bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectral characteristics of DDPM streams and their application to all‐digital amplitude modulation
Authors: Crovetti P. S.
Published: January 2021

A new closed‐form expression of the spectral coefficients of the digital streams obtained by dyadic digital pulse modulation is presented and validated in this letter. The new expression provides in‐depth insight into the spectral properties of dyadic digital pulse modulation, revealing its applicability as an all‐digital bandpass amplitude modulation technique. Simulations and measurements on a proof‐of‐concept dyadic digital pulse modulation amplitude modulator prototype demonstrate the effectiveness of the approach.
Dual‐band orthogonal polarised shared aperture array with shared‐elements
Authors: Xu Jiachen , Guo Chenjiang , Ding Jun
Published: January 2021

In this paper, an orthogonal polarised dielectric resonator antenna (DRA) which can operate at S‐ and C‐band, has been designed as “shared‐element” for forming a dual‐band shared aperture array. Furthermore, in this shared aperture array, the S‐band array contains four shared‐elements, and the C‐band array contains four shared‐elements and twelve C‐band DRA elements. Moreover, a phase compensation power divider is employed to help offset the radiation performance differences between the two types of antenna elements when forming the C‐band array. A prototype array was fabricated and measured, showing that the antenna can cover the band of 2.4–2.63 GHz and 6.9–7.1 GHz, respectively. The isolation between bands is higher than 30 dB. The cross‐polarisation levels are less than ‐30 dB in both bands.
Multi‐layered PCB distributed filter
Authors: Bulja S. , Kozlov D.
Published: January 2021

In this paper, multi‐layered print circuit board distributed resonators and filters are introduced. Here, the individual elements of the distributed resonator are made as part of a multi‐layered print circuit board, commonly used in the circuitry of transceiver boards. In this way, the unused real estate available on the board is used effectively. As a demonstrator of the proposed technology, a 2‐pole filter fabricated using a 5‐layer substrate and consisting of a matrix of 11 × 11 elements per resonator is fabricated and its performance is measured. Due to a large number of individual elements, which perform dimensional averaging of manufacturing inaccuracies, the filter obtained in this way not only requires no post‐production tuning, but it also has an extremely low profile of 5o, which is the lowest profile to be reported in the literature. The filter was made to operate at a centre frequency of 1.8 GHz with an absolute bandwidth of 65 MHz. The measured and computed results are in good agreement.
Driver behaviour detection using 1D convolutional neural networks
Authors: Shahverdy M. , Fathy M. , Berangi R. , Sabokrou M.
Published: January 2021

Driver behaviour is an important factor in road safety. Computer vision techniques have been widely used to monitor the driver behaviour. The violation of privacy and the possibility of spoofing are two continuing challenges in camera‐based systems. To address these challenges, we propose an efficient approach to monitor and detect driver behaviour based on movement characteristics of the vehicle rather than the visual features of the driver. The main goal of this paper is to classify the driver behaviour into five classes: safe, distracted, aggressive, drunk, and drowsy driving. A lightweight 1D Convolutional Neural Network with high efficiency and low computational complexity is suggested to classify the driver behaviour. Experimental results confirm that our method could successfully classify behaviours of a driver with accuracy of 99.999%.
Spatially coupled serially concatenated codes via parity re‐encoding
Authors: Zhao Shancheng , Yang Chaojie , Wen Jinming
Published: January 2021

The recently introduced spatially coupled turbo‐like codes are attractive in trading‐off performances between the error‐floor region and the water‐fall region. This letter is concerned with the construction of spatially coupled serially concatenated codes. Particularly, a new construction of spatially coupled serially concatenated codes is presented, in which a portion of the encoding output of the previous inner encoder is taken as the input of the current inner encoder. The authors show that by proper selection of the component codes and the re‐encoding ratio, performance gain about 0.25 dB is obtained with the proposed construction.
Ultra‐wideband on‐body elliptical monopole antenna
Authors: Nguyen Duy Hai , Krozer Viktor , Moll Jochen , Zimmer Gernot
Published: January 2021

This study presents an ultra‐wideband, elliptical slot, planar monopole antenna for early breast cancer microwave imaging. The on‐body antenna's operation is optimised by direct contact with the patient's skin. With a compact size of 9 × 7 mm, the antenna covers a wide bandwidth from 16 to 24 GHz for reflection coefficients lower than –10 dB. Besides, it also features an electrode for electrical impedance tomography applications. Verification on a volunteer's breast gives an excellent agreement with the simulation for the defined bandwidth. Furthermore, as the first stage of the system's characterisation, pork fat is also used to demonstrate the possibility to enhance the transmission between the antennas within the high loss environment. Those results propose the feasibility of implementing a high‐frequency radar system for breast cancer detection.
Fault current limiting method based on virtual impedance for hybrid high‐voltage direct current with cascaded MMC inverters
Authors: Jiang Qin , Li Baohong , Liu Tianqi , Wang Peng
Published: January 2021

