Article
Physics, Fluids & Plasmas
Licun Fu, Lijin Wang
Summary: This study investigates the effect of anharmonicity on sound attenuation in two-dimensional glasses using computer simulations. The findings reveal that the influence of anharmonicity on sound attenuation in two-dimensional glasses is the same as in three-dimensional glasses.
Article
Physics, Fluids & Plasmas
Licun Fu, Lijin Wang
Summary: In this study, computer simulations of 2D glasses were performed to investigate the influence of anharmonicity on sound attenuation. The results showed that the influence of anharmonicity on sound attenuation in 2D glasses is the same as that in 3D glasses, indicating that this effect is independent of spatial dimension.
Article
Physics, Multidisciplinary
Florian Vogel, Matthias Fuchs
Summary: We study the vibrational properties of topologically disordered materials by analyzing particles that oscillate harmonically around random positions. Utilizing classical field theory in the thermodynamic limit, we establish a self-consistent model that takes into account nonplanar diagrams for multiple local scattering events. This allows us to accurately predict anomalies in athermal disordered materials, including the boson peak, sound softening, and Rayleigh damping of sound. The vibrational density of states exhibits Debye's law for small frequencies and an excess starting as co4 in the low frequency limit, attributed to (quasi-) localized modes.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Fluids & Plasmas
C. Granier, D. Borgogno, L. Comisso, D. Grasso, E. Tassi, R. Numata
Summary: The marginal stability conditions for the formation of plasmoids in a purely collisionless and strong guide field situation are investigated in this study. It is found that plasmoids can be obtained from current sheets with a smaller aspect ratio in the marginal stability current layers.
Article
Materials Science, Multidisciplinary
Anustup Chakraborty, Sakthi Prasad, Shashi Kant, Rathina Vel, Sucheta Tripathy, P. K. Sinha, Krishna K. Dey, Lekhan Lodhi, Manasi Ghosh, Amarnath R. Allu, Subhadip Bodhak, Kaushik Biswas
Summary: The study aims to address the challenge of high crystallization tendency of commercial bioactive glasses, which leads to the loss of desired functionalities in bone tissue engineering applications. By understanding the composition-structure-property correlations, borosilicate bioactive glasses with improved thermal stability were developed. Structural studies showed a highly crosslinked network rich in B-O-Si bonds, which contributed to enhanced thermal stability (>150 ℃) for glasses containing 17.96-35.92 mol% B2O3. These glasses also exhibited improved in vitro biological properties such as biomineralization, cell proliferation, alkaline phosphatase expression, and antibacterial efficacy due to the prevalence of B-O-Si and B-O-B bonds. However, more detailed pre-clinical studies are required to validate these observations and explore specific applications.
JOURNAL OF MATERIALS RESEARCH
(2023)
Article
Materials Science, Multidisciplinary
R. Kumar, A. Chakraborty, S. Fukuoka, F. Damay, E. Kermarrec, P. L. Paulose, Y. Ihara
Summary: By studying the isostructural kagome magnet Li9Cr3(P2O7)3(PO4)2 (LCPO) with active t2g orbitals and S = 3/2, we found that the ground-state properties of LCPO are dominated by ferromagnetic interactions, with a mean-field temperature of around 3 K and an ordering temperature of around 2.7 K. The material exhibits additional in- and out-of-plane further-neighbor antiferromagnetic couplings, although weaker compared to the dominant first-nearest-neighbor ferromagnetic coupling. Experimental results demonstrate the stabilization of a ferromagnetic-like ground state and the persistence of magnetic correlations above the ordering temperature in LCPO.
Article
Materials Science, Ceramics
Yang Liu, Huashan Liu, Hailong Peng
Summary: We use molecular dynamics simulations to mimic the structural heterogeneity of inclusions in nanoscale CuZr metallic glasses (MGs) by pinning a portion of atoms. The results indicate that the yielding behavior of MGs transitions from a system-spanning shear band to a localized plastic flow with pinning. The spatial correlation of the nonaffine displacement exhibits a quadrupolar symmetry that shrinks with pinning, which signifies the anisotropic nature of the plastic regions diminishing with pinning.
JOURNAL OF NON-CRYSTALLINE SOLIDS
(2023)
Article
Materials Science, Multidisciplinary
David Richard, Edan Lerner, Eran Bouchbinder
Summary: Understanding the fracture toughness of glasses is crucial for science and technology. Atomistic simulations show that varying parameters such as cooling rate and loading geometry can affect the toughness of glasses. Soft defects and loading geometry play significant roles in the toughness of glasses.
