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## Quantum Criticality and Black Holes

Fonte: Institute of Physics
Publicador: Institute of Physics

Tipo: Artigo de Revista Científica

Português

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#superconductivity#nanoscale science#low-D systems#structural condensed matter#mechanical condensed matter#thermal condensed matter#gravitation#cosmology#particle physics#statistical physics#nonlinear systems

Many condensed matter experiments explore the finite temperature dynamics of systems near quantum critical points. Often, there are no well-defined quasiparticle excitations, and so quantum kinetic equations do not describe the transport properties completely. The theory shows that the transport coefficients are not proportional to a mean free scattering time (as is the case in the Boltzmann theory of quasiparticles), but are completely determined by the absolute temperature and by equilibrium thermodynamic observables. Recently, explicit solutions of this quantum critical dynamics have become possible via the anti-de Sitter/conformal field theory duality discovered in string theory. This shows that the quantum critical theory provides a holographic description of the quantum theory of black holes in a negatively curved anti-de Sitter space, and relates its transport coefficients to properties of the Hawking radiation from the black hole. We review how insights from this connection have led to new results for experimental systems: (i) the vicinity of the superfluid–insulator transition in the presence of an applied magnetic field, and its possible application to measurements of the Nernst effect in the cuprates, (ii) the magnetohydrodynamics of the plasma of Dirac electrons in graphene and the prediction of a hydrodynamic cyclotron resonance.; Physics

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## Quantum Annealing: from Viewpoints of Statistical Physics, Condensed Matter Physics, and Computational Physics

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 13/04/2012
Português

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#Condensed Matter - Disordered Systems and Neural Networks#Condensed Matter - Statistical Mechanics#Quantum Physics

In this paper, we review some features of quantum annealing and related
topics from viewpoints of statistical physics, condensed matter physics, and
computational physics. We can obtain a better solution of optimization problems
in many cases by using the quantum annealing. Actually the efficiency of the
quantum annealing has been demonstrated for problems based on statistical
physics. Then the quantum annealing has been expected to be an efficient and
generic solver of optimization problems. Since many implementation methods of
the quantum annealing have been developed and will be proposed in the future,
theoretical frameworks of wide area of science and experimental technologies
will be evolved through studies of the quantum annealing.; Comment: 57pages, 15figures, to appear in "Lectures on Quantum Computing,
Thermodynamics and Statistical Physics," Kinki University Series on Quantum
Computing (World Scientific, 2012)

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## Trends in condensed matter physics: is research going faster and faster?

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 06/11/2012
Português

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#Physics - Physics and Society#Condensed Matter - Other Condensed Matter#Computer Science - Digital Libraries

In this paper we study research trends in condensed matter physics. Trends
are analyzed by means of the the number of publications in the different
sub-fields as function of the years. We found that many research topics have a
similar behavior with an initial fast growth and a next slower exponential
decay. We derived a simple model to describe this behavior and built up some
predictions for future trends.

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## Condensed Matter Physics - Biology Resonance

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 02/01/2000
Português

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The field of condensed matter physics had its genesis this century and it has
had a remarkable evolution. A closer look at its growth reveals a hidden aim in
the collective consciousness of the field - a part of the development this
century is a kind of warm up exercise to understand the nature of living
condensed matter, namely the field of biology, by a growing new breed of
scientists in the coming century. Through some examples the vitality of this
interaction will be pointed out.; Comment: 4 pages; Based on a talk given at the Annual Meeting of the Indian
National Science Academy at Madras during 29-31 Dec 1998. (To appear in the
International Journal of Modern Physics B)

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## Performance Acceleration of Kernel Polynomial Method Applying Graphics Processing Units

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 27/05/2011
Português

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#Physics - Computational Physics#Condensed Matter - Other Condensed Matter#Computer Science - Performance