The hybrid high‐voltage direct current (HVDC) with cascaded multi‐infeed MMC inverters is proposed in recent years, and it will be put into reality in near future. But the commutation failure of the line‐commutated converter (LCC) inverter will make the whole HVDC system to be blocked because the DC fault current could reach beyond the safety region of the MMC inverter. To solve such problem, this letter proposes a novel fault current limiting method based on the LCC control strategy, namely, the virtual impedance method. Such method can limit the fault current effectively and need no extra devices, which can avoid the block of the whole HVDC system on one side, and save the cost of the construction on the other side. The theoretical analysis shows that the proposed method can improve the high‐frequency characteristic of the DC system and realise the fault current limitation effect. The simulations validate the analysis finally.
Fault diagnosis of power transistors in a power converter of SRM drive based on a state inverse solution
Authors: Liu Yongzhi , Wang Rongji
Published: January 2021

Switched reluctance motor drives are a common technology used in traction motor drives. Herein, an online method is proposed for the fault diagnosis of power transistors in the popular asymmetric half‐bridge power converter of the SRM drive. Based on the rearrangement of three current sensors, each phase current was first calculated by solving equations associated with their detected values and the drive signals of the transistors. The faults in the transistors were then preliminarily detected by monitoring the error between the calculated sum of currents and the sum of actual phase currents detected by a current sensor. Once a fault was identified, the actual states of all transistors of the power converter were solved for inversely using a mathematical model and the necessary rule for a trade‐off. Then, the faulty transistors and the fault types were identified by comparing the actual states with the drive signals. Compared with prevalent methods, the diagnostic range of the proposed scheme was wider, and its control modes and the number of motor phases were not limited. A higher accuracy than currently available methods was its prominent advantage. The effectiveness of the proposed solution was also validated on a three‐phase 6/4 SRM drive.
Ultrasensitive immunosensor for detecting CEA based on double amplified signal of graphene loaded CoFe2O4/Ag nanoparticles
Authors: Wang Xiao , Wu Mei , Zhao Chulei , Liao Xiaochen , Zhang Mengmeng , Mei Lisha , Qiao XiuWen , Hong Chenglin
Published: January 2021

Using Ag‐CoFe2O4‐GO nanocomposite as biosensor interface, a novel unlabelled electrochemical immunosensor was designed to detect tumour marker carcinoembryonic antigen. Here, Ag‐CoFe2O4‐GO was synthesized by one‐pot method as an immunological probe. They have the following advantages: (1) Silver nanoparticles have a strong redox capacity under applied voltage and good biocompatibility, so they can bind more antibodies; (2) GO has a large specific surface area, which can load more Ag NPs and CoFe2O4 nanoparticles, and has excellent conductivity; (3) CoFe2O4 is widely favoured by researchers due to its advantages such as low production cost and simple preparation process, The prepared Ag‐CoFe2O4‐GO nanocomposite can amplify the electrochemical signal; (4) The presence of GO can effectively prevent the agglomeration of Ag NPs nanoparticles and CoFe2O4 nanoparticles, promote the formation of electron transfer network, and contribute to the electron transfer of sensors. Under optimal condition, the current signal and the concentration of carcinoembryonic antigen were linear in the range of 1 pg mL < sp > −1 < /sp > ∼ 80 ng mL < sp > −1 < /sp , > and the detection limit was 0.3 pg mL < sp > −1 < /sp > (S/N = 3). Under certain conditions, the manufactured immunosensor has good reproducibility, selectivity and excellent stability. Thus it has certain clinical value for the detection of carcinoembryonic antigen.
Enhanced performance of mesoporous NiCo2S4 nanosheets fibre‐shaped electrode for supercapacitor
Authors: Qi Jiqiu , Wang Di , Zhang Zhiyi , Hu Rui , Sui Yanwei , He Yezeng , Meng Qingkun , Wei Fuxiang
Published: January 2021

Here, mesoporous NiCo2S4 nanosheet fibre‐shaped electrode was prepared using Ni–Co layered double hydroxide (LDH) grown on nickel wire as precursor. NiCo2S4 nanosheet electrode displayed excellent electrochemical properties with specific capacitance of 1974.55 mF/cm2 at 2 mA/cm2 and 86.2% capacitance retention after 5000 cycles, which were far higher than those of Ni‐Co LDH precursor. Our work provides new strategy to improve the performance of LDH used for supercapacitor.
Z‐source inverter topologies with switched Z‐impedance networks: A review
Authors: Subhani Nafis , Kannan Ramani , Mahmud Apel , Blaabjerg Frede
Published: January 2021

The Z‐source inverter is one of the most interesting power electronic converters. Over the past decades, research and development have been in high demand to meet the challenges for improving the converter performance with reduced weight and cost while having high efficiency along with high gain or boost factor. Since the inception, tons of resolutions, customizations, and improvements have appeared to achieve these performance goals. To overcome the most common drawback, i.e. the low boost factor of classical Z‐source inverters, the switched inductor/capacitor and switched boost Z‐source inverter topologies have become predominant in the recent epoch. Furthermore, the higher component voltage stress, discontinuous input current, and high inrush start‐up current issues have also been addressed and solved in various literature as part of this topical advancement. In this study, a comprehensive review of various switched impedance network‐based Z‐source inverter topologies has been accomplished for providing a quick report to researchers and engineers so that they can consider this as a one‐stop solution for selecting inverters from this group. The overall study covers the methodology, features, and relevant important results of the latest switched Z‐source inverter models in order to demonstrate the coordination between pitfalls and improvements.
A non‐isolated single‐input dual‐output boost DC–DC converter
Authors: Farhadi‐Kangarlu Mohammad , Moallemi Khiavi Abdolhamid , Neyshabouri Yousef
Published: January 2021

