Running Queueable - Apex DML Exception: LOCK ERROR Unable to get exclusive lock

Question: I have a batch Apex that processes timecards that meet a certain criteria. if the project(parent project) in the timecard has active child projects and the timecard is approved, the time in the timecard is distributed to all the child projects. Some parent projects have 100 to 800 active child projects. The batch apex processes one timecard at a time. But due to the large no .of child projects the batch hits a cpu limit when processing one timecard too. In order to get around the cpu limit error, the timecards having large no .of child projects are processed by a Queueable which chains itself in batches of 30 child projects.
The batch processes timecards that have 30 or less not .of child projects. Any thing above this the queueable is initiated from the batch
The queueable run in parallel to the batch and everything works well if all the parent projects in all the timecards are unique.
Example: If timecard1 has parentproject1 having 100 child projects and timecard2 also has parentProject1. These two timecards will be processed by the queueable and they trip on each when time is distributed to the active child projects and cause the LOCK error mentioned above. I am assuming this happens because the queueables are executing in parallel. This does not happen to the timecards being processed by the batch apex.
Can the queueables initiated from the batch be forced to execute serially?
OR
Is there another way to around this error?
Answer: You should use a FOR UPDATE query to make sure you have exclusive locks on the records you need to modify. Make sure you lock parents first, and then children, as appropriate. See the Locking Statements documentation for specifics. If you're concerned you won't be able to get a lock in time (you have about 5 seconds), you can query the records in a loop until you get some threshold or successfully lock the records. Time spent acquiring the locks do not count against your CPU time, although there is an ultimate 10 minute transaction limit you should also be aware of.
Comment: Thank You. couple of questions.
1. Do I need to specifically lock the parents first and then the children?From the documentation it seemed that if the children are locked sales force automatically locks the parent.
2.Question regarding the statement from your answer
If you're concerned you won't be able to get a lock in time (you have about 5 seconds), you can query the records in a loop until you get some threshold or successfully lock the records.
Comment: Continuation..
Does this mean that, first query the records using the 'FOR UPDATE' in a loop .If this results in a 'Query Exception' then lock was not successfully acquired.  Set a flag 'lockAcquired=ffalse'. check against this flag in the loop and query until lock is successfully obtained. Is my understanding correct?
When you say (you have about 5 seconds), is this time just for getting the lock on the records?
Comment: @Neema See [this question](https://salesforce.stackexchange.com/q/22636) for more information on the lock timeout, but yes, that generally means you can put your query in a try-catch inside a loop with some limit of retries; if you don't get a lock in say, 30 seconds, just requeue your job to run later. Salesforce recommends locking parents before children explicitly, though my understanding is also that parents will be automatically locked at some point. I think it's simply a way to help avoid deadlocks.


How to pay zakat in non-fasting days as a woman?

Question: As a woman, I get my period for one week. In that week during ramadan, I don't fast. In these non-fasting days, I must give zakat to the poor. What kind of zakat do I give? How much zakat should I give for each non-fasting day? I am a woman that does not have a job yet but has some savings.
Comment: Zakat does not have anything to do with fasting, unless you are talking about  Sadaqat-ul-Fitr. You do not need to pay any charity for fasts that you miss because of periods, you just have to make up for missed days later.
Comment: Why you need to give zakat while you don't fast? Giving zakat to non-Muslims is hardly allowed.
Comment: There's some rule in Islam that says that when a person doesn't fast because they are sick or breaks his fast for any reason has to feed 60 people or pay an amount. Not entirely sure about the certainty of this, perhaps you can help me understand it.
Comment: There should be some posts covering the topic of kaffarah. Therefore I think it is better to clear your confusion.
Answer: You are confusing Zakat with Kaffara and Fidyah.  Kaffara is due on a person who breaks their fast without a valid excuse, it is not due on those who have an excuse to not fast, such as a sick person or a traveler, they only have to do قضاء

فمن شهد منكم الشهر فليصمه ومن كان مريضا أو على سفر فعدة من أيام أخر
So whoever sights [the new moon of] the month, let him fast it; and whoever is ill or on a journey - then an equal number of other days.
— Quran 2:185

Similarly, a menstruating woman is not required to pay it. Rather she needs to fast additional days to make up for those that she missed.

كان يصيبنا ذلك فنؤمر بقضاء الصوم ولا نؤمر بقضاء الصلاة
That used to happen to us and we were commanded to make up the fasts but we were not commanded to make up the prayers
— Sahih Muslim and Nasai


What is happening to the none approved transactions?

Question: Every 10 minutes only 1MB of transactions are been approved, so what happened to the rest of them? Let's say my transaction was not entered into the block, can I be sure that no one is going insert it to the next block?
Comment: You may also have a look to this epic thread on delays with tx: https://bitcoin.stackexchange.com/questions/9046/why-is-my-transaction-not-getting-confirmed-and-what-can-i-do-about-it
Answer: Each node on the peer-to-peer network may store the transaction in its mempool, during which time they will continue to relay it to other nodes.  After some amount of time, the node will drop it from the mempool.  The default time in Bitcoin Core is two weeks but individual nodes are free to use a different value.

Let's say my transaction was not entered into the block, can I be sure that no one is going insert it to the next block?

No, you can't be sure of that.  Certainly while the transaction is in most node's mempools, it will continue to be considered for inclusion in new blocks.  That's desirable for most people, who would prefer that the transaction get confirmed soon, even if it isn't confirmed immediately.
In principle it's possible that some node sits on your transaction, and that it makes its way into a block a long time later - years, even.  The only way to be sure your transaction is never going to confirm is to double-spend it: make a new transaction which spends at least one of the same inputs.  If the new transaction is confirmed (with a sufficient number of confirmations, say 6) then the old one can't be, because the block chain isn't allowed to contain conflicting transactions.
Comment: "make a new transaction which spends at least one of the same inputs."
This is not an easy thing to do with a normal wallet because usually you can't control this info.
Comment: @Mr.Turing: In general, yes.  Though Bitcoin Core has a "coin control" feature where you can choose the inputs for your transaction.  Of course, you first have to convince it that those inputs are actually available, and make it forget that it spent them once before.


Do wages differ in two perfectly competitive labour markets?

Question: I understand that within a single labour market, the wages would be the same between two workers as firms and workers are both wage takers, but what about when there is more than one perfectly competitive labour market: if the labour market for jobs A and B are both perfectly competitive, would the workers in A earn the same as the workers in B, provided that the two jobs are not the same?
Answer: This will typically depend on if people can switch between the two markets. If switching is possible then the marginal worker has to be indifferent between working in market A and market B and this equalizes the wages in the two markets. This also assumes you mean wage rates and not wage bills. Wage bills also depend on hours worked per worker, and that decision need not be equal across industries because of sorting and other reasons.
If people can't switch between markets it can, but doesn't have, to be that wages do not equalize. Consider two workers on two different islands with residents that don't trade or even meet. Even if labor markets on both islands were perfectly competitive, it needn't be that their wage rates were equalized.
Answer: Your question can be rephrased as follows:

Are workers with different abilities paid differently in a competitive labour market? In other words, is each worker paid their marginal contribution to total production?

This is perfectly possible.
To see this, assume a continuum of workers, with index $i$, where $\eta_{i}$ denotes the ability of worker $i$. The distribution of ability in this population is given by $G(\eta)$. Since the market is competitive, we can forget about firms, and solve the problem from the social planner perspective (because of the 1st welfare theorem).
For simplicity, assume that labour is the only factor of production. All workers supply the same number of hours. Furthermore, assume that workers' production is given by the sum of their individual contributions, times a technology level parameters, $A$. So, if there are only two workers, with ability $\eta_{a}$ and $\eta_{b}$ respectively, total output is given by $A(\eta_{a}+\eta_{b})$. In the general case, total output is given by:
$$Y = A \int_{i \in L}^{}\eta_i\,\mathrm{d}i$$
(Notice that, for simplicity, this production function assumes constant returns to scale)
Now, let's postulate the hypothesis that workers are paid proportionally to their marginal product. It is clear that this is equivalent to $\eta_{i}$, as not having this worker reduces output by that amount (notice the importance of the assumption of output as the sum of workers' ability). If the wage per unit of ability is $\omega$, then the real wage of worker $i$ is
$$w(i) = \omega\eta_{i}$$
Now, under perfect competition (and without capital), all product is paid to workers. This is,
$$Y = \int_{i \in L}^{}w(i)\,\mathrm{d}i$$
Replacing the definition of wages and rearranging leads to:
$$Y = \omega\int_{i \in L}^{}\eta_{i}\,\mathrm{d}i$$
Given the production function assumed, this implies:
$$A=\omega$$
Given our assumption of constant returns to scale, this is of course reasonable. The wage per unit of ability must be equal to the technology level (as it is in the case of $Y=AL$). This completes the proof.
Notice the above result is true, irrespective of which is the distribution of ability. Notice further that equal ability ($\eta_{i}=\eta$) means $w(i)=w$, which brings us back to the Econ 101 labour market.


A2C Critic Loss Interpretation

Question: I'm working on an Advantage A2C implementation, and I just finished creating the value network $\hat{V_{\phi}}$. I train this network with the standard MSE loss of discounted rewards-to-go:$$\|\hat{V_{\phi}}(s_{t'}) - \sum_{t=t'}^{T}\gamma^{t-t'} r(s_t, a_t)\|^2$$
I would like to be able to evaluate and assess the performance and ability of the value network as I train, especially to see how that relates and interacts with the changes and improvements in the policy, however I'm not sure how to do this.
My first instinct was to track the loss after each batch of experiences, but this doesn't work. As the policy improves, episodes last longer, and the value loss increases. I understand why this happens, as it is harder to predict the rewards-to-go when the length of the future is more undetermined.
To fix this, I tried dividing the loss that I'm computing by the total number of steps in the batch of episodes. However, the loss is still increasing as the policy improves (as the episodes get longer). Why is this still happening? Then, is there anything I can do to get a better assessment of the quality of the value network?
Answer: Unfortunately no, the way to go is track the total reward and see if it's increasing and converging eventually. Value loss isn't a useful metric as the loss can be 0 when the value network always predicts 0 and the agent doesn't collect any reward, meaning very poor behavior.