The Kernel Polynomial Method (KPM) is one of the fast diagonalization methods
used for simulations of quantum systems in research fields of condensed matter
physics and chemistry. The algorithm has a difficulty to be parallelized on a
cluster computer or a supercomputer due to the fine-gain recursive
calculations. This paper proposes an implementation of the KPM on the recent
graphics processing units (GPU) where the recursive calculations are able to be
parallelized in the massively parallel environment. This paper also illustrates
performance evaluations regarding the cases when the actual simulation
parameters are applied, the one for increased intensive calculations and the
one for increased amount of memory usage. Finally, it concludes that the
performance on GPU promises very high performance compared to the one on CPU
and reduces the overall simulation time.; Comment: IPDPS/APDCM11, pp. 564-571, Anchorage USA, May 2011

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## Exploiting Grids for applications in Condensed Matter Physics

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 11/02/2010
Português

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#Condensed Matter - Mesoscale and Nanoscale Physics#Condensed Matter - Other Condensed Matter#Computer Science - Computational Engineering, Finance, and Science#Physics - Computational Physics

Grids - the collection of heterogeneous computers spread across the globe -
present a new paradigm for the large scale problems in variety of fields. We
discuss two representative cases in the area of condensed matter physics
outlining the widespread applications of the Grids. Both the problems involve
calculations based on commonly used Density Functional Theory and hence can be
considered to be of general interest. We demonstrate the suitability of Grids
for the problems discussed and provide a general algorithm to implement and
manage such large scale problems.

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## First direct observation of Spin-textures in Topological Insulators : Spin-resolved ARPES as a probe of topological quantum spin Hall effect and Berry's phase

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 16/02/2009
Português

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#Condensed Matter - Mesoscale and Nanoscale Physics#Condensed Matter - Disordered Systems and Neural Networks#Condensed Matter - Superconductivity

A topologically ordered material is characterized by a rare quantum
organization of electrons that evades the conventional spontaneously broken
symmetry based classification of condensed matter. Exotic spin transport
phenomena such as the dissipationless quantum spin Hall effect have been
speculated to originate from a novel topological order whose identification
requires a spin sensitive measurement, which does not exist to this date in any
system (neither in Hg(Cd)Te quantum wells nor in the topological insulator
BiSb). Using Mott polarimetry, we probe the spin degrees of freedom of these
quantum spin Hall states and demonstrate that topological quantum numbers are
uniquely determined from spin texture imaging measurements. Applying this
method to the Bi{1-x}Sb{x} series, we identify the origin of its novel order
and unusual chiral properties. These results taken together constitute the
first observation of surface electrons collectively carrying a geometrical
quantum (Berry's) phase and definite chirality (mirror Chern number, n_M =-1),
which are the key electronic properties for realizing topological computing
bits with intrinsic spin Hall-like topological phenomena. Our spin-resolved
results not only provides the first clear proof of a topological insulating
state in nature but also demonstrate the utility of spin-resolved ARPES
technique in measuring the quantum spin Hall phases of matter.; Comment: 15 pages...

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## Ultracold Atomic Gases: Novel States of Matter

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 31/03/2009
Português

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Article to appear in the Encyclopedia of Complexity and Systems Science, Dr.
R. A. Meyers (Ed.) (Springer Heidelberg, 2009).; Comment: 43 pages, 17 figures. To appear in the Encyclopedia of Complexity and
Systems Science, Dr. R. A. Meyers (Ed.) (Springer Heidelberg, 2009)

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## The effect of 'Open Access' upon citation impact: An analysis of ArXiv's Condensed Matter Section

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 14/11/2006
Português

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#Computer Science - Digital Libraries#Computer Science - Information Retrieval#Physics - Physics and Society

