bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic field resilient high kinetic inductance superconducting niobium nitride coplanar waveguide resonators
Authors: Yu Cécile Xinqing , Zihlmann Simon , Troncoso Fernández-Bada Gonzalo , Thomassin Jean-Luc , Gustavo Frédéric , Dumur Étienne , Maurand Romain
Published: February 2021

We characterize niobium nitride (NbN) λ/2 coplanar waveguide resonators, which were fabricated from a 10-nm-thick film on silicon dioxide grown by sputter deposition. For films grown at 180 °C, we report a superconducting critical temperature of 7.4 K associated with a normal square resistance of 1 kΩ, leading to a kinetic inductance of 192 pH/◻. We fabricated resonators with a characteristic impedance up to 4.1 kΩ and internal quality factors Qi>104 in the single photon regime at zero magnetic field. Moreover, in the many photon regime, the resonators present a high magnetic field resilience with Qi>104 in a 6 T in-plane magnetic field and in a 300 mT out-of-plane magnetic field. These findings make such resonators a compelling choice for circuit quantum electrodynamics experiments involving quantum systems with small electric dipole moments operated in finite magnetic fields.
Single pixel camera methodologies for spatially resolved acoustic spectroscopy
Authors: Patel Rikesh , Sharples Steve D. , Clark Matt , Somekh Mike G. , Li Wenqi
Published: February 2021

Spatially resolved acoustic spectroscopy (SRAS) is a laser ultrasound technique used to determine the crystallographic orientation (i.e., microstructure) of materials through the generation and measurement of surface acoustic wave velocity on a sample. Previous implementations have used a grating pattern imaged onto the surface to control the frequency of the generated wave in a single direction—grain orientation can be computed by acquiring wave velocities in different directions on the surface (gathered by physically rotating the grating pattern). This paper reports an advance to this methodology, inspired by single pixel cameras, using a coded grating pattern, created using a spatial light modulator, to excite surface acoustic waves in multiple directions simultaneously. This change to the optical arrangement can simplify the overall system alignment, remove mechanical complexities, and is well suited for point-by-point full orientation imaging, potentially allowing for faster orientation imaging using SRAS microscopy. Improvements to the robustness of measurement may be expected to extend the applicability of SRAS in the materials science field. To demonstrate this methodology, experiments were conducted on isotropic and anisotropic samples.
Enhancement of low-frequency spin-orbit-torque ferromagnetic resonance signals by frequency tuning observed in Pt/Py, Pt/Co, and Pt/Fe bilayers
Authors: Aoki Motomi , Shigematsu Ei , Matsushima Masayuki , Ohshima Ryo , Honda Syuta , Shinjo Teruya , Shiraishi Masashi , Ando Yuichiro
Published: February 2021

DC voltages via spin rectification effect (SRE), VDC, under microwave irradiation are investigated for three platinum (Pt)/ferromagnetic metal (FM) bilayer structures: Pt/Ni80Fe20, Pt/Co, and Pt/Fe. At the microwave frequency region lower than the resonant frequency, large VDC is obtained at zero DC magnetic field for all devices. In frequency dependence just around the resonant frequency, sharp rise and drop of magnitude in VDC are observed. These behaviors are well explained by the numerically calculated magnetic susceptibility. It is also found that the magnitude of VDC is strongly dependent on the slope of magnetoresistance spectrum. These findings lead to developments of sensitive detection technique for nano-scale magnetization switching.
The impact of solvent tanδ on the magnetic characteristics of nanostructured NiZn-ferrite film deposited by microwave-assisted solvothermal technique
Authors: Kahmei R. D. Ralandinliu , Arackal Sarath , Shivashankar S. A. , Bhat Navakanta , Sai Ranajit
Published: February 2021

Nanostructured Ni-Zn ferrite (NZF) thin films, deposited by a CMOS-compatible microwave-assisted solvothermal deposition (MAS-D) process, exhibit ‘far-from-equilibrium’ distribution of cations in the spinel structure, and thus, exciting magnetic properties. Solvents with different dielectric loss-tangents, such as ethanol (tanδ≈0.94), 1-decanol (tanδ≈0.1), and benzyl alcohol (tanδ≈0.67), were mixed in five judiciously-chosen proportions – ED35 (ethanol:1-decanol=3:5; tanδ≈0.51), ED33 (tanδ≈0.63), EB25 (tanδ≈0.66), EB35 (tanδ≈0.70), and EB33 (tanδ≈0.74) – to study the impact of effective tanδ on cation occupancy and the nature of magnetization in the resulting films. The maximum temperature attained during microwave irradiation (Tmax) and the heating rate (∆T/trise) increase as the effective tanδ of the solvent mixture increases, which in effect leads the Ni atoms to migrate towards equilibrium lattice sites. Unlike bulk NZF, where all Ni atoms occupy octahedral sites (B-sites), the films reported here exhibit just 28% of Ni atoms in B-sites at best when deposited from the precursor solution EB25. At room temperature all films are superparamagnetic, while the maximum moment (MS=100 emu/cc) is observed in the film with the highest % of Ni atoms in B-sites. Thermoremanent magnetization (TRM) of the samples is studied and compared. Very high effective anisotropy constants (Keff=140 kJ/m3), and two-orders-of magnitude-higher inter-particle dipole moment (Edipole≈8×10-20 J @300 K) are observed in samples prepared from benzyl alcohol rather than 1-decanol – signifying the potential for tailoring magnetic properties by the choice of solvents in the MAS-D process.
Harvesting forage fish can prevent fishing-induced population collapses of large piscivorous fish
Authors: Soudijn Floor H. , Daniël van Denderen P. , Heino Mikko , Dieckmann Ulf , de Roos André M.
Published: February 2021

