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8:00 PM
@BernardMeurer your mistake was not making it an MPI joke
 
@AndrasDeak, I think it'll be fine
 
@heather No, seems like that's not public domain. Let me check further
 
@BernardMeurer, oh, okay, thanks
 
Anonymous
@heather I found that image on several websites...it is public..ceocoachrobinson.com/wp-content/uploads/2009/10/…
 
Anonymous
 
8:02 PM
@S007, okay, that's good
 
@Secret So, in a way $a$ replaces the role of $0$ in usual semirings?
 
probably some stock photo (originally?)
 
@heather Yes, it's public
 
at least in the annihilation aspect in multiplication
 
Couldn't find it on any stock sites for sale, nor could I find a version with a watermark
 
8:02 PM
@S007 That it's "public" in the sense of being found on several websites doesn't tell you anything about its copyright, you need to find the original source and the copyright it's licensed under to be sure.
 
well this is physics, we can round down to 0 ;D
 
@ACuriousMind Good luck, your google foo is better than mine, I just tried and failed
 
Anonymous
@ACuriousMind I could trace it's original source...any idea how to ?
 
@S007 Reverse search image
 
@Obliv yeah (except wth the additional property it is additive absorbing (but that's just's a convenient choice While the + cayley table is heavily constrained by the * cayleytable, a is not being constrainted by them). Since a is a two sided aobsorber, it has no inverses as expected. The point however is that the additive ientity 0 has a one sided multiplicative inverse, thus it is a legitmate division by zero
 
8:04 PM
Thank you everyone for your help, I think I need to learn to google foo =P
 
Well, I didn't say it's possible/easy, I just pointed out that being on several websites doesn't necessarily mean it's public domain
 
@heather You're still young, googling is harder than physics
@ACuriousMind Lack of a watermarked version is a strong indication though
Together with widespread usage
 
@heather google-fu as in kung-fu:P
@BernardMeurer no, widespread usage doesn't count, that's ACM's point
winrar anybody?:D
 
@AndrasDeak It doesn't imply public domain, but it points towards
Specially when they aren't watermarked
@AndrasDeak 7-Zip
 
seriously, though, does it look alright?
 
Anonymous
8:09 PM
I don't think we can be legally accused for using the image...as there is no watermark ...that is a very strong indicator
 
@heather I like it, the kid looks gravely constipated though
 
@S007 It is very unlikely that someone will care, but lack of a watermark doesn't actually prove anything about copyright either.
 
@BernardMeurer, I'm glad you like it, but, um, constipated?!
@JohnRennie, hello
 
@heather It looks good, but I'm not sure it will attract the right crowd.
 
@S007 a lot of people on Stack Overflow are very consciously aware of licensing. That's why I asked in the first place, it's marginally on my radar
 
8:11 PM
@heather As you get older you will become familiar with that term, ask @JohnRennie
 
That is, you'll attract people who have issues with homework, but does that ad speak to people who want to answer questions?
 
@BernardMeurer, gosh, I know what it means I just don't think the kid looks constipated.
 
@ACuriousMind: Jesus or Rasputin? :-)
 
@ACuriousMind, hmm...good point
 
Anonymous
@ACuriousMind I agree with you on this
 
8:12 PM
@JohnRennie Heh. Durance.
 
@heather No, no, you know what it's definition is. The meaning will come with the pain
 
something something lots of fibers
 
@JohnRennie Jasputin
 
@BernardMeurer, um, let's move on from this strange conversation, shall we?
 
@AndrasDeak The fibers are a lie
@heather All my conversations are weird
 
8:13 PM
okay:P
@heather welcome to TMI Land
 
Anonymous
@heather I think ACM is right about not attracting the right crowd
 
@AndrasDeak, no kidding
 
most of the people here are regulars, right? (ha ha...)
 
Anonymous
@heather Should we rethink the ad ?
 
@S007, I'm not sure how to fix this. Should we do two ads? Should we keep the background image and change the text? I have no idea.
 
8:14 PM
have you pinned down scope by now?:D
 
Anonymous
@heather I don't think people who answer graduate level physics will be attracted by the ad
 
@AndrasDeak, yeah, see this
@S007, also true
 
cool, thanks
 
Anonymous
Yeah...i suggest do some more ads
 
@S007, but I mean, isn't multiple ads a bit much?
 
