Locrian mode and power chords

Question: I'm studying in an online game music course, and I'm experimenting Modes to add unusual sound to the music. I'm a complete newbie in music. So let's have the Locrian mode, the root chord is a dimished one, so the V is dimished. As far as I read, power chord are created with a V, so, if I want to play a power chord on the root in locrian mode, do I have to use the dimished fifth, or have I to use the fifth, playing a note that does not belong to the key? I tried the two: strangely the one with the fifth, playing the note out of key sounds better ( ie, it produce a dark feeling ) but is it correct to play?
Comment: Sounds like you are doing very well for a complete newbie - keep it up!
Answer: The term 'Power chord' normally means a perfect 5th.  It can sound like a reinforced single note, because of the way harmonics work. But then it's often played on guitar with a distorted sound, so the harmonics are all mussed up anyway!  Whatever.  We know what a 'Power chord' sounds like.
You are perfectly at liberty to play a diminished 5th in a 'power chord' sort of way.  It won't have the same effect of reinforcing the harmonics of the bottom note.  It would probably be inaccurate to call it a 'Power chord'.  But that doesn't matter.  If you like the sound, use it.
Don't worry about theory 'allowing' you to do things.  Theory describes, it does not command.  (I say this a lot, and will continue saying it until it sinks in :-)   If you're thinking harmonically, and are going for a Locrian feel, it may be better to keep all notes within the mode.  Or you can belt out a Locrian scale, each note played as a 'Power chord' with the (perfect) 5th above added.   Theory will help you describe what you're doing.  It won't tell you WHAT to do.
Comment: thanks for the reply: actually the one that fit better is the "standard" power chord, the one that respect the model, sounds weak, maybe the extra note give some extra "distorsion" that increase the tension...
Answer: If you want to be 'faithful' to the mode/scale you are in (in your case the Locrian Mode), you have to use the diminished fifths. For instance, the Power chords would be B-F (diminished fifth), C-G (natural fifth), D-A (natural fifth) etc..
It's not uncommon though to use notes outside the mode. You can use the Power Chord B-F# which is a natural fifth. Musicians do this all the time.
Really depends on what you want to create. My suggestion would be to try both out and see what you like best. In some cases you might like the diminished sound and in some other cases, you might want the neutral sounding natural fifth.
Answer: Here's the script I used to generate the below plots
As Laurence Payne said, it's only a power chord if you use a pure fifth. Any chord you put through distortion will give you not only the frequencies actually played, but also new components that weren't originally there at all, via intermodulation.
plotWindow . distortionCompare $ sineSig 163 ^+^ sineSig 308

Recall that even a single note on an instrument like guitar corresponds to a whole bunch of sinusoidial frequencies, however because these are in neat integer ratios those actually line up perfectly with the new distortion-frequencies, that's why distortion works fine on single guitar notes – it simply gives a more agressive, overtone-rich spectrum but doesn't change the harmonic content itself:
plotWindow . distortionCompare $ stringSig 100

Similarly, if you distort a powerchord (in which the fundamental frequencies are in a neat 3:2 ratio) the result has merely a "filled up" spectrum, but the new frequencies align perfectly with the already-there harmonic content, thus you get a very fat and agressive, but still clear sound:
plotWindow . distortionCompare $ stringSig (note "A2") ^+^ stringSig (note "E3")

In fact, all the frequencies you see here are integer multiples of 55 Hz, i.e. of A1. Therefore, this sound actually makes sense even in A-Locrian, despite the E that isn't supposed to fit in that scale.
Incidentally, the harmonic-alignment effect still kind-of works with a major third:
plotWindow . distortionCompare $ stringSig (note "C3") ^+^ stringSig (note "E3")

Here, the new frequencies fit pretty well in the spectrum, but are significantly "smeared out", which makes the signal dirty in a way that starts to resemble white noise. That's actually an artifact of the tuning system: I've used the common 12-edo tuning above, which handles thirds pretty badly. In the correct just intonation, major thirds distort in fact very nicely:
plotWindow . distortionCompare $ stringSig (note "C3") ^+^ stringSig (5/4*note "C3")

Anyway, for something as dissonant as a tritone, all bets are off:
plotWindow . distortionCompare $ stringSig (note "B2") ^+^ stringSig (note "F3")

Here, the intermodulation frequencies are all over the place. There's nothing the ear can really cling to anymore, so it won't sound powerful anymore but just annoying.
So no, it doesn't make a lot of sense to play diminished fifths when accompaning Locrian mode on electric guitar. Better just play powerful deep single notes if you want a dark sound, or indeed standard powerchords, as already suggested.
Alternatively: it is actually possible to re-tune a tritone-near interval to something that can be resolved in just intonation, namely the 7:5 ratio that also occurs in the harmonic seventh chord (aka Barbershop seventh):
plotWindow . distortionCompare $ stringSig (note "B2") ^+^ stringSig (7/5*note "B2")

You can achieve that by tuning the F note of the B-Locrian scale down by 17 cents from its 12-edo frequency. That's not really feasible on a 12-edo guitar, but it can be done on a many-fretted microtonal instrument. 31-edo is definitely capable of this. 22-edo might also work.
Ron Sword makes such guitars.
Comment: @Stinkfoot well, _yeah_... although obviously it doesn't say anything about what amount of dissonance is good/bad. Furthermore it's all only so clear when you actually toss in a significant amount of distortion, concretely 1D time-domain nonlinear distortion. Which is mostly characteristic for analogue electronic processing, and thus to ≈1920-1990 Western music. In most other cultures, the interaction between voices is largely linear. And all the discussion only applies when you start out with tones consisting of integer-multiple harmonics, e.g. for Gamelan it doesn't make sense at all.
Comment: _what amount of dissonance is good/bad_ Regardless - there is a math and physics that determine the degree of dissonance the ear perceives. The point is that physics is fundamental to how we hear music, in the same way as how we see colors. We can no more hear a perfect 5th like we hear a tritone, than we can see green when the color is purple. I'm making this point because there are those who believe that Functional Harmony is just some sort of meaningless "European" convention. It's not, no more than the overtone series is.
Comment: Good graphs. Such representations put the lie to the claim that how we hear music is "entirely subjective" and "one man's dissonance is another man's consonance".
Answer: The only difference between the Phrygian and Locrian modes is that the fifth scale degree of the Locrian mode is 1 semitone flat from the Phrygian one. At this point, unless you want your Locrian music to sound like it's in the Phrygian mode instead, I'm afraid you're stuck with diminished fifths for playing "power chords" on the root.
Comment: This is also true, I noticed that probably the correct mode to play, is Phrygian!
Comment: @FelicePollano but then the question is all wrong! Phrygian mode is of course fine to use (done all the time in metal), but it's something entirely different from Locrian.
Comment: @leftaroundabout possibly it is: I'm a newbie :) Actully is true anyway that B phrygian and B locrian differ just for the F#, so they are not so far, anyway, are they?
Comment: Sure, they are closely related, but that diminished fifth is the crucial distinguishing part of the Locrian mode. Changing it to Phrygian is about as character-changing as switching from melodic minor to an ordinary (Ionian) major scale.

Locrian mode and power chords


Purpose of Phase Information

Question: I am learning Fourier Transform from many days but till now I am not able to understand what does phase angle image show us or tell us? They say that MAGNITUDE tells "how much" of a certain frequency component is present and the PHASE tells "where" the frequency component is in the image. I understood about the MAGNITUDE part but not able to understand PHASE part. Please explain what it means by "PHASE tells "where" the frequency component is in the image". Thanks
Answer: I don't think of the phase as providing information related to position or location.
A simple example might be illustrative. In 1-D, consider these two signals, x and y:
t = 0:0.001:0.1;
x = cos(2*pi*20*t) + cos(2*pi*30*t);
y = cos(2*pi*20*t + pi/4) + cos(2*pi*30*t - pi/6);

The magnitude spectrums of x and y are the same, but they're not the same signal; if you plot them, you'll see that they're different. In the frequency domain, you need both the magnitude and the phase to fully describe the signals. It doesn't make sense to refer to the harmonics as "being somewhere".
Answer: The fourier transform decomposes a signal into basic sinusoidal waves that are phase shifted in such a way that when added together, they sum up to form the original time domain signal. The magnitude, is the energy that that particular frequency contributes to the summation.

Purpose of Phase Information


Adding height to wooden fence post

Question: Would it be strong enough if I was to add 1ft of fence post to a 5ft garden post using a box joint? I am looking at attaching a 6ft wooden gate to it on one side and a standard fence panel to the other side
Comment: Are you suggesting that you want to extend the length of the post without first removing it from the ground?
Answer: A box joint might be strong enough but that's just a guess, the loads placed on the finished post will determine if it is or it isn't, along with how accurately it's cut of course.
Could be a bit difficult cutting a box joint in situ on a standing fence post accurately enough! Even if for that reason alone you may want to go for something simpler, like a scarf joint (glued and further strengthened by nailing, screws or through-bolts).
You could get away with a butt joint, suitably reinforced, if you don't mind the aesthetics. Even though this is an end-grain joint you should glue it, with structural adhesive or epoxy, but the reinforcing metal plates attached to the outside will provide most of the strength.

You may want to give some thought to whether it would be better to bite the bullet and take out the 5 foot post and replace it with a 6 foot post. Probably simpler and faster and it might work out cheaper at the end of the day, best of all there wouldn't be any worries about the strength of whatever lengthening method you chose otherwise.
Comment: You hit the nail on the head here, there may be a huge difference in answer between "could you..." and "should you..."
Answer: Yes, I think a box-joint would provide sufficient strength, at least if you add the additional foot on top, and not on the bottom where there might be more leverage on the joint, but even there it would probably suffice.
I'd cut the fingers on the thin and long side, as most of the strength in the joint will come from the glue, and more, longer fingers will mean more gluing surface.

