Why do bubbles make a sound?

Question: I have an understanding of how bubbles work. They encapsulate air (or other fluids) in a membrane caused by surface tension.
When they pop, there is often a sound. Sound is a type of energy, kinetic to be precise, that usually occurs from collisions. When a bubble pops I would assume that a sound implies that air rushes out due to a pressure change. Why is there a pressure change? I wouldn't expect the bubble to exert enough pressure to compress air. If the sound is caused by the air now being able to move into the rest of the room due to Brownian motion, then why wouldn't I hear air moving in a still room?
Comment: I think if you could find some slow-motion (with audio!) of a bubble popping, it might be interesting.  I suspect the air is not the cause but the tension in the water film.  I'll bet the sound is either of the film "tearing" or of the tension accelerating the water together at the end where it "claps" together.  I was unable to find good audio for a bubble pop to see if it gave evidence for or against either of these ideas.
Comment: you can create your own pops with with you mouth and feel how much pressure is really needed to create an audible pop
Comment: I would think (based on how I make that sound) that it involves further exhalation, after examination, you seem correct. (@ratchetfreak)
Answer: The air pressure inside the (intact) bubble is larger than in the surrounding. This pressure difference is called Laplace pressure and is caused by the surface tension between the soap film and the air. When the bubble pops the compressed air expands, thus creating a pressure wave, which you ultimately hear as the typical popping sound.
Comment: The way I think of it from an intuition point of view is that bubbles want to be small, the surface tension is pulling all the parts together. This means that at that surface there is the outside air pressure pushing in, the inside air pressure pushing out and the surface tension pushing in. Thus the air pressure must be greater inside to balance that surface tension.
Comment: @Cruncher: That would depend on how the bubble was formed. In the case of soap bubbles created by blowing on a film then in woolly terms the blowing is applying a force that is compressing the air (a bit) while causing the film to buckle out. When it snaps into a bubble then the compressed air remains in the bubble, thus higher pressure. Use a balloon as an analogy and it might be more obvious in some ways (as long as you accept the analogy).
Comment: Hi David Zwicker, and welcome to Physics.SE! We usually like our answers to be a bit more self-contained, or at least link to some useful resources. I believe your answer might even be right, but it's bery hard for me to judge that from what you've written. For example, why is the pressure inside the bubble different?
Comment: I added a link to Wikipedia, which explains Laplace pressure much better than I ever could.
Comment: Is there an intuition I can gain for why the pressure is greater on the inside? I'd assume the very fact that it is contained by the bubble itself right? Off to look up a  pressure wave. Thank you.
Comment: Is it because cohesion forces are relatively more powerful on smaller scales, so only small bubbles can withstand the pressure gradient, but in larger ones they would immediately pop?
Comment: @Chris I was going to say this. But I was thinking. We know the pressure inside has to be higher, by the nature of the bubble. Is there any indication of *how* it got higher though?
Comment: Alright, this discussion got a little bit out of hands, so I decided to post a Q&A on why the pressure inside a bubble is larger than outside: http://physics.stackexchange.com/q/127695/45640
Answer: This page quotes the pressure inside a soap bubble as $\frac {4\gamma }R$, where $\gamma$ is the surface tension, about $25\text { dyne}/\text{cm }$ for soapy water, and $R$ is the radius of the bubble.  For $R=1$ cm, the pressure is then $100 \text { dyne}/\text{cm}^2 = 10 \text{ Pa}$.  This is released when the bubble pops.  It doesn't seem like much with the atmosphere being $101 \text{kPa}$ but it doesn't take much.
Answer: The surface formed by the bubble is such that its energy is minimized. Since increasing the interface between a liquid and air increases its energy due to surface tension, the bubble tends to reduce its radius, which implies that the pressure inside it must be higher than the pressure outside, and following this reasoning you may also get a quantitative result that relates this pressure difference with the principal curvatures of the interface (Laplace equation). Since the pressure is higher inside the bubble, if the bubble bursts, energy in the form of sound will be propagated.
Answer: Cavitation is the formation of bubbles in a liquid when a sufficiently strong negative pressure is applied. A point in the liquid experiences a "negative pressure" if the local pressure goes below the average pressure in the liquid. This can happen when water in a pipe has a very abrupt turn, near the propellers of ships and submarines, in presence of a high-intensity sound (you can imagine sound as an oscillation of pressure).
In the Cavitator, sound is pulling the water apart, leaving a bubble of gas which is due to the excess pressure inside
which is why smaller bubbles tend to pop with a greater sound (more pressure)
Comment: So the thought is that sound causes popping? I was thinking more along the lines of soap bubbles blown from a jar (with a wand). So would my blowing by the initial sound in this case?

Why do bubbles make a sound?


Nautilus cannot display what inside a mounted windows system partition

Question: I've using ubuntu dual boot with windows for years, since jaunty jackalope i think. i usually make three partition; 1 ntfs for windows system (C:), 1 ntfs for data storage and ext3/4 for linux. at first i could mount and access my ntfs C: and data ntfs out the box. but since the nth upgrade of lucid or precise (i dont remember) until now, nautilus stop to display the contents of C: (windows 7 system partition), but the data partition works well as usual. it seems that the drive c: is mounted, and the properties display correct usage of the drive, but i still cant see the files inside the drive in the file manager. i've searched on the web but no result, most of the cases are windows partition cannot be mounted.
I need to share my Download folder in windows with ubuntu while im working with ubuntu. Anyone can help?
Comment: It would help if you formatted and broke down that wall of text into easily "digestible" paragraphs. The title sounds like I can help you but I, like many people here (and elsewhere), can't be bothered to read paragraphs as long as the one in the current edition of your question unless they have a good incentive.
Comment: Could you please [edit] your question to include the output of `sudo lsblk -f`? Thanks.
Answer: Try mounting it through the terminal by
creating a folder to mount to with
sudo mkdir /mnt/windows

finding the partition with
sudo fdisk-l

Then with the partition you want,
sudo mount -t ntfs (disk partition) /mnt/windows

Then in nautilus, go to /mnt/windows
If it still doesn't work, then try
sudo apt install --reinstall ntfs-3g

Comment: Thank u NerdOfLinux for ur response. the partition is mounted, but nautilus still blank page, cant see the files inside. It seems to me that it's about the option in mounting process, but I dont understand the choices and how to use 'em. which option that prevent the file manager to display the contents of the partition. Any idea Nerd?
Comment: Sorry, I had a typo, please try it again now.
Comment: it's ok, I already fixed that. but still no result.
Comment: Can you access it via the terminal with cd /mnt/windows
Comment: it shows like this:
Comment: root@rig90:/mnt/windows# ls
ls: reading directory '.': Invalid or incomplete multibyte or wide character


correct usage with although/therefore

Question: but cannot be used in the same way at although/though. We use
but to connect items which are the same grammatical type.
https://dictionary.cambridge.org/dictionary/english/conjunction
The conjunction "although" joins the two clauses in the sentence "He left, although I begged him not to."
You can switch out although with but and other conjunctions, so is the explanation they provide not contradicting this.
He left, but I begged him not to.
He left, and I begged him not to.
Isn't the meaning the same and both grammatically accurate?
Answer:

He left, although I begged him not to.
He left, but I begged him not to.
He left, and I begged him not to.

These three sentence do not have the same meaning, and the first is far more natural than the other two.
The first means "He left, in spite of my begging him not to." In short the begging did not have its expected or desired effect.
The second suggests that the begging was somehow not expected to occur, but did. A better sentence using a similar construction would be:

He left, but I wouldn't go with him.

In this sentence the leaving happens  first, and the decision of the speaker not to go with "him" seems to happen after. There may be a suggestion that the speaker was expected to go. Here "although" could be substituted for "with" and the meaning would not change much.
The third sentence says that other person left, and afterwards the speaker begged him not to. This makes little sense. Better would be:

He left, and I begged him to come back.

In this kind of construction "and" usually indicates a simple sequence, and can often be replaced by "then" or "and then".

correct usage with although/therefore


Remove item entities in Single Player

Question: I accidentally loaded a string duper within lazy chunks and it caused 8000+ entities to render without being able to despawn. I'm trying to find a way to remove the items on the ground, however NBTexplorer hasn't been helpful since I'm playing BnC Advancement pack through the Curse Forge Launcher. I can still enter the world but loading the chunks crashes every time.
Comment: **This is not a request for *technical* support.** The problem is a large amount of entities (not a technical problem) of which the OP wants to get rid, and every solution would be helpful.
Comment: I disagree - surely using NBTexplorer to modify the world or a crash is a classic technical support issue.
Answer: First, make sure to back up your world before trying anything, in case you get stuck in a situation where you are unable to recover.
You could enable cheats (via NBTExplorer if you don't already have them enabled), give yourself a repeating command block and place it close to the item pile (without loading it in) and add this command to the command block:
/kill @e[type=minecraft:item,nbt={Item:{id:"minecraft:string"}}]

If you were duping a type of modded string, you want to replace the id property ("minecraft:string") with the type of string you are trying to clear. If it was multiple types, you can either use multiple command blocks or remove the NBT argument and hope for the best. Make sure to activate the command blocks!
You can then load the chunks (facing away from them if that helps) and hope the command blocks are able to resolve the situation.
Once you've cleared all of the entities, destroy the command blocks and use NBTExplorer to disable cheats if you didn't have them enabled before. It might also be wise to disable the source of the problem.
Comment: And *before* anyone points out that they can't use NBTExplorer to fix the problem, please note that I am saying to modify level data and not chunk data, which is what OP tried to do.
Comment: How can /kill possibly affect entities in unloaded chunks? Surely if the entities are loaded enough to be killed they are loaded enough to crash the game.
Comment: @pppery I don't know if the game is straight-up crashing or simply freezing. If it's actually crashing I'd need a crash report.
Answer: If you have cheats enabled, go to the chat & type /kill @e[type=! player], which will kill all entities except players.
Comment: Although that is a decent answer, this person might not have cheats enabled.
Comment: Also I don't think kill affects entities in unloaded chunks anyway.

