Is it possible to switch to a different squad within the platoon of which you are part?

Question: I joined a squad that was part of a platoon, but noticed that I preferred to join another squad within the same platoon. Is it possible to make that switch?
Answer: Yes if you go to your social bar (the one with 2 people shown) you can actually switch by the plus sign next the the squad you would like to join. I would suggest tho u stay in a squad of about 5 people.
Comment: I didn't see the plus sign. Maybe I didn't look well, or could they have been private squads?
Comment: may be they were private
Answer: If you are a leader of the unit, you can reassign people to squads, including (I think) yourself.
If you're not a leader, you can use chat or voice to ask the leader to transfer you to the other squad.
If you're not a leader and you want to do it yourself, there is no direct UI for it as Young Guilo wrote in April 2013. However, what you can do is make sure there is an open slot in the squad you want to join, note which squad it is you want to join, then leave the platoon, and join the other squad using the list of all squads, which will list each available squad. This won't work if the platoon is set not to allow people to join, or if the squad becomes full before you manage to join it.


Is it possible to charm/intimidate The Illusive Man on Mars with only an imported ME2 character?

Question: I just started my second playthrough of ME3 with a second ME2 imported character, and on Mars, I still didn't pass the rep check for The Illusive Man.  My Paragon bar was basically full in ME2 (I passed the Morinth check).  I started with total rep slightly below the first tick, which I assume is what's required to pass that rep check, and quickly surpassed it during my first visit to the Citadel.  My question is how can I make up the difference before speaking with The Illusive Man, or is it even possible in my case?  Is it only possible with an imported ME3 save?
Answer: Its possible to do it with an imported ME2 save, I just did it recently on a new playthrough.  I didn't check to see what my rep was at the time, but all I know is I was able to choose the paragon option.
Also, you may want to consider going back to redo this choice if you can:

 In order to persuade the illusive man at the end of the game you'll need to have passed every paragon/renegade check in the game with him, this one also counts.
Comment: I may just do that (which basically means completely starting over, but what ever).  My FemShep doesn't look quite right anyway (stupid failed custom appearance import).
Comment: @MBraedley yea, even if you imported the shepard, I found it better to install a new face
Comment: This was after trying to get it close.  It might partially be uncanny valley, but I still messed up on some of the facial features.
Comment: @MBraedley yea, the uncanny valley is a big issue with this game, the little boy in the game and the girl in the trailer just does not look normal


Why are vacancies in solids called as equilibrium defects?

Question: My professor, when discussing about Random Walk model during diffusion in metals said that "Vacancies are equilibrium defects but dislocations are not". I could not understand why. Why is it so?
Comment: https://www.researchgate.net/post/Why_dislocations_are_referred_as_non-equilibrium_defects
Comment: @SolarMike , what has equilibrium have to do with a defect like vacancy?
Answer: Imagine you have two boxes separated by a removable partition. Each box is filled with a different pure monatomic gas. When you remove the partition, the gases mix. Their equilibrium state tends toward an equitable mixture at every point in time. The likelihood of the gases spontaneously separating is essentially zero for any appreciable number of atoms. This is modeled by statistical mechanics, and occurs for any similar system consisting of multiple mobile components.
Solids are no different from gases in that they obey the principles of statistical mechanics. In the case of a crystal lattice, vacancies are lattice points with no atom, i e. empty space. All solids are constantly exposed to empty space at their surface, and tend to mix with it. This may sound strange, but remember that atoms in a lattice are mobile, and can shift lattice positions if a neighboring space is available. All of the lattice points at the surface have lots of space available outside the crystal. The same applies at grain boundaries and at dislocations. So by random atomic movement, empty space can diffuse into the lattice and create vacancies. As we established with the two-gas setup, the empty space and solid tend to be in some mixed equilibrium, i.e. the equilibrium concentration of vacancies is non-zero. The only detail remaining is that the mixture isnt equal because the atoms of the solid have strong cohesive forces binding them together. Unlike gases the crystal doesn't evenly diffuse about the room and instantly vaporize. At least, in equilibrium it wouldn't (discounting vapor pressure)!
As for dislocations, their equilibrium concentration is zero because they don't spontaneously form, but can spontaneously leave crystals. Recall that dislocations form in response to a net shear creating an "excess" half plane of atoms, or alternately an "excess" half plane of vacancies. This occurs by a process called "slip".  Slip does not occur in equilibrium. Getting a half plane of vacancies into the crystal, all organized along a plane, and done spontaneously, is simply not going to happen by chance. In contrast, an existing dislocation can move spontaneously by absorbing or emitting dislocations in a process called "climb". If a vacancy is absorbed, the half-plane of atoms decreases in number, moving the dislocation line in that direction. If a vacancy is emitted, the opposite occurs. If the dislocation line reaches the surface, it is no longer a dislocation. Thus dislocations can leave the crystal, but can't enter, resulting in a net equilibirum concentration of zero.
Answer: Nature will always try to minimize the number of dislocations and grain-boundaries, whereas in the case of vacancies, there is an optimum number that will lead to the lowest Gibbs energy.


Is it possible to integrate Salesforce with SDL Tridion?

Question: I would like to know how can we integrate SDL Tridion with Salesforce.com. The idea is to use the content developed by Tridion to use in self service portal in salesforce.com
Answer: You have to be careful when you say "SalesForce" because it can mean a lot of different features... SalesForce is a series of apps and they all have different requirements.
Given that you mention "self-service portal" I assume you're looking into integrating with Force.com, and for that I see a couple of possible solutions:

Expose an OData endpoint and consume it from force.com - they have rest connectors, and APEX can use content delivered like this
Write a set of deployer extensions to deploy and undeploy to force, then consume the content "natively" in your APEX app.

We do expect developments in the integrations between Tridion and SFDC, but there's nothing in the current Tridion suite to give "out-of-the-box" integration.
Comment: +1 for suggesting oData; Tridion provides this integration API out-of-the-box and any application that can consume content over oData doesn't need a connector to Tridion specifically
Answer: As far as I know, direct out-of-the-box integration of SDL Tridion with Salesforce is not available. However, a custom solution can be built to achieve this by using SDL Tridion Extension Points and Salesforce APIs on the same note as you get Drupal's Salesforce Suite which allows to have an integration of Drupal with the Salesforce.
Comment: Can someone explain me the reason for downvote, so that I can take care in furture.
Comment: It was not me that down-voted your answer, but I suspect that it does not provide enough detail.  "Using SDL Tridion Extension Points" is very generic.  I think your answer could be improved by stating exactly which extensions point(s) could be used (as Nuno has above) and/or providing details about the SalesForce API or possible connection points.


Disabling BGP dampening that is enabled for a long time

Question: I have many dampened routes for now. What could possibly happen if I will disable BGP dampening that is previously enabled?
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 provide and accept your own answer.
Answer: Prefixes get dampened because they are not stable; they are added and withdrawn multiple times. This is a sign of network instability. Having prefixes constantly added and withdrawn places a large burden on your routers, and it can cause lost traffic, broken TCP connections, etc. BGP dampening is protecting your network from the worst of this instability. What you need to do is determine the root cause of the network instability, and correct it.
It used to be (and still is with some companies) that if you have a lot of network instability, other ASes would basically cut you off and refuse to peer with you, or you would cut off and refuse to peer with other ASes exhibiting such instability, until such a time as the unstable AS proves it has corrected its problems.


What do abbreviations in movie scripts stand for?

Question: What do abbreviations in movie scripts stand for? For example, EXT., INT., (O.S.), (V.O.), ...
Comment: Relevancy is matter of perspective dude. anyway, if you're looking for default/standard abbreviations, then you should mention it in your question. Even though if there is *default standard abbreviations* like you say, it'll still be a broad area to cover, isn't it? and how can one consider which are the standards? I don't know if there's any official guidelines , if there's then it'll be usable as a foundation to get what you're looking for
Comment: @Vishwa, I don't think your comment is relevant here. Since there are a number of default standard abbreviations in movie scripting used by all script writers
Comment: Unless you specify which abbreviations you're looking for, I'm not sure this'll be a straightforward question. since there could be movie specific, writer specific, era specific etc...
Comment: @Vishwa, If a question is a straightforward question or not is a matter of perspective.
Comment: yes.. by all means *if*
Answer: These abbreviations represent the type of scene and the area where it's being filmed.
From this glossary and this page from abbreviations used in movie scripts,

EXT. => Exterior
INT. => Interior
O.S. => Abbreviation for Off Screen, denoting that the speaker is not resident within the scene.
V.O. => Abbreviation for Voice Over, denoting that the speaker is narrating the action onscreen.

You can find more abbreviations on the linked pages.
Comment: Really, the only other common ones I can think of would be FX/SFX (sound effect) and MOS (silent)--oh, and POV (shot from the character's point of view).
Comment: MOS= Man of Steel ;)


What to do about bathroom ceiling peeling

Question: It was painted early in the year. Now large parts of it are peeling into large slices of paint, like an orange. It's still attached, just being peeled away and hanging from the ceiling. Under the white paint or above it, a grey ceiling unaffected.
Answer: In all likelihood, you put a modern water based paint over an older oil based paint.
Peel off the paint, Put on a mask and go over the old paint with a random orbit sander just to rough it up a bit.  Wipe off the dust with a damp rag, and let it dry.  This would be a good time to go to your favourite orange or blue store to get some primer.  I happen to like Kilz, particularly for bathrooms.   Prime the ceiling, and let it dry thoroughly.
Now paint, letting it dry completely between coats, and avoid using the shower for a couple of days.
Answer: It's because you painted over a glossy surface.  The entire purpose of gloss in paint is to provide a surface that lends itself to easy cleaning and resists contamination by dirt, water, oils or ... Paint.
The right way to paint a glossy surface is to

If you're changing paint types, wait until the paint is old enough that it's no longer chemically active.
clean it... Because dirt and oils will contaminate the new paint, and best to do it while it's still glossy.
knock the gloss off any practical way.  You're done when it's not very glossy anymore.   I'm a big fan of green scotchbrite pads, they are readily available, make a minimal cut, and are easy to work wet if you're worried about dust.  Not as big a fan of sanding since that will blow out high spots, re-contour the surface and miss low spots. If the sander punches through to the substrate, now you have to prime, or the substrate will show through.
a last cleaning to remove sanded material.
If the old paint is uniform and in good condition, I would consider skipping primer unless the topcoat requires a special primer.

