How do I prevent smoke problems indoors?

Question: I live in a small apartment, and the kitchen is tucked away in a corner without any outside ventilation (windows or stovetop exhaust). Every once in a while I'll be cooking and something will start to smoke (a different problem, I know!) and the smoke detector will go off. How do I eliminate or reduce the amount of ambient smoke? I don't have access to external ventilation.
Comment: Very closely related to [How do I stop my fire alarm from going off when I cook?](http://cooking.stackexchange.com/q/10115) I'm leaving it alone because the current answer is dealing specifically with the smoke issue and not the alarm, but if too many answers focus on the alarm issue, it might have to be closed. You might want to remove the bit about the smoke detector so that it's not construed as a duplicate.
Comment: At least in the US, if you have no ventilation or exhaust in the kitchen, your home would not meet building codes.
Comment: Unfortunately, sanitation codes for where I live (Boston) don't have a section on kitchen ventilation, and the building itself has been grandfathered in.
Answer: As SAJ14SAJ said, the best solution is to simply not live in a place like that - it can be a bit dangerous.
But since you're there, about the only thing you can do is get a decent fan and use it to direct air out of the kitchen toward rooms with open windows. Depending on the layout (and the fans) you may need multiple fans, and might want one of them to be a box fan in the window helping push air out.
For things you think may be smoky, you might also consider cooking outside if possible, on a hot plate, a camping stove, or a small grill. (Or you could just not do them at all.)
Comment: And avoid stir frying, searing, and similar techniques.
Comment: It seems this is the only thing to do for an apartment like mine.


Does our planet's inorganic period negate the concept of creation through observation?

Question: How can our physical world (only) manifest itself to us through observation when we know that our planet experienced a long inorganic phase that predated organic evolution by millions of years?  In other words, There were not yet any sentient eyes to observe our young planets existence.  It seems credible to assume our planet is not an illusion because during it's formative period there was no one there to (observe) it into reality.
Comment: @MarshallO'Donovan - An electron can act as an "observer" in quantum mechanics. Except for quantum theories of woo, there's nothing about consciousness being required in **any** interpretations of QM.
Comment: I'd suggest it should be "nothing is interacted with until it's interacted with".  All an observation tells you is that you made the observation and it had some value(s).   Physics is not about existence or consciousness, just about using what we measure to try and construct useful models.  Existence is a philosophical thing, now't to do with physics, IMO.  Anyway, any thought process that implies the non-existence of pizza can't be good. :-)
Comment: @StephenG - The non-existence of some kinds of pizza might not be that bad. My wife loves anchovies on top of any kind of pizza while my sister loves ham pineapple pizza. This has led to nightmares where the only thing to eat is a ham pineapple anchovy pizza.
Comment: Unclear:  Are you referring to theories such as the "Copenhagen interpretation" of quantum mechanics, where basically something doesn't exist until it's observed?  (I only know enough about this to be thoroughly baffled by it.)
Comment: Thanks Hot Licks.  I have always assumed that "nothing exists until observed" is embraced by most quantum theories.
Comment: An illusion is something that you see but does not exist. That should not be confused with the paradoxical idea that something may not exist until you see it. There is no place in _any_ interpretation of QM for illusions. The best way to interpret QM is to stick with the facts.
Comment: There are some intriguing implications for "dark matter" when considered in the context of observation and quantum mechanics.
Answer: This question partially stems from a popular misunderstanding of what physicists mean by "observe" in the context of quantum mechanics.
I've addressed that misunderstanding here in a previous question.
When physicists say a wavefunction collapses when it is "observed", they really mean "interacted with", not necessarily "observed" in the sense of a person looking at something. In order to measure the position, velocity, or some over observable quantity of something (a.k.a., in the parlance of physicists, "observing"), for example, an atom, we essentially need to bounce something off it. In the case of our eyes, that something is a photon, but we've built other instruments that use other particles. However, there doesn't need to be a person or an instrument or anything "observing" our electron to cause this wavefunction collapse. In universe empty of everything except our electron, a photon interacting with this electron would also cause a wavefunction collapse under the Copenhagen interpretation. While the act of looking at an atom involves bouncing a photon off it and collecting that photon with one's eyes, and that act does cause the atom's wavefunction to collapse, the eyes are irrelevant to the wavefunction collapse - it's the photon bouncing off it that is relevant.
The theory of quantum mechanics does not have any rules involving sentience or consciousness or eyes - the idea of wavefunction collapse is completely independent of and unrelated to organic life.
Comment: Thanks for the comment Brionius.  I agree with your notion of interacting vs. observation, as the real cause of wave function collapse, but the collapse being "completely independent of and unrelated to organic life" sounds too definite and dogmatic in a science that may be far from it's natural conclusion.  Without the consciousness of an organic life form, who's to say that a photon (would ever) be bounced off an atom... and who would record the result.
Answer: I don't think observation is a way of creating things, for physics.
Maybe what you are referring to is the wave function collapse principle, where the observation of a physical quantity makes the system's wave function collapse in one of its states. But not observing it doesn't mean that all the other states don't exist. They exist with their own probability of becoming the collapsed state at the time of observation.
Personally, I don't put so much philosophy in this modern physics things anymore. It's not magic it's only: there are more things that can be, each of them with its probability.
I think as this: you have a particle moving at 2 km/h. You take it and put in a box where you cannot see it anymore. Open the box: the particle has (for example) 99% of chance to be in the state "still 2 km/h" and 1% "now I move at 3 km/h cause a photon excited me". It's kind of more natural than thinking that the particle is moving both at 2 km/h and 3 km/h contemporary (Schrödinger's cat-like) or thinking that the particle doesn't exist anymore until you re-open the box. It's more about probability.
Comment: Thanks Costantino.   I'm thinking more along the line of of Einsteins statement about the moon.  To paraphrase he said...I'd like to think that the moon is still there when I turn my back.


One Infopath Form that displays data from Two Lists

Question: I have two SharePoint Lists.  My primary list consists of Field Names with their definitions.  My secondary list consists of all the values and the value's definition for the field on my primary list with a look up column to the ID for the primary list.  My intention is that when the user clicks on the Field Name from the primary list, that I could populate the values associated with that field from my secondary list on one Infopath form.  I have yet to figure this out.  When I add the secondary source to the Infopath form, it brings back every value on the secondary list and not just the values associated with the ID on the first list.
Comment: Is it like a mapping in your second list. Example Field1-Value1,alue2; Field2-Value1, Value2. On InfoPath form, you need to get value1 and value 2 for field 1. Am I right?
Answer: Please make sure to apply the filter (rule) for the secondary list lookup ID.
It can be done by following steps (high level) :

Add rule for the property and select set field value
In the rule detail you have to select the field value (destination)
In the value field, you have to map the source and destination lookup field values to apply the filter like below :

<code>xdXDocument:GetDOM("DatasourceName")/dfs:myFields/dfs:dataFields/d:SharePointListItem_RW/d:Engagement_x0020_PMM/pc:Person/pc:AccountId[../../../d:PMOPMM/pc:Person/pc:AccountId = xdXDocument:get-DOM()/dfs:myFields/dfs:dataFields/my:SharePointListItem_RW/my:Portfolio_x0020_PMM_x0020__x0028/pc:Person/pc:AccountId]
</code>
Comment: Yes, map all the require fields


Link Receiving address with other addresses

Question: Assumed somebody knows one of my several addresses in my wallet for receiving bitcoins, can he link this address with the other addresses I got? Or does every address stand for its own?
Comment: Please take some time to read the `Technical background of version 1 Bitcoin addresses` entry on wiki: https://en.bitcoin.it/wiki/Technical_background_of_Bitcoin_addresses
Comment: I'm not sure what you're asking. Are you asking whether someone can tell that multiple addresses are owned by the same person?
Answer: Say you have two addresses, address A and address B. If someone sends coins to you at address A, and someone also sends coins to address B, then no one can link those addresses together. They are just separate transactions with separate transaction outputs, just like any two transactions that are sent to different people.
But now, if you have to send some coins and you need to spend both of the previous transaction outputs were generated by sending to address A and address B, then you will be associating those addresses together. This is not a proven association, two different people could come together and spend two of their outputs together in the same transaction, but this is not a very likely scenario. The more likely scenario is that the person who initiated that transaction (you) owns both address A and address B.
That said, just because someone watching the block chain can tell that the SAME person owns address A and address B, that doesn't mean that they know that YOU are the one who owns address A and address B. Read this stack exchange for more info: How anonymous are Bitcoin transactions?. If they know that you are the owner of address A, though, then they would be able to determine that you are (likely) also the owner of address B (but only if you have made a transaction before that spends from both of those addresses).
Comment: And if you would spend coins from Address A and Address B, the person whom you did the transaction with to obtain Address A (or B) probably also has your email address or some other information about you. So it is possible that they could link these seemingly disparate meta-data items to at least an email address.


What is the discussion tag for?

