bluuebunny/crossref_metadata_2025 huggingface dataset:
Robust high-order petal-mode laser with tunable topological charge pumped by an axicon-based annular beam
Authors: Zhang Zihan , Liu Jie , Duan Yanmin , Zhang Yongchang , Jin Xinxin , Li Zhihong , Zhu Haiyong
Published: April 2024

In this work, we demonstrate a watt-level laser producing high-order, petal-shaped output modes with tunable topological charge, by using an axicon-based divergent annular pump beam. The topological charge of the output beam could be varied in the range of 34–72 by adjusting the position of the Nd:YVO4 crystal relative to the focal plane of the pump beam. The highest order petal-mode beam generated from the system had a topological charge of 72 and a power of 1.3 W. The highest output power up to 2.1 W with a topological charge of 34 was achieved at an absorbed pump power of 5.8 W. The generated output modes were observed to be robust under power scaling and on propagation, with the same spatial profiles being maintained in the near- and far-fields. We anticipate that this system design may find use as a laser source in applications such as 3D optical trapping, fabrication of optical vortex arrays, optical communications, and high-sensitivity spatial measurement.
Graphics processing unit (GPU)-enhanced nonhydrostatic model with grid nesting for global tsunami propagation and coastal inundation
Authors: Wang Hang , Wang Gang , Fu Ruili , Zheng Jinhai , Wang Peitao , Yu Fujiang , Liang Qiuhua
Published: April 2024

Nonhydrostatic models have proven their superiority in describing tsunami propagation over trans-oceanic distances and nearshore transformation because of their good dispersion and nonlinearity properties. The novel one-layer nonhydrostatic formulations proposed by Wang et al. [Phys. Fluids 35, 076610 (2023)] have been rederived in the spherical coordinate system incorporating Coriolis effects to enable the application of basin-wide tsunami propagation. The model was implemented using the fractional step method, where the hydrostatic step was solved by a Godunov-type finite-volume scheme, and the nonhydrostatic step was obtained with the finite-difference method. Additionally, a two-way grid-nesting scheme was employed to adapt the topographic features for efficient computation of tsunami propagation in deep ocean and coastal inundation. Furthermore, graphics processing unit (GPU)-parallelism technique was incorporated to further optimize the model performance. An idealized benchmark test as well as three experiments of regular and irregular waves, solitary, and N-waves transformations have been simulated to demonstrate the superior performance of the current GPU-accelerated grid-nesting nonhydrostatic model. Finally, the model has been applied to reproduce the 1964 Prince William Sound Tsunami, its propagation across the North Pacific and induced inundation in the Seaside.
Hybrid ultrathin metasurface for broadband sound absorption
Authors: Abrahams Marnix P. , Oudich Mourad , Revalor Yann , Vukadinovic Nicolas , Assouar Badreddine
Published: April 2024

To this day, achieving broadband low-frequency sound absorption remains a challenge even with the possibilities promised by the advent of metamaterials and metasurfaces, especially when size and structural restrictions exist. Solving this engineering challenge relies on stringent impedance matching and coupling of the multiple independent local resonators in metasurface absorbers. In this Letter, we present an innovative design approach to broaden the sound absorption bandwidth at low-frequency regime. A hybrid metasurface design is proposed where four coupled planar coiled resonators are also coupled to a well-designed thin planar cavity. This hybrid metasurface creates a broad sound absorption band (130–200 Hz) that is twice as wide as that of the traditional single layer metasurface utilizing four coiled cavities at a deep subwavelength thickness (∼λ/51). This design strategy opens routes toward engineering a class of high-performance thin metasurfaces for ultra-broadband sound absorption, while keeping the planar size unchanged.
Molecular diversity of black corals from the Saudi Arabian Red Sea: a first assessment
Authors: Vicario Silvia , Terraneo Tullia Isotta , Chimienti Giovanni , Maggioni Davide , Marchese Fabio , Purkis Sam J. , Eweida Ameer Abdulla , Rodrigue Mattie , Benzoni Francesca
Published: April 2024

Black corals occur as part of benthic assemblages from shallow to deep waters in all oceans. Despite the importance in many benthic ecosystems, where these act as biodiversity aggregators, antipatharians remain poorly studied, with 75% of the known species occurring below recreational SCUBA diving depth limits. Currently, information regarding the diversity and evolutionary history is limited, with most studies focusing on Hawaii and the South Pacific Ocean. Other regions of the world have received less attention, such as the Red Sea, where only two black coral families and four genera have been recorded. We provide the first analysis of the molecular diversity of black corals in the eastern Gulf of Aqaba and the northern and central Saudi Arabian Red Sea, based on a dataset of 161 antipatharian colonies collected down to 627 m deep. Based on specimen morphology, we ascribed our material to 11 genera belonging to 4 of the 7 known Antipatharia families, i.e. Antipathidae, Aphanipathidae, Myriopathidae and Schizopathidae. The genus level phylogeny of three intergenic mitochondrial regions, the trnW-IGR-nad2 (IgrW), nad5-IGR-nad1 (IgrN) and cox3-IGR-cox1 was reconstructed including previously published material. Overall, we recovered six molecular clades that included exclusively Red Sea sequences, with the highest diversity occurring at mesophotic depths. This study highlights that diversity of black corals in the Red Sea is much higher than previously known, with seven new generic records, suggesting that this basin may be a hotspot for antipatharian diversity as is known for other taxa. Our results recovered unresolved relationships within the order at the familial and generic levels. This emphasises the urgent need for an integration of genomic-wide data with a re-examination of informative morphological features necessary to revise the systematics of the order at all taxonomic levels.
Distinct lateral hypothalamic CaMKIIα neuronal populations regulate wakefulness and locomotor activity
Authors: Heiss Jaime E. , Zhong Peng , Lee Stephanie M. , Yamanaka Akihiro , Kilduff Thomas S.
Published: April 2024

