transfer Steam games from one steam account to another?

Question: I want to play Dota 2 with my friend. However his Internet connection is so slow that it would take him about 2 days to download it and then it will be throttled. I am thinking of transferring the version I downloaded per USB-Drive to his Computer and account. Since this is a free game anyways. Would this work or will there be problems?
Answer: Yes, you can copy steam game files from one computer to anther to avoid having to download them again.
Simply copy the game files from the 'common' folder of the steam library where they are installed. By default this will be something similar to:
C:\Program Files (x86)\Steam\steamapps\common\GAME NAME
On the second machine copy these files to it's 'common' folder, then install the game as usual. When the steam installation gets to the bit where it would normally download the game files it will display 'Discovering existing files' instead.
Once it has finished discovering the existing files you'll be able to launch the game.
If you follow these steps and steam starts to download the game (instead of discovering the existing files) that means the files haven't been copied to the correct 'common' folder.
This will work between different computers and accounts as long as the game is free, or as long as the new account owns/buys the game.


What's the best location for a Continue button on multi stage Mobile App?

Question: My app has multiple pages, each page the user adds info and continues to the next page. Where is the best place for the Continue control? Bottom & Centered for hierarchy or top right for consistency?
Answer: It is logical to have "Back" and "Continue" next to each other for symmetry, but a button for going to the next page after filling in information is typically at the bottom, since it follows the user's flow of filling in the form from top to bottom.
Why not have both "Back" and "Continue" at the bottom?
Also, I might consider "Next" instead of "Continue", since it seems to pair better with "Back".
Update: the placement of the on-screen keyboard is a legitimate concern, as mentioned in the other answer.  That may affect whether the bottom is a viable location.
Comment: @YonatanGalili, that might leave the user confused, as they would not know that there are more pages of information, and there would be no clear way to submit the form.  I think you do need the buttons, though also allowing swipe is a good idea.
Comment: I think you're right. What about using only swipe left/right and getting rid of the Next/Back buttons altogether?
Comment: If the multiple views were incorporated into a view pager with indicator that should reduce the chances of confusion. You could also include a swipe right hint on the first page.
Answer: I think it depends on the platform you're designing for. If it's iOS, then the standard is to put the "Continue" button at the top.
The reason behind this is the keyboard: when the user starts typing info in the "Placeholder" box, then the keyboard will hide the "Continue" button. Note that you can have the continue button on the keyboard itself.
Personally I wouldn't go for the back button at the bottom as it is not a standard pattern.
Comment: I think the real answer is that the Next/Continue button actually *should* be at the bottom of the page, but more importantly, **the Enter key on the keyboard** (labelled as Next) **should also serve the same function**. I disagree that having the Next button at the bottom of the page is not a standard pattern; it very much is, especially on modal-like screens, on all devices (picture an app log-in screen).
Answer: One article from the Nielsen Norman Group (4 iOS Rules to Break) suggests that you put your Submit/Continue/Next buttons at the bottom.

Even in iOS apps we recommend against following this pattern [putting the submit button at the top] for the simple reason that it goes against the natural top–bottom workflow on the page. As users fill in the form, they usually do it top to bottom. When they get to the end of it, they expect to find a Submit button right there, next to the last field they have completed.

This all falls back on what your user should expect. You could train your users to expect where the Continue button should be.
While I'm not sure of the exact nature of the form you shared I'll use it as an example:

When the user enters the Title, it should be very obvious that they need to press Continue. When they move on to the next page, they're still expecting a Continue button at the bottom. Even if the keyboard overlaps or changes the view in some way the user should expect a Continue button at the bottom based on their experience on the previous page.
Answer: The top '< back' and 'continue >' links are used as sign posting and orientation for navigation, whereas your button indicates a clear call to action.
Think of the flow and order of interaction. It should be in context with the investment from the user. If the user is filling out something, it makes sense to confirm it after the interaction. To ask them to confirm it outside of this context is disorientating and unnatural.
If you write out your interaction as a set of written instructions, your design would naturally follow this order. If your wrote your interactions out with 'continue >' at the top, the instructions would be out of sequence.
Hope this makes sense!?
Good luck!


How to download Firefox via command line FTP

Question: I am attempting to install Firefox on my Mac, which currently does not have a browser. From a bash terminal I have ftp installed and am currently connected to the internet. However, I have been unsuccessful in connecting to their FTP server.  How do I go about installing Firefox for my Mac via the command line?
Comment: The Safari browser is a default part of the OS X, did you delete it and if so, curious as to why?
Comment: Can your client use `http` protocol? See this [Mozilla support issue](https://support.mozilla.org/en-US/questions/1078139).
Comment: I was installing it for a friend.  Their OS X had safari installed but on the launcher it showed a cancel sign over it, and when attempting to launch it an error would occur in regards to the version of OS X.  I thought it may be necessary to update the computer's operating system to the newest version in order to get safari to work, so in the mean time I just installed firefox to give basic browsing functionality via firefox
Comment: You may be able to launch Safari anyway by starting the binary from a shell. Inside the app there is contents/MacOS/Safari which when started from a shell (e.g. bash) often bypasses restrictions launchservices might impose (such as rules from info.plist). If the app is broken that won't work of course.
Comment: I'll give it a try next time I have the computer in front of me, I'm familiar with launching binaries in linux so I imagine it is very similar. However, it is likely the app could be broken.
Answer: You can skip the download step, and mount it directly over the internet like so:
hdiutil attach https://ftp.mozilla.org/pub/firefox/releases/43.0.4/mac/en-US/Firefox\ 43.0.4.dmg

Saves a step, time, and storage space!
Comment: That's pretty neat! :) +1
Comment: It's one of those hidden gems that Apple sneaks in. I tried attaching directly over the internet like that many years back to see if it would work, and it actually did. Definitely a neat trick. ;) Of course, I realized afterwards that it's mentioned in the man page. Heh.
Comment: You're mounting it over HTTP, which is pretty insecure. Does the command support HTTPS ?
Comment: Fair point. Fixed! Yes, it does support HTTPS.
Answer: ftp access to ftp.mozilla.org was turned off (see this, thanks Davïd). However, you can use curl from the command line:
curl 'https://ftp.mozilla.org/pub/firefox/releases/43.0.4/mac/en-US/Firefox%2043.0.4.dmg' >~/Desktop/'Firefox 43.0.4.dmg'

That gets the latest (as of this writing) US English release for Mac OS X of Firefox.
You can get a directory listing thusly:
curl 'https://ftp.mozilla.org/pub/firefox/releases/43.0.4/mac/'

That outputs HTML, but it's pretty simple HTML, so it shouldn't be a problem reading it to get a different language. You can also chop additional elements off the path, for example if you want a different version:
curl 'https://ftp.mozilla.org/pub/firefox/releases/'


Submit Major Version from Microsoft Flow, without content approval

Question: Is it possible to publish a major version of a document using Microsoft Flow, specifically when Content Approval is disabled?  I cannot see any relevant Flow actions that might accomplish this for me.
Answer: You can enable check in and check out for the document library and use "Check in file" action in Microsoft Flow to publish as a major version.
Comment: Perfect! I'll also note that I didn't have to enable check in/check out on the library. I just added a check out action followed by a check in inside the flow, and a major version was published. Thanks!


Bike stops Suddenly after 2 to 3 Km

Question: I have a Royal Enfield 350 Classic,15000km and 4 years old.
These days I am facing a problem ,it stops after a few kms. I was on highway and it stopped so I visited a mechanic he said there is water in your petrol tank ,he cleaned petrol tank as well as carburettor.After few days again same problem, now this time I visited authorize service centre of Royal Enfield , they are saying there is a lot of rust in petrol tank and rust in your petrol on off switch ,so they changed the switch and cleaned the petrol tank as well. .But after taking my bike from the showroom again same problem.I don't now why it occur ? now this time showroom guys saying the there is some problem in your engine so it is cutting fuel supply
Can someone please suggest me what could be the reason and what should i do?
Comment: Have the carburetor cleaned as that may be the issue, then purchase your fuel from a different, quality, supplier.
Comment: yes sir ,the road side Mechanic and showroom guys both had clean the carburetor and I also change the petrol ,last time I I fill petrol from shell extra premium petrol .   still problem ..?? Engine proble.????
Comment: soo after concern with showroom engineer  , he says engine oil is leakage through towards to spark plug.
Comment: Your gas tank breather hole may be plugged. Try riding with the gas cap open a little and see if the problem goes away.
Answer: When it happens again, check spark plug has spark.
Comment: sir , right now the Bike is in Showroom and its not starting, may be there is no current in spark plug because of oil leakage.
Comment: @RahulBhardwaj I'm not sure how the oil leakage would stop the current in the spark plug. It could be some issue in the ignition coil, in the spark plug itself, or maybe wiring.

Bike stops Suddenly after 2 to 3 Km


Is there a universal label for the sustainability impact of a specific coffee product?

