Photo resolution for a large canvas

Question: I'm trying to resize a photo taken with a Canon 5D Mark III for a 36" X 72" canvas at 300ppi through Lightroom 5. I exported the photo at H: 10800 X W: 21600, but the printing company is telling me that the resolution is still too small. Can anyone give me a suggestion?
Comment: Possible duplicate of [What is a suitable image resolution for canvas prints?](http://photo.stackexchange.com/questions/19678/what-is-a-suitable-image-resolution-for-canvas-prints)
Comment: 10800 x 21600 is 230 megapixels, your camera has 22 megapixels
Comment: Did you verify that the exported image actually had those dimensions? I'm not familiar with Lightroom's behavior, but some software will only use the dimensions you give for *downscaling*, and will do no resizing if the image is already smaller than the specified size.
Comment: It has TOTALLY no sense on resampling an image like that! Send the original file!
Answer: We already have quite a few answers on this topic, so you should do some reading at least here:

Is there a general formula for image size vs. print size?
What is a suitable image resolution for canvas prints?

The short of it is that you should not resize anything on your side. Let the printer do that for you. Send them the largest image you have before you have tried any resizing. It should work just fine for what you are doing(assuming up to 72 inches) if the image was from a 5D MkIII.
Comment: I can not understate the importance of this: "The short of it is that you should not resize anything on your side"... (Is that a correct use of understate? :o)
Comment: But... the question implies that the printers *aren't* going to do that for them, and have said so.
Comment: @junkyardsparkle Yes I agree that it implies that. The issue I believe is user error and not any printer shortcomings.

Photo resolution for a large canvas


Was T'Uerell ever mentioned or appeared in any other Star Trek storylines?

Question: A Vulcan Philosopher named T'Uerell who was obssessed with "logic" and "perfection" was credited as the creator of the Borg in the videogame Star Trek: Legacy. I was wondering if she ever appeared anywhere else as she was very badass.
Comment: [According to this](http://memory-beta.wikia.com/wiki/T'Uerell), she has nothing to do with the creation of the Borg.  Rather, she used their technology and took over the Borg.
Answer: According to Star Trek : Legacy, T'Uerell isn't credited with having created the Borg. Within that particular canon, that honour goes to V'ger.

A later origin was discovered by the Vulcan scientist T'Uerell during
  her attempt to become the new controlling entity within the Collective
  in order to mold the galaxy into a realm of pure logic. After entering
  a deep meditative state, she mind melded with the Borg Collective
  consciousness and discovered that the origin of the Collective lies
  with the human-built machine probe that would be known as "V'Ger."

As regards further appearances of T'Uerell in the Star Trek EU, there haven't been any.
They did at least leave the door open for a possible sequel though...


plural/singular controller name

Question: I know that using plural for controllers name is the right way in Ruby, but in some cases using singular for controllers name is more appropriately. For example
http://foobar.com/admin/login/
http://foobar.com/admin/dashboard/
http://foobar.com/profile/

I think you get what I mean.
So which are the best practices of using singular for controllers names ?
Any example will be appreciated !
Answer: If you don't need the whole scaffolding, for example you probably have no admin model, then you can just generate a controller with a singular name.
rails g controller admin
Then, you need to take care of the routing.
match 'admin/login' => 'admin#login'
Answer: Rails favours convention over configuration, so it means that controllers are ALWAYS using plural, table names also, whereas models are always using singular, with an uppercase at the beginning.
I would strongly advice you to stick to these conventions, that's best practice and in the foundation of the Rails framework
Comment: I know that but it will be ugly to see http://foobar.com/logins/ or http://foobar.com/profiles/ etc.

plural/singular controller name


Configure AAA on a router - Extended ACLs

Question: How do I write a named extended ACL which will allow for traffic between a DNS from a LAN (IP address) to a DNS server at (IP address), ping from a host PC (IP address) to any destination and allow for telnet packets from a telnet server with any source address going to any destination?
Comment: Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can post and accept your own answer.
Answer:
allow for traffic between a DNS from a LAN (IP address) to a DNS server at (IP address)

permit udp <LANIPaddress> <LANIPwildcard> <DNSIPaddress> 0.0.0.0 eq 53
permit tcp <LANIPaddress> <LANIPwildcard> <DNSIPaddress> 0.0.0.0 eq 53

ping from a host PC (IP address) to any destination

permit icmp <hostPCaddress> 0.0.0.0 any echo

allow for telnet packets from a telnet server with any source address going to any destination

permit tcp any eq 23 any

Depending on where exactly you apply the rules, you might also require ACL rules for their reverse directions. Don't forget that an ACL denies/filters everything without an explicit permit.
Since you've flagged your question aaa: ACLs cannot provide that, they just provide basic filtering - possibly Authorization (in cooperation with other mechanisms) but no Authentication or Accounting.
Comment: If the LANIPaddress is 188.8.131.52, is the LANIPwildcard 10.0.0.1 OR 0.0.3.255? Is it both?
Comment: The wildcard is the inverse (ones' complement) of a subnet mask if you use it with subnets. For e.g. a /20 subnet you'd use 0.0.15.255 as wildcard. In contrast to subnet masks, wildcard bits don't have to be contiguous. Any wildcard bit that is set makes the according address bit match either 0 or 1.
Comment: Also, if I wanted to allow SSH from any source address to another router's fa0/0 address and include an ACE on line 800 that will deny all other IP traffic, how would I do that? @Zac67
Comment: Denying all other IP traffic doesn't require anything. It's the default, implied final ACE in any ACL. SSH uses TCP port 22, just replace that in the above examples.
Comment: One last thing, how would I edit the ACL to match packets from a host PC (IP address) to access the server on 2 TCP ports?
Comment: You use two rules.


What is bitly='BITLY_PROCESSED' in  tag?

Question: While i was inspecting facebook html code through with firebug in Chrome, i found this tag :

What is the bitly attribute? Anyone has an idea?
:)
Comment: In my opinion, that's some dark magic from facebook
Answer: It gets added by the bit.ly plug-in (and perhaps some others) when it examines links (see http://bit.ly/pages/tools form more on that). If you don't have that plug-in yoruself, then it may be that someone somewhere along the line did.
Answer: bit.ly offers URL redirection service with real-time link tracking, or in other words URL shortener, so I am guessing you have it's plugin installed.

What is bitly='BITLY_PROCESSED' in  tag?


concrete slab up over vinyl siding

Question: I tore out my front porch slab so I can waterproof the foundation. It was also sinking and since it has a column to support an overhang, that's a problem.
My question is what should I do about where it needs to come up to a level higher than the bottom of the vinyl siding? In an ideal world, the slab for the porch would be against the block foundation of the house, staying well below the siding. The level of the slab also puts it above the wooden bottom plate of the house. In the picture you can see by the dark line on the siding where the main level of the slab was (there is also a step up to the front door). It also looks like no forms were used by the house, the concrete was just poured against the siding. How would I do better?
Comment: Wow, just wow - what a throughly poor job that was. Don't repeat it.
Comment: And that's not all I've encountered at this house. A deck ledger was put right over vinyl siding. No flashing at all. And then to top it off they used long nails for the joist handers that also penetrated the siding!
Answer: You can pour a new slab up to the level of the foundation, not higher. In this case,  you could basically fabricate a new concrete patio that's below the level of the previous one and build some steps leading down from the door to the patio.
You could also forget about making a concrete patio and build a wooden (or composite decking) patio at the current level of the door.
In general, I would recommend against pouring concrete right up against the foundation, because it provides hidden termite entry points and makes it very difficult for you or future owners to insulate the exterior of the foundation later (if this is an appropriate foundation insulation and hasn't already been done). Also, you have to get the slope away from the house perfect or else you're redirecting water into your foundation.
Comment: Interesting idea about a wood deck. The lower level might work, as there was already a small slab in front of the porch at the lower level.
Comment: I think a wood deck is probably the way to go, just make sure that the land is sloped away from the house. It's possible that by excavating all this concrete you have created a low point in this corner, which is bad for water runoff. Also, this is a good time to install a perimeter drain if drainage is questionable.
Comment: Yes, installing foundation waterproofing and a perimeter drain are the main reasons for tearing out the slab.

concrete slab up over vinyl siding


Swapping Rockshox TwistLoc lockout to trigger lockout

Question: I have a Trek Top Fuel 8 with a Rockshox TwistLoc lockout system. Can I switch it for a trigger lockout?
Answer: Yes, I believe the Top Fuel has a Rockshox Recon shock - Rockshox have a "Remote upgrade Kit" for the job (Make sure the kit matches your shock) . Not particularly hard to do yourself, but you may prefer to get the LBS to to do it if you are no familiar with shock servicing procedures.


Why does Fluent NHibernate create ALWAYS a Text field from a C# String property as DEFAULT?