Significance

In many marine ecosystems, fisheries target predatory fish, known as piscivores, as well as their prey fish, known as forage fish. It is generally thought that harvesting of forage fish negatively affects piscivore population abundance and resilience. Here, we show that, contrary to this widely held belief, piscivorous fish stocks exposed to high fishing mortality benefit from harvesting of their forage fish. On the other hand, piscivorous fish stocks exposed to low fishing mortality are reduced by harvesting of their forage fish. The beneficial effect occurs when the harvesting of forage fish releases density dependence in the forage-fish population. Our findings have implications for policy advice regarding the management of forage-fish fisheries and the protection of piscivorous fish stocks.
The conserved autoimmune-disease risk geneTMEM39Aregulates lysosome dynamics
Authors: Luo Shuo , Wang Xin , Bai Meirong , Jiang Wei , Zhang Zhe , Chen Yifan , Ma Dengke K.
Published: February 2021

Significance

Autoimmune diseases are characterized by overactivation of an organism’s immune system and subsequent tissue damage and pathogenesis. Although genome-wide association studies have identified genetic variations, such as single-nucleotide polymorphisms (SNPs), that are linked to autoimmunity, the exact function of the genes involved and molecular mechanisms underlying their contribution to autoimmunity remain not well understood. Here, we show that an evolutionarily conserved autoimmunity risk gene,TMEM39A, regulates lysosome dynamics through interacting and functioning with molecular motor dynein intermediate light chain. As lysosomes are implicated in various aspects of immune-system dysfunction, including abnormal cytokine secretion and antigen presentation, our study provides an important mechanistic insight suggesting how TMEM39A might contribute to autoimmunity like multiple sclerosis and lupus.
Characterization of the strain-rate–dependent mechanical response of single cell–cell junctions
Authors: Esfahani Amir Monemian , Rosenbohm Jordan , Safa Bahareh Tajvidi , Lavrik Nickolay V. , Minnick Grayson , Zhou Quan , Kong Fang , Jin Xiaowei , Kim Eunju , Liu Ying , Lu Yongfeng , Lim Jung Yul , Wahl James K. , Dao Ming , Huang Changjin , Yang Ruiguo
Published: February 2021

Significance

Cell–cell junctions are essential components in multicellular structures and often experience strains of different magnitudes and rates. However, their mechanical behavior is currently underexplored due to the lack of techniques to quantitatively characterize junctional stress–strain relationships. We developed a polymeric microstructure to strain the mutual junction of a single cell pair while simultaneously recording the junction stress and observed previously unseen strain-rate–dependent junction responses. We showed that cytoskeleton growth could relax the stress buildup and prevent junction failure at low strain rates, while high strain rates led to synchronized junction failures at remarkably large strains (over 200%). We expect this platform and our biophysical understanding to form the foundation for the rate-dependent mechanics of cell–cell junctions.
Temporal dissociation of neural activity underlying synesthetic and perceptual colors
Authors: Teichmann Lina , Grootswagers Tijl , Moerel Denise , Carlson Thomas A. , Rich Anina N.
Published: February 2021

Grapheme-color synesthetes experience color when seeing achromatic symbols. We examined whether similar neural mechanisms underlie color perception and synesthetic colors using magnetoencephalography. Classification models trained on neural activity from viewing colored stimuli could distinguish synesthetic color evoked by achromatic symbols after a delay of ∼100 ms. Our results provide an objective neural signature for synesthetic experience and temporal evidence consistent with higher-level processing in synesthesia.
Indefinite subjects in Mandarin Chinese
Authors: Nie Xiaowen , Liu Feng-hsi
Published: February 2021

Indefinite subjects in Mandarin Chinese are dis-preferred or restricted according to previous studies although they do exist in natural data. In this study we examine two issues: when they are used and why they are used. The first issue is best answered by looking at the information status of indefinite subjects. We adopt the framework of givenness and newness developed byPrince (1992)and revised by Birner’s (2004,2006). We find that although indefinite subjects are new most of the time, most of them also carry some old information; the given-before-new principle is satisfied. For the second issue, we examine topic continuity of indefinite subjects in discourse. We find that they perform a discourse function different from that of the post-verbal NPs in existential sentences. Most of the time their referents are non-persistent, and they are not discourse topics, unlike post-verbal NPs in existential sentences.
Language policy and linguistic landscape
Authors: Savski Kristof
Published: February 2021

Analysis of signage has traditionally represented a point of entry into examinations of language policy, with the
visibility of different languages seen to be potentially indicative of repression of multilingualism, of struggles between
different language regimes or of grass-roots resistance to top-down agendas. This paper argues for a more discursive approach to
the nexus between linguistic landscape and language policy in investigations of multilingual spaces. I present two case studies of
the interaction between language policy and linguistic landscape in the southern Thai city of Hat Yai, the first examining part of
the central commercial district and the second the cafeteria of the main university located in the city. The findings highlight
numerous points of interaction between language policy and public signage, though they also underline the complex and sometimes
tenuous nature of this relationship.
e-DriMe
Authors: Ortego-Antón María Teresa
Published: February 2021

