qid int64 1 74.7M | question stringlengths 12 33.8k | date stringlengths 10 10 | metadata list | response_j stringlengths 0 115k | response_k stringlengths 2 98.3k |
|---|---|---|---|---|---|
12,601 | Reading about the Star KIC 8462852, it has been said that the SETI project turned its radio telescopes towards the star to search for extra terrestrial radio signals as the star had strange fluctuations in light. How can we point from earth a radio telescope towards a star which is 1480 light years away whilst the earth is spinning at 1675 km/h and keep it focused or, in the case of a radio telescope, aligned in order to try and receive radio waves?? | 2015/11/23 | [
"https://astronomy.stackexchange.com/questions/12601",
"https://astronomy.stackexchange.com",
"https://astronomy.stackexchange.com/users/1478/"
] | Part of the answer that I suspect the original questioner needs is that although the Earth is indeed spinning very fast, the amount the surface of the Earth moves relative to an astronomical object is tiny.
So you put motors in the base of the telescope so that it slowly turns to look at the same patch of sky. You don't need to refocus because telescopes are looking at objects so far away that focus doesn't matter. You don't need to do anything else because the Earth's movement is smooth and continuous, and it's not about how fast you're moving, it's about how quickly you're turning. In our case, one complete circle every 24 hours which is pretty slow.
Focus at infinity just means that you set the focus of the telescope so that an object which is infinitely far away would be in perfect focus. It depends on the quality of the telescope, but the practical difference between focus at infinity and focus at the actual distance disappears after a few miles or so. At the distance of stars, there is essentially no difference at all. | Because the speed of light is so much faster than the speed of the telescope, the star looks like it is standing still in the sky so the telescope only needs to track it as it moves across the sky at 15-degrees per hour.
However, the speed of light isn't infinite, and there is a measurable effect there. When you're riding in a car while it is raining and the rain preferentially hits your windshield, to you it looks like the rain is coming from some location in front of you even though it is falling straight down, and because of this when you try to look directly at the source of the rain, you look tilt your head forward rather than look straight up. The same thing happens with light from stars. Because the Earth is going around in its orbit and spinning on its axis, light falling "straight down" on us looks like it is coming from a position a little ahead. This is called [stellar aberration](https://en.wikipedia.org/wiki/Aberration_of_light). It isn't a large effect, but it is large enough that if you're trying to figure out very precisely where the stars are, then you need to correct for it. |
12,601 | Reading about the Star KIC 8462852, it has been said that the SETI project turned its radio telescopes towards the star to search for extra terrestrial radio signals as the star had strange fluctuations in light. How can we point from earth a radio telescope towards a star which is 1480 light years away whilst the earth is spinning at 1675 km/h and keep it focused or, in the case of a radio telescope, aligned in order to try and receive radio waves?? | 2015/11/23 | [
"https://astronomy.stackexchange.com/questions/12601",
"https://astronomy.stackexchange.com",
"https://astronomy.stackexchange.com/users/1478/"
] | There are two processes to manage this:
First, the telescopes (really, big antennas) are aimed mechanically and move so they can maintain their reception of a specific star/source/sky location over time.
However, except for stars immediately in the vicinity of the pole stars, the star will eventually go below the horizon. Once this happens the telescope/antenna cannot receive anything further until the source appears above the horizon again.
What happens at this point is we have many telescopes/antennas around the world that are collectively controlled. Long before a star/source/etc falls below the horizon for one telescope, another telescope further west has already pointed at it, and is receiving the same signal. Once this switchover has occurred, the previous telescope is free to select another target - something else on the other side of the planet that will be falling below the horizon for telescope further east.
In this way:
* The telescopes are under constant use pointing at interesting things
* Things which need continuous monitoring can be monitored without interruption despite the world turning
* We can observe anything at any time, as long as there's available time on the radio telescope network
* Sharing resources allows scientists to conduct science more completely and inexpensively
* By having 2 or more telescopes pointing at the same object at once, we can effectively increase the signal to noise ratio and get better data - it's technically very similar to having one earth sized single antenna rather than two tiny (relatively) antennas.
* With central control of a whole participating worldwide network, scientists can react very quickly to sudden phenomena, like bursts, at any time, regardless of the position of the earth | Let's say you go out on a warm summer day, lie down and look up at the stars. For some reason you manage to not fall asleep, while you only look at one star the whole night. You will have no problems pointing your eyes at this star (except for falling eyelids), like it is no problem to point a telescope at one star.
Edit:
curiousdannii is right, I didn't explain how. I will do this now: There is a machine called motor, or motor drive, or engine, which converts electrical energy into motion energy. With a little engineering, you can use this motion energy to turn the telescope. |
12,601 | Reading about the Star KIC 8462852, it has been said that the SETI project turned its radio telescopes towards the star to search for extra terrestrial radio signals as the star had strange fluctuations in light. How can we point from earth a radio telescope towards a star which is 1480 light years away whilst the earth is spinning at 1675 km/h and keep it focused or, in the case of a radio telescope, aligned in order to try and receive radio waves?? | 2015/11/23 | [
"https://astronomy.stackexchange.com/questions/12601",
"https://astronomy.stackexchange.com",
"https://astronomy.stackexchange.com/users/1478/"
] | There are two processes to manage this:
First, the telescopes (really, big antennas) are aimed mechanically and move so they can maintain their reception of a specific star/source/sky location over time.
However, except for stars immediately in the vicinity of the pole stars, the star will eventually go below the horizon. Once this happens the telescope/antenna cannot receive anything further until the source appears above the horizon again.
What happens at this point is we have many telescopes/antennas around the world that are collectively controlled. Long before a star/source/etc falls below the horizon for one telescope, another telescope further west has already pointed at it, and is receiving the same signal. Once this switchover has occurred, the previous telescope is free to select another target - something else on the other side of the planet that will be falling below the horizon for telescope further east.
In this way:
* The telescopes are under constant use pointing at interesting things
* Things which need continuous monitoring can be monitored without interruption despite the world turning
* We can observe anything at any time, as long as there's available time on the radio telescope network
* Sharing resources allows scientists to conduct science more completely and inexpensively
* By having 2 or more telescopes pointing at the same object at once, we can effectively increase the signal to noise ratio and get better data - it's technically very similar to having one earth sized single antenna rather than two tiny (relatively) antennas.
* With central control of a whole participating worldwide network, scientists can react very quickly to sudden phenomena, like bursts, at any time, regardless of the position of the earth | The way telescopes work is pretty much the same in the optical and radio wavelengths- the telescopes collect electromagnetic radiation, rather than focusing at a point. There are multiple reasons for this, the main one being the amount of photons reaching the telescope from the region of interest is pretty low.
In order to collect more photons, the telescope (or telescope array) has to 'look' into the area of interest for a long time- this is achieved in case of earth based telescopes by mechanically steering the antennae, so that they are pointed in the same direction for a long amount of time. The principle is pretty much [the same in space](https://en.wikipedia.org/wiki/Hubble_Ultra-Deep_Field).
For looking at KIC 8462852, SETI used the [Allen Telescope Arry](https://en.wikipedia.org/wiki/Allen_Telescope_Array), which is basically a set of 42 antennae scanning the skies in radio wavelengths. The problem of earth's rotation is basically solved in two steps by (radio) telescopes.
* By steering the antenna(e) as decided by the software so that the antenna points at the same position of the sky. For a star at ~1500 light years, the angular speed required is pretty small and can be easily supplied by the modern telescopes.
* Even if the star (or any other object of interest) passes below the horizon, the telescope can simply continue its work on the next day, gathering more photons. Of course, other telescopes can take over from this one, but the end result is the same- collecting more photons. |
12,601 | Reading about the Star KIC 8462852, it has been said that the SETI project turned its radio telescopes towards the star to search for extra terrestrial radio signals as the star had strange fluctuations in light. How can we point from earth a radio telescope towards a star which is 1480 light years away whilst the earth is spinning at 1675 km/h and keep it focused or, in the case of a radio telescope, aligned in order to try and receive radio waves?? | 2015/11/23 | [
"https://astronomy.stackexchange.com/questions/12601",
"https://astronomy.stackexchange.com",
"https://astronomy.stackexchange.com/users/1478/"
] | Because the speed of light is so much faster than the speed of the telescope, the star looks like it is standing still in the sky so the telescope only needs to track it as it moves across the sky at 15-degrees per hour.
However, the speed of light isn't infinite, and there is a measurable effect there. When you're riding in a car while it is raining and the rain preferentially hits your windshield, to you it looks like the rain is coming from some location in front of you even though it is falling straight down, and because of this when you try to look directly at the source of the rain, you look tilt your head forward rather than look straight up. The same thing happens with light from stars. Because the Earth is going around in its orbit and spinning on its axis, light falling "straight down" on us looks like it is coming from a position a little ahead. This is called [stellar aberration](https://en.wikipedia.org/wiki/Aberration_of_light). It isn't a large effect, but it is large enough that if you're trying to figure out very precisely where the stars are, then you need to correct for it. | The way telescopes work is pretty much the same in the optical and radio wavelengths- the telescopes collect electromagnetic radiation, rather than focusing at a point. There are multiple reasons for this, the main one being the amount of photons reaching the telescope from the region of interest is pretty low.
In order to collect more photons, the telescope (or telescope array) has to 'look' into the area of interest for a long time- this is achieved in case of earth based telescopes by mechanically steering the antennae, so that they are pointed in the same direction for a long amount of time. The principle is pretty much [the same in space](https://en.wikipedia.org/wiki/Hubble_Ultra-Deep_Field).
For looking at KIC 8462852, SETI used the [Allen Telescope Arry](https://en.wikipedia.org/wiki/Allen_Telescope_Array), which is basically a set of 42 antennae scanning the skies in radio wavelengths. The problem of earth's rotation is basically solved in two steps by (radio) telescopes.
* By steering the antenna(e) as decided by the software so that the antenna points at the same position of the sky. For a star at ~1500 light years, the angular speed required is pretty small and can be easily supplied by the modern telescopes.
* Even if the star (or any other object of interest) passes below the horizon, the telescope can simply continue its work on the next day, gathering more photons. Of course, other telescopes can take over from this one, but the end result is the same- collecting more photons. |
12,601 | Reading about the Star KIC 8462852, it has been said that the SETI project turned its radio telescopes towards the star to search for extra terrestrial radio signals as the star had strange fluctuations in light. How can we point from earth a radio telescope towards a star which is 1480 light years away whilst the earth is spinning at 1675 km/h and keep it focused or, in the case of a radio telescope, aligned in order to try and receive radio waves?? | 2015/11/23 | [
"https://astronomy.stackexchange.com/questions/12601",
"https://astronomy.stackexchange.com",
"https://astronomy.stackexchange.com/users/1478/"
] | First you are talking about pointing the telescope at the source not focusing it on the source. Telescopes are generally focused at infinity, and there is no need to compensate for the Earth's rotation in the focusing.
The speed of motion of the telescopes location on the Earth is also not directly relevant, what is relevant is the apparent rotation of the sky around the projection of the Earth's axis onto the sky. That is (in the Northern hemisphere) the rotation of the sky about the pole star.
There are a number of ways of dealing with the earth rotation.
1. Actually use it to scan over the sources
2. Drive the telescope to keep it pointing in the direction of interest
3. Track the source (use multiple channels to measure the source error from boresight and drive the telescope to to null the error).
:
etc
This really has nothing to do with radio telescopes per se, but is common to all telescopes including optical. | The way telescopes work is pretty much the same in the optical and radio wavelengths- the telescopes collect electromagnetic radiation, rather than focusing at a point. There are multiple reasons for this, the main one being the amount of photons reaching the telescope from the region of interest is pretty low.
In order to collect more photons, the telescope (or telescope array) has to 'look' into the area of interest for a long time- this is achieved in case of earth based telescopes by mechanically steering the antennae, so that they are pointed in the same direction for a long amount of time. The principle is pretty much [the same in space](https://en.wikipedia.org/wiki/Hubble_Ultra-Deep_Field).
For looking at KIC 8462852, SETI used the [Allen Telescope Arry](https://en.wikipedia.org/wiki/Allen_Telescope_Array), which is basically a set of 42 antennae scanning the skies in radio wavelengths. The problem of earth's rotation is basically solved in two steps by (radio) telescopes.
* By steering the antenna(e) as decided by the software so that the antenna points at the same position of the sky. For a star at ~1500 light years, the angular speed required is pretty small and can be easily supplied by the modern telescopes.
* Even if the star (or any other object of interest) passes below the horizon, the telescope can simply continue its work on the next day, gathering more photons. Of course, other telescopes can take over from this one, but the end result is the same- collecting more photons. |
12,601 | Reading about the Star KIC 8462852, it has been said that the SETI project turned its radio telescopes towards the star to search for extra terrestrial radio signals as the star had strange fluctuations in light. How can we point from earth a radio telescope towards a star which is 1480 light years away whilst the earth is spinning at 1675 km/h and keep it focused or, in the case of a radio telescope, aligned in order to try and receive radio waves?? | 2015/11/23 | [
"https://astronomy.stackexchange.com/questions/12601",
"https://astronomy.stackexchange.com",
"https://astronomy.stackexchange.com/users/1478/"
] | Because the speed of light is so much faster than the speed of the telescope, the star looks like it is standing still in the sky so the telescope only needs to track it as it moves across the sky at 15-degrees per hour.
However, the speed of light isn't infinite, and there is a measurable effect there. When you're riding in a car while it is raining and the rain preferentially hits your windshield, to you it looks like the rain is coming from some location in front of you even though it is falling straight down, and because of this when you try to look directly at the source of the rain, you look tilt your head forward rather than look straight up. The same thing happens with light from stars. Because the Earth is going around in its orbit and spinning on its axis, light falling "straight down" on us looks like it is coming from a position a little ahead. This is called [stellar aberration](https://en.wikipedia.org/wiki/Aberration_of_light). It isn't a large effect, but it is large enough that if you're trying to figure out very precisely where the stars are, then you need to correct for it. | Let's say you go out on a warm summer day, lie down and look up at the stars. For some reason you manage to not fall asleep, while you only look at one star the whole night. You will have no problems pointing your eyes at this star (except for falling eyelids), like it is no problem to point a telescope at one star.
Edit:
curiousdannii is right, I didn't explain how. I will do this now: There is a machine called motor, or motor drive, or engine, which converts electrical energy into motion energy. With a little engineering, you can use this motion energy to turn the telescope. |
12,601 | Reading about the Star KIC 8462852, it has been said that the SETI project turned its radio telescopes towards the star to search for extra terrestrial radio signals as the star had strange fluctuations in light. How can we point from earth a radio telescope towards a star which is 1480 light years away whilst the earth is spinning at 1675 km/h and keep it focused or, in the case of a radio telescope, aligned in order to try and receive radio waves?? | 2015/11/23 | [
"https://astronomy.stackexchange.com/questions/12601",
"https://astronomy.stackexchange.com",
"https://astronomy.stackexchange.com/users/1478/"
] | Because the speed of light is so much faster than the speed of the telescope, the star looks like it is standing still in the sky so the telescope only needs to track it as it moves across the sky at 15-degrees per hour.
However, the speed of light isn't infinite, and there is a measurable effect there. When you're riding in a car while it is raining and the rain preferentially hits your windshield, to you it looks like the rain is coming from some location in front of you even though it is falling straight down, and because of this when you try to look directly at the source of the rain, you look tilt your head forward rather than look straight up. The same thing happens with light from stars. Because the Earth is going around in its orbit and spinning on its axis, light falling "straight down" on us looks like it is coming from a position a little ahead. This is called [stellar aberration](https://en.wikipedia.org/wiki/Aberration_of_light). It isn't a large effect, but it is large enough that if you're trying to figure out very precisely where the stars are, then you need to correct for it. | The smart antennas are already in work and software controlled beam forming is also pretty much in use now.
Therefore, at even this very high spinning speed of the earth, the tracking of the stars at large distances is not that difficult.
Also high speed data acquisition and compression algorithms are there to help. So it's been with help of control engineering been possible to point at a specific celestial object. |
12,601 | Reading about the Star KIC 8462852, it has been said that the SETI project turned its radio telescopes towards the star to search for extra terrestrial radio signals as the star had strange fluctuations in light. How can we point from earth a radio telescope towards a star which is 1480 light years away whilst the earth is spinning at 1675 km/h and keep it focused or, in the case of a radio telescope, aligned in order to try and receive radio waves?? | 2015/11/23 | [
"https://astronomy.stackexchange.com/questions/12601",
"https://astronomy.stackexchange.com",
"https://astronomy.stackexchange.com/users/1478/"
] | Part of the answer that I suspect the original questioner needs is that although the Earth is indeed spinning very fast, the amount the surface of the Earth moves relative to an astronomical object is tiny.
So you put motors in the base of the telescope so that it slowly turns to look at the same patch of sky. You don't need to refocus because telescopes are looking at objects so far away that focus doesn't matter. You don't need to do anything else because the Earth's movement is smooth and continuous, and it's not about how fast you're moving, it's about how quickly you're turning. In our case, one complete circle every 24 hours which is pretty slow.
Focus at infinity just means that you set the focus of the telescope so that an object which is infinitely far away would be in perfect focus. It depends on the quality of the telescope, but the practical difference between focus at infinity and focus at the actual distance disappears after a few miles or so. At the distance of stars, there is essentially no difference at all. | There are two processes to manage this:
First, the telescopes (really, big antennas) are aimed mechanically and move so they can maintain their reception of a specific star/source/sky location over time.
However, except for stars immediately in the vicinity of the pole stars, the star will eventually go below the horizon. Once this happens the telescope/antenna cannot receive anything further until the source appears above the horizon again.
What happens at this point is we have many telescopes/antennas around the world that are collectively controlled. Long before a star/source/etc falls below the horizon for one telescope, another telescope further west has already pointed at it, and is receiving the same signal. Once this switchover has occurred, the previous telescope is free to select another target - something else on the other side of the planet that will be falling below the horizon for telescope further east.
In this way:
* The telescopes are under constant use pointing at interesting things
* Things which need continuous monitoring can be monitored without interruption despite the world turning
* We can observe anything at any time, as long as there's available time on the radio telescope network
* Sharing resources allows scientists to conduct science more completely and inexpensively
* By having 2 or more telescopes pointing at the same object at once, we can effectively increase the signal to noise ratio and get better data - it's technically very similar to having one earth sized single antenna rather than two tiny (relatively) antennas.
* With central control of a whole participating worldwide network, scientists can react very quickly to sudden phenomena, like bursts, at any time, regardless of the position of the earth |
12,601 | Reading about the Star KIC 8462852, it has been said that the SETI project turned its radio telescopes towards the star to search for extra terrestrial radio signals as the star had strange fluctuations in light. How can we point from earth a radio telescope towards a star which is 1480 light years away whilst the earth is spinning at 1675 km/h and keep it focused or, in the case of a radio telescope, aligned in order to try and receive radio waves?? | 2015/11/23 | [
"https://astronomy.stackexchange.com/questions/12601",
"https://astronomy.stackexchange.com",
"https://astronomy.stackexchange.com/users/1478/"
] | First you are talking about pointing the telescope at the source not focusing it on the source. Telescopes are generally focused at infinity, and there is no need to compensate for the Earth's rotation in the focusing.
The speed of motion of the telescopes location on the Earth is also not directly relevant, what is relevant is the apparent rotation of the sky around the projection of the Earth's axis onto the sky. That is (in the Northern hemisphere) the rotation of the sky about the pole star.
There are a number of ways of dealing with the earth rotation.
1. Actually use it to scan over the sources
2. Drive the telescope to keep it pointing in the direction of interest
3. Track the source (use multiple channels to measure the source error from boresight and drive the telescope to to null the error).
:
etc
This really has nothing to do with radio telescopes per se, but is common to all telescopes including optical. | Let's say you go out on a warm summer day, lie down and look up at the stars. For some reason you manage to not fall asleep, while you only look at one star the whole night. You will have no problems pointing your eyes at this star (except for falling eyelids), like it is no problem to point a telescope at one star.
Edit:
curiousdannii is right, I didn't explain how. I will do this now: There is a machine called motor, or motor drive, or engine, which converts electrical energy into motion energy. With a little engineering, you can use this motion energy to turn the telescope. |
31,793,428 | I have looked into SQLite with iOS development, and I found that the iPhone 6, and iPhone 7 will support SQLite version 3.7.13. I find it hard to believe that these are the ONLY ones that support it. Are there any iPads that also support it, and other iPhones like iPhone 6 Plus? | 2015/08/03 | [
"https://Stackoverflow.com/questions/31793428",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/5128009/"
] | SQLite has been supplied with iOS since iOS 2.0. It is available for any iOS device. There is no reason to think that will stop.
But even if Apple stopped supplying it, you could still use it. It's just a third party library you can include in your app.
Its support is based on being part of your app, not any specific device or version of iOS. | Yes IPhone and iPad support sqlite It is part of Core Services in ios architecture layers |
11,386,111 | I'm stuck with a question I can't find an answer to in the official documentation, on Stackoverflow or on Google.
I'm an experienced iOS developer but new to Storyboards. I'd like to instantiate a view on the current viewcontroller, a view that, in a NIB, I would draw outside the viewController and attach an outlet to to refer to it in code and call something like addSubview: or so. It's useful to draw an overlay or, in my current case, a callout view for use in a MapView delegate. But I can't figure out how I can do this in a Storyboard.
I can't seem to have a view outside of a viewcontroller, and views inside the viewcontroller either have to be subviews of the controller's view or don't be visible in Interface Builder at all (which is okay when you drag a view composed outside, in a traditional NIB, but quite a problem if you need to tweak even the least detail of it).
Any hint on what to do or where to look? Thanks. | 2012/07/08 | [
"https://Stackoverflow.com/questions/11386111",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/364446/"
] | It appears there is no way to do it. See [Jason's comment](https://stackoverflow.com/questions/11386111/uiview-outside-of-a-view-controller-in-a-storyboard#comment15008191_11386111) and [this question](https://stackoverflow.com/questions/9648076/how-to-design-separate-uiview-outside-of-any-viewcontroller-in-storyboard) addressing the same problem, though in a different context.
However, I realised earlier when thinking about the implications of my problem — as I began to explain in [my previous comment](https://stackoverflow.com/questions/11386111/uiview-outside-of-a-view-controller-in-a-storyboard#comment15010381_11386111) before deciding it would be worth a full answer — it makes sense to separate the design of a custom view from the design of an application flow. So the fact that it's not possible to design custom views in Storyboards may very well be... by design.
A custom view (which is a reusable component) is very different from a view controller (which represents a scene in your application storyboard). It's the same as a character and a scene, in a movie. You don't want to design your character in your scene, even if you happen to use that character in only one scene. It's fortuitous if you use it in only one scene, but not essential. So it has to be separate.
The fact that you want to use Interface Builder to design your custom view is only [an implementation detail](https://stackoverflow.com/questions/8976873/uiviewcontrollers-initwithnibname-a-reason-behind-this-design) that should be encapsulated in your class. The application storyboard has no need of knowing, even less managing, how you deal with the particular implementation of your reusable view.
Hmm, I wish I had more of this brand of interrogation :) | I was wondering the same thing myself, and actually was able to get this to happen, though after messing around, its gone. I have a Nav Controller, a View Controller and two views. I had developed the views in a separate nib, and imported them to this project. While was was connecting buttons, the view I was working in suddenly appeared next to my View Controller. Unfortunately, while trying to get the other view to appear, I somehow lost it, and dont know how to get it back. It doesnt seem like you can drag a view to the storyboard, only into a view controller. However, if I was able to do it once, its got to be reproduceable. |
11,386,111 | I'm stuck with a question I can't find an answer to in the official documentation, on Stackoverflow or on Google.
I'm an experienced iOS developer but new to Storyboards. I'd like to instantiate a view on the current viewcontroller, a view that, in a NIB, I would draw outside the viewController and attach an outlet to to refer to it in code and call something like addSubview: or so. It's useful to draw an overlay or, in my current case, a callout view for use in a MapView delegate. But I can't figure out how I can do this in a Storyboard.
I can't seem to have a view outside of a viewcontroller, and views inside the viewcontroller either have to be subviews of the controller's view or don't be visible in Interface Builder at all (which is okay when you drag a view composed outside, in a traditional NIB, but quite a problem if you need to tweak even the least detail of it).
Any hint on what to do or where to look? Thanks. | 2012/07/08 | [
"https://Stackoverflow.com/questions/11386111",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/364446/"
] | It appears there is no way to do it. See [Jason's comment](https://stackoverflow.com/questions/11386111/uiview-outside-of-a-view-controller-in-a-storyboard#comment15008191_11386111) and [this question](https://stackoverflow.com/questions/9648076/how-to-design-separate-uiview-outside-of-any-viewcontroller-in-storyboard) addressing the same problem, though in a different context.
However, I realised earlier when thinking about the implications of my problem — as I began to explain in [my previous comment](https://stackoverflow.com/questions/11386111/uiview-outside-of-a-view-controller-in-a-storyboard#comment15010381_11386111) before deciding it would be worth a full answer — it makes sense to separate the design of a custom view from the design of an application flow. So the fact that it's not possible to design custom views in Storyboards may very well be... by design.
A custom view (which is a reusable component) is very different from a view controller (which represents a scene in your application storyboard). It's the same as a character and a scene, in a movie. You don't want to design your character in your scene, even if you happen to use that character in only one scene. It's fortuitous if you use it in only one scene, but not essential. So it has to be separate.
The fact that you want to use Interface Builder to design your custom view is only [an implementation detail](https://stackoverflow.com/questions/8976873/uiviewcontrollers-initwithnibname-a-reason-behind-this-design) that should be encapsulated in your class. The application storyboard has no need of knowing, even less managing, how you deal with the particular implementation of your reusable view.
Hmm, I wish I had more of this brand of interrogation :) | You can use a Container View, is like a regular view(You can assign a IBOutlet UIView) but you can define it outside of your UIViewController.
 |
11,386,111 | I'm stuck with a question I can't find an answer to in the official documentation, on Stackoverflow or on Google.
I'm an experienced iOS developer but new to Storyboards. I'd like to instantiate a view on the current viewcontroller, a view that, in a NIB, I would draw outside the viewController and attach an outlet to to refer to it in code and call something like addSubview: or so. It's useful to draw an overlay or, in my current case, a callout view for use in a MapView delegate. But I can't figure out how I can do this in a Storyboard.
I can't seem to have a view outside of a viewcontroller, and views inside the viewcontroller either have to be subviews of the controller's view or don't be visible in Interface Builder at all (which is okay when you drag a view composed outside, in a traditional NIB, but quite a problem if you need to tweak even the least detail of it).
Any hint on what to do or where to look? Thanks. | 2012/07/08 | [
"https://Stackoverflow.com/questions/11386111",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/364446/"
] | You can use a Container View, is like a regular view(You can assign a IBOutlet UIView) but you can define it outside of your UIViewController.
 | I was wondering the same thing myself, and actually was able to get this to happen, though after messing around, its gone. I have a Nav Controller, a View Controller and two views. I had developed the views in a separate nib, and imported them to this project. While was was connecting buttons, the view I was working in suddenly appeared next to my View Controller. Unfortunately, while trying to get the other view to appear, I somehow lost it, and dont know how to get it back. It doesnt seem like you can drag a view to the storyboard, only into a view controller. However, if I was able to do it once, its got to be reproduceable. |
60,322 | I'm in the job market and I have a set of priorities for my next job including salary, line of business, etc. One thing that is nowhere on my list of requirements however, is the development process methodology. I feel my job is to create software and I view the process structure as something I can adapt to whether it's scrum or waterfall or whatever.
Is the development process methodology a priority for you? | 2011/03/21 | [
"https://softwareengineering.stackexchange.com/questions/60322",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/18957/"
] | As a developer, I care that the development process is sane. A number of different development methodologies can provide a sane development process. Conversely a broken company can provide an insane process no matter what they call it.
Therefore I don't particularly care what their official "development methodology" is. However I'll still ask about it simply because it gives a context for me to ask follow-up questions to figure out what they are *really* doing. | Yes, I've seen some poor methodologies that I don't think I'd want to repeat again. As a couple of examples, consider these: Would you be alright with a cowboy style for a team of a dozen developers where everyone may use their own source control, coding conventions, etc? I know I wouldn't. How about where to change a line of code there are a dozen forms to fill out and a about 20 signatures to OK the change in production that may take weeks to get done as the senior management sign off may take a while to get? The "whatever" leaves things a bit too open to my mind but then maybe I'm a little cyncial here. |
60,322 | I'm in the job market and I have a set of priorities for my next job including salary, line of business, etc. One thing that is nowhere on my list of requirements however, is the development process methodology. I feel my job is to create software and I view the process structure as something I can adapt to whether it's scrum or waterfall or whatever.
