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Metamaterial-based octave-wide terahertz bandpass filters

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Photonics Research 2023年第4期11卷 526-532页

作者： ALI MALEKI AVINASH SINGH AHMED JABER wEI CUI YONGBAO XIN BRIAN T.SULLIVAN robert w.boyd JEAN-MICHEL MÉNARD Department of Physics University of OttawaOttawaOntario K1N 6N5Canada Iridian Spectral Technologies Ltd OttawaOntario K1G 6R8Canada School of Electrical Engineering and Computer Science University of OttawaOttawaOntario K1N 6N5Canada Institute of Optics and Department of Physics and Astronomy University of RochesterRochesterNew York 14627USA

we present octave-wide bandpass filters in the terahertz(THz)region based on bilayer-metamaterial(BLMM)*** passband region has a super-Gaussian shape with a maximum transmittance approaching 70%and a typical stopband rejection of 20 *** design is based on a metasurface consisting of a metallic squarehole array deposited on a transparent polymer,which is stacked on top of an identical metasurface with a subwavelength *** superimposed metasurface structures were designed using finite-difference time-domain(FDTD)simulations and fabricated using a photolithography *** characterization of these structures between 0.3 and 5.8 THz is performed with a time-domain THz spectroscopy *** agreement between experiment and simulation results is *** also demonstrated that two superimposed BLMM(2BLMM)devices increase the steepness of the roll-offs to more than 85 dB/octave and enable a superior stopband rejection approaching 40 dB while the maximum transmittance remains above 65%.This work paves the way toward new THz applications,including the detection of THz pulses centered at specific frequencies,and an enhanced time-resolved detection sensitivity toward molecular vibrations that are noise dominated by a strong,off-resonant,driving field.

关键词： process. field. approaching

Single-End Adaptive Optics Compensation for Emulated Turbulence in a Bi-Directional 10-Mbit/s per Channel Free-Space Quantum Communication Link Using Orbital-Angular-Momentum Encoding

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Research 2019年第1期2019卷 1134-1143页

作者： Cong Liu Kai Pang Zhe Zhao Peicheng Liao Runzhou Zhang Haoqian Song Yinwen Cao Jing Du Long Li Hao Song Yongxiong Ren Guodong Xie Yifan Zhao Jiapeng Zhao Seyed M.H.Rafsanjani Ari N.willner Jeffrey H.Shapiro robert w.boyd Moshe Tur Alan E.willner Department of Electrical Engineering University of Southern CaliforniaLos AngelesCA 90089USA Department of Physics and Astronomy University of Southern CaliforniaLos AngelesCA 90089USA Te Institute of Optics University of RochesterRochesterNew York 14627USA Massachusetts Institute of Technology Research Laboratory of ElectronicsCambridgeMassachusetts 02139USA School of Electrical Engineering Tel Aviv UniversityRamat Aviv 69978Israel

A single-end adaptive-optics(AO)module is experimentally demonstrated to mitigate the emulated atmospheric turbulence efects in a bi-directional quantum communication link,which employs orbital angular momentum(OAM)for data encoding.A classical Gaussian beam is used as a probe to detect the turbulence-induced wavefront distortion in the forward direction of the *** on the detected wavefront distortion,an AO system located on one end of the link is used to simultaneously compensate for the forward and backward ***,with emulated turbulence and when the probe is turned on,the mode purity of photons carrying OAMℓ=1 is improved by∼21%with AO *** also measured the performance when encoding data using OAM{ℓ=−1,+2}and{ℓ=−2,+1}in the forward and backward channels,respectively,at 10 Mbit/s per channel with one photon per pulse on *** this case,we found that the AO system could reduce the turbulence efects increased quantum-symbolerror-rate(QSER)by∼76%and∼74%,for both channels in the uni-directional and bi-directional cases,*** QSER improvement is observed for the opposite direction channels in the bi-directional case.

关键词： turbulence directional backward

Realization of a Laguerre-Gaussian mode sorter

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Realization of a Laguerre-Gaussian mode sorter

High-nickel insects and nickel hyperaccumulator plants： A review

第十八届全国量子光学学术会议

作者：付栋之 Yiyu Zhou Rui Qi Stone Oliver Yunlong wang Seyed Mohammad Hashemi Rafsanjani Jiapeng Zhao Mohammad Mirhosseini Zhimin Shi Pei Zhang robert w.boyd 西安交通大学 The Institute of Optics University of Rochester Department of Physics Miami University Shaanxi Key Laboratory for Quantum Information and Quantum Optoelectronic Devices Department of Applied PhysicsXi'an Jiaotong University Department of Physics University of South Florida Department of Physics University of Ottawa

The transverse structure of light is recognized as a resource that can be used to encode information onto photons and has been shown to be useful to enhance communication capacity as well as resolve point sources in superresolution imaging. The Laguerre-Gaussian(LG) modes form a complete and orthonormal basis and are described by a radial index p and an orbital angular momentum(OAM) index l. Earlier works have shown how to build a sorter for either the radial index p or the OAM index l of LG modes, but simultaneous determination of p and l is not straightforward and has not yet been realized. Here we propose and experimentally demonstrate a scheme to accomplish complete LG mode sorting, which consists of a novel, robust radial mode sorter, an l-dependent phase shifter and an OAM mode sorter. Our scheme is efficient, scalable, and intrinsically crosstalkfree, and therefore has potential for applications in optical communications, quantum information technology, superresolution imaging, and fiber optics.