Article
Astronomy & Astrophysics
P. H. Yoon, M. Sarfraz, Z. Ali, C. S. Salem, J. Seough
Summary: This paper formulates a velocity moment-based quasi-linear theory to study the impacts of weakly unstable modes on the solar wind plasma. By characterizing the weakly unstable modes using an analytical formalism, an efficient numerical platform is provided for analyzing the development of these instabilities.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Materials Science, Multidisciplinary
D. Sopu, X. Yuan, F. Moitzi, F. Spieckermann, X. Bian, J. Eckert
Summary: Shear transformation zones (STZs) are crucial for explaining plastic flow in metallic glasses, but their morphological and dynamical characteristics are not fully understood. Through simulations, it has been found that STZ activation occurs from the early stage of elastic deformation to the final shearing stage. STZs in the elastic and plastic ranges share similar characteristics but differ in magnitude and dynamics.
APPLIED MATERIALS TODAY
(2021)
Article
Astronomy & Astrophysics
Dmitriy Ovchinnikov, Muhammad Umar Farooq, Ibrar Hussain, Ahmadjon Abdujabbarov, Bobomurat Ahmedov, Zdenek Stuchlik
Summary: This study investigates the marginally stable circular orbits of test particles in the vicinity of a charged Kiselev black hole, taking into consideration the influence of the quintessence field on the innermost and outermost stable circular orbits, as well as the radii of photon circular orbits. The analysis also includes the radial and latitudinal epicyclic motion of test particles, showing that azimuthal and latitudinal frequencies coincide while the radial epicyclic frequency varies depending on spacetime parameters and equation of state parameters. Furthermore, the effects of the normalization factor and electric charge on the epicyclic frequencies near the innermost and outermost stable circular orbits are discussed.
Article
Engineering, Mechanical
Yuling Shen, Muhao Chen, Manoranjan Majji, Robert E. Skelton
Summary: An observer-based q-Markov Covariance equivalent realization (QMC) formulation is presented in the paper. It is shown that by inserting an observer in the input-output relationship associated with the dynamical system, a QMC approach can be developed that is applicable to systems with marginally stable or unstable equilibrium points. A system of equations governing all linear state-space realizations, along with the corresponding observers, is derived from matching a set of Markov and Covariance parameters. The solution to this equation system is shown to parameterize all state-space realizations that match the pre-specified correlation functions. Four numerical examples are used to show the utility of the proposed approach. The numerical results show that the observer-based QMC presented in the paper can identify linear SISO and MIMO systems with stable, marginally stable, and unstable characteristics.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2023)
Article
Mathematics, Applied
Aghil Alaee, Martin Lesourd, Shing-Tung Yau
Summary: Various notions of stability for surfaces embedded and immersed in spacetimes and initial data sets are explored. The study includes Christodoulou-Yau estimates for H-stable surfaces, a Cohn-Vossen type inequality for non-compact stable MOTS, and a global theorem on the topology of H-stable surfaces. Additionally, capillary stability for MOTS with boundary is defined. Area upper bound inequality and a local splitting theorem for free boundary stable MOTS are generated from this notion of stability. Index and diameter estimates for free boundary MOTS are also established, which are generalizations of results for free boundary minimal surfaces.
CALCULUS OF VARIATIONS AND PARTIAL DIFFERENTIAL EQUATIONS
(2021)
Article
Mathematics, Interdisciplinary Applications
Giacomo Gradenigo, Matteo Paoluzzi
Summary: Early studies have shown that the geometric features of the energy landscape play a fundamental role in the crossover from high-temperature simple relaxational dynamics to low-temperature activated relaxation in the glass transition. Active particles are shown to be useful in gaining insight into this topological crossover, especially in inducing critical non-equilibrium correlations in the presence of self-propulsion.
CHAOS SOLITONS & FRACTALS
(2021)
Article
Physics, Multidisciplinary
Lukas Sponfeldner, Nadine Leisgang, Shivangi Shree, Ioannis Paradisanos, Kenji Watanabe, Takashi Taniguchi, Cedric Robert, Delphine Lagarde, Andrea Balocchi, Xavier Marie, Iann C. Gerber, Bernhard Urbaszek, Richard J. Warburton
Summary: The coupling of intralayer A and B excitons and interlayer excitons (IE) in a two-dimensional semiconductor, homobilayer MoS2, is studied. The optical susceptibility measurements reveal both the magnitude and phase of the coupling constants. The coupling mechanisms between IE-B and IE-A are interpreted as hole tunneling and electron-hole exchange, respectively. It is also found that even in a monolayer, the A and B excitons have mixed spin states. Moreover, a bright and highly tunable lowest-energy momentum-direct exciton is achieved under high electric fields.
