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Observation of Photonic Chiral Flatbands

Physical Review Letters 2025年第10期134卷 103801-103801页

作者： Minho Choi Andrea Alù Arka Majumdar Department of Electrical and Computer Engineering University of Washington Seattle Washington 98195 USA Photonics Initiative Advanced Science Research Center City University of New York New York New York 10031 USA and Physics Program Graduate Center City University of New York New York New York 10031 USA Department of Electrical and Computer Engineering University of Washington Seattle Washington 98195 USA and Department of Physics University of Washington Seattle Washington 98195 USA

Distinct selectivity to the spin angular momenta of photons has garnered significant attention in recent years, for its relevance in basic science and for imaging and sensing applications. While nonlocal metasurfaces with strong chiral responses to the incident light have been reported, these responses are typically limited to a narrow range of incident angles. In this study, we demonstrate a nonlocal metasurface that showcases strong chirality, characterized by circular dichroism (∼0.6), over a wide range of incident angles ±5°. Its quality factor, circular dichroism and resonant frequency can be optimized by design. These findings pave the way to further advance the development of valley-selective optical cavities and augmented reality applications.

关键词： Natural frequencies

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Gelatine-Based Phantom for Simulating A-Line Reverberations in Lung Ultrasonogram 8

Gelatine-Based Phantom for Simulating A-Line Reverberations ...

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8th International Conference on Instrumentation, Control, and Automation, ICA 2023

作者： Nabila, Citra Alfa Bahri, Saeful Adhika, Damar Rastri Suprijanto, Suprijanto Institut Teknologi Bandung Master Program of Instrumentation and Control Faculty of Industrial Technology Bandung Indonesia Institut Teknologi Bandung Doctoral Program of Engineering Physics Faculty of Industrial Technology Bandung Indonesia Institut Teknologi Bandung Advanced Functional Material Research Group Faculty of Industrial Technology Research Center of Nanosciences and Nanotechnology Bandung Indonesia Institute Teknologi Bandung Instrumentation and Control Research Group Faculty of Industrial Technology Bandung Indonesia

ISBN: (纸本)9798350301274

To understand typical features that could be imaged using ultrasonography (USG) in the training phases of medical students or practitioners, a lung phantom is required. The research team suggests using a gelatine-based phantom to demonstrate A-line reverberations in lung ultrasound. The ordinary gelatine-based phantom has the disadvantage of being too fragile and prone to breaking. The specific process was attempted on gelatine with a plasticizer and carrier agent to increase the gelatine's strength and elasticity. To simulate the A-lines, two different textures of gelatine layers are used, with other processes in between. A special procedure was used to set off the various acoustic impedances affecting reverberation physics with those varied textures. Based on USG image analysis, the proposed lung phantom material has some advantages: it is inexpensive and easy to find, despite its complicated procedures. Furthermore, it could be processed to have the desired properties and recycled after hardening with water bath melting. © 2023 IEEE.

关键词： Textures

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Spin nematic order and superconductivity in J1-J2 Kondo lattice model on square lattice

arXiv

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arXiv 2025年

作者： Uraga, Sho Tada, Yasuhiro Quantum Matter Program Graduate School of Advanced Science and Engineering Hiroshima University Hiroshima Higashihiroshima739-8530 Japan Institute for Solid State Physics University of Tokyo Kashiwa277-8581 Japan

We investigate competition and cooperation of magnetic frustration and the Kondo effect in the J1-J2 Kondo lattice model on the square lattice at zero temperature. In this model, the frustrated interactions J1,J2 between the localized spins stabilize spin nematic orders, while the Kondo coupling favors local spin singlets. Using the slave boson mean field approximation, we find that the spin nematic order remains stable against small Kondo coupling, and the localized spins and the conduction electrons are effectively decoupled. On the other hand, a standard Fermi liquid state is formed for sufficiently strong Kondo interactions. Furthermore, in an intermediate region with moderate Kondo coupling, the spin nematic order and the Kondo effect coexist, and superconducting pairing of the conduction electrons is induced by the spinon pairing. We discuss the ground state phase diagram and nature of the quantum phase transitions between the different superconducting states. Copyright © 2025, The Authors. All rights reserved.

关键词： Fermi liquids

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Application of the bRapid Fission Matrix Burnup Methodology to the JSI TRIGA Mark II Research Reactor

Application of the bRapid Fission Matrix Burnup Methodology ...

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2022 International Conference on physics of Reactors, PHYSOR 2022

作者： Pungerčič, Anže Haghighat, Alireza Snoj, Luka "Jožef Stefan" Institute Reactor Physics Department Jamova cesta 39 Ljubljana1000 Slovenia University of Ljubljana Faculty of Mathematics and Physics Jadranska ulica 19 Ljubljana1000 Slovenia Nuclear Engineering Program Virginia Tech 7054 Haycock Road Falls ChurchVA22043 United States

ISBN: (纸本)9780894487873

The novel burnup methodology, bRAPID, of the RAPID code system has been applied to the TRIGA Mark II research reactor at the "Jozef Stefan" Institute. This paper presents the first step in our goal for on-line determination of isotope inventory and burnup, that the RAPID code system with its Fission Matrix method enables. Burnup analysis of changes in Fission Matrix (FM) coefficients due to TRIGA fuel burnup at different irradiation times and specific power distribution in the reactor core is presented. Our results demonstrate that primary contribution for changes of FM coefficients is the burnup of the destination regions, while the spectrum differences, that arise due to fuel's core location, have negligible effect on FM coefficients. © 2022 Proceedings of the International Conference on physics of Reactors, PHYSOR 2022. All Rights Reserved.

