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Old 16th May 2019, 05:48 AM   #2321
JayUtah
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Originally Posted by Gingervytes View Post
Itís already been proven that air pushes off other air. What do you think back pressure is?
Air doesn't "push off" other air. Air behaves as a compressible flow. Your theory requires there to be two kinds of air, and that the air just magically knows which kind it's supposed to be in any given case. The real theory doesn't need any of that. And since you don't know a single thing about actual physics and can't answer the simplest questions, no one trusts your ability to theorize.

As for propulsion, you already admitted an ambient wasn't required in order for gas molecules to transfer momentum to a solid surface. Where you lying then, or are you lying now? You were invited to quantify the effect, but you obviously don't know how. Should we consider that someone who can't work a single elementary physics problem has overturned both Newton and Bernoulli? Or maybe linking to crank YouTube videos isn't the way to explain science.
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Old 16th May 2019, 06:02 AM   #2322
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Originally Posted by Gingervytes View Post
Itís already been proven that air pushes off other air. What do you think back pressure is?
You need to tell us what your version of back pressure is.

Back pressure is a friction loss that occurs during flow through a pipe or other system which reduces overall system energy. One of the reasons a muffler works on an internal combustion engine or a firearm.
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Old 16th May 2019, 06:04 AM   #2323
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Originally Posted by arthwollipot View Post
A tachometer is the correct tool to measure revolutions per second in a turbine.
But if the issue was electrical output generated, a tach wouldn't address that. Kind of like your car's engine could run at a given RPM without charging the battery.
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Old 16th May 2019, 06:07 AM   #2324
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Originally Posted by Ranb View Post
You need to tell us what your version of back pressure is.
Actually, no; introducing an erroneous conception of back pressure is Gingervytes' way of pretending to have answered the question, "What is the reaction force that forms an action reaction pair with the pressure gradient force accelerating gas out of a rocket nozzle?" Gingervytes actually needs to answer the question. His/her continued failure to address it and blatant attempts at misdirection indicate that s/he is well aware that s/he lacks an answer to the question.

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Old 16th May 2019, 06:13 AM   #2325
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Originally Posted by JayUtah View Post
Air doesn't "push off" other air.
This doesn't even make sense.

Gas molecules in the air will bounce off each other, but given the mass match, they are basically equally affected. So which air is pushing off which? In a center-of-mass frame of reference, it is all the same.

There is no such thing as "the atmosphere" to push off. Gasses make up the atmosphere. Gasses are expelled out of the rocket engine. Once they are out, they run into gas molecules in the surroundings, at a rate that is dictated by the density (ignoring, here, the collisions within the gas being expelled). And when the run into the gas molecules in the surroundings, they undergo scattering collisions sending gasses in all directions, depending on the angle of impact, but most of the scattering will be forward scattering, due to the momentum of the expelled gas.

But here's the problem: how the hell does that do ANYTHING to the thing that expelled the gas in the first place? The gas is gone. It's out and away. As far the gas knows, the rocket engine could just as well be miles away. So what makes the rocket move? The small fraction of gas molecules that are back-scattered? That is idiotic.

Imagine a very long pool table. Rack up the balls and break. By the argument presented in this thread, the claim would be that, with no back wall behind the rack, that the pool balls would be coming back toward the cue with enough momentum to create a force to do something. It's mental.
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Old 16th May 2019, 06:16 AM   #2326
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Originally Posted by pgwenthold View Post
It's mental.
Welcome to the tortured logic used by Flat Earthers and Creationists.
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Old 16th May 2019, 06:39 AM   #2327
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Originally Posted by pgwenthold View Post
Gas molecules in the air will bounce off each other, but given the mass match, they are basically equally affected. So which air is pushing off which? In a center-of-mass frame of reference, it is all the same.

There is no such thing as "the atmosphere" to push off. Gasses make up the atmosphere. Gasses are expelled out of the rocket engine.
Yes, that's exactly what I'm talking about. Gingervytes argues as if "the atmosphere" and "pressure gradient force" are just magical externalized phenomena that don't participate in gas behavior, or at least in the same way. In his model, gas that's part of "the air" behaves according to one set of rules, and gas that's part of an exhaust plume obeys fundamentally different rules. Congruently to him, "vacuum" isn't simply the lowest gas pressure that can be produced. To him it's a mysterious, altogether new phenomenon having properties utterly different from the presence of even a tenuous amount of gas.
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Old 16th May 2019, 08:31 AM   #2328
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Originally Posted by smartcooky View Post
I wasn't confused. I've even drawn a nice little illustration for GV to use to explain his theory. Its rudimentary, but it will suffice for this debate.

