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Three-Dimensional Refractive Index Estimation Based on Non-interferometric Optical Diffraction Tomography with Angular and Axial Illumination Scanning

Three-Dimensional Refractive Index Estimation Based on Non-i...

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Digital Holography and Three-Dimensional Imaging, DH 2024

作者： Bazow, Brad Raub, Christopher B. Nehmetallah, George Departments of Electrical Engineering and Computer Science The Catholic University of America 620 Michigan Avenue N.E. WashingtonDC20064 United States The Johns Hopkins University Applied Physics Laboratory 11100 Johns Hopkins Road LaurelMD20723 United States Departments of Biomedical Engineering The Catholic University of America 620 Michigan Avenue N.E. WashingtonDC20064 United States

We present computational inverse scattering to achieve three-dimensional refractive index reconstructions of biological specimens with sub-micron resolution in an optical diffraction tomography system with angular and...

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Ensemble Learning for Microbubble Localization in Super-Resolution Ultrasound

Ensemble Learning for Microbubble Localization in Super-Reso...

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IEEE International Symposium on Biomedical Imaging

作者： Sepideh K. Gharamaleki Brandon Helfield Hassan Rivaz Electrical and Computer Engineering Department Concordia University Montréal QC Canada Physics and Biology Departments Concordia University Montréal QC Canada

ISBN: (数字)9798331520526

ISBN: (纸本)9798331520533

Super-resolution ultrasound (SR-US) is a powerful imaging technique for capturing microvasculature and blood flow at high spatial resolution. However, accurate microbubble (MB) localization remains a key challenge, as errors in localization can propagate through subsequent stages of the super-resolution process, affecting overall performance. In this paper, we explore the potential of ensemble learning techniques to enhance MB localization by increasing detection sensitivity and reducing false positives. Our study evaluates the effectiveness of ensemble methods on both in vivo and simulated outputs of a Deformable DEtection TRansformer (Deformable DETR) network. As a result of our study, we are able to demonstrate the advantages of these ensemble approaches by showing improved precision and recall in MB detection and offering insights into their application in SR-US.

关键词： Location awareness Ultrasonic imaging Accuracy Sensitivity Superresolution Performance gain Transformers Ensemble learning Resource management Spatial resolution

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Theory of Quantum Circuits with Abelian Symmetries

arXiv

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arXiv 2023年

作者： Marvian, Iman Duke Quantum Center Departments of Physics & Electrical and Computer Engineering Duke University DurhamNC United States

Quantum circuits with gates (local unitaries) respecting a global symmetry have broad applications in quantum information science and related fields, such as condensed matter theory and quantum thermodynamics. However, despite their widespread use, fundamental properties of such circuits are not well-understood. Recently, it was found that generic unitaries respecting a global symmetry cannot be realized, even approximately, using gates that respect the same symmetry. This observation raises important open questions: What unitary transformations can be realized with k-local gates that respect a global symmetry? In other words, in the presence of a global symmetry, how does the locality of interactions constrain the possible time evolution of a composite system? In this work, we address these questions for the case of Abelian (commutative) symmetries and develop constructive methods for synthesizing circuits with such symmetries. Remarkably, as a corollary, we find that, while the locality of interactions still imposes additional constraints on realizable unitaries, certain restrictions observed in the case of non-Abelian symmetries do not apply to circuits with Abelian symmetries. For instance, in circuits with a general non-Abelian symmetry such as SU(d), the unitary realized in a subspace with one irreducible representation (charge) of the symmetry dictates the realized unitaries in multiple other sectors with inequivalent representations of the symmetry. Furthermore, in certain sectors, rather than all unitaries respecting the symmetry, the realizable unitaries are the symplectic or orthogonal subgroups of this group. We prove that none of these restrictions appears in the case of Abelian symmetries. This result suggests that global non-Abelian symmetries may affect the thermalization of quantum systems in ways not possible under Abelian symmetries. Copyright © 2023, The Authors. All rights reserved.