A new non‐isolated single‐input dual‐output boost DC–DC converter is introduced in this paper. The motivation of the work is that in various applications such as some multilevel converters, it is required to provide multiple dc sources that are not required to be isolated. In the proposed structure, the output ports of the converter can provide different values of power and still balance the output voltage. Even, if required, the output voltages can be set to different values. From practical point of view, the proposed topology uses minimum number of power‐electronic switches (two switches for two outputs) which have common ground making their drive circuit simple and easy to implement. The state‐space modelling of the proposed converter is presented, then, the model is used to design the passive elements. Moreover, the proposed converter is compared with the relevant converters. In order to verify the performance of the proposed DC–DC converter, a prototype of the converter has been implemented and the results are presented.
Decentralized stochastic programming for optimal vehicle‐to‐grid operation in smart grid with renewable generation
Authors: Wang Yue , Liang Hao , Dinavahi Venkata
Published: January 2021

This paper presents a decentralized stochastic programming operation scheme for a vehicle‐to‐grid system in a smart grid, which includes a series of equipment with random power generation and demands. For households with electric devices, renewable solar power generation, energy storage systems and electric vehicles, we consider utility operating expenses, including power loss and energy consumption cost as the objective function. For customers, we consider the cost of electricity, including battery degradation. To investigate the uncertainty of the devices, a bottom‐up approach is proposed to develop a random device usage model for analyzing customers' uncertain behaviour. Besides, a random renewable power generation model and an electric vehicle random driving model are implemented. The proposed approach is implemented with OpenMP to simulate the decentralized process on a multi‐core CPU while reducing the computational burden. A case study based on the IEEE 33‐bus distribution system with different scenarios is used to evaluate the performance of the proposed approach. The simulation results show that by introducing an optimal household operation schedule, the expense of distribution system utility company can be reduced in which both customers and operators can benefit from the optimization of the system schedules.
Impact of renewable energy sources on modelling of bidding strategy in a competitive electricity market using improved whale optimization algorithm
Authors: Sahoo Abhilipsa , Hota Prakash Kumar
Published: January 2021

In a competitive power market, generating utilities can be enhanced to achieve maximum profit by implementing a process of bidding strategy. Now‐a‐days renewable sources like solar and wind have become better alternatives significantly than other sources prior to power generation. These sources have extensive utilisation day‐by‐day in power sector and their impact in developing precise bidding strategies is getting more challenging aspect in the market. Since these renewable sources possess intermittent nature and undergo many uncertainties, the generating utilities encounter an unavoidable problem. Taking these aspects into consideration, attempts have been made using improved whale optimization algorithm to make the bidding strategy model for maximizing the power supplier's profit. Weibull and Beta distribution functions are used for modelling the stochastic characteristics of wind‐speed profile and solar‐irradiation, respectively. The proposed technique is tested and clarified with an IEEE‐30, IEEE‐57 and practical 75‐bus Indian system. The outcomes of this method were taken into comparison with other optimization techniques and found that it has an advantage upon other methods in solving bidding problems. Further, it is observed that the impact of renewable sources on bidding strategy reduces the market clearing price and the generation of thermal power while increases the total bidding power.
Enhanced modelling of doubly fed induction generator in load flow analysis of distribution systems
Authors: C.V.S. Anirudh , V Seshadri Sravan Kumar
Published: January 2021

This paper presents an accurate framework for incorporating the doubly fed induction generator based wind farms in load flow analysis of distribution systems. The proposed model for doubly fed induction generator is based on an accurate equivalent circuit and also takes into consideration the voltage dependent reactive power limits associated with the doubly fed induction generator. In addition, the developed approach is capable of handling a doubly fed induction generator operating in either maximum power point tracking or non‐maximum power point tracking modes. The proposed PQ model of doubly fed induction generator easily fits into the forward–backward technique that is typically employed for obtaining the load flow solution of distribution networks. Test results on 19‐bus and 133‐bus systems are reported to indicate the effectiveness of the proposed approach.
Sub‐Nyquist receiver using sampling frequency and instant offsets
Authors: Cheng Chi‐Hao , Dye Gregory , Pennington Jason
Published: January 2021

With rapid advance in analogue‐to‐digital converters, more analogue‐to‐digital converters in the market can cover multiple Nyquist zones. As a result, the implementation of a sub‐Nyquist receiver designed to cover a bandwidth wider than what is dictated by Nyquist theory has become more feasible than ever. This article presents a sub‐Nyquist receiver using both different sampling rates and an offset at sampling instant. Compared with other sub‐Nyquist receivers, the proposed design is straightforward to implement and can avoid issues conventional sub‐Nyquist receivers encounter at the presence of multiple signals.
ANFIS‐fuzzy logic based UPQC in interconnected microgrid distribution systems: Modeling, simulation and implementation
Authors: Renduchintala Udaya K. , Pang Chengzong , Tatikonda Krishna M. , Yang Lin
Published: January 2021