Question: Some people seem to have an opinion that a meta thread is not a suitable place for discussion as the comments of this thread show.
Hence my title question.
Comment: @ivanhoescott: What's the deal with the strong attitude? You're new here, don't you think you should hang out a while to figure out what the culture is like? Also read some of the FAQs? This all feels like an argument for argument's sake. __Discuss a little,  but not much; more is tolerable on meta.__ that's SO's intent.
Comment: The tag set is not exactly well-defined. Somebody had an idea once, and it got added to a tag. What it's for is essentially whatever anybody uses it for; there really are no systematic definitions of anything.
Comment: One of our moderators gave you a link to just such an article below. I tried to help you out by pointing you at additional resources along those lines, specifically the founders' rationales for all this. It's fascinating reading, and the sort of people who fit in well here would be eager to read it. The people who fit in well here would also be eager to find it themselves. In contrast, you keep pestering people for more and more help even when they ask you to stop. Repeatedly. Please make more of an effort to fit in. **We are not tour guides.**
Comment: @ivanhoescott: Oh...then I don't understand what your problem is. Is it with ELU or the entire SE system? I'd expect that since you are an old member of another SE site the culture must be different there. If not then you should have no complaint here (or you should complain on SO.meta. If so, then hey follow the different culture here now that you know what it is.
Comment: @JohnLawler Do you mean that anybody can add whatever tag to the meta threads?
Comment: I don't know. All I know is that there's no system there, and every idea or term that anybody uses seems to be included.
Comment: Meta is a good place for opinion polling, which is what the discussion tag indicates. But it's a poor place for **interactive** discussion (which Stack Exchange developers deliberately discourage throughout the network).
Comment: @BraddSzonye Could you explain why you think so?
Comment: It's a fundamental part of the site design. I recommend familiarizing yourself with it. It's documented in depth in Jeff Atwood's Coding Horror blog, probably also at Meta Stack Overflow.
Comment: @BraddSzonye Would you please tell me the link to the article?
Comment: Could you please use the site archive, or Google, to find the information yourself? Atwood has posted many articles about the site philosophy, and it would probably do you some good to research it yourself. I am not a tour guide, and I will not answer you again unless you demonstrate at least **some** effort to do your own research.
Comment: @BraddSzonye I can google about it, but I'm not sure if I'd be searching for the right article you are talking about.
I guess he wrote many articles in his blog.
Comment: Please make your best effort with the information you have now. If it doesn't help you, them come back and explain what you did learn and what you still don't understand. At SE we expect you to do that for **all** questions. While you're looking at Atwood's blog, also look up the rubber duck article. (And if you ask me another question before even making an attempt to learn this, I will assume that you are trolling and ignore you.)
Comment: @BraddSzonye His blog has many entries. I cannot read all of them. Could you tell me the title and the date of his blog article you are talking about?
Comment: You can use Google as well as I can. I told you what to look for. Start with the rubber duck.
Comment: @BraddSzonye You are the person, not me, who has the opinion that Stack Exchange developers deliberately discourage interactive discussion throughout the network.
I think you need to prove it if you would like us to agree with you on that.
Comment: @BraddSzonye [This article](http://meta.stackexchange.com/questions/124643/how-can-meta-be-made-more-conducive-to-discussions) does not discourage discussions in the meta site.
Comment: @Mitch I'm only new here. I'm rather an old member of an SE site.
Comment: Also, you may want to link your network profiles together.
Comment: This appears to be off-topic because it is not a question so much as an attempt to turn the site into a discussion forum (despite repeated requests to desist). OP does not even refer to questions, only to "threads".
Answer: Discussion is appropriate on meta, based on MSO precedent [1] [2], as well as FAQ guidance. It is true that the Stack Exchange platform is not well-suited for discussions, but chat is often not an appropriate place for site discussions, for several reasons in the aforelinked post.
As to the specific case: Your question has been closed as a duplicate of your earlier question, and I do not see good reason to reopen it. I think your previous question received good answers, and as it has not been closed, I do not think there is anything further to be done in this instance.
Comment: My point in the earlier post is that meta is still not a good place to **chat,** and that the OP really needs to do more of his own homework and ask fewer chatty questions. So I think this question is rather missing the point, but +1 anyway for a reasonable answer to it.
Answer: It seems to me the "difference of opinion" on the linked earlier question is about exactly what kind of "discussions" should be conducted on SO sites.
So far as I'm aware, most ELU users agree with me (and with those arguing against OP on the earlier post). We think the "discussion" tag on meta questions just means people are encouraged to post what they think in respect of the issue being raised. An example of that being the "answer" I'm currently posting right here and now.
I'm not expecting to engage in a protracted back-and-forth interchange of ideas through comments here. We have our main chat room for general-purpose discussions, and if anyone wants an interactive discussion focussing on a specific issue, they can always create a chatroom just for that.

Obviously there will always be a certain amount of comment -> response -> counter-response ->... Plus people often post multiple clarification, supporting evidence comments under their own actual question or answer, even when they should more properly edit the original post.
But in general we don't really want the main/meta Q&A sites to be used to "kick ideas around" interactively. If you don't already know exactly what you think, and you want to explore an issue interactively to help firm up your ideas, do that in a chat broom, then post whatever you eventually decide is your contribution to the "question" - so people can vote on whether they agree or not.
Comment: I think that for new users going to chat to discuss their English query could be intimidating, that is my subjective view. For me it feels like I'm butting in on a private conversation between established friends. I realize I am in the minority (or am I?) feeling like this, and what's more the chat layout/design is confusing for people (like myself) who have never used chat before. Private messages would be so much nicer *sigh*...
Comment: @ivanhoescott: "meta **threads**" is your terminology, not mine. Strictly speaking I should probably have just kept extending my answer to address these questions you keep asking. I personally rarely use the chat facilities here, and I'd rather not post something in an answer when I don't really *know* it. It's possible future visitors might be enlightened by reading these comments, but I'm sure TPTB would rather see the relevant information in the actual answer text. Since two people have downvoted my answer (and only one *upvoted*), I assume they're fighting something of a losing battle.
Comment: For what it's worth, I agree with you 100%, FF.
Comment: @ivanhoescott: It might well matter in this specific context, since "threads" (often explicitly identified as "**discussion** threads") strongly implies the very activity I'm saying should not be encouraged on SO Q&A sites.
Comment: @FumblerFingers Can a chatroom discussion be visible for everybody?
Comment: @ivanhoescott: Normally, chat rooms are "public", meaning anyone (with at least 20 rep) can enter, view, and post. But to *create* a chat room you need 100 rep. Users with 1000+ can create "private" rooms where they specifically "invite" others in, but I've never done this (I've created several public rooms though).
Comment: @FumbleFingers Can anyone read *all* chat in any chat room? Can they read old chat?
Comment: @ivanhoescott: I believe so - unless it's one of those "private" rooms (which I've never created or used, so I don't really know about). I assume you can follow [this link](http://chat.stackexchange.com/rooms/8795/hangman-room) if you fancy a game of "Hangman" (assuming someone else also wants to play, but obviously *someone* must start each game). You can also go to the [ELU General Chat room](http://chat.stackexchange.com/rooms/95/english-language-usage), and even though you don't currently have the rep to create your own room, I'm sure most people there could and would do it for you.
Comment: @FumbleFingers If the chat rooms are suitable for discussions, then what are the meta threads for?
Comment: @FumbleFingers [*"meta threads" is your terminology, not mine.*] Does it matter if it is my terminology or yours?
Answer: Meta sites do permit some discussion. However, even here, the developers discourage extended discussion in comments. Please note the bold warning above the comment box in the image below. Also see this MSO post.
Comment: @ivan **It did happen. That's how I got the screenshot.** And it should answer your questions above: Even on meta, **extended discussions are strongly discouraged.**
Comment: See the picture above, which shows an extended discussion in comments **on meta,** followed by an **automated warning from the developers** not to have extended discussions in comments. I should not have to explain this!
Comment: How many comments does it need to show that message?
Comment: That shows when two people post several comments in a short span of time. I've added a link to an MSO post from when the feature was new. It does not give hard numbers but otherwise explains it well. (The exact numbers shouldn't matter anyway. Follow the spirit, not the letter.)
Comment: Let us worry about it when it happens.
Comment: Could you give us a supporting evidence of this claim?
Comment: I don't think it is necessarily an extended discussion in comments on meta. However, the time span does matter. [That shows when two people post several comments in a short span of time.]
Comment: @ivanhoescott Is there some reason you do not believe regular users when they try to tell you about do's and don'ts? Is there some reason you still do not believe us even when there are pictures and FAQs and dev blogs backing it all up? (And is there some reason you keep quoting comments like they are email messages, even when you are only replying to one person? Even though you've been politely asked to stop?)

What is the discussion tag for?


Reference request for Hecke operators for principal congruence subgroup of modular group

Question: I am looking for references that discuss Hecke operators $T_n$ acting on modular forms
for the principal congruence subgroup $\Gamma(N)$ of the modular group $SL(2,Z)$ and am happy to restrict to the case that $(n,N)=1$. Most textbooks (Diamond and Shurman, Koblitz etc.) that discuss Hecke operators for congruence subgroups specialize to $\Gamma_0(N)$ or
$\Gamma_1(N)$ which contain $T: \tau \rightarrow \tau+1$, but I am specifically interested in the action of Hecke operators on modular forms which are invariant under $T^N$ but not under $T$ and are thus forms for $\Gamma(N)$ but not for $\Gamma_0(N)$ or $\Gamma_1(N)$. It seems reasonably clear how to obtain the answer using the double coset formulation of Hecke operators, but I have not found a reference which writes this out explicitly in terms of the relation between the coefficients of the Fourier expansion of the form at the cusp at infinity and the coefficients of its
image under $T_n$.
Comment: Miyake also works out the case $\Gamma_0(N)$, so I do not know. Have you looked at Shimura, introduction to the theory of automorphic form? It may contain what you want, but I don't have it here and can't check.
Comment: There's some information/references, as well as applications (with the trace formula) in the recent paper of Kaplan and Petrow "Elliptic curves over a finite field and the trace formula", https://arxiv.org/abs/1510.03980
Comment: Thanks. I did find something useful in Chapter 3 of Shimura.
Answer: The reason why Hecke theory for $\Gamma(N)$ doesn't get much treatment in the literature is because you can easily reduce it to the $\Gamma_1(N)$ case. More precisely, you can conjugate $\Gamma(N)$ by $\begin{pmatrix} N & 0 \\ 0 & 1\end{pmatrix}$ to get a group intermediate between $\Gamma_0(N^2)$ and $\Gamma_1(N^2)$.
This has come up before (in the context of explicit calcuations): see this question.
Answer: The Hecke operators $T(n)$ and the dual Hecke operators $T'(n)$ acting as correspondences on the modular curve $Y(N)$ are defined by Kato in $p$-adic Hodge theory and values of zeta functions of modular forms, section 2.9 (in Kato's notation $Y(N)=Y(N,N)$). The action of $T(p)$ on Fourier expansions is given in section 4.9, there he also describes the relation between his definition and other definitions in the litterature.
Actually, when you conjugate the double coset $\Gamma(N) \begin{pmatrix} n & 0 \\ 0 & 1 \end{pmatrix} \Gamma(N)$ in $\mathrm{GL}_2(\mathbf{Q})$ by the matrix $\begin{pmatrix} N & 0 \\ 0 & 1 \end{pmatrix}$, you get the double coset $\Gamma \begin{pmatrix} n & 0 \\ 0 & 1 \end{pmatrix} \Gamma$, where $\Gamma$ is this subgroup intermediate between $\Gamma_1(N^2)$ and $\Gamma_0(N^2)$. So it should be a simple exercise to check that Kato's definition agrees with David's answer.
Comment: In section 4.9 of Kato he does give the action of $T(p)$ on Fourier coefficients, but in the case $p|n$ for the coefficient $b_n$ he has an assumption about the action of $\begin{pmatrix} 1/p & 0 \\ 0 & p \end{pmatrix}^*$ on the modular function $f$. If $p^2=1 ~mod~N$ then I believe the assumption is trivially satisfied, but if this is not the case I don't see that the assumption is true in general. In this case is it true that the Hecke operator still exists but does not have a simple expression in terms of coefficients of the $q$ expansion?
Comment: @Jeff Harvey The assumption $(\begin{smallmatrix} 1/p & 0 \\ 0 & p \end{smallmatrix})^* f = \varepsilon(p) f$ is trivially satisfied when $p=1 \pmod{N}$ but not otherwise (this matrix is a diamond operator). You're right that in general there is no simple expression for Hecke operators in terms of $q$-expansions.