Remove item entities in Single Player


ERC721 "Digibles": different than Bitcoin colored coin concept?

Question: As I understand ERC721 contracts, in particular Cryptokitties, a cryptokitty is not associated with a piece of ETH but rather is just some storage associated with the Cryptokitty smart contract. Is this correct? That is to say, while a cryptokitty is a token on the Ethereum blockchain, it is not a token in the sense that ETH is a token/coin?
Answer: An ERC721 compliant smart contract has an array (or ledger) of who owns which tokens and what the properties of the tokens are. It also implements some standard functions that make it easy for people to predict how they will work. You can think of it as a homemade token, maybe.
You can think of Ether as the systemwide (ie not homemade) token.

a cryptokitty is not associated with a piece of ETH

Specific "pieces of ETH" can't be associated with things. They are nonfungible, which basically means they don't have unique IDs.
Not the greatest explanation, but hopefully it helps a bit. I would continue reading up and watching videos on general Ethereum concepts.


Should I wait for version 6.0 or can I install elementaryOs right now?

Question: The reason I am asking is I want to switch from Windows to elementaryOs on my laptop before I go on a trip and I want to know if I will be able to update elementary from 5.x to 6.0 when the full release comes out or should I wait with my install till the 6.0 is finished?
Answer: It is currently not supported to update Elementary OS between versions.
However, since it's Linux running under the hood there may be someone who releases an "update script" that accomplishes this in the future.


Problems upgrading from 9.04

Question: When I try to do a distribution upgrade, my mouse and keyboard completely stop responding, if I plug them back in, they continue to not respond.
Answer: I really REALLY recommend to not do a distribution upgrade. you would need to download from each distribution upgrade than just download 11.04 and doing a backup before starting fresh. This is, assuming you wan to upgrade from 9.04 -> 9.10 -> 10.04 -> 10.10 -> 11.04
We are talking more than 1GB of download of distribution upgrades comparing it to downloading the 700MB Ubuntu 11.04 and doing the backup and installing it fresh (And feeling you PC as new as ever...and happy too)
Comment: The problem with that is that when I try to install the 11.04, or even the 10.04 Ubuntu refuses to boot afterwards, when I try to reinstall the installer recognizes it as Ubuntu but it never boots. Never even gets to GRUB, the only way I can get it to work is through 9.04 (ugh). (The 11.04 installer complained about not being able to install GRUB), I've had Ubuntu on this computer before, I tried to install Windows 7 and it ate my ubuntu partition :(
Comment: Ok what error does is popup when installing. Can you select from the Live CD/Live USB main menu "Try Ubuntu" but before pressing enter press F6 and remove the last part of the line that reads "quiet splash --" then press enter. It will start loading but showing you what is happening step by step. There are also several options to try when you press F6 since a small menu will appear. If you press ESC when that menu appear then you can eliminate the options i mentioned above.
Comment: The Live CD works just fine, but after install nothing boots.
Comment: There was an error message in the 11.04 install about GRUB not being able to install
Comment: Can you post the error here. When did it say it, what did it say?

Problems upgrading from 9.04


How can you get ReqBin to POST a body to a logic app?

Question: How can you get ReqBin to POST a body to a logic app?
I'm baffled trying to get ReqBin to actually send a body! It thinks it is, but the logic app doesn't think so. I've checked using Curl that the logic app is working as expected, i.e. it's accepting a POST request with request body. The test request has a 15 character body, and the logic app shows the expected details; both body and the various headers; content-type and content-length.
When I try to use ReqBin, it reckons it's sent the test body of 15 characters, see below. But the logic app reckons there was 0 content-length.
I'm trying similar in ReqBin, because it's a lot easier to just cut & paste each of my test request bodies into the web UI, rather than hand-encoding each of the JSON request to use in a Curl command.
How can I determine where the content is being lost, when Curl works, but ReqBin doesn't ?
ReqBin ...
POST /workflows/c604f34c750c49cba716f2998b1ce1d3/triggers/request/paths/invoke?api-version=2016-10-01&sp=%2Ftriggers%2Frequest%2Frun&sv=1.0&sig=xxxxxxxxxx HTTP/1.1
Host: prod-57.northeurope.logic.azure.com
Content-Type: application/json
Content-Length: 15
{"key":"value"}

and the response from the logic app ...
body:
headers:  {"Transfer-Encoding":"chunked","Accept":"*/*","Accept-Encoding":"deflate,gzip","Host":"prod-57.northeurope.logic.azure.com","User-Agent":"Mozilla/5.0,(Windows NT 10.0; Win64; x64),AppleWebKit/537.36,(KHTML, like Gecko),Chrome/64.0.3282.140,Safari/537.36,Edge/18.17763","Content-Type":"application/json","Content-Length":"0"}

I don't believe it's the logic app, as I can happily do a POST with body in both Postman and Curl. It's just ReqBin that doesn't seem to want to send the body.
Curl ...
curl -d "{\"key\":\"value\"}" -X POST "https://prod-57.northeurope.logic.azure.com:443/workflows/c604f34c750c49cba716f2998b1ce1d3/triggers/request/paths/invoke?api-version=2016-10-01&sp=%2Ftriggers%2Frequest%2Frun&sv=1.0&sig=xxxxxxxxxx" -H "Content-Type: application/json" -H "Accept: application/json"

and the response ...
body: {"key":"value"}
headers:  {"Accept":"application/json","Host":"prod-57.northeurope.logic.azure.com","User-Agent":"curl/7.55.1","Content-Length":"15","Content-Type":"application/json"}

Answer:
In your curl example, you have added "Accept: application/json" HTTP header but missed this header in ReqBin request. Some servers reject sending JSON back to the client when the client doesn't provide this header. Please add this header on the Headers tab and try again.
Do you get the same result when making your curl request in ReqBin Curl client?
https://reqbin.com/curl


Does Agar Agar expand in the stomach if not diluted enough?

Question: This might be an odd question. But I am making gummybears from fruit i mixed smooth in a food processor and agar agar. I read that agar is a potential chocking hazard when taken with insufficient amount of water. Since I used about 3 teaspoons for my mixture to set it firm, will it expand once it comes in contact with the fluid when eaten? Or is the structure changed once it got heated and then cooled again into jelly form?
Comment: From that website I get the impression that it is about digesting agar directly (or at least in large quantities in order to lose weight): *Take agar on an empty stomach with at least 8 ounces of water*. That would not apply in your case.
Comment: Agar is a gelling agent, made from seaweed.  I can't imagine how it would be a choking hazard.  Gummies themselves, of course, could be a choking hazard.
Comment: @moscafj Certain gelling agents can increase the risk of choking because of their nature (https://en.wikipedia.org/wiki/Konjac#Choking_risk). I don't think that applies to agar, though.
Comment: I have edited your text and changed *choking* to *obstruction*. I assume you did not mean suffocation. If you *did* mean choking your question needs a rewrite because that is not in the stomach *and* that link does not apply.
Comment: I am wondering about obstruction and if it is a choking hazard actually. I will edit it once I am able to get to the webmd page: https://www.webmd.com/vitamins-supplements/ingredientmono-80-AGAR.aspx?activeIngredientId=80&activeIngredientName=AGAR&source=0
Comment: "Chocking" is the process of inserting a wedge under a wheel or tyre. "Choking" is asphyxiation due to an obstruction in the throat.
Answer: Assuming that you are worried about the expansion rate in the stomach from having an insufficient ratio of water to agar during digestion, a quick search came up with the following results from wikipedia (https://en.wikipedia.org/wiki/Agar):

Agar-agar is approximately 80% fiber, so it can serve as an intestinal regulator. Its bulking quality has been behind fad diets in Asia, for example the kanten (the Japanese word for agar-agar[3]) diet. Once ingested, kanten triples in size and absorbs water. This results in the consumers feeling fuller. This diet has recently received some press coverage in the United States as well. The diet has shown promise in obesity studies.

The same Agar used in culinary dishes is the same one used in laboratories for testing.  Resistance to high temperature (melting point is 85 °C) makes Agar ideal for studies that need an environment to mimic human body temperature.  This means that Agar will not melt in the body once digested.
Melting Agar is also not the same as denaturing Agar.  The act of melting it to form and then cooling to set does not change the structure and properties of Agar.  Just like how ice melts into water and you can freeze again while also being able to reverse the process at any time, you can do the same with Agar just at a different temperature.  Since the Agar has the same properties as before melting, this does not keep it from expanding when exposed to water.
To add to this: Just because your body does not get hot enough to melt agar, that does not mean the bacteria in your intestine won't break it down into smaller molecules and denature the Agar to aid in digestion.  Source: https://www.ayurtimes.com/agar-agar-kanten/
Comment: "Since the Agar has the same properties as before melting, this does not keep it from expanding when exposed to water." does this conflict with the answer @Bugmo gave "Like other gelling agents, agar becomes more liquified and hence softer ..." or do is it expanding but liquefying more? I guess my worry is that if the gummy bears have enough agar in them that they will only expand to a point where they can become a danger and not enough to be liquid.
Comment: @OliverSchöning The more liquid you add, the less absorption will take place.  That will have to do with the saturation properties of Agar though and that has more to do with chemistry.  For a rough guess you would need "20 times the weight of the agar in water" to keep further absorption to happen, but that makes unsatisfying gummies.  The only saturation statistics I could find on Agar are at this link (very chemistry oriented): http://www.agargel.com.br/agar-tec-en.html
Comment: @OliverSchöning I wouldn't worry about Agar expanding to be a danger unless you are eating super concentrated Agar gummies (to the point they would be borderline inedible) and you are dehydrated.  As agar expands and absorbs water it will break down into smaller chunks by the churning of your digestive system.  As long as you drink some water while eating your gummies you should be fine.
Answer: The short answer is: Yes, it can. But it's not really about dilution.
Agar agar, along with foods such as chia seeds and flax seeds, are mucilaginous. This property can indeed pose a hazard if the ingredient is consumed while it still possesses a substantial capacity to absorb water. In this case, the product absorbs moisture from the alimentary canal, which can lead to an obstruction of the gut. There is at least one well-documented case of this occurring with chia seeds.
This risk can be completely mitigated by near-total hydration of the ingredient, i.e., by assuring that its capacity to absorb water has been nearly exhausted. To do so, find the absorptive capacity of the ingredient. My research found that agar agar's capacity is to absorb about 20 times its weight in water. Thus if your finished product contains 1Kg (1 liter) of water and 50 grams of agar agar, you have nothing to worry about. (You should do your own research and not rely on mine.)
I would guess that your finished product is actually substantially dryer than that, and as such, consuming substantial quantities of the product along with dehydration could lead to an obstruction. I would suggest eating this "food" with water.
Answer: Like other gelling agents, agar becomes more liquified and hence softer in the presence of the warmth of one's body and the liquid present in the digestive system. Therefor the cooked agar is not in itself a choking hazard, though, as noted above, the gummies could be. It is only agar that has not been combined with liquid, heated, and gelled that it is a choking hazard. So your cooked agar is not a danger. (Though I did notice a distinct flavor from the agar when I made a similar recipe several years ago.)
Comment: exactly, yes. Not rapid expansion.
Comment: Do you mean the gummies could be a choking hazard in the same sense how all foods can be a choking hazard? Not rapid expansion.