(example image for long finger joints from woodgears.ca)

In addition to the box-joint I remembered a video that might proof some good food for thoughts by Mathias Wandel where he fixes a broken chair leg.

Adding height to wooden fence post


Why does my system power off suddenly?

Question: I am using desktop with intel dual core processor on biostar motherboard. Now days,after 1 hour working(not exact) it suddenly power off(not shut down) with out warning.when i try to power it on,some time it woks for few minutes and again power off and some time it  start for 2 or 3 second and power off(before booting). can any one help me to identify and fix this issue??
Answer: There are a lot of things can cause this such as:
1- Check if the CPU fan is working fine
2- Check if viruses found in your PC.
3- Check your electricity cable.
Comment: 1. b) check the CPU temperature isn't climbing too high
Answer: Are you living in India or where electricity reliability is poor? If yes, on my recent visit I noticed several thousand volt surges in power supply (frying two motherboards and one PSU). So, do you have a good voltage stabilizer or Uninterrupted Power Supply?
Second, if you assembled the PC, did you use high quality CPU grease (Thermal compound) like Artic5 or like that?
Third, do you have simple fan or a cooling tower on CPU?
If any one of this is correct, I am guessing that you have a misconfigured PC setup, including corrupt BIOS, motherboard or CPU temp sensor.
You can monitor CPU temp with CPUz or Sandra Lite (NOTE: I am note endorsing any product mentioned herein)
http://www.filehippo.com/software/system_tuning/
http://www.alcpu.com/CoreTemp/
Also, it is possible that your Power Supply Unit is not able to provide enough power for dual core CPU. You should have at least 650W PSU, may be 750W. Do you have top notch GPU? If so, it is drawing more power that CPU goes without power (may be a few hundredth of millisecond).

Why does my system power off suddenly?


Should an intranet web application utilize a CDN

Question: With the Announcement of the Microsoft AJAX CDN a debate arouse this morning about whether utilizing a public CDN for common libraries was a good idea for intranet applications. I can see both sides of the argument but without revealing too much of our discussion I wanted to put forth the topic on Stack Overflow to see other's opinions.
Answer: I'm a big fan of using CDNs for these things, but I think it would be a rare exception when using Google or Microsoft's CDN would be appropriate for an Intranet application.

For users on an internal network, an external request (even to a fast, nearby CDN) will be much slower than an internal request.
Often, these things need to be accessible when no Internet connection is present on the client.
Even if you do have geographically dispersed VPN users, all of their requests are often being routed through the company's network anyway, making the CDN request even slower than the VPN-local request.
Comment: What's about data privacy? You rely on the security of another server. If that script on the CDN is manipulated, it has access to the content of the intranet.
Comment: Intranets can be widespread. So we need to name also solutions for intranet based CDNs
Answer: The main advantage of a CDN is that it delivers content from close to the user.  Your intranet is closer still!
The second advantage is that the user might already have the content cached, which again isn't all that relevant on your intranet - you can set up caching to your own requirements, and delivering the content will be fast anyway.
The main disadvantage is that you put a key piece of your application into someone else's hands.  Unless the locality advantage is important, which in your case it isn't, that's a pointless risk.
The only people who might benefit would be remote workers, VPN'ing into your intranet, but even then the risks are likely to outweigh the benefits.
Answer: Well it depends on several things.
Is this intranet just at one location or spread across multiple locations?  If so are those locations in the same state/country/contininent?  Obviously the more locations you have and the more distance between them, the more utility a CDN would provide.
What server(s) will this be hosted on?  Are the servers used to host this application already bogged down from other running process/sites, etc?  The less server resources you have available, the more beneficial a CDN will become, as it will reduce the amount unnecessary server traffic and resources being used.
How many people will be using this application simultaneously?  If you are going to have lots of requests coming in every minute/second for static content like images, scripts, etc then more and more of your resources are going to be used delivering that content, slowing down the application as a whole.  This one goes hand-in-hand with the above question as well.
There's many other things to consider when looking at a CDN, but those are a few of the major points to think about.
Answer: Let's say most usually user of intranet are all on the same network so it would be faster to put your file on a local server.
But if your user are all around the world and using vpn or something else to connect to the intranet it might be not a bad idea to use a cdn.


What adjective would you choose if you want to elevate a workaholic to a higher degree?

Question: I want to refer a hard-working person something far more than referring him a mere "workaholic". What adjective should I choose with "workaholic", if I want to refer him as someone working even harder than a workaholic? What adjective would be proper: "ardent workaholic", "unstoppable workaholic", "hyper workaholic", "super workaholic" or any other adjective with "workaholic"? I agree that "workaholic" is a negative term: used for a person who obsessively work for long hours and thereby neglects other aspects of his life. The context in which I want to use the word "workaholic" is a positive one: I want to heap praise on him. What if I refer him a "relentless taskmaster"? Is there any better alternative? Please suggest.
Comment: How about *relentless workaholic*?
Comment: *inveterate* and perhaps *chronic* come to mind.  They don't mix metaphors.  *hopeless* might work along the same lines, as the -aholic suffix implies disease.
Comment: Workaholic has a somewhat negative connotation, like the person works so much that they neglect other elements of their life. Like they're out of balance in an unhealthy way. Do you want to convey that or do you just want to convey that the person works very hard?
Comment: Maybe "a god of obsessive labor."
Answer: I'm interpreting "higher degree" to mean that you'd put this particular person ahead (or beyond) a simple workaholic but are trying to describe them only in terms of how much of a workaholic they are. If this last point is true then words like "ardent", "unstoppable", and "hyper" each have an issue because they add additional information.  "Super" may work because it doesn't add information beyond a comparison with other (lesser) workaholics.

Ardent adds an unrequired indication of enthusiasm or passion.
Unstoppable adds an unrequired indication of inevitability.
Hyper adds an unrequired indication of energy.

A workaholic may have any, all, or none of those qualities.  Some workaholics are dull.
Super workaholic doubles down on the workaholic quality and only the workaholic quality without bringing in other associated, but distict, qualities.  It even manages to work in both negitive and positive contexts since it does not indicate aproval or disaproval.  It's simply an amplifier.
Alternatives to super:
total, serious, extreme
Answer: I think the adjective pathological could provide the meaning you seek.

: extreme in a way that is not normal or that shows an illness or
  mental problem
Link-MW

In US usage, it does not necessarily imply that the person has a actual illness, just that their compulsion is so strong that the effect is similar.  This does imply that this is a harmful state of affairs.
A pathological workaholic.
Answer: I think the adjective you want is "dedicated" as in "She's dedicated to her job."  http://dictionary.reference.com/browse/dedicated.  In my opinion this does not have a negative connotation.


Can an Optical Low Pass Filter be applied via a lens filter?

Question: I constantly see references to video being the application where an Optical Low Pass Filter is most useful, but it seems that still images do best without one. Would it be possible to then have a camera with a sensor sans the OLPF (such as the D7100) apply the benefits of an OLPF through a special filter on the lens? Do any manufacturers make such a filter?
Answer: In cameras without an Optical Low Pass Filter (OLPF) that are becoming more common, the high resolution of the sensor often approaches or even exceeds the resolving power of many of the lenses that will potentially be used with that camera. This means the limits of the lens itself provide the benefit of reducing moire. Reduction of moire, also known as aliasing, is the whole point of putting an OLPF, also sometimes called an anti-aliasing (AA) filter, in front of the sensor.
An OLPF works by refracting the light striking it into four paths. Since theses are very tightly spaced, this has the effect of slightly blurring the image focused on the sensor just behind the OLPF. You can't detect the four different images because the size of the spread produced by the OLPF is about the same size as a single pixel well, which is the smallest unit of detection the sensor is capable of.
There are at least these problems with trying to do this from the lens.

The light at the front and even the back of the lens is not focused. Current OLPFs are designed to refract light that is focused.
Changes within the lens, such as moving focus elements or zoom elements that change the focal length, would require different spreads of the lens mounted OLPF's effect to get the desired blur of the sensor's Nyquist Frequency.
Interchangeable lenses must be compatible with a variety of camera models, many of which have different sensor designs from the other models that are also compatible with the same lens mount design. A filter optimized for a sensor with 4µm pixel pitch would not be useable in a camera with a 6µm pixel pitch sensor. This issue is also compounded by the way that different cameras deal with using high resolution sensors that often exceed 20MP to produce HD video, which is only about 2MP in terms of resolution. Some use down sampling, others skip pixels. Each method produces it's own flavor of aliasing.
Even with a fixed-focal-length fixed-focus lens, designing a filter that could achieve the desired effect for a single specific sensor design would be difficult. If such a thing could even be achieved accurately enough from the front of the lens or even attached behind the lens' rear element within the limits of today's design and manufacturing technology it would be expensive and so sensitive to changes in temperature and other environmental factors that it could only be used in a strictly controlled environment.

