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 |
|---|---|---|---|---|---|
507,192 | As light is electromagnetic radiation. Then why I don't see any magnet bending light wave? Or why light doesn't diffract whenever it passes by a live wire? | 2019/10/09 | [
"https://physics.stackexchange.com/questions/507192",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/-1/"
] | Roughly speaking, electric fields push and pull charges, while magnetic fields cause charges to loop around (by 'loop around' I'm saying that the magnetic fields cause the charges to accelerate at a right angle to their direction of motion).
Since light doesn't have an electric charge, there is nothing for electric fields to push or pull and nothing for magnetic fields to loop around.
If we just look at the classical case, then there is no direct interaction between magnetic fields and the electromagnetic wave. It's a little bit like how most waves can just pass right through each other without changing each other.
That being said, if magnetic fields are crazy intense, (say the magnetic fields near the surface of a magnetic pole of a neutron star) then there are some higher-order quantum effects that come into play.
This is due to the possibility that the photon splits into a virtual electron-positron pair and then recombines. An intense magnetic field could interact with the virtual pair and have an effect.
For instance, depending on how the virtual pair is aligned with the magnetic field, the energy level would be higher or lower, and this has an effect on how much of a contribution this possibility has.
This is called the [Euler-Heisenberg interaction](https://en.wikipedia.org/wiki/Euler%E2%80%93Heisenberg_Lagrangian). | In classical physics, electromagnetic fields and waves are additive so nothing can happen in vacuum between electromagnetic fields. They don't see each other.
In quantum physics, photons theoretically DO interact. The effect is rather small even in high-energy experiments, so don't expect some visible distortion with visible light and an iron magnet.
<https://en.wikipedia.org/wiki/Two-photon_physics> |
507,192 | As light is electromagnetic radiation. Then why I don't see any magnet bending light wave? Or why light doesn't diffract whenever it passes by a live wire? | 2019/10/09 | [
"https://physics.stackexchange.com/questions/507192",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/-1/"
] | In vacuum electromagnetic fields obey superposition to a very high degree of accuracy. A magnetic field does not have any effect on light. Light in material media *can* be affected by a magnetic field. This is known as the [Kerr effect](https://en.wikipedia.org/wiki/Kerr_effect).
As for current carrying wires, these reflect and diffract electromagnetic waves like any metallic or dielectric object. This is why you see them. However, there is no effect of the current until the wire heats up. | In classical physics, electromagnetic fields and waves are additive so nothing can happen in vacuum between electromagnetic fields. They don't see each other.
In quantum physics, photons theoretically DO interact. The effect is rather small even in high-energy experiments, so don't expect some visible distortion with visible light and an iron magnet.
<https://en.wikipedia.org/wiki/Two-photon_physics> |
88,952 | I want to express that I learning some courses will give me a good vision in a specific field.
Can I say like "these courses take me on the way to the statistics"? | 2016/05/02 | [
"https://ell.stackexchange.com/questions/88952",
"https://ell.stackexchange.com",
"https://ell.stackexchange.com/users/32654/"
] | Maybe you want to say
>
> These courses should/will get me started on my way to learning/understanding statistics.
>
>
>
We can shorten this in several ways.
>
> These should get me on my way
>
>
>
would be clear and idiomatic if your listener knows what you are talking about.
The sense of *way* here, means *heading toward* or *going in the direction of* some destination. We can assume that the destination you have in mind is the mastery of statistics to some degree.
See <http://idioms.thefreedictionary.com/on+way> | No, that's not correct.
I assume the course is about statistics, right? Maybe you could say,
>
> This course will give a good overview of statistics.
>
>
>
An "overview" means you will understand what the subject is about, but not be an expert. I'm not sure if that's what you want to say. |
88,952 | I want to express that I learning some courses will give me a good vision in a specific field.
Can I say like "these courses take me on the way to the statistics"? | 2016/05/02 | [
"https://ell.stackexchange.com/questions/88952",
"https://ell.stackexchange.com",
"https://ell.stackexchange.com/users/32654/"
] | Maybe you want to say
>
> These courses should/will get me started on my way to learning/understanding statistics.
>
>
>
We can shorten this in several ways.
>
> These should get me on my way
>
>
>
would be clear and idiomatic if your listener knows what you are talking about.
The sense of *way* here, means *heading toward* or *going in the direction of* some destination. We can assume that the destination you have in mind is the mastery of statistics to some degree.
See <http://idioms.thefreedictionary.com/on+way> | I think it's not idiomatic to say:
These courses will take me on the way to the statistics.
I think you can rephrase your sentence as follows:
These courses will go a long way toward(s) learning statistics.
These courses will give a good insight into statistics. |
293,927 | Because while that is technically the correct spelling for each word, but as a phrase it doesn't seem to work well together. It lacks symmetry (Hipp**ie** vs. Dipp**y**) and uses the extremely rare-yet-proper Italian "bologna".
Origin: The phrase is used with delightful comic effect in [*The Lego Movie*](http://www.imdb.com/title/tt1490017/) and quoted on [wikiquote](https://en.wikiquote.org/wiki/The_Lego_Movie#Lord_Business) as "hippie, dippy baloney".
Consider:
* "Hippie-dippie" for symmetry? [Merriam-Webster](http://www.merriam-webster.com/dictionary/hippie-dippie) supports it. (Wiktionary includes it as [a short entry](https://en.wiktionary.org/wiki/hippie-dippie)).
* Hippy? Would match "Dippy". Although "Hippie" has the most support in usage and prescription (on [wiktionary](https://en.wiktionary.org/wiki/hippie) and [English stackexchange](https://english.stackexchange.com/questions/227992/of-yuppies-and-yippies-and-hippies))
+ And yet [Google suggests](http://google.com/search?q=hippie+dippy+baloney+lego) "**Hippy** Dippy Baloney Lego" for a "**Hippie** Dippy Baloney Lego" search, as if "Hippie" were misspelled based on the comparative number of search results.
* Dippie? Would match "Hippie".
+ And yet scarce presence [among Internet dictionaries](http://google.com/search?q=dippie+in+a+dictionary).
+ Whereas [Dippy](http://en.wiktionary.org/wiki/dippy)
* Baloney? Far more common in usage and [growing in dictionary acceptance](https://en.wiktionary.org/wiki/baloney).
* Dash between hippie and dippy? Dash between all three?
The question is: How best to spell "Hippie-Dippie Baloney"? | 2015/12/14 | [
"https://english.stackexchange.com/questions/293927",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/151541/"
] | >
> ’Tis one thing to be tempted, Escalus,
> Another thing to fall. *(Measure for Measure* 2.1.17–18)
>
>
>
The coordinate pairing of infinitives in this construction is so well established that a reader is likely to reach the end of your first sentence waiting for the other shoe to drop. Your then beginning the second with a *to* infinitive *of purpose* is thus a kind of [garden path](https://en.wikipedia.org/wiki/Garden_path_sentence). It is grammatically perfectly correct, but not as foolproof for your reader as you can and should make it. | It seems that you want to use unsuccessfully two constructions combined
“It is one thing to passively learn about all those various commands in JavaScript by poring over online materials. However, in order to fully appreciate how and when to use each one, I need to try them out in my own code and have them corrected by someone in the know.”
“It is one thing to passively learn about all those various commands in JavaScript by poring over online materials, but to fully appreciate how and when to use each one, I need to try them out in my own code and have them corrected by someone in the know.”
You are using a shortcut for no particular reason.
First solution is ok. It gives you a rest after one long sentence for approaching another long sentence.
Second one is stressing the importance of the second sentence, you want a reader to concentrate and grasp the complete meaning, compare two choices you are trying to explain. You are building a momentum.
It is up to you which one you like better, but your solution is really neither one nor the other. |
293,927 | Because while that is technically the correct spelling for each word, but as a phrase it doesn't seem to work well together. It lacks symmetry (Hipp**ie** vs. Dipp**y**) and uses the extremely rare-yet-proper Italian "bologna".
Origin: The phrase is used with delightful comic effect in [*The Lego Movie*](http://www.imdb.com/title/tt1490017/) and quoted on [wikiquote](https://en.wikiquote.org/wiki/The_Lego_Movie#Lord_Business) as "hippie, dippy baloney".
Consider:
* "Hippie-dippie" for symmetry? [Merriam-Webster](http://www.merriam-webster.com/dictionary/hippie-dippie) supports it. (Wiktionary includes it as [a short entry](https://en.wiktionary.org/wiki/hippie-dippie)).
* Hippy? Would match "Dippy". Although "Hippie" has the most support in usage and prescription (on [wiktionary](https://en.wiktionary.org/wiki/hippie) and [English stackexchange](https://english.stackexchange.com/questions/227992/of-yuppies-and-yippies-and-hippies))
+ And yet [Google suggests](http://google.com/search?q=hippie+dippy+baloney+lego) "**Hippy** Dippy Baloney Lego" for a "**Hippie** Dippy Baloney Lego" search, as if "Hippie" were misspelled based on the comparative number of search results.
* Dippie? Would match "Hippie".
+ And yet scarce presence [among Internet dictionaries](http://google.com/search?q=dippie+in+a+dictionary).
+ Whereas [Dippy](http://en.wiktionary.org/wiki/dippy)
* Baloney? Far more common in usage and [growing in dictionary acceptance](https://en.wiktionary.org/wiki/baloney).
* Dash between hippie and dippy? Dash between all three?
The question is: How best to spell "Hippie-Dippie Baloney"? | 2015/12/14 | [
"https://english.stackexchange.com/questions/293927",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/151541/"
] | >
> ’Tis one thing to be tempted, Escalus,
> Another thing to fall. *(Measure for Measure* 2.1.17–18)
>
>
>
The coordinate pairing of infinitives in this construction is so well established that a reader is likely to reach the end of your first sentence waiting for the other shoe to drop. Your then beginning the second with a *to* infinitive *of purpose* is thus a kind of [garden path](https://en.wikipedia.org/wiki/Garden_path_sentence). It is grammatically perfectly correct, but not as foolproof for your reader as you can and should make it. | First, it is always awkward to have anything between to and the infinitive as we were told in grammar school. Secondly, the comparison should form a somewhat sharp contrast rather than two similar but slightly different things. My example is this: "It is one thing for a person to own what he has created; it is another for him to stop others from copying it." |
293,927 | Because while that is technically the correct spelling for each word, but as a phrase it doesn't seem to work well together. It lacks symmetry (Hipp**ie** vs. Dipp**y**) and uses the extremely rare-yet-proper Italian "bologna".
Origin: The phrase is used with delightful comic effect in [*The Lego Movie*](http://www.imdb.com/title/tt1490017/) and quoted on [wikiquote](https://en.wikiquote.org/wiki/The_Lego_Movie#Lord_Business) as "hippie, dippy baloney".
Consider:
* "Hippie-dippie" for symmetry? [Merriam-Webster](http://www.merriam-webster.com/dictionary/hippie-dippie) supports it. (Wiktionary includes it as [a short entry](https://en.wiktionary.org/wiki/hippie-dippie)).
* Hippy? Would match "Dippy". Although "Hippie" has the most support in usage and prescription (on [wiktionary](https://en.wiktionary.org/wiki/hippie) and [English stackexchange](https://english.stackexchange.com/questions/227992/of-yuppies-and-yippies-and-hippies))
+ And yet [Google suggests](http://google.com/search?q=hippie+dippy+baloney+lego) "**Hippy** Dippy Baloney Lego" for a "**Hippie** Dippy Baloney Lego" search, as if "Hippie" were misspelled based on the comparative number of search results.
* Dippie? Would match "Hippie".
+ And yet scarce presence [among Internet dictionaries](http://google.com/search?q=dippie+in+a+dictionary).
+ Whereas [Dippy](http://en.wiktionary.org/wiki/dippy)
* Baloney? Far more common in usage and [growing in dictionary acceptance](https://en.wiktionary.org/wiki/baloney).
* Dash between hippie and dippy? Dash between all three?
The question is: How best to spell "Hippie-Dippie Baloney"? | 2015/12/14 | [
"https://english.stackexchange.com/questions/293927",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/151541/"
] | >
> ’Tis one thing to be tempted, Escalus,
> Another thing to fall. *(Measure for Measure* 2.1.17–18)
>
>
>
The coordinate pairing of infinitives in this construction is so well established that a reader is likely to reach the end of your first sentence waiting for the other shoe to drop. Your then beginning the second with a *to* infinitive *of purpose* is thus a kind of [garden path](https://en.wikipedia.org/wiki/Garden_path_sentence). It is grammatically perfectly correct, but not as foolproof for your reader as you can and should make it. | >
> It is one thing to *X* but another to *Y*
>
>
>
Often means things like:
* *X* may be good, but *Y* is much better (or: *X* may be bad, but *Y* is much worse)
* Don't mistake *X* for *Y*
* Don't overestimate *X* / let *X* impress you
* Don't underestimate or disregard *Y*
The author of your example sentence implies that although "passively learn[ing] about all of those various commands" may be worthwhile by itself, it can lead you to think you understand more than you really do, and you won't truly understand until you try out all those various commands yourself. In other words, you can't expect to be successful if you only rely on passive learning.
Also, "in order to" is implied in your example sentence. It makes perfect sense when inserted into the sentence:
>
> It is one thing to passively learn about all those various commands ... but **in order to** fully appreciate how and when to use each one, I need to try them out in my own code.
>
>
> |
293,927 | Because while that is technically the correct spelling for each word, but as a phrase it doesn't seem to work well together. It lacks symmetry (Hipp**ie** vs. Dipp**y**) and uses the extremely rare-yet-proper Italian "bologna".
Origin: The phrase is used with delightful comic effect in [*The Lego Movie*](http://www.imdb.com/title/tt1490017/) and quoted on [wikiquote](https://en.wikiquote.org/wiki/The_Lego_Movie#Lord_Business) as "hippie, dippy baloney".
Consider:
* "Hippie-dippie" for symmetry? [Merriam-Webster](http://www.merriam-webster.com/dictionary/hippie-dippie) supports it. (Wiktionary includes it as [a short entry](https://en.wiktionary.org/wiki/hippie-dippie)).
* Hippy? Would match "Dippy". Although "Hippie" has the most support in usage and prescription (on [wiktionary](https://en.wiktionary.org/wiki/hippie) and [English stackexchange](https://english.stackexchange.com/questions/227992/of-yuppies-and-yippies-and-hippies))
+ And yet [Google suggests](http://google.com/search?q=hippie+dippy+baloney+lego) "**Hippy** Dippy Baloney Lego" for a "**Hippie** Dippy Baloney Lego" search, as if "Hippie" were misspelled based on the comparative number of search results.
* Dippie? Would match "Hippie".
+ And yet scarce presence [among Internet dictionaries](http://google.com/search?q=dippie+in+a+dictionary).
+ Whereas [Dippy](http://en.wiktionary.org/wiki/dippy)
* Baloney? Far more common in usage and [growing in dictionary acceptance](https://en.wiktionary.org/wiki/baloney).
* Dash between hippie and dippy? Dash between all three?
The question is: How best to spell "Hippie-Dippie Baloney"? | 2015/12/14 | [
"https://english.stackexchange.com/questions/293927",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/151541/"
] | "It is one thing to (blank), but another to (blank)" is a comparative structure.
Taking a cue from your example, it would make more sense to say something like "It is one thing to learn passively, but another to understand the material."
It's used specifically when you're comparing two things, with the second of them being the more important half of the pairing. [(Macmillan)](http://www.macmillandictionary.com/us/dictionary/american/it-s-one-thing-to-it-s-another-a-different-thing-to) | It seems that you want to use unsuccessfully two constructions combined
“It is one thing to passively learn about all those various commands in JavaScript by poring over online materials. However, in order to fully appreciate how and when to use each one, I need to try them out in my own code and have them corrected by someone in the know.”
“It is one thing to passively learn about all those various commands in JavaScript by poring over online materials, but to fully appreciate how and when to use each one, I need to try them out in my own code and have them corrected by someone in the know.”
You are using a shortcut for no particular reason.
First solution is ok. It gives you a rest after one long sentence for approaching another long sentence.
Second one is stressing the importance of the second sentence, you want a reader to concentrate and grasp the complete meaning, compare two choices you are trying to explain. You are building a momentum.
It is up to you which one you like better, but your solution is really neither one nor the other. |
293,927 | Because while that is technically the correct spelling for each word, but as a phrase it doesn't seem to work well together. It lacks symmetry (Hipp**ie** vs. Dipp**y**) and uses the extremely rare-yet-proper Italian "bologna".
Origin: The phrase is used with delightful comic effect in [*The Lego Movie*](http://www.imdb.com/title/tt1490017/) and quoted on [wikiquote](https://en.wikiquote.org/wiki/The_Lego_Movie#Lord_Business) as "hippie, dippy baloney".
Consider:
* "Hippie-dippie" for symmetry? [Merriam-Webster](http://www.merriam-webster.com/dictionary/hippie-dippie) supports it. (Wiktionary includes it as [a short entry](https://en.wiktionary.org/wiki/hippie-dippie)).
* Hippy? Would match "Dippy". Although "Hippie" has the most support in usage and prescription (on [wiktionary](https://en.wiktionary.org/wiki/hippie) and [English stackexchange](https://english.stackexchange.com/questions/227992/of-yuppies-and-yippies-and-hippies))
+ And yet [Google suggests](http://google.com/search?q=hippie+dippy+baloney+lego) "**Hippy** Dippy Baloney Lego" for a "**Hippie** Dippy Baloney Lego" search, as if "Hippie" were misspelled based on the comparative number of search results.
* Dippie? Would match "Hippie".
+ And yet scarce presence [among Internet dictionaries](http://google.com/search?q=dippie+in+a+dictionary).
+ Whereas [Dippy](http://en.wiktionary.org/wiki/dippy)
* Baloney? Far more common in usage and [growing in dictionary acceptance](https://en.wiktionary.org/wiki/baloney).
* Dash between hippie and dippy? Dash between all three?
The question is: How best to spell "Hippie-Dippie Baloney"? | 2015/12/14 | [
"https://english.stackexchange.com/questions/293927",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/151541/"
] | "It is one thing to (blank), but another to (blank)" is a comparative structure.
Taking a cue from your example, it would make more sense to say something like "It is one thing to learn passively, but another to understand the material."
It's used specifically when you're comparing two things, with the second of them being the more important half of the pairing. [(Macmillan)](http://www.macmillandictionary.com/us/dictionary/american/it-s-one-thing-to-it-s-another-a-different-thing-to) | First, it is always awkward to have anything between to and the infinitive as we were told in grammar school. Secondly, the comparison should form a somewhat sharp contrast rather than two similar but slightly different things. My example is this: "It is one thing for a person to own what he has created; it is another for him to stop others from copying it." |
293,927 | Because while that is technically the correct spelling for each word, but as a phrase it doesn't seem to work well together. It lacks symmetry (Hipp**ie** vs. Dipp**y**) and uses the extremely rare-yet-proper Italian "bologna".
Origin: The phrase is used with delightful comic effect in [*The Lego Movie*](http://www.imdb.com/title/tt1490017/) and quoted on [wikiquote](https://en.wikiquote.org/wiki/The_Lego_Movie#Lord_Business) as "hippie, dippy baloney".
Consider:
* "Hippie-dippie" for symmetry? [Merriam-Webster](http://www.merriam-webster.com/dictionary/hippie-dippie) supports it. (Wiktionary includes it as [a short entry](https://en.wiktionary.org/wiki/hippie-dippie)).
* Hippy? Would match "Dippy". Although "Hippie" has the most support in usage and prescription (on [wiktionary](https://en.wiktionary.org/wiki/hippie) and [English stackexchange](https://english.stackexchange.com/questions/227992/of-yuppies-and-yippies-and-hippies))
+ And yet [Google suggests](http://google.com/search?q=hippie+dippy+baloney+lego) "**Hippy** Dippy Baloney Lego" for a "**Hippie** Dippy Baloney Lego" search, as if "Hippie" were misspelled based on the comparative number of search results.
* Dippie? Would match "Hippie".
+ And yet scarce presence [among Internet dictionaries](http://google.com/search?q=dippie+in+a+dictionary).
+ Whereas [Dippy](http://en.wiktionary.org/wiki/dippy)
* Baloney? Far more common in usage and [growing in dictionary acceptance](https://en.wiktionary.org/wiki/baloney).
* Dash between hippie and dippy? Dash between all three?
The question is: How best to spell "Hippie-Dippie Baloney"? | 2015/12/14 | [
"https://english.stackexchange.com/questions/293927",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/151541/"
] | "It is one thing to (blank), but another to (blank)" is a comparative structure.
Taking a cue from your example, it would make more sense to say something like "It is one thing to learn passively, but another to understand the material."
It's used specifically when you're comparing two things, with the second of them being the more important half of the pairing. [(Macmillan)](http://www.macmillandictionary.com/us/dictionary/american/it-s-one-thing-to-it-s-another-a-different-thing-to) | >
> It is one thing to *X* but another to *Y*
>
>
>
Often means things like:
* *X* may be good, but *Y* is much better (or: *X* may be bad, but *Y* is much worse)
* Don't mistake *X* for *Y*
* Don't overestimate *X* / let *X* impress you
* Don't underestimate or disregard *Y*
The author of your example sentence implies that although "passively learn[ing] about all of those various commands" may be worthwhile by itself, it can lead you to think you understand more than you really do, and you won't truly understand until you try out all those various commands yourself. In other words, you can't expect to be successful if you only rely on passive learning.
Also, "in order to" is implied in your example sentence. It makes perfect sense when inserted into the sentence:
>
> It is one thing to passively learn about all those various commands ... but **in order to** fully appreciate how and when to use each one, I need to try them out in my own code.
>
>
> |
293,927 | Because while that is technically the correct spelling for each word, but as a phrase it doesn't seem to work well together. It lacks symmetry (Hipp**ie** vs. Dipp**y**) and uses the extremely rare-yet-proper Italian "bologna".
Origin: The phrase is used with delightful comic effect in [*The Lego Movie*](http://www.imdb.com/title/tt1490017/) and quoted on [wikiquote](https://en.wikiquote.org/wiki/The_Lego_Movie#Lord_Business) as "hippie, dippy baloney".
Consider:
* "Hippie-dippie" for symmetry? [Merriam-Webster](http://www.merriam-webster.com/dictionary/hippie-dippie) supports it. (Wiktionary includes it as [a short entry](https://en.wiktionary.org/wiki/hippie-dippie)).
* Hippy? Would match "Dippy". Although "Hippie" has the most support in usage and prescription (on [wiktionary](https://en.wiktionary.org/wiki/hippie) and [English stackexchange](https://english.stackexchange.com/questions/227992/of-yuppies-and-yippies-and-hippies))
+ And yet [Google suggests](http://google.com/search?q=hippie+dippy+baloney+lego) "**Hippy** Dippy Baloney Lego" for a "**Hippie** Dippy Baloney Lego" search, as if "Hippie" were misspelled based on the comparative number of search results.
* Dippie? Would match "Hippie".
+ And yet scarce presence [among Internet dictionaries](http://google.com/search?q=dippie+in+a+dictionary).
+ Whereas [Dippy](http://en.wiktionary.org/wiki/dippy)
* Baloney? Far more common in usage and [growing in dictionary acceptance](https://en.wiktionary.org/wiki/baloney).
* Dash between hippie and dippy? Dash between all three?
The question is: How best to spell "Hippie-Dippie Baloney"? | 2015/12/14 | [
"https://english.stackexchange.com/questions/293927",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/151541/"
] | It seems that you want to use unsuccessfully two constructions combined
“It is one thing to passively learn about all those various commands in JavaScript by poring over online materials. However, in order to fully appreciate how and when to use each one, I need to try them out in my own code and have them corrected by someone in the know.”
“It is one thing to passively learn about all those various commands in JavaScript by poring over online materials, but to fully appreciate how and when to use each one, I need to try them out in my own code and have them corrected by someone in the know.”
You are using a shortcut for no particular reason.
First solution is ok. It gives you a rest after one long sentence for approaching another long sentence.
Second one is stressing the importance of the second sentence, you want a reader to concentrate and grasp the complete meaning, compare two choices you are trying to explain. You are building a momentum.
It is up to you which one you like better, but your solution is really neither one nor the other. | First, it is always awkward to have anything between to and the infinitive as we were told in grammar school. Secondly, the comparison should form a somewhat sharp contrast rather than two similar but slightly different things. My example is this: "It is one thing for a person to own what he has created; it is another for him to stop others from copying it." |
293,927 | Because while that is technically the correct spelling for each word, but as a phrase it doesn't seem to work well together. It lacks symmetry (Hipp**ie** vs. Dipp**y**) and uses the extremely rare-yet-proper Italian "bologna".
Origin: The phrase is used with delightful comic effect in [*The Lego Movie*](http://www.imdb.com/title/tt1490017/) and quoted on [wikiquote](https://en.wikiquote.org/wiki/The_Lego_Movie#Lord_Business) as "hippie, dippy baloney".
Consider:
* "Hippie-dippie" for symmetry? [Merriam-Webster](http://www.merriam-webster.com/dictionary/hippie-dippie) supports it. (Wiktionary includes it as [a short entry](https://en.wiktionary.org/wiki/hippie-dippie)).
* Hippy? Would match "Dippy". Although "Hippie" has the most support in usage and prescription (on [wiktionary](https://en.wiktionary.org/wiki/hippie) and [English stackexchange](https://english.stackexchange.com/questions/227992/of-yuppies-and-yippies-and-hippies))
+ And yet [Google suggests](http://google.com/search?q=hippie+dippy+baloney+lego) "**Hippy** Dippy Baloney Lego" for a "**Hippie** Dippy Baloney Lego" search, as if "Hippie" were misspelled based on the comparative number of search results.
* Dippie? Would match "Hippie".
+ And yet scarce presence [among Internet dictionaries](http://google.com/search?q=dippie+in+a+dictionary).
+ Whereas [Dippy](http://en.wiktionary.org/wiki/dippy)
* Baloney? Far more common in usage and [growing in dictionary acceptance](https://en.wiktionary.org/wiki/baloney).
* Dash between hippie and dippy? Dash between all three?
The question is: How best to spell "Hippie-Dippie Baloney"? | 2015/12/14 | [
"https://english.stackexchange.com/questions/293927",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/151541/"
] | >
> It is one thing to *X* but another to *Y*
>
>
>
Often means things like:
* *X* may be good, but *Y* is much better (or: *X* may be bad, but *Y* is much worse)
* Don't mistake *X* for *Y*
* Don't overestimate *X* / let *X* impress you
* Don't underestimate or disregard *Y*
The author of your example sentence implies that although "passively learn[ing] about all of those various commands" may be worthwhile by itself, it can lead you to think you understand more than you really do, and you won't truly understand until you try out all those various commands yourself. In other words, you can't expect to be successful if you only rely on passive learning.
Also, "in order to" is implied in your example sentence. It makes perfect sense when inserted into the sentence:
>
> It is one thing to passively learn about all those various commands ... but **in order to** fully appreciate how and when to use each one, I need to try them out in my own code.
>
>
> | First, it is always awkward to have anything between to and the infinitive as we were told in grammar school. Secondly, the comparison should form a somewhat sharp contrast rather than two similar but slightly different things. My example is this: "It is one thing for a person to own what he has created; it is another for him to stop others from copying it." |
22,044 | After some unsuccessful uploads I ended up with a lot of loose files in craft/storage/runtime/assets/tempuploads
They show up in the asset list when selecting assets for new entry. How do I remove them completely from the record?
Tried manually deleting them via FTP and running "Update Asset Indexes" but that didn't work. Also tried "Clear Caches" options. | 2017/09/19 | [
"https://craftcms.stackexchange.com/questions/22044",
"https://craftcms.stackexchange.com",
"https://craftcms.stackexchange.com/users/7082/"
] | In Craft 2 the only real solution is to delete all the entries from craft\_assetfiles where the sourceId is set to `null`.
The reason why there's no clear cache tool for these is because that might allow for deletion of Assets that were just uploaded by someone else who might be about to use them.
This is really far from a practical solution and we know that, but it's not easily improved in Craft 2.
Craft 3 will slightly improve things by adding a "Temporary uploads" Asset volume which will hold all of the current user's *leftover* Assets, allowing you to deal with them as you would with regular Assets. | If you've already deleted the actual files, you can try rebuilding the Asset Index (via Settings -> Update Asset Indexes |
278,674 | Say I use a font "foo" in my TeX document.
