bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance evaluation of linearization strategies for a directly interfaced thermistor
Authors: Ul Abdin Muhammad Zain , Sami Abdul , Asif Ali , Aziz Farah
Published: August 2023

Sensor linearization is an important aspect for enhancing the efficiencies of measuring systems. Conventional methods use additional circuits and/or software models to achieve linearization. The direct interface technique obviates the requirement for intermediate electronic circuits, including linearization circuits, between sensors and embedded systems. Sensor linearization strategies need to be explored to obtain maximized performances from directly interfaced sensing systems. In this work, the performances of both hardware- and software-based strategies for linearization of directly interfaced thermistor sensors are evaluated. The experimental results show that the hardware-based linearization approach (1P_Shunt, 2P_Shunt) can yield a maximum linearized output range, i.e. from 0 °C to ∼70 °C with <1% full scale span (FSS) nonlinearity error (NLE). The sensitivities in both cases are found to be comparable. In 1P_Shunt, the linearized range is found to be almost independent of the β-values, ranging from 3012 K to 3924 K. A high-speed timer, via minimization of quantization errors, allows a significant reduction in measurement time while maintaining the linearized range. With the artificial neural network based linearization approach, a linearized range up to 100 °C and beyond can be achieved. A shallow network with optimum architecture (1-5-1), with Bayesian regularization and log-sigmoid as an activation function, is found to be sufficient to yield <1% FSS NLE.
Extracting weak electromagnetic signals based on RMPSO-SPBSR in virtual anechoic chamber
Authors: Yao Jinjie , Guo Yurong , Bai Jiansheng , Miao Jing , Wang Chenguang
Published: August 2023

To enhance the signal extraction performance at weak noise intensity in virtual anechoic chamber, this study investigates the correlation between the generation conditions of a stochastic resonance (SR) system and its output performance. To achieve optimal resonance effects, an adaptive system called symmetric piecewise bistable SR (SPBSR) is proposed. This system improves its structure by modifying the potential function to facilitate the occurrence of SR. Meanwhile, it combines a regional multi-role strategy and particle swarm optimization algorithm to determine the optimal structural parameters. The adaptive optimization process utilizes update rules that balance global and local optimal solutions, thereby mitigating the tendency to quickly converge to a local optimum. Experimental results demonstrate that the proposed system exhibits excellent performance within a noise intensity range of 0–10 dB, with a correlation coefficient of over 0.75, which can effectively suppress noise interference. In practical signal processing, the system excels at accurately extracting signal characteristics, resulting in improved similarity and smoothness of the detected signal. Both simulation and experimental results validate this algorithm’s strong practical relevance.
Improved cycling performance of silicon-based nanocomposites with pyrolytic polyacrylonitrile for lithium-ion batteries
Authors: Sun Jichang , Li Aohan , Zheng Penglun , Zheng Yun
Published: August 2023

The Si/FeSi2@C composite material offers several advantages due to its unique design. It effectively combines the high capacity and safety features of the Si negative electrode with FeSi2’s stabilizing properties. By incorporating a homogeneous carbon layer, the composite material enhances electrical conductivity and provides structural support, thereby mitigating the detrimental effects of significant volume expansion resulting from repeated insertion and extraction of lithium ions. Furthermore, the composite material contributes to stabilizing the solid-electrolyte interphase (SEI) film, which is a critical factor in battery performance. The improved SEI film stability, combined with the overall enhancement in electronic conductivity, significantly enhances the performance of the negative electrode. Test results demonstrate that the composite, consisting of pyrolyzed polyacrylonitrile and Si/FeSi2 nanoparticles, exhibits excellent electrochemical properties. During the first charging cycle, the composite material achieves a specific capacity of 1280 mAh g−1. Impressively, after 200 cycles, the specific capacity of the composite doubles compared to that of the raw material, indicating a remarkable improvement in cycling stability. These findings highlight the positive impact of rational material design on the performance of the Si/FeSi2@C composites.
ROP-GAN: an image synthesis method for retinopathy of prematurity based on generative adversarial network
Authors: Hou Ning , Shi Jianhua , Ding Xiaoxuan , Nie Chuan , Wang Cuicui , Wan Jiafu
Published: August 2023

Objective. Training data with annotations are scarce in the intelligent diagnosis of retinopathy of prematurity (ROP), and existing typical data augmentation methods cannot generate data with a high degree of diversity. In order to increase the sample size and the generalization ability of the classification model, we propose a method called ROP-GAN for image synthesis of ROP based on a generative adversarial network. Approach. To generate a binary vascular network from color fundus images, we first design an image segmentation model based on U2-Net that can extract multi-scale features without reducing the resolution of the feature map. The vascular network is then fed into an adversarial autoencoder for reconstruction, which increases the diversity of the vascular network diagram. Then, we design an ROP image synthesis algorithm based on a generative adversarial network, in which paired color fundus images and binarized vascular networks are input into the image generation model to train the generator and discriminator, and attention mechanism modules are added to the generator to improve its detail synthesis ability. Main results. Qualitative and quantitative evaluation indicators are applied to evaluate the proposed method, and experiments demonstrate that the proposed method is superior to the existing ROP image synthesis methods, as it can synthesize realistic ROP fundus images. Significance. Our method effectively alleviates the problem of data imbalance in ROP intelligent diagnosis, contributes to the implementation of ROP staging tasks, and lays the foundation for further research. In addition to classification tasks, our synthesized images can facilitate tasks that require large amounts of medical data, such as detecting lesions and segmenting medical images.
Color-guided deformable convolution network for intestinal metaplasia severity classification using endoscopic images
Authors: Li Zheng , Zheng Xiangwei , Mu Yijun , Zhang Mingzhe , Liu Guanqun
Published: August 2023

