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Eigenvalue-Based Micromagnetic Analysis of Switching in Spin-Torque-Driven Structures

Physical Review Applied 2022年第3期17卷 034016-034016页

作者： Z. Lin I. Volvach X. Wang V. Lomakin Department of Electrical and Computer Engineering University of California San Diego La Jolla California 92093 USA Center for Memory and Recording Research La Jolla California 92093 USA Materials Science and Engineering Program University of California San Diego La Jolla California 92093 USA

We present an eigenvalue-based approach for studying the magnetization dynamics in magnetic nanostructures driven by spintronic excitations, such as spin-transfer torque and spin-orbit torque. The approach represents the system dynamics in terms of normal oscillation modes (eigenstates) with corresponding complex eigenfrequencies. The dynamics is driven by a small number of active eigenstates and often considering just a single eigenstate is sufficient. We develop a perturbation theory that provides semianalytical dynamic solutions by using eigenstates for the case in the absence of damping and spintronic excitations as a basis. The approach provides useful insights into dynamics in such systems and allows solving several difficulties in their modeling, such as extracting the switching current in magnetic random-access memories and understanding switching mechanisms. We show that the presented approach directly predicts the critical switching current, i.e., switching current for an infinite time. The approach also provides solutions for the switching dynamics allowing the switching current to be obtained for a finite switching time, provided that the system symmetry is broken, e.g., by tilting the polarizer, so that switching by a finite pulse is possible.

关键词： Magnetization dynamics Spin transfer torque Spin-orbit torque Spintronics Devices for digital logic, storage & processing Landau-Lifschitz-Gilbert equation Micromagnetic modeling Perturbation theory

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Cross-system biological image quality enhancement based on the generative adversarial network as a foundation for establishing a multi-institute microscopy cooperative network

arXiv

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arXiv 2024年

作者： Panek, Dominik Rząca, Carina Szczypior, Maksymilian Sorysz, Joanna Misztal, Krzysztof Baster, Zbigniew Rajfur, Zenon Doctoral School of Exact and Natural Sciences Jagiellonian University ul. Lojasiewicza 11 Kraków30-348 Poland Department of Molecular and Interfacial Biophysics Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University ul. Lojasiewicza 11 Kraków30‑348 Poland Undergraduate Program in Biophysics Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University ul. Lojasiewicza 11 Kraków30‑348 Poland Undergraduate program in Biomedical Engineering Faculty of Electrical Engineering Automatics Computer Science and Biomedical Engineering AGH University of Science and Technology Al. A. Mickiewicza 30 Building B-1 Kraków30-059 Poland Division of Computational Mathematics Faculty of Mathematics and Computer Science Jagiellonian University 6 Lojasiewicza St. Kraków Poland

High-quality fluorescence imaging of biological systems is limited by processes like photobleaching and phototoxicity, and also in many cases, by limited access to the latest generations of microscopes. Moreover, low temporal resolution can lead to a motion blur effect in living systems. Our work presents a deep learning (DL) generative-adversarial approach to the problem of obtaining high-quality (HQ) images based on their low-quality (LQ) equivalents. We propose a generative-adversarial network (GAN) for contrast transfer between two different separate microscopy systems: a confocal microscope (producing HQ images) and a wide-field fluorescence microscope (producing LQ images). Our model proves that such transfer is possible, allowing us to receive HQ-generated images characterized by low mean squared error (MSE) values, high structural similarity index (SSIM), and high peak signal-to-noise ratio (PSNR) values. For our best model in the case of comparing HQ-generated images and HQ-ground truth images, the median values of the metrics are 6·10-4, 0.9413, and 31.87, for MSE, SSIM, and PSNR, respectively. In contrast, in the case of comparison between LQ and HQ ground truth median values of the metrics are equal to 0.0071, 0.8304, and 21.48 for MSE, SSIM, and PSNR respectively. Therefore, we observe a significant increase ranging from 14% to 49% for SSIM and PSNR respectively. These results, together with other single-system cross-modality studies, provide proof of concept for further implementation of a cross-system biological image quality enhancement. © 2024, CC BY-SA.