>
> \setmainfont{foo}
>
>
>
This font is not free or not widely available on other systems.
Will my PDF document will look same in other computers where this font is not available / installed?
And if not what can I do about it to make sure that it looks same in other computers? | 2015/11/17 | [
"https://tex.stackexchange.com/questions/278674",
"https://tex.stackexchange.com",
"https://tex.stackexchange.com/users/63140/"
] | Fonts are embedded by default when you compile TeX to PDF. To be sure, you may wish to upload your PDF to a cloud, say, GoogleDrive (free) and see, how it looks there in another previewer. | I'm not an expert on PDF, but the whole idea of PDF in opposite to Word is that the viewer displays the same picture and the printer prints the same glyphs on the paper.
Well, more or less. It obviously does not depend on the installation of fonts on the computer you use to display the PDF, but there are differences even between different viewers on the same computer. Compare the display of a PDF by Adobe's Reader and DocView (Emacs!). For an example see here: [Why do fonts look thinner in adobe and different and richer in sumatra pdf](https://tex.stackexchange.com/q/171706/4736)
And think of the properties of the printer. Or: A printout from a dot matrix printer will look completely different from a ink printer. Even laser printer produce very different output.
tl;dr: Your PDF will look quite similar, independently from installed fonts.
---
### Edit:
There seems to be a misunderstanding about the license of commercial fonts. Of course you can use a fonts you bought to produce a PDF. The company which sold the fonts to you has no whatever rights on your PDF! Selling fonts includes the fair use of making a PDF. And making a PDF means that all the needed glyphs become part of the PDF. (I am a lawyer! OK, only in Germany.)
It is something different, if you embedd by using attachfile, embeddfile or whatever the \*.ttf or \*.otf file itself -- this might not be legal!
---
### Edit 2:
There are companies which try to limit the use of sold fonts to a PDF with a circulation of one hundred copies, e.g. the Font Bureau in Florida (thank you, [Thérèse](https://tex.stackexchange.com/users/7883/th%C3%A9r%C3%A8se)). I read the license agreement of some of the fonts I bought and there is no limitation for a PDF, but the lincense of Linotype says:
>
> »Embedding of the Font Software into electronic documents
> or Internet pages is only permitted under the absolute assur-
> ance that the recipient cannot use the Font Software to edit or
> create a new document (read-only). It must be ensured that the
> Font Software cannot be fully or partially extracted from said
> documents.«
>
>
> |
2,624 | There are many questions in philosophy of the following kind:
* Does my friend have a soul, or is my friend a zombie?
* Is the mind separate from the body, or is it the same?
* Where does the universe come from?
These questions have the property that, whatever the hypothetical answer would be, every one of your perceptions of the world is *exactly the same*.
It is a central tenet of Carnap and the positivists that one should consider such questions as meaningless, as an abuse of language. This position answers or moots most of the questions on this site. Positivism was accepted for a while in philosophy, but no longer. I am shocked by this.
Is it still considered correct that a question with no perceptible difference one way or another (like, "Are you a zombie?") is inherently meaningless? Why would anyone assign meaning to such a question? | 2012/04/18 | [
"https://philosophy.stackexchange.com/questions/2624",
"https://philosophy.stackexchange.com",
"https://philosophy.stackexchange.com/users/1370/"
] | >
> These questions have the property that, whatever the hypothetical answer would be, every one of your perceptions of **the world** is exactly the same.
>
>
>
(emphasis mine).
You have imported an assumption here that, I think, explains why all of your examples are problematic.
What precisely do you mean by *the world*? If souls are real, and they (we) exist after death, does *the world* include the post-death environment of the soul, or not? If no, why do you privilege existence-as-soul-plus-corporeal-physical-form above existence-as-soul-in-post-death-environment? If yes, is it *necessarily* true that you have to find evidence pre-death, or can you wait until post-death to make the call?
So I think these are sensible questions to ask, even if, after a long detour that requires one to rethink one's epistemology, one concludes that the answers are, "no zombies or the question is meaningless; the mind is the same as the body or the question is meaningless; the origin of the universe is an insensible question unless you're redefining universe". You don't just (or many people do not) end up there intuitively, so the questions are reasonable to ask even if at the end you conclude, "Well, that was all just confused, wasn't it?" | **"no perceptible difference one way or another"**
To the senses, "no perceptible difference". To the intellect? **Profound** perceptible differences!
Nothing to be shocked about. |
2,624 | There are many questions in philosophy of the following kind:
* Does my friend have a soul, or is my friend a zombie?
* Is the mind separate from the body, or is it the same?
* Where does the universe come from?
These questions have the property that, whatever the hypothetical answer would be, every one of your perceptions of the world is *exactly the same*.
It is a central tenet of Carnap and the positivists that one should consider such questions as meaningless, as an abuse of language. This position answers or moots most of the questions on this site. Positivism was accepted for a while in philosophy, but no longer. I am shocked by this.
Is it still considered correct that a question with no perceptible difference one way or another (like, "Are you a zombie?") is inherently meaningless? Why would anyone assign meaning to such a question? | 2012/04/18 | [
"https://philosophy.stackexchange.com/questions/2624",
"https://philosophy.stackexchange.com",
"https://philosophy.stackexchange.com/users/1370/"
] | It ***can*** be very meaningful, and just *how* meaningful will vary depending on the person and the question. **Even if it doesn't alter the observable (physical) world** ("your perceptions of the world"), **it is still meaningful if it alters *human behavior*.** In fact, it is strange to me that you don't seem to consider human behavior as a "perceptible difference" of the world.
Consider:
Does God exist?
---------------
* If God **does** exist, then the way things are in the world is exactly as he planned. He is here and has always been here.
* If God **does *not*** exist, then the world keeps on ticking, exactly as it has this whole time.
However, while the ***world/universe*** doesn't change, **our behavior towards the world can change**. For example, if I was provided solid evidence for the existence of God, I would radically change my life in order to conform to his will (if we are talking about the Christian God, perhaps I would start praying, repent for my sins, attend Church more, etc.). | **"no perceptible difference one way or another"**
To the senses, "no perceptible difference". To the intellect? **Profound** perceptible differences!
Nothing to be shocked about. |
2,624 | There are many questions in philosophy of the following kind:
* Does my friend have a soul, or is my friend a zombie?
* Is the mind separate from the body, or is it the same?
* Where does the universe come from?
These questions have the property that, whatever the hypothetical answer would be, every one of your perceptions of the world is *exactly the same*.
It is a central tenet of Carnap and the positivists that one should consider such questions as meaningless, as an abuse of language. This position answers or moots most of the questions on this site. Positivism was accepted for a while in philosophy, but no longer. I am shocked by this.
Is it still considered correct that a question with no perceptible difference one way or another (like, "Are you a zombie?") is inherently meaningless? Why would anyone assign meaning to such a question? | 2012/04/18 | [
"https://philosophy.stackexchange.com/questions/2624",
"https://philosophy.stackexchange.com",
"https://philosophy.stackexchange.com/users/1370/"
] | >
> These questions have the property that, whatever the hypothetical answer would be, every one of your perceptions of **the world** is exactly the same.
>
>
>
(emphasis mine).
You have imported an assumption here that, I think, explains why all of your examples are problematic.
What precisely do you mean by *the world*? If souls are real, and they (we) exist after death, does *the world* include the post-death environment of the soul, or not? If no, why do you privilege existence-as-soul-plus-corporeal-physical-form above existence-as-soul-in-post-death-environment? If yes, is it *necessarily* true that you have to find evidence pre-death, or can you wait until post-death to make the call?
So I think these are sensible questions to ask, even if, after a long detour that requires one to rethink one's epistemology, one concludes that the answers are, "no zombies or the question is meaningless; the mind is the same as the body or the question is meaningless; the origin of the universe is an insensible question unless you're redefining universe". You don't just (or many people do not) end up there intuitively, so the questions are reasonable to ask even if at the end you conclude, "Well, that was all just confused, wasn't it?" | It ***can*** be very meaningful, and just *how* meaningful will vary depending on the person and the question. **Even if it doesn't alter the observable (physical) world** ("your perceptions of the world"), **it is still meaningful if it alters *human behavior*.** In fact, it is strange to me that you don't seem to consider human behavior as a "perceptible difference" of the world.
Consider:
Does God exist?
---------------
* If God **does** exist, then the way things are in the world is exactly as he planned. He is here and has always been here.
* If God **does *not*** exist, then the world keeps on ticking, exactly as it has this whole time.
However, while the ***world/universe*** doesn't change, **our behavior towards the world can change**. For example, if I was provided solid evidence for the existence of God, I would radically change my life in order to conform to his will (if we are talking about the Christian God, perhaps I would start praying, repent for my sins, attend Church more, etc.). |
2,624 | There are many questions in philosophy of the following kind:
* Does my friend have a soul, or is my friend a zombie?
* Is the mind separate from the body, or is it the same?
* Where does the universe come from?
These questions have the property that, whatever the hypothetical answer would be, every one of your perceptions of the world is *exactly the same*.
It is a central tenet of Carnap and the positivists that one should consider such questions as meaningless, as an abuse of language. This position answers or moots most of the questions on this site. Positivism was accepted for a while in philosophy, but no longer. I am shocked by this.
Is it still considered correct that a question with no perceptible difference one way or another (like, "Are you a zombie?") is inherently meaningless? Why would anyone assign meaning to such a question? | 2012/04/18 | [
"https://philosophy.stackexchange.com/questions/2624",
"https://philosophy.stackexchange.com",
"https://philosophy.stackexchange.com/users/1370/"
] | I think that methaphysical theories (non testable in principle) are necessary and important to scientific research because they may be capable of becoming physical (testable in principle) theories.
Of course, if you understand clearly that your answers are completely equivalent experimentally, then you are saying just the same in different ways, you get into a purely formal ground, like when we state the equivalence of two different formulations of the same physical theory; but it may happen that the possible ways of showing the difference empirically are still not understood - think about the [Aharonov–Bohm effect](https://en.wikipedia.org/wiki/Aharonov%E2%80%93Bohm_effect#Potentials_vs._fields), e.g. | **"no perceptible difference one way or another"**
To the senses, "no perceptible difference". To the intellect? **Profound** perceptible differences!
Nothing to be shocked about. |
2,624 | There are many questions in philosophy of the following kind:
* Does my friend have a soul, or is my friend a zombie?
* Is the mind separate from the body, or is it the same?
* Where does the universe come from?
These questions have the property that, whatever the hypothetical answer would be, every one of your perceptions of the world is *exactly the same*.
It is a central tenet of Carnap and the positivists that one should consider such questions as meaningless, as an abuse of language. This position answers or moots most of the questions on this site. Positivism was accepted for a while in philosophy, but no longer. I am shocked by this.
Is it still considered correct that a question with no perceptible difference one way or another (like, "Are you a zombie?") is inherently meaningless? Why would anyone assign meaning to such a question? | 2012/04/18 | [
"https://philosophy.stackexchange.com/questions/2624",
"https://philosophy.stackexchange.com",
"https://philosophy.stackexchange.com/users/1370/"
] | Logical Positivism, seems to me a philosophy that evolved by taking the scientific viewpoint as the only legitimate way to ask meaningful questions. Its greatest failing is that its not very imaginative. Its an interesting perspective to hold for a while, but to hold it exclusively feels severely limiting.
Also, historically its not even true as to how science developed.
Leucippus came up with the atomic theory without any hope of establishing the truth of his hypothesis until 2 millenia later.
The hypothesis of a spherical Earth, established in antiquity, but not *observationally* verified until the first circumnavigation of the earth. | I think that methaphysical theories (non testable in principle) are necessary and important to scientific research because they may be capable of becoming physical (testable in principle) theories.
Of course, if you understand clearly that your answers are completely equivalent experimentally, then you are saying just the same in different ways, you get into a purely formal ground, like when we state the equivalence of two different formulations of the same physical theory; but it may happen that the possible ways of showing the difference empirically are still not understood - think about the [Aharonov–Bohm effect](https://en.wikipedia.org/wiki/Aharonov%E2%80%93Bohm_effect#Potentials_vs._fields), e.g. |
2,624 | There are many questions in philosophy of the following kind:
* Does my friend have a soul, or is my friend a zombie?
* Is the mind separate from the body, or is it the same?
* Where does the universe come from?
These questions have the property that, whatever the hypothetical answer would be, every one of your perceptions of the world is *exactly the same*.
It is a central tenet of Carnap and the positivists that one should consider such questions as meaningless, as an abuse of language. This position answers or moots most of the questions on this site. Positivism was accepted for a while in philosophy, but no longer. I am shocked by this.
Is it still considered correct that a question with no perceptible difference one way or another (like, "Are you a zombie?") is inherently meaningless? Why would anyone assign meaning to such a question? | 2012/04/18 | [
"https://philosophy.stackexchange.com/questions/2624",
"https://philosophy.stackexchange.com",
"https://philosophy.stackexchange.com/users/1370/"
] | >
> These questions have the property that, whatever the hypothetical answer would be, every one of your perceptions of the world is exactly the same.
>
>
>
That is absolutely untrue. My perception of the world might be profoundly different if I knew with certainty information regarding the existence of souls, or the independence of mind from body, or the source of the universe.
These are not trivial matters.
One could just as easily say that it makes no difference whether string theory is correct or not, as it makes no perceptible difference to one's life.
>
> Is it still considered correct that a question with no perceptible difference one way or another [...] is inherently meaningless?
>
>
>
Could you provide a legitimate example of a question with *no perceptible difference one way or another*?
>
> Positivism was accepted for a while in philosophy, but no longer. I am shocked by this.
>
>
>
Why does this shock you? There have been many critiques of positivism, and virtually everybody (including many former positivists) believe that philosophy has moved forward since positivism's heyday. A.J. Ayer, in fact, famously said "I suppose the most important [defect]...was that nearly all of it was false." | I think that methaphysical theories (non testable in principle) are necessary and important to scientific research because they may be capable of becoming physical (testable in principle) theories.
Of course, if you understand clearly that your answers are completely equivalent experimentally, then you are saying just the same in different ways, you get into a purely formal ground, like when we state the equivalence of two different formulations of the same physical theory; but it may happen that the possible ways of showing the difference empirically are still not understood - think about the [Aharonov–Bohm effect](https://en.wikipedia.org/wiki/Aharonov%E2%80%93Bohm_effect#Potentials_vs._fields), e.g. |
2,624 | There are many questions in philosophy of the following kind:
* Does my friend have a soul, or is my friend a zombie?
* Is the mind separate from the body, or is it the same?
* Where does the universe come from?
These questions have the property that, whatever the hypothetical answer would be, every one of your perceptions of the world is *exactly the same*.
It is a central tenet of Carnap and the positivists that one should consider such questions as meaningless, as an abuse of language. This position answers or moots most of the questions on this site. Positivism was accepted for a while in philosophy, but no longer. I am shocked by this.
Is it still considered correct that a question with no perceptible difference one way or another (like, "Are you a zombie?") is inherently meaningless? Why would anyone assign meaning to such a question? | 2012/04/18 | [
"https://philosophy.stackexchange.com/questions/2624",
"https://philosophy.stackexchange.com",
"https://philosophy.stackexchange.com/users/1370/"
] | It ***can*** be very meaningful, and just *how* meaningful will vary depending on the person and the question. **Even if it doesn't alter the observable (physical) world** ("your perceptions of the world"), **it is still meaningful if it alters *human behavior*.** In fact, it is strange to me that you don't seem to consider human behavior as a "perceptible difference" of the world.
Consider:
Does God exist?
---------------
* If God **does** exist, then the way things are in the world is exactly as he planned. He is here and has always been here.
* If God **does *not*** exist, then the world keeps on ticking, exactly as it has this whole time.
However, while the ***world/universe*** doesn't change, **our behavior towards the world can change**. For example, if I was provided solid evidence for the existence of God, I would radically change my life in order to conform to his will (if we are talking about the Christian God, perhaps I would start praying, repent for my sins, attend Church more, etc.). | I think that methaphysical theories (non testable in principle) are necessary and important to scientific research because they may be capable of becoming physical (testable in principle) theories.
Of course, if you understand clearly that your answers are completely equivalent experimentally, then you are saying just the same in different ways, you get into a purely formal ground, like when we state the equivalence of two different formulations of the same physical theory; but it may happen that the possible ways of showing the difference empirically are still not understood - think about the [Aharonov–Bohm effect](https://en.wikipedia.org/wiki/Aharonov%E2%80%93Bohm_effect#Potentials_vs._fields), e.g. |
2,624 | There are many questions in philosophy of the following kind:
* Does my friend have a soul, or is my friend a zombie?
* Is the mind separate from the body, or is it the same?
* Where does the universe come from?
These questions have the property that, whatever the hypothetical answer would be, every one of your perceptions of the world is *exactly the same*.
It is a central tenet of Carnap and the positivists that one should consider such questions as meaningless, as an abuse of language. This position answers or moots most of the questions on this site. Positivism was accepted for a while in philosophy, but no longer. I am shocked by this.
Is it still considered correct that a question with no perceptible difference one way or another (like, "Are you a zombie?") is inherently meaningless? Why would anyone assign meaning to such a question? | 2012/04/18 | [
"https://philosophy.stackexchange.com/questions/2624",
"https://philosophy.stackexchange.com",
"https://philosophy.stackexchange.com/users/1370/"
] | Logical Positivism, seems to me a philosophy that evolved by taking the scientific viewpoint as the only legitimate way to ask meaningful questions. Its greatest failing is that its not very imaginative. Its an interesting perspective to hold for a while, but to hold it exclusively feels severely limiting.
Also, historically its not even true as to how science developed.
Leucippus came up with the atomic theory without any hope of establishing the truth of his hypothesis until 2 millenia later.
The hypothesis of a spherical Earth, established in antiquity, but not *observationally* verified until the first circumnavigation of the earth. | **"no perceptible difference one way or another"**
To the senses, "no perceptible difference". To the intellect? **Profound** perceptible differences!
Nothing to be shocked about. |
2,624 | There are many questions in philosophy of the following kind:
* Does my friend have a soul, or is my friend a zombie?
* Is the mind separate from the body, or is it the same?
* Where does the universe come from?
These questions have the property that, whatever the hypothetical answer would be, every one of your perceptions of the world is *exactly the same*.
It is a central tenet of Carnap and the positivists that one should consider such questions as meaningless, as an abuse of language. This position answers or moots most of the questions on this site. Positivism was accepted for a while in philosophy, but no longer. I am shocked by this.
Is it still considered correct that a question with no perceptible difference one way or another (like, "Are you a zombie?") is inherently meaningless? Why would anyone assign meaning to such a question? | 2012/04/18 | [
"https://philosophy.stackexchange.com/questions/2624",
"https://philosophy.stackexchange.com",
"https://philosophy.stackexchange.com/users/1370/"
] | >
> These questions have the property that, whatever the hypothetical answer would be, every one of your perceptions of the world is exactly the same.
>
>
>
That is absolutely untrue. My perception of the world might be profoundly different if I knew with certainty information regarding the existence of souls, or the independence of mind from body, or the source of the universe.
These are not trivial matters.
One could just as easily say that it makes no difference whether string theory is correct or not, as it makes no perceptible difference to one's life.
>
> Is it still considered correct that a question with no perceptible difference one way or another [...] is inherently meaningless?
>
>
>
Could you provide a legitimate example of a question with *no perceptible difference one way or another*?
>
> Positivism was accepted for a while in philosophy, but no longer. I am shocked by this.
>
>
>
Why does this shock you? There have been many critiques of positivism, and virtually everybody (including many former positivists) believe that philosophy has moved forward since positivism's heyday. A.J. Ayer, in fact, famously said "I suppose the most important [defect]...was that nearly all of it was false." | **"no perceptible difference one way or another"**
To the senses, "no perceptible difference". To the intellect? **Profound** perceptible differences!
Nothing to be shocked about. |
2,624 | There are many questions in philosophy of the following kind:
* Does my friend have a soul, or is my friend a zombie?
* Is the mind separate from the body, or is it the same?
* Where does the universe come from?
These questions have the property that, whatever the hypothetical answer would be, every one of your perceptions of the world is *exactly the same*.
It is a central tenet of Carnap and the positivists that one should consider such questions as meaningless, as an abuse of language. This position answers or moots most of the questions on this site. Positivism was accepted for a while in philosophy, but no longer. I am shocked by this.
Is it still considered correct that a question with no perceptible difference one way or another (like, "Are you a zombie?") is inherently meaningless? Why would anyone assign meaning to such a question? | 2012/04/18 | [
"https://philosophy.stackexchange.com/questions/2624",
"https://philosophy.stackexchange.com",
"https://philosophy.stackexchange.com/users/1370/"
] | >
> These questions have the property that, whatever the hypothetical answer would be, every one of your perceptions of **the world** is exactly the same.
>
>
>
(emphasis mine).
You have imported an assumption here that, I think, explains why all of your examples are problematic.
What precisely do you mean by *the world*? If souls are real, and they (we) exist after death, does *the world* include the post-death environment of the soul, or not? If no, why do you privilege existence-as-soul-plus-corporeal-physical-form above existence-as-soul-in-post-death-environment? If yes, is it *necessarily* true that you have to find evidence pre-death, or can you wait until post-death to make the call?
So I think these are sensible questions to ask, even if, after a long detour that requires one to rethink one's epistemology, one concludes that the answers are, "no zombies or the question is meaningless; the mind is the same as the body or the question is meaningless; the origin of the universe is an insensible question unless you're redefining universe". You don't just (or many people do not) end up there intuitively, so the questions are reasonable to ask even if at the end you conclude, "Well, that was all just confused, wasn't it?" | Logical Positivism, seems to me a philosophy that evolved by taking the scientific viewpoint as the only legitimate way to ask meaningful questions. Its greatest failing is that its not very imaginative. Its an interesting perspective to hold for a while, but to hold it exclusively feels severely limiting.
Also, historically its not even true as to how science developed.
Leucippus came up with the atomic theory without any hope of establishing the truth of his hypothesis until 2 millenia later.
The hypothesis of a spherical Earth, established in antiquity, but not *observationally* verified until the first circumnavigation of the earth. |
1,311 | I want a writing panel for a custom field called 'Sub-title' and would like it to appear in its logical place in the Page editor (that is, between the title and the Page content). Is that possible?
I would like to avoid having to create a custom post type, since a Page + custom fields is all I really need. | 2010/09/03 | [
"https://wordpress.stackexchange.com/questions/1311",
"https://wordpress.stackexchange.com",
"https://wordpress.stackexchange.com/users/106/"
] | I am wondering why my first answer was down-voted. :)
I think the only way to do is to add a meta box below the post content field and use javascript to move it above.
This is the way it is done with the slug field in the WordPress core (the slug field is were you edit the page or post url). Disable javascript in your browser and you will see the slug field at the bottom of the page.
If WordPress does it with javascript, I think the best way to do it is javascript too. As, I can't see any hook between the title and content fields which will allow it to be done without using javascript. | You can add it below the content area and use javascript code to move it above it. |
1,311 | I want a writing panel for a custom field called 'Sub-title' and would like it to appear in its logical place in the Page editor (that is, between the title and the Page content). Is that possible?
I would like to avoid having to create a custom post type, since a Page + custom fields is all I really need. | 2010/09/03 | [
"https://wordpress.stackexchange.com/questions/1311",
"https://wordpress.stackexchange.com",
"https://wordpress.stackexchange.com/users/106/"
] | I am wondering why my first answer was down-voted. :)
I think the only way to do is to add a meta box below the post content field and use javascript to move it above.
This is the way it is done with the slug field in the WordPress core (the slug field is were you edit the page or post url). Disable javascript in your browser and you will see the slug field at the bottom of the page.
If WordPress does it with javascript, I think the best way to do it is javascript too. As, I can't see any hook between the title and content fields which will allow it to be done without using javascript. | You could have a look at the excellent qTranslate. That should provide you with an example of everything you need since it adds a.o. multiple Title boxes. |
1,311 | I want a writing panel for a custom field called 'Sub-title' and would like it to appear in its logical place in the Page editor (that is, between the title and the Page content). Is that possible?
I would like to avoid having to create a custom post type, since a Page + custom fields is all I really need. | 2010/09/03 | [
"https://wordpress.stackexchange.com/questions/1311",
"https://wordpress.stackexchange.com",
"https://wordpress.stackexchange.com/users/106/"
] | I am wondering why my first answer was down-voted. :)
I think the only way to do is to add a meta box below the post content field and use javascript to move it above.
This is the way it is done with the slug field in the WordPress core (the slug field is were you edit the page or post url). Disable javascript in your browser and you will see the slug field at the bottom of the page.
If WordPress does it with javascript, I think the best way to do it is javascript too. As, I can't see any hook between the title and content fields which will allow it to be done without using javascript. | To the best of my knowledge the priority of a meta box is limited to: Low, Default and High. Which is unlike admin menus that let you specify a value and put it anywhere. I'd try "High."
You can change the order of all your meta boxes by dragging and dropping so where ever High puts the subtitle you can drag it to be beneath the Title. The only disadvantage is that you'd have to do it for every user. There are plugins like Adminize that let you specify the order of meta boxes for all user accounts which would overcome this problem.
**Create Subtitle Meta box:** www.spencerfinnell.com/2010/07/05/wordpress-custom-write-panels/
**Adminize Plugin:** wordpress.org/extend/plugins/adminimize/
\**I don't have a high enough rank to post links so you'll have to copy and paste* |
320,304 | I will go on a site where is a HP PSC 1350 printer but no internet connection. I understand that there is no driver for download available from HP and it will connect to WinUpdate once connected the printer with USB. But there will be no Internet. Any chance to get the driver without connection to the printer ? | 2011/08/07 | [
"https://superuser.com/questions/320304",
"https://superuser.com",
"https://superuser.com/users/11334/"
] | Why can't you download the driver from HP and put it on a CD-ROM or usb stick?
[hp link to download driver](http://h10025.www1.hp.com/ewfrf/wc/softwareCategory?product=306888&lc=en&cc=us&dlc=en&lang=en&cc=us) | Contact HP to see what options they may have in this situation. They may be able to get you a physical disk, possibly for a small handling fee. |
178,459 | Sometimes I'm on call for work overnight and would like to know a quick way that I can silence all notifications except for the call ringer. The closest thing I see is allowing calls from everyone on do not disturb but that will allow messages to ring as well. | 2015/03/27 | [
"https://apple.stackexchange.com/questions/178459",
"https://apple.stackexchange.com",
"https://apple.stackexchange.com/users/119721/"
] | Actually, Do Not Disturb is indeed your solution as it blocks ALL notifications EXCEPT the calls which you specifically allow. It will block message notifications.
After you have configured the settings in Settings -> Do Not Disturb, all you need to do to enable it is swipe up from the bottom of the screen and tap the moon icon.
You can configure it to only allow certain contact groups, favorites, all callers, and/or repeated calls. | You can also head to Settings->Sounds->Text Tone and set tone and vibration there. You can configure texts for no sound and/or no vibration. Similarly, you can allow ALL calls (from any number) to ring as you have set in Settings->Sounds->Ringtone
I was just dealing with the same issue as I expect and need to hear work calls (any number) but can't have my phone buzzing from a bunch of texts all the time. |
178,459 | Sometimes I'm on call for work overnight and would like to know a quick way that I can silence all notifications except for the call ringer. The closest thing I see is allowing calls from everyone on do not disturb but that will allow messages to ring as well. | 2015/03/27 | [
"https://apple.stackexchange.com/questions/178459",
"https://apple.stackexchange.com",
"https://apple.stackexchange.com/users/119721/"
] | Actually, Do Not Disturb is indeed your solution as it blocks ALL notifications EXCEPT the calls which you specifically allow. It will block message notifications.
After you have configured the settings in Settings -> Do Not Disturb, all you need to do to enable it is swipe up from the bottom of the screen and tap the moon icon.
You can configure it to only allow certain contact groups, favorites, all callers, and/or repeated calls. | Try and place your do not disturb button on, "ON" and that would just allow your phone to ring and will block all other incoming notifications.
