bluuebunny/crossref_metadata_2025 huggingface dataset:
SDN‐enabled Cognitive Radio Network Architecture
Authors: Cicioğlu Murtaza , Cicioğlu Seda , Çalhan Ali
Published: May 2020

In this study, a new network architecture based on the software‐defined networking (SDN) approach is proposed for cognitive radio networks (CRNs). The proposed network architecture [software‐defined cognitive radio (SDCR)] assumes the responsibilities of network resource management for CRNs and provides a dynamic spectrum management mechanism with an SDN controller. In this way, the dependency of network users on base stations is reduced in dynamic cognitive radio environments, and network performance is improved by delegating some of the management responsibilities to the controller. The performance analysis of the SDCR is carried out through the RIVERBED MODELER simulation software. End‐to‐end delays and packet loss rates for the primary network are investigated by selecting different offered loads for secondary users. In addition, for the equal and different packet sizes, primary network and SDCR throughput are examined and network performance is improved by using channel bonding technique. The results indicate that the SDCR outperforms the traditional CRN architecture, in terms of the throughput, and the proposed architecture can provide effective performance. Bit error rate parameter is investigated in the study and the energy consumption parameter of the SDCR is also compared with the cognitive radio wireless network.
Generalised expression for the symbol error floor of M‐ary phase shift keying in the presence of phase noise, I/Q imbalance and DC‐offset
Authors: Jafari Hamid , Miar‐Naimi Hossein , Kazemitabar Javad
Published: May 2020

This study, for the first time, presents an exact expression for the symbol error floor (SEF) of M‐ary phase shift keying in the presence of phase noise, in‐phase/quadrature (I/Q) gain and phase imbalances, and DC‐offsets altogether. Accurate calculation of symbol error probability, and also the SEF, in the presence of transmitter and receiver impairments is usually a cumbersome task. In this study, the symbol decision boundaries are moved from the demodulator output to the demodulator input as a means to simplify the SEF calculation. In other words, the effect of the receiver I/Q imbalance and DC‐offset is applied on the symbol decision boundaries. Using the decision boundaries at the demodulator input facilitates the exact SEF calculation. The proposed exact expression consists of single integrals. These integrals can be accurately approximated by Gaussian one‐dimensional Q‐functions assuming a Gaussian distribution for the phase noise. Computer simulations with Gaussian phase noise validate the exactness of the proposed analysis.
Super‐resolution image reconstruction using molecular docking
Authors: Nayak Rajashree , Patra Dipti , Balabantaray Bunil Ku
Published: May 2020

Molecular‐docking is an essential tool in the drug designing process, where a small molecule ligand (drug) binds with disease‐causing protein molecule to prevent its further activity. Docking process helps in predicting the most appropriate configuration and the optimal interaction energy between the interacting molecules (ligand and protein) to form a stable complex. Based on this idea, a new learning‐based single image super‐resolution reconstruction (LSI‐SRR) method is proposed here. Estimation of a high resolution (HR) patch is achieved by optimising the interaction energy between the input low resolution patch and its corresponding candidate patches appropriately chosen from the training image dataset via Genetic algorithm. Structured‐spatiogram based measure; a new and competent similarity criterion is proposed to select potentially efficient training images which encompass better statistical and structural co‐relation with the input image. The proposed method is tested on synthetic and real‐time images at different magnification factors. Performance analysis of the proposed work is compared with some of the representative state‐of‐the‐art LSI‐SRR methods. Experimental results demonstrate that the proposed method produces HR images with enhanced image details, minimal artefacts and most importantly enables an efficient trade‐off between the image qualities to speed than the competing methods.
Evaluation of dielectric strength of SiR/TiO2 composites using feed‐forward neural network
Authors: Qenawy Shaymaa A. , Nasrat Loai S. , Ismail Hanafy M. , Asaad Jeannette N.
Published: May 2020