How to write a sick character?

Question: So, in my story, a main character gets sick with a virus. (Not a real one). I alternate POV's, and she is one of my favorite to write. I'm pretty sure her mindset would change slightly. But how? Please help!
Answer: If I correctly read your question, its more about the voice and pov.
You can research symptoms and bring it out in forgetfulness, repetition, misidentification etc
A knock on the door, it was a salesman. What does he want to sell me? It was the third one this week.
"Mom, are you okay?", asked the salesman
Answer: Put yourself at her place !
You can make her first observe some symptoms, without paying a real attention, it has to be small details, you don't even have to make it like she is noticing, like she sees something in her eye but she thinks it's because she did'nt sleep enough, or she feels weak that afternoon, or her cat acts strangely in her presence  etc.
But slowly bigger symptoms will appear, ans she will begin to suspect something !
Also, are you writing a realistic story or a SF story ?
Comment: cant scifi be realistic for health? ;)

How to write a sick character?


How I am I supposed to "Properly" follow through to the next string while playing the electric bass guitar?

Question: So, I understand that when playing (plucking the string in particular) that when you pluck a particular string, you are supposed to follow through, and let your finger hit the previous, or last, string. The problem is that when I do this, when my plucking finger follows through to the previous string, it makes excess noise. It sounds like a thump. Also, when it comes to doing fast plucking motions, I find it hard to follow through to the previous string. Am I doing something wrong. Please Help. Thank You.
Comment: Can that sound be heard from the speaker? If not, why do you care? It's an _electric_ bass
Comment: Yes, it can be heard from the speaker. Well, at least I believe that it CAN be heard from the speaker, itself. I guess that I'm not 100% sure, though Thanks for your answer.
Comment: "Bass Guitar For Dummies" ?  :-) .  I'll go with the answer from droog, i.e. practice until you get gentle enough.
Answer: If your action is very low, or your pickups very high, you might be touching the pickup with the next string when you land on it. That would account for the loud noise you're experiencing. So the instrument might need some adjustment.
Otherwise the technique is correct as you describe it. When playing faster, you don't necessarily bounce against the next string as much as when going slower; but you still kind of graze it (and need to mute with the left hand). This helps your fingers maintain the correct position by touch.


Would a comet break up during a close pass of the Earth

Question: Would a short-period comet, with a 2-mile nucleus, be able to come within 200,000 miles of Earth without breaking up?
Comment: James K, Rob Jefferies, and Ken Draco. Your answers are all very helpful, perhaps you will help with the rest of my problem. I need for the comet to pass by, causing minor damage, perhaps such as can come from a meteor shower. I need for this comet to return in 30 years and seriously damage planet Earth.
Comment: Then you need a collision with Earth (make the comet smaller). Read about the Tunguska event including accounts of witnesses. Apparently it was a small comet or part of a comet (Don't trust Wiki too much. Anybody edits anybody and posts anything nowadays). If we say roughly Tunguska was 50 meters in size, then if you have a comet 10 times as large, consider explosion and damage to be roughly 10$^3$=1000 times
Comment: as devastating. So, raise to the cube to get a rough idea without misrepresenting things too much. A larger comet will also burst/disintegrate but may leave a crater. Use something like this http://purdue.edu/impactearth to get a rough idea or http://impact.ese.ic.ac.uk/ImpactEffects/ However, all this is still EXTREMELY rough approximations. Set density to 0.5 Hope it all helps and will suffice for the book.
Answer: It wouldn't break up.
As my Granddad used to say "Close is only good in horseshoes". If the comet doesn't impact the Earth will be able to pass by unchanged. 200000 miles is a long way, about the distance of the moon from Earth. Asteroids have come this close before (eg 2011 XC2).
Comets can be broken up by close encounters with the sun, but the sun is rather hotter than the Earth [citation needed]. 200000 miles is also well outside the Roche limit for the Earth-comet system, and at the speed that comets travel relative to the Earth, tidal effects won't have enough time to act.
So the comet will pass the Earth quite happily. It is a rather small comet, and even the comet's coma won't interact with the Earth. After closest approach it is possible that the Earth could pass through the comet's tail, which would cause a meteor storm.
Even at 100000 miles, there is not much effect on satellites nearly all of which orbit at 22000 miles or less (22000 is geostationary orbit) It is plausible that they could be damaged by meteoroids.
The dust that comes of comets is all quite small. If you are looking for a "near miss that still causes damage" try this. The comet makes a close pass of Jupiter that causes it to split into two parts. The larger part misses Earth by 100000 miles but the smaller part (a 300m chunk that wasn't noticed until too late because story) hits Merchtem 10km outside Brussels
Comment: Would the same apply if the comet came within 100,000 miles of Earth? Might either one damage satellites? And might the meteor storm include fragments large enough to constitute minor, but not catastrophic damage from falling space debris?
Answer: No, that isn't close enough. The Roche Limit for break up of a rigid body, caused by tidal forces is given by
$$d = 1.26 R_C \left(\frac{M_E}{M_C}\right)^{1/3},$$
where $M_E$ is the mass of the Earth, $M_C$ and $R_C$ are the mass and radius of the comet, and $d$ is how close the comet can come to the Earth before tidal forces disrupt it.
If you have a comet with a 1.6 km radius and assume it has a density of 0.6 g/cc, then $M_C \simeq 10^{13}$ kg.
Putting this into the Roche Limit formula, we get $d =  17,000$ km. So the comet would have to get within 10,000 km of the surface of the Earth before it broke up.
Comment: While the formula is a good one, the calculations and assumptions make it look like we arrived at some exact figure (17,000). This is an extreme approximation with a lot more variables in fact. Such a clear-cut answer, in my opinion, is very misleading for the folks who are gonna read or rely on it. Hence, I'm sorry, but I'm voting it down.
Comment: The calculation is as precise as the clearly stated assumptions.


How experiments differentiate between valence quarks and sea quarks

Question: The picture that baryon consist of three quarks and mesons consist of a quark,anti-quark pair is inaccurate.However this simple picture is enough to explain many properties of the hadrons as mentioned in the answer here What is the experimental evidence that the nucleons are made up of three quarks?
A more accurate picture is that baryons are made up of three valence quarks plus a sea of quarks,anti-quarks and gluons.It is the sea of quark,anti quark pairs that determine their masses.What is the experimental evidence of the presence of sea quarks ?experimentally how can we prove the existence of sea quarks as opposed to valence quarks?
Answer: First of all physics is not about proofs. It is about mathematical models that are fitted to data, and the same models make predictions for new experiments. If the predictions come true, the model is validated.
To start with there was the parton model, before quarks as such were accepted as a standard model. When deep inelastic scattering data on protons showed that there was a hard core

In particle physics, the parton model is a model of hadrons, such as protons and neutrons, proposed by Richard Feynman. It is useful for interpreting the cascades of radiation (a parton shower) produced from QCD processes and interactions in high-energy particle collisions.

.....

The parton model was proposed by Richard Feynman in 1969, used originally for analysis of high-energy collisions. It was applied to electron/proton deep inelastic scattering by Bjorken and Paschos. Later, with the experimental observation of Bjorken scaling, the validation of the quark model, and the confirmation of asymptotic freedom in quantum chromodynamics, partons were matched to quarks and gluons. The parton model remains a justifiable approximation at high energies, and others have extended the theory over the years.
It was recognized   that partons describe the same objects now more commonly referred to as quarks and gluons.

This happened when the quark model with the basic SU(3)xSU(2)xU(1) symmetries became the standard model for particle physics.
Parton distribution functions  can be extracted from the data by using elaborate QCD  calculation models.  This laborious method is explained in this link.

So this type of plot is the experimental evidence, because it is a fit to data, and in addition it is predictive of other data.
Answer: Well in a baryon there are three quarks that are not virtual. Then there is the quark and the gluon field which constantly creates quarks and gluons and those are destroyed and created again. For a pion(neutral) there is not even these valence quarks. There is only the quark field. The charged pions are a little different and they can not have virtual quarks only. They have vitual quarks and real quarks(to make sure the charge is all perfect).
Comment: By non virtual quarks I do not mean they are not part of the quark field. Of course even the valence quarks are part of the quark field. There are only fields and no particles. Particles are excitations of fields.


What are tax implications of sending USD 22000 to my brother's NRE account in India?