I have iphone 7 |
178,459 | Sometimes I'm on call for work overnight and would like to know a quick way that I can silence all notifications except for the call ringer. The closest thing I see is allowing calls from everyone on do not disturb but that will allow messages to ring as well. | 2015/03/27 | [
"https://apple.stackexchange.com/questions/178459",
"https://apple.stackexchange.com",
"https://apple.stackexchange.com/users/119721/"
] | Actually, Do Not Disturb is indeed your solution as it blocks ALL notifications EXCEPT the calls which you specifically allow. It will block message notifications.
After you have configured the settings in Settings -> Do Not Disturb, all you need to do to enable it is swipe up from the bottom of the screen and tap the moon icon.
You can configure it to only allow certain contact groups, favorites, all callers, and/or repeated calls. | With the 7/7 Plus you simply engage Do Not Disturb and select "Allow Calls" from "Everyone". Nice and easy. |
66,486 | I have Dropbox installed on my Mac with OS X Lion 10.8.2. I don't use it often, so I eliminated it from the login item list. However, every time I open Dropbox from the application folder, it automatically add itself to the login item list. Is that normal, even if I locked changes? Can I prevent Dropbox to add itself to my item list every time I open it? | 2012/10/06 | [
"https://apple.stackexchange.com/questions/66486",
"https://apple.stackexchange.com",
"https://apple.stackexchange.com/users/-1/"
] | Under Dropbox preferences, there is a checkbox for "Start Dropbox on System Startup".
However, as patrix says, Dropbox is really only useful if you leave it running all the time. | The idea of Dropbox is to always sync files across all your devices in the background. So disabling the login item doesn't really make sense from a Dropbox point of view. And at least at first glance I don't see significant drawbacks from keeping it there either.
If you just want to access some files in your Dropbox account you could use the web interface instead. |
172,671 | According to the Wikipedia page for the [Oxford Comma](http://en.wikipedia.org/wiki/Serial_comma#Arguments_for_and_against), "Use of the comma is consistent with conventional practice" and "Use of the comma is inconsistent with conventional practice." Did the Oxford Comma come before its omission, or was the Oxford Comma traditionally omitted?
It makes logical sense that every item in a list would be separated in the same way: by a comma. If the Oxford Comma is conventionally correct, when and why did people begin to omit it? | 2014/05/24 | [
"https://english.stackexchange.com/questions/172671",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/-1/"
] | There are situations where use of the [Oxford comma](https://en.wikipedia.org/wiki/Serial_comma "(a.k.a. serial comma or series comma)") will make or break a sentence.
**Choose a style and *be consistent*.** When you run into a situation in which your choice suggests a misinterpretation of the sentence, rewrite it in another manner to avoid the confusion.
Consider these two pairs where the Oxford comma makes (1) or breaks (2) the intention:
>
> **Oxford comma:**
>
>
> 1. *We invited the strippers, JFK, and Stalin.* = Strippers and JFK and Stalin.
> 2. *We invited the stripper, JFK, and Stalin.* = JFK (the stripper) and Stalin.
>
>
> **No Oxford comma:**
>
>
> 1. *We invited the strippers, JFK and Stalin.* = Strippers named JFK and Stalin.
> 2. *We invited the stripper, JFK and Stalin.* = Stripper and JFK and Stalin.
>
>
>
A picture (from [Joe Kessler's blog](http://lesserjoke.tumblr.com/post/17114988391/captainrobocop-politicalprof-the-oxford)) to better illustrate this:
[](http://lesserjoke.tumblr.com/post/17114988391/captainrobocop-politicalprof-the-oxford) | I don't have information about the history of this, so I'm just responding to the second part of your question. Why should there be no comma before 'and'? The answer is simple - there has never been a convention for adding a comma (as far as I know) for mentioning two items: *I like apples and oranges* or *She doesn't mind running or swimming*. The problem comes when you want to add a third item: *I like pears, apples and oranges* or *She doesn't mind jogging, running or swimming*. It must seem fussy to people to insist on a comma before 'and' here, if there was no comma for two items. |
172,671 | According to the Wikipedia page for the [Oxford Comma](http://en.wikipedia.org/wiki/Serial_comma#Arguments_for_and_against), "Use of the comma is consistent with conventional practice" and "Use of the comma is inconsistent with conventional practice." Did the Oxford Comma come before its omission, or was the Oxford Comma traditionally omitted?
It makes logical sense that every item in a list would be separated in the same way: by a comma. If the Oxford Comma is conventionally correct, when and why did people begin to omit it? | 2014/05/24 | [
"https://english.stackexchange.com/questions/172671",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/-1/"
] | I don't have information about the history of this, so I'm just responding to the second part of your question. Why should there be no comma before 'and'? The answer is simple - there has never been a convention for adding a comma (as far as I know) for mentioning two items: *I like apples and oranges* or *She doesn't mind running or swimming*. The problem comes when you want to add a third item: *I like pears, apples and oranges* or *She doesn't mind jogging, running or swimming*. It must seem fussy to people to insist on a comma before 'and' here, if there was no comma for two items. | According to Willam J. Strunk in *The Elements of Style*, Rule 2 states that a comma should be used after each term except the last in lists of three or more items. There is an exception which is in names of businesses, the correct example given is: Brown, Shipley and Company (as opposed to Brown, Shipley, and Company).
See the link for the full online text:
<https://faculty.washington.edu/heagerty/Courses/b572/public/StrunkWhite.pdf> |
172,671 | According to the Wikipedia page for the [Oxford Comma](http://en.wikipedia.org/wiki/Serial_comma#Arguments_for_and_against), "Use of the comma is consistent with conventional practice" and "Use of the comma is inconsistent with conventional practice." Did the Oxford Comma come before its omission, or was the Oxford Comma traditionally omitted?
It makes logical sense that every item in a list would be separated in the same way: by a comma. If the Oxford Comma is conventionally correct, when and why did people begin to omit it? | 2014/05/24 | [
"https://english.stackexchange.com/questions/172671",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/-1/"
] | There are situations where use of the [Oxford comma](https://en.wikipedia.org/wiki/Serial_comma "(a.k.a. serial comma or series comma)") will make or break a sentence.
**Choose a style and *be consistent*.** When you run into a situation in which your choice suggests a misinterpretation of the sentence, rewrite it in another manner to avoid the confusion.
Consider these two pairs where the Oxford comma makes (1) or breaks (2) the intention:
>
> **Oxford comma:**
>
>
> 1. *We invited the strippers, JFK, and Stalin.* = Strippers and JFK and Stalin.
> 2. *We invited the stripper, JFK, and Stalin.* = JFK (the stripper) and Stalin.
>
>
> **No Oxford comma:**
>
>
> 1. *We invited the strippers, JFK and Stalin.* = Strippers named JFK and Stalin.
> 2. *We invited the stripper, JFK and Stalin.* = Stripper and JFK and Stalin.
>
>
>
A picture (from [Joe Kessler's blog](http://lesserjoke.tumblr.com/post/17114988391/captainrobocop-politicalprof-the-oxford)) to better illustrate this:
[](http://lesserjoke.tumblr.com/post/17114988391/captainrobocop-politicalprof-the-oxford) | If find the Oxford comma to give fair representation to how people speak. When listing items in speech, equal pause is given between each item. For me, the Oxford comma emphasizes that there is, indeed, a pause before the 'and' preceding the last item of the list.
I think the Oxford comma also indicates the direction of the sentence -- it makes it clear that you are reading from a list. Often I find myself rereading sentences that don't make use of the Oxford comma because, on the first pass, I have misunderstood what they are saying.
But, as your question points out, many do not use the Oxford comma (e.g., The New York Times). |
172,671 | According to the Wikipedia page for the [Oxford Comma](http://en.wikipedia.org/wiki/Serial_comma#Arguments_for_and_against), "Use of the comma is consistent with conventional practice" and "Use of the comma is inconsistent with conventional practice." Did the Oxford Comma come before its omission, or was the Oxford Comma traditionally omitted?
It makes logical sense that every item in a list would be separated in the same way: by a comma. If the Oxford Comma is conventionally correct, when and why did people begin to omit it? | 2014/05/24 | [
"https://english.stackexchange.com/questions/172671",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/-1/"
] | If find the Oxford comma to give fair representation to how people speak. When listing items in speech, equal pause is given between each item. For me, the Oxford comma emphasizes that there is, indeed, a pause before the 'and' preceding the last item of the list.
I think the Oxford comma also indicates the direction of the sentence -- it makes it clear that you are reading from a list. Often I find myself rereading sentences that don't make use of the Oxford comma because, on the first pass, I have misunderstood what they are saying.
But, as your question points out, many do not use the Oxford comma (e.g., The New York Times). | According to Willam J. Strunk in *The Elements of Style*, Rule 2 states that a comma should be used after each term except the last in lists of three or more items. There is an exception which is in names of businesses, the correct example given is: Brown, Shipley and Company (as opposed to Brown, Shipley, and Company).
See the link for the full online text:
<https://faculty.washington.edu/heagerty/Courses/b572/public/StrunkWhite.pdf> |
172,671 | According to the Wikipedia page for the [Oxford Comma](http://en.wikipedia.org/wiki/Serial_comma#Arguments_for_and_against), "Use of the comma is consistent with conventional practice" and "Use of the comma is inconsistent with conventional practice." Did the Oxford Comma come before its omission, or was the Oxford Comma traditionally omitted?
It makes logical sense that every item in a list would be separated in the same way: by a comma. If the Oxford Comma is conventionally correct, when and why did people begin to omit it? | 2014/05/24 | [
"https://english.stackexchange.com/questions/172671",
"https://english.stackexchange.com",
"https://english.stackexchange.com/users/-1/"
] | There are situations where use of the [Oxford comma](https://en.wikipedia.org/wiki/Serial_comma "(a.k.a. serial comma or series comma)") will make or break a sentence.
**Choose a style and *be consistent*.** When you run into a situation in which your choice suggests a misinterpretation of the sentence, rewrite it in another manner to avoid the confusion.
Consider these two pairs where the Oxford comma makes (1) or breaks (2) the intention:
>
> **Oxford comma:**
>
>
> 1. *We invited the strippers, JFK, and Stalin.* = Strippers and JFK and Stalin.
> 2. *We invited the stripper, JFK, and Stalin.* = JFK (the stripper) and Stalin.
>
>
> **No Oxford comma:**
>
>
> 1. *We invited the strippers, JFK and Stalin.* = Strippers named JFK and Stalin.
> 2. *We invited the stripper, JFK and Stalin.* = Stripper and JFK and Stalin.
>
>
>
A picture (from [Joe Kessler's blog](http://lesserjoke.tumblr.com/post/17114988391/captainrobocop-politicalprof-the-oxford)) to better illustrate this:
[](http://lesserjoke.tumblr.com/post/17114988391/captainrobocop-politicalprof-the-oxford) | According to Willam J. Strunk in *The Elements of Style*, Rule 2 states that a comma should be used after each term except the last in lists of three or more items. There is an exception which is in names of businesses, the correct example given is: Brown, Shipley and Company (as opposed to Brown, Shipley, and Company).
See the link for the full online text:
<https://faculty.washington.edu/heagerty/Courses/b572/public/StrunkWhite.pdf> |
257,984 | When people say "Unbelievable" in texting, does it usually mean "Unbelievably good" or "Unbelievably bad", or neutral, when the context is unclear?
Details about the background:
I send something neutral and playful to a friend, and the friend replied "unbelievable" without any additional words or follow-ups.
When the details are missing, how would you usually interpret the mood or attitude behind the word "unbelievable"? Positive or negative? | 2020/08/21 | [
"https://ell.stackexchange.com/questions/257984",
"https://ell.stackexchange.com",
"https://ell.stackexchange.com/users/104870/"
] | Without context, there is no way to know for sure, but my guess would be the more general sense of disbelief (“I don’t believe it”) regarding whatever they replied to.
For instance, if you said “my friend did [something stupid]”, that response would mean they don’t believe the friend could be so stupid as to do that thing. | In texts, it would *more likely* mean "amazing!" (ie, good) if the context is otherwise unclear.
In general in English, it's extremely common to use (confusing!) reversals, double-negatives, sarcasm as the norm, etc. |
75,759 | I have a three-wheat batter bread recipe that calls for baking in four 16 oz cans. What size pan can I substitute? | 2016/11/22 | [
"https://cooking.stackexchange.com/questions/75759",
"https://cooking.stackexchange.com",
"https://cooking.stackexchange.com/users/52188/"
] | Three small (but not mini) metal loaf pans (5"L x 3"W x 3"D) will do it. Check out vintage bakeware in thrift stores to find that odd size, or choose pans closest to that size. | Honestly, use whatever size pans you have available to you and just monitor the baking process. Get creative. |
9,576 | I have edited [this closed question](https://worldbuilding.stackexchange.com/questions/220638/our-missing-sense-what-is-it-and-how-does-it-work) to provide some details that a few commentators mentioned were missing and submitted it for reopening. The reopen was rejected and the feedback is insufficient for me to work out why. Could I get some clarification please? Or better still, the question reopened. | 2021/12/24 | [
"https://worldbuilding.meta.stackexchange.com/questions/9576",
"https://worldbuilding.meta.stackexchange.com",
"https://worldbuilding.meta.stackexchange.com/users/23756/"
] | Let's clear up some doubts here :
Why didn't I vote to reopen the question
----------------------------------------
It's simple : Because I wasn't aware of the edit until you posted here and that I got through end-of-year-family-time downtime :). Otherwise the vote to reopen would have happened sooner.
The edit you made answered at least half of the issue I raised, which is you added constraints and therefore it gave a direction to look at.
What can you do to improve your question (and future ones)
----------------------------------------------------------
I've spread enough time on the definition of "external" in the comments, that's in any case not worth a point of closure. So instead I'll focus more on the big issue that caused that annoying closure : The intentions. But what do I mean by intentions, beyond my short 500-character long comment?
When creating a world you are engaging in an artistic process, even if said world is very tightly set in our reality. Artists -knowingly or unknowningly- tell some "inner message" in the result. Taking the spectator's view, if you watch a [movie about a virtual universe within a world](https://en.wikipedia.org/wiki/The_Matrix), you're most likely to find some inherent questions about one's identity, what is real and what isn't and so on. Same if you see a story set in a world where characters are clear[ly divi](https://en.wikipedia.org/wiki/Avatar_(2009_film))de[d in](https://en.wikipedia.org/wiki/Cop_Craft) c[astes](https://en.wikipedia.org/wiki/Isle_of_Dogs_(film)) or [with ap](https://en.wikipedia.org/wiki/Horizon_Zero_Dawn)pa[rent d](https://en.wikipedia.org/wiki/Ernest_%26_Celestine)i[stinc](https://en.wikipedia.org/wiki/Pillars_of_Eternity_II:_Deadfire)t[ions](https://en.wikipedia.org/wiki/X-Men) (there are a loooot of examples :D), the message behind is more likely to be about ostracism, discrimination or colonialism. It's not all the time the case or the main message, but it at least entices to that.
But that's the point of view of a player, a watcher, a listener, a reader. From the artist's side, more often than not they work first with the intentions -or message if you prefer- then with how to reach that goal. They can set the goal knowingly and sometimes unknowingly, getting the direction they want to reach through pure feelings or a mix of reasoning and sentiments.
In the present question, your intentions can be deduced from the constraints. That is, you want something more believable as your world is more bound to realism than others. By limiting, you brought an area we can play inside, on top of giving an hint of your intentions. However, it could be clearer by stating the inherent intentions instead of using constraints to do the job.
By asking "what is possible" instead of "how to reach something", I think it will be a lot more hard oui-no to make this change ^^. However, it doesn't mean you can't ask this kind of question, just that you need to express your goals another way than plainly stating them. One common way is to give a way to scale answers : "I will evaluate answers by plausibility", or going further "the senses that make old humans stronger in their native environment (within the constraints) will be marked as better to my eyes". Being able to compare answers indirectly tells what is it you want to reach. It's also in fact a common way to tell whether a question is opinion-based or not.
**I believe you get the gist now : the more you know what kind of answers will help you reach your goals, the more people will be able to help you in return.** Plus, it also helps you ensure you hold your universe tightly in regard with what you want to tell, so it is a good training to make! | From what I see, the question has been closed with the following motivation
>
> This question is opinion-based. It is not currently accepting answers.
>
>
> Update the question so it can be answered with facts and citations.
>
>
>
The edit that you have done doesn't seem to do anything to solve that problem. |
28,403,782 | What is the difference between back-propagation and feed-forward neural networks?
By googling and reading, I found that in feed-forward there is only forward direction, but in back-propagation once we need to do a forward-propagation and then back-propagation. I referred to [this link](http://www.nnwj.de/backpropagation.html)
1. Any other difference other than the direction of flow? What about the weight calculation? The outcome?
2. Say I am implementing back-propagation, i.e. it contains forward and backward flow. So is back-propagation enough for showing feed-forward? | 2015/02/09 | [
"https://Stackoverflow.com/questions/28403782",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/2028043/"
] | * A [Feed-Forward Neural Network](http://en.wikipedia.org/wiki/Feedforward_neural_network) is a type of Neural Network **architecture** where the connections are "fed forward", i.e. do not form cycles (like in recurrent nets).
* The term "Feed forward" is also used when you input something at the input layer and it *travels* from input to hidden and from hidden to output layer.
**The values are "fed forward"**.
Both of these uses of the phrase "feed forward" are in a context that has nothing to do with training per se.
* Backpropagation is a **training algorithm** consisting of 2 steps: 1) **Feed forward** the values 2) calculate the error and **propagate it back** to the earlier layers. So to be precise, forward-propagation is part of the backpropagation **algorithm** but comes before back-propagating. | There is no pure backpropagation or pure feed-forward neural network.
Backpropagation is algorithm to train (adjust weight) of neural network.
Input for backpropagation is output\_vector, target\_output\_vector,
output is adjusted\_weight\_vector.
Feed-forward is algorithm to calculate output vector from input vector.
Input for feed-forward is input\_vector,
output is output\_vector.
When you are training neural network, you need to use both algorithms.
When you are using neural network (which have been trained), you are using only feed-forward.
Basic type of neural network is multi-layer perceptron, which is Feed-forward backpropagation neural network.
There are also more advanced types of neural networks, using modified algorithms.
Also good source to study : <ftp://ftp.sas.com/pub/neural/FAQ.html>
Best to understand principle is to program it (tutorial in this video) <https://www.youtube.com/watch?v=KkwX7FkLfug> |
28,403,782 | What is the difference between back-propagation and feed-forward neural networks?
By googling and reading, I found that in feed-forward there is only forward direction, but in back-propagation once we need to do a forward-propagation and then back-propagation. I referred to [this link](http://www.nnwj.de/backpropagation.html)
1. Any other difference other than the direction of flow? What about the weight calculation? The outcome?
2. Say I am implementing back-propagation, i.e. it contains forward and backward flow. So is back-propagation enough for showing feed-forward? | 2015/02/09 | [
"https://Stackoverflow.com/questions/28403782",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/2028043/"
] | There is no pure backpropagation or pure feed-forward neural network.
Backpropagation is algorithm to train (adjust weight) of neural network.
Input for backpropagation is output\_vector, target\_output\_vector,
output is adjusted\_weight\_vector.
Feed-forward is algorithm to calculate output vector from input vector.
Input for feed-forward is input\_vector,
output is output\_vector.
When you are training neural network, you need to use both algorithms.
When you are using neural network (which have been trained), you are using only feed-forward.
Basic type of neural network is multi-layer perceptron, which is Feed-forward backpropagation neural network.
There are also more advanced types of neural networks, using modified algorithms.
Also good source to study : <ftp://ftp.sas.com/pub/neural/FAQ.html>
Best to understand principle is to program it (tutorial in this video) <https://www.youtube.com/watch?v=KkwX7FkLfug> | Neural Networks can have different architectures. The connections between their neurons decide direction of flow of information. Depending on network connections, they are categorised as - Feed-Forward and Recurrent (back-propagating).
**Feed Forward Neural Networks**
In these types of neural networks information flows in only one direction i.e. from input layer to output layer. When the weights are once decided, they are not usually changed. One either explicitly decides weights or uses functions like Radial Basis Function to decide weights. The nodes here do their job without being aware whether results produced are accurate or not(i.e. they don't re-adjust according to result produced). There is no communication back from the layers ahead.
**Recurrent Neural Networks (Back-Propagating)**
Information passes from input layer to output layer to produce result. Error in result is then communicated back to previous layers now. Nodes get to know how much they contributed in the answer being wrong. Weights are re-adjusted. Neural network is improved. It learns. There is bi-directional flow of information. This basically has both algorithms implemented, feed-forward and back-propagation. |
28,403,782 | What is the difference between back-propagation and feed-forward neural networks?
By googling and reading, I found that in feed-forward there is only forward direction, but in back-propagation once we need to do a forward-propagation and then back-propagation. I referred to [this link](http://www.nnwj.de/backpropagation.html)
1. Any other difference other than the direction of flow? What about the weight calculation? The outcome?
2. Say I am implementing back-propagation, i.e. it contains forward and backward flow. So is back-propagation enough for showing feed-forward? | 2015/02/09 | [
"https://Stackoverflow.com/questions/28403782",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/2028043/"
] | There is no pure backpropagation or pure feed-forward neural network.
Backpropagation is algorithm to train (adjust weight) of neural network.
Input for backpropagation is output\_vector, target\_output\_vector,
output is adjusted\_weight\_vector.
Feed-forward is algorithm to calculate output vector from input vector.
Input for feed-forward is input\_vector,
output is output\_vector.
When you are training neural network, you need to use both algorithms.
When you are using neural network (which have been trained), you are using only feed-forward.
Basic type of neural network is multi-layer perceptron, which is Feed-forward backpropagation neural network.
There are also more advanced types of neural networks, using modified algorithms.
Also good source to study : <ftp://ftp.sas.com/pub/neural/FAQ.html>
Best to understand principle is to program it (tutorial in this video) <https://www.youtube.com/watch?v=KkwX7FkLfug> | To be simple:
Feed-foward is an architecture. The contrary one is Recurrent Neural Networks.
Back Propagation (BP) is a solving method. BP can solve both feed-foward and Recurrent Neural Networks. |
28,403,782 | What is the difference between back-propagation and feed-forward neural networks?
By googling and reading, I found that in feed-forward there is only forward direction, but in back-propagation once we need to do a forward-propagation and then back-propagation. I referred to [this link](http://www.nnwj.de/backpropagation.html)
1. Any other difference other than the direction of flow? What about the weight calculation? The outcome?
2. Say I am implementing back-propagation, i.e. it contains forward and backward flow. So is back-propagation enough for showing feed-forward? | 2015/02/09 | [
"https://Stackoverflow.com/questions/28403782",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/2028043/"
] | * A [Feed-Forward Neural Network](http://en.wikipedia.org/wiki/Feedforward_neural_network) is a type of Neural Network **architecture** where the connections are "fed forward", i.e. do not form cycles (like in recurrent nets).
* The term "Feed forward" is also used when you input something at the input layer and it *travels* from input to hidden and from hidden to output layer.
**The values are "fed forward"**.
Both of these uses of the phrase "feed forward" are in a context that has nothing to do with training per se.
* Backpropagation is a **training algorithm** consisting of 2 steps: 1) **Feed forward** the values 2) calculate the error and **propagate it back** to the earlier layers. So to be precise, forward-propagation is part of the backpropagation **algorithm** but comes before back-propagating. | Neural Networks can have different architectures. The connections between their neurons decide direction of flow of information. Depending on network connections, they are categorised as - Feed-Forward and Recurrent (back-propagating).
**Feed Forward Neural Networks**
In these types of neural networks information flows in only one direction i.e. from input layer to output layer. When the weights are once decided, they are not usually changed. One either explicitly decides weights or uses functions like Radial Basis Function to decide weights. The nodes here do their job without being aware whether results produced are accurate or not(i.e. they don't re-adjust according to result produced). There is no communication back from the layers ahead.
**Recurrent Neural Networks (Back-Propagating)**
Information passes from input layer to output layer to produce result. Error in result is then communicated back to previous layers now. Nodes get to know how much they contributed in the answer being wrong. Weights are re-adjusted. Neural network is improved. It learns. There is bi-directional flow of information. This basically has both algorithms implemented, feed-forward and back-propagation. |
28,403,782 | What is the difference between back-propagation and feed-forward neural networks?
By googling and reading, I found that in feed-forward there is only forward direction, but in back-propagation once we need to do a forward-propagation and then back-propagation. I referred to [this link](http://www.nnwj.de/backpropagation.html)
1. Any other difference other than the direction of flow? What about the weight calculation? The outcome?
2. Say I am implementing back-propagation, i.e. it contains forward and backward flow. So is back-propagation enough for showing feed-forward? | 2015/02/09 | [
"https://Stackoverflow.com/questions/28403782",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/2028043/"
] | * A [Feed-Forward Neural Network](http://en.wikipedia.org/wiki/Feedforward_neural_network) is a type of Neural Network **architecture** where the connections are "fed forward", i.e. do not form cycles (like in recurrent nets).
* The term "Feed forward" is also used when you input something at the input layer and it *travels* from input to hidden and from hidden to output layer.
**The values are "fed forward"**.
Both of these uses of the phrase "feed forward" are in a context that has nothing to do with training per se.
* Backpropagation is a **training algorithm** consisting of 2 steps: 1) **Feed forward** the values 2) calculate the error and **propagate it back** to the earlier layers. So to be precise, forward-propagation is part of the backpropagation **algorithm** but comes before back-propagating. | To be simple:
Feed-foward is an architecture. The contrary one is Recurrent Neural Networks.
Back Propagation (BP) is a solving method. BP can solve both feed-foward and Recurrent Neural Networks. |
28,403,782 | What is the difference between back-propagation and feed-forward neural networks?
By googling and reading, I found that in feed-forward there is only forward direction, but in back-propagation once we need to do a forward-propagation and then back-propagation. I referred to [this link](http://www.nnwj.de/backpropagation.html)
1. Any other difference other than the direction of flow? What about the weight calculation? The outcome?
2. Say I am implementing back-propagation, i.e. it contains forward and backward flow. So is back-propagation enough for showing feed-forward? | 2015/02/09 | [
"https://Stackoverflow.com/questions/28403782",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/2028043/"
] | To be simple:
Feed-foward is an architecture. The contrary one is Recurrent Neural Networks.
Back Propagation (BP) is a solving method. BP can solve both feed-foward and Recurrent Neural Networks. | Neural Networks can have different architectures. The connections between their neurons decide direction of flow of information. Depending on network connections, they are categorised as - Feed-Forward and Recurrent (back-propagating).
**Feed Forward Neural Networks**
In these types of neural networks information flows in only one direction i.e. from input layer to output layer. When the weights are once decided, they are not usually changed. One either explicitly decides weights or uses functions like Radial Basis Function to decide weights. The nodes here do their job without being aware whether results produced are accurate or not(i.e. they don't re-adjust according to result produced). There is no communication back from the layers ahead.
**Recurrent Neural Networks (Back-Propagating)**
Information passes from input layer to output layer to produce result. Error in result is then communicated back to previous layers now. Nodes get to know how much they contributed in the answer being wrong. Weights are re-adjusted. Neural network is improved. It learns. There is bi-directional flow of information. This basically has both algorithms implemented, feed-forward and back-propagation. |
9,917 | We have implemented/are implementing a network vulnerability scanning process, and we have chosen to use Qualysguard.
Qualys supply a scanner appliance for the internal network scanning, which obviously connects to the network. Our internal network is segmented into multiple subnets, each firewalled from the others. We have a network segment which is used for IT management (such as Snort and Splunk). It would seem to make sense to have the scanner appliance in this network segment. The obvious issue is that the scanner appliance needs full visibility into all the devices it will scan on the network, and I'm loathe to open up firewall ports if it can be helped. I know that someone will say that there should be a scanner appliance in each subnet, but that's not practical for us.
I can think of several possible network locations for the scanner appliance:
* In the management network
* At the most-protected segment of the network (scanning out to less-protected devices)
* At the lest-protected segment of the network (scanning in to more protected devices)
* In an entirely separate subnet
So my question is that given that the appliance needs full (all ports open) access to all devices, where would you put the scanner appliance on your network and why? | 2011/12/20 | [
"https://security.stackexchange.com/questions/9917",
"https://security.stackexchange.com",
"https://security.stackexchange.com/users/1064/"
] | I have not used QualysGuard however using a vendor agnostic approach I would consider the following.