Question: I am interested in the environmental impact of coffee and am therefore wondering whether a system exists for labeling the environmental impact of coffee. So not so much brands, such as Fairtrade, but rather if it is possible for the consumer to get information about how sustainable the plantation associated with the specific coffee product (beans, grounds or powder) is, and if there is a scale to measure it?
Comment: Isn't it also related with how you brew it? Where the heat comes from for brewing? Seems quite unlikely but very environmental-unfriendly: a psychopath may kill seals and use their bones to light up a fire to brew his/her coffee. Even, isn't it related to how you digest it? Did you burp or not after the cup? Final words: I think it is nearly impossible to measure (then quantize and label) the cumulative environmental effect of the final cup of coffee. Sustainability... This is even harder than classifying environmental effects as it also includes social and economical issues...
Comment: The short answer is "No". You can only trust your local third wave roastery. The only thing that comes close to some label would be a european certificate for organic farming (not sure if there is a US equivalent and even less sure about other parts of the world). At least there you have some legal guidelines and you can make some educated guesses about environmental impact. However there is no scale or anything...who would measure these things on a farm level? Coffee is most of the times produced on small scale farms (Fair Trade alone represents 500k or so). It's absolutely impossible.
Comment: @MTSan I really feel that your situation presented is a bit far-fetched. I mean take organic meat for example: if you cook it in a fire of banned substance, then is it no longer organic?
Comment: @AnthonyPham Hi. I don't know what's far fetched. The question is "universal label for sustainability". I think, the question itself is far fetched. However, UTZ, rainforest alliance and fair trade have all visible problems. So... This, just by itself is a really hard issue. (This is why I prefer to not answer but discuss in comments, also.)
Answer: There is no universal label though there are various labels for coffee sustainability.
You can't really have an universal label as each of the labels have their own standards which have to be met and various coffee farms and producers follow certain ones. For example, in the Huffington Post, it mentions some of these labels:

USADA (or simply USDA): This is basically the United States' label for organic for various products (i.e meat and fruits) that is not limited to only coffee. It is quite strict (has certification agencies, checks for criterion not only during production but also distribution and packaging) as it

Aims to promote and enhance natural soil activity and cycling of resources, which helps to create a rich and fertile substrate for the crop and maintain ecological balance by prohibiting use of artificially produced (synthetic) agrochemicals.

As mentioned by @avacado1, there is an European equivalent to the USDA, which is the EU Organic Program (note that the EU doesn't cover all of Europe). Source
Some companies like Starbucks have their own labels that guarantee their standards for their coffee:

C.A.F.E. (which stands for Coffee and Farmer Equity) evaluates the economic, social, and environmental aspects of coffee production in order to ensure that Starbucks's sources of coffee are sustainably grown. Starbucks collaborated with Scientific Certification Systems (SCS), a third-party evaluation and certification firm, to develop the guidelines for the program.

Rainforest Alliance Program: This is a more "natural" certification since:

With this program, coffee is grown on farms where forests, rivers, soils, and wildlife are conserved and workers are treated with respect, paid decent wages, have proper and safe equipment, and are given access to education and medical care.

Bird Friendly Conversation: This label ensures that the coffee farms support the native and migratory birds that come over for a visit:

The Smithsonian Migratory Bird Center (SMBC) gives this certification to farmers in order to promote shade-grown organic coffee plantations that can play a key role in the conservation of our global environment and of migratory birds that find sanctuary in these forest-like plantations.

So as you can see here, the various labels not only have various standards and goals but have their own area jurisdiction as well, each trying to gain support based on what they are.
Answer: I was at Ikea the ither day and noticed that their coffee is UTZ certified. I've never heard of this before so I looked into it.
"UTZ is committed to creating a sustainable, viable coffee market. How? Through an efficient certification and traceability program for socially and environmentally responsible coffee production that meets the needs of both producers and markets."
That's straight from their site. Check them out for more info:
https://utz.org
Comment: I have checked this and also read a comparison with Fair Trade and Rain Forest Alliance. UTZ seems like it does not care for the usage of chemical fertilizers or pesticides. Also, it does not care for supporting local populations. Thus, it is financially easier to have this certificate. One advantage is, they care about worker wages and ages. Mostly, this looks like an alternative (cheaper) certification. (Note: IKEA coffees are UTZ certified.)
Comment: Ah ok, good to know. Kind of misleading, I would think you should care about chemical usage and support local populations to ensure a sustainable and viable coffee market.
Answer: I answered a similar question a while back on the following thread.  Although it is slightly different, it may contain some information that is applicable, or you may be interested in.
Coffee Stack Thread
There is no universal sustainability grade for coffee plantations that I know of.  Many times coffee comes from individual shareholders that don't own much more than a coffee 'garden', much less than a plantation.  Because of this, it is basically impossible to assign a grade to all sources of coffee.  Additionally, many coffee farms are far off the beaten track.  There's a story in the link I posted that describes the difficulty in reaching some of these coffee plantations.  Consider that most coffee is high grown, much of it between 1800 and 2000 meters in elevation.  This is pretty much up in the mountains where large cities, significant infrastructure may be lacking due to the terrain.
From a roasters perspective, I am able to find lots of coffee coming from farms that focus heavily on sustainability, but they are typically microlots and they are typically quite expensive.  Also as a roaster, it is to my benefit to tell the end consumer all about the farm and what they do for sustainability, because like you, a lot of individuals are interested in knowing that type of information.  I would keep an eye out for specialty roasters and just go read the informational pages on their coffees and you should be able to find coffees very quickly that come from farms that focus sustainability.
One other tidbit of information.. There are certain countries that regulate the export of coffee in such a way that the majority of coffees are lumped into the same lots, and you lose all traceability.  Ethiopia's ECX exchange is an example of this, and much of the Colombian coffee trade is regulated by the government.  (there are microlots coming from both these countries so this isn't an 'avoid these coffees' warning or anything ... avoid Ethiopian coffee.... the horror!)


Is it possible to take screenshots on the 3DS?

Question: In Pokemon X and Y there are specific locations in the game that allows you to save what are essentially 3D screenshots from the upper screen using a virtual camera. This made me wonder - is it possible to take screenshots, 3D or otherwise, from within the 3DS?
Answer: In many cases, yes.
There is no "save screenshot to SD card" feature in the 3DS as of right now. Some games allow you to take pictures under certain conditions (the camera man in Pokémon XY, the camera in Pilotwings Resort, pressing L + R in Animal Crossing New Leaf, etc.), but this differs from game to game.
With the Miiverse, however (which was added to 3DS in a firmware update), you can post whatever is on screen at the time if that particular game has a Miiverse community (and you are able to bring up the home menu, of course) - and then only in that particular community. After posting a screenshot on Miiverse, you can then access the image via Wii U, 3DS or the Miiverse site.
Comment: you can also get unofficial screen recorders
Comment: @qwertyk31 Yes, such as [this one](http://3dscapture.com/), but that saves video and images externally - not on your 3DS.
Comment: The inclusion of the Miiverse on the 3DS was mainly meant as a way to unify the 3DS store and the Wii U one, as people have started complaining about having to buy funds cards for both and having to buy GBA games on the Wii U, despite already owning them on the 3DS (through the 3DS Ambassador program). Still, it would be awesome if you could post screenshots from the 3DS onto the Miiverse as well.
Comment: @Nolonar "was mainly meant as a way" - It's not even out yet. Nintendo has only mentioned the NNID eShop merging so far, but it's not out of the question that it'll add more features related to NNID than that.
Comment: Miiverse *does* let you share screenshots on the 3DS. It's not exactly easy to do, since it requires you to go to the home menu and into Miiverse, but you *can* take screenshots now.
Comment: @Unionhawk Managed to forget about this answer, thanks for reminding me to update it!
Comment: Note that Miiverse will not allow you to post a screenshot if the game has the 3DS camera turned on.  (Presumably, this is to prevent people from posting inappropriate photographs.)
Comment: Miiverse is [being shut down](https://miiverse.nintendo.net/posts/AYMHAAADAAADV44YslslXw). =/
Comment: as of Nov 7th, 2017, it's no longer possible to do screenshots through Miiverse (RIP).
Answer: If you have custom firmware installed on your 3DS, there are many homebrew tools able to take screenshots:

If you have Rosalina, press L+Down+select to open the menu, then select "Take screenshot (slow)". It's indeed slow (about 10 seconds), but otherwise woks fine, even with extended memory games like Pokemon X/Y.
If you run the game via TestMenu, suspend it using Home, then press L to take the screenshot. I'm not using this tool so cannot tell how well it works.
Answer: If you pause in "super smash bros" during a single player (and maybe multiplayer), L and R will take pictures which you can see in the 3DS camera along with your other pictures.


What is difference between standard VLAN extended VLAN?

Question: I know that the range of standard VLAN is 1-1005 and in extended VLAN the range is 1-4094.
But is just range is the difference?
Answer: VLAN are introduced by the IEEE 802.1Q standard, which doesn't have this notion of standard or extended VLAN, nor made any difference between VLAN under or above 1005.
This is Cisco implementation that introduce this segregation.
The first Cisco implementation actually supported only VLAN up to 1001, and Cisco reserved VLAN 1002-1005 for FDDI and Token Ring. They added support for VLAN 1006-4094 later, and called them "Extended VLAN". My guess is that since it was an addition, and probably to enforce backward compatibility, those VLAN are technically different, within Cisco IOS
Quoted from Extended VLAN ID (Disclaimer: this document date from 2007 and part of the content may be outdated)

Before Cisco IOS Release 12.4(15)T, users were permitted to configure
  VLANs numbered from 2 to 1001. The remaining VLANs (numbered from 1006
  to 4094) were reserved for use as internal VLANs configured by
  applications. Beginning with Cisco IOS Release 12.4(15)T, all VLAN
  numbers except those reserved for default and reserved VLANs are
  available for user configuration. The result is that users and
  applications share the VLAN number space from 1006 to 4094.

You can find in this documentation for example this table:

Note that as pointed out by @Andriy Berestovskyy this table is outdated and Extended VLANs are propagated by VTP version 3
Comment: Extended VLANs are propagated by VTP version 3. The link you provided is a bit outdated.
Comment: You're right, I was mainly focus on the fact that this is a Cisco-only distinction, but I agree I shouldn't include misleading /outdated information. Will edit.
Comment: You are right, it is a Cisco-specific question. That is why my answer is more precise ;)
Comment: It is not clear that the question is Cisco specific as the OP didn't add the Cisco tag (while using several other tags). Cisco has great documentation and courses but this could lead people to think that Cisco version is the standard, but it's not always the case.
Answer: AFAIR, there are just two differences:

Only VTP version 3 supports extended VLAN propagation:

Support for extended range VLAN (VLANs 1006 to 4094) database propagation. VTP versions 1 and 2 propagate only VLANs 1 to 1005.