Question: I want to send USD 22000 to my brother's NRE account in India. I pay taxes in the US. Are there any other tax implications for this transaction in US? Also, this money is not a gift. My brother will repay the amount (principal only)
Answer: Your brother is also an NRI and hence eligible to hold an NRE account?  What country is he residing in?
Unless you have proper documentation to establish that this is a loan, it is considered to be a gift by the IRS, and you are liable for gift tax on $8K (= $22K - $14K annual per-recipient exemption) in the US when you send your brother the money. On the Form 709 that you must file in the US (it is not attached to your Form 1040 but is instead sent to a different IRS office), you can choose to reduce your lifetime combined gift and estate tax exemption (currently $5.4M but wait till the Trump Tax Act becomes law when it will likely be even higher) and not have to pay any gift tax at all. (Or you can pay the gift tax and be done with it.) If you are worried about reducing your exemption below $5.4M, congratulations on your achievement of (or aspiration to) a very large net worth so early in life, and talk to your lawyers about alternative strategies.  As far as your brother is concerned, he does not have to pay any taxes (income or gift) in India when he receives the money or when he returns the money since gifts of money between close relatives are not taxable in India.
The loan must charge a minimum interest rate as specified by US law, and if you choose to forego this interest (since you say that your brother will be returning only the principal to you), then you are making a gift of the annual interest due (but not collected) to your brother. On a $22K loan, the annual interest will be less that $14K and so this annual gift will not be liable for gift tax. In the best of all worlds, your brother will send you the interest and you will return it so that there is a paper trail showing interest paid, and a small gift given (cf. the answers and comments on this question.) Finally, since you bring up 2017-2018 in your comment, be aware that the US tax year runs from January 1 to December 31 for most ordinary taxpayers, and so at least as far as the US is concerned, the lending and the repayment are likely to be in different tax years even though they might be in the same tax year in Indian law where the tax year covers parts of two consecutive calendar years.
Comment: Thanks a lot for the response. I am a H1 B visa holder since Oct 1,2017.  My brother works for an international shipping company as  a marine engineer. So, he is on the ship for 8 months and the remaining 4 months, he lives in India. He will repay the amount in the same financial year (2017-18). What I inferred from your answer is this: 1. We do not execute any loan documentation and pay taxes on $8K OR 2.Treat it as a loan,execute documents, take the minimum interest from my brother and then give it back to him as a gift. Is that what you mean? Just making sure.Thanks.


Does Photoshop scale better than Illustrator?

Question: Is it advisable to scale a raster image in Photoshop to the final size before embedding it in Illustrator or does Illustrator use the same bicubic algorithm as Photoshop when (up)scaling pixel images?
Answer: Photoshop interpolates pixels. This means when you scale in Photoshop, Photoshop uses mathematical algorithms to determine either the best pixels to remove (if reducing) or the best color pixels to add (if enlarging). When you scale a raster image in Photoshop you alter the pixels of the image itself.
Illustrator does not interpolate pixels. Illustrator simply alters the outer dimensions of a raster image to fit the desired size. This will either condense pixels (if reducing) or stretch pixels (if enlarging). Illustrator does not alter raster images at the pixel level.
Both methods can be both useful and detrimental depending upon the project. However, it is exceptionally unwise to enlarge raster images beyond 100% within Illustrator if you are concerned about image quality. You should always use Photoshop to enlarge a raster image, never Illustrator.
Answer: Having worked in the print industry for close to 20 years, I usually will import the image, unscaled, into AI, get it to the size I want, then, using the data from the links panel, I open the image in PS, rotate/scale it to the specs from AI, save it with a different name, then replace the link in AI. Hope this helps!
Comment: Illustrator supports live links correct? i.e. edits to the linked file will propagate, similar to inDesign. (Photoshop supports linked files, but the link is really a snapshot and changes to the file outside of photoshop's awareness will not update). I am fairly certain that Illustrator sdoes this with illustrator files, I am unsure about raster links however.
Comment: @horatio Illustrator will update changes to linked files.. or rather.. will ask the user if they want to update when a linked file has changed outside of Illustrator. And you're correct - Photoshop won't do this.


Creatures with variable power and toughness

Question: If I summon a creature like Boneyard Wurm whose power and toughness depends on the number of creatures in my graveyard, and afterwards another creature of mine dies, do the Boneyard Wurm's power and toughness increase? What about the opposite: if a creature card is removed from my graveyard, do its power and toughness decrease?
Comment: I picked a card that has power and toughness depending on number of creature cards in your graveyard as you described - pretty sure it's what you had in mind, but let us know if you had something different in mind.
Comment: To get really technical P/T of a creature is only checked as a creature's state.  This means that if a spell says remove all creatures from your graveyard and put back 4 of them.  While The Wurm will be 0/0 for a period during spell resolution it does not die because the p/t will be 4/4 when it is checked.  See 704.3 in CR
Answer: Yes, that creature's power and toughness will change as the number of creatures in your graveyard changes. It doesn't say something weird like "when it enters the battlefield, count the creatures in your graveyard, etc etc". It just says:

Boneyard Wurm's power and toughness are each equal to the number of creature cards in your graveyard.

So that's what it does. However many creature cards are in your graveyard right at this moment, that's its power and toughness. Add one, they go up by one, remove one, they go down by one.
Comment: Also worth noting is that */* creatures have that power and toughness in any zone, so if, for example, an effect allows you to search your library for a creature card with power >= 4, and you have >= 4 creatures in your graveyard, you could select Boneyard Wurm.


Which version of Hibernate is suited for Spring 4.3.2?

Question: I use Spring framework 4.3.2.RELEASE
I saw on a tutorial site that both Spring and Hibernate must match their versions in order to integrate Hibernate with Spring.
So what is the appropriate version of Hibernate for Spring 4.3.2.RELEASE ?
Answer: Read the link https://spring.io/blog/2016/06/10/spring-framework-4-3-goes-ga
Seems to me  Hibernate 5.2 is the way to go.
Answer: I belive that correct answer is Hibernate 4.* try with Hibernate Core 4.3.6.Final.
Comment: You can also use Hibernate 3.x (although deprecated) or 5.x (as mentioned in other answers) with Spring 4.x.
Answer: From the Spring point of view with Spring 4.3.2 you can use any Hibernate version up to the latest 5.2. For example i have used Spring with Hibernate 4.3.7 and Hibernate 5.0.7 so there does not have to be an exact match of versions.


Saying the Ribono Shel Olom after counting the Omer

Question: If one is no longer counting the Omer with a Brocho can one still recite the Ribono Shel Olom prayer?
Comment: Why might you think one can or cannot do so or that they are related at all? Please [edit] your question to clarify.
Comment: Short answer: yes.
Answer: I assume that you are referring to the paragraph that appears in most siddurim following the actual counting. This is an additional / optional paragraph that is not part of the essential mitzvah of counting.
Additionally, part of the paragraph references one of the Kabbalistic "sefirah" terms related to that day. The point is, that each day, there is a mitzvah to count, with or without a bracha. If you count without a bracha, you still fulfilled the mitzvah of counting that day. The saying of the vracha is contingent on the concept of having "temimot" meaning "full", "Complete" or "unblemished", and since you missed a day, you've lost the completeness, and cannot say the bracha. But, obviously, you still can and MUST count, daily.
For either of these two reasons, you can recite the Ribbono shel Olam following the counting.
Comment: Isn't the bracha not said because there is a doubt if one is obligated or not?
Comment: @DoubleAA Sorry, I don't understand. "Obligated or not .. " for what? To say the bracha if you forgot, to say bracha at all (even if you never forgot) or to continue counting if you forgot a day?
Comment: The latter. [15]
Comment: @DoubleAA - Hmmm. I have to look this up. That factor would change my answer.
Answer: The Chok Yakov ( O. Ch.489) writes not to say  the kabalistic tefilos  after counting the Omer.
Comment: He says that in general, unrelated to whether or not you are counting with a Bracha, so this doesn't really address the question.


Can we use Active Directory for Access Control?

Question: We have a quite elaborate set up for Active Directory, and would like to use this to provision & deprovision access to the Control Panel. Would this be possible in Craft core or in a plugin? Are there hooks to use alternative access methods?
Answer: No, this is not available in the core. There is a plugin which deals with OAuth which may help you.
You can view a list of hooks which Craft provides out of the box here.
I imagine you will need to develop your own plugin for this. There is some guidance in the Craft documentation on creating hooks/events in a custom plugin if that's the route you'd prefer go down.
Comment: See here for some more information on how you'd approach AD/LDAP in a plugin: http://craftcms.stackexchange.com/a/486/57


Is there any reason why some people's names in Tana"ch include their grandfather (or beyond)?

Question: In most cases, when peole's names are mentioned in Tana"ch only their and their father's names are mentioned (e.g. - Yehoshu'a bin Nun). In some cases, the grandfather is also mentioned (e.g. - Betzalel ben Uri ben Chur) and in only 1 case I can thnk of (are there others?) the great-grandfather is also mentioned (Korach ben Yitzhar ben K'hat ben Levi). Is there a specific reason why only certain people's names go beyond the father?
Answer: As you mentioned yourself, there are "specific reason[s] why only certain people's names go beyond the father". However, I don't think there is a hard and fast rule for each example, rather each one is brought for a specific reason.
With regards to one of your examples:
Korach's genealogy was listed in the beginning of Numbers 16:1 only up to Levi, since Yaakov (one generation farther) specifically requested that his name not be associated with the quarrel he caused. (Rashi)
I also seem to remember a reason for listing Betzalel's genealogy (possibly due to Chur being killed for trying to prevent the Golden Calf), but I don't remember the source offhand.
Comment: I don't see how Rashi's piece connects to the question here.


Can you please help me translate this title and signature?