Most of these issues are less severe if the camera in question skips pixels to produce video at HD resolution. Since the pixel size is the same but only about every third or fourth pixel is contributing to each frame of video, the margin for error in terms of the precise amount of blur induced would be much greater. There are a few such products on the market aimed at improving the anti-aliasing performance of cameras that already have an OLPF, but they are camera (not lens) specific and tend to install in the camera's mirror box rather than attach to the lens. They usually hold the reflex mirror in the up position the entire time they are installed.
Comment: You can mount the AF filter successfully *behind* the lens, however. This gets around three of the problems you state, the different pixel pitch issue is largely insignificant for cameras that use line skipping to produce HD video (which is almost all of them!)
Comment: Yes, but the question specifically asks, "Would it be possible to then have a camera with a sensor sans the OLPF (such as the D7100) apply the benefits of an OLPF through a special filter *on the lens*?" (italics added)
Comment: Also, by putting the filter *behind* the lens you preclude the possibility of using most camera models for anything that requires the mirror to be down so the viewfinder is functional. Even when using the camera for video, it may be preferred to do framing at times prior to shooting a scene without having the sensor constantly energized and generating heat.
Comment: Although the question specifically states "Can you put an OLPF in front of the lens?", "no, but you can put one behind the lens" is a better answer than "no" IMO. Also there are ways to mount the filter behind the lens that don't interfere with standard operation of the mirror, some lenses have slots for rear mounted filters.
Comment: But no one makes such a filter for a rear lens filter holder. At least in the case of Canon, none of the newer designs include a rear gel filter holder (not to be confused with internal filter holders on the super telephoto series, which are placed in front of the rear group). Probably also because they are more effective/precise the closer they are to the sensor.
Answer: The problem with aliasing in video is to do with the method of downsampling the high resolution sensor image to produce a 1080p video frame (roughly 2 megapixels, a fraction of the resolution of modern image sensor), which uses line skipping (only reading every three or four lines from the sensor).
This is akin to scaling images using "nearest neighbour" resampling in Photoshop (or other editing program). The gaps between the pixels that are read out is much greater than the 1 pixel blur radius of the camera's AA filter.
However there are after market solutions for video aliasing, including lens mounted solutions as you suggest, though I imagine the eventual blur radius will be somewhat dependent on focal length.
A better solution is to get a filter from Mosaic Engineering that mounts behind the lens, which are also specially designed for DSLR video (to provide sufficient blur for sensors that use line skipping).
Comment: what if you find the right amount of front focus?


Why can't LiAlH4 react with alcohols?

Question: In the reaction of $\ce{LiAlH4}$ with carboxylic acids, deprotonation is followed by a step in which $\ce{O-AlH2-}$ acts as a leaving group. The mechanism is given here in this answer.
$\ce{LiAlH4}$ does not, however, reduce alcohols. Why doesn't a similar reaction occur with alcohols - deprotonation, followed by substitution by a hydride ion and removal of $\ce{O-AlH2-}$?
Comment: Alcohols need to be turned into much better leaving groups.
Comment: I thought so too, but then as I said above, -OAlH2 does leave. And esters are able to react too, where the leaving group is -OR, which is even poorer.
Answer: The main issue is that the Al needs to remove its hydride. With a carboxylic acid and/or an aldehyde, it can stick its hydride onto the carbonyl carbon without issue. But the carbon bonded to the alcohol cannot take on a hydride.
Comment: This also explains Charles's confusion about the $\ce{-OR}$ group leaving in ester reduction (in the above comments). The hydride from $\ce{LiAlH4}$ isn't displacing the $\ce{-OR}$ group directly in a substitution-like mechanism, instead it's "only" reducing the carbonyl to a (hemi)acetal, and it's the collapse of the hemiacetal which kicks the $\ce{-OR}$ off, rather than the hydride transfer directly.
Comment: So in general, it's easier to substitute an ester and remove the -OR than an ether - since the leaving group isn't removed directly? Nucleophilic substitution is easier at carbonyl carbons of acid derivatives than at alcohols, ethers, amines, etc.? In nucleophilic substitution at any acid derivative - which is the RDS - the nucleophile's attack step or the step in which the group leaves?

Why can't LiAlH4 react with alcohols?


Is there a MIDI music notation program (e.g. Finale) that automatically detects rhythm?

Question: I want to notate some piano songs that I have written. My problem is that I can't find a program that will record the pitch and the rhythm of the note. In every program that I've seen, you have to manually enter the duration of the note. I have a MIDI keyboard and a MIDI-USB cable. I have computers that run Windows (XP, 7), Linux (Ubuntu), and Mac (PowerPC 10.4). I have tried Anvil Studio, Finale Notepad, and Musescore so far. Thanks!
Answer: This is possible in any notation program I'm familiar with.  In Finale (my choice), you use the HyperScribe function, outlined here:
http://www.finalemusic.com/usermanuals/finale2012win/content/finale/ID_MAINTOOL_HYPERSCRIBE.htm
I'm fairly certain Finale Notepad has this function.
Answer: Here is another one: http://notionmusic.com/
Using it on the iPad and Mac, works for me and is cheaper than most others. No need to manually modify pitch and note length.
You may want to watch this:

Shows how it works.
Answer: For Linux, take a look at http://rosegardenmusic.com/
It opens to a MIDI view initially, where you can record from your MIDI keyboard. The software quantizes the note durations into the program's internal representation, and with a click of a button you can switch to the score view to see the resulting sheet music.
There's also a Windows port of Rosegarden, but I believe it depends on KDE, and I don't know if they got the sound playback working yet.
Disclaimer: I'm listed as one of the Rosegarden developers, courtesy of two patches I contributed a few years ago.


What are some of the most logical and rational Hindu text?

Question: I am interested in old texts which uses rationale and logical arguments only to reach to conclusion or prove some axiom. Are there such text which can be rightfully called logical treatises, scientific papers.
Does ancient Hindu literature contain such body of texts?
Comment: The question is about "Hindu Texts" not "Hindu Facts". Should not be closed as duplicate.
Answer: In any logical/mathematical sysem, we have certain Axioms, whose validity are taken for granted within that system.
For example,  a mathematical system that tries to introduce the concept of real/complex numbers, the three Axioms - field, order and completeness Axioms - are taken for granted. That is they are not required to be proved (within that particular system). All the remaining propositions/theorems of that system are then proved using those Axioms.
The only Hindu scriptures which share this pattern to an extent are the Darshana Shastras (the 6 Philosophical scriptures - Samkhya, Nyaya etc).
In the Darshanas, we have the proofs/standards (known as Pramana) which serve the same purpose as does an Axiom in a mathematical system.
For example, for the Samkhya Philosophy, we have:

Drishtamanumanamaptavachanancha sarvapramanasiddhatvat |
Trividham pramanamishtam prameyasiddhih pramanAddhi ||
Pratyaksha (direct perception), anumAna (inferrence) and Apta Vakya
  (i.e words of the Rishis or scriptures) - these three standards are
  accepted in Samkhya. All other standards are accomplished/established
  by these three only. By using these three pramanas the propositions
  are established.
Samkhya Karika 4

So, just like all the theorems/propositions in a logical system, are established using the validity of the Axioms which are accepted in that system, in this Samkhya doctrine, all the propositions are similarly established using the three Pramanas which are accepted as valid in the doctrine.
Comment: I don't doubt your answer at all. But it's just a suggestion that the Bhavishya Purana also fits well in this answer.
Comment: @baba But how? Because it correctly predicts the future?
Comment: No. As the question asks about texts with rational and logical arguments, this book has many of those. But I gave a second thought to this question and realised that it only partially fits here. So it's fine not to include it in this answer.
Answer: In addition to the answer by @Rickross I recommend

Jonardon Ganeri: Philosophy in Classical India. The proper work of reason. Ganeri is familiar with mathematical logic. In his book, "Chapter III The rational basis of metaphysics" he attempts to reconstruct some of the Nyaya-Vaiseshika logical texts by a graph-theoretic approach. The chapter contains a detailed reference, not only to the original Indian sources.
More general concerning its philosophical scope is
Roy W. Perrett: An Introduction to Indian Philosophy. Perrett has a chapter on "Reasoning" which also discusses Nyaya logic. Perret tries to handle Indian and Western philosophy on the same footing. His approach aims to "give proper weight to cultural diversity - indeed requires it - but eschews any kind of relativism that would prohibit cross-cultural criticism." Also Perrett's book gives many references.

In my opinion, both texts are quite challenging.
Answer: Bhagwat Gita is the most logical book. It is also the source of Motivation. Once you read the book then you will get all the answer of your question.


Polite phrase apologizing for irregular (written) correspondence

Question: What is the set phrase used to apologize for not corresponding regularly?
Answer:
ご無沙汰しております。

means something like "I apologize for not contacting you for such a long time".
It is a set phrase which is polite and suited for written correspondence and thereby satisfies almost all your requirements, except for the fact that it doesn't mention that you regularly fail to keep in touch. But then, I don't see how mentioning this would have any positive effect.
As you haven't given a clear context for your question, I should just like to mention that the above is better suited if the "late" correspondence was initiated by your letter or email and you are not simply replying late to a particular letter or email. (For the latter, something like 「返事が遅くなり、申し訳ございませんでした」 would probably be more suited.)


Issues when using pgrouting's shortest path

Question: I am having some issues when using pgrouting's shortest path. I am following this tutorial available at http://workshop.pgrouting.org/chapters/shortest_path.html#dijkstra. This query returns a list of edges. Then I get the start and end points of each edge. Then I just join these points to show the shortest path. Just to let you know that I don't necessarily get the ending point of the first edge in the list to be the starting point of the second edge in the list returned. So I join, the ending and starting points of the two edges as well. However, sometimes the points are repeated and I have lines crossing over each other and the path looks a mess. What could be the reason behind this?
Comment: you need to assign_vertex_id('', float tolerance, '') http://workshop.pgrouting.org/chapters/topology.html
Comment: I already have it. I actually used osm2p tool to create the table consisting of the edges with their corresponding vertices
Answer: The result of shortest path is not ordered. Therefore you cannot rely on it. To visualize the results, you could use the edge geometries instead.
Comment: Do you know any way to order them in postgressql?