What is the difference between contract, deed and covenant?

Question: What is the difference between a contract, deed and a covenant?
Answer: A contract is an agreement legally enforceable against at least two people, in writing or otherwise.
A deed is a formal document conveying an interest in real property from one party to another.
A covenant is most typically going to refer to a condition that is part of either of those transactions, such as a contractual covenant not to compete or a deed covenant to use property in a certain way.
Comment: No, it does not.
Comment: @bdb484 A deed can also give effect to an agreement (like a contract) in the absence of consideration by one party.
Comment: Thank you. Is "consideration" mandatory for a contract?
Comment: Consideration is necessary for a contract, though some agreements may be enforced as though they were contracts despite the absence of a consideration.
Comment: Thank you. Does consideration need to be monetary?
Answer: You may want to search for these words in the Black's Law Dictionary. That legal dictionary is a very useful starting point for when one needs to do legal research.
After reading the definitions, feel free to ask about any specific details that might remain unclear to you.


Can anybody know the saved passwords on browser?

Question: There is a option almost in every web browser to save passwords.Can any site know these passwords from browser?I these passwords are saved in encrypted format?
Answer: No, only your host PC can. If your computer was compromised, however, it would be quite easy for people to get these passwords as most browsers do not encrypt them.
Comment: Do you have a reference for browsers not encrypting the passwords? That'd be a huge security flaw.
Answer: Typically browsers (assuming they are not vulnerable - which they might be) do not provide a method for websites to get your passwords, however, if you have not set a master password or opted for an encrypted profile, it will be easy to for other programs to snatch them. So it is a good practice to have a master password set.
Fimally, bear in mind that most of the modern browsers (read Chrome and Firefox) can, and sometimes subliminally sync your profile, which MAY include your passwords. That means that saved passwords are not only stored on your machine but also on the sync servers.
Just so that you are aware of some of the risks.


Provide external link without exposing record id?

Question: I have visualforce page that displays information from custom object. I get id from the url and do SOQL query in controller.
Client wants to send the link to this page (hosted on Salesforce site). What is the best practices for record id? I'm not sure that is good solution to provide link like site.force.com/your_page?id=salesforce_id because we are sending original Salesforce id of the record.
Comment: Your user ca still access recordId from URL. Unless you use some manual encryption.
Comment: Can you please clarify your current approach and what is wrong with it?
Comment: Adrian, the thing is I'm not sure that is good idea to display salesforce record id of security reason.
Answer: For the most part, exposing an ID is completely harmless. The limited exception I'd place on that rule are 00DXXXXXXXXXXXX Id values, which can allow spammers to hit your web-to-lead or web-to-case queues if enabled. Even salesforce.com uses ID values in various places, such as Help & Training, the Developer Forums, etc. For example, here's a question (picked at random) from the Developer Forums:
https://developer.salesforce.com/forums#!/feedtype=SINGLE_QUESTION_DETAIL&dc=Developer_Forums&criteria=ALLQUESTIONS&id=9060G000000UUKbQAO
However, what is important is to make sure your code runs "with sharing", so that the user can't query or modify a record they shouldn't have access to, and make sure your security model (OWD, FLS, profiles, sharing rules, etc) are correctly configured.
Answer: If you want the URL to be in encoded form then you can have a java-script button that will encode the id and will send it to custom attribute with a random name like  not a obvious name like '?Id=*' . Then you can in constructor get the apex parameter value, decode it and run the SOQL.
Comment: Thanks Adrian! That is good point. As @sfdcfox mentioned I can use id but I should sharing rules/profile settings correctly.
Comment: @EugeneVabishchevich Just want to point out that this answer was given by Rachit, not Adrian (Adrian simply made a couple of simple edits).


Getting to POSE mode in 2.77a

Question: How, pray tell, are you able to get to POSE MODE in Blender version 2.77a? I've imported a free, rigged model I downloaded to practice animating, but cannot get to this mode. CTRL + TAB does not work. Help please!
Comment: Try the dropdown with the name "Object mode" in the bottom of the 3D View. Select "Pose mode". Of course, the object must be posable.
Comment: Thanks, Gunslinger. I tried the object mode drop down menu. Pose mode is not there. If the object is not posable, shouldn't pose mode still show up? If not, that may be the problem. This is an .obj model (which I think originated in 3D Max), and I have discovered that this is not the rigged version. The rigged version is a .max file, which Blender does not read. Might then the answer be that I have to rig the model first, before pose mode is viable?
Comment: A hint, try using the rigify addon (if you are rigging a humanoid). When you have problems with it, come back here. :-)
Answer: Ctrl+Tab will toggle pose mode if an object of type 'ARMATURE' is selected, or it will toggle weight paint if an object of type 'MESH' is selected.
Otherwise, you can select the armature in your 3D View (or outliner), then select pose mode from the menu in the header.
Comment: Thank you, Timaroberts. I think the problem is, as I recently discovered,  that the model is not rigged after all. I am supposing this precludes the ability to see (e.g., through the object mode drop down menu), much less get into pose mode . Am I right about that?
Comment: @Anthony yes, pose mode is only available on armature objects.
Answer: Select the armature in the outliner panel and this should give you pose mode when you change from object or edit mode.

Getting to POSE mode in 2.77a


Format all Hard Drives within Domain

Question: I am currently running a domain with Windows Server 2012 R2 as the DC. Is there a way I can format every single hard drive within the domain then fill all the drives with useless data so the original information isn't easily recoverable? The goal is the create a security application that I can trigger in the event there is a break in.
Comment: This seems like a pretty silly idea.  If there is a breakin, wouldn't the attackers just turn off the power?  Better solution:  Setup full disk encryption, just computers off when they are not in use.
Comment: Encrypt!  Data on formatted drive is still recoverable!
Comment: I think you need to think this through: 1. Are robbers going to patiently wait for your format and re-write to finish before unplugging? 2. How is it going to trigger? The cost of a false alarm is astronomical! 3. What about machines that are powered down? Encryption is the key here.
Answer: Run full disk encryption and in case of break-in just wipe the data or use a program like RDFC to overwrite important files.

Format all Hard Drives within Domain


What should I answer in "Do you have other incomes or savings?

Question: I am an employee with regular salary in UAE and I'm applying for UK standard visit visa, I don't have other incomes but I have savings that I have saved using my salary so should I choose savings?
Answer: As you have savings you should mention those in answer to that question, even when you do not intent to use them for the trip you apply a visa for.
Visa officials will want to know that you can afford the trip, not just have enough money to come but also have some money in the bank (or in an other way) to tide you over if needed.
If you have no other income, you can not chose that.
Answer: According to 5.12 in these guidance notes https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/589168/VAF1-guidance.pdf you should answer 'Yes' and provide details.


Different kind of infinitesimals or zeros

Question: If there are different kind of infinities (aleph0 aleph1 and so on) then are there different kind of infinitesimals? Or should I consider zero the "opposite" of infinity if there is such a thing and ask the same questions with different kind of zeros?
Comment: Aside: $\aleph_0$ and $\aleph_1$ are the same *kind* of 'infinity': they are both (infinite) cardinal numbers. Cardinal numbers are unrelated to infinitesimals.
Answer: In a nonstandard model of the reals $0$ is not the reciprocal of any element. There are infinities of various magnitudes, and their reciprocal steps are infinitesimals of various magnitudes. If you throw away the infinitely large and small elements and identify all infinitesimals to $0$, then you obtain the classical reals as a quotient. So, different infinities correspond to different non-zero infinitesimals (bijectively) and $0$ is not the reciprocal of anything.
Addendum following comment below: You can view a one-point compactification as adding a point at infinity. But that is a topological intuition that has little to do with any kind of reciprocal of $0$. The closest I can think of to address your intuition can be gathered from "The reals as rational Cauchy filters", New Zealand Journal of Mathematics, to appear, available here. In that article I show how to construct the reals as rational Cauchy filters. Then $0$ is the minimal Cauchy filter containing every rational neighborhood of $0$. Filters are very robust, and in particular you can often extend partial operations on the rationals to a full operations on filters of rationals, point-wise. So, the partial operation $x\mapsto 1/x$ extends to an operation on filters, and thus $1/0$ is defined. In more detail, $1/0$ is a certain filter, but it is, of course, not a minimal Cauchy filter since that would make it a real number, which is impossible. But it is a very concrete filter. That filter can be shown to have certain characteristics making it an infinitely large extended real number. I hope this is in line with what you are looking for.
Comment: What about the real projective line to consider zero the reciprocal of infinity?
Comment: @Masacroso I extended my answer to address your further question.
Answer: There are different ways of formalizing infinity in mathematics.  Cantorian set theory is only one of them, and not necessarily the most useful one.  Cantor himself was virulently against infinitesimals, claiming that he proved their self-contradictoriness (the published proof was incorrect).
A different approach was that proposed by Abraham Robinson around 1960.  Here one constructs a proper order field extension denoted ${}^\ast\mathbb{R}$ of the real field $\mathbb{R}$.  The extended field contains both infinite numbers and infinitesimals, and they are precisely in the reciprical relationship that you indicated.
For a gentle introduction to these ideas see Elementary Calculus.


