Is there a faster process for converting splines into rigged meshes?

Question: I wanted to have my character's arms be more akin to that of a cartoonish noodle, so I decided that the best way to accomplish this would be to create a Bezier curve, create a mesh out of that curve by duplicating and converting it, create an armature from the curve's various points, rig the mesh to that armature, and apply a Spline IK constraint. However, I think that there might be an easier way to do it than how I'm currently accomplishing it. Here's my process.

Here is a simple Bezier curve. I would then proceed to duplicate the curve three times so that I can use each one for a different purpose.

I'd then expand the depth of one of the curves to a suitable value ('0.07 m' in this case) and convert it into a mesh.

Hiding the mesh, I'd move onto another curve, converting it into a mesh while making sure that the depth stayed at a volume of '0 m'. With the mesh being nothing more than a curved line of vertices, I'd then add a Skin modifier. After selecting the modifier's "Create Armature" button and deleting the mesh, I'd have an armature ready for me to utilize.

Before rigging the mesh to the armature, I'd extrude another bone out of the end bone for the sake of accurate deformation.

Allowing the mesh to become visible again, I'd select the mesh and then the armature. I'd then parent the mesh to the armature with empty groups (automatic weights give messy results).

Now here comes the part where I want to rip my hair out.
Since automatic weights don't give me the results I want, I'd select the armature, go to the Object Data properties, go to the "Viewport Display" tab, and check "Names". With that out of the way, I'd select the mesh and go into edit mode. I'd then select a ring of vertices and assign it to the vertex group that properly corresponds with the appropriate bone.

And then I'd do it again.

And again, and again, and again, until I eventually run out of vertex groups to assign the model to.

Now, it's not too big of a deal when I only have 13 bones within this example armature, but if I were to deal with 30 or 50 bones here so that the mesh can look extra smooth while the arm is being deformed by the spline, things suddenly get significantly more tedious to set up than before, especially so if I'm dealing with multiple limbs. After this I'd just add a Spline IK modifier to Bone.11 and add a few fancy hooks to the Bezier curve, but I think you get my problem here.
I don't want to go and apply weights to the various vertex groups in my model so that it responds to every single bone in my armature here. Is there a script/add-on that can do this automatically, or is there a better workflow that would make this sort of thing easier to accomplish?
Answer: Skin Modifier
Using the Skin Modifier along with a Subdivision Surface Modifier you can do this rather quickly.
The skin modifier has the option to create an armature for you, so convert your curve to mesh first, and use the modifier.

The spiral in the image below is a very basic example, but you can get the point from it.
Comment: Very interesting. I'll look into it!
Comment: It works! While it may be an issue if one were to want to imitate the bevel options that the curve geometry allows, it's a quick and simple method that is just what I need for my type of character. Thanks!


Whatsapp backup for new and old chats

Question: I recently accidentally deleted a chat in Whatsapp for Android 7.0 "Nougat". I know if you uninstall and reinstall the app, you can download the backup containing these old messages. Now my problem is, this certain contact messaged me again after deleting the chat, so if I use the uninstall method, I lose all the chats from after the deleted ones. If I say "backup now" as to keep the new messages, it will delete the old backed up messages and only keep the new ones. Is there any way I can have my bread buttered on both sides and get my old messages back while still keeping the new ones?
Thanks in advance.
Comment: No. Unless your device is rooted and you merge both databases, which is complicated and results in varying success!//mail yourself those chats from the contact and keep it safe. You have a record that can be used though not in chat format. //Delete and restore account  with old backup as usual
Answer: If these messages are important, you can root your phone in order to restore them.
There are many methods to root Android 7 to use at your own risk.
WhatsApp make a backup of the messages database each day at 2:00 AM, these databases are stored encrypted in /sdcard/WhatsApp/Databases/. The key used to encrypt the backup is stored in /data/data/com.whatsapp/files/key which can be accessed only if you have root privileges.
To restore your previous messages:

root your phone
enable USB debugging
dump the encrypted databases

adb shell pull /sdcard/WhatsApp/Databases/

dump the key

adb shell pull /data/data/com.whatsapp/files/key

use this python script to decrypt the encrypted databases:
Comment: https://forum.xda-developers.com/showthread.php?t=2896496
Comment: https://forum.xda-developers.com/showthread.php?t=2770982
Comment: https://android.stackexchange.com/q/205706

Whatsapp backup for new and old chats


Making a pineapple

Question: Do you guys know any good ways of making a pineapple in Blender? It can be low poly and cartoonish. So far THIS is best i got
Comment: Way better I could do it. Why don't you like your result?
Comment: LowRes https://identity.trimble.com/commonauth MidRes https://www.turbosquid.com/3d-models/free-max-model-pineapple/741563 HiRes https://www.the-boundarystore.com/products/pineapple
Answer: So... hi poly.

The leaves are done with an array modifier driven by an empty a bit scaled down, rotated and shifted down.

The body is an hexagon inside of which the pineapple skin is modeled. It is a bit stretched as will need to make it more oblong later.
Then use 3 arrays to have an hexagonal map:

Now we need to make that spherical, and we can use this answer to do it.
This is two simple deforms and a lattice to make it more tubular/oblong:

The sequence of modifiers:

PS: I know there is a gap at the edges of the second simple deform modifier. That will be possible to join it with the weld modifier in 2.83, using a vertex group. For now in 2.82 the weld modifier does not take the vertex group into account.
Comment: Can you describe the process of making the hexagon? Or point me to a link?
Comment: @Strawberry, to make a base hexagon, just add a circle and change its vertices to 6. From that here i've simply extruded and scaled down.
Comment: I get that part; it's what happens next that I'm struggling with! Ah, extruded and scaled down - let me try that
Comment: The best to see what is happening (from the blend file in the answer) is to disable all the modifiers (disable, not remove) then reactivate them one by one (like in the gif above). So you can see how it works step by step.
Answer: Low Poly

add Cylinder
in edit mode Loop Cut Ctrl+R
search Un-Subdive > 1
Scale down top and bottom part to shape oval

Triangulate Ctrl+T (but not necessary), for horiyontal split I scale it verticaly so blender use the shorter (horizontal) direction between vertices
for leaves - Extrude E / Scale S top vertices, Subdivide W and Scale down
Comment: That's actually quite a cute pineapple. But I have one question: If I look at it from the top or bottom, what will I see? Will the top just be green or the pineapple color? And the bottom? Is it just a pineapple-color "base"?
Comment: You will see what you make :) Yes I could left it filled and extrude, it make more sence - manifold mesh. It was just a quick test, I did not expect such interest on this topic.
Comment: WORK IS REALLY AWESOME DUDE
Comment: I'm sorry, but I do not understand your comment. Could you please rephrase it?
Comment: @IsmaelMiguel I dont understand your Q. It depend on you, how you will model your. Now there is a hole (because I delete top face as you can see), but you can keep top face when extruding "green" so like that it stay green from top, that is more natural.

Making a pineapple


Where can I find or make a script for focus stacking using Raynox DCR 250?

Question: I am looking for a script for focus stacking with Raynox DCR 250. There is already default script there but it is linear and that is better suited to stock lenses and, with the Raynox 250 attached, I think it needs to exponential focus. Can anyone help me find such script or may be some setting with that default stacking script? I am using a Canon SX40.
Comment: When you say script...do you absolutely have to have a "script"? There are a few tools, in particular CombineZ, that will automatically align and blend a focus stack for you. CombineZ produces pretty darn good results as far as I've seen, too. Would that work?
Comment: What do you mean by exponential focus? You mean instead of incrementing in fixed focus increments, you want it to skip some focus intervals? Not sure what this will buy you except to skip a few shots?
Answer: I have just written a focus-bracketing script for closeup lenses, including the Raynox 250.
Here is a link to my article, which contains documentation of the script as well as the script itself:
http://www.dpreview.com/articles/9780512447/focus-bracketing-scripts-for-macro-setting-and-for-closeup-lenses
Here is another link to some outdoor stacked images made using the script
http://www.dpreview.com/forums/thread/3508821
Answer: Really old thread.  Anyway, it seems people confuse 'stacking' and 'bracketing'.  Bracketing is used to capture a number of pictures of a scene while varying a parameter, exposure, focus, what have you.  Stacking is a post processing technique for combining bracketed photos to create HDR or increased depth of field, for instance.
For the original posters question, long time back i loaded up my Canon A720IS with the hacked CHDK firmware which facilitates scripting and wrote a script based on the  hyperfocal distances.  It worked ok and stacking the focus bracketed shots did result in enhanced DOF.
Some google fu came up with https://chdk.fandom.com/wiki/UBASIC/Scripts/CanonA640:_Focus_Bracketing
Comment: Unless i'm completely misreading, the OP is asking to focus bracket using his camera and the Raynox lens.  Once you have a bunch of bracketed photos they get stacked in some PP software. From what i understand the PP stacking sw is independent of lens.  Stacking sw combines the in-focus areas of each picture in the bracketed series.
Comment: The existing answers don't seem to confuse bracketing and stacking at all. The OP was asking about focus stacking for macro photography.
Comment: Thanks for response.. It's been long CHDK was fun. I was able to capture star trails. But I don't remember getting focus stacking work. I did manual shoot and stacking software to achieve some good result.
https://www.flickr.com/photos/ianoopkumar/8104934849/
Comment: @scottbb The OP itself does seem to have trouble making the differentiation.
Answer: I don't think you need to use a special "script". There are some softwares that do the trick and are easy to use.
If by any chance you're using photoshop, this guide will help you:
focus-stacking-made-easy-with-photoshop
I was using it to stack 20 photos and it works great for me.


Need help with Watch Tag Issue

Question: I was in a post, I put my mouse over an item to click, I clicked and at the same instant a Watch Tag popped up and I clicked it instead. How do I clear Watch Tags - that is, how do I reset them?
Answer: You can edit your watch tags in the side bar of the main site where there is an "edit" button on your watched tags.