Topcoat should stick fine at this point. It will be molding into, and mechanically engaging, the microscopic "tooth" of roughness in the old paint.  So the type of old paint shouldn't matter too much.


Game engines for iPhone vs. native iPhone sdk development

Question: What are people's opinions and/or experiences with game engines such as Unity or Torque Engine? If one were new to iPhone game dev is it worth it to learn one of the engines? What is the performance difference between apps generated by those engines vs a natively built App using the sdk?
Answer: Both will equal the performance of what most people could write themselves (i.e. if you're not an experienced game engine developer).
Whether it's worth learning (and buying since both Unity and Torque cost for iPhone development) you'll have to ask yourself two questions:

Is my game idea suited the engine?
Is my passion for programming or game design?

Looking at the range of games made with Unity, it seems very flexible because although it is a 3d engine, lots of 2d games have been made with it. The downside of using Unity for something very simple (say, a match-3 tile game) is that it's a bit over the top in terms of download size.
On the passion issue, some people like programming a lot and will always feel it's better to write the engine themselves. And that's OK. But if you have a great idea for a game and just want to 'bring it to market' as soon as possible, and it requires 3d rendering, character animation, that sort of thing, using Torque or Unity is going to get you there a lot faster.
Answer: If you want to do 2d development you should have a look at cocos2d iphone it is implemented in cocoa free open source and very easy to pick up
Answer: I think time to market is important to consider - if your going to burn out after a short time and of the engines mentioned above will allow you to build and launch a game quickly compared to writing the engine & game from scratch.
Like U62 said, where is your passion?
Currently I'm building a framework/engine and a game. Its a great learning experience, but we had to understand that it would take a long time (we have day jobs) and that we have to just keep chipping away at it. So far, the experience has been an eye opener and I've learned a great deal ... however, would I do it again? Probably not - I think I prefer designing the game and coding game specific logic - not engine specific.
I've done a lot of research on the platforms and I personally really like Unity. You can email them and request the iphone trial license.
Anyways, good luck!


Are Ornamental chilies safe to eat?

Question: I have a plant of ornamental chilies, which most probably they are little elf chilies. I would like to know if they are safe to eat and/or use them in cooking?
Comment: There is only one tiny caveat: If you *bought the plant labeled explicitly as ornamental*, it *may* have been treated with chemicals not approved for food.
Comment: They are usually very hot, but edible
Comment: @Stephie Not a tiny caveat, its a major one!
Comment: Gosh, this looks terribly like Thai Chili!  A smallish rounded perennial plant with lots of small chili fruits.  LUCKY YOU!  Of course until you've got a VERIFIED id...I'd wait.  You could collect the red chili and dry them.  Please do this as if this is Thai Chili you've got to save these!  Please send more information, what was on the tag, a larger photo with scale indicator...I am 90% sure but not enough to rely upon!!
Comment: In my opinion they are habanner chilli, but I'm not 100% sure
Answer: I wouldn't use them - any plant sold as 'ornamental' may have been produced by the growers using systemic pesticide/fungicide treatments not suitable for edible foods, and traces of which will be within the tissues of the plant and the fruits - the use of the term 'ornamental' means the growers are not restricted to non systemic, intended for human consumption, treatments during the growing process.
Comment: This depends on whether the whole plant was bought, or seeds of a variety labeled as *ornamental peppers*. The latter would be safe, but you are right about the first option.
Answer: Ornamental chile peppers are perfectly safe to eat, including Little Elf.
I've only grown one kind of ornamental pepper, so far: Chinese 5 Color. I understand Chinese 5 Color is supposed to taste better than most ornamental peppers do. Usually, ornamental peppers are not said to have much taste appeal. Chinese 5 Color tastes pretty good when it's purple (the first phase), but when fully ripe it's unpleasant to my taste. It's quite hot either way, but the heat seems to be a much more pleasant kind of heat while purple.
So, in essence, some ornamental peppers may not be palatable, but they shouldn't poison you or anything either way.
So, I recommend trying these at each color phase. It's possible you might like yellow more than red, or vice versa.
I do caution you, however, to make sure they actually are peppers. If they're not peppers (but rather a related nightshade species), they might be toxic to eat.
Comment: Yes I've known them dry 'on the vine' - unlike regular peppers which will rot first, here in North Texas.   when I've tried them they haven't been that hot, but of course it will vary by variety.
Comment: Great answer! Just one more point that I would emphasize from experience: Small ornamental peppers are usually a lot hotter than usual peppers. Which you might like or dislike... Also, they are often pretty easy to dry since the pulp (hopefully the right word) tends to be rather thin.
Answer: Go ahead and enjoy.. but please read my hints.
There is no such thing as ornamental chillies.:)
Wash them off, before eating if you got doubts about the treatment.
Rest assured, I got them outside and the previous owner named them ornamental!!
They just got a higher voltage than your ordinary jalapeno. Ours are volcanic strength and I recommend that you remove the seeds before using.
I also STRONGLY recommend that you wash your hands immediately, under NO circumstances rub you eyes or delicate parts, you can even feel it rubbing your nose!!
One per two people is usually sufficient, only if you invite Malaysian or Thai friends use more.
The only Chilies I have ever eaten with a higher voltage were growing wild in Northern Malaysia, those were about half the size of the "ornamental" ones.
I would rate those as atomic grade.
Comment: Ornamental just means people plant them for their looks. It sounds like maybe you thought it was a variety. Most ornamental peppers are very hot, but there are exceptions (e.g. Medusa peppers).
Comment: Did you know that you can use human hair to absorve the chillies juices when you accidentaly touch your eyes? I have done this before and works

Are Ornamental chilies safe to eat?


Geometry nodes line of touching circles

Question: I am trying to make a line of touching circles but cant seem to figure it out jet.
What I want is just a few connected vertices, projected on the vertices are circles that touch on the outside. I think the circle radius must be the edge length minus or plus the difference of the next edge length. I couldn't translate that to nodes jet.
Comment: i am not sure whether this is possible rn with GN. It would be with animation nodes.
Comment: Yep, with loops it would be possible. Animation nodes has loops ….♂
Comment: I guess I will need something like forloops. I could probably do it in Unreal Engine.
Answer: Basically you are right, to really solve this solidly you would need more tools. Loops and more complex calculations would be nice, but are not available with Geometry Nodes alone, and this is Blender and not Houdini.
Of course you can help yourself with Animation Nodes, but I think there is a more fundamental problem here.
The following example illustrates that you can't always get the desired result using a curve as the only starting point:

The distance between 0-1, 1-2 is self-explanatory, but as you can see here, it would not be possible to calculate a correct radius for another circle due to the distance between 2-3. This would be in the negative range in any case.
To solve the puzzle somehow, you would have to go the other way around and calculate your curve using randomly generated radii within a specific range.
How do we get these?
I present here two solutions:

Solution A: The simple variant, where a curve is calculated by randomly generated radii and directions.
Solution B: The complex and more mathematical or tricky variant, in which further circles are inserted between circles created with random radii and offset in position.

Solution A

Here we first create a curve with the desired number of points.
Once we apply the node Set Position, a radius and a direction are created per point.
The calculated direction is based on a randomly created angle and a vector length that is the sum of the radii of the current and the following point.
By accumulating the direction vectors created per point, the position for the individual points is obtained, which are changed there with the Set Position node.
Finally, circles are created at these points with the node Ìnstance on Points and scaled with the previously created radii

And here is the blend file for Solution A:

Solution B
The other variant is rather more complicated and based on a tricky approach.
Even though it is more complex and less performant, it is still an interesting solution that should not work any less well.
This looks like this (roughly sketched):

First, generate a curve with random positions of the points.

Then subdivide that curve and imagine a circle with random radius at every second point.
This step is crucial!
Since you don't have loops or other tools available with Geometry Nodes, you need fixed values at least every second position to calculate with instead.

At the points in between, simply imagine more circles. The position and radius for this can be calculated relatively easily by capturing the radii and positions of the two surrounding points.

In the next step, however, these circles are to be shifted additionally by a random value. For this the following mathematical basis will help you:

The trick is that you first take a random radius (r0) for another circle as a base, which is somewhere between the distance between your surrounding points and continue calculating with that.

Translated into Geometry Nodes, it looks something like this:

So, in the last step, if you use your randomly generated radii to calculate the positions of the circles in between, you will get this result:

Here is an overview of the entire Node Group:

And here is the blend file for Solution B:
Comment: Clever and well written. Nice one !
Comment: Wow thanks, very interesting solution. I was thinking of something similar but not creating an extra circle perpendicular to the subdivided point, that is quite brilliant. I made it work with drawn vertices instead of a generated curve, still works perfect. You put in so much work to answer my question. I really eppreciate that :)
Comment: You are welcome! But be careful: The offset takes place here in the perpenticular angle, but NOT from the point which results from the subdivision. Since this point changes depending on the radius of the intervening circle, I applied the mathematical solution as described above.

Geometry nodes line of touching circles


Multi-temporal Maximum Likelihood classification?

Question: Here is my basic questions. Does it make sense from a theoretical point of view to use the Maximum Likelihood classifier in a multi-temporal dataset of satellite images (Sentinel-2)? I mean, perform a single MLC classification for the complete multitemporal dataset, not MLC for each image.
Comment: What is your overall objective and the desired output?
Comment: I want to use a multi-temporal dataset of S2 images to classify land cover. What I want to know is how the MLC manage multi-temporal datasets, knowing that it uses 2 dimensional space to make decisions.
Answer: Yes. It does make sense and it is a very classical way of going about using phenology to classify different types of vegetation.
Using multiple timesteps in classification generally helps separate deciduous from coniferous forests, and farmland from meadows / fallow areas, but it also adds some noise depending on exactly when the two images were taken. These noise elements can be differences in time of plowing of fields, or browning of leaves in different parts of the study area. Another potentially source of noise is actual changes in land cover between the two images were acquired.
All in all, using two or more images for classification is commonplace, and which exact method for classification that you use have limited impact on this (with a few exceptions).