Is the development process methodology a priority for you? | 2011/03/21 | [
"https://softwareengineering.stackexchange.com/questions/60322",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/18957/"
] | Yes, I've seen some poor methodologies that I don't think I'd want to repeat again. As a couple of examples, consider these: Would you be alright with a cowboy style for a team of a dozen developers where everyone may use their own source control, coding conventions, etc? I know I wouldn't. How about where to change a line of code there are a dozen forms to fill out and a about 20 signatures to OK the change in production that may take weeks to get done as the senior management sign off may take a while to get? The "whatever" leaves things a bit too open to my mind but then maybe I'm a little cyncial here. | So long as we have some semblance of sensible requirements, some business representative who is engaged and responsive, and an understanding that the dev team has a large say in timescales, then I'm happy and I can fit into anything. |
60,322 | I'm in the job market and I have a set of priorities for my next job including salary, line of business, etc. One thing that is nowhere on my list of requirements however, is the development process methodology. I feel my job is to create software and I view the process structure as something I can adapt to whether it's scrum or waterfall or whatever.
Is the development process methodology a priority for you? | 2011/03/21 | [
"https://softwareengineering.stackexchange.com/questions/60322",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/18957/"
] | As a developer, I care that the development process is sane. A number of different development methodologies can provide a sane development process. Conversely a broken company can provide an insane process no matter what they call it.
Therefore I don't particularly care what their official "development methodology" is. However I'll still ask about it simply because it gives a context for me to ask follow-up questions to figure out what they are *really* doing. | So long as we have some semblance of sensible requirements, some business representative who is engaged and responsive, and an understanding that the dev team has a large say in timescales, then I'm happy and I can fit into anything. |
60,322 | I'm in the job market and I have a set of priorities for my next job including salary, line of business, etc. One thing that is nowhere on my list of requirements however, is the development process methodology. I feel my job is to create software and I view the process structure as something I can adapt to whether it's scrum or waterfall or whatever.
Is the development process methodology a priority for you? | 2011/03/21 | [
"https://softwareengineering.stackexchange.com/questions/60322",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/18957/"
] | I prefer places that have a development method that everyone can actually follow. | So long as we have some semblance of sensible requirements, some business representative who is engaged and responsive, and an understanding that the dev team has a large say in timescales, then I'm happy and I can fit into anything. |
60,322 | I'm in the job market and I have a set of priorities for my next job including salary, line of business, etc. One thing that is nowhere on my list of requirements however, is the development process methodology. I feel my job is to create software and I view the process structure as something I can adapt to whether it's scrum or waterfall or whatever.
Is the development process methodology a priority for you? | 2011/03/21 | [
"https://softwareengineering.stackexchange.com/questions/60322",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/18957/"
] | As a developer, I care that the development process is sane. A number of different development methodologies can provide a sane development process. Conversely a broken company can provide an insane process no matter what they call it.
Therefore I don't particularly care what their official "development methodology" is. However I'll still ask about it simply because it gives a context for me to ask follow-up questions to figure out what they are *really* doing. | I've worked in jobs that were very frustrating because of process choices used for development and business in general. These days I have some minimum requirements for process. Any business that doesn't engage in these I consider poorly run and will not work for. I don't have the patience for idiocy I used to have so I save myself and them alot of aggravation by skipping those jobs. |
60,322 | I'm in the job market and I have a set of priorities for my next job including salary, line of business, etc. One thing that is nowhere on my list of requirements however, is the development process methodology. I feel my job is to create software and I view the process structure as something I can adapt to whether it's scrum or waterfall or whatever.
Is the development process methodology a priority for you? | 2011/03/21 | [
"https://softwareengineering.stackexchange.com/questions/60322",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/18957/"
] | I prefer places that have a development method that everyone can actually follow. | I've worked in jobs that were very frustrating because of process choices used for development and business in general. These days I have some minimum requirements for process. Any business that doesn't engage in these I consider poorly run and will not work for. I don't have the patience for idiocy I used to have so I save myself and them alot of aggravation by skipping those jobs. |
60,322 | I'm in the job market and I have a set of priorities for my next job including salary, line of business, etc. One thing that is nowhere on my list of requirements however, is the development process methodology. I feel my job is to create software and I view the process structure as something I can adapt to whether it's scrum or waterfall or whatever.
Is the development process methodology a priority for you? | 2011/03/21 | [
"https://softwareengineering.stackexchange.com/questions/60322",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/18957/"
] | As a developer I don't mind which methodology it is, as long as it is proper methodology, properly used.
So for example I wouldn't like to work for company which does ["cowboy coding"](http://en.wikipedia.org/wiki/Cowboy_coding), especially if they are ignorant enough to think that they're actually doing [Agile](http://en.wikipedia.org/wiki/Agile_software_development). | I've worked in jobs that were very frustrating because of process choices used for development and business in general. These days I have some minimum requirements for process. Any business that doesn't engage in these I consider poorly run and will not work for. I don't have the patience for idiocy I used to have so I save myself and them alot of aggravation by skipping those jobs. |
6,737 | I'm not asking what will happen if everyone in the world suddenly turned to vegetarianism. In an ideal world with the current population, can everyone follow a vegetarian diet (except for people who may need to eat meat if they have allergies to some other vegetarian alternative)?
I've tried to search for answers but all I found was things like what would happen if everyone suddenly turned vegetarian or things like that. But I want to know can everyone turn into vegetarianism in some time? If yes/no, how much population can Earth sustain if everyone is always a vegetarian. Also, animals would only be breed in zoological parks or for medical or some other science related needs (or for exceptional cases) | 2018/07/16 | [
"https://sustainability.stackexchange.com/questions/6737",
"https://sustainability.stackexchange.com",
"https://sustainability.stackexchange.com/users/5873/"
] | [Earth's total land area is 196.9 million square miles.](https://www.google.com/search?q=what%20is%20earth%27s%20land%20area&oq=what%20is%20earth%27s%20land%20area)
[The proportion of this which is farmable is 37.7%.](https://sciencing.com/much-earths-land-farmable-16685.html)
Therefore the total farmable land area is 74 million square miles.
[Intensively cultivated corn yields 15 million kcal per acre.](https://www.washingtonpost.com/lifestyle/food/in-defense-of-corn-the-worlds-most-important-food-crop/2015/07/12/78d86530-25a8-11e5-b77f-eb13a215f593_story.html)
There are 640 acres per square mile.
Therefore intensively cultivated corn yields 9.6 billion kcal per square mile.
Therefore intensively cultivating corn on all farmable land on earth would produce 7.1 \* 10^17 kcal (9.6 \* 10^9 \* 74 \* 10^6).
Each human needs 7.3 \* 10^5 kcal per year (based on 2000 kcal/day).
Therefore, the number of humans that can be fed if all farmable land on earth grows corn is 970 billion ((7.1 \* 10^17) / (7.3 \* 10^5)).
If you like eating (field!) corn all day, every day, that is. Also, it's a good thing there's an unlimited supply of natural gas because [this is a (practically) required feedstock in producing all that corn](https://en.wikipedia.org/wiki/Haber_process#Sources_of_hydrogen). | The carrying capacity of planet Earth is about 1 billion Humans (with lifestyles similar to the USA in 1999). There are over 7.6 billion people on the planet right now. We're in overshoot. Our current population is only possible because we are exploiting non-renewable energy sources. As they run out the population will crash and ultimately stabilise at an equilibrium level — a small fraction of what it is now.
At this point it really doesn't matter what you eat. The best thing you can do to sustain life on Earth is to avoid having children.
Trivia: Each Joule of energy you get from corn requires the same amount in oil to produce. Apples and chicken require about 7x as much oil as they yield in nutritional energy. Milk is ~2x. Pork is ~12x. Beef is ~23x.
The average US diet a few years ago required 9 Joules of fossil fuels for every 1 Joule of food consumed. It is tempting to use this as a mathematical basis for saying "the planet can support 11x as many vegetarians as is can normal people" — but that would be a mistake.
The depletion of non-renewable energy sources (oil, specifically) will *force* the Human species to find more *economical* food sources... but that won't lift the carrying capacity of the planet because solar panels displace photosynthesis.
Overshoot is overshoot. Unless someone manages to defy the laws of physics and invent **Free and Unlimited Energy™** we're in for some rude shocks as the crude runs out.
tl;dr: **The Earth cannot sustainably support the current population, regardless of what they eat. Switching from an omnivorous to a vegetarian diet won't change that.** The Earth can, however, sustainably support about 1 billion people. When natural forces reduce our population back down to that level folks will have more pressing issues on their minds and no-one will care what people eat. Diet is not the problem — (over)population and extravagant (energy-demanding) lifestyles are. |
6,737 | I'm not asking what will happen if everyone in the world suddenly turned to vegetarianism. In an ideal world with the current population, can everyone follow a vegetarian diet (except for people who may need to eat meat if they have allergies to some other vegetarian alternative)?
I've tried to search for answers but all I found was things like what would happen if everyone suddenly turned vegetarian or things like that. But I want to know can everyone turn into vegetarianism in some time? If yes/no, how much population can Earth sustain if everyone is always a vegetarian. Also, animals would only be breed in zoological parks or for medical or some other science related needs (or for exceptional cases) | 2018/07/16 | [
"https://sustainability.stackexchange.com/questions/6737",
"https://sustainability.stackexchange.com",
"https://sustainability.stackexchange.com/users/5873/"
] | The answer by Jean-Paul Calderone correctly specified how much population the food can support. I'm not focusing on that at all in my answer; I'm only focusing on energy.
This answer, however, did not take into account energy aspects, only mentioning than an unlimited supply of natural gas is needed. That is most certainly false: methane can be created with only energy, carbon dioxide and water as the source materials. As we all know, there is no shortage of carbon dioxide.
Carbon dioxide can be recycled in industrial processes, and natural gas can be synthetically created using water electrolysis and Sabatier reaction.
Thus, the only problem is how much input energy we can harness. Solar radiation is 1000 W / square meter on non-cloudy days, and Earth receives 1.27\*10^14 square meters of radiation minus clouds. If we could harness only 1% of the radiation before clouds (seems doable), we have 1275 terawatts of radiation. This is 11166905 terawatt hours per year.
US primary energy use is 88000 kWh / year / capita ([source](https://en.wikipedia.org/wiki/World_energy_consumption#Trends)). Thus, it is possible to support **127 billion people having US lifestyle**.
More likely, the answer would be larger, as 30% of Earth is land, cloudy days are perhaps 50% of the days and we could perfectly well use 15% of landmass for solar power and the rest 85% for other purposes. Thus, 0.30 \* 0.50 \* 0.15 = 0.0225, or 2.25%, larger than 1%.
So, even with solar radiation as the only energy source, a US lifestyle is possible for hundreds of billions of people.
If we want to support a larger number of people, e.g. thousands of billions of people all having a western lifestyle, we cannot do it with solar power only, but there is always the nuclear option. Once-through fission cycle will quickly lead to exhaustion of cheap uranium. However, it is possible to build breeder reactors that use uranium 50-100 times more efficiently than current reactors.
With such breeder reactors, at the current consumption level, uranium will last for billions of years ([source](http://www-formal.stanford.edu/jmc/progress/cohen.html)).
Multiply the population having a western lifestyle by 1000, and uranium is still enough for millions of years. Some could consider it unsustainable if the human population runs out of energy in millions years. Some other could consider it sustainable enough.
I'm not saying these breeder reactors are the optimal solution. Growth to population of 127 billion seems unlikely, so it is likely that exponentially reducing solar power production costs mean solar power will be enough and needs not be supplemented by nuclear.
Also, with a population of 1000 billion, all using nuclear power to have a western lifestyle, the waste heat would be enormous and could somewhat heat up the planet directly.
Some might protest that solar can be generated only when sun shines and there are not enough battery minerals for storing that electricity for cloudy days. The most likely solution to this problem is power-to-gas, where solar power is stored as synthetic hydrogen or synthetic methane (along with carbon dioxide recycling, of course, if methane is selected instead of hydrogen). Enormous amounts of energy can be stored as gas, with no need for battery minerals. | [Earth's total land area is 196.9 million square miles.](https://www.google.com/search?q=what%20is%20earth%27s%20land%20area&oq=what%20is%20earth%27s%20land%20area)
[The proportion of this which is farmable is 37.7%.](https://sciencing.com/much-earths-land-farmable-16685.html)
Therefore the total farmable land area is 74 million square miles.
[Intensively cultivated corn yields 15 million kcal per acre.](https://www.washingtonpost.com/lifestyle/food/in-defense-of-corn-the-worlds-most-important-food-crop/2015/07/12/78d86530-25a8-11e5-b77f-eb13a215f593_story.html)
There are 640 acres per square mile.
Therefore intensively cultivated corn yields 9.6 billion kcal per square mile.
Therefore intensively cultivating corn on all farmable land on earth would produce 7.1 \* 10^17 kcal (9.6 \* 10^9 \* 74 \* 10^6).
Each human needs 7.3 \* 10^5 kcal per year (based on 2000 kcal/day).
Therefore, the number of humans that can be fed if all farmable land on earth grows corn is 970 billion ((7.1 \* 10^17) / (7.3 \* 10^5)).
If you like eating (field!) corn all day, every day, that is. Also, it's a good thing there's an unlimited supply of natural gas because [this is a (practically) required feedstock in producing all that corn](https://en.wikipedia.org/wiki/Haber_process#Sources_of_hydrogen). |
6,737 | I'm not asking what will happen if everyone in the world suddenly turned to vegetarianism. In an ideal world with the current population, can everyone follow a vegetarian diet (except for people who may need to eat meat if they have allergies to some other vegetarian alternative)?
I've tried to search for answers but all I found was things like what would happen if everyone suddenly turned vegetarian or things like that. But I want to know can everyone turn into vegetarianism in some time? If yes/no, how much population can Earth sustain if everyone is always a vegetarian. Also, animals would only be breed in zoological parks or for medical or some other science related needs (or for exceptional cases) | 2018/07/16 | [
"https://sustainability.stackexchange.com/questions/6737",
"https://sustainability.stackexchange.com",
"https://sustainability.stackexchange.com/users/5873/"
] | The answer by Jean-Paul Calderone correctly specified how much population the food can support. I'm not focusing on that at all in my answer; I'm only focusing on energy.
This answer, however, did not take into account energy aspects, only mentioning than an unlimited supply of natural gas is needed. That is most certainly false: methane can be created with only energy, carbon dioxide and water as the source materials. As we all know, there is no shortage of carbon dioxide.
Carbon dioxide can be recycled in industrial processes, and natural gas can be synthetically created using water electrolysis and Sabatier reaction.
Thus, the only problem is how much input energy we can harness. Solar radiation is 1000 W / square meter on non-cloudy days, and Earth receives 1.27\*10^14 square meters of radiation minus clouds. If we could harness only 1% of the radiation before clouds (seems doable), we have 1275 terawatts of radiation. This is 11166905 terawatt hours per year.
US primary energy use is 88000 kWh / year / capita ([source](https://en.wikipedia.org/wiki/World_energy_consumption#Trends)). Thus, it is possible to support **127 billion people having US lifestyle**.
More likely, the answer would be larger, as 30% of Earth is land, cloudy days are perhaps 50% of the days and we could perfectly well use 15% of landmass for solar power and the rest 85% for other purposes. Thus, 0.30 \* 0.50 \* 0.15 = 0.0225, or 2.25%, larger than 1%.
So, even with solar radiation as the only energy source, a US lifestyle is possible for hundreds of billions of people.
If we want to support a larger number of people, e.g. thousands of billions of people all having a western lifestyle, we cannot do it with solar power only, but there is always the nuclear option. Once-through fission cycle will quickly lead to exhaustion of cheap uranium. However, it is possible to build breeder reactors that use uranium 50-100 times more efficiently than current reactors.
With such breeder reactors, at the current consumption level, uranium will last for billions of years ([source](http://www-formal.stanford.edu/jmc/progress/cohen.html)).
Multiply the population having a western lifestyle by 1000, and uranium is still enough for millions of years. Some could consider it unsustainable if the human population runs out of energy in millions years. Some other could consider it sustainable enough.
I'm not saying these breeder reactors are the optimal solution. Growth to population of 127 billion seems unlikely, so it is likely that exponentially reducing solar power production costs mean solar power will be enough and needs not be supplemented by nuclear.
Also, with a population of 1000 billion, all using nuclear power to have a western lifestyle, the waste heat would be enormous and could somewhat heat up the planet directly.
Some might protest that solar can be generated only when sun shines and there are not enough battery minerals for storing that electricity for cloudy days. The most likely solution to this problem is power-to-gas, where solar power is stored as synthetic hydrogen or synthetic methane (along with carbon dioxide recycling, of course, if methane is selected instead of hydrogen). Enormous amounts of energy can be stored as gas, with no need for battery minerals. | The carrying capacity of planet Earth is about 1 billion Humans (with lifestyles similar to the USA in 1999). There are over 7.6 billion people on the planet right now. We're in overshoot. Our current population is only possible because we are exploiting non-renewable energy sources. As they run out the population will crash and ultimately stabilise at an equilibrium level — a small fraction of what it is now.
At this point it really doesn't matter what you eat. The best thing you can do to sustain life on Earth is to avoid having children.
Trivia: Each Joule of energy you get from corn requires the same amount in oil to produce. Apples and chicken require about 7x as much oil as they yield in nutritional energy. Milk is ~2x. Pork is ~12x. Beef is ~23x.
The average US diet a few years ago required 9 Joules of fossil fuels for every 1 Joule of food consumed. It is tempting to use this as a mathematical basis for saying "the planet can support 11x as many vegetarians as is can normal people" — but that would be a mistake.
The depletion of non-renewable energy sources (oil, specifically) will *force* the Human species to find more *economical* food sources... but that won't lift the carrying capacity of the planet because solar panels displace photosynthesis.
Overshoot is overshoot. Unless someone manages to defy the laws of physics and invent **Free and Unlimited Energy™** we're in for some rude shocks as the crude runs out.
tl;dr: **The Earth cannot sustainably support the current population, regardless of what they eat. Switching from an omnivorous to a vegetarian diet won't change that.** The Earth can, however, sustainably support about 1 billion people. When natural forces reduce our population back down to that level folks will have more pressing issues on their minds and no-one will care what people eat. Diet is not the problem — (over)population and extravagant (energy-demanding) lifestyles are. |
13,082,149 | After getting tired of numerous Match-O linker error, I want to know that this thing means. Instead of trial and error solution, I would like to know the concept behind these things. Specifically I want to know the difference between :
1. Executable
2. Dynamic Library
3. Bundle
4. Static Library
5. Relocatable Object File
These are the options presented when I click on Mach-O Type settings on Linking section. Some small definition or some link to appropriate content is ok too. | 2012/10/26 | [
"https://Stackoverflow.com/questions/13082149",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/341800/"
] | [Mach-O](http://en.wikipedia.org/wiki/Mach-O), short for Mach object file format, is a file format for executables, object code, shared libraries, dynamically-loaded code, and core dumps. For unix users this is like `a.out` but with improvements. This is the format used in Mac OS X and iPhone OS libraries for executable files.
As you know iOS devices (iPhone, iPad etc.) have different architectures ARMv6 (iPhone 2G + 3G, iPod Touch) and ARMv7 (iPhone 3GS, iPod Touch 2G + 3G) but the simulators used in Xcode runs mostly on i386 platform. This means the that the library clients have to setup separate targets for the simulator and device. The separate targets duplicate most information, and only differ in the static libraries included. So if you are getting a Mach-O linker error what it means is that xcode is having trouble linking to one of the libraries for that target device; as a result of which compilation fails.
Now your definitions -
1. Executable - compiled machine targeted program ready to be run in binary format.
2. Dynamic Library - are linked during runtime -- a program with references to a dynamic library will load and link with the library when it starts up (or on demand).
3. Bundles - and bundle identifier let iOS and OSX recognise any updates to your app. It gives it a unique presence in the app.
4. Static Library - files are linked at build time. code is copied into the executable. Code in the library that isn't referenced by your program is removed. A program with only static libraries doesn't have any dependencies during runtime.
5. Relocatable Object File - is another word for a dynamic library. When you link with a dynamic library, the addresses of the functions contained within are computed, based on where the library is loaded in memory. They are "relocatable" because the addresses of the contained functions are not determined at link time. (In a static library, the addresses are computed during link time.) | As per apple documentation,
Check this for more details [Building Mach-O Files](https://developer.apple.com/library/mac/#documentation/developertools/conceptual/MachOTopics/1-Articles/building_files.html) and [Xcode Build Setting Reference](https://developer.apple.com/library/mac/#documentation/DeveloperTools/Reference/XcodeBuildSettingRef/1-Build_Setting_Reference/build_setting_ref.html) |
202,472 | I was just looking at this question: [How much freedom should a programmer have in choosing a language and framework?](https://softwareengineering.stackexchange.com/questions/214639/how-much-freedom-should-a-programmer-have-in-choosing-a-language-and-framework)
As I was reading the question, the very last line seemed sort of out-of-place and weirdly phrased for where it was, but I didn't think much of it. Then I was reading the comments and one read:
>
> Please do not put monikers like "EDIT" in your posts. We already know
> the post was edited; a complete edit history of your question can be
> found here:
> <https://softwareengineering.stackexchange.com/posts/214639/revisions>.
>
>
>
Apparently the last line of the question *had* originally been prefixed with "EDIT:", which was later removed. And in my opinion the line would have made more sense contextually as an explicit called-out edit.
But this example aside (it's honestly not the best example, just used it for the comment), I generally don't buy the argument that "EDIT:" should never be included in the post body. While I agree that sometimes "EDIT" can just be noise, this is not always the case.
* An explicitly called out "EDIT:" has an editorial meaning. It's a stand-in for "ADDENDUM:" or "UPDATE:", and can help logically separate parts of the post by chronology or topicality. It adds value by making the structure of the post clearer. When used properly, it is not simply noise.
* Secondly, it's a little misleading to say we "already know the post was edited". I, in fact, don't usually check to see if a post was edited when I'm reading it, and even if I do notice the "edited..." line, all that tells me is *that* it was edited, not how so. Knowing that it was edited it not the same as knowing how -- and I almost never look at the revision history. There's not usually a good reason to. Many edits don't even alter the post content in any substantial ways (just formatting/spelling/grammar fixes), and for those that do the edit is not usually relevant to the me, the reader.
Furthermore, I've seen "EDIT:" in many posts before seeing this, and I've even included it in some of my posts (a very small subset of my edits -- only those where it made sense to call it out explicitly), and this is the first time I've seen its usage admonished.
Is this a standard admonishment? Do you disagree with my reasoning above about why I think "EDIT:" isn't necessarily noise? | 2013/10/21 | [
"https://meta.stackexchange.com/questions/202472",
"https://meta.stackexchange.com",
"https://meta.stackexchange.com/users/155650/"
] | Personally, I'm inclined to disagree. Stack Overflow is not a forum, so it shouldn't be necessary to 'separate parts of the post by chronology or topicality' - each question should be as self-contained as possible, and should be constrained to a single topic at hand. **One question, one answer.**
*EDIT:* usually means one of a few things, in my experience.
1. OK, that solved my immediate problem, but I still have this other one.
2. OK, I tried that, but it didn't work.
3. OK, here's another code dump since you asked for it.
4. OMG I found the answer!
In the first case, this should be posted as a separate question.
In the second or third case, this can still be part of the same question, but adding "EDIT:" only signals something to those people who have already read the question. Usually, these people will be invested enough in the question to notice.
The fourth case should obviously be posted as an answer instead.
If you really want to be sure that people who have already interacted with the question will notice that a change has been made, **you can add a comment to your question, or to any relevant answers you've received so far**. These are the second-class citizens of Stack Overflow, where transitory information like this can be given.
In both cases, what does it add in the long run? Speaking broadly, people who come to this question a year later will not care that something was appended to the question between the time it was created and the time it was accessed. Those who do will still have the edit summaries (and possibly the comments), because that it what they are for.
In other words:
>
> I almost never look at the revision history. There's not usually a good reason to...the edit is not usually relevant to the me, the reader.
>
>
> | I don't think EDIT means the same as ADDENDUM or UPDATE. Those mean that something was added. EDIT means something was changed. I don't think it's really necessary to put EDIT in the body of your posts, since the revision history is linked at the bottom for anyone to look at.
If it needs to be pointed out in the body of the question that it was edited (for example, in response to a comment) then the reason should probably be spelled out instead of simply saying EDIT. I usually remove it and try to make the question flow more naturally. |
202,472 | I was just looking at this question: [How much freedom should a programmer have in choosing a language and framework?](https://softwareengineering.stackexchange.com/questions/214639/how-much-freedom-should-a-programmer-have-in-choosing-a-language-and-framework)
As I was reading the question, the very last line seemed sort of out-of-place and weirdly phrased for where it was, but I didn't think much of it. Then I was reading the comments and one read:
>
> Please do not put monikers like "EDIT" in your posts. We already know
> the post was edited; a complete edit history of your question can be
> found here:
> <https://softwareengineering.stackexchange.com/posts/214639/revisions>.
>
>
>
Apparently the last line of the question *had* originally been prefixed with "EDIT:", which was later removed. And in my opinion the line would have made more sense contextually as an explicit called-out edit.
But this example aside (it's honestly not the best example, just used it for the comment), I generally don't buy the argument that "EDIT:" should never be included in the post body. While I agree that sometimes "EDIT" can just be noise, this is not always the case.
* An explicitly called out "EDIT:" has an editorial meaning. It's a stand-in for "ADDENDUM:" or "UPDATE:", and can help logically separate parts of the post by chronology or topicality. It adds value by making the structure of the post clearer. When used properly, it is not simply noise.
* Secondly, it's a little misleading to say we "already know the post was edited". I, in fact, don't usually check to see if a post was edited when I'm reading it, and even if I do notice the "edited..." line, all that tells me is *that* it was edited, not how so. Knowing that it was edited it not the same as knowing how -- and I almost never look at the revision history. There's not usually a good reason to. Many edits don't even alter the post content in any substantial ways (just formatting/spelling/grammar fixes), and for those that do the edit is not usually relevant to the me, the reader.
Furthermore, I've seen "EDIT:" in many posts before seeing this, and I've even included it in some of my posts (a very small subset of my edits -- only those where it made sense to call it out explicitly), and this is the first time I've seen its usage admonished.
Is this a standard admonishment? Do you disagree with my reasoning above about why I think "EDIT:" isn't necessarily noise? | 2013/10/21 | [
"https://meta.stackexchange.com/questions/202472",
"https://meta.stackexchange.com",
"https://meta.stackexchange.com/users/155650/"
] | Personally, I'm inclined to disagree. Stack Overflow is not a forum, so it shouldn't be necessary to 'separate parts of the post by chronology or topicality' - each question should be as self-contained as possible, and should be constrained to a single topic at hand. **One question, one answer.**
*EDIT:* usually means one of a few things, in my experience.
1. OK, that solved my immediate problem, but I still have this other one.
2. OK, I tried that, but it didn't work.
3. OK, here's another code dump since you asked for it.
4. OMG I found the answer!
In the first case, this should be posted as a separate question.
In the second or third case, this can still be part of the same question, but adding "EDIT:" only signals something to those people who have already read the question. Usually, these people will be invested enough in the question to notice.
The fourth case should obviously be posted as an answer instead.
If you really want to be sure that people who have already interacted with the question will notice that a change has been made, **you can add a comment to your question, or to any relevant answers you've received so far**. These are the second-class citizens of Stack Overflow, where transitory information like this can be given.
In both cases, what does it add in the long run? Speaking broadly, people who come to this question a year later will not care that something was appended to the question between the time it was created and the time it was accessed. Those who do will still have the edit summaries (and possibly the comments), because that it what they are for.
In other words:
>
> I almost never look at the revision history. There's not usually a good reason to...the edit is not usually relevant to the me, the reader.
>
>
> | There's a fundamental tension at work in the posts on Stack Overflow. As with all truly great endeavors (and SO is a *great* endeavor), the tension exists between the vision, with its clean lines and stark distinctions, and reality, in its messiness, resistance to organization and many unaccounted-for artifacts.
**Comparison to Waterfall**
Consider project management. In the "early days", many subscribed to the idealistic waterfall method, where you put together your requirements, then perform some basic analysis, build your solution, test it and then deploy it. Isn't this approach similar to that proposed by some of the posts here? Put together a question containing your ultimate goal, include your analysis so far (including context), others put together answers, which the OP then tests and finally selects one as "accepted".
Of course, revision is acceptable, even in waterfall, but the format of revision involves going back and rewriting the question. New information, if introduced "correctly", ought to be smoothly incorporated into the question as if it had been there from the beginning, potentially "scattering" it in different places throughout the post.
**Asking Complex Questions is Complex**
But this belies the complex, messy reality of asking complex technical questions. Non-trivial issues usually require some degree of diagnosis and many halting attempts to discover both what the core issue is and what an appropriate solution would be. "Diagnosis" infers a **conversation**, but, *to its credit*, Stack Overflow is *not* a message board. There is no "thread", no real sense of replying to an answer, so users tend to shoehorn in a message board-like quality - they "UPDATE" their question in response to answerers and commenters. Sometimes this is to provide additional information, other times to provide a status update after an unsuccessful attempt to apply a suggestion.
As the conversation goes on, the answerers also "UPDATE" their posts, to provide additional suggestions (building off of, or alternatives to, previous suggestions) until, finally, a solution is found and the OP accepts an answer. Like it or not, this is sometimes the reality of working through technical questions and it is how some questions are eventually answered.
**Leave it Be, Initially, Then Reformat**
In the end, I don't think that this is necessarily harmful. Using "UPDATE" (or, in practice, the semantically equivalent "EDIT") can help draw attention to new information. Placing this information in a single paragraph helps followers keep track of the evolving situation without requiring them to re-read the entire question (or load a new, somewhat distracting page - who wants to waste time teaching other users how to access and understand the revision history?).