Clicking "edit" will change the tags to add an "x" to remove them or add a box where you can add more tags:

Need help with Watch Tag Issue


Efficiency of short dipole receiving antenna

Question: For a transmitting dipole antenna, its length is important. If it is close to half the wavelength, it will be efficient and most of the input power will be radiated.
How important is the length of dipole in case of receiving antenna? Will a dipole of given length as inefficent as receiver as a transmitter? As far as receiving is concerned, how inefficient will a $\lambda$/10, $\lambda$\100 and $\lambda$\1000 dipole antenna relative to a $\lambda$\2 dipole?
Comment: The goals of transmitting and receiving systems may be different. The goal of a receiving system is to maximize the ratio of signal energy to noise energy. There are many very inefficient antenna systems which dramatically improve receiving capability.
Answer: The efficiency of any antenna has a direct impact on the gain of the antenna. The gain of the antenna equally effects transmit and receive - a characteristic known as reciprocity.
The highest gain dipole is a 10/8 wave dipole. When you begin to shorten that dipole, its gain drops. When the dipole becomes very short (<<1/10 $\lambda$) it is called an infinitesimal dipole. Its gain drops significantly.
To see what why the gain of the dipole is dropping, we need to understand the primary factors that make up antenna gain (in linear form):
$$ \text{Gain} = \text{Directivity} \times \text{Efficiency} \tag 1$$
The directivity of the dipole antenna does not change a lot because of its size. For example, a 1/2 wavelength dipole has a directivity of 1.64 and an infinitesimal dipole has a directivity of 1.5.
The major factor impacting gain, in the case of this dipole question, is efficiency. Efficiency is defined as:
$$\text{Efficiency}=\frac{R_r}{R_r+R_l}  \tag 2$$
where Rr is the radiation resistance and Rl is the resistive losses in the antenna.
The radiation resistance is the dominating factor in most cases. A 1/2 wave dipole in free space has a radiation resistance of 72 ohms. A 0.05 wavelength dipole has a radiation resistance of only 0.49 ohms. To see the effect this has, let us assume that the losses in the antenna are simply related to the length of wire. If the 1/2 wavelength antenna had say 1 ohm of losses, then the 0.05 wavelength antenna would have 0.1 ohms of losses since it is 1/10 the length of the 1/2 wave dipole. According to equation 2, this makes the efficiency of the 1/2 wave dipole 98.6% and the efficiency of the 0.05 wavelength dipole 83.1%. While this is not yet the complete efficiency story, if we pause here to plug these numbers into equation 1, the gains so far are are 1.63 (2.12 dBi) and 1.25 (0.98 dBi).
To complete the efficiency picture we need to look not just at the antenna but rather at the antenna system. This includes any matching network and transmission lines. For the latter, the calculations are fairly straight forward and it is length and frequency dependent so I will not address that here. But the matching network warrants some scrutiny.
The goal of the matching network is to transform the feedpoint impedance of the antenna into an impedance that minimizes the losses in the transmission line (when viewed from a transmitting perspective). In the case of a 1/2 wavelength dipole, as it is brought close to earth, its feedpoint impedance nearly matches the impedance of common coaxial cable (50 ohms) so no matching network is needed. Thus we can assign 100% efficiency to the matching network in this case.
The infinitesimal dipole is very short compared to a wavelength so its feedpoint impedance is dominated by capacitive reactance while the real part of its impedance is a fraction of an ohm (0.49 ohms in the earlier example). The matching network will therefore contain sufficient inductive reactance to neutralize the capacitive reactance and it will contain other reactive or transformative components to raise the real part of the impedance by a factor of 100 or so. Analyzing the efficiency of such a network requires a significant effort but efficiencies in the 20% range or less are not uncommon. Using this coarse estimate, this introduces another 7 dB or so of losses for the 0.05 wavelength infinitesimal dipole bringing its gain to 0.25 (-6.02 dBi).
To wrap up this analysis consider that the gain difference between the two antennas in this example is 8.17 dB. If 100 watts into the 1/2 wavelength antenna would barely allow another station to hear you, you would need to use more than 656 watts into the 0.05 wavelength dipole to achieve the same result. And to receive the other station, because of reciprocity, they would need to increase their power by nearly 7 times or you would need to find a receiver with 2.6 times more sensitivity (since sensitivity is expressed in field units such as $\mu$V and therefore the square root of power).
And finally, the radiation resistance of other lengths of infinitesimal dipoles is related by approximately the square of their fractional wavelength. So a 0.005 wavelength dipole has 1/100 the radiation resistance of our 0.05 wavelength dipole. Noting that the resistive losses only went down by 1/10,  if all other things are equal, and without considering the matching network efficiency, the antenna efficiency has dropped to 33%.
Answer: As antenna geometry (including length) changes, so does its radiation gain pattern in 3D space. According to reciprocity, the pattern of receive efficiency has an equivalent change.  So the receive efficiency also depends on the direction of the RF source.
Reciprocity implies that, just as one could increase transmit power to compensate for a less efficient transmit antenna, one could increase receiver gain to compensate for a less efficient receive antenna.  However, even if both the received signal and received noise roughly scale together, and thus can be compensated for in a receiver by gain, at some point the lower signal level from a less efficient antenna will drop below the thermal noise (and other internal and nearby RF noise sources) of the receiver front-end or LNA, and gain won't help (the S/N).
Comment: Radiation patterns of a 1/2 wave dipole and an infinitesimally short dipole are almost identical.
Answer:
Will a dipole of given length as inefficent as receiver as a transmitter?

Yes, antennas are reciprocal.
There's the common theme in ham radio that "matching your antenna for TX is more important than for RX", which is based on the fact that 1/2 of the power put out by your transmit amplifier might be very much and damage your amplifier if reflected back, but:
From a pure link perspective, it doesn't matter whether you lose x dB at the transmitter or at the receiver.
While one could reasonably give you an answer to your "what's the efficiency of a $\frac\lambda{10}$ dipole", asking that question $\frac1{1000}$ of the wavelength makes no sense, since everything is an (potentially extremely ineffective) antenna for any wavelength; if you need your antenna to be $\frac1{1000}$ of the wavelength in size, you simply don't use a dipole.
Furthermore, when you cross three orders of magnitude, typically, physical effects that play no role at one wavelength become dominant. So, the questions related to high wavelength-to-antenna-size questions can only actually be answered sensibly when you say which bands you actually aim for. The methods and elements from which you can build a 200m antenna simply aren't the same as for 10 GHz...
Answer: Although reciprocity and conjugate matching are physics facts there are certainly examples where an antenna system that is poorly matched will suffice for receive only use, ie on an HF band with high noise levels where the receiver is nowhere near it's limits of sensitivity and the receivers own noise levels are swamped by the received noise. Personally I often use nearly 20dB of attenuation in the receive path, on VHF/UHF I worry about small accidental losses in the feeder etc. The impedance of very short dipoles tends to have a very low resistive content and a huge reactive content, tricky to match with any efficiency.
Comment: Welcome to ham.stackexchange.com!


What database does Google use?

Question: Is it Oracle or MySQL or something they have built themselves?
Comment: Hey, dont bash him, I ended up here from a google search lol.
Comment: He'll use Google when he wants to find out what database stack overflow uses
Comment: Is it further irony that the top result for searching "Google's Database" on Google is now this page, on which the first comment is to use Google?
Comment: @Patrick Szalapski sounds like a stack overflow situation.
Comment: Before searching i was wondering if Google will gave me right answer but here we go :P
Comment: I'm voting to close this question as off-topic because didn't follow question guidelines
Comment: a detailed write-up on this https://www.8bitmen.com/google-database-how-do-google-services-store-petabyte-exabyte-scale-data/
Comment: Google suggests this page to check what database it uses. LOL
Comment: I believe it depends on org stru ture. Earlier I believe it used to be like a German made crochet lace with rhombus pattern. Now it could be diamond pattern. Zindagi naa milegi dobaara.
Answer: Bigtable
A Distributed Storage System for Structured Data

Bigtable is a distributed storage
  system (built by Google) for managing structured data
  that is designed to scale to a very
  large size: petabytes of data across
  thousands of commodity servers.
Many projects at Google store data in
  Bigtable, including web indexing,
  Google Earth, and Google Finance.
  These applications place very
  different demands on Bigtable, both in
  terms of data size (from URLs to web
  pages to satellite imagery) and
  latency requirements (from backend
  bulk processing to real-time data
  serving).
Despite these varied
  demands, Bigtable has successfully
  provided a flexible, high-performance
  solution for all of these Google
  products.

Some features

fast and extremely large-scale DBMS
a sparse, distributed multi-dimensional sorted map, sharing characteristics of both row-oriented and column-oriented databases.
designed to scale into the petabyte range
it works across hundreds or thousands of machines
it is easy to add more machines to the system and automatically start taking advantage of those resources without any reconfiguration
each table has multiple dimensions (one of which is a field for time, allowing versioning)
tables are optimized for GFS (Google File System) by being split into multiple tablets - segments of the table as split along a row chosen such that the tablet will be ~200 megabytes in size.

Architecture
BigTable is not a relational database. It does not support joins nor does it support rich SQL-like queries. Each table is a multidimensional sparse map. Tables consist of rows and columns, and each cell has a time stamp. There can be multiple versions of a cell with different time stamps. The time stamp allows for operations such as "select 'n' versions of this Web page" or "delete cells that are older than a specific date/time."
In order to manage the huge tables, Bigtable splits tables at row boundaries and saves them as tablets. A tablet is around 200 MB, and each machine saves about 100 tablets. This setup allows tablets from a single table to be spread among many servers. It also allows for fine-grained load balancing. If one table is receiving many queries, it can shed other tablets or move the busy table to another machine that is not so busy. Also, if a machine goes down, a tablet may be spread across many other servers so that the performance impact on any given machine is minimal.
Tables are stored as immutable SSTables and a tail of logs (one log per machine). When a machine runs out of system memory, it compresses some tablets using Google proprietary compression techniques (BMDiff and Zippy). Minor compactions involve only a few tablets, while major compactions involve the whole table system and recover hard-disk space.
The locations of Bigtable tablets are stored in cells. The lookup of any particular tablet is handled by a three-tiered system. The clients get a point to a META0 table, of which there is only one. The META0 table keeps track of many META1 tablets that contain the locations of the tablets being looked up. Both META0 and META1 make heavy use of pre-fetching and caching to minimize bottlenecks in the system.
Implementation
BigTable is built on Google File System (GFS), which is used as a backing store for log and data files. GFS provides reliable storage for SSTables, a Google-proprietary file format used to persist table data.
Another service that BigTable makes heavy use of is Chubby, a highly-available, reliable distributed lock service. Chubby allows clients to take a lock, possibly associating it with some metadata, which it can renew by sending keep alive messages back to Chubby. The locks are stored in a filesystem-like hierarchical naming structure.
There are three primary server types of interest in the Bigtable system:

Master servers: assign tablets to tablet servers, keeps track of where tablets are located and redistributes tasks as needed.
Tablet servers: handle read/write requests for tablets and split tablets when they exceed size limits (usually 100MB - 200MB). If a tablet server fails, then a 100 tablet servers each pickup 1 new tablet and the system recovers.
Lock servers: instances of the Chubby distributed lock service. Lots of actions within BigTable require acquisition of locks including opening tablets for writing, ensuring that there is no more than one active Master at a time, and access control checking.