Question: I run this sample here: https://github.com/jagregory/fluent-nhibernate/blob/master/src/Examples.FirstProject/Program.cs
All C# Properties of type String are mapped into TEXT sql fields and not
nvarchar OR varchar as I would except it to be as DEFAULT setting.
How can I change that?
I know I can do this:
Map(x => x.Name).CustomSqlType("nvarchar").Length(50); // does not work !!!
Map(x => x.Name).CustomSqlType("nvarchar (50)"); // does work !!!

but I do not want to change every field...
UPDATE: ... therefore I can do a custom convention via =>
What I have to do is write a custom Convention class like:
public class ColumnStringToNVarCharConvention : IPropertyConvention, IPropertyConventionAcceptance
    {
        public void Apply(IPropertyInstance instance)
        {
            instance.CustomSqlType("nvarchar");
        }

        public void Accept(IAcceptanceCriteria<IPropertyInspector> criteria)
        {
            criteria.Expect(x => x.Property.GetType().Equals(typeof(string)));
        }
    }

Can someone proper the above code? I tested it and it did not work whyever...
Comment: Wouldn't it be more confusing if it *didn't* default to `Text`, or `NVARCHAR(MAX)`? After all, any length chosen as a default would be just as arbitrary and your question could then be "Why does NH choose length x as the default for NVARCHAR fields?"
Comment: Funny... this guy has the OPPOSITE problem just 6 months ago: http://stackoverflow.com/questions/3105391/mapping-large-string-with-fluent-nhibernate  He gets as DEFAULT NVARCHAR and wants Text lol ???
Comment: The major part > 90 % of database string fields are varchar or nvarchar not TEXT which can not be indexed. So why not offer then varchar/nvarchar as DEFAULT?
Comment: I have to manually edit my field settings from TEXT to Varchar because 10 % of the fields in average are used as TEXT ? Does not make sense. Why not make DEFAULT what is 90% ? Logical eh?
Comment: Are you using the same dialect in your configuration as your database?
Comment: @Kent CONVENTION over CONFIGURATION !!! :)
Comment: @Paco same dialect? I use C# class with String property and get a Text field in my database. There is not more info.
Comment: I have updated my question at top with a sample!
Comment: With dialect means something like mysql, sqlserver2000, sqlserver2008
Answer: You're using SQLite, correct? That's where your problem lies. It's described better in this answer to another post, but SQLite doesn't have data-types in the same sense as other databases. It's not a Fluent NHibernate issue, it's the way NHibernate deals with an almost data-typeless database.
For more strict databases, Fluent NHibernate defaults to more sensible data-types. It varies by database, but it will be an nvarchar for strings.
Comment: I have read your post James about the sqlite datatypes. I knew a date is a string but I did not knew at all that there are only 5 datatypes using an sqlite IDe for years displaying stuff like varchar,nvarchar HAHA
Comment: So the only reason why my IDE shows nvarchar,varchar etc.. is a friendly way of the IDE for people migrating from T-SQL,MySQL to sqlite because they are used to this datatypes. James would you though change my ColumnStringToNVarCharConvention  class, please?
Answer: You might try checking what compatibility level the database you are connecting to is.  If it is set too low (80), it might be defaulting to text because NTEXT was not deprecated until SQL2005, which is compatibility level 90.  This is not a guarantee, just a possible thought.
This is the MSDN instructions for checking to compatibility level...

To view or change the compatibility
  level of a database
After connecting to the appropriate
  instance of the SQL Server Database
  Engine, in Object Explorer, click the
  server name to expand the server tree.
Expand Databases, and, depending on
  the database, either select a user
  database or expand System Databases
  and select a system database.
Right-click the database, and then
  click Properties.
The Database Properties dialog box
  opens.
In the Select a page pane, click
  Options.
The current compatibility level is
  displayed in the Compatibility level
  list box.
To change the compatibility level,
  select a different option from the
  list. The choices are SQL Server 2000
  (80), SQL Server 2005 (90), or SQL
  Server 2008 (100).

With SQLite, there are only 5 datatypes, one being string.
http://www.sqlite.org/c3ref/c_blob.html

Every value in SQLite has one of five
  fundamental datatypes:
64-bit signed integer
  64-bit IEEE floating point number
  string
  BLOB
  NULL
These constants are codes for each of
  those types.
Note that the SQLITE_TEXT constant was
  also used in SQLite version 2 for a
  completely different meaning. Software
  that links against both SQLite version
  2 and SQLite version 3 should use
  SQLITE3_TEXT, not SQLITE_TEXT.
Comment: It's not a problem with fluent, it's how NHibernate handles SQLite.
Comment: Added more info to my above answer. You might also add a SQLite tag to the original question so you get someone who knows more about it to weigh in.
Comment: I retagged with fluent nhibernate because its a fluent problem not database related I am sure. I have updated my question again!
Comment: @James ok you beat me to it ;-)


Linked Sales Navigator Login issue in salesforce

Question: I did the configuration for linkedIn Sales Navigator and Salesforce. I am able to see Member and Company Information in LinkedIn widget embedded in Contact Layout too while I am logged in using LinkedIn Credentials on my system. The problem arises when I logged out of LinkedIn on my PC and check LinkedIn widget in salesforce. It's again asking for login as in attached Image.
Answer: If anyone else is facing same issue, Just want to add that I contacted LinkedIn support and confirmed that it is expected behaviour. Cheers!


F-measure for document clustering evaluation - NaN

Question: I'm developing the Java application for text document clustering, and I'm researching some evaluation methods. I implemented F-measure (http://en.wikipedia.org/wiki/F1_score), but I have a problem - the returned value is NaN. It happens where a cluster doesn't contain any data from a specific category - precision and recall are equal to zero. How should I handle this situation - F-measure in that case should be zero as well? I will be very grateful for any advice.
Answer: Short answer: I would just have an if statement that checks if both the precision and recall are zero and set the F-score to zero when that occurs.
Long answer:
In a rigorous mathematical sense, the F1-score is defined such that if the precision and recall are both zero, the F1-score is undefined:
$$
F1=2\cdot\frac{precision \cdot recall}{precision+recall}.
$$
You could perhaps justify setting F1 to zero by arguing that you are only sampling the true population and as precision and recall approach a small value, $\epsilon$, the numerator approaches zero faster than the denominator since it goes like $\frac{\epsilon^{2}}{\epsilon}=\epsilon$~0.
Answer: There is more than one F-measure around in the sense that it is computed on different data.
For evaluating cluster analysis, it seems to be most common to compute the F-measure on pairs of objects, and on the complete data set, not on single clusters.
See for example: https://stackoverflow.com/questions/12725263/computing-f-measure-for-clustering
Comment: I know, I'm calculating a weighted mean of F-measures for all clusters later.
Comment: Precision and recall for individual clusters aren't clearly defined or sensible, that is the problem you are running into.


How can I place my object onto a UV sphere to give it a rounded appearance?

Question: Blender newbie here, I'm trying to make a character for the first time, for the head I used a UV Sphere and I'm making all the stuff on its head, but I made it flat.

As the title says, is there a way to overlay my object onto the UV Sphere to make it rounded ?
Answer: Create a new plane behind Plane.001, subdivide it, give it a Shrinkwrap modifier with Sphere.001 as Target, disable it for the moment:

Give a Surface Deform modifier to Plane.001 with the new plane as Target, click on the Bind button:

Enable the visibility of the Shrinkwrap modifier of the new plane, it will wrap on the sphere and your other object will deform as well. If it doesn't deform enough, add topology:
Comment: I've edited my answer, if your french you can join our Discord here: https://discord.gg/E6wXbR7A5S
Comment: Sorry for the late answer, I tried it and it works but it's kinda glitchy : https://imgur.com/a/FopWTv1 and https://imgur.com/a/X50Zw8n
Maybe I did something wrong or it's because the shape of my object is bad : https://imgur.com/a/tCOGKkJ
Comment: are you using my method?Maybe share your file:https://blend-exchange.com/
Comment: Yeah but I probably made a mistake I guess, sorry, here's the link : https://blend-exchange.com/b/dZJlZbDG
Comment: Thanks it works fine ! I made a mistake the first time, I use a subdivision modifier instead of a simple subdivision with right click.
Also yes I'm french I'll join it, appreciate it :)
Answer: To do what you are wanting you'd have to change your approach a little bit, currently it looks like you have made a faceplate and an eye brow, but you made them with thickness, so if you project them onto the sphere it would flatten and you'd have both sides overlapping.
So instead you can make your shapes as flat planes (no thickness, you can just delete the back and sides of your current objects). Then add a Shrinkwrap modifier, and set the target as your sphere, and wrap method as "target normals", then add a Solidify modifier after the shrink wrap to add the thickness to your objects.
Alternatively If you are wanting to interactively move your points and have them stick to the sphere, you can turn on Snap, and set Snap to to Face Project, and now while in edit mode you can have your vertices snap to other shapes when ever you move them over it.


General Polygon Clipper: Triangulate without additional vertices

Question: I am using GPC to break up polygons into triangles. However, GPC is very obviously creating additional vertices while generating triangles. Is there a way to avoid this?
Answer: Use a different triangulator.  poly2tri looks promising.
Answer: Use an alternate method, such as ear clipping. This triangulates a polygon, but does not introduce additional vertices. Note, sometimes this can result in some odd triangles (very long and thin), which may be unwanted, since they are more prone to rendering artefacts.


2003 Dodge Ram 1500 3.7 engine knock

Question: My truck has been making a knocking noise upon acceleration. Today the knocking is constant and louder. What could this be?  Pistons? Oil sludge?  New motor?
Comment: Can you add some information?  Does the knocking stay in time with engine speed or road speed?  Does volume of the knocking increase under certain conditions?  How many miles are on the truck?  Have you looked for metal shavings in the oil during an oil change?  Thanks and Cheers!
Comment: Constant with engine. Louder when you accelerate. 197000 miles. Haven't noticed any shavings
Comment: See my answer here....http://mechanics.stackexchange.com/a/29550/16882
Comment: Shavings will be seen in fast failures, more than likely yours is normal wear of the rod-crank bearings and crankshaft over time, this will show no noticeable shavings. The wear is slow and small particles will be drained with each oil change.
Answer: The 3.7 is notorious for having a rocker arm fall off and or lifters collapsing. This is usually accompanied by a check engine light being illuminated.
Use a stethoscope or a long screw driver and try to isolate where the knock is coming from.
If it's coming from a valve cover, remove the valve cover and you're likely to find a rocker laying around. If this is true you need to thoroughly inspect the valve train components.
Comment: @ablank13 Try removing the serpentine belt to rule out a bad water pump or accessories. But if it's truly coming from the bottom of the engine you're going to need to pull the pan and inspect everything.
Comment: Knock sounds like it's coming from the bottom of engine
Comment: The early Hemi  V8 engines had catastrophic valve train failures also, Dodge quality.
Answer: Remove the valve cover and oil pan and inspect for rod bearing damage. Black or discolored rod caps are good indicators of spun bearings. Then, check the valve train for damage, failed lifters, heavy pitting, etc. If everything comes up good, then I suspect the timing guides or chains.
Answer: what about 2008 Dodge Magnam-v6 ride knock
Comment: Welcome to the site. If you'd like this answer taken seriously, you'd explain what "ride knock" is, and how it can be fixed or alleviated. Just saying it exists makes this a very weak answer.

2003 Dodge Ram 1500 3.7 engine knock


In Another, does the curse also kill the adults?

