Can you draft a question before making it public?

Question: Can you draft a question before making it public for everyone on Stack Overflow? A lot of times, when the question gets laid out in that format it helps you think, and avoid pushing out something silly like a typo or code that isn't up to date with what you are currently working on.
Comment: What would be the purpose of this? You can already preview it below the editor.
Comment: You can have draft Q&A in the StackExchange mobile app (on iOS); not sure about android or the newer SO mobile app.  For the site, how about you just leave the tab open in the background where you started typing the Q?
Comment: Essentially you're asking here to make it so posting a question requires two clicks, right? Put a little extra moment of contemplation in between.
Answer: Yes, you can draft a post before you actually publish it.  According to this MSE answer about drafts, the Stack Overflow editor saves a single draft for questions and another one for answers at a profile level.  The text in the editor will be periodically saved (every 45 seconds).  Drafts last for up to 7 days, or until you manually post or discard them.  If you are using drafts to gather your thoughts and proofread your work, the 7 day limit shouldn't be an issue.
I don't know of any way to manually save the draft on the site itself, but you could always save the raw markdown elsewhere.  Then just copy-paste.


The required energy to accelerate a particle from one velocity to another

Question: Say I have a charged molecule running along a linear evacuated tube (so no wind resistance).  In the laboratory frame, we can measure that the particle is moving at some speed $v_1$.  Provided that kinetic energy scales as the square of the velocity, how much energy do we need to impart on the particle to accelerate it to some velocity $v_2$?  Why should this depend on $v_1$ and not strictly the difference $v_2 - v_1$?
Comment: kinetic energy is also proportional to mass. Try moving a ton.
Answer:
Why should this depend on v1 and not strictly the difference v2−v1?

If I understand your question correctly, you're not so much asking for a mathematical explanation as you are for a physical one?
Remember that KE is essentially the energy stored from work done by a force on the particle and that work is force through a distance.
When there is an initial velocity, the distance through which the force is applied is different than when there is no initial velocity.
For example, let's say that to uniformly accelerate from 0 to $\Delta v$ requires 1 second and a distance of 1 meter.
Now, imagine that there is an initial velocity $v_1$, in the direction of the applied force, and we have the same uniform acceleration for 1 second.  The change in velocity is the same but the distance through which the same force is applied is now larger by $v_1 \cdot 1 s$.
More work is done by the force since it is applied through a greater distance.  So, the change in KE must depend on the initial velocity, i.e., change in KE must be frame dependent.
Answer: The kinetic energy depends on $v_1$ because it's not a linear function of velocity. You can show the problem with a bit of algebra - nothing too scary!
Take your example of accelerating from $v_1$ to $v_2$, then the energy required is:
$$ \Delta E = \frac{1}{2}mv_2^2 - \frac{1}{2}mv_1^2 $$
To make the problem clearer rewrite this as:
$$ \Delta E = \frac{1}{2}m \left( v_2^2 - v_1^2 \right) $$
Can we write this equation as a function of just $\Delta v = v_2 - v_1 $? Well we can factor $(v_2^2 - v_1^2)$ to $(v_2 - v_1)(v_2 + v_1)$ or $\Delta v(v_2 + v_1)$, but we can't get rid of both $v_1$ and $v_2$ in the $(v_2 + v_1)$. The best we can do is write $\Delta E$ as a function of $v_2$ and $\Delta v$ or $v_1$ and $\Delta v$ e.g.
$$ \Delta E = \frac{1}{2}m \Delta v \left( \Delta v + 2v_1 \right) $$
or
$$ \Delta E = \frac{1}{2}m \Delta v \left( 2v_2 - \Delta v \right) $$
Answer: (This answer uses Special relativity, if that is not what your question is concerned then I apologize.)
If $v_1$ is close to $c$ ($v_1 \geq 0.3c$) then it does matter.
as the energy (Using Lorentz transformation) that is required to accelerate an object from $v_1$ to $v_2$ is:
$E = (\frac{1}{\sqrt{1-(\frac{v_2}{c})^2}}-\frac{1}{\sqrt{1-(\frac{v_1}{c})^2}})mc^2$
so, it takes more energy to accelerate an object from $0.3c$ to $0.3c+15 [\frac{m}{s}]$ (almost 1.8 billion joules assuming $m=1 [kg]$)
then from 0 to 15 $[\frac{m}{s}]$ (about 112 joules, again with $m=1 [kg]$)
Comment: While this isn't wrong you appear to have misunderstood the question.
Answer: Kinetic energy:
$E=\frac{m v^2}{2}$
Derivative of E towards v:
$\frac{dE}{dv}=mv$
Thus, the energy $dE$ required to accelerate a mass $m$ by a given additional velocity $dv$ is proportional to the mass $m$ and the velocity $v$.
Or in simpler terms: the higher the velocity the more energy it takes for the same amount of additional velocity.


Why did the Tesla truck have a centre mounted steering wheel? Are there any advantages to such a system?

Question: I asked this question on a trucking forum and the general consensus was that it would make backing up much harder. Does it eliminate any sort of blind spots?
Comment: Welcome to Motor Vehicle Maintenance & Repair!
Comment: Agricultural tractors have centre mounted steering wheels - and from lots of experience backing up is the same for each side...
Answer: According to the Tesla site about the truck, the reason for the center mount steering wheel is:

Enhanced Autopilot helps avoid collisions, a centered driver position provides maximum visibility and control, and a low center of gravity offers rollover protection.

If you look at the (what I take to be an artist's rendition) of the cab of the truck looking out, you can see there isn't much room for it to be anything but a center placed steering wheel:

The cab of the truck is quite narrow, which provides for better aerodynamics. These trucks (as far as I know) aren't made for long distance hauling, so most likely wouldn't have the availability of a sleeper or other things which conventional semi-trucks have need of.
With having visibility the same on both sides, it seems to me it would make it easier for backing the truck up. To me, the talk you are hearing elsewhere is just talk because truck drivers of conventional trucks are just "used to" how things are not equal in the side view mirrors. If they used this truck, they'd get used to the new paradigm very quickly whether they believe it or not. (Full Disclosure: Both my Dad and Father-in-Law were both truck drivers. I've done some driving myself.)
Comment: Okay. This truck seems to be narrower. Would this set-up also work in conventional trucks? ie, if I took a traditional truck and made it a center seater, would it offer the same benefits?
Comment: @kiiler - I would believe so, but you wouldn't have the amenities of the conventional. One of the issues which would occur with conventional trucks is the placement of the engine, which would entail having to work the steering around it. Having it on the side makes this a lot easier. In Tesla's design, there's no need because I believe the electric motors are direct drive at the wheel. The steering wheel can go anywhere across the width of the cab and still work well. Having it centrally located as shown just works for the narrow cab, but does give the other added bennies.
Comment: we could adopt a drive-by-wire system which could get around the steering wheel placement problem for conventional trucks. Would it be beneficial then?
Comment: @kiiler - I would bet the Tesla is already steer by wire, but yes you could possibly do that with a conventional truck. I'd also like to reiterate, having the steering wheel on the side of the vehicle is a lot more natural for an experienced driver than is having it in the center. It would take some getting used to by experienced drivers. This may seem like a trivial thing, but there would be a learning curve, one which may get bucked by the status quo.
Comment: One other consideration is that the Construction and Use regulations in the UK require a physical connection between the steering wheel and the steered wheels - a hydraulic only connection is not sufficient - so if the power assistance fails the truck can still be controlled : this may be the case in other countries as well.


Accessing DAPPs through HTTP

Question:
The blockchain is all about serverless and removing the third party. But I saw many DAPPs accessible through HTTP. Isn't this breaking the serverless concept? I read in a lot of places that IPFS aims to replace HTTP to make the web decentralized.
How can browsers like Google Chrome run DAPPs that using protocols such as Whisper?
What is the point of Mist Browser if I can access DAAPs through any other browsers(using HTTP)?
Comment: the whole concept of DAPP is a marketing thing to invite people write apps just like an app for Android. But it is not going to work, Ethereum is just a set of services. Everything will stay like it is, you are going to use Chrome or Android app, with the only difference that it is now going to interact with the blockchain. Forget about the DAPP word, replace it with API word and you will understand it quicker.
Comment: Yeah, I see, this explanation makes a lot easier to understand, but I was thinking if the new internet would be a  decentralized internet ( like in silicon valley series :D), HTTP will have no place at all and DAAPs should not depend on HTTP.
Comment: @Mayasara, there can't be internet on the blockchain. First, because there is no capacity to do it, current Ethereum rate is 15 TPS. Second; blockchains do not scale. Third: it is of very high cost, the consensus algorithm in (current) cryptocurrencies is very foolish, it wastes a lot of resources. Centralized servers are a lot cheaper solution. Blockchain is only good for money, but not for everything
Answer: Not exactly.
If you think of the blockchain as a solution to fault-tolerance and a 1:1 replacement for server-side logic and storage, blockchain will never make sense.
Blockchain solves for trust by presenting inarguable sets of proven facts. In practice, these are generally none of the facts you'll find in existing database designs and none of the logic you'll find in existing software over even familiar software patterns.
It's completely different. It's about proving the important facts.
High-availability is an important requirement simply because so much blockchain projects lean so heavily on the blockchain at the core of the design.
All manner of software stacks are possible on these foundations. These can includes servers talking to contracts, browsers talking to contracts, devices talking to contracts. It's fair to say that those aspects are not fault-tolerant or distributed when they (typically) rely on DNS and web servers to deliver assets.

If a CryptoKitty is born in a contract and there are no people to see how cute it is, is it still there? Yes.

