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Is Perfect Reversibility A Myth?...

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Juan R." González-Álvarez...
Posted: Wed Nov 04, 2009 1:39 am
Guest
Robert L. Oldershaw wrote on Fri, 30 Oct 2009 12:08:59 -0400:

(...)

[quote]Is it possible that prefect reversibility is a mathematical ideal that
does not apply exactly to any system found the the real world of nature?
[/quote]
*Any* law of physics is a mathematical ideal. One would not confound
reality with our models of her.

For certain systems the production of entropy is so low that cannot be
differentiated from zero and are explained using reversible models.

[quote]Did Poincare already discover this during the 1892-1899 period when
modern chaos theory was founded in his "New Methods of Celestial
Mechanics"?
[/quote]
Poincaré showed that not all mechanical systems are integrable due to
presence of resonances.

The so-called Brussels school tries to build models of irreversibility and
to solve the problem of the arrow of time using Poincare theorems.

They think that irreversible systems are LPS (Large Poincaré Systems).

They also think that resonances introduce an arrow of time.

Their work is well explain to broad audiences in the best-seller book

http://www.amazon.com/End-Certainty-Ilya-Prigogine/dp/0684837056

where he explain how to extend reversible theories from particle physics
to general relativity for accounting for irreversible phenomena, including
a resolution of the measurement problem in quantum mechanics as a bonus.

Whereas I agree on motivations, I disagree on the details of their theory.
In my opinion resonances are not the origin of the time arrow.

[quote]Are the examples of revesibility that physicists frequently cite
actually either artificial idealizations, or refer to systems maintained
briefly in periodic states, but whose full, and unmanipulated, behavior
would include the much more extensive behavior of nonlinear dynamical
systems?
[/quote]
It depends. A reversible model of Moon motion is an excellent idealization
and the time-reversible mechanical equations work fine. A reversible model
of dissipation in a fluid would be artificial.

[quote]What are the best examples of candidates for truly and ideally
reversible systems?
[/quote]
The second law says: reversible systems are those for which production of
entropy is zero.

In thermodynamics we compute the production of entropy (using the
well-known product of forces and fluxes) for checking irreversibility.

Microscopically we have the dissipative quantum equation

d(rho)/dt = L rho + D

when D is zero the production of entropy is also zero and the resulting
dynamics is reversible and described by the Liouville equation

d(rho)/dt = L rho

When the state can be approximated by a pure state

rho = |Psi><Psi|

then the Liouville equation reduces to the Schrödinger equation

d|Psi>/dt = H |Psi>

Therefore one computes D and it if it is zero or close to zero, the
dynamics is reversible.

The big question is what is the new term D? Nobody knows for sure.

Each School propose a diferent D. Some people has proposed
phenomenological terms in wait for a theory of irreversibility.

Zubarev School proposes D = epsilon (rho - rho_R)

where epsilon is a positive infinitesimal and rho_R an auxiliary state
postulated according to certain kernels and phenomenology.

Lindbald proposes another D

http://en.wikipedia.org/wiki/Lindblad_equation

assuming some mathematical properties.

Prigogine School proposes another

http://www.amazon.com/End-Certainty-Ilya-Prigogine/dp/0684837056

where the new term is explained in terms of collision operators
that contain resonances among degrees of freedom.

Byung Chan Eu proposed other based in a generalization of
Boltzmann kinetic theory and the observation of behavior of
hundred of physicochemical systems he studied

http://www.canonicalscience.org/en/researchzone/time.html

Etc.


--
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BLOG:
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Juan R. González-Álvarez...
Posted: Thu Nov 05, 2009 5:58 pm
Guest
Arnold Neumaier wrote on Mon, 02 Nov 2009 11:51:17 -0500:

(...)

[quote]Actually, it follows from the assumption that the universe as a whole is
reversible that asny subsystem of it (in particular anything we cannot
observe) is not reversible, since it depends on interaction with the
remainder of the universe.
[/quote]
Untrue. It is not possible to derive irreversibility from reversibility.
As Van Kampen brilliantly noted "One cannot escape from this fact by any
amount of mathematical funambulism".

The open-system approach is totally inconsistent. The subdynamics of a
reversible system is of course reversible. The so-called derivations of
irreversibility are mathematical and physically invalid.