Question: In the anime 'Another', the curse is seen to only kill the teenage students of the school, so my question is - does the curse also kill the adults too? By adults I refer to the various parents and the tecahers.
Comment: Did you get to the end of the show?
Comment: Yes This is a website where people ask questions and answer said questions about sci fi.
Comment: I was just asking in case you didn't want anything spoiled...
Comment: Also, I remember that the teacher committed suicide after murdering his mother, and the car accident that killed student Aya Ayano also killed both of her parents who were driving the car
Answer: Yes it does. this wiki lists the deaths that occurred as apart of the Calamity

This page lists the deaths that have occurred due to class 3 grade 9's curse to the latest episode.

a couple of the adults from the 1998 Calamity are

Mieko Sakuragi - Died in a car accident in the same day as her daughter, Yukari.
Shoji Kubodera - The class teacher. He committed suicide by stabbing himself in the neck with a kitchen knife in front of the class, Monday July 13th. He also killed his elderly mother a little earlier.

we can also count The Extra's death whos very existence in 1998 is because of the Calamity due to the fact that had previously died
the page also notes that one adult who died in the 1998 Calamity but because of their location and lack of connection with Class 3-3 may not be counted as having died as a result of the Calamity

Teruya Sakaki, a survivor of the 1987 Calamity, died in his home on May 3 of 1998; however, as he was outside Yomiyama and no longer directly connected to Class 3-3, his death may not have counted as part of the Calamity of 1998.


How to route copied packets to second interface?

Question: I have two AWS instances running CentOS 7, A and B, and I need to send all copied packets from A to a second interface on B (eth1). I have set up IPTables to copy and send packets:
iptables -t mangle -A PREROUTING -i eth0 -j TEE --gateway 10.0.3.101

I can see the packets increment using:
iptables -t mangle -L -n -v

I can ping both interfaces from each other. The route is set up as:
default via 10.0.3.1 dev eth1 table 100
10.0.3.100 dev eth1 table 100

The rules are set as:
from 10.0.3.100 lookup table 100
to 10.0.3.101 lookup table 100

When I do a tcpdump for eth1, I only get ARP request and reply. When I ping from 10.0.3.100 to 10.0.3.101, I can see the ICMP packets.
Source/destination check is disabled. ip_forward is enabled on both instances.
With a single interface set up on an instance in the same subnet, I can see the copied packets. When I set up an instance with two interfaces, in two different subnets, I can not see any copied packets, but I can see pings and responses to them on both instances.

Instance A has eth0 on 10.0.3.100 (subnet 10.0.3.0/24).
Instance B has eth0 on 10.0.4.100 (subnet 10.0.4.0/24) and
eth1 on 10.0.3.101 (subnet 10.0.3.1/24).
I am trying to send copied packets from 10.0.3.100 to 10.0.3.101.
Answer: Since this was on AWS, I didn't disable source and destination check on the second interface. After correcting that, it worked.


What is the difference between 形成, 构成, 组成, 养成?

Question: According to the dictionary, 成 has meanings of to become or to form, what is the subtle difference between 形成, 构成, 组成 and 养成?
Comment: I suggest you to look up the compounds, rather than the individual characters. No +1 from me today for this reason. Would be a much more valuable question if you had done some research and are stuck on more specific nuances.
Answer: You can look up a dictionary first, as they are quite different, except for 组成 and 构成. Compared with 组成, 构成 sometimes emphasize the interaction between constituents, but they are very similar in most cases.
Answer: 形成: to form to some situation or status by developing a progress of action
构成, 组成: consist of
构成 and 组成 can be used interchangeably in most of case.
养成 is a bit different from the other 3 words. It means to cultivate (a habit).


simple exercise of euclidean geometry

Question: I've to solve this simple exercise but i can't see how.
Problem: let $AB$ and $CD$ two equivalent ropes of one circle of centre $O$. Let $P$ and $Q$ two points that belong on the extentions of the previous ropes such that $BP$ and $DQ$ are equivalent. So show that the centre $O$ belong on the axis of the segment $PQ$ .
Comment: What is a "rope of a circle"?  Can you provide a drawing?  Even a snapshot of a hand drawing, with the points labelled, would suffice.
Comment: @Brian Tung in the figure you can see the rope of a circle. I don't know the right english term
Comment: Ahh, OK, they're called "chords."
Comment: By "axis," do you mean "perpendicular bisector"?  That is, the line that is perpendicular to $\overline{PQ}$ and intersects it at its midpoint?
Comment: yes that's right
Comment: @Brian Tung how you that $P$ and $Q$ lie in the same circle?
Comment: @Brian Tung  sorry i get it
Answer: First, show that $OP = OQ$; that is, both $P$ and $Q$ lie on a circle with center $O$:

$OB = OD$ (both on the same circle)
$BP = DQ$ (given)
$\triangle OAB \cong \triangle OCD$ (side-side-side, see below)

$OA = OC$ (both on the same circle)
$OB = OD$ (both on the same circle)
$AB = CD$ (given)

$m\angle OBA = m\angle ODC$ (corresponding angles of congruent triangles)
$m\angle OBP = m\angle ODQ$ (supplementary angles of equal angles)
$\triangle OBP = \triangle ODQ$ (side-angle-side)
$OP = OQ$ (corresponding sides of congruent triangles)

Now consider triangle $OPQ$.  Let $R$ be the midpoint of $PQ$.  Then

$PR = QR$ (midpoint)
$OP = OQ$ (proved above)
$\triangle OPQ$ is isosceles
$m\angle OPQ = m\angle OQP$ (base angles of isosceles triangle)
$\triangle OPR \cong \triangle OQR$ (side-angle-side)
$m\angle ORP = m\angle ORQ$ (corresponding angles of congruent triangles)
$m\angle ORP = m\angle ORQ = 90$ (congruent supplementary angles)

Therefore $\overline{OR}$ is the perpendicular bisector of $\overline{PQ}$.

simple exercise of euclidean geometry


Pattern Lock can't be disabled through settings

Question: my girlfriend set up a pattern lock and we're unable to remove the pattern now. The Settings show the disabled Option and the text: "Admin, Guideline or login data prevent this". So I disabled all device admins, deleted all VPNs, removed all Login Data and found out that this helped nothing.
The device is a HUAWEI P8 Lite (no root/no bootloader enabled) running on Marshmallow.
Does anyone have an idea how to resolve this problem?
Comment: Do you have Android Pay or Mobile Iron (for corp access) setup? Maybe those are requiring pattern lock to be enabled.
Answer: If you have locked it through third-party app then try this. If there is Advanced Protection enabled on your pattern locking app, then you you need to deactivate the Advance Protection. You can do this by going to Settings >Security >Device Administrator >Uncheck the app. After this disable/force stop/uninstall the app. If you have put pattern on settings too then Goto SafeMode. Google it

Goto SafeMode [Your device brand] [Your device model]

After going into SafeMode do the above steps and after that restart your phone. Hope it will help.


Deformation of particle objects

Question: When an object is added to particle system, it remains in original form. Is it possible to make so that these objects deform & wrap around mesh?
Answer: The closest I can get:

Make sure the particle object is a plane and has a good amount of subdivisions

Name it with a unique name, like 'stick'
Make a duplicate of Suzanne, remove the ParticleSystem from it (this is if you want to have the Subsurf modifier eventually on for Suzanne)
Apply the Subsurf modifier of the temporary particle-Suzanne, which leaves only the ParticleSystem to the modifier panel
(You may need to update the ParticleSystem by clicking the 'Seed' value to 1, for example)
Click the 'Convert' button in the ParticleSystem modifier

A whole lot of stick objects are created to the scene
Delete the particle-Suzanne
In Outliner, search for 'stick.'
Still in Outliner, select them all with A, then right-click one of them and click 'Select'
Press U to make them unique, select 'Object & Data'
Press Ctrl+J to join them as one
Add 'Shrinkwrap' and 'Solidify' modifiers to it

Maybe also 'Subsurf' modifier as well
There you have it

Hope this helps!
Comment: Yes, it works! Thank you!
By the way, but what if need to use not plane, need use an object of a certain shape? Shrinkwrap won't work in this case.
Comment: Yep :/ That makes things a bit more harder. I don't have much advice on that.
Comment: OK. But thanks anyway, that you helped.

Deformation of particle objects


Submitting a form causes 'secure connection failed' error that persists

Question: I've got a SSL certified server running drupal 7.37.
Everything was working fine until I started adding form submission to a module I'm working on.
As soon as I submit the form, I get 'Secure Connection Failed' in all browsers.
I can get to other pages ok, but not the homepage which then also throws the same error.
This persists until I restart my internet connection.
I did the following test to try and find the problem:
I submit the form on my desktop pc - secure connection failed.
I try to go to the domain root - secure connection failed.
I check on my laptop which is connected to the same router - secure connection failed.
I check on my phone using 4g - works fine.
So I seem to be causing a local network wide issue somehow, but I don't know how to fix it.
This is the form, it just uploads an xml file to the temp directory:
<code>$form['file'] = array(
    '#type' => 'file',
    '#title' => t('XML file'),
    );
$form['submit_button'] = array(
    '#type' => 'submit',
    '#value' => t('Import'),
    );
return $form;
</code>
This is the validate function:
<code>$file = file_save_upload('file', array(
    'file_validate_extensions' => array('xml'),
));

if ($file = file_move($file, 'public://'))
{
    $form_state['storage']['file'] = $file;
}
else
{
    form_set_error('file', t("No file was uploaded. Check extension is .xml"));
}
</code>
This is the submit function:
<code>$file = $form_state['storage']['file'];
unset($form_state['storage']['file']);
dsm($file);
$file->status = FILE_STATUS_PERMANENT;
file_save($file);

$filepath = file_create_url($file->uri);
dsm($filepath);
</code>
Any help would be appreciated, it's driving me mental.
UPDATE: This problem disappeared for a few hours, then returned for no apparent reason.
I'm thinking it might be a problem with my internet provider.
Comment: Welcome to Drupal Answers! It sounds like you've already identified the problem here. The fact that you're not seeing the problem solely on the form should rule out any issue with your code, thus it's not really a Drupal-centric question. As such, you might find a more receptive audience on one of the broader StackExchange sites like [Webmasters](http://webmasters.stackexchange.com/)
Comment: That's a pretty messed up situation. Hope you resolve this soon!
Answer: For those who end up in this situation, the reason for this to happen is an error somewhere in your PHP code that is not caught by the PHP interpreter or Drupal itself and the server disconnects to your browser immediately before sending any information (including for example the web server certificate). It is not a network-related error as suggested above here.
To solve the problem, install the xdebug PHP module, configure it and run your scripts again. You will now get far better insight in the cause of the error(s) and it is actually caught before a disconnect.
In my case, the disconnect was caused by a recursion limit hit in my code, which was not caught by the PHP interpreter. Took me a few hours, mostly looking in the wrong direction (network issues, certificate issues).