A2C Critic Loss Interpretation


Progressive vs. Optimized jpegs

Question: I know that progressive jpegs download in multiple passes, and optimized are smaller (and thus faster to finish downloading), but does anyone have any hard data or best practices on which type users actually prefer?
Comment: Photoshop has an "optimized" option which compresses jpegs even smaller than baseline or progressive.
Comment: Progressive JPGs were kind of a thing during the dial-up era. They're likely still a good idea, but just haven't been used that much since then. BTW, I believe these concepts aren't mutually exclusive. A JPG can be both optimized and progressive. As for the user, I think they simply prefer whatever loads faster.
Comment: I consider myself a user, and will, from today, be using non-progressive jpegs, as my image-editor of choice (MS Paint - love it) cannot open progressives.
Comment: Are you referring to reduced file size as optimized here? if yes, then read the document in the link I've posted in my answer. That's the best as far as  best practises go.
Answer: Let's start with the difference between progressive and non-progressive JPEG files.
Non-progressive JPG files ar not by definition smallers than progressive JPEG files. A rule of thumb found by Stoyan Stefanov is that JPEG files smaller than 10K are best compressed non-progressive JPEG, but that bigger JPEG files become smaller when stored as progressive JPEG.source see the chapter progressive JPEG.
So if you just want the smallest download non-progressive is not always the best choice.
This 2012 article goes into more detail Progressive jpegs a new best practice
Tip if you want even smaller JPEG files use mozjpeg
But now to anwser your question.
You wanted to know if anyone has actually done any research on user preferences.
Well actually someone did.
You can read an article on the research by Tammy Everts here: Progressive image rendering: Good or evil? It contains a link to where you can obtain the full report.
Spoiler: users seem to prefer baseline JPEG files over progressive.
Answer: Here's an alternative perspective on it. Not an absolute rule, but a thing to keep in mind.
It depends on what the image is for. Content, or decoration?
If it's a background or other design element, use progressive, so the page looks okay-ish as soon as possible. If it's an element that moves stuff around, it needs to be there ASAP so people don't mis-press a button due to layout shifting. (been there a couple of times on mobile.)
If it's content the user is going to download, or consciously pay attention to, use regular JPGs. This communicates to the user that it's not yet finished, that they have to wait a bit. This stops them from saving an unfinished download, and they won't experience the site as bad quality but the server/connection.
Comment: I like the perspective.  On a side note: stuff shifting around can be helped by setting height or min-height in your CSS (where possible)
Answer: +1 to DA01
If OP is referring to reduced file size as "optimized" then here are some standard practices when saving as JPEG.

Don't embed color profiles. Browsers these days have better ICC
profile support.
Export image as sRGB
Set metadata to none
Set quality at 65%. More about quality settings can be found here.
Ensure the file size and dimensions are in scope of your requirement. i.e. don't export a 2000x3000px image for a mobile website.

More about Optimizing images Guide by Google.
Comment: Where does the 65% come from?
Comment: Trial and error with over 6 years spent on optimizing images for the web. Here's a pretty picture example http://laurashoe.com/2011/10/18/jpeg-quality-compression-lightroom/ added to post. ty.
Comment: I would recommend against picking a hard and fast JPEG quality setting.  65% is a great target, but the particular content may require a higher quality.  Or, you may be able to get away with less.
Comment: I think my reply needs an upgrade. Since 2017 I've been experimenting with content aware image compression ever since I caught google chrome browser using a variational autoencoder to upscale images on the client. I found a python implementation https://github.com/iamaaditya/image-compression-cnn of Semantic Perceptual Image Compression using Deep Convolution Networks https://arxiv.org/abs/1612.08712 which is worth checking out. Google released a similar encoder https://github.com/google/guetzli
Comment: Also here's a more practical explanation of perceptual image compression by Flickr https://code.flickr.net/2015/09/25/perceptual-image-compression-at-flickr/
Answer: I'm having trouble finding a definitive, recent answer but from what I can tell, Mobile Safari, to pick just one mobile browser, supports progressive JPGs, but doesn't actually load them progressively--meaning it just waits for it to download entirely, then displays it.
So it seems that the visual progressive loading feature simply isn't all that relative today, making the benefit much less appealing.
That said, making a JPG progressive may help compress it's total size, so by all means, that's still a benefit, but it's probably just not a big enough benefit where it's caught on widely.
Also, as stated in my comment, I don't think this is a 'vs.' issue. Unless I'm misunderstanding what you mean by 'optimized' a JPG can be both progressive and optimized. In fact, any image format for your web site should be optimized.
Answer: The main difference is that when the picture (jpeg file) is export as "progressive" is going to load the full size image with reduced quality, while if it's export as "optimize" is going to load section by section from top to bottom.

Progressive vs. Optimized jpegs


Anime about a group of guys looking fo a girl that can fused with their individual powers

Question: Do you know any anime that has 5-7 boys looking for a girl that can fused with them? Then they'll know it if the feel an electricity on their finger tips.
Comment: You could improve this question by going through the checklists [here](https://scifi.meta.stackexchange.com/questions/11874/how-to-ask-a-good-anime-story-id-question) and editing in any relevant info you can think to add.
Answer: Prétear matches the details that you give - a high school girl encounters seven boys known as the "Leafe Knights" and her ability to merge with them identifies hers the "Prétear". A plot summary from the Wikipedia link:

A high school girl named Himeno Awayuki is attempting to adjust to her new life after her widowed father remarries wealthy widow Natsue. While taking a short cut to school, Himeno jumps out of a bush and lands on Hayate, the Knight of Wind. After some arguing Himeno wants to punch Hayate, but he blocks her hand causing a powerful light. Later she meets the other Leafe Knights who tell her that the red snow that has been falling on the town recently is being caused by the Princess of Disaster who is awakening, and that she is using demon larva to absorb Leafe, the essence of all life. They ask Himeno to become the Prétear and help them protect the world. Himeno is initially reluctant, believing they are trying to play a trick on her. When a larva attacks them and begins stealing leafe, Himeno agrees to help. Hayate tells her to take his hand and she merges with him to become the Wind Prétear. After adjusting to her new powers, Himeno is able to defeat the larva.
As the series progresses, Himeno finds herself slowly falling in love with Hayate, who is initially cold and refuses to acknowledge her as the Prétear. Eventually she learns the Princess of Disaster was once a girl named Takako, who was the last Prétear. She had not enjoyed fighting, but did it anyway, also falling in love with Hayate. When he could not return her feelings, her anguish caused her powers to turn to evil, changing her into the Princess of Disaster.
Mawata, one of Himeno's stepsisters, has been overwhelmed with grief since the death of her father and holds herself distant from her family. She and Himeno temporarily connect over their shared feelings, but Mawata is hurt when she sees Himeno with Hayate. Mawata is in love with Sasame, but it is revealed that he was in love with Takako. He throws away his status as a Leafe Knight and joins Takako to become her Knight of Darkness. Takako uses Mawata's love for Sasame to hurt her even more, enabling Takako to use her to fuel the Great Tree of Fenrir.
The town is overrun by the Great Tree. To protect the rest of her family, Himeno reveals her Prétear powers to them, then begs them to escape while she rescues Mawata. Instead, the family refuses to leave Mawata behind and put themselves in great physical danger to rescue her. Hayate and Sasame engage in a battle to the death, and Himeno climbs the Great Tree of Fenrir. Himeno's family starts attacking the bubble holding Mawata, calling to her desperately. Himeno continues up the tree to confront the Princess of Disaster. Mawata is freed and safe in the arms of her family. Takako doesn't want her to go and becomes desperate calling out for Sasame who appears after beating Hayate in battle. Fenrir asks Sasame to kill both Hayate and Himeno, but he is convinced by Himeno not to. Believing that not even Sasame loves her, Takako tries to kill herself, but Sasame shields her and dies. Takako comes back to her true self realizing that she loved Sasame too. Out of control, the tree captures Takako. Himeno tries to save her and she's attacked by the tree. Hayate shields her and then he dies in her arms.
To stop the tree, Himeno by herself becomes the legendary White Prétear and pours out a massive amount of Leafe. The town is restored, the Leafe Knights healed, and Sasame and Hayate are brought back to life. Hayate awakens to find the others crying over Himeno's lifeless body, lying in the grass as if she were sleeping. In agony, he holds her, then kisses her, which restores her life and enables her to awaken. At the end of the series, Himeno and Hayate are a couple, Himeno and her family are closer, Mawata is happier, and Takako is seen quietly sitting with Sasame.


Framework for a simple web app for intranet

Question: I need to make a web server (application) which will let user to upload some files, process them somehow (run a script) and return result as http document and optionally let user download a file.
This is for private intranet (no serious security needed) and low volume of requests.
The OS should be Linux.
Does some framework exist for such applications?
Comment: If you're experienced with PHP Javascript and html you can use [TinyMCE](https://www.tiny.cloud/).
Answer: Alfresco lets you do this.
It is a document management server, so you can upload files via the web interface, or via WebDAV/FTP/CMIS/etc.
A folder in Alfresco can have rules.
A rule has a condition and a procedure. Example:

Condition: Any file that arrives in this folder
Procedure:

Create a backup of the original in the "archive" folder
Convert the file to PDF and to HTML
Move it to the "output" folder
Send an email notification to the file's owner

Conditions and procedures can be as easy or as complex as you want. For most simple actions like document conversion and moving files around, clicking in the web UI is enough, but for more complex things you can also write your own actions, in JavaScript or even in Java if you need. There is a JavaScript debugging console to make this task easier.
People can download anything from Alfresco if they have the correct login/password and permissions.
Alfresco rule configuration:

Free and open source.
Comment: Thank you Nicolas this is close. Though a bit heavy, need to see what are resource requirements.  Meanwhile, I've found Jupyter and Interactive Python. This is really close to my need, but there I'm feeling too dumb and unable to connect dots... How to stuff a binary file into a Jupyter sheet? And the UI is nerdy, so I'd prefer Alfresco ...
Comment: .Is there something like Alfresco but simpler/smaller?
Answer: Vaadin
If you are familiar with Java, I recommend the Vaadin Framework for developing your user-interface and application server.