关键词： Burnup calculations Fission Matrix MRT methodology RAPID TRIGA reactor

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Hydrodynamic fluctuations and ultra-central flow puzzle in heavy-ion collisions

arXiv

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arXiv 2023年

作者： Kuroki, Kenshi Sakai, Azumi Murase, Koichi Hirano, Tetsufumi Department of Physics Sophia University Tokyo102-8554 Japan Physics Program Graduate School of Advanced Science and Engineering Hiroshima University Hiroshima739-8526 Japan Yukawa Institute for Theoretical Physics Kyoto University Kyoto606-8502 Japan

One of the long-standing problems in the field of high-energy heavy-ion collisions is that the dynamical models based on viscous hydrodynamics fail to describe the experimental elliptic flow v2 and the triangular flow v3 simultaneously in ultra-central collisions. The problem, known as the ultra-central flow puzzle, is specifically that hydrodynamics-based models predict the flow ratio of the two-particle cumulant method v2{2}/v3{2} > 1 while v2{2}/v3{2} ∼ 1 in the experimental data. In this Letter, we focus on the effects of hydrodynamic fluctuations during the space-time evolution of the QGP fluid on the flow observables in the ultracentral collisions. Using the (3+1)-dimensional integrated dynamical model which includes relativistic fluctuating hydrodynamics, we analyze the anisotropic flow coefficients vn{2} in 0–0.2% central Pb+Pb collisions at √sNN = 2.76 TeV. We find that the hydrodynamic fluctuations decrease the model overestimate of v2{2}/v3{2} from the experimental data by about 19% within the present setup of η/s = 1/2π. This means that the hydrodynamic fluctuations qualitatively have an effect to improve the situation for the puzzle, but the effect of the hydrodynamic fluctuations alone is quantitatively insufficient to resolve the puzzle. The decrease of the ratio largely depends on the shear viscosity η/s, which calls for future comprehensive analyses with, for example, a realistic temperature-dependent viscosity. Copyright © 2023, The Authors. All rights reserved.

关键词： Hydrodynamics

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Measurement of Water Diffusion Coefficient in Cross-Linked Gelatins Using the Terahertz Time-Domain Spectroscopy Technique

Measurement of Water Diffusion Coefficient in Cross-Linked G...

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CLEO: Applications and Technology in CLEO 2024, CLEO: A and T 2024 - Part of Conference on Lasers and Electro-Optics

作者： Walden, D. Chakraborty, D. Cheng, J. Straksys, A. Stirke, A. Melo, W.C.M.A. Jukna, A. Komissarov, I. Sobolewski, Roman Department of Physics and Astronomy University of Rochester RochesterNY14627 United States Laboratory for Laser Energetics University of Rochester RochesterNY14623-1299 United States Materials Science Graduate Program University of Rochester RochesterNY14627 United States State Research Institute Center for Physical Sciences & Technology Vilnius Lithuania Department of Physics Vilnius Gediminas Technical University Vilnius Lithuania Department of Electrical and Computer Engineering University of Rochester RochesterNY14627 United States

A novel method has been developed to evaluate the water diffusion dynamics in gelatin-based gels, based on transient terahertz time-domain spectroscopy measurements. Such gels are widely used models for human skin. &#... 详细信息

关键词： Terahertz spectroscopy

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Information geometry of the retinal representation manifold 23

Information geometry of the retinal representation manifold

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Proceedings of the 37th International Conference on Neural Information Processing Systems

作者： Xuehao Ding Dongsoo Lee Joshua B. Melander George Sivulka Surya Ganguli Stephen A. Baccus Department of Applied Physics Stanford University Neurosciences Phd Program Stanford University Department of Electrical Engineering Stanford University Department of Neurobiology Stanford University

The ability for the brain to discriminate among visual stimuli is constrained by their retinal representations. Previous studies of visual discriminability have been limited to either low-dimensional artificial stimuli or pure theoretical considerations without a realistic encoding model. Here we propose a novel framework for understanding stimulus discriminability achieved by retinal representations of naturalistic stimuli with the method of information geometry. To model the joint probability distribution of neural responses conditioned on the stimulus, we created a stochastic encoding model of a population of salamander retinal ganglion cells based on a three-layer convolutional neural network model. This model not only accurately captured the mean response to natural scenes but also a variety of second-order statistics. With the model and the proposed theory, we computed the Fisher information metric over stimuli to study the most discriminable stimulus directions. We found that the most discriminable stimulus varied substantially across stimuli, allowing an examination of the relationship between the most discriminable stimulus and the current stimulus. By examining responses generated by the most discriminable stimuli we further found that the most discriminative response mode is often aligned with the most stochastic mode. This finding carries the important implication that under natural scenes, retinal noise correlations are information-limiting rather than increasing information transmission as has been previously speculated. We additionally observed that sensitivity saturates less in the population than for single cells and that as a function of firing rate, Fisher information varies less than sensitivity. We conclude that under natural scenes, population coding benefits from complementary coding and helps to equalize the information carried by different firing rates, which may facilitate decoding of the stimulus under principles of information maximizatio