关键词： Fluorescence imaging

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Evaluating the Robustness of Complementary Channel Ferroelectric FETs Against Total Ionizing Dose Towards Radiation-Tolerant Embedded Nonvolatile Memory

TechRxiv

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TechRxiv 2023年

作者： Jiang, Zhouhang Guo, Zixiang Luo, Xuyi Sayed, Munazza Faris, Zubair Mulaosmanovic, Halid Duenkel, Stefan Soss, Steven Beyer, Sven Gong, Xiao Kurinec, Santosh Narayanan, Vijaykrishnan Amrouch, Hussam Zhang, Enxia Fleetwood, Daniel M. Schrimpf, Ronald D. Ni, Kai The Microsystems Engineering Ph.D. Program The Mechanical Engineering Rochester Institute of Technology RochesterNY14623 United States The Department of Electrical and Computer Engineering Vanderbilt University NashvilleTN37235 United States University of Stuttgart Stuttgart70174 Germany Germany The Munich Institute of Robotics and Machine Intelligence Arcisstrasse 21 Munich80333 Germany The GlobalFoundries Fab1 LLC Dresden Germany The Department of Electrical Computer Engineering National University of Singapore 119077 Singapore The Department of Computer Science and Engineering Penn State University University ParkPA16802 United States The Department of Electrical and Microelectric Engineering Rochester Institute of Technology RochesterNY14623 United States

In this work, a thorough assessment of the robustness of complementary channel HfO2 ferroelectric FET (FeFET) against total ionizing dose (TID) radiation is conducted, with the goal of determining its suitability for use as high-performance and energy-efficient embedded nonvolatile memory (eNVM) for space applications. We demonstrate that: i) ferroelectric HfO2 thin film is robust against X-ray and proton irradiation;ii) FeFET exhibits a polarization state dependent radiation sensitivity where the high-VTH (HVT) state sees noticeable negative VTH shift and low-VTH (LVT) is immune to irradiation, irrespective of the channel type;iii) the state dependence is ascribed to the depolarization field in the HVT, which points toward the channel and facilitates the transport and trapping of radiation-generated holes close to the channel. In the future, radiation hardening techniques need to be considered. © 2023, CC BY.

关键词： Radiation effects

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Microstructural analysis and electro-optic properties of thick epitaxial BaTiO3 films integrated on silicon (001)

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Physical Review Materials 2022年第9期6卷 095201-095201页

作者： Marc Reynaud Zuoming Dong Hyoju Park Wente Li Agham B. Posadas Jamie H. Warner Daniel Wasserman Alexander A. Demkov Department of Physics University of Texas at Austin Austin Texas 78712 USA Department of Electrical and Computer Engineering University of Texas at Austin Austin Texas 78758 USA Walker Department of Mechanical Engineering University of Texas at Austin Austin Texas 78712 USA Materials Science and Engineering Program and Texas Materials Institute The University of Texas at Austin Texas 78712 USA

Recent advances in epitaxial oxide deposition have enabled the fabrication of thick films of ferroelectric perovskite BaTiO3 capable of providing a robust electro-optic response via the Pockels effect in silicon photonic devices. We report a microstructure analysis of such films integrated on Si(001) by molecular beam epitaxy, showing how the crystallographic and polarization orientation change as a function of thickness. The measured electro-optic properties of the film correlate well with the microstructural analysis and demonstrate the potential of Si-integrated BaTiO3 for silicon photonics. An effective Pockels coefficient of up to 268 pm/V has been demonstrated in 110-nm-thick films in transmission measurements and 352 pm/V in waveguide measurements.

关键词： Ferroelectricity Photonics Epitaxy

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Integration of allocentric and egocentric visual information in a convolutional/multilayer perceptron network model of goal-directed gaze shifts

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Cerebral Cortex 2022年第3期3卷 026-026页

作者： Abedi Khoozani, Parisa Bharmauria, Vishal Schutz, Adrian Wildes, Richard P Crawford, J. Douglas Centre for Vision Research and Vision: Science to Applications (VISTA) Program York University Toronto M3J 1P3 ON Canada Department of Neurophysics Phillips-University Marburg Marburg 35037 Germany Department of Electrical Engineering and Computer Science York University Toronto M3J 1P3 ON Canada Departments of Psychology Biology and Kinesiology & Health Sciences York University Toronto M3J 1P3 ON Canada

Allocentric (landmark-centered) and egocentric (eye-centered) visual codes are fundamental for spatial cognition, navigation, and goal-directed movement. Neuroimaging and neurophysiology suggest these codes are initially segregated, but then reintegrated in frontal cortex for movement control. We created and validated a theoretical framework for this process using physiologically constrained inputs and outputs. To implement a general framework, we integrated a convolutional neural network (CNN) of the visual system with a multilayer perceptron (MLP) model of the sensorimotor transformation. The network was trained on a task where a landmark shifted relative to the saccade target. These visual parameters were input to the CNN, the CNN output and initial gaze position to the MLP, and a decoder transformed MLP output into saccade vectors. Decoded saccade output replicated idealized training sets with various allocentric weightings and actual monkey data where the landmark shift had a partial influence (R2 = 0.8). Furthermore, MLP output units accurately simulated prefrontal response field shifts recorded from monkeys during the same paradigm. In summary, our model replicated both the general properties of the visuomotor transformations for gaze and specific experimental results obtained during allocentric-egocentric integration, suggesting it can provide a general framework for understanding these and other complex visuomotor behaviors. © 2022 The Author(s). Published by Oxford University Press.