8:16 PM
@AndrasDeak I could make a joke about my intestines, but I won't because I'm in the first world now
 
user116211
@JohnRennie You okay?
 
Anonymous
@heather No, i mean prepare a few more ads...we can decide tomorrow
 
Anonymous
If you get time that is
 
@S007, prepare some other drafts, yeah, sure. I've got time.
@S007, how about we go back to the problem solving room and discuss some ideas, so I can start creating a couple.
 
Anonymous
@heather can we do it tomorrow...i'm sleepy
 
Anonymous
8:17 PM
:-P
 
@heather It may well be that posting multiple ads to the community ads thread will make people think you're trying to hog the ad space and vote you down.
 
@S007, alright, sure...have a good night. I'll think of a few ideas.
 
Anonymous
@heather good luck and bbye
 
@ACuriousMind Is right, I wouldn't liek someone with 2 ads
 
@ACuriousMind, yeah, @S007 was just saying to create a few and then we can pick one. I definitely don't think posting two would be good
@S007, good night
 
8:20 PM
Someone bested me lol
 
umm...great job?
 
that is fabulous
 
@heather the man is a genius isn't he?
 
I would say that the girl should surely love that since they're the guy's girlfriend, but then again "My girlfriend always complains that I don't care about what she's doing, I don't like her post on Instagram / Wechat / Weibo... and I don't comment on her posts, bla bla bla." seems to contradict this
I guess there's no real reason why a nerdophile girl wouldn't want to be followed on social media
 
@AndrasDeak Maybe she's not a nerdophile
 
8:22 PM
yeah right
> So I build this. Although now she knows that I'm using this to like her post. But she's pretty happy about it (don't ask me why) and never complained again. So I'm very happy with this tool.
 
@AndrasDeak Also "nerdophile" sounds awfully cannibalistic
 
no, that's nerdophage:P
 
@AndrasDeak Dude, it's like if my GF built me a machine that congratulates me for building the kernel correctly
Heck, I'd love that shit, right now I rely on @DanielSank to call me a scrub
 
Congrats on building the kernel correctly!
 
@heather Now make that a bot :p
It needs to run integrated to my EXT4 driver so it KNOWS when the binaries show up :P
or on the TTY driver, your pick
(Please don't attempt that, you'll end up like me)
 
8:26 PM
@BernardMeurer, oh boy. Sounds kind of...fun, actually. =D
Though I have no idea how to do it.
 
@heather I didn't know how to run a single Linux command 3 years ago
 
@mafia do you know if jackson/tong's notes covers the photoelectric effect (at least at the very end)?
 
@BernardMeurer, I could maybe switch between directories, but otherwise don't give me a linux command line =)
 
also, I have barely any clue on how to modify the EXT driver, that shit is evil code
@heather There's a Linux Command line book on that folder
 
8:28 PM
hmm, so how would I start this program...let's see, it would have to check if the kernel compiles, and if it does print a message?
 
You need to get Linux
 
I wish
but me even using this chromebook is kind of an accident =P
 
@heather Dude talk to mr heather Senior :P
Say you need it for world domination
Parent's love it when you're ambitious
(Don't do that you'll get grounded)
 
@BernardMeurer, my dad? haha. believe me, I've already tried asking for computers and stuff and barely escaped madness. so. actually, wait...
would a raspberry pi do the trick? Because my dad has a few. and I might be able to borrow one.
=D
 
@heather YES!
 
8:30 PM
Oh dear
 
@BernardMeurer, YES!!!! Okay, I'll use that, and try not to break it =P
 
We could SSH into it, you wouldn't have a DE but WHO NEEDS GRAPHICS
@heather Do you have potatoes?
 
He'll soon recruit you to work on the potato army
 
Actually, I have a google app on this thing that can tight VZN into the raspberry pi
 
Called it.
 
8:31 PM
wait, wait, potatoes?
 
@ACuriousMind I'm faster than you
 
I mean, I had french fries for lunch but I have a feeling that's not what you're talking about...
 
@heather tight VZN? I'm not sure you're old enough to see that. Do you mean tight VPN? :P
@heather In 2 years you will be able to run a computer running off of a potato, it's my baby project right now
 
@BernardMeurer, actually, it might be tight VNC. I'm not even going to be ask about the thing I mis-said.
 