This study focuses on the improvement of the power quality in interconnected power distribution systems using connected microgrids. The power quality issues at the secondary distribution level are addressed using a unified power quality conditioner, which aids in controlling voltage imbalances and current harmonics. Further, a power control method, adaptive network‐based fuzzy inference system, is proposed as a global solution by installing independent compensating devices at the point of common coupling. The proposed strategy can improve the power quality in traditional installations because the proposed unified power quality conditioner method maximizes power utilization and improves the efficiency of the system. The microgrids integrate renewable energy sources, which generate green energy with low loss. Case studies, a prototype, and simulations via MATLAB/Simulink are used to validate the proposed method, and the results prove the enhancement in power quality control. The proposed control strategy had a response time of 0.3 s, reduced peak voltage distortions, and restored the voltage at the interconnecting point to a normal level. The total harmonic distortion of currents decreased from 21.13% to 14.74% when a PI technique was used to control the UPQC‐P, and the proposed adaptive network‐based fuzzy inference system‐based UPQC‐P reduced the harmonic content to 2.43% from 21.13%.
A novel path planning algorithm for mobile robot in dynamic environments using modified bat swarm optimization
Authors: Ajeil Fatin Hassan , Ibraheem Ibraheem Kasim , Humaidi Amjad J. , Khan Zeashan Hameed
Published: January 2021

This paper describes the path planning of an autonomous mobile robot using an advanced version of the swarm bat algorithm in a time‐varying situation. The foremost objective of this present contribution is to acquire the shortest path between the initial and end‐point avoiding dynamic obstacles. In this work, an adaptation of the frequency parameter of the standard bat algorithm to develop an improved version known as the modified frequency bat (MFB) algorithm is proposed. The modified frequency bat algorithm works in two steps, in the first step, the robot path is generated when there are no obstacles in the environment using the proposed method. As soon as an obstacle is detected near the robot, the second mode is initiated to avoid any obstacle. Extensive simulations are performed to validate the effectiveness of the proposed modified frequency bat algorithm by implementing it on standard benchmark functions and path planning problems and simultaneously matching its performance with the original bat algorithm. It has been concluded that the modified frequency bat algorithm shows superior performance as compared to the standard bat algorithm by drawing a shorter and collision‐free path for the mobile robot path‐planning problem.
Fast and robust motion averaging via angle constraints of multi‐view range scans
Authors: Zhang Xin , Zhang Yan , Qu Chengzhi , Tan Zhuangbin
Published: January 2021

The motion averaging problem arises when recovering the motions for a set of scans in three‐dimensional (3D) reconstruction. Motion averaging is taken as an optimisation problem, whose solution can be obtained via matrix decomposition in principal component analysis. The latest motion averaging methods utilize the Cauchy kernel function or overlap rate to construct the weighted matrix in the cost function, yielding weighted low‐rank sparse matrix decomposition solutions. Nevertheless, the over‐reliance on the initial value and high computational complexity remain two major problems. Here, we aim to improve the motion averaging performance via a fast and robust method based on the angle constraints of multiple scans. The additional term representing the angle constraint is added into the original cost function. By doing this, two benefits are facilitated: 1) the iteration times for the optimisation process are reduced; and 2) it effectively mitigates the over‐reliance on the initial value and thus caters for outliers and random noise of initial motions. Compared with state‐of‐the‐art motion averaging methods, it is indicated that the proposed method is more efficient and robust for numerical simulations of using both simulated motions and real 3D scanning data, given a large range of angle constraint values.
Outflows, envelopes, and disks as evolutionary indicators in Lupus young stellar objects
Authors: Vazzano M. M. , Fernández-López M. , Plunkett A. , de Gregorio-Monsalvo I. , Santamaría-Miranda A. , Takahashi S. , Lopez C.
Published: January 2021

Context.The Lupus star-forming complex includes some of the closest low-mass star-forming regions, and together they house objects that span evolutionary stages from prestellar to premain sequence.

Aims.By studying seven objects in the Lupus clouds from prestellar to protostellar stages, we aim to test if a coherence exists between commonly used evolutionary tracers.

Methods.We present Atacama Large Millimeter Array (ALMA) observations of the 1.3 mm continuum and molecular line emission that probe the dense gas and dust of cores (continuum, C18O, N2D+) and their associated molecular outflows (12CO). Our selection of sources in a common environment, with an identical observing strategy, allows for a consistent comparison across different evolutionary stages. We complement our study with continuum and line emission from the ALMA archive in different bands.