In most cases, temporary localized failures are not a huge concern. In any case, removing the dreaded single-point-of-failure from the edges is arguably a separate concern.
This might be helpful: https://blog.b9lab.com/the-joy-of-minimalism-in-smart-contract-design-2303010c8b09
Hope it helps.
Comment: If your app can't tolerate a certain failure mode then there is always a way to remove a single point of failure. The price one is willing to pay for different kinds of fault-tolerance depends on the app. It depends on the case. For example, if you are trying to make fault-tolerant S.O.S. signals, then end-point censorship might be a serious concern. If you are primarily concerned with the integrity and availability of an asset registry, then possible temporary unavailability of cute jpeg images may not be a critical fault.
Comment: Thanks a lot, That was very helpful, But my only problem with DAAPs that are using HTTP protocols and relying on DNS that it may keep the problem of the ability to shut down the servers by the government or whatever, I don't think anyone can shut down the blockchain but its so easy to shut down a particular server. In my point of view, DAAPs should be only stand-alone applications (Desktop applications) or similar that connect and interact with the blockchain, what do you think?
Answer:
Google Chrome can't run DApps (short for Distributed Applications) on its own (atleast at the moment). Google Chrome needs an extension (for eg Metamask) to connect to underlying Ethereum blockchain.
It's extensions like Metamask that allow Chrome to run Dapps that use Whisper protocol.
Mist browser is just another option (apart from Chrome, etc) to be able to run Dapps. It is not mandatory to use Mist browser. One doesn't need to use an "extension" with Mist browser as it is built specifically for handling Dapps on blockchain.
Answer: The problem with 'traditional' HTTP technology and Dapps is that they do not like each other too much. Things are easy if we live in the traditional HTTP world or if we somehow managed to live purely in the Dapp world but unfortunately the Dapp world is not ready for total immersion.
Currently we still need technology which bridges these two worlds together - such as Metamask. Maybe somewhere in the future we only need decentralized solutions, but meanwhile we're stuck with what we have and HTTP is one of the best available means to get users to use Dapps (through Metamask, for example).
If we could connect to the Internet with decentralized means (IPFS maybe?) we could possibly also connect to Dapps without centralized intermediaries.
As already stated, regular browsers can't connect to the blockchain directly.
Answer:
The blockchain is all about serverless and removing the third party.
  But I saw many DAPPs accessible through HTTP. Isn't this breaking the
  serverless concept? I read in a lot of places that IPFS aims to
  replace HTTP to make the web decentralized.

In theory and in ways, yes, this breaks the serverless concept. Think about different network layers first, then evaluate the robustness and maturity of technologies associated when them. For example, decentralized apps can still run on TCP/IPC, but are decentralized at the application layer. In the future there may be a decentralized Ethereum-inspired cloud computer, but it will still utilize TCP/IP protocols. Imo IPFS has yet to become widely adopted, but can and still should happen.

How can browsers like Google Chrome run DAPPs that using protocols
  such as Whisper?

This is why people have created browsers like Brave, or are creating web-based platforms specifically for running Dapps, like Cosmos. Google Chrome needs a bridge as it stands because it isn't natively 'running' a Dapp.

What is the point of Mist Browser if I can access Dapps through any
  other browsers(using HTTP)?

Mist provides valuable visualization as to what is happening in the Dapp as well as wallets. It provides valuable monitoring and in many ways a testing environment for the Dapp. It is especially powerful to show this to non-technical people, plus it has a great UI. It isn't essential to the Dapp, but makes people's lives much easier, and ultimately promotes widespread adoption quicker.

Accessing DAPPs through HTTP


Cleaning relay contacts?

Question: I have an old transceiver. I have a problem where ocassionally the received signal will drop out when switching from transmit to receive. I've narrowed it down to the transmit/receive relay. When bench-testing the relay, it "clicks" over to receive, but shows a very high resistance. The contacts aren't visibly corroded or damaged. I have heard that the contacts may have to be cleaned - what's the best way to do this? Are there any cleaners that should be avoided?
Comment: Note, many [contact platings](https://www.te.com/usa-en/products/relays-contactors-switches/relays/intersection/relay-contact-life.html?tab=pgp-story) can include cadmium, indium, palladium, mercury, etc., even today and long into the foreseeable future.
Answer: Cleaning relay contacts is usually done mechanically. Use fine grade garnet paper (not generic sandpaper -- it can leave conductive dust behind), fold a strip in half and put it between the relay contacts, push the contacts together, and pull the paper out. Repeat until done.
Comment: Garnet paper *is* sandpaper, of a type.  However, it's one that's getting hard to find these days.  It's not friable like aluminum oxide (the much more common type of sandpaper) and so it cuts slower and wears out more quickly.  I imagine the name aluminum in aluminum oxide can lead one to believe it's conductive, but it's not really, it's a big ingredient in ceramics.  Aluminum has a resistivity of 2.82 × 10^-8 Ω·m, where aluminum oxide has a resistivity of 1 x 10^16 Ω·m.
Comment: @WPrecht-AB3RY - I clarified the difference. Google shows garnet paper available from Amazon and Woodworker.com.
Answer: To follow up on my comment to Pete's answer, the contacts probably have some oxidation (tarnish) on them, depending on the metal involved.
What you don't want to do is gouge up the contact surface with something that's too abrasive.  You just want to clean the surface and restore conductivity. Rag based bond paper works well (a crisp US dollar bill, for instance).  Insert the paper, gently hold the contacts together and swipe out the paper.  Should only take a few swipes.  If the contacts are plated over a base metal, any cleaning process will have a limited number of uses as the plating in these cases is very thin.

Cleaning relay contacts?


Suitable grade oil

Question: i am going to do a service on my work car(vw caddy 1.9 sdi 1999). My question is... What engine oil grade should i use 10w40 or 15 w40. In my country during the summer the temperature goes up to 30 grade celsius and during the winter the temperature goes to -15 or -20 grade celsius.  And what kind of oil should I use  full synthetic or semi synthetic. Also what do you think about these brand oil: Profi Car oil and Addinoil(zeller+gemellin) both  branda made in Germany. Thank you!
Comment: Are you sure the oil is made in Germany or just bottled?
Comment: I never heard of those brands in the UK, but apparently zeller+gemellin is a specialist chemicals conglomerate that has makes lubricating oils among other things. I have no idea if they are better or worse than mainstream oil brands in Europe (Shell, BP, etc)
Answer: According to Car.info, your Caddy can use 0W-30, 0W-40, 5W-30, or 5W-40 synthetic oil, or 10W-40, 10W-50, or 10W-60 in a semi-synthetic version.
You talk about the temperatures of either 30°C (86°F) or down to -15 to -20°C (-4°F). Neither of these are what I'd call extreme. Because of this, my recommendation to you would be to run the 5W-30 synthetic year round. You shouldn't have an issue with either the hot side or the cold side of where you live.
Firestone Complete Auto Care website states:

Typically, a 5W oil is recommended for winter use, but synthetic oils can be formulated to flow even more easily when cold. This way, they are able to pass tests that meet the 0W rating.

If you are choosing to run synthetic, you should not have any issues.
As far as a brand of oil goes, I'm not going to recommend one to you. The reason? We don't do that here. If you buy a major brand (for your country) full synthetic, you really shouldn't have an issue.

Suitable grade oil


What are the dominant elements that oxygen is bonded to on earth?

Question: Elements are found in different minerals and chemical compounds on earth. Oxygen is dominantly found in silicate minerals which, aside from silica, contain other elements. One way of looking at the chemical form of oxygen is to look at its bonds within the compounds. Is oxygen dominantly bonded to silicon? If so by how much and to what other elements does it most likely bond to?
Answer: This answer is basically an expanded version of my comments on this answer here.
If you consider the crust and the mantle, then the most abundant metals are magnesium, silicon, iron, nickel, calcium, aluminium (in that order). Other notable elements would be titanium, chromium, and just about all lithophile elements. The key is to understand that any single oxygen is not exclusively bonded to a single metal. It's bonded to several (different) metals at the same time.
There is an important point to be made here: because we call the minerals "silicates", it's often thought that most of the stuff in there is silicon (and oxygen). In fact, there is actually more magnesium in most of the Earth. Ideal Mg-olivine (forsterite) has double the amount of magnesium than silicon. Enstatite, an orthopyroxene, has the same amount of both elements. It is a common misconception to think of oxygen as being bonded to silicon while the other metals just "hop along". Silica, as SiO2 doesn't actually exist. Not in quartz and not in other silicate minerals. It's not like CO2 that exists as an independent molecule. It's just a convenient, charge-balanced way of representing oxidised silicon that has no existence if there are no oxygens around it. These oxygens are bonded to this silicon cation, but they are also bonded to everything else around it, be it magnesium or iron or whatever. An olivine is not a solid with molecules of SiO2 and MgO, it is an (almost) infinite solid with oxygens bonded to both Si4+ and Mg2+ in a three-dimensional structure. It's just a pile of cations (metals) and anions (oxygen), that happen to conform to combinations of "conventional" oxides because of charge balance.
Comment: I think you left out some words in your 1st sentence. Should it read "**If** **you** consider the crust and the mantle, then **the most abundant metals are:** ...?
Comment: @Fred yes of course
Comment: Did you forget hydrogen?...
Comment: @Floris Not at all. If you consider the crust and the mantle, there's hardly any hydrogen relative to the other elements. Water is abundant in the upper crust, but that's about it.
Answer: As mentioned, if you mean Earths crust, then it is bonded mostly to Si and Al (quartz, feldpspars, then other silicates, water, iron oxides etc.). If you mean a whole Earths body, then crust is just a minuscule part compared to mantle - the details are in the previous response. We think that mantle consists of olivine, spinel group etc. Actually recent research suggest much higher water content in the mantle then previously anticipated. But keep in mind that we have no direct evidence of what really is inside the mantle or core.
Answer: One of the most abundant chemicals in the outer surface of the Earth is water - where one oxygen atom bonds with two hydrogen.


How does the Tor Circuit Map works?

Question: I always wondered how Tor knows all the nodes in the connection path when the Tor Browser connects to a server. I though that the idea behind the onion routing was to hide nodes from each other, so that node A might know node B, but not node C? How does the Tor Browser than know all of the (three) nodes - from me to the exit node and the final server, like in the following screenshot?
Comment: The circuit map can be disabled if you want, there's an option for that in the Tor Browser Sandbox and I think it's the default in Whonix 13.
Answer: The relays do not know the full path through the network.
The client (your local instance of Tor) chooses the path. This means that the client (you) knows the full path, but any single relay in the circuit does not know the full path.
As to how how it displays it, it retrieves the information from the control port using the GETINFO request for circuit-status. Since this command returns additional information, like the SOCKS username and password used, and Tor Button sets the SOCKS username and password credentials use for any given site, it can tell which circuit is assocaited with each site and thus display the circuit information.

How does the Tor Circuit Map works?