Objective. Intestinal metaplasia (IM) is a common precancerous condition for gastric cancer, and the risk of developing gastric cancer increases as IM worsens. However, current deep learning-based methods cannot effectively model the complex geometric structure of IM lesions. To accurately diagnose the severity of IM and prevent the occurrence of gastric cancer, we revisit the deformable convolution network (DCN), propose a novel offset generation method based on color features to guide deformable convolution, named color-guided deformable convolutional network (CDCN). Approach. Specifically, we propose a combined strategy of conventional and deep learning methods for IM lesion areas localization and generating offsets. Under the guidance of offsets, the sample locations of convolutional neural network adaptively adjust to extract discriminate features in an irregular way that conforms to the IM shape. Main results. To verify the effectiveness of CDCN, comprehensive experiments are conducted on the self-constructed IM severity dataset. The experimental results show that CDCN outperforms many existing methods and the accuracy has been improved by 5.39% compared to DCN, reaching 84.17%. Significance. To the best of our knowledge, CDCN is the first method to grade the IM severity using endoscopic images, which can significantly enhance the clinical application of endoscopy, achieving more precise diagnoses.
A generalizable new figure of merit for dose optimization in dual energy cone beam CT scanning protocols
Authors: Li Chenguang , Zhou Li , Deng Jun , Wu Hao , Wang Ruoxi , Wang Fei , Yao Kaining , Chen Chen , Niu Tianye , Zhang Yibao
Published: August 2023

Objective. This study proposes and evaluates a new figure of merit (FOMn) for dose optimization of Dual-energy cone-beam CT (DE-CBCT) scanning protocols based on size-dependent modeling of radiation dose and multi-scale image quality. Approach. FOMn was defined using Z-score normalization and was proportional to the dose efficiency providing better multi-scale image quality, including comprehensive contrast-to-noise ratio (CCNR) and electron density (CED) for CatPhan604 inserts of various materials. Acrylic annuluses were combined with CatPhan604 to create four phantom sizes (diameters of the long axis are 200 mm, 270 mm, 350 mm, and 380 mm, respectively). DE-CBCT was decomposed using image-domain iterative methods based on Varian kV-CBCT images acquired using 25 protocols (100 kVp and 140 kVp combined with 5 tube currents). Main results. The accuracy of CED was approximately 1% for all protocols, but degraded monotonically with the increased phantom sizes. Combinations of lower voltage + higher current and higher voltage + lower current were optimal protocols balancing CCNR and dose. The most dose-efficient protocols for CED and CCNR were inconsistent, underlining the necessity of including multi-scale image quality in the evaluation and optimization of DE-CBCT. Pediatric and adult anthropomorphic phantom tests confirmed dose-efficiency of FOMn-recommended protocols. Significance. FOMn is a comprehensive metric that collectively evaluates radiation dose and multi-scale image quality for DE-CBCT. The models and data can also serve as lookup tables, suggesting personalized dose-efficient protocols for specific clinical imaging purposes.
A learnable front-end based efficient channel attention network for heart sound classification
Authors: Liu Aolei , Zhang Sunjie , Wang Zhe , Tang Yiheng , Zhang Xiaoli , Wang Yongxiong
Published: August 2023

Objective. To enhance the accuracy of heart sound classification, this study aims to overcome the limitations of common models which rely on handcrafted feature extraction. These traditional methods may distort or discard crucial pathological information within heart sounds due to their requirement of tedious parameter settings. Approach. We propose a learnable front-end based Efficient Channel Attention Network (ECA-Net) for heart sound classification. This novel approach optimizes the transformation of waveform-to-spectrogram, enabling adaptive feature extraction from heart sound signals without domain knowledge. The features are subsequently fed into an ECA-Net based convolutional recurrent neural network, which emphasizes informative features and suppresses irrelevant information. To address data imbalance, Focal loss is employed in our model. Main results. Using the well-known public PhysioNet challenge 2016 dataset, our method achieved a classification accuracy of 97.77%, outperforming the majority of previous studies and closely rivaling the best model with a difference of just 0.57%. Significance. The learnable front-end facilitates end-to-end training by replacing the conventional heart sound feature extraction module. This provides a novel and efficient approach for heart sound classification research and applications, enhancing the practical utility of end-to-end models in this field.
Structural investigation of ultra-low resistance deeply recessed sidewall ohmic contacts for AlGaN/GaN HEMTs based on Ti/Al/Ti-metallization
Authors: Chen Ding-Yuan , Persson Axel R , Darakchieva Vanya , Persson Per O Å , Chen Jr-Tai , Rorsman Niklas
Published: August 2023