Among the recently insulating materials broadly utilized in high voltage outdoor insulation, silicone rubber (SiR) has gotten the foremost consideration. Actually, SiR is becoming an efficient countermeasure to insulator contamination issues. To enhance different properties of polymeric materials, micro‐ and nanofillers have been used for dielectric applications. In this study, micron‐sized titanium dioxide (TiO2) and nano‐sized TiO2 fillers were added to the SiR matrix to improve electrical and mechanical properties. Dielectric strength, tensile strength, and elongation at break tests were monitored. Also, a scanning electron microscope was carried out. The samples were prepared by mixing micro‐TiO2 into SiR with the content of 0, 10, 20, 30, and 40 wt% and also mixing nano‐TiO2 into SiR with the content of 0, 1, 3, 5, and 7 wt%. A feed‐forward neural network technique was used to estimate the dielectric strength in different conditions and different percentages of fillers. Adding nano TiO2 filler enhances the electrical and mechanical properties of SiR composites. SiR with 5 wt% nano TiO2 showed the best improvement in electrical and mechanical properties.
Learning‐based load control to support resilient networked microgrid operations
Authors: Radhakrishnan Nikitha , Schneider Kevin P. , Tuffner Francis K. , Du Wei , Bhattarai Bishnu P.
Published: May 2020

Networked and interconnected microgrids can improve resilience of critical end‐use loads during extreme events. However, the frequency deviations in microgrids during transient events are significantly larger than those typically seen in bulk transmission systems. The larger frequency deviations can cause a loss of inverter‐connected assets, resulting in a loss of power to critical end‐use loads. Grid Friendly ApplianceTM (GFA) controllers can mitigate the transient event effects by engaging end‐use loads. This paper presents a method to select set‐points for end‐use loads equipped with GFA controllers, while minimizing the interruptions to end‐use customers. An online (i.e. real‐time), device‐level algorithm adjusts individual GFA controller frequency setpoints based on the operational characteristics of each end‐use load and on the changing grid dynamic characteristics to selectively engage the load for mitigating the switching transients. The adaptive gradient‐descent‐based algorithm does not require control or coordination amongst end‐use devices for adapting frequency set‐points. The method is validated using dynamic simulations on a modified version of the IEEE 123‐node test system with three microgrids using the GridLAB‐DTM simulation environment. The improved dynamic stability achieved through the engagement of GFAs support the switching operations necessary for networked microgrid operations.
Synthesis of iron‐oxide magnetic nanoparticles coated with dextran of varied molecular mass using a facile ball‐milling method
Authors: Chen Bo‐Wei , Hatamie Shadie , Garu Prabir , Heravi Pooyan , Chen Jiann‐Yeu , Liu Bo‐Tau , Wei Zung‐Hang , Yao Da‐Jeng
Published: May 2020

A simple ball‐milling method was implemented to prepare dextran‐coated superparamagnetic iron oxide nanoparticles (dextran‐coated SPIONs, DSPIONs) by coating dextran (molecular mass, Mdextran, 10, 40, 70 and 100 kDa) onto nanoparticles, which synthesised with co‐precipitation methods. The size, saturation magnetisation and hydrodynamic diameters of the DSPIONs, composed of Fe3O4 and γ‐Fe2O3 proved by X‐ray diffraction and Raman spectra, were 11–14 nm, 55–65 emu g−1 and 200–300 nm using transmission electron microscope, superconducting‐quantum‐interference‐device magnetometer and dynamic light scattering devices, respectively. The characteristic lines of surface coating were revealed in attenuated‐total‐reflection Fourier‐transform infrared spectra. The saturation magnetisation and surface coating percentage (thermogravimetric analysis) of the ball‐milled DSPIONs were independent on Mdextran. The results were different from the statistical data from previous studies: DSPIONs using increasing Mdextran were accompanied by decreasing saturation magnetisation and increasing surface coating in conventional co‐precipitation protocols. 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay indicated the ball‐milled DSPIONs exhibited low cytotoxicity in human hepatoma (SK‐HEP1) cells, and the implementation of Prussian blue staining proved the DSPIONs were able to be uptaken by SK‐HEP1. There was no obvious difference between the ball‐milled DSPIONs with various Mdextran. It demonstrated the ball milling process might be potential for SPION preparation in the biomedical field.
The importance of magnification effects in galaxy-galaxy lensing
Authors: Unruh Sandra , Schneider Peter , Hilbert Stefan , Simon Patrick , Martin Sandra , Puertas Jorge Corella
Published: May 2020