This article statistically analyses how the citation impact of articles
deposited in the Condensed Matter section of the preprint server ArXiv (hosted
by Cornell University), and subsequently published in a scientific journal,
compares to that of articles in the same journal that were not deposited in
that archive. Its principal aim is to further illustrate and roughly estimate
the effect of two factors, 'early view' and 'quality bias', upon differences in
citation impact between these two sets of papers, using citation data from
Thomson Scientific's Web of Science. It presents estimates for a number of
journals in the field of condensed matter physics. In order to discriminate
between an 'open access' effect and an early view effect, longitudinal citation
data was analysed covering a time period as long as 7 years. Quality bias was
measured by calculating ArXiv citation impact differentials at the level of
individual authors publishing in a journal, taking into account co-authorship.
The analysis provided evidence of a strong quality bias and early view effect.
Correcting for these effects, there is in a sample of 6 condensed matter
physics journals studied in detail, no sign of a general 'open access
advantage' of papers deposited in ArXiv. The study does provide evidence that
ArXiv accelerates citation...

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## Soft Condensed Matter (Materia Condensata Soffice)

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 25/11/2004
Português

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This article was written for a multi-volume History of Science, and published
in Italian translation: Storia della Scienza, Volume IX, La Grande Scienza, pp
645-656 (published by Istituto della Enciclopedia Italiana, Fondata da Giovanni
Treccani, 2003). In it, I describe the evolution of soft matter physics as a
discipline during the 20th century.

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## Dynamical Simulation of Nuclear "Pasta": Soft Condensed Matter in Dense Stars

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Português

Relevância na Pesquisa

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More than twenty years ago, it was predicted that nuclei can adopt
interesting shapes, such as rods or slabs, etc., in the cores of supernovae and
the crusts of neutron stars. These non-spherical nuclei are referred to as
nuclear "pasta".
In recent years, we have been studying the dynamics of the pasta phases using
a method called quantum molecular dynamics (QMD) and have opened up a new
aspect of study for this system. Our findings include: dynamical formation of
the pasta phases by cooling down the hot uniform nuclear matter; phase diagrams
in the density versus temperature plane; structural transitions between the
pasta phases induced by compression and elucidation of the mechanism by which
they proceed. In the present article, we given an overview of the basic physics
and astrophysics of the pasta phases and review our works for readers in other
fields.; Comment: 33 pages, 18 figures, revised version, published in "Soft Condensed
Matter: New Research", edited by K. I. Dillon (Nova Science Publishers, New
York, 2007), high-res figures can be seen at
http://www.nordita.dk/~gentaro/research/figs

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## First-principles calculation of entropy for liquid metals

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Português

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We demonstrate the accurate calculation of entropies and free energies for a
variety of liquid metals using an extension of the two phase thermodynamic
(2PT) model based on a decomposition of the velocity autocorrelation function
into gas-like (hard sphere) and solid-like (harmonic) subsystems. The hard
sphere model for the gas-like component is shown to give systematically high
entropies for liquid metals as a direct result of the unphysical Lorentzian
high-frequency tail. Using a memory function framework we derive a generally
applicable velocity autocorrelation and frequency spectrum for the diffusive
component which recovers the low frequency (long time) behavior of the hard
sphere model while providing for realistic short time coherence and high
frequency tails to the spectrum. This approach provides a significant increase
in the accuracy of the calculated entropies for liquid metals and is compared
to ambient pressure data for liquid sodium, aluminum, gallium, tin, and iron.
The use of this method for the determination of melt boundaries is demonstrated
with a calculation of the high pressure bcc melt boundary for sodium. With the
significantly improved accuracy available with the memory function treatment
for softer interatomic potentials...

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## The Fermi Gases and Superfluids: Short Review of Experiment and Theory for Condensed Matter Physicists

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 09/02/2012
Português

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The study of ultracold atomic Fermi gases is a rapidly exploding subject
which is defining new directions in condensed matter and atomic physics. Quite
generally what makes these gases so important is their remarkable tunability
and controllability. Using a Feshbach resonance one can tune the attractive
two-body interactions from weak to strong and thereby make a smooth crossover
from a BCS superfluid of Cooper pairs to a Bose-Einstein condensed superfluid.
Furthermore, one can tune the population of the two spin states, allowing
observation of exotic spin-polarized superfluids, such as the Fulde Ferrell
Larkin Ovchinnikov (FFLO) phase. A wide array of powerful characterization
tools, which often have direct condensed matter analogues, are available to the
experimenter. In this Chapter, we present a general review of the status of
these Fermi gases with the aim of communicating the excitement and great
potential of the field.; Comment: 34 pages, 15 figures. To appear as a chapter in "Contemporary
Concepts of Condensed Matter Science", Elsevier