How to make text look realistic on scanned paper

Question: Please kindly teach me how to create the blurry effect for the background where I will type in words to make them more realistic (the illustration below is what I want to achieve after all)
Any help would be appreciated.
Comment: Please do not delete a question just because it has been answered. The point of this site is not only to help you but also further visitors. Also, deleting deprives answerers of the possibility to gain some recognition for their effort. If an answer helped you, please accept it.
Answer: Just save it as a jpg, zero quality. Repeat if it's not blurry enough.
Increase/re-scale the size of the imported image.
Font & background colour optional.


Any reason why Swype isn't in Play Store?

Question: Have developers of Swype keyboard ever told anywhere why they haven't added their app in Play Store yet? As Play Store is easiest way of installing and updating apps, it'd be nice..
Comment: In short, they get their money from OEM sales. The beta is still relatively easy to get into though.
Comment: Not a technical reason, most hardware supports it. Part of it might be the fact that manufacturer installed versions would conflict with an "official" Play Store version, much like the Beta version. The PR response: "This eliminates confusion and allows us to deliver the best Swype experience possible..."
Comment: @above commenters - is there other versions of Swype that aren't Beta?
Answer: They have here but doesn't give a clear reason.

How can I buy Swype? / When will Swype be on the Android market?
We have considered a direct-download sales model, but there are two challenges to that approach:

Customer Support - Providing Swype users with the level of professional support they deserve is a priority for us. We're still a small (but quickly growing!) company, and we don't have the resources necessary to support a full end-user sales model. It is much more efficient for us to focus on improving Swype and to partner with large organizations like Samsung and T-Mobile who already have customer support structures in place.
Device integration - Swype isn't just an app; it's a keyboard - the most widely used piece of software on a device. It interacts with nearly every single application on the phone. As such, it's more like a system component than an application. For each device release we do a tremendous amount of testing and we always find issues due to the varying components - the OS version, the device hardware, the OEM UI implementation, etc. In addition, some features can't be implemented without an OEM's engineering assistance. We end up doing a large amount of work on each device to be sure that you have a great experience entering text using Swype. So, we appreciate your enthusiasm, but we are not ready to do direct-downloads at this time.


Determine which app version to send apple push notification to (free or paid-for app version)

Question: We have two versions of our app (free and paid-for), and we want to support push notifications for both of them, and they are both using the same server.
So far we can update the user data on the server, so if the user changes from the free to the paid version, we update the server and the user will start receiving push notifications to the paid-for version.
However, I've seen updates for apps in the past, that had a negative impact on the paid-for version, and people have downgraded to the free version.
It's a rare situation, however how can this be handled?
The logic we use to register the token is as follows:
We store the token and a confirmation in the user settings (AppDefaults).
When the user enables push notifications, we check if the app have these settings registered (notification_token and notification_token_confirmed_by_server).
If we have a token, but it's not confirmed by the server (as in the first time you enable push notification for the app) we send the token to the server along with what version of the app it is.
So if the user have both the paid for version on their phone, and the free version, and choose to use the free version for whatever reason, after upgrading the paid-for version, what is the best way to handle a scenario like this?
I saw one app called Draw Something, that was asking the user to uninstall the free version, but I think that's a terrible solution (you can't 'ask' your user to do anything and base your logic on that!)
Comment: Have you find any solution regarding to this issue?
Answer: The solution in the end was to send push notifications to the app version the user last signed in with.
You could alternatively update the server every time the user makes a request assuming you include the application version in the request, however this becomes "chatty" so in the interest of not hitting the database constantly it's a small price to pay


Solubility of Amylopectin and Glycogen in water

Question: The only difference between the structures of Amylopectin and Glycogen is that Glycogen is more highly branched than Amylopectin. How this difference between their structures makes difference between their solubilities in water?
Answer: The answer is relatively simple: Amylopectin is watersoluble, and this seems to be a classical textbook error, which has been propagated now for decades. As you say yourself, the only difference is the number of 1,6-glycosidic branches, which occur every 8-12 glucose monomers in glycogen and every 15-30 monomers in amylopectin.
There are even scientific articles which show that amylopectin is watersoluble, see the references below:

Green et al., Journal of Chemical Education vol 52, p.729 (1975) Which  Starch Fraction  is  Water-soluble,  Amylose  or
Amylopectin?
J. Robyt, Encyclopedia of Life Sciences (2001) "Polysaccharides: Energy Storage"
Answer: The question is incorrect in asserting that the only difference between amylopectin and glycogen is their extent of branching. This is only an incidental difference.
As I explain in more detail in the answer to another post, the key difference is in the topography of their branching.

This leads to spherical size-limited globules, in the case of glycogen, and large semi-crystalline extended structures, in the case of amylopectin.
This is the basis for their different chemical and physical properties within the cell (glycogen is soluble, starch is in a semi-insoluble form), which is all that is of biological interest to me. I cannot adjudicate on, nor am I concerned with, the properties chemists observe when extracts are manipulated in vitro.


Room Impulse Response Domain of Sparsity

Question: I have been studying the problem of room impulse responses (RIRs) interpolation for a couple of months. I am trying to use compressed sensing to reconstruct (at best) the sound field in the room with a better resolution, or (at least) get an RIR at some desired location where it was not measured before. "A better resolution" here means that by having only 20-30 measured RIRs in the room, I want to get the RIRs of, say, one million locations. That is, think of it as a better sampling of the sound field in the room, given the three dimensions of the room.
The problem is, in most RIR interpolation using CS papers, the domain of sparsity is not really described well. Most of the CS algorithms use some pre-defined domain of sparsity. When I think about it, RIRs are not sparse in time (generally around 3 seconds filled with data), neither are they sparse in frequency (an impulse utilizes all the frequencies from $-\infty$ to $\infty$). Does anyone have an idea of the sparsity of RIRs? Or, do you have any suggestions on how to tackle this problem using common and well-studied CS algorithms?
I want to give you my intuition. I believe that RIRs are sparse in some domain inspired by the spatial characteristics of the room. That is, one RIR is not sparse itself, and this is not what we are after. We are after the sparsity of the sound field in some domain. I do not know how to represent such a domain mathematically, but it can be thought of as follows: only a couple of samples of the sound field (a couple of RIRs) are enough to carry all the information of the sound field in the room (low entropy of the sound field), and hence projecting them onto that certain domain that inscribes this property can ease the task of CS. Then we can go back to the original domain (which is a 4D domain of 3 spatial dimensions and 1 temporal dimension) by taking the inverse of the transform that took us to the sparsity domain.
Any help is appreciated, especially if MATLAB is involved.
Comment: I think in this context the idea is to learn some dictionary which will yield sparse representation for many RIR's.
Comment: @Royi Yes fine, but how can I find that dictionary?
Also, we need to enumerate over the possible representations in that dictionary, but then this will become computationally infeasible. Think about it in this way, we need a sparse representation of a sound field that is 4-dimensional. If we want to sample the dimensions of the room in mm, and the sound signal in 44.1kHz, then we will have something like 3000x3000x3000x44100 ≈ 1.2e15 for a 3x3x3 m^3 room and RIR's of 1 second each. This sounds like an impossible task for any commercial computer.
Comment: I am not an expert about RIR. But probably I wouldn't look for a sparse representation per room as a 4D signal but per `$\left( x, y, z \right)$ over time.
Answer: That's tricky.
RIRs are NOT sparse in any obvious physical sense (time, frequency, etc). In fact they are insanely complicated with thousands of degrees of freedom. The amount of relevant physical parameters is very large: we have

Position and orientation of the source
Directional characteristic of the source
Position and orientation of the receiver
Directional characteristic of the receiver
Geometry and acoustic properties of all surfaces including reflection, absorption, diffraction, resonance, diffusion, etc.

First of all you need to define which of this you want to interpolate. I think you want to the receiver location for a fixed source position in a fixed room, but it would help to specifically state that. And what about orientation? Natural sources and receivers are NOT omnidirectional so orientation matters.
I think your best chance to find any sparsity would be in the perceptual domain. In a reasonably well behaved room, when moving a relatively small distances from A to B, the fine structure of the RIR changes drastically (to the point of being mostly uncorrelated), but they often sound very similar. One potential way here would be to derive relevant perceptual attributes, interpolate those and and the resynthesize an RIR from that.
Another approach would be to use a parametric physical mode. The RIR can be broken down roughly in three areas

Direct Sound
Early reflections
Late reverberation

The direct sound can often be calculated directly from the locations, orientations and polar patterns of source and receiver.
Early reflections are probably the most tricky one: You would need to identify the major reflections (Ceiling, floor, etc) in the measured RIRs and try then to interpolate "matching" reflections.
The late reverberation is  fairly straight forward. You can use the frequency dependent decay envelop and just fill the fine structure with white noise. The thing here to interpolate are the reverb times and the direct/reflected energy ratio to the the reverb level correct.
Things get much more difficult in less "well-behaved" rooms. For example if you move from an area where there is direct line of sight to the source to one where the source is obstructed, the RIR changes fairly drastically over a relatively small distance. I don't think this can be interpolated with any reasonable means.
Comment: The interesting part is, people are publishing research papers that employ optimization to solve the problem simply by assuming some sparsity. I am not sure what difference it makes if an impulse is applied (hence RIRs are recorded as direct responses to it), or a sound source is applied (hence the output is a response to that specific sound source) then deconvolution is used to get the impulse response out of that. Is it the case that by applying a normal (hearable) sound we can assume sparsity in frequency (which is not the case with impulses and impulse responses)?
Comment: Another problem is, how can I handle the horrendous high dimensionality of the problem? If I want to apply some 'mainstream' techniques such as trying what sinc interpolation might yield, I need over 300GB of memory, considering the numbers I mentioned in my comment on my question. This also hinders any application of machine learning methods or any type of interpolation over the dimensions of the room.


Can CBC encryption have separate keys for separate blocks of plain text?

