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Connecting polymer collapse and the onset of jamming

Physical Review E 2024年第3期109卷 034406-034406页

作者： Alex T. Grigas Aliza Fisher Mark D. Shattuck Corey S. O'Hern Graduate Program in Computational Biology and Bioinformatics Yale University New Haven Connecticut 06520 USA Integrated Graduate Program in Physical and Engineering Biology Yale University New Haven Connecticut 06520 USA Department of Mechanical Engineering and Materials Science Yale University New Haven Connecticut 06520 USA Benjamin Levich Institute and Physics Department The City College of New York New York New York 10031 USA Department of Physics Yale University New Haven Connecticut 06520 USA Department of Applied Physics Yale University New Haven Connecticut 06520 USA

Previous studies have shown that the interiors of proteins are densely packed, reaching packing fractions that are as large as those found for static packings of individual amino-acid-shaped particles. How can the interiors of proteins take on such high packing fractions given that amino acids are connected by peptide bonds and many amino acids are hydrophobic with attractive interactions? We investigate this question by comparing the structural and mechanical properties of collapsed attractive disk-shaped bead-spring polymers to those of three reference systems: static packings of repulsive disks, of attractive disks, and of repulsive disk-shaped bead-spring polymers. We show that the attractive systems quenched to temperatures below the glass transition T≪Tg and static packings of both repulsive disks and bead-spring polymers possess similar interior packing fractions. Previous studies have shown that static packings of repulsive disks are isostatic at jamming onset, i.e., the number of interparticle contacts Nc matches the number of degrees of freedom, which strongly influences their mechanical properties. We find that repulsive polymer packings are hypostatic at jamming onset (i.e., with fewer contacts than degrees of freedom) but are effectively isostatic when including stabilizing quartic modes, which give rise to quartic scaling of the potential energy with displacements along these modes. While attractive disk and polymer packings are often considered hyperstatic with excess contacts over the isostatic number, we identify a definition for interparticle contacts for which they can also be considered as effectively isostatic. As a result, we show that the mechanical properties (e.g., scaling of the potential energy with excess contact number and low-frequency contribution to the density of vibrational modes) of weakly attractive disk and polymer packings are similar to those of isostatic repulsive disk and polymer packings. Our results demonstrate that static

关键词： Jamming Polymer folding Protein folding Single polymer chains

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Gallium Oxide as Photonic Integrated Platforms in the UV-Visible Spectra

Gallium Oxide as Photonic Integrated Platforms in the UV-Vis...

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2023 Conference on Lasers and Electro-Optics, CLEO 2023

作者： Zhou, Jingan Zhao, Xuan Xu, Rui Zhang, Xiang Fu, Kai Li, Tao Xu, Mingfei Luo, Shisong He, Ziyi Robinson, Jacob T. Zhu, Hanyu Ajayan, Pulickel M. Zhang, Xiaodong Zhao, Yuji Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Materials Science and NanoEngineering Rice University HoustonTX77005 United States School of Electrical Computer and Energy Engineering Arizona State University TempeAZ85287 United States Nanofabrication facility Suzhou Institute of Nano-Tech and Nano-Bionics Chinese Academy of Sciences Jiangsu Suzhou215123 China

We report the Ga2O3 as photonic integrated platforms and its nonlinear optical effects in the UV-visible spectra. A low propagation loss of 3.7 dB/cm and second-order susceptibility of x(2)=4.89xl03pm/V were obtained.... 详细信息

ISBN: (纸本)9781957171258

关键词： Gallium compounds

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Large effective magnetic fields from chiral phonons in rare-earth halides

arXiv

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arXiv 2023年

作者： Luo, Jiaming Lin, Tong Zhang, Junjie Chen, Xiaotong Blackert, Elizabeth R. Xu, Rui Yakobson, Boris I. Zhu, Hanyu Department of Materials Science and Nano Engineering Rice University HoustonTX77005 United States Applied Physics Graduate Program Rice University HoustonTX77005 United States

Time-reversal symmetry (TRS) is pivotal for materials’ optical, magnetic, topological, and transport properties. Chiral phonons, characterized by atoms rotating unidirectionally around their equilibrium positions, generate dynamic lattice structures that break TRS. Here we report that coherent chiral phonons, driven by circularly polarized terahertz light pulses, can polarize the paramagnetic spins in CeF3 like a quasi-static magnetic field on the order of 1 Tesla. Through time-resolved Faraday rotation and Kerr ellipticity, we found the transient magnetization is only excited by pulses resonant with phonons, proportional to the angular momentum of the phonons, and growing with magnetic susceptibility at cryogenic temperatures, as expected from the spin-phonon coupling model. The time-dependent effective magnetic field quantitatively agrees with that calculated from phonon dynamics. Our results may open a new route to directly investigate mode-specific spin-phonon interaction in ultrafast magnetism, energy-efficient spintronics, and non-equilibrium phases of matter with broken TRS. Copyright © 2023, The Authors. All rights reserved.