You write your business logic and UI code in pure Java. At runtime, that Java code runs in the server-side in a Java Servlet web container. Vaadin automagically renders your UI using HTML5 web standards technology (HTML, CSS, DOM, JavaScript, WebSocket, Push, and such) for remote display in the user's web browser.
Here's the amazing thing about Vaadin: You do not need to learn about all that HTML, CSS, DOM, JavaScript, WebSocket, Push, and such! All you need know is Java. Vaadin does all the heavy-lifting of dynamically generating the web-based UI seen by the user.

(source: vaadin.com)
Vaadin includes an upload widget. Your server-side Java app can then manipulate that uploaded file, output some other file, and offer that new file for download.
With Vaadin 8.1, the Vaadin team is working on advanced support for new HTML5 drag-and-drop protocols being defined by the web standards community. This should result in smoother interaction for dragging files from the user's computer's file system into the web browser and your Vaadin app. See the Drag-and-Drop chapter of Vaadin documentation.
Comment: This looks good, especially drag and drop files and responsive UI . But Java is a steep learning ramps for us. Maybe we'll be able to outsource.   Thanks.
Answer: I use CubicleSoft Admin Pack for creating admin interfaces and internal software such as Intranets all the time.  Not too long ago, I added a multiple file uploader widget to FlexForms Modules, which could be useful for your needs.
Admin Pack my go-to tool of choice for building web backends since it is written in PHP and therefore runs on a standard LAMP/WAMP stack.  PHP is an excellent server-side scripting language.  Admin Pack is just a framework (of sorts) that does require writing software, but I've found that custom-built software solutions are usually better than prepackaged software when it comes to streamlining business processes because you get only what you need.
What most people don't realize is that PHP is also a fantastic command-line scripting language.  If you have a long-running process or need to run a process as a user other than the web server user (e.g. 'root'), there are two routes that you can take to run a command-line PHP script:

A cron job that runs periodically (e.g. every minute), where the script looks at a specific directory for new files, processes them, and then stops running when it runs out of files to process.  This is the classic quick-n-dirty solution.
Trigger a script to run via Cloud Storage Server /scripts.  This is much more efficient since processing is triggered to start only when there is something to do.  However, this solution takes more effort to set up and also blurs the web vs. system security line a bit.

Your web app drops uploaded files in a folder, the processing script picks them up and processes them, and processed files are dropped into an output folder, which the web app can show to the user.  Periodic, automated cleanup of both folders should also take place.  This sort of workflow is all fairly standard fare.
Standard Apache + PHP offers certain security and process isolation metrics that you won't find in other tools that emit a dynamic web server interface.  When it comes to open ports in network infrastructure, even internally, the fewer the better.  Also, system security should be the first priority in selecting a piece of software as many successful attacks against infrastructure start by exploiting internal actors (e.g. convincing an employee they should run some piece of software not caught by malware filters).
For a quick-n-dirty solution from a pure security standpoint, I'd stick with a package managed LAMP stack and fill in the long-running process bits with command-line PHP scripting.
Comment: Thank you.               ....................................


Canon 600D image captured with date and time display?

Question: I own a Canon EOS 600D camera. I need to know if it is possible to capture a picture along with the date and time. The image displayed after capture should also show the date and time of capture. I need to know what settings to be enabled.
Answer: The camera will automatically record this information in the JPEG file, but not as a picture of numbers superimposed on the image. Some cameras have a feature to do this, but I don't think yours does. That's not necessarily bad, because doing it that way means you have part of the image covered by numbers and you can't get a clean image if you change your mind.
Instead, I suggest using the embedded, "hidden" metadata to add the timestamp using your computer after importing the photos. We have information on how to do this at How to overlay date and time onto the corner of photos?
Answer:
The image displayed after capture should also show the date and time of capture. I need to know what settings to be enabled.

Whenever you take a photo, a number of pieces of information about the photo and camera settings are recorded in what's known as EXIF data. Time and date, location, aperture and focal length, ISO, white balance, camera make and model, image resolution, and software version are just some of the values that may be found in an image's EXIF data. Most photo viewing and editing programs have a way to examine the EXIF data.
Answer: In the preview mode you should click info button twice which displays the Image Size, the iso , the date and time of the image captured. If you click info again you will see the RGB displayed along with histogram. Clicking info again will take you back to the preview.


Guitar Acoustic Best Practice for chords hand

Question: I am new to acoustic guitar . What is best practice for chords hand ? I want to improve my chords' hand speed .
Answer: Hammer-ons. Rather than putting your fingers on the appropriate strings/frets one at a time, try to get them down as a hammer-on. After all, this is how, hopefully, you will end up forming them when you are playing. All fingers need to land together and firmly.You sort of make the chord shape before you smartly land them on the strings. Of course it'll take practice time.
Second hint - there are many changes that occur frequently. Take open E and A. If you leave your index finger on 3rd string, 1st fret for both, it will act like a pivot, and the middle and ring fingers can move across one string each, leaving the pinky to join them on 2nd string, 2nd fret to make the A.Look for changes where you can leave a finger or two on the same place.
Third hint - be aware that there can, and should be two or three different fingerings for some chords, dependent on which chord precedes and follows. For instance, open D has 12 different fingerings, so find two or three that you're happy with, and change to and from D to see which work best.
Comment: +1 for noting that alternate fingerings (sometimes for the same voicing) may make certain transitions easier.  If an open E chord is to be followed by any E shaped barre chord then I will play it with my middle, ring and pinkie so I can just slide that shape up and add the index finger to form the barre chord.  But if an open E is to be followed by an open E7, then I will use my index, middle and ring finger so I can just add the pinkie to form the E7.
Comment: *open D has 12 different fingerings* Any quick sources you can share. I'm self toughed and have only been playing and learning for a year, so this would be a great addition. I know one or two alternatives for other chords, but D, I know the one standard which most use
Comment: @PieterGoosen - no, there's no need, you can work them all out. Three strings need to be pressed down. 6 shapes use separate fingers - some are easy, some fiddly, and the others involve a half-barre across the three top strings, with any of the fingers index, middle or ring. Try them all out, there will be 3 or 4 that will be good for you.
Comment: I actually forgot that I do have charts I made where I mapped out all the notes for each chord across the complete fretboard. Sorry about that. ;-)
Answer: Welcome to the wonderful world of learning to play guitar.
I think one of the must frustrating things for new aspiring guitarist in the beginning stages is learning to play chords.  The strange and unusual shapes that your brain must get your fingers to contort into are unnatural and often very difficult in the beginning. Everyday life does not require your fingers to do anything like what you must do to form chords.  Yet the ability to play chords is central to playing the instrument - because just about everything we do on a guitar revolves around chord formations.
One of the problems is that to play guitar and form chords, you must develop finger independence. Most folks start out with one finger wanting to drag another along with it - but some chords require them to go in opposite directions.
One exercise you can do to help develop finger independence is to lay your hand palm down on a table and lift each finger (excluding the thumb) one at a time while keeping the others on the table. Then do the same but lift two at a time, alternating through all the possible pairings of fingers.  Finally lift 3 at a time in each of four combinations where the fourth finger would remain on the table.
Another exercise for finger independence would be to start with all of your fingers together and then make a scissor clipping motion first using your index and middle finger, then your middle and ring finger and finally your ring and little finger (pinkie).
These exercises can be done even when you don't have access to your guitar and will help your brain learn to control your fingers independently.  It's difficult to do at first but eventually it gets much easier.
As far as learning to form the actual chords, Tim made a great point in his answer about choosing logical chord formations that help you make common transitions without having to lift all of your fingers off the fret board.
To further illustrate the idea that there are different ways to form the same chord - click here  5 ways to play an open G to learn 5 different ways to play an open G that don't include any barre chord voicings of that chord.
After you decide on a chord formation that works for you that you want to learn, you will want to practice forming the chord until you can basically form it in mid air before your fingers land on the strings. In the beginning, you might start by practicing just hitting two of the three or four strings called for in the chord.  Place your fingers simultaneously and then straighten them and then place them again.  Do this over and over until you can do it quickly with two of the fingers.  Then do the same thing using two other strings (maybe one of the same fingers while bringing a third into play).  Finally, practice forming the entire chord and hitting all the strings with all the fingers at once then straightening your hand and repeating until you can do it reasonably quickly.
Once you are able to form a chord quickly and straighten your fingers and form the chord again, learn another common chord that fits with the chord you just learned (part of the chord set for the same key). So if you just learned to play a G chord for example - you might want to learn a D or a C chord next - as these are the two most common chords besides G that you find in music written in the key of G.
One you learn two chords in the same key, practice transitioning back and forth between the two because in the real world of playing guitar, that is what you will be doing often.
The most important thing I want you to understand is that it is natural and common and normal for it to be difficult to form chords in the beginning.  It is a slow process but once you begin to learn a few chords and start playing a few two or three chord songs, you will further the development of finger independence and it gets easier and easier to learn more chords as you go.
So realize that it will take time and there will be great frustration in the beginning.  But if you stick with it, you will be playing your favorite songs before you know it and you will be on your way to a life long skill that will provide countless hours of enjoyment.  Enjoy the journey!
Answer: In addition to the other answers, you need to look at your ergonomics, which will not only improve speed but prevent injury.  Musicians are small-muscle athletes and get injured without proper technique and warmup.
Press a chord voicing on your guitar with your fingers as close behind the frets as possible. Playing one string at a time, lighten your finger pressure until the string no longer sounds. Now press very slightly until the note sounds again. This is the finger pressure that you should use when you press chords.  You will slow down and hurt yourself if you get a death grip on your guitar neck. For every chord shape, play each string to make sure that the string sounds cleanly.  If a string does not ring, then adjust your finger position not your finger pressure.
Fret chords with your wrist as straight as possible, even for barre chords.  Cranking your wrist at a sharp angle pits your fingers against your wrist.  You don't want to fight yourself.  Angling the guitar neck up and making sure your thumb is on the middle of the back of the guitar neck helps.  Keep the thumb relaxed.  You can actually fret chords without your thumb on the neck at all, it's just a convenient anchor.  Keep the guitar in position by pressing the elbow of your picking hand on the body of the guitar, not your grip on the neck.
Learn the open position chords next to the nut first.  Then learn to play power chords.  Then learn barre chords.  Open position chords you will learn to play without even thinking about them.  Power chords are for when you know the root of the chord but can't finger its major or minor form.  Barre chords are for when you don't have an open position chord for that chord.  Bb major, for example.
Go forth and do good!