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## Quantum Information Meets Quantum Matter -- From Quantum Entanglement to Topological Phase in Many-Body Systems

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Português

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This is the draft version of a textbook, which aims to introduce the quantum
information science viewpoints on condensed matter physics to graduate students
in physics (or interested researchers). We keep the writing in a
self-consistent way, requiring minimum background in quantum information
science. Basic knowledge in undergraduate quantum physics and condensed matter
physics is assumed. We start slowly from the basic ideas in quantum information
theory, but wish to eventually bring the readers to the frontiers of research
in condensed matter physics, including topological phases of matter, tensor
networks, and symmetry-protected topological phases.; Comment: Hyperref added. This draft is by no means final. Substantial
scientific and format changes are still to be made. We have received many
helpful comments. We are very grateful for them and will incorporate them
into later versions. Please keep sending us comments. The full edition of the
book will be available from Springer, in which we will acknowledge the help
we have received from everyone

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## Cold and Ultracold Molecules: Science, Technology, and Applications

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 21/04/2009
Português

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55.45%

#Quantum Physics#Condensed Matter - Quantum Gases#Physics - Atomic Physics#Physics - Chemical Physics

This article presents a review of the current state of the art in the
research field of cold and ultracold molecules. It serves as an introduction to
the Special Issue of the New Journal of Physics on Cold and Ultracold Molecules
and describes new prospects for fundamental research and technological
development. Cold and ultracold molecules may revolutionize physical chemistry
and few body physics, provide techniques for probing new states of quantum
matter, allow for precision measurements of both fundamental and applied
interest, and enable quantum simulations of condensed-matter phenomena.
Ultracold molecules offer promising applications such as new platforms for
quantum computing, precise control of molecular dynamics, nanolithography, and
Bose-enhanced chemistry. The discussion is based on recent experimental and
theoretical work and concludes with a summary of anticipated future directions
and open questions in this rapidly expanding research field.; Comment: 82 pages, 9 figures, review article to appear in New Journal of
Physics Special Issue on Cold and Ultracold Molecules

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## Characterizing Structure Through Shape Matching and Applications to Self Assembly

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 20/12/2010
Português

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55.57%

#Condensed Matter - Soft Condensed Matter#Computer Science - Computer Vision and Pattern Recognition

Structural quantities such as order parameters and correlation functions are
often employed to gain insight into the physical behavior and properties of
condensed matter systems. While standard quantities for characterizing
structure exist, often they are insufficient for treating problems in the
emerging field of nano and microscale self-assembly, where the structures
encountered may be complex and unusual. The computer science field of "shape
matching" offers a robust solution to this problem by defining diverse methods
for quantifying the similarity between arbitrarily complex shapes. Most order
parameters and correlation functions used in condensed matter apply a specific
measure of structural similarity within the context of a broader scheme. By
substituting shape matching quantities for traditional quantities, we retain
the essence of the broader scheme, but extend its applicability to more complex
structures. Here we review some standard shape matching techniques and discuss
how they might be used to create highly flexible structural metrics for diverse
systems such as self-assembled matter. We provide three proof-of-concept
example problems applying shape matching methods to identifying local and
global structures, and tracking structural transitions in complex assembled
systems. The shape matching methods reviewed here are applicable to a wide
range of condensed matter systems...