**Indirect connection through firewall:**
This can be a good option if you are unable to connect to the subnet for some reason (not enough connections, physically not accessible, etc...).
Some types of active scans depend on logical network location and may not work though a firewall / IPS (such a broadcasts and some poisoning) depending on your configuration. This is normally not a problem because the firewall / IPS provides that layer of protection, but an assessment may not be complete.
Increased load / processing through firewall and network equipment. Vulnerability scanning traffic can stress network equipment and may flood links. If this is a concern then locating the scanning interface logically close to the target is an advantage.
**Direct connection to subnet:**
Generally the best performance way to install a scanner, but can be a problem if you are unable to connect to a switch port with access to the network or VLAN you want to scan.
Directly connecting a scanner where it has direct connectivity to it’s target may allow it to detect vulnerabilities that are masked behind switch, firewall or IPS devices.
Scanners bridges secure zones. A scanner can have vulnerabilities too, less so these days but every scanner interface is potentially a bridge to multiple networks. This obviously depends on your implementation and product, some are better than others. Scanners would not normally route traffic but may if a vulnerability existed in the scanner or the scanner OS.
**Conclusion:**
The other options you have listed are all valid and could be used with an indirect connection through a firewall. Ideally you need to scan the platforms or applications from the side they will be servicing requests on. That may not be possible on a management network, depending on your configuration.
>
> Where would you put the scanner appliance on your network and why?
>
>
>
I would connect the scanner with directly connected ports on your most secure subnets (Internal network) which would likely have more hosts to scan. And then put some other interfaces in a separate subnet with access through firewalls to your least secure subnets.
This limits bridging and allows you to scans most/all of your hosts with minimal performance hit.
Hope this helps. | I am not sure that you will be able to get away with not adding rules to your firewalls to allow the traffic from the scanner. You will not need to open them up globally, just for the scanner's IP.
If you are using stateful inspection, the scanners should be on the untrusted side of the firewall anyway so that the state tables of the firewalls do not fill up and cause traffic problems.
The QualysGuard scanner supports VLAN tagging, so you might be able to work around the firewalls, depending on your setup. |
9,917 | We have implemented/are implementing a network vulnerability scanning process, and we have chosen to use Qualysguard.
Qualys supply a scanner appliance for the internal network scanning, which obviously connects to the network. Our internal network is segmented into multiple subnets, each firewalled from the others. We have a network segment which is used for IT management (such as Snort and Splunk). It would seem to make sense to have the scanner appliance in this network segment. The obvious issue is that the scanner appliance needs full visibility into all the devices it will scan on the network, and I'm loathe to open up firewall ports if it can be helped. I know that someone will say that there should be a scanner appliance in each subnet, but that's not practical for us.
I can think of several possible network locations for the scanner appliance:
* In the management network
* At the most-protected segment of the network (scanning out to less-protected devices)
* At the lest-protected segment of the network (scanning in to more protected devices)
* In an entirely separate subnet
So my question is that given that the appliance needs full (all ports open) access to all devices, where would you put the scanner appliance on your network and why? | 2011/12/20 | [
"https://security.stackexchange.com/questions/9917",
"https://security.stackexchange.com",
"https://security.stackexchange.com/users/1064/"
] | I have not used QualysGuard however using a vendor agnostic approach I would consider the following.
**Indirect connection through firewall:**
This can be a good option if you are unable to connect to the subnet for some reason (not enough connections, physically not accessible, etc...).
Some types of active scans depend on logical network location and may not work though a firewall / IPS (such a broadcasts and some poisoning) depending on your configuration. This is normally not a problem because the firewall / IPS provides that layer of protection, but an assessment may not be complete.
Increased load / processing through firewall and network equipment. Vulnerability scanning traffic can stress network equipment and may flood links. If this is a concern then locating the scanning interface logically close to the target is an advantage.
**Direct connection to subnet:**
Generally the best performance way to install a scanner, but can be a problem if you are unable to connect to a switch port with access to the network or VLAN you want to scan.
Directly connecting a scanner where it has direct connectivity to it’s target may allow it to detect vulnerabilities that are masked behind switch, firewall or IPS devices.
Scanners bridges secure zones. A scanner can have vulnerabilities too, less so these days but every scanner interface is potentially a bridge to multiple networks. This obviously depends on your implementation and product, some are better than others. Scanners would not normally route traffic but may if a vulnerability existed in the scanner or the scanner OS.
**Conclusion:**
The other options you have listed are all valid and could be used with an indirect connection through a firewall. Ideally you need to scan the platforms or applications from the side they will be servicing requests on. That may not be possible on a management network, depending on your configuration.
>
> Where would you put the scanner appliance on your network and why?
>
>
>
I would connect the scanner with directly connected ports on your most secure subnets (Internal network) which would likely have more hosts to scan. And then put some other interfaces in a separate subnet with access through firewalls to your least secure subnets.
This limits bridging and allows you to scans most/all of your hosts with minimal performance hit.
Hope this helps. | It's highly recommended that you work with your network group to determine where to
place Scanner Appliances in an enterprise network environment. Some things to
consider: place Scanner Appliances as close to target machines as possible, and make sure
to monitor and identify any bandwidth restricted segments or weak points in the
network infrastructure. Scanning through layer 3 devices (such as routers, firewalls and
load balancers) could result in degraded performance so you may consider using our
VLAN tagging feature (VLAN trunking) to circumvent layer 3 devices to avoid potential
performance issues.
A static IP is reserved for the Qualys scanner in each of the VLAN to be scanned by it.
The scanner uses the reserved static IP while scanning the VLAN.
So ,as you said, effectively it will be sitting inside the VLAN and hence L3 routing is not required.
Example : Scanner will scan VLAN A - 192.168.1.0/24 & VLAN B- 192.168.2.0/24
A static IP,Lets say 192.168.1.2 & 192.168.2.2 in each of the VLAN's is reserved for the scanner.
While scanning VLAN A,it will use the IP 192.168.1.2 thus effectively sitting inside VLAN A.
Similarly for VLAN B |
122,466 | My hard drive had some bad sectors recently, so I backed up, re-formatted, and clean installed Mavericks.
Everything seemed to work fine until couple days ago when I tried to look at some photos I recently imported to iPhoto, things got stuck and sometimes wouldn't move at all for up to 40 seconds, I knew it was a hard drive issue.
I tried to use the os x disk util to verify and repair disk but it all came up green.
when I try to run time machine it transfers REALLY REALLY SLOW and than gets stuck and says backup failed.
what should I do? | 2014/02/27 | [
"https://apple.stackexchange.com/questions/122466",
"https://apple.stackexchange.com",
"https://apple.stackexchange.com/users/71588/"
] | I had the same problem as you few years ago.
You definitely have the sympthoms of bad sectors. If you can't backup with Time Machine I advise you to back your data from the finder by yourself and skipping the files that can't be read.
---
Edit : You won't be able to backup all your files. You can't retrieve the data stored on the dead sectors. | Open Console in your Utility folder.
Type "disk" in the search (Filter) window
Look if you have disk I/O errors.
If you do see them (like a lots of them), your disk is bad, so back up, and get new disk. |
75,498 | The "ninth chord" that Rameau, Kirnberger, Marpurg or Koch (inter alia) discuss during the 18th century is the chord formed by a triad and an added ninth, and its explanation is always through a "chord of supposition", i.e., the supposed root is a third above the lowest note of the chord, since chords that spanned more than an octave were not "acceptable"
70-80 years laters, in harmony treatises like Reber or Richter (around 1850) the dominant ninth chord has earned its status as dissonant chord along with the seventh, and it is considered as a dominant 7 plus a third, its root being the root of the dominant seventh. Furthermore, diminished and half diminished seventh chords are now considered as a dominant ninth without its fundamental.
My question is: who was the first theoretician that considered this chord as an acceptable entity, and placed it side by side with the triad and the seventh chords? Who started thinking about chords as a stack of thirds that could exceed the octave? Who was the first to propose that diminished and halfdim chords are rootless dominant ninths?
Any help would be much appreciated. | 2018/10/17 | [
"https://music.stackexchange.com/questions/75498",
"https://music.stackexchange.com",
"https://music.stackexchange.com/users/52903/"
] | In addition to Reber and Richter that you mention, I know that Fétis (1844), Durand (1881), and Dubois (1889, 1921) also discussed ninth chords.
But the earliest theorist that I know of, not including theorists like Sorge that fall into the fundamental-bass camp with Rameau and Marpurg (it was this group, by the way, that claimed that diminished chords were incomplete dominant ninths), would be Charles-Simon Catel (1773–1830). His *Traité d'harmonie* of 1804 was actually the official harmony textbook of the Paris Conservatory (of which Catel was a founding member).
Believe it or not, Catel actually claimed that a single ninth chord was the source of all harmony (!). He vaguely justifies it with the opening pitches of the harmonic series, but mostly it's just a pedagogical tool that he uses: chords that are a part of this ninth chord are "natural," and chords that are not found within the ninth chord are "artificial."
[](https://i.stack.imgur.com/cMMbH.png)
And Catel's work is especially important because it was really the forerunner to Fétis's own treaty, which would be the single most influential French text on harmony in the nineteenth century.
Lastly, it should be noted that many viewed Catel's work as a bastardization of Rameau's treatise; they felt that Catel was too invested in "third-stacking" to be musically helpful. | It first gained common usage in the late baroque, its origin was through intervallic supposition and accidental harmonic forms. |
1,523,170 | I've been looking around at various APIs, and since twitter seems to be a common discussion point, I'll use it as an example.
A lot of APIs are implementing oAuth which is great for allowing the service to authenicate and authorize the application connecting to it, however, from what I have seen there doesnt seem to be a way for the application to verify that Twitter is actually Twitter (and not a man in the middle based attack)? I would expect to see some kind of signature (using a shared / public key) of the response body which I can use to validate that twitter signed it.
Is it just because currently there isnt really a point to a man in the middle attack with twitter tweets since currently, whats the worst that can happen (and why would someone want to give me invalid tweets)
On this point, if you were to sign the response, what method would you use? Im currently considering a HMAC-SHA1 signature of the response body using a shared key. | 2009/10/06 | [
"https://Stackoverflow.com/questions/1523170",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/56940/"
] | This is what the 'trust' part of SSL does.
-- Edit
I note this has been downvoted, but it's important that other readers realise it's due to a personal disagreement, not due to incorrectness. | In the .NET world we use WCF, which has many different security models, including signing (and if desired encrypting) each message/response. This adds up to a non-trivial amount of overhead, but can give you more 'trust' in the security model. You can switch to using binary-serialized data to cut down on the bloat and message size if you desire.
I'm not sure what other Web Service APIs offer in that area, though I'm sure someone else can add further details as needed. |
26,884,806 | So recently i gave my friend a URL on facebook chat while we were discussing on how much further we have to go on a booking system, my friend says he cant open the link, when i tried clicking it worked but what caught my eye was the referring URL by facebook:
>
> <https://www.facebook.com/>**l.php**?u=https%3A%2F%2F192.168.42.149%2FIS314%2Freservations.php
>
>
>
I was intrigued by the l.php (L.PHP), what actually does l.php do? I googled and a author speculated something on privacy at this page <http://www.codehesive.com/index.php/archive/facebook-privacy-and-the-mystery-of-l-php/> but nothing too certain. So i was wondering if anyone has a clear idea of what l.php could be, i find this interesting (weird i know). Thanks! | 2014/11/12 | [
"https://Stackoverflow.com/questions/26884806",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/3198256/"
] | No one can know what exactly that script does but the developers at Facebook.
I presume they track all outgoing links from Facebook to get some statistics on them and on the users. After that it just sends you to the external page. | Please check out the following article [Facebook, privacy and the mystery of l.php](http://web.archive.org/web/20160826060705/http://www.codehesive.com:80/index.php/archive/facebook-privacy-and-the-mystery-of-l-php/) which says:
>
> Unless it’s from a public page, all you’re bound to see is one simple
> referring URL: <http://www.facebook.com/l.php>. Facebook ‘wraps’ all
> links on Facebook within this simple file — once you click on a link
> in Facebook, l.php will ‘redirect’ you to the actual URL. Why Facebook
> does this is unclear.
>
>
>
So now you have more questions to answer.
Update: Sorry, I just realised that you posted actually the same link. |
85,421 | The police arrested a suspect linked to sexual assaults. The police searched his home. It sounds like initially the search warrants were very limited in scope but they widened as things turned up. While he was in jail, his lawyer followed his instructions to hide evidence.
From [Wikipedia](https://en.wikipedia.org/wiki/Paul_Bernardo#cite_note-17)
>
> Bernardo told his lawyer, Ken Murray, that the rape videotapes were
> hidden in a ceiling light fixture in the upstairs bathroom. Murray
> found the tapes and hid them from evidence. Later Murray resigned as
> Bernardo’s lawyer and John Rosen stepped in. Rosen turned the tapes
> over to police. [17]
>
>
>
Murray got off on [all charges](https://www.cbc.ca/news/canada/court-finds-bernardo-lawyer-not-guilty-1.252668). How is this possible? He knew what was on the tape, at least in a general sense. Doesn't a lawyer have a responsibility not to defend a specific fact that they know is criminal? This action had the potential to lead to the release of an extremely dangerous person to the public.
I find a lot of the story confusing. For example if police were still searching the house why would they let someone remove the tapes? If they were finished searching the house and didn't find them then why did he get the lawyer to remove them? Also why could he be kept in jail without charge for 71 days? | 2022/10/16 | [
"https://law.stackexchange.com/questions/85421",
"https://law.stackexchange.com",
"https://law.stackexchange.com/users/4067/"
] | Quick answer
============
"Is a lawyer allowed to follow a client's instructions to hide evidence?" **Probably not**. I discuss this in the final section of this answer.
About this specific case, the Crown did not prove beyond a reasonable doubt that the lawyer (Ken Murray) had intended to conceal the tapes permenantly or that he was aware of an obligation to disclose them prior to trial. As summarized by [Austin Cooper, K.C.](https://criminal-lawyers.ca/2009/10/16/the-ken-murray-case-defence-counsels-dilemma/):
>
> Justice Gravely held that the concealing of the tapes for 17 months until Bernardo’s trial had a tendency to obstruct the course of justice, and therefore the actus reus of the offence was proved. On the issue of whether Mr. Murray willfully intended to obstruct justice, because it was feasible that Mr. Murray could have used the tapes for the defence and may well have believed that he had no obligation to disclose the tapes until the trial, he found the necessary mens rea was not proved. Accordingly, he found him not guilty.
>
>
>
Deeper answer
=============
I'll first attempt to explain the trial judge's reasons ([*R. v. Murray*, 2000 CanLII 22378 (ON SC)](https://canlii.ca/t/1w0w5)). At the end, I answer your more general questions.
Facts
-----
* February, 1993: Ken Murray was retained to defend Paul Bernardo on sexual assault charges; **it was this charge for which Bernardo was already in custody at the time of the search of his home**.
* April 30, 1993: The final search warrant of the Bernardo home expired.
* May 6, 1993: Ken Murray opened a letter from Bernardo that instructed the defence team to retrieve six 8mm videotapes. They located the tapes, removed them, and they committed to not tell anyone about the tapes.
* May 18, 1993: Bernardo was charged with two counts of first-degree murder and related offences. Murray's retainer was expanded to include defence of these charges. Bernardo authorized Murray to copy and review the videotapes and make use of them as appropriate in his defence.
* Two of the tapes contained evidence of sexual assault and death threats. Others contained evidence about the character and actions of a co-accused which Murray thought could be useful in Bernardo's defence.
* Early June 1993: Murray made a copy of the tapes and became fully aware of their contents.
* July 11 and 12, 1994: Bernardo told Murray he intended to deny ever having any contact with the victims that were on the tapes. He told Murray that the tapes were not to be used to contradict this position.
* July 24, 1994: After learning about DNA evidence and learning what the co-accused told police (all pointing to Bernardo being with the victims in the home), and **after confirming that Bernardo insisted on maintaining his position that he had no contact with the victims and that the tapes were not to be used, Murray "felt obliged to terminate the solicitor-client relationship"**.
* August 25, 1994: After a period of discussion with John Rosen (a lawyer from another firm), Rosen agreed to take over the defence of the first-degree murder charges. Murray did not tell Rosen about the tapes. Murray would remain defence counsel on the sexual assault charges.
* August 27, 1994: Rosen and Murray met with Bernardo to explain the change in counsel on the murder charges.
* August 30, 1994: Bernardo directed Murray to not reveal any of his materials to "other counsel retained on my behalf for other offences that are currently before the Court... unless I specifically direct the release of such materials, in writing."
* Murray retained his own lawyer who further sought advice from the law society. The law society advised that (1) Murray remove himself as counsel for Bernardo on all matters; (2) Murray give the tapes to the judge in a sealed packet to be subect to court determination; and (3) to tell Bernardo of these steps as soon as possible.
* Rosen (the new defence counsel on the murder charges) became aware of these plans, learned that the tapes existed, and was concerned the tapes would be turned over without any input from him.
* September 21 and 22, 1994: After much discussion with Crown counsel, Rosen got instructions from Bernardo to turn over the tapes; the tapes were delivered to the Metropolitan Toronto Police and the Niagara Regional Police.
The charge
----------
Ken Murray was charged with wilfully obstructing or attempting to obstruct the course of justice.
The law
-------
The judge applied what is known as the "tendency test". He said:
>
> Attempting to obstruct justice is construed as the doing of an act which has a tendency to pervert or obstruct the course of justice (the actus reus). "Wilfully" then constitutes the mens rea -- that is the act is done for the purpose of obstructing the course of justice
>
>
>
He noted:
>
> The system functions within the broad principles of the presumption of innocence and the right to silence. The Crown must fully disclose its case. The defence has no reciprocal obligation.
>
>
>
Application of the law
----------------------
### *Actus reus*
In this case, the judge found that Murray had done the *actus reus* of the offence:
>
> On the face of the evidence Murray's action in secreting the critical tapes had the tendency to obstruct the course of justice at several stages of the proceedings.
>
>
> The tapes were put beyond the reach of the police who had unsuccessfully attempted to locate them. Secreting them had the tendency to obstruct the police in their duty to investigate the crimes of Bernardo and Homolka.
>
>
>
Further, there was no justification that negated the actus reus. This evidence on the tapes was not privilged; it was not communication between solicitor and client. The judge found that "once [Murray] had discovered the overwhelming significance of the critical tapes, Murray... was left with but three legally justifiable options":
>
> (a) immediately turn over the tapes to the prosecution, either directly or anonymously;
>
>
> (b) deposit them with the trial judge; or
>
>
> (c) disclose their existence to the prosecution and prepare to do battle to retain them.
>
>
>
### *Mens rea*
The Crown had to prove that Murray's *intention* was to obstruct the course of justice. The judge found that the Crown did not prove this element beyond a reasonable doubt. The judge found that Murray may have not intended to permanently suppress the tapes and that Murray may have believed he had no obligation to disclose the tapes prior to the trial. He had presented several theories regarding the potential usefulness of the tapes to the defence which would have required holding back the tapes for their tactical or "surprise" value. Also, the judge noted that the law in this area was confusing.1
>
> While Murray made only a token effort to find out what his obligations were, had he done careful research he might have remained confused. The weight of legal opinion in Ontario is to the effect that lawyers may not conceal material physical evidence of crime, but how this rule applies to particular facts has been the subject of extensive discussion. Lawyers in the United States have been afflicted with the same dilemma. In the materials supplied to me by counsel, there is reference to at least 15 law journal discussions on the issue.
>
>
>
Ethical responsibility
----------------------
>
> Doesn't a lawyer have a responsibility not to defend a specific fact that they know is criminal?
>
>
>
No. But they do have an obligation to not lie to the court or to allow their client to lie to the court. This is why Murray knew he had to withdraw from the case when Bernardo was committed to the defence that he had never encountered the victims.
To answer your title question, "Is a lawyer allowed to follow instructions from his client to hide evidence?", the answer today is "probably not." [It has even been suggested](https://criminal-lawyers.ca/2009/10/16/the-ken-murray-case-defence-counsels-dilemma/) that if defence counsel is faced with this issue, they should instruct their client:
>
> It is evidence that might convict you; if you give it to me, I may have to turn it over to the prosecution. Take it away and keep it in your residence; if you destroy it, you may be guilty of a crime.
>
>
>
The Law Society of Ontario's Rules of Professional Conduct now say ([Rule 5.1-2A](https://lso.ca/about-lso/legislation-rules/rules-of-professional-conduct/chapter-5#ch5_sec1-2-incriminating-physical-evidence)):
>
> A lawyer shall not counsel or participate in the concealment, destruction or alteration of incriminating physical evidence or otherwise act so as to obstruct or attempt to obstruct the course of justice.
>
>
>
Any lawyer faced with this dilemma should probably do what Mr. Murray eventually did and retain their own lawyer and/or get advice from their law society.
---
1. While the maxim "ignorance of the law is no excuse" generally holds true, the *mens rea* of this offence includes an intention to obstruct justice. The judge understood this to invite an inquiry into what Murray believed the law required of him. This approach has been criticized: see Lucinda Vandervort, "[Mistake of Law and Obstruction of Justice: A 'Bad Excuse'... Even for a Lawyer](https://journals.lib.unb.ca/index.php/unblj/article/view/29482/1882524671)", 2001. | The details and principles of this case seem well addressed in the [answer by Jen](https://law.stackexchange.com/a/85423/17500). But I wish to address a particular point in the question which does not depend on the detailed facts of this particular case.
The OP asks in the question:
>
> Doesn't a lawyer have a responsibility not to defend a specific fact that they know is criminal?
>
>
>
First of all, a lawyer does not defend facts, a lawyer defends accused persons.
A lawyer who has accepted the case of a person accused of a crime is permitted, indeed is often required, to present the best defense possible, even in the face of facts that seem to support the charges, or seem to prove the guilt of the accused. The defense lawyer may argue, and present evidence to try to show, that the evidence is not reliable, or that the evidence relied on by the prosecution can be explained by a theory other than the guilt of the accused. The defense lawyer may present evidence of diminished capacity, or insanity, or that others were responsible, or partly responsible, for the crime. There are various defenses which might apply in a specific case, and the lawyer is supposed to pick the one that seems to him or her the best choice, in consultation with the accused.
A defense lawyer is not permitted to destroy or alter evidence. Doing so is a crime. Actively concealing evidence is also a crime, but reserving evidence for use by the defense may not be, depending on the circumstances and the applicable law in that jurisdiction.
The defense lawyer is **not** supposed to directly lie to the court, nor to advise the accused to do so. Whether a defense lawyer may lawfully present the testimony of witnesses that s/he knows, or has good reason to believe, are lying varies in different jurisdictions.
Whether a defense lawyer has an obligation to disclose evidence that s/he knows of to the prosecution depends on the detailed circumstances, and is different in different jurisdictions.
A defense lawyer is not ethically responsible for the acquittal of an accused, provided that s/he has not violated the applicable rules of procedure. |
85,421 | The police arrested a suspect linked to sexual assaults. The police searched his home. It sounds like initially the search warrants were very limited in scope but they widened as things turned up. While he was in jail, his lawyer followed his instructions to hide evidence.
From [Wikipedia](https://en.wikipedia.org/wiki/Paul_Bernardo#cite_note-17)
>
> Bernardo told his lawyer, Ken Murray, that the rape videotapes were
> hidden in a ceiling light fixture in the upstairs bathroom. Murray
> found the tapes and hid them from evidence. Later Murray resigned as
> Bernardo’s lawyer and John Rosen stepped in. Rosen turned the tapes
> over to police. [17]
>
>
>
Murray got off on [all charges](https://www.cbc.ca/news/canada/court-finds-bernardo-lawyer-not-guilty-1.252668). How is this possible? He knew what was on the tape, at least in a general sense. Doesn't a lawyer have a responsibility not to defend a specific fact that they know is criminal? This action had the potential to lead to the release of an extremely dangerous person to the public.
I find a lot of the story confusing. For example if police were still searching the house why would they let someone remove the tapes? If they were finished searching the house and didn't find them then why did he get the lawyer to remove them? Also why could he be kept in jail without charge for 71 days? | 2022/10/16 | [
"https://law.stackexchange.com/questions/85421",
"https://law.stackexchange.com",
"https://law.stackexchange.com/users/4067/"
] | Quick answer
============
"Is a lawyer allowed to follow a client's instructions to hide evidence?" **Probably not**. I discuss this in the final section of this answer.
About this specific case, the Crown did not prove beyond a reasonable doubt that the lawyer (Ken Murray) had intended to conceal the tapes permenantly or that he was aware of an obligation to disclose them prior to trial. As summarized by [Austin Cooper, K.C.](https://criminal-lawyers.ca/2009/10/16/the-ken-murray-case-defence-counsels-dilemma/):
>
> Justice Gravely held that the concealing of the tapes for 17 months until Bernardo’s trial had a tendency to obstruct the course of justice, and therefore the actus reus of the offence was proved. On the issue of whether Mr. Murray willfully intended to obstruct justice, because it was feasible that Mr. Murray could have used the tapes for the defence and may well have believed that he had no obligation to disclose the tapes until the trial, he found the necessary mens rea was not proved. Accordingly, he found him not guilty.
>
>
>
Deeper answer
=============
I'll first attempt to explain the trial judge's reasons ([*R. v. Murray*, 2000 CanLII 22378 (ON SC)](https://canlii.ca/t/1w0w5)). At the end, I answer your more general questions.
Facts
-----
* February, 1993: Ken Murray was retained to defend Paul Bernardo on sexual assault charges; **it was this charge for which Bernardo was already in custody at the time of the search of his home**.
* April 30, 1993: The final search warrant of the Bernardo home expired.
* May 6, 1993: Ken Murray opened a letter from Bernardo that instructed the defence team to retrieve six 8mm videotapes. They located the tapes, removed them, and they committed to not tell anyone about the tapes.
* May 18, 1993: Bernardo was charged with two counts of first-degree murder and related offences. Murray's retainer was expanded to include defence of these charges. Bernardo authorized Murray to copy and review the videotapes and make use of them as appropriate in his defence.
* Two of the tapes contained evidence of sexual assault and death threats. Others contained evidence about the character and actions of a co-accused which Murray thought could be useful in Bernardo's defence.
* Early June 1993: Murray made a copy of the tapes and became fully aware of their contents.
* July 11 and 12, 1994: Bernardo told Murray he intended to deny ever having any contact with the victims that were on the tapes. He told Murray that the tapes were not to be used to contradict this position.
* July 24, 1994: After learning about DNA evidence and learning what the co-accused told police (all pointing to Bernardo being with the victims in the home), and **after confirming that Bernardo insisted on maintaining his position that he had no contact with the victims and that the tapes were not to be used, Murray "felt obliged to terminate the solicitor-client relationship"**.
* August 25, 1994: After a period of discussion with John Rosen (a lawyer from another firm), Rosen agreed to take over the defence of the first-degree murder charges. Murray did not tell Rosen about the tapes. Murray would remain defence counsel on the sexual assault charges.
* August 27, 1994: Rosen and Murray met with Bernardo to explain the change in counsel on the murder charges.
* August 30, 1994: Bernardo directed Murray to not reveal any of his materials to "other counsel retained on my behalf for other offences that are currently before the Court... unless I specifically direct the release of such materials, in writing."
* Murray retained his own lawyer who further sought advice from the law society. The law society advised that (1) Murray remove himself as counsel for Bernardo on all matters; (2) Murray give the tapes to the judge in a sealed packet to be subect to court determination; and (3) to tell Bernardo of these steps as soon as possible.
* Rosen (the new defence counsel on the murder charges) became aware of these plans, learned that the tapes existed, and was concerned the tapes would be turned over without any input from him.
* September 21 and 22, 1994: After much discussion with Crown counsel, Rosen got instructions from Bernardo to turn over the tapes; the tapes were delivered to the Metropolitan Toronto Police and the Niagara Regional Police.
The charge
----------
Ken Murray was charged with wilfully obstructing or attempting to obstruct the course of justice.