Question: Can we have separate key for separate blocks which we get while operating a plain text message  using CBC encryption model? If yes, what are it's advantage? Please enlighten me.
Comment: No, as that would no longer be CBC mode, which is described as using a single key
Comment: that being said, it would eliminate the need for an IV, but make the key change overhead insanely high
Answer: SHORT: The key remains the same. CBC mode is one of the ways which allow block cipher to securely process multi block input.

Block cipher with single key produces same output for same input, as it is relatively common for input to contain duplicate blocks, instead of using block cipher as is, a more complex construct is needed.
The idea of CBC mode is that the ciphertext of the previous block affects encryption of the next block. Specifically, plaintext input is XORed with the previous block cipher text (or with "Initialization Vector" also known as IV) for the first block. This operation is much less time consuming than key change.
So shortly, the benefit of CBC mode is that it allows securely using the block cipher, something that raw block cipher (ECB mode) generally does not allow for multi block messages.
In addition to CBC mode, also numerous other block cipher modes of operation exist. There are circumstances where one of the other block cipher modes of operation is more appropriate than CBC.
The most basic block cipher modes of operation (ECB, CBC, CFB, OFB, CTR) are described e.g. in Wikipedia and NIST Special Publication 800-38A. The Wikipedia article contains great picture, which illustrates the need for modes of operation beyond ECB.


Instructing Linq to Entities to Parse the Result of a Function, Not the Function Call

Question: I have an function outside my EDM that I would like to include in some of my Linq to Entities expressions. The function returns an IEnumerable of Int. An example of how I might use it is:
context.Employees.Where(e => GetValidEmployeeIds().Contains(e.EmployeeId));

The function GetValidEmployeeIds is the function that is returning the IEnumerable. The result of this function isn't something that I can get from the database - I pretty much have to get it externally from the EDM.
When I execute the line of code I get "LINQ to Entities does not recognize the method" - which makes since. However if I break the call out of the expression it works fine:
var validEmployees = GetValidEmployeeIds();
context.Employees.Where(e => validEmployees.Contains(e.EmployeeId));

My question is: Is there anything I can do to instruct Linq to Entities to not parse the function as part of the expression? To instead parse the result of the function. I was hoping there was an attribute I could decorate the method with but haven't been able to find one.
Normally, I would be fine with just breaking out the call and not using it directly in the expression. However, I'm going to be using this call a lot and was hoping to clean up the code a bit.
Answer: No, you'd need to move the function invocation:
I.e., this:
var q = Context.Entities.Where(e => e.Something == DoStuff());

...has to become:
var stuff = DoStuff();
var q = Context.Entities.Where(e => e.Something == stuff);

However, if you can put your function into an Expression, then you can use that directly:
var stuff = DoStuff();
Expression<Func<Entity, bool>> predicate = e => e.Something == stuff;
var q = Context.Entities.Where(predicate);

... so you may be able to clean up your cut and paste that way.


Do photos violate the 4th amendment?

Question: Can a municipal worker photograph over a privacy fence when given permission to enter an adjacent property without violation 4th amendment?
Answer: Maybe and Yes respectively
The relevant legal principle is if the photographs constitute a 'search' within the meaning of the 4th amendment. If they violate the expectation of privacy they are a 'search' and must therefore be reasonable; if they don't they are not a 'search' and their reasonableness is irrelevant.
In Florida v Riley 488 U.S. 445 (1989) the Supreme Court held that observing someone's property from a helicopter is not a 'search'. If that's not a search then looking over a fence isn't either.
Comment: In contrast, using a technology beyond the powers of the human eye, such as X-rays or infrared cameras, have been held to be a search. Similarly, if you flew an insect sized drone into someone's house or covered rear veranda, that would also probably be a search.
Comment: @DaleM The Supreme Court held that infrared cameras were a search because they involved a technology that wasn't in general public use (whereas the skies *are* in general public use, so it's less reasonable to expect privacy for something that's visible from the air). Binoculars are in general public use, so absent some very special binoculars they'd likely be fine.
Comment: @ohwilleke binoculars are ok?
Comment: Depends on how good they are.

Do photos violate the 4th amendment?


What kind of home flooring is this?

Question: I came across a home in Westchester County, NY that was built in 1908. The entry, living room and dining room had an unusual flooring that I have never seen before. It is multicolored, rectangular squares that appear as if they are cork but much harder. It doesn't seem likely that the floor is original and may be over hardwood underneath. Anyone ever seen this before, know what it is?
Comment: Could be tile made to look like cork, or actually cork. (FWIW, cork can be quite dense.) If there are no seams, it could be marmoleum.
Comment: I'd test it for asbestos.
Comment: It looks somewhat like Parquet flooring, but with different types of wood and different sizes, and the pattern doesn't appear to repeat.
Answer: I think this is a patch work of "early vinyl tile" these type of tiles were reenforced with asbestos but the colors look a lot like what used to be available in the 40's and 50's from the homes I have worked on.
The photo looks to have a texture in the center but I think there was something on top that caused that.  the light reflecting off the floor from the door is smooth and that is normal. I call them asphalt vinyl because I don't remember the correct name and they usually have a asphalt like tar for the adhesive that is really horrible to try and clean up.
Comment: My dad put tile like that in our 50's farm house. Only difference was the tiles were checkerboarded with light and vey dark brown tiles. He called it asphalt tile at the time. It was about 1/8" thick (maybe a little bit more than that). As I recall the tile was smooth and hard. Scraps of it would break when attempting to fold it over.
Comment: the texture could be from the underside of a mat
Comment: I think that is spot on wrt vinyl asbestos tiling. The texture looks like remnants of some kind of mat/padding. Seems like it would be a real hassle to dispose of and try to get to an underlying wood floor.

What kind of home flooring is this?


How many amps does it take to power 2 AC's, a freezer, a refrigerator, 2 TV's, and a computer?

Question: I'm making my garage into a living place and I put in a 50 amp line from my house to the garage. The garage has its own fuse box but I want to have an upstairs living area and a downstairs man-cave. I want to plug in a freezer, refrigerator and a couple of AC's and of course upstairs would have a TV and a computer. Am I going to have enough amps or am I going to be blowing the fuse box often?
Comment: What country are you in? Is your AC line voltage 120V (e.g. USA) or 240V (Europe) or other?
Comment: Find out with a Kill-a-Watt: https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=killawatt&safe=off&tbm=shop
Comment: Remember a 240V amp is worth two 120V amps.  So 50A of 240V gives you 50 amps of 120V on each of two poles, or 100A worth of 120V.  If you total up 62 amps of 120V loads, you will be in good shape.
Answer: Look at the published ratings for each of the specific appliances you want to run simultaneously, and add them up. You'll have to do this yourself; we don't know which units you're interested in, and in fact it may affect which ones you purchase.
If the sum is more amps than the breaker will permit, the breaker or fuse will eventually blow when everything happens to make its peak demand simultaneously.
Answer: A 50A (@240v) feeder will be more than enough for this load. If this were a work shop where several larger tools would be run at the same time then you might be pushing it, but a few window A/C's and some electronics will be absolutely fine.
Remember, 50A @ 240V is 12,000 watts. A 10k BTU A/C is around 1000 watts.
Answer: The best way to find out is with a Kill-A-Watt or equivalent. They are sold at most big box, hardware stores, and anywhere electrical supplies are sold. I just bought one off Amazon a couple of weeks ago to see how much power some LED lights I bought will draw. If you want to watch your usage over time there are even many new products that will report via you house WiFi or Bluetooth.


Pivot Tables Excel

Question: I have a question about using pivot tables in Excel.  I have multiple fields listed in the rows section; in the table, one field is grouped by the other.  By default, all of the rows in my pivot table are expanded.  However, I would like to make all of the rows compressed by default.  How can I do this?
Answer: Not sure, but could it be so easy to just collapse the fields, and then save? Next time you open, the fields should be collapsed.

Pivot Tables Excel


Do I have to be a Scrum Master to manage the agile scrums?

Question: I am sure to become a scrum master could really add value to the process I am following, however I believe that the background of the area of the application I am working on help more to get better planning and scheduling done for the project
Comment: I'm voting to close this question as off-topic because [project management is now off-topic on Stack Overflow](//meta.stackoverflow.com/questions/343829/is-stack-overflow-an-appropriate-website-to-ask-about-project-management-issues/343841#343841). Ask these questions on [SoftwareEngineering.SE](//softwareengineering.stackexchange.com/) and [ProjectManagement.SE](//pm.stackexchange.com/) instead. (Unfortunately, this question is too old to be  migrated.)
Answer: I just have an issue with the wording used here - in the question and responses. As a scrum master you would not be managing the project, or running it. The team runs the project in a self-directed way. The scrum master's role is to facilitate and coach.
This may seem like semantics, but I often find that our chosen terms shed light on our underlying tendencies - in this case they may indicate a tendency towards command and control vs. facilitating self-directed teams.
I do agree that reading on agile (not just scrum) is helpful. And having been a member of an agile team is incredibly useful in serving as a scrum master. CSM is like the PMP for classic project management (without the test) for agile - not an indicator of ability, but useful for finding jobs with acronym-myopic recruiters and hiring managers.
There are good consultants out there to help, and useful resources online (see the scrumdevelopment group on Yahoo). I suggest you use both liberally.
Comment: I agree about the role of scrum master. Thats why I used the words like planning and scheduling and not running or controlling the scrums.
Comment: Excellent. This is one of the reasons I think having folks who have been members of scrum teams are often the best options for the scrum master role. My issue was directed more at some of the responses to your questions than to your specific question.
Answer: Becoming a CSM doesn't really qualify you for running a Scrum project either.  Practice is the only preparation you can ever hope for.
The CSM class/cert is valuable still, though.  At the very least, if you don't have a mentor/coach to lean on, you should read..