关键词： Phonons

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AI Aided GPR Data Multipath Summation Using x-t Stacking Weights

AI Aided GPR Data Multipath Summation Using x-t Stacking Wei...

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International Conference on Telecommunications and Signal Processing (TSP)

作者： Economou Nikos Nasir Sobhi Al Abri Said Bader Al Shaqsi Hamdan Hamdan Applied Geophysics Lab School of Mineral Resources Engineering Technical University of Crete Chania Greece Department of Earth Sciences Sultan Qaboos University College of Science Muscat Oman Department of Applied Physics and Astronomy Petroleum Geosciences and Remote Sensing Program Sharjah University UAE

ISBN: (数字)9798350365597

ISBN: (纸本)9798350365603

Migration velocity of Ground Penetrating Radar (GPR) data is a low wavenumber attribute crucial for migration. Obtaining a migration velocity model, which is considered closer to a Root Mean Square (RMS) model, from zero-offset (ZO) data requires analysis of the available diffractions whose density and (x, t) coverage is random. Thus, accuracy and efficiency of such a velocity model either for migration or its usage for interval velocity model estimation is not guaranteed. Here, with the aid of an Artificiaal Intelligence (AI) algorithm, which detects diffractions and usage of their kinematic information, we generate a diffraction velocity model used for the assignment of 2D weights for weighted multipath summation. The scope is to efficiently focus the scattered energy within a GPR section. We describe this methodology and demonstrate its application in enhancing the lateral continuity of reflections. We compare it with the multipath summation using lD weights with simulated data and present its application on marble assessment GPR data for imaging cracks in the subsurface structure.

关键词： Analytical models Diffraction Stacking Estimation Kinematics Data models Reflection

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Increased light-emission efficiency in disordered InGaN through the correlated reduction of recombination rates

arXiv

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arXiv 2023年

作者： Pant, Nick Kioupakis, Emmanouil Applied Physics Program University of Michigan Ann ArborMI48109 United States Department of Materials Science & Engineering University of Michigan Ann ArborMI48109 United States

Experiments have shown that the light-emission efficiency of indium gallium nitride (InGaN) light-emitting diodes improves with increasing indium concentration. It is widely thought that compositional fluctuations due to indium incorporation suppress diffusion of carriers to non-radiative centers, thus leading to defect-insensitive emission. However, recent experiments have challenged this hypothesis by revealing unexpectedly long diffusion lengths at room temperature. Here, we demonstrate an alternative mechanism involving the correlated reduction in radiative and nonradiative recombination rates that explains the increase in light-emission efficiency of InGaN with increasing indium concentration, without invoking the suppression of carrier diffusion. Our analysis challenges the notion that carrier localization gives rise to defect tolerance in InGaN. Copyright © 2023, The Authors. All rights reserved.

关键词： III-V semiconductors

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Partial observation can induce mechanistic mismatches in data-constrained models of neural dynamics 24

Partial observation can induce mechanistic mismatches in dat...

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Proceedings of the 38th International Conference on Neural Information Processing Systems

作者： William Qian Jacob A. Zavatone-Veth Benjamin S. Ruben Cengiz Pehlevan Biophysics Graduate Program and Kempner Institute for the Study of Natural and Artificial Intelligence Harvard University Cambridge MA John A. Paulson School of Engineering and Applied Sciences and Center for Brain Science Harvard University and Department of Physics Harvard University Cambridge MA Biophysics Graduate Program Harvard University Cambridge MA Kempner Institute for the Study of Natural and Artificial Intelligence and John A. Paulson School of Engineering and Applied Sciences and Center for Brain Science Harvard University Cambridge MA

ISBN: (纸本)9798331314385

One of the central goals of neuroscience is to gain a mechanistic understanding of how the dynamics of neural circuits give rise to their observed function. A popular approach towards this end is to train recurrent neural networks (RNNs) to reproduce experimental recordings of neural activity. These trained RNNs are then treated as surrogate models of biological neural circuits, whose properties can be dissected via dynamical systems analysis. How reliable are the mechanistic insights derived from this procedure? While recent advances in population-level recording technologies have allowed simultaneous recording of up to tens of thousands of neurons, this represents only a tiny fraction of most cortical circuits. Here we show that observing only a subset of neurons in a circuit can create mechanistic mismatches between a simulated teacher network and a data-constrained student, even when the two networks have matching single-unit dynamics. In particular, partial observation of models of low-dimensional cortical dynamics based on functionally feedforward or low-rank connectivity can lead to surrogate models with spurious attractor structure. Our results illustrate the challenges inherent in accurately uncovering neural mechanisms from single-trial data, and suggest the need for new methods of validating data-constrained models for neural dynamics.