关键词： Quantum electronics

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ENSEMBLE LEARNING FOR MICROBUBBLE LOCALIZATION IN SUPER-RESOLUTION ULTRASOUND

arXiv

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arXiv 2024年

作者： Gharamaleki, Sepideh K. Helfield, Brandon Rivaz, Hassan Concordia University Electrical and Computer Engineering Department MontréalQC Canada Concordia University Physics and Biology Departments MontréalQC Canada

关键词： Ultrasonics

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EVALUATING DETECTION THRESHOLDS: THE IMPACT OF FALSE POSITIVES AND NEGATIVES ON SUPER-RESOLUTION ULTRASOUND LOCALIZATION MICROSCOPY

arXiv

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arXiv 2024年

Super-resolution ultrasound imaging with ultrasound localization microscopy (ULM) offers a high-resolution view of microvascular structures. Yet, ULM image quality heavily relies on precise microbubble (MB) detection. Despite the crucial role of localization algorithms, there has been limited focus on the practical pitfalls in MB detection tasks such as setting the detection threshold. This study examines how False Positives (FPs) and False Negatives (FNs) affect ULM image quality by systematically adding controlled detection errors to simulated data. Results indicate that while both FP and FN rates impact Peak Signal-to-Noise Ratio (PSNR) similarly, increasing FP rates from 0% to 20% decreases Structural Similarity Index (SSIM) by 7%, whereas same FN rates cause a greater drop of around 45%. Moreover, dense MB regions are more resilient to detection errors, while sparse regions show high sensitivity, showcasing the need for robust MB detection frameworks to enhance super-resolution imaging. © 2024, CC BY-NC-ND.

关键词： Image quality

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Rotationally Invariant Circuits: Universality with the Exchange Interaction and Two Ancilla Qubits

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Physical Review Letters 2024年第13期132卷 130201-130201页

作者： Iman Marvian Hanqing Liu Austin Hulse Departments of Physics Duke University Durham North Carolina 27708 USA Department of Electrical and Computer Engineering Duke University Durham North Carolina 27708 USA Duke Quantum Center Durham North Carolina 27708 USA

Universality of local unitary transformations is one of the cornerstones of quantum computing with many applications and implications that go beyond this field. However, it has recently been shown that this universality does not hold in the presence of continuous symmetries: generic symmetric unitaries on a composite system cannot be implemented, even approximately, using local symmetric unitaries on the subsystems. In this Letter, we show that, despite these constraints, any SU(2) rotationally invariant unitary can be realized with the Heisenberg exchange interaction, which is 2-local and rotationally invariant, provided that the system interacts with a pair of ancilla qubits. We also show that a single ancilla is not enough to achieve universality. Furthermore, we study qubit circuits formed from k-local rotationally invariant unitaries and fully characterize the constraints imposed by locality on the realizable unitaries. We also find an interpretation of these constraints in terms of the average energy of states with a fixed angular momentum.

关键词： Resource theories

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Controlling gene-expression variability via sequestration-based feedbacks

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IFAC-PapersOnLine 2024年第23期58卷 13-18页

作者： Supravat Dey Cesar A. Vargas-Garcia Abhyudai Singh Department of Physics and Department of Computer Science and Engineering SRM University-AP Amaravati Andhra Pradesh Department of Physics SRM University - AP Amaravati Andhra Pradesh 522240 India Corporación Colombiana de Investigación Agropecuaria - AGROSAVIA Mosquera Colombia Departments of Electrical and Computer Engineering Biomedical Engineering at the University of Delaware Newark DE 19716 USA

Expressed Transcription Factors (TFs) not only bind to sites at target promoters but also to decoy sites scattered across the genome. Binding to such “decoys” sequesters TFs critically impacting the response time and stochasticity (noise) in TF and target gene expression level. When the TF is a stable molecule, whose concentration is diluted by cellular growth, our results show that for fixed mean concentration levels, such decoy bindings can both enhance or suppress random fluctuations in TF levels depending on the source of noise (i.e., intrinsic vs. extrinsic noise) and the strength of binding (i.e., weak vs. strong decoys). We implement negative autoregulation where free (unbound) TF molecules inhibit their synthesis. Our analytical results corroborated by numerical simulations reveal that sequestration accentuates the effects of feedback in the sense that noise attenuation by negative feedback is higher with sequestration than in the absence of feedback. We next consider an alternative form of feedback where the TF increases the production of its decoys, and such feedback architectures are frequently seen in endogenous gene regulation involving microRNA-TF circuits and in controlling cellular stress responses. For these circuits where decoy numbers are TF-regulated, we identify limits of noise suppression, and in many cases, these limits occur at intermediate TF-decoy binding affinities.

关键词： Stochastic gene expression decoys feedback regulation transcription factors

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Study of ASIC Readout Used for Detectors in an MR Compatible, RF-Penetrable TOF-PET Insert

Study of ASIC Readout Used for Detectors in an MR Compatible...