Environmental concerns of a plastic bottle boat?

Question: Having found several images of boats constructed primarily of plastic bottles, the boy scout within me was interested by the idea. However, I know that plastic bottles biodegrade in sunlight, and the byproducts of plastic biodegration are a major pollution concern. All of the resources I encountered when researching this idea state that the rate of biodegration is heavily affected by the flexibility, density, and pigmentation of the plastic in question, but I was not able to find resources detailing the specifics.
Due to its availability, I am mainly considering a boat made of Polyethylene Terephthalate (PET, PETE), which is used for standard two-liter soda bottles and Gatorade bottles. I am interested in what effects this material will have on both the lifetime of the boat and the rate/amount of pollution the boat will contribute to.
Comment: Not sure how to link questions, but this one is very related: https://sustainability.stackexchange.com/questions/734/how-to-make-a-fully-reused-reusable-plastic-bottle-raft
Comment: Why wouldn't you use the bottles for some time in your boat, then discard them responsibly? Given that an adagium for waste is *reduce - reuse - recycle*, you extend the 'reuse' phase this way, which is good.
Comment: Most plastic is not biodegradable.  This includes PET and PETE.  Instead, over any interesting timeframe, they break down into smaller pieces of plastic.  This is the hazard.  Tiny pieces of PET and PETE floating around the environment, being eaten by things which then get sick or concentrate them to be eaten by something else which gets sick.  Making a boat out of this stuff is a great way to accelerate the rate of this degradation and pollution.
Answer: The boat made from plastic bottles is a nonsense. One day it falls apart and makes more pollution to the environment, than the recycled bottle.
If the boat is motorized, then this could be the source of the pollution too, as the bottle shapes usually are not optimized for hydrodynamics processes and the boat is usually very slow and consumes much more fuel than a regular boat.
I would not worry so much about sunlight degradation, as this could be a very slow process with PET bottles. Bottles will become yellow on the sunlight. Here is the whole study. This can cause some problems due to recycling. The question of what chemicals are produced by PET during such exposure is here. It could be:

Ethyl Benzene
Benzoic acid
4-methyl Benzoic acid

but potential health issues were not analyzed and are unknown. Sunlight degradation of the bottles could be stopped by UV stabilizers, but usually is not.
My conclusion is:

RECYCLE
do not use plastic bottles for construction in the exterior, gardening etc.
buy or construct a ship of a suitable material and shape and you will save the nature.


local DB server as proxy/cache for big storage engine which is online

Question: There is a big database engine running online with an interface to the net. You have a local software that is not written by yourself, which tries to connect to a local database. To connect these two I thought about using a local DB engine that kind of proxys the requests to the online db and caches the result for usage by the software on the local machine.
Does such kind of sceniaro makes sense? How would you solve that problem?
Answer: Your question is too abstract. Please add more details or this question might be flagged and deleted.
What is this 'big database engine'? (some sql database?)
what technology uses local software? Are you absolutely sure is it not possible to change connection address?
As for proxies, there are number of proxy(+connection poolers) for different database engines.
As for cache, in genetic case you'll get inconsistent results when trying to cache sql answers.


How to make a mustard sauce for salmon steak?

Question: I'd like to make a sauce for salmon steak, using a whole grain mustard. I would make a roux-based white sauce but I'd like something healthier because the roux has a lot of butter in it. Any ideas of what else I could use to make the sauce?
Answer: Gravlaxsås is a mustard sauce for salmon, made with dill.
The one I bought reports the following ingredients:

mustard
vegetable oil
sugar
water
wine vinegar
dill
modified cornstarch

On this site, the ingredients reported for gravlaxsås are the following:

6.5 tbsp. oil
2 tbsp. vinegar
2 tbsp. prepared mustard
1 egg yolk
0.25 tsp. salt
0.25 tsp. dill

Preparing the sauce seems quite easy:

Mix all ingredients in a jar and fasten lid.
Shake vigorously until the ingredients are well mixed.

Gravlaxsås is the sauce used for gravlax, a dish prepared with raw salmon, cured in salt, sugar, and dill.
Answer: I began writing this as a comment to kiamlaluno's reply about gravlaxsås but it turned out too long to post as a comment. +1 for suggesting gravlaxsås, but the recipe does not have much to do with the traditional preparation that I am used to (I am Swedish). I found a more orthodox version here:
http://www.grouprecipes.com/45013/gravlax-or-dill-cured-salmon-with-sauce.html
A few tips if you want to try making this sauce: The dill has to be fresh. Do not even think of using the dried stuff. If you  cannot get fresh dill, just leave it out altogether or make different sauce. The sauce contains some sugar, the amount of which you can adjust to your liking. The recipe in the link fails to mention the amount of dill. You should use a lot, like 1/2 cup or so of chopped dill. Regarding the mustard: If you cannot get to Ikea, just use any whole-grain mustard and adjust the amount of sugar and vinegar accordingly (the Swedish-style mustard is usually quite sweet, and so should this sauce be).
Answer: I'd make some kind of honey-mustard sauce, perhaps with either some horseradish or dill in it. Just honey, mustard, perhaps a little lemon juice, salt and pepper.
Answer: A mustard sauce is pretty much going to end up tasting like mustard, with possibly one other note if it's a strong underlying flavor.  Other than that, you're just balancing texture.  I'd go with a bunch of mustard, bit of white wine, bit of olive oil or grapeseed oil, and small bit of horseradish to taste (told you the second note had to be strong).   A "bit" in this context means "an appropriate amount to make a sauce of desired thickness and oiliness" while a "small bit" means "enough you know it's there, but not enough to overpower anything".
You could also go with dill instead of horseradish but, well, I hate dill.
Comment: While I agree, this answer difficult to follow without some culinary background.  Would you consider rewriting it some to make it easier for a new cook to understand?  The discussion of notes, balancing texture, and vague quantities are particularly challenging.


WP REST API returns blank response if post is too long

Question: I'm working on an iOS app that requires the use of WP Rest API to fetch posts. Everything is working smoothly and I fetch posts by ID using this endpoint:
<code>https://example.com/wp-json/wp/v2/posts/12345
</code>
Most of the time the API returns the post as expected, but if the article is over 1300 words long or so, it will return an empty response. By empty I mean the page will be completely blank, not even a 404 status code or an empty array []. It does return code 200 which supposedly means everything looks good, but the response is empty.
From my troubleshooting it seems that the reason for the empty response is because the post has too many words. Is there any way for me to update the WP REST API settings? Or do I have to create a new custom endpoint that can handle the retrieval of large posts?
Any help would be much appreciated.
Update: I installed the REST API Log plugin to see what's going on. To my surprise, I am getting the correct response in the response body, but for some reason it is not showing up in any browser. Will have to investigate further.
Update2: Still nothing. I have a second wordpress installation and I decided to try and replicate things there. I imported the 1300+ word long post into the new site and the same thing happened. If you try to fetch the post by id or slug it will just return a blank page...
Small rant. Not sure what the issue is, but WP REST API has been giving me nothing but problems. Not sure why they even decided to update the API as v1 worked perfectly fine for me. v2 just gives me problem after problem.
Update3: Decided to write a custom endpoint and see what's going on. Wrote a function to only return the post_content which seems to be the issue. This is the code I got:
<code> function get_long_post ( $params ){
    $post = get_post(59101);

    if( empty( $post ) ){
        return null;
    }
    return $post->post_content;
 }
 // Register the rest route here.

 add_action( 'rest_api_init', function () {
        register_rest_route( 'custom/v1', 'long-post',array(
            'methods'  => 'GET',
            'callback' => 'get_long_post'
        ) );
 } );
</code>
It simply pulls a post by it's ID and returns the content. I hardcoded the ID of the long post in question and surprise surprise, the response is blank. Works flawlessly for any other post that isn't super long.
Update4: This "question" might end up being super long with all my updates. But for the poor soul that has to deal with this I think documenting as much as I can is best.
I do feel I'm getting somewhere because I am now able to at least see part of the long post_content if I get a substring of the overall post_content. It seems that any substring with more than 7603 characters will NOT show in chrome or other browsers. Here is the modified function that returns at least part of the content:
<code>     function get_long_post ( $params ){
        $post = get_post(59101);

        if( empty( $post ) ){
            return null;
        }
        //echo "<script>console.log( 'Debug Objects: " . $post->post_title . "' );</script>";
        $output =  apply_filters( 'the_content', $post->post_content );

        return substr($output,0,7603);
}
</code>
Don't ask me why it's 7603 characters. I have no clue why it's such a weird number. Going to have to investigate further.
Update5: Progress has been made! If I use echo instead of return then I get the full post content. At this point, I'm thinking of just rewriting the get REST api v2 functions I need using echo instead of return. Will have to do a bunch of formatting to get it into a valid JSON format but at this point it seems like the only solution. Will update this when I get the full functions written. After all, for my iOS app I only need a few things from the post like the post title, author, content, categories, featured image, post ID, and tag. Here is the function so far:
<code> function get_long_post ( $params ){
    $post = get_post(59101);

    if( empty( $post ) ){
        //return null;
    }
    $output =  apply_filters( 'the_content', $post->post_content );
    echo $output;
    return null;
 }
</code>
Answer: I have the same issue as you. I figured out the problem is actually with json_encode.
I fized this by making a custom API, and converting my data to JSON using json_encode by using the options:
<code>$json = json_encode($your_array, JSON_HEX_TAG | JSON_HEX_APOS | JSON_HEX_QUOT | JSON_HEX_AMP | JSON_UNESCAPED_UNICODE)

return $json
</code>
Using that solution, you no longer need to echo the data.