Question:
I am trying to translate this signature from a watercolor painting I bought many years ago at a thrift store.  I've tried google translate along with searching Asian artist seals, but no luck.
Comment: 水鄉䥫堃(author)寫(painted)。The seal: 金+夷 or 銕。(This Q will be closed soon.)
Comment: I re-opened this question because @Dalice705 has shown that prior research and effort was made; as per our requirements: **unless prior research effort is clearly indicated**.
Answer: The translation of 水鄉 is "water town". In China, "水鄉" usually refers to "江南水鄉", which are the villages/ town in the Yangtze River Delta (e.g. Suzhou Zhouzhuang Water Town). "鐵" is iron.
According to Kangxi Dictionary, "堃" means compliance, obedience, female and is the variant of "坤". "坤" is one of the Bagua("八卦" or the eight trigrams) and it represents "地" (earth/ground/floor).  "寫" is writing or painting.


Can I wash my dog on my lawn without damaging the grass?

Question: Is it bad to give my dog a bath on our lawn?  Will the soap residue end up killing our grass? I never had a second thought about this but I've recently come across some natural weed killer suggestions that use soap as an herbicide.
Comment: Never heard of soap as an herbicide though it is sometimes used as a wetting agent along with other ingredients to help it stick to the plants. The soap shouldn't hurt the grass. Some people even spray dilute baby shampoo on their lawns because they think it helps with compaction. I think they're wrong but it doesn't kill the grass.
Comment: I'm not exactly sure why soap is used in the natural weed killer recipes, but I believe the soap is used as a suspension to get the herbicide on the plant or to "suffocate" the plant by coating the leaves with it.
Answer: It's all about ratios - the ratio of soap to water, and the type of soap. I shouldn't imagine you're using anything too noxious to wash your dog, and I assume you will be rinsing him off in the same area, which will dilute any soapy solution on the lawn. Just use the hose or something to wash the lawn off a bit more after you're done - so long as you're not doing it very frequently, it should be okay.
Answer: Too much water will drown the lawn and squeeze the life out of it.  I put a Slip N' Slide out on my back lawn for a party and, of course, the lawn turned brown under where it had been all day, but also it browned where just the runoff was nearby.  I decided it was because the kids were running all over that area and "squeezed the life" out of the grass.  That said, I just drove my pickup up the inclined part of my lawn with about 800 lbs of dirt and stone in it. Tomorrow it will be fully loaded with soil, weighing at least 1500 lbs; and Thursday comes the mulch.  But I am careful to never drive on the lawn when it is wet. I also use 4 wheel drive to clime the incline so the wheels don't spin.


How to define this function on arrows?

Question: I want to solve the following exercise:

Let $U: \mathcal{C}\rightarrow\mathcal{D}$ be a functor, $F:\operatorname{Obj}(\mathcal{D})\rightarrow \operatorname{Obj}(\mathcal{C})$ be a function. Assume that there is a $\operatorname{Obj}(\mathcal{D})$ indexed family $\{\alpha_X\}$ of $\mathcal{D}$-maps $\alpha_X:X\rightarrow U(F(X))$. Now suppose that for all $f:X\rightarrow U(Y)$ in $\mathcal{D}$ there exists a unique $\tilde{f}:F(X)\rightarrow Y$ in $\mathcal{C}$ such that $U(\tilde{f})\circ\alpha_X=f$. Define $F$ on maps to make a functor such that $\{\alpha_X\}$ is a natural transformation.

I had a look on this exercise and thought about the following. Let $g:X\rightarrow Y$ be an arrow in $\mathcal{D}$ then define $F(g)=\tilde{g}$. Is this a good choice and is this choice good enough to end the exercise?
Can someone help me by hints or solution?
Thank you.
Answer: For $g:D_1\to D_2$ in $\mathcal D$, extend it to $f:=\alpha_{D_2}\circ g:D_1\to UF(D_2)$. By hypothesis, for this arrow there exists a unique $\tilde f:F(D_1)\to F(D_2)$. So, let $Fg:=(\alpha_{D_2}\circ g)^{\tilde{}}$.

How to define this function on arrows?


What term describes the state of being either enabled or disabled?

Question: I need to refer to the attribute of a button that describes whether it is enabled or disabled. "Enablement state" sounds awkward and clunky.
Comment: What is wrong with just *state*? The state of the button is "enabled". The state of the button is "disabled". Perfectly fine. Only not an option if you reserve or already use *state* for some other attribute of the button, but I struggle to think which attribute that could be.
Comment: If you put your question into sentence format, then it'll be easier to answer, e.g., "# 5 is the _Enable/Disable_ button" or "Button 5 _enables/disables_ the XYZ function".
Comment: @Cody: again, the word for the "state" of color is *Color*. The word for the "state" of text is *Text*, or *Label*. And so on. "The state of the button is blue"? Nah. The *color* of the button is blue. "The state of the button is 'On/off'"? Come on. That makes you sound like a non-native speaker. And the word for the superset of all these attributes is not *state*, either, but *attributes*, which is why you keep using that word yourself in the first place. I'm afraid you're overthinking this, trying to take problems into account that do not really exist.
Comment: @RegDwigнt _"What is wrong with just state?"_ There can be a lot of different states: the button can be either in a pressed or a released state, it can also be in either a greyed out state: won't react to when you click on it, or it can be in a functioning state: will react and be pressed when you click on it. Here are just 2 examples of just calling one of them state. What are you going to call the other one then? The thing in programming is that you simply won't be able to refer to both of those things by just using the "state" word.
Comment: The development environment simply won't allow us to have 2 variables with the same "state" name, we have to differentiate.
Comment: I started to type up an answer, then I read these comments and discovered they contain the entirety of my intended answer, but far more succinctly. +1s for everyone. Except you, Cody. Enablement? Clunky only scratches the surface.
Comment: Is on/off to simplistic?
Comment: @Kristina Lopez: Yes. It's also not the standard jargon. Plus, "on/off" can be misleading because the power switch is an "on/off" toggle.
Comment: @RegDwighт I considered "state", but that seems to represent a superset of attributes of the button, including it's color, text, etc.
Answer: I take it you mean a word for whether or not a button is "grayed out", not for whether it has turned something "on" or "off". If "state" or "mode" are too general or in use, then I suggest availability, which could have values "enabled" and "disabled".
Answer: It's not whether the button is enabled vs disabled, only that it is disabled or not. Hence the parameter that controls this behavior, in various software and html/css, is simply "disabled", which has a value true or false. It's also more handy in programming logic to treat a bi-state parameter in this way. Instead of all such parameters having all sorts of values you have to keep track of and compare as strings in conditionals. When you name and use a parameter as representing the truth or falsehood of only one of the states, then you can always test more quickly for true or false. Less typos and most programming languages provide shortcut conditionals, e.g. If(button.disabled) instead of if(button.state==disabled).
Comment: That's valid, but my issue with this is that it's ambiguous whether the status is enabled:true or disabled:false. I generally prefer to pick the positive term, but I was wondering if there were a way to avoid making that choice altogether.
Comment: @Cody, then use If(button.isDisabled)
Comment: @Cody Yes. Technically the "is" prefix is syntatic sugar. Same idea is there that we were taught many moons ago as good software engineering practise.
Comment: As an additional example from life, one would ask if the light switch is on, instead of asking about the state of the switch in relation to artificial lighting level in the room. Speaking and coding this way makes things simpler, without having an artificial level of semantics on top. In coding, you can easily loop through a collection of say buttons and check which are enabled with a isEnabled flag true. Otherwise you'd potentially have to check each funkily named enablement state property value individually. Come to think of it, the latter confusion is how most microsoft stuff is set up.
Answer: I think "Enablement state" is as close as you can get.
Cody is looking for a noun to describe the variable that will contain either "enabled" or "disabled", not an adjective that describes its current state. ie. If presence means "the state of being present", then _____ means "the state of being enabled"
As others have suggested, the variable would be named "isEnabled" in code, but this is the English Language & Usage Stack Exchange and isEnabled isn't English. I don't think isEnabled has a direct counterpart in English, and "device is enabled" isn't a noun.
I'm writing a list in plain-english of different settings that can be set for a device. The term that our team chose seems to be "state of operation", but that is ambiguous because without context, it's not clear if the contents of that variable tells us if it's currently operating or whether it's meant to be operating. It is also vague as to what part of the device is enabled.
With "enablement state", it's clearer that it's describing the variable rather than the contents, and as a bonus it's possible to be more specific as to what is being enabled, such as "water enablement state" or "lantern enablement state". That said awkward and clunky are definitely the first two words that come to mind for this phrase.
EDIT: Apprently "enabledness" is an option
Answer: I think the answer lies in what are you disabling and enabling.  The graphic of a toggle button is a verb in and of itself.  If it has a label such as "water", you press the button in and as long as the button is in its inward state (or locked down), it's understood that water will continue to flow.  As soon as you press the button again to return it to its outward state (or up), it's understood that the water will stop flowing.  We already know the button is enabling or disabling something.  What is it enabling and disabling?
Comment: Oh, you're not talking about the label of the button, but the enabled state.
My typical approach here is to have the state be a boolean value, and name the attribute the positive form of the state.  I.e., if Button.enabled=true, then we know the button is enabled. If Button.enabled=false, then we know the button is disabled.

Don't use disabled=true, though since double negatives can be confusing to others.
Answer: One of my favorite synonyms to the enabled/disabled pair is the on/off pair. When looking up synonyms for "off" on thesaurus.com, one of its antonyms I found was "present" in the context of being absent/present.
These proved to be helpful, because there are words for the state of being present and the state of being absent (according to dictionary.com). They are "presence" and "absence" respectively. Which one you choose to use depends on what state of being you prefer as a default.
"what state of being you prefer as a default" basically means which state of being is more important to you and stands out?
Example 1:
In schools, absence is considered to significantly take away from your education, so addressing absence is more important to school teachers and admins than your actual presence.
Example 2:
In a program, a new feature's presence is considered more important than its absence. You don't ever want to state that a feature is or could be absent in a program. That's just (simply put) bad marketing.
Example 3:
Another example in programming that is the opposite of the previous example is bugs and their presence in a program. It is more important that bugs are absent than they are present.