How can you send calendar invites on iPhone 5 without using iCloud?

Question: How can you send out calendar invites in the iPhone 5 Calendar app? I have synced my phone calendar with one Gmail account and Outlook.
How can I create an entry on my phone and invite attendees without using iCloud?
Answer: If you invite someone from the Gmail calendar, it should send invites to persons via Google's Service.


Need suggestions on making Network File Share, Internal Wiki, Google Docs, and emails searchable from a single location for my organization

Question: I want my coworkers to be able to type a search into a single box and have it return information from all those sources.

Network File Share
Internal Wiki (based on MediaWiki)
Google Docs (we use google apps for your domain)
Emails sent to a particular email address (firstname.lastname@example.com)

Search results would be text, images, and also to just find files buried in the network file share.
The best idea i've come up with so far is to install a Desktop Search tool on each computer which is capable of indexing network drives (so far the best one i've found is Copernic Desktop Search).  Then, find a way to export the information (even if it's just the ascii text) from the other sources like the internal wiki, google docs, and email so information from these sources can be located as well.
The reason for this post is two fold:

Am I reinventing the wheel?  It
seems like this should be a common
thing by now.
I could use suggestions for utilities to help me get 2-4 above
into my file system.

Google Docs -> Files
I know syncplicity can do this which is overkill in some ways.  Let me know if you have other suggestions.
Internal Wiki -> Files
I bet there are a lot of ways to do this.  There are ways to spider sites and I bet there are ways to export using mediawiki plugins.  I wish that someone would come out with a desktop search tool which could index websites as well.  Any recommendations here?
Email to file
We need an easy way for people to be able to input information which is why I want to have an email address like email@example.com that people can CC on emails.  I'd like to have some type of mail client periodically fetch emails from this address and then save the email to a PDF, DOC or txt file using the subject line as the filename.  I did a quick google search and was suprised not to find this right away.  It'd be nice if the application had additional support for like virus checking etc.  But, I'm not too worried about this right now as we can setup certain controls like only allow people from inside our domain to send email to this address etc.
Desktop Search Tool
Copernic is the surprisingly the only desktop search tool which comes close to having the features I needed.  Out of the box it has several features I haven't seen in it's alternatives like Google Desktop Search... mainly it can index network file shares, has good filtering options like searching for pictures by size, and you can specify date ranges.  I doubt there is something better as I've searched the web many times but please let me know if you do know of something better.
Company background: We are a fairly small company (<10 employees).  So, I'm not too concerned about the network file share indexing.
Edit 1: This project is still active.  Any other suggestions besides the Google Search Appliance which is out of my companies price range.
Answer: Have you looked at the Google Search Appliance or Google Mini?
Comment: Not very closely.  I'm guessing it's several thousand dollars which is out of our price range at the moment.  Plus, unless the search features are drastically different from web search... it's not as appropriate.  I'd like to filter by date modified, file extention, image size, etc.


How can I get the car refinanced under my name if my girlfriend signed for the loan?

Question: I was trying to get a car financed under my name and it turned out my girlfriend had much better credit than i did. She had a score of 826 and mine was like 560. So she signed on the loan solely under her name instead of mine, which saved us like $100 a month. I was wondering how I can refinance under my name with her as a cosigner later on or get the title under my name? I just want to find out how I can be safe if anything ever happens between us since I am making all the payments.
Comment: She wants to do this as well, just in case you turn up a flake and don't make payments.
Comment: two things. you can add a person to your title without needing to change the loan terms/conditions. Secondly, if you do get a loan for the car, you are still going to be in the original situation you were in (high interest rate because your credit sucks).
Answer: You should have her sell it to you for the amount of the outstanding loan. You take out a loan in your name for the amount (or at least, the amount you have to come up with). You then transfer the title from her to you, just as you would if you were buying the car from someone else.
While the title is in her name, she has ownership. This isn't a technicality, this is the explicit legal situation you two have agreed to.
Comment: I'm not sure. If she cosigns, it's likely that she will have to be on the title for the car, which means you do not own it, or at least don't own it outright.
Comment: can i apply for the new loan with her as a cosigner?
Comment: im just trying to find a way to get myself on it, with or without her
Comment: This would be a very expensive move if private party car sales are subject to sales tax in your state.
Answer: The best solution is to "buy" the car and get your own loan (like @ChrisInEdmonton answered).
That being said, my credit union let me add my spouse to a title while I still had a loan for a title filing fee.   You may ask the bank that holds the title if they have a provision for adding someone to the title without changing the loan.   Total cost to me was an afternoon at the bank and something like $20 or $40 (it's been a while).
Comment: +1, this may well be the easiest solution. The car would then be joint-owned, but that may be sufficient.
Answer: Your best bet would be to add your name to the title through the bank or have her sell it to you for the amount she owes then you get a loan for that amount like they said before. If you guys split up at this point she'll legally get to keep the car you've been paying for. You could apply for a new loan and have her cosign but it'll make your monthly payments higher. Have her sell you the car for the amount owed them you get a loan for that amount. Since you are together and you've been paying for it you won't lose any money and your monthly payments won't be expensive if you don't owe that much on the car. Pretty much having her sell it to you would be the smartest idea cause keeping Her name on the title will allow Her to legally drive away in your car if you split and you don't want that lol


Orbot, SSL Error 3 - Why?

Question: I'm in a private network, where everything runs on a proxy, that uses a HTTP, the phone/tablet isn't rooted. On Orbot, I have put in the address, I have put in the ports and all the bridges too. However when I try to run the Orbot browser I get an error that says SSL Error 3. (For more info, YHGFL are the ones that are blocking websites such as reddit.) So if anyone can help, much appreciated.
Comment: Not an answer, just that I'm getting the same and cant find out why. Monitoring.
Comment: As far as I can figure, orweb wants to run https. Error 3 basically says that the site you're on has responded that it can run https (a secure connection), but that there is something wrong with the certificate that it's presenting. Fine, I can deal with that. I'm not going to enter any info that is confidential. BUT... orweb won't let me make an insecure connection. Enter http://... and orweb converts it to https. It doesn't show me the cert and ask if I want to grant an exemption. No, the developers are much smarter than am, and must protect me from myself.
Comment: Pretty much all the sites I visit are blocked by orweb/orbot making the application absolutely useless. The reasons some sites do not conform to this certificate issue is very acceptable to me.
Answer: In such cases proxies usually performing at least one of the bad tricks like that:

MitM attack by intruding into SSL/TLS connecions. Tor will give you an error because for directories it has hardcoded keys and on another screinario proxy just ruins the SSL handshake that it can't intervene into
by-ip blocklists for Tor entry guards and directories. Instead of the full list of Tor nodes, a list of directories and entry guards is relatively manageable to block by ip. Your connection will just die when trying to connect to these addresses - or maybe you'll see a 403 error
filtering remote/destination ports. If you're trying to connect to the port which is not in the "white list"/"allowed ports list" - it just dies or gets you 403

All this stuff makes it harder to use Tor, but you should try meek, obfs3 or obfs4 pluggable transports and bridges. This can help you. If they are blocking bridges too - try to use an unpublished bridge on port 443 with obfs3 or obfs4 - you can even make your own
Answer: Orbot has no interface for errors in SSL/TLS connections. So in case there is a wrong or unknown certificate it just drops the connection and shows this error message. When you visit the page with some other browser, you'll see a certificate warning.
The Guardian project works on integrating Firefox as a mobile browser. When this is deployed, you'll see the warning you're used to.

Orbot, SSL Error 3 - Why?


How to retrieve broken off end of gear cable from inside Shimano 105, 11 gear, lever?

Question: The gear cable was badly frayed in the handle system, where it bends through 90 deg. I had to cut it to remove the cable...but in doing so, the tip with the cable end (about 10mm long), has moved on round the corner and on into the lower part of the handle where it is very inaccessible.
I am able to get hold of the cable end with pliers but unable to pull it back, even with the gear changer set in it's highest gear because the nipple is stopping it.
Any ideas?
Do bike engineers in UK shops take these brifter gear levers apart or do they just advise replacement?
Comment: Sometimes you have to take it apart.  https://www.youtube.com/watch?v=xKNYgHuxBQ4
Comment: Did you try a magnet?
Comment: Pushing the cut end and twisting simultaneously can sometimes do it
Answer: I just got done doing this to my 5800-series brifter. Looking at it, it seems to be kind of fortified against amateur disassembly.
However, I discovered that this took a lot less disassembly than Criggie's answer had led me to believe. Indeed, you could do it with the brifter still on the handlebar.
All it took is undoing one screw on the underside of the lever:

This let me remove the two bottom parts of the brifter's case and access the part of the mechanism the stub of wire was in:

As a reassembly note, the larger piece is backwards in the image, those "teeth" point backwards in the assembled brifter.
Comment: These 11sp shifters all have this repeating cable problem. Ultegra too. Your photos show clearly how to access the mechanism, which can be done on the bike (in the field) and without fully removing the hood.
Comment: Great pictures. If anything, 5800 was the generation when they made this task much easier and quicker and I'd expect this to be possible while shifter is still mounted on the bar. I've certainly removed cable heads this way multiple times.
Answer: If I understand correctly, you have access to the end of the cable coming out of the shifter, but not the end inside the shifter, with the metal cylinder. To get access to the cylinder end, you need to pull on the cable end with pliers and then click through the gears until it is in what would be the smallest cog. At this point, you should be able to peel back the hood to grab the cylinder (maybe with needle nose pliers or a sharp spoke) to pull it through.
Answer: I've done this with a RSX shifter.  It was a full on dismantle and rebuild to get the mushroom out, because it had wedged and the wire stubs splayed out stopping it from shaking loose.
The real solution is to periodically change your gear inner cables when using brifters.  If shifting starts getting really tenuous, that's your warning to change the inner.
Do check out Disassembling Shimano integrated gear shifters (brifters) and  STI shifter sometimes doesn't catch in cooler weather
Comment: *If shifting starts getting really tenuous*  Unfortunately, the first-generation "hidden shiter cable" Shimano STI shifters (Ultegra's 6700, 105's 5700) have the shift cable make a rather sharp bend from where the cable housing ends on the top of the unit down into the shifter mechanism inside. The cable frays there, but sometimes the fraying doesn't impact shifting, which means you have no warning. Later versions of the shifters have the shift cable enter from the inner *side* of the shifter body.  I don't have enough time on the later versions to comment on the effectiveness of that change.
Comment: (cont) but since this appears to be one of the later 11-speed shifters, it likely has a similar problem.
Comment: IME it can go from "that's odd, it needs adjusting and I only did it a week ago" to snapped in the course of a single ride (of <100km).  I've snapped 2 rear cables on my Sora setup this way.  This is likely to be the same failure point that @AndrewHenle points out.