Results.The quality of the ALMA molecular data allows us to reveal the nature of the molecular outflows in the sample by studying their morphology and kinematics, through interferometric mosaics covering their full extent. The interferometric images in IRAS 15398-3359 appear to show that it drives a precessing episodic jet-driven outflow with at least four ejections separated by periods of time between 50 and 80 yr, while data in IRAS 16059-3857 show similarities with a wide-angle wind model also showing signs of being episodic. The outflow of J160115-41523 could be better explained with the wide-angle wind model as well, but new observations are needed to further explore its nature. We find that the most common evolutionary tracers in the literature are useful for broad evolutionary classifications, but they are not consistent with each other to provide enough granularity to disentangle a different evolutionary stage of sources that belong to the same Class (0, I, II, or III). The evolutionary classification revealed by our analysis coincides with those determined by previous studies for all of our sources except J160115-41523. Outflow properties used as protostellar age tracers, such as mass, momentum, energy, and opening angle, may suffer from differences in the nature of each outflow and, therefore, detailed observations are needed to refine evolutionary classifications. We found both AzTEC-lup1-2 and AzTEC-lup3-5 to be in the prestellar stage, with the possibility that the latter is a more evolved source. IRAS 15398-3359, IRAS 16059-3857, and J160115-41523, which have clearly detected outflows, are Class 0 sources, although, we are not able to determine which is younger and which is older. Finally Sz 102 and Merin 28 are the most evolved sources in our sample and show signs of having associated outflows, which are not as well traced by CO as for the younger sources.
The role of stochastic and smooth processes in regulating galaxy quenching
Authors: Kipper Rain , Tamm Antti , Tempel Elmo , de Propris Roberto , Ganeshaiah Veena Punyakoti
Published: January 2021

Context. Galaxies can be classified as passive ellipticals or star-forming discs. Ellipticals dominate at the high end of the mass range, and therefore there must be a mechanism responsible for the quenching of star-forming galaxies. This could either be due to the secular processes linked to the mass and star formation of galaxies or to external processes linked to the surrounding environment. However, the contribution from these smooth and stochastic processes to galaxy quenching has yet to be quantified.

Aims. In this paper, we analytically model the processes that govern galaxy evolution and quantify their contribution. The key advantage of our method is that we do not assume the strength of the contribution from any of these processes beforehand, but instead aim to find their efficiencies. We have specifically studied the effects of mass quenching, gas stripping, and mergers on galaxy quenching.

Methods. To achieve this, we first assumed a set of differential equations that describe the processes that shape galaxy evolution. We then modelled the parameters of these equations by maximising likelihood. These equations describe the evolution of galaxies individually, but the parameters of the equations are constrained by matching the extrapolated intermediate-redshift galaxies with the low-redshift galaxy population. In this study, we modelled the processes that change star formation and stellar mass in massive galaxies from the GAMA survey between z ≈ 0.4 and the present.

Results. We identified and quantified the contributions from mass quenching, gas stripping, and mergers to galaxy quenching. By modelling mass quenching, we found that quenching begins for galaxies above a mass of ≈1010.2 M⊙, but is dependent on the gas accretion rate before quenching. The quenching timescale is on average 1.2 Gyr and a closer look reveals support for the slow-then-rapid quenching scenario. The major merging rate of galaxies is about once per 10 Gyr, while the rate of ram pressure stripping is significantly higher. In galaxies with decreasing star formation, we show that star formation is lost to fast quenching mechanisms such as ram pressure stripping and is countered by mergers, at a rate of about 41% Gyr−1 and to mass quenching 49% Gyr−1. Therefore, slow quenching mechanisms have a greater influence on galaxies in group or cluster environments than fast quenching mechanisms.
Effects of erupting magnetic flux rope on running penumbral waves
Authors: Wang Wensi , Liu Rui
Published: January 2021

Context. It is widely known that solar flares have a substantial impact on the low atmosphere but the matter of how they affect sunspot waves and oscillations is generally unknown. In addition, there are ongoing debates on whether the flare-induced photospheric changes are due to the momentum conservation with coronal mass ejections or to magnetic reconnection.

Aims. To shed light on the so-called “back reaction” of solar eruptions, we investigated how running penumbral waves (RPWs) at one foot of an erupting magnetic flux rope (MFR) respond to the rope buildup and subsequent erosion.

Methods. We used UV/EUV images from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory (SDO) to explore the changing behaviors of RPWs in response to the MFR evolution, as well as 135-s vector magnetograms from the SDO Helioseismic and Magnetic Imager to analyze the changes in photospheric magnetic field during the eruption.

Results. During the rope buildup stage, the western foot of the rope, which is completely enclosed by a hooked ribbon, expands rapidly and consequently ends up overlapping a sunspot penumbra. This converts the original penumbral field into the rope field, which is associated with a transient increase in electric currents flowing through the ribbon-swept penumbral region. During the rope erosion stage, the rope foot shrinks as the eastern section of the hooked ribbon slowly sweeps the same penumbral region, where the rope field is converted into flare loops. This conversion induces mixed effects on the photospheric field inclination but heats up the low atmosphere at the footpoints of these flare loops to transition-region temperatures, therefore resulting in the post-eruption RPWs with an enhanced contrast in the 1600 Å passband and an extended bandwidth to low frequencies at 3–5 mHz, compared with the pre-eruption RPWs that peak at 6 mHz.