Why does my car sound like it has no catalytic converter when it hasn't been removed?

Question: Well, my car suddenly started making a sound like if the catalytic converter was removed, which it has not. The noise started when my husband connected the a/c compressor directly to the battery because it didn't turn on automatically when we turned on the a/c on the dash. So, yes the compressor is on all the time until it gets fixed and we already know it is because of a bad transducer.  So, with that said, is that why my car sounds like it has no catalytic converter?
Comment: Hard wiring the ac compressor is a bad idea, more than likely it is the compressor making the noise.
Comment: Welcome to Motor Vehicle Maintenance & Repair! What you are describing is very subjective. Really, a car doesn't sound too much different without a cat than with a cat, if all else in the exhaust system stays the same. Are you just saying it's "louder" than before? Maybe give us a little more information? Are there any dash lights? Also, plugging the A/C compressor clutch directly into the battery is a BAD choice. Great way to destroy the compressor.
Comment: As you have not mentioned your car, it could be the compressor itself making the noise, in most dated cars you can hear from inside the cabin when the compressor turns on and off.
Answer: I would start by getting down low/underneath it, on a cold start and looking under the car to see if there's a visible exhaust leak.
Have someone rev the engine a bit, and see if you can see any puffs of smoke.
Shining a flashlight on the likely areas can sometimes help, as well.
If the sound isn't as extreme, it might have something to do with an air silencer in the air intake "System". There's a possibility it was jostled out of place during his working on the vehicle.
I hope this helps.


Can dogs see things that humans can't?

Question: The other day I was sitting in my lounge alone and my dog got up and started growling and barking at the air. She wouldn't stop whining and wouldn't take her eyes of this spot for ages.
Can dogs see things that humans can't?
Comment: Like what? ghosts? Your dog probably heard or smelled something
Comment: Using logic to explain it away. Are unseen things logical? Thank God for good dogs.
Answer: Yes and no. That is, in some areas they see better, and in some areas they see worse.
Both human eyes and dog eyes have rod and cone cells making up the retina. Rods are better at vision in low light conditions and detecting motion. Cones are better at visual acuity and can actually detect color.
In comparison to humans, dogs have more rod cells, which means their visual acuity in well-lit conditions is actually poorer, and of course their color vision is much worse. Their vision is usually estimated to be 20/75 versus 20/20 which is considered the norm for humans, although certain types of dogs, such as sight hounds, may have vision acuity closer to that of a human's.
On the flip side, they will see better under low light conditions. In addition to their rod cells, unlike the human eye, a dog's eye has a layer of tissue behind the retina called the tapetum lucidum. It's a reflective layer that reflects light back onto the retina, to help increase the light that hits the retina. This improves their night vision even more, and it's what gives dogs that distinctive greenish yellowish eyeshine in flash photos.
Furthermore, a dog's eyes are set a little more to the sides of the face than a human's, giving them a narrower field of good binocular vision but a little wider field of vision overall. They can compensate for the lesser binocular vision by turning their head to get the thing they're trying to look at more centered in their vision.
But also in comparison to humans, dogs are able to detect higher frequencies of flickering light, whereas to a human a light flickering so quickly will appear steady. In other words, dogs have a higher flicker fusion threshold. This means that it takes more frames per second in video media for the image to appear to be smoothly moving to dogs than to a human. Television, which is optimized for the human eye, may very well look like a stream of flickering still images to them. This is especially true of older media, where framerates tended to be lower.
To summarize, a dog's vision:

is worse at visual acuity
is worse at color vision
has a narrower field of binocular vision
has a wider field of vision
is better in low-light conditions
is better at detecting movement
has a higher flicker fusion threshold
Answer: I see that this was asked a long time ago but it's still worth answering.
Dogs are predators and are very sensitive to movement.  They can sometimes miss seeing a stationary animal (such as a rabbit) when it is obvious to us. However the second it moves, they will spot it.
Dogs with good eyesight can see tiny flies such as fruit flies in the air, even in conditions where it is hard for us - again this is because the flies are constantly moving.
I regularly observe this with my own dog. She will chase and snap apparently at mid-air.  It is only occasionally that I will manage to see what she sees but I certainly do sometimes if I look where she is looking.
So yes. Dogs who have good eyesight, can see things that humans can't. There's nothing weird about it. They are just more sensitive to movement.  Also it is quite possible they hear things that we don't and your dog was looking in the direction of a sound.
Comment: just to add some additiona information to this answer https://www.psychologytoday.com/us/blog/canine-corner/201604/can-dogs-see-in-ultraviolet

Can dogs see things that humans can't?


When using PGP/GPG, is it safe to use the same public/private key pair on multiple computers for the same person?

Question: It seems somewhat unsafe to move the private portion of one's key around to multiple machines...but it also seems odd to have multiple identities floating around.
Answer: The private key is owned by a human, not by a machine -- indeed, the normal case is that you (as a user) have one key pair, and use the private key on all machines where you need to.
Having a key pair per machine would not work well; this would mean that when people send you an encrypted email, they will use one of your public keys, and you will be able to read the email only on the specific machine which contains the corresponding private key. This is hardly convenient.
We can say that as long as you want to read the same emails on several machines, then these machines must contain private keys which are functionally equivalent. Making these private keys distinct from each other is then a useless complication; just accept that you really want to have your private keys in several machines. Of course, the security of your key against theft will then be bounded by the security level of the weakest of these machines. You have to balance the convenience of being able to use many machines to read your emails, with the increased risks.
To move the private key safely (independently of the wisdom, or lack thereof, of having the same private key in many machines), you should protect your "keyring" with symmetric encryption and a passphrase of high entropy. Encryption of the keyring with a passphrase is the normal setting, so your job is "just" to use a strong passphrase. Since the format allows for reasonably strong password hashing (with iterations and salts), you can get away with a passphrase of entropy 60 bits or so. With such a strong passphrase, the keyring is "inherently" strong, and the travelling key is no longer an issue.
Comment: By "keyring", are you referring to the private key itself, say, in a GPG implementation, in which the private key is secured by a sufficiently high-entropy passphrase, which is required to be entered every time a message encrypted with one's public key is decrypted? Or are you referring more to something akin to OS X's KeyChain? Or both?
Comment: Your question is confused.  The keyring isn't the private key; the keyring contains the private key.
In GPG:
Your public keys are stored in ~/.gnupg/pubring.gpg

Your secret keys are stored in ~/.gnupg/secring.gpg

Since the question is not about OS X's KeyChain (actually it's "Keychain"), let's not go there. (And it has very partially overlapping functionality.)
Answer: Each additional computer that has access to your keys increases your risk of being compromised.  However, one way that you can greatly reduce the risk is by using a cryptographic smart card.  Cryptographic smart cards store the private keys and do the encryption / decryption on the card.  This means that the computer never sees the private keys.
Assuming you are using a smart card, if someone compromises the computer, they still can't access your private key.  As long as it is plugged in, they can make use of it, but they can't steel your private key.  Once you unplug the smart card, they have no more ability to decrypt or sign content.
Note: this only applies to cryptographic smart cards.  Some simple smart cards don't do on-board processing; they offer little security.


Who owns the logo of a company after the company declares bankruptcy?

Question: Who owns the logo of a company after the company declares bankruptcy? For example who owns the logo for toys R'us after they declare bankrupt?
Answer: Whoever buys it.
When a company declares bankruptcy then its assets are owned by its creditors, as compensation for the standing debts.
Since usually there are multiple creditors, what happens is that its assets are sold/auctioned, as money is easier to divide between the different creditors1.
A logo or a trademark is an asset like any other and can be sold separately.
If nobody did come forward for the logo, then one of the creditors could accept it as part of its repayment.

1 If a company is in bankruptcy it means that its assets cannot cover all of its debts, so creditors are usually paid only a part of their debts.
Comment: The usual way of looking at it is that the assets are held by the receiver/liquidator on trust for the creditors.  He can sell the logo to a creditor in exchange for writing off some debt, or to anybody else for cash which will be used to pay debts; but a creditor can't decide "I'll take the logo at this value against my debt".


I have just watched my 22 month old dive head first over the gate on her bedroom 5 times after putting her to back to bed 50-60 times

Question: I'm not concerned about the fact she physically hurts herself by jumping the gate, she is as tough as they come. She screams so loud every time I walk down the stairs and is up the gate within  seconds. I just worry about long term mental issues. My elder daughter has never been a problem. I put them to bed at the same time, seperate rooms and allow my 5 year old the light on as the younger one can't see her room. Either my 5 year old, my wife or i will read her a quiet story and we make it clear that the elder one has gone to bed. But the second we move away from the bed, she is crying for a 'cuggle' and as we leave the room, the screaming becomes deafening. We have been hard with her on this issue but, it seems to re-occur every couple of nights. Am I doing the right thing?
Comment: I do not think there ever is a "right thing" to do.  So I would like you to clear up the question a bit. Stating the problem and be open to the experiences of others.
Answer: First: all people are different and have different needs.  Do not use the needs of one person to determine the needs of another.
What is going on in your child's mind and emotions is unique to her.  Some may tell you that you are being manipulated, but I would say that child needs a lot of touch, and close connections with her parents especially before going off on her own into the dark scary night - for what ever reason. Give it to her.
Our children slept with us from the time we brought them home from the hospital until they wanted a bed of their own.  Each had their own needs and time of departure to that independence. It was not always easy, as one of them took up to an hour of crawling around between us before he could fall asleep.
At 22 months, I feel that it is important that a child KNOWS that they are loved and their individual needs will be met.  At a older age those apparent needs may turn into wants and you can tackle that at that age.
Comment: Hi, and welcome to the site. :-)
Answer: There may be several alternatives to just locking her into her room, that may lead to your final goal of getting her to sleep alone.
Would it be very bad for the sleep of the older child to let your younger one sleep in the same room? I had a hard time moving my oldest son out of our bed to his own room, but it was relatively easy to move my middle child to the lower bunk under his big brother's bed. But my kids were older than 1 when they moved to their own rooms.
Could another option be putting a mattress down on the floor of your room or of your older child, and letting your younger child leave her bed to go to sleep there when she wants? If she feels she can go to you when she needs to, she might not be so upset when put in her own bed. For some time she might immediately go to the mattress, but eventually she would stay in her own bed longer and longer if you read her stories there and made a pleasant night routine. Good luck-- time is on your side!
Comment: Welcome to the site! Thanks for the thoughtful answer.
Answer: I will confess that I have never faced quite this issue, so take my opinion with a large bag of salt.
First, lose the gate. It's not accomplishing its purpose. You might get something for it from a garage sale.
Second, establish an evening routine designed to encourage sleep.