Dried meats is an area that has not been widely studied from a terminological approach despite the growing need of Spanish companies to adapt data about their products into English to export their goods abroad. In this paper, we focus on the design and compilation of e-DriMe, a Spanish and English e-dictionary intended to assist to communicate effectively in the field of dried-meats. This e-dictionary is based on the principles of the Function Theory of Lexicography (Bergenholtz and Tarp 2002,2003) and lexical semantics for terminology (L’Homme 2020). Firstly, the methodology to compile the e-dictionary is described, which relies on the content of a virtual Spanish-English comparable corpus of dried meat product cards. In addition, term extraction and entry tailoring are explained. Finally, some entries are exemplified. To summarize, we propose a new resource, e-DriMe, that can be easily integrated into computerized writing aids and computer-assisted translation tools.
Corrigendum: Does time always slow down as gravity increases? (2020 Eur. J. Phys.
41 023001)
Authors: Okołów Andrzej
Published: February 2021

Here we correct two linguistic mistakes we have made repeatedly in [1].
Facile fabrication of binary wettability patterned microstructure for microfluidics
Authors: Tang Biao , Wei Miaoyang , Shao Wan , Barman Jitesh , Sun Hailing , Lu Longsheng , Groenewold Jan , Wang Yao , Zhou Guofu
Published: February 2021

Diverse wetting contrasts of binary wettability patterns in nature have inspired a versatile platform for microfluidics manipulation. To date, nevertheless, building a binary wettability patterned micro/nano structure with highly ordered configuration has inevitably brought wettability contamination challenges in interface control. Herein, this work studied a facile approach to fabricate permanent and contamination-free microstructure with high contrast wettability by means of adding a small amount of surfactant to the photoresist, rather than through any surface modification of the substrate. Accordingly, we focused on a systematic research of the wettability contamination prevention, binary wettability interfacial pattern control, and the dynamic electrowetting performance. The results demonstrated the proposed fabrication of binary wettability patterned microstructure without reactive-ion etching would be advantageous for contamination-free, permanent, simple, reliable and precise process, which could enable the microfluidic electrowetting display highly stable and controllable, thus it is expected to suit fields all the way from microfluidic-based fundamental studies to materials processing engineering and device applications.
Strain engineering of graphene nano-resonator
Authors: More S K , Naik A K
Published: February 2021

Nano-resonators are increasingly used to study fundamental phenomena in dynamical systems. Strain tuning of resonance frequency provides an additional control knob in experiments that use these devices. In this work, we present a simple technique to tune the strain in these nano-resonators by controllably deforming a small section of the silicon substrate. We fabricate the graphene nano-resonators on a thinned circular region on the Si/SiO2 substrate. This circular diaphragm can be easily deformed by creating a pressure difference across it. We achieve this using a simple printed circuit board and KF-flange assembly. With this setup, we can produce a strain change of 12 × 10−5 on the device, with 1 bar pressure difference. This strain is enough to observe a corresponding frequency shift of 9 MHz. The proposed method to produce strain in the nano-resonators is free from any fabrication constraints and can be utilized for a wide variety of nano-resonators.
Defect coupling behavior and flexural wave energy harvesting of phononic crystal beams with double defects in thermal environments
Authors: Geng Qian , Wang Tian , Wu Lei , Li Yueming
Published: February 2021

As an effective means to manipulate elastic wave energy, the defect mode of phononic crystals (PCs) has recently been employed to implement vibration energy harvesting by localizing waves within certain areas at defect frequencies. Prior research has indicated that the thermal environment affects the defect behavior and energy harvesting of single defects. However, the dynamic characteristics of multi-defect phononic crystals have not yet been discussed. This paper presents an investigation of the coupling behavior and energy harvesting of double defects in heated PC beams. The frequencies and mode shapes of defect modes are studied for different defect pairs within the first bandgap. Results indicate that the difference in the single-defect frequency between the two defects plays a dominant role in determining the intensity of the defect interaction which splits the defect modes. Meanwhile, the influence of the energy distribution around the defects on the coupling behavior becomes prominent when the two defects are quite close to each other. These two factors could cause degeneration of the defect modes. As an external factor, thermal load could enhance the defect coupling intensity, and may reactivate the degenerated defect modes. This effect would increase as the initial defect interaction gets stronger. For vibration energy harvesting, temperature rise may lead to a significant reduction in defect-based harvested energy, even though the number of defect-induced resonance peaks could be increased in the thermal environment. The thermosensitivity of harvesting performance varies greatly for different combinations of defects. Thermal effects should be considered in the design of defect-based harvesters.
Non–monotonic behaviour in the mean transverse energy of electrons emitted from a reflection–mode p-GaAs(Cs,O) photocathode during its QE degradation through oxygen exposure
Authors: Jones L B , Scheibler H E , Kosolobov S N , Terekhov A S , Militsyn B L , Noakes T C Q
Published: February 2021