Lighted Switch Wiring

Question: I have installed a lighted single pole switch. The light on the paddle does not come on and the hot lead and the switch leg both show hot when the switch is in the on or off position. When I remove the switch the wires test normal.  What is going on?
Comment: Is a light bulb installed in the fixture?  Is it an incandescent bulb?  Try an incandescent. Bet it clears right up.
Comment: What make and model is said switch? What are you using for a light fixture?
Comment: A picture of how you wired the switch would be most helpful.
Comment: lighted switches tend to need a neutral, did you connect one of those?
Answer: Lighted switches, as with many other devices (smart switches, timers, motion detectors, etc.) need to get power for something else - i.e., they don't just need power for the light.
There are a few ways of doing that:

Batteries - This is incredibly simple but means changing batteries periodically and doesn't work well for a lighted switch because it would drain the battery pretty quickly.
Neutral - This is the preferred method. Unfortunately, many older houses (like mine) were wired with switch loops, which often (older houses: almost always) do not provide neutral in the switch box. Adding a neutral is easy with conduit but hard (usually) with cables. The NEC now requires neutral in the switch box in new installations most cases (except conduit), but that is a very new requirement.
Ground - Ground is electrically equivalent to neutral in terms of voltage level. It is not supposed to be used in place of neutral. However, code typically allows for some very low-current exceptions, including certain types of switches. This is only allowed if the switch is listed (e.g., by UL or ETL) for that installation method.
Leak through Load - This is an old method that avoids extra wires (yay!) and batteries, but it doesn't work well with LEDs. A small current passed through incandescent bulbs will normally not be noticeable. With LEDs, it can do any/all of: dim light on when switch is off, blinking, not work at all, work but cause the LEDs to fail prematurely. In general this will have a better chance of working with dimmer-compatible LEDs, but even that is not 100% guaranteed.

Your best bet in general is:

If you have (or can easily add) neutral, get a switch that requires neutral, as that will mean it is designed to use neutral and not to leak through the load.
If you do not have neutral, see if you can find a switch that specifically does not require neutral and requires ground. Note that almost all switches will include a ground screw or wire, but in many cases it is not required. You are looking here for something that must have ground.
Comment: The "requires ground" option can be crossed off the list for a lighted switch.  In the rare cases where UL approves ground leakage, they require that leaked current be less than 0.5 ma (yeah that's 1/10 of GFCI trip threshold. Really.)  That only allows about 60mw theoretical max power. Not enough for a light.  About as much as an indicator LED e.g. the "hard disk accessing" light on a PC.
Comment: I wasn't sure of the limit, other than "less than GFCI" for obvious reasons. I had a hunch it wouldn't work here - though it is kind of amazing how bright a single LED can be if you're trying to sleep :-)

Lighted Switch Wiring


How to get rid of blur background in photography ? How to get the background in focus as well in photography?

Question: I have a Nikon D-5300 with 18-140mm zoom lens, Recently I visited a place, where I wanted to capture the mountain and lakes with the subject. As a beginner I used to click in Auto mode. I was able to focus the subject and making the background in blur and vice versa with auto mode. Is there any way, so I can get a  clear back ground as well.
Thanks
Answer: A possibility is to put your camera in an 'aperture priority' mode, which is some form of auto mode with the exception that you are in charge of the aperture. (Aperture influences the depth of field, causing blurry foregrounds/backgrounds) Once in that mode you can close down the aperture (increasing the number). By closing down you allow the dept of field to increase, and in that case getting more of your view in focus.
Some notes to keep in mind: when you are at the wide end of your lens (18mm) and you focus on the subject in front of the mountain using a smal aperture, you are more likely to have everything in focus. When using the telephoto end of your lens (140mm) and focus on the subject, chances are only the subject and nearby object might be in focus due to the compression cause by the telephoto propertie (but that is another topic).
Answer: It's all about depth of field.  That's the distance range from your camera where subjects will be reasonably in focus.
Depth of field is a function of aperture.  The more wide open (lower f-number) the lens is set to, the shallower the depth of field.  For example, you get more of the scene in focus at f/22 than you do at f/4.
Some lenses, particularly old manual-focus and manual-aperture ones, come with a scale showing you what will be in focus.  There is usually a pair of lines for a few choice f-stops.  These are fixed to the lens body, and match up to points on the focus ring as that is moved.  The two lines for the current f-stop show you the distance range on the focus ring that will be in focus.
This leads to something called the hyperfocal distance.  Let's say you want to take a picture of a mountain in the background with as much of the near foreground in focus as possible.  First, you use the highest f-stop you can tolerate for other reasons.  Then you set the focus to the hyperfocal distance for that f-stop.  That means the center focus is a bit in front of infinity.  The hyperfocal distance is where you set the focus so that infinity is just at the far end of the depth of field.  That leaves the near end of the depth of field as close as possible while still keeping the background in focus.
There is another competing effect that eventually gets you at small apertures.  That effect is diffraction.  Things like the f-stop diaphragm are intended to cast a hard shadow.  Light rays either go straight thru or get blocked.  However, light rays very close to the edge are actually bent around that edge a little.  This happens over distances about the wavelength of the light, so we don't usually notice this on a human scale.
This happens all the time at the edges of the aperture diaphragm in the lens, regardless of what the aperture is set to.  However, at small aperture, the thin ring of area around the edge where diffraction is significant is a much larger fraction of the overall area.  When a large enough portion of the light rays don't go straight when passing thru aperture anymore, the image appears unsharp and can also look hazy if there are some bright areas, even if off-picture.
For most ordinary uses, you won't notice this effect except at particularly small apertures, like are common on macro lenses.


Finding all other workstations on the network

Question: at my home I have both workstations directly use Ethernet cables to connect to router, and also a few laptops/mobile devices that connect to wifi. Is there a command in linux to see list of all devices accessing wifi/network? Thanks in advance, sorry for bad english.
Answer: open your terminal and type this
sudo apt-get install nmap

then type as
sudo nmap -sP 192.168.0.1-254

so it will search all the devices from the range of 192.168.0.1 – 192.168.0.254 .
Hope that helps .
Answer: A nice way to detect all devices in a IPv6 supported network is to ping the ip6-allnodes
address via ping6 like this
ping6 -c 2 ff02::1%eth0
all ipv6 capable devices will answer to that ping
Comment: nice , I am sure it will help in future.
Answer: nmap -sP 192.168.0.0/24 (where 192.168.0.0/24 - your subnet). If you need other scan method, not ping - read man nmap.


What is the best source for Solaris packages?

Question: There are multiple sources for add on packages for Solaris, blastwave, openCSW, Sunfreeware, and pkgsrc. Ideally, I'd like to stick as close as possible to a single packaging system, so which of these would you recommend I use? Or, should I ignore them, and roll my own?
Answer: OpenCSW has the most up to date packages of the three sites, unless you specifically want the full GNOME desktop stuff.
We have all the gtk/etc basic libs up to date, and even firefox3. It's just that no-one so far has cared enough about the gnome desktop environment to update "the desktop".
Check out the packages page, for revs of what we have.
http://www.opencsw.org/packages
Comment: For those who like tinkering with packages: It's also easy to use build descriptions from OpenCSW:

svn co --ignore-externals https://gar.svn.sourceforge.net/svnroot/gar/csw/mgar opencsw

The OpenCSW build system abstracts away most of the annoyances of Solaris package building.
Answer: I think Sunfreeware is seen as the most stable and reliable source, although it often lags behind Blastwave with regards to recent versions.
In my shop, we employ Sunfreeware for our production packages, and Blastwave for development tools. This has the nice benefit that there is a physical and logical distinction between the two sets of packages, as Sunfreeware install under /usr/local and Blastwave installs under /opt/csw.
Hence, when we build and link software against /usr/local on our development machine, we are confidant that it closely replicates our production environment, whereas everything under /opt/csw is considered a kind of free zone, where all kinds of development packages and their dependencies are installed.
Blastwave also has a recent build of Trac - which is a blessing because building that from source on Solaris is painful.
PS: And no, you certainly should NOT ignore them, not only do they save huge amounts of time, they also have also been built by experts who know how to iron out various incompatibilities and issues that may exist. Dont be afraid to build your own either if there is good reason - you can often drastically cut down on dependencies by building 'lite' versions of packages (e.g. I build a version of PHP that excludes all XML related funcitonality). Ultimately you need to find a balance that suits your needs and environment.
Answer: If you're coming from an environment like Ubuntu or Debian where 99% of the time you're one apt-get away from whatever package you want to install, then Blastwave is going to be a better fit. It comes with a tool that overlays pkg-add called pkg-get that will take a package name, find it in the the network repository and install it.
On our Solaris Express machines, we use Blastwave almost exclusively. It's fast, easy and we haven't had any reliability issues with the packages (we run a 24/7 messaging service). Occasionally, there is a package Blastwave doesn't have, and we'll manually install that from Sunfreeware if its available or build from source.
Alternately, if you're just getting started with Solaris, giving Opensolaris a shot is also an option. Similar, apt-get like experience for all packages (including system ones). The repos are not quite as large as Blastwave yet but getting there. We've migrated about 80% of our Solaris Express boxes over to Opensolaris 2008.11 and 2009.06.


Can a suspension be combined with an anticipation?