What was the lift-to-drag ratio for WWI biplanes?

Question: I will be interested to know what was the lift-to-drag ration for a few more known WWI biplanes at take-off, cruise and landing speed; with the propeller running, stopped or non existent (tests in wind tunnels).
Comment: It'll be tough to find that unless you rummage around university study archives or find some old NACA reports.  It's easy to give a ballpark figure.  Reasonably clean monoplanes are generally 8:1 to 11:1. A flying barbwire fence like a WW1 biplane would range from 4:1 to 7:1.
Comment: @JohnK I'm looking at Wikipedia. Maybe I could infer the value from the specs?
Comment: I don't think you could.  You would have to be able to work out the glide angle at different speeds, and so you'd have to have the sink rate at a given speed.
Comment: @JohnK well, what i was trying to do was get the thrust/weight then reciprocal. You know, get a lower bound value?
Answer: AE Berriman published his respected survey of Aviation in 1913. At that time drag was known as resistance, with other terms such as head resistance or drift also used. He discusses the lift:resistance ratio only with respect to aerofoil design.
It is unlikely that the l/d of the whole aircraft was ever considered quantitavely as a useful number. One might gain some idea by looking at Farnborough wind tunnel results for propeller thrust at given airspeed and RPM, and then comparing those with aircraft fitted with that propeller, but that would have been of little value in a hectic war and would not have been done. Of more use was the relative speeds of different types when given the same engine and propeller, or of a given machine when fitted with a new propeller.
Pilots would have had some idea of how far their machines would glide when the engine failed, as happened often enough, but only hazy notions of actual speeds and sink rates. They would also have struggled with the fact that the gliding speeds and angles for minimum sink rate and maximum distance were different.
With hindsight we can make guesses. Glide slopes remained well below 1:10 until the German soaring gliders of the 1920s. Airspeeds were slow, around 100 mph, so thrust and drag were not as high as might be expected today. While engines had relatively poor power-to-weight, airframes were so light they would sometimes break up under the extreme manoeuvres of combat. A steep gliding angle of say 1:4 would have required an unrealistically powerful engine to generate thrust (nominally) equal to a quarter of the gross weight, so wings were relatively large and lightly-loaded to give better lift at lower speeds.
So I'd hazard that around 1:5 to 1:8 would have been the norm. If anybody knows of a better-researched analysis, I would be delighted to be proved wrong.


Do smart-contracts work as APIs?

Question: Is it possible to put a smart contract "behind" a restful API, i.e. expose my contract functions and properties through restuful API where I can make RPC to it?
Or does it work as an API already, but instead of GET/POST requests, there are .CALL()/.SEND() requests?
Answer: Read operations you can put behind a regular API as you get the result instantly. As for write operations, you can expose an API which has something like "initiateFunctionA" and another operation which returns the results when it's ready but you shouldn't keep the API call hanging waiting for the result to the write operation - it may take a while (or even infinity if you have too low gas price).

Do smart-contracts work as APIs?


How to view output for ALL processes simultaneously?

Question: I know that you can connect to various background processes to watch their console output, but is there a way to view the output of all processes at once? Likely it would scroll quickly and be hard to read, but is it possible?
Answer: Well, you can spawn several processes in your shell in the background and then (if they all use their stdout or stderr) you can get lots of information intermingled in the console - and by intermingled I mean it can possibly even mix data from several processes in the middle of a line.
What you are probably looking for is logging to a file (system services usually use something in /var/log) and then viewing the file(s). There are couple of utilities for this: tail (important option -F, which monitors the file and prints any lines added), less can (in the follow mode) do the same interactively (i.e. you can switch back and forth between following the file and scrolling back). most is another interesting file pager utility, more is the "classic" one found almost everywhere (even on DOS and Windows).
Last but not the least, tee might be of interest - it duplicates its stdin to stdout and to a file, which can often come in handy.
Answer: If they all write to a logfile, you can use multitail to tail them all simultaneously.
Answer: All processes?  Most background processes actually intentionally close their file descriptors, and there's no easy way to grab them back or force the process to recognize a new one.
You can watch all the messages to syslog, as others have said, and a lot of user-spawned processes do actually have their output directed somewhere (at least, if you're running a sane X startup environment), so you can watch a lot of them if you know what files to look at.  But for the most part, you can't see the output of ALL non-user processes because they simply don't have anywhere defined to send output.


Why didn't the hero association use Hitoshi the guy with the brainwashing quirk to make AFO leak information?

Question: Why they didn't use him which such a strong quirk? Did it got explained in the anime or manga, or did the author just forgot he even existed?
Answer: Since there isn't any objective answer to this, we can only speculate on the matter. Probably the obvious and simple reason is that Shinso isn't a fully fledged hero and exposing a kid to AFO interrogation isn't quite the most ethical thing to do and also AFO probably has barriers and others countermeasures to prevent brainwashing or mind reading.
Answer: During the Joint Training Arc Shinso explained some of the limitations of his quirk, namely that he couldn't make brainwashed people do anything that requires using their brain in a non-trivial capacity or that would require them to speak.
Answer: I don't think he could make the brainwashed talk. If he did, he would have just made Deku forfeit instead of having him walk out of the arena. Also, don't you think that if the guy who absolutely trashed All Might was in front of him, he would be a little scared.


Is review history not public in private beta?

Question: I just crossed 350 and now can see review queue but not able to see review history. On clicking History option for any review it only shows my own reviews. But in Other site graduated or Public beta i can see all review history. Is it happening just to me or  review history in Private beta kept Private?
Comment: This seems unintentional. I'll have an ask internally to see what comes up on it.
Answer: I am only 3K on Stack Overflow, and I can only see my own history, but I am 10K on Meta Stack Overflow and I can see all.  I think it is a 10K privilege (or the beta equivalent), so I am virtually certain this is status-bydesign
Comment: "Moderator tools" is kind of vague and, AFAIK, not enumerated anywhere, but it does seems to me that the review history is one of the things included under that heading. So it should be a 1K privilege here.
Comment: Ohhh...its the case. I noticed that i am also unable to see review history on SO because of 1k rep but can see it in Movies and TV beta because i have 9k+ rep there.
Answer: Yes, this is status-bydesign. Viewing the full history for any queue is a "mod tools" privilege. We just added a small note on this to the mod tools privilege wiki.


Symbols in Mac OS

Question: Where can I find those symbols on Mac OS such as Apple logo, small iPhone?
Answer: You need the Special Characters Palette. You can usually access it from almost any program and it's a generic palette, so the changes you make, will be global and shared across applications.
It's almost always (by convention) located in the Edit menu of any application. In this case, this is Google Chrome's Edit menu:

Once you select the Special Characters palette, you will be presented with the following palette, where you have to click on it's "toolbar"
and select Customize List:

From the sheet list, scroll down until you find Sign/Standard Symbols, and/or experiment with others. You can find things like: ☎☏✆��
Please bear in mind that:
1) The above screenshots were taken under OS X Lion (10.7), the Snow Leopard version of the Character palette is similar and you will find it in the same place, but as far as I can remember, won't allow customization, you'll have to play seek and find. :)
2) OS X Lion supports Emoji, which cannot be displayed in Stack Exchange and I'm not sure what other OSses support them natively. This is what the Emoji look like:
Answer: Open Keyboard from System Prefs & klick show Keyboard & Character Viewer in Menu bar
Open language & text in SystemPrefs & select Input Sources, & check keyboard & Character Viewer.

Then go to the menu bar, click on the inout sources icon & choose character viewer.
Comment: Can't find them there.
Comment: Opps, my bad forgot a part will edit the answer
Comment: I mean I cannot find some specific symbols I am looking for in there.
Comment: Try to press Alt/Cmd/Ctrl/Shift in different combinations while Keyboard Viewer is opened and you'll see the magic :)
Comment: 'Shift' + 'Option' + 'K' =  Wohoo! :)
Comment: Some of the symbols you're looking for probably aren't in any of the default fonts -- there's no unicode character for "Apple logo" or "small iPhone". For those, you'll probably have to try to find and install a font like "Mac Dingbats" that contains Apple-related glyphs.
Answer: There is also a Dashboard widget from Tacowidgets called CharacterPal that will display all of the extra characters in a small window. place your mouse over the character, and it will display the key combination to create the character.

Symbols in Mac OS


How did SegWit start

Question: My understanding of SegWit is that any non-segwit (legacy) nodes will see a SegWit output as an output anyone can spend (i.e. no signature required). This is currently fine since if the miner mines a block with a transaction that tries (illegally) to spend from that output, it will be rejected by the majority of the nodes because most nodes support segwit and see that there is no witness proof as part of the transaction. But my question is how could a segwit output possibly be used in the beginning when segwit was just launched and the majority of the network where non-segwit? Then anyone could just spend the segwit outputs?
Thanks!
Answer: Segwit was activated using bip9. The precondition for segwit's activation was that 95% of the hashrate was signaling readiness to enforce segwit's rules. Also, a majority of the other nodes had upgraded at that point. Quickly after activation, almost 100% of the hashrate was running a segwit-compatible version.
Comment: I'm not aware of any reason to run a legacy miner except for ideological opposition to segwit. I do know multiple reasons against it: a legacy miner would not include any segwit transactions, since they look non-standard to a legacy miner. As today 5/6 of all transactions use segwit, they would earn less transaction fees (but fees are still only a tiny part of the block reward). Also the last non-segwit version of Bitcoin Core is severely outdated, it has been end-of-life (beyond maintenance patches) for more than four years at this point.
Comment: Thank you so much! Are there any good reasons for why anyone would want to run a legacy miner these days? I assume they are open for attacks where someone can send them invalid transactions (with a high fee to make sure they are accepted to the block) and any block mined would immediately be rejected?