For nearly a century, evidence has accumulated indicating that the lateral hypothalamus (LH) contains neurons essential to sustain wakefulness. While lesion or inactivation of LH neurons produces a profound increase in sleep, stimulation of inhibitory LH neurons promotes wakefulness. To date, the primary wake-promoting cells that have been identified in the LH are the hypocretin/orexin (Hcrt) neurons, yet these neurons have little impact on total sleep or wake duration across the 24-h period. Recently, we and others have identified other LH populations that increase wakefulness. In the present study, we conducted microendoscopic calcium imaging in the LH concomitant with EEG and locomotor activity (LMA) recordings and found that a subset of LH neurons that express Ca
2+
/calmodulin-dependent protein kinase IIα (CaMKIIα) are preferentially active during wakefulness. Chemogenetic activation of these neurons induced sustained wakefulness and greatly increased LMA even in the absence of Hcrt signaling. Few LH CaMKIIα-expressing neurons are hypocretinergic or histaminergic while a small but significant proportion are GABAergic. Ablation of LH inhibitory neurons followed by activation of the remaining LH CaMKIIα neurons induced similar levels of wakefulness but blunted the LMA increase. Ablated animals showed no significant changes in sleep architecture but both spontaneous LMA and high theta (8 to 10 Hz) power during wakefulness were reduced. Together, these findings indicate the existence of two subpopulations of LH CaMKIIα neurons: an inhibitory population that promotes locomotion without affecting sleep architecture and an excitatory population that promotes prolonged wakefulness even in the absence of Hcrt signaling.
Engineering a nanoantibiotic system displaying dual mechanism of action
Authors: Xing Huihua , de Campos Luana Janaína , Pereira Aramis Jose , Fiora Maria Mercedes , Aguiar-Alves Fabio , Tagliazucchi Mario , Conda-Sheridan Martin
Published: April 2024

In recent decades, peptide amphiphiles (PAs) have established themselves as promising self-assembling bioinspired materials in a wide range of medical fields. Herein, we report a dual-therapeutic system constituted by an antimicrobial PA and a cylindrical protease inhibitor (LJC) to achieve broad antimicrobial spectrum and to enhance therapeutic efficacy. We studied two strategies: PA–LJC nanostructures (
Encapsulation
) and PA nanostructures + free LJC (
Combination
). Computational modeling using a molecular theory for amphiphile self-assembly captures and explains the morphology of PA–LJC nanostructures and the location of encapsulated LJC in agreement with transmission electron microscopy and two-dimensional (2D) NMR observations. The morphology and release profile of PA–LJC assemblies are strongly correlated to the PA:LJC ratio: high LJC loading induces an initial burst release. We then evaluated the antimicrobial activity of our nanosystems toward gram-positive and gram-negative bacteria. We found that the
Combination
broadens the spectrum of LJC, reduces the therapeutic concentrations of both agents, and is not impacted by the inoculum effect. Further, the
Encapsulation
provides additional benefits including bypassing water solubility limitations of LJC and modulating the release of this molecule. The different properties of PA–LJC nanostructures results in different killing profiles, and reduced cytotoxicity and hemolytic activity. Meanwhile, details in membrane alterations caused by each strategy were revealed by various microscopy and fluorescent techniques. Last, in vivo studies in larvae treated by the
Encapsulation
strategy showed better antimicrobial efficacy than polymyxin B. Collectively, this study established a multifunctional platform using a versatile PA to act as an antibiotic, membrane-penetrating assistant, and slow-release delivery vehicle.
Fuzzy bounces
Authors: Giovannini Massimo
Published: April 2024

We observe that the energy and the enthalpy densities can be smeared by two fudge factors that are constrained by the contracted Bianchi identities. Depending on the analytic properties of the smearing functions the underlying cosmological solutions belong to two physically different classes, namely the bounces of the scale factor and the curvature bounces. While the curvature bounces are naturally compatible with a stage of accelerated expansion, the bounces of the scale factor demand an early phase of accelerated contraction even if a short inflationary stage may arise prior to the decelerated regime. Despite the regularity of the underlying solutions, gradient instabilities and singularities do occasionally appear in the evolution of curvature inhomogeneities. After deducing the specific criteria behind these occurrences, the background-independent conclusions are corroborated by a series of concrete examples associated with different forms of the smearing functions. The evolution of the curvature inhomogeneities restricts the ranges of the solutions that turn out to be unsuitable even for a limited description of the pre-inflationary initial data. The same observation holds in the case of the gauge-invariant evolution of the matter density contrast. It is however not excluded that a class of scenarios (mainly associated with the curvature bounces) could indeed avoid the potential instabilities. All in all the present analysis explore a general approach whose results are relevant in all the contexts where bouncing solutions are invoked either as complementary or as alternative to the conventional inflationary scenarios.
Gravitational wave pulse and memory effects for hairy Kiselev black hole and its analogy with Bondi–Sachs formalism
Authors: Hadi H , Rezaei Akbarieh Amin , Mota David F
Published: April 2024