What is a rod knock?

Question: What is a rod knock? What causes a rod knock, how bad is a knocking rod, and how can I tell if a rod is knocking?
Answer: To get to basics, the rod (or connecting rod) is the portion of the engine which connects the piston to the crankshaft. Where the rod connects to the crankshaft there is a bearing which separates the rod itself from the crank journal. The bearing is made from a softer material than the rod or the crankshaft.
You can see most all of the internal parts of an engine in this exploded view below.
The connecting rod is #7, the crank shaft is #16, piston #4, and bearing can be found marked as #8.

When an engine is built, there are certain gap tolerances (specific distance measured in .001") which are built into it, the rod bearing to crankshaft journal being no different. In this case, the tolerance is there to allow a specific amount of oil through from a hole in the crankshaft journal and remain on the bearing surface. Oil films on the bearing and keeps the two parts from touching during normal engine operation. If the clearance gets too big from either wear or deformation, the oil will no longer film correctly and you will get the rod knock. The noise itself occurs due to metal on metal contact between the bearing and the crankshaft journal during the power stroke of the engine cycle. If the situation is really bad it can even be caused by the rod itself contacting the crankshaft journal (where the bearing has become out of place). The most common cause of rod knock is due to a spun bearing (bearing itself actually spins in the end of the rod so it becomes out of position). This usually happens due to rod cap stretch during abusive driving situations. It can also happen due to a lack of lubrication, either because of a lack of oil or because oil is flowing incorrectly. It can also be caused by a combination of any (or all) of the three.
A rod knock is a very serious issue with the engine. As you can probably tell from my write-up, it means the engine is no longer functioning correctly. It is the death knell of the engine. Once the rod knock occurs, it will not cure itself. The rod bearing must either be replaced along with fixing associated parts (you don't usually replace just one rod bearing as the entire engine would need rebuilt at that point), or the engine will need to be replaced.
A rod knock is as described ... A low pitched knocking sound which can be heard low in the engine. It will increase in frequency as the engine speeds up, but can usually be heard at any engine speed. If you hear a knocking sound which seems to disappear after the engine warms up, it's probably not a rod knock. It may be something as innocuous as a leaking exhaust gasket. If you believe you have a rod knock, you should seek a second opinion from a trusted mechanic. A rod knock is an expensive fix, so you need to make sure of what it is prior to diving in head first.
Answer: Rod knock is caused by a severe failure of one or more crankshaft connecting rod bearings. Repairs require engine removal and complete disassembly at significant expense.  The most common cause is lack of engine oil, this is usually the first part in an engine to fail when it runs out of oil. The second most common cause is very hard driving. The test is simple, rev up the engine and listen for a loud knock in time with rotation; an experienced tech knows this sound all too well. Not every noise is a rod knock, so an experienced ear is needed.  I saw three this week: one driven too hard, one ran out of oil and one manufactured incorrectly.
If you think your engine might have this problem do not run the engine, get it to an experienced tech.
Answer: I have only heard a rod knock, or spun bearing, once when I was asked to diagnose a friends car and although I had never heard one before I diagnosed it and it was in fact a spun rod bearing -- which was confirmed upon removal and disassembly and rebuild.
Valve tick and rod knock are often confused. Neither is a particularly good situation, but rod knock is much worse as Paulster2's response explains. Valve tick can be just because of low oil.
Valve tick  is a lighter more tinny sound at a higher pitch than the lower pitched and more subdued rod knock. Rod knock will come from the low end, versus valve tick from the top end. You can use a piece of vacuum tubing as a makeshift stethoscope with one end near (no in) your ear and the other end moving towards the sound.
If you open the oil fill cap on the cylinder head and the noise gets louder/clearer, it is valve tick. Is you take the engine oil dipstick out and listen there and the sound gets louder/clearer, it is a knock from the lower end and most likely a rod bearing.
Please note that running the car with the dipstick removed will create a vacuum leak and the idle will be poor and you might throw a check engine code. But if troubleshooting a potential spun bearing, a CE code is not really your main concern. The engine will idle correctly once the dipstick is put back in, and if a code was thrown it will clear over time or with a code clearing tool.
Piston slap could also be confused with valve tick and rod knock. It would be tough to explain how the sound would be different between rod knock and piston slap, but the general rule is if you have a knock from the engine -- and especially the low end -- it isn't good and the engine won't be running long and repairs will be costly and become more costly if you continue running the engine.
Running the engine in hopes it will go away on its own will lead to a seized engine, piston through the hood, rod through the block etc.
The good news is there are a lot of knocking sounds that originate external to the engine, and if that is the case the problem isn't necessarily severe. Worn engine mounts, bad belt, pulley, etc. are examples.
The problem is misdiagnosis does happen and results in a good engine being torn down and a lot of costs sunk. That can happen either by honest mistake, or a shady shop milking a customer for unnecessary repairs.
There are companies that you can send an engine oil sample for analysis to confirm. A severe problem with the low end will have high metallic content in the oil. If you aren't sure and want to be sure, get an oil analysis done.
If you do have an engine problem in the internals which is making audible noise, don't waste your time or money on the various products sold as "engine repair". While it is possible adding product might reduce the sound or make it go away, the damage is not reversed. People do this to sell a car to an unsuspecting buyer and mask the engine knock. People don't do this as a permanent fix.
Answer: I have had rod knock for over 8 years on my daily driver. Its not good but its not the apocolypse people are claiming. It happened when the oil line broke on my astro v6 on the highway and it ran till the engine siezed up. Towed it back home and dropped the pan. The pan was full of bearing pieces. So I ordered cheap new main and rod bearings and installed them from the pan side. It was no big deal. One rod bearing was in particularly torn up shape. Thats the one that heated up the most. Replace oil and filter a few times and the engine runs smooth and strong again with great oil pressure, except for that knocking. The crank journal on that one rod must be deformed oblong and the van is NOT worth all the work of a replaced engine. So I run it with the knock and it still runs today. I dont race it. First gear is the knockyist so I lift my accelerator at 10mph so the tranny shifts up to higher gears. Then the knock is barely there. And most important, I run as thick an oil as I can find. 20w50 and when I go on long trips, I pour in a quart of motor honey. Thick oil is a shock absorber to a huge rod bearing gap that is too expensive to fix. And if Im towing a heavy load, thats even better on the bad rod because its working so hard it cant lift off the crank to smack back down again. So there you go. The poor mans cure for rod knock headaches. I never looked at the cam shaft but clearly no worse for the wear. The crank burns up WAY quicker than the camshaft. Soon I will drop the pan to see the toll of 8 years of knocking. I will install a new rod bearing of Standard size when I do, but I will have a used rod cap at the ready in case the rod cap looks like it needs replaced. No point in using oversized bearings since the crank journal is oblonged. What I need is a new high tech high temperature plastic bearing to absorb the knock impact without making a sound. Ive waited 8 years but i guess I will have to wait some more. :)
Comment: Welcome to Motor Vehicle Maintenance & Repair! I'm not really sure how this answers the OP's question at large. It imparts your experience with rod knocks, but really doesn't give much information in reference to what the OP asking. What you've written here does not add anything past what has already been written in other answers. Please read entries in the [Help Center](https://mechanics.stackexchange.com/help/answering) about answering questions and take [The Tour](https://mechanics.stackexchange.com/tour) which explains how Stack Exchange works.

What is a rod knock?


How astronomers distinguishes between natural and artificial signals coming from outer space?

Question: How astronomers really distinguishes between the natural and artificial signals? From time to time astronomers detects many signals from outer space and SETI is always trying to find signals that carries the sign of intelligent beings. The Wow signals was such a much hyped signal that we received. So what properties a signal should carry so that we can conclude it is from some alien civilizations?
Comment: The signal was a single detection that was never repeated.  It's pretty much impossible to say *what* it was or *where* it came from, or even if it was nothing more than an equipment error.  The last question you ask seems like an interesting one to get answers to, though.
Comment: Yes I want to know how to distinguish between the characteristics of signals.
Comment: The only artificiality we know of is what we ourselves do. So if we find ourselves, then we have a perfect match. Ironically, scientific SETI is geocentric.
Answer: We could begin to conclude if a signal is from some Extra Terrestrial Intelligence (ETI) if the signals are very difficult or impossible to explain by non-life origins or terrestrial origins. One commonly cited example is with a very narrowband radio signal. In natural radio emission, the frequencies are spread out due to processes like Doppler shift which raise and lower the frequency or radio emission. The Wow signal was so narrowband that it behaved just like one would expect for ETI, but having only one detection that disappeared makes it hard to be sure it wasn't interference or a problem with that particular antenna.
I would suggest that ETI detection should have some of these properties, but feel free to add more:

No natural abiotic terrestrial phenomenon that can produce it
Verifiability - multiple detection methods, instruments and teams that can confirm the signal is not due to errors in processing, analysis or local interference
Evidence for non-random patterns such as prime numbers

KIC 8462852 currently has a feasible solution that dust escaping from a comet or multiple comets can obscure light from its host star. This natural explanation has ways of being confirmed (such as wavelength dependence to the stellar blockage), which will help with the first criterion. Hopefully, the flux dips observed in Kepler's days ~800 and ~1500 will repeat in the future but if they don't, it fails the second criterion. As with definition life, it is hard to come up with a rule book. However, if we see a lot of the properties we associate with ETI, we can start the classification process. As more evidence comes in, like polarization, multi-wavelength and Doppler shift data for KIC 8462852, we can evaluate which criteria are satisfied.
Comment: Can modulation be a factor? Communication signals got AM/FM modulation can a natural signal be modulated?
Comment: Got to know about lots of stuff, beautiful answer.
Answer: A signal artificial is a product from no natural radio frequency composition, so ,we principally change Amplitude (AM) or frequency(FM) and combinations, but required a pattern like a time or position, and a common "simple structure of communication", this algorithms are used to detect a signal from Intelligence
Answer: Considering the vastness of space, an alien(artificial) signal will have to be pointed in our direction and when it reaches us the strength will be very very small. Natural signals are more pronounced and 'appear' all the time. To duplicate a natural signal the artificial source have to have lot of energy resources at disposal.