Example from Google's research paper:

A slice of an example table that
  stores Web pages. The row name is a
  reversed URL. The contents column
  family contains the page contents, and
  the anchor column family contains the
  text of any anchors that reference the
  page. CNN's home page is referenced by
  both the Sports Illustrated and the
  MY-look home pages, so the row
  contains columns named
  anchor:cnnsi.com and
  anchor:my.look.ca. Each anchor cell
  has one version; the contents column
  has three versions, at timestamps
  t3, t5, and t6.

API
Typical operations to BigTable are creation and deletion of tables and column families, writing data and deleting columns from a row. BigTable provides this functions to application developers in an API. Transactions are supported at the row level, but not across several row keys.

Here is the link to the PDF of the research paper.
And here you can find a video showing Google's Jeff Dean in a lecture at the University of Washington, discussing the Bigtable content storage system used in Google's backend.
Comment: Now they use Spanner, the successor to BigTable
Comment: Do anyone know if it was that built from scratch or based on some product? I heard somewhere I don't remember where, that google used Oracle once, but they drop it because they need some modifications that Oracle won't do nor allow them to do. I'll try to get the link.
Comment: It's from scratch, like most of their other core competencies (web server, GFS, ...).
Comment: I was looking for info about the compression algorithms (BMDiff and Zippy) and found that now Zippy is called Snappy and it's published in Google Code: http://code.google.com/p/snappy/
Comment: So, it looks similar to nosql database such Mongodb or Marklogic.
Answer: It's something they've built themselves - it's called Bigtable.
http://en.wikipedia.org/wiki/BigTable
There is a paper by Google on the database:
http://research.google.com/archive/bigtable.html
Answer: Spanner is Google's globally distributed relational database management system (RDBMS), the successor to BigTable. Google claims it is not a pure relational system because each table must have a primary key.
Here is the link of the paper.

Spanner is Google's scalable, multi-version, globally-distributed, and
  synchronously-replicated database. It is the first system to
  distribute data at global scale and support externally-consistent
  distributed transactions. This paper describes how Spanner is
  structured, its feature set, the rationale underlying various design
  decisions, and a novel time API that exposes clock uncertainty. This
  API and its implementation are critical to supporting external
  consistency and a variety of powerful features: non-blocking reads in
  the past, lock-free read-only transactions, and atomic schema changes,
  across all of Spanner.

Another database invented by Google is Megastore. Here is the abstract:

Megastore is a storage system developed to meet the requirements of
  today's interactive online services. Megastore blends the scalability
  of a NoSQL datastore with the convenience of a traditional RDBMS in a
  novel way, and provides both strong consistency guarantees and high
  availability. We provide fully serializable ACID semantics within
  fine-grained partitions of data. This partitioning allows us to
  synchronously replicate each write across a wide area network with
  reasonable latency and support seamless failover between datacenters.
  This paper describes Megastore's semantics and replication algorithm.
  It also describes our experience supporting a wide range of Google
  production services built with Megastore.
Comment: @MikkoRantalainen You may want to check out the Apache Hadoop ecosystem or CockroachDB (though Cockroach is alpha)
Comment: Spanner has been available for everyone to use on Google Cloud since 2017: https://cloud.google.com/spanner/
Comment: It's a shame that Spanner is closed source project. According to the description, I'd love to use that for my projects, too.
Comment: Thanks, CockroachDB looks interesting. I have to test it to see what kind of performance it has. Features look like the stuff I would like to have.
Answer: As others have mentioned, Google uses a homegrown solution called BigTable and they've released a few papers describing it out into the real world.
The Apache folks have an implementation of the ideas presented in these papers called HBase. HBase is part of the larger Hadoop project which according to their site "is a software platform that lets one easily write and run applications that process vast amounts of data." Some of the benchmarks are quite impressive. Their site is at http://hadoop.apache.org.
Comment: Link is 404 not found
Answer: Although Google uses BigTable for all their main applications, they also use MySQL for other (perhaps minor) apps.
Comment: @smoothdeveloper's link is dead; read an archived copy here: http://web.archive.org/web/20071102233627/http://xooglers.blogspot.com/2005/12/lets-get-real-database.html
Comment: however Google is no longer in the list of MySQL Customers...
Answer: And it's maybe also handy to know that BigTable is not a relational database (like MySQL) but a huge (distributed) hash table which has very different characteristics. You can play around with (a limited version) of BigTable yourself on the Google AppEngine platform.
Next to Hadoop mentioned above there are many other implementations that try to solve the same problems as BigTable (scalability, availability). I saw a nice blog post yesterday listing most of them here.
Answer: Google primarily uses Bigtable.
Bigtable is a distributed storage system for managing structured data that is designed to scale to a very large size.
For more information, download the document from here.
Google also uses Oracle and MySQL databases for some of their applications.
Any more information you can add is highly appreciated.
Comment: `Google also use Oracle` - reference needed.
Comment: @user https://cloud.google.com/sql/docs ? If developers can use MySQL, Google must, at least, have created a "database translator" with MySQL and Bigtable.
Answer: Google services have a polyglot persistence architecture. BigTable is leveraged by most of its services like YouTube, Google Search, Google Analytics etc. The search service initially used MapReduce for its indexing infrastructure but later transitioned to BigTable during the Caffeine release.
Google Cloud datastore has over 100 applications in production at Google both facing internal and external users. Applications like Gmail, Picasa, Google Calendar, Android Market & AppEngine use Cloud Datastore & Megastore.
Google Trends use MillWheel for stream processing. Google Ads initially used MySQL later migrated to F1 DB - a custom written distributed relational database. Youtube uses MySQL with Vitess. Google stores exabytes of data across the commodity servers with the help of the Google File System.
Source: Google Databases: How Do Google Services Store Petabyte-Exabyte Scale Data?
YouTube Database – How Does It Store So Many Videos Without Running Out Of Storage Space?

What database does Google use?


Is the equilibrium temperature of a black body higher than other objects?

Question: Suppose we place a black body and an object of lower emissivity, both of the same shape, into an evacuated glass contained, and we place that container in sun light. After time, if both reach thermal equilibrium (either effect the other), does the black body have a higher temperature at its equilibrium? Why or why not?
Comment: When you expose an object to sun light, it is *not* in thermal equilibrium and will not be until the object's surroundings are at the same temperature as the sun. The assumption that the black body is in equilibrium is an error which leads to your confusion.
Comment: @DanielSank     I guess I was assuming that the surrounding of the glass container also wouldn't effect the two object. If there is no air nor any other surrounding to the two object, then its thermal equilibrium will only relate to itself and the incoming radiations.
Comment: You already accepted John Rennie's answer, so I guess you understand what I mean now :D
Answer: Your objects will reach equilibrium when the energy absorbed from the sunlight is equal to the energy radiated by the body.
The energy radiated will be given by the Stefan-Boltzmann law:
$$ J_\text{out} = Ae\sigma T^4 $$
where $A$ is the surface area of the object and $e$ is the emissivity.
Now let $I$ be the energy per unit area in the sunlight incident on the object, so the total energy will be $W = aI$ where $a$ is the cross sectional area of the object. The proportion of the energy reflected is $rW$, where $r$ is the reflectivity, so the energy absorbed is:
$$ J_\text{in} = W - rW = (1-r)W = (1-r)aI $$
The reflectivity is related to the emissivity by $e+r=1$, which means $1-r=e$ and the equation simplifies to:
$$ J_\text{in} = eaI $$
At equilibrium we set $J_\text{in} = J_\text{out}$ to get:
$$ eaI = Ae\sigma T^4 $$
and rearranging gives:
$$ T = \left(\frac{aI}{A\sigma}\right)^\frac{1}{4} $$
So at equilibrium the temperature is not related to the emissivity. A higher emissivity means the body loses more energy due to black body radiation, but because higher emissivity means lower reflectivity it means the object absorbs more of the sunlight falling on it. The two effects balance out.
Note that although the emissivity does not affect the equilibrium temperature it does affect the speed that the object attains equilibrium. The higher the emissivity the faster the object will reach equilibrium. So while your two objects are warming up they will warm up at different rates and therefore will temporarily have different temperatures.
Comment: Thank you @John Rennie. Your answer is very thorough and answers my question. There is a few details I am uncertain of. Is J(out) the power of its emission of radiation? And should [I] be the power per unit area of the sun's incident ray on the object? Thanks
Comment: @A.Jiao: yes, $J_\text{out}$ is the total power emitted as black body radiation. $I$ is indeed the power per unit area of the sunlight.
Answer: The temperature of blackbody could vary from 0 to $\infty$ (take our Sun and a much larger star as an example; you can assume both as a radiating blackbody but their temperatures are different). Based on this temperature, the spectrum they emit is different (see the figure).

In your question the object's temperature has to depend on the source that is heating it up (here, the sun); the spectrum that this blackbody radiates is the same as the spectrum of sun, assuming a perfect blackbody.
Then if both your objects are exactly the same (mass, shape and material) their temperature also has to be the same. However, the difference in emissivity means difference in absorption as well, so, they have to be different in temperature and this does not depend on whether they are blackbody or not.