The investigation of non-vacuum cosmological backgrounds containing black holes is greatly enhanced by the Kiselev solution. This solution plays a crucial role in understanding the properties of the background and its relationship with the features of the black hole. Consequently, the gravitational memory effects at large distances from the black hole offer a valuable means of obtaining information about the surrounding field parameter N and parameters related to the hair of the hairy Kiselev Black hole. This paper investigates the gravitational memory effects in the context of the Kiselev solution through two distinct approaches. At first, the gravitational memory effect at null infinity is explored by utilizing the Bondi–Sachs formalism by introducing a gravitational wave (GW) pulse to the solution. The resulting Bondi mass is then analyzed to gain further insight. Therefore, the Kiselev solution is being examined to determine the variations in Bondi mass caused by the pulse of GWs. The study of changes in Bondi mass is motivated by the fact that it is dynamic and time-dependent, and it measures mass on an asymptotically null slice or the densities of energy on celestial spheres. In the second approach, the investigation of displacement and velocity memory effects is undertaken in relation to the deviation of two neighboring geodesics and the deviation of their derivative influenced by surrounding field parameter N and the hair of hairy Kiselev black hole. This analysis is conducted within the context of a GW pulse present in the background of a hairy Kiselev black hole surrounded by a field parameter N.
Jet propulsion from a closing book
Authors: Pantaleone J
Published: April 2024

When a book closes, the air between the approaching surfaces is accelerated and ejected through the open sides at large speeds. The air resists this motion, and so a reaction forces acts on the closing book. To study this force, an idealized book is placed on rollers so it is free to move horizontally. The speed gained by the book is measured for different initial opening angles and for different book lengths. The dependence on these parameters is found to be surprisingly simple, and the extrapolation to plates of infinite length agrees well with a simple model. This system is interesting because it is relatively easy to build, measure, and model, and also because colliding surfaces in a fluid are an everyday occurrence. This system can be used as either a classroom demonstration or a laboratory experiment.
A novel variational approach for multiphoton microscopy image restoration: from PSF estimation to 3D deconvolution
Authors: Ajdenbaum Julien , Chouzenoux Emilie , Lefort Claire , Martin Ségolène , Pesquet Jean-Christophe
Published: April 2024

In multi-photon microscopy (MPM), a recent in-vivo fluorescence microscopy system, the task of image restoration can be decomposed into two interlinked inverse problems: firstly, the characterization of the point spread function (PSF) and subsequently, the deconvolution (i.e. deblurring) to remove the PSF effect, and reduce noise. The acquired MPM image quality is critically affected by PSF blurring and intense noise. The PSF in MPM is highly spread in 3D and is not well characterized, presenting high variability with respect to the observed objects. This makes the restoration of MPM images challenging. Common PSF estimation methods in fluorescence microscopy, including MPM, involve capturing images of sub-resolution beads, followed by quantifying the resulting ellipsoidal 3D spot. In this work, we revisit this approach, coping with its inherent limitations in terms of accuracy and practicality. We estimate the PSF from the observation of relatively large beads (approximately 1 

μ

m

in diameter). This goes through the formulation and resolution of an original non-convex minimization problem, for which we propose a proximal alternating method along with convergence guarantees. Following the PSF estimation step, we then introduce an innovative strategy to deal with the high level multiplicative noise degrading the acquisitions. We rely on a heteroscedastic noise model for which we estimate the parameters. We then solve a constrained optimization problem to restore the image, accounting for the estimated PSF and noise, while allowing a minimal hyper-parameter tuning. Theoretical guarantees are given for the restoration algorithm. These algorithmic contributions lead to an end-to-end pipeline for 3D image restoration in MPM, that we share as a publicly available Python software. We demonstrate its effectiveness through several experiments on both simulated and real data.
Cross sections of neutral-current neutrino scattering on 98,100Mo isotopes
Authors: Sahu R , Kota V K B , Kosmas T S
Published: April 2024

Coherent elastic neutrino–nucleus scattering (CEνNS) is a neutral-current low-energy electro-weak reaction-channel detected recently by the COHERENT experiment at the Oak Ridge National Laboratory (ORNL), USA, in the Spallation Neutron Source facility. The extremely weak signal on the CsI detector of the first experiment and on the liquid Ar of the repeated COHERENT experiment is the energy-recoil due to the neutrino–nucleus interaction, where the nucleus is elastically scattered as a whole while simultaneously the neutrino goes out. Today, several promising nuclear detectors are on the way to be employed in designed and ongoing experiments. In our present work, we provide predictions for incoherent scattering cross sections of low-energy neutrinos on 98,100Mo isotopes obtained with the deformed shell model employed previously for similar predictions in other electroweak processes. We mention that, Mo detector medium has been used previously in the MOON and NEMO double beta decay experiments.
Automatic multi-LiDAR calibration and refinement method
Authors: Wei Pengjin , Yan Guohang , Li Yikang , Fang Kun , Cai Xinyu , Liu Wei , Yang Jie
Published: April 2024