PHYSICAL REVIEW LETTERS
(2022)
Article
Mechanics
Pier Giuseppe Ledda, Gioele Balestra, Gaetan Lerisson, Benoit Scheid, Matthieu Wyart, Francois Gallaire
Summary: This study examines the role of hydrodynamic instabilities in the formation of typical karst draperies structures in limestone caves. The research uses the long wave approximation to analyze the fluid film flowing under an inclined substrate with substrate variations growing according to a deposition law. Numerical simulations are conducted to study the linear and nonlinear evolution of localized initial perturbations in the fluid film and on the substrate, leading to a deeper understanding of pattern formation.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Physics, Multidisciplinary
Marko Popovic, Valentin Druelle, Natalie A. Dye, Frank Juelicher, Matthieu Wyart
Summary: Amorphous materials exhibit complex material properties with strongly nonlinear behaviors. The density of weak spots and flow properties can be determined from the geometry of an amorphous structure alone. This suggests that tissue exhibits plasticity and non-linear material properties emerging from collective cell behaviors.
NEW JOURNAL OF PHYSICS
(2021)
Article
Mechanics
I Paga, Q. Zhai, M. Baity-Jesi, E. Calore, A. Cruz, L. A. Fernandez, J. M. Gil-Narvion, I Gonzalez-Adalid Pemartin, A. Gordillo-Guerrero, D. Iniguez, A. Maiorano, E. Marinari, V Martin-Mayor, J. Moreno-Gordo, A. Munoz-Sudupe, D. Navarro, R. L. Orbach, G. Parisi, S. Perez-Gaviro, F. Ricci-Tersenghi, J. J. Ruiz-Lorenzo, S. F. Schifano, D. L. Schlagel, B. Seoane, A. Tarancon, R. Tripiccione, D. Yllanes
Summary: The research focuses on a microscopic analysis of spin-glass dynamics through experiments and simulations, with a particular emphasis on the evolution of spin-glass correlation length at different times and temperatures.
JOURNAL OF STATISTICAL MECHANICS-THEORY AND EXPERIMENT
(2021)
Article
Mechanics
Jonas Paccolat, Leonardo Petrini, Mario Geiger, Kevin Tyloo, Matthieu Wyart
Summary: This article explores how neural networks compress uninformative input space in feature learning and lazy training regimes, and demonstrates that compression can improve learning curves and test error. The study suggests that compression is crucial for training MNIST, as well as proposing kernel principal component analysis on the evolving NTK as a useful diagnostic in deep networks.
JOURNAL OF STATISTICAL MECHANICS-THEORY AND EXPERIMENT
(2021)
Review
Physics, Multidisciplinary
Mario Geiger, Leonardo Petrini, Matthieu Wyart
Summary: Deep learning algorithms have revolutionized tasks like image recognition, however the underlying mechanisms are still not fully understood. Classifying data in high dimension is a challenging feat due to the curse of dimensionality, yet deep learning manages to do so. Research has shown that learning involves minimizing loss in high dimension, which can lead to difficulties in finding optimal solutions.
PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS
(2021)
Article
Chemistry, Physical
Junzhang Ma, Simin Nie, Xin Gui, Muntaser Naamneh, Jasmin Jandke, Chuanying Xi, Jinglei Zhang, Tian Shang, Yimin Xiong, Itzik Kapon, Neeraj Kumar, Yona Soh, Daniel Gosalbez-Martinez, Oleg Yazyev, Wenhui Fan, Hannes Huebener, Umberto De Giovannini, Nicholas Clark Plumb, Milan Radovic, Michael Andreas Sentef, Weiwei Xie, Zhijun Wang, Christopher Mudry, Markus Mueller, Ming Shi
Summary: Using angle-resolved photoemission spectroscopy, the authors detected mobile bound states of excitons in quasi-one-dimensional metallic TaSe3, providing evidence for the elusive exciton mobility in metals.
Article
Biodiversity Conservation
Agnieszka Sendek, Marco Baity-Jesi, Florian Altermatt, Martin K. -F Bader, Andrew M. Liebhold, Rebecca M. Turner, Alain Roques, Hanno Seebens, Piet Spaak, Christoph Vorburger, Eckehard G. Brockerhoff
Summary: Non-native insect species are under-represented in freshwater habitats compared to terrestrial habitats. This pattern is consistent across different regions. Our study contributes to understanding the drivers and impacts of biological invasions.
DIVERSITY AND DISTRIBUTIONS
(2022)
Article
Ecology
Ian R. McFadden, Agnieszka Sendek, Morgane Brosse, Peter M. Bach, Marco Baity-Jesi, Janine Bolliger, Kurt Bollmann, Eckehard G. Brockerhoff, Giulia Donati, Friederike Gebert, Shyamolina Ghosh, Hsi-Cheng Ho, Imran Khaliq, J. Jelle Lever, Ivana Logar, Helen Moor, Daniel Odermatt, Loiec Pellissier, Luiz Jardim de Queiroz, Christian Rixen, Nele Schuwirth, J. Ryan Shipley, Cornelia W. Twining, Yann Vitasse, Christoph Vorburger, Mark K. L. Wong, Niklaus E. Zimmermann, Ole Seehausen, Martin M. Gossner, Blake Matthews, Catherine H. Graham, Florian Altermatt, Anita Narwani
Summary: Human impacts such as habitat loss, climate change, and biological invasions are drastically changing biodiversity. We propose an integrative approach to explain the differences in impacts between terrestrial and freshwater ecosystems by linking them to four fundamental processes that structure communities. Through this approach, we aim to provide insights into why human impacts and responses to them may differ across ecosystem types, using a mechanistic, eco-evolutionary framework.