What is a good prepaid credit card?

Question: I recently came across the concept of prepaid credit cards. Although the name is nonsensical (there is no credit if it is prepaid), I find it quite interesting, since Credit Cards are a necessity in online purchases and traveling abroad. In these circumstances there are risks involved if your cc details are obtained. Any experiences with prepaid credit cards and what would be the most affordable prepaid credit card?
Comment: Helps to tell us where you're located.  These prepaid credit cards vary widely by country.
Comment: Belgium, Netherlands
Answer: Prepaid cards are not credit cards, they're debit cards (in a sense that there's no credit given to the holder, but rather an immediate debit from the holder's account). From the merchant point of view they're the same, unless the debit card is used as ATM card (which is a different kind of transaction).
The best debit card would be a debit card tied to your bank account. But that leaves you vulnerable in case of fraud (debited amounts are only returned after the investigation is through, whereas with credit cards - you only need to pay after the investigation is through and no fraud found, exactly the opposite).
Debit cards that you can buy in store ("Pre-paid" cards) are basically standard debit cards with account "hidden" from you, much higher fees, and usually without ATM service (i.e.: You cannot get the cash back, only use it for purchases). The fees on these cards range anywhere from 5% to 105% (when you put money on the card, pay for it, and loose all the money in "inactive" fees).
Many credit card issuers provide one-time code for internet purchases, which would be a better option if you're worried about on-line fraud.
For travelers - companies like Travelex provide pre-paid debit cards in various currencies, with ATM access, and fees which are reasonable (for Travelex the inactivity fee kicks in after a year of inactivity).
Comment: He was talking about online shopping security concerns and traveling, what would that have to do with the secured cards? Besides, secured cards are credit cards in all and any way, it's just a secured credit, vs the unsecured credit of the "ordinary" credit cards, they're not prepaid.
Answer: In North America these are generally referred to pre-paid cards.  Quite the difference in terminology. :-)
They are primarily useful to help (re)build credit history for those with out any or with bad  history.
Because the initial deposit is treated like a zero from the card perspective, when you so-called pay it off back to the initial deposit amount, this generates a good credit report that you pay your bill on time.
I cannot think of other good reasons to have cash tied up in this way.
Comment: Indeed, my mistake. It must be the late hour. Post paid is the normal situation.
Credit history is not so much an issue here. If you have bad credit history you are flagged as such at a central institute of credit registrations.
A cc here is primarily a form of payment. Most people pay their "debt" immediately.
I would like to have a prepaid credit card to do online payments. In case my cc details are obtained, I don't risque loosing the maximum allowed credit on my credit card.
Comment: In retrospect I did not fully understand the question(s).  THe last part "what is the most affordable" is not answerable in any case, as it would constantly change.  I might suggest another question specific to "should I use a prepaid ... for internet ..."
Comment: I think you confused Pre-Paid Cards (like the GreenDot) with secured credit cards (like Capital One Secured). The poster was asking about Pre-Paid Cards. These have no impact on the users credit report at all.
Answer: A number of banks and credit card companies issue single use "credit card" numbers.   These are very good for online purcases as they appear to the merchant as a standard master/visa card but with the security advantage that once you have used the number it cannot be used by anyone else.  Citi is one bank that reportedly offers this service but you will have to research for your own country.  Unfortunately these facilities tend to be made available country by country.
I believe that you can do the same thing through paypal.
Comment: This feature you speak of is a fraud protection feature that isn't related to the question at hand.
Comment: @Frazell - the OP wrote "In these circumstances there are risks involved if your cc details are obtained."  I would say that this part of the question is referring directly to fraud protection.  The previous sentence was referring to online purchases where this protection is particularly relevant.
Answer: What is the problem that you are trying to solve?
In most places, credit cards have fraud protections that limit your liability to fraudulent activity.
I've yet to see a scenario other than preventing the user from spending too much money where pre-paid cards made any sense.
Comment: In Europe budget airlines make per sector charges when you make bookings using any payment method other than their "preferred" card type.  In general this preferred card is the most obscure that they can find, trapping the majority of their customers into paying the fees.  For many airlines this is a Visa Electron debit card.  Ryanair charge if you use anything other than a prepaid Mastercard.  The fees are often higher than the airfare.  This is why I use one of these cards.
Comment: @Ian: Interesting fact. Didn't knew about this practise engaged by Airlines. Seems very innovative :)
Comment: There is a case going through the UK courts, brought by The Consumer's Association (they publish Which? magazine) that is attempting to outlaw this practice.

What is a good prepaid credit card?


Tire size conversion from 700 x 23c

Question: A tire with the size of 700 x 23c, when changed to inches, what is the diameter and what is the width?
Comment: It would help if we knew what you are trying to do. Are you trying to buy a new tire?
Answer: You're asking a question that cannot be answered.  Sorry - the plethora of tyre size measuring systems means there is no good answer.
Diameter could be 29 inches, it could be 28 inches, it could even be 27 inches.  But the bead seat IS 622 millimetres without exception.
The width likewise varies - there are fractional inch measurements that do not line up with the decimal inch of the same size - IE 1 1/2 inches is not the same width of tyre as 1.5 inches.  But 23mm is 23mm without exception.
This is why the ETRTO measurement system is simply superior to all that went before.  Not that its based on metric, but ETRTO is consistent and accurate.
A "700c" tyre in a width of 23 is a ETRTO measurement of 622-23, which is sometimes written as 23-622.
You might glean some more information from How do I know what size tyres can I fit on my rims? and from How do I determine my wheel size
Or consider asking about what you're trying to achieve - this sounds like an XY problem.
Comment: It is true that equal metric and fractional inch sizes in general don't match, but usually the difference is in rim diameter, not tire width.
Comment: And history behind why "700c" means "622 mm" is explained by the great [Sheldon Brown](https://www.sheldonbrown.com/tire-sizing.html)
Answer: To answer the question as written, 23 is the width of the tire in millimeters when mounted and inflated. The actual width depends on the rim width, and manufacturers typically don't tell which rim width the announced width is measured with.
Diameter is more complicated. 700mm is the outer diameter of "C" type tire when mounted and inflated. This gives rim diameter of 622mm (the same as 622, one of the two 28"s and 29"). It does not make any sense, but you can memorize or look up it. The 700A and 700B sizes have been long forgotten, but 650A and 650B are specified the same way.
Answer: It is correct (as stated in the other answers, which I've voted up) that tyre sizing systems mean the actual stated sizes can't be converted, and in fact the width of a given tyre will vary depending on the rim width.
That said, ETRTO 622-23 tyres are sometimes sold as 28x0.9" (random web example).  This link is priced in €, which isn't surprising - it's often German manufacturers/sellers that use 28" as a tyre size, even though they don't use inches otherwise.  This may help you if you're shopping for tyres and they're only specified in inches, but confirm the ETRTO size.

Tire size conversion from 700 x 23c


What does "believe the Bible" mean?

Question: What do Christians, namely Evangelicals, mean when they say it? To what extent must the Bible be "believed"? Does this connote a literal interpretation of the scriptures, or does this connote a general attitude of how a Christian may view the Bible?
Comment: It varies from person to person.
Comment: My Pastor, being a fundamentalist, meant basically what I described in my answer to [this question](http://christianity.stackexchange.com/questions/9961/from-a-fundamentalist-viewpoint-what-does-it-mean-to-take-the-bible-literally). Read it, apply sound principles when interpreting it, and if he says something contrary,take him to the verse(s) and point it out.  He may explain what he meant, and may take us to other Scriptures that show how I'm misunderstanding, or he may search it out and question his understanding.  His point is that he's fallible, God's Word is not.
Comment: I don't think there's an objective answer to this one.
Comment: @DavidStratton So, did you *know* what it means when your pastor said "Believe the Bible, not me."
Answer: It means to believe the propositions of Scripture to be true. Everyone believes some set of propositions to be true, which they cannot prove. For a Christian this axiom is: That the Bible is the Word of God (and hence is true in what it teaches).
Same applies to any belief....e.g. for a Muslim, they believe the propositions of the Koran to be true. Likewise Hindus believe the propositions of Vedas to be true. Atheists believe the propositions of Bertrand Russell, Dawkins and so on to be true. And if I believed all that your Pastor said (say his name is "Smith") then I would be called a Smithian in my belief.
But a Christian believes the propositions of the Bible to be true. For a person to say they are a Christian but say they don't believe the Biblical propositions is nonsense. A person may not state it exactly that way, but if they do not believe the Bible to be true then all they have left are their own muddled thoughts at least as far as being a Christian is concerned. So the propositions that God made the world, that Jesus is the Son of God, that He died and rose again from the grave and is coming back again, that God is a Trinity of persons etc all these propositions are clearly in the Bible (1 Cor.15:1-4). To believe these to be true is to be a Christian. Not to believe them is to be something else.
You ask, "Does it denote a literal interpretation"?  It depends on the genre of the passage being read e.g. if the genre is metaphorical then the passage needs to be read metaphorically or else confusion will reign. Where it is historical genre, then it needs to be read as history,  poetry as poetic and so on. The Bible is not written in a single genre.
Answer: I don't know that everyone who uses this phrase would say it quite this way, but the phrase could be reworded to make the meaning more plain.
"I believe the Bible is true."
How one applies this is not entirely uniform among the evangelicals that I know. It probably means that, in general, the speaker does not consider it proper to believe something appearing to be in opposition to a straightforward reading of the Bible.
If this is someone's response to something you have said, the more complete sentence might be, "I believe [God who wrote] the Bible, not you."
It may connote a "literal" reading of the text, but even that is a sliding scale. Even people who claim "literal readings" realize that some things are poetic, metaphorical, or figurative, though they probably restrict those allowances to certain places, like the books of wisdom or apocalyptic literature. Probably what most people mean when they speak of "literal" readings is that they prefer the simplest, most straightforward way of understanding what's written.'
It probably suggests that the speaker believes that the Bible is a sufficient and reliable source of information to lead us to Christ. I don't intend to prove such an assertion, but there are numerous evangelicals who claim to believe it.
Sometimes, when I hear people speak this way, it seems to me that they mean: "I believe what I read in the Bible, even if it doesn't make sense to me." Another phrase I've heard along these lines is "The Bible says it, and I believe it." It seems to me that this is a reactionary position to the theological acrobatics some "Bible experts" go through to read the scriptures and arrive at a conclusion that typical uneducated protestants don't consider reasonable. I don't subscribe to this philosophy, but I can at least understand why it might be appealing.
I frequently hear evangelicals refer to the Bible as if it were a person or living agent (e.g. "The Bible says, ..."). In a technical sense, this is not accurate, but if one believes that the Bible is the untainted, perfectly preserved Word of God, then it is only a matter of poetic usage to speak of the Bible as if it were a plenipotentiary representative of God himself.