Unplugged Trezor when incoming transaction was unconfirmed

Question: I transferred some bitcoins from one of my online wallet to my Trezor. When the transaction is in unconfirmed mode I unplugged my Trezor. Then after I plugin my Trezor that transaction somehow did not show up on my Trezor. Now what should I do?
Answer: If the transaction has confirmed, then there is nothing that you need to do. Your Trezor device does not actually receive the transaction nor does it need to. All that matters is that the wallet software that you are using knows about the transaction, and if the transaction has confirmed, it is trivial for it to find out about the transaction. Check the wallet software that you are using and make sure that you see the transaction there.
Comment: Thanks for the reply.  The transaction has confirmed on blockchain finally, but somehow my trezor seem have lost the receiving address and this transaction as well. By the way how to check the wallet software that I am using?
Comment: Your Trezor doesn't actually store any transactions (especially ones you receive), and may not even store addresses either. You won't see anything about your transactions or your addresses when you plug in a Trezor to your computer because a) you need software that is running to interact with it and b) the Trezor can't just ask your computer for any data nor does it want to. The wallet software that you are using is whatever software you are using on your computer that lets you get addresses and make transactions. This could be the My Trezor webwallet or a desktop wallet like Electrum.
Comment: Thanks. I use Trezor webwallet, but I does not see the blockchain confirmed transaction. What should I do?
Comment: Contact Trezor's support as they are the only ones that can do anything about their own web wallet service.
Comment: To sum it up are you saying: The address that receives the private key is not stored on the Trezor wallet. But the Trezor wallet is required to access that address?
Comment: Addresses do not receive private keys. Addresses are directly derived from private keys. The private keys are stored in the trezor and nothing more.
Answer: Bottom line on this-- Trezor only stores your private keys, not transaction information. To isolate whether the problem is your web wallet or something else, you can just open any other wallet software that can support the Trezor and see if the transaction shows there.
For example, try installing Exodus, Electrum, or even Trezor suite. Any of those applications can be installed on your computer and can work with Trezor Model T (not sure what works with the cheaper model).
Once you have opened a different wallet and your Trezor is connected and signed in with your PIN, the wallet software will extract transaction information from the blockchain associated with the private keys stored on the Trezor.
One other thing I've seen happen that can be confusing is, you may have two accounts with the same name, like there could be a Bitcoin #1 that is a Native Segwit (Bech32) wallet and then also a regular Segwit P2SH wallet with the same name Bitcoin #1. If you happen to have the Bech32 wallet selected, but your bitcoins are in the P2SH wallet, it'll show 0 bitcoins. Click on the P2SH wallet, and you will see your coins. Happened to me ;)


Do SN2 reactions always invert absolute configuration?

Question: I know that an $\mathrm{S_N2}$ reaction proceeds through complete inversion of configuration, but is it necessary that the absolute configuration (R/S) of the chiral centre change after an $\mathrm{S_N2}$ attack ?
Comment: No, it is not.Why do you think it should?
Comment: Short answer: No
Answer: For the ease of thinking about this, let's imagine $\mathrm{S_N2}$ attack of $\ce{CN-}$ on bromochlorofluoroiodomethane, where iodide is being displaced.

Absolute stereochemistry is retained in this case because the highest priority substituent is becoming the lowest priority substituent. If you were to find the absolute stereochemistry of $\ce{2 ->3->4}$ in (R)-bromochlorofluoroiodomethane, which becomes $\ce{1->2->3}$ after attack, you would see that it is S and after attack becomes R. You can see that here:
Answer: The assigned configuration is based on the substituents at the stereocenter.  If what is entering has a different prority than what is leaving relative to the other groups, there may be no change in R/S.
For example:
The SN2 reaction of cyanide with MeCClHCH(SEt)2; in this case S alkyl chloride-->S nitrile (or R-->R) because the -CH(SEt)2 substituent is higher priority than -CN. The -Cl was 1st priority in the starting material.
Answer: To determine whether the $S_N2$ substitution inverts $R/S$ configuration, just do some simple arithmetic.
Let $Nu$ be the nucleophile, $L$ be the leaving group, and $R_1,R_2, R_3$ be the remaining groups.  $L$ will be higher in priority than 0, 1, 2, or 3 of the groups, and similarly for $Nu$.  You work out the difference between the two correct numbers for your specific reaction.  If it's even, you invert absolute configuration, if it's odd, you don't.  For example, in @Ringo's example above the leaving group, iodide, is higher than 3 of the retained groups but cyanide is higher than 0.  These numbers have an odd difference --> absolute configuration is retained.


Is a man obligated to seek a medical remedy to fulfill onah?

Question: If a husband is physically incapable or performing onah (the obligation for a husband to sexually satisfy his wife as outlined in Shulchan Aruch Even Ha'Ezer 76)due to an inability to have an erection is that husband obligated to purchase medicine or have a surgery which will remove his inability?
Related
Comment: Under the assumption that the husband and wife didn't talk about this ahead of time and therefore the onah clause is still included in the Kesubah?
Comment: @DonielF yes, that's correct
Comment: @rikitikitembo Your answer to the previous comment seems to imply that this medical issue was known prior to marriage, and the husband hid it from his future wife. Is that the scenario you are talking about, or are you referring to where someone lost the ability to fulfill Onah at a later time after the couple was already married? Whichever one you're asking should probably be edited in to the question, as I can imagine the rulings would be wildly different.
Comment: @Salmononius2 sorry if the comment was misleading i meant that there was nothing previous to the marriage which should effect things during the marriage. your description of the scenario first appearing during the marriage is in line with my intent
Comment: My follow-up question was going to be that if it was before marriage, I wonder if the wife can claim mekach ta'us and annul the marriage retroactively, like he could if a medical condition was found in her. But as per your previous comment, that seems to be irrelevant to this case. In any event, the wife *should* forego her onah, but I'm not sure that he can force her to do so.
Comment: @DonielF what is the source that a husband can get a marriage annuled if his wife had a (unrevealed) medical condition, (I only know Sources regarding besula, mumim and vows)
Comment: @hazoriz I believe it's toward the end of Kesubos
Comment: @DonielF I whould appreciate it is you find it https://judaism.stackexchange.com/q/84875/5120
Answer: The Mahari'k in shoresh 10' says that the chiuv onah is considered davar she'bemomon meaing a monetary issue.Therefore a person must give all he has got to fulfill it.
We see that when paying a debt the bais din takes away all  but a few things.Which tells us that more than a chomesh which is required for an Assay is required of someone looking to pay his debts.Therefore that which shall be an excuse in a regular mitvah shall not be sufficient in a monetary issue.
According to this certainly the husband is obligated to treat his condition.However even according to the shulchan aruch that it not considered monetary which is why he can not make a condition with a wife to be exempt of this obligation according to the shulchan aruch,nevertheless since it is interpersonal it will require him to do his utmost to fulfill it and act on it as though it were monetary.
In conclusion he is obligated to heal himself of this shortcoming for his wife's sake.
In regard to whether or not the husband may rely on the forgiving of his wife and not treat his deficiency,or is it a chesed on the wife's part to be forgiving in this area.
The Gemarah in Yevomot 109'b' relay's an episode where Chonyov the son of Shimon Ha'Tsaddik was offered the Kehunah Gedolah after the passing of his father. He declined as respect to his older brother, letting him take it for himself. After a while jealousy took hold of him, which led him to disgrace his brother thereby causing himself to have to run for his life to Egypt and build what became known as Bais Chonyov to serve as his Bais Hamikdash.
The depth in this story is as,cited in that Gemarah,Rav Yehohuah Ben Peracyah said "before i became Nassi i would say that if someone were to push me to accept such a position i shall give him over to the lions,and now after being Nassi if someone should tell me to step off i would spill burning hot water on him".
This meaning, that when giving up an opportunity so tempting as this,one shall be sure that his heart is fully compliant with it.For when the jealousy kicks in  later it shall be it shall be in great measures,and will leave you in a state of inconsolable regret.
Now,in our case,do we know that the wife is all forgiving and not suffering in silence? Is she really complacent being robbed of her basic rights?
Therefore i conclude that the husband should not rely on his wife's forgiveness and should undoubtfully treat the condition and give her that which she deserves.
Comment: "In regard to whether or not the husband may rely on the forgiving of his wife" the question never asked that.
Answer: From the simple reading of the Shulchan Aruch E"H 76.11 it seems
That medical problems are an excuse, not to fullfill a man's marital obligation, but it works only up to 6 months,
After 6 months the wife has the right to demand a divorce (and since it is his fault (even if not directly since only the woman has the claim of your field got inundated) he is obligated to give the whole kesuba), or forgive her husbands obligation.
(The commentators (on that sif)  say:)
But if the doctors claim it will get better in a specific time even after 6 months then she will have to wait until it happens
So it seems in your case you can not take the medication/operation  up to 6 months.
after that if you did not take them your wife can demand a divorce

PS That was the law but it seems to be good behavior to heal yourself asap, since peace in your house is a big mitzvah , and your organ is called the peace maker in your house (shabos 152a)
the Lubavicher Rebbe who would be the last person to tell someone to give up , advised at least 3 times for men to give in to their wife's demands (with dignity (becouse they are not woman (weak minded, easaly offended) so it is they who are the ones to give in))
Igros 1141 , 1154 and 2454

PPS it is possible that I the wife forgives the husband obligation towerds her she is also fulling the mitzvah of making peace between a husband and wife

PPPS
I guess this halacha in the Rambam (Avodim End) can be applied here by both parties

And whoever shows mercy to others will have mercy shown to him, as implied by Deuteronomy 13:18: "He will show you mercy, and be merciful upon you and multiply you."


Is 512 bits a more secure hashing than 256 bits?

Question: I know that 512 bit hashing is more secure, but I don't really know why. I hope someone can help me to better understand it in more detail.
Comment: It's not universally true. For example, SHA-512 is less secure than the 256-bit "SHA-512/256" (which is basically SHA-512 with a different initialization vector, then truncated to 256 bits). This is because SHA-512 suffers from length extension attacks whereas "SHA-512/256" does not.
Comment: academically speaking, yes 512 is more secure than 256. but realistically speaking, they're both equally strong. (at least as far as SHA2/SHA3 is concerned)
Answer: When there is no known weakness in the hash function we talk about their generic1 resistances

Pre-image resistant: given a hash value $h$ find a message $m$ such that $h=Hash(m)$. E.g., consider storing the hashes of passwords on the server. An attacker will try to find a valid password to your account.

Second Pre-image resistant: given a message $m_1$ is should be computationally infeasible to find another message $m_2$ such that $m_1 \neq m_2$ and $Hash(m_1)=Hash(m_2)$, e.g., producing a forgery of a given message.

Collision resistance : it is hard to find two distinct inputs, $a$ and $b$, that hash to the same output $a$ and $b$, i.e., $H(a)= H(b)$ and $a \neq b.$

A hash function with output size $n$ is expected to have $\mathcal{O}(2^n)$ pre-image resistance and secondary image resistance and $\mathcal{O}(\sqrt{2^n)} = \mathcal{O}(2^{n/2})$ collision resisance. The collision resistance is less due to the birthday paradox (attack).
If we plug 256 and 512 into those equations you will see that

256 has $\mathcal{O}(2^{256})$ pre and secondary and $\mathcal{O}(2^{128})$ collision resistance, whereas
512 has $\mathcal{O}(2^{512})$ pre and secondary and $\mathcal{O}(2^{256})$ collision resistances.