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2022 IEEE Nuclear Science Symposium, Medical Imaging Conference, and Room Temperature Semiconductor Detector Conference, IEEE NSS MIC RTSD 2022

作者： Dong, Qian Sajedi, Salar Sacco, Ilaria Fischer, Peter Levin, Craig S. Stanford University Departments of Electrical Engineering and Radiology StanfordCA United States Stanford University Departments of Radiology StanfordCA United States Heidelberg University Department of Computer Science Baden-Württemberg Germany Stanford University Department of Radiology Electrical Engineering Bioengineering and Physics United States StanfordCA94305 United States

ISBN: (纸本)9781665488723

Developing positron emission tomography (PET) systems with high channel number has driven the need for application-specific integrated circuits (ASICs) owing to their compactness, multi-channel readout capability, and excellent time and energy resolution performance. They can also be quite flexible by employing field-programmable gate arrays (FPGAs) in the readout circuit. In particular, the ASIC+FPGA approach provides a high performance and compact solution for TOF-PET applications. ASICs serve functions of extracting time and energy information from analog SiPM signals, and an FPGA is employed for other application-specific requirements like on-board chip configuration, communication with data acquisition (DAQ) systems, and system monitoring. Based on this foundation, we developed TOF-capable detector modules for our second generation RF-penetrable PET insert. During our previous experiments, we found that different trigger and readout methods lead to different noise pattern and intensity in MR environment, and also have different singles count loss ratio. This paper aims to study and compare different readout configurations for our MR-compatible detectors. We studied four trigger and readout methods: hit-standard, frequent-standard, hit-bypass, and frequent-bypass, and compared their singles count loss ratios with both theoretical models and experimental results. For all four methods, the theoretical results matched the experimental results well. The two methods which used bypass mode performed better than those using the standard mode approach. With the most optimized trigger and readout method (hit-bypass), we achieved 1.2% singles count loss ratio at a 20 kcps count rate per channel. © 2022 IEEE.

关键词： ASIC FPGA PET insert readout TOF-PET

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Maximizing MeV x-ray dose in relativistic laser-solid interactions

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Physical Review Research 2023年第1期5卷 L012044-L012044页

作者： Kyle G. Miller Dean R. Rusby Andreas J. Kemp Scott C. Wilks Warren B. Mori Departments of Physics and Astronomy and of Electrical and Computer Engineering University of California Los Angeles California 90095 USA Lawrence Livermore National Laboratory Livermore California 94551 USA

Bremsstrahlung x rays generated in laser-solid interactions can be used as light sources for high-energy-density science. We present electron and x-ray spectra from multidimensional kinetic simulations with varying laser pulse intensity and duration at fixed energy of 200J. A phenomenological model for the transition from superponderomotive to ponderomotive temperatures is described, yielding a temperature scaling that depends on pulse duration and density scale length. The shortest pulses create low-divergence electron beams before self-generated magnetic fields evolve, yielding 1–5−MeV forward-going x rays containing ∼0.5% of the laser energy.

关键词： High intensity laser-plasma interactions Laser driven electron acceleration Laser light absorption in plasmas Plasma-solid interactions X-ray generation in plasmas Relativistic plasmas Monte Carlo methods Particle-in-cell methods

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Hilbert-Space Ergodicity in Driven Quantum Systems: Obstructions and Designs

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Physical Review X 2024年第4期14卷 041059-041059页

作者： Saúl Pilatowsky-Cameo Iman Marvian Soonwon Choi Wen Wei Ho Center for Theoretical Physics Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Departments of Physics and Electrical and Computer Engineering Duke University Durham North Carolina 27708 USA Department of Physics National University of Singapore Singapore 117551 Centre for Quantum Technologies National University of Singapore 3 Science Drive 2 Singapore 117543

Despite its long history, a canonical formulation of quantum ergodicity that applies to general classes of quantum dynamics, including driven systems, has not been fully established. Here we introduce and study a notion of quantum ergodicity for closed systems with time-dependent Hamiltonians, defined as statistical randomness exhibited in their longtime dynamics. Concretely, we consider the temporal ensemble of quantum states (time-evolution operators) generated by the evolution, and investigate the conditions necessary for them to be statistically indistinguishable from uniformly random states (operators) in the Hilbert space (space of unitaries). We find that the number of driving frequencies underlying the Hamiltonian needs to be sufficiently large for this to occur. Conversely, we show that statistical pseudo-randomness—indistinguishability up to some large but finite moment—can already be achieved by a quantum system driven with a single frequency, i.e., a Floquet system, as long as the driving period is sufficiently long. Our work relates the complexity of a time-dependent Hamiltonian and that of the resulting quantum dynamics, and offers a fresh perspective to the established topics of quantum ergodicity and chaos from the lens of quantum information.

关键词： Quantum information theory Quantum statistical mechanics Quantum many-body systems Ergodic theory

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