Get the kids to play strenuously for a continuous hour or so after
supper.
An hour before lights out, pop her in a warm bath.
Once she
settles down, the combination of physical exhaustion and body
temperature changes should encourage sleep (or that's the theory, until the plan meets up with an actual child).
Answer: Co-sleeping works wonders - probably a sleeping pad or some such on the floor at the foot of the bed. Every couple of months, try to establish her in her own room, or better yet, with her sibling.
I'm not saying this is your best long-term option, but it will) get everybody some good sleep. Some kids are not ready for that kind of separation. I don't know of any studies on excessive crying causing emotional damage, but it certainly makes sense.
Comment: Since I was the parent who could easily sleep anywhere, any time, it was my job to get my daughter down. I'd just bring a pillow with me, crash on the floor next to the crib with my hand in the crib, on her back. Since I'd also fall asleep, it was easy to not leave too early, before she was really out for good.


Drawing software with slight animation capabilities

Question: I am looking for a drawing software which has animation capabilities. That being said, it shouldn't be completely animation oriented. I only need it for the purpose of teaching physics, that is draw a moving pendulum etc. I saw a video of KhanAcademy using a software meeting my requirements, but unfortunately,  I couldn't tell which software it is. This is the video:https://m.youtube.com/watch?v=_4VC3IHbuW8
(at 9:27).
So in short, I need software recommendations meeting the above criteria or just the name of the software used in the video.
Answer: I would strongly suggest investing some time, (but absolutely no money), in looking into Python, Jupyter and the associated tools such as matplotlib.
One of the great thing is that with these tools rather than drawing what your experience tells you happens in physics systems and animating it you can simulate the physical system with an animation as the display and then your, or your students, can play with the parameters to see how they vary the behavior.
Another is that they are completely free, gratis & open source, and will run on most platforms from a RaspberryPi, up through OS-X & Windows, on through workstations to super computing clusters - so your students can run them at home.
In python this matplotlib example the following code produces an animation of a double pendulum, (source code from the matplotlib examples):
<code>"""
===========================
The double pendulum problem
===========================

This animation illustrates the double pendulum problem.
"""

# Double pendulum formula translated from the C code at
# http://www.physics.usyd.edu.au/~wheat/dpend_html/solve_dpend.c

from numpy import sin, cos
import numpy as np
import matplotlib.pyplot as plt
import scipy.integrate as integrate
import matplotlib.animation as animation

G = 9.8  # acceleration due to gravity, in m/s^2
L1 = 1.0  # length of pendulum 1 in m
L2 = 1.0  # length of pendulum 2 in m
M1 = 1.0  # mass of pendulum 1 in kg
M2 = 1.0  # mass of pendulum 2 in kg

def derivs(state, t):

    dydx = np.zeros_like(state)
    dydx[0] = state[1]

    del_ = state[2] - state[0]
    den1 = (M1 + M2)*L1 - M2*L1*cos(del_)*cos(del_)
    dydx[1] = (M2*L1*state[1]*state[1]*sin(del_)*cos(del_) +
               M2*G*sin(state[2])*cos(del_) +
               M2*L2*state[3]*state[3]*sin(del_) -
               (M1 + M2)*G*sin(state[0]))/den1

    dydx[2] = state[3]

    den2 = (L2/L1)*den1
    dydx[3] = (-M2*L2*state[3]*state[3]*sin(del_)*cos(del_) +
               (M1 + M2)*G*sin(state[0])*cos(del_) -
               (M1 + M2)*L1*state[1]*state[1]*sin(del_) -
               (M1 + M2)*G*sin(state[2]))/den2

    return dydx

# create a time array from 0..100 sampled at 0.05 second steps
dt = 0.05
t = np.arange(0.0, 20, dt)

# th1 and th2 are the initial angles (degrees)
# w10 and w20 are the initial angular velocities (degrees per second)
th1 = 120.0
w1 = 0.0
th2 = -10.0
w2 = 0.0

# initial state
state = np.radians([th1, w1, th2, w2])

# integrate your ODE using scipy.integrate.
y = integrate.odeint(derivs, state, t)

x1 = L1*sin(y[:, 0])
y1 = -L1*cos(y[:, 0])

x2 = L2*sin(y[:, 2]) + x1
y2 = -L2*cos(y[:, 2]) + y1

fig = plt.figure()
ax = fig.add_subplot(111, autoscale_on=False, xlim=(-2, 2), ylim=(-2, 2))
ax.grid()

line, = ax.plot([], [], 'o-', lw=2)
time_template = 'time = %.1fs'
time_text = ax.text(0.05, 0.9, '', transform=ax.transAxes)

def init():
    line.set_data([], [])
    time_text.set_text('')
    return line, time_text

def animate(i):
    thisx = [0, x1[i], x2[i]]
    thisy = [0, y1[i], y2[i]]

    line.set_data(thisx, thisy)
    time_text.set_text(time_template % (i*dt))
    return line, time_text

ani = animation.FuncAnimation(fig, animate, np.arange(1, len(y)),
                              interval=25, blit=True, init_func=init)
# Uncomment the next line to save to a movie file
# ani.save('double_pendulum.mp4', fps=15)
plt.show()
</code>
This results in, saved as gif with resolution and frame rate reduced for SO limits:

You may also find this gallery of notebooks interesting & useful and there are a huge number of other examples available online.
Comment: Personally I think vPython (http://vpython.org) is even better for this.
Comment: Thanks. This is helpful indeed, but I'm actually looking for something simpler as I am to suggest this software to someone less used to computers.


CLS to work with third-party Ring Flash?

Question: I was new to this CLS technology from Nikon and wanting to make full use of this technology. Unfortunately recently I just bought a Sunpak ring flash and it does not support CLS function. May I know is there any extension modules to be able to use my ring flash as part of the CLS so it can fire off from my main camera?
Comment: Is this a fashion type ringflash or one designed for macro photography? And do you intend to use it for portraits or macro?
Comment: @Matt this is a fashion type ringflash. I intend to use for portrait.
Answer: No, but both Metz and Sigma offer flashes which are compatible with the Nikon wireless flash system. They work differently — Sigma's acts as a controller, while Metz's works as one of the slaves, controlled by the on-camera flash.
I don't think you're going to have any options with the flash you have. While there are now some radio triggers (from PocketWizard and maybe others) that can transmit Nikon's proprietary TTL protocol, they require the flash itself to speak the protocol already. And even if that would work, you'd end up with a rather unwieldy bunch of connectors plugging it all together.
Comment: thanks may I know what is it called? I need it to use with my ring flash.
Comment: Sorry, I wasn't quite clear. These *are* third-party ring flashes that are compatible with the Nikon system. They won't help with your Sunpak flash.
Comment: pocket wizard is one option but I would really hope if i can make use of the CLS. :/ Getting pocket wizard defeat the rest of the purpose.
Comment: Pocket wizards only transmit CLS signals, you still need a CLS aware flash which yours most likely isn't I'm afraid. What aspect of CLS were you hoping to benefit from?
Comment: @matt I was hoping to use my ringflash which attached to my main camera D90 to trigger together with an external nikon flash. that simple. I was asking if there is any CLS modules that can help me on this to support my ringflash.
Answer: I've assumed that you're probably only talking about triggering as it's unlikely that there is anything out there that can do a CLS to generic TTL. You have several options depending on what other equipment you're shooting with.

Use a PC Sync cord to hotshoe adapter from a PC Sync socket on your camera or flash that is being triggered by CLS.
Use a cable such as the SC28 / SC29 to connect the sunpack to the hotshoe via cable. Ensure that you check that the voltage of the SunPack won't ruin your SLR first though. There are step down voltage converters that sit in your hotshoe for this.
Use either an optical slave or radio popper that attaches to your camera's hotshoe to trigger the ring flash. Often these allow a flash to be attached atop the trigger. Use a flash that supports being used as a CLS master (e.g. SB700, SB800, SB900) to trigger your other CLS flashes.
Search your favourite Auction or photographic supplier's website for cheap versions of these devices.
Answer: Not sure if it would work for your situation... but I have a Ray Flash attached to my SB-600 that I fire off via CLS. The infrared signals are usually bouncy enough that the sensor can pick it up, even behind the "down" part of the Ray Flash.
Comment: I know those ray flashes should work but what I have the problem now is the ringflash which I currently have does not work. I need a solution for this. thanks.
Answer: Will you be firing other flashes that do have CLS? If so, your best-bet answer is probably to get an "optical slave" trigger that you can plug in to the Sunpak.
There are a variety of options at a variety of prices... Here's B&H's selection of optical slaves to give you an idea. A quick search also turns up other sources and information... including options for about US$13. If you have a good ("pro") camera store in your area, they're sure to have at least a few of these on hand, for significantly less than a pair of PocketWizards.
There are some complications with this methodology, depending on your situation (read some articles from that search for full details), e.g. pre-flash triggering (some optical slaves claim to account for that), making sure the slave can "see" other flashes, etc. However, I'm guessing that for your situation, this could work quite well. I know I've had good luck with a little flash I have that has an optical slave built in, as long as I'm cognizant of positioning of its "eye" relative to my other strobes.
Also, there are other radio slave options than PocketWizard. In some circumstances, and depending on your demands, at least some of them can be quite adequate. (That said, I've gone to PocketWizard, myself. So, your results may vary.)