In the Dune series, why are they not using computers and programming related technologies?

Question: I've never quite understood this about the series. They have space travel, but most other things about their universe seem primitive compared to ours.
Comment: Many machines on IX. https://en.wikipedia.org/wiki/Ix_(Dune)
Comment: They do use them, but are careful not to go too far.
Answer: It is connected to the Buthlerian Jihad - the crusade against computers and AI technologies that left them universally banned. The punishment for violation is death.
From the glossary in the original Dune:

Jihad, Butlerian: (see also Great Revolt) — the crusade against computers, thinking machines, and conscious robots begun in 201 B.G. and concluded in 108 B.G. Its chief commandment remains in the O.C. Bible as "Thou shalt not make a machine in the likeness of a human mind."
Comment: @Bill So killing AI.SE wan't really because of low-level questions? (-;
Comment: We are still comfortably shy of violating that command.
Comment: *You'll never get me alive!*
Comment: @MateenUlhaq *"We, uh, weren't... intending to? The entire plan was to execute you anway..."*
Answer: They are using mentats, the human equivalent of a computer, which came with analytical capabilities - the equivalent of programming, and with mnemonic abilities - the equivalent of computer data storage (databases).
For space travel they are using navigators, which are also an equivalent for a specialized navigation and prediction computer.
Comment: @Teknophilia Yeah, it's a clear reference.
Comment: "the human equivalent of a computer" You prolly want to understand the etymology of the word '[computer](https://en.wikipedia.org/wiki/Computer_(occupation))'.
Comment: I'm curious if the mentats from Fallout's universe come from Dune?
Answer: One of the prequel books by Herbert's son: Machine Crusade, fills in the past where computers took over the early planets settled by humanity. The uprising to overthrow the computer/cybernetic/robot civilization was called the Butlerian Jihad (one of the final battles involved glassing and sterilizing Earth). It was so traumatic that following the destruction of the computers, having computers, or even machines that worked like human minds, were forbidden.
Comment: I liked those books but felt they seriously missed the mark. When I read Dune as a kid I imagined the Butlerian jihad to be a political and philosophical thing. Then Brian Herbert goes and invents a canon where there was literally a war against robots. This is just one of the reasons I've never fully bought into Brian Herbert's work.
Answer: The series of novels isn't entirely consistent about what exactly constitutes a computer and what sort of limitations are imposed by the Butlerian Jihad prohibitions.
In Dune, it first seems that the limit stops at a what we would recognize as artificial intelligence able to pass a Turing Test - in practical terms where a human interrogator unable to see subjects cannot tell the differences of written (or typed) responses to questions asked of both a human and computer. This would allow for data storage, decision trees (if/else statements), and automated control systems using state machines. One would think that this would be necessary for signal processing required for interstellar communication at the very least.  Basically, at Dune, it does not appear that Turing Completeness is punishable by death :-)
Herbert would appear to raise the bar in God Emperor of Dune. Moneo (Leto II's lieutenant) is observed by Duncan Idaho to be hiding printouts from something behind a hidden door of what Duncan assumes to be a computer used for simply storing data, prompting Duncan to speculate that Moneo is 'testing the boundaries' of the Butlerian Jihad prohibitions. This would indicate that any sort of digital storage device constitutes a computer "in man's likeness"...now HTML (in our day) would be forbidden. This is fine so far because it makes accomplishments of biological and mechanical engineers even more impressive, and the scope of technologies used in the Dune universe is limited at this point to what is seen on Arrakis itself, which is fairly primitive but fascinating.
However, in the next book Frank Herbert takes a detour in Heretics where he goes off-planet and describes devices like the T-Probe, torture/interrogation devices which can basically hold a subjects consciousness in digital memory, and interrogators can query and manipulate the digital representation of consciousness and make modifications to the subject. These never raised any questions or seemed alarming in concept, however at this point in Heretics people had more important things to worry about...
So, it jumps around a bit but I would speculate that, much like our own religions, the rules are interpreted differently by folks over time.
Answer: Spoilers ahead, hover to see them:

 Because machines that think were extinguished during Butlerian Jihad because they represent a perverted imitation of human mind. They use mentats (human computers) instead. However, if I'm not mistaken, Ixians break this rule, and other worlds tolerate this mostly because they need their technology.
Comment: Hardly a spoiler ...
Answer: From what I remember, there was a computer revolt prior to the time of Paul Atreides, so they started training people to be human computers (Mentats).
Answer: It's one of the most interesting things about the series.  As others have noted in their sound answers, the Butlerian Jihad, fought against machines who tried to take over human society, resulted in a universal ban of what we might call AI.
Despite this, however, the planet Ix, and to a lesser extent Richese, are seen as leaders in technology and are somewhat mistrusted because of their flirtation with the boundaries of the anti-AI rule.  Indeed, in the later books Leto sees the rebirth of AI on Ix as the possible downfall of mankind, but doesn't fully defeat them.  Dancan Idaho (reincarnated) thinks it's because Leto can't help but be fascinated by the possibility of a joint man-machine future.

Idaho: "He was fascinated by the idea of human and machine inextricably bound to each other, each testing the limits of the other."

This exploration of the idea is about as far as the AI aspect of Dune gets though.
It's one of the core assumptions of the series that there is no AI, but it does come up semi-frequently.  By restraining this particular aspect of technological advancement, the idea of a feudal society with Dukes and Barons, hand-to-hand war fighting, concubines, etc. becomes credible.
Answer: My thought is they simply are not needed. Peter De Vries says something like

"Those things were toys compared to me. You yourself Baron could
  outperform them"
Answer: They are using computers, but their intelligence is limited. Computers with AI (Artificial Intelligence) is banned. It's impossible not to use computers in space and build laser weapons and ships.
Comment: The accepted answer already mentions  Buthlerian Jihad. For space travel they have the navigators.


What causes the dimensions of a star increase when its hydrogen fuel is exhausted?

Question: What causes the dimensions of a star increase when its hydrogen fuel is exhausted? For example, the Sun is expected to increase its radius 250 times. What causes this if its temperature is expected to fall? How gas can expand if the temperature falls?
Answer: The Sun will never run out of Hydrogen. This is a common misconception.
At this moment the Sun is fusing Hydrogen into Helium. This fused Helium remains at the core until it will reach a critical mass. At this point the core will begin to collapse. This collapse increases the temperature and pressure around the core where Hydrogen is being fused causing the increase the Hydrogen fusion which also causes an increase of the radiation pressure making the outer layers to expand and cool.
Once the core reaches a temperature of about 100 million Kelvin Helium fusion starts dramatically (Helium Flash) with high radiation pressure in the core. Here is where the Sun will reach 250 times it's current radius.
When the Helium fusion stabilizes the radiation pressure at the cores decreases making the Sun's radius to shrink.
The temperature will only drop at the surface because as it's expands it's further from the core.
Comment: According to The Disappearing Spoon, at least as I understand it, an increase in temperature results in a *decrease* in the rate of fusion--a fact which establishes the equilibrium temperature for a star of given composition.  If helium is capable of supporting fusion at higher temperatures than hydrogen which is subjected to similar pressure, that would suggest a higher equilibrium temperature.
Comment: Temperature is not all what matters in fusion. There are high increases in pressures in the core.
Comment: Density is a function of pressure and temperature.  As temperatures increase, density decreases.  Further, by my understanding, in order for atoms to fuse, the difference in their velocity vectors must be in a certain range. If too small, the nuclei will be pushed apart by their electric charges. If too great, the kinetic energy remaining after the collision will carry them apart. Similar to the reason that nuclear reactors need something to moderate the speed of the neutrons flying around therein.
Comment: @supercat Not exactly.  In degenerate matter pressure is almost completely independent of temperature.  This is what critically happens in various stages of the evolution of various stars (such as a helium flash): the core becomes degenerate before it can begin fusing, so temperature can scale up (or down) drastically with little to no pressure change, resulting in an extremely rapid fusion of nearly the entire core once temperatures reach a certain point.


Does proofs are programs apply to any functional program?

Question: Does Curry howard correspondence, apply to all Functional Program, e.g. in Haskell. i.e. Is it possible to write Equivalent Haskell programs, to COQ proofs?
Answer: In Haskell there are more programs than there are Coq proofs because Haskell has general recursion whereas Coq does not. (In fact Coq allows you to extract proofs into Haskell code.)
The reason that Coq does not have general recursion is that with it we can "prove" anything, simply by saying "to prove $t$ just make a recursive call to itself":
proveAnything :: t
proveAnything = proveAnything

In some languages, for instance in OCaml, you can't do it this way so you have to go indirectly through a recursive function call:
let rec proveAnythingAux _ = proveAnythingAux ()
let proveAnything = proveAnythingAux ()

This shows that type theory can be used for many things, two of which are programming and logic. The difference between these two is general recursion: we want it in programming but it makes logic inconsistent.
Answer: The Curry-Howard correspond is an observation that the structure of type systems mirrors the structure of logics, specifically propositions. Under this view, we can see similarities between an expression of a certain type, and a proof of a proposition.
Of course, there are many type systems (and logical systems) under the sun, and it is not an exact correspondence. Some type systems are stronger than other. Some languages that call themselves functional don't even have type systems (e.g. Lisp).
Moreover, the mapping is not always intuitive: what does it mean to say that the type of natural numbers is a proposition? It would be more accurate to say that some types can be considered propositions.