As a result, as long as there is no specific weakness in the (unspecified) hash function the larger the output the better the resistance they will have.
When the hash function is specified then one can talk about their resistance in all directions. For example;

Standard Merkle–Damgård constructions (MD) (MD5, SHA-1, SHA-2) are vulnerable to length extension attacks, however, sponge constructions (SHA3) and HAIFA based (e.g. BLAKE(2)) are not. Note that after SHA3, there are variants of SHA-2 that have resistance against length extension attack like SHA512-256,

Herding attack for MD constructions is introduced by Kelsey and Kohno in 2005 and applied to MD5 Finding Preimages in Full MD5 Faster Than Exhaustive Search with Chosen Target Forced Prefix Pre-image resistance

Chosen-prefix collision on SHA-1 is a Shambles - First Chosen-Prefix Collision on SHA-1 and Application to the PGP Web of Trust, 2020. List of attacks on SHA-1 can be found 1,2

The relations of the generic resistances are, in simple terms,

Collision resistance implies 2nd-preimage resistance of hash functions, see a detailed work on our site

2nd-preimage resistance implies preimage resistance, see the proof on this site.

The formal definitions of the resistance and modern cryptographic deal of the above facts and more provided in the novel article; Cryptographic Hash-Function Basics: Definitions, Implications, and Separations for Preimage Resistance, Second-Preimage Resistance, and Collision Resistance by P. Rogaway and T. Shrimpton on 2009.

1 The term generic is used when a resistance ( or the attacks) applies all of the hash functions. This term similarly used in other cryptographic contexts, too.
Comment: So @kelalaka, is the term generic applies to all hash functions because it is referring to the construction of the function itself?
Comment: Yes, if you look at their definitions you will see an arbitrary function. When one defines the function the one can talk deaper.
Answer: A n-bit hash can be brute forced $O(2^n)$ operations.  If you run the numbers, you find that a 256-bit hash is completely immune to brute force attacks.  $2^{256}$ is so large that it would literally take a good chunk of the available energy in our galaxy to break it.  So in that sense, they are both "completely secure against brute force."
However, we do find attacks against hashes.  These are not brute force attacks, but rather leveraging mathematical quirks about the hash to do the attack with fewer operations than the brute force attack.  We can measure the effectiveness of these things in terms of the original brute force attack.  If I find an attack on a 256-bit hash which can be done in $O^{192}$ operations, then I have reduced the strength of the hash by $256-192=64$ bits.
Historically, we find that most hashes which survive the initial cryptonanalysis that they receive when they are introduced tend to fall apart gradually.  Its rare that we suddenly find a new angle which lets us drop 100 or 200 bits off of the strength of the hash in one big advancement.  Typically we see mathematicians take nibbles off of the hash strength, slowly weaning it down.
Past performance does not predict future behaviors.  Any given hash could indeed be suddenly broken at any point in time.  However, as a general, we find that isn't how it works.
So how do you value this?  Well, we can look at computational resources available.  The Folding@HOME response to COVID-19 was on the order of $2.4\cdot10^{18}$ operations per second, or $7.5\cdot10^{25} \approx 2^{86} $ operations per year.  The speed of Fugaku, a top Japanese super computer, is on a similar scale.  So once the number of operations required to break the hash gets to that level, it becomes feasible to break the hash in a year.  Using a 512 bit hash provides some additional buffer before it reaches this point.
I'm intentionally ignoring details like birthday attacks, which are important, but do not change the fundamental way the risks are analyzed.
So in general, you can expect a 512-bit hash to remain safe against attacks longer.  However, you cannot assume it.  There's nothing about a 512-bit hash which is fundamentally safer than a 256-bit hash.  It just has a bit more buffer against the historical trends in cryptography.  It's the quality of the math inside the hash which is more important.  As a reduction to absurdity: I can always make a 512-bit hash by taking a 256-bit hash and doubling each bit.  Of course, people will notice rather quickly that there's an attack against it which reduces the strength of my hash by 256-bits!
Comment: Thank you so much you provided me with extra information which is very valuable to me.


Mac Automator to "Get Info" on sing in iTunes and then press next until the last song

Question: Without getting into details, I am updating ID3 tags outside of iTunes and would like to import all of that data into iTunes. Before iTunes 10 I was able to select all songs and click "Get Info" - this would automatically pull all the updated ID3 tags for every song. It seems like the only way to do that now is to either play each song individually OR "Get Info" and continue pressing "Next" for every single song. I want to setup an action in Automator to do this for me. I have never used it before and am having some trouble with it. I would appreciate if somebody could give me a hand setting this up. Thank you!!
Answer: Found exactly what I needed here: http://marv.kordix.com/archives/000860.html It's an Applescript called "Refresh Selected Tags". You select whatever songs you want and click "Refresh Selected Tags" - simple as that!
Answer: how about trying this with a few songs first:
select the songs, right click and select 'convert id3 tags'. select the most recent version.
not sure if that will work.
otherwise make a new automator workflow, press the record button at the top, switch to itunes press command+i (get info) then command+n (next button), then stop the workflow recording.
you'll see automator made a new action called 'watch me do'. test it out. if this works, try holding option and dragging the command+n part of the action underneath it to duplicate it. you can then select both and duplicate those, then duplicate the 4 you have and so on. you should have a long list of command+n. then, in itunes select the song you want to start from and then press play in automator.


Are there any airlines that offer nonstop flights from Ottawa or Montreal to Central America?

Question: I am looking to get to Costa Rica or a country close by such as Nicaragua or Guatemala, but I need a direct flight because I cannot enter the US.
Comment: A hint to use is to avoid US based airlines (which will have a US layover).
Comment: What research have you attempted thus far? For the most obvious, have you consulted the flight schedules of Air Canada?
Answer: I think this sort of question may have been asked previously, but I can't find it just now.
A good way to solve this problem is to use a search engine like Kayak which lets you filter by layover airport.  If you search for a flight from Montreal (YUL) to San José (SJO, not SJC), there is a "layover airport" dropdown on the left panel, where you can uncheck layover airports that you want to avoid.  Unchecking all US airports leaves, among other options, flying Copa with a connection in Panama City, or Aeroméxico with a connection in Mexico City.  There are further options available with an extra connection in Toronto.
Comment: Wow .. I don't know if to laugh or just cry that such is possible today @pnuts.
Comment: @BurhanKhalid: There's lots of stories like that.  A quick Google turned up Grenada vs Granada; Birmingham (Alamaba, USA) vs Birmingham (UK); Sydney (Nova Scotia, Canada) vs Sydney (Australia).  I would guess London (Ontario, Canada) is also a common source of confusion.
Answer: As Nate explained (+1), many search engines do let you filter flights by layover and exclude specific airports based on your needs.
Another way to find flights that do not go through the US is to look up Wikipedia articles or official websites from the main airports in Costa Rica and start from there. Thus, you can see that Air Canada Rouge or Air Transat have direct flights from Canada to Juan Santamaría International Airport. There are also various flights to destinations in Latin America like Mexico that could be used as a layover.


Did Jyn know her father worked for the Empire before the Rebellion told her so?

Question: Did Jyn really assume her father was dead/had been killed on Lah'mu, or had she actually heard the rumors saying her father worked for the Empire (the same rumors that caused Saw to abandon her)?
Answer:
"Any idea where he's been all that time?".
  "I'd like to think he's dead " Jyn answered "makes things easier." - Rogue One novelization, Ch. 2

Part of her did think he might be dead, because when they tell her the pilot has a message from him hers thoughts go into turmoil when she realizes they are telling the truth.

My father is alive. My father is a traitor. My father is building a weapon to destroy worlds.

Based on this I think it is safe to say she assumed her father was probably dead, better that than a turncoat.
Answer: She's certainly heard the rumours...
There's discussion of this in the 2017 novel Rebel Rising, which follows Jyn between the Rogue One prologue and the film proper. For example, it establishes early that Jyn knew (or, at least, believed) that her father had survived Lah'mu:

Jyn gasped.
Saw glanced where she was looking and nodded grimly. A Star Destroyer hung in the blackness of space, the sun illuminating the underbelly of the ship.
They'd sent a Star Destroyer for her father.
Papa's on that ship, Jyn realized, her eyes widening. He was somewhere, somewhere there, just out of reach but so close.
Rebel Rising Chapter 2

More to the point, the novel reveals that Saw told Jyn about her father's supposed allegiances not long after picking her up:

"Galen Erso is working alongside Orson Krennic." Saw spoke in clear tones, enunciating each word, as if he knew the truth would cut her and it would be cleaner if he used a sharp razor rather than a dull blade. "Your father is working - knowingly - with the Empire. He reports directly to Imperial forces. He has made it entirely clear to my sources that he has chosen a side, and that side is the Empire."
Rebel Rising Chapter 5

This scene takes place at least a month after Jyn leaves Lah'mu, but likely not much more than that.
...but it's not clear whether she believes he's dead
There's evidence in the narration throughout the rest of the book that she never really suspects Galen's death; in fact, there's a point, when she's around 17 or 18 (so three or four years before Rogue One), where she briefly considers finding him, and living in the lap of Imperial luxury:

What would happen if she went back to her father? The Empire had killed her mother but just taken her father. He was their golden boy, and he seemed to relish that status. Could she be afforded the same luxuries he had been? Another apartment on Coruscant, another Mac-Vee, another chance?
Rebel Rising Chapter 37

In fact, the epilogue of the novel implies that Jyn is lying about believing her father to be dead:

"That's your given name, is it not? Jyn Erso? Daughter of Galen Erso." He paused. "A known Imperial collaborator in weapons development."
"I have no father," Jyn said, her words strong with the conviction she put behind them.
Rebel Rising Epilogue

However, this becomes inconsistent with Rogue One (both the film and the novelization) and the Visual Guide cited by Valorum, so it's hard to say which explanation is canon.
Comment: A good find, albeit one that conflicts with the Visual Guide. You have my +1
Comment: @Valorum Okay yeah, the novel pretty severely disagrees with the visual guide on this. So, philosophical question time: in a canon-off between a licensed writer and Pablo Hidalgo, [who wins](https://en.wikipedia.org/wiki/Irresistible_force_paradox)?
Comment: I suppose you could argue that she knew he was alive and captured but imagined that he must have died in the intervening years
Comment: @Valorum Doesn't seem to be borne out by later parts of the book; there's a point when she's about 18 where she plays with the idea of seeking him out on Coruscant, for example. Also her entire motivation for helping the Alliance is retconned (it's about believing in hope in the novel, not really about finding her father)
Answer: The film's Ultimate Visual Guide advises us that Jyn is of the opinion that her father is almost certainly dead.