We present a study on the evolution of both transverse and longitudinal energy distributions due to oxygen–induced quantum efficiency degradation in the electrons emitted from a reflection–mode p-GaAs(Cs,O)-photocathode over an effective electron affinity range of χ
*∼ −0.1 eV to χ
*∼ +0.3 eV under illumination wavelengths λ = 808, 635 and 532 nm. For λ = 635 and 532 nm, we found that the mean transverse energy of electrons emitted as the photocathode effective electron affinity increased has a non–monotonic character. Our proposed fitting model links the measured response to changes in the relative number of thermalised and non–thermalised electrons in the total emitted photocurrent.
Enhanced deep-ultraviolet sensing by an all-inorganic p-PZT/n-Ga2O3 thin-film heterojunction
Authors: Liu Zeng , Zhang Shaohui , Zhi Yusong , Li Shan , Yan Zuyong , Chu Xulong , Bian Ang , Li Peigang , Tang Weihua
Published: February 2021

In this work, an enhanced-performance deep-ultraviolet (DUV) photodetector based on a Ga2O3/lead zirconate titanate (Pb(Zr0.52Ti0.48)O3, PZT) p-n heterojunction is fabricated and characterized for the first time. Compared to a Ga2O3-based device, the heterojunction device achieved a lower dark current of 2.7

×

10−11 A, a higher photo- to dark-current ratio of 2

×

103, a higher responsivity of 5.5 mA W−1, a larger specific detectivity of 2.6

×

1011 Jones and a higher external quantum efficiency of 2.7% at −2 V under 254 nm UV light illumination with an intensity of 500 μW cm−2. The p-PZT/n-Ga2O3 was confirmed to be a potential candidate for the construction of DUV photodetectors with enhanced sensing performance.
Accurate 3D reconstruction of complex defects based on combined method of MFL and MFDs
Authors: Li Hengtao , Liu Xiucheng , Wu Bin , He Cunfu
Published: February 2021

The two-step strategy for 3D reconstruction of complex defects was updated by combining the magnetic field disturbance (MFD) with magnetic ﬂux leakage (MFL) measurement methods. Firstly, the plane-scanned MFD imaging was employed to achieve high-accuracy reconstruction of the opening outlines of complex defects. Secondly, the finite element simulation model of the defect with the recognized opening outline was established as the forward model for depth profile inversion with the particle swarm optimization algorithm. The performances of the conventional MFL-based and updated strategies were carefully compared through finite element simulation. The results proved that the updated method combining MFD signals with MFL signals had the better performance in accurate 3D reconstruction of complex defects than the conventional MFL-based inversion strategy, displaying smaller errors in opening outline, peak depth and the profile. Experimental results confirmed that the updated strategy could accurately reconstruct the 3D shape of 8-shaped defect and rectangular defect with rounded corners.
Optimally adding additional inertial sensors to an initial configuration of sensors to maximize the sensing accuracy
Authors: Sahu Nitesh , Babu Prabhu , Kumar Arun , Bahl Rajendar
Published: February 2021

In this paper, we solve the problem of optimally adding additional inertial sensors to any known initial configuration of inertial sensors. The initial known configuration may be the optimal configuration or any random configuration of sensors. In this problem, we do not change the initial configuration of sensors, instead we determine the optimal orientations of the sensors which are to be added. We have posed this problem as an optimization problem and proposed a novel method to solve this optimization problem. The proposed method is based on the majorization-minimization procedure. The proposed method has been implemented and tested via numerical simulations in MATLAB. The simulation results show that the proposed method converges to the optimal solution and hence determines the optimal orientations for the sensors which are added to any known configuration of the sensors.
A high sensitivity microwave glucose sensor
Authors: Shahri Atena A , Omidvar Amir H , Rehder Gustavo P , Serrano Ariana L C
Published: February 2021

A simple, sensitive, low-cost microwave sensor capable of conducting glucose concentration measurements has been developed without chemical bindings. The sensing device uses a microstrip transmission line to detect variation of the glucose component of the solutions placed in a cavity under it. The uniform and concentrated electric field distribution results in an accurate and sensitive measurement of the absorption frequency shift in the frequency response of the sensor. The sensor was fabricated on a FR4 substrate for low-cost purpose. The shift in the absorption frequency of the device was measured in the frequency range between 4.8 GHz and 5.7 GHz using solutions with different glucose concentrations in two ranges: (a) high concentration from 1000 mg dl−1 to 8000 mg dl−1 and (b) low concentration from 100 mg dl−1 to 300 mg dl−1. The experimental results showed a high sensitivity of 0.32 MHz (mg dl−1)−1 for the low concentrations in terms of absorption frequency.
Exploiting gold nanoparticles for diagnosis and cancer treatments
Authors: D’Acunto Mario , Cioni Patrizia , Gabellieri Edi , Presciuttini Gianluca
Published: February 2021