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3560/software/release/12-2_52_se/configuration/guide/3560scg/swvtp.html#wp1316856

Extended VLANs are VTP pruning-ineligible, i.e. they have to be pruned manually:

Extended-range VLANs (VLAN IDs higher than 1005) are also pruning-ineligible.

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3560/software/release/12-2_52_se/configuration/guide/3560scg/swvtp.html#wp1308874


How secure is ISA Server 2000

Question: We have a small office using ISA Server 2000, previously this was connected to the internet through another firewall provided by the business park we are at, but soon will be connected directly to the internet. Is this a high security risk given its age, with all patches installed, will it still give adequate protection until next summer when it goes EOL and we have to upgrade the small business server or is it a high risk that would need immediate attention. This is a standard office with no internet servers attached.
Answer: It's safe. I would sleep easy.  Just install all the patches.
Answer: I think there are no problems keeping your ISA in place as long as it is properly configured and updated.

How secure is ISA Server 2000


Beer left fermenting 2 months

Question: Brewed beer in 5 gallon bucket in my nyc apt then had to leave town bc of covid. Been sitting there 2 months. Will it be smelling up my apt or building?  the water on airlock has surely evaporated. What to expect for smell ? Wont be able to go there to ditch it for 1 more month. Should i worry?
Comment: Since there's nothing you can do anyway, is there really any point in worrying? Whatever you end up going home to is exactly what was always going to be there, no matter what you do in the meantime.
Comment: Well if someone knows if it will be smelling terrible,  then I could get someone (pay) to go in and remove it. Rather than have neighbors complain and call landlord or police. Just trying to see if anyone knows? Has anyone left beer in bucket for 3 months?
Comment: Is your appartment in a basement?  Any air conditionning?  Temperature could influence the results...
Answer: Two months is not too much, if the temperature is not too hot.
Best scenario, you could be lucky and still have some water in the airlock.  Beer might be fine.
Worst scenario, water has evaporated in the airlock.  Beer has a great risk of contamination or spoilage.
As for the smell, it will depend on temperature as well.  If the airlock is dry and the temperature rises, so will the smell.  If you can send someone to get rid of it, you could also send someone to fill the airlock, giving you more time?
Comment: Thanks for the advice. The temp probably hasnt been bad yet- left a window cracked open when i left, but the weather is getting warmer now in nyc.and potential to start stinking is there. I just dont want anyone thinking there is a dead body in there!
Answer: 2 months is fine.  Lots of people will leave their beer in a secondary fermentor longer than that.  The only issue you'll have is that your beer might be oxidized and taste old because the cheapo plastic bucket fermentors generally aren't terribly air tight and are only good for the primary fermentation.  If it was in a carboy or more airtight vessel, it would be perfect.
As for smell, it won't.  I once forgot to clean out a fermentor after bottling and had it sit in a hot garage with about half a gallon of beer and the yeast cake for the better part of a year without odor.

Beer left fermenting 2 months


Is Genesis 1 a type of Hebrew Poem?

Question: Is Genesis 1 structured so that there is a general category and then with what will fill it, which would be a type of Hebrew poem of parallel ideas?  In this case day one (light), would relate to day four (sun, moon, and stars) while day two (sea and sky) would relate to day five (birds and sea creatures) and day three (the land & vegetation) with day six (animals and humanity).  Does this indicate that it is a type of creation poem or song?
Comment: Related: https://hermeneutics.stackexchange.com/questions/26478/does-the-literary-content-of-genesis-1-compel-the-conclusion-that-it-is-a-fictiv
Answer: Not poetry, but Prologue
Gordon J. Wenham notes in The Word Biblical Commentary Vol. 1: Genesis 1-15 on page 46

...[Genesis 1:1–2:3] stands apart from the narratives that follow in style and content and makes it an overture to the whole work.

On page 50 he continues:

Extrabiblical creation stories from the ancient Near East are usually poetic, but Gen 1 is not typical Hebrew poetry. Indeed, some writers endeavoring to underline that Gen 1 is pure priestly theology insist that it is not poetry at all. There is no "hymnic element in the language" (von Rad, 47). On the other hand, Gen 1 is not normal Hebrew prose either; its syntax is distinctively different from narrative prose. Cassuto (1:11 [1961]), Loretz (1975) and Kselman (1978) have all pointed to poetic bicola or tricola in Gen 1, while admitting that most of the material is prose. It is possible that these poetic fragments go back to an earlier form of the creation account, though, as Cassuto observes, "it is simpler to suppose … the special importance of the subject led to an exaltation of style approaching the level of poetry" (1:11).
Gen 1 is unique in the Old Testament. It invites comparison with the psalms that praise God's work in creation (e.g., 8, 136, 148) or with passages such as Prov 8:22–31 or Job 38 that reflect on the mystery of God's creativity. It is indeed a great hymn, setting out majestically the omnipotence of the creator, but it surpasses these other passages in the scope and comprehensiveness of vision. In that it is elevated prose, not pure poetry, it seems unlikely that it was used as a song of praise as the psalms were. Rather, in its present form it is a careful literary composition introducing the succeeding narratives.

(emphasis added)
And indeed, scholars like McBride1 and Waltke2 also regard Genesis 1:1-2:3 as prologue and The opening prologue of Genesis has been compared to the opening prologue of John by several scholars. Subsequently, it is pretty clear that this writing was intended to act as a prologue or overture to the book of Genesis.
Correspondence of days is a framework
While the correspondence of days is present in the structure of Genesis 1, this represents a literary framework, but it does not equate to poetry itself. There are some poetry-like elements within the text however. Whenham notes some of these on page 50 of his commentary:

1:1–2:3 form the first section of Genesis; the second starts with 2:4. 2:1–3 echoes 1:1 by introducing the same phrases but in reverse order: "he created," "God," "heavens and earth" reappear as "heavens and earth" (2:1) "God" (2:2), "created" (2:3). This chiastic  pattern brings the section to a neat close which is reinforced by the inclusion "God created" linking 1:1 and 2:3.
The correspondence of the first paragraph, 1:1–2, with 2:1–3 is underlined by the number of Hebrew words in both being multiples of 7. 1:1 consists of 7 words, 1:2 of 14 (7 x 2) words, 2:1–3 of 35 (7 x 5) words. The number seven dominates this opening chapter in a strange way, not only in the number of words in a particular section but in the number of times a specific word or phrase recurs. For example, "God" is mentioned 35 times, "earth" 21 times, "heaven/firmament" 21 times, while the phrases "and it was so" and "God saw that it was good" occur 7 times.

Conclusion
Genesis 1:1 is almost, but not quite a poem or hymn. As such it rises to the level elevated or high prose and acts as a prologue to the book of Genesis. It also repeatedly invites polemic comparison to other creation myths in Mesopotamia.

1 Dean McBride Jr. "Divine Protocol: Genesis 1:1-2:3 as Prologue to the Pentateuch"
2 Bruce K. Waltke Genesis: A Commentary
Comment: @Mr.Bultitude I'd call it [constrained writing](https://en.wikipedia.org/wiki/Constrained_writing) rather than elevated prose
Comment: Very helpful. The comparison to gJohn's prologue could use some nuance, though. It sounds as if you're suggesting that because gJohn has a prologue, and it's similar to Genesis, then the opening of Genesis must be a prologue too. Maybe you don't intend that, but it comes across that way. Note, too, that [Endo's book](https://goo.gl/tui8rC) (your Amazon link) has *very* little to do (almost nothing) with Genesis 1, and doesn't belong in that list. The general point (association of Gen 1 and Jn 1) is not controversial, though. In any case, this connection doesn't really bear on OP's question.
Comment: @Davïd - no, that *is* the intention. By nature of the comparison, Genesis needs to have all of the elements of a prologue - assuming that we can accept John as having a prologue as well. Did it not have the elements, the comparison never would have been made in the first place, or it would have been a contrast intended to prove genesis *isn't* a prologue. This also helps to illustrate that many scholars regard it as prologue, and it wasn't just one scholar's throw-away observation - there is a general consensus on that point.
Comment: Could you define "elevated prose"? What separates it from "normal prose" other than containing elements of poetry (if anything)?
Comment: I think it is supposed to be a sort of "in-between" descriptor. Shakespeare's plays are sometimes regarded as elevated prose in that they have a meter and verse, but aren't truly poetry. Yet they aren't regular prose either.
Answer: As the question recognises, Hebrew poetry is very different from Western poetry and thus difficult to recognise initially. We have to look for parallel ideas, rather than rhyme and rhythm.  Francis S. Collins (The Language of God: A Scientist Presents Evidence for Belief, page 140) says, "There is no question that this is a powerful and poetic narrative recounting the story of God's creative actions."
Jeff A. Benner ('Poetry in the Hebrew Bible') finds multiple levels of poetry in the first creation story (Genesis 1:1-2:3). First, Benner defines a chiastic structure for this passage, although I would regard it as a parallel structure (one in which the second set is not reversed). Either way, this is a form of poetry common to ancient Hebrew and Greek:

A. Elohiym filled the sky and the land because it was empty and it was all in chaos so the wind of Elohiym settled upon the water (1:1 to 1:2)
       A1.   Day 1 - Elohiym separates (1:3 to 1:5, Day one)
                 a. light
                 b. dark
            A2. Day 2 - Elohiym separates (1:6 to 1:8, Day two)
                      a. water
                      b. sky
                 A3.   Day 3 - Elohiym separates(1:9 to 1:13, Day three
                           a. land
                           b. Plants spring up from the land
       B1.   Day 4 - Elohiym fills (1:14 to 1:19, Day four)
                 a. the light with the sun
                 b. the dark with the moon
            B2. Day 5 - Elohiym fills (1:20 to 1:23, Day five)
                      a. fills the water with fish
                      b. fills the sky with birds
                 B3.   Day 6 - Elohiym fills (1:24 to 1:31, Day six)
                           a. the land with animals and man
                           b. Plants are given as food
B. Elohiym Finishes his separating and filling of the sky and the land and respects the seventh day because in it he did his occupation (2:1 to 2:3, Day seven)

At another level, Benner says when we read Genesis chapter one we usually see only one story there, but there are actually many stories. Important to his explanation is that the Hebrew word bara is better translated as 'fatten' or 'fill'. His poetic translation of chapter 1 can be read in full here, but the following is an extract:

Genesis 1:1-2: (Filling the Void) In the beginning the Mighty One filled the skies and the land because the world existed devoid and void. A chaotic void was over the face of the deep then the creative breath of the Mighty One hovered over the face of the water.