For Jyn, it's the swapping of one prison cell for another. She cares
not for the cause of the Rebel Alliance, and being briefed by their
command while still in binders does little to sway her. Until, that
is, she hears about her father, a man she had decided had died years
ago.
Star Wars: Rogue One: The Ultimate Visual Guide
Comment: "she had decided" - This could be interpreted as her merely considering him essentially dead in order to avoid complications without truly believing it.
Comment: @RogueJedi - Indeed. Or simply wanting it to be the case.


All Wordpress scheduled posts are being published immediately

Question: I am having a problem when creating scheduled posts. I create the posts as normal, click edit, set a scheduled time and click ok then the shedual button. Soon as i do this i check the website and the post has been published immediately. I looked back in the view all posts page and the post says its still scheduled. It was working fine for months but suddenly this is occurring. Really need this sorting asap! cheers
Comment: You can view scheduled posts as if they were public if you're logged in, but they won't appear in archives. Where are you seeing the published post? On the main blog page?
Comment: The site is just one page. So i think it must be. Not sure if its anything to do with being logged in. I can view the site from another computer and the post is still published.
Comment: Try installing a plugin called [WP-Crontrol](https://wordpress.org/plugins/wp-crontrol/) which basically will help you debug WP-Cron and add more details to your question.
Comment: I installed it and i can see the cron event for the scheduled post. The date is correct and the post still says its scheduled on the posts page. But the post is still viewable on the website.
Answer: I'd check to make sure that the scheduled time is actually in the future - date and time. And check the time offset settings on your site are set to the proper time zone.
Comment: I set the date to a month from the current time. I have already tried changing my time zone from UTC + 0 to London where i live. It was working on UTC+0  and just suddenly stopped. I haven't changed anything recently apart from install the zoast seo plugin and a minify plugin. Surley they cant be connected to this?
Comment: It also does it on my local host as well. Really strange this.
Answer: Ok i managed to fix it. I added <code>'post_status' => 'publish'</code> to my WP-Query args in the loop and it seems to have solved it. Really bizarre that its been working for months without this argument. Wonder if one of you clever people has a clue to whats happening? cos im baffled!


Pagination for a cpt filtered with a category

Question: I was tasked with creating a posts aggregator that fits seamlessly into the category nav-bar. For this to work, I could not use the category-list.php that exists, for it is full of workarounds and exceptions and i can barely make sense of it.
So I went simple and created a CPT (mensuels) to create archives (month/year) of posts based on their date and tags. I added the taxonomies category and post_tag  and categorize them as 'themes-mensuels' so that I can include them as part of the category nav-bar in the site header.
I created a file called category-themes-mensuels.php that displays the list of archives and a file called single-mensuels.php that displays the chosen month (one cpt) and lists the articles it aggregated.
The CPT has posts basics plus 2 fields: year and month. When I create one,
I fill those in, add a month-year title, check the 'themes-mensuels' category, then choose whatever posts tags came up during that month. I can then add content to comment on such or such particular subject I am filtering for.
I did not create specific pages in the wordpress theme.
This works well:

hovering over the bar shows 4 latests "themes" just like they were
posts in other categories
clicking the tab takes me to the category page and lists all the themes. I had to list their articles below each item (like another
CPT on the site) and that works too.
choosing one takes me to the single-mensuels page (blog/mensuels/month-year) where there is a bit of a intro showing thumbnail/excerpt/content then lists each posts as per the filter.
each article is shown in single.php as expected.

But pagination does not work for either page.
I list the custom-post-type list using the category tag as a category-$slug page.
Then I list ONE theme using its single-$posttype page.
The paginate_links() code does its job: the links are there.
But the query_var(paged) is not read, so the category page goes to a 404,
and the single-mensuels page (for one theme) just returns the first page of articles.
I looked at other cpt pages on the site and created wp pages for my needs, but pagination was the only thing that worked: category page did not link to category nav-bar (not the "right" way. Though that page showed all the items), and single-mensuels page ignored the new wp_query that was coded in, showing ALL POSTS EVER. So I am not using those.
I tried quite a few things over the past week : renaming the category, changing the number of posts read and removing posts_per_page from the new wp_queries, renaming the file to archive-themes-mensuels.php (and back again)
I save the permalink structure in the settings tab when I change something in the functions.php file.
I cannot change the permalink structure of my site and it uses the word "categorie" as a prefix for the categories.
I am so close to getting this to work, but something in the WordPress logic escapes me and it seems no one has attempted this.
Edit:
I realized I could link the nav-bar category tab-link to an archive page for the cpt rather than mistreat the category.
So I dutifully reproduced the formatting code for the category (getting links for each theme-post), stuck it in the bar, and directed the tab-link to a renamed category-themes-mensuel.php to archive-mensuels.php.
Now I have pagination for the cpt archive page and better understanding of the template hierarchy.
That's 1/2 pagination.
Edit 2:
I DID try several combinations of the global $tempquery = $wp_query switcheroo hack. It didn't work.
Part of the challenge is that there are 3 loops going on in that page, more if you count the header. My custom post type is only just a placeholder for the keys that will be used to query for the posts I really want. My "single-$posttype.php" page is the starting point for another loop once that month's theme comment is displayed. Every article page on the site has a footer containing 3 related articles filtered by tags.
I finally applied the
<code>    /* pagination fix for custom loops on pages*/
add_filter('redirect_canonical', 'custom_disable_redirect_canonical');
function custom_disable_redirect_canonical($redirect_url){
    if(is_paged() && is_singular('mensuels')) $redirect_url = false;
return $redirect_url;
}
</code>
in functions.php.
I was hesitant until I saw I could specify the cpt i wanted.
Well, it almost works.

If I start from the 1st page, I get nowhere.
If I put /page/2 in the url, I get page 2 but can't navigate.
If I put in page/3 I get the proper page AND then can navigate back and forth.

I am le dumbfound.
Answer: Screw using a category. I manually added the tab to the nav-list and disguised it as a category. The posts are filtered by a "special" tag that doesn't need to show up anywhere else. The custom post type looks for that tag and has fields for month and year. Archive-* and single-* template pages display according to plan. Everything works now. Thank you very much to everyone who helped out.


What does "Piggy" mean in this Schematic?

Question:
What does the word "Piggy" mean in this schematic diagram?
I found some sections of a schematic where a part is denoted as "Piggy".
What does it mean?
Comment: I've seen "Fred, Jim and Sheila" but never a "Piggy" before... (for old timers in the UK)
Comment: @BrianDrummond I was always a bigger fan of Fat Agnus, Denise, and Paula.
Comment: @Polynomial : Never ran across them. By the time they came along I was working with a chip called "So long and thanks for all the fish", being the fourth member of a trilogy.
Answer: The block might be "piggy backed".
A piggyback board is an extension or a daughter board.
Thus in this case it means that the V35/X21 module is located on a daughter board.
Here an example:
Answer: Piggy or piggy board usually refers to devices (or small boards) which are plugged / soldered onto larger boards.
For example, bluetooth uses 2.4GHz, which is really sophisticated stuff and could easily need more design work that the entire rest of the board. So there are small bluetooth modules of the size of a post stamp available, which can be soldered onto your board. They need some power and offer a serial interface, which is quite handy.
I have no idea what exactly this device on your schematic is, but the word piggy, the red box (and may be the word serial) makes me guess that it's something like this.
Answer: I believe the "Piggy" is referring to "Piggyback board" or sometimes called a daughter board. What I think the schematic means is that the serial interface outlined in the red dashes is part of a piggyback board connected to the main circuit.
Answer: Most likely this refers to and is derived from the expression "piggy back". Meaning of course to ride on the pigs back. In more modern terms you may give a child a "piggy back" ride whereby they climb on your back and get a ride.
In the context of a circuit board environment a piggy back component or module would be one that mounts onto the main board and provides some function when installed. You could even think of that component as "taking a ride there".
There are even some instances in electronics where some components may get installed by reworking the board after it has been built. Some times the reworked components need to be mounted on top of other component in order to gain access to solder connection points. Such components are commonly referred to as being mounted "piggy back" on the other component. A simple example would be a case where it was found that some IC was missing its decoupling capacitor and the fix is to piggy back the capacitor on top the IC chip and solder the leads to the IC chip leads.
Answer: Not all designers are deadly serious, some are quite whimsical when they name signals. In a big commercial project, it's one of the jobs of the project leader, once he's finished smiling at the joke, to make sure names like these don't get out in the public literature. No one wants to keep explaining, or apologising for, the joke.
As the block is labelled 'Serial Int', which is probably Serial Interface, I suspect the allusion is either to 'Squeak Piggy, Squeak', or to the general observation that pigs squeal when poked. I think it's a signal that makes the downstream controller do something.
Comment: While this may not be accurate to OP's situation, it is realistic.