How did SegWit start


Problem on speed of light

Question: As I was reading special relativity, my book says the speed of light is $c$ with respect to any other thing. Does that mean the speed of an individual photon is $c$ even with respect to another photon? I mean, shouldn't the relative velocity be zero?
Comment: Related: http://physics.stackexchange.com/q/16018/. That comes awfully closing to being a duplicate because the answer is *"the question doesn't make sense because it presupposes a rest frame for one of the photons."* Also http://physics.stackexchange.com/q/68600/ .
Comment: I've answered his question in detail. While it's true that the answer to the question you posted must be mentioned, it doesn't strike at the heart of what he's asking.
Comment: Which book? Which page?
Answer:
Does that mean the speed of an individual photon is c even with
  respect to another photon? I mean, shouldn't the relative velocity
  be zero?

When we write
<code>"the speed with respect to X"
</code>
we mean precisely
<code>"the speed as observed from the inertial frame of reference in which X is at rest"
</code>
Thus, if it is true that the speed of an individual photon is $c$ as observed from any inertial frame of reference, it logically follows that there is no inertial frame of reference in which a photon is at rest.
In other words, if it is true that the speed of an individual photon is $c$ as observed from any inertial frame of reference, then the phrase with respect to another photon presumes something that isn't true.
Answer: The whole point of special relativity is that imposing this postulate (on the constancy of the speed of light) forces a reunderstanding on the very geometry of space and time. This re-understanding can be summarized by the Lorentz transformations. These describe the coordinate transformations required when transferring measurement from one observer in reference frame $S$ to another, $S^\prime$, that is moving relative to the first one. If the motion is along the x-axis, these are :
\begin{eqnarray}
t^\prime &=& \gamma (t - vx/c^2) \\
x^\prime &=& \gamma (x - vt) \\
y^\prime &=& y \\
z^\prime &=& z
\end{eqnarray}
Where $\gamma = 1 / \sqrt{1 - v^2/c^2}$. These relations are quite different than the more intuitive Galilean relations, and herein lies the answer to your question. Notice that we hit a singularity for $v = c$, so we can't answer your exact question. In other words, it is impossible to see things from the point of view of an observer moving at the speed of light. However, let us change your question a bit in a way that makes it possible to answer your conundrum. You are observer $O$. Relative to you, observer $O^\prime$ is moving at $0.9c$. You observe a photon moving toward $O^\prime$ at speed $c$. Now, let us transform the motion of that photon as seen by $O$ to the reference frame of $O^\prime$. Of course, if you were to use the classical Galilean transformations, you would find $1.9c$. However, if you were to use the relations given above, you would again find that the speed of the photon is $c$. Those relations were specifically designed to obtain that answer.
Answer: The idea behind special relativity is that the laws of physics do not change from one reference frame to another (this is key).  So, if you're moving at velocity v, a photon traveling in that reference frame will travel at c (not c - v, which is the classical Galilean transformation).
I believe this is what your book means when it says "with respect to any other thing."
Now, about your question regarding two photos - I don't believe that you can travel at exactly c without some consequences.  For instance, the look at the equation for time dilation - it blows up for v = c (the Lorentz factor has a singularity).

Problem on speed of light


What is the recommended thinset when tiling over concrete?

Question: I am about to start tiling a concrete area of my home about 220 sq feet. I was wondering if there is any specific type of thinset I should be using for a concrete surface. The tiles will be 12x12" ceramic tiles.
Answer: I use this type of Flexbond for concrete applications - well most applications.  This will isolate cracks up to 1/16th of an inch.  Also this stuff really bonds well to concrete.  I know that you can buy that $10 bag but I wouldn't skimp on the thinset.  I can say I have done a lot of tiling and not a crack yet (knock on concrete).
Also want to mention that I end up doing a lot of glass mosaic patterns (even in floors) and this stuff (get the white for glass) works great.
Comment: Yup, that's the stuff to use. Never skimp on the most important component of the floor system


What is the word used when you are aware of a wrong doing or crime, after the event but do nothing about it

Question: Looking for a crime or misdoing that has been done and you are aware but chose to do nothing about it. Say in court how would a lawyer explain this
Comment: Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.
Comment: You are aware of a crime you committed?  someone you know committed? a stranger committed?   How are aware? Because you saw it? Because you heard about it? From the person who did it? From a witness? From a someone who heard it from someone else?  I saw someone speeding past me on the highway and didn't call the cops…
Answer: Misprision of felony consists of

failing to report knowledge of a felony to the appropriate authorities.

It has been removed as a crime in many jurisdictions.


Netbeans dist jar file giving NoClassDefFoundError

Question: Yes I have a project that I'm working on in NetBeans 7.1 and I come to the point where I want to use the jar file on a different computer but when I try to run it it gives a NoClassDefFoundError. But when I run it on my computer it works fine. I've extracted the .jar file all the classes seem to be there. I've checked to see if netbeans thinks my project is the main project and that it has a main class which I also confirmed in the MANIFEST.MF file. My program does have swing components if that affects anything.
Edit
Also there are no other folders in my dist folder like any lib or picture folders
I have also clean and rebuilt about a hundred times
/Edit
Here is the error
Caused by: java.lang.ClassNotFoundException: ClubControl.jar
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)

I have searched through countless articles on this subject and still I don't think I have found the problem. Hopefully I didn't miss it and someone responds with a link to another question.
If any other info is needed just ask.
Edit
here is the MF file
    Manifest-Version: 1.0
Ant-Version: Apache Ant 1.8.3
Created-By: 1.7.0_01-b08 (Oracle Corporation)
Class-Path:
X-COMMENT: Main-Class will be added automatically by build
Main-Class: GUI.MainWindow

Comment: All of my class files are in two folders/packages and when I extract the .jar file I confirmed this.
Answer: From the exception stacktrace it would seem that a class is misnamed somewhere in your code:
Caused by: java.lang.ClassNotFoundException: ClubControl.jar
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)

It appears to be trying to load up a class named ClubControl.jar - there should be no extension on the name, and definitely not a .jar one.
Comment: No all my java files have a package.
Comment: I misread your stacktrace - lack of sleep! While going over it again I did notice that the class its trying to load has an odd name (.jar extension?). You might want to check that.
Comment: I don't know why it would be looking for that file. This error was given from a mac, when run on a pc the error given is that the program cannot find the GUI.MainWindow class. I added the MF file above.
Answer: You have to include other dependencies of the .jar. Like /lib folder or sometimes if you have images on the project you have to include those as well and make sure that the .jar can locate those dependencies. And try to Clean and Build the Netbeans project.
Comment: I don't have any lib folders and I don't think there are any dependencies. I have also ran Clean and Build plenty of times.


real life distribution question

Question: Me and my wife had bought and planted ~20 plants in ~8 pots in our garden.
the plants are of the same specie and were all very much alive when we bought them.
The number of plants per pot varies as the pots are of different size.
I've notice that some many of the pots are dying/dead and I think that the proportion of dead is different in different pots which would suggest that something in the pot (different watering/soil/virus in the soil etc) is what is killing the plants. My wife sticks with H0 "there is not difference in the proportion of dead plants between the pots"
how would you go about this?
should I assume same probability per pot (and count the total dead/total as P)? and use chi-squared to show that the number of dead in each pot does not fit this distribution? I have only a few (1-4) plants per pot so I guess ANOVA is out of the question...your help is appreciated.
Answer: Since the expected cell count is small, instead of $\chi^2$ you may do a Fisher exact test.
Comment: While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference.  Link-only answers can become invalid if the linked page changes. - [From Review](/review/low-quality-posts/166016)
Comment: @Antoine well... it's not quite link-only, and Fisher's exact test will remain googlable even if the linked page changes. I believe short answers are in the spirit of the model for all these sites, StackOverflow.
Answer: 20 plants in 8 pots are few plants and a lot of pots. This is not likely to bring a $p < .05$.  First see, if you can group some pots together (maybe some where in the shadow, others in bright light? Some planted with compost, some not)? Or maybe you can restrict your analysis to a few pots with many plants in them? Of course, you would have to do that before looking at the observations.
If that does not work, change to Baysian for this time. In Frequentist statistics, when $p > \alpha$, nothing is gained whilst in Baysian, you at least gain some information about the true rate of dead plants in small pots.
Given, that there is a handy conjugate prior for the Binomial distribution, this comes easy with no need to learn any new software: $Beta(1, 1)$ is a flat prior. If you find 3 living plants and 1 dead plant in a pot, the posterior probability distribution of the survival chance of each plant is $Beta(1+3, 1+1) = Beta(4,2)$. All these beta-Distributions will give you and your wive a good basis to argue upon data, instead of a $p$-value that is basically useless, if not smaller than $\alpha$.
Here is an easy example that may take you even a bit further: https://lingpipe-blog.com/2009/10/13/bayesian-counterpart-to-fisher-exact-test-on-contingency-tables/

real life distribution question


Cannot accept invitation to Stack Overflow Careers 2.0

Question: I clicked the invitation link in the email I received.  When I log in, it seemingly accepts the login credentials but brings me back to the login screen.  My user id and password are correctly entered but have not been able to accept the invitation.  The invitation, by the way, was sent to my work email address, which is the one I'm trying to log into the site with.
Comment: Try again?  We had a cookie issue that should be fixed now.
Comment: @David well, [another one](http://meta.stackexchange.com/questions/154768/unable-to-log-to-careers-2-0-stuck-at-login) had same thing happening.
Comment: @ShaWizDowArd yes, but in my case it could be related to some issue with the original mail gone missing and the invitation timeout. That said, the behaviour described here is the same - accepted credentials but sent back at the login screen. Also notice that if you don't clear the browser cookies, any attempt to use the same login provider WON'T display the login prompt again.
Answer: Sorry about that user and thanks for the report. I believe you've been a victim of a couple of our recent login and [invitation acceptance] bugs (14 - 7 = 3: Arithmetic overflow in Careers invitation?) which should both be fixed now. Take another crack at it and let us know if you're still having problems logging in or accepting your invitation.