Sensor-based environmental perception is a crucial component of autonomous driving systems. To perceive the surrounding environment better, an intelligent system would utilize multiple LiDARs (3D Light Detection and Ranging). The accuracy of the perception largely depends on the quality of the sensor calibration. This research aims to develop a robust, fast, automatic, and accurate calibration strategy for multiple LiDAR systems. Our proposed multi-LiDAR calibration method consists of two stages: rough and refinement calibration. In the first stage, sensors are roughly calibrated from an arbitrary initial position using a deep neural network that does not rely on prior information or constraints on the initial sensor pose. In the second stage, we propose the octree-based refinement, an optimization method that considers sensor noise and prioritization. Our strategy is robust, fast, and not restricted to any environment. Additionally, we collected two datasets consisting of both real-world and simulated scenarios. Our experimental results from both datasets demonstrate the reliability and accuracy of our method. All the related datasets and codes are open-sourced on the GitHub website at https://github.com/OpenCalib/LiDAR2LiDAR.
Immersive visualisation for a large metrological data set
Authors: Babic B , Coleman V A , Herrmann J
Published: April 2024

A purpose of scientific visualisation is to facilitate the extraction of information within underlying data. Visualisation of a large data set requires an appropriate visualisation method where, instead of focusing on expected features, all acquired data are treated on an equal footing. Here, we identify critical differences between raw and processed data acquired from displacement measurements at the nanoscale. We illustrate the strength of immersive data visualisation in rapidly and intuitively identifying non-obvious data trends, supported by correlation with the associated measurement uncertainties. These insights can be directly leveraged for optimisation of instrumentation and measurement protocols, application of appropriate measurement corrections, and iterative experimental design changes.
Relative humidity measurements of a thin-film humidity sensor in condensing conditions in the temperature range from −40 °C to 5 °C
Authors: Lee Sang-Wook , Lee Young-Suk , Choi Byung Il , Kim Yong-Gyoo , Kim Sunghun
Published: April 2024

In condensing conditions, metastable states such as supersaturation of water vapour and supercooling of liquid water are commonly observed in the free atmosphere. This study investigates the response of a polymeric thin-film humidity sensor under condensing conditions at various temperatures (−40 °C, −20 °C, −5 °C, and 5 °C) and different relative humidity (RH) levels. To ensure precise control of RH, a saturator-based humidity generator operating in a two-temperature mode is utilized. The condensing conditions are achieved in two ways: by increasing water vapour pressure (WVP) at a fixed temperature and by decreasing the temperature while maintaining a constant WVP. In general, when measuring RH under condensing conditions, the sensor indicates a temporary supersaturation state with an RH peak exceeding 100% before the onset of condensation. Subsequently, the RH value exhibits a delayed decrease when exposed to a non-condensing RH level. The experiments with a constant WVP demonstrate a lower likelihood of ice condensation compared to those with a constant temperature. This study demonstrates the measurement capability and behaviour of thin-film humidity sensors above 100% RH in the supersaturation states that are commonly observed in the free atmosphere at meteorologically-relevant temperatures.
UV photodetectors based on W-doped ZnO thin films
Authors: Jalal R , Ozel K , Atilgan A , Yildiz A
Published: April 2024

W-doped ZnO thin films deposited on Si substrates with (100) orientation by sol–gel spin coating method at temperature 500 °C. W/Zn atomic ratio varies from 0% to 4%. Then, the UV detection performance analysis of p–n heterojunction UV photodetectors based on W-doped ZnO/Si is analyzed. The current–voltage curves of W-doped ZnO/Si are investigated in dark and exhibit diode-like rectifying behavior. Among doped ZnO/Si, sample with atomic ratio of W/Zn = 2% is the best candidate to study photodetector characteristics in UV range. The resulting device exhibits a rectification ratio RR of 5587 at ±5 V, a higher responsivity of 3.84 A W−1 and a photosensitivity value of 34 at 365 nm under 0.5 mW cm−2. The experimental findings reveal that the UV detection performance of the heterojunction-based photodetectors strongly dependent on the properties of metal oxide layer. The main goal of this work is to investigate the effect of W doping on the performance of ZnO/Si based photodetectors. Based on our results, it is observed that 2 at% of W dopant is the optimum amount of doping for high performance photodetector of ZnO:W/Si heterojunction thanks to the suppressed recombination ratio and enhanced carrier separation properties in the depletion zone.
Phonon energy dissipation in friction between black phosphorus layers
Authors: Dong Yun , Wang Jinguang , Rui Zhiyuan , Yang Futian , Tang Xinyi , Tao Yi , Liu Yifan , Shi Bo
Published: April 2024