Xen machine can see others on subnet but not gateway

Question: EDIT: solved
it appears that switching static MAC definitions combined with mapping vif/0 and vif/0 statically to eth0 and eth1 (in domU, as per http://tomclegg.net/xen-eth0-renamed) done it.
I'm troubleshooting this strange issue (well, for me at least) on my xen domU.
Here's the basic layout:

-------- -------------
|      | | XEN  d0   |
|  A   | | --------- |
|      | | | xen dU| |
-------- -------------

Host A is unrelated machine with IP 213.226.13x.yyy/24
XEN d0 is the hypervisor with IP 213.226.13x.zzz/24
XEN dU is the guest OS (debian etch) I'm trying to configure to see the gateway, it has IP 213.226.13x.jjj/24
The gateway is 213.226.13x.1.
All machines are on the same subnet. The problem is that gues OS can't ping the gateway, but can ping dom0 and host A no problem.
dom0 and host A can ping each other, the gateway and guest.
Things I've tried on host A:
ARP ping
$ arping -c 1 -i eth0 213.226.13x.1

ARPING 213.226.13x.1
60 bytes from 00:02:b3:e8:30:7e (213.226.13x.1): index=0 time=224.113 usec
...

(strangely, arping -c 1 -i eth0 00:02:b3:e8:30:7e does not work).
Broadcast ping
$ ping -b 213.226.13x.255

WARNING: pinging broadcast address
PING 213.226.13x.255 (213.226.13x.255) 56(84) bytes of data.
64 bytes from 213.226.13x.18: icmp_seq=1 ttl=64 time=0.463 ms
64 bytes from 213.226.13x.28: icmp_seq=1 ttl=64 time=0.478 ms (DUP!)
...

Same stuff on xen guest doesn't return any results (both, arping and ping -b).
$ iptables -L output on both, host A and xen guest is the same (zero rules):

Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

Things I've ruled out as of this time:
damaged physical link - XEN dom0 wouldn't work also, which is not the case.
firewall on gateway - my ARP pings would still get through?
firewall on xen guest - iptables -L has no rules
routing issue - not sure about this one, but I wouldn't be able to ping host A and dom0 with messed up routing table, would I?
Any help is very much appreciated
EDIT1: additional info
I'm not using xen's bridging scripts, network-dummy instead with manually created br-eth1 for eth1 which is the interface for the local network. eth0 is the bridge created by XEN installation for eth0 interface (renamed to peth0 AFAIK).
Here's how /etc/network/interfaces look like on dom0:

# The loopback network interface
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static
  address 213.226.13x.zzz
  netmask 255.255.255.0
  gateway 213.226.13x.1

auto eth1
iface eth1 inet manual

auto br-eth1
iface br-eth1 inet static
  address 192.168.1.11
  netmask 255.255.255.0

And "brctl show" (with domU being off)..

bridge name bridge id       STP enabled interfaces
br-eth1     8000.000423d0d059   no      eth1
eth0        8000.000423d0d058   no      peth0

EDIT2: additional info
XEN config for domU:

#
#  Bootloader + kernel + memory size
#
bootloader  = '/usr/lib/xen-3.2-1/bin/pygrub'
kernel      = '/boot/vmlinuz-2.6.18-5-xen-686'
ramdisk     = '/boot/initrd.img-2.6.18-5-xen-686'
memory      = '3072'
vcpus       = '4'

#
#  Disk device(s).
#
root        = '/dev/sda1 ro'
disk        = [
                  'phy:/dev/vg_main/domain-disk,sda1,w',
                  'phy:/dev/vg_main/domain-swap,sda2,w',
              ]

#
#  Hostname
#
name        = '...'

#
#  Networking
#
vif = [
        'ip=213.226.13x.jjj,mac=00:16:3E:83:0B:BC,bridge=eth0',
        'ip=192.168.1.12,mac=00:16:3E:83:0B:AC,bridge=br-eth1',
]

#
#  Behaviour
#
on_poweroff = 'destroy'
on_reboot   = 'restart'
on_crash    = 'restart'
Comment: It would be clearer to place your solution as an answer itself.
Comment: Need all networking details, along with tcpdumps for all cases at all points in the chain.
Comment: If you could provide the output from running `/sbin/ip addr`, `/sbin/ip route` and `/usr/sbin/brctl show` that would help
Answer:
Show your xen bridge/route script (that actually provides network for domU).
What's the difference in tcpdump output on dom0 external interface when you ping host A and gateway from domU ?


Is there any FAR defining an "introductory" or "familiarization" flight?

Question: I have given a number of young people their first inspirational flight. I am a CFI, but I do not issue any endorsement for these flights, and do not charge for my time or the aircraft. Is there any FAR defining "introductory" or "familiarization" flight, or addressing how many times a non-flight-student (no student pilot medical certificate and no student pilot log book) can receive an introductory or familiarization flight?
Comment: Free aircraft/instructor??? You are one of very few that offer that, usually introductory/discovery flights run $100 or more. It is also a way to filter out people just wanting airplane rides versus those who are seriously considering training. If you want to offer free flights, I'd suggest joining the Young Eagles program, but you should charge for your airplane at the very least for intro/discovery flights. I'd be interested in hearing about your conversion rate...
Answer: There's no formal definition or regulation that I could find; introductory flights aren't defined in 14 CFR 1.1, for example. I'm not sure why the FAA would care how often you fly with someone, or what the difference is between an introductory flight and any other flight with a non-paying, 'non-logging' passenger.
The only other people who might care about it are the TSA but if you aren't providing instruction during the flight then that shouldn't matter either. Introductory flights are usually understood to be a "demonstration flight for marketing purposes" (49 CFR 1552.1) and therefore exempt from TSA requirements, but there doesn't seem to be any rule about how many demo flights you can make with an individual.
Comment: The verbal direction we have received from the TSA is that the marketing rule is only for the first flight. Yeah, yeah..."but show me the reg," right? Given the aggressor here will be the TSA and admin courts typically side with the administrative org, take your chances with multiple "intro rides" at your own risk. I sincerely belive the spirit of the rule is pretty clear and I *rarely* take a pro-regulation (or even regulation tolerant) position on anything.
Comment: @acpilot That's a good point, and it's a messy situation for sure. Did the TSA tell you that their intro flight direction applies to foreigners only, or also to US citizens? At least for now citizens don't need any TSA approval anyway until they solo.
Comment: I don't know the details.  I was not part of the talk.  Management was.
Comment: @acpilot OK, thanks. I was wondering because I've read about the 'one flight' statement from the TSA before, and it always seems to be a verbal thing and always in the context of foreign students. But all the references I can find were written before the TSA started vetting citizens too, so I don't know if their 'guidance' has changed now.
Answer: There is no FAR regarding intro flights for prospective student pilots. Different instructors handle things differently.
I use a log sheet which was created with a spreadsheet program, which I use for student flights. It has critique blocks for different parts of the lesson, which includes preflight, engine start, take-off, medium bank turns, etc.  You get it.
The prospective student gets graded same as if they were a continuing student.  I sign the sheet, and they do as well, and they get the original and I keep a copy.  Their time is dual-received and mine is dual-given. They get the same post-flight briefing I give students, and it includes tips on handling parts of the flight, perhaps motion induced feelings, and what to expect in future lessons. I tell them  to keep the sheet, and should they take up lessons in the future, that sheet can become an entry in their logbook, and put into an envelope in the rear of the logbook.
This way students have a better idea how lessons will work, and the same importance is given to the first lesson as will be the case in all subsequent lessons.  It is situational, but usually my intro flights take the same 90 minute time that I plan for other training flights.
I always try to have the student practice a few things they do well at, such as power settings, trim or medium bank turns to a heading, so that there are parts of their critique which will show higher scores. The scores are genuine, and if the student does poorly, that is the critique they get, along with any coaching.
Through the years I have given initial rides to 75 yo and 9 yo. These rides are lessons, and not "Eagle Flights" or some other ride.  Accordingly, I handle the TSA required documentation as if the flight initiated flight lessons.


What kind of ID does the US accept when visiting bars or drinking age events?