关键词： allocentric convolutional network egocentric multilayer perceptron saccades

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Biophysics of amplitude-modulated giga-hertz electromagnetic waves stimulation

Biophysics of amplitude-modulated giga-hertz electromagnetic...

引用

Asilomar Conference on Signals, Systems & computers

作者： Fatima Ahsan Aravind C. Govindaraju Robert M. Raphael Taiyun Chi Sameer A. Sheth Wayne Goodman Behnaam Aazhang Department of Electrical and Computer Engineering Rice University Houston TX USA Applied Physics Graduate Program Smalley-Curly Institute Rice University Houston TX Department of Bioengineering Rice University Houston TX USA Department of Neurosurgery Baylor College of Medicine Houston TX USA Menninger Department of Psychiatry and Behavioral Sciences Baylor College of Medicine Houston TX USA

This paper presents the biophysical modeling for neuronal stimulation caused by amplitude-modulated giga-hertz (GHz) electromagnetic (EM) waves. We model a 1D cable equation for electrical signal propagation in a vestibular ganglion neuronal fiber and use Hodgkin-Huxley formalism to model voltage-dependent channel conductances. We find out that for a given stimulation signal strength, the GHz waveform amplitude-modulated at a low frequency of Δf causes neuronal firing with the frequency of Δf whereas the continuous wave GHz did not elicit any neuronal firing. Moreover, the voltage-dependent channel gating dynamics of the Δf amplitude-modulated GHz stimulation matches that of a simple low frequency stimulation at Δf. Additionally, we find that the modulation depth controls the firing rate of the neurons. The significance of this property is that the amplitude modulation caused by the interference of two similar high frequency signals could be leveraged to focally excite neurons at depth without stimulating overlying cortical regions. These theoretical predictions based on the Hodgkin-Huxley model can later be tested experimentally.

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A Neuroimaging Yolov8-Based Cad Framework for Anosmia Grading in Covid-19

A Neuroimaging Yolov8-Based Cad Framework for Anosmia Gradin...

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IEEE International Conference on Image Processing

作者： Hossam Magdy Balaha Mayada Elgendy Ahmed Alksas Mohamed Shehata Norah Saleh Alghamdi Fatma Taher Mohammed Ghazal Mahitab Ghoneim Eslam Hamed Fatma Sherif Ahmed Elgarayhi Mohammed Sallah Mohamed Abdelbadie Salem Elsharawy Kamal Harpal Sandhu Ayman El-Baz Department of Bioengineering J.B. Speed School of Engineering University of Louisville Louisville USA Physics Department Applied Theoretical Physics Research Group Faculty of Science Mansoura University Egypt Department of Computer Sciences College of Computer and Information Sciences Princess Nourah bint Abdulrahman University Saudi Arabia The College of Technological Innovation Zayed University Dubai UAE Electrical Computer and Biomedical Engineering Depatrment Abu Dhabi University UAE Department of Radiology Faculty of Medicine Mansoura University Egypt Otolaryngology Department Faculty of Medicine Mansoura University Egypt Department of Physics College of Sciences University of Bisha Saudi Arabia

ISBN: (数字)9798350349399

ISBN: (纸本)9798350349405

COVID-19, a respiratory illness caused by SARS-CoV-2, has brought attention to a common symptom: loss of smell and taste. Anosmia, a prevalent symptom of COVID-19, varies in severity from mild to severe, necessitating accurate diagnostic tools. The study proposes a novel framework for predicting COVID-19 anosmia severity utilizing YOLOv8 for classification and EigenCAM for interpretability. YOLOv8, optimized for object detection, is adapted for classification tasks using advanced architectural enhancements and mosaic augmentation. EigenCAM provides interpretability by highlighting image regions crucial for predictions, aiding clinical decision-making. Evaluation across multiple YOLOv8 model sizes using DTI and FLAIR modalities reveals robust performance, with the Large model excelling in DTI and the Nano model in FLAIR. Compared to our previous work, the framework significantly enhances accuracy and interpretability in predicting anosmia severity, marking a substantial advancement in medical image analysis. This study underscores the potential of deep learning for precise and interpretable medical diagnostics, offering insights into anosmia severity prediction.