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On The Mechanism of Nucleation in Pulsed-laser Quenched Si Films on SiO 2

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MRS Online Proceedings Library 2021年第1期1245卷 1-6页

作者： Y. Deng Q. Hu U. J. Chung A. M. Chitu A. B. Limanov S. James Im Program in Materials Science and Engineering Department of Applied Physics and Applied Mathematics Columbia University New York USA

We have investigated the solid nucleation mechanism in laser-quenched Si films on SiO2. Previously neglected experimental steps, consisting of BHF-etching and irradiation in vacuum, were implemented to reduce potential extrinsic influences. The resulting experimental findings and computational analysis lead us to conclude that solid nucleation consistently takes place heterogeneously at, and only at, the bottom liquid Si-SiO2 interface.

关键词： Si thin film nucleation & growth

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Advancing hybrid quantum-classical algorithms via mean operators

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Physical Review A 2023年第1期108卷 L010401-L010401页

作者： Donggyu Kim Pureum Noh Hyun-Yong Lee Eun-Gook Moon Department of Physics Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Korea Department of Applied Physics Graduate School Korea University Sejong 30019 Korea Division of Display and Semiconductor Physics Korea University Sejong 30019 Korea Interdisciplinary Program in E·ICT-Culture-Sports Convergence Korea University Sejong 30019 Korea

Hybrid quantum-classical algorithms have been suggested to control the quantum entanglement of many-body systems in noisy intermediate-scale quantum technology, and yet their applicability is limited by the numbers of qubits and quantum operations. Here, we propose a mean-operator theory which overcomes limitations by combining the advantages of hybrid algorithms and standard mean-field theory. We demonstrate that an introduction of a mean operator prepares an entangled target many-body state with a significantly reduced number of quantum operations. We also show that a class of mean operators is expressed as time-evolution operators, which indicates that our theory is directly applicable to quantum simulations with Rydberg atoms and trapped ions.

关键词： Atom & ion trapping & guiding Quantum algorithms Quantum phase transitions Quantum simulation Strongly correlated systems Ultracold gases Symmetries in condensed matter Tensor network methods Variational wave functional methods

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Alert system with IoT Techniques for Stray Children

Alert system with IoT Techniques for Stray Children

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Cybernetics and Innovations (ICCI), International Conference on

作者： Patiyuth Pramkeaw Thittaporn Ganokratanaa Thidarat Pinthong Napathsorn Kitprasert Media Technology Program King Mongkut's University of Technology Thonburi Bangkok Thailand Applied Computer Science Program King Mongkut's University of Technology Thonburi Bangkok Thailand Dep. of Business Information Management Phetchaburi Rajabhat University Phetchaburi Thailand

The purpose of this research was to design, produce and evaluate a stray child warning system. The device has been designed by using 2 ESP8266 boards to receive signals as specified. The system will notify the information via Line Notify to let users know how far the board that acts as a Client is from the board that acts as an Access Point. Expressed in meters (m) in the notification line notify process. The test results of the system in terms of signal transmission between the Access Point and the Client can work well. Buzzer speaker and LED notification light according to the specified distance every time. Notifications to LINE Notify to mobile phones can be done every time.

关键词： Meters Pediatrics Technological innovation LED lamps Alarm systems Turning Mobile handsets

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Topology of three-dimensional Dirac semimetals and quantum spin Hall systems without gapless edge modes

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Physical Review Research 2023年第1期5卷 L012019-L012019页

作者： Alexander C. Tyner Shouvik Sur Danilo Puggioni James M. Rondinelli Pallab Goswami Graduate Program in Applied Physics Northwestern University Evanston Illinois 60208USA Department of Physics and Astronomy Northwestern University Evanston Illinois 60208 USA Department of Materials Science and Engineering Northwestern University Illinois 60208 USA Northwestern Argonne Institute for Science and Engineering Evanston Illinois 60208 USA

The quantum spin Hall states are usually expected to possess gapless, helical edge modes. We show that the generic, n-fold-symmetric, momentum planes of three-dimensional, stable Dirac semimetals, which are orthogonal to the direction of nodal separation are examples of generalized quantum spin Hall systems, that possess quantized, spin or relative Chern numbers as bulk topological invariants, and gapped edge modes. We demonstrate these planes and the celebrated Bernevig-Zhang-Hughes model support identical quantized, non-Abelian Berry flux of magnitude 2π. Hence, they display identical quantized, topological response such as spin-charge separation and pumping of one Kramers-pair or SU(2) doublet, when probed with a magnetic flux tube. The Dirac points are identified as unit-strength, monopoles of SO(5) Berry connection, describing topological phase transitions between generalized quantum spin Hall and trivial insulators. Our work identifies precise bulk invariant and quantized response of Dirac semimetals, which are not diagnosed by nested Wilson loops and filling anomaly of corner-localized-states, and shows that many two-dimensional higher-order topological insulators can be understood as generalized quantum spin Hall systems.

关键词： Fractionalization Geometric & topological phases Spintronics Topological insulators Topological phase transition Topological phases of matter

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