This study presents a novel approach to forming low-resistance ohmic contacts for AlGaN/GaN HEMTs. The optimized contacts exhibit an outstanding contact resistance of approximately 0.15 Ω·mm. This is achieved by firstly recessing the barrier of the heterostructure to a depth beyond the channel. In this way, the channel region is exposed on the sidewall of the recess. The coverage of the Ti/Al/Ti ohmic metalization on the sidewall is ensured through tilting of the sample during evaporation. The annealing process is performed at a low temperature of 550 °C. The approach does not require precise control of the recess etching. Furthermore, the method is directly applicable to most barrier designs in terms of thickness and Al-concentration. The impact of recessed sidewall angle, thickness and ratio of Ti and Al layers, and the annealing procedure are investigated. Structural and chemical analyses of the interface between the ohmic contacts and epi-structure indicate the formation of ohmic contacts by the extraction of nitrogen from the epi-structure. The approach is demonstrated on HEMT-structures with two different barrier designs in terms of Al-concentration and barrier thickness. The study demonstrate large process window in regard to recess depth and duration of the annealing as well as high uniformity of the contact resistance across the samples, rendering the approach highly suitable for industrial production processes.
Modulation of vortex pinning by matrix defects in YBa2Cu3O7 nanocomposite film
Authors: Horide Tomoya , Higashi Kento , Ishimaru Manabu , Okada Tatsunori , Awaji Satoshi , Matsumoto Kaname
Published: August 2023

Nanorods are a very effective pinning center in YBa2Cu3O7 films, and the vortex pinning mechanism should be understood to further improve the critical current density (J
c) in the nanocomposite films. Matrix defects are naturally formed during nanocomposite growth, and in this study the effect of matrix defects on the J
c in the YBa2Cu3O7 films containing nanorods is discussed. YBa2Cu3O7 + BaHfO3 and YBa2Cu3O7 + BaSnO3 films were prepared by varying the laser repetition frequency to control the matrix defects. All the films contained the nanorods. The YBa2Cu3O7 + BaHfO3 film of 2 Hz exhibits high J
c for magnetic field parallel to the c-axis (B//c) due to the nanorods and the isolated random point defects. In the YBa2Cu3O7 + BaHfO3 film of 10 Hz, while the short stacking faults and networked random point defects decreased the J
c for B//c, the short stacking faults improved the J
c for tilted magnetic field. In the YBa2Cu3O7 + BaSnO3 film of 10 Hz, the isolated random point defects improved J
c regardless of the magnetic field direction. While the ab-plane correlated defects are analyzed by the structural observation, the network or isolated nature of the random point defects can be discussed by the normal state resistivity. The matrix defects of YBa2Cu3O7 nanocomposite films should be designed considering the correlated/network/isolated nature which is determined by the morphology and defect concentration.
Improved device-independent randomness expansion rates using two sided randomness
Authors: Bhavsar Rutvij , Ragy Sammy , Colbeck Roger
Published: August 2023

A device-independent randomness expansion (DIRE) protocol aims to take an initial random string and generate a longer one, where the security of the protocol does not rely on knowing the inner workings of the devices used to run it. In order to do so, the protocol tests that the devices violate a Bell inequality and one then needs to bound the amount of extractable randomness in terms of the observed violation. The entropy accumulation theorem lower bounds the extractable randomness of a protocol with many rounds in terms of the single-round von Neumann entropy of any strategy achieving the observed score. Tight bounds on the von Neumann entropy are known for the one-sided randomness (i.e. where the randomness from only one party is used) when using the Clauser–Horne–Shimony–Holt game. Here we investigate the possible improvement that could be gained using the two-sided randomness. We generate upper bounds on this randomness by attempting to find the optimal eavesdropping strategy, providing analytic formulae in two cases. We additionally compute lower bounds that outperform previous ones and can be made arbitrarily tight (at the expense of more computation time). These bounds get close to our upper bounds, and hence we conjecture that our upper bounds are tight. We also consider a modified protocol in which the input randomness is recycled. This modified protocol shows the possibility of rate gains of several orders of magnitude based on recent experimental parameters, making DIRE significantly more practical. It also enables the locality loophole to be closed while expanding randomness in a way that typical spot-checking protocols do not.
Breaking the mass law for broadband sound insulation through strongly nonlinear interactions
Authors: Fang Xin , Li Tao , Hu Bin , Yu Miao , Sheng Peng , Wen Jihong , Cheng Li
Published: August 2023

Sound transmission through panels is governed by the well-known mass law in the mid-frequency range. This paper reveals a possibility of breaking this density-dominant law through strongly nonlinear interaction, while broadening the bandwidth for effective sound insulation. For this purpose, a basic model is established, and corresponding exact analytical methods for bifurcation and stability analyses are proposed. Influences of four typical types of nonlinear interactions on the wave insulation are analytically and numerically investigated. We find that, by introducing strongly nonlinear interactions at appropriate locations, the nonlinear model can not only break the barrier imposed by the mass law, but also entails broadband sound insulation by 2–3 times relative to the optimal linear model. Meanwhile, the sound insulation valley due to the coincident effects can also be eliminated. With bifurcation and effective mass, we clarify that the enhanced wave insulation of the strongly nonlinear models arises from the broader band of super mass induced by strongly nonlinear local resonances, which depends on the bifurcation of periodic solutions. The proposed models and the findings provide a solid basis and new possibilities for wave insulation in complex nonlinear structures and nonlinear acoustic metamaterials.
Performance comparison and analysis of D-type single and dual-core PCF-SPR sensors
Authors: Li Yunqiang , Chen Chuntian , Liu Xin , Gong Aina , Shen Tao
Published: August 2023