The law
-------
The judge applied what is known as the "tendency test". He said:
>
> Attempting to obstruct justice is construed as the doing of an act which has a tendency to pervert or obstruct the course of justice (the actus reus). "Wilfully" then constitutes the mens rea -- that is the act is done for the purpose of obstructing the course of justice
>
>
>
He noted:
>
> The system functions within the broad principles of the presumption of innocence and the right to silence. The Crown must fully disclose its case. The defence has no reciprocal obligation.
>
>
>
Application of the law
----------------------
### *Actus reus*
In this case, the judge found that Murray had done the *actus reus* of the offence:
>
> On the face of the evidence Murray's action in secreting the critical tapes had the tendency to obstruct the course of justice at several stages of the proceedings.
>
>
> The tapes were put beyond the reach of the police who had unsuccessfully attempted to locate them. Secreting them had the tendency to obstruct the police in their duty to investigate the crimes of Bernardo and Homolka.
>
>
>
Further, there was no justification that negated the actus reus. This evidence on the tapes was not privilged; it was not communication between solicitor and client. The judge found that "once [Murray] had discovered the overwhelming significance of the critical tapes, Murray... was left with but three legally justifiable options":
>
> (a) immediately turn over the tapes to the prosecution, either directly or anonymously;
>
>
> (b) deposit them with the trial judge; or
>
>
> (c) disclose their existence to the prosecution and prepare to do battle to retain them.
>
>
>
### *Mens rea*
The Crown had to prove that Murray's *intention* was to obstruct the course of justice. The judge found that the Crown did not prove this element beyond a reasonable doubt. The judge found that Murray may have not intended to permanently suppress the tapes and that Murray may have believed he had no obligation to disclose the tapes prior to the trial. He had presented several theories regarding the potential usefulness of the tapes to the defence which would have required holding back the tapes for their tactical or "surprise" value. Also, the judge noted that the law in this area was confusing.1
>
> While Murray made only a token effort to find out what his obligations were, had he done careful research he might have remained confused. The weight of legal opinion in Ontario is to the effect that lawyers may not conceal material physical evidence of crime, but how this rule applies to particular facts has been the subject of extensive discussion. Lawyers in the United States have been afflicted with the same dilemma. In the materials supplied to me by counsel, there is reference to at least 15 law journal discussions on the issue.
>
>
>
Ethical responsibility
----------------------
>
> Doesn't a lawyer have a responsibility not to defend a specific fact that they know is criminal?
>
>
>
No. But they do have an obligation to not lie to the court or to allow their client to lie to the court. This is why Murray knew he had to withdraw from the case when Bernardo was committed to the defence that he had never encountered the victims.
To answer your title question, "Is a lawyer allowed to follow instructions from his client to hide evidence?", the answer today is "probably not." [It has even been suggested](https://criminal-lawyers.ca/2009/10/16/the-ken-murray-case-defence-counsels-dilemma/) that if defence counsel is faced with this issue, they should instruct their client:
>
> It is evidence that might convict you; if you give it to me, I may have to turn it over to the prosecution. Take it away and keep it in your residence; if you destroy it, you may be guilty of a crime.
>
>
>
The Law Society of Ontario's Rules of Professional Conduct now say ([Rule 5.1-2A](https://lso.ca/about-lso/legislation-rules/rules-of-professional-conduct/chapter-5#ch5_sec1-2-incriminating-physical-evidence)):
>
> A lawyer shall not counsel or participate in the concealment, destruction or alteration of incriminating physical evidence or otherwise act so as to obstruct or attempt to obstruct the course of justice.
>
>
>
Any lawyer faced with this dilemma should probably do what Mr. Murray eventually did and retain their own lawyer and/or get advice from their law society.
---
1. While the maxim "ignorance of the law is no excuse" generally holds true, the *mens rea* of this offence includes an intention to obstruct justice. The judge understood this to invite an inquiry into what Murray believed the law required of him. This approach has been criticized: see Lucinda Vandervort, "[Mistake of Law and Obstruction of Justice: A 'Bad Excuse'... Even for a Lawyer](https://journals.lib.unb.ca/index.php/unblj/article/view/29482/1882524671)", 2001. | A lawyer protects lawfully. Once an evidence is encountered, every lawyer must expose it to the court or take criminal complicity responsibility. |
85,421 | The police arrested a suspect linked to sexual assaults. The police searched his home. It sounds like initially the search warrants were very limited in scope but they widened as things turned up. While he was in jail, his lawyer followed his instructions to hide evidence.
From [Wikipedia](https://en.wikipedia.org/wiki/Paul_Bernardo#cite_note-17)
>
> Bernardo told his lawyer, Ken Murray, that the rape videotapes were
> hidden in a ceiling light fixture in the upstairs bathroom. Murray
> found the tapes and hid them from evidence. Later Murray resigned as
> Bernardo’s lawyer and John Rosen stepped in. Rosen turned the tapes
> over to police. [17]
>
>
>
Murray got off on [all charges](https://www.cbc.ca/news/canada/court-finds-bernardo-lawyer-not-guilty-1.252668). How is this possible? He knew what was on the tape, at least in a general sense. Doesn't a lawyer have a responsibility not to defend a specific fact that they know is criminal? This action had the potential to lead to the release of an extremely dangerous person to the public.
I find a lot of the story confusing. For example if police were still searching the house why would they let someone remove the tapes? If they were finished searching the house and didn't find them then why did he get the lawyer to remove them? Also why could he be kept in jail without charge for 71 days? | 2022/10/16 | [
"https://law.stackexchange.com/questions/85421",
"https://law.stackexchange.com",
"https://law.stackexchange.com/users/4067/"
] | The details and principles of this case seem well addressed in the [answer by Jen](https://law.stackexchange.com/a/85423/17500). But I wish to address a particular point in the question which does not depend on the detailed facts of this particular case.
The OP asks in the question:
>
> Doesn't a lawyer have a responsibility not to defend a specific fact that they know is criminal?
>
>
>
First of all, a lawyer does not defend facts, a lawyer defends accused persons.
A lawyer who has accepted the case of a person accused of a crime is permitted, indeed is often required, to present the best defense possible, even in the face of facts that seem to support the charges, or seem to prove the guilt of the accused. The defense lawyer may argue, and present evidence to try to show, that the evidence is not reliable, or that the evidence relied on by the prosecution can be explained by a theory other than the guilt of the accused. The defense lawyer may present evidence of diminished capacity, or insanity, or that others were responsible, or partly responsible, for the crime. There are various defenses which might apply in a specific case, and the lawyer is supposed to pick the one that seems to him or her the best choice, in consultation with the accused.
A defense lawyer is not permitted to destroy or alter evidence. Doing so is a crime. Actively concealing evidence is also a crime, but reserving evidence for use by the defense may not be, depending on the circumstances and the applicable law in that jurisdiction.
The defense lawyer is **not** supposed to directly lie to the court, nor to advise the accused to do so. Whether a defense lawyer may lawfully present the testimony of witnesses that s/he knows, or has good reason to believe, are lying varies in different jurisdictions.
Whether a defense lawyer has an obligation to disclose evidence that s/he knows of to the prosecution depends on the detailed circumstances, and is different in different jurisdictions.
A defense lawyer is not ethically responsible for the acquittal of an accused, provided that s/he has not violated the applicable rules of procedure. | A lawyer protects lawfully. Once an evidence is encountered, every lawyer must expose it to the court or take criminal complicity responsibility. |
316,716 | Related to [What's the uA741's appeal?](https://electronics.stackexchange.com/questions/8253/whats-the-ua741s-appeal), a lot of schematics use this rather dated opamp. My follow-up question would be: What is a good alternative?
Of course if you have specific requirements you just search for the correct part. What I'm talking about is, what should be the default opamp I stock in my parts bin?
Imagine the average hobby project with a breadboard and an Arduino, single-supply, probably 5V, frequencies in the audio spectrum, and accidental shorts.
It should just be a nice, single-ended, well behaved (no phase reversal) opamp with a large voltage swing (preferably rail-to-rail), and reasonable performance for audio.
Some comments on the linked question mention LM358 and LM324, but I've read the low slew-rate may be bad for audio, which is what most of my analogue signals are. | 2017/07/11 | [
"https://electronics.stackexchange.com/questions/316716",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/94884/"
] | >
> what should be the default opamp I stock in my parts bin?
>
>
>
It's a failure on your part to think that there is a default op-amp that suits most applications. It's as simple as that. It's also a failure to limit what you think are the important parameters to those that you have stated.
There are many important parameters that may be important to a particular target application but, these parameters may be of no-consequence to a different application.
Examples are, but not limited to: -
* Input offset voltage
* Input offset voltage drift with temperature
* Input bias and offset currents
* Input common mode range
* Input impedance (resistance and capacitance)
* PSRR
* CMRR
* Phase margin
* Input equivalent voltage and current noises
* Ability to operate down to 1.8 volts on power supply
* Operating current
* Output impedance versus frequency
* Open loop gain
Your question is asking about the uA741 yet you quote a general application that would run on 5 volts - are you aware that the minimum recommended power supply is sometimes as high +/-10 volts with some hints in some data sheets that +/- 5 volts will be OK.
The ST uA741 is quoted to run at 5 volts but this is the exception rather than the rule. | Here is a brief answer - go to a distributor site and look at the op-amp section. One can normally select by parameters. For example, [Farnell](http://uk.farnell.com/c/semiconductors-ics/amplifiers-comparators/operational-amplifiers-op-amps) |
316,716 | Related to [What's the uA741's appeal?](https://electronics.stackexchange.com/questions/8253/whats-the-ua741s-appeal), a lot of schematics use this rather dated opamp. My follow-up question would be: What is a good alternative?
Of course if you have specific requirements you just search for the correct part. What I'm talking about is, what should be the default opamp I stock in my parts bin?
Imagine the average hobby project with a breadboard and an Arduino, single-supply, probably 5V, frequencies in the audio spectrum, and accidental shorts.
It should just be a nice, single-ended, well behaved (no phase reversal) opamp with a large voltage swing (preferably rail-to-rail), and reasonable performance for audio.
Some comments on the linked question mention LM358 and LM324, but I've read the low slew-rate may be bad for audio, which is what most of my analogue signals are. | 2017/07/11 | [
"https://electronics.stackexchange.com/questions/316716",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/94884/"
] | >
> what should be the default opamp I stock in my parts bin?
>
>
>
It's a failure on your part to think that there is a default op-amp that suits most applications. It's as simple as that. It's also a failure to limit what you think are the important parameters to those that you have stated.
There are many important parameters that may be important to a particular target application but, these parameters may be of no-consequence to a different application.
Examples are, but not limited to: -
* Input offset voltage
* Input offset voltage drift with temperature
* Input bias and offset currents
* Input common mode range
* Input impedance (resistance and capacitance)
* PSRR
* CMRR
* Phase margin
* Input equivalent voltage and current noises
* Ability to operate down to 1.8 volts on power supply
* Operating current
* Output impedance versus frequency
* Open loop gain
Your question is asking about the uA741 yet you quote a general application that would run on 5 volts - are you aware that the minimum recommended power supply is sometimes as high +/-10 volts with some hints in some data sheets that +/- 5 volts will be OK.
The ST uA741 is quoted to run at 5 volts but this is the exception rather than the rule. | Ne5532 is a good all purpose opamp. Tda1308 is another one for good low voltage application. It has poorer DC performance however. |
316,716 | Related to [What's the uA741's appeal?](https://electronics.stackexchange.com/questions/8253/whats-the-ua741s-appeal), a lot of schematics use this rather dated opamp. My follow-up question would be: What is a good alternative?
Of course if you have specific requirements you just search for the correct part. What I'm talking about is, what should be the default opamp I stock in my parts bin?
Imagine the average hobby project with a breadboard and an Arduino, single-supply, probably 5V, frequencies in the audio spectrum, and accidental shorts.
It should just be a nice, single-ended, well behaved (no phase reversal) opamp with a large voltage swing (preferably rail-to-rail), and reasonable performance for audio.
Some comments on the linked question mention LM358 and LM324, but I've read the low slew-rate may be bad for audio, which is what most of my analogue signals are. | 2017/07/11 | [
"https://electronics.stackexchange.com/questions/316716",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/94884/"
] | >
> what should be the default opamp I stock in my parts bin?
>
>
>
It's a failure on your part to think that there is a default op-amp that suits most applications. It's as simple as that. It's also a failure to limit what you think are the important parameters to those that you have stated.
There are many important parameters that may be important to a particular target application but, these parameters may be of no-consequence to a different application.
Examples are, but not limited to: -
* Input offset voltage
* Input offset voltage drift with temperature
* Input bias and offset currents
* Input common mode range
* Input impedance (resistance and capacitance)
* PSRR
* CMRR
* Phase margin
* Input equivalent voltage and current noises
* Ability to operate down to 1.8 volts on power supply
* Operating current
* Output impedance versus frequency
* Open loop gain
Your question is asking about the uA741 yet you quote a general application that would run on 5 volts - are you aware that the minimum recommended power supply is sometimes as high +/-10 volts with some hints in some data sheets that +/- 5 volts will be OK.
The ST uA741 is quoted to run at 5 volts but this is the exception rather than the rule. | Because you mentioned Arduino (low power, low voltage):
LM358N - 0.5mA, min 3V 1MHz
MCP6001 - 0.1mA, min 1.8V 1MHz
LM324 - 0.7mA, min 3V 1MHz (quadruple)
NE5532a - ?mA min +-5V (10MHz!)
TDA1308 - 3mA, min 3V, (class-AB stereo headphone driver, circ boards already available on ebay for $1)
LM193, LM293, LM393, LM2903, min 2V
Note:
\* min is minimum voltage required to run
\* mA is typical current consumption
\* I am going to prepare a RAR file with the data sheets for all the above ICs and upload it somewhere (for lazy people like me). |
316,716 | Related to [What's the uA741's appeal?](https://electronics.stackexchange.com/questions/8253/whats-the-ua741s-appeal), a lot of schematics use this rather dated opamp. My follow-up question would be: What is a good alternative?
Of course if you have specific requirements you just search for the correct part. What I'm talking about is, what should be the default opamp I stock in my parts bin?
Imagine the average hobby project with a breadboard and an Arduino, single-supply, probably 5V, frequencies in the audio spectrum, and accidental shorts.
It should just be a nice, single-ended, well behaved (no phase reversal) opamp with a large voltage swing (preferably rail-to-rail), and reasonable performance for audio.
Some comments on the linked question mention LM358 and LM324, but I've read the low slew-rate may be bad for audio, which is what most of my analogue signals are. | 2017/07/11 | [
"https://electronics.stackexchange.com/questions/316716",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/94884/"
] | Ne5532 is a good all purpose opamp. Tda1308 is another one for good low voltage application. It has poorer DC performance however. | Here is a brief answer - go to a distributor site and look at the op-amp section. One can normally select by parameters. For example, [Farnell](http://uk.farnell.com/c/semiconductors-ics/amplifiers-comparators/operational-amplifiers-op-amps) |
316,716 | Related to [What's the uA741's appeal?](https://electronics.stackexchange.com/questions/8253/whats-the-ua741s-appeal), a lot of schematics use this rather dated opamp. My follow-up question would be: What is a good alternative?
Of course if you have specific requirements you just search for the correct part. What I'm talking about is, what should be the default opamp I stock in my parts bin?
Imagine the average hobby project with a breadboard and an Arduino, single-supply, probably 5V, frequencies in the audio spectrum, and accidental shorts.
It should just be a nice, single-ended, well behaved (no phase reversal) opamp with a large voltage swing (preferably rail-to-rail), and reasonable performance for audio.
Some comments on the linked question mention LM358 and LM324, but I've read the low slew-rate may be bad for audio, which is what most of my analogue signals are. | 2017/07/11 | [
"https://electronics.stackexchange.com/questions/316716",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/94884/"
] | Because you mentioned Arduino (low power, low voltage):
LM358N - 0.5mA, min 3V 1MHz
MCP6001 - 0.1mA, min 1.8V 1MHz
LM324 - 0.7mA, min 3V 1MHz (quadruple)
NE5532a - ?mA min +-5V (10MHz!)
TDA1308 - 3mA, min 3V, (class-AB stereo headphone driver, circ boards already available on ebay for $1)
LM193, LM293, LM393, LM2903, min 2V
Note:
\* min is minimum voltage required to run
\* mA is typical current consumption
\* I am going to prepare a RAR file with the data sheets for all the above ICs and upload it somewhere (for lazy people like me). | Here is a brief answer - go to a distributor site and look at the op-amp section. One can normally select by parameters. For example, [Farnell](http://uk.farnell.com/c/semiconductors-ics/amplifiers-comparators/operational-amplifiers-op-amps) |
50,239,555 | I have a doubt about Microservices Architecture. We are developing an ERP and there're several microservices such as Human Resources, Identity, Orders and so on.
We've implemented a shared domain layer for entities that are common for all those layers, including abstractions ( interfaces ) of Company, Location and some value objects.
My question is: What's the boundary of shared items for microservices and how bad is that?
In that case, Those shared entities would be the same for each microservice, so that help us to write less code BUT at the same time creates a small level of coupling. | 2018/05/08 | [
"https://Stackoverflow.com/questions/50239555",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/-1/"
] | Usually microservice architectures adopt a "share nothing" concept, which mean your code bases should be ideally separate. Yes, that will mean you will write more code but will keep your microservices more manageable, uncoupled and probably lighter.
Also, regarding the DDD-part do the question, you should really strive to keep well defined boundaries within your application, which means you shouldn't be scared to have "redundant" entities in different bounded contexts because the same concept usually mean different things to different domain areas of your application.
Keeping onto the "ERP" theme, you'd expect the "Order Placing" context of your application to have quite a different view on the "Product" entity than that of the "Tax" context. Keeping those in distinct contexts in different code bases will allow you to model smaller aggregates with a higher level of cohesion that will be way less coupled to the other constructs of your model thus, making evolve your microservices way easier. | >
> My question is: What's the boundary of shared items for microservices and how bad is that?
>
>
>
Up until a few years ago it was complicated to get the boundaries a microservice defined because there was simply no agreement on how to archieve that, but Evans sorted that out a few years ago:
[GOTO 2015 • DDD & Microservices: At Last, Some Boundaries! • Eric Evans](https://www.youtube.com/watch?v=yPvef9R3k-M)
Microservices also follow the four tenants of SOA and the same 9 fallacies of distributed system are to take in consideration nevertheless their business scopes are different. Bear in mind that a microservice architecture should follow a Shared-nothing sort of architecture, so services don't really share entities, what they do is subscribe to messages, typically in a bus, and store local copies of the pieces of data they are interested in. This obviously introduce another concept called eventual consistency and depending on your business requirements,that might or might not if in your overall design. |
368,131 | Between a mains step down transformer and a SMPS, which would be safer for a bench power supply? I cannot look inside the transformer in either case to judge the insulation quality. But, if the insulation does fail there would be 230VAC at the secondary for the mains transformer. And, maybe 325VDC at the output of the SMPS (is that possible)? I can visually inspect the SMPS PCB to check if there is proper clearance, presence of MOVs, thermistors, fuses etc, but of course cannot see inside the transformer.
So the question is, which is easier to make safer (or screw up)? Which is easier to figure out when new, if failure will be catastrophic in future? Can SMPS transformers fail due to failing mosfets etc? I'm guessing that if a mains transformer works without issues when new (including the problem of interwinding capacitance), I can expect it to work for at least a decade without issues, right? Assuming everything will be fused properly and fan cooled.
It's one thing to get a shock from inadvertently touching bad wiring, and quite another to be exposed while clutching the wires in my hands. So I am concerned somewhat about safety. Of course, an RCD/RCCB should probably be put in, but I don't have that yet.
[PS: I'm planning to put a buck converter and then a linear regulator to drop and adjust the final output voltage, be it the SMPS, or the mains transformer.] | 2018/04/12 | [
"https://electronics.stackexchange.com/questions/368131",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/72155/"
] | >
> Battery A still had potential of 12V, but the battery B showed 0V.
>
>
>
When you connect batteries in series, you have to make sure they are of equal capacity (Ampere hours), equal Voltage and equal wear and age.
Basically you may only create a series pack with two brand new batteries.
This is important to prevent one battery limiting the entire pack. When discharging with unequal batteries your drain one of the batteries to damaging levels, and with charging you overcharge the other.
You can buy lead acid battery equalizers that make sure they are both the same voltage during charging and discharging so they wear out at the same rate.
However, this is not strictly required. But it can be helpful when you have such a heavy load that the differences in internal resistance at high currents have an effect on the balance.
For other battery chemistries, such as lithium batteries, balance is more strictly managed since these batteries are a fire hazard when you (dis)charge them too much. | Voltage is not a reliable indicator of charge state.
Both batteries can have a terminal voltage of 12V, but one be half charged and the other nearly dead. Running them in series will work until the weakest one is completely discharged.
At that point, the battery that still has charge begins pushing current through the discharged one. This "charge current" is running in the opposite direction from the current when the battery is being normally charged. Sort of like if you connected a 12V battery charger to a battery backwards.
This "backwards charging" will usually destroy the battery. This has happened to your battery. A discharged battery will usually show some voltage. Yours is showing 0V, so it is shot. |
368,131 | Between a mains step down transformer and a SMPS, which would be safer for a bench power supply? I cannot look inside the transformer in either case to judge the insulation quality. But, if the insulation does fail there would be 230VAC at the secondary for the mains transformer. And, maybe 325VDC at the output of the SMPS (is that possible)? I can visually inspect the SMPS PCB to check if there is proper clearance, presence of MOVs, thermistors, fuses etc, but of course cannot see inside the transformer.
So the question is, which is easier to make safer (or screw up)? Which is easier to figure out when new, if failure will be catastrophic in future? Can SMPS transformers fail due to failing mosfets etc? I'm guessing that if a mains transformer works without issues when new (including the problem of interwinding capacitance), I can expect it to work for at least a decade without issues, right? Assuming everything will be fused properly and fan cooled.
It's one thing to get a shock from inadvertently touching bad wiring, and quite another to be exposed while clutching the wires in my hands. So I am concerned somewhat about safety. Of course, an RCD/RCCB should probably be put in, but I don't have that yet.
[PS: I'm planning to put a buck converter and then a linear regulator to drop and adjust the final output voltage, be it the SMPS, or the mains transformer.] | 2018/04/12 | [
"https://electronics.stackexchange.com/questions/368131",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/72155/"
] | Voltage is not a reliable indicator of charge state.
Both batteries can have a terminal voltage of 12V, but one be half charged and the other nearly dead. Running them in series will work until the weakest one is completely discharged.
At that point, the battery that still has charge begins pushing current through the discharged one. This "charge current" is running in the opposite direction from the current when the battery is being normally charged. Sort of like if you connected a 12V battery charger to a battery backwards.
This "backwards charging" will usually destroy the battery. This has happened to your battery. A discharged battery will usually show some voltage. Yours is showing 0V, so it is shot. | The battery connected to the positive terminal will drain first every time. The idea that they drain evenly is incorrect. I check my trolling motor batteries for voltage every time I bring my boat back from the lake. The one connected to the positive lead is low and the one connected to the negative lead is 12+V. |
368,131 | Between a mains step down transformer and a SMPS, which would be safer for a bench power supply? I cannot look inside the transformer in either case to judge the insulation quality. But, if the insulation does fail there would be 230VAC at the secondary for the mains transformer. And, maybe 325VDC at the output of the SMPS (is that possible)? I can visually inspect the SMPS PCB to check if there is proper clearance, presence of MOVs, thermistors, fuses etc, but of course cannot see inside the transformer.
So the question is, which is easier to make safer (or screw up)? Which is easier to figure out when new, if failure will be catastrophic in future? Can SMPS transformers fail due to failing mosfets etc? I'm guessing that if a mains transformer works without issues when new (including the problem of interwinding capacitance), I can expect it to work for at least a decade without issues, right? Assuming everything will be fused properly and fan cooled.
It's one thing to get a shock from inadvertently touching bad wiring, and quite another to be exposed while clutching the wires in my hands. So I am concerned somewhat about safety. Of course, an RCD/RCCB should probably be put in, but I don't have that yet.
[PS: I'm planning to put a buck converter and then a linear regulator to drop and adjust the final output voltage, be it the SMPS, or the mains transformer.] | 2018/04/12 | [
"https://electronics.stackexchange.com/questions/368131",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/72155/"
] | >
> Battery A still had potential of 12V, but the battery B showed 0V.
>
>
>
When you connect batteries in series, you have to make sure they are of equal capacity (Ampere hours), equal Voltage and equal wear and age.
Basically you may only create a series pack with two brand new batteries.
This is important to prevent one battery limiting the entire pack. When discharging with unequal batteries your drain one of the batteries to damaging levels, and with charging you overcharge the other.
You can buy lead acid battery equalizers that make sure they are both the same voltage during charging and discharging so they wear out at the same rate.
However, this is not strictly required. But it can be helpful when you have such a heavy load that the differences in internal resistance at high currents have an effect on the balance.
For other battery chemistries, such as lithium batteries, balance is more strictly managed since these batteries are a fire hazard when you (dis)charge them too much. | The battery connected to the positive terminal will drain first every time. The idea that they drain evenly is incorrect. I check my trolling motor batteries for voltage every time I bring my boat back from the lake. The one connected to the positive lead is low and the one connected to the negative lead is 12+V. |
5,259 | I asked a question, which I believed was with a very simple answer and then it got on hold as too broad.
None of the "too-broad" voters actually gave a reason why it would be too broad. And only one of the answers given fits all the clues (the accepted one). I even added two more hints after the first close vote - to make it clearer for the readers, even though the additional hints are not really necessary to solve the riddle.
I am referring to this question: [Question](https://puzzling.stackexchange.com/questions/41095/you-want-it-yet-you-dont-really)
I have read the answer to [this question](https://puzzling.meta.stackexchange.com/questions/4523/how-is-this-too-broad), here on Meta, and I believe the situation is similar and the close-voters didn't really think on the riddle. | 2016/08/20 | [
"https://puzzling.meta.stackexchange.com/questions/5259",
"https://puzzling.meta.stackexchange.com",
"https://puzzling.meta.stackexchange.com/users/29050/"
] | That is the whole problem with riddles. You might have thought of a certain answer but you will find lots of different answers, many of which will make sense because riddles usually are "think out of the box".
And looking at your question, if you see the answers, from a neutral perspective, many of the answers make sense. Fame, pokemons(OK, maybe a little too out of the box) are not that bad answers. | >
> I asked a question, which I believed was with a very simple answer and then it got on hold as too broad.
>
>
>
The problem is that unless specific clues are given, many different things under the Sun can fit as an answer to a riddle, thus making it a bad one.
>
> And only one of the ... I even added two more hints after the first close vote - to make it clearer for the readers, even though the additional hints are not really necessary to solve the riddle.
>
>
>
"Make everything as simple as possible, but not simpler." **Albert Einstein** ([probably](https://skeptics.stackexchange.com/q/34599/31063)) |
5,259 | I asked a question, which I believed was with a very simple answer and then it got on hold as too broad.
None of the "too-broad" voters actually gave a reason why it would be too broad. And only one of the answers given fits all the clues (the accepted one). I even added two more hints after the first close vote - to make it clearer for the readers, even though the additional hints are not really necessary to solve the riddle.
I am referring to this question: [Question](https://puzzling.stackexchange.com/questions/41095/you-want-it-yet-you-dont-really)
I have read the answer to [this question](https://puzzling.meta.stackexchange.com/questions/4523/how-is-this-too-broad), here on Meta, and I believe the situation is similar and the close-voters didn't really think on the riddle. | 2016/08/20 | [
"https://puzzling.meta.stackexchange.com/questions/5259",
"https://puzzling.meta.stackexchange.com",
"https://puzzling.meta.stackexchange.com/users/29050/"
] | Your riddle, if I understand correctly, works on a simple principle, namely **two different meanings of the same word.** While this is a nice principle, the implementation is, IMHO, a bit weak: there are too few constraints on the desired answer, which broadens the list of possible answers. For example, I can think of at least three other answers, which I believe satisfy all the clues:
>
> *Hypothetical Answer 1*:
>
> I think the answer is :
>
>
>
> >
> > Puzzle.
> >
> >
> >
>
>
> Because:
>
> You may want it here,
>
>
>
> >
> > We want good puzzles here on PSE.