Herein, we employ molecular dynamics simulations to decode the friction properties and phonon energy dissipation between black phosphorus layers. The observations reveal the influence of three factors, temperature, velocity, and normal load, on the friction force of monolayer/bilayer black phosphorus. Specifically, friction is negatively correlated with layer thickness and temperature, and positively correlated with velocity and normal load. The change in friction force is further explained in terms of frictional energy dissipation, and supplemented by the height of potential barriers as well as the number of excited phonons. From the phonon spectrum analysis, the phonon number at the contact interface is found to be higher than that at the non-contact interface. This is due to the larger distance of the contact interface atoms deviate from their equilibrium positions, resulting in higher total energy generated by more intense oscillations, and therefore contributes greater to friction.
Mott memristor based stochastic neurons for probabilistic computing
Authors: Fida Aabid Amin , Mittal Sparsh , Khanday Farooq Ahmad
Published: April 2024

Many studies suggest that probabilistic spiking in biological neural systems is beneficial as it aids learning and provides Bayesian inference-like dynamics. If appropriately utilised, noise and stochasticity in nanoscale devices can benefit neuromorphic systems. In this paper, we build a stochastic leaky integrate and fire (LIF) neuron, utilising a Mott memristor’s inherent stochastic switching dynamics. We demonstrate that the developed LIF neuron is capable of biological neural dynamics. We leverage these characteristics of the proposed LIF neuron by integrating it into a population-coded spiking neural network and a spiking restricted Boltzmann machine (sRBM), thereby showcasing its ability to implement probabilistic learning and inference. The sRBM achieves a software-comparable accuracy of 87.13%. Unlike CMOS-based probabilistic neurons, our design does not require any external noise sources. The designed neurons are highly energy efficient and ultra-compact, requiring only three components: a resistor, a capacitor and a memristor device.
A novel non-chemically amplified resist based on polystyrene-iodonium derivatives for electron beam lithography
Authors: Cui Xuewen , Zhang Siliang , Cong Xue , Gao Jiaxing , Wu Yurui , Guo Xudong , Hu Rui , Wang Shuangqing , Chen Jinping , Li Yi , Du Wenna , Yang Guoqiang
Published: April 2024

To break the resolution limitation of traditional resists, more work is needed on non-chemically amplified resists (non-CARs). Non-CARs based on iodonium salt modified polystyrene (PS-I) were prepared with controllable molecular weight and structure. The properties of the resist can be adjusted by the uploading of iodonium salts on the polymer chain, the materials with a higher proportion of iodonium salts show better lithography performance. By comparing contrast curves and quality of the lithographic patterns, the optimum developing condition of 4-methyl-2-pentanone and ethyl alcohol (v:v = 1:7) was selected. The high-resolution stripes of 15 nm half-pitch (HP) can be achieved by PS-I0.58 in e-beam lithography (EBL). PS-I0.58 shows the advanced lithography performance in the patterns of 16 nm HP and 18 nm HP stripes with low line edge roughness (3.0 nm and 2.4 nm). The resist shows excellent potential for further pattern transfer, the etch selectivity of resist PS-I0.58 to the silicon was close to 12:1. The lithographic mechanism of PS-I was investigated by experimental and theoretical calculation, which indicates the polarity of materials changes results in the solubility switch. This work provides a new option and useful guidelines for the development of high-resolution resist.
LymphoDose: a lymphocyte dose estimation framework—application to brain radiotherapy
Authors: de Kermenguy François , Benzazon Nathan , Maury Pauline , Vauclin Rémi , M’hamdi Meissane , Cifliku Vjona , Limkin Elaine , Diallo Ibrahima , Morel Daphné , Milewski Candice , Clémenson Céline , Mondini Michele , Deutsch Eric , Robert Charlotte
Published: April 2024

Objective. Severe radiation-induced lymphopenia occurs in 40% of patients treated for primary brain tumors and is an independent risk factor of poor survival outcomes. We developed an in-silico framework that estimates the radiation doses received by lymphocytes during volumetric modulated arc therapy brain irradiation. Approach. We implemented a simulation consisting of two interconnected compartmental models describing the slow recirculation of lymphocytes between lymphoid organs (

M
1

) and the bloodstream (

M

2

). We used dosimetry data from 33 patients treated with chemo-radiation for glioblastoma to compare three cases of the model, corresponding to different physical and biological scenarios: (H1) lymphocytes circulation only in the bloodstream i.e. circulation in

M

2

only; (H2) lymphocytes recirculation between lymphoid organs i.e. circulation in

M

1

and

M

2

interconnected; (H3) lymphocytes recirculation between lymphoid organs and deep-learning computed out-of-field (OOF) dose to head and neck (H&N) lymphoid structures. A sensitivity analysis of the model’s parameters was also performed. Main results. For H1, H2 and H3 cases respectively, the irradiated fraction of lymphocytes was 99.8 ± 0.7%, 40.4 ± 10.2% et 97.6 ± 2.5%, and the average dose to irradiated pool was 309.9 ± 74.7 mGy, 52.6 ± 21.1 mGy and 265.6 ± 48.5 mGy. The recirculation process considered in the H2 case implied that irradiated lymphocytes were irradiated in the field only 1.58 ± 0.91 times on average after treatment. The OOF irradiation of H&N lymphoid structures considered in H3 was an important contribution to lymphocytes dose. In all cases, the estimated doses are low compared with lymphocytes radiosensitivity, and other mechanisms could explain high prevalence of RIL in patients with brain tumors. Significance. Our framework is the first to take into account OOF doses and recirculation in lymphocyte dose assessment during brain irradiation. Our results demonstrate the need to clarify the indirect effects of irradiation on lymphopenia, in order to potentiate the combination of radio-immunotherapy or the abscopal effect.
Iterative reconstruction for limited-angle CT using implicit neural representation
Authors: Lee Jooho , Baek Jongduk
Published: April 2024