My suggestion, then, would be to leave the "UPDATE"s alone initially. Allow the conversation to flow naturally. If the topic is too broad, or the user is fundamentally changing the question ("Ok, that worked, but now..."), take appropriate action (rollback, downvote and/or close). **When an answer has been accepted, however, the post should be rewritten** to fit within our preferred format - that of a clean, concise, self-contained question. While providing "UPDATE"s is useful in the short-term to help followers of the question, it provides little if any value once the question has been answered, and should ultimately be reformatted.
>
> **See Some Examples**
>
>
> * [Why does Environment.Exit() not terminate the program any more?](https://stackoverflow.com/questions/18036863/why-does-environment-exit-not-terminate-the-program-anymore)
> * [How can I perform a culture-sensitive "starts-with" operation from the middle of a string?](https://stackoverflow.com/questions/15980310/how-can-i-perform-a-culture-sensitive-starts-with-operation-from-the-middle-of)
> * [How can I find out what's causing differences in generated Sandcastle docs?](https://stackoverflow.com/questions/14914222/how-can-i-find-out-whats-causing-differences-in-generated-sandcastle-docs)
>
>
> |
202,472 | I was just looking at this question: [How much freedom should a programmer have in choosing a language and framework?](https://softwareengineering.stackexchange.com/questions/214639/how-much-freedom-should-a-programmer-have-in-choosing-a-language-and-framework)
As I was reading the question, the very last line seemed sort of out-of-place and weirdly phrased for where it was, but I didn't think much of it. Then I was reading the comments and one read:
>
> Please do not put monikers like "EDIT" in your posts. We already know
> the post was edited; a complete edit history of your question can be
> found here:
> <https://softwareengineering.stackexchange.com/posts/214639/revisions>.
>
>
>
Apparently the last line of the question *had* originally been prefixed with "EDIT:", which was later removed. And in my opinion the line would have made more sense contextually as an explicit called-out edit.
But this example aside (it's honestly not the best example, just used it for the comment), I generally don't buy the argument that "EDIT:" should never be included in the post body. While I agree that sometimes "EDIT" can just be noise, this is not always the case.
* An explicitly called out "EDIT:" has an editorial meaning. It's a stand-in for "ADDENDUM:" or "UPDATE:", and can help logically separate parts of the post by chronology or topicality. It adds value by making the structure of the post clearer. When used properly, it is not simply noise.
* Secondly, it's a little misleading to say we "already know the post was edited". I, in fact, don't usually check to see if a post was edited when I'm reading it, and even if I do notice the "edited..." line, all that tells me is *that* it was edited, not how so. Knowing that it was edited it not the same as knowing how -- and I almost never look at the revision history. There's not usually a good reason to. Many edits don't even alter the post content in any substantial ways (just formatting/spelling/grammar fixes), and for those that do the edit is not usually relevant to the me, the reader.
Furthermore, I've seen "EDIT:" in many posts before seeing this, and I've even included it in some of my posts (a very small subset of my edits -- only those where it made sense to call it out explicitly), and this is the first time I've seen its usage admonished.
Is this a standard admonishment? Do you disagree with my reasoning above about why I think "EDIT:" isn't necessarily noise? | 2013/10/21 | [
"https://meta.stackexchange.com/questions/202472",
"https://meta.stackexchange.com",
"https://meta.stackexchange.com/users/155650/"
] | Imagine a post with three or four paragraphs, and a sentence in the middle of the second paragraph is muddy or unclear. The author now wants to edit it. They have at least 5 options:
* stick a sentence at the top that says EDIT: Actually this is a Windows machine.
* stick the same sentence at the bottom
The first is not good because you have no idea why you are being told this. The second is not good because the reader first reads the vague or misleading sentence and has to go back and fix it when they hit the edit.
* same sentence at the top without EDIT:
* same sentence at the bottom without EDIT:
These are even worse, and someone who edits just to remove the word EDIT: without solving the problem has made the post worse.
But there is a fifth option:
* edit the troublesome sentence so it makes sense. Do not label the edit as an edit, just make the sentence make sense. Optionally, add a comment that says "It's a Windows system, I've edited."
The person quoting the rules "don't say EDIT:" is misunderstanding the purpose of the guideline. When you see that happen, fix it if you can. | I don't think EDIT means the same as ADDENDUM or UPDATE. Those mean that something was added. EDIT means something was changed. I don't think it's really necessary to put EDIT in the body of your posts, since the revision history is linked at the bottom for anyone to look at.
If it needs to be pointed out in the body of the question that it was edited (for example, in response to a comment) then the reason should probably be spelled out instead of simply saying EDIT. I usually remove it and try to make the question flow more naturally. |
202,472 | I was just looking at this question: [How much freedom should a programmer have in choosing a language and framework?](https://softwareengineering.stackexchange.com/questions/214639/how-much-freedom-should-a-programmer-have-in-choosing-a-language-and-framework)
As I was reading the question, the very last line seemed sort of out-of-place and weirdly phrased for where it was, but I didn't think much of it. Then I was reading the comments and one read:
>
> Please do not put monikers like "EDIT" in your posts. We already know
> the post was edited; a complete edit history of your question can be
> found here:
> <https://softwareengineering.stackexchange.com/posts/214639/revisions>.
>
>
>
Apparently the last line of the question *had* originally been prefixed with "EDIT:", which was later removed. And in my opinion the line would have made more sense contextually as an explicit called-out edit.
But this example aside (it's honestly not the best example, just used it for the comment), I generally don't buy the argument that "EDIT:" should never be included in the post body. While I agree that sometimes "EDIT" can just be noise, this is not always the case.
* An explicitly called out "EDIT:" has an editorial meaning. It's a stand-in for "ADDENDUM:" or "UPDATE:", and can help logically separate parts of the post by chronology or topicality. It adds value by making the structure of the post clearer. When used properly, it is not simply noise.
* Secondly, it's a little misleading to say we "already know the post was edited". I, in fact, don't usually check to see if a post was edited when I'm reading it, and even if I do notice the "edited..." line, all that tells me is *that* it was edited, not how so. Knowing that it was edited it not the same as knowing how -- and I almost never look at the revision history. There's not usually a good reason to. Many edits don't even alter the post content in any substantial ways (just formatting/spelling/grammar fixes), and for those that do the edit is not usually relevant to the me, the reader.
Furthermore, I've seen "EDIT:" in many posts before seeing this, and I've even included it in some of my posts (a very small subset of my edits -- only those where it made sense to call it out explicitly), and this is the first time I've seen its usage admonished.
Is this a standard admonishment? Do you disagree with my reasoning above about why I think "EDIT:" isn't necessarily noise? | 2013/10/21 | [
"https://meta.stackexchange.com/questions/202472",
"https://meta.stackexchange.com",
"https://meta.stackexchange.com/users/155650/"
] | Imagine a post with three or four paragraphs, and a sentence in the middle of the second paragraph is muddy or unclear. The author now wants to edit it. They have at least 5 options:
* stick a sentence at the top that says EDIT: Actually this is a Windows machine.
* stick the same sentence at the bottom
The first is not good because you have no idea why you are being told this. The second is not good because the reader first reads the vague or misleading sentence and has to go back and fix it when they hit the edit.
* same sentence at the top without EDIT:
* same sentence at the bottom without EDIT:
These are even worse, and someone who edits just to remove the word EDIT: without solving the problem has made the post worse.
But there is a fifth option:
* edit the troublesome sentence so it makes sense. Do not label the edit as an edit, just make the sentence make sense. Optionally, add a comment that says "It's a Windows system, I've edited."
The person quoting the rules "don't say EDIT:" is misunderstanding the purpose of the guideline. When you see that happen, fix it if you can. | There's a fundamental tension at work in the posts on Stack Overflow. As with all truly great endeavors (and SO is a *great* endeavor), the tension exists between the vision, with its clean lines and stark distinctions, and reality, in its messiness, resistance to organization and many unaccounted-for artifacts.
**Comparison to Waterfall**
Consider project management. In the "early days", many subscribed to the idealistic waterfall method, where you put together your requirements, then perform some basic analysis, build your solution, test it and then deploy it. Isn't this approach similar to that proposed by some of the posts here? Put together a question containing your ultimate goal, include your analysis so far (including context), others put together answers, which the OP then tests and finally selects one as "accepted".
Of course, revision is acceptable, even in waterfall, but the format of revision involves going back and rewriting the question. New information, if introduced "correctly", ought to be smoothly incorporated into the question as if it had been there from the beginning, potentially "scattering" it in different places throughout the post.
**Asking Complex Questions is Complex**
But this belies the complex, messy reality of asking complex technical questions. Non-trivial issues usually require some degree of diagnosis and many halting attempts to discover both what the core issue is and what an appropriate solution would be. "Diagnosis" infers a **conversation**, but, *to its credit*, Stack Overflow is *not* a message board. There is no "thread", no real sense of replying to an answer, so users tend to shoehorn in a message board-like quality - they "UPDATE" their question in response to answerers and commenters. Sometimes this is to provide additional information, other times to provide a status update after an unsuccessful attempt to apply a suggestion.
As the conversation goes on, the answerers also "UPDATE" their posts, to provide additional suggestions (building off of, or alternatives to, previous suggestions) until, finally, a solution is found and the OP accepts an answer. Like it or not, this is sometimes the reality of working through technical questions and it is how some questions are eventually answered.
**Leave it Be, Initially, Then Reformat**
In the end, I don't think that this is necessarily harmful. Using "UPDATE" (or, in practice, the semantically equivalent "EDIT") can help draw attention to new information. Placing this information in a single paragraph helps followers keep track of the evolving situation without requiring them to re-read the entire question (or load a new, somewhat distracting page - who wants to waste time teaching other users how to access and understand the revision history?).
My suggestion, then, would be to leave the "UPDATE"s alone initially. Allow the conversation to flow naturally. If the topic is too broad, or the user is fundamentally changing the question ("Ok, that worked, but now..."), take appropriate action (rollback, downvote and/or close). **When an answer has been accepted, however, the post should be rewritten** to fit within our preferred format - that of a clean, concise, self-contained question. While providing "UPDATE"s is useful in the short-term to help followers of the question, it provides little if any value once the question has been answered, and should ultimately be reformatted.
>
> **See Some Examples**
>
>
> * [Why does Environment.Exit() not terminate the program any more?](https://stackoverflow.com/questions/18036863/why-does-environment-exit-not-terminate-the-program-anymore)
> * [How can I perform a culture-sensitive "starts-with" operation from the middle of a string?](https://stackoverflow.com/questions/15980310/how-can-i-perform-a-culture-sensitive-starts-with-operation-from-the-middle-of)
> * [How can I find out what's causing differences in generated Sandcastle docs?](https://stackoverflow.com/questions/14914222/how-can-i-find-out-whats-causing-differences-in-generated-sandcastle-docs)
>
>
> |
52,751 | A girl was found in a house belonging to one of two criminals; is it correct to express this in the following way:
*The girl was found in one of the criminals' houses*.
Does the plural use of 'house' suggest that the criminal in whose house she was found has more than one house? Or is it ambiguous meaning that he could have one or more houses?
Another example:
*The drugs were found in one of the men's cars.* ?
Does the meaning suggest, as in the other example above, that the man in whose car the drugs were found has more than 1 car? Or again, is it ambiguous suggesting that he may or may not have more than 1 car? | 2011/12/25 | [
"https://english.stackexchange.com/questions/52751",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/6346/"
] | Let us analyze this sentence:
>
> The girl was found in one of the criminals' houses.
>
>
>
There is a group of criminals. At least one of the criminals owns at least 1 house, while the total number of the houses owned in the group is more than 1. Therefore, this **group of criminals** owns **a certain number of houses**, in one of which the girl was found.
It's like saying:
>
> This product was created in one of the company's laboratories.
>
>
>
The same way there are many laboratories belonging to 1 entity, "the company", there are many houses belonging to 1 group of people, "the criminals."
Therefore, the sentence is perfectly correct and there isn't really any "more proper" way to express what it says.
Regarding the ambiguity, I wouldn't say it's ambiguous. It simply doesn't specify the number of houses per each person in the group it describes. Therefore it's impossible to determine what number of houses each person owns.
It may be like this:
Criminal 1 owns 3 houses.
Criminal 2 owns 1 house.
Criminal 3 owns 12 houses.
If in one of those houses a girl was found. It really isn't important which person owns how many, therefore the sentence isn't prepared to deal with it in the first place.
EDIT
Adding another example to back up my case:
>
> I'm interested in buying one of the red houses on Lincoln Street.
>
>
>
Explanation example: There are 30 houses on Lincoln Street. 12 of them have the property of "being red." I want one of those!
>
> I'm interested in buying one of the criminals' houses.
>
>
>
Explanation example: There are 1 000 000 houses in my town. 6 of them have the property of "belonging to a group of criminals responsible for robbing a bank." For some reason I want to buy one of those houses! | >
> The girl was found in one of the criminals' houses.
>
>
>
This is read as "The girl was found in one of (the criminals' houses)" — the criminals together have a bunch of houses (maybe each criminal has one house, or each has five houses, or there are three houses all shared by the criminals, or whatever), and the girl was found in one of them.
The natural interpretation (based on the world, not based on grammar) is that each criminal has one house, though other interpretations are possible. It does not *imply* that the criminal has more than one house.
If you want to make it clear that the particular criminal had only one house, you can write:
>
> The girl was found in the house of one of the criminals.
>
>
>
where "the house" indicates uniqueness. Or if you want to make it clear that the criminal had more than one house, you can use "a house", or:
>
> The girl was found in one of the houses of one of the criminals.
>
>
>
Similarly with
>
> The drugs were found in one of the men's cars.
>
>
>
It means "The drugs were found in one of (the men's cars)" — the men had more than one car in total, and the drug was found in one such car. |
52,751 | A girl was found in a house belonging to one of two criminals; is it correct to express this in the following way:
*The girl was found in one of the criminals' houses*.
Does the plural use of 'house' suggest that the criminal in whose house she was found has more than one house? Or is it ambiguous meaning that he could have one or more houses?
Another example:
*The drugs were found in one of the men's cars.* ?
Does the meaning suggest, as in the other example above, that the man in whose car the drugs were found has more than 1 car? Or again, is it ambiguous suggesting that he may or may not have more than 1 car? | 2011/12/25 | [
"https://english.stackexchange.com/questions/52751",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/6346/"
] | Let us analyze this sentence:
>
> The girl was found in one of the criminals' houses.
>
>
>
There is a group of criminals. At least one of the criminals owns at least 1 house, while the total number of the houses owned in the group is more than 1. Therefore, this **group of criminals** owns **a certain number of houses**, in one of which the girl was found.
It's like saying:
>
> This product was created in one of the company's laboratories.
>
>
>
The same way there are many laboratories belonging to 1 entity, "the company", there are many houses belonging to 1 group of people, "the criminals."
Therefore, the sentence is perfectly correct and there isn't really any "more proper" way to express what it says.
Regarding the ambiguity, I wouldn't say it's ambiguous. It simply doesn't specify the number of houses per each person in the group it describes. Therefore it's impossible to determine what number of houses each person owns.
It may be like this:
Criminal 1 owns 3 houses.
Criminal 2 owns 1 house.
Criminal 3 owns 12 houses.
If in one of those houses a girl was found. It really isn't important which person owns how many, therefore the sentence isn't prepared to deal with it in the first place.
EDIT
Adding another example to back up my case:
>
> I'm interested in buying one of the red houses on Lincoln Street.
>
>
>
Explanation example: There are 30 houses on Lincoln Street. 12 of them have the property of "being red." I want one of those!
>
> I'm interested in buying one of the criminals' houses.
>
>
>
Explanation example: There are 1 000 000 houses in my town. 6 of them have the property of "belonging to a group of criminals responsible for robbing a bank." For some reason I want to buy one of those houses! | The first **could** mean that there were several criminals, that they had several houses and that the girl was found in one of them. The second **could** mean that there were several men, that they had several cars and that the drugs were found in one of them.
Any writer wanting to make it quite clear that in the first there was one criminal with several houses would be well advised to write *The girl was found in one of the houses of one of the criminals* and any writer wanting to make it clear that in the second there was one man with several cars would be well advised to write *The drugs were found in one of the cars of one the men*. Fortunately, the need for either sentence is unlikely to arise very often. |
52,751 | A girl was found in a house belonging to one of two criminals; is it correct to express this in the following way:
*The girl was found in one of the criminals' houses*.
Does the plural use of 'house' suggest that the criminal in whose house she was found has more than one house? Or is it ambiguous meaning that he could have one or more houses?
Another example:
*The drugs were found in one of the men's cars.* ?
Does the meaning suggest, as in the other example above, that the man in whose car the drugs were found has more than 1 car? Or again, is it ambiguous suggesting that he may or may not have more than 1 car? | 2011/12/25 | [
"https://english.stackexchange.com/questions/52751",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/6346/"
] | Let us analyze this sentence:
>
> The girl was found in one of the criminals' houses.
>
>
>
There is a group of criminals. At least one of the criminals owns at least 1 house, while the total number of the houses owned in the group is more than 1. Therefore, this **group of criminals** owns **a certain number of houses**, in one of which the girl was found.
It's like saying:
>
> This product was created in one of the company's laboratories.
>
>
>
The same way there are many laboratories belonging to 1 entity, "the company", there are many houses belonging to 1 group of people, "the criminals."
Therefore, the sentence is perfectly correct and there isn't really any "more proper" way to express what it says.
Regarding the ambiguity, I wouldn't say it's ambiguous. It simply doesn't specify the number of houses per each person in the group it describes. Therefore it's impossible to determine what number of houses each person owns.
It may be like this:
Criminal 1 owns 3 houses.
Criminal 2 owns 1 house.
Criminal 3 owns 12 houses.
If in one of those houses a girl was found. It really isn't important which person owns how many, therefore the sentence isn't prepared to deal with it in the first place.
EDIT
Adding another example to back up my case:
>
> I'm interested in buying one of the red houses on Lincoln Street.
>
>
>
Explanation example: There are 30 houses on Lincoln Street. 12 of them have the property of "being red." I want one of those!
>
> I'm interested in buying one of the criminals' houses.
>
>
>
Explanation example: There are 1 000 000 houses in my town. 6 of them have the property of "belonging to a group of criminals responsible for robbing a bank." For some reason I want to buy one of those houses! | Yes, the sentence, "The girl was found in one of the criminals' houses" is ambiguous. It could mean:
(a) Each criminal owns one house, and the girl was found in the house owned by one of the criminals.
(b) The criminals collectivelly own several houses, that is, the criminals are part of some organization, and that organization owns several houses. The girl was found in one of these.
(c) One or more of the criminals owned several houses, and the girl was found in one of the houses owned by one of the criminals.
(d) It's even possible that it means: One of the criminals owns more than one house, and the girl was found in all of these houses. That doesn't make a lot of sense in this context -- how was she found in more than one house? But it would be quite plauble in a similarly-constructed sentence in a different context, like, "The drugs were found in one of the criminals' houses." That could mean drugs were found in each of his houses. (I suppose in the original sentence, the girl may have been murdered and pieces of her body found scattered among the houses.)
If the ambiguity is important, you can clarify by rewording the sentence. Like, "The girl was found in a house belonging to one of the criminals", versus, "The girl was found in one of the houses owned by the crime syndicate." |
52,751 | A girl was found in a house belonging to one of two criminals; is it correct to express this in the following way:
*The girl was found in one of the criminals' houses*.
Does the plural use of 'house' suggest that the criminal in whose house she was found has more than one house? Or is it ambiguous meaning that he could have one or more houses?
Another example:
*The drugs were found in one of the men's cars.* ?
Does the meaning suggest, as in the other example above, that the man in whose car the drugs were found has more than 1 car? Or again, is it ambiguous suggesting that he may or may not have more than 1 car? | 2011/12/25 | [
"https://english.stackexchange.com/questions/52751",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/6346/"
] | Let us analyze this sentence:
>
> The girl was found in one of the criminals' houses.
>
>
>
There is a group of criminals. At least one of the criminals owns at least 1 house, while the total number of the houses owned in the group is more than 1. Therefore, this **group of criminals** owns **a certain number of houses**, in one of which the girl was found.
It's like saying:
>
> This product was created in one of the company's laboratories.
>
>
>
The same way there are many laboratories belonging to 1 entity, "the company", there are many houses belonging to 1 group of people, "the criminals."
Therefore, the sentence is perfectly correct and there isn't really any "more proper" way to express what it says.
Regarding the ambiguity, I wouldn't say it's ambiguous. It simply doesn't specify the number of houses per each person in the group it describes. Therefore it's impossible to determine what number of houses each person owns.
It may be like this:
Criminal 1 owns 3 houses.
Criminal 2 owns 1 house.
Criminal 3 owns 12 houses.
If in one of those houses a girl was found. It really isn't important which person owns how many, therefore the sentence isn't prepared to deal with it in the first place.
EDIT
Adding another example to back up my case:
>
> I'm interested in buying one of the red houses on Lincoln Street.
>
>
>
Explanation example: There are 30 houses on Lincoln Street. 12 of them have the property of "being red." I want one of those!
>
> I'm interested in buying one of the criminals' houses.
>
>
>
Explanation example: There are 1 000 000 houses in my town. 6 of them have the property of "belonging to a group of criminals responsible for robbing a bank." For some reason I want to buy one of those houses! | >
> The girl was found in one of the criminals' houses. **Correct?**
>
>
>
Almost.
One of the criminals owns a house. That is all you know; and any other house is immaterial anyway...because the sentence implies as much. Therefore strike *s* in houses.
The house, whose ever it is, is not owned by two criminals. Therefore, make *one of the criminals'* (but not not both criminals) singular.
**So you have: the girl was found in one of the criminals's house.**
Your can pronounce it aloud, if you must, as if a singular possessive, just as you "heard" in the original example. Or you can pronounce it with the sss-is sound, if your colloquial dialect preference is so inclined.
You need not be distracted for sake of consistency by the (aural) sense of there being a possessive voice incongruity between criminal's and house. The match is actually between one (criminal) and the possessed house.
May I suggest that *punctuation* would have been the approriate tag. Ambiguity...well, no, because meanings were clear. |
52,751 | A girl was found in a house belonging to one of two criminals; is it correct to express this in the following way:
*The girl was found in one of the criminals' houses*.
Does the plural use of 'house' suggest that the criminal in whose house she was found has more than one house? Or is it ambiguous meaning that he could have one or more houses?
Another example:
*The drugs were found in one of the men's cars.* ?
Does the meaning suggest, as in the other example above, that the man in whose car the drugs were found has more than 1 car? Or again, is it ambiguous suggesting that he may or may not have more than 1 car? | 2011/12/25 | [
"https://english.stackexchange.com/questions/52751",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/6346/"
] | The first **could** mean that there were several criminals, that they had several houses and that the girl was found in one of them. The second **could** mean that there were several men, that they had several cars and that the drugs were found in one of them.
Any writer wanting to make it quite clear that in the first there was one criminal with several houses would be well advised to write *The girl was found in one of the houses of one of the criminals* and any writer wanting to make it clear that in the second there was one man with several cars would be well advised to write *The drugs were found in one of the cars of one the men*. Fortunately, the need for either sentence is unlikely to arise very often. | >
> The girl was found in one of the criminals' houses.
>
>
>
This is read as "The girl was found in one of (the criminals' houses)" — the criminals together have a bunch of houses (maybe each criminal has one house, or each has five houses, or there are three houses all shared by the criminals, or whatever), and the girl was found in one of them.
The natural interpretation (based on the world, not based on grammar) is that each criminal has one house, though other interpretations are possible. It does not *imply* that the criminal has more than one house.
If you want to make it clear that the particular criminal had only one house, you can write:
>
> The girl was found in the house of one of the criminals.
>
>
>
where "the house" indicates uniqueness. Or if you want to make it clear that the criminal had more than one house, you can use "a house", or:
>
> The girl was found in one of the houses of one of the criminals.
>
>
>
Similarly with
>
> The drugs were found in one of the men's cars.
>
>
>
It means "The drugs were found in one of (the men's cars)" — the men had more than one car in total, and the drug was found in one such car. |
52,751 | A girl was found in a house belonging to one of two criminals; is it correct to express this in the following way:
*The girl was found in one of the criminals' houses*.
Does the plural use of 'house' suggest that the criminal in whose house she was found has more than one house? Or is it ambiguous meaning that he could have one or more houses?
Another example:
*The drugs were found in one of the men's cars.* ?
Does the meaning suggest, as in the other example above, that the man in whose car the drugs were found has more than 1 car? Or again, is it ambiguous suggesting that he may or may not have more than 1 car? | 2011/12/25 | [
"https://english.stackexchange.com/questions/52751",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/6346/"
] | Yes, the sentence, "The girl was found in one of the criminals' houses" is ambiguous. It could mean:
(a) Each criminal owns one house, and the girl was found in the house owned by one of the criminals.
(b) The criminals collectivelly own several houses, that is, the criminals are part of some organization, and that organization owns several houses. The girl was found in one of these.
(c) One or more of the criminals owned several houses, and the girl was found in one of the houses owned by one of the criminals.
(d) It's even possible that it means: One of the criminals owns more than one house, and the girl was found in all of these houses. That doesn't make a lot of sense in this context -- how was she found in more than one house? But it would be quite plauble in a similarly-constructed sentence in a different context, like, "The drugs were found in one of the criminals' houses." That could mean drugs were found in each of his houses. (I suppose in the original sentence, the girl may have been murdered and pieces of her body found scattered among the houses.)
If the ambiguity is important, you can clarify by rewording the sentence. Like, "The girl was found in a house belonging to one of the criminals", versus, "The girl was found in one of the houses owned by the crime syndicate." | >
> The girl was found in one of the criminals' houses.
>
>
>
This is read as "The girl was found in one of (the criminals' houses)" — the criminals together have a bunch of houses (maybe each criminal has one house, or each has five houses, or there are three houses all shared by the criminals, or whatever), and the girl was found in one of them.
The natural interpretation (based on the world, not based on grammar) is that each criminal has one house, though other interpretations are possible. It does not *imply* that the criminal has more than one house.
If you want to make it clear that the particular criminal had only one house, you can write:
>
> The girl was found in the house of one of the criminals.
>
>
>
where "the house" indicates uniqueness. Or if you want to make it clear that the criminal had more than one house, you can use "a house", or:
>
> The girl was found in one of the houses of one of the criminals.
>
>
>
Similarly with
>
> The drugs were found in one of the men's cars.
>
>
>
It means "The drugs were found in one of (the men's cars)" — the men had more than one car in total, and the drug was found in one such car. |
52,751 | A girl was found in a house belonging to one of two criminals; is it correct to express this in the following way:
*The girl was found in one of the criminals' houses*.
Does the plural use of 'house' suggest that the criminal in whose house she was found has more than one house? Or is it ambiguous meaning that he could have one or more houses?
Another example:
*The drugs were found in one of the men's cars.* ?
Does the meaning suggest, as in the other example above, that the man in whose car the drugs were found has more than 1 car? Or again, is it ambiguous suggesting that he may or may not have more than 1 car? | 2011/12/25 | [
"https://english.stackexchange.com/questions/52751",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/6346/"
] | The first **could** mean that there were several criminals, that they had several houses and that the girl was found in one of them. The second **could** mean that there were several men, that they had several cars and that the drugs were found in one of them.
Any writer wanting to make it quite clear that in the first there was one criminal with several houses would be well advised to write *The girl was found in one of the houses of one of the criminals* and any writer wanting to make it clear that in the second there was one man with several cars would be well advised to write *The drugs were found in one of the cars of one the men*. Fortunately, the need for either sentence is unlikely to arise very often. | Yes, the sentence, "The girl was found in one of the criminals' houses" is ambiguous. It could mean:
(a) Each criminal owns one house, and the girl was found in the house owned by one of the criminals.
(b) The criminals collectivelly own several houses, that is, the criminals are part of some organization, and that organization owns several houses. The girl was found in one of these.
(c) One or more of the criminals owned several houses, and the girl was found in one of the houses owned by one of the criminals.
(d) It's even possible that it means: One of the criminals owns more than one house, and the girl was found in all of these houses. That doesn't make a lot of sense in this context -- how was she found in more than one house? But it would be quite plauble in a similarly-constructed sentence in a different context, like, "The drugs were found in one of the criminals' houses." That could mean drugs were found in each of his houses. (I suppose in the original sentence, the girl may have been murdered and pieces of her body found scattered among the houses.)
If the ambiguity is important, you can clarify by rewording the sentence. Like, "The girl was found in a house belonging to one of the criminals", versus, "The girl was found in one of the houses owned by the crime syndicate." |
52,751 | A girl was found in a house belonging to one of two criminals; is it correct to express this in the following way:
*The girl was found in one of the criminals' houses*.
Does the plural use of 'house' suggest that the criminal in whose house she was found has more than one house? Or is it ambiguous meaning that he could have one or more houses?
Another example:
*The drugs were found in one of the men's cars.* ?