Gold nanoparticles (AuNPs) represent a relatively simple nanosystem to be synthesised and functionalized. AuNPs offer numerous advantages over different nanomaterials, primarily due to highly optimized protocols for their production with sizes in the range 1–150 nm and shapes, spherical, nanorods (AuNRs), nanocages, nanostars or nanoshells (AuNSs), just to name a few. AuNPs possess unique properties both from the optical and chemical point of view. AuNPs can absorb and scatter light with remarkable efficiency. Their outstanding interaction with light is due to the conduction electrons on the metal surface undergoing a collective oscillation when they are excited by light at specific wavelengths. This oscillation, known as a localized surface plasmon resonance, causes the absorption and scattering intensities of AuNPs to be significantly higher than identically sized non-plasmonic nanoparticles. In addition, AuNP absorption and scattering properties can be tuned by controlling the particle size, shape, and the local refractive index near the particle surface. By the chemical side, AuNPs offer the advantage of functionalization with therapeutic agents through covalent and ionic binding, which can be useful for biomedical applications, with particular emphasis on cancer treatments. Functionalized AuNPs exhibit good biocompatibility and controllable distribution patterns when delivered in cells and tissues, which make them particularly fine candidates for the basis of innovative therapies. Currently, major available AuNP-based cancer therapeutic approaches are the photothermal therapy (PTT) or photodynamic therapy (PDT). PTT and PDT rely upon irradiation of surface plasmon resonant AuNPs (previously delivered in cancer cells) by light, in particular, in the near-infrared range. Under irradiation, AuNPs surface electrons are excited and resonate intensely, and fast conversion of light into heat takes place in about 1 ps. The cancer cells are destroyed by the induced hyperthermia, i.e. the condition under which cells are subject to temperature in the range of 41 °C–47 °C for tens of minutes. The review is focused on the description of the optical and thermal properties of AuNPs that underlie their continuous and progressive exploitation for diagnosis and cancer therapy.
Enhanced interfacial reaction of silicon carbide fillers onto the metal substrate in carbon nanotube paste for reliable field electron emitters
Authors: Go Eunsol , Kim Jae-Woo , Lee Jeong-Woong , Ahn Yujung , Jeong Jin-Woo , Kang Jun-Tae , Park Sora , Yun Ki Nam , Kim Seong Jun , Kim Sunghee , Yeon Ji-Hwan , Song Yoon-Ho
Published: February 2021

Adhesion of carbon nanotube (CNT) onto a cathode substrate is very crucial for field electron emitters that are operating under high electric fields. As a supporting precursor of CNT field emitters, we adopted silicon carbide (SiC) nano-particle fillers with Ni particles and then enhanced interfacial reactions onto Kovar-alloy substrates through the optimized wet pulverization process of SiC aggregates for reliable field electron emitters. As-purchased SiC aggregates were efficiently pulverized from 20 to less than 1 micro-meter in a median value (D50). CNT pastes for field emitters were distinctively formulated by a mixing process of the pulverized SiC aggregates and pre-dispersed CNTs. X-ray photoelectron spectroscopy studies showed that the optimally pulverized SiC-CNT paste-emitter had a stronger Si 2p3/2 signal in the Ni2Si phase than the as-purchased one. The Si 2p3/2 signal would represent interfacial reaction of the SiC nano-particle onto Ni from the CNT paste and the Kovar substrate, forming the supporting layer for CNT emitters. The optimal paste-emitter even in a vacuum-sealed tube exhibited a highly reliable field emission current with a high current density of 100 mA cm−2 for over 50 h along with good reproducibility. The enhanced interfacial reaction of SiC filler onto the metal substrates could lead to highly reliable field electron emitters for vacuum electronic devices.
A remote-controlled detector system with Geiger–Müller counter
Authors: Le Anh Duc , Nguyen Quoc B , Tran Ngoc Chat , Nguyen Ngoc Hung
Published: February 2021

In Vietnam, nuclear physics is a fundamental part of the national curriculum for physics. However, due to a lack of experimental apparatus (detectors, radioactive sources, etc) at most of the schools, the majority of students do not have opportunities to experience the phenomena behind the concepts. Moreover, safety is another major concern when conducting experiments on radioactive materials. We have developed a system of remote-controlled detector which allows students and teachers to conduct radioactive experiments safely. The system is assembled from many accessible components with reasonable prices such as Geiger–Müller counter, Arduino board, distance sensor, Wi-Fi transceiver receiver model board and stepper motor, etc. These components are widely available in the market.
Influence of segmentation accuracy in structural MR head scans on electric field computation for TMS and tES
Authors: Rashed Essam A , Gomez-Tames Jose , Hirata Akimasa
Published: February 2021

In several diagnosis and therapy procedures based on electrostimulation effect, the internal physical quantity related to the stimulation is the induced electric field. To estimate the induced electric field in an individual human model, the segmentation of anatomical imaging, such as magnetic resonance image (MRI) scans, of the corresponding body parts into tissues is required. Then, electrical properties associated with different annotated tissues are assigned to the digital model to generate a volume conductor. However, the segmentation of different tissues is a tedious task with several associated challenges specially with tissues appear in limited regions and/or low-contrast in anatomical images. An open question is how segmentation accuracy of different tissues would influence the distribution of the induced electric field. In this study, we applied parametric segmentation of different tissues to exploit the segmentation of available MRI to generate different quality of head models using deep learning neural network architecture, named ForkNet. Then, the induced electric field are compared to assess the effect of model segmentation variations. Computational results indicate that the influence of segmentation error is tissue-dependent. In brain, sensitivity to segmentation accuracy is relatively high in cerebrospinal fluid (CSF), moderate in gray matter (GM) and low in white matter for transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (tES). A CSF segmentation accuracy reduction of 10% in terms of Dice coefficient (DC) lead to decrease up to 4% in normalized induced electric field in both applications. However, a GM segmentation accuracy reduction of 5.6% DC leads to increase of normalized induced electric field up to 6%. Opposite trend of electric field variation was found between CSF and GM for both TMS and tES. The finding obtained here would be useful to quantify potential uncertainty of computational results.
Diagnostics of laser-produced Mg plasma through a detailed collisional radiative model with reliable electron impact fine structure excitation cross-sections and self-absorption intensity correction
Authors: Baghel S S , Gupta S , Gangwar R K , Srivastava R
Published: February 2021