What should I do to secure my Steam account after I redeemed a Steam wallet code sent by another user? As that user can now possibly access my account

Question: I redeemed a Steam wallet code that was sent to me by another Steam user. Before I did this, I asked a different question in this link in Arqade - Stack Exchange. I asked if my computer/account could get hacked if I redeem a Steam wallet code sent to me by another user. The answer to that question by Joseph Richardson shows that "One of the methods of account recovery is providing to the Steam support team a game key code or wallet funds code that has previously been redeemed on the account (as per here)" so "If you redeem the code then the scammer can provide that code to Steam support, as well as proof of purchase, and gain access to your account." Well I have already redeemed the Steam wallet code so my account can be accessed; What should I do now to secure my account?
Answer: You should contact support and let them know.
This kind of trick will usually take time, since that historical record will be associated with you permanently. The hacker can wait until you have not used your account for a while, then claim it and re-sell it before you know it got compromised.
Let support know that you redeemed a code from an unknown 3rd party, and, if possible, reverse that redemption (you'll lose the funds, but better than the whole account).
Next time, do not accept free stuff from random people. There are no free lunches.
If you want to scam the scammer, make a new account, claim the code, and gift yourself a purchase. Never associate unknown redemptions on your main account.
Answer: Since Steam Wallet is within steam, I would take the guess that the steam wallet ket and CD key are 2 things that are different.
In the system, its gonna show that yes the thing was bought with account X, but then the code was used by account Y.
If you had bought a product key from another source I'd say your account might be at risk looking at the angle your explaining, but since the transaction was made using a Steam service, that transaction has a mark in their system and I would guess that trying to use that code to unlock an account would be stopped.


Using Data Import Wizard to Update Existing Accounts without any Contacts

Question: I'm trying to update existing account records (that are not associated with contacts), and in the Update Existing Records section, it's requiring that I select something for "Match Contact By" - I don't have the option to leave it as "--None--". Even if I select something (I've tried Salesforce.com ID and name) leave that field unmapped, I repeatedly get a report back that says all rows of my csv were ignored. I can only assume that they're being ignored because of the contact issue. I've updated account information via DIW before, so I'm not sure what's going on this time. Thanks for the help!
Comment: Hi Jill

You say you're trying to update existing Accounts, what option are you selecting for matching the accounts? Salesforce Id or Name & Site?
Comment: Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.
Comment: Apologies that my question was unclear. I was running into an issue where my Account updates kept being ignored. I thought it was because the DIW was requiring me to choose a field for Contacts when I don't have any contact fields in my CSV file (yellow). But it turns out it was because I didn't check this box (pink) to allow it to update existing Accounts.
Answer: SF Support helped me figure out that it was not about the Contacts field (yellow), it's about checking the box re updating existing accounts (pink).


Why is it inadvisable to get statistical summary information for regression coefficients from glmnet model?

Question: I have a regression model with binary outcome. I fitted the model with glmnet and got the selected variables and their coefficients.
Since glmnet doesn't calculate variable importance, I would like to feed the exact output (selected variables and their coefficients) to glm to get the information (Standard errors, etc).
I searched r documents, it seems I can use "method" option in glm to specify user defined function.
But I failed to do so, could someone help me with this?
Comment: see `?glm`. I really don't think `offset` is going to work for you, though.  If you give a **reproducible** example maybe someone else will chime in.
Comment: reproducible example please?  http://tinyurl.com/reproducible-000
Comment: I don't have an example right now, but, to simplify the question a little bit. Suppose I have a formula output from glmnet as y=2.3*x1+3.1*x2+0.9*x3. How do I specify this formular in glm so that it is manipulated?
Comment: that's not reproducible, but it gives me a slightly better idea.  I think you may not be able to do what you want: that is, you could feed a fully specified model to glm by specifying it as an offset term, but I'm not sure it could compute variable importance from that starting point. Have you thought about using the `caret` package, which does a form of shrinkage by averaging across models *and* provides info on variable importance?
Comment: I will check out "caret", and also could you help me with some source on how to use the offset term in glm?
Answer:
"It is a very natural question to ask for standard errors of regression
  coefficients or other estimated quantities. In principle such standard
  errors can easily be calculated, e.g. using the bootstrap.
Still, this package deliberately does not provide them. The reason for
  this is that standard errors are not very meaningful for strongly
  biased estimates such as arise from penalized estimation methods.
  Penalized estimation is a procedure that reduces the variance of
  estimators by introducing substantial bias. The bias of each estimator
  is therefore a major component of its mean squared error, whereas its
  variance may contribute only a small part.
Unfortunately, in most applications of penalized regression it is
  impossible to obtain a sufficiently precise estimate of the bias. Any
  bootstrap-based calculations can only give an assessment of the
  variance of the estimates. Reliable estimates of the bias are only
  available if reliable unbiased estimates are available, which is
  typically not the case in situations in which penalized estimates are
  used.
Reporting a standard error of a penalized estimate therefore tells
  only part of the story. It can give a mistaken impression of great
  precision, completely ignoring the inaccuracy caused by the bias. It
  is certainly a mistake to make confidence statements that are only
  based on an assessment of the variance of the estimates, such as
  bootstrap-based confidence intervals do."

Jelle Goeman, Ph.D. Leiden University, Author of the Penalized package in R.
Comment: Very well explained of why S.E. is not provided!
Answer: There is CRAN packages hdi and selectiveInference which provide inference for high-dimensional models, you might want to take a look at those...
I've also seen people just run a glm using the predictors selected by glmnet, but this doesn't take into account the uncertainty produced by the selection process of the best model itself...


API key for themoviedb.org

Question: I need to use themoviedb.org for one of the apps I am working on. For using the API, I need an API key. How do I get an API key on themoviedb.org?
Answer: I found this in the forum:
You can request an API key by clicking on the "API" link from within your account page on the left hand sidebar. See here
Comment: Don't miss FROM WITHIN YOUR ACCOUNT PAGE in this answer, otherwise nothing will show up.
Answer: In terms of making things faster for people, the URL for application is here these days (Under Account>Settings>API as previously mentioned):  https://www.themoviedb.org/settings/api
You'll want to start with a Developer key as wait time for a Developer key is zero (immediate).  A commercial key, as far as I understand it, is only appropriate once the app is developed and running.  Turnaround for a commercial API key is about 3 days-ish though obviously could vary.
Once you have a key, inside the doco pages there's a "Try It Out" tab which lets you do calls.  The normal code flow (for getting movie details) would be something like:

Get Configuration (needed for image paths, should be cached)
Search Movies (returns a list, find the numeric id for the one you want in the list returned).  Be aware there might be duplicates returned - you can use the year of release, title and language to find the one you want.
Get Movie Details with the movie numeric ID, with "append_to_response" of "credits,images,trailers" so that actors, writers, directors, and trailers (aka videos) are returned.

Check doco for how to find the actual image paths, using configuration values fetched above.  It's generally considered courteous to copy the images you want to use to your own server rather than serving them from TMDB's server.

API key for themoviedb.org


How does Quantum science and Objectivism mix?

Question: First off please bear with me that I am entering the realm of learning about both of these topics. However from what I have gathered objectivism says that reality is the only reality and that there is nothing but, thus being no point in finding something else (most religions in regards to their "afterlife"), you know, A is A. So my understanding of this is that unless something can be proven then it does not exist. As stated on the Ayn Rand Lexicon, "Reality exists as an objective absolute—facts are facts, independent of man's feelings, wishes, hopes or fears." This would be saying that something such as the Quantum Immortality theory (basically says that if a person dies in a "schrodinger's box" then they will simply wake up in a tangent created by a superposition dividing) which can not be proven, at least to my knowledge, would not be considered reality and thus should not be sought after to prove and explain. SOMEWHAT SPOILERS AHEAD TO ATLAS SHRUGGED I'm at the part now where Dagny is talking to Galt and all of her old friends and his new friends on why they left it all behind. So if stuff like this is further explained and answered later in this book or in The Fountainhead please answer starting off saying that, then continue to answer if it dives deeper than what the book explains.
Comment: Schrodinger's Cat is a *criticism* of that particular interpretation. It is meant to be a *reductio*. Quantum immortality is a fun theory, but it shouldn't be taken too seriously.
Comment: @era and neither should Ayn Rand.....
Comment: This answer may be relevant https://philosophy.stackexchange.com/a/34022/5759
Answer: From your post

"Reality exists as an objective absolute—facts are facts, independent of man's feelings, wishes, hopes or fears."

And the wikipedia article on objectivism:

Objectivism's central tenets are that reality exists independently of consciousness, that human beings have direct contact with reality through sense perception,[...]

So Realism is a central component of Objectivism.
There are more than one interpretation of Quantum Mechanics (henceforth QM), so answering the question how do objectivism and QM mix is contingent on which interpretation you subscribe to. At least two interpretations (Copenhagen, Wigner) assign an active role to the observer in the collapse of the wave-function, meaning that they don't go well with Objectivism's hard realist stance.
Moreover, one of QM's central results, Heisenberg's uncertainty principle, dictates a Kantian ontology, where the human subject can never access the things in themselves. Again this flies directly in the face of objectivism's absolute realism, and in particular is in direct conflict with "[..]human beings have direct contact with reality through sense perception,[..]".
In so far as objectivism is a philosophical theory of anything at all, it is mainly a values and ethics theory that Ayn Rand used to build her political worldview on. The ontological and epistemic positions about realism and materialism that are associated with objectivism are merely cosmetic presuppositions designed to inflate it into a complete system, and to try to elevate it above being just a bunch of folk maxims.
Further relevant research on Objectivism, QM and relativity can be found in Sokal's groundbreaking work on Quantum Hermeneutics.
Comment: @JoWehler : Take a wild guess.
Comment: Is this entire answer meant to be ironic? I don't think that's appropriate on SE, even in response to a ridiculous question.
Comment: Something can be ironic, informative, factually correct and relevant all at the same time.
Comment: Sokal's "groundbreaking" work is a hoax, see https://en.wikipedia.org/wiki/Alan_Sokal. Do you know this?
Comment: Era does have point here... @AlexanderSKing you should delete your answer...
Comment: While I'm not an Objectivist, I think this answer fundamentally misunderstands Objectivism's metaphysics and epistemology.