Magnification changes the observed local number density of galaxies on the sky. This biases the observed tangential shear profiles around galaxies: the so-called galaxy-galaxy lensing (GGL) signal. Inference of physical quantities, such as the mean mass profile of halos around galaxies, are correspondingly affected by magnification effects. We used simulated shear and galaxy data from the Millennium Simulation to quantify the effect on shear and mass estimates from the magnified lens and source number counts. The former is due to the large-scale matter distribution in the foreground of the lenses; the latter is caused by magnification of the source population by the matter associated with the lenses. The GGL signal is calculated from the simulations by an efficient fast Fourier transform, which can also be applied to real data. The numerical treatment is complemented by a leading-order analytical description of the magnification effects, which is shown to fit the numerical shear data well. We find the magnification effect is strongest for steep galaxy luminosity functions and high redshifts. For a KiDS+VIKING+GAMA-like survey with lens galaxies at redshift zd = 0.36 and source galaxies in the last three redshift bins with a mean redshift of ¯zs = 0.79, the magnification correction changes the shear profile up to 2%, and the mass is biased by up to 8%. We further considered an even higher redshift fiducial lens sample at zd = 0.83, with a limited magnitude of 22 mag in the r-band and a source redshift of zs = 0.99. Through this, we find that a magnification correction changes the shear profile up to 45% and that the mass is biased by up to 55%. As expected, the sign of the bias depends on the local slope of the lens luminosity function αd, where the mass is biased low for αd <  1 and biased high for αd >  1. While the magnification effect of sources is rarely more than 1% of the measured GGL signal, the statistical power of future weak lensing surveys warrants correction for this effect.
Ultrasound of Normal and Injured Ligaments and Retinacula of the Hand
Authors: McCarthy Catherine L.
Published: May 2020

Clinical diagnosis of ligament and retinacular injuries of the hand may be challenging. Ultrasound (US) enables detailed high-resolution, dynamic, and real-time evaluation of these structures. This article is a comprehensive review of the intricate anatomy, optimal imaging technique, and normal US appearances of these ligaments and retinacula. The US features, pertinent biomechanics, clinical presentation, and differential diagnosis of injuries affecting the annular pulleys, differentiating from climber's finger; extensor hood including sagittal band and central slip rupture; proximal interphalangeal and metacarpophalangeal collateral ligaments including the Stener lesion and associated volar plate injury; and the anterior oblique or beak ligament of the trapeziometacarpal joint are reviewed. Emphasis is placed on optimal transducer positioning, value of dynamic US, injury severity, surgical indications, and other US findings with important management implications. US facilitates a timely accurate diagnosis of hand ligament and retinacular injury to ensure optimal patient management and minimize the risk of functional impairment of the hand.
Use of Sham Interventions in Randomized Controlled Trials in Neurosurgery
Authors: Gorayeb Rodrigo Panico , Forjaz Maria João , Ferreira António Gonçalves , Ferreira Joaquim José
Published: May 2020

Background The use of sham interventions in randomized controlled trials (RCTs) is essential to minimize bias. However, their use in surgical RCTs is rare and subject to ethical concerns. To date, no studies have looked at the use of sham interventions in RCTs in neurosurgery.

Methods This study evaluated the frequency, type, and indication of sham interventions in RCTs in neurosurgery. RCTs using sham interventions were also characterized in terms of design and risk of bias.

Results From a total of 1,102 identified RCTs in neurosurgery, 82 (7.4%) used sham interventions. The most common indication for the RCT was the treatment of pain (67.1%), followed by the treatment of movement disorders and other clinical problems (18.3%) and brain injuries (12.2%). The most used sham interventions were saline injections into spinal structures (31.7%) and peripheral nerves (10.9%), followed by sham interventions in cranial surgery (26.8%), and spine surgery (15.8%). Insertion of probes or catheters for a sham lesions was performed in 14.6%.

In terms of methodology, most RCTs using sham interventions were double blinded (76.5%), 9.9% were single blinded, and 13.6% did not report the type of blinding.

Conclusion Sham-controlled RCTs in neurosurgery are feasible. Most aim to minimize bias and to evaluate the efficacy of pain management methods, especially in spinal disorders. The greatest proportion of sham-controlled RCTs involves different types of substance administration routes, with sham surgery the less commonly performed.
Combined Coronary Artery Bypass Grafting, Aortic, and Lung Carcinoma Surgery
Authors: Goebel Nora , Franke Ulrich F.W.
Published: May 2020

Background Patients presenting with several cardiothoracic conditions that need to be addressed surgically require individual decision making as evidence remains inconclusive and combined surgical procedures carry an elevated perioperative risk.

Case Description We present the case and management of a 73-year-old male with myocardial infarction due to three-vessel disease and left main stem stenosis, calcified aortic aneurysm, and right-sided non-small cell lung carcinoma.

Conclusion High-risk combined surgery should be indicated with scrutiny after individual consideration by an experienced heart team.
Tracheal Transection—A Novel Airway Management
Authors: Fleißner Felix , Timm Max Eike , Lang Carl Philipp , Lenarz Thomas , Kühn Christian , Jaeger Daniel Benjamin
Published: May 2020

Background Traumatic injury of the trachea is rare, especially complete transection. Its operative revision requires an interdisciplinary approach.