Question:
On the word "destiNAtion" there is what looks to be 7-6 suspension except the suspension is not prepared on the strong beat as I believe it must be for it to be a suspension. So what is this then? Can a suspension be prepared in such a way?
Comment: "as I believe it must be for it to be a suspension": in the 18th century, perhaps.  This was written neither in the 18th century nor in an 18th-century style.
Comment: As I understand it, a suspension is a harmony, but an anticipation relates to rhythm. There's no reason not to combine these. Unless, for instance, you're strictly following a set of rules which explicitly forbids it.
Comment: phoog, when you study music you generally  learn THAT style, do you think there must be a reason for that? It is not like most of the most prestigous universities randomly pick a style.We still learn 18th century music not to write in that style but to write all other styles which deviate from it
Comment: But there are dozens of composers who never learned that style, including probably the vast majority of composers writing songs like the one in question.  Who wrote this one?  How was he or she trained? Even those computers who did learn classical counterpoint (as you note) deviate from that style, which is why compositions by 19th and 20th and 21st century composers don't sound like 17th-century music.  Seeking to analyze music with anachronistic theoretical constructs is sometimes fruitful but often leads to problems.
Comment: Oops.  "Even those computers" should be "even those composers," recent developments in artificial "intelligence" notwithstanding.
Answer: Yes. It isn't necessary for the note onset to occur exactly on the strong (part of the) beat — only that the note be sounding at that point. So it would be fair to interpret the sixteenth-note "na" as an anticipation, its extension onto beat 3 as the preparation, and the change to E on "tion" as the resolution.
However, the bigger issue is that a suspension is a chord tone in the chord of preparation and a non-chord tone in the chord of resolution. Here, it's a non-chord tone in the the chord of preparation. So the better interpretation is probably as an incomplete upper neighbor.
Comment: Non chord tone? If we see that chord as a ii63 or ii65 chord then it is a chord tone right?
Comment: @armani I don't think it holds up to interpret that chord as a `ii` chord. It's very clearly A major, the IV chord, and the F# is an ornamental pitch.
Comment: is that because it doesnt progress to V?
Comment: @armani It does progress to `V`, but either way, the interpretation as `ii` doesn't pass the ear test. The chord is so strongly establish as A major` on the downbeat, that a brief visit to F# doesn't change the heard nature of the chord. For theory purposes, I suppose one could call it a `IV` chord up until the arrival of the F# and then call it a `ii` chord, in which case the first paragraph of my answer applies.
Comment: fair enough, thanks Aaron
Comment: Where is there a V chord?
Comment: @phoog My mistake. It's a `I` chord. I was absorbed in the A minor chord.
Comment: But the bass is a 6th below the melody, so then the suspension is prepared properly isnt it? A 6th is an imperfect consonance.
Comment: @armani It's a non-chord tone, which is the criterion for the preparation of a suspension.
Answer: There is such a thing as an 'unprepared suspension'.   This one works particularly well because the melodic line echoes that in the previous bar.
The rule that is 'broken' by an unprepared suspension belongs to a musical era way before I think this piece was written!  These days we even use suspensions that are both unprepared and unresolved. Thinking in chord symbols, 'Csus4' MIGHT resolve to 'C', but it's by no means required or inevitable.
Comment: Laurence, do you mean the rhythm of the melody echoes that of the previous bar?
Comment: Both the rhythm and the actual melody, in the portion (F# -E) where the suspension occurs.
Comment: Ok I understand.  You say that the suspension is unprepared but looking again on this, the suspension happens right after the C# in the bass and this effectively prepares the suspension does it not?
Comment: Er…how does a C# prepare an F# again?
Comment: Sorry I mean A... F# is consonant against the bass and thus the suspension is prepared


Generalizing pullbacks

Question: A cospan is two morphisms having the same codomain. A pullback is a limit of a cospan. If instead of having two morphisms, we have a set of morphisms having the same codomain, is there a name corresponding to "cospan" and a name corresponding to "pullback" (as we have with "discrete diagram" and "Cartesian product")?
Answer: These are commonly called wide pullbacks. As far as I can tell, this terminology is due to Definition 1.2.3 of Taylor's
Quantitative domains, groupoids and linear logic. The term wide cospan for the analogous diagram is in use, but appears to be slightly less common.

Generalizing pullbacks


Resources to learn how Solana RPC API works?

Question: I'm doing a project with Solana, I'm trying to learn how the RPC API works but it's very difficult because there isn't enough information on https://docs.solana.com/developing/clients/jsonrpc-api Can you link to some resources on where can learn how this API works? Also is there is anyone here that wouldn't mind me asking them questions about how it works to talk in Discord or something like that?
Comment: what type of information are you looking for that isn't covered by the documentation that you've linked?
Comment: There are I think 100s of things, but one example would be in "sendTransaction" one of the parameters is "fully-signed Transaction, as encoded string" and I'm not sure how to do that and there aren't a few examples of this with it broken down to exactly how this works in depth.
Answer: The Solana Cookbook is a good place to start. You mentioned sending transactions in a comment so here's the cookbook section about sending transactions https://solanacookbook.com/references/basic-transactions.html#how-to-send-sol
Comment: Do you know of anything that teaches how the RPC API works instead of @solana/web3.js?


Can I transport canned food in hand luggage in Europe?

Question: I love canned food, specially tuna and sardines and I like to bring them from wherever I go (if the country has good conserves). It's a very nice "recuerdo" and experience (while it lasts). Can I bring these in hand luggage? Often these come in oil, olive oil, water or tomato sauce therefore my question.  Anyone has experience with these?
Answer: Liquids and paste-like substances are prohibited, meaning that anything moist or canned in oil, brine, fruit juice, syrup, water or any other liquid will be prohibited too.
Comment: The sardines are in oil or water and that is the forbidden item. When the container is over 100 ml, or 3.4 OZ you can not bring it in hand luggage, you are allowed to transport it in your checked luggage.
Comment: Thanks! I wouldn't call either sardines, tuna a paste. I don't know what you have in mind but most of the canned food I know is not a paste. Would that make a difference?
Comment: This answer is correct.  I've personally had some small cans of delicious Baltic sprats in oil confiscated in the EU, because terrorism(tm).
Comment: @nsn The only dry, canned food I can think of at the moment is milk powder, which I guess is not what you want to bring in your hand luggage. I have never seen tuna or sardines canned in anything else but water, brine or oil.
Comment: I dont disagree, I am just saying that itś not a paste. You may confusing it with Pâté.
Answer: Liquid in the Can Makes the Whole Can Liquid
The issue with canned food is not the food itself but rather the liquid suspension in which it is preserved - brine, oil, sauce, water, etc. Because the can contains some liquid, the whole item will understandably be treated as a liquid container. Your canned food will therefore be subject to the 100ml rule (3-1-1 for the US). This is to say that in theory, you should be able to carry canned food tins of ≤ 100ml volume in your carry on.
A Matter of Interpretation
Having said this, the airport-security liquid rule is often subject to interpretation. More importantly, the interpretation the passenger gives is always powerless against the interpretation given by the security personnel. Hence why it makes sense to search for what the individual security agencies specify on their policies regarding liquids.
European Regulations as Interpreted by the UK Authorities
You mention travelling to Europe, hence here is the UK governmental page on liquid allowance in hand luggage, which is arguably one of the most complete and easy to search source of information available in Europe. It explicitly mentions food, but not canned food:

There are restrictions on the amount of liquids you can take in your hand luggage. If possible, pack liquids in your hold baggage (luggage that you check in).
Liquids include:

all drinks, including water
liquid or semi-liquid foods, eg soup, jam, honey and syrups

British Airways seems to parrot the exact same information on their dedicated webpage. This is somewhat inconclusive as it leaves space for interpretation, without providing a definite yes-no answer as to canned food specifically.
TSA to the Rescue
Obviously the TSA does not define the rules for European airports. Nevertheless its website is arguably one of the most complete sources of information out there regarding airport security matters. Moreover it is safe to assume that, when is comes to global policies such as the liquid rule, international airport security agencies should abide by similar rules. Searching for canned food using the TSA prohibited items search tool yields the following result:

This is in my opinion a thinly veiled way of saying that the canned food is likely to be confiscated, since the doubtful TSA agent is always right, and that you should therefore place it in your checked-in luggage.
Better Safe than Thrown Away
Personally I would err on the safe side and pack canned food in my checked-in luggage. On one hand the liquids rule is likely to apply to them, regardless of the effective net content of liquid/gel preserve. On the other hand, hard metal cans and containers may be considered as harmful items, let alone weapons, by over-zealous security agents, inevitably guaranteeing them to be thrown in the thrash. Why waste a perfectly good can of gourmet sardines?


How do I sign into jetpack joyride on the same account but on different device?

Question: I have gone into profile but still can't figure it out.I just got a new phone and downloaded jetpack joyride but couldn't figure out how to use the same account on different devices.
Comment: I can't start all my progress on jetpack joyride over
Comment: The game account links with your email. Providing your using the same email, the phone will automatically use the same account
Answer: I think you can make your old account log in to facebook or google and repeat the same thing to your new account.
Answer: As far as I know, Jetpack Joyride does not support any cloud saves/backups.
Comment: As of version 1.8 there is cloud saving with a Halfbrick account.


Nuclear Fusion Proton-Proton Chain

Question: When hydrogen nuclei are able to overcome the coulomb forces, two protons collide. As a result, one of them decays into a neutron and a positron and electron neutrino are emitted. However, isn't mass gained in this scenario because the the sum of the  mass of a proton and neutron is larger than the sum of two protons? I might be missing something completely obvious and may be overthinking this.
Comment: A deuteron is lighter than an unbound proton + neutron.
Answer: The mass of the deuteron is less than the mass of two protons.
The deuterium atom has mass excess of 13.14 MeV, while a hydrogen atom has mass excess 7.29 MeV.
(Source. These values are for neutral atoms, which include the 0.51 MeV electron.)
So in the reaction
$$
\rm p + p \to d + e^+ + \nu_e,
$$
we have an initial mass excess of 13.56 MeV changing to a final of only 13.14 MeV.  The remaining 0.42 MeV is available as extra kinetic energy for the reaction products.
Note also that a free neutron and free proton together are also more massive than the deuteron, by about 2.2 MeV.  That's why the deuteron is stable against dissociation.
Answer: To overcome coulomb forces energy has to be provided   to the two protons, and if it is high enough  a proton can change into a neutron (inverse beta decay).
At higher energies  in proton proton colliders, the higher the energy .the more particles can be created, as in the LHC. In stars the energy is provided by the kinetic energies sof the ions in the plasma. –
Here is the wiki article :

In general, proton–proton fusion can occur only if the kinetic energy (i.e. temperature) of the protons is high enough to overcome their mutual electrostatic or Coulomb repulsion

Nuclear Fusion Proton-Proton Chain


Step sisters showering together?