Conclusions. This observation clearly demonstrates that it is the magnetic reconnection in the corona that impacts the low atmosphere and leads to the changing behaviors of RPWs, which, in turn, offer a new window onto diagnosing flare reconnections.
Constraining millisecond pulsar geometry using time-aligned radio and gamma-ray pulse profile
Authors: Benli Onur , Pétri Jérôme , Mitra Dipanjan
Published: January 2021

Context. Since the launch of the Fermi Gamma-Ray Space Telescope, several hundred gamma-ray pulsars have been discovered, some being radio-loud and some radio-quiet with time-aligned radio and gamma-ray light curves. In the second Fermi Pulsar Catalogue, 117 new gamma-ray pulsars have been reported based on three years of data collected by the Large Area Telescope on the Fermi satellite, providing a wealth of information such as the peak separation Δ of the gamma-ray pulsations and the radio lag δ between the gamma-ray and radio pulses.

Aim. We selected several radio-loud millisecond gamma-ray pulsars with period P in the range 2–6 ms and showing a double peak in their gamma-ray profiles. We attempted to constrain the geometry of their magnetosphere, namely the magnetic axis and line-of-sight inclination angles for each of these systems.

Method. We applied a force-free dipole magnetosphere from the stellar surface up to the striped wind region – well outside the light cylinder – to fit the observed pulse profiles in gamma-rays, consistently with their phase alignment with the radio profile. In deciding whether a fitted curve is reasonable or not, we employed a least-square method to compare the observed gamma-ray intensity with that found from our model, emphasising the amplitude of the gamma-ray peaks, their separation, and the phase lag between radio and gamma-ray peaks.

Results. We obtained the best fits and reasonable parameters in agreement with observations for ten millisecond pulsars. Eventually, we constrained the geometry of each pulsar described by the magnetic inclination α and the light-of-sight inclination ζ. We found that both angles are larger than approximately 45°.
Dynamically reconfigurable high-efficiency terahertz metasurface holograms
Authors: Hu Mengyuan , Tian Zhen
Published: January 2021

A reflective, dynamically reconfigurable, high-efficiency metasurface holographic scheme is presented in this paper, which is realized by pumping thin gallium arsenide wafers with a structured femtosecond laser. When the terahertz (THz) passes through the gallium arsenide wafer (GaAs), the pattern carried by the pump light is converted into the complex permittivity of the light carrier density distribution on the gallium arsenide wafer, which modulates the wafer, thereby changing the transmittance of the THz wave. The wavefront of the THz beam is determined by changing the shape and direction of the projected resonator on the DMD by Pancharatnam-Berry (P-B) phase principle. The numerical simulation results show that different holograms can be obtained by dynamically switching the projection on the DMD, and the orthogonal conversion efficiency of circularly polarized light can reach 90%. The holographic scheme proposed in this paper is convenient and fast and may advance the real-time dynamic conversion and dynamic display of holograms.
Error estimates for a robust finite element method of two-term time-fractional diffusion-wave equation with nonsmooth data
Authors: Nong Lijuan , Chen An , Cao Jianxiong
Published: January 2021

In this paper, we consider a two-term time-fractional diffusion-wave equation which involves the fractional ordersα∈ (1, 2) andβ∈ (0, 1), respectively. By using piecewise linear Galerkin finite element method in space and convolution quadrature based on second-order backward difference method in time, we obtain a robust fully discrete scheme. Error estimates for semidiscrete and fully discrete schemes are established with respect to nonsmooth data. Numerical experiments for two-dimensional problems are provided to illustrate the efficiency of the method and conform the theoretical results.
Successful Replantation of Tamai Zone I Amputation with Delayed Vein Repair
Authors: Özkan Burak , Uysal Ahmet Çagri , Markal Ertas Nilgün
Published: January 2021

Die Rekonstruktion digitaler Venen ist eine der schwierigsten Phasen der Endgliedreplantation. Distal lokalisierte digitale Venen haben ein kleines Gefäßkaliber und kollabierte Lumina, so dass sie nur schwer zu identifizieren und zu versorgen sind. Digitale Venen sind gelegentlich auch in den ersten Minuten nach der arteriellen Anastomose nicht erkennbar. In dieser Situation kann der Patient einige Stunden nach der Revaskularisierung erneut in den Operationssaal gebracht werden, um die dann erweiterten Venen sekundär zu rekonstruieren. Die verzögerte Rekonstruktion digitaler Venen ist eine zuverlässige und alternative Methode zur Replantation ohne Venennaht. In diesem Bericht wird eine erfolgreiche Replantation mit verzögerter Rekonstruktion digitaler Venen in der Tamai Zone I vorgestellt.
Spinal Tuberculosis
Authors: Heyde Christoph Eckhard , Lübbert Christoph , Wendt Sebastian , Rodloff Arne , Völker Anna , von der Höh Nicolas H.
Published: January 2021

Tuberculosis is one of the most common infectious diseases worldwide. The
frequency in Germany is low, however, an increase has been observed in the past
few years. The incidence of extrapulmonary manifestation accounts for up to 10
to 20%. In 50% of these cases the spinal column is affected. Although literature
reveals worldwide experiences in the treatment, in Germany spinal tuberculosis
remains a rarity. Different pitfalls and specific characteristics regarding
diagnosis and therapy are to consider. Therefore, a presentation of these
specifics and their discussion based on the available literature will be
presented. The purpose is to achieve an increase in awareness regarding this, in
our latitudes, rare disease.
Facet-Sparing Decompression of Lumbar Spinal Stenosis: The Minimally Invasive Bilateral Crossover Approach
Authors: Klingler Jan Helge , Hubbe Ulrich , Scholz Christoph , Krüger Marie T.
Published: January 2021

Background and Study Objective One risk of established decompression techniques for lumbar spinal stenosis is the resection of facet joints, especially if they are steeply configured, promoting destabilization. Minimally invasive bilateral crossover decompression aims to preserve the facet joints and thus stability of the spine. The purpose of this study is to demonstrate the feasibility and early results of this technique.