关键词： COVID-19 Deep learning Solid modeling Adaptation models Accuracy Robustness Medical diagnosis

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Impact of Constant Bias Stress on Reliability of A-Igzo Thin-Film Transistors

SSRN

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SSRN 2023年

作者： Gutierrez-Heredia, Gerardo Rodriguez-Lopez, Ovidio Rocha-Flores, Pedro Emanuel Voit, Walter E. Departamento de Fisica de la Universidad de Sonora Hermosillo Sonora 83000 Mexico Department of Electrical and Computer Engineering The University of Texas at Dallas RichardsonTX75080 United States Department of Bioengineering The University of Texas at Dallas RichardsonTX75080 United States Department of Materials Science and Engineering The University of Texas at Dallas RichardsonTX75080 United States

In this study, the electrical behavior of amorphous-indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) was analyzed under different applied voltages. These TFTs were fabricated on a polymer substrate using full photolithographic processes. The electrical performance was monitored under constant bias stress for 10,000 seconds and the analysis revealed relatively high field-effect mobility (>10 cm2/Vs) for the a-IGZO TFTs when higher voltages (>5 V) were applied. Additionally, the experimental results demonstrated shifts in the threshold voltage, field-effect mobility, and saturation drain current, which exhibited a strong dependence on the applied voltage. After 10,000 seconds, the threshold voltage shift varied by 0.5 V for the lowest applied voltage and exceeded 5 V for the higher values. Furthermore, the electrical analysis indicated a significant reduction in the lifetime of a-IGZO TFTs when the applied voltage exceeded 15 V. Understanding these changes induced by the constant electric field at the gate contact can provide insights into the reliability and lifetime prediction of novel devices intended for wearable, flexible, and biomedical applications. © 2023, The Authors. All rights reserved.

关键词： Thin film transistors

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Why Room Temperature GeSn Lasers Need Carbon

Why Room Temperature GeSn Lasers Need Carbon

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IEEE International Conference on Group IV Photonics

作者： Tuhin Dey Augustus W. Arbogast Qian Meng Shamim Reza Aaron Muhowski Joshua Cooper Rachel S. Goldman Thales Borrely Seth R. Bank Mark A. Wistey Materials Science Engineering and Commercialization Program Texas State University San Marcos Texas USA Department of Physics Texas State University San Marcos Texas USA Department of Electrical and Computer Engineering University of Texas at Austin Austin Texas USA Department of Materials Science and Engineering University of Michigan Ann Arbor MI USA Departments of MSE Physics and EECS University of Michigan Ann Arbor MI USA Department of Physics and MSEC Program Texas State University San Marcos Texas USA

Device models show GeSn lasers are limited by weak electron and photon confinement. Adding carbon offers strong conduction band offsets, freeing SiGeSn layers for separate confinement heterostructures, reducing thresh...

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Reducing Effective System Dimensionality with Long-Range Collective Dipole-Dipole Interactions

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Physical Review Letters 2024年第17期132卷 173803-173803页

作者： Ashwin K. Boddeti Yi Wang Xitlali G. Juarez Alexandra Boltasseva Teri W. Odom Vladimir Shalaev Hadiseh Alaeian Zubin Jacob Elmore Family School of Electrical and Computer Engineering Purdue University West Lafayette Indiana 47907 USA Birck Nanotechnology Center Purdue University West Lafayette Indiana 47907 USA Graduate Program in Applied Physics Northwestern University Evanston Illinois 60208 USA Department of Materials Science and Engineering Northwestern University Evanston Illinois 60208 USA Department of Chemistry Northwestern University Evanston Illinois 60208 USA School of Physics and Astronomy Purdue University West Lafayette Indiana 47907 USA

Dimensionality plays a crucial role in long-range dipole-dipole interactions (DDIs). We demonstrate that a resonant nanophotonic structure modifies the apparent dimensionality in an interacting ensemble of emitters, as revealed by population decay dynamics. Our measurements on a dense ensemble of interacting quantum emitters in a resonant nanophotonic structure with long-range DDIs reveal an effective dimensionality reduction to d¯=2.20(12), despite the emitters being distributed in 3D. This contrasts with the homogeneous environment, where the apparent dimension is d¯=3.00. Our work presents a promising avenue to manipulate dimensionality in an ensemble of interacting emitters.

关键词： Light-matter interaction Long-range interactions Metamaterials Optics & lasers Photonics Plasmonics Quantum optics

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