Exposure time for spectroscopy compared to photometry

Question: For a report I'm writing, I'm interested in comparing the exposure time required for spectroscopy versus photometry for a given magnitude. I found the figures on pages 7 and 8 of this lecture particularly informative. I tried emailing the author, but his email address is inactive. Where can I get similar information?
Answer: Your question is a bit unclear. Compare in what sense?
The problem boils down to that you have a fixed number of photons in a wavelength band and you can choose, with the appropriate filters or dispersion elements, how many "bins" to divide these photons into.
To accumulate the same total number of photons with the same telescope will take the same amount of time, except putting more optical elements in the way will reduce the efficiency of the instrument. Filters are more efficient than spectrographs by factors of a few to an order of magnitude.
However a further factor to consider, is that although in principle we could divide the light up as finely as we want, there may be static sources of noise that are independent of the signal. In the case of a CCD detector, this means the read noise.
If you want read noise not to limit the observations, then the product of the bin size and exposure time needs to be large enough that the square root of the accumulated counts (including any sky background) in a bin exceeds the read noise.
An example might help. Suppose I have a star that I observe for 10s through a V-band filter with a width of 100 nm and it produces 1000 detected photons on a CCD, where the star image effectively illuminates 10 pixels, each of which has a read noise of 10 counts. The total read noise is $10\sqrt{10} = \sqrt{1000}$ counts (the square root of the total variance) and equals the Poisson noise from the source plus sky. Ignoring the sky, the signal to noise ratio is $1000/\sqrt{1000+1000}=22$.
Now suppose I do slitless spectroscopy, passing the starlight through a diffraction grating, splitting the light into 1 nm bins. My signal strength in each bin is divided by 100, but the read noise is approximately the same. To obtain a spectrum with a similar signal to noise ratio you would need to expose for 100 times longer, i.e.1000 s (probably longer because a diffraction grating is not as efficient as a filter).
So there is no general answer to your question, it depends on the spectrograph efficiency, the "resolution" of the spectrograph, the relative contributions of source, sky and read noise and the signal to noise ratio desired.
A simple rule of thumb to get an exposure that is just limited by read noise for an imaging filter of wavelength width $w$ and a spectrograph with a resolution element $\Delta \lambda$, would be to observe for a factor of $w/\Delta \lambda$ longer, with an extra factor of a few to account for poorer spectrograph efficiency.
Edit:
To test my ideas I go to the Isaac Newton group of telescopes' signal to noise calculator.http://catserver.ing.iac.es/signal/
I try observing a 20th magnitude star for 10s with a V filter on the WHT prime focus, assuming 1 arcsec seeing and no moon. This gives me a SNR of 46.
To get the same SNR in a low resolution spectrum withe ISIS spectrograph and 158R grating (lowest resolution available) takes 15,000 s.
Does this stack up with what I said above? Each pixel in the spectrum is 0.16 nm. If the V band filter is about 100nm wide, my crude formula above suggested an increase in exposure time of 100/0.16 = 625. But the instrument throughput is only 33% (compared with essentially 100% for the filter) so we have to add another factor 3, to get a required exposure that is 1875 times as long as for the photometry. Pretty close!
Comment: Fair comment. I'm just interested in highlighting the long exposure times necessary to get a spectrum of a dim object, compared to getting a photometric magnitude (say, in V band) of the same object. I appreciate that the situation is not that simple, but are there any resources out there that do a good job of comparing how long it takes to get a spectrum with how long it takes to get photo data?
Comment: @Jim421616 why can't you work out what you want from the last paragraph of my answer? "Get a spectrum" is incredibly vague. At what resolution?
Comment: I wrote that comment before you added your edits, I think (unless I just missed them). Your edits do help me answer my question, thank you. I'll mark as answered.


When should you carry a firearm when hiking/trekking?