Methods This retrospective case series includes 10 consecutive patients with lumbar stenosis and steep-angle (<35 degrees) facet joints who were treated with minimally invasive bilateral crossover decompression. Eleven segments were decompressed, most commonly L3/L4 (63.6%), followed by L1/L2 and L2/L3 (18.2% each). The effectiveness of surgical decompression was assessed by self-reporting questionnaires.

Results After a follow-up of 10.5 months, the Symptom Severity Scale and Physical Function Scale of the Swiss Spinal Stenosis Questionnaire improved by 0.9 (p < 0.05) and 0.7 points, respectively. The mean Oswestry Disability Index improved from 53.9 to 34.6 (p < 0.05). Local and radiating pain under strain showed statistically significant improvement on the Visual Analog Scale (8.9 vs. 5.0 and 8.4 vs. 4.6, respectively). Maximum walking distance increased from 190 to 1,029 m. Apart from one patient requiring surgical decompression of an adjacent segment, there were no reoperations, neurological deteriorations, or other complications.

Conclusion The results of this study indicate that minimally invasive bilateral crossover decompression is a promising technique for the treatment of spinal canal stenosis. With its design to spare facet joints, it can potentially reduce the risk of spinal instability, especially in patients with steep facet joints.
Awake Surgical Mitral Valve Repair after Transcatheter Aortic Valve Replacement
Authors: Hirofuji Aina , Kanda Hirotsugu , Kitani Yuya , Kamiya Hiroyuki
Published: January 2021

Transcatheter aortic valve replacement has become a popular choice for cases with severe aortic stenosis. However, when severe mitral regurgitation is comorbid in high-risk patients with severe aortic stenosis, therapeutic options must be weighed for each case. Here we present a very frail 88-year-old patient with severe aortic stenosis and severe mitral valve regurgitation who underwent a successful awake minimally invasive mitral valve repair after transcatheter aortic valve replacement.
Intradiskal Injection of Methylene Blue for Discogenic Back Pain: A Meta-Analysis of Randomized Controlled Trials
Authors: Deng Ming , Huang Hui , Ma Yong-gang , Zhou Yan , Chen Qing , Xie Ping
Published: January 2021

Introduction Intradiskal injection of methylene blue has some potential in alleviating discogenic back pain. This meta-analysis aims to explore the impact of intradiskal injection of methylene blue for discogenic back pain.

Methods Several databases such as PubMed, EMbase, Web of Science, EBSCO, and Cochrane Library databases have been searched through November 2019, and randomized controlled trials (RCTs) assessing the effect of intradiskal injection of methylene blue for discogenic back pain are included.

Results Three RCTs are included in the meta-analysis. Overall, compared with control group for discogenic back pain, intradiskal injection of methylene blue remarkably decreased pain scores at 3 months (mean difference [MD] = –0.71; 95% confidence interval [CI] = –0.96 to –0.46; p < 0.00001) and 6 months (MD = –13.92; 95% CI = –22.31 to –5.54; p = 001) and Oswestry Disability Index (ODI) at 4 to 6 weeks (MD = –10.39; 95% CI = –16.95 to –3.83; p = 0.002) and 3 months (MD = –3.66; 95% CI = –4.85 to –2.48; p < 0.00001), but demonstrated no obvious effect on ODI at 6 months (MD = –11.76; 95% CI = –33.33 to 9.80; p = 0.28).

Conclusions Intradiskal injection of methylene blue can substantially decrease pain scores and improve function for discogenic back pain.
Hemorrhagic Suprasellar Central Nervous System Embryonal Tumor in an Adult: Uncommon Features of an Extremely Rare Neoplasm
Authors: Piloni Martina , Gagliardi Filippo , Bailo Michele , Barzaghi Lina Raffaella , Callea Marcella , Terreni Mariarosa , Falini Andrea , Castellano Antonella , Mortini Pietro
Published: January 2021

Background Occurrences of suprasellar central nervous system (CNS) embryonal tumors in adults are extremely rare. Hemorrhagic onset is further uncommon, with only anecdotic cases reported in the literature. The authors describe the case of a 57-year-old man affected by a suprasellar CNS embryonal tumor, with hemorrhagic onset and a unique diffusion pattern along the optic pathways.

Material and Methods A 57-year-old man presenting with acute visual acuity worsening and left homonymous hemianopia was referred to our hospital. Neuroradiologic studies demonstrated an infiltrating, high-grade lesion involving the optic chiasm and right retrochiasmatic pathways with a hemorrhagic area in the ipsilateral pulvinar.

