Article
Physics, Multidisciplinary
Toni Annala, Roberto Zamora-Zamora, Mikko Mottonen
Summary: This study presents research on topological knots and linked structures, constructs topologically protected links that cannot be untied through local reconnections, and proposes a classification scheme for topological vortex links.
COMMUNICATIONS PHYSICS
(2022)
Review
Chemistry, Physical
Timothy J. Sluckin
Summary: In memory of Maurice Kleman, this article discusses the history of defects in condensed matter, particularly in the context of dislocations, disclinations, and defects in liquid crystals. Maurice's contributions in this field, as well as his interdisciplinary approach combining mathematics, physics, material science, and biology, are highlighted.
LIQUID CRYSTALS REVIEWS
(2022)
Article
Physics, Multidisciplinary
Haiping Hu, Erhai Zhao
Summary: This study explores knots tied by eigenenergy strings in one-dimensional non-Hermitian Hamiltonians, as well as their relationship with Wilson loops. An algorithm is developed to construct corresponding tight-binding non-Hermitian Hamiltonians and a scheme is proposed to probe knot structures via quantum quench.
PHYSICAL REVIEW LETTERS
(2021)
Article
Polymer Science
Bartosz Ambrozy Gren, Pawel Dabrowski-Tumanski, Wanda Niemyska, Joanna Ida Sulkowska
Summary: Complex lasso proteins share topological features with cysteine knots and lasso peptides, and exhibit antimicrobial properties. A method to determine the functional lasso motif is introduced based on stability analysis. Evolution, conservation, and the utility of lasso fingerprint are also studied, revealing 21 previously unknown complex lasso proteins with specific bridge types.
Article
Materials Science, Multidisciplinary
MinSu Kim, Francesca Serra
Summary: This work demonstrates the controlled assembly of liquid crystal topological defects in aperiodic arrays, including quasicrystals and moire patterns. By combining topographic cues and electro-optic effects, the defects can be assembled in multiple patterns with specific symmetries.
ADVANCED OPTICAL MATERIALS
(2022)
Article
Multidisciplinary Sciences
Alvin Modin, Biswarup Ash, Kelsey Ishimoto, Robert L. Leheny, Francesca Serra, Hillel Aharoni
Summary: This study introduces a theoretical framework to quantitatively predict the connectivity and shape of disclination lines in liquid crystals. Through experimental testing and computer simulations, it is found that certain parameters can tune the curvature of disclination lines. This research provides a powerful method to understand and control defect lines in liquid crystals.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Physics, Multidisciplinary
Alexander R. Klotz, Matthew Maldonado
Summary: The ropelength of a knot is the minimum amount of rope needed to tie the knot without self-overlap in three dimensional space. Theoretical upper and lower bounds have been established for the relationship between crossing number and ropelength, and stronger bounds have been conjectured. Studies have shown that ropelength can be described well by a model involving minimal convex hulls around cross-sections of components.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2021)
Article
Chemistry, Multidisciplinary
Geonhyeong Park, Ahram Suh, Hanqing Zhao, Changjae Lee, Yun-Seok Choi, Ivan I. Smalyukh, Dong Ki Yoon
Summary: Topological solitons are continuous field configurations embedded in a uniform background and occur in various fields. However, observing their real-time morphogenesis and dynamics is challenging due to their large or small size and timescale. Researchers have found a new method to observe the generation and transformation of topological solitons using cholesteric liquid crystals confined in patterned substrates. The experimental demonstration shows the formation of topologically protected structures through the transformation of topological defects.
ADVANCED MATERIALS
(2022)
Article
Physics, Mathematical
Benjamin Bode
Summary: Persistent topological structures have gained importance in physical systems, especially electromagnetic fields with knotted field lines. In null electromagnetic fields, the electric and magnetic field lines behave like unbreakable elastic filaments, maintaining their topology and transferring their knottedness to other systems. The knotted and linked field lines are projections of real analytic Legendrian links with respect to the standard contact structure on the 3-sphere.