Poetry is so commonly used in the Old Testament that we should not conclude this belongs to a particular genre of  'creation poem or song'.
Comment: Benner is not a good guide here, Dick. In fact, some of his claims are decidedly ropey. (And macro-structures have no bearing on prose/poetry distinctions here.) Better off with things like [Petersen & Richards](https://books.google.co.uk/books?id=0usjMJ4xRG8C&printsec=frontcover), or [Kugel](http://www.amazon.com/gp/product/0801859441), or [Alter](https://books.google.co.uk/books?id=MjsAfGYEOBoC&printsec=frontcover), or [either](https://books.google.co.uk/books?id=ohN0CVPCR2AC&printsec=frontcover) of [Watson's](https://books.google.co.uk/books?id=H7dej3vnZ4IC&printsec=frontcover) books.
Comment: I'm confused by your final statement - could you edit to make it more clear?  It seems to contradict the rest of the answer, which to me says that it is at least poetic language in Genesis 1-2, so then why should we not conclude it is a poem?
Comment: @LightCC The  OP  was asking 2 questions and I was trying to answer both: i) is it poetry; ii) if so is it  a type of creation poem or song?  I guess I was not very clear on the second. To me, an possibly to OP, a creation poem or song is distinct genre, recognisable across the Near East, not just in Palestine.  I have made a small change to the  last para in order to bring this out - please let me know if this helps; otherwise I'll have to try writing it quite differently.
Comment: Yes, that helps.  Another way to approach it is to put a few headings in and make clear which sections are answering which parts of the question, or otherwise introduce each section.  I've found it helpful to put the dividing line often in those cases (blank line then ---).
Answer: The answer is that this is historical, rather than poetic. The only reason people try to make Gen. 1:1-2:4a poetic is to try to justify their belief of evolution over special creation. If we were to take Dick Harfield's example above, the consensus would be that days one and four would be prominent as they would be the first on the list in each of their respective accounts (forming vs. filling). That would do irreparable damage to God as the highlight of God's creation is light (sun, moon, and stars).
Second, if the focus is "that" God created and not "how" God created, then why would God waste an entire chapter when it could have been summed up in v.1? He could have stated 1:1, then moved to 2:4b with no literary issues. So if there is any literary genre taking place, a parenthetic would be the best explanation because there was something between his assertion in v.1 to his summary of 2:4b. However, synonymous parallelism is not the only poetic device the evolutionary creationist argues for.
Other scholars believe that this is chiastic as opposed to synonymous parallelism to defend evolutionary creation, but that again emphasizes the third and fourth days, which are not even parallel to each other. The point is that one group says it is one type of parallelism, while another of the same belief believes it is chiasm. It can't be both. So how can one know for sure?
Fourth, there is nothing to suggest that Gen. 1:1 is not directly tied to Gen. 1:2 as in, Day 1 was not just light, but the heavens and the earth also. If that is the case, then it shoots a major hole in the parallelism theory, because evolutionary creationists have to force Gen. 1:1 into the mix, and that does not coincide with Day 4.
The rule of literariness is simply this: If the literal sense make sense, then there is no other sense." (Dr. Howard Hendricks, ). God is the God of the miraculous. He is not bound to natural law. The miraculous is supernatural. And if there was any literariness taking place in the Genesis account, the best option would be a crescendo, because man is the pinnacle, the highlight of God's creation. It is only man that was created in His image. It was man He created the whole world to know.
And finally, to those who would argue that the Bible is a theological, rather than a scientific book, the you have a real theological connundrum with a number of passages that declare a baby as a living being in the womb (not just a fetus until it is viable as science declares): "Truly children are a gift from the Lord; the fruit of the womb is a reward" (Psalm 127:3)
"You knit me in my mother's womb . . . nor was my frame unknown to you when I was made in secret" (Psalm 139:13,15)
"You have been my guide since I was first formed . . . from my mother's womb you are my God" (Psalm 22:10-11).
"God… from my mother's womb had set me apart and called me through his grace" (St. Paul to the Galatians 1:15).
The Bible is both scientific and theological. It is for these reasons that the Genesis account should be taken literally instead of figuratively.

Is Genesis 1 a type of Hebrew Poem?


Does any problem arise when the order of an elliptic curve is equal to its prime field modulus?

Question: Regarding cryptographic schemes in elliptic curve cryptography, is there a problem with having the order of an elliptic curve being equal to its prime field modulus?
That is, an elliptic curve where $\#E(\mathbb{F}_p) =p$ for some prime $p$?
As I understand it, this seems to be an optimal curve because by the lagrange's theorem the order of an elliptic curve's subgroup must be divisible by the order of the elliptic curve. But if the order of an elliptic curve is prime, that then that means that any point in this curve is a generator that produces all of the points in $E$ and has a cofactor of $1$. For example, this curve here.
So, is there some kind of 'gotcha' with this sort of elliptic curve? Something that might allow an attacker to easily solve it by some math trick? Of course, assume for an elliptic curve some large prime $p$ but with the same properties.
Answer: Found an answer: Why Smart's attack doesn't work on this ECDLP?
Smart's attack seems to be what I was looking for.


Effects of an alien weather generator?

Question: An alien race wants to test out its new technology that modifies the atmosphere of Earth and other terrestrial planets, they decide to center it over Central Park, NYC. One of the first things they want to test is how the wind affects the environment. The weather modifier appears to be a large tower that extends into outer space. Now let's say 40 miles from the center of the alien device, winds are sustained at 140 mph with higher gusts, From 40 to 80 miles they are sustained at 100 mph and from 80 to 130 miles they are sustained at 70 mph, from 130 miles to 180 miles the wind rapidly tapers off but is sustained around 20 to 70 mph. What would be the long term effects if these winds remained this way for a full year?
Comment: Central park as in "Central Park, NYC"? You want to put the place into the center of a permanent hurricane? That's kinda mean, isn't it?
Comment: Yes I guess that would be kinda be rude of the aliens :P
Comment: Which way are the winds blowing? My first thought was of a circulating wind centred on Central Park, but they could blowing out radially. There is nothing to precisely indicate which way they are blowing. Please clarify.
Comment: Your alien weather makers obviously have no sense of humour. They could have chosen Chicago which is famous as the "Windy City". :)
Comment: If I am reading this correctly, This is basically a still, Cat4,  hurricane with an 80 mile wide eye, right? At the very least, this would cut off people in the eye from fresh supplies so they would all starve to death. X3
Answer: New York City
Well, New York City would have to be evacuated and no one would live there for a while.  There's going to be a substantial economic effect due to that (expensive but not ultimately destructive to the USA as a whole).
Weather
I don't think that a 400 mile wide stationary hurricane would be large enough to affect weather outside of the immediate area.  However, it might well be enough to disrupt the northern Jet Stream, affecting weather in Northern Europe.
USAF
The USAF will of course do whatever they could to destroy the weather tower as quickly as possible.
Comment: Destroying the tower would mean war.. I doubt we have the resources to go to war against such an advanced civilization.
Answer: The effects would be locally limited, on one side is the sea where the created wind would simply dissolve in the air masses that are moving over the sea, propelled by much bigger forces than such a weather generator.
The same would probably be the case for the weather over the land, but a little more altered through the terrain, in some cases it would be possible that such a wind would strengthen natural weather phenomenon or weaken them but neither on a big scale nor lasting, if you see the massive influence humanity had on weather with the comparative little effect (even though the consequences of these effects are huge) you get an idea of the necessary force you need to bring up so actually have a bigger impact on weather.
Answer: At first though, the sudden polar change would tip Earth onto another axis of rotation; it would be rapid and very violent. Most likely gravity would have the biggest effect on life, and hurl things violently around (you would probably be hit on the backside by trees).
Secondly, the sun would rise/set at different angles, as most likely the south pole would be somewhere around Brazil and the wind would have blow down almost everything around or bend them before they froze; trees would freeze downwards, depending on the actual length of freeze they would never return to there original shape and most likely die from sudden changes.
Comment: Are you sure you meant to post it under this question?

Effects of an alien weather generator?


Privacy in Google Assistant

Question: The other day my phone upgraded from Google Now to Google Assistant. I was having a conversation with a coworker and noticed my phone vibrate. Google Assistant had recorded the conversation and tried to answer a question even though I never said "ok google".
My phone was in standby and in my pocket and I'm not ok with this. Is there a way to set it so I must launch an app to cause it to start listening, like some sort of widget? Is Google Assistant only supposed to record when you say "Ok Google" or does it not need any specific phrase? Does Google Now offer better privacy than Google Assistant? If not, is there a way to remove them both?
Answer: In very noisy situation Assistant may be invoked by mistake. If you do not want to happen this again then turn off OK Google Detection from any screen in the Google settings.