Does the meaning suggest, as in the other example above, that the man in whose car the drugs were found has more than 1 car? Or again, is it ambiguous suggesting that he may or may not have more than 1 car? | 2011/12/25 | [
"https://english.stackexchange.com/questions/52751",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/6346/"
] | The first **could** mean that there were several criminals, that they had several houses and that the girl was found in one of them. The second **could** mean that there were several men, that they had several cars and that the drugs were found in one of them.
Any writer wanting to make it quite clear that in the first there was one criminal with several houses would be well advised to write *The girl was found in one of the houses of one of the criminals* and any writer wanting to make it clear that in the second there was one man with several cars would be well advised to write *The drugs were found in one of the cars of one the men*. Fortunately, the need for either sentence is unlikely to arise very often. | >
> The girl was found in one of the criminals' houses. **Correct?**
>
>
>
Almost.
One of the criminals owns a house. That is all you know; and any other house is immaterial anyway...because the sentence implies as much. Therefore strike *s* in houses.
The house, whose ever it is, is not owned by two criminals. Therefore, make *one of the criminals'* (but not not both criminals) singular.
**So you have: the girl was found in one of the criminals's house.**
Your can pronounce it aloud, if you must, as if a singular possessive, just as you "heard" in the original example. Or you can pronounce it with the sss-is sound, if your colloquial dialect preference is so inclined.
You need not be distracted for sake of consistency by the (aural) sense of there being a possessive voice incongruity between criminal's and house. The match is actually between one (criminal) and the possessed house.
May I suggest that *punctuation* would have been the approriate tag. Ambiguity...well, no, because meanings were clear. |
52,751 | A girl was found in a house belonging to one of two criminals; is it correct to express this in the following way:
*The girl was found in one of the criminals' houses*.
Does the plural use of 'house' suggest that the criminal in whose house she was found has more than one house? Or is it ambiguous meaning that he could have one or more houses?
Another example:
*The drugs were found in one of the men's cars.* ?
Does the meaning suggest, as in the other example above, that the man in whose car the drugs were found has more than 1 car? Or again, is it ambiguous suggesting that he may or may not have more than 1 car? | 2011/12/25 | [
"https://english.stackexchange.com/questions/52751",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/6346/"
] | Yes, the sentence, "The girl was found in one of the criminals' houses" is ambiguous. It could mean:
(a) Each criminal owns one house, and the girl was found in the house owned by one of the criminals.
(b) The criminals collectivelly own several houses, that is, the criminals are part of some organization, and that organization owns several houses. The girl was found in one of these.
(c) One or more of the criminals owned several houses, and the girl was found in one of the houses owned by one of the criminals.
(d) It's even possible that it means: One of the criminals owns more than one house, and the girl was found in all of these houses. That doesn't make a lot of sense in this context -- how was she found in more than one house? But it would be quite plauble in a similarly-constructed sentence in a different context, like, "The drugs were found in one of the criminals' houses." That could mean drugs were found in each of his houses. (I suppose in the original sentence, the girl may have been murdered and pieces of her body found scattered among the houses.)
If the ambiguity is important, you can clarify by rewording the sentence. Like, "The girl was found in a house belonging to one of the criminals", versus, "The girl was found in one of the houses owned by the crime syndicate." | >
> The girl was found in one of the criminals' houses. **Correct?**
>
>
>
Almost.
One of the criminals owns a house. That is all you know; and any other house is immaterial anyway...because the sentence implies as much. Therefore strike *s* in houses.
The house, whose ever it is, is not owned by two criminals. Therefore, make *one of the criminals'* (but not not both criminals) singular.
**So you have: the girl was found in one of the criminals's house.**
Your can pronounce it aloud, if you must, as if a singular possessive, just as you "heard" in the original example. Or you can pronounce it with the sss-is sound, if your colloquial dialect preference is so inclined.
You need not be distracted for sake of consistency by the (aural) sense of there being a possessive voice incongruity between criminal's and house. The match is actually between one (criminal) and the possessed house.
May I suggest that *punctuation* would have been the approriate tag. Ambiguity...well, no, because meanings were clear. |
298,304 | If the front fan on a gas turbine had a blade, or some of its blades extending into the surrounding housing, where there was a maglev ring of electromagnets, could fuel use be reduced by the engine? While still providing similar levels of thrust? Perhaps at the expense of electricity in the cabin. | 2016/12/12 | [
"https://physics.stackexchange.com/questions/298304",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/138964/"
] | There's a few layers to this question, each with its own answer. However, fortunately, the answers for each layer are the same: no. You cannot improve your fuel economy by adding a maglev system to an engine.
The first layer is easy -- conservation of energy. Any energy that you put into the compressor blades from the maglev system must come from somewhere. That "somewhere" is another engine, such as the APU. All you do in this case is rob Peter to pay Paul. However, it's even worse in this case. Jet engines are *tremendously* optimized beasts. A 1/10th of a percent improvement in fuel economy translates to somewhere around $500 in savings *per plane, per flight!* I hand waved the distances there... math is based on a 10 hour flight and 36,000 gallons of gas consumed. You should get the idea for just how much money there is in this business.
What does this mean? Well, it means that the engines are already optimized to do exactly what they need to do. Using an APU and bulky maglev system would consume far more energy than it cost to keep the compressors spinning the normal way. Yes, your main engine may be slightly more efficient, but you *more* than pay for those enhancements by running a less efficient engine.
Worse, you might not get any benefit at all! Maglev equipment doesn't exactly come without costs. It takes space to put that equipment into the engine space, and it brings mass. You may not be able to use the most ideal materials for compressor blades because they need to have good magnetic properties now... that can decrease efficiency. You may find that not only does the maglev equipment require a separate power source, but that it actually *decreases* the efficiency of the engine by applying new requirements to the design!
I hate to use an appeal to authority on Physics.SE, but truthfully, if there was a solution like this, the engineers who pour hundreds of thousands of hours into these devices would probably have found it. Airplane manufacturing is a multi-billion dollar industry feeding an even more massive air travel industry. There's a lot of eyes on efficiency of planes. Lots of sharp eyes. | No is the quick answer
>
> If the front fan on a gas turbine had a blade, or some of its blades extending into the surrounding housing, where there was a maglev ring of electromagnets,
>
>
>
This is an engineering question. The thrust from a [Rolls-Royce\_Trent](https://en.wikipedia.org/wiki/Rolls-Royce_Trent), for example, is 420 kN and a lot of that comes from the high by pass ratio. We know exactly how fan blades thrust air backwards and that fan housing is vital to performance.
It's a double whammy, you take power from the engine core to power the maglev, (**if** they can provide it), then you block off the very point of the high pass systems but without giving an explanation for how magnets would have sufficient power to drive enough air to rip off the top layer of a badly maintained runway, which a modern turbine engine is perfectly capable of doing, if the aircraft rotates too quickly on takeoff.
From [Power of High Bypass Engines](http://www.boeing.com/commercial/aeromagazine/aero_06/textonly/s02txt.html)
>
> The airplane was positioned for the run with asphalt extending from close to the wing trailing edges to beyond the empennage. During the high-power part of the run, asphalt lifted from behind the left engine and broke into pieces, sending large fragments into the aft fuselage and outboard horizontal stabilizer.
>
>
>
Or am I misunderstanding you, if I am, my sincere apologies. |
340,671 | I was using Shotwell on an old computer running 12.04 LTS. Not sure what the Shotwell version was [I've looked since, and it's 0.12.3], but it would have been up-to-date for that OS version. Got a new computer running 13.04 and Shotwell 0.14.1; copied Pictures folder to new computer; copied ~/.shotwell to ~/.local/share/shotwell. It kept all the tags and the images are there but the images don't match the tags (or vice versa) and the images are mostly all distorted like Shotwell is retaining the orientation and/or resolution for the wrong photo.
So, the question is: Is there a way to get the right tags matched back up with the right photos, etc., so that everything is back like it was? Or do I just have to delete the photo.db, let Shotwell re-index everything and start over retagging everything? (sigh)
Shotwell did give me an import log, which pointed out a number of duplicate directories that I'll be able to easily clean up. Nice. | 2013/09/03 | [
"https://askubuntu.com/questions/340671",
"https://askubuntu.com",
"https://askubuntu.com/users/189620/"
] | Jim Nelson responded to [my post on yorba](http://redmine.yorba.org/issues/7498) which resolved this. My guess is that my not deleting the cache after the first attempt is why I couldn't get any further. | >
> copied ~/.shotwell to ~/.local/share/shotwell.
>
>
>
I would have thought that you should copy ~/.shotwell to ~/.shotwell. If shotwell has an upgrade mechanism, finding its data in the "old" directory and not the new might trigger its upgrade mechanism and do any necessary conversion.
It's worth a try, at least. I must admit to not knowing much about shotwell. |
153,493 | When a voltage is applied to a diode (forward or reversed bias) the depletion zone is changed due to charges change in this region. My question is in both case (forward or reversed bias), how the electric field that is responsible of moving the charges in the P and N region is established ? Is it the same mechanism of electric field establishment inside a conductor i.e surface charges density making the electric field? | 2014/12/15 | [
"https://physics.stackexchange.com/questions/153493",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/67786/"
] | You are talking about a p-n junction which forms a diode. Now a diode junction is very small compared to the rest of semiconductor. The diode junction can in a first approximation be taken as an insulator since it does not have any mobile charges compared to the rest of the region. When a voltage is applied at the ends the region outside the junction can be viewed as a conductor and hence in a fist approximation has no potential drop or electric field. Therefore all the applied voltage shifts to the p-n junction and an electric field is added or subtracted from original electric field arising from the built-in voltage. In case of forward voltage the electric field due to the applied voltages oppose that due to the built in voltage and opposite is for reverse voltage. Remember the built-in voltage is always from n side to p side. | The electric field inside the diode will be opposite to that of the electric field of the source. Thus will cause a barrier potential of 0.3 or 0.7 volts opposite to the source when its forward biased. That is why the the diode start conducting when forward biased when source is at more than 0.3 or 0.7 volts. Less than 0.3 or 0.7 volts it will conduct very low current or no current. When reversed biased diode will again built polarity opposite to the source which would be equal to the potential difference of the battery. Thus there is no conduction in reverse biased diode. |
153,493 | When a voltage is applied to a diode (forward or reversed bias) the depletion zone is changed due to charges change in this region. My question is in both case (forward or reversed bias), how the electric field that is responsible of moving the charges in the P and N region is established ? Is it the same mechanism of electric field establishment inside a conductor i.e surface charges density making the electric field? | 2014/12/15 | [
"https://physics.stackexchange.com/questions/153493",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/67786/"
] | You are talking about a p-n junction which forms a diode. Now a diode junction is very small compared to the rest of semiconductor. The diode junction can in a first approximation be taken as an insulator since it does not have any mobile charges compared to the rest of the region. When a voltage is applied at the ends the region outside the junction can be viewed as a conductor and hence in a fist approximation has no potential drop or electric field. Therefore all the applied voltage shifts to the p-n junction and an electric field is added or subtracted from original electric field arising from the built-in voltage. In case of forward voltage the electric field due to the applied voltages oppose that due to the built in voltage and opposite is for reverse voltage. Remember the built-in voltage is always from n side to p side. | In a diode, two processes are at play, first one is the "diffusion" and the second one is the "drift" , now even at room temperature electrons on the n-side try to go the p-side so as to stabilize themselves or to reduce their potential energy to a minimum, but when they do that they get stuck in the holes on the p-side, now those electrons were first in the conduction band that's why they were able to go haywire but now when they enter that hole ( a hole is essentially a vacancy in the valence band ) , they release their extra potential energy, and gets stabilized by entering in the valence band, now they are stuck and can't move due to the normal thermal energy that we get at the room temperature, due to this a "depletion region" is formed, we call it depletion because electrons are not able to go crazy in that region, same happens on the n- side, as electrons initially move from n-side to p-side, this exposes the +ve charge of the dopant atom and we call it a "hole" ( I don't like holes though ). Now this depletion layer has a voltage associated to it that tries to prevent more diffusion and tries to revert it back, so for example diffusion tries to kick electrons from n-side to p-side whereas drift tends to take them back to their initial configurations, when these two processes are balanced, we get stable equilibrium.
Now to distort that equilibrium, we can do two things.
1. Forward Bias : We know that "diffusion" and "drift" are fighting with each other, but under normal conditions no one wins, but what if we make one of them win! Aha! Thats what we do when we bias a diode. In forward bias we attach +ve pole of battery on the p side and -ve pole of battery on the n-side, as we do that -ve side of battery pushes electrons in the n-side and slides them towards the p-side, due to this that depletion layer starts vanishing, and now is the fun part when it vanishes electrons are no longer prevented to diffuse over to the p-side and diffusion current increases heavily.electrons were trying to go all the way to p side ever since we made a pn junction but they were not able to do so due to that depletion layer, what we did in forward bias is reduced that depletion layer and then diffusion did its work.
2. Reverse Bias : exactly opposite happens, in this case depletion layer increases and diffusion almost stops but drift continues its work in the opposite direction, that's why we get a small current in the opposite direction. |
153,493 | When a voltage is applied to a diode (forward or reversed bias) the depletion zone is changed due to charges change in this region. My question is in both case (forward or reversed bias), how the electric field that is responsible of moving the charges in the P and N region is established ? Is it the same mechanism of electric field establishment inside a conductor i.e surface charges density making the electric field? | 2014/12/15 | [
"https://physics.stackexchange.com/questions/153493",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/67786/"
] | I don't think any of the current answers address your question as I understand it.
My understanding is that your question is effectively: What spatial distribution of charge gives rise to the electric field in a diode?
In the case of a uniform dielectric, the internal field is created by surface charges on the two surfaces, such are usually very small in width. In a pn junction this is not the case.
<https://ecee.colorado.edu/~bart/book/book/chapter4/gif/fig4_3_1.gif>[](https://i.stack.imgur.com/IOj2G.gif)
Figure a of the above image shows the charge density profile of a pn junction. Notice that you have both nonzero charge density in a sizeable area, the depletion region. In the case of two dielectrics, instead of a pn junction, you would get charge accumulating only along the surface of the interface. This non uniform charge density also means that the electric field is not simply a constant in the material, but rather varies along the depletion region, something that ia very different than for a simple resistor.
This charge density comes the bare donors/acceptors that cannot move, and are neutralized at the ends of the depletion region by the electrons and holes which accumulate in very small regions due to being free to move. | You are talking about a p-n junction which forms a diode. Now a diode junction is very small compared to the rest of semiconductor. The diode junction can in a first approximation be taken as an insulator since it does not have any mobile charges compared to the rest of the region. When a voltage is applied at the ends the region outside the junction can be viewed as a conductor and hence in a fist approximation has no potential drop or electric field. Therefore all the applied voltage shifts to the p-n junction and an electric field is added or subtracted from original electric field arising from the built-in voltage. In case of forward voltage the electric field due to the applied voltages oppose that due to the built in voltage and opposite is for reverse voltage. Remember the built-in voltage is always from n side to p side. |
153,493 | When a voltage is applied to a diode (forward or reversed bias) the depletion zone is changed due to charges change in this region. My question is in both case (forward or reversed bias), how the electric field that is responsible of moving the charges in the P and N region is established ? Is it the same mechanism of electric field establishment inside a conductor i.e surface charges density making the electric field? | 2014/12/15 | [
"https://physics.stackexchange.com/questions/153493",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/67786/"
] | The electric field inside the diode will be opposite to that of the electric field of the source. Thus will cause a barrier potential of 0.3 or 0.7 volts opposite to the source when its forward biased. That is why the the diode start conducting when forward biased when source is at more than 0.3 or 0.7 volts. Less than 0.3 or 0.7 volts it will conduct very low current or no current. When reversed biased diode will again built polarity opposite to the source which would be equal to the potential difference of the battery. Thus there is no conduction in reverse biased diode. | In a diode, two processes are at play, first one is the "diffusion" and the second one is the "drift" , now even at room temperature electrons on the n-side try to go the p-side so as to stabilize themselves or to reduce their potential energy to a minimum, but when they do that they get stuck in the holes on the p-side, now those electrons were first in the conduction band that's why they were able to go haywire but now when they enter that hole ( a hole is essentially a vacancy in the valence band ) , they release their extra potential energy, and gets stabilized by entering in the valence band, now they are stuck and can't move due to the normal thermal energy that we get at the room temperature, due to this a "depletion region" is formed, we call it depletion because electrons are not able to go crazy in that region, same happens on the n- side, as electrons initially move from n-side to p-side, this exposes the +ve charge of the dopant atom and we call it a "hole" ( I don't like holes though ). Now this depletion layer has a voltage associated to it that tries to prevent more diffusion and tries to revert it back, so for example diffusion tries to kick electrons from n-side to p-side whereas drift tends to take them back to their initial configurations, when these two processes are balanced, we get stable equilibrium.
Now to distort that equilibrium, we can do two things.
1. Forward Bias : We know that "diffusion" and "drift" are fighting with each other, but under normal conditions no one wins, but what if we make one of them win! Aha! Thats what we do when we bias a diode. In forward bias we attach +ve pole of battery on the p side and -ve pole of battery on the n-side, as we do that -ve side of battery pushes electrons in the n-side and slides them towards the p-side, due to this that depletion layer starts vanishing, and now is the fun part when it vanishes electrons are no longer prevented to diffuse over to the p-side and diffusion current increases heavily.electrons were trying to go all the way to p side ever since we made a pn junction but they were not able to do so due to that depletion layer, what we did in forward bias is reduced that depletion layer and then diffusion did its work.
2. Reverse Bias : exactly opposite happens, in this case depletion layer increases and diffusion almost stops but drift continues its work in the opposite direction, that's why we get a small current in the opposite direction. |
153,493 | When a voltage is applied to a diode (forward or reversed bias) the depletion zone is changed due to charges change in this region. My question is in both case (forward or reversed bias), how the electric field that is responsible of moving the charges in the P and N region is established ? Is it the same mechanism of electric field establishment inside a conductor i.e surface charges density making the electric field? | 2014/12/15 | [
"https://physics.stackexchange.com/questions/153493",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/67786/"
] | I don't think any of the current answers address your question as I understand it.
My understanding is that your question is effectively: What spatial distribution of charge gives rise to the electric field in a diode?
In the case of a uniform dielectric, the internal field is created by surface charges on the two surfaces, such are usually very small in width. In a pn junction this is not the case.
<https://ecee.colorado.edu/~bart/book/book/chapter4/gif/fig4_3_1.gif>[](https://i.stack.imgur.com/IOj2G.gif)
Figure a of the above image shows the charge density profile of a pn junction. Notice that you have both nonzero charge density in a sizeable area, the depletion region. In the case of two dielectrics, instead of a pn junction, you would get charge accumulating only along the surface of the interface. This non uniform charge density also means that the electric field is not simply a constant in the material, but rather varies along the depletion region, something that ia very different than for a simple resistor.
This charge density comes the bare donors/acceptors that cannot move, and are neutralized at the ends of the depletion region by the electrons and holes which accumulate in very small regions due to being free to move. | The electric field inside the diode will be opposite to that of the electric field of the source. Thus will cause a barrier potential of 0.3 or 0.7 volts opposite to the source when its forward biased. That is why the the diode start conducting when forward biased when source is at more than 0.3 or 0.7 volts. Less than 0.3 or 0.7 volts it will conduct very low current or no current. When reversed biased diode will again built polarity opposite to the source which would be equal to the potential difference of the battery. Thus there is no conduction in reverse biased diode. |
153,493 | When a voltage is applied to a diode (forward or reversed bias) the depletion zone is changed due to charges change in this region. My question is in both case (forward or reversed bias), how the electric field that is responsible of moving the charges in the P and N region is established ? Is it the same mechanism of electric field establishment inside a conductor i.e surface charges density making the electric field? | 2014/12/15 | [
"https://physics.stackexchange.com/questions/153493",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/67786/"
] | I don't think any of the current answers address your question as I understand it.
My understanding is that your question is effectively: What spatial distribution of charge gives rise to the electric field in a diode?
In the case of a uniform dielectric, the internal field is created by surface charges on the two surfaces, such are usually very small in width. In a pn junction this is not the case.
<https://ecee.colorado.edu/~bart/book/book/chapter4/gif/fig4_3_1.gif>[](https://i.stack.imgur.com/IOj2G.gif)
Figure a of the above image shows the charge density profile of a pn junction. Notice that you have both nonzero charge density in a sizeable area, the depletion region. In the case of two dielectrics, instead of a pn junction, you would get charge accumulating only along the surface of the interface. This non uniform charge density also means that the electric field is not simply a constant in the material, but rather varies along the depletion region, something that ia very different than for a simple resistor.
This charge density comes the bare donors/acceptors that cannot move, and are neutralized at the ends of the depletion region by the electrons and holes which accumulate in very small regions due to being free to move. | In a diode, two processes are at play, first one is the "diffusion" and the second one is the "drift" , now even at room temperature electrons on the n-side try to go the p-side so as to stabilize themselves or to reduce their potential energy to a minimum, but when they do that they get stuck in the holes on the p-side, now those electrons were first in the conduction band that's why they were able to go haywire but now when they enter that hole ( a hole is essentially a vacancy in the valence band ) , they release their extra potential energy, and gets stabilized by entering in the valence band, now they are stuck and can't move due to the normal thermal energy that we get at the room temperature, due to this a "depletion region" is formed, we call it depletion because electrons are not able to go crazy in that region, same happens on the n- side, as electrons initially move from n-side to p-side, this exposes the +ve charge of the dopant atom and we call it a "hole" ( I don't like holes though ). Now this depletion layer has a voltage associated to it that tries to prevent more diffusion and tries to revert it back, so for example diffusion tries to kick electrons from n-side to p-side whereas drift tends to take them back to their initial configurations, when these two processes are balanced, we get stable equilibrium.
Now to distort that equilibrium, we can do two things.
1. Forward Bias : We know that "diffusion" and "drift" are fighting with each other, but under normal conditions no one wins, but what if we make one of them win! Aha! Thats what we do when we bias a diode. In forward bias we attach +ve pole of battery on the p side and -ve pole of battery on the n-side, as we do that -ve side of battery pushes electrons in the n-side and slides them towards the p-side, due to this that depletion layer starts vanishing, and now is the fun part when it vanishes electrons are no longer prevented to diffuse over to the p-side and diffusion current increases heavily.electrons were trying to go all the way to p side ever since we made a pn junction but they were not able to do so due to that depletion layer, what we did in forward bias is reduced that depletion layer and then diffusion did its work.
2. Reverse Bias : exactly opposite happens, in this case depletion layer increases and diffusion almost stops but drift continues its work in the opposite direction, that's why we get a small current in the opposite direction. |
224,475 | I cannot unlock apps to close them in the recent apps screen on my new phone. Pressing the lock icon only open the app.
[](https://i.stack.imgur.com/OBb85.png) | 2020/04/29 | [
"https://android.stackexchange.com/questions/224475",
"https://android.stackexchange.com",
"https://android.stackexchange.com/users/321835/"
] | I solved it by swiping down the lock icon on my android 10 device. Hope this helps | Not sure if you're still having this issue, but recently suffered the same (different app) and managed to resolve it completely by accident:
Go to the recent apps menu (as shown in image) and simple do a (quick) swipe to the right on the app you want to lock/unlock, starting point doesn't seem to matter much but make sure to swipe all the way to (or over) the edge. If you do it too slow or not far enough it doesn't work.
I haven't been able to find this in any official documentation or if/where it can be configured/disabled, it's not listed in the System->Gestures menu. It also seems to be fairly tenacious since 'locking' an app persists after a reboot or force stop via developer menu's 'running services'.
It seems to be something similar to Windows' 'Pin to Taskbar' or Apple's 'Keep in Dock'.
Phone: Alcatel 1S (2019) running Android 9 (build 01001) |
31,012 | I'm imagining if you had a panicky passenger sitting in the right seat who had both feet firmly on the brakes while landing. Unless you had a crosswind and needed rudder as you touched down it's possible you wouldn't be aware of it. Or if there was a malfunction causing them to be locked. How likely is it that could cause you to have a bad day?
What if only one side was locked up (which seems worse to me)?
I'm mainly asking about small aircraft. Would it be any different for an airliner?
What if you were aware of it? What action would you take? | 2016/08/26 | [
"https://aviation.stackexchange.com/questions/31012",
"https://aviation.stackexchange.com",
"https://aviation.stackexchange.com/users/8730/"
] | It's mostly harmless in a nose wheel configuration. You quickly blow all tires and slide along the runway on your wheel hubs until the aircraft comes to a rest. Crosswind will make the experience worse, because at lower speed you have less rudder authority and the aircraft might leave the runway.
If only one side is locked you will risk a ground loop. Here it is best to step on the other brake so both cause the same braking force.
But this is peanuts when compared to a tailwheel configuration. Here the consequence is a headstand right after you put some load on the wheels, which can be right at touchdown when you come down with some sink speed. Depending on the speed of the aircraft when this happens and the length of the fuselage nose, the aircraft might even flip on its back. Now this is sure to ruin your day. I've witnessed this once with a Polish [Yak-12](https://en.wikipedia.org/wiki/Yakovlev_Yak-12) which landed on soft ground - nothing more. The pilot climbed out unhurt from his inverted position, but damage to the aircraft was extensive. This was the occasion when I learned the worst Polish cursing ever.
If only one side is locked in case of a taildragger, I am unsure what will happen first: Ground loop or headstand. Details depend on the wheel track and the attitude at touchdown. Be sure to touchdown at the lowest possible speed and with the highest nose-up incidence possible to increase the resistance of the aircraft against flippig over. Unload the locked wheel with ailerons, so you touch down on the working wheel only, but make sure that you do this with as little sideslip angle as possible. Flying a gentle turn while touching down will help - just place the touchdown point at the moment when the aircraft is aligned with the runway (I know - easier said than done).
Touching down on one main wheel of a taildragger with some lateral speed by sideslipping into the direction of the working wheel will quickly roll the aircraft into the direction of the lateral speed, which helps to unload the locked wheel but might end up in a three-point landing: One wheel, wingtip and fuselage nose. Again, this is sure to ruin your day.
That is what is colloquially called a "headstand" (Picture [source](http://replicainscale.blogspot.de/2011/08/walkin-dog-chief-goes-to-france-hawks.html)) | I've seen it happen many times (ask any rental place about this). You get a big bald spot cut into the tread. Sometimes it goes all the way through the tire.
If it happened on one side, you'd likely get a ground loop.
[](https://i.stack.imgur.com/mAvqB.jpg)
[](https://i.stack.imgur.com/a8BSZ.jpg) |
31,012 | I'm imagining if you had a panicky passenger sitting in the right seat who had both feet firmly on the brakes while landing. Unless you had a crosswind and needed rudder as you touched down it's possible you wouldn't be aware of it. Or if there was a malfunction causing them to be locked. How likely is it that could cause you to have a bad day?
What if only one side was locked up (which seems worse to me)?
I'm mainly asking about small aircraft. Would it be any different for an airliner?
What if you were aware of it? What action would you take? | 2016/08/26 | [
"https://aviation.stackexchange.com/questions/31012",
"https://aviation.stackexchange.com",
"https://aviation.stackexchange.com/users/8730/"
] | I've seen it happen many times (ask any rental place about this). You get a big bald spot cut into the tread. Sometimes it goes all the way through the tire.
If it happened on one side, you'd likely get a ground loop.
[](https://i.stack.imgur.com/mAvqB.jpg)
[](https://i.stack.imgur.com/a8BSZ.jpg) | If that happens to an airliner(full brakes at touchdown), a lot can happen.
1- depending on the landing speed, the wheel struts could break off
2- if the struts resist such enormous load and bending force, the n the wheels will wear and burst due to friction and then most certainly burn depending on the condition of the runway(wet or dry). |
31,012 | I'm imagining if you had a panicky passenger sitting in the right seat who had both feet firmly on the brakes while landing. Unless you had a crosswind and needed rudder as you touched down it's possible you wouldn't be aware of it. Or if there was a malfunction causing them to be locked. How likely is it that could cause you to have a bad day?
What if only one side was locked up (which seems worse to me)?
I'm mainly asking about small aircraft. Would it be any different for an airliner?
What if you were aware of it? What action would you take? | 2016/08/26 | [
"https://aviation.stackexchange.com/questions/31012",
"https://aviation.stackexchange.com",
"https://aviation.stackexchange.com/users/8730/"
] | I've seen it happen many times (ask any rental place about this). You get a big bald spot cut into the tread. Sometimes it goes all the way through the tire.
If it happened on one side, you'd likely get a ground loop.
[](https://i.stack.imgur.com/mAvqB.jpg)
[](https://i.stack.imgur.com/a8BSZ.jpg) | When [Air Transat Flight 326](https://en.wikipedia.org/wiki/Air_Transat_Flight_236) glided into the Azores after fuel exhaustion over the Atlantic, the pilots were unsure whether they would be able to apply the brakes on their Airbus 330 more than once, and their anti-skid systems were inoperative. So they applied the brakes and held them, locking the wheels. The results, from the [accident report:](http://www.fss.aero/accident-reports/dvdfiles/PT/2001-08-24-PT.pdf)
>
> The tires quickly abraded and deflated at a point between about 300 and 450 feet beyond the second and final touch down. The segments of the main wheels contacting the pavement were worn down to the bearing journals, the left, rear, inboard wheel detached from the axle. Both left and right brake anti-torque links attachment horns on the bottom segments of the main oleos also contacted the pavement; the horns were abraded to the point that some of the links separated from the oleo resulting in the rotation of at least one brake carrier. Shedding of brake and wheel components during the landing run also resulted in a combination of punctures and impact damage to the airframe and left engine nacelle.