But I haven't had time to work on it, I need to eat my potatoes because college
@heather AH
You are right
 
8:33 PM
Wait, so you were talking about literal potatoes!? I mean, I've heard about a potato clock, but I'm pretty sure there's not enough in there for a computer...
 
jesus, I hadn't heard that name in so long
@heather Yes. Using a low power ARM cpu, with minimal memory and a very minimal OS
Chain-linking potatoes for some extra juice
 
why? what is the point when there is this wonderful device called a power supply?
 
@heather Why climb the Everest?
Because it's there!
Also, because it's badass
It's good bar talk too, trust me, Slovenians LOVE it
 
@BernardMeurer, alright, but just an fyi, i have no wish to climb everest, potato computers sound much better =P
 
@ACuriousMind On this note, Slovenian blueberry mystery moonshine is awesome
 
8:36 PM
though i do rock climb, just not on mountains
 
@heather The only rock I climb is the hill my building is on
 
I'm not sure I'd drink something called 'mystery moonshine'
 
And by climb I mean walk
And by walk I mean take the bus
 
@BernardMeurer, it's actually really fun (to climb, I mean, not take the bus)
 
@Obliv Man, you really should, those slovenians know their shit. Very tasty
I'm trying to get some, my neighbour's mom makes it in her basement
 
8:39 PM
I wonder what it'd be like to live in your shoes for a day @bernard ...
 
@BernardMeurer lol
 
@Obliv Meh, it's all spinning around 90% of the time
 
@BernardMeurer, I don't believe I ever did thank you for the books. But even if I did, I'll say again, many thanks for the books!
 
@heather No problems, make good use of the material and I'll be happy
Also, never take drinks from strangers, unless their slovenian
 
wasn't planning on it (the taking drinks from strangers part)
 
8:45 PM
@ACuriousMind Did I tell you I got married?
 
nope
 
@BernardMeurer, congrats!
 
@heather I'm 99% sure he's joking :P
 
@heather no, no, it wasn't voluntary
 
I'm just waiting for the punchline
 
8:46 PM
There is none
I got drunk and married a girl, the priest was a literal hobo
 
lol
Did you at least know the girl? :P
 
She lives in my building, we had just met
She calls me husband now
She invited me for tea lol
 
must have been some party
wait.. don't you have a GF already?
 
@Obliv That's like the speed of an object
relative
 
@bernard I don't follow
 
8:48 PM
Umm...how was it not voluntary? Did Father Hobo hold the shotgun?
 
if you're drunk, it's like 50% your conscious choices @andras i assume
 
"Measurement of deformation in rolling and sliding contacts"...hmmm, why did I download this?
Should've cleaned my download folder more regularly
 
Okay, new community ad idea, how bad is this:
seems more oriented for graduate students and such
 
rob
@heather Sounds like the tagline for a car commercial :-)
 
that seems to convey "help vampires, don't come near" to me, good job:P
 
9:00 PM
@rob, yeah, I'm good at coming up with cheesy slogans =P
@AndrasDeak, not sure if you're serious or not =)
 
I am, if I were a clueless help vampire (the kind which you surely don't want to attract to any healthy site), I'd be put off by all that text on the blackboard. That seems to say "work" which I would not like to do
 
@acuriousmind I still have your CFT notes sitting in my gmail in case I ever need to learn constructive fermionic field theory I'll look back at those with your permission 8^)
 
@Obliv I have no recollection of sending those to you, but I don't see why you'd need my permission to read them either
 
@AndrasDeak, okay, that's good
 
@Obliv what?
@ACuriousMind Why didn't I get your CFT notes?
 
9:04 PM
@ACuriousMind, less specific to younger question askers, you think?
 
You told you don't have CFT notes
 
@acuriousmind You were trying to link something else one day. I'll try to find it in the transcript
 
@0celo7 I'm pretty sure those are just my handwritten notes and I also don't recall sending them to anyone, as I said
@Obliv ah, lol
 
@ACuriousMind Why didn't you tell me about them though
what the hell is constructive field theory, anyway
 
9:06 PM
@heather Yes, the picture change is good. I'm not sold on the slogan, though, I'm not sure that I'm trying to "go" anywhere when I'm stuck on an exercises.
 