Agile Project Management with Scrum (Schwaber)
Agile Estimation and Planning (Cohn)
User Stories Applied (Cohn)

and take the CSM course.  You'll be moderately prepared to run a Scrum project.
The biggest thing you can take away from this is:  you'll make mistakes if you're new to this.  If you can learn some pitfalls and see what to avoid, then you can avoid the cost of making/learning from these mistakes.
Comment: Also http://www.crisp.se/henrik.kniberg/ScrumAndXpFromTheTrenches.pdf is very recommended.
Answer: You probably would benefit from becomming a certified scrum master (i recently became one myself).
The scrum master shouldn't 'manage the scrums' but instead be there to facilitate the team - help it remove impediments. The team is self organizing and pretty much manages itself.
Comment: And yeah, being part of a scrum team is what helps you qualify really. The course or reading books will only get you that far...
Answer: If you need the official certification to feel good or to show to your management - go for it. However, you don't have to have the certification in order to apply the Scrum process in your team.
(In fact, requiring a certification to be able to run an agile process would  be very anti-agile to me :-))
Of course, taking a course to understand better what are the Agile principles and how to use Scrum to apply them to your daily work is always good.
Answer: Required:       No.
Recomended: Yes.
But nothing beats experience.
Also note that every team project is unique and thus following a set of rules set out in an agile book may be a good point to start but you will need to adapt the processes to your scrum. Rember the whole point is to let ytour team do their work without adding unneeded processes (note some processes is required).
In my experience management still want metrics that SCRUM does not provide. Personally I humor them for the first couple of months but try and drop them as the scrum processes starts to show that we are making our targets and these metrics become more and more out of line.
Answer: Do not understand scrum master as some kind of manager role!
This is big mistake, but many companies understand it that way. Anyone can be Scrum master.
Sometimes every sprint can have different scrum master. BTW, this is very interesting, because everyone will realize what does it means to be scrum master.
Answer: The discussion about the Scrum Master role starts with the word Master. From my point of view we need to understand the difference between Scrum implementation/transition and taking care of Scrum in an environment where Scrum is already running.

Everybody can become a Scrum Master by attending a course. The certification is NOT an indication of experience or know how regarding agile processes.
A good Scrum Master will take care of the Scrum Flow in an Scrum Environment. He will coach the team and takes care that the team can work undisturbed. But this does not mean, that he can train and teach the team the PO and everybody else how to do Scrum...
To implement Scrum in an organisation or team it needs experiences on overall processes and strategic thinking.

If you have a look at the Scrum Alliance Website you will find the descriptions of the certifications, and what one have to know and prove before getting the certification.
There is much to learn for a "Certified Scrum Master" before he will be a Certified Scrum Coach
If Scrum fails not because of Scrum, but because people THINK they do Scrum ;-)
Doro
Answer: this is an interesting topic, and to some extent extremely undefined... the word "manage" is entailing potentially a whole world of things.
Everybody can "try" to do Scrum, the theory it is not difficult to grasp, what is hard is the practice. Scrum like other agile approaches is very much based on "People and Interactions" and in order to make them happen right, you will have to deeply understand the values, the relationships and the ownerships that the whole Scrum framework describe. That is the hard part, and is a part that requires a lot of practice, and experience to be effectively converted into daily practice.
This of course doesn't mean that you can "learn" yourself, on the contrary, often we hear that Scrum is "learning by doing... and failing" and so "fail often... and fail fast!". All Lean thinking principles, but it is much less trivial than it seems to get the point where it is time to assess results, identify failure, and set best practices for improvement. Being a Scrum Master means that one knows the framework and the relationship between the three main roles, which is way far from saying that he can implement Scrum. That step is in the Scrum Alliance signed buy the CSP (Certified Scrum Practitioner) accreditation, that requires a minimum of one year of practicing Scrum, to be allowed to submit the accreditation form. This is intentionally done because only with practice people will learn what the principle "that in theory are sounding clear" - and you will learn at a CSM Training - really mean, and moreover how to use them to maximize the productivity and efficiency of a Scrum Team.
When we talk about an organization, and we want to implement Scrum, the dimensions to consider, as well as the complexity, are some order of magnitude bigger, and way out of reach of a "simple" - no offence, we talk about mapping value streams, structures, accounting... - Scrum Master. To do something like that, either you take a lot of risk yourself, and you can afford to heavily affect the productivity of your company, or you need someone who has experience in helping companies to transact to agile and Scrum. This is what the CSC (Certified Scrum Coach) accreditation is all about.
Hope this helps a bit :-)


Are rocks and other solid objects just very slow moving fluids?

Question: Will a rock or other solid object under the influence of gravity, given enough time, behave like a fluid and slowly flatten out? Or do the properties of matter that make it solid prevent it from ever deforming in the way a fluid does?
Comment: I really like this question.  I always think of energy as diluted mass as mass can be turned into energy.  I'm working on a question about that too but want to exhaust resources for possible answers before I do. I like the way you contemplate.
Answer: There is no such thing as a perfectly rigid body. The rigidness of a body is given from the chemical bonds that hold the object together, so given enough energy you can deform any material without liquefying it.
There is no real boundary between a really viscous fluid and a really soft solid, as the famous experiment of the pitch drops shows.
This was of course very general, while your answer is quite specific. There exist countless cases of deformed rocks, usually due to mountains formation, as in this image, but the pressure that curves this rocks is much larger than the one exerted by gravity alone. On the surface of Earth, gravity can't slowly deform rocks, it doesn't have enough energy to rearrange the chemical bonds.
Answer: In continuum mechanics, fluid is defined (for e.g. see Fluid dynamics by Batchelor) to be that form of matter which $\textit{deforms continuously}$ so far as a $\textit{shear stress}$ acts on it, $\textit{no matter how small}$ the applied shear stress is. As per this definition, rocks do not qualify as fluids. You may object that it is an arbitrary definition and so it is, but you need some such definition, because you can make anything deform continuously with an appropriate amount of stress.
Answer: Crystals (rocks, metals, etc.) do not flow (unless they are heated to melting). Glass is amorphous (not crystal), but it doesn't flow either (in spite of the "urban legend" that says very old glass has "drooped".
Ice in glaciers is said to "flow", but it's not clear if that is any different from simple plastic deformation (i.e. movement of crystal dislocations (video)), like you get when you bend metal.
I can't say there are no solids that don't flow.
Butter, maybe?
Answer:
Will a rock or other solid object under the influence of gravity, given enough time, behave like a fluid and slowly flatten out? Or do the properties of matter that make it solid prevent it from ever deforming in the way a fluid does?

Samples of Moon rock taken from the surface  of the moon by the Apollo crews are estimated to be around 4.5 billion years old, so they are a few hundred million years older than the oldest Earth rocks.
Assuming that geological processes are slower and less violent on the moon, and that possibly less repeated heating and cooling occurred,  there is a greater probability that these lumps or rock have not been affected by   gravitional slumping for a long,  long time.
If gravity has not caused slumping for that length of time, it could be safe to extrapolate to say it will never occur.


Maps which induce the same homomorphism on homotopy and homology groups are homotopic

Question: I am interested in the following question. Are maps which induce the same homomorphism on homotopy and homology groups homotopic? I am sure the answer is no, however I cannot imagine how to construct counterexamples.
Comment: It seems I was wrong! I must have thought too stably.
Comment: It's an open question. It's not even known if two maps between finite CW-complexes which induce the trivial homomorphisms in stable homotopy groups, is stably nullhomotopic.
Comment: Ooops, thanks Fernando. I did not know.
Answer: Take the composition of a degree one map $f:T^3\to S^3$ with the Hopf map $g:S^3\to S^2$, where $T^3$ is the 3-torus. This composition is trivial on homotopy groups since $T^3$ is aspherical and $\pi_1S^2=0$. It is trivial on $H_i$ for $i>0$ since this is true for $g$. If $gf$ were nullhomotopic we could lift a nullhomotopy to a homotopy of $f$ to a map to a circle fiber of $g$, which would imply that $f$ had degree 0, a contradiction.  Thus $gf$ induces the same maps on homology and homotopy groups as a constant map, but it isn't homotopic to a constant map.  (I forget where I first saw this example, maybe in something of Arnold.)
Comment: Your answer is so brilliant that I just went blind.
Answer: Phantom maps provide a large class of examples of maps which are not homotopic to the constant map, but which induce the zero map on both homology and homotopy groups. There are uncountably many distinct homotopy classes of phantom maps $\mathbb{C}P^\infty\to S^3$, for example.
Edit: In many cases one can determine whether nontrivial phantom maps can be found between two spaces by investigating rational homotopy invariants. Some great references include Phantom maps and Rational Equivalences by Roitberg and McGibbon, or McGibbon's survey in the Handbook of Algebraic topology.
Comment: James, thank you for your answer. I have read the definitions and it seems that phantom maps are $f:X\rightarrow Y$ such that restriction of $f$ to each skeleton is null-homotopic. So, this definition is of interest when $X$ is infinite dimensional. Is there some theory for finite complexes? For example, when $X$ and $Y$ are 2-dimensional, how can we check that map $f:X\rightarrow Y$ satisfy $0=f_*:\pi_2 X \rightarrow \pi_2 Y$.


Will the bulb glow in this circuit?

Question: Will the bulb glow in this circuit? Why not? I think the bulb should glow because there's a potential difference.
Answer: The bulb will not glow. There is a potential difference between the open electrodes of the batteries but none at the terminals of the bulb. The "circuit" is not a circuit, it is open. Or you could consider it a circuit with an infinite resistance between the electrodes of the batteries. This also explains why there is no current in the circuit.
Answer: It will not glow until the circuit is completed.  The batteries are not connected so there is no completed path for the current.  Connect the positive and negative terminals of the two batteries and then it will glow.
Comment: Why do the cells need to be connected for current to flow? The Bulb is connected to a positive end and a negative end.
Comment: The circuit as drawn is an open circuit.  Two of the battery terminals are not connected to anything.  They need to be connected together or be connected to ground.  Current needs a completed path to flow.  Otherwise it would need to 'jump across' the space between the unconnected battery terminals, which it can not do (in the steady state).
Comment: Why can't the current flow from the left cell to the right cell or vice-versa?
Comment: It needs to flow from the positive terminal of the left cell to the negative terminal of the right cell (where it has a path now), and then flow from the positive terminal of the right cell to the negative terminal of the left cell (where now it has no path).  If you think of current as moving electrons, then the electrons need a conductor between the terminals to flow through.  Otherwise charge would be accumulated somewhere and there is no capacitor (charge accumulator) in this circuit.
Comment: The current flowing out of the battery must equal the current flowing in to the battery. see  https://www.slideshare.net/HimanshuBatra2/circuit-laws-network-theorems  --these are Kirchoff's circuit laws.
Answer: The circuit must be complete for the bulb to light, otherwise no current will flow. A current will flow for a very short period of time, but then a concentration of charge will form that will create a potential difference negating that potential difference from the batteries.