Objective. Limited-angle computed tomography (CT) presents a challenge due to its ill-posed nature. In such scenarios, analytical reconstruction methods often exhibit severe artifacts. To tackle this inverse problem, several supervised deep learning-based approaches have been proposed. However, they are constrained by limitations such as generalization issue and the difficulty of acquiring a large amount of paired CT images. Approach. In this work, we propose an iterative neural reconstruction framework designed for limited-angle CT. By leveraging a coordinate-based neural representation, we formulate tomographic reconstruction as a convex optimization problem involving a deep neural network. We then employ differentiable projection layer to optimize this network by minimizing the discrepancy between the predicted and measured projection data. In addition, we introduce a prior-based weight initialization method to ensure the network starts optimization with an informed initial guess. This strategic initialization significantly improves the quality of iterative reconstruction by stabilizing the divergent behavior in ill-posed neural fields. Our method operates in a self-supervised manner, thereby eliminating the need for extensive data. Main results. The proposed method outperforms other iterative and learning-based methods. Experimental results on XCAT and Mayo Clinic datasets demonstrate the effectiveness of our approach in restoring anatomical features as well as structures. This finding was substantiated by visual inspections and quantitative evaluations using NRMSE, PSNR, and SSIM. Moreover, we conduct a comprehensive investigation into the divergent behavior of iterative neural reconstruction, thus revealing its suboptimal convergence when starting from scratch. In contrast, our method consistently produced accurate images by incorporating an initial estimate as informed initialization. Significance. This work showcases the feasibility to reconstruct high-fidelity CT images from limited-angle x-ray projections. The proposed methodology introduces a novel data-free approach to enhance medical imaging, holding promise across various clinical applications.
Full waveform inversion using frequency shift envelope-based global correlation norm for ultrasound computed tomography
Authors: Wu Yun , Yan Weicheng , Liu Zhaohui , Zhang Qiude , Zhou Liang , Song Junjie , Qiu Wu , Ding Mingyue , Yuchi Ming
Published: April 2024

Many studies have been carried out on ultrasound computed tomography (USCT) for its ability to offer quantitative measurements of tissue sound speed. Full waveform inversion (FWI) is a technique for reconstructing high-resolution sound speed images by iteratively minimizing the difference between the observed ultrasound data and the synthetic data based on the waveform equation. However, FWI suffers from cycle-skipping, which usually causes FWI convergence at a local minimum. Cycle-skipping occurs when the phase difference between the observed data and the synthetic data exceeds half a cycle. The simplest way to avoid cycle-skipping is to use low-frequency information for reconstruction. Nevertheless, in imaging systems, the response bandwidth of the probe is limited, and reliable low-frequency information often exceeds the response band. Therefore, it is a challenge to perform FWI imaging and avoid cycle-skipping problems without low-frequency information. In this paper, we propose a frequency shift envelope-based global correlation norm (FSEGCN), where an artificial source wavelet with a lower frequency is adopted to calculate synthetic data. FSEGCN compared with FWI, envelope inversion (EI), global correlation norm (GCN), envelope-based global correlation norm (EGCN) through concentric circle phantom without low-frequency information. The experimental results demonstrated the capability of the proposed method to recover the sound speed close to the exact model in the absence of low-frequency information, whereas FWI, EI, GCN, and EGCN cannot. Experiments on phantoms of the human head and calf show that artificial source wavelets can reduce image artifacts and enhance reconstruction robustness, when original low-frequency information is absent.
SPFS: SNR peak-based frequency selection method to alleviate resolution degradation in MPI real-time imaging
Authors: Shan Shihao , Zhang Chenglong , Cheng Min , Qi Yafei , Yu Dexin , Wildgruber Moritz , Ma Xiaopeng
Published: April 2024

Objective. The primary objective of this study is to address the reconstruction time challenge in magnetic particle imaging (MPI) by introducing a novel approach named SNR-peak-based frequency selection (SPFS). The focus is on improving spatial resolution without compromising reconstruction speed, thereby enhancing the clinical potential of MPI for real-time imaging. Approach. To overcome the trade-off between reconstruction time and spatial resolution in MPI, the researchers propose SPFS as an innovative frequency selection method. Unlike conventional SNR-based selection, SPFS prioritizes frequencies with signal-to-noise ratio (SNR) peaks that capture crucial system matrix information. This adaptability to varying quantities of selected frequencies enhances versatility in the reconstruction process. The study compares the spatial resolution of MPI reconstruction using both SNR-based and SPFS frequency selection methods, utilizing simulated and real device data. Main results. The research findings demonstrate that the SPFS approach substantially improves image resolution in MPI, especially when dealing with a limited number of frequency components. By focusing on SNR peaks associated with critical system matrix information, SPFS mitigates the spatial resolution degradation observed in conventional SNR-based selection methods. The study validates the effectiveness of SPFS through the assessment of MPI reconstruction spatial resolution using both simulated and real device data, highlighting its potential to address a critical limitation in the field. Significance. The introduction of SPFS represents a significant breakthrough in MPI technology. The method not only accelerates reconstruction time but also enhances spatial resolution, thus expanding the clinical potential of MPI for various applications. The improved real-time imaging capabilities of MPI, facilitated by SPFS, hold promise for advancements in drug delivery, plaque assessment, tumor treatment, cerebral perfusion evaluation, immunotherapy guidance, and in vivo cell tracking.
Deep learning and radiomics-based approach to meningioma grading: exploring the potential value of peritumoral edema regions
Authors: Zhang Zhuo , Miao Ying , Wu JiXuan , Zhang Xiaochen , Ma Quanfeng , Bai Hua , Gao Qiang
Published: April 2024