I'm trying to go to sleep usually.
 
@0celo7 Tell you about what?
 
@ACuriousMind, also a fair point. Hmm, what about "Helping you take it one problem at a time"? Also cheesy, I know.
 
I have handwritten notes from all my courses, I don't consider that worthy of mention
 
@ACuriousMind I misread. I never asked about constructive field theory.
What is it?
 
9:07 PM
"We do your homework."
2
 
Please do my homework
 
@MetaEd, that phrase implies that?
Yeah, you're probably right.
 
@0celo7 It's the rigorous functional integral approach to QFT, basically
I think
I only took this one course on it :D
 
it must be real constructive:P
 
@heather Oh, I was just suggesting a slogan that would get lots of attention.
 
9:09 PM
Though in a broader sense I guess it might refer to any rigorous attempt to construct a quantum field theory
 
And hopefully a slogan that isn't too far removed from what's being advertised.
 
@MetaEd, not really what's being advertised, but alright.
 
@ACuriousMind Your quantum field theory can either be rigorous, or unified, but not both at the same time.
 
@ACuriousMind what did you do in it?
 
@0celo7 We developed the machinery necessary to construct 2D and 3D theories of fermions
Fermions are easier than bosons in some sense because the $\theta^2 = 0$ of Graßmann variables makes some things finite that would otherwise be infinite series
@MetaEd Huh? I'd be happy already if you can hand me a rigorous version of the non-unified Standard Model
 
9:12 PM
Ok using the sharp s is just pretentious
 
@ACuriousMind I think it's courteous to ask regardless of the answer, since you posted them on accident anyway.
 
@ACuriousMind Me too.
And yes, given my level of physics study, that is an AOL "me too".
 
If I accidentally post pictures of my hemorrhoids, you don't need permission to look @Obliv
 
Hmm, or maybe "Problem solving techniques in physics" but that's a tad impersonal. I also kind of want to make it funny like the first one. This is kind of maddening.
 
That's great @0celo7 thanks :) but what about those pictures of you in yoga pants? Do I have permission for those too?
 
9:16 PM
@MetaEd I'm afraid I don't know what an AOL "me too" is
 
@ACuriousMind Age of Legends.
 
I thought this, TV Tropes warning
 
rob
Hey @0celo7, your profile suggests you're at my alma mater.
 
@rob UTK?
 
@AndrasDeak Oh, well, I'm too young to remember that, I guess
 
rob
9:19 PM
@0celo7 Two degrees and a spouse. Good times
 
Cool!
Remember any profs?
 
rob
I'm still collaborating with some of the symmetries folks.
Physics, not engineering, though.
 
I know
Who are the symmetry people?
whatever that means
 
@ACuriousMind You're too young, I suppose.
 
that's what he said:P
 
rob
9:28 PM
most of these guys are old friends, but especially the neutron folks.
 
@rob I work in a lab specializing in radiation damage, and we use neutrons a lot
 
rob
@0celo7 Do you have some D-T source on campus, or do you get to go to SNS?
 
neutrons are fun when they're not trying to kill you
 
rob
@AndrasDeak Neutrons are slippery little bastards who don't care about you or what you want. They are fun, though.
 
@rob Or HFIR, yeah.
 
9:32 PM
@rob yeah I've seen some neutron-optics elements intended to focus/guide thermal neutrons, I think. Pretty weird notion
 
rob
Cool. My thesis experiment ran out of neutrons at LANSCE. I started designing a beamline for it at HFIR but that fell through. It ended up at SNS.
 
What were you doing that LANL was interested?
I'm currently working on weaponized alloy surrogates, so I'm hoping to go out there next semester and actually work with the stuff
Apparently that's in the realm of possibility
 
rob
LANL had a neutron user facility like SNS, and like SNS it had mostly condensed-matter instruments but a couple of cold beamlines for nuclear physicists.
 
If you wanted cold neutrons, why not HFIR from the beginning?
 
rob
After SNS became operational the external funding for LANSCE shifted away from there ... the user program still exists but the operational schedule is spotty.
@0celo7 Pulsed beam. Plus some history.
 