Question: For tourists visiting the states, what kind of ID do you need to carry with you to visit bars or drinking age events?  I understand the passport is the main piece of ID but do they accept any other forms of ID from other countries such as a driver's license with a photo?
Comment: Showing a driver's license in order to be allowed to drink alcohol always puzzled me.
Comment: @JeremyMiles "it's a bad idea to carry that around" unless you're near the  Mexican or Canadian border.  In that case, it may be a bad idea to go out without your passport.  See, for example, http://redbus2us.com/h1b-issue-at-immigration-checkpoint-within-us-must-carry-passport-visa-for-travel/
Comment: In San Francisco/the Bay Area, I've only been denied once when showing my Swedish driver's license. All other pubs, wineries and liquor shops have accepted it. Probably varies a lot though, and San Francisco has lots of internationals coming and going so bouncers are probably used to non-US IDs.
Comment: A friend visiting from Mexico was denied entry to a bar in Kansas, when she presented her Mexican national ID. Admitedly, the bouncer was a jerk, and anyone else probably would have accepted her ID.
Comment: It's because the driver's licence has your date of birth and photo on it. Any other ID that has those would work. In some states in the US, you can get a driver's licence which doesn't give you permission to drive, because you need a driver's licence for other reasons, such as getting into bars. You could use your passport, but it's a bad idea to carry that around.
Comment: At a certain store they would consistently refuse to accept my passport "because it is not an American issued document". Fortunately I had a visa in it, which was good enough for them. I did wonder what someone travelling with ESTA could have done ...  At a bar on the other hand they said that just showing a *photo* of an ID is good enough, acknowledging that it's not always a good idea to carry passports around.  So in practice anything can happen.
Answer: There is no nationally, or even locally mandated standard. I've certainly seen friends have no issues using both Passports and Drivers Licenses from their home country. I've also seen people have issues - especially when their ID is written in a non-latin script, or when they have a DOB which can be misread by using a non-American date ordering scheme, (i.e. someone born on August the 10th, 1992, would have their BOD listed as 8/10/92 here in the states, and would be of legal drinking age. If their ID instead reads 10/8/92 a not particularly sharp waiter may give you a hard time - admittedly, an extreme edge case.)
Realistically, there's no single answer that can be provided here however, because there is no standard for what's accepted. At the end of the day, the acceptability of your proof of age is up to the merchant with whom you do business to evaluate. You'll have an easier time in more cosmopolitan cities like New York, but realistically, you can't do much better than your Passport, and I've almost never seen an issue with one.
Comment: As an example of the lack of any standard, even some of the states don't recognize other states' IDs.  Massachusetts, by law does not allow any ID except a Mass license/ID or a Passport.  Nothing.  In practice this is often ignored, for obvious reasons, but I've been denied at restaurants multiple times for being out-of-state.
Comment: For what it's worth, I've personally seen someone turned down for using a passport. It actually happened frequently where I went to school. The argument was that the employee had no way of verifying on the spot that the passport was real and valid. This happened in a college town where there are commonly issues with fake Ids and underage purchase/consumption.
Comment: I am almost never asked to show ID.  I guess I am no longer youthful and beautiful.
Comment: Many years ago I showed a student ID and they accept it..
Answer: Generally bars have always asked me for my passport in the US. It's frustrating as you'd rather not take your passport out to town, but when I've tried to take my driver's license as ID, I've either been turned away, or had to really ask nicely and still get told to bring my passport next time.
In New Zealand, they're as strict - you either show a NZ driver's license, or a foreign passport.  Everywhere. No exceptions (well they're not meant to).  And similarly in the US, although with all the various states and their differences in IDs, sometimes you can talk your way out of it.
However, getting turned down WITH my passport? Never happened, and I've never seen it happen.  If in doubt, take your passport.
Comment: *It's frustrating as you'd rather not take your passport out to town...* I've always wondered about this, because I've always carried my passport on my person *everywhere* when in a foreign country. For one, I keep it on my person so that it would be very difficult to pickpocket (whereas I have had my luggage stolen when I was out and about in town), and second, I want a piece of ID that will suffice if I am asked for it by the authorities. I figure there will be less red tape if I'm in a situation where I need ID and I present my passport, versus another foreign ID.
Comment: There are plenty of places where the lockers are insecure or routinely broken into. It's also not as uncommon as it should be for things left at hostel and hotel safes to go missing. Especially budget/party/sketchy places. I always get a feeling of the place before deciding whether my passport comes with me or goes in the locker.
Comment: @ChrisGregg certainly in some countries you *have* to keep it on you (eg Russia), but in other places if there's a locker in my hostel dorm, that's where it goes, under lock and key.  Some hostels even have a safe in the reception area.
Answer: I am a "bouncer" in Boston. As far as the state of Massachusetts goes, it is very clear:
Boston bars must ID all people who appear to be under the age of 30.
Acceptable identification includes: U.S drivers license, U.S liquor identification, U.S military card, and all U.S. and international passports recognized by the U.S.
What is NOT accepted: International I.D's, or U.S employment cards.
I cannot stress this enough to foreigners visiting Boston: ALWAYS ALWAYS ALWAYS carry your passport on you if you plan on drinking alcohol at a bar or restaurant. We are encouraged to ID everyone, so if you look 29 and only have a foreign drivers license, you will not be allowed to drink. It's a state law.
Answer: I work in a grocery store as a cashier. We sell liquor.
We can accept any state issued IDs for the US, as well as passports. We are not permitted to accept any other forms of ID. This is a corporate policy, but I doubt that it is unique.
However if we get a passport we can't read, we need to have a manager look at it (like they can read it). I would not be surprised if a store/bar/club/etc where there is no way to validate an ID in another language would simply refuse to accept it.
Answer: The National Minimum Drinking Age Act of 1984 set the legal age of public possession and purchasing to 21. Some states do allow consumption at younger age (just not purchase and possession in public). There does not seem to be a common standard on valid identification, it seems likely that the laws concerning age verification for alcohol consumption vary from state to state.
The Liquor Control Board of Pennsylvania for example has the following information regarding valid ID:

Q:  What are valid forms of ID?
A:  The only acceptable forms of ID in PA are a valid photo driver's license or state ID card, a valid photo armed forces ID, and a valid photo passport or travel visa.

Currently living in Pennsylvania, I've been told by different bouncers that in Pennsylvania bars are required to check the age of anyone that looks 30 or younger, and that they may only accept passports from foreign countries, or any US issued identification. However, in four months I have only once been denied entrance with my German Identity Card. (I don't usually carry my passport.)
I would speculate that you should be fine everywhere with your passport, but foreign driver's licenses and ID cards might or might not work.
Answer: What establishments accept as proper proof of age is set at the state level. This means each state has it's own rules, although the great majority of these rules are very similar if not the same.
Your passport is by far your safest bet concerning forms of ID you already have. Some states may even allow you to obtain a state issued ID card if you are a student. Although, seeing as you mentioned you are a tourist, I'm assuming you're not a student.
Also, if you do a Google search for the liquor control board (or some synonym) in the state you are visiting, they will often list their accepted forms if ID. For example, here is Oregon's: http://www.oregon.gov/olcc/docs/publications/acceptable_id.pdf
Answer: A passport should always be enough.
My experience with a foreign ID (entirely written in latin characters) is that it always worked in big cities like NYC but a few times, I had to go back get my passport in smaller cities in California.
A foreign ID written entirely or partially in non-latin characters will be rejected way more often especially if it looks easy to counterfeit.
Answer: A passport is generally but not always enough in the USA, so sometimes you just have to deal with it and go somewhere else. I can't count the number of times I've had to point out the photo page of my passport to a bouncer, a lot of the residents in less cosmopolitan cities and small towns aren't familiar with international passports and won't recognise them as ID.
Also don't think you're home free because you're well past the drinking age, in the US it's likely you'll be refused entry without ID even if by appearance you're obviously well over 21 (wrinkles, grey hairs, full beard, etc..!).
I've traveled a fair amount and this only ever happened in the USA. Generally other popular countries for travel (New Zealand, Australia, UK, Europe) will look at you first and only ID you if it's unclear you're of age. I hadn't been ID'd for years until moving to the US, now I can't leave the house without my passport despite being in my 30's.
So to reiterate - take your passport, a pain yes but it's most likely to be accepted (and just be careful and aware that you have it on you), and don't be put out if it is rejected somewhere you go (just find another bar/restaurant to visit), and check with event organisers before buying tickets to a drinking age event what forms of ID they accept.
Answer: I was interested in other people experience. I'm a bartender at a nice chain restaurant here in Vegas. Our policy is only to accept a US drivers license/ID, US military ID, or international passport. All must be in date with no hole punched through. It's very frustrating to some patrons, especially since most casinos will accept international drivers licenses. I try to explain casinos are much more equipped to validate IDs compared to a restaurant.  I understand most travelers don't want to carry their passports...especially in Vegas where ANYTHING can happen...but it's your best bet.


Good DSLR camera for ice hockey pictures

Question: My son just started hockey and my pictures are very dark and grainy.  The lights are dim.  Was looking to get another camera and lens to take better pictures.  Would like to stay under $5,000.  Any suggestions?
Comment: What camera (and lens, if the camera accepts interchangeable lenses) do you currently have?
Comment: Spend part of the money for a good camera and fast zoom lens with a low f (aperture) value. Spend the rest of the money to a good course how to make use of such expensive equipment (if you are already know, forgive my wrong assumption).
Comment: Related: [Canon Camera Settings for Ice Hockey](https://photo.stackexchange.com/q/87107/15871)
Answer: If you are shooting ice hockey the exposure is probably biased by the white ice. Before you spend any money try to use the camera's exposure compensation to make the pictures lighter.
The Wikipedia article starts with an example which is pretty close to your problem (shooting snowy mountains).
Here are some more explanations on exposure compensation.
Comment: Letting the camera decide exposure in a hockey rink with flickering lights is doomed to failure.
Answer: The best way to shoot indoors sports in most fairly evenly lit gyms/rinks/arenas is to set exposure manually. It gives you the most complete control over shutter times, aperture, and ISO.
Keep in mind that manual exposure will be more accurate than automatic metering under flickering lights such as those found in most indoor sports arenas and outdoor stadiums used at night. The meter will often measure the lights at their peak and then the shutter will open when they are in the valley of their cycle and vice-versa. Setting manual exposure for the middle of the lights' cycle will get you closer overall for all of your shots.
There are cameras that measure the flicker of the lighting and time the shutter to open when the lights are at their peak. Most of them are Canon models. The 7D Mark II introduced the feature in late 2014 and most upper tier bodies (1DX Mark II, 5D Mark IV, 6D Mark II, 90D, 80D, 77D) and even a few "Rebels" (T6i/750D, T6s/760D, T7i/800D) include it. Nikon's D500 and D5 have a similar feature as does the Sony α9. Note that there are other cameras that have a "flicker reduction" feature that is only applicable to video shooting, but does not works when shooting stills.
If you want to get anywhere close to freezing the action you're just going to have to live with whatever flicker the lights are giving you. To eliminate most of the flicker you would need to use shutter times of about 1/125 second or longer/"slower" and that's not happening with ice hockey. If you can get the shots you want shooting raw that will give you more latitude to correct the color and exposure of the peaks and valleys of the lights in post-processing. (The linked question is about how to process hockey photos shot under marginal lighting. The answer shows an example of the power of raw post processing vs. jpeg.)
Of course shooting raw will lower the number of frames you can take in a burst before your buffer fills up and your frame rate bogs down. Normally you'll want to avoid filling the buffer completely, though. Try to limit your bursts to about half that so you will have a few shots in reserve if a key action moment happens.
You can set a custom white balance by shooting directly at a solid white, glare free section of ice. Intentionally underexpose a stop or two, set the focus switch on the lens to "MF" and defocus at either the MFD or infinity. If the lights in the venue flicker (they probably will - our eyes can't tell the difference but our cameras sure can!) take several shots and use a shot that is about halfway in between the brightest and darkest one to set the custom WB.
Don't forget to switch the lens back to "AF" when you've got the WB set. While you're at it, set the Image Stabilization to "On", the IS mode to panning mode if your camera/lens combo offers it, and the focus limiter, if available, to limit very close focus distances (unless your subjects will be closer to you than the focus limiter threshold at points in the action).
Unless you have a super telephoto lens (over 300mm) you're not going to get many tight shots unless the players are on the closest parts of the ice to where you are. If you plan on cropping shots of players further away your maximum shutter times will need to get shorter to control blur from subject motion than they would be for uncropped shots.
You're probably going to want to manually select the center AF point only and leave it there. Set the AF mode to AI Servo AF or AF-C (or whatever your camera maker calls "continuous AF"). You'll need to keep your main subject in the center of the frame. For distant shots you're probably going to crop a bit anyway, so you can adjust the composition if you want by cropping off-center. If you set the AF point selection to Auto you'll wind up with the closest thing in the frame (usually a plexiglass support) instead of your intended subject in focus. When shooting action I prefer to use the AF ON button to initiate AF and disable AF connected to the shutter button but it takes a bit of getting used to it. YMMV.
Set the drive mode to Continuous/Burst.
Set your aperture to f/2.8, set your shutter time to 1/1000 and then dial up the ISO until you get a decent histogram on the back of the camera when reviewing your shots. Avoid the +1/3 stop ISO settings on Canon DSLRs. Keep in mind that if you are shooting at a downward angle with most of the frame consisting of white ice you'll need the histogram to be shifted a bit to the right. If you're shooting from a very low angle such as the team bench and a lot of the frame is a dark background (such as dimly lit seating areas) you'll want a histogram more to the left. If 1/1000 second forces you into an ISO higher than you're willing to accept, reduce the shutter time to 1/800, 1/640, or 1/500 second and check your results. When reviewing your shots on the LCD, zoom in all the way to see how much motion blur you're getting.
Don't be afraid to take plenty of frames. Under the best of circumstances the "keeper" rate is lower for sports than most other kinds of photography. But that doesn't mean you shouldn't plan your shots instead of just "praying and spraying." It just means you should accept that sometimes the action will move a different way than you anticipated. Sometimes the AF will miss a little. Sometimes it will miss by a country mile. Sometimes another player (or, even more likely, a referee with his back to you) will pass between you and your subject at the exact instant the shutter is open.