>
>
> ...
>
>
> CFR [Crash Fire Rescue] reported that there was fire visible coming from the
> main wheels, and responded to put out the fire. At 06:46, CFR reported that the evacuation was in progress and that some signs of fire still existed in the left main wheels. By 06:54, all fires were extinguished; the areas around the main wheels continued to be monitored due to the fire hazard associated with the damaged wheels and hot brakes.
>
>
>
[](https://i.stack.imgur.com/5Ab5D.png)
However, the airline stayed on the runway, and everyone survived. (Two passengers were hospitalized due to their injuries.) |
31,012 | I'm imagining if you had a panicky passenger sitting in the right seat who had both feet firmly on the brakes while landing. Unless you had a crosswind and needed rudder as you touched down it's possible you wouldn't be aware of it. Or if there was a malfunction causing them to be locked. How likely is it that could cause you to have a bad day?
What if only one side was locked up (which seems worse to me)?
I'm mainly asking about small aircraft. Would it be any different for an airliner?
What if you were aware of it? What action would you take? | 2016/08/26 | [
"https://aviation.stackexchange.com/questions/31012",
"https://aviation.stackexchange.com",
"https://aviation.stackexchange.com/users/8730/"
] | It's mostly harmless in a nose wheel configuration. You quickly blow all tires and slide along the runway on your wheel hubs until the aircraft comes to a rest. Crosswind will make the experience worse, because at lower speed you have less rudder authority and the aircraft might leave the runway.
If only one side is locked you will risk a ground loop. Here it is best to step on the other brake so both cause the same braking force.
But this is peanuts when compared to a tailwheel configuration. Here the consequence is a headstand right after you put some load on the wheels, which can be right at touchdown when you come down with some sink speed. Depending on the speed of the aircraft when this happens and the length of the fuselage nose, the aircraft might even flip on its back. Now this is sure to ruin your day. I've witnessed this once with a Polish [Yak-12](https://en.wikipedia.org/wiki/Yakovlev_Yak-12) which landed on soft ground - nothing more. The pilot climbed out unhurt from his inverted position, but damage to the aircraft was extensive. This was the occasion when I learned the worst Polish cursing ever.
If only one side is locked in case of a taildragger, I am unsure what will happen first: Ground loop or headstand. Details depend on the wheel track and the attitude at touchdown. Be sure to touchdown at the lowest possible speed and with the highest nose-up incidence possible to increase the resistance of the aircraft against flippig over. Unload the locked wheel with ailerons, so you touch down on the working wheel only, but make sure that you do this with as little sideslip angle as possible. Flying a gentle turn while touching down will help - just place the touchdown point at the moment when the aircraft is aligned with the runway (I know - easier said than done).
Touching down on one main wheel of a taildragger with some lateral speed by sideslipping into the direction of the working wheel will quickly roll the aircraft into the direction of the lateral speed, which helps to unload the locked wheel but might end up in a three-point landing: One wheel, wingtip and fuselage nose. Again, this is sure to ruin your day.
That is what is colloquially called a "headstand" (Picture [source](http://replicainscale.blogspot.de/2011/08/walkin-dog-chief-goes-to-france-hawks.html)) | If that happens to an airliner(full brakes at touchdown), a lot can happen.
1- depending on the landing speed, the wheel struts could break off
2- if the struts resist such enormous load and bending force, the n the wheels will wear and burst due to friction and then most certainly burn depending on the condition of the runway(wet or dry). |
31,012 | I'm imagining if you had a panicky passenger sitting in the right seat who had both feet firmly on the brakes while landing. Unless you had a crosswind and needed rudder as you touched down it's possible you wouldn't be aware of it. Or if there was a malfunction causing them to be locked. How likely is it that could cause you to have a bad day?
What if only one side was locked up (which seems worse to me)?
I'm mainly asking about small aircraft. Would it be any different for an airliner?
What if you were aware of it? What action would you take? | 2016/08/26 | [
"https://aviation.stackexchange.com/questions/31012",
"https://aviation.stackexchange.com",
"https://aviation.stackexchange.com/users/8730/"
] | It's mostly harmless in a nose wheel configuration. You quickly blow all tires and slide along the runway on your wheel hubs until the aircraft comes to a rest. Crosswind will make the experience worse, because at lower speed you have less rudder authority and the aircraft might leave the runway.
If only one side is locked you will risk a ground loop. Here it is best to step on the other brake so both cause the same braking force.
But this is peanuts when compared to a tailwheel configuration. Here the consequence is a headstand right after you put some load on the wheels, which can be right at touchdown when you come down with some sink speed. Depending on the speed of the aircraft when this happens and the length of the fuselage nose, the aircraft might even flip on its back. Now this is sure to ruin your day. I've witnessed this once with a Polish [Yak-12](https://en.wikipedia.org/wiki/Yakovlev_Yak-12) which landed on soft ground - nothing more. The pilot climbed out unhurt from his inverted position, but damage to the aircraft was extensive. This was the occasion when I learned the worst Polish cursing ever.
If only one side is locked in case of a taildragger, I am unsure what will happen first: Ground loop or headstand. Details depend on the wheel track and the attitude at touchdown. Be sure to touchdown at the lowest possible speed and with the highest nose-up incidence possible to increase the resistance of the aircraft against flippig over. Unload the locked wheel with ailerons, so you touch down on the working wheel only, but make sure that you do this with as little sideslip angle as possible. Flying a gentle turn while touching down will help - just place the touchdown point at the moment when the aircraft is aligned with the runway (I know - easier said than done).
Touching down on one main wheel of a taildragger with some lateral speed by sideslipping into the direction of the working wheel will quickly roll the aircraft into the direction of the lateral speed, which helps to unload the locked wheel but might end up in a three-point landing: One wheel, wingtip and fuselage nose. Again, this is sure to ruin your day.
That is what is colloquially called a "headstand" (Picture [source](http://replicainscale.blogspot.de/2011/08/walkin-dog-chief-goes-to-france-hawks.html)) | When [Air Transat Flight 326](https://en.wikipedia.org/wiki/Air_Transat_Flight_236) glided into the Azores after fuel exhaustion over the Atlantic, the pilots were unsure whether they would be able to apply the brakes on their Airbus 330 more than once, and their anti-skid systems were inoperative. So they applied the brakes and held them, locking the wheels. The results, from the [accident report:](http://www.fss.aero/accident-reports/dvdfiles/PT/2001-08-24-PT.pdf)
>
> The tires quickly abraded and deflated at a point between about 300 and 450 feet beyond the second and final touch down. The segments of the main wheels contacting the pavement were worn down to the bearing journals, the left, rear, inboard wheel detached from the axle. Both left and right brake anti-torque links attachment horns on the bottom segments of the main oleos also contacted the pavement; the horns were abraded to the point that some of the links separated from the oleo resulting in the rotation of at least one brake carrier. Shedding of brake and wheel components during the landing run also resulted in a combination of punctures and impact damage to the airframe and left engine nacelle.
>
>
> ...
>
>
> CFR [Crash Fire Rescue] reported that there was fire visible coming from the
> main wheels, and responded to put out the fire. At 06:46, CFR reported that the evacuation was in progress and that some signs of fire still existed in the left main wheels. By 06:54, all fires were extinguished; the areas around the main wheels continued to be monitored due to the fire hazard associated with the damaged wheels and hot brakes.
>
>
>
[](https://i.stack.imgur.com/5Ab5D.png)
However, the airline stayed on the runway, and everyone survived. (Two passengers were hospitalized due to their injuries.) |
31,012 | I'm imagining if you had a panicky passenger sitting in the right seat who had both feet firmly on the brakes while landing. Unless you had a crosswind and needed rudder as you touched down it's possible you wouldn't be aware of it. Or if there was a malfunction causing them to be locked. How likely is it that could cause you to have a bad day?
What if only one side was locked up (which seems worse to me)?
I'm mainly asking about small aircraft. Would it be any different for an airliner?
What if you were aware of it? What action would you take? | 2016/08/26 | [
"https://aviation.stackexchange.com/questions/31012",
"https://aviation.stackexchange.com",
"https://aviation.stackexchange.com/users/8730/"
] | When [Air Transat Flight 326](https://en.wikipedia.org/wiki/Air_Transat_Flight_236) glided into the Azores after fuel exhaustion over the Atlantic, the pilots were unsure whether they would be able to apply the brakes on their Airbus 330 more than once, and their anti-skid systems were inoperative. So they applied the brakes and held them, locking the wheels. The results, from the [accident report:](http://www.fss.aero/accident-reports/dvdfiles/PT/2001-08-24-PT.pdf)
>
> The tires quickly abraded and deflated at a point between about 300 and 450 feet beyond the second and final touch down. The segments of the main wheels contacting the pavement were worn down to the bearing journals, the left, rear, inboard wheel detached from the axle. Both left and right brake anti-torque links attachment horns on the bottom segments of the main oleos also contacted the pavement; the horns were abraded to the point that some of the links separated from the oleo resulting in the rotation of at least one brake carrier. Shedding of brake and wheel components during the landing run also resulted in a combination of punctures and impact damage to the airframe and left engine nacelle.
>
>
> ...
>
>
> CFR [Crash Fire Rescue] reported that there was fire visible coming from the
> main wheels, and responded to put out the fire. At 06:46, CFR reported that the evacuation was in progress and that some signs of fire still existed in the left main wheels. By 06:54, all fires were extinguished; the areas around the main wheels continued to be monitored due to the fire hazard associated with the damaged wheels and hot brakes.
>
>
>
[](https://i.stack.imgur.com/5Ab5D.png)
However, the airline stayed on the runway, and everyone survived. (Two passengers were hospitalized due to their injuries.) | If that happens to an airliner(full brakes at touchdown), a lot can happen.
1- depending on the landing speed, the wheel struts could break off
2- if the struts resist such enormous load and bending force, the n the wheels will wear and burst due to friction and then most certainly burn depending on the condition of the runway(wet or dry). |
24,490,844 | This may be a noob question as i am new to Android development.
So i downloaded **ADT** and when i started **SDK Manager** it threw me a long list of Android APIs; i installed the latest API but i got confused as i don't know if i only install **API 20** will i get full Android API or specific to that version/release?
**For example:** I downloaded API for KitKat so i get the full API with all the classes and interfaces? or only the new ones that are introduced in KitKat? | 2014/06/30 | [
"https://Stackoverflow.com/questions/24490844",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/2065490/"
] | If you download API 20, you will get all the API's that are available to the level 20. It means you will get the new features, AND all the apis that are required to develop for devices running level 20.
**It does not mean that you will only get the updates**
Some features might be deprecated in a newer version. That means if a particular function has been changed, you will get updated version in the respective level. | It will give you a latest API, but if any feature are been diprecated, they won't be included in them. But for startup purpose its no stuffs to worry about having only one API installed.
refer the below link:-
[Android API References](http://developer.android.com/guide/topics/manifest/uses-sdk-element.html) |
51,090 | Central Banks around the world have cut interest rates in the past few days in response to the COVID-19 pandemic, including the [US Federal Reserve (0-0.25%)](https://www.federalreserve.gov/newsevents/pressreleases/monetary20200315a1.htm), the [Bank of England (0.1%)](https://www.bankofengland.co.uk/monetary-policy-summary-and-minutes/2020/monetary-policy-summary-for-the-special-monetary-policy-committee-meeting-on-19-march-2020), and the [Reserve Bank of Australia (0.25%)](https://www.rba.gov.au/media-releases/2020/mr-20-08.html). Notably, the European Central Bank has not yet cut interest rates further, but this is partly because it is already in the negatives, at [-0.5%](https://www.ecb.europa.eu/stats/policy_and_exchange_rates/key_ecb_interest_rates/html/index.en.html).
Why are central banks taking this measure in response to this pandemic in particular - i.e. how does this measure lessen the pandemic's economic impact - and what are the impacts on the average consumer of a cut in their country's central bank interest rate in general? | 2020/03/19 | [
"https://politics.stackexchange.com/questions/51090",
"https://politics.stackexchange.com",
"https://politics.stackexchange.com/users/28994/"
] | Cutting interest rates makes loans cheaper for banks. It's typically used [in bad economic times](https://www.cnbc.com/2020/03/15/federal-reserve-cuts-rates-to-zero-and-launches-massive-700-billion-quantitative-easing-program.html)
[](https://i.stack.imgur.com/VzA3L.png)
Why is it important? [It helps keep banks liquid](https://nymag.com/intelligencer/2020/03/why-the-federal-reserve-cut-interest-rates-to-zero.html)
>
> The Federal Reserve cannot directly improve how our government is handling the novel coronavirus, and as I’ve written before, it can’t do a lot right now to stimulate the economy through low interest rates. Where the Fed can do a lot is helping to ensure virus-driven problems in the real economy do not turn into problems in the banking system. The ultra-low rate at the discount window is intended to eliminate any hesitation banks might have about borrowing directly from the Fed; in normal conditions, market participants may look at a bank borrowing at the discount window and infer that it has problems and couldn’t find capital anywhere else. But when the rate is this low, borrowing at the discount window just looks like something you do because it is a good deal. With this move, the Fed is helping banks access the liquidity they need in times of extreme financial uncertainty, and therefore helping to ensure the availability of credit to businesses and individuals.
>
>
>
Liquidity is important because banks need money "in the vault" (so to speak) to operate. In times like these, banks are taking a double hit from both lower asset values and people wanting more in cash. If a bank were to run out of liquid cash, it could cause a [bank run](https://en.wikipedia.org/wiki/Bank_run)
>
> A bank run (also known as a run on the bank) occurs when many clients withdraw their money from a bank, because they believe the bank may cease to function in the near future. In other words, it is when, in a fractional-reserve banking system (where banks normally only keep a small proportion of their assets as cash), numerous customers withdraw cash from deposit accounts with a financial institution at the same time because they believe that the financial institution is, or might become, insolvent; they keep the cash or transfer it into other assets, such as government bonds, precious metals or gemstones. When they transfer funds to another institution, it may be characterized as a capital flight. As a bank run progresses, it generates its own momentum: as more people withdraw cash, the likelihood of default increases, triggering further withdrawals. This can destabilize the bank to the point where it runs out of cash and thus faces sudden bankruptcy. To combat a bank run, a bank may limit how much cash each customer may withdraw, suspend withdrawals altogether, or promptly acquire more cash from other banks or from the central bank, besides other measures.
>
>
>
See also [the Fed's $1.5T injection](https://politics.stackexchange.com/q/50968/12027) | By lowering interest rates the Fed's main goal is to prop up the stock market, and support US corporations.
This is achieved through the following effects:
- it encourages credit creation through bank lending, and because most money originates in credit it makes money cheaper and more widely available
- it lowers the rates of return on savings and thus encourages savers to spend more freely, which has a twofold effect: it stimulates the economy into the creation of yet more loans, and it tells savers to go elsewhere with their money
The resulting availability of money/credit and lowered bank savings rates makes the stock market an attractive destination.
Since 2007, the financial crisis, the Fed is essentially a hostage of the stock market in that if now *must* keep loose monetary policy to further the illusion of perpetual long term stock market gains. This is further evidenced by the tentative and then aborted QT (quantitive tightening) attempt last year.
In the current climate of coronavirus economic meltdown, the lowered interest rate has a further goal: to help protect US corporations who are now overstretched on corporate bonds.
Since 2007, unbeknownst to many, and I think illegal outside the US (?) , corporations - rather than restructure in the wake of the crisis - regularly take advantage of the cheap money stimulus by issuing corporate bonds (essentially borrowing money at low rates) so that their execs can use this to direct the company to purchase its own stock on the stock market. This creates the illusion of rising corporate value while allowing shareholders to receive big dividends and CEOs to pay themselves income related bonuses.
This irresponsible corporate behaviour has brought US corporations to the point that the coronavirus meltdown has slowed earnings below what they need to pay on the corporate bonds. Without direct government support many US corporations will go bust, and corporate bond prices will plummet, which will trigger further meltdown in financial institutions that invest in those assets.
Again, silently under the media radar, just this week the US (?) and ECB created new funds that will be directed to supply money to those institutions buying corporate bonds. To be clear, the way that works is that bondholders who are now nervous about the corporation defaulting might not roll over their bond....rather than reacquiring bonds at the end of their term, or even ending prematurely, they will demand their money from the corps. The corps. don't have it, but new bonds will be sold to the govt backed funds. (Once again the taxpayer bails out the fatcat)
So in summary, the reduced interest rate in combo with new funds, is designed to prop up the stock market and corporations to prevent socioeconomic collapse.
Around the world, central banks lower the rate for the effects of stimulus and stock market prop-up described above. ECB does not lower because the negative interest rate actually makes loans more expensive in some cases as being paid to borrow makes it easier than to lend. |
51,090 | Central Banks around the world have cut interest rates in the past few days in response to the COVID-19 pandemic, including the [US Federal Reserve (0-0.25%)](https://www.federalreserve.gov/newsevents/pressreleases/monetary20200315a1.htm), the [Bank of England (0.1%)](https://www.bankofengland.co.uk/monetary-policy-summary-and-minutes/2020/monetary-policy-summary-for-the-special-monetary-policy-committee-meeting-on-19-march-2020), and the [Reserve Bank of Australia (0.25%)](https://www.rba.gov.au/media-releases/2020/mr-20-08.html). Notably, the European Central Bank has not yet cut interest rates further, but this is partly because it is already in the negatives, at [-0.5%](https://www.ecb.europa.eu/stats/policy_and_exchange_rates/key_ecb_interest_rates/html/index.en.html).
Why are central banks taking this measure in response to this pandemic in particular - i.e. how does this measure lessen the pandemic's economic impact - and what are the impacts on the average consumer of a cut in their country's central bank interest rate in general? | 2020/03/19 | [
"https://politics.stackexchange.com/questions/51090",
"https://politics.stackexchange.com",
"https://politics.stackexchange.com/users/28994/"
] | Cutting interest rates makes loans cheaper for banks. It's typically used [in bad economic times](https://www.cnbc.com/2020/03/15/federal-reserve-cuts-rates-to-zero-and-launches-massive-700-billion-quantitative-easing-program.html)
[](https://i.stack.imgur.com/VzA3L.png)
Why is it important? [It helps keep banks liquid](https://nymag.com/intelligencer/2020/03/why-the-federal-reserve-cut-interest-rates-to-zero.html)
>
> The Federal Reserve cannot directly improve how our government is handling the novel coronavirus, and as I’ve written before, it can’t do a lot right now to stimulate the economy through low interest rates. Where the Fed can do a lot is helping to ensure virus-driven problems in the real economy do not turn into problems in the banking system. The ultra-low rate at the discount window is intended to eliminate any hesitation banks might have about borrowing directly from the Fed; in normal conditions, market participants may look at a bank borrowing at the discount window and infer that it has problems and couldn’t find capital anywhere else. But when the rate is this low, borrowing at the discount window just looks like something you do because it is a good deal. With this move, the Fed is helping banks access the liquidity they need in times of extreme financial uncertainty, and therefore helping to ensure the availability of credit to businesses and individuals.
>
>
>
Liquidity is important because banks need money "in the vault" (so to speak) to operate. In times like these, banks are taking a double hit from both lower asset values and people wanting more in cash. If a bank were to run out of liquid cash, it could cause a [bank run](https://en.wikipedia.org/wiki/Bank_run)
>
> A bank run (also known as a run on the bank) occurs when many clients withdraw their money from a bank, because they believe the bank may cease to function in the near future. In other words, it is when, in a fractional-reserve banking system (where banks normally only keep a small proportion of their assets as cash), numerous customers withdraw cash from deposit accounts with a financial institution at the same time because they believe that the financial institution is, or might become, insolvent; they keep the cash or transfer it into other assets, such as government bonds, precious metals or gemstones. When they transfer funds to another institution, it may be characterized as a capital flight. As a bank run progresses, it generates its own momentum: as more people withdraw cash, the likelihood of default increases, triggering further withdrawals. This can destabilize the bank to the point where it runs out of cash and thus faces sudden bankruptcy. To combat a bank run, a bank may limit how much cash each customer may withdraw, suspend withdrawals altogether, or promptly acquire more cash from other banks or from the central bank, besides other measures.
>
>
>
See also [the Fed's $1.5T injection](https://politics.stackexchange.com/q/50968/12027) | The theory goes something like this:
1. If interest rates are lower, there's less reason to save. After all you earn less from interest.
2. If money isn't being saved, it's being spent.
3. More spending (= more buying = more business) helps the economy. |
51,090 | Central Banks around the world have cut interest rates in the past few days in response to the COVID-19 pandemic, including the [US Federal Reserve (0-0.25%)](https://www.federalreserve.gov/newsevents/pressreleases/monetary20200315a1.htm), the [Bank of England (0.1%)](https://www.bankofengland.co.uk/monetary-policy-summary-and-minutes/2020/monetary-policy-summary-for-the-special-monetary-policy-committee-meeting-on-19-march-2020), and the [Reserve Bank of Australia (0.25%)](https://www.rba.gov.au/media-releases/2020/mr-20-08.html). Notably, the European Central Bank has not yet cut interest rates further, but this is partly because it is already in the negatives, at [-0.5%](https://www.ecb.europa.eu/stats/policy_and_exchange_rates/key_ecb_interest_rates/html/index.en.html).
Why are central banks taking this measure in response to this pandemic in particular - i.e. how does this measure lessen the pandemic's economic impact - and what are the impacts on the average consumer of a cut in their country's central bank interest rate in general? | 2020/03/19 | [
"https://politics.stackexchange.com/questions/51090",
"https://politics.stackexchange.com",
"https://politics.stackexchange.com/users/28994/"
] | Cutting interest rates makes loans cheaper for banks. It's typically used [in bad economic times](https://www.cnbc.com/2020/03/15/federal-reserve-cuts-rates-to-zero-and-launches-massive-700-billion-quantitative-easing-program.html)
[](https://i.stack.imgur.com/VzA3L.png)
Why is it important? [It helps keep banks liquid](https://nymag.com/intelligencer/2020/03/why-the-federal-reserve-cut-interest-rates-to-zero.html)
>
> The Federal Reserve cannot directly improve how our government is handling the novel coronavirus, and as I’ve written before, it can’t do a lot right now to stimulate the economy through low interest rates. Where the Fed can do a lot is helping to ensure virus-driven problems in the real economy do not turn into problems in the banking system. The ultra-low rate at the discount window is intended to eliminate any hesitation banks might have about borrowing directly from the Fed; in normal conditions, market participants may look at a bank borrowing at the discount window and infer that it has problems and couldn’t find capital anywhere else. But when the rate is this low, borrowing at the discount window just looks like something you do because it is a good deal. With this move, the Fed is helping banks access the liquidity they need in times of extreme financial uncertainty, and therefore helping to ensure the availability of credit to businesses and individuals.
>
>
>
Liquidity is important because banks need money "in the vault" (so to speak) to operate. In times like these, banks are taking a double hit from both lower asset values and people wanting more in cash. If a bank were to run out of liquid cash, it could cause a [bank run](https://en.wikipedia.org/wiki/Bank_run)
>
> A bank run (also known as a run on the bank) occurs when many clients withdraw their money from a bank, because they believe the bank may cease to function in the near future. In other words, it is when, in a fractional-reserve banking system (where banks normally only keep a small proportion of their assets as cash), numerous customers withdraw cash from deposit accounts with a financial institution at the same time because they believe that the financial institution is, or might become, insolvent; they keep the cash or transfer it into other assets, such as government bonds, precious metals or gemstones. When they transfer funds to another institution, it may be characterized as a capital flight. As a bank run progresses, it generates its own momentum: as more people withdraw cash, the likelihood of default increases, triggering further withdrawals. This can destabilize the bank to the point where it runs out of cash and thus faces sudden bankruptcy. To combat a bank run, a bank may limit how much cash each customer may withdraw, suspend withdrawals altogether, or promptly acquire more cash from other banks or from the central bank, besides other measures.
>
>
>
See also [the Fed's $1.5T injection](https://politics.stackexchange.com/q/50968/12027) | Lowering interest rates brings future consumption to the present, it has zero net effect over the medium to long term. For example you can only buy a home to live in once in your life, if you do it now you won't do it further into the future. The central banks know this and they also know the day of reckoning will eventually arrive, where their pea and thimble trick will no longer work, because the consumer is all but tapped out. So the real is answer is, they lower interest rates because they are going to try and avoid a depression on their watch and hope that it happens to some other schmuck who replaces them. |
51,090 | Central Banks around the world have cut interest rates in the past few days in response to the COVID-19 pandemic, including the [US Federal Reserve (0-0.25%)](https://www.federalreserve.gov/newsevents/pressreleases/monetary20200315a1.htm), the [Bank of England (0.1%)](https://www.bankofengland.co.uk/monetary-policy-summary-and-minutes/2020/monetary-policy-summary-for-the-special-monetary-policy-committee-meeting-on-19-march-2020), and the [Reserve Bank of Australia (0.25%)](https://www.rba.gov.au/media-releases/2020/mr-20-08.html). Notably, the European Central Bank has not yet cut interest rates further, but this is partly because it is already in the negatives, at [-0.5%](https://www.ecb.europa.eu/stats/policy_and_exchange_rates/key_ecb_interest_rates/html/index.en.html).
Why are central banks taking this measure in response to this pandemic in particular - i.e. how does this measure lessen the pandemic's economic impact - and what are the impacts on the average consumer of a cut in their country's central bank interest rate in general? | 2020/03/19 | [
"https://politics.stackexchange.com/questions/51090",
"https://politics.stackexchange.com",
"https://politics.stackexchange.com/users/28994/"
] | By lowering interest rates the Fed's main goal is to prop up the stock market, and support US corporations.
This is achieved through the following effects:
- it encourages credit creation through bank lending, and because most money originates in credit it makes money cheaper and more widely available
- it lowers the rates of return on savings and thus encourages savers to spend more freely, which has a twofold effect: it stimulates the economy into the creation of yet more loans, and it tells savers to go elsewhere with their money
The resulting availability of money/credit and lowered bank savings rates makes the stock market an attractive destination.
Since 2007, the financial crisis, the Fed is essentially a hostage of the stock market in that if now *must* keep loose monetary policy to further the illusion of perpetual long term stock market gains. This is further evidenced by the tentative and then aborted QT (quantitive tightening) attempt last year.
In the current climate of coronavirus economic meltdown, the lowered interest rate has a further goal: to help protect US corporations who are now overstretched on corporate bonds.
Since 2007, unbeknownst to many, and I think illegal outside the US (?) , corporations - rather than restructure in the wake of the crisis - regularly take advantage of the cheap money stimulus by issuing corporate bonds (essentially borrowing money at low rates) so that their execs can use this to direct the company to purchase its own stock on the stock market. This creates the illusion of rising corporate value while allowing shareholders to receive big dividends and CEOs to pay themselves income related bonuses.
This irresponsible corporate behaviour has brought US corporations to the point that the coronavirus meltdown has slowed earnings below what they need to pay on the corporate bonds. Without direct government support many US corporations will go bust, and corporate bond prices will plummet, which will trigger further meltdown in financial institutions that invest in those assets.
Again, silently under the media radar, just this week the US (?) and ECB created new funds that will be directed to supply money to those institutions buying corporate bonds. To be clear, the way that works is that bondholders who are now nervous about the corporation defaulting might not roll over their bond....rather than reacquiring bonds at the end of their term, or even ending prematurely, they will demand their money from the corps. The corps. don't have it, but new bonds will be sold to the govt backed funds. (Once again the taxpayer bails out the fatcat)
So in summary, the reduced interest rate in combo with new funds, is designed to prop up the stock market and corporations to prevent socioeconomic collapse.
Around the world, central banks lower the rate for the effects of stimulus and stock market prop-up described above. ECB does not lower because the negative interest rate actually makes loans more expensive in some cases as being paid to borrow makes it easier than to lend. | Lowering interest rates brings future consumption to the present, it has zero net effect over the medium to long term. For example you can only buy a home to live in once in your life, if you do it now you won't do it further into the future. The central banks know this and they also know the day of reckoning will eventually arrive, where their pea and thimble trick will no longer work, because the consumer is all but tapped out. So the real is answer is, they lower interest rates because they are going to try and avoid a depression on their watch and hope that it happens to some other schmuck who replaces them. |
51,090 | Central Banks around the world have cut interest rates in the past few days in response to the COVID-19 pandemic, including the [US Federal Reserve (0-0.25%)](https://www.federalreserve.gov/newsevents/pressreleases/monetary20200315a1.htm), the [Bank of England (0.1%)](https://www.bankofengland.co.uk/monetary-policy-summary-and-minutes/2020/monetary-policy-summary-for-the-special-monetary-policy-committee-meeting-on-19-march-2020), and the [Reserve Bank of Australia (0.25%)](https://www.rba.gov.au/media-releases/2020/mr-20-08.html). Notably, the European Central Bank has not yet cut interest rates further, but this is partly because it is already in the negatives, at [-0.5%](https://www.ecb.europa.eu/stats/policy_and_exchange_rates/key_ecb_interest_rates/html/index.en.html).