Results The patient underwent microsurgical biopsy. Pathologic assessment confirmed the diagnosis of CNS embryonal tumor, not otherwise specified (NOS) according to the 2016 World Health Organization (WHO) classification of CNS tumors. The patient was referred to a multimodal adjuvant treatment; he eventually died 4 months after surgery. Competent literature has been systematically reviewed in the light of the relevant changes made in the last version of the WHO classification.

Conclusion Embryonal tumors should be considered in the differential diagnosis for sellar and suprasellar space-occupying lesions, despite the rarity of the disease and the uncommon features at time of presentation. As per our knowledge, this is the first case ever described of hemorrhagic suprasellar embryonal tumor with a diffusion pattern along white matter fibers. Histogenesis, biomolecular and neuroradiologic features, and classification of embryonal tumors are an open field of research, with considerable implications for the definition of better diagnostic pitfalls and therapeutic regimens.
Ab initio interphase characteristics in HfO2 and ZrO2 and nucleation of the polar phase
Authors: Falkowski Max , Kersch Alfred
Published: January 2021

Recently, the crystallographic phases of HfO2 and ZrO2, including the polar phases, have been well characterized, and also the total and free energies have been calculated. However, less is known about the structure and energy of the crystalline coherent interface—also called the interphase. The formation of domain and phase boundaries is determined by interphase energies and properties, and their knowledge is indispensable to better understand the phase formation and phase stability. We have calculated the interphase energy for HfO2 and ZrO2 at T = 0 K for the relevant phase pairs with two methods, which are in good agreement. The method is applicable to any crystalline material with metastable phases. The values range in a few 100 mJ/m2, which is consistent with previous estimates from room temperature but too large for estimates from high-temperature processes. We propose a temperature dependence of interphase energy such that it becomes small close to the phase transition.
Earthworm activity and its coupling to soil hydrology: A deterministic analysis
Authors: Mangiarotti S. , Fu E. , Jouquet P. , Tran M. T. , Huc M. , Bottinelli N.
Published: January 2021

Considering in situ observations, chaos theory was taken as a basis to study the activity of anecic earthworms based on cast production from September 2016 to January 2018 in the Dong Cao watershed (Vietnam). To study this activity, the global modeling technique was used to obtain deterministic models of ordinary differential equations directly from observational time series. The obtained models show that the behavior of earthworms is chaotic; it is coupled to the dynamics of soil water content in a complex (integrative) way and can be interpreted as an habituation/sensitization process. However, this coupling is insufficient to explain the desynchronization of the cast production variations observed at different study sites. The retroaction of earthworm activity on soil is required to explain the spatiotemporal discrepancies.
When do short-range atomistic machine-learning models fall short?
Authors: Yue Shuwen , Muniz Maria Carolina , Calegari Andrade Marcos F. , Zhang Linfeng , Car Roberto , Panagiotopoulos Athanassios Z.
Published: January 2021

We explore the role of long-range interactions in atomistic machine-learning models by analyzing the effects on fitting accuracy, isolated cluster properties, and bulk thermodynamic properties. Such models have become increasingly popular in molecular simulations given their ability to learn highly complex and multi-dimensional interactions within a local environment; however, many of them fundamentally lack a description of explicit long-range interactions. In order to provide a well-defined benchmark system with precisely known pairwise interactions, we chose as the reference model a flexible version of the Extended Simple Point Charge (SPC/E) water model. Our analysis shows that while local representations are sufficient for predictions of the condensed liquid phase, the short-range nature of machine-learning models falls short in representing cluster and vapor phase properties. These findings provide an improved understanding of the role of long-range interactions in machine learning models and the regimes where they are necessary.
Anomalous dielectric response of nanoconfined water
Authors: Mondal Sayantan , Bagchi Biman
Published: January 2021

In order to develop a microscopic level understanding of the anomalous dielectric properties of nanoconfined water (NCW), we study and compare three different systems, namely, (i) NCW between parallel graphene sheets (NCW–GSs), (ii) NCW inside graphene covered nanosphere (NCW–Sph), and (iii) a collection of one- and two-dimensional constrained Ising spins with fixed orientations at the termini. We evaluate the dielectric constant and study the scaling of ε with size by using linear response theory and computer simulations. We find that the perpendicular component remains anomalously low at smaller inter-plate separations (d) over a relatively wide range of d. For NCW–Sph, we could evaluate the dielectric constant exactly and again find a low value and a slow convergence to the bulk. To obtain a measure of surface influence into the bulk, we introduce and calculate correlation lengths to find values of ∼9 nm for NCW–GS and ∼5 nm for NCW–Sph, which are surprisingly large, especially for water. We discover that the dipole moment autocorrelations exhibit an unexpected ultrafast decay. We observe the presence of a ubiquitous frequency of ∼1000 cm−1, associated only with the perpendicular component for NCW–GS. This (caging) frequency seems to play a pivotal role in controlling both static and dynamic dielectric responses in the perpendicular direction. It disappears with an increase in d in a manner that corroborates with the estimated correlation length. A similar observation is obtained for NCW–Sph. Interestingly, one- and two-dimensional Ising model systems that follow Glauber spin-flip dynamics reproduce the general characteristics.