(And please you rocket scientists out there, don't ruin this exercise and distract from what I am trying to do here by getting nitpicketty on piffling details)

https://www.dropbox.com/s/yd31q8wy3m...sion.png?raw=1

The blue is the atmosphere
The orange is the rocket exhaust
The red arrows are the direction of thrust

The gradient of orange to blue indicates the transition of the density of rocket exhaust gases to the density of the atmosphere.

Now Gingervytes, you argue that the motion of a rocket is caused by the exhaust gases pushing on the atmosphere. Please use the diagram to answer the following questions and requests...

1. Please show everyone the point at which your alleged pushing force occurs. It cannot be inside the rocket bell itself because once it is ignited, all of the atmosphere will be blown away so there will be no atmosphere left inside the bell to push against.

2. Please explain what connects the point at which your alleged pushing force occurs back to the rocket in order to move it, i.e., how is the pushing force transferred back to the rocket?

3. What is the rate at which your alleged pushing force falls away as the atmosphere becomes less dense with increasing altitude? Please express this in terms of ΔF/m i.e. the change in Force per metre of altitude.
Is that a force direction arrow or a fin?
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Old 16th May 2019, 11:11 AM   #2329
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Originally Posted by Gingervytes View Post
It’s already been proven that air pushes off other air.

In what direction does air push on a rocket operating within the atmosphere?
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Old 16th May 2019, 11:38 AM   #2330
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Originally Posted by Elagabalus View Post
Is that a force direction arrow or a fin?
In the black, above the red arrows? I take it to be the exhaust nozzle.
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Old 16th May 2019, 12:59 PM   #2331
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Originally Posted by Elagabalus View Post
Is that a force direction arrow or a fin?
Originally Posted by Trebuchet View Post
In the black, above the red arrows? I take it to be the exhaust nozzle.
I've labelled the diagram for you


Gingervytes. How about trying to answer my questions in post 2303?

http://www.internationalskeptics.com...postcount=2303

What are you afraid of?

You think you are right, so here is your chance to prove it and show us all you know what you're talking about.
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Old 16th May 2019, 03:19 PM   #2332
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Originally Posted by Gingervytes View Post
So when you light, do you face towards the wind blowing or away from it?
As a smoker, neither.
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Old 16th May 2019, 03:26 PM   #2333
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Originally Posted by Gingervytes View Post
It’s already been proven that air pushes off other air. ...
That is as usual irrelevant physics. Gases hitting other gases push the gases (not quite "push off" though), e.g. sound waves ! This is back pressure which is not "air pushes off other air".

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Old 16th May 2019, 03:40 PM   #2334
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Originally Posted by Worm View Post
Can't believe it took me until now to remember this little gem from my favorite podcast.

My Brother, My Brother and Me : When You Nut In Space, It Push You Backwards
(audio certainly NSFW, but the animation is pretty vanilla)

https://www.youtube.com/watch?v=0RsLNwVAAos
My kids love that podcast and it is growing on me. I prefer Sawbones, though.
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Old 16th May 2019, 05:02 PM   #2337
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Originally Posted by curious cat View Post
If you read some of my previous posts, you may have guessed I probably know that .
We are talking about power generated [W] here and that was what they were referring to.
Is there a direct correlation between RPM and power output?
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Old 16th May 2019, 05:11 PM   #2338
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Originally Posted by arthwollipot View Post
Is there a direct correlation between RPM and power output?
I'm bit lost as to the connection to this thread, but yes. If you have RPM and torque, you can calculate power. It just takes force, distance, and time.
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Old 16th May 2019, 05:17 PM   #2339
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Originally Posted by Trebuchet View Post
I'm bit lost as to the connection to this thread, but yes. If you have RPM and torque, you can calculate power. It just takes force, distance, and time.
Then a tachometer is an appropriate tool for measuring power output.
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Old 16th May 2019, 05:51 PM   #2340
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Originally Posted by arthwollipot View Post
Then a tachometer is an appropriate tool for measuring power output.
Not really, because in practical terms for most automobiles a graph of power versus RPM peaks and then falls off. Power is a function of RPM, but not a simple function. Similarly the torque curve also falls off, when plotted against RPM. The interval between the torque peak and the power peak is the "power band," and race drivers tend to shift frantically up and down to keep the RPMs in that power band. Or me, when driving to work.
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Old 16th May 2019, 06:04 PM   #2341
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Originally Posted by JayUtah View Post
Not really, because in practical terms for most automobiles a graph of power versus RPM peaks and then falls off. Power is a function of RPM, but not a simple function. Similarly the torque curve also falls off, when plotted against RPM. The interval between the torque peak and the power peak is the "power band," and race drivers tend to shift frantically up and down to keep the RPMs in that power band. Or me, when driving to work.
Interesting. Thanks for the detailed explanation.
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Old 16th May 2019, 06:14 PM   #2342
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Originally Posted by JayUtah View Post
Not really, because in practical terms for most automobiles a graph of power versus RPM peaks and then falls off. Power is a function of RPM, but not a simple function. Similarly the torque curve also falls off, when plotted against RPM. The interval between the torque peak and the power peak is the "power band," and race drivers tend to shift frantically up and down to keep the RPMs in that power band. Or me, when driving to work.
Is the same true for a wind turbine generator? Is the power output linear with rotational speed of the input shaft? I was taught that it depends largely on load!