Why are central banks taking this measure in response to this pandemic in particular - i.e. how does this measure lessen the pandemic's economic impact - and what are the impacts on the average consumer of a cut in their country's central bank interest rate in general? | 2020/03/19 | [
"https://politics.stackexchange.com/questions/51090",
"https://politics.stackexchange.com",
"https://politics.stackexchange.com/users/28994/"
] | The theory goes something like this:
1. If interest rates are lower, there's less reason to save. After all you earn less from interest.
2. If money isn't being saved, it's being spent.
3. More spending (= more buying = more business) helps the economy. | Lowering interest rates brings future consumption to the present, it has zero net effect over the medium to long term. For example you can only buy a home to live in once in your life, if you do it now you won't do it further into the future. The central banks know this and they also know the day of reckoning will eventually arrive, where their pea and thimble trick will no longer work, because the consumer is all but tapped out. So the real is answer is, they lower interest rates because they are going to try and avoid a depression on their watch and hope that it happens to some other schmuck who replaces them. |
5,686,934 | I have installed Eclipse SDK, which doesn't come with Eclipse Marketplace. Is it possible to download Eclipse Marketplace as a plugin?
From what it looks from their site, it seems as we can only get it when downloading specific versions of Eclipse.
Thanks | 2011/04/16 | [
"https://Stackoverflow.com/questions/5686934",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/130758/"
] | See [How do I install Eclipse Marketplace in Eclipse Classic?](https://stackoverflow.com/questions/5285623/how-do-i-install-eclipse-marketplace-in-eclipse-classic) | As far as I know, the Classic distribution does not contain the Marketplace client (and that is the only such official distribution). However, it is available for download.
Select Help/Install new software... from the menu, select the Juno update site (<http://download.eclipse.org/releases/juno>), and then look for the Marketplace client - it is in the General Purpose Tools category. |
166,155 | I want to "host" a blender file. I mean if antoher pc edit it I can see it from my PC. Is there any way to do that? | 2020/02/07 | [
"https://blender.stackexchange.com/questions/166155",
"https://blender.stackexchange.com",
"https://blender.stackexchange.com/users/76472/"
] | Unable to load your Blend file (still operating on Vers 2.77a) and probably not seeing what your helpers are referring to.
[](https://i.stack.imgur.com/CE8GB.gif)
Going on your pic and on the face of it, the problem you appear to be encountering, might well be solvable by simply parenting all components to the one common parent and moving/rotating that instead.
I see 'parenting' has been mentioned in the comments/answers but would this make it a little clearer? ...
By making every separate component a child of a common parent, using the parenting feature, (CTL-P) not the child-of constraint, that parent (the Circle-Empty) should "localise" and hold all the bits & pieces together, with respect to the Empty. (and the house)
It's the empty you move/rotate around the scene, not the house or it's components.
The house and components would be forced to move with the Parent-Empty and importantly, their relative positions are maintained with respect to the house.
Individual components can still be moved around, scaled etc without affecting the 'bond'.
I apologise if I'm barking up the wrong tree here, I cannot see the Blend file, but if it helps... If not, say so and I'll delete this. | Select all of the objects by pressing 'A', then rotate by pressing 'R' + 'Z' to rotate on the Z axis. If you want to reset the origin of the other house to the same as the first part you have rotated, then set the cursor to that part of the house, then select the other part you want to reset the origin on. Go to **Objec > Transform > Origin to 3D Cursor**. Now it will rotate on the same origin. |
304,574 | There seems to be a recent trend in JavaScript towards treating data structures as immutable. For example, if you need to change a single property of an object, better to just create a whole new object with the new property, and just copy over all the other properties from the old object, and let the old object be garbage collected. (That's my understanding anyway.)
My initial reaction is, that sounds like it would be bad for performance.
But then libraries like [Immutable.js](http://facebook.github.io/immutable-js/) and [Redux.js](http://redux.js.org/) are written by smarter people than me, and seem to have a strong concern for performance, so it makes me wonder if my understanding of garbage (and its performance impact) is wrong.
Are there performance benefits to immutability I'm missing, and do they outweigh the downsides of creating so much garbage? | 2015/12/08 | [
"https://softwareengineering.stackexchange.com/questions/304574",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/30385/"
] | To add on to this (already excellently answered) question:
The short answer is **yes**; it will hurt performance because you're only ever creating objects instead of mutating existing ones, resulting in more object creation overhead.
---
However, the long answer is **not really**.
From an actual runtime point of view, in JavaScript you already create quite a lot of runtime objects - functions and object literals are everywhere in JavaScript and no-one seems to think twice about using those. I would argue that object creation is actually quite cheap, though I have no citations for this so I wouldn't use it as a stand-alone argument.
For me, the biggest 'performance' increase isn't in runtime performance but in **developer** performance. One of the first things I learned while working on Real World (tm) applications is that mutability is really dangerous and confusing. I've lost many hours chasing down a thread (not the concurrency type) of execution trying to work out what is causing an obscure bug when it turns out to be a mutation from the other side of the damn application!
Using immutability makes things a **lot** easier to reason about. You're able to know immediately that X object is **not** going to change during its lifetime, and the only way for it to change is to clone it. I value this a lot more (especially in team environments) than any micro-optimisations that mutability might bring.
There are exceptions, most notably data structures as noted above. I've rarely come across a scenario where I have wanted to alter a map after creation (although admittedly I am talking about pseudo-object-literal maps rather than ES6 maps), same for arrays. When you're dealing with larger data structures, mutability *might* pay off. Remember that every object in JavaScript is passed as a reference rather than a value.
---
That said, one point brought up above was the GC and its inability to detect duplications. This is a legitimate concern, but in my opinion it is only a concern when memory is a concern, and there are far easier ways to code yourself into a corner - for example, circular references in closures.
---
Ultimately, I would prefer to have an immutable codebase with *very* few (if any) mutable sections and be slightly less performant than have mutability everywhere. You can always optimise later on if immutability, for some reason, becomes a concern for performance. | In a straight line, immutable code has the overhead of object creation, which is slower. However, there are a lot of situations where mutable code becomes very difficult to manage efficiently (resulting in a lot of defensive copying, which is expensive too), and there are a lot of clever strategies for mitigating the cost of 'copying' an object, as mentioned by others.
If you have an object such as a counter, and it's getting incremented many times a second, having that counter be immutable might not be worth the performance penalty. If you have an object that's being read by many different parts of your application, and each of them want to have their own slightly different clone of the object, you'll have a far easier time orchestrating that in a performant manner by using a good immutable object implementation. |
304,574 | There seems to be a recent trend in JavaScript towards treating data structures as immutable. For example, if you need to change a single property of an object, better to just create a whole new object with the new property, and just copy over all the other properties from the old object, and let the old object be garbage collected. (That's my understanding anyway.)
My initial reaction is, that sounds like it would be bad for performance.
But then libraries like [Immutable.js](http://facebook.github.io/immutable-js/) and [Redux.js](http://redux.js.org/) are written by smarter people than me, and seem to have a strong concern for performance, so it makes me wonder if my understanding of garbage (and its performance impact) is wrong.
Are there performance benefits to immutability I'm missing, and do they outweigh the downsides of creating so much garbage? | 2015/12/08 | [
"https://softwareengineering.stackexchange.com/questions/304574",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/30385/"
] | First of all, your characterization of immutable data structures is imprecise. In general, most of a data structure is not copied, but *shared*, and only the changed portions are copied. It is called a [persistent data structure](https://en.wikipedia.org/wiki/Persistent_data_structure). Most implementations are able to take advantage of persistent data structures most of the time. The performance is close enough to mutable data structures that functional programmers generally consider it negligible.
Second, I find a lot of people have a fairly inaccurate idea of the typical lifetime of objects in typical imperative programs. Perhaps this is due to the popularity of memory-managed languages. Sit down sometime and really look at how many temporary objects and defensive copies you create compared to truly long-lived data structures. I think you'll be surprised at the ratio.
I've had people remark in functional programming classes I teach about how much garbage an algorithm creates, then I show the typical imperative version of the same algorithm that creates just as much. Just for some reason people don't notice it anymore.
By encouraging sharing and discouraging creating variables until you have a valid value to put in them, immutability tends to encourage cleaner coding practices and longer lived data structures. This often leads to comparable if not lower levels of garbage, depending on your algorithm. | To add on to this (already excellently answered) question:
The short answer is **yes**; it will hurt performance because you're only ever creating objects instead of mutating existing ones, resulting in more object creation overhead.
---
However, the long answer is **not really**.
From an actual runtime point of view, in JavaScript you already create quite a lot of runtime objects - functions and object literals are everywhere in JavaScript and no-one seems to think twice about using those. I would argue that object creation is actually quite cheap, though I have no citations for this so I wouldn't use it as a stand-alone argument.
For me, the biggest 'performance' increase isn't in runtime performance but in **developer** performance. One of the first things I learned while working on Real World (tm) applications is that mutability is really dangerous and confusing. I've lost many hours chasing down a thread (not the concurrency type) of execution trying to work out what is causing an obscure bug when it turns out to be a mutation from the other side of the damn application!
Using immutability makes things a **lot** easier to reason about. You're able to know immediately that X object is **not** going to change during its lifetime, and the only way for it to change is to clone it. I value this a lot more (especially in team environments) than any micro-optimisations that mutability might bring.
There are exceptions, most notably data structures as noted above. I've rarely come across a scenario where I have wanted to alter a map after creation (although admittedly I am talking about pseudo-object-literal maps rather than ES6 maps), same for arrays. When you're dealing with larger data structures, mutability *might* pay off. Remember that every object in JavaScript is passed as a reference rather than a value.
---
That said, one point brought up above was the GC and its inability to detect duplications. This is a legitimate concern, but in my opinion it is only a concern when memory is a concern, and there are far easier ways to code yourself into a corner - for example, circular references in closures.
---
Ultimately, I would prefer to have an immutable codebase with *very* few (if any) mutable sections and be slightly less performant than have mutability everywhere. You can always optimise later on if immutability, for some reason, becomes a concern for performance. |
304,574 | There seems to be a recent trend in JavaScript towards treating data structures as immutable. For example, if you need to change a single property of an object, better to just create a whole new object with the new property, and just copy over all the other properties from the old object, and let the old object be garbage collected. (That's my understanding anyway.)
My initial reaction is, that sounds like it would be bad for performance.
But then libraries like [Immutable.js](http://facebook.github.io/immutable-js/) and [Redux.js](http://redux.js.org/) are written by smarter people than me, and seem to have a strong concern for performance, so it makes me wonder if my understanding of garbage (and its performance impact) is wrong.
Are there performance benefits to immutability I'm missing, and do they outweigh the downsides of creating so much garbage? | 2015/12/08 | [
"https://softwareengineering.stackexchange.com/questions/304574",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/30385/"
] | First of all, your characterization of immutable data structures is imprecise. In general, most of a data structure is not copied, but *shared*, and only the changed portions are copied. It is called a [persistent data structure](https://en.wikipedia.org/wiki/Persistent_data_structure). Most implementations are able to take advantage of persistent data structures most of the time. The performance is close enough to mutable data structures that functional programmers generally consider it negligible.
Second, I find a lot of people have a fairly inaccurate idea of the typical lifetime of objects in typical imperative programs. Perhaps this is due to the popularity of memory-managed languages. Sit down sometime and really look at how many temporary objects and defensive copies you create compared to truly long-lived data structures. I think you'll be surprised at the ratio.
I've had people remark in functional programming classes I teach about how much garbage an algorithm creates, then I show the typical imperative version of the same algorithm that creates just as much. Just for some reason people don't notice it anymore.
By encouraging sharing and discouraging creating variables until you have a valid value to put in them, immutability tends to encourage cleaner coding practices and longer lived data structures. This often leads to comparable if not lower levels of garbage, depending on your algorithm. | In a straight line, immutable code has the overhead of object creation, which is slower. However, there are a lot of situations where mutable code becomes very difficult to manage efficiently (resulting in a lot of defensive copying, which is expensive too), and there are a lot of clever strategies for mitigating the cost of 'copying' an object, as mentioned by others.
If you have an object such as a counter, and it's getting incremented many times a second, having that counter be immutable might not be worth the performance penalty. If you have an object that's being read by many different parts of your application, and each of them want to have their own slightly different clone of the object, you'll have a far easier time orchestrating that in a performant manner by using a good immutable object implementation. |
304,574 | There seems to be a recent trend in JavaScript towards treating data structures as immutable. For example, if you need to change a single property of an object, better to just create a whole new object with the new property, and just copy over all the other properties from the old object, and let the old object be garbage collected. (That's my understanding anyway.)
My initial reaction is, that sounds like it would be bad for performance.
But then libraries like [Immutable.js](http://facebook.github.io/immutable-js/) and [Redux.js](http://redux.js.org/) are written by smarter people than me, and seem to have a strong concern for performance, so it makes me wonder if my understanding of garbage (and its performance impact) is wrong.
Are there performance benefits to immutability I'm missing, and do they outweigh the downsides of creating so much garbage? | 2015/12/08 | [
"https://softwareengineering.stackexchange.com/questions/304574",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/30385/"
] | >
> For example, if you need to change a single property of an object, better to just create a whole new object with the new property, and just copy over all the other properties from the old object, and let the old object be garbage collected.
>
>
>
Without immutability, you might have to pass an object around between different scopes, and you do not know beforehand if and when the object will be changed. So to avoid unwanted side effects, you start creating a full copy of the object "just in case" and pass that copy around, even if it turns out no property has to be changed at all. That will leave a lot more garbage than in your case.
What this demonstrates is - if you create the right hypothetical scenario, you can prove anything, especially when it comes to performance. My example, however, is not so hypothetical as it might sound. I worked last month on a program where we stumbled over exactly that problem because we initially decided against using an immutable data structure, and hesitated to refactor this later because it did not seem worth the hassle.
So when you look at cases like [this one from an older SO post](https://stackoverflow.com/questions/4101924/functional-programming-is-immutability-expensive), the answer to your questions becomes probably clear - **it depends**. For some cases immutability will hurt performance, for some the opposite might be true, for lots of cases it will depend on how smart your implementation is, and for even more cases the difference will be negligible.
A final note: a real world problem you might encounter is you need to decide early for or against immutability for some basic data structures. Then you build a lot of code upon that, and several weeks or months later you will see if the decision was a good or a bad one.
My personal rule of thumb for this situation is:
* If you design a data structure with only a few attributes based on primitive or other immutable types, try immutability first.
* If you want to design a data type where arrays with large (or undefined) size, random access and changing contents are involved, use mutability.
For situations between these two extremes, use your judgement. But YMMV. | First of all, your characterization of immutable data structures is imprecise. In general, most of a data structure is not copied, but *shared*, and only the changed portions are copied. It is called a [persistent data structure](https://en.wikipedia.org/wiki/Persistent_data_structure). Most implementations are able to take advantage of persistent data structures most of the time. The performance is close enough to mutable data structures that functional programmers generally consider it negligible.
Second, I find a lot of people have a fairly inaccurate idea of the typical lifetime of objects in typical imperative programs. Perhaps this is due to the popularity of memory-managed languages. Sit down sometime and really look at how many temporary objects and defensive copies you create compared to truly long-lived data structures. I think you'll be surprised at the ratio.
I've had people remark in functional programming classes I teach about how much garbage an algorithm creates, then I show the typical imperative version of the same algorithm that creates just as much. Just for some reason people don't notice it anymore.
By encouraging sharing and discouraging creating variables until you have a valid value to put in them, immutability tends to encourage cleaner coding practices and longer lived data structures. This often leads to comparable if not lower levels of garbage, depending on your algorithm. |
844 | I, myself, do not plan on getting into a situation where I would be unable to use a computer in order to communicate securely. However, I can think of many practical situations in which mental cryptography would be useful.
Is there a secure cryptosystem that is simple enough to be performed mentally?
Clearly, one of the challenges is remembering >100 bits of entropy to leverage, but I am assuming that this can be done beforehand.
How susceptible would any such system be to side channel attacks (like trash rummaging)? | 2011/09/28 | [
"https://crypto.stackexchange.com/questions/844",
"https://crypto.stackexchange.com",
"https://crypto.stackexchange.com/users/99/"
] | I can think of 2 cryptographic systems.
One that can be done with a deck of cards is a scheme called [Pontifex](http://en.wikipedia.org/wiki/Solitaire_%28cipher%29) (aka solitaire) that was developed for the book [Cryptonomicon](http://rads.stackoverflow.com/amzn/click/0380973464). Some more technical details and example of it in use at [Bruce Schneier's website](http://www.schneier.com/solitaire.html). Although it should be noted that some [weaknesses](http://www.ciphergoth.org/crypto/solitaire/) have been discovered in Pontifex .
Another one, although this one involves lots of paper, is a [straddling checkerboard](http://en.wikipedia.org/wiki/Straddling_checkerboard) which formed the basis of the system used by Soviet spies in the US (the full system was more complicated and called [VIC](http://en.wikipedia.org/wiki/VIC_cipher)). The spy using the system would only need to remember a phrase and a date. From these 2 items, one could [generate the checkerboard](http://practicalcryptography.com/ciphers/straddle-checkerboard-cipher/). It takes a simple set of rules to encode a message. The book [Kahn on Codes](http://rads.stackoverflow.com/amzn/click/0025606409) has a couple of pages where they explain how messages were encrypted with this scheme. Several spies were detected by finding intermediate work in trash. | **this doesn't suit the entropy part**
the old & basic encoding mechanisms like Caesar (easy) or Substitution (concentrate) Cipher could be done mentally too.
if you simply want to speak or signal an encoded message to few in public place.
You could do "gibberish talk", which has several ways..... with basic outline as
* decide on peices of 'gibberish' (some jumbled up letters) and their place-holders in the sentence (like spaces, fullstop); you can even choose multiple gibberish for same placeholder and use randomly any of it for more Confusion
* decide on break-point length for actual words, after which the gibberish has to be inserted..... you can even have a series of queued break-points if you can process it |
844 | I, myself, do not plan on getting into a situation where I would be unable to use a computer in order to communicate securely. However, I can think of many practical situations in which mental cryptography would be useful.
Is there a secure cryptosystem that is simple enough to be performed mentally?
Clearly, one of the challenges is remembering >100 bits of entropy to leverage, but I am assuming that this can be done beforehand.
How susceptible would any such system be to side channel attacks (like trash rummaging)? | 2011/09/28 | [
"https://crypto.stackexchange.com/questions/844",
"https://crypto.stackexchange.com",
"https://crypto.stackexchange.com/users/99/"
] | *(Converted to answer from a comment.)*
If pen and paper are permitted, one could probably carry out the [RC4](http://en.wikipedia.org/wiki/RC4) algorithm fairly easily using 256 numbered pieces of paper (small post-it notes might be ideal, since they'd be harder to move by accident) arranged in a 16 by 16 grid (I'd suggest numbering the notes in hex for easier indexing), with two coins or something to keep track of the $i$ and $j$ indices. The algorithm itself is simple enough to memorize, too. To destroy the internal state, just shuffle the notes (and cut them up and burn them if you want to be sure).
The hard part would be key setup. The usual way of keying RC4 is not only laborious to do by hand (it's more or less equivalent to 256 encryption steps), but doesn't really shuffle the state all that well. The standard remedy for that is to discard the initial part of the output, which makes for even more work for our would-be computerless cryptographer. If you can safely carry around the state as a stack of notes, you can do it once and then just keep churning out more of the same keystream for each message, but if not, some alternative key setup mechanism would be highly recommended.
Also, there's always [Solitaire](http://en.wikipedia.org/wiki/Solitaire_%28cipher%29), although it needs a deck of cards and has significantly [worse biases](http://www.ciphergoth.org/crypto/solitaire/) than RC4. In fact, the design of Solitaire bears a strong resemblance to RC4, and was almost certainly inspired by it. Given the known weaknesses of Solitaire, if you want a hand cipher using playing cards it might be better to go with RC4-52 (i.e. standard RC4, only with 52 instead of 256 elements in the state array), although I don't know if anyone's done any serious cryptanalysis of that. (It's almost certainly weaker than normal RC4, but I'm not sure how much weaker. Probably still better than Solitaire, though.) | I can think of 2 cryptographic systems.
One that can be done with a deck of cards is a scheme called [Pontifex](http://en.wikipedia.org/wiki/Solitaire_%28cipher%29) (aka solitaire) that was developed for the book [Cryptonomicon](http://rads.stackoverflow.com/amzn/click/0380973464). Some more technical details and example of it in use at [Bruce Schneier's website](http://www.schneier.com/solitaire.html). Although it should be noted that some [weaknesses](http://www.ciphergoth.org/crypto/solitaire/) have been discovered in Pontifex .
Another one, although this one involves lots of paper, is a [straddling checkerboard](http://en.wikipedia.org/wiki/Straddling_checkerboard) which formed the basis of the system used by Soviet spies in the US (the full system was more complicated and called [VIC](http://en.wikipedia.org/wiki/VIC_cipher)). The spy using the system would only need to remember a phrase and a date. From these 2 items, one could [generate the checkerboard](http://practicalcryptography.com/ciphers/straddle-checkerboard-cipher/). It takes a simple set of rules to encode a message. The book [Kahn on Codes](http://rads.stackoverflow.com/amzn/click/0025606409) has a couple of pages where they explain how messages were encrypted with this scheme. Several spies were detected by finding intermediate work in trash. |
844 | I, myself, do not plan on getting into a situation where I would be unable to use a computer in order to communicate securely. However, I can think of many practical situations in which mental cryptography would be useful.
Is there a secure cryptosystem that is simple enough to be performed mentally?
Clearly, one of the challenges is remembering >100 bits of entropy to leverage, but I am assuming that this can be done beforehand.
How susceptible would any such system be to side channel attacks (like trash rummaging)? | 2011/09/28 | [
"https://crypto.stackexchange.com/questions/844",
"https://crypto.stackexchange.com",
"https://crypto.stackexchange.com/users/99/"
] | I can think of 2 cryptographic systems.
One that can be done with a deck of cards is a scheme called [Pontifex](http://en.wikipedia.org/wiki/Solitaire_%28cipher%29) (aka solitaire) that was developed for the book [Cryptonomicon](http://rads.stackoverflow.com/amzn/click/0380973464). Some more technical details and example of it in use at [Bruce Schneier's website](http://www.schneier.com/solitaire.html). Although it should be noted that some [weaknesses](http://www.ciphergoth.org/crypto/solitaire/) have been discovered in Pontifex .
Another one, although this one involves lots of paper, is a [straddling checkerboard](http://en.wikipedia.org/wiki/Straddling_checkerboard) which formed the basis of the system used by Soviet spies in the US (the full system was more complicated and called [VIC](http://en.wikipedia.org/wiki/VIC_cipher)). The spy using the system would only need to remember a phrase and a date. From these 2 items, one could [generate the checkerboard](http://practicalcryptography.com/ciphers/straddle-checkerboard-cipher/). It takes a simple set of rules to encode a message. The book [Kahn on Codes](http://rads.stackoverflow.com/amzn/click/0025606409) has a couple of pages where they explain how messages were encrypted with this scheme. Several spies were detected by finding intermediate work in trash. | A [self-shrinking LFSR](http://en.wikipedia.org/wiki/Self-shrinking_generator) can be implemented using nothing but a couple of decks of cards.
* 0 equals face down
* 1 equals face down.
You can then split the deck at each tap point and XOR the items in your head. After the XOR is done, you move the cards on to next split deck; this has the effect of shifting the register.
Key set-up is easy, each iteration is extremely easy however it would be painfully slow to operate.
Given a sufficiently long and dense polynomial, it is however, secure. |
844 | I, myself, do not plan on getting into a situation where I would be unable to use a computer in order to communicate securely. However, I can think of many practical situations in which mental cryptography would be useful.
Is there a secure cryptosystem that is simple enough to be performed mentally?
Clearly, one of the challenges is remembering >100 bits of entropy to leverage, but I am assuming that this can be done beforehand.
How susceptible would any such system be to side channel attacks (like trash rummaging)? | 2011/09/28 | [
"https://crypto.stackexchange.com/questions/844",
"https://crypto.stackexchange.com",
"https://crypto.stackexchange.com/users/99/"
] | I can think of 2 cryptographic systems.
One that can be done with a deck of cards is a scheme called [Pontifex](http://en.wikipedia.org/wiki/Solitaire_%28cipher%29) (aka solitaire) that was developed for the book [Cryptonomicon](http://rads.stackoverflow.com/amzn/click/0380973464). Some more technical details and example of it in use at [Bruce Schneier's website](http://www.schneier.com/solitaire.html). Although it should be noted that some [weaknesses](http://www.ciphergoth.org/crypto/solitaire/) have been discovered in Pontifex .
Another one, although this one involves lots of paper, is a [straddling checkerboard](http://en.wikipedia.org/wiki/Straddling_checkerboard) which formed the basis of the system used by Soviet spies in the US (the full system was more complicated and called [VIC](http://en.wikipedia.org/wiki/VIC_cipher)). The spy using the system would only need to remember a phrase and a date. From these 2 items, one could [generate the checkerboard](http://practicalcryptography.com/ciphers/straddle-checkerboard-cipher/). It takes a simple set of rules to encode a message. The book [Kahn on Codes](http://rads.stackoverflow.com/amzn/click/0025606409) has a couple of pages where they explain how messages were encrypted with this scheme. Several spies were detected by finding intermediate work in trash. | People have long used code systems for this purpose, instead of ciphers. With a code, you pre-establish entire messages. "John has a long mustache" might mean "sabotage the phone lines". Or the number of suits on the dry cleaning order might indicate the size of the enemy force.
Sometimes the codes are awkward, and give away the existence of the code without giving up the meaning. A telegraph agent once received a reply to a message that asked "is mother 'dead' or 'deceased'?" which was a pretty pointless clarification to ask for unless there was a hidden meaning.
Used once, they're as secure as the endpoints who protected them. Used multiple times, they leave a distinctive pattern that can be decoded. |
844 | I, myself, do not plan on getting into a situation where I would be unable to use a computer in order to communicate securely. However, I can think of many practical situations in which mental cryptography would be useful.
Is there a secure cryptosystem that is simple enough to be performed mentally?
Clearly, one of the challenges is remembering >100 bits of entropy to leverage, but I am assuming that this can be done beforehand.
How susceptible would any such system be to side channel attacks (like trash rummaging)? | 2011/09/28 | [
"https://crypto.stackexchange.com/questions/844",
"https://crypto.stackexchange.com",
"https://crypto.stackexchange.com/users/99/"
] | *(Converted to answer from a comment.)*
If pen and paper are permitted, one could probably carry out the [RC4](http://en.wikipedia.org/wiki/RC4) algorithm fairly easily using 256 numbered pieces of paper (small post-it notes might be ideal, since they'd be harder to move by accident) arranged in a 16 by 16 grid (I'd suggest numbering the notes in hex for easier indexing), with two coins or something to keep track of the $i$ and $j$ indices. The algorithm itself is simple enough to memorize, too. To destroy the internal state, just shuffle the notes (and cut them up and burn them if you want to be sure).
The hard part would be key setup. The usual way of keying RC4 is not only laborious to do by hand (it's more or less equivalent to 256 encryption steps), but doesn't really shuffle the state all that well. The standard remedy for that is to discard the initial part of the output, which makes for even more work for our would-be computerless cryptographer. If you can safely carry around the state as a stack of notes, you can do it once and then just keep churning out more of the same keystream for each message, but if not, some alternative key setup mechanism would be highly recommended.
Also, there's always [Solitaire](http://en.wikipedia.org/wiki/Solitaire_%28cipher%29), although it needs a deck of cards and has significantly [worse biases](http://www.ciphergoth.org/crypto/solitaire/) than RC4. In fact, the design of Solitaire bears a strong resemblance to RC4, and was almost certainly inspired by it. Given the known weaknesses of Solitaire, if you want a hand cipher using playing cards it might be better to go with RC4-52 (i.e. standard RC4, only with 52 instead of 256 elements in the state array), although I don't know if anyone's done any serious cryptanalysis of that. (It's almost certainly weaker than normal RC4, but I'm not sure how much weaker. Probably still better than Solitaire, though.) | **this doesn't suit the entropy part**
the old & basic encoding mechanisms like Caesar (easy) or Substitution (concentrate) Cipher could be done mentally too.
if you simply want to speak or signal an encoded message to few in public place.
You could do "gibberish talk", which has several ways..... with basic outline as
* decide on peices of 'gibberish' (some jumbled up letters) and their place-holders in the sentence (like spaces, fullstop); you can even choose multiple gibberish for same placeholder and use randomly any of it for more Confusion
* decide on break-point length for actual words, after which the gibberish has to be inserted..... you can even have a series of queued break-points if you can process it |
844 | I, myself, do not plan on getting into a situation where I would be unable to use a computer in order to communicate securely. However, I can think of many practical situations in which mental cryptography would be useful.
Is there a secure cryptosystem that is simple enough to be performed mentally?
Clearly, one of the challenges is remembering >100 bits of entropy to leverage, but I am assuming that this can be done beforehand.