Surface plasmon resonance sensors, based on photonic crystal fibers, have demonstrated immense potential in various application fields, owing to their structural design flexibility, operability, and superior sensing capabilities. Despite the potential, the design of photonic crystal fibers with various structures has been a challenging task, due to manufacturing constraints. Thus, this paper aims to explore the design rules of photonic crystal fibers based on surface plasmon resonance, by proposing and designing four photonic crystal fiber sensors with distinct structures. The study investigates the influence of single-core, double-core, and large and small air holes on the sensor’s performance, through theoretical analysis, numerical simulation, data acquisition, and analysis. Through our research, we have discovered that by altering the size of pores surrounding the fiber core, as well as the fiber core’s single-mode and dual-mode configurations, we were able to increase the sensitivity of the sensor from its lowest value of 266 nm RIU−1 to as high as 2066 nm RIU−1, an improvement of nearly eightfold. The findings suggest that the sensor with double-core air hole structure exhibits relatively better performance. This analysis is expected to aid in the design of high-performance photonic crystal fiber-based surface plasmon resonance sensors.
Quantum walk state transfer on a hypercube
Authors: Štefaňák Martin , Skoupý Stanislav
Published: August 2023

We investigate state transfer on a hypercube by means of a quantum walk where the sender and the receiver vertices are marked by a weighted loops. First, we analyze search for a single marked vertex, which can be used for state transfer between arbitrary vertices by switching the weighted loop from the sender to the receiver after one run-time. Next, state transfer between antipodal vertices is considered. We show that one can tune the weight of the loop to achieve state transfer with high fidelity in shorter run-time in comparison to the state transfer with a switch. Finally, we investigate state transfer between vertices of arbitrary distance. It is shown that when the distance between the sender and the receiver is at least 2, the results derived for the antipodes are well applicable. If the sender and the receiver are direct neighbours the evolution follows a slightly different course. Nevertheless, state transfer with high fidelity is achieved in the same run-time.
Polarization characteristics of partially coherent radially and azimuthally polarized beams with vortex phase propagating through atmospheric turbulence
Authors: Xu Qian , Xu Yonggen , Zhao Liang , Liu Wenli , Liu Yongtao
Published: August 2023

Analytical formulas for the normalized spectral Stokes parameters of the partially coherent radially and azimuthally polarized beams with vortex phase (i.e., PCRPV and PCAPV beams) propagating through the turbulent atmosphere are derived. The polarization properties of PCRPV and PCAPV beams in atmospheric turbulence have been studied in detail. Our findings show that different correlation lengths induce nonuniform distribution to degree of polarization (DOP) and the normalized spectral Stokes parameters. And different correlation lengths also cause the polarization singularity splitting. Besides, we find also that the vortex phase will lead to the rotation of distributions of orientation angles and the normalized spectral Stokes parameters of PCRPV and PCAPV beams in turbulence, and the rotation degree will become obvious with increasing topological charge number. It can be found also that larger topological charge number can reduce the speed of polarization singularities destroyed by atmospheric turbulence, meaning that PCRPV and PCAPV beams with a larger topological charge has a stronger ability to resist atmospheric turbulence. Our studies could be important for free-space optical communications and polarization lidar system.
Diversity of exact solutions to the (2+1)-dimensional Ito equation via bilinear neural network method
Authors: Ma Wenbo , Sudao Bilige
Published: August 2023

Recently, searching for exact solutions to nonlinear partial differential equations has gradually become a hot research topic. It is of great scientific research and application value to reveal the law of wave propagation, explain natural phenomena accurately and apply related technologies scientifically. In this paper, bilinear neural network method (BNNM) was employed to obtain some new exact analytical solutions to the (2 + 1)-dimensional Ito equation. Based on the Hirota form of Ito equation, we constructed activation functions f in various forms containing the exp(ξ), sin(ξ), cos(ξ), cosh(ξ) and squares of polynomial functions in multi-layer neurons such as [3-2-2] and [3-2-3] neural network models. The test function f in this work is a new expression. On the other hand, these solutions have not been studied yet. As a result, we obtained several new interaction solutions, such as periodic wave solution, breather solution and bright-dark soliton solution, etc. In addition, the corresponding 3D, density and contour plots of all the solution forms were drawn and their characters and dynamic behaviors were vividly demonstrated.
Controlling the thermal and electric fields in isotropic and anisotropic media
Authors: Raza Muhammad , Rybin Oleg , Ahsan Muhammad , Alonazi Wadi B , Rameen Kiran
Published: August 2023