Privacy in Google Assistant


do digital input pins act as a positive or negative

Question: I've gotten contradicting information on the subject.  Some say that digital input pins send out positive voltage, and if it goes to ground (for example) it reads LOW but if the pin is connected to power, it will read HIGH.  On the other hand, some say that the input pin is receiving voltage from either power (+5V) or ground (0V).  which one is it?
Answer: Digital pins sink or source current. They don't provide negative voltages. If the pin is set to INPUT then it is high impedance and will not "send out positive voltage".
However if you activate the internal pull-ups, as Ignacio said, then effectively the pin is connected to +5V via (approximately) a 50k resistor.
Answer: It's both, depending on whether or not the internal pullup has been enabled (INPUT versus INPUT_PULLUP). The pullup ties the input to the positive supply through a moderately large resistance, meaning that it is possible to source a small amount of current from the input pin.


bitcoind and onion listening

Question: I would like to get Bitcoind to advertise that it is listening on an onion address.  However, I do not want to have Bitcoind use a tor socks proxy to connect.  I have a special router for tor connections and the Bitcoind server uses that as its network gateway.  How do I get bitcoind to advertise an onion address without setting a socks proxy?
Answer: You need a way for an onion service to be created, connected to and advertised. Usually, with Tor running on the same machine, just start bitcoind with the following option should do it depending if your installed versions of Tor and Bitcoin Core are new enough:
>bitcoind -listenonion

You may also need to override -bind=, -discover=, listen= and -externalip= after that to suit your exact configuration.

Of course, the setup in your question is a little different to standard. What you will need to do is:

Bind your bitcoind to the network IP of the machine it is running on. It probably is already but, you can use -bind= if necessary.
Ensure the firewall on your bitcoind machine will allow incoming connections to the bitcoind service from your Tor router. With firewall configuration, it is always best to be specific.
Setup the onion service on your Tor router and point it to your bitcoind machine. Make a note of your onion service name.

Ordinarily, you should be able to add the following lines to the /etc/tor/torrc file:
HiddenServiceDir /var/lib/tor/bitcoin-service/
HiddenServicePort 8333 {machine IP of bitcoind}:{mainnet port}
HiddenServicePort 18333 {machine IP of bitcoind}:{testnet port}

*Note that I have not tested this setup and presume Tor will allow you to specify the IP of your network machine running bitcoind

You may consider adding 8333 to the LongLivedPorts parameter in your permanent Tor config and restart Tor unless you have a live configuration editor like nyx to also change it on the hop.
Configure bitcoind to use and advertise the onion address for incoming connections. You can use -externalip={onion}. I am not sure if you can or if you need to specify this multiple times, for any standard IPv4/IPv6 external incoming addresses also.
You may also consider using -discover=1 since you are not trying to hide your standard external IP addresses I presume.

In bitcoin-qt, you can see the command line options and their descriptions in the help menu.
Comment: tor is running on a separate machine.  So I cannot do this.
Comment: @jdejesus068 I have extended my answer. Hope it helps.

bitcoind and onion listening


How are mRNA vaccines spread across the body?

Question: Covid mRNA vaccines are injected into the deltoid. What is the process in which they spread from there to the rest of the body? Would there be a better immunization reaction if the second dose is injected elsewhere?
Comment: Why do you think the vaccine would need to spread to the rest of the body?
Comment: https://meta.stackexchange.com/questions/66377/what-is-the-xy-problem
Comment: @KyuriOseetea The vaccine doesn't spread; instead, the immune system spreads its responsive elements.
Comment: Mostly because of reports from Israel, US army and UK on miocardatis which may be linked to the vaccine in younger patients (although in the UK it is in low numbers compared with the others, but the age of the patients is older). If it is related, I'm trying to ascertain whether it could be from the mRNA instructions
Comment: https://www.docdroid.net/xq0Z8B0/pfizer-report-japanese-government-pdf#page=16
Pfizer's study for the Japanese government, cp. 22.214.171.124B. PHARMACOKINETICS: ORGAN DISTRIBUTION e.g. ovaries 23, testis 0,3 after 48 h.
Answer: The short answer to how vaccines are spread around the body is, quickly.

What is the process in which they spread from there to the rest of the body?

The reason vaccines are often delivered into muscle tissue is because muscle tissue is highly vascularized with both blood and lymphatic vessels. Immediately after a vaccine injection, the delivery vehicle (probably lipid nanoparticles or a viral vector) will quickly start diffusing into the blood, where it will be carried up to the heart, and from there begin spreading around the body (a lot of it ends up in the liver). Somewhat less quickly, in the lymph it will essentially start to generate an immune response immediately as it drains into lymph nodes and begins circulating throughout the lymphatic system (note the the desired immune response won't start until the genetic component of a vaccine has entered nucleated cells and has started being translated into the desired viral antigens).

Would there be a better immunization reaction if the second dose is injected elsewhere?

Don't know if I can definitively justify saying "no" to this question, but probably not. Muscle tissue seems to be the best injection site for vaccines. Deltoids are probably the best muscle because there's a lower chance of missing the intended injection site compared with some other muscles (e.g. glutes). And the systemic spread of vaccine components starts happening pretty fast after injection. In one animal study, researchers surgically removed a leg muscle 1 to 10 minutes after injection and still didn't prevent the related antibody response, or even really reduce it compared to animals with the muscle left intact.
Assorted References:
mRNA Vaccines: What Happens
Inadvertent subcutaneous injection of COVID-19 vaccine
The importance of injecting vaccines into muscle
Different patients need different needle sizes
Unmodified mRNA in LNPs constitutes a competitive technology for prophylactic vaccines
Differential dependence on target site tissue for gene gun and intramuscular DNA immunizations (1997)


CDG to Bordeaux train options

Question: I need to get from Paris CDG to Bordeaux and there appears to be a direct train from the airport, but it seems to be full. Is going to Montparnasse a viable option to catch another train?
Comment: Notice that there's currently a strike going at the SNCF. As many trains are canceled, that might explain the lack of available seats on the CDG-Bordeaux line (and a general lack of available seats on all lines). Depending on your schedule, things might get better at a future date.
Comment: Yes but also look for other options where you do not travel into Paris to leave it again.
Comment: The strike is on a 2-days of strike, 3-days normal cycle. All trains during the 2 days of strike are shown as full even if they aren't, as they don't know yet if they will be running. If at all possible, try to avoid the strike days.
Answer: TL;DR
Yes
Longer answer
You can either take the direct train which is a little slower (given it goes around Paris at slower speeds) or go to Montparnasse where the high-speed services run from. You will have a lot more services from there but you have to deal with the hassle of going to Montparnasse. There is a direct bus service from CDG to Montparnasse as well as local rail (RER+transfer on the Metro). It'll take 1 hour at least to go from CDG to Montparnasse. I would be tempted to either (a) try to grab a train from CDG (more convenient) or fly from CDG to BOD. It could even be cheaper.
Comment: Second the recommendation to fly. One advantage of flying to BOD is that you avoid using the public transportation in Paris, which isn't the cleanest and safest, especially in the northern suburbs. Even passing through CDG is enough of a chore anyway.

CDG to Bordeaux train options


Are these GND connected resistors on the Arduino Due redundant?

Question: Does anyone know why these 4 resistors are there (attachment)? It seems like they are useless since connected in a loop to GND.
Full schematics here: https://store.arduino.cc/arduino-due
Comment: Just guessing RN is for **r**esistor **n**etwork.  So they may have more than they needed to use.  I'd say probably "unused".  If that what you meant by "redundant?"  Hard to say with any certainty.  It may be better to ask the electronics stack exchange.
Comment: `RN2B` would be resistor network `2`, resistor element `B`. There appear to be 4 resistors, `A` through `D`, inside one resistor-network package. You can see `RN5` has the two unused resistors unconnected. The reason RN1 and RN2 have them connected to ground might have to do with noise. EDIT: looking at the eagle file, it seems like they connected them to ground to make the ground-plane flow better. My only question is why they didn't use a single resistor network here, instead of using only halve of two resistor networks.
Answer: Yes, they are redundant. They are elements of resistor arrays (multiple resistors in one package) that aren't used. They have just connected all unused pins of those packages to ground.
If you want to know why they would have unused elements, it's all to do with optimizing the manufacturing process. If you have, say some 100k arrays elsewhere in your design and you want to have maybe one or two other 100k resistors elsewhere, rather than adding another component of a discrete 100k resistor it's cheaper to use a 100k array and not use some of the elements. One of the factors in the cost of pick-and-place operations is the number of different components. By keeping the number of component types to a minimum they keep the manufacture costs to a minimum.
Comment: great thanks, so if I understand correctly I could just use 1 resistor network (consisting of 4 resistors) to apply pullups to JTAG_RESET, JTAG_TDI, JTAG_TCK and JTAG_TMS and then get rid of the other 4 resistors? I'm designing a board based on this, hence the question.
Comment: Sure. A resistor array is just four individual resistors in a convenient package.


If particles are points, then aren't atoms empty space?