COMMUNICATIONS IN MATHEMATICAL PHYSICS
(2021)
Review
Chemistry, Physical
Gareth P. Alexander, Randall D. Kamien
Summary: We review the interpretation of Whitehead products in homotopy theory as an entanglement of topological defects in ordered media.
LIQUID CRYSTALS REVIEWS
(2022)
Article
Crystallography
Olaf Stenull, Tom C. Lubensky
Summary: This paper presents analytical calculations of the energies and eigenfunctions of two-dimensional splay (bend) disclinations in different boundary conditions. The stability and transition conditions of the splay configuration are discussed. The differences between the calculations and other methods are also explored.
Article
Crystallography
Sasa Harkai, Charles Rosenblatt, Samo Kralj
Summary: In this study, we numerically investigate the reconfiguration process of colliding 1/2 strength disclinations in an achiral nematic liquid crystal. We find that under certain initial conditions, these disclinations undergo reconfiguration at critical angles, leading to the formation of new defect structures.
Article
Chemistry, Physical
Sasa Harkai, Kaushik Pal, Samo Kralj
Summary: Topological defects, such as disclinations, in liquid crystals are of great interest due to their universal behavior and potential applications. Local melting can trigger the splitting of defects, while nanoparticles can manipulate the core structures. This research provides insights for various fields of physics.
JOURNAL OF MOLECULAR STRUCTURE
(2021)
Article
Physics, Multidisciplinary
L. N. Carenza, G. Gonnella, D. Marenduzzo, G. Negro, E. Orlandini
Summary: This study investigates the phase behavior of quasi-two-dimensional cholesteric liquid crystal shells and discovers novel topological phases that differ from those observed on flat geometries. For spherical shells, finite quasicrystals and amorphous structures are identified, which are made up of mixtures of polygonal tessellations of half-skynnions. For toroidal shells, variations in local curvature lead to the stabilization of heterogeneous phases where cholesteric patterns coexist with hexagonal lattices of half-skyrmions. These findings provide important insights for experimental self-assembling of cholesteric shells.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Physical
Hee Seong Yun, Zazo Cazimir Meijs, Geonhyeong Park, Yutong Fu, Lucio Isa, Dong Ki Yoon
Summary: Hypothesis: Colloidal particles in nematic liquid crystals (LCs) can self-assemble due to attractive forces generated by distorted nematic director configuration when free particles approach. Immobilized particles, on the other hand, can generate repulsive forces, causing deflection of interacting defects to compensate energy increase. Experiments: Tailored arrays of silica microparticles were fabricated to investigate defect interactions, and polarized optical microscopy (POM) was used to study deflection of boojum defects within thin LC films. Findings: Deflected boojum defects were observed on fixed particle arrays, confirming the effect of repulsive forces on defect orientation. Our results provide a platform for controlling defect interactions and exploring potential applications in LC films.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2023)
Article
Physics, Multidisciplinary
Danilo B. Liarte, Matthew Bierbaum, Ricardo A. Mosna, Randall D. Kamien, James P. Sethna
PHYSICAL REVIEW LETTERS
(2016)
Article
Physics, Mathematical
Christyan C. de Oliveira, Ricardo A. Mosna, Joao Paulo M. Pitelli
Summary: In this paper, we revisit the propagation of classical scalar fields in an asymptotically anti-de Sitter spacetime. The lack of global hyperbolicity in the underlying background leads to an ambiguity in the dynamical evolution of wave equation solutions, requiring the specification of additional boundary conditions at the conformal infinity. We demonstrate that the only boundary conditions compatible with the hypothesis of the system being isolated, as defined by the (improved) energy-momentum tensor, are of Dirichlet and Neumann types.
JOURNAL OF MATHEMATICAL PHYSICS
(2022)
Article
Mathematics, Interdisciplinary Applications
Ronaldo S. S. Vieira, Ricardo A. Mosna
Summary: This study explores a different route to chaos in the dynamics of extended bodies, which arises due to finite-size corrections to the otherwise integrable motion of a test particle. Cyclic changes in the overall shape of the body may lead to the onset of chaos in the Duffing and Yukawa potentials, while for Kepler's potential, periodic deviations from spherical symmetry give rise to chaotic regions around the unperturbed parabolic orbit.