Question: so my 6yr step daughter just told me that she is now showering with her 17yr step sister when she is at her mothers house. She said nothing inappropriate  has happend but is this really okay? A little back ground they have only been in 3ach others life for less then 1 1/2 years and have never showered together tell recently and the 17yr has never given her a bath or shower
Comment: What culture are you from? What are you concerned about? Attitudes towards these things are very culturally dependent, so answers might vary and the extra context might help you.
Answer: Some teens can be extremely modest and self conscious of their bodies, but many take a very relaxed view of non-sexual same-gender nudity, and especially if it has become pretty normal for them (for example, if on a sports team it's common to shower and change in front of teammates with little privacy, the same is even somewhat true of theater and dance groups, who often have to change costume in a fairly small room and with limited time between dances/scenes).  I have known of college students to share a shower just because there were not enough shower cubicles and everyone had morning classes.
It's also normal and not considered inappropriate for family members to see each other unclothed in many cultures, for example in places with sauna or communal bathing traditions. In general, my view on casual family nudity is that it's fine and healthy as long as everyone involved is comfortable with it.
That said, the fact this is a new behavior and you seem uncomfortable with it is probably reason enough to ask them to please shower separately, without making any accusations or embarrassing the girls.  I think there's a high probability that it's innocent, but of course there is no way I can know that with certainty.
Listen to your instincts.  If your gut feeling is that this bathing arrangement isn't right for your daughter, don't ignore it.  It's reasonable to set a boundary at not letting siblings shower together.
Answer: From a United States perspective this is something you should definitely do your best to stop.  These kids are not sisters and there is simply too much possibility for abuse.  My wife is a early education major with 20 years teaching experience now.  This situation is a HUGE RED FLAG for her.  It has nothing to do with trust or gut feelings, but rather making rational decisions to protect your child.  Reduce the opportunity for abuse when possible, and this is that time.
This also has the provided benefit of letting your child know you care for and love them and will take steps to protect them.  Kids don't also immediately show appreciation for restrictions in their life, but they do respect it. As they grow older they will benefit and appreciate what you went through for them.
Comment: I'm glad you pointed out that this may be a US perspective, but remember, US culture was created initially from the Puritan founding fathers, so is considered very repressive by a lot of the rest of the world. Your second paragraph is very opinion based, and while it may be right for you, it would have the opposite effect in other cultures, where it can be normal and healthy without any fear of abuse. Happy to have discussions like this in Chat, but happily this question has been closed.
Comment: @RoryAlsop not sure how you or any downvoter can minimize the possibility for sexual abuse which is a lot more common than known in the united states.  The severity of the crime makes being attentive and protective pretty important in most educators opinions, anecdotally speaking as my wife's family and my personal family have 7 teachers and obviously all talk with other teachers/co-workers so the information net is wider than 2 families here.  Sad that people feel like downvoting and putting a child in danger (in the US).

Step sisters showering together?


Analog early 60s story one spaceship of scientists innovating on the fly to overcome multiple adversaries

Question: This short story or novella published in Analog in the early 1960s was remarkable for the wealth of technical ideas in one storyline.  The heroes  first developed a space-warp battery capable of storing huge amounts of energy in a small lightweight package.  Next they became able to create matter directly from energy, then to direct the process by thought alone, then to power it from the network of nearby stars.  All the while they were barely escaping from fleets of enemies.  In a dramatic finale they visited the planetary system of their greatest enemy and thought-created a huge hemispheric cup fixed in the path of their homeworld.  The planet runs into the obstacle and is destroyed, while all the stars in the immediate area dim briefly from the power drain.
Comment: E E Doc Smith came up with the idea of a "sunbeam" that concentrates the power of the Sun into a single beam as a weapon in Children of the Lens, but nothing else in that book matches. Subspace Survivors doesn't match at all.
Answer: That is Invaders from the Infinite by John W. Campbell Himself.  All of the events and inventions you mention -- including the giant cup of "artificial matter" -- are in the story.
The book was published in 1961, but it was originally in Amazing Stories Quarterly in 1932! (I've never compared the two versions, but I'd be shocked if the 1961 version wasn't a rewrite of the 1932 version, as it's decidedly better-written than was common in Amazing in the early 30s.  A quick check doesn't find any online discussion of this.)
This is the third novel in the "Arcot, Wade, and Morey" series which began with The Black Star Passes and followed by The Island of Space.  They're really good examples of the best of 30's super-science SF.


changed permission of 'usr' to 700

Question: I changed the permissions of /usr in Ubuntu to 700.
Graphics are not working. In a tty I have no access to sudo to change permissions back again.
I tried to access root from 'advanced boot option' and run the command chmod 755 /usr but it said something like 'read only file' and the permissions didn't change.
One of my friends also tried by mounting the drive and changing owner, but nothing seems to be working.
Comment: When in recovery mode ('advanced boot options') the root filesystem is initially mounted read-only: you will need to remount it in read-write mode first `mount -o remount,rw /` **then** `chmod 755 /usr`. (NOTE: both `mount` and `chmod` are in `/bin` so shouldn't be affected by bad permissions on `/usr`).
Comment: @steeldriver  you saved my life. Like a moron i changed the root directory permissions without fully understanding the consequences.
Answer: Unfortunately, you removed group permissions and all other permissions. And you did it to just about every program that your system uses to boot and draw the GUI. You also nuked the terminal emulator. Unless you have an image that you can restore from, I think you're going to have to re-install the OS.
Comment: It looks like they didn't do recursive chmod, in which case it's not so bad
Comment: Well, the OP still has stuff under `/bin` and TTY is always available.
Answer: If you boot in recovery and get given a menu where you can enable networking (this option mounts the file system with read write permission), then enable networking and then choose the option to enter a root shell and skip to step 3 - you can omit sudo on the commands in this case. If you boot in recovery and don't get this option, then it won't work because you have to use sudo to remount as read-write and you cannot use sudo, so in that case:
If you don't have the networking & root shell recovery option, then boot into a live session (get that friend to make you a live USB if you don't have one) and mount your installation:

Find the root partition with sudo fdisk -l . It will be the biggest one if you don't dual boot and most likely have an ext4 filesystem.
Mount the partition, using the actual name of your root patition instead of /dev/sdxY and cd to the mountpoint:
sudo mount /dev/sdxY /mnt
cd /mnt

Check the current permissions
ls -ld /usr

Change the owner back to root if it is not root:
sudo chown root:root /usr

Check whether your friend used -R by doing ls -ld /usr/bin and if it says root is the owner, then do nothing more and go to the next step. If your friend used -R then you must use sudo chown -R root:root /usr to correct it here. root should be the owner of everything in /usr except /usr/bin/at which should belong to daemon so if you used chown -R root:root /usr then afterwards do chown daemon:daemon /usr/bin/at (I checked this using the clever find command from this answer... if you have /usr/sbin/uuidd that should also be chowned : chown libuuid /usr/sbin/uuidd

change the permissions (NOT USING -R)
sudo chmod 755 /usr

Again, please please do not use the -R flag

a. Assuming you did not use the -R flag in the first place, you've fixed it now. If you did use the -R flag, then it might be easier to back up your /home stuff safely and reinstall, but for now fix sudo which needs the setuid bit (octal 4):
sudo chmod 4755 /usr/bin/sudo

If running a live session, cd out and unmount the partition:
cd /
sudo umount /dev/sdxY

and reboot back into your system. Now you have sudo, and chmod is in /bin so you can use sudo chmod to fix broken permissions on anything else you need in /usr for whatever you want to do next, but make sure you know exactly what you are doing (read some stuff, for example this and this) when using chmod (read and avoid using the -R flag - if you clear the setuid bit from sudo you will break it again.

changed permission of 'usr' to 700


How to use router connect via cable like a wifi card in Kali Linux?

Question: I'm doing a Kali Linux course and next concepts are about airmon and airodump.
The practice requires that you install a Oracle Extension to active USB 2.0(EHCI) device and select your wifi cardboard.
The problem I dont have wifi cardboard.
I have this ethernet card: Atheros ar8151 pci-e gigabit ethernet controller (ndis 6.20)
And this router connected via LAN cable: ZXHN H108L
Is posible to set that modem like a wifi cardboard to active wlan and capture air traffic?
I tried using Tethering with my phone (android 6.0), and the extension recognize the BLU ADVANCE[FFFF] like a usb2.0 EHCI element.
But when I run the VMs with kali linux my host pc lost the internet connection (apparently is normal).
The kali linux DONT GET INTERNET.
Update 15-08-2017
I Triyed this for get internet:
1 Go to network configuracion of the VM and set the brige adapter and select remote NDIS Based Internet Shared Device
2 Go to VM run the machine (the cellphone get disconected for HOST)
3 Later do this:
Unplug the phone, replug phone.
4 Internet works in KALI LINUX

The problem Only appear usb0 non like a wlan
Answer: I'm guessing the answer is no, you cannot do that. The sorts of information you'd get in a wireless frame won't make it onto the ethernet connection. For example, there are no beacon frames in ethernet.
You can, however, use a wifi router + ethernet to get onto a wifi network, just not to sniff wireless packets (AFAIK).
Comment: and someway to virtualize a wifi?
Answer: Truth is you can't use host machine wifi adapter in virtualbox.
Yes you read that right you can't use host pc/laptop build in wifi adapter in virtualbox and the above statement is absolutely true and i have spent many hours figuring out how to enable it and reason i found on web is:-
"VirtualBox or any virtualization application abstract the hardware of its host machine, and creates the virtual or hypervisor layer between the host machine's hardware and virtual or hypervisor application"
Pretty simple huh? In layman terms it means that to use host pc hardware virtualisation software builds a virtual layer between the hardware on host pc and virtual application due to which we are unable to access wifi adapter.
To counter this problem there are mainly two way:-
Dual boot:-This is a method in which you don't have to spend a single penny.Dual boot simply means to install multiple operating system on single machine and you will find tons of tutorials on youtube.
External wifi adapter:-This is somewhat easy method but you have to spend some money to buy a decent wifi adapter from amazon or flipkart.Once you have bought one just connect it and navigate to Devices—>USB and you will find the external wifi adapter.
So these are only two methods to use wifi adapter of host machine on virtualisation software.If you know another one let me know in comment section.