Question: Zero dimensional points do not take up space, so then wouldn't everything in the universe be literally empty? Or is there something that I'm missing?
Comment: Related and possibly a duplicate: [Why doesn't matter pass through other matter if atoms are 99.999% empty space?](http://physics.stackexchange.com/q/126512/)
Comment: Apart from the fact that you, made of atoms,  are here to ask the question?:) where did you see the 0 dimensional reference? Have a read of this: http://physics.stackexchange.com/q/126512/
Answer: Although it's commonly said that fundamental particles are point particles you need to be clear what this means. To measure the size of the particle to within some experimental error $d$ requires the use of a probe with a wavelength of $\lambda=d$ or less i.e. with an energy of greater than around $hc/\lambda$. When we say particles are pointlike we mean that no matter how high the energy of your probe, or how small its wavelength, you will never measure a particle radius greater than your experimental limit $d$. That is the particle will always appear pointlike no matter how precise your experiment is.
But this does not mean that the particles are actually zero dimensional, infinite density, dots whizzing around. An elementary particle does not have a position in the way we think of a macroscopic object as having a position. It is always delocalised to some extent, i.e., it exists across a region of some non-zero volume. More precisely the probability of finding the particle is non-zero anywhere within that region.
So an atom is not empty space. The usual analogy is that it is a fuzzy blob, and actually that's a not a bad metaphor. If we take any small volume $\mathrm dV$ within the atom then the probability of finding the electron in that region is given by:
$$ P = \int \psi^*\psi\,\mathrm dV $$
where $\psi$ is the wavefunction describing the electron in the atom. And since this probability is just the charge density that means the charge density varies smoothly throughout the atom.
It is important to be clear that this is not just some time average due to the electron whizzing about the atom very fast. It is not the case that the electron has a precise position in the atom and our probability is some time average. The electron genuinely has no position in the usual macroscopic sense.
Answer: Because of the Pauli exclusion principle, it's extremely difficult to compress atomic matter beyond a certain density. It's not impossible, because there are always higher-energy electron states available, but there's a very strong force opposing it (called electron degeneracy pressure).
This is what it means for space to be full. If you define "empty space" in such a way that atoms are empty space, then atoms are empty space, but also the notion of "empty space" becomes useless because all space is empty. The idea of empty and occupied space long predates the modern understanding of fundamental particles. The job of science is to explain why the world is the way it is—for example, why you can't walk through walls—not to give new meanings to existing words.
Answer: Yes, elementary particles such as electrons and quarks (inside protons) are point-like or at least, their internal structure is incomparably smaller than the size of the atom. So the atom is mostly empty space.
However, that doesn't mean that atoms may penetrate each other. Matter is impenetrable because of a combination of

the uncertainty principle that says that the electrons can't be simultaneously sitting at/near the nucleus and have a small velocity (and kinetic energy), so the typical distance of an electron from a nucleus is finite (comparable to what is then interpreted as the size of the atom)
the Pauli exclusion principle that says that electrons can't occupy the same state. For this reason, even though the space in the atom is "empty", it is not possible for many electrons to occupy the same space.

For those reasons, atoms, although they're empty space, don't allow other atoms to overlap with them – and that's why atoms always "push" on other nearby atoms.
Comment: @lemon the wavefunction is a probability function, and gives the probability of finding an electron at (x,y,z,t) , and it is for a point that this can be calculated. The probability is smeared, not the electron.
Comment: @lemon It means that they scatter like a Mott particle down to $10^{-18}\,\mathrm{m}$ and shows no signs of internal structure.
Comment: Although I know it is a standard usage, I would echo @lemon and suggest when discussing this issue you refrain from using the term 'point-like' and instead exclusively emphasize that you mean 'fundamental' or 'no internal structure.' The former term always seems to lead to confusion about the various notions of what the size of a delocalized particle is.
Comment: In the context of atoms where (say) the electronic wave function is smeared out over space, what does it even mean to speak of the "size" of electrons?
Answer: A charged particle like electron maybe is point-like (of radius zero), but it is "long-handed" as it is "felt" far away. In this sense it is not so "point-like".
Comment: That's kind of beside the point (pun totally intended).
Answer: What we intuitively think of as "solid objects" are actually electromagnetic force-fields repelling each other. So you are correct; atoms are 'empty' in that they contain no solid objects or things. On the other hand, they are 'full' of basic force field which, in the aggregate, on a macro-scale, creates the illusion of 'solidity' that is what we perceive to be solid objects.
Answer: Another issue is that the forces between elementary particles in an atom introduce some characteristic length scales. For example, although quarks are possible point particles, the protons and neutrons in which they reside are about 2 femtometres wide because the forces between quarks prevent further compression. This gives nuclei a femtometre-scale size, but an atom is picometres wide due to the orbital radius of electrons. An atom therefore functions like a sphere with a certain chemical valency. In each case, the occupied space is filled with a forcefield of a certain mass-energy density.


What do you term when swapping same characters [1] spawns and [2] doesn't spawn new meaning?

Question: I just saw on Wiktionary that verbs 澄清 and 清澄 don't mean exact same. What are linguistic terms when swapping same Chinese characters

spawn new meanings?

keeps meaning same?
Answer: If you swap the two characters in a compound word, and the meaning changes, then it is just a different word that happens to use the same two characters, e.g. 中心 (center) and 心中 (in the heart) are two different words;
If you can swap the two characters in a compound word and the meaning remain the same, it indicates the compound word itself is made up of two characters that have the same or extremely similar meaning, e.g. 打擊 --> 擊打 (both 打 and 擊 contain the meaning of 'hit'); 拯救 -->救拯 (both 拯 and 救 contain the meaning of 'rescue'

擊打(v) is a (not commonly used) variant of 打擊(v)

救拯(v) is a (not commonly used) variant of 拯救(v)

識見(n) is a (not commonly used) variant of 見識(n)

見識(v) and 識見 (n) are two different words

澄清(v) and 清澄 (adj) are two different words

In olden time, people often use this kind of variant to showcase their literary knowledge and sound more classical. You have to know what compound words are made up of two characters that contain the same meaning to be able to do so. In modern time, you can often find them in song lyrics when the writer needs to make it rhythm
Answer: As far as I know, we don't have specific terms for these two kinds of word.
But I can give you more examples:
1: 名人-人名、事故-故事、星球-球星、明天-天明、牙刷-刷牙、科学-学科...
2: 讲演-演讲、觉察-察觉、依偎-偎依、缓和-和缓、察觉-觉察、妒忌-忌妒、奋发-发奋、登攀-攀登、寂静-静寂、容颜-颜容、情感-感情、别离-离别....
Found any rules? If two Chinese characters have the same part of speech and they have similar meanings, you can switch them and the meaning won't change. (It feels strange sometimes though). If two Chinese characters are different parts of speech or they have different meanings, that means one character is to describe the another character, changing the order changes their relationship so it's meaning changes.


Did "big bang" radiate light?

Question: According to present day physics nothing existed before the "big bang", even space and time. But often in documentaries, the "big bang" is shown as a ball of light that exploded at some point. If this were so, then photons should have been the first particles that flowed in the new universe. If we placed an imaginary observer at some visible distance from the "big bang" would they have been able to observe it?
Comment: Related: http://physics.stackexchange.com/q/7359/2451 and links therein.
Comment: Another way to look at it is this. During the first moments after the big bang, light could not exist. The physics required for light did not exist, not until the Electro-Magnetic force decoupled from the Weak Nuclear force.
Answer: The Big Bang didn't occur at a special isolated place in the Universe. It occurred in the whole Universe and every place of it. Every point was an equal player in the Big Bang.
Lots of light at various frequencies was produced during the epochs of or after the Big Bang. But it's wrong to imagine that they were coming from a particular distant place. Instead, it's right to imagine that every point of the Universe, even the point where our galaxy was later born, including the point where your imaginary man is located, much like the real men on the Earth, was somewhere in the middle of the "oven" of the Big Bang.
The Universe has always been pretty much uniform and homogeneous – this insight is known as the cosmological principle. The cosmological principle prohibits a privileged place of an explosion that is "better than others". On the other hand, the explosion is a good idea to have in mind for some purposes – regardless of the choice of the "center" of the explosion – as long as one appreciates that everything sits at a place where the explosion used to occur in the past, too.
Because our place is in the "middle" of the Big Bang explosion as well, we see the light coming to our eyes from all the directions around us, just like if you're in the middle of the oven.
Comment: I think the word "explosion" is misleading. The big bang is the moment of time when the scale factor equals zero. There is no large explosion of energy. It's terms like that that lead to people having similar misunderstandings about the concept as the OP. That said, it is a good answer, +1, I just am not a fan of "explosion"
Answer: I would like to think about the universe as a balloon's surface. Imagine yourself as a 2D person living on this balloon, can never get out of it.
If the balloon expand, you will just see everything is going far away from you, and vice versa.
So if you think of Big Bang as a sudden great expansion of the balloon, you - the 2D person on the balloon - will see no explosion but things around are like leaving you very fast.
That's how I think about Big Bang and universe's expasion.
Answer: You cannot place anything "outside" to observe the big bang because there was no space that thing could have existed in (as you rightly said in your first sentence). So any observer is necessarily right in the middle of the bang happening. The popular science illustrations showing a ball of light expanding are essentially wrong. There is nothing the ball expands into.
However, the early universe was very hot, and filled with radiation, but also very full of particles of all kinds due to the high energy density creating particles from the vacuum. It was opaque until matter was dilute enough to allow the passing of light, indicated below @380000yrs as the origin of the CMB. An observer right after the big bang wouldn't have seen anything (but that admittedly makes for poor images to show in TV ;) )(Image courtesy of Wikipedia)
Comment: The opaqueness before recombination is not so much due to the concentration of matter as much as it is due to the fact that the plasma was so ionized and energetic that baryons easily coupled to photons and so the mean free path of a photon was very short. After recombination, the concentration of matter was very similar to before, but the neutral atoms allow light to pass through much easier than the ionized plasma.

Did "big bang" radiate light?


Listing of DNS vulnerabilities

Question: I am currently studying how to setup DNS servers and all aspects of the DNS system. I would also like to study the security aspect. I want to use current DNS server attack on my test servers. Is there one place that lists the current attacks that are used by hackers so I can learn how to prevent them?
Answer: I'm not sure that there's any single place that lists all of the vulnerabilities related to DNS, but here are some pointers you might use for further research.
General DNS Weaknesses
One broad category of DNS vulnerabilities would be at the protocol- and system-layer.