INSULATING A STUCCO SHED

Question: I live in an high desert where it gets very cold, -20  in the winter,with 95 degree days in the summer. I have a beverage cooler in a building with a new shed attached to it to protect the compressor. The shed is stuccoed with a metal roof. I have a vent in the upper portion of the shed, no windows. I will install an exhaust fan in the spring, but now I need to insulate the shed for winter. What is the best material to use and who do I avoid mold or condensation issues?
Comment: Hello, and welcome to Stack Exchange. Some pictures of the cooler and its building would be helpful.
Answer: You don't need to insulate this shed. Also, it's a bad idea to have the compressor in a shed in the first place. Compressors are designed to be outdoors because they need to reject heat. In sunny 95f summer weather, your "insulated shed" is really an oven. In winter, insulating a building will not actually raise interior temperatures unless there is a source of heat on the inside (insulation slows heat movement, but it does not generate heat where none exists). High deserts are sunny, but you mentioned that your shed has no windows to allow sunlight in. So insulating the shed will not actually meaningfully raise the temperatures that the compressor is exposed to.
Next, you will not be able to prevent condensation in -20f weather. However at that temperature the moisture-holding capacity of the air is incredibly low--especially in a high-altitude desert (I live in one too; I know what it's like). Despite this, if there is a source of moisture, it will condense somewhere; the only way around that is to keep all condensation-forming surfaces above the dew point which is impossible in the winter without a source of heat, irrespective of how much insulation you have.
Finally, your concern about mold is misplaced. Mold won't grow in -20f weather. The time to worry is during the summer and the swing seasons, but during those times of year, the problem won't be condensation because you generally won't have interior surfaces below the dew point. The real cause of mold is not condensation but rather water leaks from a faulty roof or bad flashing somewhere. Monsoon rains can be brutal so the roof especially needs to be leak-proof. The intense sun in your climate will do a great job of killing mold if you let it!
Here's what I would do: remove the shed's walls and make your shed essentially just a roof to protect the compressor from rain and snow. This will ensure enough airflow around the unit in summer to do its job and allow the sun to warm it in winter and kill any mold that grows as a result of monsoon rains.
Answer: I would go with styrofoam. You can get it in sheets at most local hardware stores like Lowes and Home Depot. You can also get it sprayed on if you are looking to hire a company. Plus it is extremely easy to work with.
This is also how people are insulating their garages by adding them to the aluminum doors.
Styrofoam (sheathing) is commonly used under stucco and styrofoam also breathes well and tends to be mold free. I have never seen a styrofoam cup with mold. :P
Here is a link to sheathing at Home Depot
Comment: This is not advisable. Styrofoam is flammable and starts to melt at 165f; any building insulated like that (*especially* a garage) without covering it in fire-rated drywall afterwards is a firetrap. Insulating the OP's shed like this is a bad idea for multiple additional reasons, too (explained in my answer)
Comment: There's [worse things](http://diy.stackexchange.com/questions/68912/is-it-dangerous-to-use-polyisocyanurate-without-covering-it-with-drywall/68919#68919) but I agree, *especially in a garage*.

INSULATING A STUCCO SHED


Have proteins been observed to come into existence through mutations and natural selection?

Question: A protein that catalyzes one reaction can theoretically be modified by mutations and natural selection and eventually catalyze another reaction completely unrelated to the original. Has this been observed, documented, or at least postulated to be where a certain protein(s) came from?
Comment: The "real time" requirement is an incompatible criterion with the rest. It's designed to make this question essentially unanswerable.
Comment: Mutation of a (duplicated) existing protein is the *usual* way a new protein evolves.
Comment: This sounds dangerously close to the fundamental biblical literalist Ken Ham's distinction between "Historical" versus "Observable" knowledge, which is utter tripe ([refer to crime scene analogy](http://www.skepticblog.org/2014/02/26/observational-vs-historical-bunk/)). Especially with the odd parameter that "homologs don't count".  As @KonradRudolph eluded to, this question is designed to be unanswerable, but fortunately, the more patient users on this site have provided awesome answers.
Comment: What do you mean with "in real time"? Sequencing an organisms, adding an evolutionary pressure, sequencing again and suddenly finding a new protein?
Comment: @James I apologize for the poor quality of the original question. I was fresh off a heated debate when I asked this question. I have modified it to better reflect my ignorance seeking understanding.
Answer: How about EWS-FLI1 and other oncofusion proteins?
One could argue that cancer progression is as close to viewing "evolution in real time" (as you say) as possible.
Comment: how was this a new protein from scratch? thnx
Comment: Oncofusion is very similar to homologues, especially when there is not modification of function.  Your link on "EWS-FLI1" explains that a virus causes a cancer by modifying gene regulation, which is a change in DNA sequence not Protein amino acid sequence. I don't see how your answer addresses a change in reaction catalyzed.
Answer: From the following free review:

Here we review some of the successful strategies in creating protein
diversity and the more recent progress in directed protein evolution
in a wide range of scientific disciplines and its impacts in chemical,
pharmaceutical, and agricultural sciences.

Quoting three examples, but the article has much more:

Directed evolution has been successfully applied to DNA polymerase for
enhanced activity (233) and conversion to an efficient RNA polymerase
(232, 333).
Naumann and Reznikoff (216) used directed evolution to generate a
mutated Tn5 bacterial transposase that could function on transposons
with mutated end binding sequences.
Organophosphate-degrading enzymes have been evolved and selected for
broadened substrate specificity (53, 335). Broadened substrate
specificity of a biphenyl dioxygenase has also been achieved (33, 87,
164, 291). Efforts in cleaning underground water contamination
prompted the evolution of an enzyme for chlorinated ethene degradation
(41).

L. Yuan, I. Kurek et al: Laboratory-directed protein evolution. In: Microbiology and molecular biology reviews : MMBR. 69, 3, September 2005, 373–392. doi:10.1128/MMBR.69.3.373-392.2005. PMID 16148303. PMC 1197809.
Comment: Assuming that the OP was really interested in "natural selection" I guess these don't provide an answer. Of course, in the broader sense, human activity could be deemed to be an agent of natural selection.
Comment: These are fascinating modifications of proteins. I was hoping for something more drastic than modified binding specificity and catalytic efficiency. Has there been a change in function from one reaction to a completely unrelated one?


Transmission or not?

Question: I have a question. My 2007 ford Mustang with an automatic transmission will start up and allow you to put it in any gear, but the car will not move even though the motor revs up. Any idea what caused this. It drove normal the day before with no check engine warnings.
Comment: When you move the shifter from Park to Drive (or Reverse), do you feel it shift, or does it act like it's just ignoring the shifter?
Answer: Inspect your transmission shifter cable. Make sure it is tight at both ends, as this is the most likely cause. This would leave the transmission in Park. If the cables seems tight, shift through all the positions on the selector, do this a few times, and then try D again. If it still doesn't work, try R.
Make sure you have transmission fluid. Use the dipstick, make sure you have enough tranny fluid. In an automatic, no fluid, tranny no go.

Transmission or not?


Connect C wire to Furnace

Question: I have a Lenox Merit system in the house. I am trying to install Nest E thermostats and want to do it with a C wire. I noticed an unused Blue Wire (pic attached) at the thermostat location and then in the attic saw that the Blue wire is not attached to the C at the circuit board. There is another wire in the C. Do I just add the blue wire in the same location ?
Answer: Go ahead
The terminal blocks on HVAC control boards can generally handle two wires per terminal, so landing the C wire to your thermostat on the furnace board's C terminal directly is fine.
Comment: Thank you, thats what I was hoping for. I added the wire straight to the terminal and tested the current thermostats, everything is fine. Now on to the nest

Connect C wire to Furnace


Interfacing 4 ESCs and an Arduino with a single LiPo battery

Question: I have 4 BLDC motors, and 4 ESCs, one for each motor. But I have one LiPo battery from which I want to power one Arduino Mega and all the 4 ESCs. Can I remove the connectors from the ESCs and put them on a breadboard in a single column/row so that they are connected together, and then connect the + and - of the battery (after removing its connector as well) to the respective breadboard column/row, so that they are essentially connected together to power all the ESCs? Also, I would want to use a jumper from the Arduino Vin and GND pins to the same column/row on the breadboard. Will this method of powering all the 4 ESCs and the Arduino from a single LiPo work?
Comment: Please edit the post to explain what ESCs and BLDCs are.  These are not obvious acronyms.
Comment: Yes, but you don't want to use a breadboard for it.
Answer: Powering all the ESCs from a single LIPO is not an issue.
Using a breadboard to distribute this power is highly unlikely to work, breadboard connectors are usually only good to a few hundred mA, 1A is you want to push your luck.  Most ESCs and BLDC motors are in the 5A to 50A range (each, your power bus has to handle 4 times this current).
Also, ESCs tend to inject a lot of noise into the power bus.  If you connect the arduino to the ESC power bus, you will likely get random resets and really poor noise performance on the ADCs.  Keep in mind that some ESCs actively brake the motors using regenerative braking, which puts the kinetic energy of the motor back into the power bus.  This can increase the voltage on the power bus to more than the nominal battery voltage and can have large voltage spikes on it causing a failure on the Arduino.
If you are prototyping, use a separate power supply/battery for the arduino and connect all the grounds together instead of using a single supply.  If you are building a rover/uav/whatever and don't want a second battery, use a high quality BEC (or the BEC output from a high quality ESC) and remember that the 5V output on a BEC/ESC can be significantly higher than 5V in reality).
ESC = Electronic Speed Controlled
BEC = Battery eliminator circuit (I think, basically a 5V-ish regulator)
BLDC = Brushless DC motor (three phase in this case)


Reusing a portion of a neural network (with shared weights) in Keras

Question: I have a partial neural network with several layers of various types, with weights $\theta$; let's call it $F_{\theta}$; and the dimensions of input and output arrays are the same, implemented in Keras with Tensorflow backend. Within this framework, how do train a model of the form $y = F_{\theta}(F_{\theta}(x))$, or more generally some $n$-th iteration of $F_{\theta}$? In other words, I reuse an entire subset of the neural network, with all the same weights, so the full model is deeper but does not have more parameters than the shallower model.
Answer: When you build your Keras model using the functional interface, you can also build additional models on any subset of the paths through the network by reusing the intermediary functions. Then you can train on just portions of the network (given that you have targets for the outputs). I haven't tried to train on sub-networks of a network, but I do use these intermediary models to propagate activations between internal layers. The Python package conx that is built on top of Keras will build these intermediary models for you, by the way. For more, see: http://conx.readthedocs.io/en/latest/Getting%20Started%20with%20conx.html?highlight=propagate_from#Propagation-functions


Can I get in trouble for making a malware?

Question: I'm making a malware software in my final thesis at the university. I won't use it ever, and it was made by educational and scientific purposes only. But my university will publish it, giving the opportunity for everyone to use it. If someone commit a crime with my software, can I get in trouble?
Comment: Was this a project set by your university, or did you select it yourself?
Comment: I selected it by myself, but they approved it.
Comment: Computer crime laws around the world vary a lot. What's legal in Nigeria might be illegal in Switzerland. Please add a tag appropriate to the jurisdiction you are in.
Answer:
my university will publish it, giving the opportunity for everyone to
  use it. If someone commit a crime with my software, can I get in
  trouble?