A detailed fine-structure resolved collisional radiative model is developed to investigate the laser-produced Mg plasma. The dominant processes linked with the electron impact excitation and de-excitation have been considered explicitly in a very reliable and consistent manner in the present model. The required electron impact excitation cross-sections of Mg for the large number of transitions from the ground state 3s2 (J = 0) to the 3s3p, 3s4s, 3s3d, 3s4p, 3s5s, 3s4d, 3s5p, 3s6s, 3s5d, and 3s6p excited states and from 3s3p manifolds to the other fine-structure levels of 3s4s, 3s3d, 3s5s, 3s4d, 3s6s, and 3s5d configurations are obtained using the fully relativistic distorted wave approach. To ensure the accuracy of our calculations, where available, the oscillator strengths and cross-sections are compared with previous measurements and other calculations. Further, plasma diagnostics are carried out by coupling the present collisional radiative model with the laser-induced breakdown spectroscopy measurements reported by Delserieys et al (2009 J. Appl. Phys., 106, 083304). Five measured intense emission lines of Mg viz 383.3, 470.3, 517.8, 552.8, and 571.1 nm are used and corrected through the self-absorption to extract the plasma parameters i.e. electron temperature and electron density. The obtained plasma parameters at different delay times ranging from 100–700 ns are compared with the results of Delserieys et al (2009 J. Appl. Phys., 106, 083304) that were estimated using the Thomson scattering and Boltzmann plot approaches.
Enhancing the performance of photodetectors based on ZnO nanorods decorated with Ag nanoparticles
Authors: Dinh Tan Muon , Huynh Hung Quang , Mai Thi My Nhung , Truong Hong Sang , Luong Hoai Nhan , Nguyen Ngoc Phuong , Tran Cong Khanh , Phan Bach Thang , Dang Vinh Quang
Published: February 2021

Zinc oxide nanorods (ZnO NRs) were modified by decorating with silver (Ag) nanoparticles to enhance visible absorption. The morphology, structure and optical properties of the modified ZnO NRs were investigated by scanning electron microscopy, x-ray diffraction and UV–vis absorption spectroscopy. Photodetectors (PDs) based on the modified ZnO NRs successfully detected visible radiation. The result showed high performance of the visible sensor (λ = 400 nm) with a maximum responsivity of 46 mA W−1. The photoconductive gain of Ag/ZnO NR-based PDs was 5.8 times higher than that of pure ZnO NR ones. With their enhanced visible absorption, the multi-modified ZnO NRs are suitable for practical applications, especially in optoelectronic devices operating in the visible region.
Stability model of bulk HTS field pole of a synchronous rotating machine under load conditions
Authors: Watasaki Masahiro , Izumi Mitsuru , Miki Motohiro , Bocquel Clement , Shaanika Erasmus , Yamaguchi Kota , Ida Tetsuya , Englebretson Steven , Chin Robert , Morita Mitsuru , Teshima Hidekazu
Published: February 2021

High-temperature superconducting (HTS) bulks act as magnets with trapped magnetic flux and potentially exhibit high magnetic field performance, superior to that of permanent magnets. In the fourth industrial revolution, HTS magnets could potentially facilitate the development of highly efficient and lightweight motors and generators for propulsion. To evaluate and verify the durability of HTS rotating machines, we developed a radial-gap-type rotating machine whose field-pole modules comprised HTS bulks. We examined the stability of the trapped magnetic flux of the field poles during the machine’s operation. The rotating machine was operated with different loads, and the magnetic field associated with the trapped flux of the HTS bulks was analyzed. The analysis was performed for different loads and revolution speeds, and the long-term operation for a constant load was investigated. The trapped flux of the bulk field poles and the output power were observed to be almost constant for over 360 h, and the HTS bulk magnet’s surface temperature hardly changed below 40 K during the machine’s operation. Furthermore, the magnetic flux decay determined from magnetic flux measurements before and after a load test was less than 1%. An analysis of the magnetic field distribution around the HTS bulk revealed that the transverse magnetic flux flowed through the magnetic guide of the rotor core. These results indicate the potential synchronous machine application of the high trapped magnetic flux of the field-pole modules accumulated by the appropriate positioning the HTS bulks three-dimensionally.
A nonlinear interaction between SU(1,1) quantum system and a three-level atom in different configurations with damping term
Authors: Obada A-S F , Ahmed M M A , Abu-Shady M , Khalil E M , Mohamed A-B A , Habeba H F
Published: February 2021