The wikipedia article on DNS lists security issues with the system.
A particular vulnerability is cache poisoning.
You can learn about DNSSEC as a countermeasure against some of the weaknesses in the protocol.
Here's a list of notes on DNS that point out several system-level weaknesses.
DNS is described in numerous RFCs. (That list is not up to date. You can find newer RFCs by looking at the references section in a recent DNS RFC.) Modern RFCs include a "Security Considerations" section that discusses security aspects related to the topic of the RFC.

Specific Vulnerabilities in DNS Implementations
Another broad category of vulnerabilities are bugs in specific implementations of DNS. There have been so many bugs in ISC Bind, for example, that this attack vector is much more likely to be successful than an attack at the system level (this depends on the target and the environment, though).

Search the National Vulnerabilities Database. (E.g. ISC Bind)
Search at SecurityFocus
Look for exploits in the exploit database.
Metasploit and various other scan tools may be able to automatically detect vulnerabilities on unpatched servers.

Complex Interactions
Studying DNS in a vacuum isn't really enough, though. DNS interacts with other protocols in interesting ways.
For example, if your network doesn't protect against rogue DHCP servers, it may be possible for an attacker to run a DHCP server that hands out a lease that points to a rogue DNS server. The DNS server then returns whatever addresses the attacker wants -- substituting his own address for paypal.com, or rerouting email, for example.
Comment: Doesn't Wikipedia provide a list of DNS vulnerabilities?
Answer: Your question is a bit vague.
If you want to learn about attacks on the DNS system, make sure you first fully understand how DNS works (and DNSSEC, if you're interested in the security of that as well). Then I recommend you read up on DNS cache poisoning attacks, as there are multiple kinds and DNS is plagued most by those.
Of course, DNS server software suites have been plagued by all kinds of bugs, but those are implementation bugs and not protocol bugs.
Comment: It's not vague at all. He wants a list of DNS vulnerabilities, so that he can compare each item on this list with his DNS server. To see whether the DNS server is secure against all these vulnerabilities.

Listing of DNS vulnerabilities


Determine realistic training goals for a set period of time?

Question: When training in the gym, I rarely ever set myself (longterm) goals for my lifts. Or when I do, I most certainly don't reach them, what demotivates me. Is there a good way or method to determine realistic goals? So goals that are challenging in order to motivate while training but at the same time doable to achieve?
Comment: What do you actually want? If you had one wish fitness related, what would it be? It doesn't need to be achievable for you, but it's a good way to start not in the middle but somewhere at the end. Then you can go from there. As far as I know that's how most respectable people and companies operate anyhow
Answer: This will depend heavily on what you're training for. I personally set few, but hard to achieve goals per year. And with few I mean things like, I want to be able to deadlift x-amount (right now I'm shooting for deadlifting 3x my own bodyweight) or I want to be able to do a one-arm handstand (my main sport is calisthenics).
These are very hard but achievable things if you work hard. It helps me focus to become really good at one thing, rather than being mediocre at everything. I understand that this is not for everyone, but it's an example of what I do.
As I said, setting goals depends on what kind of sport you're doing.


View a buffer in read-only mode in a window while editing it in another window

Question: A buffer can be made write-protected by toggling the read-only mode via M-x toggle-read-only.
Is there a way to make a buffer read-only in a window, while editing it in another window?
Answer: In your original buffer, where you want to keep editing it :
M-x clone-indirect-buffer

This would create another buffer, and by default open it in another window too. Initially both of these are editable. But a buffer specific mode change can be made in the second one - which will now become read only after you do the following :
M-x read-only-mode

Now this second buffer is your buffer in read-only mode - same content as the earlier read-write buffer.
Comment: could you please add some explanation?
Comment: Ah, ok, one min. Since you were using M-x and toggling modes already, I thought you would understand very easily.
Comment: Thanks. IMO, it is better to add some explanation along with the commands for the general audience.


How do I obtain sharp images on full body portraits?

Question: I currently have a 50mm 1.8 and 85mm 1.8 and would want to know if the bokeh or sharpness  would be any different at all. Many seem to say that the 85mm woud work best, but wouldn't I have to bump up my Aperture to get a sharp image? I'm shooting on a full frame camera not a crop sensor.
Comment: Possible duplicate of [50mm vs 85mm for portraits on a crop sensor?](https://photo.stackexchange.com/questions/25350/50mm-vs-85mm-for-portraits-on-a-crop-sensor)
Comment: Bokeh or sharpness would most likely be different, because every lens has it's own bokeh and sharpness. About aperture - you set the it to get what you want at the time. It's unclear what you're asking, can you rephrase your post?
Comment: Have you a specific problem (e.g. post an example image with EXIF data) as as written your question could involve any number of issues.
Answer: If you want more depth of field in your subject, stand further away, &/or close the aperture.
The added distance will mean the 'percentage' of distances from front to back of your subject will be less, increasing apparent DoF, at the expense of your subject taking up less of the frame.
If you want more bokeh with that setting, separate the background from the subject by a greater distance.
You can't really have both at once.
Longer focal length will give a shorter DoF for a given distance. Shorter focal length will give you a wider background.
I don't have the math to calculate what the actual difference would be. I'd try both & see which you prefer.
Comment: This is where it's useful to use a depth-of-field calculator, which are available in app form and online. For example, if you're shooting at f/1.8 at 10 feet with a typical crop-sensor prosumer camera, with the 50mm your depth of field is about 9 inches; with the 85mm it's about 4 inches. Close up to 2.8 and you're talking about 1.5 feet vs. 5-6 inches.
Comment: @jeffronicus DoF calculators are useless unless the user realizes they assume a specific display size and viewing distance. If you print the same exact image in two sizes, say 8x12 and 16x24, and view them side-by-side from the same distance the smaller one will have more DoF than the larger one will. If you are pixel peeping on a monitor, you can forget most DoF calculators. Looking at a 24MP image at 100% (one screen pixel per image pixel) on a 23" HD monitor, you're looking at a piece of a 60x40" image!
Comment: @jeffronicus Not to mention that you'll need to back up to 17 feet with the 85mm to get the same framing of the subject as the 50mm at 10 feet. But then your distance ratio between subject and background changes unless you also increase subject to background distance by a factor of 1.7X...
Answer: To get the same framing of your subject using the same camera, you'll have to shoot from further back with the 85mm lens than with the 50mm lens. The decrease in DoF from using an 85mm lens compared to a 50mm lens when both are used from the same distance is offset by the increase in DoF when using the same lens from a greater distance. In the end at most distances they usually offset each other almost exactly.
Assuming an 8x10 display size viewed from a distance of 12 inches, shooting from 20 feet with the 50mm lens at f/1.8 on a FF camera will give you a DoF of about 1.86 feet or 22.32 inches. Shooting from 34 feet with the 85mm lens at f/1.8 on a FF camera will give you a DoF of about 1.86 feet or 22.32 inches.
Assuming an 8x10 display size viewed from a distance of 12 inches, shooting from 10 feet with the 50mm lens at f/1.8 on a FF camera will give you a DoF of about 0.46 feet or 5.52 inches. Shooting from 17 feet with the 85mm lens at f/1.8 on a FF camera will give you a DoF of about 0.46 feet or 5.52 inches.
In both cases the total depth of field is the same when the 85mm lens is used from 1.7X the distance of the 50mm lens to get the same framing of the same subject as the 50mm lens. What does change is how much of that DoF is on front of and behind the point of focus.
At 20 feet, the 50mm lens distributes the DoF 0.89/0.97 feet in front of/behind the point of focus.
At 34 feet, the 85mm lens distributes the DoF 0.9/0.95 feet in front of/behind the point of focus.
At 10 feet the 50mm lens distributes the DoF 0.22/0.24 feet in front of/behind
the point of focus.
At 17 feet the 85mm lens distributes the DoF 0.23/0.23 feet in front of/behind the point of focus.
Please note: All distances are rounded to the nearest two significant digits to the right of the decimal, which can introduce rounding errors between the sum of the distances on each side of the point of focus and the total distance.
Having said that, which lens is sharper, a 50mm or an 85mm, depends entirely upon the two lenses in question.
A budget 50mm lens will probably not be as sharp as a premium 85mm lens. But a budget 85mm lens will probably not be as sharp as a premium 50mm lens, either.
Then, depending on how you define "sharp" one lens might be better than the other or vice versa.
Do you define "sharp" as absolute performance at the center of the lens? Average performance over the lens' entire field of view? Do you measure "sharpness" over the entire field of view using a flat test chart? Or do you base it on the shape of the space occupied by a three dimensional subject?
Lenses that are well corrected for field curvature and thus do better on flat test charts tend to have "rougher", "harsher",  or "busier" bokeh than lenses that don't correct as much for field curvature but tend to have "smoother" bokeh.
What aperture you need to use to get all of your subject within the depth of field depends upon:

The focal length of the lens.
The distance from the camera to the point on the subject you want to be most in focus. There's always only one distance that is truly in focus. The rest of what we call "depth of field (DoF)" is not actually in sharpest focus, but is close enough that our eyes can't tell the difference when the image is displayed at a specific size from a specific viewing distance. In short, depth of field is an illusion, although a very convincing one.
Which way your subject's body is oriented in relation to the camera. If they are standing perpendicular to the optical axis of the lens you'll need much less DoF than if they are lying prone along the same direction as the lens' optical axis.
The size you intend to display the image.
The distance from which you intend the image to be viewed.

For full body portraits, though, neither a 50mm or 85mm is probably your best choice unless you plan on shooting from halfway across a small parking lot, even with a full frame sensor.