CHAOS SOLITONS & FRACTALS
(2022)
Article
Astronomy & Astrophysics
Christyan C. de Oliveira, Ricardo A. Mosna, Joao Paulo M. Pitelli
Summary: We propose an analog model in which the conformally coupled scalar field on the BTZ black hole is represented by the propagation of acoustic waves in a Laval nozzle. By imposing appropriate boundary conditions at its spatial infinity, the dynamics of the scalar field in the BTZ black hole can be well-defined. We demonstrate that the quasinormal modes (QNMs) satisfying different boundary conditions in the BTZ black hole can be interpreted as ordinary QNMs in the extended nozzle.
Article
Astronomy & Astrophysics
Joao Paulo M. Pitelli, Ricardo A. Mosna, Christyan C. de Oliveira, Mauricio Richartz
Summary: The paper discusses analog models for the Schwarzschild and Reissner-Nordstrom spacetimes and compares them to previous research. The study discovers changes in the speed of sound and inconsistencies with the continuity equation, analyzing and explaining these contradictory conclusions.
Article
Astronomy & Astrophysics
Christyan C. de Oliveira, Ricardo A. Mosna
Summary: In this study, we present an analog model for the Banados, Teitelboim, Zanelli (BTZ) black hole based on a hydrodynamical flow. We numerically solve the fully nonlinear hydrodynamic equations of motion and observe the excitation and decay of the analog BTZ quasinormal modes in the process. We consider both a small perturbation in the steady state configuration of the fluid and a large perturbation, which can be regarded as an example of the formation of the analog (acoustic) BTZ black hole.
Article
Astronomy & Astrophysics
Ricardo A. Mosna, Fernanda F. Rodrigues, Ronaldo S. S. Vieira
Summary: We investigate the long-term orbital dynamics of spinless extended bodies in Schwarzschild geometry, and show that periodic deviations from spherical symmetry in the shape of a test body may trigger the onset of chaos.
Article
Astronomy & Astrophysics
Joao P. M. Pitelli, Bruno S. Felipe, Ricardo A. Mosna
Summary: In this study, the response function and transition rate for an Unruh-DeWitt detector interacting with a conformal scalar field in global two-dimensional anti-de Sitter (AdS) spacetime were found. The particle energy spectrum as observed by subcritical accelerated detectors was calculated, and the dependence on boundary conditions was discussed. Despite the nontrivial dependence on boundary conditions, it was shown that the well-defined limit is reached as the AdS length scale tends to zero, leading to the well-known results of 1 + 1 Minkowski space. This suggests that the AdS energy scale serves as a natural regulator for the infrared ambiguity of massless scalar fields in 1 + 1 Minkowski spacetime.
Article
Astronomy & Astrophysics
Christyan C. de Oliveira, Ricardo A. Mosna, Joao Paulo M. Pitelli, Mauricio Richartz
Summary: Analogue models for Schwarzschild and Reissner-Nordstrom spacetimes are presented based on unidirectional hydrodynamic flows. Sound waves in a moving fluid propagate as scalar fields at the equatorial sections of the black holes, with the flow velocity magnitude related to the mass and charge of the analogue black hole. Physical quantities like pressure and density remain finite at the analogue horizon, resulting in well-defined sound waves almost everywhere.
Article
Astronomy & Astrophysics
S. Carlip, R. A. Mosna, J. P. M. Pitelli
Article
Astronomy & Astrophysics
Joao Paulo M. Pitelli, Vitor S. Barroso, Ricardo A. Mosna
Article
Physics, Multidisciplinary
Daniel A. Beller, Kim M. J. Alards, Francesca Tesser, Ricardo A. Mosna, Federico Toschi, Wolfram Mobius
Article
Astronomy & Astrophysics
David Q. Aruquipa, Ricardo A. Mosna, Joao Paulo M. Pitelli
Article
Physics, Fluids & Plasmas
Yimin Luo, Francesca Serra, Daniel A. Beller, Mohamed A. Gharbi, Ningwei Li, Shu Yang, Randall D. Kamien, Kathleen J. Stebe