What were the mammal ancestors like 65 million years ago?

Question: What we know about our mammal ancestors that were alive (and survived) at the extinction event 65 million years ago?
Answer: Many of them looked like little rodents. However, several distinct mammalian lineages were already present, including Monotremes, marsupials and placental mammals. Throughout the whole Mesozoic era, mammals were already quite diversified! Also, even though most of the mammals that survived the K/T boundary were rather small, there were already some larger mammals around in the Cretaceous.
Here is a nice picture of a symmetrodont:

See a nice page on early mammals.
Answer: A recent genetic analysis suggests that they were probably bigger that we thought before :
http://www.newscientist.com/article/dn22343-mammals-ancestor-was-not-as-puny-as-we-thought.html
Answer: In a 2013 study, that combined genetic data and morphological data, the last common ancestor of placental mammals was estimated to be a four-legged creature likely ate insects, weighed from 6 grams (about the weight of some shrews) up to 245 grams — and was more adapted for general scampering.  Also, its cerebral cortex — the part of the brain linked to higher mental processes — was probably convoluted, folds linked with greater brain activity, http://www.livescience.com/26929-mama-first-ancestor-placental-mammals.html
The same study estimates that this ancestral creature arose some 200,000 to 400,000 years after the end of the age of dinosaurs. This is in line with what paleontology suggest... but is in contrast with other studies based purely on genetic data, which puts the last common ancestor of placental mammals 36 million year before the dinosaur extinction. (which depends on how accurate you can estimate the speed of the genetic clock which is dependent on number of generations and thus the lifespan of the animal...faster in fast breeding, short lived animal. Slower in long lived, slow breeding animals)


Doppler and Speed of light

Question: If an an over-the-air radio signal of a certain frequency $f_c=300$ MHz travels in my direction while I'm standing still, then I observe the signal travelling towards me at the speed to light and I measure no Doppler switch.
However, if the speed of light is always constant to the eyes of a the observer regardless if the observer is moving or not, I should also measure $300$x$10^6$ periods a second (and thus no Doppler shift) if I move towards the light source. But theory tells that, when moving towards the light source, positive Doppler should happen.
Where is the mistake in my understanding?
Answer: if you move relativ to the sending source of the wave, your time scale is different, so the frequency you measure is different.

Doppler and Speed of light


Modify object's geometry after animation has been applied

Question: I have just made some animation on object (applied some Rot, Scale, Transform keys on different frames so object is performing motion) and suddenly it is understood that object must have some other proportions (a little bit more). The question is: how to change geometry of such an object without affecting (remove, change or other actions) all animation keys?
Comment: This depends on how you animated the object. If it's just simple transformations, you should be able to edit  it and have it behave fine, if it has any deformation, it might be a bit tricky or next to impossible. If you could share the blend file, we might be better able to assist you.
Answer: One trick you can use is to parent it to an Empty object. Any transformation to an object will affect any other object parented to it, compounding their own transformation without needing to change any single keyframe. And an Empty is the simplest to setup as the parent, for such purpose.


Unanswered and abandoned questions

Question: I had the same question as Nolan about rendering in blender, Why won't objects appear in motion tracking?
But there is no answer to the question and it is a few months old with no signs of attention. Is there any other way to spark interest in an old question, other than bounties? I have very little rep, and don't want to waste it all. Should I ask a similar question, or will that just get marked as a duplicate? If nobody has seen the orignal question will they bother marking the new one? Perhaps we should push to close them, or put them higher on the unanswered list.
Answer: In this case, I'd say it's okay to post your own question with a link to the old question. This is a rare exception to the rule, based off some assumptions:

The other question has no answers (or only low-scoring answers which don't help solve the problem)
The other question is at least a month or two old, and/or it seems unlikely that the old question's OP is readily available.
The other question was not posted by you

If all these are true, then IMO the best course of action is to start afresh. Keep in mind that to answer a "trouble-shooting" question like this, information about the details is of the utmost importance.
A .blend is invaluable. If you don't want to upload your project to the world, take the time to try and make a simple example of the problem in a new file (or go backwards by starting with your project file and deleting unrelated objects).
See Including a .blend file for instructions on actually uploading the file.
Chances are, a lack of info is likely what resulted in the lack of answers to the other question.
With a little luck, you'll get some answers which successfully answer your question. If you do, we can close the old question as a duplicate of your new question, redirecting future visitors.
Comment: Just a side note: When the user doesn't want to or can't upload the original file, one very interesting benefit that may rise from the user trying to recreate the problem is that he often finds the solution to the problem himself.
Comment: Sorry if I was unclear but, I did not make the question, I simply had the same question with no answer and I don't have enough rep to edit a question.
Comment: @SammySwanson Ah, my mistake. In that case, I'd say it's fine to post a "duplicate" question of your own, perhaps with a link to the abandoned question. (IIRC closing as a duplicate of a question with 0 answers isn't even possible)

Unanswered and abandoned questions


should I buy this drone?

Question: I am a beginner and wanted to buy myself a little drone kit to learn to program it. I was thinking about a raspberry pi 4b and pixhawk drone, but I don't know what to buy.
I saw this thing on amazon, and I know that it is quite old but it is very cheap https://www.amazon.fr/gp/product/B09SZ74YFK/ref=ox_sc_act_image_1?smid=AQQD305QEV0YZ&psc=1
and I would add by myself the raspberry pi 4b and the rasberry pi camera module https://www.amazon.fr/gp/product/B01ER2SKFS/ref=ox_sc_act_title_2?smid=AYJCVVRX88QTX&psc=1
I was thinking to do it like in this yt video https://www.youtube.com/watch?v=kB9YyG2V-nA&list=PL_2ZLLWNjKFHxIDptncuVNmTsvjAdAjM7&index=3
I would like to program it with python. Is this good, if not does anybody have an alternative in the same price range? Am I missing some elements that I will need to buy to control my drone? I have a total budget of 500 euros without the RC since I would prefer to control the drone entirely with python scripts
Answer: I would avoid this kit:

its pretty outdated hardware
the arms are made of thin plastic, this is likely going to break when crashed

if you don't care about the plastic problem, you can get the frame without the hardware (so you can buy more modern one) for cheap on ali-express (its called F450).
if you spend a bit more time searching ali-e for comparable frames, you might find one of these kits: https://www.aliexpress.com/item/1005004864316433.html it's marginally better than the F450 kit, mostly because its using carbon arms.
I'd like to point out to you, that you will need rc equipment, as full autonomous flight will need a lot of paperwork (I'm assuming EU rules as you posted french links) if you ever want to fly that outside of a hall, while if you want to fly that in the open category (de-facto category for hobby), you need to be able to control the drone.
that said, you want that ability either way - and if it's only to shut down the motors after your Python code crashed the drone full-speed in the next bush.
Generally. I would recommend connecting with builders in your region, for advice & help, and because you might be able to get a few used parts for cheap.
PS: one of the best drone-part stores i buy from is in france: https://www.drone-fpv-racer.com/en/ while they aren't likely to have the kind of frame you are looking for, they should have most other things you could need.
Comment: Thanks for your answer, I checked a bit Alie express and the link that you gave me ```https://www.aliexpress.com/item/1005004864316433.html```  So it has a carbon frame, telemetry module and plenty of other stuff. It is also very cheap and has a lot of components. But I never bought anything on Alie express, is it trust worthy? Also there is a lot of different packs, which one would you recommend (probably one with a telemetry module) but which one?
Comment: is ali-e trustworthy: well, its a sales platform with a bunch of different sellers, and i have heard of people having trouble - myself, the only issues i ever had were easily solved by requesting to get my money back.It does take some time to be delivered from china though.

as for which pack: you have to check what suits  your usecase best, i probably would go a totally different route with a lot more customization
Answer: Python and a Raspberry Pi aren't really a good match for a drone. The Pi is a complete computer, and thus has a lot of overhead. It isn't solely focused on your programme, and can pause briefly to handle other tasks. Similarly, Python is an interpreted language and not ideal for a real-time system. I'll add that popular flight controller software (like BetaFlight or INav) are also mature products with lots of complex features that make them hard to understand.
I recommend looking at dRehmFlight (pronounced dream-flight). The code is simple and it runs on a Teensy, which is small, cheap and light-weight.
Comment: the question was about a drone with pixhawk and raspberry pi, not for raspberry pi as flight controller - in a combination like that the pixhawk is acting as the flight controller and doing the realtime job, the rapsberry pi then communicates with the flight controller - if their goal is to build something that needs to computational power of the sbc, for example to work with map data, trigger a payload when reaching an area etc. then this is a setup that should work fine, especially for a beginner

should I buy this drone?


Does c#k + i actually generate all primes above c# (plus some composites)?

Question: The Wikipedia page for "Primality test", linked below [1], states that "all primes are of the form c#k + i for i < c# where c and k are integers, c# represents c primorial, and i represents the numbers that are coprime to c#."
I understand this to mean the following:

Pick a particular value for c, for example set c=11.
Compute the primorial of c, c#=2*3*5*7*11=2310.
The values that i can take on for this choice of c are: 1, 13, 17, ..., 2309. (The values 2, 3, 5, 7, and 11 are omitted  due to being primes less than 11, and the list of possible i values ends at the largest prime smaller than c#=2310 or in this case 2309.)
For this c# every possible prime number above c#=2310, can be produced for some value k (any integer) and a particular value of i.
Note, I understand that the series will ALSO generate composite numbers, but my understanding is that it will be guaranteed to generate every prime above c#.