How susceptible would any such system be to side channel attacks (like trash rummaging)? | 2011/09/28 | [
"https://crypto.stackexchange.com/questions/844",
"https://crypto.stackexchange.com",
"https://crypto.stackexchange.com/users/99/"
] | *(Converted to answer from a comment.)*
If pen and paper are permitted, one could probably carry out the [RC4](http://en.wikipedia.org/wiki/RC4) algorithm fairly easily using 256 numbered pieces of paper (small post-it notes might be ideal, since they'd be harder to move by accident) arranged in a 16 by 16 grid (I'd suggest numbering the notes in hex for easier indexing), with two coins or something to keep track of the $i$ and $j$ indices. The algorithm itself is simple enough to memorize, too. To destroy the internal state, just shuffle the notes (and cut them up and burn them if you want to be sure).
The hard part would be key setup. The usual way of keying RC4 is not only laborious to do by hand (it's more or less equivalent to 256 encryption steps), but doesn't really shuffle the state all that well. The standard remedy for that is to discard the initial part of the output, which makes for even more work for our would-be computerless cryptographer. If you can safely carry around the state as a stack of notes, you can do it once and then just keep churning out more of the same keystream for each message, but if not, some alternative key setup mechanism would be highly recommended.
Also, there's always [Solitaire](http://en.wikipedia.org/wiki/Solitaire_%28cipher%29), although it needs a deck of cards and has significantly [worse biases](http://www.ciphergoth.org/crypto/solitaire/) than RC4. In fact, the design of Solitaire bears a strong resemblance to RC4, and was almost certainly inspired by it. Given the known weaknesses of Solitaire, if you want a hand cipher using playing cards it might be better to go with RC4-52 (i.e. standard RC4, only with 52 instead of 256 elements in the state array), although I don't know if anyone's done any serious cryptanalysis of that. (It's almost certainly weaker than normal RC4, but I'm not sure how much weaker. Probably still better than Solitaire, though.) | A [self-shrinking LFSR](http://en.wikipedia.org/wiki/Self-shrinking_generator) can be implemented using nothing but a couple of decks of cards.
* 0 equals face down
* 1 equals face down.
You can then split the deck at each tap point and XOR the items in your head. After the XOR is done, you move the cards on to next split deck; this has the effect of shifting the register.
Key set-up is easy, each iteration is extremely easy however it would be painfully slow to operate.
Given a sufficiently long and dense polynomial, it is however, secure. |
844 | I, myself, do not plan on getting into a situation where I would be unable to use a computer in order to communicate securely. However, I can think of many practical situations in which mental cryptography would be useful.
Is there a secure cryptosystem that is simple enough to be performed mentally?
Clearly, one of the challenges is remembering >100 bits of entropy to leverage, but I am assuming that this can be done beforehand.
How susceptible would any such system be to side channel attacks (like trash rummaging)? | 2011/09/28 | [
"https://crypto.stackexchange.com/questions/844",
"https://crypto.stackexchange.com",
"https://crypto.stackexchange.com/users/99/"
] | *(Converted to answer from a comment.)*
If pen and paper are permitted, one could probably carry out the [RC4](http://en.wikipedia.org/wiki/RC4) algorithm fairly easily using 256 numbered pieces of paper (small post-it notes might be ideal, since they'd be harder to move by accident) arranged in a 16 by 16 grid (I'd suggest numbering the notes in hex for easier indexing), with two coins or something to keep track of the $i$ and $j$ indices. The algorithm itself is simple enough to memorize, too. To destroy the internal state, just shuffle the notes (and cut them up and burn them if you want to be sure).
The hard part would be key setup. The usual way of keying RC4 is not only laborious to do by hand (it's more or less equivalent to 256 encryption steps), but doesn't really shuffle the state all that well. The standard remedy for that is to discard the initial part of the output, which makes for even more work for our would-be computerless cryptographer. If you can safely carry around the state as a stack of notes, you can do it once and then just keep churning out more of the same keystream for each message, but if not, some alternative key setup mechanism would be highly recommended.
Also, there's always [Solitaire](http://en.wikipedia.org/wiki/Solitaire_%28cipher%29), although it needs a deck of cards and has significantly [worse biases](http://www.ciphergoth.org/crypto/solitaire/) than RC4. In fact, the design of Solitaire bears a strong resemblance to RC4, and was almost certainly inspired by it. Given the known weaknesses of Solitaire, if you want a hand cipher using playing cards it might be better to go with RC4-52 (i.e. standard RC4, only with 52 instead of 256 elements in the state array), although I don't know if anyone's done any serious cryptanalysis of that. (It's almost certainly weaker than normal RC4, but I'm not sure how much weaker. Probably still better than Solitaire, though.) | People have long used code systems for this purpose, instead of ciphers. With a code, you pre-establish entire messages. "John has a long mustache" might mean "sabotage the phone lines". Or the number of suits on the dry cleaning order might indicate the size of the enemy force.
Sometimes the codes are awkward, and give away the existence of the code without giving up the meaning. A telegraph agent once received a reply to a message that asked "is mother 'dead' or 'deceased'?" which was a pretty pointless clarification to ask for unless there was a hidden meaning.
Used once, they're as secure as the endpoints who protected them. Used multiple times, they leave a distinctive pattern that can be decoded. |
98,583 | I'm working out a concept for a story where there's a gas giant with at least 6 habitable moons (willing to use teraforming tech to get over any big hurdles) and the planet itself has a ring of rocks and minerals around it, like Saturn but closer to a sun. Are there other concerns to have (gravity, for example, if the moons are too small)?
Thanks! | 2017/11/23 | [
"https://worldbuilding.stackexchange.com/questions/98583",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/45021/"
] | Things float because they are (on average) less dense than the medium they float in.
Any other means of staying on top is not floating but flying or hovering, which requires energy to counter gravity.
So, the simple, albeit fairly impossible, Answer is that the air your islands float in is extremely dense.
I assume you want some kind of breathable atmosphere on the upper side of your islands.
That would mean a two-phased atmosphere: your incredibly dense floating-gas below, and above that your regular breathable and very much non-dense gas above that.
That means the density cannot be achieved by pressure (which would eventually liquefy the gas anyway), because that would apply to the air above too, but it must be achieved by the molecule mass. Something like gaseous Uranium.
This is possible, but it would be a bit on the warm side.
At least 4131°C, to be precise.
Still cooler than the surface of the sun (approx. 6000°C), but still...
At these temperatures it is no longer relevant if an atmosphere was theoretically breathable, because the people who could report breathability have long turned gaseous themselves.
Or, to put it short:
It can't be done.
EDIT
Let's take a closer look at gases.
Under standard conditions (approx: 1 bar pressure, 20°C), WF6 (Tungsten hexafluoride) is the densest gas, with a density of 12.4g/l.
The density of water is 1000g/l. The density of humans is somewhere in the same ballpark (depending on body fat, the volume of air currently in the lungs, ...).
Rock has densities between 1200g/l and 3300g/l, depending on it's composition.
As you can see, your island is some two orders of magnitude more dense than any conceivable gas.
They could float on liquids, though, if you tune things just right. | In Weiss and Hickman's "Deaths Gate Cycle", they had a coral like creature that built calcite foam shells around hydrogen bubbles, and then a lot of handwavium to avoid questions like "where did the calcium originate? " and is this mathematically feasible? " |
98,583 | I'm working out a concept for a story where there's a gas giant with at least 6 habitable moons (willing to use teraforming tech to get over any big hurdles) and the planet itself has a ring of rocks and minerals around it, like Saturn but closer to a sun. Are there other concerns to have (gravity, for example, if the moons are too small)?
Thanks! | 2017/11/23 | [
"https://worldbuilding.stackexchange.com/questions/98583",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/45021/"
] | I can do something close, but yet entirely possible within our known sciences.
In 1984, Larry Niven published a book called [The Integral Trees](https://en.wikipedia.org/wiki/The_Integral_Trees). The setting is a vast gas torus, around a neutron star. The [gas torus](https://en.wikipedia.org/wiki/Gas_torus) is a known object, and Niven did the math to make the setting scientifically accurate. This gas torus was formed by a gas giant's atmosphere being sucked into orbit around the neutron star.
The gas torus was located 26,000 kilometers away from the neutron star, but, after a detailed examination of the numbers- distances, the neutron star's size, orbit time, etc, it was found that it was incorrect. But by adding a [zero](http://forum.mongoosepublishing.com/viewtopic.php?t=105725) to the kilometers, it was corrected. So, Niven just dropped a zero, and removed public interest in this fantastical object.
So we have a place for floating islands, but no floating islands. And that's where [Jupiter's Trojans](https://en.wikipedia.org/wiki/Jupiter_trojan) come in. They are two large clusters of asteroids at Jupiter's L4 and L5 points. These asteroids are numerous, and there are estimated to be around 600,000 asteroids in between 2km and 1km in the L4 group. In the L5 group, there are over 1 million asteroids above 1km in size.
Now, we just put these two things together. It is not a world in the strictest sense, but no world seldom is. The main problem is the absence of gravity, but we don't know what happens when someone is born in zero gravity. That means you can make something up for yourself. There is a miniscule amount of gravity on these asteroids, but it's so negligible it could just be called zero gravity. Plants should still be able to grow downwards on their own. They should be extremely tall, but I cannot find anything about that. This should be enough for your world, as anything else would be not be your work. | In Weiss and Hickman's "Deaths Gate Cycle", they had a coral like creature that built calcite foam shells around hydrogen bubbles, and then a lot of handwavium to avoid questions like "where did the calcium originate? " and is this mathematically feasible? " |
98,583 | I'm working out a concept for a story where there's a gas giant with at least 6 habitable moons (willing to use teraforming tech to get over any big hurdles) and the planet itself has a ring of rocks and minerals around it, like Saturn but closer to a sun. Are there other concerns to have (gravity, for example, if the moons are too small)?
Thanks! | 2017/11/23 | [
"https://worldbuilding.stackexchange.com/questions/98583",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/45021/"
] | Things float because they are (on average) less dense than the medium they float in.
Any other means of staying on top is not floating but flying or hovering, which requires energy to counter gravity.
So, the simple, albeit fairly impossible, Answer is that the air your islands float in is extremely dense.
I assume you want some kind of breathable atmosphere on the upper side of your islands.
That would mean a two-phased atmosphere: your incredibly dense floating-gas below, and above that your regular breathable and very much non-dense gas above that.
That means the density cannot be achieved by pressure (which would eventually liquefy the gas anyway), because that would apply to the air above too, but it must be achieved by the molecule mass. Something like gaseous Uranium.
This is possible, but it would be a bit on the warm side.
At least 4131°C, to be precise.
Still cooler than the surface of the sun (approx. 6000°C), but still...
At these temperatures it is no longer relevant if an atmosphere was theoretically breathable, because the people who could report breathability have long turned gaseous themselves.
Or, to put it short:
It can't be done.
EDIT
Let's take a closer look at gases.
Under standard conditions (approx: 1 bar pressure, 20°C), WF6 (Tungsten hexafluoride) is the densest gas, with a density of 12.4g/l.
The density of water is 1000g/l. The density of humans is somewhere in the same ballpark (depending on body fat, the volume of air currently in the lungs, ...).
Rock has densities between 1200g/l and 3300g/l, depending on it's composition.
As you can see, your island is some two orders of magnitude more dense than any conceivable gas.
They could float on liquids, though, if you tune things just right. | Look into something like Bioshock Infinites floating city of Columbia. In the world your building the core of the world can be a super powerful magnet, and the bottom of your 'islands' can be made out of some strange superconductor that doesn't rely on cold.
<https://www.quora.com/What-are-the-supposed-physics-behind-the-floating-city-Columbia-in-Bioshock-Infinite> |
98,583 | I'm working out a concept for a story where there's a gas giant with at least 6 habitable moons (willing to use teraforming tech to get over any big hurdles) and the planet itself has a ring of rocks and minerals around it, like Saturn but closer to a sun. Are there other concerns to have (gravity, for example, if the moons are too small)?
Thanks! | 2017/11/23 | [
"https://worldbuilding.stackexchange.com/questions/98583",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/45021/"
] | I can do something close, but yet entirely possible within our known sciences.
In 1984, Larry Niven published a book called [The Integral Trees](https://en.wikipedia.org/wiki/The_Integral_Trees). The setting is a vast gas torus, around a neutron star. The [gas torus](https://en.wikipedia.org/wiki/Gas_torus) is a known object, and Niven did the math to make the setting scientifically accurate. This gas torus was formed by a gas giant's atmosphere being sucked into orbit around the neutron star.
The gas torus was located 26,000 kilometers away from the neutron star, but, after a detailed examination of the numbers- distances, the neutron star's size, orbit time, etc, it was found that it was incorrect. But by adding a [zero](http://forum.mongoosepublishing.com/viewtopic.php?t=105725) to the kilometers, it was corrected. So, Niven just dropped a zero, and removed public interest in this fantastical object.
So we have a place for floating islands, but no floating islands. And that's where [Jupiter's Trojans](https://en.wikipedia.org/wiki/Jupiter_trojan) come in. They are two large clusters of asteroids at Jupiter's L4 and L5 points. These asteroids are numerous, and there are estimated to be around 600,000 asteroids in between 2km and 1km in the L4 group. In the L5 group, there are over 1 million asteroids above 1km in size.
Now, we just put these two things together. It is not a world in the strictest sense, but no world seldom is. The main problem is the absence of gravity, but we don't know what happens when someone is born in zero gravity. That means you can make something up for yourself. There is a miniscule amount of gravity on these asteroids, but it's so negligible it could just be called zero gravity. Plants should still be able to grow downwards on their own. They should be extremely tall, but I cannot find anything about that. This should be enough for your world, as anything else would be not be your work. | Look into something like Bioshock Infinites floating city of Columbia. In the world your building the core of the world can be a super powerful magnet, and the bottom of your 'islands' can be made out of some strange superconductor that doesn't rely on cold.
<https://www.quora.com/What-are-the-supposed-physics-behind-the-floating-city-Columbia-in-Bioshock-Infinite> |
1,194 | I have an application I am designing and it's in a pretty functional state at the moment. But the database I am using has 1000's of items and is constantly changing and growing. The application of certain data items may vary depending on the user constraints as well (product interfacing with, user levels, etc..). I have tried to make this layout as flexible as possible to the point where the database basically controls the GUI layouts.
I would like to make this GUI as clean and easy to use as possible without having to redo everything when something changes. So basically....
What are some good approaches to making a dynamic/scalable GUI? If such a thing is possible.
EDIT- Good stuff so far, since you guys want to see what I am talking about, here is an idea. I have a SQLite database that contains fields for groupings and display formats and lots of other things which are parsed into a dynamic config tree on the left, and the tabs and groupboxes are all dynamicly generated from some creative SQL. There is a lot of data, so something generic isn't exactly a bad thing, since the complicated stuff will be hidden from less advanced users anyways. If the database is setup properly this could work very well I think.
I have a wizard as well which needs some work, but will make alot of this easier to handle since it isn't touched very often. But this all needs to be accessible without going through a wizard so someone can setup a custom configuration. | 2010/09/01 | [
"https://ux.stackexchange.com/questions/1194",
"https://ux.stackexchange.com",
"https://ux.stackexchange.com/users/1010/"
] | I know what you're thinking when you say "as flexible as possible to the point where the database basically controls the GUI layouts", but this is a warning sign: you're going to end up with an app that is generic at the cost of usability. I see this a lot with "programmer UIs", where developers have extended their database and object oriented architecture into the user interface. Unfortunately, you often end up with a user interface designed for the programmer instead of the end user.
My advice would be to forget about looking for the ideal super-flexible, dynamic, scalable GUI and instead start identifying patterns of use you can design against. I'll be able to help you out more in this area if you provide more details (such as the domain you're designing for, examples, mockups, etc).
---
**Edit**: So, going by the screenshot you've added, it looks like the complexity of the database is spilling over into the UI. What I'm seeing here is literally a huge dashboard full of choices - I feel like I'm in Star Trek with the panels full of glowing buttons! Let me give you a quick first impression from myself as an outsider:
It looks like we're configuring something. By choosing an item to configure on the left, the right area updates with input fields corresponding to parameters that can be changed? But those input fields are themselves located within a tab, and there are so many tabs they're flowing off the screenshot towards the right. Also, the label for each field is cryptic at best: "Mx Ld Fct". It's nice that when hovering, you see a label that explains more, but do I really want to hover over different items just to find out they're not what I'm looking for? It's like an easter egg hunt. Further, it's not clear to me what "tools" does on the lower left. Both panes on the left appear to be maximizable, though I'm not sure to what effect.
I can sort of see where you're going with this, but I have to recommend against it. It's hard to explain why if you haven't gone through this process before. The best advice I can give is to grab some people who'll be using this right now and get them to use the app. Sit with them and ask them to perform some common tasks. Without commenting, just watch what they do and write down on a notepad what your thoughts are. You'll learn a lot. Try and do this every week, with the whole dev team. | I have some points to consider:
* Make sure long strings don't break the layout. Naturally I'm talking about the data itself, but the surrounding UI might also suffer. For example, consider a command bar with buttons. When the text on the buttons is translated, they might grow large and overflow the bar.
* Make the UI "lazy load" some of the info and consider using pagination. For example, it might take too long to load at once thousands of items - make sure the UI doesn't look frozen or broken while it loads, or that you load one page and then load the rest while the user can also start interacting with the UI.
Otherwise I agree with Rahul that we need some more details to get specific. |
560,347 | I have added a menu item in edit control block(ECB) in document library(using following msdn article <http://msdn.microsoft.com/en-us/library/ms473643.aspx>)
Now i found that the custom action(menu Item) in ECB is displayed for both document item and document folder. So how to apply custom action only for document item? | 2009/02/18 | [
"https://Stackoverflow.com/questions/560347",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/67349/"
] | In general there should be disassemblers available for executables, regardless how they have been created (gcc, proC, handwritten, etc.) but decompiling an optimized binary most probably leads to unreadable or source.
Also, Pro C/C++ is not directly a compiler but outputs C/C++ code which then in turn is compiled by a platform native compiler (gcc, xlc, vc++, etc.).
Furthermore the generated code is often not directly compilable again without lots of manual corrections.
If you still want to try your luck, have a look at this list of [x86 disassemblers](http://en.wikibooks.org/wiki/X86_Disassembly/Disassemblers_and_Decompilers) for a start. | Try [PE Explorer Disassembler](http://www.heaventools.com/PE_Explorer_disassembler.htm), a very decent disassembler for 32-bit executable files. |
31,409 | I went to a concert the other day and noticed that the bows (violins, cellos, violas) were all coordinated as the orchestra played. It looks neat, but is there an audible difference if they're not in sync bow-wise? If there's a difference, is it more or less obvious depending on the player/instrument? | 2015/04/04 | [
"https://music.stackexchange.com/questions/31409",
"https://music.stackexchange.com",
"https://music.stackexchange.com/users/19767/"
] | It's easiest for the player to put downward pressure on the instrument string when the bow is making contact with the string near the end that the player holds (the 'frog' end). This means that on a downstroke (extending the arm), it's easier to start the bowing action with firmer pressure.
Players tend to take advantage of this by using downstrokes to play strong beats, and upstrokes to play weak beats. Obviously it may not be possible to maintain this rule strictly, depending on the rhythm of the passage being played; if not, players will have to compensate by applying more pressure on the upstrokes.
Another consideration is that if a section indicates repeated strokes in the same direction, the bow will have to be lifted between each stroke, leading to shorter strokes even if rests aren't indicated between the notes.
In theory it's also possible that the direction of the horsehair makes a difference - but although [some think so](http://www.atelierdarcheterie.com/blog/blog_eng/Articoli/Replacingbowhair.html), Others don't ([1](http://russellhopperviolinmaking.blogspot.co.uk/2011/02/violin-bow-maintenance-and-myths.html)) ([2](http://blog.feinviolins.com/2011/06/violin-bow-hair-having-good-hair-day.html)), so it's possible that bows aren't always re-haired in the same direction anyway. If there is any effect, it's likely to be very small as the [scales on the hair are very tiny](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.124.5065&rep=rep1&type=pdf) (p28).
To your question, then : *Can one tell by ear* ? The answer is probably that it depends how skilled at compensating for pressure differences between down and up strokes the player is, and of course whether or not they are actually trying to compensate. In most situations though, a player would use the natural difference between an up and downstroke to their advantage, rather than try to fight against it. | Yes, it is obvious. A note played "up-bow" sounds discernably different than a note played "down-bow". A string player can also play a series of notes continuously using the same long bowing motion, or the player can "saw" back-and-forth, reversing direction between each note. There are several other kinds of bowing articulation techniques as well. They all create different sounds and effects.
Bowing direction, up or down, is often written into the sheet music by the composer, as a symbol above each note.
String sections in orchestras can spend a lot of time in rehearsal on planning out and coordinating bowing motions. Earlier music, such as from the Baroque era, generally didn't include up-and-down bowing symbols written into the sheet music. In that case, in the present day, the members of the string section, usually led by the concertmaster, will devise and agree upon precise bowing directions for certain notes in rehearsal, pencil in bowing markings on their sheet music, and practice the agreed-upon articulations for each note. This shapes the phrasing and the rhythm of the parts being played. |
31,409 | I went to a concert the other day and noticed that the bows (violins, cellos, violas) were all coordinated as the orchestra played. It looks neat, but is there an audible difference if they're not in sync bow-wise? If there's a difference, is it more or less obvious depending on the player/instrument? | 2015/04/04 | [
"https://music.stackexchange.com/questions/31409",
"https://music.stackexchange.com",
"https://music.stackexchange.com/users/19767/"
] | Yes, it is obvious. A note played "up-bow" sounds discernably different than a note played "down-bow". A string player can also play a series of notes continuously using the same long bowing motion, or the player can "saw" back-and-forth, reversing direction between each note. There are several other kinds of bowing articulation techniques as well. They all create different sounds and effects.
Bowing direction, up or down, is often written into the sheet music by the composer, as a symbol above each note.
String sections in orchestras can spend a lot of time in rehearsal on planning out and coordinating bowing motions. Earlier music, such as from the Baroque era, generally didn't include up-and-down bowing symbols written into the sheet music. In that case, in the present day, the members of the string section, usually led by the concertmaster, will devise and agree upon precise bowing directions for certain notes in rehearsal, pencil in bowing markings on their sheet music, and practice the agreed-upon articulations for each note. This shapes the phrasing and the rhythm of the parts being played. | Someone above made the comment that down-bows are pulling the bow and up-bows are pushing the bow. This may be true, but it's not my understanding. Clearly, down-bows are pulling the bow over the string. And I think the Russian style is for the hand to be somewhat rigid on the bow, so up-bows are indeed pushing on the string. But the in the Franco-Belgian style, both directions are really pulling on the bow. On a down bow you keep your hand loose, and change the fingers so that the hand leads the fingers. This is pretty obvious. To do this on an up-bow, you make your hand loose, so that the hand, again, leads the fingers. If you ever have the chance to see a violinst play long, whole-bow notes very legato, you will see that their fingers change from knuckles-up, tips down on the up-bows and knuckles-down, fingers up on the down-bows. This is the reason. Also, I think a loose hand helps mediate the weight of the hand and bow on the string, and helps find the right bow speed and weight combination.
So, why do I think up bows sound different from down bows? I think it's because the up-bows start with the tip and the down bows start with the handle end, which we call the frog. The tip is lighter than the frog, so notes on the tip are not as loud as those played on the frog. Notes played on the frog may have so much weight that they squash the string and make it scratch.
Fiddling is not just fiddling around, you know.
Of course, I could be completely wrong about this. |
31,409 | I went to a concert the other day and noticed that the bows (violins, cellos, violas) were all coordinated as the orchestra played. It looks neat, but is there an audible difference if they're not in sync bow-wise? If there's a difference, is it more or less obvious depending on the player/instrument? | 2015/04/04 | [
"https://music.stackexchange.com/questions/31409",
"https://music.stackexchange.com",
"https://music.stackexchange.com/users/19767/"
] | It's easiest for the player to put downward pressure on the instrument string when the bow is making contact with the string near the end that the player holds (the 'frog' end). This means that on a downstroke (extending the arm), it's easier to start the bowing action with firmer pressure.
Players tend to take advantage of this by using downstrokes to play strong beats, and upstrokes to play weak beats. Obviously it may not be possible to maintain this rule strictly, depending on the rhythm of the passage being played; if not, players will have to compensate by applying more pressure on the upstrokes.
Another consideration is that if a section indicates repeated strokes in the same direction, the bow will have to be lifted between each stroke, leading to shorter strokes even if rests aren't indicated between the notes.
In theory it's also possible that the direction of the horsehair makes a difference - but although [some think so](http://www.atelierdarcheterie.com/blog/blog_eng/Articoli/Replacingbowhair.html), Others don't ([1](http://russellhopperviolinmaking.blogspot.co.uk/2011/02/violin-bow-maintenance-and-myths.html)) ([2](http://blog.feinviolins.com/2011/06/violin-bow-hair-having-good-hair-day.html)), so it's possible that bows aren't always re-haired in the same direction anyway. If there is any effect, it's likely to be very small as the [scales on the hair are very tiny](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.124.5065&rep=rep1&type=pdf) (p28).
To your question, then : *Can one tell by ear* ? The answer is probably that it depends how skilled at compensating for pressure differences between down and up strokes the player is, and of course whether or not they are actually trying to compensate. In most situations though, a player would use the natural difference between an up and downstroke to their advantage, rather than try to fight against it. | Someone above made the comment that down-bows are pulling the bow and up-bows are pushing the bow. This may be true, but it's not my understanding. Clearly, down-bows are pulling the bow over the string. And I think the Russian style is for the hand to be somewhat rigid on the bow, so up-bows are indeed pushing on the string. But the in the Franco-Belgian style, both directions are really pulling on the bow. On a down bow you keep your hand loose, and change the fingers so that the hand leads the fingers. This is pretty obvious. To do this on an up-bow, you make your hand loose, so that the hand, again, leads the fingers. If you ever have the chance to see a violinst play long, whole-bow notes very legato, you will see that their fingers change from knuckles-up, tips down on the up-bows and knuckles-down, fingers up on the down-bows. This is the reason. Also, I think a loose hand helps mediate the weight of the hand and bow on the string, and helps find the right bow speed and weight combination.
So, why do I think up bows sound different from down bows? I think it's because the up-bows start with the tip and the down bows start with the handle end, which we call the frog. The tip is lighter than the frog, so notes on the tip are not as loud as those played on the frog. Notes played on the frog may have so much weight that they squash the string and make it scratch.
Fiddling is not just fiddling around, you know.
Of course, I could be completely wrong about this. |
44,641,511 | I am working an existing app on the App Store. The only thing I have to do is update the splash screen and icon.
However, when I try to upload iTunes Store I get the error:
"Invalid code signing entitlements - specifically value 'dns-proxy' for key 'com.apple.developer.networking.networkextension' in 'Payload/AppName.app/AppName' is not supported."
I'm new to building IOS apps - can someone please point in the right direction to fix this? | 2017/06/19 | [
"https://Stackoverflow.com/questions/44641511",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/8185563/"
] | I solved this problem by adding the Network Extensions capability, which seems to only appear in Xcode 8.3.3, for all related targets in the Capabilities Tab. | I found the solution.
1. Go to the You Apps on Apple Developer.
2. Go to your Idetifiers (App IDS) and uncheck Network Extensions.
3. Try again to upload. |
44,641,511 | I am working an existing app on the App Store. The only thing I have to do is update the splash screen and icon.
However, when I try to upload iTunes Store I get the error:
"Invalid code signing entitlements - specifically value 'dns-proxy' for key 'com.apple.developer.networking.networkextension' in 'Payload/AppName.app/AppName' is not supported."
I'm new to building IOS apps - can someone please point in the right direction to fix this? | 2017/06/19 | [
"https://Stackoverflow.com/questions/44641511",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/8185563/"
] | I solved this problem by adding the Network Extensions capability, which seems to only appear in Xcode 8.3.3, for all related targets in the Capabilities Tab. | I guess you need to update your developer certificate in your XCode and patch it again.Try to validate it before you upload it. |
128,580 | When I wind it back there is a click noise once i let go of the winder and then i cant press the shutter release so i have to wind again which advances it, I dont have film in it but it seems if i did it could waste some shots which I do not want | 2022/02/11 | [
"https://photo.stackexchange.com/questions/128580",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/104859/"
] | >
> I bought a Canon IXUS 255 HS eight years ago... the battery lasts a ridiculously short time.
>
>
>
After eight years, it may be time to replace the battery, especially if you haven't kept it charged to 40-60% during that time.
>
> Especially if I'm recording video.
>
>
>
Most cameras have a video recording time limit of about half an hour for tax classification purposes. If your primary objective is to record video, use a camcorder.
>
> Within half an hour, it's basically drained. If I'm lucky, it might last a couple of hours.
>
>
>
That's a big difference. Use a stopwatch to obtain more precise timing.
>
> If I were to finally go on vacation...
>
>
>
Consider carrying a **spare battery**.
>
> ... some sort of much physically larger thing that fits into the battery slot but also extends way beyond it, to enable a full 24 hours of video recording and photo-taking... Does such a thing exist for my camera? Does it exist for any camera?
>
>
>
They're known as **dummy batteries** or **DC couplers**. One end fits into the battery slot of your camera. The other end attaches to an AC adapter or battery pack.
Many camcorders have extended batteries. These are possible because of the position of the battery at the back of the camcorder.