The effect of nonlinear medium and phase damping is investigated on an atom of three levels in different forms interacting with the SU(1,1) Lie algebra. The SU(1,1) system starts the interaction from the Perelomov coherent state, while the atom starts the interaction from excited-most state. The time dependent wave function is calculated by using the Schrödinger equation. The density matrix is obtained. The influences of damping, nonlinearity (Kerr-like medium), Perelomov coherent parameter and the Bargmann index on some non-classical properties, such as: revivals-collapses phenomenon, entanglement and atomic variables squeezing, are investigated.
Tunable erbium doped fiber laser based on a spherical micro-ball lens as a Fabry–Perot interference filter
Authors: Bender-Pérez C E , Castillo-Guzmán A A , Alvarez-Tamayo R I
Published: February 2021

The tunable wavelength emission of an erbium doped fiber laser using a Fabry–Perot interference filter based on a fiber micro-ball lens (MBL) with a spherical shape is experimentally demonstrated. The filter is formed at the tip of a single-mode fiber by controlled electric arc discharge. The filter consists of a fiber MBL with a radius of 152.7 µm and a flat-convex mirror. A tunable single laser emission range of 1556.85–1569.72 nm is obtained when the mirror moves perpendicular to the fiber. Dual-wavelength laser emission with a separation of ∼12.9 nm corresponding to the free spectral range of interference modulation is obtained within the single laser wavelength tuning limits. The laser line exhibits full width at maximum half of 0.1 nm. The stability of the laser emission is also discussed. The use of a reliable tunable spectral filter for dual-wavelength emission and single tuning is demonstrated in the fiber laser’s design. The proposed spectral filter configuration can be useful in different research areas, such as the coherent development of light sources, optical communications, and optical instrumentation.
Observation of strong mode coupling in multimode step index silica optical fibers with fluorinated thermoplastic polymer cladding
Authors: Savović S , Djordjevich A
Published: February 2021

Using the power flow equation, the state of mode coupling in step index multimode silica optical fiber with fluorinated thermoplastic polymer cladding is investigated in this work. Coupling coefficient is determined by employing our previously reported calculation method. The silica optical fiber with fluorinated thermoplastic polymer cladding shows much stronger mode coupling than the all plastic-clad silica fibers investigated in earlier works. Consequently, it takes much shorter fiber length for the equilibrium mode distribution or steady state distribution to develop (faster launch beam narrowing), which is of great interest in employing silica optical fiber with fluorinated thermoplastic polymer as a part of telecommunication, medical and sensory system.
Improvement of the short-term stability of atomic fountain clock with state preparation by two-laser optical pumping*
Authors: Han Lei , Fang Fang , Chen Wei-Liang , Liu Kun , Dai Shao-Yang , Zuo Ya-Ni , Li Tian-Chu
Published: February 2021

To improve the signal to noise ratio (SNR) and the short-term stability of cesium atomic fountain clocks, the work of two-laser optical pumping is presented theoretically and experimentally. The short-term stability of the NIM6 fountain clock has been improved by preparing more cold atoms in the | F = 4, mF
= 0〉 clock state with a shortened cycle time. Two π-polarized laser beams overlapped in the horizontal plane have been applied after launching, one is resonant with | F = 4〉 → | F′ = 4〉 transition and the other is resonant with | F = 3〉 → | F′ = 4〉 transition. With optical pumping, the population accumulated in the | mF
= 0〉 clock state is improved from 11% to 63%, and the detection signal is increased by a factor of 4.2, the SNR of the clock transition probability and the short-term stability are also improved accordingly.
Effect of Mo doping on phase change performance of Sb2Te3
*
Authors: Liu Wan-Liang , Chen Ying , Li Tao , Song Zhi-Tang , Wu Liang-Cai
Published: February 2021

Mo, as a dopant, is doped into SbTe to improve its thermal stability. It is shown in this paper that the Mo-doped Sb2Te3 (Mo0.26Sb2Te3, MST) material possesses phase change memory (PCM) applications. MST has better thermal stability than Sb2Te3(ST) and will crystallize only when the annealing temperature is higher than 250 °C. With the good thermal stability, MST-based PCM cells have a fast crystallization time of 6 ns. Furthermore, endurance up to 4 × 105 cycles with a resistance ratio of more than one order of magnitude makes MST a promising candidate for PCM applications.
Effects of initial velocity on the sinking of ilmenite-bearing cumulates in the early lunar mantle: Insight from the theory of Rayleigh-Taylor instability
Authors: Yu Shuo-Ran , Zhang Xiao-Ping
Published: February 2021

The early lunar mantle overturn, associated with the sinking of the dense ilmenite-bearing cumulate (IBC) crystallized at the shallow lunar mantle, provides satisfactory explanations for the origination of high-Ti basalt, the abnormally strong magnetic field between ∼ 3.9 and ∼ 3.6 Ga and the low-viscosity zone in the deep lunar mantle, but still poses a debate regarding the initial state of IBC in the early lunar mantle. If the sinking of IBC initiated before the end of lunar magma ocean crystallization, the solidified IBC can acquire a greater thickness and a higher initial velocity at the IBC-mantle boundary. The variation of initial velocity can affect the strain rate of IBC and, correspondingly, the dislocation creep components at the shallow lunar mantle. In this work, we analyze the effects of initial velocity on the dynamics of early lunar mantle by using the theory of Rayleigh-Taylor instability. To couple the effects of diffusion creep and dislocation creep for all major minerals in the lunar mantle, we exploit an improved Minimized Power Geometric (IMPG) model and isostress mixing model to characterize the upper limit and lower limit for the viscosity of the lunar mantle comprising four major minerals, i.e. olivine, orthopyroxene, clinopyroxene and ilmenite. The modeling results suggest that a high initial velocity, in any case, can shorten the onset time, tending to promote the early lunar mantle overturn even in a rheologically-strong lunar mantle. The effect of initial velocity on the overturn wavelength shows a strong dependence on the rheological mixing model. For the isostress mixing model, the increase of initial velocity tends to elongate the overturn wavelength. For the IMPG mixing model, the overturn wavelength is insensitive to the variation of initial velocity. As the actual lunar mantle rheology sandwiches between the rheologies predicted by isostress mixing model and IMPG model, it can be anticipated that the increase of initial velocity tends to elongate the overturn wavelength. In consideration of the importance of the initial velocity on the dynamics of early lunar mantle, future investigations should focus on the dynamics of the solid IBC in the solidifying lunar magma ocean.
Effects of dynamo magnetic fields on observational properties of accreting millisecond X-ray pulsars
Authors: Belay Zeleke Dugasa , Belay Tessema Solomon , Humne Negu Seblu
Published: February 2021