9:37 PM
@rob You mean you wanted a pulsed beam?
 
rob
@0celo7 Yes. Integrated flux is about the same at HFIR and SNS, but to pulse the beam at HFIR you have to insert a chopper and throw away most of the neutrons.
I think the original proposal for my thesis experiment might have predated the cold guide hall at HFIR --- I don't know its whole history very well. I know that the beamline we considered using got snapped up by somebody else.
 
How long has SNS been open?
 
rob
First beam in 2009 or so
 
I didn't even know what a neutron was back then
 
rob
I'm getting old ... it feels recent.
 
9:45 PM
before too long you'll need dentures
@rob Did you know Haidong or is he after your time?
He's condensed matter experiment, so not your area.
 
rob
The condensed matter group is huge, active, and seems to have a fairly high turnover.
 
@rob Did you interact with anyone in NE?
 
rob
@0celo7 Very rarely. I don't remember any faculty's names.
 
@ACuriousMind Would you believe $$\sup_{x\in A}f(x)-\inf_{x\in A}f(x)=\sup_{x,y\in A}|f(x)-f(y)|?$$
 
According to [this](https://arxiv.org/abs/quant-ph/9701019) paper,
"If we wish to simulate the $n$-particle Schrodinger equation in d dimensions, one approach is to discretize space. If we discretize so that the particles move on a spatial lattice with $l$ lattice sites in each direction, the number of independent components of the $n$-particle wavefunction grows as $l^{dn}$. Even for $d = 3$, for reasonably large values of $l$ and $n$ this number becomes extremely large. If we wish to simulate the system on a classical computer, the number of independent components in the wavefunction is a
 
9:54 PM
@heather tip: link to abstracts, not PDFs
 
@DavidZ, ah, okay, thank you.
 
Always link to PDFs so it takes longer to load. In the time you waste while the thing is loading, prove a theorem of analysis
After 150 papers you will be Rudin
 
uh...
I don't think that's how it works.
 
@0celo7 yes
 
But anyway, my question related to that was what the "lattice" was here.
 
9:56 PM
@ACuriousMind good!
 
@heather a discretized mesh
you want to solve a differentail equation numerically, you need a mesh -> they call it a spatial lattice
 
@heather The "lattice" of the points where the particles are allowed to be. When you "discretize" space for a simulation, you only allow the particles to be in spots separated by a certain (often fixed) distance.
 
well not entirely, they discretize configurational space itself for the particles
 
@AndrasDeak, oh...and then what does the number assigned to the lattice size $l$ mean?
@ACuriousMind, oh, okay. And does $l$ in this case signify the length of that distance?
 
@heather "as much as you can". The better the discretization, the more valid/stable/etc. the approximation
from context, I'd say $l$ is the number of valid sites along 1 dimension
 
9:58 PM
@heather They say it in the second sentence you cited: "$l$ lattice sites in each direction"
 
@ACuriousMind, and a lattice site is a point that the particle is allowed to rest upon?
 
also, the above quote justifies the existence of solid state physics
 
That is, l is the maximum number of spots you can travel in any one direction before you hit the boundary
@heather yes
 
@ACuriousMind weeeellll
 
okay, I think that makes sense.
 
9:59 PM
where does a particle rest in terms of Schrodinger's?
 
So the larger $l$ is, the more realistic the simulation?
 
Although "rest" might not be correct, it's just a spot where it's allowed to be - whether it's moving or resting is irrelevant
 
I think it's just a fancy way of saying that $\psi(\vec r)\rightarrow \psi(\vec r_i)$
that's discretization of a PDE
 
@heather In general, one hopes that in the limit $l\to\infty$ and simultaneously $\Delta x \to 0$ (where $\Delta x$ is the spacing of the allowed spots) one recovers the original continuum theory
 
except singularities:P
 
10:01 PM
In some cases one can prove that, in others we don't know whether it's true, and in others again we know it fails
 
@ACuriousMind, so, yes? Ignoring the complicated bits, I mean?
 
but if you remove the appropriate amount of infinities...
 
@heather ehhh. Okay, yes ;)
 
what is the symbol << (where one of the signs is "inside" the other)?
 
much smaller than?
 