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## Harmonic Order Parameters for Characterizing Complex Particle Morphologies

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 20/12/2010
Português

Relevância na Pesquisa

55.51%

#Condensed Matter - Soft Condensed Matter#Computer Science - Computer Vision and Pattern Recognition#Physics - Chemical Physics

Order parameters based on spherical harmonics and Fourier coefficients
already play a significant role in condensed matter research in the context of
systems of spherical or point particles. Here, we extend these types of order
parameter to more complex shapes, such as those encountered in nanoscale
self-assembly applications. To do so, we build on a powerful set of techniques
that originate in the computer science field of "shape matching." We
demonstrate how shape matching techniques can be applied to identify unknown
structures and create highly-specialized \textit{ad hoc} order parameters.
Additionally, we investigate the special symmetry properties of harmonic
descriptors, and demonstrate how they can be exploited to provide optimal
solutions to certain classes of problems. Our techniques can be applied to
particle systems in general, both simulated and experimental, provided the
particle positions are known.; Comment: 13 pages, 9 figures, J. Chem. Phys., submitted

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## Quantum Hamiltonian Complexity

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Português

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#Quantum Physics#Condensed Matter - Strongly Correlated Electrons#Computer Science - Computational Complexity

We survey the growing field of Quantum Hamiltonian Complexity, which includes
the study of Quantum Constraint Satisfaction. In particular, our aim is to
provide a computer science-oriented introduction to the subject in order to
help bridge the language barrier between computer scientists and physicists in
the field. As such, we include the following in this paper: (1) The motivations
and history of the field, (2) a glossary of condensed matter physics terms
explained in computer-science friendly language, (3) overviews of central ideas
from condensed matter physics, such as indistinguishable particles, mean field
theory, tensor networks, and area laws, and (4) brief expositions of selected
computer science-based results in the area. For example, as part of the latter,
we provide a novel information theoretic presentation of Bravyi's polynomial
time algorithm for Quantum 2-SAT.; Comment: v3 is identical to v2; simply added new author (S. W. Shin) to arXiv
metadata. Comments otherwise identical to v2: 58 pages. Substantial changes:
(1) Length almost doubled via addition of sections on physics motivations,
indistinguishable particles (i.e. bosons, fermions), area laws, etc. (2)
Added new author, S. W. Shin. Minor changes to improve readability throughout

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## Comment on "Control of Spin Precession in a Spin-Injected Field Effect Transistor" [Science, 325, 1515 (2009)]

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 01/11/2009
Português

Relevância na Pesquisa

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A recently published report in the journal Science claims that the Datta-Das
Spin Field Effect Transistor has been demonstrated because an exact agreement
was found between the voltage modulation in a fabricated structure and a
theoretical equation that supposedly describes the voltage modulation of the
Datta-Das Transistor. Here, I show that the said theoretical equation holds
only for a one-dimensional transistor, or perhaps a quasi one-dimensional
transistor, and is certainly not applicable to the two-dimensional transistor
studied. Hence, the exact agreement is meaningless and does not substantiate
the claim.; Comment: rejected by Science

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## How to model macroscopic worlds: Towards the philosophy of condensed matter physics.

Fonte: London School of Economics and Political Science Thesis
Publicador: London School of Economics and Political Science Thesis

Tipo: Thesis; NonPeerReviewed
Formato: application/pdf

Publicado em //2001
Português

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Condensed matter physics studies many-body phenomena, the phenomena involving a huge number of constituents interacting with each other strongly. My theme is modelling in condensed matter physics: the construction of mathematical/physical structures in order to understand many-body phenomena in the world. I study how condensed matter physicists learn about many-body phenomena from the successful employment of models. My proposal is to construe condensed matter physics as engaged essentially with the three activities: model-building, model-exploring and model-based understanding. General theories such as statistical mechanics guide the process of model-building as model-building methodology. I discuss the multiple layers of interactions among general theories (particularly among thermodynamics and statistical mechanics) and show that complementation and cooperation rather than reduction are better concepts for understanding their relation. In model-exploring stage, we probe a model in order to determine what exactly the model implies in itself and what it could with additional constraints. I investigate a number of epistemic roles of approximations in this stage. I also discuss what consists of model-based understanding. With the help of appropriate interpretative models...

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