What does "believe the Bible" mean?


How should I respond to interview questions when I don't know the answer?

Question: What should I answer when I'm stuck in a technical telephone interview? Is it ok to say that I don't know the answer or should I throw in my perspective (even though it might be wrong)?
I'm talking about interview which are more like rapid fire questions where you can't search on internet.
Comment: Always answer honestly. If you don't know, then that's your answer...perhaps add how you may go about getting the answer if need be.
Comment: This definitely depends on the job and question. I work in R&D and for some questions it'd be a big red flag if a candidate thought they knew the answer, when the question is intentionally designed to see how they might approach an unsolved problem, or how familiar they are with multiple techniques/solutions.
Answer: As a hiring manager, I prefer people don't waste my time (or theirs) making up an answer.  I guarantee that the majority of the time the person asking the question will know if you're just making up your answer.  After all,  questions are often asked not just to get an answer, but to gain insight on how you answer a question.
That being said, from my perspective it is perfectly acceptable to say "I don't know the answer to that, and I'm not familiar enough to hazard a guess."  It is also perfectly acceptable to say "I'm not entirely sure of an answer, but given my limited understanding of the topic, here are a few thoughts."
Will not knowing an answer to a question be a mark against you? Probably, in the grand scheme of things -- if it's something core I expect you to know based on the job description and what you say about your experience.  But, there are ways to introduce your answer so that it is obvious you're trying to add value even if you aren't (as opposed to just sounding like you're making stuff up to look good, which rarely works).
Comment: In a world with piles of resumes and where everybody thinks they know everything, I find it preferable to hear "I don't know.  I am not familiar with that."  It demonstrates honesty, humility, and self-awareness.
Comment: I agree with this answer.  If a candidate attempts to bluff his/her way through the interview, how do I know that he/she won't attempt to do the same thing when issues arise or when I'm asking for status?
Comment: @MirroredFate: I think some organisations (or just their HR departments) treat an interview like a formal academic examination. They would prefer you to say what you know and they might even prefer you to guess, and they give you no points for knowing how to find stuff out. But you can reasonably decide that you don't want particularly want to work for an organisation that sets out to hire employees who never admit their own ignorance.
Comment: I was in this situation once with regards to a bit of language semantics, and responded that, "I think it's approximately [whatever], but I would probably Google it to make sure." They didn't really like that as an answer- I'm still not sure why.
Answer: If you have absolutely no idea, I think you're better off admitting that than trying to bluff it and then getting caught. Of course, don't just leave your answer as "I dunno", tell them how you'd find out the answer, such as "I'd search Google for ${KEYWORD} to learn more about this subject / I'd consult a coworker who is more knowledgeable about this topic / whatever you do for research".
Comment: This is what I do too. *"I don't know the answer in this case, but this is how I'd figure it out."* This shows that even if you are presented with a situation where you don't know the answer, you are able to find the answer anyway.
Answer: In the case where you're not 100% sure of the correct answer, but you have some thoughts on the subject, I think it's good to try to convey how much you know.
In this situation I'd usually say something like,

"Well I'm unfamiliar with XXX but from my understanding it's similar
  to YYY which is..."

or maybe

"I'm don't have much experience with XXX but I think it behaves ...."

So, not making stuff up, but letting the interviewer know that you have a rough understanding of it.
In the case where you really don't know much about it, try explaining how you'd go about solving the problem. So something like,

"I'm not sure what would cause the behaviour you mentioned, because I
  don't have much experience in that area, but my first step would be to
  isolate the problem and then ..."

or something like that.
If you generally have no idea about something, I find it's best to say you don't know what that is, and ask about it. Show that you're genuinely interested in the piece of technology, then as they're explaining, ask how specific bits work.

"No, I'm unfamiliar with XXX. Where does that fit in the stack?"

and follow up with

"How has XXX worked with your organisation?"

or

"That's interesting, I'll have to check that out after the interview."

I think the most important thing is to keep your composure and be nice, open and genuine. If you're a good fit for the job, you'll get it. If you're not - you don't want it anyway.
Good luck!
Comment: If you don't know, you don't know. Rather than assuming X is similar to Y, I would be far happier if you answered, *"I don't know X, is it similar to Y?"* If the interviewer tells you yes, then it's fine to explain how it works in Y. What you don't want to do is tell them all about Y only to have the interviewer say afterwards, *"Actually, X is nothing like Y."*
Comment: Yeah, I'd agree with that. I guess my point was more, be honest and try to show what you know, rather than just saying I don't know. I meant, if you don't know X but do know it's like Y, discuss that. If you think it's might be like Y, ask and if it is, discuss Y. If it's not, discuss how you'd work out what it's about. If you have no idea, ask them about it.
Answer: 1 - Be honest.
Don't give a guess unless you are able to make an educated guess.  If you can qualify an educated with guess with why you think you might right, then explain and go for partial credit.  For example, I put on my resume of the protocols where I have enough expertise to be considered an expert.  I don't have every element of every protocol memorized, but if you threw out a question I could take an educated guess on what the answer might be because I know enough of the background to be able to rule out some options.  I can show subject matter expertise by explaining why I'm making this guess.
But if you've hit the point of having no idea at all, admit it.
2 - Have an idea of where you'd find the answer
It's easy to get blindsided even when asked simple facts during a case of interviewer nervousness.  Qualify your lack of knowledge with a thought on what you'd do to find the answer if this came up while you were on the job.
3 - Context matters
Interviewers may be quizzing you based on your resume.  If you are getting stumped by a term that is considered standard knowledge for someone with your resume qualifications, then this will look pretty bad.  It happens, sometimes the scope of a given technology is wide enough that you can work deeply in it and yet miss some pretty basic terms.  Prep for that with having a wider working knowledge of any hit words you list on your resume.
Simultaneously, the interviewer may just ask the first question that comes into his head that is vaguely related to your potential position.  I've done this - particularly when a nagging issue just came up on the team, and we were all stumped.  Not knowing the answer in these cases makes you no worse than most people, but you can distinguish yourself by having a reasonable sounding plan of action for learning what you don't know.  After all, in most engineering positions it's common knowledge that everyone will be learning new things all the time.
4 - Don't let it throw you
The worst case is being so thrown by the lack of answer that you stumble through the rest of the interview.  Take a breath, put it behind you.  It happens to everyone.
Answer: I would go with "I don't know, but my educated guess is as follows...". That way, you can still tell that you don't know, and avoid wasting their time. But at the same time, you can show - or try to show - that you are willing to learn, and have overall understanding of the issue. For example, in programming, you could tell briefly how same thing is done in different language.
If you have no idea about the answer, guessing is almost never better than admitting you don't know. They know it's dangerous to have colleague who just lies when he/she doesn't know the answer.
Comment: What if your guess isn't educated? Making assumptions on how something works when you're not sure is definitely not something that impresses me. I'd much rather know that someone will look something up if they don't know, or at least ask if they're honestly stuck.
Comment: Umm... That's exactly what I'm trying to say with "educated guess". If you're just guessing the assumptions, in my opinion, you shouldn't. If you have some knowledge - and thus, educated guess - you should tell the interviewee. Original question specifically states there's no time to look up things.
Comment: Thinking your guess is educated, and your guess actually being educated are two very different things. Yes, you don't have time to look it up during the interview, that doesn't mean you will be in a crisis center where if you don't know a technical detail with perfect recall there will be some horrid consequence. If you don't know, say you don't know, but explain what you would do to find out and/or ask if it is similar to what your educated guess would be. Shouldn't cause any issues (whereas assuming, even educatedly, may).
Comment: Thinking you know the answer and knowing the right answer are very different things too. That's just how it goes.
Answer: Strictly depends on the type of questions. Some of them are strictly technical (what is the name of X that makes Y in Z). When you don't know, just say you haven't to use such feature in the past or you memorize only the things you need on daily basis, because everything else you can find when needed. Such questions aren't good fit for phone interview, anyway, I would be very suspicious about company asking such questions, that can be easily googled, by phone.
Be careful, there are some tricky questions, where the recruiter doesn't test your personal persisted dataset in head, but instead tests your ability to deal with new situations. If this is the case, and you'll simply say you don't know, this would be a red light for them, because it means that if you don't know how to deal with something, you have an inclination to give up.
In each case, be honest, don't say you know something if you don't know. Always make it clear, you are trying to invent a solution. But never simply give up.
It's normal in work life to have new situation you can't deal with. You are expected to try hard to deal with them, and not give up because you don't know something.
Answer: In my experience (of knowing and not knowing the answers) it is best to say you don't know the answer and resolve to find out as soon as you put the phone down. Phone interviews save the potential employer a lot of time but it is better to retain a good relationship by not bluffing your way through.
Always keep a notepad with you for phone/video interviews and make sure you do your homework immediately afterwards.
After the first three or four interviews you will be better than at the first. You will have discovered gaps in your knowledge and have a better idea of what the market is demanding.
Good luck!
Answer: Some interview question and answers aren't designed to probe you for real information, but to put you on the spot and see how you respond. You will need to rely upon your wit and sense of humor to get through these questions without showing your sweat.
Comment: Hey Kimmy, this makes a lot of sense, but could you elaborate a little on some strategies for getting through such questions? This will help you get more upvotes and ensure your answer can reach the widest audience possible.
Answer: Just say, sorry I don't know answer to that question and the person on the other side will be fine because rapid fire question require rapid fire answer and usually such interviews are for screening people. If you waste their time they may get irritated.
If the interviewer insists that you still answer something then you can say, whatever you think might be the right answer to the question.