10:04 PM
"much smaller than"
 
\ll
$\ll$
 
$\ll$
much smaller than, okay
thank you
 
no worries
 
@heather $\subsubset$ is nice too
never mind :)
@ACuriousMind ?
I swear that's what it is
 
is that a thing?
maybe not amsmath
 
10:06 PM
Yes it is, ACM knows what it is.
 
so, it says in the next part that as long as $n \ll l^d$ the "memory and computational requirements per time step" are described by $l^d$
 
@0celo7 Do you mean the symbol for "compactly contained"? No idea what its TeX code is, I never use it
 
and before the requirements per time step were described by $l^{nd}$
 
@ACuriousMind How do you not use it for rigorous QFT?
 
@0celo7 I obviously use compact sets from time to time. I just don't like that symbol for it
 
10:07 PM
but I don't quite understand the units here. What is meant by the "memory and computational requirements per time step"? Is this supposed to be thought of as bits/qubits, or what?
 
@ACuriousMind what do you use?
 
@0celo7 my words
 
How do I get my theorem boxes to end on the correct line
when I have an equation \[ \] it puts the damn box on the next line
 
Yes, because an equation is automatically followed by a line break.
 
Can I fix that?
 
10:09 PM
@heather You may think of it as bits, but it doesn't really matter - whatever it is you use to describe a single lattice point, you need $l^d$ times that to describe the whole lattice
 
@heather $\psi(\vec r_1, \vec r_2, \dotsc \vec r_n) \rightarrow \psi(\vec r_{1,i_1}, \vec r_{2,i_2}, \dotsc, \vec r_{n,i_n})$
each particle needs $l^d$ number of $d$-dimensional vectors as configurational space
 
@0celo7 Probably, but probably not easily. I'm sure someone at TeX - LaTeX can hack together a solution
 
that means that the wave function alone has $(l^d)^n=l^{nd}$ independent components
 
@ACuriousMind, I guess the reason I'm curious is because I'm wondering if we are saying that for an arbitrary system where $n$ is much smaller than $l^d$ the number of bits it requires to simulate the system is $l^{dn}$ and the number of qubits is $l^d$, or basically a not insignificantly smaller number.
So that it is proven quantum computers are faster than classical computers in that aspect of simulation, I mean.
 
I've always been sceptical with such speed comparison claims, considering that the algorithms running on the two kinds of computers don't really compare. Right?
 
10:13 PM
@AndrasDeak, it is about the speed of solving the problem.
 
it probably matters that I'm not a CS nor quantum info guy
 
Not necessarily about the algorithms used. If the fastest algorithm on a classical computer takes some amount of time, and there is an algorithm that can be run on a quantum computer that is faster than that, well, quantum computers are faster than classical computers at something.
 
yes
 
rob
@heather Yes, but there's wall time and algorithmic complexity time.
If I have a gigahertz classical processor, and my quantum computer requires flipping some spins using long-ish pulses of megahertz microwaves, there has to be a lot of complexity speedup before the quantum computer has faster wall time.
 
@rob, right
 
10:30 PM
 
I <3 xkcd
 
What is the purpose of having a power supply in a photoelectric effect setup? Aren't you just concerned with the current induced by the cathode from the incoming photoelectrons (then you can derive the voltage)?
 
@Obliv isn't that power supply between anode and cathode?
if you just shine a light on a metal plate, what will make the emitted photoelectrons move away from the plate?
 
10:49 PM
@andras ah okay that was precisely the question I was asking myself before (the second one you asked)
 
@Obliv I'm pretty sure you're talking about the power supply that's there to get the "stopping voltage" - you create an electric field against the motion of the electrons away from the plate to find out the maximal kinetic energy any emitted electron has (you compute it from the volate at which just no electron reaches your detector anymore)
@AndrasDeak They move away from the plate because they get the difference between the work needed to lift them out of the metal and the energy of the incident photon as kinetic energy. Their direction is somewhat random, but enough of them will move out of the plate
 
yeah but then you'll get the diffuse field of the positively charged plate keeping the rest back, right?
but you're probably right that I'm probably confused
it's weird because I would've sworn that I'm clear about the details of the experiment
 
@AndrasDeak There are so few electrons coming out of the plate that it doesn't gain any noticable positive charge in usual setups
 
probably just a habit of hubris
 
You may be confusing the setup with a cathode ray, where you need a voltage to accelerate the slow electrons emitted from a wire by the thermoelectric effect
 
10:54 PM
hmm
shit, you're probably right
thanks (and sorry @Obliv)
 

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