Question: When my friend planned to hike the Appalachian trail, his mother insisted he take her small handgun. I didn't think it would be a great idea in that case, but I'm sure there must be times when such gear would be advisable. Is it ever necessary if there aren't known dangers from large predators?
Comment: Note that the AT goes through the extreme of gun friendly and gun hostile states. Reviewing the state laws is a must, reviewing the local laws in states which do not have pre-emption is also important. handgunlaw.us is a good overview as is this book: http://www.gunlaws.com/travel.htm .
Comment: This link might be helpful: http://www.appalachiantrials.com/guns-youll-need/
Comment: I don't agree with most of the replies on here advising you to not carry. Assuming the right training and CCW permit, I think that it can be prudent to carry when you're out in the wilderness. Having said that, the AT does cross through federal lands and most of those lands prohibit the concealed carry of firearms (regardless of whether you have a CCW or not).
Comment: most answers in this thread assume that you need to shoot a bear / other large mammal as it's charging at you. Common advice is to stand your ground against a bear charge and it is most likely to avoid you. This is why national parks in Canada prohibit firearms - otherwise a lot of bears would get killed that weren't committed to a real attack
Comment: @JimBeam "assuming the right training" - that person wouldn't be asking. See the first sentence and last paragraph of my answer.
Comment: I wonder if the question had been made in Europe/for an european trail, too. Most people worry about whether they will drill holes in her toothbrush to save weight and you want to carry a handgun :D
Comment: A better use of the space and weight  in your pack would be to include a good quality pair of lightweight running shoes. As long as you can sprint faster than your hiking buddy, you don't need to worry about predator attacks ;-)
Comment: @That Idiot, Mother knows best!
Comment: Related: https://outdoors.stackexchange.com/questions/13265/what-is-the-minimum-caliber-of-handgun-that-would-stop-a-grizzly-bear#comment68618_13265 and https://outdoors.stackexchange.com/questions/6987/which-gun-should-i-use-on-the-trail-to-protect-myself-against-bears
Answer: For the purposes of defense, the only situation that comes to mind would be hiking through an area known for criminal activity ( think marijuana farm ). And even then, is a small handgun really going to help you ward off criminals with assault rifles ( it would probably just get you killed faster )?
If you're thinking of situation involving large predators, think again. Even if you managed to hit a target that's charging right at you, you're chances of doing sufficient damage with a small handgun are slim unless you've some type of professional training for such a situation.
You'll live longer if you stick to nonviolent methods ( avoiding criminal activity / alerting animals to your presence ). I leave my firearms at home when I'm out hiking.
Comment: For most polar regions where you may encounter polar bears, there are laws requiring you to carry a hunting rifle. Pretty certain that's a special case though :-)
Comment: A bit of both.  I'm pretty sure Europeans killed off most of their dangerous wildlife ages ago, so now the main risk is from drunken moose.  (I'm only being semi-serious, but I really can't think of that much dangerous European wildlife beyond the periphery, e.g. polar bears.)
Comment: However to balance that out, [the number of deaths due to bear attacks in the whole of the lower 48 states, in the ten years 2000-2010, is...3!](http://www.backpacker.com/news-and-events/news/trail-news/ask-a-bear-how-many-bear-attacks-really-2/)
Comment: The AT will be well known to anyone trying to hide illegal activity in the woods.  You're simply not going to stumble on something like a marijuana farm on or near the AT.
Comment: Agreed.  Think of it this way: bear hunters use high-powered rifles, only fire when they have a clear shot, and it still sometimes takes more than one shot to bring down the animal.  A handgun is just going to make the bear angry.  Better stick with pepper spray.
Comment: @DJClayworth: And even that probably overstates the danger. I suspect that at least some of these people who got killed were doing something stupid such as taunting the bear.
Comment: The last part sums it up. I've never heard of carrying weapons in fear of wilderness except from someone who made an expedition to Greenland. I really can't imagine animals are really *THAT* more dangerous in the US compared to e.g. Europe. Or is this just a mentally?
Comment: In Europe we still have bears and wolfs in some areas. Romania, Scandinavia and Russia mainly. Those can be of a problem, but a handgun is just a dead weight. Hunting rifle (against bears) or a shotgun (against wolfs) must be used. But yes, in tourist popular places all predators were killed by humans.
Comment: North American wildlife is significantly more dangerous than European. Bears, wolves, coyotes, lynx, mountain lion (and in the right places, alligators) are all fairly common. I don't believe that changes the answer though.
Comment: I've got to disagree. Your assertion about dangerous predators is completely wrong. People often encounter predators such as mountain lion who are potentially deadly, but have thin enough skin and can be easily stopped by a regular 9mm handguns. Ditto coyotes. For self-defense too, a girl hiking thorough the woods is an easy prey, but nobody would harass a girl with a 9mm. Finally, criminal with so-called "assault rifles" are extremely rare: statistically, only 1% gun-related crimes involve rifles of any kind.
Answer: If you need to ask, the answer is almost certainly never.
There are places (Northern Quebec, Labrador, Ontario and Manitoba near Hudson's Bay) where due to polar bear activity you should be accompanied by a guide/guard who will have a serious rifle and dedicate significant time to watching for bears while you do your scientific research or marvel at the scenery. These guides are trained on how to shoot and how to know when to shoot, and their guns are not small.
There are also less wild places where your big worry is the two-footed predators. If you think they are enough of a danger to you that you need a gun, they probably have a bigger gun. You're restricted by what you can carry over days or weeks and the bad guys are not.
This is not to say that you shouldn't bring a gun with you if you are a hunter, you know how to use it, and you know how to tell you should use it. But if you're someone who lives in the city and worries about wild animals attacking you on the trail, not only are you worrying about the wrong thing (spraining your ankle is far more likely to kill you) you are imagining the wrong solution.
Comment: Brilliant point about really being a city guy being worried about animals attack.. +1
Answer: No, there is nothing on the AT that justifies carrying a firearm.
The extra weight and space is much more of a detriment than the extremely unlikely and frankly inconceivable case where a firearm would be a help.
Since the AT crosses many jurisdictions, there may also be legal issues that could vary every few miles.  The whole concept just doesn't make sense.  A spare water bottle consuming the same space and weight would be far more useful.
Answer: If you are being attacked by a large predator a "small handgun" will accomplish nothing. If you hit something sensitive you will probably make it angrier - it won't make any difference to you if it dies from it's injuries the day after tomorrow, but at least it had a good final meal.
Smith & Wesson used to make a short-barrel .50 revolver aimed at the wilderness survival market - a 3 inch barrel is nearly useless outside of an elevator but that much power will drop most carnivores in their tracks, assuming you hit it on the first shot. As you won't get much notice from a hunting predator you will have to have the weapon ready - in your pack won't work. If it's a territorial animal you usually have lots of time to leave.
Churchill, Manitoba has a problem with polar bears. The residents there carry either a 12-gauge with deer slugs or a .45 rifle. Yes, that's big, and without experience it's just a noisy club. A charging bear can cover 100 feet in 3 seconds - can you draw faster than that? It's very much like a wild-west duel, loser gets eaten.
Also note that powerful weapons are heavy - you need the mass to soak up the recoil. The above S&W .50 revolver has recoil comparable to a mule's kick, the much larger Desert Eagle is quite manageable.
So unless you are planning on hunting small game, don't bother with mom's .38.
Comment: Good protection against gangs of marauding rodents.
Comment: Reality check: can a bear really run 100m in 3s - that's 33 m/s or 70+ mph? [Wikipedia](http://en.wikipedia.org/wiki/Polar_bear#Physical_characteristics) states 25 mph for a sprinting bear, and 70 mph for a [cheetah](http://en.wikipedia.org/wiki/Polar_bear#Physical_characteristics).
Comment: @PhilipKendall: apparently that was a typo, it is now 100ft, which is ~23mph. Wikipedia quotes top speed for grizzly bear to be ~40mph. I don't think I can personally reach 15mph, even if I really try.
Comment: Ha, I actually think she offered him a .25
Answer: I used to do a lot of backpacking with my wife in the backcountry in the Rocky Mountains. The places we hiked were remote - often hours would pass without seeing anybody else. I gave thought to getting a handgun, as protection from bad folks and/or wildlife. My father and I are fisherman, not hunters, so my knowledge of wild animals was minimal, and I had never given it thought in my younger years. So I started reading up on it, and occasionally talking to people who were hunters (I myself am not).
Over the years I've read various books on the outdoors, have talked to friends and other folks, and of course have spent a lot of time in the mountains, and I came to the conclusion that it is not necessary to carry a firearm for protection against animals in the mountains. Most animals, including black bears and mountain lions, are just too timid, they end up running away when they see you. Chances of a close encounter with an aggressive animal are slim. Supposedly bear spray is as effective, or more, than a firearm, so this, a hunting knife and a walking stick is what I carry. I've never had to use any. That's not  to say I can't and won't someday feel threatened by a large animal, but so far I haven't. The handful of times I've seen bears in the wild, they ran away once they saw me. I've never seen a mountain lion at all. (That's not to say they haven't seen me.)
Now regarding whether you should carry a firearm as protection against other people, this is more of a personal choice, but statistically the answer here probably would be no, too. I'm sure we've all got a much greater chance of getting mugged in our hometown than getting attacked out by someone in the wilderness. But I have thought about it before, because where we used to hike we occasionally encountered hunters and once in while our paths would cross with men who didn't seem particularly savory. Again, nothing ever happened, but I think I would have felt better if I had a handgun with me, or at least if they could see that I had one (although not a hunter I am experienced shooting guns). Again, we're talking about people here, and there are certain types of people who will try to take advantage of others if they feel they have the upper hand. So I think this is a personal preference and if I were to go backpacking a lot again in remote areas, I might reconsider getting a .38 or .357. As one of my friends used to say, it's not the 4-legged animals he's worried about, it's the 2-legged ones. I've got a mountain-man buddy in Colorado who lives by himself for months at a time backpacking in the mountains (he's in 60s now and still does this) and he carries a .38 with him.
So... for protection against animals? Should not carry a firearm. Carry spray instead.
Protection against people? Personal choice. Generally speaking should not need it.
now of course if you plan to go hunting, that's a different matter. One time, we were hiking and came across a man hiking down the trail with a .22 rifle (with a silencer) slung over his shoulder and holding a blue grouse in his hand. We stopped to talk with him, he had just killed the grouse and was going to prepare it and eat it later for his dinner. He said it's the best-tasting bird you could ever have. After a few minutes, we parted ways and, sure enough, a little bit later on the trail we came across a clearing with a bunch of blue grouse frolicking around. Well, I gave some thought to the idea of getting a .22 (or resurrecting my dad's old .22s), but never acted on it.
Answer: Generally speaking I agree with the sentiment that carrying a handgun is not necessary and more likely to get you into trouble than out of it, and I wouldn't suggest it was the right approach, however for the sake of a rounded argument...
I have read & watched several guides on bear encounters, including a mandatory video before hiking in Canada's Kluane National Park. These guides typically say something along the lines of "if you're being mauled by a bear play dead, unless the attack lasts more than 30 seconds, then fight back as it likely has decided to eat you". One day I finally wondered - how would I fight back?
For this reason I always keep a large knife to hand. I don't expect to disable a charging bear with it but I do expect a few slashes to the head / neck could potentially save my life. It's likely a better bet than a clenched fist. The same argument says that a handgun is likely better than a knife.
However you're probably more likely to hit your hiking partner :)
Answer: Let me qualify myself, first, for any reader interested: I'm a former Marine and avid hiker, and I consider myself fairly well educated on firearms, their use, and more importantly what it feels like to be afraid for your very life.
The above is important when addressing an issue that most people here only have a philosophical understanding of.
To begin, you don't need a firearm. That's a personal choice, much like the choice to carry bear spray, a dedicated axe, or a folding shovel. This choice differs from the aforementioned in that it may carry legal consequence, so do your homework.
Secondly, a firearm could save your life from both two and four legged animals, provided you pack smart. A pocket .25, a .38 special, or a 9mm are not really that effective. Better than nothing in the last two cases, but worse than useless in the first. If you want a pistol, pack a big round with decent penetrating to get through fat layers.  Hollow point is not your friend with big game.
In regards to the issues others have brought up, if a criminal armed with a rifle is going to shoot you, a pistol is not going to make it worse.  It can only make it better, and I really strongly advise you to ignore anyone who believes that. As a man trained and experienced in that very issue, they're full of it if they're spouting such nonsense.
Yes, you are more likely to die in a car accident than to need a gun. Funny, I was more likely to die in a car accident than to need one in Iraq, but I still had one.
In regards to the likelihood of you shooting your buddy instead of a bear at a few feet, that's Hollywood bs. And NEVER knife fight a bear. Hacking a slashing is not enough. You have to penetrate his hide. Rawhide has been an effective defense against slashing since time immemorial. As for stabbing, you need about a foot and a half penetrating to do much to a bear. Have fun with an 8 inch knife. Also, if you'd like to know how easy it is to ram a knife through a 2 legged predator, go stab a tire. That's kind of what ramming a blase through cartilage and bone is going to feel like.
Point is, you have to weigh the pros and cons yourself. If you have enough gun and there's even a mildly reasonable chance you'll need it, consult the local laws and carry away. If not, or if it's illegal, don't carry. This isn't rocket science. I will say the following, though. One alternative might make people insult you, look down upon you, or avoid your company, but it could save your life. The other will result in those same people most likely not noticing you, and it will make it less uncomfortable for others to talk to you on the trail, but you might end up dead. Take your pick.
Comment: As a former US Army Scout, I agree with your reasoning on carrying a firearm. The chance of needing it is remote but I would rather have it with me and not need it than need it and not have it. HOWEVER, I wouldn't recommend that just anyone takes a firearm with them hiking. Having the proper training is just as important as the weapon itself.
Comment: In regards to the likelihood of you shooting your buddy instead of a bear at a few feet, there was a bear attack around here earlier this year where exactly that happened.
Answer: To say that there is nothing that would provide a reason for carrying a firearm while hiking is completely false. There are numerous accounts where people have been killed by wildlife and hostile people. However, this doesn't just mean that anyone should just carry a firearm with them because they are scared. The likelihood of these situations happening is extremely low.
The purpose of having a firearm is to provide an absolute last method of protection from something/someone that is trying to kill you (unless you are hunting). Using a firearm as a means of protection should not be taken lightly. Without the proper training you could be more harmful to yourself than your fear of being attacked.
As for if you should take a firearm with you or not...
Consider the following

Can you logistically afford to carry a weapon with ammunition?
Are there any historical cases of animal/human attacks in the area you are hiking in?
Do you have the proper training to use a firearm against an attacking force?
Do you have the proper type/size of firearm for the threats you may face?
Are you willing to kill another animal, or worse, a human if necessary?
Answer: I always carry some kind of firearm when hiking, I do not care if I never need one, the fact is, if I do need one it will be a matter of life or death.
I have never needed a seat belt in a car or jeep to save my life, does that mean I should not wear a seat belt?
As for the made up stats on people having issues in state or federal parks, Google will show you there are plenty of times a firearm (with some training) has or would have made a difference.
A firearm is a tool and if needed, could be priceless. I doubt anyone would argue rapes, robberies and murders do not occur in isolated areas of the wilderness, because the facts are such crimes do occur there.
There are lite weight pistols that carry easy and are effective, any woman not carrying a weapon of so kind in remote areas is pretty ignorant in my professional opinion as a former law enforcement officer.
Comment: Statistically there is a much greater probability of you getting in a car accident than being attacked in the woods. So your analogy isn't really applicable. But I am not opposed to carrying a firearm in the backcountry, although is it "needed"? Probably not.
Comment: Maybe it makes *your* world better but that's what I call ignorant then.
Comment: For long distance hiking a firearm often become less appealing. In many countries carrying is also not an option. One should consider the bigger risk factors; robberies and murders would not be on the top of my list when backpacking.


Are keeping assistance dogs permissible in Islam?

Question: Are keeping assistance dogs permissible in Islam? I have speech dysfluency and assistance dogs can be kept for emotional support. They can provide reassurance in public situations. I know that its not permissible to keep them just for the reason of it so do the rulings apply in this circumstance?
Answer: It is not permissible for a Muslim to keep a dog, unless he needs this dog for hunting, guarding livestock or guarding crops.
As Quran says :

وَ تَحۡسَبُهُمۡ اَيۡقَاظًا وَّهُمۡ رُقُوۡدٌ ۖ وَنُـقَلِّبُهُمۡ ذَاتَ الۡيَمِيۡنِ وَ ذَاتَ الشِّمَالِ ۖ وَكَلۡبُهُمۡ بَاسِطٌ ذِرَاعَيۡهِ بِالۡوَصِيۡدِ ؕ لَوِ اطَّلَعۡتَ عَلَيۡهِمۡ لَوَلَّيۡتَ مِنۡهُمۡ فِرَارًا وَّلَمُلِئۡتَ مِنۡهُمۡ رُعۡبًا
  (18:18)
On seeing them you would fancy them to be awake though they were
  asleep; and We caused them to turn their sides to their right and to
  their left, and their dog sat stretching out its forelegs on the
  threshold of the Cave. Had you looked upon them you would have
  certainly fled away from them, their sight filling you with terror.