There is a bug in ubuntu (cannot find a medium containing a live file system)

Question: I cannot install ubuntu, and there is no way for me to submit a bug report, because I don't have ubuntu, because I can't install ubuntu.
I've followed all the instructions several times, and it just doesn't work on my system.
I know people are going to tell me to try a bunch of different stuff, but it just doesn't work. I've tried everything.
There is something wrong with ubuntu.
It does the same thing with Mint.
I guess there's not real way for me to report it though, so I don't know what to do.
It's weird though, because it works on a partition.
However, when I try to install it (I create a bootable USB drive (Yes, I've tried unebootin, I've tried dd, turning it into an img and leaving it as an ISO)), I can boot, it gives me the option to try or install ubuntu. I click install, and it says it cannot find a medium containing a live file system, whatever that means.
I'm using a Mid 2010 MacBook with an i5 Processor and an after market crucial 250 GB solid state drive.
Also, wanted to point out I've tried all this stuff in every usb slot.
Comment: @LiveWireBT I tried both USB slots
Comment: Please read the other answers too.
Answer: As you said, the only thing that happens it's a messenge saying  "cannot find a medium containing a live file system"
Try search the answers at this link if you doesn't ;)
Error when installing: "unable to find a medium containing a live file system"
Sorry if I can't help more than this....
Comment: Thanks, yeah, I read that thread and tried all that stuff.
Comment: @ZaneHitchcox Oh sorry, so I can't help more :(
Comment: That's ok, I appreciate the effort!


How to delete database without using any plugin?

Question: I am using WordPress based web development. I am a beginner, somewhere on YouTube I learned that, to change domain name, install plugin "Better search and replace", and using it replaced my domain name with the desired domain name. But after that, the domain stopped responding. I replaced the whole WordPress file from the ftp server, but in the installation process, it shows the message, "Already Installed, You appear to have already installed WordPress. To reinstall please clear your old database tables first".
I have searched ways to do that, but everywhere it's saying to use plugins, which I can't do due to above mentioned issue.
Comment: Most web hosts provide access like phpMyAdmin. Check with your host and see what's available. You can either delete your database entirely or often restore a backup of your database from before you made the changes. It's always safer before doing major changes like domain replacement to back up the database manually, in case something like this happens. :)
Comment: then go back with your Better seach and replace and reverse the changes?
Comment: Actually this domain is given by the instructor to me, for practice purpose. All I have is, Filezilla Confidentials and WordPress Database Confidentials and the domain name.
Answer: If the database server is available publicly you should be able to use a MySQL client to interact with it.
Sequel Pro is a good one for mac, check this list if you need something for windows or linux.
If the database is only available locally on your web server, you might be able to upload a DB admin script like adminer via filezilla and use that to interact with the database.
If all else fails you will likely have to go back to your instructor and ask him/her to reset the DB for you.
Answer: Another option that doesn't require installing anything: clear the database with PHP. Possibly a little easier. See this answer, just replace host, username, password, and database_name with your own from wp-config.php. Save the file, upload it to your root folder, and access it in a web browser to run it.


rails has_one scaffold

Question: I have two models linked together with a belongs_to and a has_one association, but I can add more than one record to the database since I have generated that model through scaffold generation. My code looks like the following:
<code>class User < ActiveRecord::Base
has_one :setting, dependent: :destroy

class Setting < ActiveRecord::Base
belongs_to :user
</code>
I can create multiple settings for each individual user. I was under the impression that by adding this association to the model, that rails would disallow the ability to create more than one record. Since I have run scaffold generation I have a standard restful controller, would there be something I need to change or update in my model other than the code I have specified above?
Answer: Each user has one setting. But there can be multiple users and multiple corresponding settings. You might try looking at singular resources.

rails has_one scaffold


50 amp RV outlet installation need wire size

Question: I am installing a 50 amp 120/240 volt RV outlet, the distance from my main panel to the RV outlet is 200' what size wire will I need to run? What size breaker should I use in my main panel? What size duct should I run the wire through?
Comment: If you're installing a 50a outlet & cable to match, you'd _better_ install a breaker no larger than 50a, otherwise you risk things catching fire. Also, "duct" is called conduit. Make sure you get the stuff from the electrical aisle, not the plumbing aisle. It's a touch more expensive, they're both made of PVC & both called "Schedule 40", but the plumbing stuff isn't NEC approved for electrical use.
Comment: Schedule 80 from a real electrcial supply can be well worth it if using PVC. It's actually required anywhere the conduit is considered to be "exposed to damage." Then again, more expensive metallic conduit can save a lot on the cost of the trench, and replace the need for a ground wire.That can make the whole job less expensive, depending on circumstances.
Comment: Conduit is also called duct - that's why the gray putty to prevent air and bug traffic  is "duct seal"
Comment: What is the *purpose* of this RV outlet? Is it to actually plug in an RV? Or is it for electrical vehicle charging? In either case, a small subpanel (they make them specifically for RV hookups with a 50A 240V, 30A 120V and 20A 120V) may make sense. But if it is for EV charging and *not* for RV use then a hardwired EVSE may make more sense (though still possibly with a subpanel so you can have a 120V convenience receptacle). Also **GFCI is a Must**.
Answer: 50A breaker
4 AWG aluminum conductors (voltage drop might be an issue on 6 AWG - it's marginal, but not outright unthinkable. 4 is also the size at or above which you can buy all black and just tape the ends to indicate function - 6, you have to buy proper colors for. So you can get bulk deals on a roll of 4 that you won't get on 6.)
1 inch (or larger) conduit (duct)
Depending on local pricing, 2-2-2-4 aluminum mobile home feeder might even cost less, though it's overkill for a 50A feeder and requires 1-1/4" conduit, (unless you opt to direct-bury it - which needs a deep trench and is also not something I would recommend, in general, due to maintenance issues - digging up a damaged line is expensive) which might make it cost more.
Comment: If using 2-2-2-4 mhf and a subpanel at receptacle location then in the US you could feed it with up to a 90A breaker. 90A load would result in Voltage drop near 5% on feeder and would exceed NEC feeder recommendation of 3%. The 3% recommendation is pretty conservative considering NEMA equipment standards call out acceptable operation at 10% loss.
Answer: 40A or 50A breaker is mandatory per NEC 210.21.  If you are powering an RV, it must be a 50A breaker.
If this is for an electric vehicle charger, talk to us - you're following the lemmings and doing it the hard way! It's easier and cheaper than you know.
Most NEMA 14-50 RV outlets are rated for aluminum wire and 75 degrees C thermal. I advise people take full advantage of that.  But look closely at the wire size limit of the socket - some limit you to 4 AWG wire.
As an aside - this has nothing to do with aluminum wire - it is vitally important to torque the screws to specification.  If you don't, the terminals can burn up whether they are aluminum or copper - not aluminum's fault obviously. (this was NOT understood in the 1980s when aluminum got blamed for problems that were actually misuse.  Heavy feeder has always been reliable.)
Below about 170' I don't even bother crunching the numbers.  However at your distance I would consider one size bump, to 6 AWG copper or 4 AWG aluminum.   If you're using UF-B cable this is the minimum size anyway due to UF-B's low temperature rating.  NM cable cannot be used underground or outdoors, not even in conduit. Outdoor conduit is presumed to be full of water all the time; the protection is in the wire.
2 AWG aluminum may be at a pricing advantage, since biblical quantities of it are used in wiring 100A distribution around mobile home parks.  However make sure it fits on your socket.
Aluminum is a particularly good choice if you are going to an "RV Subpanel" which typically provides you a 50A NEMA 14-50 and a standard 120V/20A socket, and often a 30A NEMA TT30 for smaller RVs.  That is because subpanels have lugs which are made of aluminum. Aluminum lugs play well with both aluminum and copper due to the differences in thermal expansion working favorably. Torque still matters, as always.


how to automate DB restore to another server?

Question: The plan is to have 1 backup set that will contain full and transactional log backup. (Server1)
There is already a scheduled job that will append any transactional log to the file after 30 minutes. (Server1)
There is a shared network drive between Server1 and Server2. But the problem is automating it via T-SQL. Here is the script:
RESTORE LOG [db_test_rep] FROM  DISK = N'Z:\db_rep.bak' WITH  FILE = 19,  NORECOVERY,  NOUNLOAD,  STATS = 5

The issue with this is that everytime the scheduled job executes, it will update the backup file numbering + 1. So in this case on the next transaction log backup, when I script into action the restoration using SSMS, it will generate FILE = 20
Can you guys give me a simple workaround for this?
Answer: The best suitable solution in your scenario is LOG SHIPPING which is available in Web, Standard and Enterprise editions. I assume that your SQL server is not express as you mentioned There is already a scheduled job
If you want work with T-SQL, i don't think appending backup files is good idea, so you may want to change schedule job to create separate file for each backup. Then you can start with following query to get dynamic restore command based on backup history:
SELECT      [b].[database_name] ,
            [b].[backup_start_date] ,
            [b].[backup_finish_date] ,
            f.physical_device_name,
            ((b.compressed_backup_size / 1024) / 1024) as CompressedSize_MB,
            CASE    WHEN Type = 'L'
                        Then 'RESTORE LOG '+ QUOTENAME([database_name]) +' FROM DISK=N''' + f.physical_device_name + ''' WITH NORECOVERY, REPLACE, STATS;  '
                    WHEN Type = 'D'
                        Then 'RESTORE DATABASE '+ QUOTENAME([database_name]) +' FROM DISK=N''' + f.physical_device_name + ''' WITH NORECOVERY, REPLACE, STATS;  '
            END as Script,
            b.is_single_user,
            b.user_name
FROM    [msdb].[dbo].[backupset] AS [b]
            LEFT JOIN  msdb.dbo.backupmediafamily f ON b.media_set_id = f.media_set_id
where   b.type in ('D', 'L')
        and b.database_name = 'TestDAG' --- add your database name here
order by b.backup_finish_date desc