What makes a cancer contagious?

Question: Most human cancers are not (very?) contagious (perhaps besides a couple of incidents). But the Tasmanian devil seems to have a form of cancer which is contagious. Now what makes the difference between a contagious cancer and a non contagious cancer in the DNA mutations of a cell?
Answer: There are two relatively common contagious cancers: Tasmanian Devil Facial Tumor, and Canine Transmissible Venereal Tumor.  Both are truly contagious cancers, in that the cancer cells themselves are transmitted from one host to the next, and expand and cause disease in each successive host.  (There was also a contagious cancer of hamsters, which has long since gone extinct, and there are some transmissible tumors in clams and oysters; the latter don't have immune systems that are remotely similar to dogs, Devils, or humans.)
It's believed that one key aspect of the Devil Facial Tumor is that Tasmanian Devils are immunologically closely related.  Normally, cancer cells from one host would be a tissue graft in a different individual and would be rapidly rejected as with any allograft.  However, immunologically closely related individuals can tolerate each others' grafts, and it's believed that this is part of what allows the Devil tumor to spread -- a lack of genetic diversity among Tasmanian Devils.

Major histocompatibility complex class I and class II genes have extremely low levels of sequence divergence in the devil population from the Tasmanian east coast (Siddle et al., 2007a, 2007b). ... The lack of diversity at MHC loci, coupled with weak responses of east coast devils to allogeneic mixed lymphocyte culture, has led to the suggestion that this population may be functionally identical at MHC loci, thus permitting the spread of DFTD as an allograft.

--Clonally transmissible cancers in dogs and Tasmanian devils
The genetic diversity explanation is widely accepted, but it hasn't been formally proven and there are a number of points that suggest that it isn't the whole story.  There are several other molecular features of the tumor that probably make it less immunogenic (see the review The role of MHC genes in contagious cancer: the story of Tasmanian devils) and the full story probably involves a combination of these things.
CTVT is different.  It's astonishingly ancient (it apparently arose in a dog, or a wolf, 11,000 years ago and has been passed from dog to dog continuously since), so it's obviously very successful at what it does, but it's not at all understood how it does it. Dogs are genetically pretty diverse and definitely don't tolerate arbitrary grafts from each other, so that's not the explanation. Lots of other possible explanations have been put forward, most of which point to various immunological features of the tumor; however, while that's clearly an important point, none of the things people have implicated are unique to CTVT -- tumors invariably have immune suppressive abilities and don't have the same ability to spread. (Going back to the Devil tumors, the low expression of MHC molecules on the cancer cells is probably a factor there too, but it's important to understand that low MHC expression is almost universal among tumors, including the vast, vast majority that can't transmit.)
Summary:

There do exist a very small number of truly contagious cancers.
The reasons for their transmissibility are not fully understood.
Genetic diversity and immune evasion are probably two of the causes.
Comment: Thanks a lot. The reading is quite diverse and very informative (read abstracts, will read the rest slowly.)
Comment: Joined just to upvote, very elaborate and interesting answer.
Comment: Very nice answer.
Answer: Different mechanisms can explain why some cancers are contagious. They don't necessarily belong to the same category.
For instance, certain cancers, like the cervical cancer, can be caused by viruses (in that case, HPV). The cancer itself is not contagious, but the virus is. Other famous viruses that can cause cancer are HTLV-1, MCV, Herpes Virus 8 (or KSHV), HCV, HBV and EBV.
The case of the Tasmanian Devils is more complex. It was thought for some time that the same viral mechanism could explain the Devil Facial Tumour Disease, or DFTD, specially the fact that DFTD is contagious. However, there is no evidence (to date) of such a virus.
Thus, some alternative hypothesis have been proposed, such as environmental toxins.
However, the most accepted hypothesis nowadays is the Allograph hypothesis. According to the Save the Tasmanian Devil Program:

Trials are being held to examine the transmission of Devil Facial Tumour Disease. Preliminary results support the increasingly accepted hypothesis that we are dealing with a transmissible cancer and that cancerous cells are passed directly between devils as an allograft. Put more simply, we are getting more and more evidence to support the theory that DFTD is spread by the cancer cells themselves being passed from one animal to another. (emphasis mine)
Comment: There are two relatively common contagious cancers: Tasmanian Devil Facial Tumor, and [Transmissible Canine Venereal Tumor](http://onlinelibrary.wiley.com/doi/10.1111/vco.12060/abstract;jsessionid=5C62A9B0F26531A852CC12DA8D727E41.f04t03).  Both are truly contagious cancers, in that the cancer cells themselves are transmitted from one host to the next, and expand and cause disease in each successive host.  (There was also a contagious cancer of hamsters which has long since gone extinct.)
Comment: Yes, the Transmissible Canine Tumor is in the page I linked about the allographs. However, it's important to mention that the case is not closed for the TDFT: it's still a *hypothesis*.
Comment: What about immune system killing non-self cells?
Comment: *it's still a hypothesis* -- that's fair. My response was too long for a comment so I wrote another answer, basically to say I agree with you.  @roni-saiba the immune system killing non-self cells is that issue we raised in the comments
Comment: @iayork a good answer indeed.

What makes a cancer contagious?


Can Low speed shutter damage Camera in Bright light?

Question: Can low speed shutter like 20sec in "Bright Light Condition" Damage the Camera?
"Bright light condition" mean artificial lights and Indirect sunlight.
Just like a picture tooked in a bright room with 20sec shutter and the result is "one color white picture because high light!"
Comment: Can the sun damage a sensor? yes but can you give a bit more information, are you asking out of curiosity for an idea? why would you need to do this?
Comment: @saidh if it's just like a bulb, no, if it's something like the sun or laser yes, however, I'd wait for a better answer giving more detail.
Comment: @saidh can you give a bit more detail on what exactly is "bright light"
Comment: There's a big difference between taking a blown out, overexposed photo and damaging a sensor. What are you trying to figure out? If overexposure can cause damage?
Comment: Describe  "bright light conditions".  Are we talking about sunlight or artificial light?  If sunlight, where is the sun in relation to the camera?
Comment: Bright light condition mean artificial lights and Indirect sunlight.
Comment: @matthew ,My question  is about shutter speed. Long shutter in bright room can demage the camera?
Comment: I think this question would be better phrased: "How much energy is needed to damage a modern camera sensor? Can this amount of energy be created artificially?" - right now, it's very vague.
Answer: If you are talking about normal lighting conditions, then overexposing a photo that results in a totally white image will not damage a camera. After all, if there is any pure white in a scene, that spot on the sensor is totally saturated when properly exposed. Such an exposure does not damage the spot on the sensor that records the pure white, does it?
If you are using a mirrorless camera, other than the very brief times when the mechanical shutter closes/opens to expose the image/closes/reopens to continue Live View, the imaging sensor is exposed to light for the entire time the camera is turned on. Under very bright daylight conditions the camera is not damaged even after many minutes of continuous use. The same is true with shooting video. Even in very bright conditions the sensor is not damaged when exposed to light for several minutes or even hours.
Where you will get into problems is if an extremely bright direct light source, such as the sun or a powerful laser, is inside the camera's field of view. In that case it might not even take a long exposure to damage the camera. Lasers with enough power can damage a sensor almost instantly.
Damage from pointing the camera at the sun is usually heat related and takes a bit longer. Longer focal length lenses, which concentrate more of the sun's energy, can contribute to major damage:

With wider angle lenses and a camera with a mechanical shutter that covers the sensor at all times except when the image is actually exposed, it is possible to take images that contain the sun in the field of view without damaging the camera. Be very careful not to look directly at the sun in the viewfinder, though, as the sun can damage your eyes!
Answer: You are mixing few things together. First, take a look at the exposure triangle. What is shows is that amount of light hitting your sensor, depends on exposure and aperture. Smaller apertures (f-number 22) will let in less light. Longer exposure will let in more total amount of light.
Now, sensor can be damaged by very intense light, just like any material. Exposure is only part of equation, for example, you might be OK with 20 second exposure when aperture is very low. On the other hand, short exposure can let in enough light to damage the sensor when aperture is open.
From this question, it seems that if you shoot sun directly (or sun eclipse) at 1/4000 shutter speed and f22 aperture, you can actually damage your sensor. So don't do it.
What also is important is not just amount of light getting into camera, but how fast it gets there. In other words, your 20 second exposure with small aperture can get in a lot of light, but over longer period, allowing camera to cool down, hence lowering chance of damage. Damage to camera is a sum of heat in versus heat out.
Comment: @robin I guess you mean: you would have burning mirror before sensor is burning? You are right, in DSLR also your eye might be damaged before sensor. I quoted that Q because it points to one particular case
Comment: The question you referenced is specifically about mirrorless cameras. In a DSLR, sunlight would not be hitting the sensor until you open the shutter, so I don't think you would have to worry about any damage shooting at high speeds.
Comment: @Robin You wouldn't need to worry about damaging the sensor, but you could damage other parts of the camera with focal lengths typically used for   imaging objects only 1/2° of arc in width. And then there is Live View... [Can the sun damage the camera sensor? Under what conditions?](https://photo.stackexchange.com/a/91388/15871)
Comment: I burned the sensor on my old D70 while on holiday.
Luckily it would only show up on long exposures as a slight shadow.
Comment: @PhotoScientist i doubt calculations can be covered by NDA :) And since there were 36 solar eclipses in 21st century, there should be enough practical data to accurately set up photography
Comment: Sorry. I'll shut up.