But this is not to say that we should treat the dogs unfairly (I won't comment on the whole killing the dog issue, because i'm not even sure if it is true or not) because stories are told how a prostitute gained a place in heaven because she gave the thirsty dog a drink. The story gain a place in Islam teachings because the animal was a dog (God knows that it will be an issue) and it shows that all animals should be treated equally with kindness only then will God look kindly to us as well.
As they may be used as guards, so the Quran says :

يَسۡـَٔـــلُوۡنَكَ مَاذَاۤ اُحِلَّ لَهُمۡؕ قُلۡ اُحِلَّ لَـكُمُ الطَّيِّبٰتُ ۙ وَمَا عَلَّمۡتُمۡ مِّنَ الۡجَـوَارِحِ مُكَلِّبِيۡنَ تُعَلِّمُوۡنَهُنَّ مِمَّا عَلَّمَكُمُ اللّٰهُ فَكُلُوۡا مِمَّاۤ اَمۡسَكۡنَ عَلَيۡكُمۡ وَاذۡكُرُوا اسۡمَ اللّٰهِ عَلَيۡهِ وَاتَّقُوا اللّٰهَ ؕ اِنَّ اللّٰهَ سَرِيۡعُ الۡحِسَابِ
  (5:4)
They ask you what has been made lawful to them. Say: 'All clean things
  have been made lawful to you, and such hunting animals as you teach,
  training them to hunt, teaching them the knowledge Allah has given you
  - you may eat what they catch for you19 - but invoke the name of Allah on it.20 Have fear of Allah (in violating His Law). Allah is swift in
  His reckoning.'.

Hope this helps.
Comment: Thank you for your answer. But there is nothing in your reference to support what you convey. Please consider adding relevant answers.
Comment: Sure @Ghasan, I tried to make it to the point, by referencing the ayat according to question, if you think, it could be made better, please suggest  an edit.
Answer: It is not permissible to have dogs as pets without a real need; for guarding mainly. (source) (Arabic source)
I am not sure how it affects those with speech dysfluency, but you might need to consult your local scholar or Muslim community on the matter for more context. Because as for dogs, it is quite difficult to clean oneself from its Najasah.


mouse interaction with ls output - click to open

Question: I would like to be able to (double) click a file from the ls output and open it with the associated program. Anyone knows a way to do this?
Mouse-console interaction is possible with GPM and links shows how it works.
Answer: This is up to your terminal to handle.
urxvt has a plugin interface that enables this kind of interaction. One of the standard plugins provides clickable URLs directly in the terminal. These plugins are Perl scripts, and it would surely be in the scope to do something close to what you want.
Easy would be to let fully specified paths open with the WM default application.
Harder would be to let relative links understand their directory context (perhaps reading $PWD), but it would also be possible.
Answer: The only think I could think of is if you write some sort of program using GPM and a simple programming language that can implement GPM. Then if you use this, you could replace the ls file in your binary folder (probably either /bin or /usr/bin) with this program (in compiled form).


a word/couple to express eagerness to win

Question: Winning is a thing that is supposed to happen during an event.
Before the event, of course, there are many competitors eager to win.
I need a nice word or phrase to express eagerness to win — but not winning itself.
Comment: **keenness** is also comparable to **eagerness*.
Answer: Ambitious describes an eagerness to succeed and also implies that success has not yet been attained.
Answer: Alternatives that are quite similar to eagerness to win are

eagerness to succeed
desire to win

Maybe these works in your context, too

fighting spirit
competitive spirit
Comment: +1 for beating me to _competitive spirit_. I think that's spot-on.
Answer: I think eagerness to win is a good alternative. I can´t really think of a better term that expresses exactly that, but Enthusiasm may be close, though. The problem is that with no additional context, the enthusiasm could be taken for other aspects of the competition, and not specifically for winning.
Comment: u r right abt enthusiasm
Answer: You could consider: pumped up, fired up, psyched (anybody else remember the cheerleaders shouting "P-S-Y-C-H-E-D psyched is what we want to be!")
Answer: Two words come close to me, at least in usage.
One is thrust, as in "We were stymied in our thrust for victory."
The second is the commoner hunger: "The team had an insatiable hunger for victory."
Answer: Motivation - one could write of highly motivated competitors
Answer: A couple more:
'Desire for victory' implies the person, group or team have set their sights on winning and will only be satisfied if they emerge from the scenario as victorious.
'Lust for victory' implies that the person/people are as equally determined, and may even resort to slightly unsportsmanlike behaviour in order to win (rigging a competition, cheating during gameplay or engaging in subterfuge)
Answer: There is a perfectly adequate word which means "eager to win". And that's "competitive".
And that's shows the redundancy in what you're trying to say, because it leaves you with:

Before the event, of course, there are many competitive competitors

Pretty much by definition, if they're competitors, they're expected to be competitive.
If you want to say that some entrants are more competitive than others (and imply that some entrants aren't serious competitors at all - maybe they're just there to make up the numbers), then say that.
Or are you trying to take it down the route of saying that although there are many competitors initially, many get eliminated despite their best efforts?
All in all, the question probably needs a little more context to make sense of it.
Answer: Taken in context the word determined might fit:

Before the event there were many determined competitors.


Python: Adding a asection to a PE file

Question: I am working with PE binaries using Python and the pefile library. Its good for reading information out of a binary and rewriting certain bytes. If I wanted to add a section to the file then i am clueless on how to do it. I would be thankful if someone can provide me any previous works in this topic or help regarding this.
Answer: This isn't a language specific concept. The values you'll need to modify as they are (or are meant to be) referenced:
!IMAGE_FILE_HEADER:
    - NumberOfSections
!IMAGE_OPTIONAL_HEADER:
    - SizeOfImage
    - SizeOfHeaders
(optional depending on which sections you're modifying. Relevant for .text, .data, and .idata but afaik are unused)
    - SizeOfCode, SizeOfInitializedData, or SizeOfUninitializedData
    - BaseOfCode, BaseOfData
Then you'll have to construct a new IMAGE_SECTION_HEADER, some values are dependant on the image.
    - VirtualAddress and VirtualSize must be aligned to !IMAGE_OPTIONAL_HEADER.SectionAlignment
    - PointerToRawData and SizeOfRawData must be aligned to !IMAGE_OPTIONAL_HEADER.FileAlignment
    - PointerToRelocations is a little tricky. If there is not enough space at the end of !IMAGE_OPTIONAL_HEADER.DataDirectory[IMAGE_DIRECTORY_ENTRY_BASERELOC], which can be calculated by finding the size of the section it is contained in, subtracting the ::.Size and (::.VirtualAddress - Reloc Section Virtual Address), you must relocate the table. After that, you'll just need to adjust the size and append.
Example
Appending an data section:
    - Check if enough room in headers for another section
    - Add
(IMAGE_SECTION_HEADER){
.VirtualSize = align_up(%SIZE%, !IMAGE_OPTIONAL_HEADER.SectionAlignment,
.SizeOfRawData = align_up(%SIZE%, !IMAGE_OPTIONAL_HEADER.FileAlignment),
.VirtualAddress = find_max(!IMAGE_SECTION_HEADER[].VirtualAddress + !IMAGE_SECTION_HEADER[].VirtualSize),
.PointerToRawData = find_max(!IMAGE_SECTION_HEADER[].PointerToRawData + !IMAGE_SECTION_HEADER[].SizeOfRawData),
.Characteristics = IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE | IMAGE_SCN_CNT_INITIALIZED_DATA
}

Then resize the file, copy your data into the .PointeToRawData
Answer: Adding a new PE section is the main approach I take when I significantly modify a PE file.  There are position and RVA and VA-specific dependencies in existing binaries.  Changing those things is challenging, especially if the base relocation table is missing or corrupted for whatever reason.
Let's take a look at the general approach I take in Windows PE Tools for PHP (it's PHP but a similar implementation/approach for Python should be possible):
https://github.com/cubiclesoft/php-winpefile/blob/master/support/win_pe_file.php#L2222
The CreateNewPESection() function first calls PrepareForNewPESection().  PrepareForNewPESection() checks to see if there is enough space in the header as-is for a new section.  If there is enough space, then it just returns.  Note that there can be all kinds of weird stuff in the header though such as Bound Imports, Debug Directory data, Relocations, etc.  PrepareForNewPESection() calculates the actual amount of available space by reducing the value if it encounters such data in the header space.
If there isn't enough space, PrepareForNewPESection() will resize the headers and shift data around up to the PE Section Alignment by minimizing the DOS stub and wiping unneeded information from the headers to attempt to make space.  A new section only needs 40 bytes.  Resizing the headers is an optional and complex exercise just to gain a few bytes of storage.
Assuming there is enough space, CreateNewPESection() then calculates the next available RVA by walking the sections and calculating the section's maximum RVA value.  Note that the RVA size in a section can actually be smaller than the raw data size.  The Windows loader in those cases appears to assume that the RVA size is equal to the section-aligned raw data size.  I consider those to be broken PE files that just happen to work.  The new section is then file aligned (usually a no-op) and the new data for the section (also file aligned) is placed at the end of the file.
After adding the PE section, don't forget to update various values:  The number of sections in the PE header as well as the code size, initialized data size, uninitialized data size, and, most importantly, the image size in the PE optional header (and, of course, the PE checksum when all is said and done).
Instead of adding another section, appending to the last section may also be an option worth considering.  First, look at the flags of the section.  If the flags match what you are looking for and the last section is also the last RVA and located at the end of the physical file, then that section may be a candidate for reuse by just resizing the existing section instead of adding a new section.  Doing this helps reduce the possibility of running out of space in the header for new sections.
Answer: See this: Adding/removing sections with Python http://www.reddit.com/r/ReverseEngineering/comments/1jpghd/addingremoving_sections_with_python/
Comment: I can tell you why I downvoted. The reason is that this amounts to a link-only answer. The link may go stale and the other link in the comment has gone stale, unless you [edit it](https://git.n0p.cc/SectionDoubleP.git). At a minimum you should include the steps and tools in _this_ answer. Not a mere link ...

Python: Adding a asection to a PE file