Is File >> Export always redundant when you have File >> Save As...?

Question: Is it better to keep both?  Chose one?  What criteria would you use to select one over the other?  If you had a button you had to name, rather than the menu to store this, would "Export is shorter than Save As" be sufficient criteria to select one over the other?  Edit: Would already having a File >> Save or a Save button influence your decision?  I think my fear here is that saving to another name is implied in the As... bit.
Answer: No it is not redundant.
"Save" should be the primary way to save files in formats that don't cause a significant loss / degradation of data.
I would use "Export" for file formats where major loss of fidelity or information is expected (for example, exporting a spreadsheet to txt or csv).
Looking at the inverse operations ("Open" vs. "Import") may be useful -- I think "Open" should be able to immediately read a file, while "Import" may require specifying extra options for parsing it (e.g. marking columns or delimiters to use when getting a table from a txt file).
Export/Import may also imply partial/incomplete support for a format. When I use Save/Open, I'd expect to be able to use the format as the native one, with no loss of data ever.
Comment: Well stated and addressed another issue too.
Answer: I'm not sure how this works on other platforms but on the Mac there is the following clear distinction in document-based applications, which has little to do with file format fidelity:
Save As... causes all subsequent Save's to overwrite the file you just created using Save As..., so Save As... modifies the location of the document that you are working with and stores its current state in that new location, while leaving the original copy untouched.
Export does not have this effect, you export to a specific path only once, after that a Save operation will still save to the location of the document as it was before the Export was done.
So, even in an application that supports a plethore of file formats, such as e.g. Excel, which allows you to Save As... to various formats of varying fidelity, an Export command may still make sense.  In fact it makes way more sense than saving (as) a complicated document to .CSV, seemingly retaining any formatting/graphs/etc. in the document, while affecting any subsequent saves to also save to that same lo-fi .CSV file.
Summarizing:  The fundamental difference is not in file format fidelity, or 'how native' a format is, but the conceptual difference —as I described above— leads to a logical distinction in what qualifies (fidelity) a file format to appear in your Save As... choices, and when you might want to relegate it to an Export feature.
Answer: In most applications I use that have both, the Save As is used to save to a native format, but the Export is used to save to a format that is somehow lossy in that if you reopen the file (if that is even possible) some of the information used to create it will not be available any more.
Example: Say you've got a program that generates music.  The editor has a score and some instruments to play.  You can 'save as' and get a standard gmidi format file, which you can later edit some more if you want to change a track.  The export option will also be there to save a MP3, but this won't let you change the file afterwards.
Answer: I would usually consider an "Export" function to have the ability to write the file to a different format than the "native" format for the application. For example, an image editing app might have a "Save as" to save as a different file in the native format, and an "Export" to export the image to a JPEG or other format.
Answer: I view [Export] as changing the format of the saved data. Whereas, [Save As] is saving the same format to a different location.
Obviously you could argue this by pointing to the various image editing programs out there where [Save As] lets you do both.


"unsubscribe from this email" should not be so close to items - how to re-enable?

Question: I just got a "1 new items in Your Stack Exchange inbox" notification (about a comment replying to mine), and accidentally hit the "If you no longer wish to receive updates every 3 hours, you may unsubscribe from this email" link.
I didn't look very closely and was also in the mood of finding the link to the post below the post, as it is the case in many other notifications I get.
The two actions of visiting the post (the normal action) and of unsubscribing (a one-time, destructive action) are very close together in that email.
The unsubscribe link should be in the footer imo, together with the "feedback site" link.
Now how do I get back my notifications? Did I unsubscribe for that post only?
I see that I can select to get new responses by mail when posting a question, but what if I post a comment?
Or is that setting not even post-specific? After all, it says "Send me new responses to my posts via email", so I guess that affects all posts (and comments?). Then why is it above the "post your question" button - everything else above that is specific to a post. (I suggest you swap the "sen me new responses" and "answer your own question" checkboxes, making the former clearly distinct).
This is an area that needs usability work I guess.
Comment: Well, the unsubscribe-link *must* be obvious at first glance to avoid getting reclassified as spam, so the footer is out. Now making sure the other links aren't directly next to it, that might be doable...
Answer: There's a preferences link on your profile page, you can find subscription settings there.


Why does the Riemann zeta function have zeros in the complex plane? How is it possible to find them?

Question: I ask this because, according to Euler's product formula, Riemann's zeta function =(1/something), so how could that be zero?
Also, how could one find zeros that are on the negative side and find a zero in the "critical strip", that is, when the real part of the input is between 0 and 1?
Comment: Euler's product formula is only valid when $\mathrm{Re}(s)>1$; indeed, the original $p$-series doesn't even converge unless $\mathrm{Re}(s)>1$, so one needs to perform [analytic continuation](http://en.wikipedia.org/wiki/Analytic_continuation). Otherwise [Weierstrass factorization](http://en.wikipedia.org/wiki/Weierstrass_factorization_theorem) gives the Hadamard product $$2\pi^{-s/2}(s-1)\Gamma(1+s/2)\zeta(s)=\prod\left(1-\frac{s}{\rho}\right)$$ taken over the nontrivial zeroes $\rho$. I believe this product is globally convergent.
Comment: [Quite related...](http://math.stackexchange.com/questions/7783)
Comment: Unfortunately, I don't have enough points to post comments, but just to tell you that you need to consider the analytic continuation of the function beyond the strip, to find the zeros.
Answer: Wherever it converges, the Riemann zeta function $\zeta(s)$ is equal to the $p$-series - and it converges only when the real part of $s$ is greater than one. The Euler product analogously only converges when $\mathrm{Re}(s)>1$, so the reasoning that $\zeta=1/\text{something}\ne0$ does not apply where the product is an invalid representation of zeta.
Moreover, the idea is flawed all by itself: the "$\text{something}$" is an infinite product, so if that product diverges to infinity in the limit, we have $\text{something}^{-1}\to0$. For example, formally we have
$$0\le\frac{1}{(1+1)(1+1/2)(1+1/3)\cdots}\le\frac{1}{1+1/2+1/3+\cdots}=\frac{1}{\infty}=0.$$
In general, properties (e.g. inequalities) satisfied by expressions with a finite number of terms do not necessarily carry over to an infinite number of terms (but we can still apply logic to the partial sums if need be).
So if neither the original series nor the product converges outside the right side of $1$, how can it be then that $\zeta(s)$ can be computed on or to the left of this? The answer is analytic continuation, which I gave a brief introductory explanation to just recently. But then precisely how can it be explicitly extended left of $1$? The simplest, but limited, way is through the Dirichlet eta function:
$$\eta(s)=1-\frac{1}{2^s}+\frac{1}{3^s}-\frac{1}{4^s}-\cdots=\left(1+\frac{1}{2^s}+\frac{1}{3^s}+\cdots\right)-2\left(\frac{1}{2^s}+\frac{1}{4^s}+\cdots\right)$$
$$=\zeta(s)-\frac{2}{2^s}\zeta(s)=(1-2^{1-s})\zeta(s).$$
The eta function converges for $\mathrm{Re}(s)>0$, so if we write $\zeta(s)=(1-2^{1-s})^{-1}\eta(s)$ we have a way to evaluate zeta to the left of where we originally could (by $1$ at most). Analytic continuation beyond this requires more sophisticated machinery - a functional equation was first established by Bernhard Riemann in the paper "On the Number of Primes Less Than a Given Magnitude,"
$$\zeta(s)=2^s\pi^{s-1}\sin\left(\frac{\pi s}{2}\right)\Gamma(1-s)\zeta(1-s).$$
This means that what $\zeta$ evaluates to on the left of $s=1/2$ is determined by its evaluation on the same point reflected across $s=1/2$. With this and the $\eta$ continuation we are given the ability to compute $\zeta$ anywhere we like. Note that with the presence of the $\sin$ above, it is trivially true that $s=-2n$ are zeros of $\zeta$ for $n=1,2,3,\dots$ Moreover, since $\zeta(s)$ has no zeros right of $\mathrm{Re}(s)=1$, the functional equation predicts it has no other nontrivial zeros to the left of $\mathrm{Re}(s)=0$: this means all of the nontrivial zeros lie in the critical strip.
The Riemann Hypothesis is that all nontrivial zeros have real part $1/2$, but it has not been proven - we can, however, calculate the zeros to arbitrary accuracy and prove when particular zeros have real part exactly half, see this question linked by J.M.
As a sidenote, while the Euler product doesn't converge globally, I believe the Hadamard product (via Weierstrass factorization) does globally converge - see my comment above.
Comment: +1! I'd have taken this example of an infinite product equal to $0$: $$\frac{1}{2}\cdot\frac{1}{2}\cdots$$ I'm lazier than you...
Comment: @Pierre: Heh, for some reason I was unconsciously shooting for a product where the factors approach $1$ in the limit, to keep it analogous to the Euler product.
Answer: Inferences about location of zeros or poles of a function from a product formula are valid only in a region where the product converges to the function.
The constant function $f(x)=1$ has no zeros or poles but can be written as a product
$$f(x) = (1-x)(1+x)(1+x^2)(1+x^4)(1+x^8)(1+x^{16})\dots$$
which superficially predicts zeros of $f(x)$, and poles of $1/f(x)$, at all $2^n$-th roots of unity.  The formula holds for $|x|<1$ so there is no contradiction.
For $\zeta(s)$ the non-trivial zeros are known to exist only through Riemann's explicit formula and calculations on the line $s=1/2$.  I don't know if there is any other argument for why zeros should exist with real part in $(0,1)$, except for analogy with other types of zeta functions (that did not exist in Riemann's time).