Case Description We hereby present a rare case of complete transection of the trachea by accident. To stabilize the patient and to allow for safe surgery, veno-venous extracorporeal support was initiated via the subclavian artery and the femoral vein. The patient was subsequently operated, and the trachea re-anastomosed with favorable outcome.

Conclusion This rare case of an accidental transection of the trachea shows the importance of a good emergency rescue chain and the ability to facilitate interdisciplinary approaches in tertiary hospitals.
A Practical Guide to a Safe Sequence of Donning and Doffing of Personal Protective Equipment in Relation to COVID-19
Authors: Richard Vijay Samuel , Kanchi Muralidhar
Published: May 2020

When caring for patients with suspected or confirmed COVID-19 (coronavirus disease 2019), especially when involved in procedures that generate aerosol, personal protective equipment (PPE) with full-body coverage is recommended. The Centers for Disease Control and Prevention emphasizes and recommends the following principles with regard to donning and doffing of PPE: (1) training and education (rigorous and repeated training of the health care workers [HCWs]), (2) all HCWs must exhibit competency in the PPE donning and doffing, and (3) PPE doffing should be done in a manner that prevents self-contamination or self-inoculation with contaminated PPE or hands (remove the most contaminated PPE items first, perform hand hygiene at each stage of doffing, and discard disposable items in containers for biomedical waste).
Physics of high-efficiency 240–260 nm deep-ultraviolet lasers and light-emitting diodes on AlGaN substrate
Authors: Liu Cheng , Zhang Jing
Published: May 2020

High-efficiency III-nitride deep-ultraviolet (DUV) lasers and light-emitting diodes (LEDs) with emission wavelengths of 240–260 nm are extremely difficult to realize due to large defect density from III-nitride materials and existence of optical polarization crossover from conventional AlGaN-based quantum wells (QWs). Free-standing wurtzite AlGaN templates have been studied and developed recently; however, the physics and optical properties of AlGaN-based emitters on AlGaN templates are still relatively lacking. Therefore, this work theoretically investigates the optical properties and quantum efficiencies of the AlGaN-based QW on AlGaN substrates. The physics analysis based on a self-consistent 6-band k⋅p model shows the transverse electric (TE)-polarized optical gain increases from 558 cm−1 by using Al0.51Ga0.49N/AlN QW on the AlN substrate to 2875 cm−1 by using Al0.48Ga0.52N/Al0.72Ga0.28N QW on the Al0.72Ga0.28N substrate at 260 nm, which is attributed to the reduced strain effect and valence band rearrangement by using the AlGaN substrate. Correspondingly, the radiative recombination efficiency increases 1.66–4.43 times based on different Shockley–Read–Hall coefficients, indicating the promising potential of the use of the AlGaN substrate for high-efficiency DUV lasers and LEDs.
All-vacuum-deposited inorganic cesium lead halide perovskite light-emitting diodes
Authors: Xie Sihan , Osherov Anna , Bulović Vladimir
Published: May 2020

Polycrystalline CsPbBr3 thin films are deposited by vacuum co-evaporation of cesium halide and lead halide precursors, leading to uniform pinhole-free morphology and precise control over the film thickness and precursor stoichiometry. By utilizing the organic hole and electron transport layers, all-vacuum-deposited perovskite LEDs are fabricated. The resulting devices exhibit a maximum luminance of 1800 cd/m2, a 531 nm emission wavelength peak with a spectral linewidth of 21 nm, and an external quantum efficiency of 1.1%.
Implementation of Talbot–Lau x-ray deflectometry in the pulsed power environment using a copper X-pinch backlighter
Authors: Vescovi Milenko , Valdivia Maria Pia , Veloso Felipe , Stutman Dan , Favre Mario
Published: May 2020