[quote]So the only perfectly reversible system (if any) is the universe as a
whole (or a set of perfectly noninteractiung universes - of which we can
of course know only the single one we are in).
[/quote]
Those "perfectly noninteractiung universes" that we cannot know belong
to the world of fantasy not to physics.

(...)


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Arnold Neumaier...
Posted: Fri Nov 06, 2009 11:26 pm
Guest
Juan R. González-Álvarez wrote:
[quote]Arnold Neumaier wrote on Mon, 02 Nov 2009 11:51:17 -0500:

Actually, it follows from the assumption that the universe as a whole is
reversible that asny subsystem of it (in particular anything we cannot
observe) is not reversible, since it depends on interaction with the
remainder of the universe.

Untrue. It is not possible to derive irreversibility from reversibility.
As Van Kampen brilliantly noted "One cannot escape from this fact by any
amount of mathematical funambulism".

The open-system approach is totally inconsistent. The subdynamics of a
reversible system is of course reversible. The so-called derivations of
irreversibility are mathematical and physically invalid.
[/quote]
As an approximation, there is nothing inconsistent.

All of physics is valid only approximately anyway; so approximations
are legitimate. In particular, one conventionally approximates the
dynamics of a part of a larger system (whether or not the latter is
assumed to be reversible) successfully as that of an irreversible
system.

This approximation process is well understood - see, e.g.,
H Grabert,
Projection Operator Techniques in Nonequilibrium
Statistical Mechanics,
Springer Tracts in Modern Physics, 1982.
It is often applicable with much success.

In all serious applications of physics, one reduces a system description
to something manageable by replacing its interaction with the unmodelled
environment, using some approximation that accounts for its influence
without having to model it. This makes the system open, but amenable to
a stochastic description. Or, with further approximation, even to a
deterministic description.

If one does not allow for that, one cannot do any physics at all.

[quote]So the only perfectly reversible system (if any) is the universe as a
whole (or a set of perfectly noninteractiung universes - of which we can
of course know only the single one we are in).

Those "perfectly noninteractiung universes" that we cannot know belong
to the world of fantasy not to physics.
[/quote]
We cannot even know whether they are fantasy or physics.
They might exist, and still we could never find out. But of course,
one can ignore them completely without losing anything of
predictive value. This is why I put the statement in parentheses.

Arnold Neumaier
 
Robert L. Oldershaw...
Posted: Mon Nov 09, 2009 10:52 am
Guest
On Nov 4, 6:39 am, "Juan R." González-Álvarez
<juanREM... at (no spam) canonicalscience.com> wrote:


I am also troubled by AN's comment that: "it follows from the
assumption that the universe as a whole is reversible..."

(1) There is considerable confusion over what the term "universe as a
whole" actually means. In fact, the phrase is scientifically undefined
at this point.

(2) Assuming this undefined thing is "reversible" just adds insult to
injury. Who says it must be so? Where is the evidence?

I realize that AN was just speaking in the vernacular, but woe be to
science when assumptions are treated as facts and and used as such in
reasoning.

RLO
www.amherst.edu/~rloldershaw
 
Phillip Helbig...
Posted: Mon Nov 09, 2009 12:24 pm
Guest
Arnold Neumaier wrote on Sat, 07 Nov 2009 09:26:11 +0000:

[quote]Juan R. wrote:
Arnold Neumaier wrote on Mon, 02 Nov 2009 11:51:17 -0500:

Actually, it follows from the assumption that the universe as a
whole is reversible that asny subsystem of it (in particular
anything we cannot observe) is not reversible, since it depends
on interaction with the remainder of the universe.

Untrue. It is not possible to derive irreversibility from
reversibility. As Van Kampen brilliantly noted "One cannot escape
from this fact by any amount of mathematical funambulism".

The open-system approach is totally inconsistent. The subdynamics
of a reversible system is of course reversible. The so-called
derivations of irreversibility are mathematical and physically
invalid.

As an approximation, there is nothing inconsistent.

All of physics is valid only approximately anyway; so approximations
are legitimate. In particular, one conventionally approximates the
dynamics of a part of a larger system (whether or not the latter is
assumed to be reversible) successfully as that of an irreversible
system.