I tried to test this. Specifically, I checked to see if [(2^13)-1]=8191 (which is a prime number, specifically a Mersenne prime) can be generated by the sequence of numbers for c=11, c#=2310.

To find the appropriate value for k I computed [(2^13)-1]/(2310)=3.54... Thus I selected k=3 since the values of i are less than c#, and if k were any other value there would be no chance of reaching the number in question (8191).
Then I did [(2^13)-1]-3*2310=1261. And looked to see if 1261 is a possible value that i can take on. However, 1261 is not prime, so i can not equal 1261.
Thus I concluded that the series of numbers generated by c#k + i can not possibly equal [(2^13)-1] for the series generated by c=11.

So it would seem to me that the claim made in the Wikipedia page for Primality Tests that all prime numbers above c# can be generated by the series c#k+i is false. Am I misunderstanding the original claim? Or have a applied it incorrectly and make a mistake in the calculations? Any clarification regarding series of this form that generate all primes (plus some composites) would be greatly appreciated. (Is there a name for series of this type that I could use to search for more information?)
[1] Wikipedia page for "Primality test"
https://en.wikipedia.org/wiki/Primality_test
Comment: It says _coprime_ to $c\#$. Since $1261 = 13\cdot 97$, it is coprime to $11\#$.
Comment: @DanielFischer Thank you. I see now I have somehow misunderstood the original claim. The value 1261 is "coprime" with c# as it shares no common prime factors (2,3,5,7,11). This is many more possible values than I listed for i, or understood that i could take on.
Answer: Yes, in the sense that , because it generates all numbers greater than c# that are coprime to it. It can generate, all primes greater than $c$ if $k$ is allowed to be 0.


Intersection of elements of a union

Question: I am working on a proof where I would like the following identity to hold.
$$\bigcap_{w \in \bigcup_{i \in \mathbb{N}} W_i}w = \bigcup_{i \in \mathbb{N}} \bigcap_{w \in W_i} w,$$
where $w$ are sets such that for any $w,w' \in W_i$, $w \cap w' \neq \emptyset$. After playing around with it for a while, I have not been able to come up with a counterexample, and it seems plausible to me that it should hold, but I have not been able to give a rigorous proof. Can someone help me to decide whether this is true or not?
Comment: I believe this is false. Look at the case where each $W_i$ contains only one $w$.
Answer: Let $W_1=\{\{a\},\{a,b\}\}$, $W_2=\{\{c\},\{d\}\}$, the rest arbitrary and check the difference.
Answer: As I said in the comments, the statement is false. In fact, if we do have
$$\bigcap_{w \in \bigcup_{i \in \mathbb{N}} W_i}w = \bigcup_{i \in \mathbb{N}} \bigcap_{w \in W_i} w,$$
then it is necessary that
$$\bigcap_{w \in W_i} w\subseteq\bigcap_{w \in \bigcup_{i \in \mathbb{N}} W_i}w,$$ for every $i\in\mathbb N$. After a close look we see that this implies $W_i\subseteq W_j$ for all $i,j$. So we must have $W_i=W_j\,, \forall i,j\in \mathbb N$. Now the statement is trivial. So this is in fact never true, exept for the trivial case.

Intersection of elements of a union


How to handle amazon MWS throttling in Salesforce

Question: I am using Amazon MWS to get Orders and insert into Salesforce. Amazon MWS have "maximum request quota"  i.e. It will allow a maximum of 6 Http Callouts. Then after 6 minutes only, we can call another 6 Http Callouts. Is there any way to delay execution for 6 minutes in APEX CODE. Also how to handle this type of Throttling.
Answer: Salesforce apex doesn't have a sleep/wait functionality. And it is not planning to have one. The idea is here: https://success.salesforce.com/ideaview?id=08730000000Bq2HAAS
I guess the best you can do here is add it as a schedulable job and schedule it to run every 6 minutes.


Why is my ASP.NET MVC project saving several copies of itself?

Question: This is really weird behavior, let's say I have an asp.net mvc project as follow on my desktop (vista):
/mvcapplication/app1
then over the course of development, I copy this solution to a briefcase on a thumbdrive so I can work on it from a laptop (xp).
When I insert the thumbdrive back on the desktop, I notice it's taking longer and longer to sync, eventually it took so long that it just hangs there. I checked the project structure and found that it is now:
/mvcapplication/app1/app1/app1/app1
with each /app1 containing the entire project structures. I am not new to visual studio, and I am sure I opened and saved the solution and files just as I normally did, but this is just bizzard. I thought this is caused by briefcase, but the same thing happened when I  copied the solution into a folder on the thumbdrive.
I would have left this alone, but with that sort of crazy folder structure it's really difficult to determine which folder has my current changes..
Anyone ever run into something like this?
Answer: Never had this happen but then I don't use the Briefcase.  Then again, I try to avoid most things in Vista.
I just use good 'ol copy and past for thumb drive stuff.


What sort of encryption is used?

Question: What encryption is used in a default Ubuntu full hard drive encryption and is it possible to specify another?
Answer: Probably AES256 (as I could figure out from https://help.ubuntu.com/community/EncryptedHome)
Answer: Apparently it uses an XTS-AES (AES-cipher) with a hash algorithm sha1 (256bit key-size) by default, using Linux Unified Key Setup (LUKS). You should be able to change this manually somewhere in the Ubiquity scripts, when the command cryptsetup is used.
Type in man cryptsetup for more information.

What sort of encryption is used?


Hungry Child? How do I tell?

Question: I just became a parent recently, so pardon me if I my question seems surprising
to some of you, but how do I exactly know if my child is hungry, he is only 6 months?
Answer: Children at six months can be taught sign language, and asking for food and drink is usually the easiest thing to teach them.
Sign language for babies is easy to learn because it involves logical motions and simple ones. Asking for food is moving hand toward face as if you have food in it. Asking for more is bringing hands together with fingers touching. Saying all done is the common motion for no more (think 'safe' call for baseball hand motion).  All of those are very easy to learn for a six month old.
Of course, sometimes your baby won't know she is hungry; the main way to deal with that is simply to make sure you make food available on a fairly frequent basis (every few hours at least) and see how much she wants. If she is hungry she will eat.
Answer: When a baby seems distressed in any way, hunger is one of the first working hypotheses to test.  It's a good idea to take a snack with you whenever you go anywhere, and to have some easy-to-serve food handy at all times.
You'll know if he was hungry if you try serving him some food and he eats it and then feels better.
As you get to know your child better, and as he matures and develops more communication skills, it will get easier to read his cues.
Answer: My wife is an amazing woman, she can tell by a cry if our kid is tired, hungry, or needs a diaper changed.  There is no "exact" way to know if your baby is hungry.  When I am home alone I usually just go down the checklist.  When he starts getting fussy first check the diaper, then see if he wants a bottle, then try and lay him down to sleep.  Sometimes he is real fussy and doesn't want a bottle or sleep.  At 6 months is around when some babies start teething.  They will be fussy for no reason at all.  Try giving him a piece of cold celery.  He can chew on it without chocking on it.  You can also try baby orajel or tylenol but we try to stay away from the medications.
Are you asking because you can't tell if you are feeding him enough or because he is always cranky?

Hungry Child? How do I tell?


Existence of weak solutions of a parabolic PDE

Question: Assume that $\Omega\subset\mathbb{R}^n(n\geq3)$ is a bounded open set with smooth boundary, $\varphi\in H^1_0(\Omega)$, $F(t)$ is differentiable in $\mathbb{R}$ and $F'$ is bounded. Given a PDE
$$
\begin{cases}
u_t-\displaystyle{\sum}_{i,j=1}^na^{ij}(x)u_{x_ix_j}=F(u)&\text{a.e. }(x,t)\in\Omega\times(0,T],\\u|_{t=0}=\varphi&\text{in }L^2(\Omega)
\end{cases}
$$
where the matrix function $[a^{ij}(x)]_{n\times n}\in C^{\infty}(\bar{\Omega})$ is positive definite and symmetric. I want to know that if there exist a weak soluton $u\in L^{\infty}(0,T;H^1_0(\Omega))\cap L^2(0,T;H^2(\Omega))$ such that $u_t\in L^2(\Omega\times(0,T])$. If it exists, how to prove it? Thanks!
Answer: Start by showing that there exists a weak solution with lower regularity (standard $L^2$ energy), i-e
$$
u\in C([0,T];L^2)\cap L^2(0,T;H^1_0)
\qquad\mbox{with}\qquad
u_t\in L^2(0,T;H^{-1}).
$$
(This can be achieved opening any textbook about quasilinear parabolic equations.)
Then improve the regularity: since $F$ is Lipschitz it is easy to see that
$$
f:=F(u)\in L^2(0,T;L^2)
$$
hence $u$ is a weak solution of the frozen Initial-Boundary-Value problem
$$
\left\{
\begin{array}{ll}
u_t+Lu=f & \mbox{in }Q_T\\
u=0 & \mbox{on } [0,T]\times \partial\Omega\\
u|_{t=0}=\varphi & \mbox{in }\Omega
\end{array}
\right.
$$
with $\varphi\in H^1_0$ and $f\in L^2(0,T;L^2)$, as well as $L$ a good, smooth, uniformly elliptic operator. Standard results (improved regularity) for this linear problem gives the desired regularity for $u$ (see e.g. Evans' book "PDEs" section 7.1.3).