Article
Physics, Multidisciplinary
M. Baity-Jesi, E. Calore, A. Cruz, L. A. Fernandez, J. M. Gil-Narvion, I. Gonzalez-Adalid Pemartin, A. Gordillo-Guerrero, D. Iniguez, A. Maiorano, E. Marinari, V. Martin-Mayor, J. Moreno-Gordo, A. Munoz Sudupe, D. Navarro, I. Paga, G. Parisi, S. Perez-Gaviro, F. Ricci-Tersenghi, J. J. Ruiz-Lorenzo, S. F. Schifano, B. Seoane, A. Tarancon, D. Yllanes
Summary: Memory and rejuvenation effects in off-equilibrium spin glasses have been regarded as a gateway to experimental exploration of ultrametricity and temperature chaos. However, simulating these effects has been difficult until recent advancements in computing power and understanding of length scales in aging dynamics of spin glasses. A numerical study has shown that at least three different length scales play a crucial role in aging dynamics, challenging previous theories that focused on a single glassy correlation length.
Article
Materials Science, Multidisciplinary
Jiajun Li, Markus Muller, Aaram J. Kim, Andreas M. Lauchli, Philipp Werner
Summary: Recent advances in ultrafast pump-probe spectroscopy have allowed the exploration of hidden phases of correlated matter, including light-induced superconducting states. A new type of chiral superconducting phase has been induced in frustrated Mott insulators through photodoping, forming a condensate of doublons and holons. This metastable phase features a spatially varying order parameter with a 120 degrees phase twist, breaking time-reversal and inversion symmetry. The presented results demonstrate the chiral nature of the light-induced superconducting state and its distinguishing properties, which can be observed in pump-probe experiments.
Article
Optics
Keita Omiya, Markus Muller
Summary: We study the nature of the ergodicity-breaking quantum many-body scar states in the PXP model and reveal a common structure that gives rise to these states. We provide an extension of the PXP model that can host exact quantum scars and show that existing scar-stabilizing extensions can be understood within this framework. The exact scar states are obtained as large spin states of explicitly constructed pseudospins, and the quasiperiodic motion is shown to be the projection of the large pseudospin's precession onto the Rydberg-constrained subspace.
Article
Physics, Fluids & Plasmas
Matthew R. Carbone, Marco Baity-Jesi
Summary: In this study, we investigate two different types of activated dynamics in simplified models of glasses, and find that one type may dominate over the other under specific conditions, with temperature and density of states shape playing a role. Additionally, we propose a possible phase transition between the two types of activation at low temperatures, and use our observations to provide a unified description of the slowdown of glasses, reconciling the facilitation and thermodynamic pictures.
Article
Geosciences, Multidisciplinary
Marvin Hoege, Andreas Scheidegger, Marco Baity-Jesi, Carlo Albert, Fabrizio Fenicia
Summary: Deep learning methods have shown better performance than conceptual hydrologic models in rainfall-runoff modelling. However, the internal workings of these deep learning models and their relationships with input and output are not fully understood. In this study, the authors propose hydrologic neural ordinary differential equation (ODE) models that combine the interpretability of conceptual models with the power of deep learning. The models are tested on 569 catchments in the continental United States, and their predictive performance and internal dynamics are analyzed.
HYDROLOGY AND EARTH SYSTEM SCIENCES
(2022)
Article
Materials Science, Multidisciplinary
A. Beckert, M. Grimm, R. Hermans, J. R. Freeman, E. H. Linfield, A. G. Davies, M. Muller, H. Sigg, S. Gerber, G. Matmon, G. Aeppli
Summary: The crystal field energy levels and magnetic moments of the insulating rare-earth magnet LiY1-xHoxF4 were investigated, including the hyperfine corrections, and the far-infrared, low-temperature refractive index of the material was determined.
Article
Physics, Fluids & Plasmas
Wencheng Ji, Tom W. J. de Geus, Elisabeth Agoritsas, Matthieu Wyart
Summary: This paper investigates the local rearrangement phenomenon in amorphous materials, where groups of particles can form new stable configurations. The study finds that the geometry of these excitations becomes smaller, with higher energy and displacement scale, as they approach the instability.