How do I disable the on screen keyboard? I have a USB keyboard attached

Question: I have a ZeniThink C91 using Ice Cream.  I also have a case that has a USB keyboard.  How do i disable the android Keyboard so only the USB keyboard is active?  Ice Cream 4.0
Comment: @jlehenbauer I think so, good find!
Comment: I was sure we had a question like this already but I can't find it.  IIRC, the solution was to install a software keyboard that was either a dummy and never showed on-screen or that was smart enough not to show when the USB keyboard was being used.
Comment: Actually I found the task and killed, now I can see the whole screen when typing on my USB keyboard.  But thanks.
Comment: @Matthew were you thinking of [this](http://android.stackexchange.com/questions/16652/how-to-disable-virtual-keyboard-when-in-landscape-mode) ?
Answer: Null Keyboard is what you want. I do this same thing with my bluetooth keyboard. It does require you manually switch the input method each time, but keeps the pesky on-screen keyboard from popping up.
Another option I've used is to use the method described here to program one of your keys to a Back button, which you can press to remove the on-screen keyboard each time it pops up.
Answer: You might want to search for an alternative to the stock-keyboard delivered with your android device.
There are keyboards that have hardware keyboard detection and settings to explicitly turn off the on-screen keyboard, blueduino soft keyboard for example.


What black piece can you capture?

Question: What black piece can you capture? This is homework from school.
[FEN "8/8/2n5/1p6/4r3/1Kb5/3p4/8 w - - 0 1"]

Answer: This question needs some context.  All the pieces are black.  In order to capture, a piece of an opposing color needs to occupy the square of the captured piece.  The king can not be captured, only placed in checkmate or stalemate.
Since there are no opposing piece, one correct answer could be none of the pieces.
If the question supplies a white piece and location, then the question can be answered.  For example if it was white to move, and there was a white bishop on d3 and a white king on d5 then the question would have some educational value for a beginning student.  What captures could be made in that situation?
Answer: If the king is white you can capture the bishop on c3.
Answer: If we make the following two assumptions

It is white's move
A piece can be captured

Then clearly the only piece the king is adjacent to is the bishop, so that must be the piece. However, this bishop appears to be protected by the pawn. This must not be the case, because the bishop is the only possible piece to capture. Thus we can conclude the bishop is not on C3, but rather F6 and the board is simply inverted.
So the game continues 1) kxf6 e8=Q 2) kg7 rd6 3) kh7 ng5+ 4) kg7 qf7++

What black piece can you capture?


Accidentally added yeast in first 24 hours

Question: I am making plum wine.  The recipe said mash the fruit, cover with water, add a campden tablet and pectinase and leave for 24 hours before adding other ingredients.  I through the yeast in at the same time before I realized I needed to wait 24 hours.  Will this negatively impact on the rest of the process?
Answer: The Campden probably will not kill your yeast, but will only make the yeast upset, causing them to increase sulfur production and make them more sluggish, but things will stabilize again after a week or so.  I believe everything will still turn out alright.  If you are concerned, then add extra yeast.  However I don't believe this will be necessary.  Good luck and enjoy.
Comment: It wouldn't hurt to toss in extra yeast though. IMO.  As long as the original pitch wasn't huge.


are questions about loadbalancing on topic?

Question: Do we consider loadbalancer configuration on topic? Though they certainly do things on layer 2/3, a lot of the things they do is on higher layers as well. At the company I work for loadbalancers are managed by NOC engineers, but I know other companies where loadbalancers are managed by systems engineers, so I'm curious what others thing about this.
Answer: Short Answer: A question about a load-balancer, that is involved in balancing traffic at the network layer (layer 4 or below) is directly involved with end to end visibility of network traffic, so by that measure, I believe it to be on topic.
I think if you are asking about how to set up a stateful load-balancer, synchronising TCP state tables between them for example, that would be OK. This is a networking question. I don't think asking about setting up a HTTP load balancer would be acceptable though (that is probably more for ServerFault's realm). That example is aimed at the application layer if you like (viewing this from a typical OSI 7 layer model view). Although I do think layer 7 can be on topic, perhaps not in this case.
Comment: Network engineers don't stop at the TCP layer... we have to be fluent all the way to the application boundaries.  HTTP-aware load-balancing is in-fact the best thing to do if you're balancing an HTTP service... I don't see a good reason to punt this question to another site if the underlying hardware (call it an F5 for sake of argument) is the same
Comment: @MikePennington I do agree with you, but I have recently been involved in a situation where the load-balancer was under the control of both network techs and sys admins. The sys admins want to control the insertion of cookies into the HTTP sessions and/remove custom headers. This is deep into the application layer, and wasn't part of my remit. My remite was making sure load balancers had multiple vlan sub interfaces to serve all the attached networks, and where failing over IPs between each other using VRRP. This is a prime example I think, of when layer 7 becomes off-top, tuning HTTP headers.
Comment: while I can understand that you don't want to be involved in cookies, that isn't sufficient justification to punt all questions about HTTP load-balancing from the site... that merely means that sometimes network engineers share service administration with system administrators
Comment: @MikePennington again I agree, so where do we drawn the line? I suppose, it could end up simply being one of those "post and see" scenarios where some get closed, and some get answered?
Comment: Ask a SysAdmin to configure a load-balancer so the server itself can reach another server via the load-balancer in the same VLAN, and you'll see this is not a job for someone who doesn't know what and where sNAT is needed.
Answer: Responsibility for load balancers often fall to the network folks and without proper consideration of the network there will be issues.  Even if they are talking about a HTTP load balancer, in my mind this makes them on topic for network engineering along with other devices that operate above L4, such as traffic shaping/policing.
Comment: I agree, I know many a Network Engineer that spend a lot of time working on F5 or ACE load balancing setup and issues.  A quick search of Stack Exchange shows questions like this spread all over.  I would think over time that the questions would find their way to the best site for the specific question.


how would you test a bitcoind/bitcoin-cli without syncing?

Question: I want to be able to test bitcoin without waiting literal days, is it possible to run a local node that doesnt require sync?
Answer: Yes you can use regtest e.g. bitcoind -regtest which is a local node without any prior block history.
But even with mainnet, testnet, signet nodes you can still run most bitcoin-cli commands during IBD (initial block download). You can't use some Core wallet functionality (e.g. spending) until IBD has completed as the wallet needs to know how much Bitcoin it has etc.
Answer: If it is just for trying I recommend using the testnet. No matter if testnet or mainnet, you could install a pruned node.

Pruned nodes, a type of full node that allows us to take advantage of their enormous security, but reducing their blockchain storage requirements so that we can run them on practically any device. Source


Trying to use IBM model F (5 pin DIN) with modern Windows PC

Question: I have a vintage IBM Model F which I just bought from eBay, that I am trying to connect to my new Windows Pc. I ordered a DIN to Ps/2 converter from Newegg, because I my pc has a combined ps/2 port, so I assumed it was just going to be an easy plug and go. However. My computer can't seem to read that there is a keyboard there! It won't work in The BIOS and it won't even come up in device manager. Is there are driver I need to download or something? Please help!
Comment: Does the keyboard have num/caps/scroll lock indicators in the top right hand corner?
If not it's an PC/XT keyboard which will not work with an passive AT converter do you have a part number?
Comment: It's a good thought. My daily driver is an IBM Model M. Works no problem with PS/2 on modern motherboards. Never tried a Model F but getting it working first on an old PC with PS/2 would be a good first step.
Comment: the keyboard used must support old serial interface for example I am using DIN5/PS2  + PS2/USB passive converters on my  oscilloscope (running Win9x) with old USB keyboard I got for my long dead laptop (let it rest in pieces). It is working but the new keyborads (especially fancy ones for gaming) do not ... And also the converters should be the right ones IIRC there were some differences between mouse and keyboard (they where usually color coded as they looked the same with the same connectors) you want the violet ones not green. And also PS2 requires restart ...
Answer: The only Model F keyboard which can be used on a modern PC with only a passive DIN to PS/2 converter is the 84-key AT keyboard. This keyboard type can be recognised by the 'Caps Lock', 'Num Lock' and 'Scroll Lock' lights in the top right-hand corner, and the keys being separated into three blocks.
Other keyboards such as the 83-key PC/XT keyboard or the 122-key 3270 PC / terminal keyboards require to be connected through an active protocol converter (such as "Soarer's Converter") to be usable on a PC with a PS/2 port.
It's also possible to use at least some 122-key keyboards if you burn a new microcontroller with AT-compatible firmware but that's rather more invasive than using a separate converter. (I've seen this process described as 'flashing' the microcontroller, which it isn't -- the 874x is based on EPROM, not flash!)


Starting with Monero - verification?

Question: Do you need to verify your identity somehow when creating a monero wallet or buying/selling/sending monero?
Thanks
Answer: When creating wallets and sending Monero you DO NOT need to identify yourself.
Personally I prefer to use the CLI wallet, This is typically how I create my wallets.
However, when buying and selling Monero, you typically will go through an exchange, this is the point where you will usually have to identify yourself to some degree.
Transacting in Monero SHOULD BE secure as Monero's key value proposition is to obscure your transactions (sending and receiving) using Ring CT.
Answer: You do not need to verify your identity when you create a wallet. If you want to buy or sell Monero on an exchange, then you need to have an account on that exchange and for that you need to verify.
But you can of course do the following:

Create an account on an axchange and verify your identity.
Deposit some Monero from your wallet to the Monero wallet on that exchange or buy Monero on that exchange (depends on if you want to sell or buy).
Sell Monero on that exchange or if you bought some, withdraw Monero from the exchange wallet to your personal wallet.

Let's say you bought some Monero on an exchange and send it to your own private wallet. In that case, after the Monero is in your private wallet, you can do whatever you like with it and nobody will ever know.
Meaning you could send it to some other wallet and nobody can tell to which wallet you sent it, if you send something or received something, or which amount was involved.

Starting with Monero - verification?