Configure Firefox to remember form changes when accidentally leaving a HTTPS page?

Question: On some webpages, changed form content gets lost when the user (accidentally) leaves and goes back to the page (before submitting the form).
Example scenario: Bob edits a wiki page in Firefox. He changes existing content of the textarea and adds many new paragraphs. While typing, he accidentally presses Alt+←. Whoops, now he is on the previous page. He clicks Firefox' "Next page" button to get back to the edit page. But, oh no, all his changes are gone.
As far as I tested, Firefox' default behaviour for forms on HTTP pages is fine: it keeps the changed content. But the same form on a HTTPS page "forgets" all unsaved changes. (assuming the webmaster didn't implement anything special)
Because it works for HTTP but doesn't work for HTTPS, it seems to be the responsibilty of the browser. I assume they deactivated it for security reasons. Is that correct?
Can this behaviour be disabled (in about:config)? Is it possible that Firefox remembers unsaved changes on HTTPS pages in the same way it does on HTTP pages?
I'm not talking about permanently saving the content with the help of a Firefox extension; it's not necessary to save form changes to be able to retrieve them anytime. I want to prevent content loss only for the situation when the user is navigating accidentally away and then going back immediately after (< 30 seconds).

Related
If you submitted the form and something went wrong, see:

Does Firefox cache submitted form content anywhere I can recover?
How do I recover a form in Firefox *without* installing a plugin? (including a nice way to save and search through the memory of Firefox)
How to recover form information for a webpage in Firefox

If you want to save all your form changes, see:

https://addons.mozilla.org/en-US/firefox/addon/lazarus-form-recovery/

If you want to prevent this problem for visitors of your website:

https://stackoverflow.com/q/14420624/1591669 (Onur YILDIRIM gave a nice overview of possible solutions)
Answer: Two Firefox extensions will accomplish what you desire.  One is called "Lazarus: Form Recovery" and the other is called "Textarea Cache".
Lazarus: Form Recovery is available here: https://addons.mozilla.org/firefox/addon/lazarus-form-recovery/
and Textarea Cache is available here: https://addons.mozilla.org/firefox/addon/textarea-cache/


How were 18-bit instructions encoded in paper tape?

Question: Early 18-bit computers like PDP-1 were based on 18-bit instruction sets, and used punched paper tape for storage etc. As far as I know paper tape was usually 8 holes, which works nicely with 16-bit etc. I haven't heard of 9-hole tape. How did they encode 18-bit instructions on tape?
Comment: Paper tape came in 7, 8, and 9-hole versions, and a few other odd variants.
Answer: The answer is invariably specific for a particular computer, and indeed may be specific depending on what is doing the reading (say, hardware bootstrap versus software loader, or what it's reading from (say, photoelectric reader versus teletype attachment).
On the PDP-1 reading 8-channel tape in binary mode from the photoelectric reader, an 18-bit word was assembled from 3 frames, taking 6 bits from each.
PDP-1 I/O manual, page 12
Assembly takes place in the I/O register, and it seems that this is accomplished by hardware obeying the "read papertape binary" instruction, rather than the reader software needing to read each frame, shift, and merge.

Read Punched Tape, Binary
For each In-Out Transfer instruction, three lines of punched tape are
read and assembled in the In-Out Register to form a full computer
word. For a line to be recognized in this mode, the eighth hole must
be punched; i.e., lines with no eighth hole will be skipped over. The
seventh hole is ignored. The pattern of holes in the binary tape is
arranged so as to be easily interpreted visually in terms of machine
instruction

1961 PDP-1 Handbook, page 22
The 1963 Handbook, page 23, has a concrete example:

The instruction sub 5137, for example, appears on tape and is
assembled by rpb as follows:

<code>Channel   8 7 6 5 4 : 3 2 1
Line 1    X   X     :   X
Line 2    X   X   X :     X
Line 3    X     X X : X X X

Reader Buffer 100 010 101 001 011 111
</code>
This answer, though about the PDP-1, shows the general nature of binary I/O (whether paper tape or otherwise) -- the medium supports units that are so-many bits wide, and there is some convention for representing machine words with multiple units.  Magnetic tape needs to do the same thing.
Comment: It's also interesting to note how the PDP-6 and the PDP-10 stored 36 bit words on binary paper tapes.  Same issue.  8 bits to a frame,  but 36 divides evenly by 6. https://www.inwap.com/pdp10/rim10b.html
Comment: That's RIM format, the possibility of which I alluded to in my first paragraph.  Was the same format used for storing non-bootstrap code on papertape?  Did anyone actually punch executable binaries on papertape?
Comment: wow thanks! ran across a fun video showing the pdp1 in action: https://www.youtube.com/watch?v=1EWQYAfuMYw
Comment: The first block of a binary tape was in RIM format and was readby the read-in-mode hardware.  The first block contained the RIM10B loader, no checksum.  The remainder of the the tape was read by the RIM10B loader.  This contained some stand alone program, such as a bootstrap that could read TOPS-10 from disk.  Does this count as an executable?  As far as storing .SAV files or .EXE files on paper tape, I'm unaware of anyone having done that at any PDP-10 site I visited. The PDP-6 was a whole different story.
Comment: I had in mind  "user" .SAV files on paper tape, not the OS itself, but I guess the second-stage bootstrap counts.
Comment: I have no personal recollection of users storing user level software on paper tape for the PDP-10.  I remember storing source code for the PDP-6 on paper tape, but that was bacause I was slow to migrate to DECtape.
Comment: @WalterMitty - you were [migrated to DECtape](https://en.wikipedia.org/wiki/The_M%C3%BCller-Fokker_Effect)?
Comment: I migrated to DECtape.  I wasn't migrated to DECtape.  In reality, in 1965, we called it microtape.
Answer: In addition to anotehr-dave's in depth answer maybe some (not PDP-1 specific) background information to show the environment:
8 hole punch tape was only a thing rather late on. Paper tape was commonly used in 5 to 8 hole versions (special types up to 24 and more), depending on purpose/equipment. 5 hole was 'small' Baudot type tapes, while 6 to 8 hole shared the same 25.4mm tape.
Thanks to this physically compatible medium, any 6..8 hole reader could any of these tapes and produce the lower 6 bits correctly. Read characters were always framed as a byte, so any 6 bit portion was always put into the lower 6 bit of whatever size that byte was, independent of paper tape 'width' or transmission byte size. That's why splitting any binary data it up into 6 bit chunks not only made a fine threesome of 18 bit words, but created as well a mostly device independent storage format. A machine could thus load a tape from any 6..8 bit reader as long as the serial interface as configured to the right word format.
At the time of the PDP-1 the most common teletypes were still operating on 6 bit.
Comment: The manuals are a bit vague.  It's a photoelectric reader, 300 cps or 400 cps depending on which document you read, and was [built into the console cabinet](https://www.computerhistory.org/pdp-1/9297cd3833e1e5ae2aa577011135a328/).
Comment: AFAIK, the PDP-1 console typewriter was made by Soroban, and used FIO-DEC codes, not ASCII.  This is form memory, no research.
Comment: Not to nit-pick, but I didn't see any easy way to attach a teletype to a standard PDP-1. There was one IBM-type typewriter connected to a dedicated slot; the connection was AFAIK more than just bit-serial (some time ago I wrote a question about machines with similar console Flexowriters).  The papertape reader was likewise a device with a dedicated controller and as far as I can tell, one per PDP-1.   I think teletypes came a little later than the PDP-1.
Comment: @another-dave True, you're right. It was meant more of a generic addition. Then again, what reader was used? I have to admit, the only part of a flexowriter I have is an auxiliary reader made for 6 hole tape. And yes again, at the time of the PDP-1, ASCII was still not invented and 6 bit TTY were still the most common.
Comment: @WalterMitty - you are correct about FIO-DEC.
Answer: This is explained here starting at page 21.  There are basically two modes in which a paper tape can be used:

Alphanumeric: 8 bits per tape line.
Binary: 3 tape lines of 6 effective bits each per 18 bit word.  Positions 7 and 8 are unpunched and punched respectively when punching. Lines with position 8 unpunched are skipped while reading.

Instructions were encoded using the binary mode.
Comment: It's also useful to note the role the sprocket holes played in establishing the location of "lines", including tape feed.  Tape feed could be useful in binary tapes to spearate "blocks" from each other visually.


Does Morphtronic Cameran defense effect negate trap and spell?

Question: I wanna know if the effect in defense of the monster "Morphtronic Cameran" negate only effect of other monster or also trap and spell ?
Comment: Posting a link to the card text or spoiler might help someone answer faster. :)
Answer: I may be answering this in a most "catch all" way, but I wanted to make sure how it works was clear to future readers who may misunderstand the card effect in this context.
The card text of Cameran reads:

Morphtronic" monsters on the field cannot be targeted by effects.

This is a continuous effect Card Rulings: Morphtronic Cameran that prevents all card effects from targeting Morphtronic monsters.
What this means is that it technically does not negate the card effects, it prevents Morphtronic monsters from being selected as targets from card effects that require choosing a card as a target.
Effects from cards like Dark Hole still apply and will destroy all the Morphtronic monsters because Dark Hole's effect does not select targets.
Effects that target will resolve something like so:
If a player chose to play Compulsory Evacuation Device (target one monster to return to the hand CED) when he/she controls one monster and the opponent has a Cameran in defense position and another Morphtronic monster, the player cannot select either of the opponent's monsters as targets, therefore he/she must return his/her own monster back to their hand.
Or in the instance that the player did not have that monster, they cannot activate the card because it does not have a legal target.
When it comes to resolving off of a chain: If a valid target was chosen (CED activated and Cameran was selected) and then it was no longer valid (i.e. a card was chained to CED's activation and the effect changed Cameran's position to defense before CED resolved), then in the resolution of CED nothing happens and CED goes to the graveyard because it is a normal trap card.
Answer: Yes, "card effect" in YGO refers to the effect text of any type of cards.