Will the bulb glow in this circuit?


What is the difference between general purpose ADCs, Audio ADCs and video ADCs?

Question: An ADC merely converts an analogue signal to a digital one. Why then do we have special ADCs for audio and video application? What if one was to use general purpose op-amp in them instead?
Answer: First, I think you use the word "merely" very lightly.  ADCs are some of the most complex, challenging mixed-signal systems in use.  To meet different performance targets practical ADCs use many different architectures (the most important right now are sigma-delta,  SAR, and Pipelined).
ADC design is characterized by very painful tradeoffs between speed, accuracy, noise, and power dissipation.  For example, to increase the SNDR of a thermal-noise limited ADC by one bit increases the power roughly 4X (because noise is proportional to sqrt(C)).
To first order (and this is VERY rough, mind) you can think of the speed-accuracy product of an ADC to be constant.  So, to make an ADC very accurate it must be slow, and, conversely, the fastest ADCs (now at 40 GS/s and beyond) have very low resolutions (4 - 6 bits or so).  This is due to a combination of factors such as oversampling (taking multiple samples and averaging) which reduces the speed, and the capabilities of sample-and-hold circuits to acquire signals at needed accuracy (for example, a 10-bit sample-and-hold needs to sample the input signal to an accuracy of about 0.1%.  A 16-bit sample-and-hold needs to sample the input to an accuracy of about 0.001% (!).  Accuracy, namely signal settling, takes time.
So, an Audio ADC is typically 16-24 bits, and has an effective sampling rate of 44kHz to 96 kHz or more.  (keep in mind the ADC is sampling MUCH faster than this because of sigma-delta modulation).
A video ADC is typically 8-12 bits (sometimes 14b) and samples between 10 - 40 MHz.
An ADC in a Gb Ethernet chip would be more like 6 - 8 bits @ 125 MHz.
An ADC in a 10Gb Ethernet chip would be more like 6 - 8 bits @ 1.25 GHz.
An ADC for a DDR4 transceiver or a radar receiver may be more like 4 bits at 10 GHz.
And so on.  The reason there are so many ADCs is that there are so many places in the parameter space.  Do you care about noise?  It will cost you.  Do you care about power?  It will cost you.
A general-purpose ADC is a balance of different factors that has use in a variety of applications, but can't perform at extremes of speed or accuracy.
Comment: @akohlsmith, the front end of Gb/10Gb Ethernet is actually fast enough and nuanced enough that calling it analog is not an unrealistic claim.  As an example, consider this link to a Vitesse GigE chip.  If you click on the small block diagram to the right to enlarge it, you can see that they choose to call out blocks labeled ADC and DAC https://www.vitesse.com/products/product/VSC8221
Comment: @CortAmmon interesting, I learned something new today. Thanks!
Answer: A general-purpose ADC is expected to work reasonably well capturing any kind of frequency content from DC up to its bandwidth limit; the accuracy at recording any particular frequency content should be unaffected by the presence of other frequency content.
An audio ADC is expected to work reasonably well at capturing audio signals in a range which does not extend to DC and typically doesn't go as high as many general-purpose ADC devices.  While the accuracy with which a general-purpose ADC can capture content at one frequency should be unaffected by other frequencies, that is not so much of a requirement with audio ones.  The ratio between the loudest allowable signal and the amount of noise on the quietest detectable signal should be high, but it is often acceptable for the ratio between the loudest signal and the amount of noise that would be present on that signal to be much lower.
A video ADC will need to operate much faster than many general-purpose or audio devices, but will often not require particularly good specifications for linearity.  Further, while the delay between a signal appearing on the input of a general-purpose ADC and its being propagated through to the output will usually be no more than two sample times, that time may be longer on a video ADC.  When an ADC is used in a control loop, it's important to minimize the the delay through the ADC, but when delay is acceptable it allows the hardware of the ADC to be simplified.  An 6-bit ADC that needs to yield "instant" results will need 63 comparators, and an 8-bit one will need 255.  Such a design is called a "flash" ADC, and the cost of flash ADCs increases exponentially with resolution.  If one doesn't need an ADC to be fast, once can use a successive-approximation ADC which takes a certain amount of time per bit, but only requires circuitry proportional to the number of bits.
A modern video ADC will work as a cross between the two approaches.  Any particular sample will have to be processed in multiple steps through different parts of the ADC, but different parts of the ADC can all work simultaneously.  Once the first stage of a pipelined ADC hands a sample off to the second stage, it can begin work on the next sample immediately; it doesn't have to wait for the remaining stages to finish their work on the first sample.  A video ADC might this take 125ns to process a sample and yet be able to process 64 million samples per second.  The fact that data from the first sample won't be available until after eight more have arrived is a tiny price to pay for having number of simple stages rather than one really massive one.
Answer:
General Purpose ADC  - These are the general run of the mill ADCs that you would use for your load cell, temperature sensor, whatever. They come single ended and differential, all sorts of
Audio ADC - There are two things that can make audio ADCs special. First, they usually have AC coupled inputs, meaning instead of a 0-5V range, they'll have a -2.5-2.5V range. Most these days will be 24-bit. More often than not, they'll have an I2S interface, and an onboard DAC for each ADC.
Video ADC - Consider old school 640x480 VGA signals. It had a 25MHz pixel clock. Video ADCs have to be insanely fast.
Answer: In broad-brush terms, it's largely about bandwidth, and quantisation fidelity.
Audio requires relatively low speed conversion rates (e.g. 44.1kHz), but typically 16bit resolution or higher conversions.
Video is far higher conversion rates (several MHz), but usually much lower resolution - say, 8, 10 or 12 bits per colour channel (RGB).
There are other applications where an "audio" or "video" ADC is appropriate, too.
And it's important for these types of applications (and others) for the ADCs to sample multiple channels simultaneously (e.g. left + right audio, or R G & B video), which essentially doubles/triples the number of ADCs needed in the system/on the chip (which is of course more expensive), whereas "general purpose" ADCs are often NOT able to sample multiple channels simultaneously, they're just a single ADC with a multiplexing switch in front of them to select the desired channel - so if you want to sample all 4 channels, you sample #1, then #2, then #3, then #4.  If that difference in timing between when the samples are taken doesn't matter to you, then this kind of multiple-input ADC is fine.
As for the op-amps involved in the front end analog circuitry of ADCs, again these are specified for a bunch of parameters that are appropriate to the bandwidth & amplitude of the signals being manipulated - GainBandwidth-product, input offset voltage, voltage ranges, linearity, etc.  The term "general purpose" op-amp might be a bit mid-leading, but it basically means it doesn't excel in any particular spec; whether or not that's good enough for a particular application is up to the designer to calculate.
edit:
also, many ADCs have differential inputs, which usually require differential op-amps.
Comment: Also, most "op amps" inside an ADC aren't really op amps but transconductance amps since you don't need a low input impedance when you're only driving capacitors.
Comment: typo alert:  by low input impedance I meant low OUTPUT impedance.


Is there any material insulating in one direction?

Question: Is it possible for a material to be insulating in z direction but conducting in x and y direction? If so want would be the DOS diagram looks like? Will there be a band gap or not?
Comment: https://en.m.wikipedia.org/wiki/Topological_insulator
Comment: @physicopath It is the surface state that is conducting in the case of topological insulator. I was wondering if strong anisotropy would lead to conduction in one direction (bulk state) but insulating in another.
Comment: what about graphene?
Comment: Hi and welcome to the Physics SE! What are your thoughts? Please note that you are expected to have thoroughly searched for an answer before asking your question. And it's important to detail where you're stuck and why, in order to attract good answers. You can consider checking the [advice on writing good questions](https://physics.stackexchange.com/help/how-to-ask).
Answer: It depends, it depends. Its difficult to answer your question compeltely because there are so many possible definitions for "materials", and what do you mean by direction? I'm not trying to be pernickety, but are you talking about individual molecules, crystals, or macroscopic electronic devices? All will have different answers. Do you mean direction on the molecular scale, or on a device?
But, what you might find interesting to consider is conjugated polymers.
These are long, thin conducting plastics. The simplest is called polyacetylene. It looks like this

We can make it as long as we want. It conducts because of the double carbon bondss. One valence electron on each double carbon atom resides in an orbital pointing upwards, which is orthogonal to the other three sigma-bonds.
All the upwards pointing orbitals combine with each other, to form a molecule wide delocalised set of orbitals. Through some oxidation reaction, some of these electrons will be lost.
Now you have a one-dimension electronic band, and the electrons within this band become mobile when it is partially emptied. If you want a mathematical rigour this can be described in the tight-binding model. The DOS looks like

Where $E_{v}$ corresponds to the top of the valence band.
These polymers will have good conductivity in one direction. Conductivity in the perpendicular direction depends on how well you can align your molecules and how close they are together. You could extend this to be two dimensional by attaching strips on the ends of the polymers.
We can adapt this molecule to be a good semiconductor by adding some more fancy molecules onto the backbone. A particular one of research interest at the moment is pentacene:

These have HOMO and LUMO levels, analogous in many ways to the valence band and the conduction band, and are organic semiconductors. According to Sigma - its HOMO and LUMO energies are HOMO $5eV$, LUMO $3eV$ (with respect to the vacuum level). - Thats a band gap of $2eV$
tl;dr
Is it possible for a material to be insulating in z direction but conducting in x and y direction?  - Yes - molecules which only have one dimension.
If so want would be the DOS diagram looks like? - Depends on the orbital geometry.
Will there be a band gap or not? - Depends on the material (but generally yes, but you have to think of the orbitals - its quite different from metals, but thats a story for another day).
DOS ref: (ref: http://www.w2agz.com/Publications/Science%20&%20Technology/IBM/30%20(1979)%20Band%20Structure%20of%20Polyacetylene,%20(CH)_x.pdf)
Answer: Consider 3D crystalline system. in x and y-direction, there is a hopping term but there is no hopping in the z-direction. consequently, the system has a dissipation in XY plane but in the z-direction, the system has a dissipationless character.
In an effective manner, we try to describe a system with anisotropic mass which for a z-direction diverge. this system has a metallic character in XY plane but insulation in the z-direction.
Comment: I don't see how this provides an answer to the question.
Comment: There is no band gap but slop of dispersion along z-direction is vanish.
Comment: That isn't really a 3D crystalline system - it's just a stack of completely unrelated 2D systems.
Comment: You must provide anisotropic situation which can be constructed by the stack of 2D systems.