> >
> >
> >
>
>
> But if you get it real,
>
>
> You'd surely want it gone,
>
>
> For it has no place at home.
>
>
>
> >
> > Because I don't want to be puzzled in real life.
> >
> >
> >
>
>
> Hints:
>
>
> I am hard to get/catch.
>
>
>
> >
> > Puzzles are hard to get (solve).
> >
> >
> >
>
>
> You will like me here, you will never want me/like me real.
>
>
>
> >
> > Explained before.
> >
> >
> >
>
>
>
---
>
> *Hypothetical Answer 2:*
>
>
> Is it
>
>
>
> >
> > fun?
> >
> >
> >
>
>
> You may want it here,
>
>
>
> >
> > I do want to have fun here.
> >
> >
> >
>
>
> But if you get it real,
>
>
> You'd surely want it gone,
>
>
> For it has no place at home.
>
>
>
> >
> > fun+real=funeral=sad :(
> >
> >
> >
>
>
>
---
>
> *Hypothetical Answer 3:*
>
>
> Maybe it's
>
>
>
> >
> > gold?
> >
> >
> >
>
>
> You may want it here,
>
>
>
> >
> > You want gold badges.
> >
> >
> >
>
>
> But if you get it real,
>
>
> You'd surely want it gone,
>
>
> For it has no place at home.
>
>
>
> >
> > Because then it might be stolen; you'd keep it in a bank instead.
> >
> >
> >
>
>
>
I'm not saying that was a bad puzzle; I simply want to suggest why it might have been put on hold as "too broad". | >
> I asked a question, which I believed was with a very simple answer and then it got on hold as too broad.
>
>
>
The problem is that unless specific clues are given, many different things under the Sun can fit as an answer to a riddle, thus making it a bad one.
>
> And only one of the ... I even added two more hints after the first close vote - to make it clearer for the readers, even though the additional hints are not really necessary to solve the riddle.
>
>
>
"Make everything as simple as possible, but not simpler." **Albert Einstein** ([probably](https://skeptics.stackexchange.com/q/34599/31063)) |
203,725 | I'd like to write about the golden age of piracy and this thought came to me: is there a standard way for a 1600's ship to handle a rogue wave, or does this vary by ship design?
My inexistent degree on sailing comes from playing Assassin's Creed. In one of the games in the series, the protagonist's ship deals with rogue waves by exposing either port or starboard to the wave. Failure to do so results in the ship taking damage. However, in the very next game, a different ship must point the bow at rogue waves, taking damage otherwise. Both ships seem to be of similar shape and build, so I found the mechanics contradictory and would like to know how this goes in real life.
A general answer would be appreciated, but if different classes of ships have different modes of operation for rogue waves, an answer detailing some of those would be appreciated even more - I do expect a frigate, a galleon and a schooner to be differently affected, and would not be surprised if they should need to react differently. | 2021/06/01 | [
"https://worldbuilding.stackexchange.com/questions/203725",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/21222/"
] | It depends on the dimensions of your boat, and of the wave.
Basically, you do not want the wave to roll you ship, nor do you want the wave to break your ship in two.
You want to hit the wave with a part of the ship that is of length a little bit longer than the maximum trough-to-peak of the wave. This way the ship "rides" the wave, rather than being tumbled by it (too short) or ploughing through multiple waves (much too long)
With you in a **1600's ship**, facing a deep-ocean wave, the **best approach will always be straight-on**. Bow or stern matters less for the wave and more for the wind, but bow tends to be pointier and stronger, so better to hit the wave first, as the leading edge of the wave is inevitably sharper than the trailing edge.
The 1600's ship will always be out-sized by a deepsea rogue wave, so your main concern is rolling over, there is *no ways* your ship will be so long as to be in greater danger of snapping due to uneven support. | **Use catamarans**
Catamarans have some drawbacks against monohulls, but handling rough seas is one of their strengths. I don't know if it was possible to build a carrack-sized catamaran, but smaller ships would be very viable. |
68,683 | I have a SPST relay that I do not have the full datasheet for, but I wish to calculate the time it takes to switch on a current for a particular voltage. Is there any easy general way to do this? My first thought would be to time it for a clicking noise, but I don't think that would be accurate for what I need.
My relay is labeled "9V" and rated for 250V AC. I plan to switch on a set of capacitors that will be a few miliFarads at around 350 volts - the current will be around 25A for a very short period of time. Ideally, it would be great if it would be a possible to design a simple circuit that could test this delay accurate to a few jiffies.
Thanks.
EDIT: I'm assuming the relay will have a pretty consistent off-on switching time. If it doesn't, is there any switching circuit with a latency between 10MS and 100MS that can handle the above specifications? | 2013/05/09 | [
"https://electronics.stackexchange.com/questions/68683",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/16834/"
] | Do you have an oscilloscope handy? A quick way to measure the switching time would be to operate the relay with probes hooked up to the control coil and the switching side of the relay. You would need to hook up some kind of dummy load so you can see it turn on. You would need to be able to monitor both the channels on a single scope, so that you can measure the time delay between the two signals.
Switching time for relays is usually in the single digit millisecond range or lower, so it would be hard to time it yourself. | If you have an Arduino or any other microcontroller devboard handy, you can set up an experiment to measure the delay.
Just hook up the relay coil to a micro via transistor (don't forget the protection diode!) and put a dummy load (something like 10k resistor) on the output of the relay and connect it to input pin of a microcontroller. Then write a simple program to switch the relay on and count time it takes the relay to switch on. If you use timers in input capture mode for that, you can get pretty accurate results.
One thing to note is that relay will bounce, so you might get really deep into it, like measuring bounce time, etc.
Edit: regarding the alternative - a solid state relay with zero crossing detection probably will have latency in your range or lower. Take care to select one that can handle more than 25A instanteneous current. |
106,784 | I am working on a team that is doing both driver software and FPGA development. The FPGA simulation is being done in Modelsim and driver software is written in C. To minimize integration risk, I would love to be able to model the interaction between the two halves of our product before putting it on hardware.
I know Modelsim supports a testbench which lets you provide stimulus in the form of a text file with times and values to input. I'm wondering if Modelsim has a mode which allows you to hook up a pipe to an external application (such as our driver), and run a sort of distributed simulation where the software can push values into the testbench, then observe the results later.
The trick that I cannot do with a text file input is have the two halves of the product interact. I need to have the software "write" values into the FPGA simulator, read the results, and then write new values into the FPGA which are dependent on the results it read. Text files require the inputs to be independent from the output.
I've done searches on both StackExchange and google, but I have not been able to come up with a set of keywords to narrow my search enough to either identify the behavior I am looking for, or determine that it does not exist. | 2014/04/16 | [
"https://electronics.stackexchange.com/questions/106784",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/40447/"
] | [External Control of a ModelSim Simulation Via Unix Named Pipes](http://books.google.com/books/about/External_Control_of_a_ModelSim_Simulatio.html?id=bBSrZwEACAAJ&redir_esc=y)
>
> Abstract: In this thesis, we present a method of controlling a
> ModelSim simulation via an external program. Communication between
> ModelSim and the external program is accomplished by using Named Pipes
> ("FIFOs"), which appear as normal files to each application. The main
> difference between using FIFOs versus normal files for Inter-Process
> Communication (IPC) is that an application attempting to write to a
> FIFO is paused until another application attempts to read from the
> FIFO and vice-versa. This improves reliability of the IPC. The major
> advantages of this method are 1) Since only generic file operations
> are used, the external application can be written in nearly any
> programming language; 2) It gives the verification engineer the
> ability to reuse standards-validation software packages with minimal
> rewriting; 3) By having multiple Devices Under Test (DUT) communicate
> with each other, a more accurate simulation of the final system can be
> created; and 4) Performance of the overall simulation can be increased
> easily on a Single-System Image (SSI) cluster or multiprocessor
> computer even though ModelSim's simulation engine is not multi-
> threaded. Due to its implementation of file input/output (I/O) for
> behavioral VHDL, ModelSim cannot read or write these FIFOs directly. A
> workaround for this limitation is demonstrated using ModelSim's
> Foreign Language Interface (FLI). This paper also shows a working
> example of this method being used in the verification of the next
> generation of floating point routines in VHDL. Specifically, the
> open-source IEEE Compliance Checker software package, which is written
> in C++, is modified to communicate with a VHDL testbench running on
> ModelSim to verify functionality of the add, multiply, divide, and
> square root operations with various widths of floating point numbers.
>
>
>
And the issue with FIFOs requiring a Foreign programming interface is that VHDL file I/O can't deal gracefully with blocking until data is available.
Unfortunately the thesis isn't available on the web.
[Model Sim ® Foreign Language Interface Version 5.6d](http://homepages.cae.wisc.edu/~ece554/new_website/ToolDoc/Modelsim_docs/docs/pdf/fli.pdf), PDF 3.4 MB.
[Using ModelSim Foreign Language Interface for c – VHDL Co- Simulation and for Simulator Control on Linux x86 Platform Andre Pool - fli@andrepool.com - Version 1.5 - created November 2012, last update September 2013](http://opencores.org/usercontent,doc,1380917197), PDF, 320KB (And never mentions FIFOs).
[Using ModelSim Foreign Language Interface for c – VHDL Co-Simulation and for Simulator Control on Linux x86 Platform](https://github.com/andrepool/fli) (The matching github code repository).
There's a bit more open source, using the VHPI Foreign function calls in ghdl:
[vhdl/src/sim/ghdlex\_mein at master · texane/vhdl · GitHub](https://github.com/texane/vhdl/tree/master/src/sim/ghdlex_mein).
And what looks like an update from Martin Strubel on the GHDL\_discuss list:
<http://www.section5.ch/downloads/ghdlex-0.051.tgz> showing a date for fifo.c of April 14, 2014.
FLI would by definition lock you in to Modelsim, not sure of the state of their VHPI support (which is part of IEEE Std 1076-2008, the VHDL LRM).
Using a socket or file FIFO allows the software and hardware process to run at different rates, by providing rate buffering. It isn't always necessary if you're software system is orders of magnitude faster than the hardware simulation (and it generally is).
There's an effort to provide UNIX (POSIX) functionality to VHDL, See [Public Domain VHDL packages](http://bear.ces.cwru.edu/VHDL/index.html), which contains a pointer to an earlier paper [SNUG San Jose 2002 1 C/UNIX Functions for VHDL Testbenches C/UNIX Functions for VHDL Testbenches](http://bear.ces.cwru.edu/VHDL/doc/snug2002_20020313_paper.pdf) along with a slide set [with additional notes on Unix pipes & rsh](http://bear.ces.cwru.edu/VHDL/doc/snug2002_20040606_slides.pdf). This shows how to keep named pipes opened. All the VHDL code can be downloaded as well. I'm of the opinion this would lead to the easiest way of achieving your goal.
So is there something native to Modelsim that allows you to hook up to a pipe? Likely not, the more so under Windows. Can it be done? Yes, but the way isn't for the fainthearted. You can deadlock one end or the other or possibly both waiting on data availability.
A Foreign programming interface theoretically allows you to spawn a child process for one or the other end of the 'pipe' which also means you could use a shared memory model to communicate between the two ends. | You might want to look at [Cocotb](http://cocotb.org). It's a Python based co-simulation library, one of the design goals was to enable the methodology you describe, easily simulating un-modified production software and RTL.
There's an example in the repository of running unmodified `ping` command against a simulation and a [tutorial](https://docs.cocotb.org/en/v1.1/ping_tun_tap.html) walking through the code.
For user-space drivers, configuration utilities etc. you have a couple of options to run your software *un-modified*:
1. If your accesses to the device boil down to a few functions (e.g. a
read and a write call) you can link against a simulation library
which block while performing the access against the simulation.
This works very well for configuration.
2. If your software uses memory mapped IO and dereferences pointers to
access the device then things get slightly more complex - you have
to create a shared memory area with protection bits set and [trap
accesses](https://stackoverflow.com/questions/21068714/trap-all-accesses-to-an-address-range-linux).
If you use networking then virtual interfaces like TUN/TAP can be used (see the [tutorial](https://cocotb.readthedocs.org/en/latest/ping_tun_tap.html) mentioned above), I suspect there may be similar options for USB transfer or other common host interfaces.
Cocotb works with a variety of simulators and VHDL (via VHPI) or Verilog/SystemVerilog designs (via VPI). Unfortunately Modelsim doesn't implement VHPI so as a VHDL user you're stuck with FLI, which is not nearly so useful as an interface. You could [moan at Mentor](https://twitter.com/PVCocotb/statuses/461808813243645952) to try and persuade them to implement an industry standard interface, or you could evaluate another simulator that supports VHPI.
Sadly, it appears that tool vendors in general aren't particularly interested in the VHDL market, judging by the time it takes them to implement any VHDL related functionality...
Disclaimer: I'm a Cocotb developer. |
54,057 | I just receive my first "official" drawing/logo project and I'm not sure how to get about doing it.
So this client asked me for a drawing for a brand logo that he's planning on doing (just a drawing for now, but maybe a logo later on, but I'll need to tell him my rates and all). So I'm planning to tell him that I don't do drawings but I do provide logo designs. But if he wants a hand drawn logo, how can I go about doing that?
I know that obviously I can't just scan it since it won't be resizeable. But turning it into a vector would be either too clean or too jaggy (lol, is that even a word). I'm curious if any. How would you go about doing it?
PS: If there are other questions/thread available already on the site, pls do let me know. Sry if it's a duplicate. | 2015/05/25 | [
"https://graphicdesign.stackexchange.com/questions/54057",
"https://graphicdesign.stackexchange.com",
"https://graphicdesign.stackexchange.com/users/44301/"
] | If you have access to an iPhone or iPad, you could try using [Adobe Shape](http://www.adobe.com/products/shape.html). It uses the device camera to take pictures and convert the pictures into vectors. | It all depends on the look you want on the logo. If it's very sketchy, or has something like watercolor textures it might be harder to vectorize, but it is possible to achieve a hand-drawn look in all vector using illustrator brushes and textures.
It is also possible to have a hand-drawn version (that you maybe draw big and scan at a high resolution so you have a file that can be used a lot)and a simplified vector version that you can use for when the bitmap version is not optimal. |
54,057 | I just receive my first "official" drawing/logo project and I'm not sure how to get about doing it.
So this client asked me for a drawing for a brand logo that he's planning on doing (just a drawing for now, but maybe a logo later on, but I'll need to tell him my rates and all). So I'm planning to tell him that I don't do drawings but I do provide logo designs. But if he wants a hand drawn logo, how can I go about doing that?
I know that obviously I can't just scan it since it won't be resizeable. But turning it into a vector would be either too clean or too jaggy (lol, is that even a word). I'm curious if any. How would you go about doing it?
PS: If there are other questions/thread available already on the site, pls do let me know. Sry if it's a duplicate. | 2015/05/25 | [
"https://graphicdesign.stackexchange.com/questions/54057",
"https://graphicdesign.stackexchange.com",
"https://graphicdesign.stackexchange.com/users/44301/"
] | If you have access to an iPhone or iPad, you could try using [Adobe Shape](http://www.adobe.com/products/shape.html). It uses the device camera to take pictures and convert the pictures into vectors. | If the logo will be used for commercial purposes then it must be professionally vectorized. Don't even think about automated vector conversion tools. They are providing terrible vector images that can not be used for any company. Check blue link with tutorial that will show you how to vectorize company logo with a pen tool in adobe illustrator -
[How to turn pixel image into vector](http://vectorizeimages.blogspot.sk/2015/01/how-to-turn-pixel-image-into-vector.html) |
12,044 | I have an APEX script that generates emails after some event occurs. I would like to see a record of all the emails that have been sent. Is this possible in the Setup portion of SalesForce? | 2013/05/23 | [
"https://salesforce.stackexchange.com/questions/12044",
"https://salesforce.stackexchange.com",
"https://salesforce.stackexchange.com/users/2772/"
] | To access email logs, click Your Name | Setup | Monitoring | Email Log Files.
<http://login.salesforce.com/help/doc/en/email_logs.htm>
For that to work, the employee will need to have the "Modify All Data" as described [here](https://help.salesforce.com/apex/HTViewHelpDoc?id=email_logs.htm&language=en_US) | You can also add a Compliance BCC email address, which will be added to the BCC of every email that is sent out of your org. Of course, you'll get a lot more than just the emails generated by the apex script. I have a separate inbox for this purpose.
<http://login.salesforce.com/help/doc/en/admin_compliancebcc.htm> |
53,995 | I just met a terminology called "embedding" in a paper regarding deep learning. The context is "multi-modal embedding"
My guess: embedding of something is extract some feature of sth,to form a vector.
I couldn't get the explicit meaning for this terminology and that stops me from fully understanding the author's idea and model mechanism
I check the dictionary and search on line,but the explanation is based more on the real life meaning rather than meaning as a machine learning terminology.
And that raise a more generalized and frequently met question, when you find some machine learning terminology/word that you can't understand well, where can you get the solution, some specific way to google? join a machine learning group? raise a question in stack exchange? | 2019/06/18 | [
"https://datascience.stackexchange.com/questions/53995",
"https://datascience.stackexchange.com",
"https://datascience.stackexchange.com/users/43765/"
] | In the context of machine learning, an embedding is a low-dimensional, learned continuous vector representation of discrete variables into which you can translate high-dimensional vectors. Generally, embeddings make ML models more efficient and easier to work with, and can be used with other models as well.
Typically, when I stumble upon jargon I'm not familiar with I first turn to Google, and if it can't be found I ping my colleagues and data science forums. | According to all answers(Thank you) and my google search I got a better understanding, So my newly updated understanding is:
The embedding in machine learning or NLP is actually a technique mapping from words to vectors which you can do better analysis or relating, for example, "toyota" or "honda" can be hardly related in words, but in vector space it can be set to very close according to some measure, also you can strengthen the relation ship of word by setting: king-man+woman = Queen.
so we can set boy to (1,0) and then set girl to (-1,0) to show they are in the same dimension but the meaning is just opposite. And all nouns that just diff in gender can be parallel~
My initial guess that embedding is extracting features from something is close but not specific enough.
And for my last point when you met a jargon in some special area how to quickly get the essential meaning of it, I still didn't find a very good way, maybe a website that can explain the meaning of jargon in that area will save great time for us. |
53,995 | I just met a terminology called "embedding" in a paper regarding deep learning. The context is "multi-modal embedding"
My guess: embedding of something is extract some feature of sth,to form a vector.
I couldn't get the explicit meaning for this terminology and that stops me from fully understanding the author's idea and model mechanism
I check the dictionary and search on line,but the explanation is based more on the real life meaning rather than meaning as a machine learning terminology.
And that raise a more generalized and frequently met question, when you find some machine learning terminology/word that you can't understand well, where can you get the solution, some specific way to google? join a machine learning group? raise a question in stack exchange? | 2019/06/18 | [
"https://datascience.stackexchange.com/questions/53995",
"https://datascience.stackexchange.com",
"https://datascience.stackexchange.com/users/43765/"
] | In the context of machine learning, an embedding is a low-dimensional, learned continuous vector representation of discrete variables into which you can translate high-dimensional vectors. Generally, embeddings make ML models more efficient and easier to work with, and can be used with other models as well.
Typically, when I stumble upon jargon I'm not familiar with I first turn to Google, and if it can't be found I ping my colleagues and data science forums. | >
> The LSA community seems to have first used the word “embedding” in Landauer
> et al. (1997), in a variant of its mathematical meaning as a mapping from one space or mathematical structure to another. In LSA, the word embedding seems to have described the mapping from the space of sparse count vectors to the latent space of SVD dense vectors. Although the word thus originally meant the mapping from one space to another, it has metonymically shifted to mean the resulting dense vector in the latent space. and it is in this sense that we currently use the word.
>
>
>
For the more generalized and frequently met questions, I'd like to recommend you read textbooks, especially classic ones.
Refrence:
[Speech and Language Processing: An introduction to natural language processing](https://web.stanford.edu/%7Ejurafsky/slp3/ed3book.pdf) |
53,995 | I just met a terminology called "embedding" in a paper regarding deep learning. The context is "multi-modal embedding"
My guess: embedding of something is extract some feature of sth,to form a vector.
I couldn't get the explicit meaning for this terminology and that stops me from fully understanding the author's idea and model mechanism
I check the dictionary and search on line,but the explanation is based more on the real life meaning rather than meaning as a machine learning terminology.
And that raise a more generalized and frequently met question, when you find some machine learning terminology/word that you can't understand well, where can you get the solution, some specific way to google? join a machine learning group? raise a question in stack exchange? | 2019/06/18 | [
"https://datascience.stackexchange.com/questions/53995",
"https://datascience.stackexchange.com",
"https://datascience.stackexchange.com/users/43765/"
] | According to all answers(Thank you) and my google search I got a better understanding, So my newly updated understanding is:
The embedding in machine learning or NLP is actually a technique mapping from words to vectors which you can do better analysis or relating, for example, "toyota" or "honda" can be hardly related in words, but in vector space it can be set to very close according to some measure, also you can strengthen the relation ship of word by setting: king-man+woman = Queen.
so we can set boy to (1,0) and then set girl to (-1,0) to show they are in the same dimension but the meaning is just opposite. And all nouns that just diff in gender can be parallel~
My initial guess that embedding is extracting features from something is close but not specific enough.
And for my last point when you met a jargon in some special area how to quickly get the essential meaning of it, I still didn't find a very good way, maybe a website that can explain the meaning of jargon in that area will save great time for us. | **For me embedding is used to represent big sparse matrix into smaller dimensions, where each dimension(feature) represent a meaningful association with other elements in the embedding matrix.**
Consider an example of NLP. Where each sentence broken down into words(also called token). Such set of different words make a vocabulary for NLP. Generally vocabulary have millions of words. All such words can be uniquely represented as OneHotEncoding.
>
> **Demerits of OneHotEncoding representation of words:**
>
>
> 1. In case of large vocabulary, OneHotEncoding representation needs a
> big chunk of memory and computationally become very expensive.
> 2. OneHotEncoding is used to represent categorical values, where each entity is
> independent to other one, whereas words in vocabulary represent some association in
> terms of similar meanings or in some other way. OneHotEncoding not utilizing that
> capability for NLP.
>
>
>
In order to overcome both the issues, we use word Embedding, where each word represented in lesser dimension, where each dimension represent some sort of features and hence each dimension will have some values. |
53,995 | I just met a terminology called "embedding" in a paper regarding deep learning. The context is "multi-modal embedding"
My guess: embedding of something is extract some feature of sth,to form a vector.
I couldn't get the explicit meaning for this terminology and that stops me from fully understanding the author's idea and model mechanism
I check the dictionary and search on line,but the explanation is based more on the real life meaning rather than meaning as a machine learning terminology.
And that raise a more generalized and frequently met question, when you find some machine learning terminology/word that you can't understand well, where can you get the solution, some specific way to google? join a machine learning group? raise a question in stack exchange? | 2019/06/18 | [
"https://datascience.stackexchange.com/questions/53995",
"https://datascience.stackexchange.com",
"https://datascience.stackexchange.com/users/43765/"
] | According to all answers(Thank you) and my google search I got a better understanding, So my newly updated understanding is:
The embedding in machine learning or NLP is actually a technique mapping from words to vectors which you can do better analysis or relating, for example, "toyota" or "honda" can be hardly related in words, but in vector space it can be set to very close according to some measure, also you can strengthen the relation ship of word by setting: king-man+woman = Queen.
so we can set boy to (1,0) and then set girl to (-1,0) to show they are in the same dimension but the meaning is just opposite. And all nouns that just diff in gender can be parallel~
My initial guess that embedding is extracting features from something is close but not specific enough.
And for my last point when you met a jargon in some special area how to quickly get the essential meaning of it, I still didn't find a very good way, maybe a website that can explain the meaning of jargon in that area will save great time for us. | >
> The LSA community seems to have first used the word “embedding” in Landauer
> et al. (1997), in a variant of its mathematical meaning as a mapping from one space or mathematical structure to another. In LSA, the word embedding seems to have described the mapping from the space of sparse count vectors to the latent space of SVD dense vectors. Although the word thus originally meant the mapping from one space to another, it has metonymically shifted to mean the resulting dense vector in the latent space. and it is in this sense that we currently use the word.
>
>
>
For the more generalized and frequently met questions, I'd like to recommend you read textbooks, especially classic ones.
Refrence:
[Speech and Language Processing: An introduction to natural language processing](https://web.stanford.edu/%7Ejurafsky/slp3/ed3book.pdf) |
53,995 | I just met a terminology called "embedding" in a paper regarding deep learning. The context is "multi-modal embedding"
My guess: embedding of something is extract some feature of sth,to form a vector.
I couldn't get the explicit meaning for this terminology and that stops me from fully understanding the author's idea and model mechanism
I check the dictionary and search on line,but the explanation is based more on the real life meaning rather than meaning as a machine learning terminology.
And that raise a more generalized and frequently met question, when you find some machine learning terminology/word that you can't understand well, where can you get the solution, some specific way to google? join a machine learning group? raise a question in stack exchange? | 2019/06/18 | [
"https://datascience.stackexchange.com/questions/53995",
"https://datascience.stackexchange.com",
"https://datascience.stackexchange.com/users/43765/"
] | In the context of machine learning, an embedding is a low-dimensional, learned continuous vector representation of discrete variables into which you can translate high-dimensional vectors. Generally, embeddings make ML models more efficient and easier to work with, and can be used with other models as well.
Typically, when I stumble upon jargon I'm not familiar with I first turn to Google, and if it can't be found I ping my colleagues and data science forums. | **For me embedding is used to represent big sparse matrix into smaller dimensions, where each dimension(feature) represent a meaningful association with other elements in the embedding matrix.**
Consider an example of NLP. Where each sentence broken down into words(also called token). Such set of different words make a vocabulary for NLP. Generally vocabulary have millions of words. All such words can be uniquely represented as OneHotEncoding.
>
> **Demerits of OneHotEncoding representation of words:**
>
>
> 1. In case of large vocabulary, OneHotEncoding representation needs a
> big chunk of memory and computationally become very expensive.
> 2. OneHotEncoding is used to represent categorical values, where each entity is
> independent to other one, whereas words in vocabulary represent some association in
> terms of similar meanings or in some other way. OneHotEncoding not utilizing that
> capability for NLP.
>
>
>
In order to overcome both the issues, we use word Embedding, where each word represented in lesser dimension, where each dimension represent some sort of features and hence each dimension will have some values. |
53,995 | I just met a terminology called "embedding" in a paper regarding deep learning. The context is "multi-modal embedding"
My guess: embedding of something is extract some feature of sth,to form a vector.
I couldn't get the explicit meaning for this terminology and that stops me from fully understanding the author's idea and model mechanism
I check the dictionary and search on line,but the explanation is based more on the real life meaning rather than meaning as a machine learning terminology.
And that raise a more generalized and frequently met question, when you find some machine learning terminology/word that you can't understand well, where can you get the solution, some specific way to google? join a machine learning group? raise a question in stack exchange? | 2019/06/18 | [
"https://datascience.stackexchange.com/questions/53995",
"https://datascience.stackexchange.com",
"https://datascience.stackexchange.com/users/43765/"
] | According to all answers(Thank you) and my google search I got a better understanding, So my newly updated understanding is:
The embedding in machine learning or NLP is actually a technique mapping from words to vectors which you can do better analysis or relating, for example, "toyota" or "honda" can be hardly related in words, but in vector space it can be set to very close according to some measure, also you can strengthen the relation ship of word by setting: king-man+woman = Queen.
so we can set boy to (1,0) and then set girl to (-1,0) to show they are in the same dimension but the meaning is just opposite. And all nouns that just diff in gender can be parallel~
My initial guess that embedding is extracting features from something is close but not specific enough.
And for my last point when you met a jargon in some special area how to quickly get the essential meaning of it, I still didn't find a very good way, maybe a website that can explain the meaning of jargon in that area will save great time for us. | Embeddings are vector representations of a particular word.
In Machine learning, textual content has to be converted to numerical data to feed it into Algorithm.
One method is one hot encoding but it breaks down when we have large no of vocabulary. The size of word representation grows as the vocabulary grows. Also, it is sparse.