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On the maximum of cotangent sums related to the Riemann hypothesis in rational numbers in short intervals

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Moscow Journal of Combinatorics and Number Theory 2022年第4期10卷 303-313页

作者： Maier, Helmut Rassias, Michael Th. Department of Mathematics University of Ulm Ulm Germany Department of Mathematics and Engineering Sciences Hellenic Military Academy Athens Greece Moscow Institute of Physics and Technology Dolgoprudny Russian Federation Program in Interdisciplinary Studies Institute for Advanced Study Princeton NJ United States

Cotangent sums play a significant role in the Nyman–Beurling criterion for the Riemann hypothesis. Here we investigate the maximum of the values of these cotangent sums over various sets of rational numbers in short ... 详细信息

关键词： Cotangent sums Estermann’s zeta function Kloosterman sums Nyman–Beurling criterion Riemann hypothesis Riemann zeta function

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Enhanced fast charging capabilities in natural graphite/iron cross-linked pectin electrodes for lithium-ion batteries

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Materials Advances 2024年第17期5卷 6820-6829页

作者： Chung, Chin-Yi Chen, Wei-Ming Chen, Yan-Ruei Chen, Liang-Yu Su, Yu-Hsuan Chi, Po-Wei Wu, Phillip M. Chang-Liao, Kuei-Shu Tang, Hong-Yi Wu, Maw-Kuen Institute of Physics Academia Sinica 128 Section 2 Academia Road Taipei11529 Taiwan Nano Science and Technology Program Taiwan International Graduate Program Academia Sinica and National Tsing Hua University 128 Section 2 Academia Road Taipei11529 Taiwan Department of Engineering and System Science National Tsing Hua University 101 Section 2 Kuang-Fu Road Hsinchu300044 Taiwan College of Science National Chung Hsing University 145 Xingda Road South District Taichung402 Taiwan Department of Applied Chemistry National Chi-Nan University 1 University Road Puli Nantou545301 Taiwan

Rapid charging capabilities are required for the broader adoption of lithium-ion batteries in emerging technologies such as electric vehicles. Although commercial graphite anodes provide a high energy density, their limitations in quick charging warrant the exploration of novel materials. This study extends prior research on the use of pectin, a natural polysaccharide, as an organic binder for graphite anodes. By introducing iron into pectin, we propose a unique ion-crosslinking mechanism that causes the graphite anode to exhibit pseudocapacitive Li storage. Our findings, corroborated by 3D Bode analysis and AC impedance spectra, revealed a positive correlation between the iron ion and the pseudocapacitive vertex in the graphite reaction. Compared with conventional binders, graphite electrodes utilizing iron-doped pectin demonstrated superior initial and stable capacities, reaching 450 mA h g−1 after 100 cycles at 1C. This study highlights the synergistic effect of pectin and iron ions, offering a new avenue for high-performance, rapid-charging, and environmentally sustainable lithium-ion batteries. © 2024 RSC.

关键词： Lithium-ion batteries

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Enhancement of superconducting transition temperature in Nb/Pd bilayers upon rapid thermal hydrogenation

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Physical Review B 2023年第10期108卷 104502-104502页

作者： Junjie Li Ali C. Basaran Ralph El Hage Ivan K. Schuller Department of Physics and Center for Advanced Nanoscience University of California–San Diego La Jolla California 92093 USA Materials Science and Engineering Program University of California–San Diego La Jolla California 92093 USA

Recent discoveries of high-Tc superconducting hydrides at high pressure have opened up new possibilities for improving the superconducting transition temperature (Tc) using hydrogenation. Here, a unique thermodynamic approach is developed based on the concept of rapid thermal annealing and is adopted to study the hydrogenation effect on the superconducting properties of Nb/Pd bilayer films. Below 300∘C annealing temperatures, the Tc is enhanced from 8.77 to 9.06 K and is correlated with the compression of the Nb unit cell. A weak lattice expansion occurs at higher annealing temperatures, and the Tc is gradually suppressed. Furthermore, the rapid thermal hydrogenation affects the Tc differently depending on the substrate on which the Nb/Pd bilayers are grown. For the c-cut Al2O3 substrate, the Tc reduction starts at 250∘C, while for the r-cut Al2O3, this occurs at 350∘C. We associate these features with the elastic behavior of Nb film upon hydrogenation. A proposed model shows that the increase of Tc could be caused by the compressive stress related to the rapid nucleation of hydrides or the removal of impurities. Our discoveries provide insights into how superconductivity can be manipulated by rapid thermal hydrogenation.

关键词： Superconductivity Elemental superconductors Thin films Film deposition Heat treatment X-ray diffraction

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