Flagship DSLRs and mirrorless cameras often have **battery grips** available. Runtime is unlikely to extend to 24 hours though. | You'll probably need to use a [third party manufacturer](https://www.bhphotovideo.com/c/product/836622-REG/watson_b_1523_nb_4l_lithium_ion_battery_pack.html) for a replacement battery. Some brands are decent quality.
If you didn't take care of your battery by keeping it charged at least 50%, or higher, then the battery capacity will suffer - especially if it drains down to zero charge. |
128,580 | When I wind it back there is a click noise once i let go of the winder and then i cant press the shutter release so i have to wind again which advances it, I dont have film in it but it seems if i did it could waste some shots which I do not want | 2022/02/11 | [
"https://photo.stackexchange.com/questions/128580",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/104859/"
] | On a compact camera you can usually take 200-300 photos on a battery. The biggest power drain is the rear display so your best strategy for power saving is to find the setting that shuts it off quickly when not in use.
Then as others say batteries are consumable so your current battery is likely dead, but you can find decent compatible batteries (avoid the cheaper ones, though) and possibly an external charger if you haven't got one already. And start the day with a couple of spare batteries in your bag (IMHO the "Power bank" solution is way too bulky to be used with a camera, unless you use a tripod). | You'll probably need to use a [third party manufacturer](https://www.bhphotovideo.com/c/product/836622-REG/watson_b_1523_nb_4l_lithium_ion_battery_pack.html) for a replacement battery. Some brands are decent quality.
If you didn't take care of your battery by keeping it charged at least 50%, or higher, then the battery capacity will suffer - especially if it drains down to zero charge. |
128,580 | When I wind it back there is a click noise once i let go of the winder and then i cant press the shutter release so i have to wind again which advances it, I dont have film in it but it seems if i did it could waste some shots which I do not want | 2022/02/11 | [
"https://photo.stackexchange.com/questions/128580",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/104859/"
] | In the first instance, 30 mins video recording actually sounds about right. At the time, video recording was very much a "nice to have" for those devices; while they can be pretty good at it, it was very rarely discussed in reviews.
Then too, since they're compact by both name and nature, their batteries are pretty small and realtime video encoding is very energy intensive!
(And, at least in the EU, the video recording features were sometimes deliberately crippled, since the import duties for a "stills" camera were lower than for a camcorder...)
Beyond that, the 255 uses the standard NB-4L battery; I probably still have a half-dozen of these sat in a drawer somewhere, though I'd be surprised if they still hold a useful charge.
I used to love my Canon Ixus compact cameras; I used to always carry one, since they made for great little camcorders at gigs and the like. And I steadily upgraded through the years, until they switched from a mono to stereo microphone, since for some reason, the newer microphones were significantly worse at handling "gig" volume levels.
(Not sure if I ever owned a 255; it looks familiar in the photos, but then, the Ixus range all looked pretty similar to each other! Equally, finding a good replacement proved tricky, since as per above, few if any reviews looked at the video quality and virtually none discussed the audio quality...)
Anyhow, since I did a lot of video recording with these cameras, I generally carried a spare battery or two around with me. All of which came from Ebay, and were both unbranded and a fraction of the cost of the official batteries.
And they all worked fine.
Did they hold as much charge as the original battery? I don't recall any being particularly different - I tended to make a point of avoiding the batteries which claimed to hold a significantly bigger charge than the OEM ones, since it was most likely either a blatant lie (as happened a lot with SD cards - a cheap 32GB card could be a 4GB card with some hacked firmware), or they were pushing the limits of the battery tech and I had no desire to find my pocket bursting into flames.
And there still seems to be plenty of said NB-4L batteries on Ebay. Even ones which are branded (e.g. Duracell, Energiser).
So my advice would be to just grab a couple off Ebay or Amazon. And to steer clear of any which claim to have more than 850mah capacity! | You'll probably need to use a [third party manufacturer](https://www.bhphotovideo.com/c/product/836622-REG/watson_b_1523_nb_4l_lithium_ion_battery_pack.html) for a replacement battery. Some brands are decent quality.
If you didn't take care of your battery by keeping it charged at least 50%, or higher, then the battery capacity will suffer - especially if it drains down to zero charge. |
128,580 | When I wind it back there is a click noise once i let go of the winder and then i cant press the shutter release so i have to wind again which advances it, I dont have film in it but it seems if i did it could waste some shots which I do not want | 2022/02/11 | [
"https://photo.stackexchange.com/questions/128580",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/104859/"
] | >
> I bought a Canon IXUS 255 HS eight years ago... the battery lasts a ridiculously short time.
>
>
>
After eight years, it may be time to replace the battery, especially if you haven't kept it charged to 40-60% during that time.
>
> Especially if I'm recording video.
>
>
>
Most cameras have a video recording time limit of about half an hour for tax classification purposes. If your primary objective is to record video, use a camcorder.
>
> Within half an hour, it's basically drained. If I'm lucky, it might last a couple of hours.
>
>
>
That's a big difference. Use a stopwatch to obtain more precise timing.
>
> If I were to finally go on vacation...
>
>
>
Consider carrying a **spare battery**.
>
> ... some sort of much physically larger thing that fits into the battery slot but also extends way beyond it, to enable a full 24 hours of video recording and photo-taking... Does such a thing exist for my camera? Does it exist for any camera?
>
>
>
They're known as **dummy batteries** or **DC couplers**. One end fits into the battery slot of your camera. The other end attaches to an AC adapter or battery pack.
Many camcorders have extended batteries. These are possible because of the position of the battery at the back of the camcorder.
Flagship DSLRs and mirrorless cameras often have **battery grips** available. Runtime is unlikely to extend to 24 hours though. | On a compact camera you can usually take 200-300 photos on a battery. The biggest power drain is the rear display so your best strategy for power saving is to find the setting that shuts it off quickly when not in use.
Then as others say batteries are consumable so your current battery is likely dead, but you can find decent compatible batteries (avoid the cheaper ones, though) and possibly an external charger if you haven't got one already. And start the day with a couple of spare batteries in your bag (IMHO the "Power bank" solution is way too bulky to be used with a camera, unless you use a tripod). |
128,580 | When I wind it back there is a click noise once i let go of the winder and then i cant press the shutter release so i have to wind again which advances it, I dont have film in it but it seems if i did it could waste some shots which I do not want | 2022/02/11 | [
"https://photo.stackexchange.com/questions/128580",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/104859/"
] | >
> I bought a Canon IXUS 255 HS eight years ago... the battery lasts a ridiculously short time.
>
>
>
After eight years, it may be time to replace the battery, especially if you haven't kept it charged to 40-60% during that time.
>
> Especially if I'm recording video.
>
>
>
Most cameras have a video recording time limit of about half an hour for tax classification purposes. If your primary objective is to record video, use a camcorder.
>
> Within half an hour, it's basically drained. If I'm lucky, it might last a couple of hours.
>
>
>
That's a big difference. Use a stopwatch to obtain more precise timing.
>
> If I were to finally go on vacation...
>
>
>
Consider carrying a **spare battery**.
>
> ... some sort of much physically larger thing that fits into the battery slot but also extends way beyond it, to enable a full 24 hours of video recording and photo-taking... Does such a thing exist for my camera? Does it exist for any camera?
>
>
>
They're known as **dummy batteries** or **DC couplers**. One end fits into the battery slot of your camera. The other end attaches to an AC adapter or battery pack.
Many camcorders have extended batteries. These are possible because of the position of the battery at the back of the camcorder.
Flagship DSLRs and mirrorless cameras often have **battery grips** available. Runtime is unlikely to extend to 24 hours though. | In the first instance, 30 mins video recording actually sounds about right. At the time, video recording was very much a "nice to have" for those devices; while they can be pretty good at it, it was very rarely discussed in reviews.
Then too, since they're compact by both name and nature, their batteries are pretty small and realtime video encoding is very energy intensive!
(And, at least in the EU, the video recording features were sometimes deliberately crippled, since the import duties for a "stills" camera were lower than for a camcorder...)
Beyond that, the 255 uses the standard NB-4L battery; I probably still have a half-dozen of these sat in a drawer somewhere, though I'd be surprised if they still hold a useful charge.
I used to love my Canon Ixus compact cameras; I used to always carry one, since they made for great little camcorders at gigs and the like. And I steadily upgraded through the years, until they switched from a mono to stereo microphone, since for some reason, the newer microphones were significantly worse at handling "gig" volume levels.
(Not sure if I ever owned a 255; it looks familiar in the photos, but then, the Ixus range all looked pretty similar to each other! Equally, finding a good replacement proved tricky, since as per above, few if any reviews looked at the video quality and virtually none discussed the audio quality...)
Anyhow, since I did a lot of video recording with these cameras, I generally carried a spare battery or two around with me. All of which came from Ebay, and were both unbranded and a fraction of the cost of the official batteries.
And they all worked fine.
Did they hold as much charge as the original battery? I don't recall any being particularly different - I tended to make a point of avoiding the batteries which claimed to hold a significantly bigger charge than the OEM ones, since it was most likely either a blatant lie (as happened a lot with SD cards - a cheap 32GB card could be a 4GB card with some hacked firmware), or they were pushing the limits of the battery tech and I had no desire to find my pocket bursting into flames.
And there still seems to be plenty of said NB-4L batteries on Ebay. Even ones which are branded (e.g. Duracell, Energiser).
So my advice would be to just grab a couple off Ebay or Amazon. And to steer clear of any which claim to have more than 850mah capacity! |
6,164,685 | Using CSS, how can I display an image behind some text and also offset it on both the X and Y axis?
I have a design that is 950px wide, so I'm wanting want this image to remain 'in sync' with the rest of the header by placing it in a container that is centered and also 950px wide.
My problem is that instead of the image being 'a layer behind' the header text, it is instead displaying the image in full and pushing the rest of the contents down.
Any help is greatly appreciated.
**IMAGE ADDED FOR CLARIFICATION**
Thanks,
Andy. | 2011/05/28 | [
"https://Stackoverflow.com/questions/6164685",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/382134/"
] | Its likely your DB is becoming corrupt somehow. There's no command that does that (I hope). | Do yourself a favor and alter each and every one of your tables so they use the [InnoDB engine](http://dev.mysql.com/doc/refman/5.5/en/innodb-storage-engine.html) instead of MyISAM. It's still be MySQL, but it'll be a lot less prone to data corruption.
And if changing DB altogether is an option, look into using [PostgreSQL](http://www.postgresql.org/docs/9.0/static/index.html) instead. |
37,182 | I've run out of drive space on my external and got a new one to move everything on to. I can't afford to lose my 'date added' values. How is this done? I should mention I let iTunes manage the files for me (in other words - it all lives in one place).
Thanks! | 2009/09/07 | [
"https://superuser.com/questions/37182",
"https://superuser.com",
"https://superuser.com/users/-1/"
] | Just move your iTunes folder (along with the iTunes library file). The "Date Added" field is stored in the library file (it's an XML file actually, so you can open it with a text editor to verify), and if you move the whole thing lock, stock, and barrel, nothing should change at all. | Change the Music Folder location in iTunes->Preferences->Advanced to the new, still empty location. Ensure "Keep iTunes Music folder organized" is checked.
Then, in the iTunes menu, select File->Library->Consolidate Library. iTunes will move the music to the new folder.
[Apple Support](http://support.apple.com/kb/HT1449) will hold your hand through this. |
124,163 | I am trying to log in on a Drupal site, but the site doesn't have the login block enabled.
How can I find the URL for the login form? | 2014/07/21 | [
"https://drupal.stackexchange.com/questions/124163",
"https://drupal.stackexchange.com",
"https://drupal.stackexchange.com/users/34191/"
] | Drupal default login URL format,
**example.com/user** | With Drupal, if the login block isn't shown in any page, you can see the login form visiting the user/login path. If you are already logged in, Drupal will return a 403 error, since only users who still have to log in can access that page.
If you visit <http://example.com/user> (replace example.com with the domain of your site), you will see your user profile page, if you are logged in, or you will be redirected to the login form, if you aren't logged in.
If clean URLs aren't enabled, the login form will be visible on <http://example.com/?q=user/login>, while the user profile page will be visible on <http://example.com/?q=user>. (Replace example.com with the domain of the Drupal site.) |
124,163 | I am trying to log in on a Drupal site, but the site doesn't have the login block enabled.
How can I find the URL for the login form? | 2014/07/21 | [
"https://drupal.stackexchange.com/questions/124163",
"https://drupal.stackexchange.com",
"https://drupal.stackexchange.com/users/34191/"
] | You can also check <http://example.com/?q=user/login> if the clean url is not enabled. | With Drupal, if the login block isn't shown in any page, you can see the login form visiting the user/login path. If you are already logged in, Drupal will return a 403 error, since only users who still have to log in can access that page.
If you visit <http://example.com/user> (replace example.com with the domain of your site), you will see your user profile page, if you are logged in, or you will be redirected to the login form, if you aren't logged in.
If clean URLs aren't enabled, the login form will be visible on <http://example.com/?q=user/login>, while the user profile page will be visible on <http://example.com/?q=user>. (Replace example.com with the domain of the Drupal site.) |
124,142 | >
> **Possible Duplicate:**
>
> [Can you help me with my software licensing question?](https://serverfault.com/questions/215405/can-you-help-me-with-my-software-licensing-question)
>
>
>
Our company needs to buy Microsoft software Licenses for our project soon and I there are so many places to buy I don't know where to trust.
We need Windows Server 2008 Standard, and SQL Server 2008 Standard.
We are in China but the prices here are ridiculous. We could buy from the US.
We need 5 CALs. Buying for business. | 2010/03/19 | [
"https://serverfault.com/questions/124142",
"https://serverfault.com",
"https://serverfault.com/users/37404/"
] | Just contact any reseller. Prices in china will seriously NOT be ridiculous - I doubt you will save buying in the US. Anyhow, any larger US resller rwill love to answer you.
How many licenses do you need and "what for" (i.e. are normal licenses applicable or do you fall under a special program)? | Prices should be same. Also define for what purpose you wish you buy the license ? NGO, Education or Business ??
you can go to any reseller site, who is Microsoft Gold partner certified. |
47,662 | I'm looking for a Sci-Fi Space-faring RPG that meets the following requirements:
1. The system is free or has enough OGL rules to be played for free.
2. The rules should be primarily or solely developed for a Sci-Fi, Space-faring RPG. No sci-fi variation on a generic system — no GURPS, Fate, Hero System, d20, etc.
3. The game is rules-heavy enough to have detailed rules on space flight and space combat.
4. The game has detailed character creation and equipment rules.
5. The setting would be at the point at which space travel was very commonplace, possibly far-future or transhumanist.
Hopefully that's enough requirements listed to narrow down to a best answer; I'd really appreciate any help with such a system. | 2014/09/10 | [
"https://rpg.stackexchange.com/questions/47662",
"https://rpg.stackexchange.com",
"https://rpg.stackexchange.com/users/-1/"
] | This is the only one I know of that is completely free:
[Stars without Number](http://www.rpgnow.com/product/86467/Stars-Without-Number-Free-Edition?filters=500_2140_0_0_0)
This was is part of the D6 universal system. However I am adding this because the progenitor system was Star Wars The Roleplaying Game. Of all the D6 games this is the closest to the original sci-fi RPG:
[D6 Space](http://www.rpgnow.com/product/20447/D6-Space?it=1&filters=500_2140_0_0_0)
[The Cepheus Game Engine](http://www.rpgnow.com/product/186894/Cepheus-Engine-System-Reference-Document?term=Cepheu&test_epoch=0) is available as a clone of classic Traveller and Mongoose Traveller 1st edition. | My very first RPG, the venerable TSR game Star Frontiers, [is (legally) available for free from starfrontiers.com now](http://www.starfrontiers.com/). Alpha Dawn was the basic space opera game and Knight Hawks was full starship rules. Percentile based stats/skills, lots of equipment.
I've also played a lot of the later TSR SF game Alternity. [The fastplays are downloadable for free](http://www.alternityrpg.net/downloads.php); the rest you'll need to get used. "Free" is a lame requirement anyway, unless you live in a third world hellhole you can easily choose to skip a movie and save enough money to get a rulebook that's going to be used to run a whole campaign with.
[Eclipse Phase](http://eclipsephase.com/) is transhumanist with space travel only within the solar system; it's freely downloadable. It's also modern and well supported.
This really isn't a very well focused recommendation question; there's 25 pages of space opera core rules listed on RPGGeek. Just on RPGNow, [searching for free sci-fi core rules](http://www.rpgnow.com/browse.php?filters=500_2140_0_0_0&pto=0&pfrom=0), there's 194 of them. SF with mechs! With Cthulhus! You need to share what kind of story you want to tell/campaign you want to run to get better answers. |
1,057,888 | I have lenovo y50-70 . there is no msata ports or no free ports . but i want to add a ssd to it without replacing hard drive . i want to add a 120gb ssd. I am thinking if by splitter cable like sata splitter cable or pcie splitter is it possible to achieve what i am thinking ? | 2016/03/27 | [
"https://superuser.com/questions/1057888",
"https://superuser.com",
"https://superuser.com/users/575700/"
] | >
> I am thinking if by splitter cable like sata splitter cable or
> PCI-e splitter. Is it possible to
>
>
>
No, at least not with a simple splitter.
SATA is a point to point connection. You can multiplex multiple streams over a single SATA channel if you use a [port multiplier](https://en.wikipedia.org/wiki/Port_multiplier). I doubt that most laptops will support this or that you can easily boot from it. (Easily as in, it might work but you might need to reinstall with additional drivers).
PCI-e is also a set of point to point devices. And PCI-e x1 lane has some control lines, some power and one set (the x1) of data lines. Same for PCI-e x4, x8, x16, but with more data lines in paralel. So you cannot just use cable splitter. Whaty you can do is add one device (one, so no splitting) which understands PCI-e and has multiple PCI-e outs (a PCI-e bridge). Usually these are sensitive things build into a motherboard, not something you just slap onto a laptop.
That leaves you with alternate solutions:
1. Connect the SSD regualry via SATA and enjoy its speed. Connect the HDD via a port which is available (e.g. firewire, USB, ...).
2. Find a way to add a port (Thunderbolt SATA card, expresscard to SATA, ...) | Rather late, but you could also use an [external USB SSD](http://www.newegg.com/External-SSDs/SubCategory/ID-2022) in a USB3 port. |
171,748 | How do apps like Symantec VIP / Okta Verify and similar implementations compare to using a hardware auth token such as the recent U2F devices?
How real is the possibility of an Android system being hijacked and 2FA app authentication tokens or otherwise secret keys being extracted?
Besides not needing another device, are there any other advantages to app-based 2FA?
Given that with app-based 2FA you authenticate a request or login session in real-time, is it not vulnerable to real-time authentication replay phishing attacks?
Edit: This seems to be sort-of answered here [Can a smartphone strictly be viewed as the 'something you posses' factor for 2FA when it has no hardware token capability like smartcards?](https://security.stackexchange.com/questions/169992/can-a-smartphone-strictly-be-viewed-as-the-something-you-posses-factor-for-2fa) | 2017/10/20 | [
"https://security.stackexchange.com/questions/171748",
"https://security.stackexchange.com",
"https://security.stackexchange.com/users/150188/"
] | Have a look at [this answer here](https://security.stackexchange.com/a/71704/2264) for more detail. But here's the salient bits for your question:
The problem with 2-factor as implemented by Symantec VIP and Okta Verify has less to do with the fact that it's implemented in software, and more to do with the fact that the code can be intercepted.
In this sense, Symantec VIP, Okta Verify, and RSA SecurID are all in the same boat as Google Authenticator; none of them will protect you from phishing because the same technique the attacker uses to get your password can *also* be used to get your 2nd factor code; usually by getting you to type it into a fake login page.
But U2F is different.
With U2F, you don't type in a one-time-password to show you have your token. Instead, the browser communicates directly with the hardware token, and part of the process is that the browser tells the hardware token the hostname of the site that is requesting identification, and 2FA identities are tied to the individual host. And the browser (unlike the user) cannot be fooled regarding which host is requesting authentication because the browser checks the TLS certificate.
This means that an attacker's website can't get the correct 2nd factor code, and it means that even if a clever social engineering attacker managed to trick a user into giving up their password, the user *can't* give up their 2nd factor code.
The 2nd factor token can ONLY be used if the browser is communicating with the correct site, and only if the browser is physically connected to the U2F token. This pretty much eliminates any attack that doesn't involve the physical theft of the victim's hardware.
U2F *could* be implemented (and has been) in software, so you're depending on software on your computer rather than a physical device. This is still better than OTP-based 2FA such as Symantec VIP for phishing resistance, but in this case physical theft is no longer a requirement for exploitation. Instead, if your token is implemented in software, then any intrusion on your computer (virus, etc.) could make a copy of your authentication device and use it on their computer without your knowledge. So it's not *quite* as good as a physical device, but it's a lot less expensive. | >
> How do apps [...] compare to using a hardware auth token [...]?
>
>
>
At first sight, they don't differ too far. Well in both cases you have some other device which does an additional cryptographic verification step for you. But one important difference is the complexity of the system (the whole software on that device).
On a smart phone there is a heck lot of interacting pieces of software form different vendors (apps), while a dedicate authentication token is there far simpler since the serve just this single one purpose. Therefore, the chance and surface for vulnerability is generally lower for the simpler system.
Another difference would be the actual algorithm used for that authentication step. But this does not depend anyhow on the hardware. However, apps tend to be simpler e.g. Time-based One-Time Password generators, while the others are usually more sophisticate about their sole purpose, for instance U2F uses challenge based Public key cryptography. BTW that's one reason why using U2F requires also support from the browser to forward the challenge to the U2F stick.
>
> How real is the possibility of an Android system being hijacked [...] and [...] secret keys being extracted?
>
>
>
Well it is real that you can hack a mobile phone like every other computer system and gain *root* access to it. If a key can be extracted, depends on how the app stores that secret. But since it has to save it and since there is no real private memory on Android devices (AFAIK), an attacker which gained *root* access could copy the key.
>
> [...] are there any other advantages to app-based 2FA?
>
>
>
On a plain security level, I don't believe there is any advantage for smart phones vs. dedicated hardware. But apps are usually far easier to install and setup than those specialized systems. And a system which is to complicated to be used by an average user, doesn't improve anything in a real world. Also notice that those special systems need usually additional service provider support, an if a technique is to complicated to be implemented or hardly used, the best user can't do anything without supported services.
>
> Given that [...] you authenticate a request or login session in real-time, is it not vulnerable to real-time authentication replay phishing attacks?
>
>
>
As far as I can see it, you can generally do a Man-in-the-middle attack and hijack the authenticated session. But that's what SSL-certificates intend to prevent.
And it is accompanied by encryption which limit the usability of simple replay attacks. A part form SSL, replay on time-based tokens is a possibility. However, a service provider could enlist the successfully used tokens and prevent replays. Still, if the attacker were fast enough he would be the one having succeed. |
226,429 | I'm trying to show cemetery label plots at all scales. I have tried to change the visible range within the label features (see screenshot below) but this wont let me go below 1:100. Anything that I type in below 100 will default back to 100.
The problem is that our cremation plots are approx 30cm x 30cm so even at a 1:100 scale these 3mm squares are too small to view labels (three digit numbers).
How do I allow labels to show below 1:100?
Is there an alternative way that would work?
[](https://i.stack.imgur.com/pT4j2.png)
**EDIT:**
I have allowed further zoom within the map settings of the application which allow for the map to zoom into 1:25 (yes the basemap will disappear at this level but that isn't a problem). Hence why I should be able to see labels at this same scale.
[](https://i.stack.imgur.com/s81CB.png) | 2017/01/31 | [
"https://gis.stackexchange.com/questions/226429",
"https://gis.stackexchange.com",
"https://gis.stackexchange.com/users/64250/"
] | * Convert labels to annotations in ArcGIS
* use [feature outline to mask tool](http://desktop.arcgis.com/en/arcmap/10.3/tools/cartography-toolbox/feature-outline-masks.htm) and publish output polygons.
This way you can see labels in Collector as well, not just ArcGIS online. | In my case, 1:100 looks like the maximum scale you can zoom at.
So there is no point displaying the label scale at a finer level of detail, because there isn't. 1:100 is the maximum scale you can zoom at. That's probably why ArcGIS online won't let you do so.
See my screenshot, the zoom is 1 cm = 1 meters (or 100 cm, hence 1:100). And my labels are visible.
[](https://i.stack.imgur.com/qVqZ4.png) |
69,839 | I'm afraid I've corrupted my OS X install. When choosing to boot up with the system I get a grey screen (there's a short load sequence before this, after klicking the system icon in the bootup menu). I can hover my mouse around but there is no content. Earlier today I tried installing Windows 8 as a second system using Mountain Lion and Boot Camp 5.
I did the following:
* Created a volume for Windows and installed Win7 + windows drivers
* Began installing Win8, only to realize that I needed more disk space (apparently using the online upgrade requires a LOT of disk in between the switch). Chose to quit the installer.
* Tried returning to OS X to delete the Windows volume but ended up with a grey screen.
Worth noting is that I see my OS X Recovery volume presented along OS X and Windows. My guess is it should be there but it could also be an indication that there is something wrong. | 2012/10/27 | [
"https://apple.stackexchange.com/questions/69839",
"https://apple.stackexchange.com",
"https://apple.stackexchange.com/users/33645/"
] | Problem solved (for now). Started up OS X successfully in Safe Mode and was able to remove the Windows partition via Boot Camp Assistant. Restarted and everything seems to be back to normal. | Upgrading to windows 8 creates a windows.old folder with the previous windows there (aprox 12~15 GB in size)
Its ok to delete it if everythinug works ok as you'll not be able to undo the upgrade after it. Truth be told, I dont think the upgrade is undoable anyway.
To delete the windows.old folder you'll need to take ownership of it first (Properties -> security tab -> advanced) and make sure that replace child permissions is checked |
1,405,120 | But default you have to issue an HTTP POST to any web method in an asp.net 2.0 web service. How do u call a web method with HTTP GET alone. In some cases I'd also want to pass arguments to an HTTP GET method. Is this possible in the context of web services? | 2009/09/10 | [
"https://Stackoverflow.com/questions/1405120",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/145682/"
] | You can take a look at
<http://commandline.codeplex.com/>
and
[GetPot command line parser](http://getpot.sourceforge.net/) | If you're interested in .NET (your question doesn't give any information) I've had the [Plossum.CommandLine](http://www.codeproject.com/KB/recipes/plossum_commandline.aspx?display=Print) library recommended to me before now. I haven't used it myself, but you might want to take a look. |
1,405,120 | But default you have to issue an HTTP POST to any web method in an asp.net 2.0 web service. How do u call a web method with HTTP GET alone. In some cases I'd also want to pass arguments to an HTTP GET method. Is this possible in the context of web services? | 2009/09/10 | [
"https://Stackoverflow.com/questions/1405120",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/145682/"
] | If you're interested in .NET (your question doesn't give any information) I've had the [Plossum.CommandLine](http://www.codeproject.com/KB/recipes/plossum_commandline.aspx?display=Print) library recommended to me before now. I haven't used it myself, but you might want to take a look. | Google's commandline-parsing library for C++ and python: <http://code.google.com/p/google-gflags/> |
1,405,120 | But default you have to issue an HTTP POST to any web method in an asp.net 2.0 web service. How do u call a web method with HTTP GET alone. In some cases I'd also want to pass arguments to an HTTP GET method. Is this possible in the context of web services? | 2009/09/10 | [
"https://Stackoverflow.com/questions/1405120",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/145682/"
] | If you're interested in .NET (your question doesn't give any information) I've had the [Plossum.CommandLine](http://www.codeproject.com/KB/recipes/plossum_commandline.aspx?display=Print) library recommended to me before now. I haven't used it myself, but you might want to take a look. | The [BizArk library](http://bizark.codeplex.com/) contains a command-line parser.
Basically you just create a class that inherits from CmdLineObject, add properties that you want populated from the command-line, add a CmdLineArgAttribute to the properties, then call Initialize in your program. It supports ClickOnce URL arguments too!
Features (from the site)...
* Automatic initialization: Class properties are automatically set based on the command-line arguments.
* Default properties: Send in a value without specifying the property name.
* Value conversion: Uses the powerful ConvertEx class also included in BizArk to convert values to the proper type.
* Boolean flags. Flags can be specified by simply using the argument (ex, /b for true and /b- for false) or by adding the value true/false, yes/no, etc.
* Argument arrays. Simply add multiple values after the command-line name to set a property that is defined as an array. Ex, /x 1 2 3 will populate x with the array { 1, 2, 3 } (assuming x is defined as an array of integers).
* Command-line aliases: A property can support multiple command-line aliases for it. For example, Help uses the alias ?.
* Partial name recognition. You don’t need to spell out the full name or alias, just spell enough for the parser to disambiguate the property/alias from the others.
* Supports ClickOnce: Can initialize properties even when they are specified as the query string in a URL for ClickOnce deployed applications. The command-line initialization method will detect if it is running as ClickOnce or not so your code doesn’t need to change when using it.
* Automatically creates /? help: This includes nice formatting that takes into account the width of the console.
* Load/Save command-line arguments to a file: This is especially useful if you have multiple large, complex sets of command-line arguments that you want to run multiple times. |
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