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Insect Science 2009年第1期16卷 19-31页

作者： robert S. boyd Department of Biological Sciences 101 Life Sciences Building Auburn University Alabama 36849-5407 USA

Insects can vary greatly in whole-body elemental concentrations. Recent investigations of insects associated with Ni hyperaccumulator plants have identified insects with relatively elevated whole-body Ni levels. Evaluation of the limited data available indicates that a whole-body Ni concentration of 500μg Ni/g is exceptional： I propose that an insect species with a mean value of 500μg Ni/g or greater, in either larval/nymphal or adult stages, be considered a ＂high-Ni insect＂. Using the 500μg Ni/g criterion, 15 species ofhigh-Ni insects have been identified to date from studies in Mpumalanga （South Africa）, New Caledonia and California （USA）. The highest mean Ni concentration reported is 3 500 μg Ni/g for nymphs of a South African Stenoscepa species （Orthoptera： Pyrgomorphidae）. The majority of high-Ni insects （66%） are heteropteran herbivores. Studies of high-Ni insect host preference indicate they are monophagous （or nearly so） on a particular Ni hyperaccumulator plant species. Much of the Ni in bodies of these insects is in their guts （up to 66%-75%）, but elevated levels have also been found in Malpighian tubules, suggesting efficient elimination as one strategy for dealing with a high-Ni diet. Tissue levels of Ni are generally much lower than gut concentrations, but up to 1200μg Ni/g has been reported from exuviae, suggesting that molting may be another pathway of Ni elimination. One ecological function of the high Ni concentration of these insects may be to defend them against natural enemies, but to date only one experimental test has supported this ＂elemental defense＂ hypothesis. Community-level studies indicate that high-Ni insects mobilize Ni into food webs but that bioaccumulation of Ni does not occur at either plant-herbivore or herbivorepredator steps. Unsurprisingly, Ni bioaccumulation indices are greater for high-Ni insects compared to other insect species that feed on Ni hyperaccumulator plants. There is some evidence of Ni mobilization into food webs

关键词： bioaccumulation elemental defense heavy metals herbivore defense,hyperaccumulation metal tolerance nickel

Multi-Scale Dilated Convolution Network for SPECT-MPI Cardiovascular Disease Classification with Adaptive Denoising and Attenuation Correction

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Computer Modeling in Engineering & Sciences 2025年第1期142卷 299-327页

作者： A.robert Singh Suganya Athisayamani Gyanendra Prasad Joshi Bhanu Shrestha Department of Computational Intelligence SRM Institute of Science and TechnologyKattankulathur603203Tamil NaduIndia School of Computing Sastra Deemed to be UniversityThanjavur613401Tamil NaduIndia Department of Artificial Intelligence&Software Kangwon National UniversitySamcheok25913Republic of Korea Department of Information Convergence System Graduate School of Smart ConvergenceKwangwoon UniversitySeoul01897Republic of Korea

Myocardial perfusion imaging(MPI),which uses single-photon emission computed tomography(SPECT),is a well-known estimating tool for medical diagnosis,employing the classification of images to show situations in coronary artery disease(CAD).The automatic classification of SPECT images for different techniques has achieved near-optimal accuracy when using convolutional neural networks(CNNs).This paper uses a SPECT classification framework with three steps:1)Image denoising,2)Attenuation correction,and 3)Image *** denoising is done by a U-Net architecture that ensures effective image *** correction is implemented by a convolution neural network model that can remove the attenuation that affects the feature extraction process of ***,a novel multi-scale diluted convolution(MSDC)network is *** merges the features extracted in different scales and makes the model learn the features more *** scales of filters with size 3×3 are used to extract *** three steps are compared with state-of-the-art *** proposed denoising architecture ensures a high-quality image with the highest peak signal-to-noise ratio(PSNR)value of *** proposed classification method is compared with the five different CNN models,and the proposed method ensures better classification with an accuracy of 96%,precision of 87%,sensitivity of 87%,specificity of 89%,and F1-score of 87%.To demonstrate the importance of preprocessing,the classification model was analyzed without denoising and attenuation correction.