Example where a finite group $G$ of order $n$ has no subgroup of order $m$

Question: Using the Fundamental Theorem of Abelian Groups, one can prove that if $G$ is a finite abelian group of order $n$ such that $m$ is a positive integer that divides $n$, then $G$ contains a subgroup of order $m$. But what are some examples of non-abelian groups $G$ of order $n$ and $m$ a factor of $n$ such that $G$ has no subgroup of order $m$?
Comment: Yes, Libertron.
Comment: @Libertron At the beginning you say it's easy to see this is true for abelian groups, but at the end you ask if $G$ is necessarily abelian? I don't understand it at all.
Comment: I take it that this means the counterexample must be a non-abelian group, right?
Comment: I just realized the logical error there. I meant to say a finite non-abelian example.
Answer: Possibly the smallest group where this occurs is the alternating group $A_{4},$ which has order $12$ and yet has no subgroup of order $6$. Note that this is a solvable group.
Answer: It is not possible for $G$ to be finite and abelian for this to be true. Many examples are given with $n=2m$ by simple groups: any subgroup of index 2 is normal, hence no simple group can have a subgroup of index 2. Furthermore, any nonabelian simple group is of even order, so any nonabelian finite simple group gives an example.
As Hagen von Eitzen points out, a concrete example is given by $A_5$, which is of order 60 and has no subgroup of order 30.
Comment: So a concrete example is that the order $60$ group  $A_5$ does not have a subgroup of order $30$.
Answer: Maybe good to know if you are interested: finite groups for which the property does hold (that is, for every divisor $d$ of the order $|G|$, $G$ has a subgroup of order $d$) have been studied extensively. They are called CLT (Converse Lagrange Theorem) groups. It is known that a CLT group must be solvable and that every supersolvable group is a CLT group: however solvable groups exist, which are not CLT and CLT groups which are not supersolvable. For example Geoff's example $A_4$ is solvable but not CLT.


Reapply a position in a company

Question: Ten years ago I left a company that I had worked for over 7 years.  Last year I rejoined the company but resigned during my probation period due to family issues. Now I see another opportunity at the same company and very much like the scope of responsibility and wish to apply.  In their, online application they required to fill out the last position that I held at the company.  Do I state the one that I left last year? Or I can skip that and say my last position was the position 10 years ago?
Comment: I would list both. If the form doesn't allow you to do that, list the last one, and use the cover letter to expand on the fact that you worked at that company 7+ years and that you know the company inside out. Either way, HR should have both recorded under your name, so it's not something you should fret too much over.
Answer: No, the last position is the last position you held, irrespective of the duration.
Mention the last position you had, and if asked, be ready to explain why you left the last time. You can however, use the cover letter to explain that the last stint with the organization was rather brief, due to personal reasons and add a bit about the previous position which was a much longer association.

Reapply a position in a company


Does class weighting encourage overfitting when the true class distribution is imbalanced?

Question: I am working on a classification problem in which ~90% of samples come from class 1 while ~10% of samples come from class 2. I have been using various techniques to combat the class imbalance while learning the problem, however, I am concerned about potential bias this may introduce because the true class distribution is unknown. Is it bad practice to weight classes during learning if the true distribution (or some reasonable approximation) is unknown?
Answer: Your assessment is right. You must first determine the data distribution in real-time (production) and only after that proceed with train_set, test_set and validation_set creation with the same distribution. And subsequently work on model training and setting the class weightages if required.
Why:

Any metrics upon which you evaluate your model are basically
unreliable as it does not indicate the model's true performance (as on the true/real distribution).
You end up training and
optimizing your model on a false perception of metrics.
Model
weightages and bias depend on the training data's distribution. To
get the best performance it must be trained on the true
distribution.
Comment: Yes exactly, an approximation should be enough. Once you go live you can observe the actual distribution and adjust the weights accordingly. Just make sure you invest time in finding a close approximation so that you don't have to change it a lot in the future!
Comment: Got it I figured that was the case. I suppose when the true distribution is unknown, we should weight classes (or resample) based on our best guess at the true distribution?


Struts 2 decorator question

Question: I'm building a website with struts 2. I got a decorator for the layout of my website and I fill the content according an action. I also want to use a column with some tools like login, latest messages, etc. I'm pretty new to struts and i don't have a good idea what the design for this would look like. My best guess is some sort of second action. But I don't have a clue how to add 2 actions to my decorator.
Is my design approach a good one and if so how should this be implemented?
Comment: i do not have idea about decorator but regarding calling 2 action using struts2.x you can either use action chaining method to accomplish this.
Answer: Struts 2 uses 1 action per page. Nested actions are possible. An other option is to use ordinarily includes.
Answer: You could make every action extend a BaseAction where the decorator could pull data from.
For example, if FooAction extends BaseAction, you can access the FooAction data from foo.jsp and the BaseAction data from main.jsp (your decorator). To list the latest messages in main.jsp, add a getLatestMessages() method to BaseAction.
Of course, ALL of your actions must extend BaseAction for this to work.

Struts 2 decorator question


What is wrong with hydrazine as a monopropellant?

Question: While answering a question about if N2O was a practical monopropellant, I found that hydrazine was considerably more efficient. So, why do people want to replace it with N2O, if hydrazine is more efficient. According to a Harvard sub-page, they are. So, why? There must be some current problem with hydrazine that people want to switch. What is that problem?
Comment: Because it is a toxic propellant? IIRC, see articles like this https://www.newscientist.com/article/mg15621033-800-what-goes-up/
Comment: @CamilleGoudeseune Gaseous nitrogen, N2, **is** used as a monopropellant. It is the favored gas for cold gas thrusters.
Comment: The book [_Ignition!_ (Clark)](https://www.amazon.com/Ignition-informal-history-liquid-propellants/dp/0813507251) - also available from other sources - discusses hydrazine as of the late '40s and the '50s.  Clark brings up two issues: pure hydrazine has an extremely high freezing point and so needs to be mixed with a "freezing point depressant" to get it usuable - not of which seemed to work - or to be changed to something else - "a derivative" - and they came up with UMDH.  But that was _not_ a monopropellant.   1/2
Comment: For monopropellant use the problem (discussed on pages 122-123) was that the hydrazine was sent over a catalyst bed, "but restarts, if the catalyst bed has cooled, are just about impossible."  But, again, that was in the late 40's early 50's, and maybe things have been discovered since then ...   2/2
Comment: @davidbak hydrazine was used as a mono(fuel, not really prop) in the shuttle Auxiliary Power Units and caused a lot of trouble including almost blowing up the orbiter on STS-9. As you say, heaters had to be supplied to keep it from freezing, and if they failed on, that was Real Bad too.
Answer: There are a few reasons why a hydrazine replacement is being looked at:

Hydrazine is highly toxic, and carcinogenic so it's dangerous to handle. A leak can put astronauts or technicians at serious risk
Hydrazine is corrosive and can damage unprotected surfaces, think metal, skin, lungs, etc.
Its breakdown products are also toxic and corrosive, so it's still nasty after it is used
As hydrazine is toxic, corrosive, etc. it requires special equipment and procedures to transport and handle, which increases complexity of the overall system
High costs: it's expensive to produce to start, then there are additional costs to safely transport and handle it

Note that's not the complete list of why hydrazine is ugly stuff, it has the tendency to spontaneously explode on contact with certain materials, but that's why it's used in rocketry.
Comment: and another bullet item, rust, i.e. oxidised steel, is just another oxidiser as far as hydrazine is concerned, thereafter once decomposition has started the generated heat can make it self-sustaining. One can''t assume that stainless steel (i.e. CRES) will be rust free and so the propellant handling equipment has to be in pristine condition.
Comment: For small satellites that are piggybacked during launch with a larger spacecraft, the owner of that larger spacecraft along with the launch provider may both take a dim view of hydrazine on the piggybacked satellites.
Comment: Another bullet item: It and its decomposition products are also quite corrosive https://nj.gov/health/eoh/rtkweb/documents/fs/1006.pdf
Comment: Thanks @OrganicMarble, I've edited with some of those details.
Comment: @Puffin: I smell a liquisolid engine.
Comment: N2O is not absolutely safe to breath either https://en.wikipedia.org/wiki/Recreational_use_of_nitrous_oxide
Comment: Sure @fraxinus, but it doesn't melt your lungs in small concentrations.
Answer: Hydrazine, as for small monopropellant thrusters, has been in use for decades on hundreds of satellites.  One model the "1N Monopropellant Hydrazine Thruster" is claimed to be in use in 165 units.   Other models have similar deployment records.
Reference: space-propulsion.com.
Many studies of monopropellants were done during the 60s and 70s.  A book by: Belal, Hatem  -- 2009/05/26SP
Modeling of Hydrazine Decomposition for Monopropellant Thrusters presents a summary performance table of a few monopropellants, including hydrazine and $N_2O$.  I am attempting to paste in a summary table.  Here it goes:

Hydrazine has higher Isp but $N_2O$ has higher combustion temp likely needing more exotic materials.
Overall, hydrazine has such a built-in infrastructure, long-term installed performance base that it unlikely that it would be displaced.
The toxicity, carcinogenic properties, corrosiveness, etc. of hydrazine are greatly overstated from my experience.  I was working in the 60s in a small combustion research company. In one work area studies of hypergolic ignition parameters of $N_2O_4$ and hydrazine, UDMH, Aerozine 50, etc. were done.  High speed movies and temperature and gas composition measurements were done to support the testing. I lived in clouds of hydrazine and $N_2O_4$ fumes.  $N_2O_4$ was treated with respect.  Hydrazine was not treated with much concern.  Hydrazine has an ammonia odor and it was attempted to keep that as low as possible but there were no real safety limits.  Also, there were no easy measurement instruments for ambient concentrations. No one in our group has become ill from anything the could have been related to hydrazine and $N_2O_4$.  Likely this work could not be done today especially in a suburban industrial park.
In its document EPA estimates that, if an individual were to continuously breathe air containing hydrazine at an average of $0.0002 \hspace{1mm} {µg}/{m^3}$ ($2.0 * 10^{-7} \hspace{1mm} mg/m^3$) over his or her entire lifetime, that person would theoretically have no more than a one-in-a-million increased chance of developing cancer as a direct result of breathing air containing this chemical.
I think hydrazine will be used for a long time.
Comment: Fascinating! Hope you do not suffer any consequences.