This approximation process is well understood - see, e.g.,
H Grabert,
Projection Operator Techniques in Nonequilibrium Statistical
Mechanics,
Springer Tracts in Modern Physics, 1982.
It is often applicable with much success.

In all serious applications of physics, one reduces a system
description to something manageable by replacing its interaction
with the unmodelled environment, using some approximation that
accounts for its influence without having to model it. This makes
the system open, but amenable to a stochastic description. Or, with
further approximation, even to a deterministic description.

If one does not allow for that, one cannot do any physics at all.
[/quote]
Evidently both Van Kampen (one of most respected physicists
in the field)

http://www.amazon.com/Views-Physicist-Selected-Papers-Kampen/dp/
981024357X

and myself (not at his level of course) are aware of the importance
of approximations. You missed the whole point

I agree with him on that the claimed 'derivations' of irreversibility
from reversibility are based in some "amount of mathematical
funambulism".

His remark is totally general and also applies to the claimed
'derivations' using PO techniques.

PO techniques introduced in NESM in early 60s are rather useful [#].
But its lack of usefulness beyond the weak limit (more exactly in
regimes where the reduced kinetic equation is not closed) is also
well-known.

Moreover, PO techniques are only a clever and *fast* technique to
decompose the so-named "relevant" and "irrelevant" subspaces.
PO techniques do not provide a foundation for NESM neither solve
the problem of the arrow of time.

A more modern and rigorous discussion of those issues was given in a
recent Solvay conference devoted to the problem. Contributions were
published in the next volume

http://www.amazon.com/Resonances-Instability-Irreversibility-Advances-
Chemical/dp/0471165263

I agree on their motivations and welcome their attempt to substitute
"mathematical funambulism" by a more rigorous and axiomatic approach.
However, I want to remark that I disagree with all the theories
presented there.

[quote]So the only perfectly reversible system (if any) is the universe
as a whole (or a set of perfectly noninteractiung universes - of
which we can of course know only the single one we are in).

Those "perfectly noninteractiung universes" that we cannot know
belong
to the world of fantasy not to physics.

We cannot even know whether they are fantasy or physics. They might
exist, and still we could never find out. But of course, one can
ignore them completely without losing anything of predictive value.
This is why I put the statement in parentheses.
[/quote]
That in your own words "set of perfectly noninteractiung universes -
of which we can of course know only the single one we are in" do not
belong to physics.

[#] I want to reproduce here an interesting episode. It is often
acknowledged in NESM literature that PO techniques were introduced
by Nakajima, Zwanzig, and Mori. However, in a personal
communication with Prigogine coworker, Gonzalo Ordonez, he said me
that Prigogine had introduced PO techniques during a talk he gave
and Zwanzig attended. Some time after Zwanzig published his
foundational paper on the PO method. Gonzalo said me that Zwanzig
gave a more elegant formulation but the original idea was from
Prigogine!

--
http://www.canonicalscience.org/

BLOG:
http://www.canonicalscience.org/en/publicationzone/
canonicalsciencetoday/canonicalsciencetoday.html
 
...
Posted: Mon Nov 09, 2009 12:30 pm
Guest
Arnold Neumaier wrote on Sat, 07 Nov 2009 09:26:11 +0000:

[quote]Juan R. wrote:
Arnold Neumaier wrote on Mon, 02 Nov 2009 11:51:17 -0500:

Actually, it follows from the assumption that the universe as a
whole is reversible that asny subsystem of it (in particular
anything we cannot observe) is not reversible, since it depends
on interaction with the remainder of the universe.

Untrue. It is not possible to derive irreversibility from
reversibility. As Van Kampen brilliantly noted "One cannot escape
from this fact by any amount of mathematical funambulism".

The open-system approach is totally inconsistent. The subdynamics
of a reversible system is of course reversible. The so-called
derivations of irreversibility are mathematical and physically
invalid.

As an approximation, there is nothing inconsistent.

All of physics is valid only approximately anyway; so approximations
are legitimate. In particular, one conventionally approximates the
dynamics of a part of a larger system (whether or not the latter is
assumed to be reversible) successfully as that of an irreversible
system.