关键词： SPECT-MPI CAD MSDC denoising attenuation correction classification

Three-Stage Transfer Learning with AlexNet50 for MRI Image Multi-Class Classification with Optimal Learning Rate

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Computer Modeling in Engineering & Sciences 2025年第1期142卷 155-183页

作者： Suganya Athisayamani A.robert Singh Gyanendra Prasad Joshi woong Cho School of Computing Sastra Deemed to be UniversityThanjavur613401India Department of Computational Intelligence SRM Institute of Science and TechnologyKattankulathur603203India Department of AI and Software Engineering Kangwon National UniversitySamcheok25913Republic of Korea Department of Electronics Information and Communication EngineeringKangwon National UniversitySamcheok25913Republic of Korea

In radiology,magnetic resonance imaging(MRI)is an essential diagnostic tool that provides detailed images of a patient’s anatomical and physiological *** is particularly effective for detecting soft tissue ***,radiologists manually interpret these images,which can be labor-intensive and time-consuming due to the vast amount of *** address this challenge,machine learning,and deep learning approaches can be utilized to improve the accuracy and efficiency of anomaly detection in MRI *** manuscript presents the use of the Deep AlexNet50 model for MRI classification with discriminative learning *** are three stages for learning;in the first stage,the whole dataset is used to learn the *** the second stage,some layers of AlexNet50 are frozen with an augmented dataset,and in the third stage,AlexNet50 with an augmented dataset with the augmented *** method used three publicly available MRI classification datasets:Harvard whole brain atlas(HwBA-dataset),the School of Biomedical Engineering of Southern Medical University(SMU-dataset),and The National Institute of Neuroscience and Hospitals brain MRI dataset(NINS-dataset)for *** hyperparameter optimizers like Adam,stochastic gradient descent(SGD),Root mean square propagation(RMS prop),Adamax,and Adamw have been used to compare the performance of the learning ***-dataset registers maximum classification *** evaluated the performance of the proposed classification model using several quantitative metrics,achieving an average accuracy of 98%.

关键词： MRI tumors classification AlexNet50 transfer learning hyperparameter tuning optimizer

Lygus hesperus （Heteroptera： Miridae） tolerates high concentrations of dietary nickel

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Insect Science 2007年第3期14卷 201-205页

作者： robert S. boyd Department of Biological Sciences Auburn University Alabama USA

Nickel hyperaccumulator plants contain unusually elevated levels of Ni （〉 1 000 μg Ni/g）. Some insect herbivores, including Lygus hesperus （western tarnished plant bug）, have been observed feeding on the California Ni hyperaccumulator Streptanthus polygaloides. This bug may be able to utilize S. polygaloides as a host either through its feeding behavior or by physiological tolerance of Ni. This experiment determined the Ni tolerance of L hesperus by offering insects artificial diet amended with 0, 0.4, 1, 2, 4.5, 10, 20 and 40 mmol Ni/L and recording survival. Survival varied due to Ni concentration, with diets containing 10 mmol Ni/L and greater resulting in significantly lower survival compared to the control （0 mmol Ni/L） treatment. Insects tolerated diet containing as much as 4.5 mmol Ni/L, a relatively elevated Ni concentration. I conclude that L hesperus can feed on S. polygaloides because it is Ni-tolerant, probably due to physiological mechanisms that provide it with resistance to plant chemical defenses including elemental defenses such as hyperaccumulated Ni.

关键词： elemental defense heavy metals herbivore defense hyperaccumulation metal tolerance nickel

Climate Change:No Going Back

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China Today 2025年第1期74卷 42-44页

作者： robert wALKER Beijing Normal University Royal Society of Arts Academy of Social Sciences in the U.K

with a commitment to reduce emissions,and its investment in green technology bringing down global costs,China is emerging as the leader in fighting climate *** knows that our world is getting *** also know *** out po... 详细信息

关键词： investment bringing fighting

Generating optical orbital angular momentum at visible wavelengths using a plasmonic metasurface

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Light(Science & Applications) 2014年第1期3卷 219-222页

作者： Ebrahim Karimi Sebastian A Schulz Israel De Leon Hammam Qassim Jeremy Upham robert w.boyd Department of Physics University of OttawaOttawaOnt.K1N 6N5Canada Institute of Optics University of RochesterRochesterNY 14627USA

Light beams with a helical phase-front possess orbital angular momentum along their direction of propagation in addition to the spin angular momentum that describes their *** recently,it was thought that these two‘rotational’motions of light were largely independent and could not be coupled during light–matter ***,it is now known that interactions with carefully designed complex media can result in spin-to-orbit coupling,where a change of the spin angular momentum will modify the orbital angular momentum and vice *** this work,we propose and demonstrate that the birefringence of plasmonic nanostructures can be wielded to transform circularly polarised light into light carrying orbital angular momentum.A device operating at visible wavelengths is designed from a space-variant array of subwavelength plasmonic *** confirms that circularly polarised light transmitted through the device is imbued with orbital angular momentum of 62"(with conversion efficiency of at least 1%).This technology paves the way towards ultrathin orbital angular momentum generators that could be integrated into applications for spectroscopy,nanoscale sensing and classical or quantum communications using integrated photonic devices.

关键词： light orbital angular momentum light spin angular momentum plasmonic metasurface