What drove the Puy de Dôme volcano?

Question: The Puy de Dôme is an extinct volcano located pretty much smack in the middle of France. It last erupted some seven thousand years ago, which in geological terms is fairly recent - prehistoric humans might even have born witness to that eruption! What I'm wondering, though, is what drove this volcano, seeing as it is not located where tectonic plates meet? Was there a hot spot underneath central France that powered this volcano, and if so, could we witness future volcanic activity in this region?
Answer: According the an Oregon State website,

Volcanism far from the edges of tectonic plates, such as Chaine des
  Puys, is rare. Changes in the mantle may have led to volcanism at
  Chaine des Puys. Several lines of evidence indicate thinning of the
  crust and upwelling of the asthenosphere. The rising mantle "diapir"
  was probably a total of 30-60 miles (50-100 km) in diameter.

Chain des Puys is the 40km long chain of volcanic features to which Puy de Dome belongs. It sounds like the causes are not completely understood. Unfortunately, all the papers I could find on the topic are in French (understandably), so if you can read French you can try Google Scholar to see if there is more info there.

What drove the Puy de Dôme volcano?


Which risk-free interest rate to use in Black-Scholes equation

Question: Sorry but i'm new in quantitative finance. According to BS derivation the risk-free interest rate is the rate to wich the rate of a particular investment tends when the risk tends to zero. Suppose i want to buy on option with fixed strike price and maturity, which rate i have to put into the equation? And why?
Comment: If one of those answers were helpful it would be great if you could upvote and accept it - Thank you :-)
Answer:
In theory, $r$ is a short-term safe interest rate, and it is constant
  through time though the theory does goes through with $\bar{r}$ (average $r$
  from $t$ to $T$) in place or $r$. In practice, you take the
  continuously compounded yield on a T-bill of maturity closest to that
  of your option. Eurocurrency rates work too, especially for currency
  options. In theory, you should choose whether to use a LIBOR or LIBID
  rate depending upon whether the option dealer who delta hedges your
  trade is going to be borrowing money (at the LIBOR rate) or lending
  money (at the LIBID rate).

Source: Basic Black-Scholes: Option Pricing and Trading (2'nd edition) by Timothy Falcon Crack, p. 143.
Answer: Most option trades are collateralized.  In that case, the correct rate to use for discounting is the rate earned by the collateral, or a mix of the collateral rate and risk-free rate for partial collateralization.  You still need to pay attention that the stock forward level is priced correctly, so use a stock repo rate or similar backed out from call/put parity in the options market or data from futures or forwards.
See
http://www.math.columbia.edu/~fts/What%20Rate%20to%20use%20v1.pdf
Answer: If you are doing this for fun then use Treasury/LIBOR rates. Otherwise the 'risk-free' rate in BS is the rate at which you can borrow/lend cash. If you have a brokerage account the broker should pay you an interest on any cash in your account or charge you interest for lending you cash.
Answer: Conventionally you use the interest rate of a sovereign with same maturity, that is considered the virtually risk-free asset.
So for a call on AAPL (T = 6m), you would use 6m rate from t-bills and annualize it.
Comment: Thanks! If there are two or more sovereigns with same maturity but different rate which is the right one?
Comment: I would say that your example violates the no-arbitrage condition, which is a base assumption of BS model. Can you be more specific? Also I edited my answer as r must be expressed in annualized terms.
Comment: I was imagining something but actually it violates no arbitrage condition. Thank you again
Comment: Using the T-Bill rate has been quite standard for a long time (in fact it is what the old textbooks recommend). In recent years some financial institutions have begun to use the OIS rate of the applicable maturity, on the idea that it better approximates the funding rate of the financial institution.
Comment: Why does Treasury Bill make sense ? Theoretically speaking, isn't replicating portfolio approach require borrowing or lending? At the very least, the rate won't be the same because of bid/ask spread. More importantly, I cannot for sure borrow anything with the same rate as US Treasury.


Need Recommendation for Simple Audio Interfacing into Raspberry Pi

Question: I'm currently searching for a way to get 4 channels of audio from mic level (XLR input) into a Raspberry Pi. Either as a single interface device or one channel and use four of them.
It only has to be something simple as it will be built into a casing of a bigger product. Price is definitely a point. I'm looking for something in the sub 60$ range.
Ideally it would have an XLR input, Phantom Power (doesn't necessarily have to include that), gain and USB-Connection to the Raspberry built onto a circuit board.  But jack input would be fine as well.
Comment: Is your goal to have a small device which records sound? If yes, why not using an actual recorder (which would be smaller compared to a custom-made Raspberry Pi based one, and of a much higher quality)?
Comment: Not really. we are trying to start a web stream with RPI. Therefore we need an audio grabber or something similar.
Comment: By web stream, you mean like a live podcast?
Comment: Yes. We want to use it for a translation Service and live broadcast to other rooms
Comment: Why not buy a small mixing board? A decent desk will have XLR, phantom, gain, etc etc, and output to XLR or a 6.35 jack - which you can convert to a 3.5 and stick that into a line in
Comment: We want to install the device into an 19" Housing. A mixing board would be to big and to complicated for the translator
Comment: OK. Still not sure why something such as Zoom H6 wouldn't be a solution for you (or a similar lower grade model, possibly second hand, to bring the price below $60).
Comment: Because we want to convert the audio to a HTML Stream.  And we Cant do this with a simple recording device...
Answer: I would advise you against your own hardware for this task. The goal of Raspberry Pi is to be a small-size substitute for a PC, not a large-size substitute for a professional recorder.
Based on your comments, you have some quantity of XLR microphones—you weren't clear if it's two stereo microphones or four mono microphones—and you want to mix this sound and stream it to the web.
With a Raspberry Pi, you'll have three limitations:

Connectors. XLR connectors are quite specific, because of the constraints of audio signal transfer. While XLR to USB adapters and cables exist, it will have its negative consequences if you require quality sound, and it possibly won't have the features of standard XLR (possibly no phantom power).
The fact that you want to install it into a rack makes things worse, since you possibly won't be able to use USB connectors, and would require to make your own connectors, somehow. Unless you have experience with that, here again the audio quality will suffer.
Performance. Raspberry Pi is a nice and very capable machine, but if you want to process and stream sound in real time, it may quickly become a limiting factor.
Software. Things as simple as adjusting the levels of the individual microphones or visualizing the levels to check if they are set correctly would probably require either to develop a custom script or to install a custom software.

Instead, you may purchase either a mixing board, or grab an audio recorder. Zoom H6 could be a good idea; while it costs around $300, you may take in account that a Raspberry Pi, the XLR connectors and the custom rack enclosure won't be cheap either.
Another choice would be to use Zoom H5 with a EXH-6 Dual XLR/TRS combo capsule if you have four XLR microphones, or just the recorder without the additional capsule if you have only two stereo ones for about $160 used (or $210 new). Or you can look for older models, second hand, which may be found for a price below $60).
A few illustrations of Zoom H6:


Can you prepare eggplant by salting, then baking, then finally rinsing?

Question: In normal eggplant preparation, you salt and rinse first. However, when the eggplant is baked, it continues to release water. This leads me to believe that I could achieve a less bitter and tastier result by putting the eggplant in the oven on a rack with salt still on it, and letting the heat help drain it. Would that work?
Comment: @Joe Yep, experiment commencing in a few minutes. Salted and rinsed, salted and unrinsed, and unsalted. Camera and kitchen scale at the ready...WooHoo!
Comment: If you are really going to rinse it at the end, I think that will be your downfall... it will get soggy.
Comment: Hmmm...It's a good thing I read new questions before going to the grocery store.
Comment: This might be a good chance for an experiment -- and I'd add a third group that are rinsed both before & after baking, and maybe even a completely unsalted group.
Comment: @Jolenealaska : I'm more interested in taste ... if the heat does something to the drippings, either evaporating and making them stick, or breaking them down into something else, then waiting to rinse could be really, really nasty.
Comment: @Jolenealaska : and it might be worth comparing how much moisture is retained from rinsing vs. wiping off w/ paper towels.
Answer: I did the experiment complete with pictures, unfortunately I managed to to screw up the pictures, but luckily I took notes.
I started with two very similar eggplants, globe variety, Like this:

I sliced each of the eggplants into five slices of equal width, discarding the ends. I took one slice of each eggplant to make five pairs to treat differently as far as salting. I pre-salted three of the pairs and drained them for one-half hour prior to baking. One of those pairs was rinsed and dried before baking, another pair was not rinsed - just thoroughly dried with a paper towel prior to baking. The third pair was left salted for baking. The fourth pair was salted (not rinsed) just before baking. The fifth pair was left unsalted.
I baked all of the slices at 400F for 90 minutes, until they were just about done. At that point I rinsed one slice of each pair and returned all of the eggplant to the 400F oven for 10 more minutes.
I weighed each of the pairs at the beginning and end of the experiment.
After allowing the eggplant to come to "eating temperature", I invited a friend to join me in the tasting. We concurred 100% as to the palatability of each slice. Here are the results:

So, bottom line, at least for this variety of eggplant, pre-salting and draining is an unnecessary step, although rinsing is necessary. Rinsing can be done after pre-salting and draining, before baking, or the eggplant can be rinsed at the end of baking. The difference in weight loss is negligible. Unfortunately, I wasn't really able to gauge "bitterness", because the eggplant wasn't bitter to begin with.
Based on this experiment, if I were to bake something like an Eggplant Parmesan (unbreaded), I would salt the eggplant just before baking, rinse when the eggplant is nearly done, sauce, then continue baking until the final dish is done, cheese melted and slightly browned. As per Joe's comment below, breading would be a different ball of wax, but I would certainly consider par-baking the salted eggplant to eliminate the draining step, rinsing is really necessary either way. A few minutes in the oven after rinsing the par-baked eggplant would give you an ideal slice, ready to bread. As a matter of fact, I'm not crazy about eggplant, but my friend is. I'll update this answer in a few days with the results of modifying Eggplant Parmesan by par-baking the salted slices prior to breading instead of draining the salted eggplant then breading. I suspect the prior method will produce better results in the same amount of time with less sogginess of the breading, as the moisture loss continues during the cooking of the pre-salted and drained eggplant. For that continuation of the experiment I will make two separate casseroles, and weigh both the par-baked eggplant and salted and drained eggplant prior to breading.
Comment: After the question was initially asked, I did some reading, and the bitterness had been bred out of your standard grocery store eggplant.  We might need to repeat w/ some heirloom varieties.  (And possibly add another variable -- the sex of the eggplant)
Comment: and re: your eggplant parmesan suggestion ... I take it you don't bread yours, then.


unable to upgrade to ubuntu 12.4 for Dell Vosto V131

Question: I am running Ubuntu 11.10 on Vosto V131 and not able to upgrade to 12.4. I tried several times to do it through 'Update Manager' but failed. I tried from a terminal using: sudo apt-get update && sudo apt-get upgrade then do-release-upgrade and got the following error:

authenticate 'precise.tar.gz' against 'precise.tar.gz.gpg'
exception from gpg: GnuPG exited non-zero, with code 2
Debug information:
gpg: Signature made Fri 20 Apr 2012 01:49:33 PM EDT using DSA key ID 437D05B5
gpg: can't open `/etc/apt/trusted.gpg'
gpg: keydb_search failed: file open error
gpg: Can't check signature: public key not found
Authentication failed
Authenticating the upgrade failed. There may be a problem with the network or with the server.
any idea how to handle it?
Answer: Fix permission on the file and it will work
<code>sudo chmod 644 /etc/apt/trusted.gpg
</code>


Epson Stylus SX235W with Ubuntu 12.04 - Scanner not recognised

Question: I'm setting up a new computer running Ubuntu 12.04 and am having trouble getting the scanner on my Epson Stylus SX235W All-in-one to be recognised. I would like to be able to use the 'Image Scan! For Linux' program. The device is connected via usb.
I installed the relevant .deb files from the Epson Download Center for Image Scan!, namely
iscan-data_1.24.0-2_all.deb
iscan_2.29.2-1-usb0.1ltdl7_i386.deb
and installed them in that order, but the program wouldn't load.
An internet search suggested downloading the libsane-extras package and editing the /etc/sane.d/dll.conf file so that the relevant driver was uncommented in the list, which I did but to no effect.
I tried uncommenting the following lines
epson
epson2
I also tried to force libsane to use the scanner by adding the number obtained from a 'lsusb' terminal command (Bus 003 Device 012: ID 04b8:0885 Seiko Epson Corp) in this form
usb 0x04b8 0x0885
to the epson.conf file but nothing happened. Beyond this I don't really know what I'm doing so any help would be greatly appreciated.
Thanks very much.
Answer: The information at -
Epson Scanner sx218 - Works Intermittently
may help. The /etc/sane.d/dll.conf and /etc/sane.d/epkowa.conf had the correct entries when the .deb packages were installed.


Where can I obtain cream without additives?

Question: Until a few years ago, with only a little effort, I could find whipping cream and heavy cream without carrageenan and other undesirable ingredients in grocery stores. Now my source has dried up. How can I obtain cream that consists of nothing but cream? I typically only need small amounts and not all that frequently. I don't imagine I can just drive up to a dairy, knock the secret knock and whisper "psssst...where do you keep the good stuff?"
Comment: Are you in the US, UK or elsewhere?
Comment: You should mention to the grocery stores that it's something you'd like to buy because if enough customers indicate an interest, that demand can cause responsive stores to carry a product.  In much of Europe, whipping cream only contains one ingredient: cream.  I've noticed that it has shifted in Canada as well, with many brands, adulterating their creams.  In the Netherlands, none of the whipping cream brands in the grocery store appear to have any additives.
Comment: @Bluebelle: Sorry, I meant to say that I'm in the US. Thanks for reminding me.
Comment: Move to another country that hasn't lost the plot!
Answer: Looking for a farmers market is a good way to find fresh possibly additive-free dairy, or to find recommendations on where to get fresh additive-free dairy. Just talk to the vendors. Most know more about the bad side of additives and hormones than us and look very diligently to avoid them.
Comment: Yes, many local dairy farms will have "raw" milk and other products (and most local dairy farmers will not use hormones, etc). They may not sell them at the Farmer's Markets, but usually you can order a la carte.
Comment: We have one dairy vendor at ours (in Downtown Columbus, OH) that sells fresh cheese products that are additive-free and from hormone-free cows. That said, I have not seen cream at his booth.
Comment: Be careful. In some states like [Florida](http://www.realmilk.com/milk-laws-1.html#fl) raw milk is illegal to sell. Saw a story about it on the news once.
Comment: @Zan true, "the federal government has  not established any mandatory national safety standards for Grade A milk; no national law even regulates the sale of raw unpasteurized milk.
That has been left up to states and localities, which are best  equipped to regulate, monitor and inspect the local dairy industry and respond to local reports of adulterated milk" (http://www.uspirg.org 2006).
Answer: You might check with localharvest.org and find a CSA (Community Supported Agriculture) farm in your area. That is if you live in the U.S. Not sure if this type of thing is available in other countries, but I wouldn't be surprised if it is in some form.
The local harvest website has a search form where you can type in your zip code to look for CSA farms in your area.
Also, in my area I can get cream at natural foods groceries and at food co-ops. So you might check on those options in your area.
Answer: Organic Valley Heavy Whipping Cream (NOT the Ultra). I had to get my local health food store to special order me some, but they were very nice about it. I used one right away, then froze the rest. I've read frozen cream doesn't whip good, but I'm using it mostly for sauce anyway.
BTW, I found Organic Valley by doing a label search for heavy creams. Organic Valley was the ONLY one I could find without carrageenan.
Answer: Skim the cream off the top from the fresh raw milk you buy from a local farmer. I know it isn't as convenient as going to the store, but getting to know some real farmers can lead to other sources of good fresh products, like eggs, and grass fed chickens/ beef. If you buy in bulk, it can be cheaper, too.
You kinda have to network a bit. I am sorry it isn't easier, but the food chain in our 'modern' western world is seriously compromised.


Input field with icon and placeholder as label

Question:
I was prototyping some inputs for a product I plan to develop and was wondering about the bad practice issue envolving the use of placeholders as labels. My question is: with the use of an icon altogether, can I achieve a better result with better affordance? Can a icon, along with a placeholder, replace the label in the context of a form? I also made two others labeled examples (first one and last one) hopping that you guys could help me to understand which one would be better, keeping in mind that I seek cleaness on my design (not willing to lose affordance for that, though). Thanks
Comment: Can you add some description of the interaction? "Placeholders" usually go away when the cursor enters the field, which means they are gone when they are needed most. Do you plan to remove the text and/or label in your designs as well (second one seems so, third one does not - would be my expectation).
Answer: This is not a widespread pattern because, what would happen when you have input fields with labels that don't have a clear icon associated with it?
Since you're working with a form for a product, you're going to encounter fields that are rather abstract. Fields like, how to address someone (sir/ma'm), initials, first and last name and so on. These are very difficult to visualise in an icon, because they have no tangible real-life equivalent.
Having distinct labels is important, even if it makes the design 'less clean'. This is simply because users tend to look specifically for labels. They scan for them. Placeholders may appear to function the same, but many users will initially overlook them. It can be mistaken for pre-filled inputs and can be less noticable than a blank space. So, to be on the safe side, include proper labeling and avoid users having to do double takes to find what they're looking for.
Clean design is nice, but your main priority with product forms is conversion: completion rates
Your form needs to become low-entry, and if you desire complex information, you need to make it as accessible as possible. Completion rates are important for the business, the feel-good about the ease of use is important to your users.
Only ask what is required

Try to minimize the number of fields as much as possible. This makes
  your form less loaded, especially when you request a lot of
  information from your users.

Focus on adding scannability

If you want users to scan out a form fast, put your labels above each
  field. This layout is easier to scan as the eyes move straight down
  the page. However if you want your users to read carefully, put the
  labels to the left of the fields.

Group Related Information

You should group related information in logical blocks or sets. The flow from one set of questions to the next will better resemble a conversation. Grouping related fields together also helps users make sense of the information that they must fill in.

Labels organise and bring clarity to your form. This is why they're such a big  help to users, even if from a designer perspective they may look a bit old-fashioned and limiting for your visual design.