This approximation process is well understood - see, e.g.,
H Grabert,
Projection Operator Techniques in Nonequilibrium Statistical
Mechanics,
Springer Tracts in Modern Physics, 1982.
It is often applicable with much success.

In all serious applications of physics, one reduces a system
description to something manageable by replacing its interaction
with the unmodelled environment, using some approximation that
accounts for its influence without having to model it. This makes
the system open, but amenable to a stochastic description. Or, with
further approximation, even to a deterministic description.

If one does not allow for that, one cannot do any physics at all.
[/quote]
Evidently both Van Kampen (one of most respected physicists
in the field)

http://www.amazon.com/Views-Physicist-Selected-Papers-Kampen/dp/
981024357X

and myself (not at his level of course) are aware of the importance
of approximations. You missed the whole point

I agree with him on that the claimed 'derivations' of irreversibility
from reversibility are based in some "amount of mathematical
funambulism".

His remark is totally general and also applies to the claimed
'derivations' using PO techniques.

PO techniques introduced in NESM in early 60s are rather useful [#].
But its lack of usefulness beyond the weak limit (more exactly in
regimes where the reduced kinetic equation is not closed) is also
well-known.

Moreover, PO techniques are only a clever and *fast* technique to
decompose the so-named "relevant" and "irrelevant" subspaces.
PO techniques do not provide a foundation for NESM neither solve
the problem of the arrow of time.

A more modern and rigorous discussion of those issues was given in a
recent Solvay conference devoted to the problem. Contributions were
published in the next volume

http://www.amazon.com/Resonances-Instability-Irreversibility-Advances-
Chemical/dp/0471165263

I agree on their motivations and welcome their attempt to substitute
"mathematical funambulism" by a more rigorous and axiomatic approach.
However, I want to remark that I disagree with all the theories
presented there.

[quote]So the only perfectly reversible system (if any) is the universe
as a whole (or a set of perfectly noninteractiung universes - of
which we can of course know only the single one we are in).

Those "perfectly noninteractiung universes" that we cannot know
belong
to the world of fantasy not to physics.

We cannot even know whether they are fantasy or physics. They might
exist, and still we could never find out. But of course, one can
ignore them completely without losing anything of predictive value.
This is why I put the statement in parentheses.
[/quote]
That in your own words "set of perfectly noninteractiung universes -
of which we can of course know only the single one we are in" do not
belong to physics.

[#] I want to reproduce here an interesting episode. It is often
acknowledged in NESM literature that PO techniques were introduced
by Nakajima, Zwanzig, and Mori. However, in a personal
communication with Prigogine coworker, Gonzalo Ordonez, he said me
that Prigogine had introduced PO techniques during a talk he gave
and Zwanzig attended. Some time after Zwanzig published his
foundational paper on the PO method. Gonzalo said me that Zwanzig
gave a more elegant formulation but the original idea was from
Prigogine!

--
http://www.canonicalscience.org/

BLOG:
http://www.canonicalscience.org/en/publicationzone/
canonicalsciencetoday/canonicalsciencetoday.html
 
Arnold Neumaier...
Posted: Sat Nov 28, 2009 12:15 pm
Guest
Robert L. Oldershaw wrote:
[quote]On Nov 4, 6:39 am, "Juan R." González-Álvarez
juanREM... at (no spam) canonicalscience.com> wrote:

I am also troubled by AN's comment that: "it follows from the
assumption that the universe as a whole is reversible..."

(1) There is considerable confusion over what the term "universe as a
whole" actually means. In fact, the phrase is scientifically undefined
at this point.
[/quote]
It can be easily defined precisely as the smallest closed and isolated
physical system that contains the earth.




[quote](2) Assuming this undefined thing is "reversible" just adds insult to
injury. Who says it must be so? Where is the evidence?
[/quote]
According to the mainstream theory, this system is governed by a
reversible dynamics; but there are a significant number of dissenters
who take this into doubt.

Therefore I called the reversibiliy an assumption.


[quote]I realize that AN was just speaking in the vernacular, but woe be to
science when assumptions are treated as facts and and used as such in
reasoning.
[/quote]
Without making assumptions and stating them clearly, no science is
possible.