With embedding (fixed size vectors with lower dimension), the size of word representation can be controlled. Also, the vector representation stores the semantic relationship b/w words. There are pretrained embeddings Word2Vec, Glove etc available which can be used just as a lookup. Embeddings improve the performance of ML model significantly. |
53,995 | I just met a terminology called "embedding" in a paper regarding deep learning. The context is "multi-modal embedding"
My guess: embedding of something is extract some feature of sth,to form a vector.
I couldn't get the explicit meaning for this terminology and that stops me from fully understanding the author's idea and model mechanism
I check the dictionary and search on line,but the explanation is based more on the real life meaning rather than meaning as a machine learning terminology.
And that raise a more generalized and frequently met question, when you find some machine learning terminology/word that you can't understand well, where can you get the solution, some specific way to google? join a machine learning group? raise a question in stack exchange? | 2019/06/18 | [
"https://datascience.stackexchange.com/questions/53995",
"https://datascience.stackexchange.com",
"https://datascience.stackexchange.com/users/43765/"
] | >
> The LSA community seems to have first used the word “embedding” in Landauer
> et al. (1997), in a variant of its mathematical meaning as a mapping from one space or mathematical structure to another. In LSA, the word embedding seems to have described the mapping from the space of sparse count vectors to the latent space of SVD dense vectors. Although the word thus originally meant the mapping from one space to another, it has metonymically shifted to mean the resulting dense vector in the latent space. and it is in this sense that we currently use the word.
>
>
>
For the more generalized and frequently met questions, I'd like to recommend you read textbooks, especially classic ones.
Refrence:
[Speech and Language Processing: An introduction to natural language processing](https://web.stanford.edu/%7Ejurafsky/slp3/ed3book.pdf) | Embeddings are vector representations of a particular word.
In Machine learning, textual content has to be converted to numerical data to feed it into Algorithm.
One method is one hot encoding but it breaks down when we have large no of vocabulary. The size of word representation grows as the vocabulary grows. Also, it is sparse.
With embedding (fixed size vectors with lower dimension), the size of word representation can be controlled. Also, the vector representation stores the semantic relationship b/w words. There are pretrained embeddings Word2Vec, Glove etc available which can be used just as a lookup. Embeddings improve the performance of ML model significantly. |
53,995 | I just met a terminology called "embedding" in a paper regarding deep learning. The context is "multi-modal embedding"
My guess: embedding of something is extract some feature of sth,to form a vector.
I couldn't get the explicit meaning for this terminology and that stops me from fully understanding the author's idea and model mechanism
I check the dictionary and search on line,but the explanation is based more on the real life meaning rather than meaning as a machine learning terminology.
And that raise a more generalized and frequently met question, when you find some machine learning terminology/word that you can't understand well, where can you get the solution, some specific way to google? join a machine learning group? raise a question in stack exchange? | 2019/06/18 | [
"https://datascience.stackexchange.com/questions/53995",
"https://datascience.stackexchange.com",
"https://datascience.stackexchange.com/users/43765/"
] | In the context of machine learning, an embedding is a low-dimensional, learned continuous vector representation of discrete variables into which you can translate high-dimensional vectors. Generally, embeddings make ML models more efficient and easier to work with, and can be used with other models as well.
Typically, when I stumble upon jargon I'm not familiar with I first turn to Google, and if it can't be found I ping my colleagues and data science forums. | Embeddings are vector representations of a particular word.
In Machine learning, textual content has to be converted to numerical data to feed it into Algorithm.
One method is one hot encoding but it breaks down when we have large no of vocabulary. The size of word representation grows as the vocabulary grows. Also, it is sparse.
With embedding (fixed size vectors with lower dimension), the size of word representation can be controlled. Also, the vector representation stores the semantic relationship b/w words. There are pretrained embeddings Word2Vec, Glove etc available which can be used just as a lookup. Embeddings improve the performance of ML model significantly. |
13,697 | I live in a 3 bedroom shared house and want to reduce the noise that the bathroom door makes when it closes.
I tried to find a photo of the door. It's basically a old mansion block of apartments in London. The door has a brass knob and stained glass is about an inch thick wooden. I don't know if you can picture the old type of door I am describing? It's very badly sealed. When the door is closed it makes a loud sound when the door touches the door frame, then you twist the knob and then it springs back slightly - all the doors inside the apartment are the same and this one wakes me up at night.
Any ideas? | 2012/04/19 | [
"https://diy.stackexchange.com/questions/13697",
"https://diy.stackexchange.com",
"https://diy.stackexchange.com/users/5943/"
] | I guess you could try putting some thin foam or felt stick on pads on the inside of the door frame where the door contacts it. This should lower the sound of the wood to wood contact. If the knob hardware is also loud, try using some dry silicon spray lubricant on the moving parts and on the door hinges. Sleep well..... | Get narrow weather seal and put it on the door jamb so the door never touches the wood. |
61,196,489 | I created a chat messenger between my website users based on wix repeater when a new msg launch a new row insert into chat collection (my chat collection including the following fields User A, User B, MSG ) and the messenger repeater should refresh for both users.
So if user A send a message to User B
I should do the following :
1. a new row inserts into DB.
2. User A repeater is refresh.
**3. Refresh user B repeater**
What is the best way to Refresh user B repeater?
I used [afterInsert()](https://www.wix.com/corvid/reference/wix-data.Hooks.html#afterInsert) to know which user received a message and when but now I need to send this user a trigger for a refresh.
I thought about sendMessage function after insert to this specific user and then refresh User B repeater when a new msg received [(use onMessage )](https://www.wix.com/corvid/reference/wix-chat-backend.Events.html#onMessage). the main problem is that I don't use wix chat so I can't generate channelId, If there was an option to send a message from a business to a specific user without channelId or alternatively get channelId without using wix chat app, it will solve this problem.
What should I use ? | 2020/04/13 | [
"https://Stackoverflow.com/questions/61196489",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/1921025/"
] | You can use the [Realtime API](https://www.wix.com/corvid/reference/wix-realtime.html) to create a subscriber for the collection on the client. In your backend code in the afterInsert function, publish a message to the specific client which execute the refresh function for the list in the repeater in the callback function. You could store the channel information for the client and backend to know each other alongside your message in your chat collection. | The best thing you can do is here is to set a setInterval() function under the page's onReady() function to refresh user B's dataset/repeater every 3-5 seconds which would check for fresh messages. |
129,334 | I have a compound, dimethylaminoethanol (DMAE) bitartrate, which I originally purchased as a supplement and possible smart drug. I bought an absurd amount of it. It didn’t do anything for me as a supplement. I understand that DMAE, not the bitartrate salt, is commonly used in cosmetics, & I’d like to play with it for that purposes, maybe mixing it with glycerin, etc. Is there a simple way to strip off the bitartrate anion and have it precipitate or sublimate or something, leaving the DMAE behind? Or otherwise separating the DMAE out from the salt?
I have a strong preference for any other reactants and reaction products being non-toxic | 2020/03/21 | [
"https://chemistry.stackexchange.com/questions/129334",
"https://chemistry.stackexchange.com",
"https://chemistry.stackexchange.com/users/90071/"
] | I see on Wikipedia: "Dimethylethanolamine (DMAE or DMEA) is an organic compound with the formula (CH3)2NCH2CH2OH. It is bifunctional, containing both a tertiary amine and primary alcohol functional groups. It is a colorless viscous liquid. It is used in skin care products."
Now the fact that it is used in skin care products does not make it safe: the SDS (<https://www.fishersci.com/store/msds?partNumber=AC116180010&productDescription=N%2CN-DIMETHYLETHANOLAMINE+1LT&vendorId=VN00032119&countryCode=US&language=en>) shows these pictograms:
[](https://i.stack.imgur.com/zWflw.png)
Uh oh! Oh, well.
Well, let's forget that for a minute. DMAE is a liquid, boiling at 134C. Bitartrate anion is very insoluble if attached to potassium (potassium bitartrate is cream of tartar). If you added a stoichiometric amount of potassium bicarbonate (KHCO3, quite safe) to an aqueous solution of DMAE, you would precipitate almost all of the bitartrate, leaving the DMAE in water. Filter off the ppt and distill off the water and then distill and collect the DMAE. It will probably be a little wet and you will hate the overwhelming fishy smell.
Oh, and use a respirator (from the SDS: "Follow the OSHA respirator regulations found in 29 CFR 1910.134 or European Standard EN 149. Use a NIOSH/MSHA or European Standard EN 149 approved respirator if exposure limits are exceeded or if irritation or other symptoms are experienced.")
Good luck. Actually, I think you will have better luck if you do something else. | This might work:
Make a solution of NaOH in absolute ethanol, e.g. at a 1 mol/L concentration. Suspend the DMAE bitartrate in ethanol, and add 2 equivalents of the NaOH solution slowly to the suspension, making sure it doesn't heat up too much. After everything is added, stir or agitate it for a while. Then filter off the solids and wash them with some ethanol. Add the washings to the ethanol solution. From this solution, let the ethanol evaporate, and only DMAE should remain. The solids are sodium tartrate. |
4,850 | I've read various pieces arguing that the USA is not a democracy, but a (fill in the blank, ex., a Republic). Perhaps there is no perfect fit, but **which form of government does the USA most closely match?** | 2014/09/13 | [
"https://politics.stackexchange.com/questions/4850",
"https://politics.stackexchange.com",
"https://politics.stackexchange.com/users/4459/"
] | The definition of democracy varies, but for most definitions used, **yes, the USA is a democracy.**
Wikipedia's article on [Liberal Democracy](http://en.wikipedia.org/wiki/Liberal_democracy) defines a liberal democracy as follows:
>
> It is characterised by fair, free, and competitive elections between multiple distinct political parties, a separation of powers into different branches of government, the rule of law in everyday life as part of an open society, and the equal protection of human rights, civil rights, civil liberties, and political freedoms for all persons.
>
>
>
Though Gerrymandering and geographical concentrations of like-minded voters make elections [less and less competitive](http://fivethirtyeight.blogs.nytimes.com/2012/12/27/as-swing-districts-dwindle-can-a-divided-house-stand/?_php=true&_type=blogs&_r=0), the United States meets these criteria. Elections are not, by and large, systematically rigged in favor of a single party, open to almost every adult American citizen (with the notable exception of [some felons in some states](http://en.wikipedia.org/wiki/Felony_disenfranchisement#United_States)), and there are multiple political parties that endorse different policies. Power is separated into an Executive, Legislative, and Judicial branch, and the Constitution guarantees certain civil rights and liberties.
The article also lists a number of Democracies, noting that they can be compatible with other forms of government:
>
> A liberal democracy may take various constitutional forms: it may be a constitutional republic, such as France, Germany, India, Ireland, Italy, or the **United States**
>
>
>
(Emphasis mine).
However, democracies need not be liberal democracies. We can define a democracy [more narrowly](http://en.wikipedia.org/wiki/Democracy), as
>
> a form of government in which all eligible citizens are meant to participate equally – either directly or, through elected representatives, indirectly – in the proposal, development and establishment of the laws by which their society is run.
>
>
>
At these criteria are the subset of a criteria for a liberal democracy, than any liberal democracy is also a democracy. If we can consider the United States a liberal democracy, we can consider it a democracy.
One can argue that the United States does not meet all these criteria perfectly. Many felons are not allowed to vote, and per-state representation in the Senate means that not every voter has equal say in how laws are made or conducted. However, nobody's perfect. Keeping this in mind, some organizations have chosen to rank countries by how democratic they are, taking into account multiple criteria. These organizations' definitions of democracy vary, but they tend to consider the USA a democracy.
The Economist Intelligence Unit gives America a rating of [8.11 out of 10](http://pages.eiu.com/rs/eiu2/images/Democracy-Index-2012.pdf). It considers any country with a ranking better than an 8 a "full democracy". By This definition, America is a Democracy. Freedom House has a list of electoral democracies which [includes America](http://freedomhouse.org/sites/default/files/FIW%202014%20Scores%20-%20Countries%20and%20Territories.pdf), and also lists America as a ["free"](http://en.wikipedia.org/wiki/Freedom_House#Freedom_in_the_World) country.
It should be noted that a government can be a democracy and a republic, or even a democracy and a monarchy. The principles of democracy imply very little in the formal structure of a government. You can have a democracy that involves direct voting on certain issues, like in [California](http://en.wikipedia.org/wiki/California_ballot_proposition), or you can have a monarch with Constitutionally limited powers, like in the [United Kingdom](http://en.wikipedia.org/wiki/United_Kingdom), or a Republican Democracy without an elected head of government and no monarch, like the United States. | The United States is a **[Representational Democracy](http://en.wikipedia.org/wiki/Representative_democracy)**. The people have no direct say in government, but have the ability to freely vote for those who *do* have direct say (the people's representatives).
This is contrast to a Direct Democracy (which is also sometimes called just a "Democracy" or a "pure democracy"), where every citizen is entitled to a vote on every issue (such as ancient Athens), and a Delegate Democracy where citizens may temporarily give their votes to a chosen delegate who can vote them as a bloc (similar to a corporate board). There are [other types of democracy](http://en.wikipedia.org/wiki/Types_of_democracy) it's also not.
It is also a Republic, which is a term that can be applied to any country which is democratic but not a direct democracy. Technically, this makes the US a [Democratic Republic](http://en.wikipedia.org/wiki/Democratic_republic), but the countries which currently use that term do *not* use it in that way, and that usage isn't common. |
4,850 | I've read various pieces arguing that the USA is not a democracy, but a (fill in the blank, ex., a Republic). Perhaps there is no perfect fit, but **which form of government does the USA most closely match?** | 2014/09/13 | [
"https://politics.stackexchange.com/questions/4850",
"https://politics.stackexchange.com",
"https://politics.stackexchange.com/users/4459/"
] | The definition of democracy varies, but for most definitions used, **yes, the USA is a democracy.**
Wikipedia's article on [Liberal Democracy](http://en.wikipedia.org/wiki/Liberal_democracy) defines a liberal democracy as follows:
>
> It is characterised by fair, free, and competitive elections between multiple distinct political parties, a separation of powers into different branches of government, the rule of law in everyday life as part of an open society, and the equal protection of human rights, civil rights, civil liberties, and political freedoms for all persons.
>
>
>
Though Gerrymandering and geographical concentrations of like-minded voters make elections [less and less competitive](http://fivethirtyeight.blogs.nytimes.com/2012/12/27/as-swing-districts-dwindle-can-a-divided-house-stand/?_php=true&_type=blogs&_r=0), the United States meets these criteria. Elections are not, by and large, systematically rigged in favor of a single party, open to almost every adult American citizen (with the notable exception of [some felons in some states](http://en.wikipedia.org/wiki/Felony_disenfranchisement#United_States)), and there are multiple political parties that endorse different policies. Power is separated into an Executive, Legislative, and Judicial branch, and the Constitution guarantees certain civil rights and liberties.
The article also lists a number of Democracies, noting that they can be compatible with other forms of government:
>
> A liberal democracy may take various constitutional forms: it may be a constitutional republic, such as France, Germany, India, Ireland, Italy, or the **United States**
>
>
>
(Emphasis mine).
However, democracies need not be liberal democracies. We can define a democracy [more narrowly](http://en.wikipedia.org/wiki/Democracy), as
>
> a form of government in which all eligible citizens are meant to participate equally – either directly or, through elected representatives, indirectly – in the proposal, development and establishment of the laws by which their society is run.
>
>
>
At these criteria are the subset of a criteria for a liberal democracy, than any liberal democracy is also a democracy. If we can consider the United States a liberal democracy, we can consider it a democracy.
One can argue that the United States does not meet all these criteria perfectly. Many felons are not allowed to vote, and per-state representation in the Senate means that not every voter has equal say in how laws are made or conducted. However, nobody's perfect. Keeping this in mind, some organizations have chosen to rank countries by how democratic they are, taking into account multiple criteria. These organizations' definitions of democracy vary, but they tend to consider the USA a democracy.
The Economist Intelligence Unit gives America a rating of [8.11 out of 10](http://pages.eiu.com/rs/eiu2/images/Democracy-Index-2012.pdf). It considers any country with a ranking better than an 8 a "full democracy". By This definition, America is a Democracy. Freedom House has a list of electoral democracies which [includes America](http://freedomhouse.org/sites/default/files/FIW%202014%20Scores%20-%20Countries%20and%20Territories.pdf), and also lists America as a ["free"](http://en.wikipedia.org/wiki/Freedom_House#Freedom_in_the_World) country.
It should be noted that a government can be a democracy and a republic, or even a democracy and a monarchy. The principles of democracy imply very little in the formal structure of a government. You can have a democracy that involves direct voting on certain issues, like in [California](http://en.wikipedia.org/wiki/California_ballot_proposition), or you can have a monarch with Constitutionally limited powers, like in the [United Kingdom](http://en.wikipedia.org/wiki/United_Kingdom), or a Republican Democracy without an elected head of government and no monarch, like the United States. | You cannot counter-posite democracy to a republic. Republic is a well-defined form of state. As such, the US is republic. Democracy is a form of government. There can be various degree of democracy and various opinions on what practice is more democratic. |
4,850 | I've read various pieces arguing that the USA is not a democracy, but a (fill in the blank, ex., a Republic). Perhaps there is no perfect fit, but **which form of government does the USA most closely match?** | 2014/09/13 | [
"https://politics.stackexchange.com/questions/4850",
"https://politics.stackexchange.com",
"https://politics.stackexchange.com/users/4459/"
] | The United States is a **[Representational Democracy](http://en.wikipedia.org/wiki/Representative_democracy)**. The people have no direct say in government, but have the ability to freely vote for those who *do* have direct say (the people's representatives).
This is contrast to a Direct Democracy (which is also sometimes called just a "Democracy" or a "pure democracy"), where every citizen is entitled to a vote on every issue (such as ancient Athens), and a Delegate Democracy where citizens may temporarily give their votes to a chosen delegate who can vote them as a bloc (similar to a corporate board). There are [other types of democracy](http://en.wikipedia.org/wiki/Types_of_democracy) it's also not.
It is also a Republic, which is a term that can be applied to any country which is democratic but not a direct democracy. Technically, this makes the US a [Democratic Republic](http://en.wikipedia.org/wiki/Democratic_republic), but the countries which currently use that term do *not* use it in that way, and that usage isn't common. | You cannot counter-posite democracy to a republic. Republic is a well-defined form of state. As such, the US is republic. Democracy is a form of government. There can be various degree of democracy and various opinions on what practice is more democratic. |
8,279,605 | I've been reading [Code Complete 2](https://rads.stackoverflow.com/amzn/click/com/0735619670). As I am not native english speaker some statements take some time for me to understand. I would like you to describe the difference between these two statements the author made in his book:
>
> 1. You should program into Your Language (programming language).
> 2. You shouldn't program in Your Language.
>
>
>
Why **in** is bad and **into** is recommended? | 2011/11/26 | [
"https://Stackoverflow.com/questions/8279605",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/44852/"
] | Program **into** your language means that you *use* the language to construct the "missing" pieces - leverage it to do more than it currently does. Things like creating missing data structure, algorithms and ways of accomplishing tasks that are not native to the language.
Program **in** your language means just that - not trying to leverage it.
I thought the examples given in the book were quite good. | The author provides an example of his own in that part of the book (which unfortunately I don't remember). You can try reading a bit further.
It means that even if the language doesn't support a particularly convenient feature, as you should always think of writing readable, easy to maintain, modular code, you should try to find a way to emulate that feature even if its not enforced by the language, then you would document that, so that other developers who may modify the code stick to the same rule. I can't provide an example right now, but I think is easy to see the rationale. |
8,279,605 | I've been reading [Code Complete 2](https://rads.stackoverflow.com/amzn/click/com/0735619670). As I am not native english speaker some statements take some time for me to understand. I would like you to describe the difference between these two statements the author made in his book:
>
> 1. You should program into Your Language (programming language).
> 2. You shouldn't program in Your Language.
>
>
>
Why **in** is bad and **into** is recommended? | 2011/11/26 | [
"https://Stackoverflow.com/questions/8279605",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/44852/"
] | As I understand it, it means to think outside of the bounds of your programming language.
So **in** means you are thinking in terms of the language, so your thinking is limited by the language itself, and the program you write may not be easily translated into some other language if needed.
But **into** means you think in algorithms, i.e. freely, then translate into your desired language. So you can easily code in any language you know the syntax of.
But as I have not read the book actually, this may be totally wrong per the context. | The author provides an example of his own in that part of the book (which unfortunately I don't remember). You can try reading a bit further.
It means that even if the language doesn't support a particularly convenient feature, as you should always think of writing readable, easy to maintain, modular code, you should try to find a way to emulate that feature even if its not enforced by the language, then you would document that, so that other developers who may modify the code stick to the same rule. I can't provide an example right now, but I think is easy to see the rationale. |
344,954 | I'm trying to switch over from USB power to external power if it's present. (External power is 6V to 13V). The current is 2A.
To do this I'm using diodes 1 and 3. See image below. ("OR" configuration.)
I'm then using diode 2 as reverse voltage protection in case the external power is connected backwards. (To avoid destroying the computer by raising the 5V USB power line to 13V.)
Is there a better way to do this? The amount of voltage and heat wasted by the 3 diodes is huge (at 2A).
Can I perhaps use 3 ideal diodes? Something like this?
<http://datasheet.octopart.com/FR014H5JZ-ON-Semiconductor-datasheet-85537694.pdf>
What's the standard way to solve this problem? | 2017/12/14 | [
"https://electronics.stackexchange.com/questions/344954",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/122765/"
] | That's right, your reverse protection chip uses an internal MOSFET to achieve lossless switching.
I seem to recall seeing a "drop-in replacement for a diode" kind of FET-based device, but I can't seem to find it now.
MOSFET's with dedicated secondary-side controllers are used for synchronous rectification in higher-end modern power supplies (and in low-volt VRM's on modern PC motherboards).
Speaking of a "diode OR" in a redundant power supply scenario, I've found another [relevant link](http://www.linear.com/product/LT4351) at LT's website... | For D2 and D3, you should consider Schottky diodes. These have a significantly lower voltage drop than standard diodes, maybe 400 mV instead of 1 V at typical load current, so you'll lose a lot less power.
For D1, if the drop of a Schottky diode is still too high, the part you've linked to looks like a valid option - I have no experience with this type of IC though. You may also find these answers helpful:
[Switch between 5V power supplies?](https://electronics.stackexchange.com/questions/401/switch-between-5v-power-supplies)
[Switch between battery and USB power](https://electronics.stackexchange.com/questions/21570/switch-between-battery-and-usb-power)
Where does your 'USB' supply come from though? You're not guaranteed to be able to draw more than **100 mA** from an actual USB port unless your device negotiates with the host for more. |
150,046 | I've got a small shaded pole motor (C-type) that I'm cannibalizing for use in a project, but the current RPM is too high. I don't want to spend the effort to build a micro-controller to run it.
Is there a way to easily change the RPM by making a relative change to the wound coil? For instance, it's currently running at 2750 RPM, it's 80W, 220V and there are 1500 windings on the coil. Without going into serious design formulas and discussions, are there 'rules of thumb' that I can use to change the RPM? For instance, to half the RPM, half the number of windings, double the wire gauge, or something similar. I'm not aiming at a specific target (RPM wise) I just want it slower - somewhere between one third, and a half of the current RPM. | 2015/01/20 | [
"https://electronics.stackexchange.com/questions/150046",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/64779/"
] | A shaded pole motor is a type of induction motor, just using some neat magnetic tricks to generate a second phase. It runs at slightly below synchronous speed, the slip depends on the torque.
For a simple 2 pole motor, you'd expect it to run at perhaps 90% of 3000 rpm (50 Hz countries), or 3600 rpm (60 Hz). This is what you are seeing.
If you reduce the voltage, with a series inductor or resistor, the motor will produce less power and depending on the load, the speed will drop and the slip increase. However the torque drops very quickly at reduced speeds, so it's unlikely you will get anywhere near as low as 50% of synchronous speed.
I think that removing turns, keeping the voltage constant, will increase the current and make it run slightly faster against the same load.
[This site](http://www.johnsonelectric.com/en/resources-for-engineers/motors/motor-design-considerations/shaded-pole-motors.html) has some diagrams and specifications. The speed when running below rated speed will be very dependent on the torque curve of the load.
So unfortunately you can only reliably reduce the speed of the motor by reducing the AC supply frequency (and voltage) with a variable speed drive. | Those answers are just mumbo-jumbo-babble. Just use a rheostat at 1000 ohms and plenty of amps ratings. Ohmite makes the best. A rheostat varies the current going through the motor. Research it and you'll see that I'm right. Not many people knows that. Laboratory stir plate are made with a shaded pole motor, a switch and a rheostat. That's all. And their speed is variable from 5% to 100%. Be careful, the rheostat gets hot. It's supposed to do that. That's why the windings are made of nichrome wire wrapped around a ceramic core. Good luck. |
75,351 | <https://www.france24.com/en/live-news/20220909-ukraine-reconstruction-to-cost-349-bn-report>
>
> Rebuilding Ukraine following the devastation caused by the Russian
> invasion will cost an estimated $349 billion, according to a report
> issued Friday.
>
>
> But the figure, which totals 1.5 times the size of the Ukrainian
> economy, is considered a minimum and is expected to grow in the coming
> months as the war continues, according to the joint assessment by the
> government of Ukraine, the European Commission, and the World Bank.
>
>
>
It has been reported that it would cost 349 billion to reconstruct Ukraine as it was before. I heard that the U.S. possess around 300 billion in frozen Russian asset, and I was wondering if the U.S. had the legal means to use that fund "illegally" and use it to finance the reconstruction of Ukraine? Is there a legal precedent for doing something similar? | 2022/09/09 | [
"https://politics.stackexchange.com/questions/75351",
"https://politics.stackexchange.com",
"https://politics.stackexchange.com/users/38301/"
] | **Legal from what perspective?**
International law consists of the assumption that states are [sovereign](https://en.wikipedia.org/wiki/Westphalian_sovereignty), and negotiated or customary rules between them. Just which customary rules are established enough to be [jus cogens](https://en.wikipedia.org/wiki/Peremptory_norm), binding on all states, is not finally clear. The ability of one state to deposit money in another state and get it back is **not guaranteed**. On the other hand, historically theft on this scale might have been a [casus belli](https://en.wikipedia.org/wiki/Casus_belli).
But simply taking that money would be a grave breach of trust into the financial services of a country, unless most or all *other* nations agree that it is a very special case. Russia is [arguing internationally](https://tass.com/economy/1504031) that Western sanction policies are a threat to the rest of the world. The Western [filter bubble](https://en.wikipedia.org/wiki/Filter_bubble) tends to dismiss it as propaganda, but it has some succes in the rest of the world.
If the US takes Russian money, would China, Saudi Arabia, India, Brazil trust American banks? And if they *don't* trust them, can they find an alternative?
---
*Follow-up: as you can see from the comments which have since been removed, some readers seem to think that I share the Russian position. I do not. But I do believe that (too) much of the rest of the world shares it, and that the West needs to be careful not to play into Russian narratives. Global support for sanctions is* not *automatic, it takes effort to maintain it.* | **Yes**.
The only potential hurdle to it would be sovereign immunity. But **sovereign immunity can be removed with a legislation**. There are already laws which remove sovereign immunity to civil law suits.
The criteria for sovereign immunity are established in [Foreign Sovereign Immunities Act](https://en.wikipedia.org/wiki/Foreign_Sovereign_Immunities_Act). But the act can be amended to allow more situations in which law suits can occur. ***For example***, [JASTA](https://en.wikipedia.org/wiki/Justice_Against_Sponsors_of_Terrorism_Act) amends it to:
>
> authorize federal courts to exercise subject matter jurisdiction over any foreign state's support for acts of international terrorism against a U.S. national or property regardless of whether such state is designated as a state sponsor of terrorism.
>
>
>
Other amendments can be passed to create exceptions to allow law suits under some other sets of limited circumstances. |
75,351 | <https://www.france24.com/en/live-news/20220909-ukraine-reconstruction-to-cost-349-bn-report>
>
> Rebuilding Ukraine following the devastation caused by the Russian
> invasion will cost an estimated $349 billion, according to a report
> issued Friday.
>
>
> But the figure, which totals 1.5 times the size of the Ukrainian
> economy, is considered a minimum and is expected to grow in the coming
> months as the war continues, according to the joint assessment by the
> government of Ukraine, the European Commission, and the World Bank.