Objective. To address the challenge of meningioma grading, this study aims to investigate the potential value of peritumoral edema (PTE) regions and proposes a unique approach that integrates radiomics and deep learning techniques. Approach. The primary focus is on developing a transfer learning-based meningioma feature extraction model (MFEM) that leverages both vision transformer (ViT) and convolutional neural network (CNN) architectures. Additionally, the study explores the significance of the PTE region in enhancing the grading process. Main results. The proposed method demonstrates excellent grading accuracy and robustness on a dataset of 98 meningioma patients. It achieves an accuracy of 92.86%, precision of 93.44%, sensitivity of 95%, and specificity of 89.47%. Significance. This study provides valuable insights into preoperative meningioma grading by introducing an innovative method that combines radiomics and deep learning techniques. The approach not only enhances accuracy but also reduces observer subjectivity, thereby contributing to improved clinical decision-making processes.
Interaction of atmospheric pressure helium plasma jet with non-planar substrates: path selectivity of surface ionization wave
Authors: Liu Guoqiang , Zhou Jiateng , Xia Yang , Wang Yuxin , Liu Dongping
Published: April 2024

Most surfaces treated by atmospheric pressure plasma jets (APPJs) in practical applications are notably three-dimensional. However, non-planar surfaces exhibit a diverse array of geometries, such as variations in curvature, roughness, and texture, complicating the prediction of surface ionization waves (SIWs) propagation behavior across varied surface shapes, in the absence of sufficient experimental data. In this study, we made measurements of APPJ interactions with the non-planar substrates using the spatio-temporal resolved image method. Non-planar substrates encompassed wavy surfaces, arrayed hemispheres, and randomly textured raised surfaces. We tracked the morphology and velocity of SIW propagation over these surfaces. The results indicate that the SIW propagation on non-planar surfaces is significantly influenced by surface geometry and displays path selectivity, i.e. the SIW tends to propagate along valleys. The average propagation velocity of the SIW increases with the increasing radius of the wavy surface, as well as with the increased height of the arrayed hemispheres. This is attributable to the surface geometry constraining the dispersion of the SIW, causing it to concentrate and propagate in a singular direction. Moreover, the surface geometry markedly affects the distribution of the plasma treatment area, with the plasma inclined to enter valleys (where the light emission is significantly stronger than that of peaks) and to closely adhere to hemispherical surfaces. These patterns suggest a potential positive impact on treating skin surfaces such as pores, reducing bacteria in wrinkles, and addressing pimples.
Advancing 4D printing through designing interlocking blocks: enhancing deformation uniformity in active composite structures
Authors: Benyahia Kheira , Seriket Hichem , Blanquer Sébastien , Gomes Samuel , Bodaghi Mahdi , André Jean-Claude , Zhou Kun , Qi H Jerry , Demoly Frédéric
Published: April 2024

Interlocking assemblies have been explored to address large assembly and complex parts and are now integral to additive manufacturing (AM) for creating objects with dissimilar materials and multiple properties. 4D printing technology, which combines smart materials (SMs) with AM, aligns with this approach by enabling the creation of objects that can change shape or properties when exposed to external stimuli. As 4D printing trends towards strategically arranging active and passive materials for improved control and performance, challenges arise due to the limited compatibility of existing 3D printers with the required SM properties. To address this issue, interlocking blocks of dissimilar materials can be printed and then assembled into a desired shape. This work aims to generalize the applicability of the interlocking block assembly approach. This will be achieved by improving the deformation uniformity in a 4D multi-material interlocked assembly. This paper also addresses limitations that can occur due to the interfaces between interlocking blocks, such as lack of deformation and contact continuity. Thus, it will be a question of customizing the shapes of the blocks in the early stages of assembly generation, considering SMs and their potential transformations. Finally, this approach is illustrated with an example, shedding light on the practical implications.
Enhanced magnetically coupled rotational piezoelectric energy harvesting based on tailored centrifugal distance
Authors: Zhang Yunshun , Wang Xin , Wang Wanshu
Published: April 2024