In this study, we theoretically propose cloaking and concentration devices allowing simultaneous control of electric and thermal fields in spherically inhomogeneous layered medium with isotropic and anisotropic layers. The above combination of layers (isotropic and anisotropic ones) is obtained by the transformation coordinate approach applied to a spherically inhomogeneous layered medium which contains isotropic and anisotropic layers. It is shown that in steady-state conditions, both thermal and electric fields can pass smoothly around the targeted area while preventing any disturbance in the surrounding medium. The constitutive parameters of both fields have been determined analytically. In this work, we have combined two different methodologies to achieve cloaking in ideal state and in homogenized structure for cylindrical and spherical cases. Numerical validation of the obtained solutions using COMSOL software is performed in this study.
Control effect of superhydrophobic grooves on flow-induced noise generated by flow around cylindrical shell at large Reynolds number
Authors: Niu Chen , Qin Qikai , Liu Yongwei , Shang Dejiang , Liu Wenbo
Published: August 2023

Flow-induced noise is an important factor affecting the quiet performance of underwater vehicles. Superhydrophobic surfaces are an emerging technology for underwater vehicles. In this study, a superhydrophobic surface is innovatively applied to the flow-induced noise control of underwater cylindrical shells. Alternating no-slip and no-shear surfaces are used to simulate the superhydrophobic surface with spanwise superhydrophobic grooves so that the flow regime and flow-induced noise of a no-slip cylinder are compared with the superhydrophobic cylinder under a high Reynolds number. The results show that the superhydrophobic surface can effectively delay flow separation and control the size of the wake shedding vortex. The flow-shedding vortices mainly affect the flow-induced noise in the lower frequency range, which is consistent with the vortex shedding frequency. The radiation characteristics of the flow-induced noise generated by the fluctuation pressure are mainly influenced by the eigenfrequency of the model in the range of 100 Hz–5000 Hz. Moreover, the superhydrophobic surface can effectively reduce the flow-induced noise and change its radiation directivity at both high and low frequencies by controlling vortex shedding and reducing the fluctuation pressure, respectively. The findings reported here shed new light on the flow-induced noise control of underwater vehicles.
Quantum dots luminescent compounds with multimodal luminescence for fuel labeling
Authors: Sagdeev Dmitriy O , Shamilov Radik R , Galyametdinov Yuriy G
Published: August 2023

The article considers the possibility of labelling oil products using luminescent ‘fingerprints’ based on several types of quantum dots to protect fuel from falsification. For the synthesis of quantum dots, a scalable universal method was proposed using an available large-producible solvent and a stabilizer, oleic acid. Using the developed technique, quantum dots were obtained that luminescence in the entire visible range of the electromagnetic radiation spectrum. The formation of nanoparticles was confirmed by a set of instrumental research methods. The determination of the presence of quantum dots in the composition of an oil product was proposed using spectrofluorometry with no additional separation or dialization of nanoparticles from the sample. Using normal regular gasoline as an example, the effect of fuel on the luminescence of quantum dots and their aggregation was studied. The interaction of different types of quantum dots in the composition of the indicator and their influence on each other’s luminescence in solvent and gasoline were analyzed. The minimum detectable by the spectrofluorometric method concentrations of quantum dots in normal gasoline and the optimal proportions of quantum dots of various types in mixtures were determined.
Highly-rectified hybrid p-MAPbBr3/n-GaN heterojunction ultraviolet photodetector featuring high-photoresponse
Authors: Zhang Maolin , Ma Wanyu , Zhang Qiong , Bian Ang , Liu Zeng , Yang Lili , Li Shan , Guo Yufeng , Tang Weihua
Published: August 2023

GaN-based photodetectors have demonstrated promising performance and find wide applications in ultraviolet sensing. In recent times, perovskite materials have also attracted significant attention due to their intriguing photoelectrical properties. In this study, we constructed a heterojunction photodetector by combining MAPbBr3 and GaN, and examined its detection capabilities. We conducted measurements of the current–voltage and current–time characteristics of the device. Our results showcased superior detection metrics, including a rectification ratio of 2.57 × 106 and a photo-to-dark current ratio of 1.52 × 105. Meanwhile, a responsivity of 1.02 A W−1, a detectivity of 4.81 × 1013 Jones and an external quantum efficiency of 346.8% under −5 V bias were achieved. Responsivity, detectivity and external quantum efficiency are significantly improved in the forward condition at the expense of low photo-to-dark current ratio and high dark current. The self-driven characteristics, non-linear photocurrent, and the persistent photoconductive effect observed in the photodetector were also discussed. Additionally, we provided guidance for further enhancements of the hybrid perovskite/GaN ultraviolet photodetector.
Linearity improvement in graded channel AlGaN/GaN HEMTs for high-speed applications
Authors: Jena Devika , Das Sanghamitra , Baral Biswajit , Mohapatra Eleena , Dash Taraprasanna
Published: August 2023