Arnold Neumaier
 
Robert L. Oldershaw...
Posted: Sat Nov 28, 2009 9:40 pm
Guest
On Nov 28, 5:15 pm, Arnold Neumaier <Arnold.Neuma... at (no spam) univie.ac.at>
wrote:
[quote]
Without making assumptions and stating them clearly, no science is
possible.

[/quote]

Of course, but without keeping theoretical assumptions and empirical
knowledge clearly identified and differentiated, science is fated to
evolve into pseudoscience.

In light of this, consider string theory, multiverses and the 32+
adjustable parameters of the Standard Paradigm.

Robert L. Oldershaw
www.amherst.edu/~rloldershaw
 
Arnold Neumaier...
Posted: Sun Nov 29, 2009 12:43 pm
Guest
juanREMOVE at (no spam) canonicalscience.com wrote:
[quote]Arnold Neumaier wrote on Sat, 07 Nov 2009 09:26:11 +0000:

Juan R. wrote:
Arnold Neumaier wrote on Mon, 02 Nov 2009 11:51:17 -0500:

Actually, it follows from the assumption that the universe as a
whole is reversible that any subsystem of it (in particular
anything we cannot observe) is not reversible, since it depends
on interaction with the remainder of the universe.
Untrue. It is not possible to derive irreversibility from
reversibility. As Van Kampen brilliantly noted "One cannot escape
from this fact by any amount of mathematical funambulism".

The open-system approach is totally inconsistent. The subdynamics
of a reversible system is of course reversible. The so-called
derivations of irreversibility are mathematical and physically
invalid.
As an approximation, there is nothing inconsistent.

All of physics is valid only approximately anyway; so approximations
are legitimate. In particular, one conventionally approximates the
dynamics of a part of a larger system (whether or not the latter is
assumed to be reversible) successfully as that of an irreversible
system.

This approximation process is well understood - see, e.g.,
H Grabert,
Projection Operator Techniques in Nonequilibrium Statistical
Mechanics,
Springer Tracts in Modern Physics, 1982.
It is often applicable with much success.

In all serious applications of physics, one reduces a system
description to something manageable by replacing its interaction
with the unmodelled environment, using some approximation that
accounts for its influence without having to model it. This makes
the system open, but amenable to a stochastic description. Or, with
further approximation, even to a deterministic description.

If one does not allow for that, one cannot do any physics at all.

Evidently both Van Kampen (one of most respected physicists
in the field)

http://www.amazon.com/Views-Physicist-Selected-Papers-Kampen/dp/
981024357X

and myself (not at his level of course) are aware of the importance
of approximations. You missed the whole point

I agree with him on that the claimed 'derivations' of irreversibility
from reversibility are based in some "amount of mathematical
funambulism".
[/quote]
Most derivations of approximations in physics are not controlled
rigorously and hence, in this sense, based on some "amount of
mathematical funambulism". So I don't care about the latter attribute.

Fact is that these approximations work, and are needed to make
practical use of the best physical theories we have.

[quote]PO techniques introduced in NESM in early 60s are rather useful [#].
But its lack of usefulness beyond the weak limit (more exactly in
regimes where the reduced kinetic equation is not closed) is also
well-known.
[/quote]
The Navier-Stokes equations are derivable by PO techniques and work
far beyond the weak limit.

[quote]Moreover, PO techniques are only a clever and *fast* technique to
decompose the so-named "relevant" and "irrelevant" subspaces.
PO techniques do not provide a foundation for NESM neither solve
the problem of the arrow of time.

A more modern and rigorous discussion of those issues was given in a
recent Solvay conference devoted to the problem. Contributions were
published in the next volume

http://www.amazon.com/Resonances-Instability-Irreversibility-Advances-
Chemical/dp/0471165263
[/quote]
(Your review there contains a number of misprints: Pauly, qunatum)

[quote]I agree on their motivations and welcome their attempt to substitute
"mathematical funambulism" by a more rigorous and axiomatic approach.
[/quote]
There cannot be any rigorous way to deduce irreversibility from
reversible foundations.

Prigogine substitutes the reversible foundations by irreversible
foundations, thereby altering the traditional assumptions.