Why do some references in Dune mention the scope as just the galaxy and others the entire universe?

Question: At some points, in the various books, we see references to the scope of the story being just the galaxy. At other points there is reference to the entire universe. I've read all the books over the years and have never been able to reconcile this.
Comment: Care to give us an example?
Comment: In the first book only, or the series as a whole?
Comment: The series as a whole...
Answer: The Galactic Padishah Empire, or the Imperium, was referred to as spanning "the known universe".
The borders of colonized space are never accurately described.
During the time of the Padishah Empire, the realm seemed to be contained within the Orion Arm of the Milky Way Galaxy, and some of the core worlds (e.g. Giedi Prime and Caladan) were described as being within 20 light years of old Earth.
In God Emperor of Dune (Page 13), Leto II refers to his "multigalactic empire", so it seems that the scope has either expanded, or some components of the earlier empire were actually outside of the Milky Way.
However, after The Scattering precipitated by Leto II, the range of the "known universe" expands tremendously.  At this point, it is almost certain that multiple galaxies have been colonized by humans.
It is worth noting that the Honored Matres make reference to old Imperium as the "Million Planets".
A really interesting and detailed analysis of the astronomic geography of the Dune universe can be found here.
Comment: I know it's considered canon because Leto II says it, but the 'multigalactic' empire has always been a hard thing to credit. The Milky Way is **really** big. Bigger than the average galaxy. Even if it were small the massive void between it and the closest one almost certainly precludes humans reaching it. Folding space safely gets more difficult the farther away the destination is, and even folding huge chunks of it would require thousands of years of jumps to get out how far our neighbor galaxies are. I've always found it easier to say Leto was being hyperbolic when he said those things.
Comment: And, the HM referring to the original empire the 'Million Planets' can be safely considered a ritual intensifier. It's like when the UK used to say 'the sun never sets on British soil' or when we're informally exclaiming how far something is and we say to each other 'it's a million miles away!'
Answer: It's true that the main narrative of the Dune novels (I've read only Frank Herbert's books, but I don't think the prequels differ) takes place in one galaxy - our own, judging by the links to Earth religions.
However, one of the main themes of the series is the Golden Path, Paul Atreides' plan to rescue humanity from its stagnation. He never got to implement it, but Leto II did, and he scattered humanity far and wide throughout the universe, far out of the galaxy. The last two novels, Heretics of Dune and Chapter House Dune, deal with those far-flung chunks of humanity returning to the main galaxy,
So yes, the story of Dune can be thought of as being in one galaxy, if you want to stick to the narrative itself, or the universe, for the whole scope.


read hard drive from dead laptop without formatting

Question: I recently pulled the hard drive from a laptop with a bad power supply, and have plugged it into my pc via a USB-SATA bridge. Both drives come from Windows 7 machines. Windows recognizes the drive as mass storage, but refuses to let me read it without formatting it first. I kinda don't wanna lose my data. Any advice?
Comment: I have had on occasion been able to open a ntfs partition windows will not read from linux.  Might be worth a try
Answer: It could be (assuming the drive isn't physically damaged) the partition table is corrupt. You can use TestDisk to fix this, as well as recover partitions and files.
Documentation examples:
Step by step
Data recovery examples
Explanation of program options
Answer: Usually when we see this type of situation the system can see the drive but does not recognize the file structure, so it will ask you to format it. This may be the result of the drive being formatted through a serial header attached to the buss.  Going through the USB bridge is likely an incompatibility for the system's ability to read the drive. - Formatting it would fix it as far as the system knows, and it would work just fine.
Your data is still most likely intact and can be accessed through a SATA interface attached to the buss.  If you have access to a tower with that interface, try this.  From my experience laptop power supply's are $20 on Ebay - no installation required.
In the old days I have slapped drives from one laptop to another, we are not supposed to be able to do this though it has worked for me numerous times.  The system just needs to load a new set of drivers - Win7?
You may also have luck with a partition or recovery tool, there many available.  I would give you a recommendation but it has been some time since I have played with one.
Hope this helps


What can I learn from these WW1 shell cases?

Question: We found these two shell cases in my parents garage. They were allegedly brought back from France by my great grandfather, but that's all we know and we'd really like to know more about them and wondering if anyone can help please? The larger shell has a diameter of 85mm and the smaller shell is 62 mm.  I hope the extra photos help. Thank you.
Comment: I can't make out all the detail at the moment (working on a mobile phone screen), but there are scanned guides to service markings on shells available online, like [this one from 1918](http://bulletpicker.com/pdf/Explanatory%20List%20of%20Service%20Markings.pdf). For example, the A in a circle followed by two punch marks shows that the casing had been repaired and annealed twice. C FFF means that it contained a cordite charge & the case was filled 3 times.
Comment: I'm not an expert by any means, but the largest one seems to be a French shell (A RS means Atelier de Constructions de Rennes ). However, it's a bit confusing, because the 10 should be for caliber in millimeters (17 is the year), and that shell looks bigger than 4 inches. Also, 4 inches would mean a howitzer or small cannon, and the only 4 inches shell on ww1 that I know of is the modified 4 inches Stokes Mortar (used mainly for chemical warfare in 1917), which was used only by British Army at that time. Maybe ammunition made in France for a British weapon?
Comment: Thank you! I have added extra pictures and the diameter of the shells
Answer: The Smaller Case
The smaller of the two seems to be a British shell case. A good source for First World War British munitions is the Explanatory List of Service Markings (1918), produced by the Royal Arsenal, Woolwich. Another useful guide is the 1915 treatise on Ammunition from the War Office.
It looks like it may be a 6-pounder round. That had a calibre of 2.2" or 57mm.
The markings that I can make out are:

the A in a circle followed by two punch marks shows that the casing
had been repaired and annealed twice.
C FFF means that it contained a cordite charge & the case was filled
3 times.
II indicates that it is a mark II casing
the 1 in a circle indicates that the case was to be fitted with a mk
2 primer
RL indicates that it was manufactured at the Royal Laboratories,
Woolwich

Another researcher that I'm working with this week believes that the "T" indicates that the shell was last filled at the Tipnor filling station and that the "95" is from the quality inspection carried out there.
The "DD" and "SOLD" stamps were, presumably applied after the case's service life.

The Larger Case
The larger case would appear to be French. It has been stamped "REMANIE" which indicates that the casing had been re-used.
From the picture, this could be the case from a 75mm mle (or French 75mm) round.
The other stamps on the base are: A. RS 10 17
I'm less familiar with French ammunition, but the 17 probably means the shell was produced in 1917, so by extension, "10 17" would suggest October 1917.
It's possible that the A.RS stamp indicates that it was manufactured in Rennes (Ateliers de construction de Rennes).

EDIT: If the measurements added to the question are across the widest part of the base of the shells, then that is consistent with their identification as a British 6-pounder and French 75mm respectively.
Comment: Yes, the measurements are taken at the widest part of the base
Answer: source
On the smaller case..  The encircled (A) means the shell has been fired once.  The two adjacent punch marks are given for each subsequent firing.  So this shell has been fired 3 times. This was a way the English  designates there shells, so it's an English shell. The C.FFF has to do with the Charge load.  It was fired with full charge, loaded with cordite again all 3 times.  Can't really make out much more..
On the larger case.. I can't match up any symbols.
Comment: Yes. The Explanatory List of Service Markings (1918), produced by the Royal Arsenal, Woolwich, linked in my comment on the question above.
Comment: I like your source better than mine..   good job.
Comment: No. The encircled A means it was annealed after repair. The punch marks show that this happened twice. See the guide to service markings on shells in my comment above.
Comment: I'm sure you know more than I.  I am 1 hour old in the art/disipline of shell deciphering.  I did notice that a non encircled A refered to annealing.   The reference given explicitly states "A (encircled).......Case has been fired once".   as well as the punch marks both being English designations.
Comment: Page 12 of the scanned pdf document.
Comment: @sempaiscuba you must be referring to your own source because the source given in the answer is not a scanned pdf document, it's a web page.
Answer: The French case is a 75mm x 350mm for the 75 DEC quick fire gun . DEC means de campagne (Field gun). REMANIE means it's a re-worked case. 10 is the Lot number , 17 is the year 1917. ARS is the factory (in the town of  RENNES).
Many models at forumactif.com :
Answer: Smallest is British (two little pits next to the A means the shell has been used twice).
Bigger is French A RS is the factory made in..
When you measure the top of these shells you will know the caliber..do research like "75mm French shell WW1" ..the British work in inch .. or pounders in their shell language .. 18 pounder, 60 pounder..6 inch..
Comment: Your answer could be improved with additional supporting information. Please [edit] to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers [in the help center](/help/how-to-answer).