In this paper, we have investigated accreting millisecond X-ray pulsars, which are rapidly rotating neutron stars in low-mass X-ray binaries. These systems exhibit coherent X-ray pulsations that arise when the accretion flow is magnetically channeled to the stellar surface. Here, we have developed the fundamental equations for an accretion disk around accreting millisecond X-ray pulsars in the presence of a dynamo generated magnetic field in the inner part of the disk. We have also formulated the numerical method for the structure equations in the inner region of the disk and the highest accretion rate is enough to form the inner region of the disk, which is overpowered by radiation pressure and electron scattering. Finally, we have examined our results with the effects of dynamo magnetic fields on accreting millisecond X-ray pulsars.
Decoding and interpreting cortical signals with a compact convolutional neural network
Authors: Petrosyan Artur , Sinkin Mikhail , Lebedev Mikhail , Ossadtchi Alexei
Published: February 2021

Objective. Brain–computer interfaces (BCIs) decode information from neural activity and send it to external devices. The use of Deep Learning approaches for decoding allows for automatic feature engineering within the specific decoding task. Physiologically plausible interpretation of the network parameters ensures the robustness of the learned decision rules and opens the exciting opportunity for automatic knowledge discovery. Approach. We describe a compact convolutional network-based architecture for adaptive decoding of electrocorticographic (ECoG) data into finger kinematics. We also propose a novel theoretically justified approach to interpreting the spatial and temporal weights in the architectures that combine adaptation in both space and time. The obtained spatial and frequency patterns characterizing the neuronal populations pivotal to the specific decoding task can then be interpreted by fitting appropriate spatial and dynamical models. Main results. We first tested our solution using realistic Monte-Carlo simulations. Then, when applied to the ECoG data from Berlin BCI competition IV dataset, our architecture performed comparably to the competition winners without requiring explicit feature engineering. Using the proposed approach to the network weights interpretation we could unravel the spatial and the spectral patterns of the neuronal processes underlying the successful decoding of finger kinematics from an ECoG dataset. Finally we have also applied the entire pipeline to the analysis of a 32-channel EEG motor-imagery dataset and observed physiologically plausible patterns specific to the task. Significance. We described a compact and interpretable CNN architecture derived from the basic principles and encompassing the knowledge in the field of neural electrophysiology. For the first time in the context of such multibranch architectures with factorized spatial and temporal processing we presented theoretically justified weights interpretation rules. We verified our recipes using simulations and real data and demonstrated that the proposed solution offers a good decoder and a tool for investigating motor control neural mechanisms.
Did a skillful prediction of near-surface temperatures help or hinder forecasting of the 2012 US drought?
Authors: Kam Jonghun , Kim Sungyoon , Roundy Joshua K
Published: February 2021

This study aims to understand the role of near-surface temperatures in predicting US climatic extremes using the North American Multi-Model Ensemble (NMME) system. Here, the forecasting skill was measured by anomaly correlation coefficient (ACC) between the observed and forecasted precipitation (PREC)/2-meter air temperature (T2m) anomalies over the contiguous United States (CONUS) during 1982–2012. The strength of the T2m–PREC coupling was measured by ACC between observed PREC and T2m or forecasted PREC and T2m over the CONUS. We also assessed the NMME forecasting skill for the summers of 2004 (spatial anomaly correlation between PREC and T2m: 0.05), 2011 (−0.65), and 2012 (−0.60) when the T2m–PREC coupling was weaker or stronger than the 1982–2012 climatology (ACC: −0.34). We found that most of the NMME models show the bias of stronger T2m–PREC coupling than the observed coupling over 1982–2012, indicating that they failed to reproduce the interannual variability of T2m–PREC coupling. Some NMME models with skillful prediction for T2m show the skillful prediction of the precipitation anomalies and US droughts in 2011 and 2012 via strong T2m–PREC coupling despite the fact that the forecasting skill is year-dependent and model-dependent. Most of the NMME models show the limited seasonal forecasting skill of the PREC surplus from active Atlantic tropical cyclones in the summer of 2004 and thus fail to reproduce weak T2m–PREC coupling. Lastly, we explored how the role of sea surface temperatures in predicting T2m and PREC. The findings of this study suggest a need for the selective use of the current NMME seasonal forecasts for US droughts and pluvials.