I find his approach interesting but at present not proven to be
better than the mainstream. Moreover, when reducing a system to
a limited number of relevant variables, he still must resprt to
uncontrolled approximations; so in this respect his derivations
do not fare better than the traditional ones.

[quote]However, I want to remark that I disagree with all the theories
presented there.
[/quote]
So do I. But it is easy to criticise what exists.
The challenge is to do something better.

[quote]So the only perfectly reversible system (if any) is the universe
as a whole (or a set of perfectly noninteractiung universes - of
which we can of course know only the single one we are in).
Those "perfectly noninteractiung universes" that we cannot know
belong
to the world of fantasy not to physics.
We cannot even know whether they are fantasy or physics. They might
exist, and still we could never find out. But of course, one can
ignore them completely without losing anything of predictive value.
This is why I put the statement in parentheses.

That in your own words "set of perfectly noninteractiung universes -
of which we can of course know only the single one we are in" do not
belong to physics.
[/quote]
It depends on the definition of physics. I didn't give any.

Arnold Neumaier
 
Uncle Al...
Posted: Sun Nov 29, 2009 1:37 pm
Guest
"Robert L. Oldershaw" wrote:
[quote]
On Nov 28, 5:15 pm, Arnold Neumaier <Arnold.Neuma... at (no spam) univie.ac.at
wrote:

Without making assumptions and stating them clearly, no science is
possible.


Of course, but without keeping theoretical assumptions and empirical
knowledge clearly identified and differentiated, science is fated to
evolve into pseudoscience.

In light of this, consider string theory, multiverses and the 32+
adjustable parameters of the Standard Paradigm.
[/quote]
One can postulate anything, from all swans are white to everything
vacuum free falls identically to string theory is both good math and
good physics. The definitive rectification is a reproducible
empirical falsification. Australia has melanotic swans that breed
true, therefore not all swans are white.

Find two lumps that vacuum free fall differently. General Relativity
postulating the Equivalence Principle and perturbative string theory
demanding BRST invariance, both used to unite the local effects of an
accelerated inertial reference frame and a massive body, are then both
falsified. This would be quite the feat, for GR is absolutely perfect
in its predictions and string theory has none to test. If the vacuum
were selectively anisotropic to pull it off without contradicting
prior observations, conservation of angular momentum through Noether's
theorems also dies - cracking the foundations of the Standard Model
and quantum field theory. That demotes all physics' fundamental
theory to heuristics.

To criticize is to volunteer,

<http://symmetry.hu/content/aus_journal_content_abs_2008_19_4.html>
pages 233-247 (physics), 307-316 (chemistry)

http://www.mazepath.com/uncleal/boojum_p.pdf

It offers an organic molecule whose handedness cannot be formally
labeled, even in principle, though it and its mirror image are
obviously handed. The planetary expert on chemical nomenclature was
sent 14 structure files, 11 killers and three controls. He has no
existing or proposed solution to date. At least five unambiguously
chiral centers in [6.6]chiralane cannot be labeled left or right - and
they are not racemic.

http://www.mazepath.com/uncleal/boojum.pdf

The same analysis applied to physics. All of physical theory could be
subtly wrong for an unsuspected but testable footnote. A cooperative
Nobel Laureate/Physics/gravitation is pondering it. He doesn't like
it, not one bit. To date he cannot find a technical flaw in analysis
or reduction to practice.

sci.physics.research readers are invited to publicly shoot down the
physics paper with technical or empirical falsification - or rally to
have the parity Eotvos experiment in quartz performed by the
U/Washington Eot-Wash group,

http://www.npl.washington.edu/eotwash/

You cannot have it both ways. Prove that macroscopically and
chemically identical, opposite geometric parity atomic mass
distributions *must* vacuum free fall identically without invoking
isotropic vacuum in the massed sector, the EP, or BRST invariance.
(Good luck there - odd-parity Chern-Simons term added to even-parity
Einstein-Hilbert action in quantized gravitations.) OR Gang up on
Blayne Heckel to have him pull his thumb out and perform the parity
Eotvos experiment in quartz.

If you want string theory dead you must empirically kill it. Uncle Al
offers a vorpal sword to behead the hydra and all 10^50,000 of its
snakes. Somebody should look.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz4.htm
 
 
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