(The original question was with regard to a wind turbine generator.)
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Old 16th May 2019, 06:59 PM   #2343
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Originally Posted by smartcooky View Post
Is the same true for a wind turbine generator? Is the power output linear with rotational speed of the input shaft?

(The original question was with regard to a wind turbine generator.)
I think it would depend on the generator. I believe unregulated output of alternators is linear. DC generators have limitations owing to commutator sparking, armature resistance and the like. If an alternator is unregulated (as permanent magnet alternators must be) and if you know the generator's amperage and the relationship of speed to voltage, then you likely could get the answer from a tachometer, but if it's regulated it reaches a cutoff voltage and that, times the current rating of the generator at some given speed, is its maximum output. RPM above that does nothing since the regulator is essentially cycling the generator on and off.
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Old 16th May 2019, 07:13 PM   #2344
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Sorry for throwing this thread off the tracks and thanks for the interesting discussion. Being originally an electronic engineer specialised in measuring and regulation, I obviously know the answers. But it is all irrelevant. These crooks didn't measure anything - they were just trying avoid giving me a refund when I claimed false advertising. I the proper context tachometer definitely wasn't the instrument to solve the problem with. I had no problems convincing E-Bay about my case and they made a quick decision in my favour already.

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Old 16th May 2019, 07:14 PM   #2345
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Originally Posted by arthwollipot View Post
Then a tachometer is an appropriate tool for measuring power output.
Only if you also know the torque.
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Old 16th May 2019, 07:17 PM   #2346
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Originally Posted by Trebuchet View Post
Only if you also know the torque.
Which is something that I would have expected the supplier to know.

Man, if any thread really deserved a good off-topic derail, it is surely this one.
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Old 16th May 2019, 07:43 PM   #2347
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Originally Posted by halleyscomet View Post
The video claims the guy in front of the whiteboard spewing nonsense is a "scientist."
The "guy in front of the whiteboard" is basically deluded with "I am a scientist". He says s a mechanical engineer with a Masters in technical physics.
What makes a scientist is knowing basic science such as how rockets work or even what Newton's third law states !
What makes a scientist is knowing the difference between writing scientific literature and making an insane flat earth video.

1:06: Insanity about rockets working being "programmed in childhood".
1:12: Gets something right: People do laugh at cranks denying that rockets work and laugh at them.
1:48: Stupidity about not seeing a reaction when punching air versus a wall.
2:00 onward: Delusions about Newton's third law, e.g. does not apply when throwing stuff. Inertia gibberish. "feeling" stupidity.
3:44: Delusion that rockets launch by pushing against the ground and then air.
4:55: Stupidity about drones which are not rockets!
5:40: Repeats his delusion abut Newton's third law needing something to push on.
6:50: Irrelevant drone demo. A drone above a sheet of cardboard rises when the sheet is raised. Ground effect (well known effect in helicopter flight and what are drones!)? Maybe even a smart drone keeping height above a "ground".

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Old 16th May 2019, 09:53 PM   #2348
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Computer says no.