As a grandma what can I say if my daughter sits and watches her 4 year old hack at her hair

Question: I find it very distressing to witness the disfiguring of my grandaughter while my daughter says it is ok for her to cut her own her hair, from beautiful long curly hair to a hacked haircut. What can I do about this?
Comment: I would need more information to offer an opinion on this. Is your daughter in a depressed funk, with no energy or enthusiasm for enforcing boundaries and no care as to what her own daughter does; or did she have a little discussion at an appropriate level with the 4 yo about it beforehand, explaining that if she wanted shorter hair it would be easier to get it to look nice and even if they went to a hairdresser, or even if she let Mummy cut it, but the 4yo was scared of letting anyone near her head with scissors so they agreed between them she could do it herself?
Comment: "She's going to be the best hairdresser in the world one day"
Comment: Better for the child to get it out of her system while she's still young and with parental observation than hiding it and fearing consequences later.
Comment: [continued...] Or something in between, or something else entirely of course. I would say that ultimately your granddaughter's appearance is not really your concern, but if the scenario is closer to the former one I described, you might want to try to get your daughter some professional help.
Answer: Assuming you're not your granddaughters legal guardian, remember that your granddaughter is not your daughter.
When a parent (read: any legal guardian) is present, knows what is going on and has okayed it, you are not to interfere. The only exceptions are when she is (in danger of) hurting herself, or hurting you or something of yours.
If those exceptions do not apply, leave it be, how hard that may be, and take it up with your daughter instead, in private.
Comment: "and take it up with your daughter" **in private**. You shouldn't question your daughter's authority in front of the child by arguing .
Comment: I agree; added.
Comment: "*The only exceptions are when...*".  Or violations of the law, of course.
Comment: Regarding "You shouldn't question your daughter's authority in front of the child by arguing" I agree so far as it is arguing.  Where questioning a decision in front of others can be done openly, without much if any emotional charge, and in a genuinely open-hearted way it can be wonderful to model healthy discussion, disagreement of opinion, and negotiation of that type of conflict.
Answer: Honestly, unless your daughter gave her a large sharp knife to cut her hair with, it's not abuse or anything. It sounds like your daughter is letting her daughter take some control over her own appearance.  If, once she's done, your granddaughter is displeased with her haircut, take her to a hairdresser for a repair.  If your granddaughter likes her hair, LET IT ALONE.
Else, if you find it distressing, I recommend you remove yourself from the situation (either physically, or by reading a book or otherwise distracting yourself).
Comment: +1 to if she is displeased take her to a hairdresser.  That's the most positive thing you can do by far - once she's made her mistake, a friendly offer to help fix :)
Answer: The answers provided so far are a bit brusque, but I'd suggest that's because, as you most likely know, we all want to be free to raise our children in our own way -- sometimes quite different from how our parents raised us.
I remember telling my mother when I was rather young that I wasn't going to learn from all of her mistakes: I would sometimes make my own mistakes and learn from those and that is OK. (I've always been rather precocious, lol.)
To me, parenting isn't about controlling your child, but teaching them to think about choices, considering the positive and negative consquences and then letting them (where it isn't dangerous) make their own decisions.  To that end, when my daughter at 12 wanted to dye her hair, I talked with her about the consequences to ensure she understood them, but ultimately let her make the decision to dye her hair... she now regrets it and "never" wants to dye her hair again.
As mentioned in one of the comments, a private conversation with your daughter to understand her rationale may be all that's needed for you to accept the parenting decision she has made.  If her decision seems illogical, then it may behoove you to kindly offer a consideration of all the facts at hand for your daughter to re-evaluate her parenting methodology, but ultimately provided she doesn't allow or cause harm to her daughter, her choice of parenting is in her hands -- we don't always like or approve of the decisions our children make, but did our parents always approve of our decisions?
Answer: The perspective we have taken with our kids is that while we would love them to have great hair all the time, it is fun for them to mess with it, and it can help get it out of their systems.
We'd rather they did it now than when they are going to job interviews as adults, so we encourage them to do what they like - and this has included a bit of self haircutting, mohawks, colours etc. It's fun.
My parents maybe wouldn't have liked it, but it's only hair.
I'd suggest relaxing and realising it won't make your granddaughter a bad/ugly/crazy person, it doesn't make your daughter a bad person, and it definitely is not your business unless either of them wants to make it your business.
Answer: I happen to believe a parent's responsibility doesn't end when her children are grown, it just changes somewhat.  Does it bother me when my Mom offers unsolicited advice about my own children?  Sometimes yes, but I understand there are things I can and do still learn from her, that it's still part of her role, and that I am free to take what she says under advisement and still do it my way.
She is kind and wise enough to not undermine me in front of my children, to use a degree of tact in bringing things up, and to leave it alone after she's given her input.  It sounds like you are extending that same courtesy to your daughter.
Understand there are things everyone likes and doesn't like about their own upbringing, and often parenting style is deliberately chosen to be different in certain areas from one's own parents.  I'm sure you can think of things your mother did that you didn't want to continue to the next generation.  Who knows, maybe one of those those things was even that your Mom never stopped you from making mistakes like hacking your hair!  That's not necessarily a sign of disrespect.  It's a sign that your daughter wants to learn both from your strengths and perceived weaknesses.
I would go with the Stephen Covey approach of "Seek first to understand, then to be understood."  Have a conversation with your daughter about why she feels it is important to her to let her daughter cut her own hair.  Listen completely before making any judgements.  Once you fully understand her reasons, you might be surprised to find you actually agree.  If you still disagree, you will have a better understanding of how to share that in a way she will understand.
A lot of parents are permissive because they don't want to stifle their child's creativity, but sometimes it's hard to recognize there is a middle ground where children can be creative without being destructive, or to recognize the difference between stifling and providing supportive structure and guidance.
There is middle ground between letting a four year-old cut her own hair and preventing a four year-old from having any say at all about her own body.  A good compromise would be to let the daughter choose her own style, but get it cut by a professional so it turns out how she intended.  I think it's a great role for a grandparent to suggest alternatives your daughter might not have considered, while taking her unique parenting style into account.
Answer: Have you talked to your daughter about it? Do you understand why she's allowing it? It's a bit weird.
If she's insistent, that's that. This is odd enough, I can't imagine anyone being surprised to be asked what's going on.


Does the orbital decay of Triton affect Neptune's rotation?

Question: Just a quick question regarding Neptune. Because Phobos is spiraling in towards Mars, Mars' rotation speeds up. Does the same thing happen with Neptune's rotation?
Comment: This is an interesting question, and since Neptune is a gas giant rather than a rocky planet, there are some interesting differences. I think this question deserves a good answer that makes this difference clear.
Comment: The obvious answer is "yes, because Newton." What you need to consider is the magnitude of the effect, roughly by comparing the mass ratio of Triton/Neptune as compared with Phobos/Mars , to see if it is significant. [ the calculation is left as a homework problem :-) ]
Comment: I don't have enough information for an answer, but some things to keep in mind: Neptune has a lot more moons, and Neptune has differential rotation since it is a gas giant.
Comment: Let's just say it  you have a moon and . planet, the moon orbits retrograde. Would it happen?
Answer: In short, the answer is yes -- because of the conservation of the angular momentum.
The orbital angular momentum scales as the square root of the semimajor axis. Therefore, if the satellite's orbit is shrinking, the orbital angular momentum is getting smaller.
Had Triton's orbit been prograde, I would have said that, to compensate for the said decrease in the orbital angular momentum, the rotational angular momentum of the planet must be increasing (i.e., the planet must be rotating faster).
However, Triton's orbit is retrograde. So the sign of the rotational orbital momentum is opposite to that of the planet's spin. (To simplify things, I am neglecting the inclination of the orbit on the equator.) In this situation, our conclusion will be opposite: to compensate for the decrease in the orbital angular momentum, the planet must be rotating slower.


Content export and import / content deployment

Question: It's easy to deploy configuration of content types, views and so on...
What are the options for deployment of content (nodes) between different environments?
Answer: The Default Content module uses cores REST/HAL/Serialisation API's to export content to JSON. You put the content into you_module/content/[entity_type]/anything.json and the content is automatically imported when you enable your module.
Answer: Historically you had options such as leveraging the Migrate module or Feeds to achieve this (Migrate introduced the idea of continuous migration of content). While this would still be viable options (once contrib is ready), it seems the common preferred approach nowadays would be to have a 'content hub' from which you can pull content to various sites over RESTful web services. By leveraging Drupal 8's RESTful capabilities, you can totally define a deployment strategy over JSON/HAL+JSON, granted you'd lock down authentication/permissions enough to not expose your content to unprivileged resources.
Answer: Also see the Deploy module:

The Deploy module is designed to allow users to easily stage and preview content for a Drupal site. Deploy automatically manages dependencies between entities (like node references).

This screencast shows it's amazing capabilities.
Answer: For continuous content deployment not using Deploy's Web services, there's Content Synchronization.

The content synchronization module provides a mechanism to export single content items, or all content items, from an environment, and move them to another, effortlessly.


Why should the ray become parallel to base in a triangular prism at minimum deviation?

Question: In the case of minimum deviation, the refracting angles at two surfaces are equal. Then the ray inside the prism should be parallel to the base only if it is isosceles triangular prism. But everywhere I read they haven't mentioned this condition. Is this correct ?
Comment: You are correct - the theorem assumes an isosceles prism, with the base at having the same angles with both of the sloping sides.  It is usually apparent in the diagram.
Answer: If the angle of the ray to each of the two surfaces of the prism is the same, it follows from symmetry that you should be able to flip the scenario left-right about an axis that bisects the angle connecting the surfaces, and have the same exact picture.
But this implies that the ray inside the prism must be perpendicular to that axis, which would put it horizontal to the base of the prism if, and only if, it is isosceles.
You are right, if you want to claim that the ray is parallel to a surface it is not interacting with, then you need to specify the relationship of that surface to the other surfaces..