AlGaN HEMTs are popular devices for high-frequency applications. At higher frequencies, nonlinearity effects are major concerns and need serious attention. In this work, we have attempted to improve the linearity performance of graded channel Al
x
Ga1−x
N/GaN HEMTs in comparison with abrupt channel GaN HEMTs through Technology Computer Aided (TCAD) simulation. In graded channel HEMTs, linearly grading of Al composition in the AlGaN layer, reduces the local carrier densities and provides improvement in the carrier saturation velocity. This provides an avenue to improve the overall linearity performance. A complete set of figures of merits (FOMs) such as

g

m
2

,

g

m
3

,

VIP

2

,

VIP

3

,

IIP

3

and

IMD

3

for both devices are presented. The simulation results have been calibrated with reported experimental results available in the literature. The graded devices are observed to have better transconductance (g

m
) and drain current for gate voltages greater than −2 V. The drop in g

m
is reduced by nearly 50% at the higher gate-to-source voltages. Moreover, the RF figure of merits such as the current gain cutoff frequency (f
T) and a maximum frequency of oscillation (f
max) have been calculated for both devices. Due to the graded channel f

T
increases by 20% and f
max becomes twice which makes it a better choice for high-voltage and high-power applications. The impact of interface trap and leakage current performance on the graded channel device are also reported. The cutoff frequency reduces by 25% with an increase in trap charge concentration from 9e17 cm−2 to 1e19 cm−2. Also, it has been found that the graded channel device shows better linearity and lower intermodulation distortion in comparison to the abrupt device which has been calculated from the linearity parameters. The high gate leakage current in the case of the graded channel device can be reduced by adding a thin GaN cap layer on the AlGaN channel which can be a future prospect of improving the performance of the graded GaN device.
Enhancing the fatigue strength of stir-casted Al7075-SiC composites through heat treatment and shot peening
Authors: Raghuvaran P , Suresh M , Narasimharaj V , Rajesh A
Published: August 2023

An attempt has been made in the present study to analyze the impact of shot peening on the fatigue strength of Al-SiC (8 wt%) composites. Composite samples prepared using stir casting method is machined to meet ASTM E466 standards, and a portion of them are subjected to T6 heat treatments. Shot peening is performed on various combinations of specimens, and fatigue tests are conducted and compared. The fatigue strength of Al7075 is 156.5 MPa and it increases to 165.8 MPa for heat-treated shot-peened Al-SiC composites. Design expert software is used for designing experiments in order to optimize process parameters and enhance the fatigue strength of the specimens. The fatigue strength of the specimens increased to 174 MPa when the test was repeated using optimized experimental parameters. The fatigue test results revealed that the heat-treated, cum shot-peened Al-SiC composite exhibited the highest performance compared to the other samples. Surface residual stress of the specimens is measured, and it is found that shot peening increases the compressive residual stress on the surface of the specimen. The surface roughness of the specimen increases with shot peening. Microstructural analysis is conducted on the specimens to determine the effect of shot peening on the surface of the composite specimens. The strengthening mechanisms of the composite samples are discussed using microstructural images.
An artificial intelligence–based pipeline for automated detection and localisation of epileptic sources from magnetoencephalography
Authors: Zheng Li , Liao Pan , Wu Xiuwen , Cao Miao , Cui Wei , Lu Lingxi , Xu Hui , Zhu Linlin , Lyu Bingjiang , Wang Xiongfei , Teng Pengfei , Wang Jing , Vogrin Simon , Plummer Chris , Luan Guoming , Gao Jia-Hong
Published: August 2023

Objective. Magnetoencephalography (MEG) is a powerful non-invasive diagnostic modality for presurgical epilepsy evaluation. However, the clinical utility of MEG mapping for localising epileptic foci is limited by its low efficiency, high labour requirements, and considerable interoperator variability. To address these obstacles, we proposed a novel artificial intelligence–based automated magnetic source imaging (AMSI) pipeline for automated detection and localisation of epileptic sources from MEG data. Approach. To expedite the analysis of clinical MEG data from patients with epilepsy and reduce human bias, we developed an autolabelling method, a deep-learning model based on convolutional neural networks and a hierarchical clustering method based on a perceptual hash algorithm, to enable the coregistration of MEG and magnetic resonance imaging, the detection and clustering of epileptic activity, and the localisation of epileptic sources in a highly automated manner. We tested the capability of the AMSI pipeline by assessing MEG data from 48 epilepsy patients. Main results. The AMSI pipeline was able to rapidly detect interictal epileptiform discharges with 93.31% ± 3.87% precision based on a 35-patient dataset (with sevenfold patientwise cross-validation) and robustly rendered accurate localisation of epileptic activity with a lobar concordance of 87.18% against interictal and ictal stereo-electroencephalography findings in a 13-patient dataset. We also showed that the AMSI pipeline accomplishes the necessary processes and delivers objective results within a much shorter time frame (∼12 min) than traditional manual processes (∼4 h). Significance. The AMSI pipeline promises to facilitate increased utilisation of MEG data in the clinical analysis of patients with epilepsy.
Comparison of momentum transport in matched hydrogen and deuterium H-mode plasmas in ASDEX Upgrade
Authors: Zimmermann C.F.B. , McDermott R.M. , Angioni C. , Duval B.P. , Dux R. , Fable E. , Salmi A. , Stroth U. , Tala T. , Tardini G. , Pütterich T. ,   the ASDEX Upgrade Team
Published: August 2023