I would say "No" for three reasons. I will assume that you are in a jurisdiction of the U.S. or reasonably similar thereto.
First, the malware code is part of your thesis, which in turn is a prerequisite (already approved by the university) for graduation. If anything, the entity that would be knowingly broadcasting the material is the university, not you. Any liability in the vein of MCL 750.540f would fall on the university, as it knows better than you about the presumed "risks" as to whether third-parties might abuse your research.
In the context of a public university with its typical status of "arm of the state", it would be untenable if one arm of the state (the university) authorizes you to proceed, and subsequently another governmental agency prosecutes you once your thesis reaches completion.
Second, your thesis with all the source code therein expresses ideas which are protected by the First Amendment. A serious discussion of malware necessarily requires that these ideas be expressed in assembly code (often intertwined with excerpts in machine code) of the architecture for which it is devised. Anything short of that makes a discussion of malware meaningless because this topic depends so heavily on the particulars of the targeted family of processors.
Furthermore, the academic context evidences your pursuit of educational & scientific advancement rather than a direct or indirect intent to encourage criminal activity. A person whose ultimate purpose is to promote computer crimes has many alternatives which are quicker and more effective than enrolling in a university, pay tuition, and undergo years of academic study.
Third, (without minimizing your merits) it is doubtful that no solution could ever exist for the malware you devise, or that no one else from a "clandestine" setting would ever come up independently with an akin variant of that malware. Thus, publications of malware made with the openness and formalities of a university thesis are likelier to be viewed as a heads up to IT security companies about enhancements they might need to make on products & services they offer.
Answer: There's not much I can say without knowing where you're operating, but I would suspect the charges would fall on the party who used it, not the developer. Especially if you could prove your university sanctioned the project's creation and lack of ill intent. I know this isn't the place for opinions, but I could find no legal precedent here in the US, and I can't assume the cyber crime laws for any other country.


What is the difference between a "compass swing" and "check swing" procedure?

Question: What is the difference between a "compass swing" and a "check swing" procedure?
Answer: Based upon the terminology I have heard over the years, a compass swing is the alignment of the compass, normally using a compass rose painted on a surface. The compass is adjusted and a deviation card is created for cardinal points on the compass.
A check swing, as I have heard it referred to, is the checking of the compass, and done with the aircraft running, and electrical loads on, similar to a compass swing, but without the adjustment.  The deviation card is verified, but there is no intent of adjusting anything.  This was typically done before we ferried aircraft over the ocean, where there would be extended dead-reckoning (before GPS and LORAN), and where flights were close to the polar regions, and compass operation needed to be verified prior to the flight.
Not that a compass is worth much near the poles (grin).
My guess is that check swing is merely a slang term, whereas compass swing is well understood and extensively documented.
Comment: In the US maintenance by pilots is governed by FAR Part 43 Appendix A, Paragraph (c). Compass swings are not included in the list of preventive maintenance pilots can do, so must be done by a certified A&P. Compass checks involve no maintenance, so are perfectly fine.
Comment: @JScarry, you are correct.  I did a double check.  I also found that when I swung the compass the mechanic put an entry in the log, along with a copy of the deviation card I created.  So I guess that is mechanic supervised maintenance.  Thanks for pointing out.   I removed my addendum, which had that error.
Comment: I happened to notice a bunch of logbook entries with the deviations in the books I was reviewing over the weekend. It seems they often did a compass swing after installing new avionics, which makes sense since the magnetic fields generated by the avionics might change.
Comment: If a HF radio was added, like for oceanic crossing, we would strap the radio in place, and swing the compass.  two degrees off makes a big difference crossing the pond.  Topping things off, most of the planes did not have working AP.  So it was about 28 hours of stick time for some of them.
Answer: A compass swing involves adjustment by a qualified person. A check swing can be done by anyone to verify the serviceability of the compass without adjustment. Check swing can be done anytime the compass is suspect or, if required for, annual check. if no adjustment is required no certification by a compass qualified person is required.


What are the Segmentation algorithms that can be used to process Satellite images (obtained from Google Earth) to segment forest and barren areas?

Question: I have tried Region based Segmentation - through Seed Growing, Watershed algorithm, and Graphcut algorithm, but none have been successful so far. I am using MATLAB.
Answer: You could try image saliency or entropy filtering. Entropy filtering calculates the entropy of gray values in the image Image within a rectangular mask. The result is written to the output image. The process is repeated in a sliding window fashion.
In the resulting image, the forest areas should appear more whitish while the barren areas appear black, because they don't contain enough information.
Of course I assume the roads would make a problem. However you could get rid of them using morphological edge finding operations.


When was the last interaction between Pandavas and Krishna?

Question: If I understand correctly, Krsihna didn't accompany them on their final ascent to the Himalaya and beyond.
Comment: Last interaction with Arjuna was during Yadav race destruction and with other Pandavas, it was when He saved Pariksit, (I guess)
Answer: When Ashwamedha Yajna of Yudhishthira has finished and Lord Krishna has described the Anugita to the Arjuna, Lord Krishna said to Arjuna that he wanted to leave for Dwaraka. It is mentioned in Mahabharata: Book 14: Aswamedha Parva: SECTION LI.

"Vasudeva said, 'I am the preceptor, O mighty-armed one, and know that the mind is my pupil. Through my affection for thee, O Dhananjaya, I have related this mystery to thee. If thou hast any love for me, O perpetuator of Kuru's race, do thou then, after having heard these instructions relating to the Soul, always act duly (according to them), O thou of excellent vows. Then when this religion has been duly practised, O mower of foes, thou wilt become freed from all thy sins and attain to absolute emancipation. Formerly, when the hour of battle came, this very religion, O thou of mighty arms, was declared by me (to thee)! Do thou, therefore, set thy mind on it. And now, O chief of Bharata's race, it is long since that I saw the lord my sire. I wish to see him again, with thy leave, O Phalguna!'
"Vaisampayana continued, 'Unto Krishna who had said so, Dhananjaya said in reply,--We shall go to-day from this town to the city called after the elephant. Meeting king Yudhishthira of virtuous soul there, and informing him (of thy intention) thou shalt then repair to thy own city!'"

And then in the next chapter, i.e. Mahabharata: Book 14: Aswamedha Parva: SECTION LII, Lord Krishna took permission of King Yudhishthira.

"Thus addressed, Phalguna, well conversant with speech, humbly approached king Yudhishthira the just and then said these words.--'Vasudeva here, of great prowess, O king, is long absent from home. He desires, with thy permission, to see his sire. Let him go, if thou thinkest it meet, to the city of the Anarttas. It behoveth thee; O hero, to grant him permission!'
"Yudhishthira said, 'O lotus-eyed one, blessed be thou. O slayer of Madhu, do thou go this very day to the city of Dwaravati for seeing, O puissant one, that foremost one of Sura's race. O mighty-armed Kesava, thy departure is approved by me. Thou hast not seen my maternal uncle as also the goddess Devaki, for a long time. Meeting my maternal uncle and repairing to Valadeva also, O giver of honours, thou wilt, O thou of great wisdom, worship both of them at my word as they deserve. 1 Do thou also think of me daily as also of Bhima, that foremost of mighty men, and of Phalguna and Nakula and Sahadeva, O giver of honours. Having seen the Anarttas, and thy sire, O mighty-armed one, and the Vrishnis, thou wilt come back to my horse-sacrifice, O sinless one. Do thou then depart, taking with thee diverse kinds of gems and various sorts of wealth. Do thou, O hero of the Satwata race, also take with thee whatever else thou likest. It is through thy grace, O Kesava, that the whole Earth, O hero, has come under our dominion and all our foes have been slain.'

So, this was the last interaction between Lord Krishna and Pandavas. After that Arjuna came to Dwaraka just after the destruction of Yadu's race (including Lord Krishna and Balarama). It is mentioned in Mahabharata: Book 16: Mausala Parva: SECTION 5.

Vaishampayana said: "Meanwhile Daruka, going to the Kurus and seeing those mighty car-warriors, the son of Pritha, informed them of how the Vrishnis had slain one another with iron bolts. Hearing that the Vrishnis along with the Bhojas and Andhakas and Kukuras had all been slain, the Pandavas, burning with grief, became highly agitated. Then Arjuna, the dear friend of Keshava, bidding them farewell, set out for seeing his maternal uncle.
Comment: i think the gap bw 2 incidents is ~36years..so didn't they meet in that duration?
Comment: @YDS Oh. I didn't know that. But I have not found any references between these two events when they interacted each other. I think they would have interacted by other means but not personal meetings.
Comment: AAfter this, Krishna attended the ashvamedha yagna of Yudhisthira and actually revived Parikshit
Comment: @Funlife Any sources?


Which of these vegetables are less bloating?

Question: Which should we prefer to feel less bloated: kale, cabbage, spinach, brussels sprout, celery, or avocado?
Is there a bloating scale for them ?
Comment: Nope, not even cabbage. It doesn't give me gas or at least not enough that I've ever noticed it. About the only food that does is beans, and that just produces flatulence, not bloating.
Comment: None of them make me feel bloated, so how would we construct such a scale?
Comment: @Carey Gregory even cabbage ? It's undeniable fact that it gives people a lot of gas.
Answer: A common cause of bloating is consumption of high amount of soluble fiber, which is fermentable by normal intestinal bacteria, which produce gas. From your list, Brussels's sprouts and avocado have more soluble fiber than kale, spinach and cabbage.
Other examples of foods high in soluble fiber (potentially bloating):

Legumes: beans, peas, lentils
Fruits: figs, eggplant, apples, pears
Cereals: barley, oats, rye
Artichokes
Sweet potatoes

Source: Nutrientsreview.com
Individuals with fructose malabsorption (which is relatively common) can experience bloating after eating foods that contain more fructose that glucose (apples, pears, honey, beverages sweetened by HFCS, commercial foods with added "fructo-oligosccarrcharids (FOS)," inulin or sugar alcohols (sorbitol, mannitol, xylitol...).
Source: Uwhealth.org
Comment: It's not only fiber, there are also sugars that mammals cannot digest.
Comment: The "sugars" that humans cannot digest or absorb are sugar alcohols (polyols) and certain artificial sweetners, such as lactulose. These substances may or may not cause bloating; they more likely cause it in individuals with fructose malabsorption, as mentioned above.
Comment: I meant that a lot of gases being produced if mammals eat such stuff like pea (I'm not sure what term I should use: meteorism, flattulence...)