>
>
>
It has been reported that it would cost 349 billion to reconstruct Ukraine as it was before. I heard that the U.S. possess around 300 billion in frozen Russian asset, and I was wondering if the U.S. had the legal means to use that fund "illegally" and use it to finance the reconstruction of Ukraine? Is there a legal precedent for doing something similar? | 2022/09/09 | [
"https://politics.stackexchange.com/questions/75351",
"https://politics.stackexchange.com",
"https://politics.stackexchange.com/users/38301/"
] | Apparently a precedent for doing so (i.e. unlocking frozen Russian assets to use in the rebuilding of Ukraine) exists legally somewhere in the Iraqi 1990 invasion of Kuwait, according to Philip Zelikow at the University of Virginia. But I'm curious as to why it must be "the U.S." that facilitates this process. What, are they ("we" actually, as I'm American) bigger than the international community writ large? And isn't the knee-jerk assumption that this is purely the U.S.'s prerogative just a reflection of the sort of rigid mindset that Russia (and, increasingly, the Global South led by China) is lashing out at in the first place? <https://www.lawfareblog.com/legal-approach-transfer-russian-assets-rebuild-ukraine> | **Yes**.
The only potential hurdle to it would be sovereign immunity. But **sovereign immunity can be removed with a legislation**. There are already laws which remove sovereign immunity to civil law suits.
The criteria for sovereign immunity are established in [Foreign Sovereign Immunities Act](https://en.wikipedia.org/wiki/Foreign_Sovereign_Immunities_Act). But the act can be amended to allow more situations in which law suits can occur. ***For example***, [JASTA](https://en.wikipedia.org/wiki/Justice_Against_Sponsors_of_Terrorism_Act) amends it to:
>
> authorize federal courts to exercise subject matter jurisdiction over any foreign state's support for acts of international terrorism against a U.S. national or property regardless of whether such state is designated as a state sponsor of terrorism.
>
>
>
Other amendments can be passed to create exceptions to allow law suits under some other sets of limited circumstances. |
75,351 | <https://www.france24.com/en/live-news/20220909-ukraine-reconstruction-to-cost-349-bn-report>
>
> Rebuilding Ukraine following the devastation caused by the Russian
> invasion will cost an estimated $349 billion, according to a report
> issued Friday.
>
>
> But the figure, which totals 1.5 times the size of the Ukrainian
> economy, is considered a minimum and is expected to grow in the coming
> months as the war continues, according to the joint assessment by the
> government of Ukraine, the European Commission, and the World Bank.
>
>
>
It has been reported that it would cost 349 billion to reconstruct Ukraine as it was before. I heard that the U.S. possess around 300 billion in frozen Russian asset, and I was wondering if the U.S. had the legal means to use that fund "illegally" and use it to finance the reconstruction of Ukraine? Is there a legal precedent for doing something similar? | 2022/09/09 | [
"https://politics.stackexchange.com/questions/75351",
"https://politics.stackexchange.com",
"https://politics.stackexchange.com/users/38301/"
] | **Legal from what perspective?**
International law consists of the assumption that states are [sovereign](https://en.wikipedia.org/wiki/Westphalian_sovereignty), and negotiated or customary rules between them. Just which customary rules are established enough to be [jus cogens](https://en.wikipedia.org/wiki/Peremptory_norm), binding on all states, is not finally clear. The ability of one state to deposit money in another state and get it back is **not guaranteed**. On the other hand, historically theft on this scale might have been a [casus belli](https://en.wikipedia.org/wiki/Casus_belli).
But simply taking that money would be a grave breach of trust into the financial services of a country, unless most or all *other* nations agree that it is a very special case. Russia is [arguing internationally](https://tass.com/economy/1504031) that Western sanction policies are a threat to the rest of the world. The Western [filter bubble](https://en.wikipedia.org/wiki/Filter_bubble) tends to dismiss it as propaganda, but it has some succes in the rest of the world.
If the US takes Russian money, would China, Saudi Arabia, India, Brazil trust American banks? And if they *don't* trust them, can they find an alternative?
---
*Follow-up: as you can see from the comments which have since been removed, some readers seem to think that I share the Russian position. I do not. But I do believe that (too) much of the rest of the world shares it, and that the West needs to be careful not to play into Russian narratives. Global support for sanctions is* not *automatic, it takes effort to maintain it.* | Apparently a precedent for doing so (i.e. unlocking frozen Russian assets to use in the rebuilding of Ukraine) exists legally somewhere in the Iraqi 1990 invasion of Kuwait, according to Philip Zelikow at the University of Virginia. But I'm curious as to why it must be "the U.S." that facilitates this process. What, are they ("we" actually, as I'm American) bigger than the international community writ large? And isn't the knee-jerk assumption that this is purely the U.S.'s prerogative just a reflection of the sort of rigid mindset that Russia (and, increasingly, the Global South led by China) is lashing out at in the first place? <https://www.lawfareblog.com/legal-approach-transfer-russian-assets-rebuild-ukraine> |
75,351 | <https://www.france24.com/en/live-news/20220909-ukraine-reconstruction-to-cost-349-bn-report>
>
> Rebuilding Ukraine following the devastation caused by the Russian
> invasion will cost an estimated $349 billion, according to a report
> issued Friday.
>
>
> But the figure, which totals 1.5 times the size of the Ukrainian
> economy, is considered a minimum and is expected to grow in the coming
> months as the war continues, according to the joint assessment by the
> government of Ukraine, the European Commission, and the World Bank.
>
>
>
It has been reported that it would cost 349 billion to reconstruct Ukraine as it was before. I heard that the U.S. possess around 300 billion in frozen Russian asset, and I was wondering if the U.S. had the legal means to use that fund "illegally" and use it to finance the reconstruction of Ukraine? Is there a legal precedent for doing something similar? | 2022/09/09 | [
"https://politics.stackexchange.com/questions/75351",
"https://politics.stackexchange.com",
"https://politics.stackexchange.com/users/38301/"
] | **Legal from what perspective?**
International law consists of the assumption that states are [sovereign](https://en.wikipedia.org/wiki/Westphalian_sovereignty), and negotiated or customary rules between them. Just which customary rules are established enough to be [jus cogens](https://en.wikipedia.org/wiki/Peremptory_norm), binding on all states, is not finally clear. The ability of one state to deposit money in another state and get it back is **not guaranteed**. On the other hand, historically theft on this scale might have been a [casus belli](https://en.wikipedia.org/wiki/Casus_belli).
But simply taking that money would be a grave breach of trust into the financial services of a country, unless most or all *other* nations agree that it is a very special case. Russia is [arguing internationally](https://tass.com/economy/1504031) that Western sanction policies are a threat to the rest of the world. The Western [filter bubble](https://en.wikipedia.org/wiki/Filter_bubble) tends to dismiss it as propaganda, but it has some succes in the rest of the world.
If the US takes Russian money, would China, Saudi Arabia, India, Brazil trust American banks? And if they *don't* trust them, can they find an alternative?
---
*Follow-up: as you can see from the comments which have since been removed, some readers seem to think that I share the Russian position. I do not. But I do believe that (too) much of the rest of the world shares it, and that the West needs to be careful not to play into Russian narratives. Global support for sanctions is* not *automatic, it takes effort to maintain it.* | The context matters.
If to ask "can and would USA just nationalize arbitrary foreign accounts for no reasons", the answer is likely no and all talks about "undermined trust" are relevant. But there is more than that in the context.
If I launch a rocket from my yard and destroy a house of my neighbor, it cannot be there is absolutely no legal basis to ask me to pay for rebuild. Even if I start to argue the launch was "somewhat provoked". Of course it must be a law court, the judges will decide, Russia will have the word to say, but I do not see how they can come up dry out of this swamp. Other answers contain references to the possible legal approaches.
It is the same as with economic sanctions, with visas, with closing the airspace. These all may have questionable legality if done for a random country without any visible reason.
There is a reason. I do not think there is any country outside your "filter bubble" that thinks it is Ukraine that invaded Russia or that comparable part of Russian civil infrastructure has been destroyed.
USA and EU may not be able to provide hundreds of billions required to repair the damage done for Ukraine. Leaving the country "as is" means creating a large unstable region with very unpredictable future. It may be no other way as to use this money. |
75,351 | <https://www.france24.com/en/live-news/20220909-ukraine-reconstruction-to-cost-349-bn-report>
>
> Rebuilding Ukraine following the devastation caused by the Russian
> invasion will cost an estimated $349 billion, according to a report
> issued Friday.
>
>
> But the figure, which totals 1.5 times the size of the Ukrainian
> economy, is considered a minimum and is expected to grow in the coming
> months as the war continues, according to the joint assessment by the
> government of Ukraine, the European Commission, and the World Bank.
>
>
>
It has been reported that it would cost 349 billion to reconstruct Ukraine as it was before. I heard that the U.S. possess around 300 billion in frozen Russian asset, and I was wondering if the U.S. had the legal means to use that fund "illegally" and use it to finance the reconstruction of Ukraine? Is there a legal precedent for doing something similar? | 2022/09/09 | [
"https://politics.stackexchange.com/questions/75351",
"https://politics.stackexchange.com",
"https://politics.stackexchange.com/users/38301/"
] | Apparently a precedent for doing so (i.e. unlocking frozen Russian assets to use in the rebuilding of Ukraine) exists legally somewhere in the Iraqi 1990 invasion of Kuwait, according to Philip Zelikow at the University of Virginia. But I'm curious as to why it must be "the U.S." that facilitates this process. What, are they ("we" actually, as I'm American) bigger than the international community writ large? And isn't the knee-jerk assumption that this is purely the U.S.'s prerogative just a reflection of the sort of rigid mindset that Russia (and, increasingly, the Global South led by China) is lashing out at in the first place? <https://www.lawfareblog.com/legal-approach-transfer-russian-assets-rebuild-ukraine> | The context matters.
If to ask "can and would USA just nationalize arbitrary foreign accounts for no reasons", the answer is likely no and all talks about "undermined trust" are relevant. But there is more than that in the context.
If I launch a rocket from my yard and destroy a house of my neighbor, it cannot be there is absolutely no legal basis to ask me to pay for rebuild. Even if I start to argue the launch was "somewhat provoked". Of course it must be a law court, the judges will decide, Russia will have the word to say, but I do not see how they can come up dry out of this swamp. Other answers contain references to the possible legal approaches.
It is the same as with economic sanctions, with visas, with closing the airspace. These all may have questionable legality if done for a random country without any visible reason.
There is a reason. I do not think there is any country outside your "filter bubble" that thinks it is Ukraine that invaded Russia or that comparable part of Russian civil infrastructure has been destroyed.
USA and EU may not be able to provide hundreds of billions required to repair the damage done for Ukraine. Leaving the country "as is" means creating a large unstable region with very unpredictable future. It may be no other way as to use this money. |
77,515 | In general I have found that as the focal length of 35mm (or APS-C) lenses increases, the physical length of the lens increases as well. However, my large format lens is much thinner than other 35mm lenses of equivalent focal length. Here is a picture:
[](https://i.stack.imgur.com/oNMHx.jpg)
The large format lens is a Wollensak Raptar 135mm f4.7, and it not more than 5 cm long. The lens next to it (albeit slightly unfair as it is a zoom) is a Sun telephoto zoom, 85mm-210mm f3.8. In general all large format lenses seem to be rather diminutive in length. Why is this? | 2016/05/18 | [
"https://photo.stackexchange.com/questions/77515",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/36933/"
] | The focal length is the distance from the (theoretical) center of the lens to the image plane. On the large format camera, there's a lot more *camera* between the lens and the film.
The lenses are also often relatively simple — there's no need for a focusing mechanism in the lens itself, for example.
@osullic gives the example of the [Schneider PC TS Makro-Symmar 90mm f/4.5](http://www.bhphotovideo.com/c/product/818360-REG/Schneider_06_1064382_PC_TS_Super_Angulon.html) for 35mm and [Schneider 90mm f/4.5 Apo Digitar N](http://www.bhphotovideo.com/c/product/400328-REG/Schneider_03_017780_90mm_f_4_5_Apo_Digitar.html) for large format. They appear to have similar optical design (six elements in four groups), and this is particularly interesting, because the former is a *tilt/shift* lens. Tilt lets you change the angle of the focal plane for depth-of-field effects; shift changes the appearance of parallel lines. As with focus, tilt and shift are both adjustable in large format by adjustments *to the camera*.
So, basically, with 35mm, much of what would be in the camera in large format is *moved to the lens*, which of course makes the lens bigger. | A few points to consider (mostly adding to mattdm's answer):
A manually focusing 135mm Nikkor 2.8 lens in F mount is about 91.5mm long, and looking at a drawing of the lens most of the optical elements are in the front. So a comparison with a zoom lens isn't really fair -- it is a much more complicated lens.
Strictly speaking, a telephoto lens is one designed to be shorter than its focal length, otherwise a 500mm lens on an SLR would be mostly a big empty tube with optical elements at the end. The telephoto design allows the lens to be shorter but requires more optical elements. In a view camera this type of construction isn't normally needed as the camera bellows can expand or contract to suit the needs of a wide range of focal lengths (and focusing distances).
See also:
<https://en.wikipedia.org/wiki/Telephoto_lens>
<http://www.mir.com.my/rb/photography/companies/nikon/nikkoresources/135mmnikkor/135mm28.htm> |
77,515 | In general I have found that as the focal length of 35mm (or APS-C) lenses increases, the physical length of the lens increases as well. However, my large format lens is much thinner than other 35mm lenses of equivalent focal length. Here is a picture:
[](https://i.stack.imgur.com/oNMHx.jpg)
The large format lens is a Wollensak Raptar 135mm f4.7, and it not more than 5 cm long. The lens next to it (albeit slightly unfair as it is a zoom) is a Sun telephoto zoom, 85mm-210mm f3.8. In general all large format lenses seem to be rather diminutive in length. Why is this? | 2016/05/18 | [
"https://photo.stackexchange.com/questions/77515",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/36933/"
] | The focal length is the distance from the (theoretical) center of the lens to the image plane. On the large format camera, there's a lot more *camera* between the lens and the film.
The lenses are also often relatively simple — there's no need for a focusing mechanism in the lens itself, for example.
@osullic gives the example of the [Schneider PC TS Makro-Symmar 90mm f/4.5](http://www.bhphotovideo.com/c/product/818360-REG/Schneider_06_1064382_PC_TS_Super_Angulon.html) for 35mm and [Schneider 90mm f/4.5 Apo Digitar N](http://www.bhphotovideo.com/c/product/400328-REG/Schneider_03_017780_90mm_f_4_5_Apo_Digitar.html) for large format. They appear to have similar optical design (six elements in four groups), and this is particularly interesting, because the former is a *tilt/shift* lens. Tilt lets you change the angle of the focal plane for depth-of-field effects; shift changes the appearance of parallel lines. As with focus, tilt and shift are both adjustable in large format by adjustments *to the camera*.
So, basically, with 35mm, much of what would be in the camera in large format is *moved to the lens*, which of course makes the lens bigger. | Take a look at these two Schneider lenses that both have 90mm focal length:
The first has coverage for "35mm" format, the second coverage for large format. I am not sure, but I think the main reason for the difference in size is the fact that the large format lens is a "simpler" design, i.e. fewer elements/groups. The reason a large format lens can use a simpler design is the distance between the lens board and the film plane - the lens need not project light at extreme angles out its rear element, whereas a 35mm-format lens must do so, and so requires a more complex design. Also, the fact that large format is so much bigger than 35mm format might have something to do with it; because 35mm format is smaller, any distortion/imperfection is "magnified" to a much greater degree, so more elements are incorporated to correct for any distortion/optical aberration. |
77,515 | In general I have found that as the focal length of 35mm (or APS-C) lenses increases, the physical length of the lens increases as well. However, my large format lens is much thinner than other 35mm lenses of equivalent focal length. Here is a picture:
[](https://i.stack.imgur.com/oNMHx.jpg)
The large format lens is a Wollensak Raptar 135mm f4.7, and it not more than 5 cm long. The lens next to it (albeit slightly unfair as it is a zoom) is a Sun telephoto zoom, 85mm-210mm f3.8. In general all large format lenses seem to be rather diminutive in length. Why is this? | 2016/05/18 | [
"https://photo.stackexchange.com/questions/77515",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/36933/"
] | The focal length is the distance from the (theoretical) center of the lens to the image plane. On the large format camera, there's a lot more *camera* between the lens and the film.
The lenses are also often relatively simple — there's no need for a focusing mechanism in the lens itself, for example.
@osullic gives the example of the [Schneider PC TS Makro-Symmar 90mm f/4.5](http://www.bhphotovideo.com/c/product/818360-REG/Schneider_06_1064382_PC_TS_Super_Angulon.html) for 35mm and [Schneider 90mm f/4.5 Apo Digitar N](http://www.bhphotovideo.com/c/product/400328-REG/Schneider_03_017780_90mm_f_4_5_Apo_Digitar.html) for large format. They appear to have similar optical design (six elements in four groups), and this is particularly interesting, because the former is a *tilt/shift* lens. Tilt lets you change the angle of the focal plane for depth-of-field effects; shift changes the appearance of parallel lines. As with focus, tilt and shift are both adjustable in large format by adjustments *to the camera*.
So, basically, with 35mm, much of what would be in the camera in large format is *moved to the lens*, which of course makes the lens bigger. | The word lens is from the Latin, shaped like a lentil seed. This is a disk that bulges out of both sides, we call this lens shape, convex – convex. A single transparent convex – convex lens will do the deed. We task the camera lens to gather image forming light rays from a 3 dimensional world (object at different distances) and project their image on a flat light sensitive surface. We task the enlarger lens to gather image forming rays from a flat object (negative / slide) and project that image on a flat light sensitive surface. The two tasks are similar but the differences are profound.
The lens maker’s desire is a lens that projects a faithful image. This has never been achieved. Every lens ever made fails to yield a faithful image because the lens is a wave guide that alters the path of light waves. Our camera and enlarger lenses are converging lenses. Light rays transverse the lens and their paths altered. The light rays emerge, tracing out a cone of light. Sorry to report that some of these redirected rays fail to hit their intended target. These errors are called aberrations from the Latin for deviation.
There are seven major lens aberrations. Five are independent of the color of the light, two are based on the color of image forming rays.
1. Spherical Aberration – Differences in focal length center of lens vs. edge of the lens.
2. Coma – Circular objects image with a dim tail like a comet,
3. Astigmatism - Horizontal rays vs, vertical rays have a different focal length.
4. Distortion – A square object images with a barrel or pincushion shape.
5. Curvature of field – The project image is not flat, best to project on a curved surface.
6. Chromatic Aberration – Longitudinal – The location of the image is a function of its color.
7. Chromatic Aberration – Transvers – Focal length of each color different.
The lens maker strives to mitigate these seven aberrations. He/she dealing is using different shape lens elements and a mix of different density glass. The camera lens tasked to image a curved world on a flat, and the enlarger lens tasked to work flat to flat pose different problems.
Some lens elements are cemented together, some are air-spaced. The air-space between the glass is also lens-like in its shape. The air-spaces act just like a glass lens element as their width becomes part of the lens formula. The focal length is the distance from rear nodal to the image when the lens is imaging an object at infinity. The back-focus is the distance lens to image plane. Many times, the camera lens must have a longer back-focus to accommodate mechanical considerations. The rear nodal is thus shifted back towards the camera body. It likely will fall in air behind the lens. Conversely, to make a telephoto less unwieldy, the barrel is artificially shortened by shifting the rear nodal forward. It can even fall in air ahead of the lens. These shifts in the rear nodal are valued art of the lens maker.
Miniature cameras have fixed distances from the flange of the lens mount to the focal plane. Often in the optical path are reflex mirrors and gadgets to measure light. The back-focus distance of a lens must be adjusted so that when the lens barrel is imaging an object at infinity, the apex of the cone of image forming light just kisses the surface of film or sensor. The large format cameras utilize bellows that allow positioning the lens near or far from the film plane. No need to shift the rear nodal, a simple three element of the Tessar generally exceeds what film need to be pictorially useful. |
77,515 | In general I have found that as the focal length of 35mm (or APS-C) lenses increases, the physical length of the lens increases as well. However, my large format lens is much thinner than other 35mm lenses of equivalent focal length. Here is a picture:
[](https://i.stack.imgur.com/oNMHx.jpg)
The large format lens is a Wollensak Raptar 135mm f4.7, and it not more than 5 cm long. The lens next to it (albeit slightly unfair as it is a zoom) is a Sun telephoto zoom, 85mm-210mm f3.8. In general all large format lenses seem to be rather diminutive in length. Why is this? | 2016/05/18 | [
"https://photo.stackexchange.com/questions/77515",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/36933/"
] | A few points to consider (mostly adding to mattdm's answer):
A manually focusing 135mm Nikkor 2.8 lens in F mount is about 91.5mm long, and looking at a drawing of the lens most of the optical elements are in the front. So a comparison with a zoom lens isn't really fair -- it is a much more complicated lens.
Strictly speaking, a telephoto lens is one designed to be shorter than its focal length, otherwise a 500mm lens on an SLR would be mostly a big empty tube with optical elements at the end. The telephoto design allows the lens to be shorter but requires more optical elements. In a view camera this type of construction isn't normally needed as the camera bellows can expand or contract to suit the needs of a wide range of focal lengths (and focusing distances).
See also:
<https://en.wikipedia.org/wiki/Telephoto_lens>
<http://www.mir.com.my/rb/photography/companies/nikon/nikkoresources/135mmnikkor/135mm28.htm> | The word lens is from the Latin, shaped like a lentil seed. This is a disk that bulges out of both sides, we call this lens shape, convex – convex. A single transparent convex – convex lens will do the deed. We task the camera lens to gather image forming light rays from a 3 dimensional world (object at different distances) and project their image on a flat light sensitive surface. We task the enlarger lens to gather image forming rays from a flat object (negative / slide) and project that image on a flat light sensitive surface. The two tasks are similar but the differences are profound.
The lens maker’s desire is a lens that projects a faithful image. This has never been achieved. Every lens ever made fails to yield a faithful image because the lens is a wave guide that alters the path of light waves. Our camera and enlarger lenses are converging lenses. Light rays transverse the lens and their paths altered. The light rays emerge, tracing out a cone of light. Sorry to report that some of these redirected rays fail to hit their intended target. These errors are called aberrations from the Latin for deviation.
There are seven major lens aberrations. Five are independent of the color of the light, two are based on the color of image forming rays.
1. Spherical Aberration – Differences in focal length center of lens vs. edge of the lens.
2. Coma – Circular objects image with a dim tail like a comet,
3. Astigmatism - Horizontal rays vs, vertical rays have a different focal length.
4. Distortion – A square object images with a barrel or pincushion shape.
5. Curvature of field – The project image is not flat, best to project on a curved surface.
6. Chromatic Aberration – Longitudinal – The location of the image is a function of its color.
7. Chromatic Aberration – Transvers – Focal length of each color different.
The lens maker strives to mitigate these seven aberrations. He/she dealing is using different shape lens elements and a mix of different density glass. The camera lens tasked to image a curved world on a flat, and the enlarger lens tasked to work flat to flat pose different problems.
Some lens elements are cemented together, some are air-spaced. The air-space between the glass is also lens-like in its shape. The air-spaces act just like a glass lens element as their width becomes part of the lens formula. The focal length is the distance from rear nodal to the image when the lens is imaging an object at infinity. The back-focus is the distance lens to image plane. Many times, the camera lens must have a longer back-focus to accommodate mechanical considerations. The rear nodal is thus shifted back towards the camera body. It likely will fall in air behind the lens. Conversely, to make a telephoto less unwieldy, the barrel is artificially shortened by shifting the rear nodal forward. It can even fall in air ahead of the lens. These shifts in the rear nodal are valued art of the lens maker.
Miniature cameras have fixed distances from the flange of the lens mount to the focal plane. Often in the optical path are reflex mirrors and gadgets to measure light. The back-focus distance of a lens must be adjusted so that when the lens barrel is imaging an object at infinity, the apex of the cone of image forming light just kisses the surface of film or sensor. The large format cameras utilize bellows that allow positioning the lens near or far from the film plane. No need to shift the rear nodal, a simple three element of the Tessar generally exceeds what film need to be pictorially useful. |
77,515 | In general I have found that as the focal length of 35mm (or APS-C) lenses increases, the physical length of the lens increases as well. However, my large format lens is much thinner than other 35mm lenses of equivalent focal length. Here is a picture:
[](https://i.stack.imgur.com/oNMHx.jpg)
The large format lens is a Wollensak Raptar 135mm f4.7, and it not more than 5 cm long. The lens next to it (albeit slightly unfair as it is a zoom) is a Sun telephoto zoom, 85mm-210mm f3.8. In general all large format lenses seem to be rather diminutive in length. Why is this? | 2016/05/18 | [
"https://photo.stackexchange.com/questions/77515",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/36933/"
] | Take a look at these two Schneider lenses that both have 90mm focal length:
The first has coverage for "35mm" format, the second coverage for large format. I am not sure, but I think the main reason for the difference in size is the fact that the large format lens is a "simpler" design, i.e. fewer elements/groups. The reason a large format lens can use a simpler design is the distance between the lens board and the film plane - the lens need not project light at extreme angles out its rear element, whereas a 35mm-format lens must do so, and so requires a more complex design. Also, the fact that large format is so much bigger than 35mm format might have something to do with it; because 35mm format is smaller, any distortion/imperfection is "magnified" to a much greater degree, so more elements are incorporated to correct for any distortion/optical aberration. | The word lens is from the Latin, shaped like a lentil seed. This is a disk that bulges out of both sides, we call this lens shape, convex – convex. A single transparent convex – convex lens will do the deed. We task the camera lens to gather image forming light rays from a 3 dimensional world (object at different distances) and project their image on a flat light sensitive surface. We task the enlarger lens to gather image forming rays from a flat object (negative / slide) and project that image on a flat light sensitive surface. The two tasks are similar but the differences are profound.
The lens maker’s desire is a lens that projects a faithful image. This has never been achieved. Every lens ever made fails to yield a faithful image because the lens is a wave guide that alters the path of light waves. Our camera and enlarger lenses are converging lenses. Light rays transverse the lens and their paths altered. The light rays emerge, tracing out a cone of light. Sorry to report that some of these redirected rays fail to hit their intended target. These errors are called aberrations from the Latin for deviation.
There are seven major lens aberrations. Five are independent of the color of the light, two are based on the color of image forming rays.
1. Spherical Aberration – Differences in focal length center of lens vs. edge of the lens.
2. Coma – Circular objects image with a dim tail like a comet,
3. Astigmatism - Horizontal rays vs, vertical rays have a different focal length.
4. Distortion – A square object images with a barrel or pincushion shape.
5. Curvature of field – The project image is not flat, best to project on a curved surface.
6. Chromatic Aberration – Longitudinal – The location of the image is a function of its color.
7. Chromatic Aberration – Transvers – Focal length of each color different.
The lens maker strives to mitigate these seven aberrations. He/she dealing is using different shape lens elements and a mix of different density glass. The camera lens tasked to image a curved world on a flat, and the enlarger lens tasked to work flat to flat pose different problems.
Some lens elements are cemented together, some are air-spaced. The air-space between the glass is also lens-like in its shape. The air-spaces act just like a glass lens element as their width becomes part of the lens formula. The focal length is the distance from rear nodal to the image when the lens is imaging an object at infinity. The back-focus is the distance lens to image plane. Many times, the camera lens must have a longer back-focus to accommodate mechanical considerations. The rear nodal is thus shifted back towards the camera body. It likely will fall in air behind the lens. Conversely, to make a telephoto less unwieldy, the barrel is artificially shortened by shifting the rear nodal forward. It can even fall in air ahead of the lens. These shifts in the rear nodal are valued art of the lens maker.
Miniature cameras have fixed distances from the flange of the lens mount to the focal plane. Often in the optical path are reflex mirrors and gadgets to measure light. The back-focus distance of a lens must be adjusted so that when the lens barrel is imaging an object at infinity, the apex of the cone of image forming light just kisses the surface of film or sensor. The large format cameras utilize bellows that allow positioning the lens near or far from the film plane. No need to shift the rear nodal, a simple three element of the Tessar generally exceeds what film need to be pictorially useful. |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.