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Old 16th May 2019, 10:34 PM   #2349
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Originally Posted by Robin View Post
Pft! You can do anything with CGI.
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Old 17th May 2019, 07:28 AM   #2350
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Originally Posted by Reality Check View Post
The "guy in front of the whiteboard" is basically deluded with "I am a scientist". He says s a mechanical engineer...
That figures.
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Old 17th May 2019, 07:53 AM   #2351
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Originally Posted by Trebuchet View Post
I think you hit the nail on the head.

https://rationalwiki.org/wiki/Engineers_and_woo
Quote:
Most individual engineers are as sensible and reasonable as anyone, but engineers as a group have a noted tendency to pontificate on things well outside their area of expertise, to the point of actual fallacy. This phenomenon is so prevalent that users of talk.origins have come up with the Salem Hypothesis, which predicts that any creationist claiming scientific expertise or advanced degrees is likely to be an engineer.[6] Of course, this does NOT mean that engineers are likely to be creationists.
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Old 17th May 2019, 08:02 AM   #2352
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Originally Posted by Gingervytes View Post
It’s already been proven that air pushes off other air. What do you think back pressure is?

https://www.youtube.com/watch?v=Fnf_f4rogtg&app=desktop
This video is an excellent demonstration of how rockets work in a vacuum. If the Flat Earthers are right, then the soda can should remain stationary in the vacuum chamber when it explodes, as there's no air for it to push off against. If everyone else is right, then the soda can should move when it explodes in the vacuum chamber because the expanding gasses are pushing off of the can.

https://www.youtube.com/watch?v=T8MOoUuLnug
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Old 17th May 2019, 09:18 AM   #2353
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Originally Posted by arthwollipot View Post
...

Man, if any thread really deserved a good off-topic derail, it is surely this one.

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Old 17th May 2019, 06:42 PM   #2354
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Hey, Gingervytes, if all that math-y and science-y stuff and those nasty rigorous engineers are making you tired, I suggest you relax in the warm, murky pools of the meta-world. Yes, philosophy, filled with ambiguity, madness and error, but without a little of which, one might argue, not much means much. Take a moment to think, please, and answer me the very important epistemological conundrum: are there tigers in India?
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Old 17th May 2019, 08:03 PM   #2355
Craig4
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Gingervytes, you know you'll never be part of any conversation that matters right? When we talk about traveling to Mars or the satellites around the Earth, there are people on this board who will be part of those conversations. You won't be though. Nothing you say, nothing you object to will ever be taken seriously. It will be as if you never existed. How does that make you feel?
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Old 17th May 2019, 08:14 PM   #2356
bruto
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Originally Posted by Craig4 View Post
Gingervytes, you know you'll never be part of any conversation that matters right? When we talk about traveling to Mars or the satellites around the Earth, there are people on this board who will be part of those conversations. You won't be though. Nothing you say, nothing you object to will ever be taken seriously. It will be as if you never existed. How does that make you feel?
It's consistent though. There's that old cartoon punchline that nobody knows you're a dog on the internet. We've never experienced him directly so there's every reason to presume that not only will it be as if he never existed, but that he actually never existed anyway. We who do exist (or at least I do - can't speak for the rest of the random flashes of my fevered mind) would be fools to take seriously someone whose existence is so easily denied. He's off in the limbo of imaginary creations, Gollum, the Queen of Hearts, Falstaff, and the tigers in India.
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I love this world, but not for its answers. (Mary Oliver)

Quand il dit "cuic" le moineau croit tout dire. (When he's tweeted the sparrow thinks he's said it all. (Jules Renard)
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Old 17th May 2019, 11:50 PM   #2357
erlando
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Originally Posted by Craig4 View Post
Gingervytes, you know you'll never be part of any conversation that matters right? When we talk about traveling to Mars or the satellites around the Earth, there are people on this board who will be part of those conversations. You won't be though. Nothing you say, nothing you object to will ever be taken seriously. It will be as if you never existed. How does that make you feel?
That's actually the point, isn't it? Nothing flat earthers or other wackos say - however mindboggling it may be - will change the fact that highly skilled engineers around the world are using science to build wonderful things. Not one of those engineers are taking anything said by a wacko seriously. They will at best be a dent in the fabric of internet forums. A very small dent.
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Old 18th May 2019, 12:00 AM   #2358
curious cat
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Originally Posted by Craig4 View Post
Gingervytes, you know you'll never be part of any conversation that matters right? When we talk about traveling to Mars or the satellites around the Earth, there are people on this board who will be part of those conversations. You won't be though. Nothing you say, nothing you object to will ever be taken seriously. It will be as if you never existed. How does that make you feel?
I think we should actually treasure Gingervytes. The point is;
There is a lot of really smart people around. Crackpots don't grow on trees. Seriously; what would've been all of us doing for the last month or so if he wasn't keeping us busy?
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Old 18th May 2019, 04:57 AM   #2359
Gingervytes
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Originally Posted by Mojo View Post
In what direction does air push on a rocket operating within the atmosphere?
Exhaust pushes in air causing back pressure which pushes the rocket
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Old 18th May 2019, 05:02 AM   #2360
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Still waiting for evidence of rockets working in space.
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