To tackle the issue of limited operating bandwidth encountered by energy harvesters in high-speed rotating contexts, this paper proposes a method for achieving rotational energy harvesting over a relatively high bandwidth through stabilizing high-energy orbit oscillations based on theoretically tailored centrifugal distance. The interaction between the cantilever beam tip permanent magnet and the fixed end magnet introduces nonlinear factors into the rotating piezoelectric energy harvesting system. By exploiting the non-linear matching relationship between the jump-down frequency under bistable condition and the rotational frequency of the external environment, the centrifugal distance theoretically derived is divided into five distinct conditions. Notably, when the centrifugal distance is in condition of 6.5 cm, optimal alignment and overlap are observed between the jump-down curve and the rotational frequency curve within the rotational frequency range of 40–80 rad s−1. Tailoring of different centrifugal distances across the five conditions is then explored and validated through simulations, including velocity profiles and energy harvesting capabilities. Finally, a rotating experimental platform was constructed and the experimental results validate that, at the theoretically tailored centrifugal distance of 6.5 cm, the rotating energy harvester achieves a peak power output of 127.4 μW within the effective bandwidth of 40–80 rad s−1. This study underscores the significance of tailoring centrifugal distance to stabilize high-energy orbit oscillations, thereby enhancing the energy harvesting potential of the device across a relatively wide range of external rotational frequencies.
3D modeling and measurement of HTS tape stacks in linear superconducting magnetic bearings
Authors: Ghabeli Asef , Fuchs Günter , Hänisch Jens , Zhou Pengbo , de Haas Oliver , Morandi Antonio , Grilli Francesco
Published: April 2024

Superconducting magnetic bearings (SMBs) are among the possible new technologies to be incorporated in maglev vehicles. Stacks of high-temperature superconductor (HTS) tapes can be used as an alternative to bulks, because stacks offer better mechanical properties, a better thermal conductivity and a simpler production process. Numerical modeling has been employed as a cost-effective, fast and reliable tool for improving the performance of SMBs. Several scenarios can be simulated with fast and relatively simple 2D models; however, in some cases using 3D models is inevitable. In this study, we use a full 3D model to solve the problem of magnetization of the tape stacks and obtaining the hysteresis force loop between a permanent magnet and the tape stacks. For this purpose, we employ an energy minimization-based method called minimum electromagnetic entropy production in 3D, combined with a homogenization technique and the

J
c

(
B
,
θ
)

dependence of the HTS tape as input. The modeling results agree very well with the experiment both in the zero-field cooled and field-cooled conditions. The presented approach offers significant computational advantages, delivering faster and more efficient results compared to previously proposed 3D methods.
Unveiling the growth mechanism of FeSeTe films by pulsed laser deposition technique
Authors: Zhang Jia-Ying , He Ya-Xun , He Tian , He Jing-Yu , Wu Wei-Bin , Ge Jun-Yi
Published: April 2024

The superconductivity of FeSeTe films, deposited by the pulsed laser deposition (PLD), is extremely sensitive to the preparation conditions. Hence, it is necessary to study the growth mechanism and reveal the key factors affecting the superconductivity of FeSeTe films. Among all the preparation conditions, the substrate temperature (

T

s

) is one of the most critical one because it can alter the diffusion and nucleation of deposited atoms, as well as subsequent secondary volatilization. In this study, we prepared a series of FeSeTe films deposited on CaF2 substrates with

T

s

ranging from 25 ∘C to 700 ∘C. It is found that the growth mechanism of the FeSeTe films deposited at different

T

s

is determined by the competition between crystallization and volatilization, and the

T

s

can serve as an effective means to regulate the (Se+Te):Fe ratio of the FeSeTe films. The superconductivity of the FeSeTe films is co-modulated by the crystallinity and composition. In addition, the

T

s

can greatly affect the pinning mechanism of the FeSeTe films by introducing the fine nonstoichiometric particles, local chemical inhomogeneity and planar defects. This work facilitates the further performance improvement and practical applications of FeSeTe superconducting films, and is of reference for the FeSeTe film prepared by other deposition methods.
NbN-based tunnel-type π-junctions for low-power half-flux-quantum circuits
Authors: Pham Duong , Li Feng , Oba Kenjiro , Takeshita Yuto , Tanaka Masamitsu , Yamashita Taro , Fujimaki Akira
Published: April 2024

We have developed half-flux-quantum (HFQ) circuits using all-π-junctions formed from an NbN/AlN/PdNi/NbN (SIFS) structure. The circuits were fabricated using a novel process that incorporated a ground plane on top of the chip, enabling the epitaxial growth of NbN-based junctions from the substrate. The π-state of the junctions was demonstrated through a HFQ shift. Notably, these π-junctions exhibited self-overdamped current-voltage characteristics, enabling them to function as switching components without the need for shunt resistors. The elimination of shunt resistors and the high sheet inductance of NbN are expected to enhance the density of HFQ circuits. To evaluate the performance and power consumption of the all-π-junctions HFQ circuits, we designed and fabricated an HFQ toggle flip-flop (HFQ-TFF) circuit utilizing π-π-π SQUIDs as the fundamental components. Our findings reveal that the NbN-based HFQ-TFF circuit correctly operates as a frequency divider while consuming only around 30% of the power compared to single-flux-quantum TFF (SFQ-TFF) circuits. These results suggest that the HFQ circuit using SIFS-π-junctions has promising potential for integrated circuits requiring low-power consumption at cryogenic temperatures, such as qubit control.