Advanced momentum transport analysis is used to study matched hydrogen (H) and deuterium (D) plasmas in the core of ASDEX Upgrade. The aim is to validate gyrokinetic theory and assess a possible isotope dependence. The methodology extracts momentum diffusion, convection, and intrinsic torque as a function of time from experiments employing neutral beam injection (NBI) modulation. H and D plasma scenarios with comparable ion heat fluxes, NBI torque, electron densities, and several dimensionless parameters were designed to highlight any mass dependency. Linear gyrokinetic simulations predict that, for similar background gradients, the Prandtl and pinch numbers should be similar for H and D. This was confirmed by the experimental momentum transport analyses. The assessed intrinsic torques were found to be similar between H and D, co-current directed and located near the outermost region of the plasma core. The strength of the intrinsic torque is correlated with the amplitude of the plasma pressure gradient in the pedestal. Finally, a robust error analysis demonstrates the uniqueness of the parameters obtained together with their uncertainties. Neglecting the intrinsic torque, or its time dependence, systematically distorts the assessed momentum diffusion and convection. This is the first method to separate all three transport mechanisms from experimental data by retaining their time dependencies, that is found to match, quantitatively, the gyrokinetic predictions for Prandtl and pinch numbers, within experimental uncertainties.
Religion, Religiosity and Parenting Practices: An Examination of Jewish, Muslim, Christian and Druze Mothers in Israel
Authors: Eseed Rana , Zadok Iris , Khoury Mona
Published: August 2023

The role of religiosity in shaping family functioning, in general, and parental discipline, in particular, have received wide research attention, especially in studies conducted amongst Christian parents from Western cultures. Little is known about the relationship between religiosity and parenting in non-Western cultures. The current study explored the role religion and religiosity play in predicting maternal use of psychological control and punitive discipline of mothers from Israel who belong to two ethnonational groups: Jews and Arabs, and who represent four religions: Jewish, Muslims, Christian and Druze. The study was based on a survey of 502 Israeli mothers of children aged three to five years (31.6 per cent Jewish, 36.0 per cent Muslims, 16.8 per cent Christians and 15.6 per cent Druze). Mothers were asked to fill out an online structured, anonymous self-report questionnaire survey distributed through social networks. We used multivariate hierarchal regression to explore the role of religion and religiosity in predicting mother’s use of punitive discipline and psychological control, after controlling for child and family factors. The results showed that religiosity was significantly and positively associated with mothers’ use of both psychological control and punitive discipline. Furthermore, it was found that Arab mothers reported using psychological control more than did Jewish mothers.
Mechanisms for Support: A Realist Evaluation of Peer Parental Advocacy in England
Authors: Fitz-Symonds Samantha , Evans Lilly , Tobis David , Westlake David , Diaz Clive
Published: August 2023

International research shows that although parents perceive the child protection system to be stigmatising and authoritarian, peer parental advocacy (PPA) programmes have a positive impact on improving complex relationships between parents and professionals. PPA programmes enable parents with lived experience of child protection processes to support other parents to navigate the system. As an emerging area of policy interest, research investigating the role of PPA in empowering parents to participate meaningfully in decision-making is crucial to developing collaborative approaches within child protection social work. This realist-informed study considered how a newly implemented PPA programme supported parents in two English Local Authorities. Our findings highlight the unique role peer advocates can play as a resource to influence decision-making, power relations and working relationships between professionals and parents. This article presents our final programme theory, which identifies four key mechanisms that support perceived effectiveness in PPA implementation: active engagement, effective communication, facilitating trust and adequate support for advocates. These findings highlight how PPA programmes in these Local Authorities were valued and begin to build a picture of how further advocacy programmes can be explored throughout the UK.
Relationship between default mode network and resting-state electroencephalographic alpha rhythms in cognitively unimpaired seniors and patients with dementia due to Alzheimer’s disease
Authors: Babiloni Claudio , Lopez Susanna , Noce Giuseppe , Ferri Raffaele , Panerai Simonetta , Catania Valentina , Soricelli Andrea , Salvatore Marco , Nobili Flavio , Arnaldi Dario , Famà Francesco , Massa Federico , Buttinelli Carla , Giubilei Franco , Stocchi Fabrizio , Vacca Laura , Marizzoni Moira , D'Antonio Fabrizia , Bruno Giuseppe , De Lena Carlo , Güntekin Bahar , Yıldırım Ebru , Hanoğlu Lutfu , Yener Görsev , Yerlikaya Deniz , Taylor John Paul , Schumacher Julia , McKeith Ian , Bonanni Laura , Pantano Patrizia , Piervincenzi Claudia , Petsas Nikolaos , Frisoni Giovanni B , Del Percio Claudio , Carducci Filippo
Published: August 2023