Answer:
The plan is to have 1 backup set

If you're looking to use the server just as a backup for high availabilty, you should consider looking at Availability groups
It's fairly easy to setup, and has useful features like automated failovers incase something goes wrong on your primary.
(very very) Short :
 - Create a cluster between your 2 windows servers
 - Create an Availability group between them
 - Add databases to your group
This link gives a pretty good overview of how to set it up.
If you're using a standard licence, you'll be stuck using Basic Availability Groups, which has the limitation of only being able to put one database in each AG.
More info in this link.
Comment: Availability group is not in our option as we are encountering some issues on our Cloud Service provider on this part "Create a cluster between your 2 windows servers"
Comment: I see, that's unfortunate. Shekars answer is probably what you need then. (Log shipping)
Answer: Maybe something like this:
Get the latest FILE number by using RESTORE FILELISTONLY:
USE master
GO

IF OBJECT_ID('tempdb..#BackupMetadata') IS NOT NULL DROP TABLE #BackupMetadata

CREATE TABLE #BackupMetadata
(LogicalName NVARCHAR(500)
,PhysicalName NVARCHAR(500)
,Type NVARCHAR(500)
,FileGroupName NVARCHAR(500)
,Size NVARCHAR(500)
,MaxSize NVARCHAR(500)
,FileId NVARCHAR(500)
,CreateLSN NVARCHAR(500)
,DropLSN NVARCHAR(500)
,UniqueId NVARCHAR(500)
,ReadOnlyLSN NVARCHAR(500)
,ReadWriteLSN NVARCHAR(500)
,BackupSizeInBytes NVARCHAR(500)
,SourceBlockSize NVARCHAR(500)
,FileGroupID NVARCHAR(500)
,LogGroupGUID NVARCHAR(500)
,DifferentialBaseLSN NVARCHAR(500)
,DifferentialBaseGUID NVARCHAR(500)
,IsReadOnly NVARCHAR(500)
,IsPresent NVARCHAR(500)
,TDEThumbprint NVARCHAR(500)
)
INSERT INTO #BackupMetadata
EXEC('RESTORE FILELISTONLY FROM DISK = N''Z:\db_rep.bak''')

DECLARE @ID INT
SELECT @ID =  Max(FileId) FROM #BackupMetadata  WHERE Type = 'L'

Then do your restore using dynamic SQL:
DECLARE @CMD NVARCHAR(500)
SET @CMD = 'RESTORE LOG [db_test_rep] FROM  DISK = N''Z:\db_rep.bak'' WITH  FILE = ' + @ID + ',  NORECOVERY,  NOUNLOAD,  STATS = 5'
EXEC (@CMD)

Comment: This is what I need. Thank you. Though I used the RESTORE HEADERONLY function. I just followed your procedure.


Is the decoder in a transformer Seq2Seq model non parallelizable?

Question: From my understanding, seq2seq models work by first computing a representation of the input sequence, and feeding this to the decoder. The decoder then predicts each token in the output sequence in an autoregressive manner. In this sense, it's limited to processing one time step at a time, as the next token in the sequence depends on the previous (non parallelizable). This is different from the encoder, as it's able to process many time steps in parallel. Is my understanding correct?
Comment: Yes, the decoder in a transformer Seq2Seq model is non-parallelizable. Yes, that is correct.
Answer: During training, the decoder can be trained in parallel (and that's one of its advantage over LSTM) :
You input <s> I love you, and the decoder learns to produce I love you </s>. For each token, the model learns to predict the next token (for example given <s> the model learns to predict I). This is possible thanks to attention.

But at inference time, you are right : the model has to predict the first token, then put this token in the decoder input and predict the second, etc...
So yes, at inference time a decoder is much slower (because we go through the whole decoder several times : one time for each token) than an encoder (which do a single forward pass).


Power of KStest

Question: I have a basic question , I wanna to calculate the power of one sample kstest. Please help me out . I have the sample of 76 data. Calculated the h,p,k,cv for the given sample but not able to calculate the power .
thanks in advance.
Comment: The issue is the same as for any test with broad alternatives, including most goodness of fit tests -- see the explanation [here](http://stats.stackexchange.com/questions/80856/how-to-calculate-power-of-different-normality-tests-such-as-shapiro-wilk-ryan-t/80960#80960). In particular, consider the third sentence "*To compute the power you need to specify a particular alternative*"; that post then goes on to illustrate an approach to computing power for specific alternatives and sequences of alternatives.
Answer: The problem is that the distribution of the Kolmogorov-Smirnov statistic will vary greatly depending on the underlying distribution of the data  when the null hypothesis is false.  So you would need to specify exactly how the null is not true in order to even get started answering this question.  My guess is that you can't get a very satisfactory answer to this in general.

Power of KStest


Include all objects in pointers in user

Question: I am looking for an answer to this year old question in the old Parse Forums
https://parse.com/questions/include-key-inside-pfuser
Basically, I am wondering how to always have all object references in the current User loaded instead of having to first retrieve the object reference from the current User and then calling fetch on that object to actually retrieve its data.
In the Forum response, they say they might look into it but then it was closed. Is there any way to do this?
Answer: Sadly this is a known issue by Pars and it seams that they won't fix it. The worst part is that some times you will get the whole object without the need of the .fetch method.
This means that you can have your app working no problem, and one day suddenly it will stop working with no errors from Parse side.
You can check my commit on this mater here: GitHub.com
It took me two days to figure this out, since even their documentation doesn't mention the need to use the .fetch method.

Include all objects in pointers in user


Disc brake conversion for Trek 7.5 FX from 2012

Question: Looking for a few tips to help me with a project. I got a Trek 7.5 FX 2012 as a hand-me-down and love the bike, but I am having trouble getting used to the brakes. I would like to do a conversion to disc brakes but I have never done a project like this before. I am an apartment dweller and so this is the only bike I have for commuting so I also can not afford to have it out of commission for an extended period of time while I tinker with it. I am thinking I need a new fork, new front and back wheels, rotors, mechanical calipers, and a mounting system for the rear caliper on the frame. What parts specifically should I get and what advice should I listen to to avoid common pitfalls?
Comment: Does this answer your question? [Converting an existing cyclocross bike to disc brakes](https://bicycles.stackexchange.com/questions/683/converting-an-existing-cyclocross-bike-to-disc-brakes) (lots of others already asked and answered on this site)
Answer: New fork, wheels and brakes is a significant art of the bike. You'd be better off selling the bike a buying a new one with disc brakes. Especially as the market for cheap MTBs or hybrids is exploding in the Washington DC region during the Corona pandemic. (Yes, I looked where you located, and that's where I live too)
Going the new bike route avoids screwing around with a rear disc brake converter and ensures you have a bike available at all times.
Alternatively, V-brakes really should be perfectly adequate and have sufficient stopping power and modulation for a road oriented hybrid. Have you considered having the brakes tuned, or perhaps upgrading the pads? Properly adjusted brakes and high end pads can make a great difference to braking performance.


Creating title blocks in QGIS

Question: I am trying to create a table in composer to be positioned at the base of the map and is essentially a title block to provide information in text, image and table form. The only success I have had is creating many small text boxes and strategically placing them to appear as a table. However this is extremely tedious and if I need to change the spacing of 1, I need to then change the spacing's of all other text boxes- surely there is an easier solution.
Comment: like this? https://gis.stackexchange.com/questions/199418/adding-excel-table-to-qgis-print-composer
Comment: If @mapperz solution isn't what you want, please update your question with an image of the "title block" you're trying to create.
Comment: Welcome to GSE ! Don't forget to specify which version of software / tool you are using, tools or code are evoluting !
Answer: I have previously (in my early days...) created simple title blocks using HTML tables, using the Add HTML tool and constructing the table from scratch using
,
,  etc., specifying most column widths and alignments in-line - a more sophisticated approach would heavily use the user stylesheet option to set certain defaults, and set up certain table style classes etc.
Then I would save the title block as a template by going to Layout > Save as Template, and using Layout Manager to create new maps from that template.
Some examples:

I think that might be the best option to create a table template, but be warned, it can be extremely time consuming, especially if you do not know much about HTML/CSS. Column widths, text padding, merged rows, font settings, etc.
Ideally, all of your text in the title block would be static or controlled by an attribute/variable as it is very inconvenient trying to replace/edit table contents in the HTML code, with the tiny text block provided - it's meant more for you to paste HTML that's ready to go.

Personally, I've since shifted to template styles that don't divide sections by lines at all, and just use text boxes with no frame for everything.
I lock the top-left coordinate of the text boxes (and sometimes the width) by going to Item Properties > Position and Size to prevent inadvertent shifting while allowing for some resizing. This still allows flexibility if needed, and is much easier and more user-friendly than modifying HTML. I also don't have to worry about shifting lines around.
If I really need a line to separate items I will just draw one using the Add Polyline tool in composer, and lock the polyline's location.

Creating title blocks in QGIS


Offline support for lightning calendar

Question: I created a network calendar and enabled offline support. However, starting thunderbird with no network-connection, the calendar doesn't show anything.
I expected that I would see my calendar entry.
Is this a bug oder do I expect the wrong thing? How can I debug this?
I'm using Thunderbird-Version: 60.2.1 (64-Bit) Lightning-Version: 6.2b6 with Linux Mint MATE 18.3
Comment: Well, in practice: when travelling by train I have often lose network, nevertheless I want to know my dates. Beside, there's the option: Offline support (especially for network calendars in lightning), thus I expected it or want to know what it means.
Comment: You can export your network calendar as an .ics file and open it locally. Why, though, would you expect a "network calendar" to be available without network connection??
Answer: With Thunderbird 60.4.0 and Lightning 6.2.4 under GNU Linux system, I find a <code>~/.thunderbird/<id>.default/calendar-data/backup/</code> directory, in which I find several ICS calendars which seems to contain the offline information for my remote calendar.
So it seems that I can consult my remote calendar offline by importing one of these ICS into a new calendar.
It feels however silly to have to create a new calendar and manually do such import. I really wish the "offline support" of Lightning for remote calendars would provide a user-friendly (if not automatic) way to switch between remote server and offline local cached data.

Offline support for lightning calendar