Here we tested the hypothesis of a relationship between the cortical default mode network (DMN) structural integrity and the resting-state electroencephalographic (rsEEG) rhythms in patients with Alzheimer’s disease with dementia (ADD). Clinical and instrumental datasets in 45 ADD patients and 40 normal elderly (Nold) persons originated from the PDWAVES Consortium (www.pdwaves.eu). Individual rsEEG delta, theta, alpha, and fixed beta and gamma bands were considered. Freeware platforms served to derive (1) the (gray matter) volume of the DMN, dorsal attention (DAN), and sensorimotor (SMN) cortical networks and (2) the rsEEG cortical eLORETA source activities. We found a significant positive association between the DMN gray matter volume, the rsEEG alpha source activity estimated in the posterior DMN nodes (parietal and posterior cingulate cortex), and the global cognitive status in the Nold and ADD participants. Compared with the Nold, the ADD group showed lower DMN gray matter, lower rsEEG alpha source activity in those nodes, and lower global cognitive status. This effect was not observed in the DAN and SMN. These results suggest that the DMN structural integrity and the rsEEG alpha source activities in the DMN posterior hubs may be related and predict the global cognitive status in ADD and Nold persons.
Joan Robinson’s historical time and the current state of post-Keynesian growth theory
Authors: Gallo Ettore , Setterfield Mark
Published: August 2023

This paper discusses Joan Robinson’s remarks on the importance of historical time in economic analysis. On the one hand, Joan Robinson expressed skepticism with equilibrium analysis as such, arguing that as soon as economists take into account the uncertainty of expectations, history needs to replace equilibrium. On the other hand, Robinson stressed that, while building economic models, one must be aware that it is historical time rather than logical time that rules reality, warning against the methodological mistake of confusing comparisons of equilibrium positions with a movement between them. We argue that these criticisms point to the possibility of thinking in terms of two different ‘levels’ of historical time—a higher (fundamentalist) level, and a practical (and more analytically tractable) lower level. Using this distinction, we provide a taxonomy of existing strands of post-Keynesian growth theory that are consistent with the concept of low-level historical time. It is shown that despite appearances to the contrary, much post-Keynesian growth theory displays fidelity to Joan Robinson’s concern with the importance of historical time.
Schizophrenia Patients Discharged on Clozapine Plus Long-Acting Injectable Antipsychotics From a Public Psychiatric Hospital in Taiwan, 2006–2021
Authors: Lin Ta-Chun , Lin Ching-Hua
Published: August 2023

Background

Some schizophrenia patients treated with clozapine experience an inadequate response and adherence problems. The purpose of this study was to compare time to rehospitalization within 6 months in schizophrenia patients discharged on 3 clozapine regimens. Additionally, the temporal trend of prescription rate in each group was also explored.

Methods

Schizophrenia patients discharged from the study hospital from January 1, 2006, to December 31, 2021, (n = 3271) were included in the analysis. The type of clozapine prescribed at discharge was divided into 3 groups: clozapine plus long-acting injectable antipsychotics (clozapine + LAIs), clozapine plus other oral antipsychotics (clozapine + OAPs), and clozapine monotherapy. Survival analysis was used to compare time to rehospitalization within 6 months after discharge among the 3 groups. The temporal trend in the prescription rate of each group was analyzed using the Cochran-Armitage Trend test.

Results

Patients discharged on clozapine + LAIs had a significantly longer time to rehospitalization than those on clozapine + OAPs or clozapine monotherapy. The prescription rates of clozapine + LAIs and clozapine + OAPs significantly increased over time, whereas the prescription rates of clozapine monotherapy significantly decreased.

Conclusions

Compared with the clozapine + OAPs group, the clozapine + LAIs group had a lower risk of rehospitalization and a lower dose of clozapine prescribed. Therefore, if a second antipsychotic is required for patients who are taking clozapine alone, LAIs should be considered earlier.
Transition from Idealized Science to Culture of Skepticism in South Korea: Micro-Level Evidence for the Two-Culture Model of Public Understanding of Science
Authors: Kim Sei-Hill , Oh Sang-Hwa , Zain Ali , Heo Yujin , Jun Jungmi
Published: August 2023

Using data from a national survey in South Korea, this study offers micro-level evidence for the two-culture model of public understanding of science, which posits that a shift from an industrializing to a post-industrial society is accompanied by a transition from a culture of idealized science to a culture of skepticism. We investigate whether older South Koreans, who spent much of their lives during the intense industrialization of the country, hold more positive perceptions about science than younger generations, who grew up mostly in a post-industrial era. As predicted, older individuals perceived greater contributions of science, suggesting that they held more idealized perceptions of science than younger individuals. Perceived importance of economic development, scientific knowledge, ideology, uncertainty of scientific risks, and formal education mediated the link between age and perceived contributions of science, suggesting that these mediators may function as causal mechanisms that could explain why citizens in post-industrial societies tend to have more skeptical perceptions about science than those in industrializing countries.
Cofinal Elements and Fractional Dehn Twist Coefficients
Authors: Clay Adam , Ghaswala Tyrone
Published: August 2023

We show that for a surface $S$ with positive genus and one boundary component, the mapping class of a Dehn twist along a curve parallel to the boundary is cofinal in every left ordering of the mapping class group $\operatorname{Mod}(S)$. We apply this result to show that one of the usual definitions of the fractional Dehn twist coefficient—via translation numbers of a particular action of $\operatorname{Mod}(S)$ on $\mathbb{R}$—is in fact independent of the underlying action when $S$ has genus larger than one. As an algebraic counterpart to this, we provide a formula that recovers the fractional Dehn twist coefficient of a homeomorphism of $S$ from an arbitrary left ordering of $\operatorname{Mod}(S)$.