A Talbot–Lau x-ray deflectometer can map electron density gradients in high energy density plasmas, as well as provide information about plasma elemental composition through single-image x-ray refraction and attenuation measurements. A new adaptation to a pulsed power environment used backlighting from copper X-pinches, allowing for electron density mapping of a low-Z object. Even though the X-pinch backlighter is not properly optimized for emitting x-rays in terms of source size and photon fluence, Moire fringe patterns with contrast up to 14% and fringe shift due to refraction on a beryllium object are obtained. Due to the proximity of the deflectometer with the X-pinch (∼6 cm), it is shown that a protective filter is required to avoid damage in the closest (i.e., source) grating due to both plasma debris and mechanical shock. Regarding grating survival, these did not show any damage due to the intense magnetic field or heating induced by plasma radiation. Electron density on beryllium was measured with a difference lower than 16%. The areal electron density mapping of the sample was limited by source size characteristics, in similarity to transmission radiography. These results show the potential of plasma electron density as well as material mapping through Talbot–Lau x-ray deflectometry in a pulsed power environment.
Controlling the dopant profile for SRH suppression at low current densities in λ ≈ 1330 nm GaInAsP light-emitting diodes
Authors: Santhanam Parthiban , Li Wei , Zhao Bo , Rogers Chris , Gray Dodd Joseph , Jahelka Phillip , Atwater Harry A. , Fan Shanhui
Published: May 2020

The quantum efficiency of double hetero-junction light-emitting diodes (LEDs) can be significantly enhanced at low current density by tailoring the spatial profile of dopants to suppress Shockley–Read–Hall recombination. To demonstrate this effect, we model, design, grow, fabricate, and test a GaInAsP LED (λ≈ 1330 nm) with an unconventional dopant profile. Compared against that of our control design, which is a conventional n+-n-p+ double hetero-junction LED, the dopant profile near the n-p+ hetero-structure of the design displaces the built-in electric field in such a way that the J02 space charge recombination current is suppressed. The design principle generalizes to other material systems and could be applicable to efforts to observe and exploit electro-luminescent refrigeration at practical power densities.
Experimental study on pulse characteristics of negative corona discharge in SF6/N2 gas mixtures under DC voltages
Authors: He Yanliang , Sun Anbang , Xue Jianyi , Shen Zhiwei , Zhang Xing , Zhang Guanjun
Published: May 2020

Corona discharge, an inevitable phenomenon, may lead to insulation degradation, threatening the safe and reliable operation of gas-insulated power equipment. The pulse stage is a complex but usual discharge process in corona discharge. In this paper, we investigate the pulse characteristics of negative corona discharge in a needle-to-plane electrode configuration in SF6/N2 gas mixtures under DC voltages. With an increase in mean current, a stage transition phenomenon from the Townsend stage through the pulse stage to the breakdown stage is observed. The variation in pulse amplitude and pulse time characteristics at the pulse stage is analyzed. In addition, the effects of gas pressure, gap spacing, and N2 content on onset voltage and pulse characteristic parameters, including pulse time parameters and the pulse repetition rate, at the pulse stage are presented. The results show that the current pulses mainly exhibit an irregular distribution of small amplitude. The pulse time parameters are not affected by gas pressure, gap spacing, or N2 content at pressures higher than 0.1 MPa. The pulse repetition rate decreases with an increase in gas pressure and N2 content but is only weakly affected by gap spacing, ranging from 1 kHz to dozens of kHz.
Design of acoustofluidic device for localized trapping
Authors: Li Li-qiang , Jia Kun , Wu Er-yong , Zhu Yong-jian , Yang Ke-ji
Published: May 2020

State of the art acoustofluidics typically treat micro-particles in a multi-wavelength range due to the scale limitations of the established ultrasound field. Here, we report a spatial selective acoustofluidic device that allows trapping micro-particles and cells in a wavelength scale. A pair of interdigital transducers with a concentric-arc shape is used to compress the beam width, while pulsed actuation is adopted to localize the acoustic radiation force in the wave propagating direction. Unlike the traditional usage of geometrical focus, the proposed device is designed by properly superposing the convergent section of two focused surface acoustic waves. We successfully demonstrate a single-column alignment of 15-μm polystyrene particles and double-column alignment of 8-μm T cells in a wavelength scale. Through proof-of-concept experiments, the proposed acoustofluidic device shows potential applications in on-chip biological and chemical analyses, where localized handing is required.
Improved measurement of electric fields by nanobeam precession electron diffraction
Authors: Bruas L. , Boureau V. , Conlan A. P. , Martinie S. , Rouviere J.-L. , Cooper D.
Published: May 2020

The electric field in a silicon p–n junction has been measured using pixelated scanning transmission electron microscopy. By using a convergence angle of 3.2 mrad, a spatial resolution better than 1 nm can be achieved leading to a rigid shift of the transmitted beam as it passes through an electric field. By precessing the beam around the optical axis at an angle of 0.1°, the effects of dynamical diffraction can be reduced. This leads to an improved measurement of the electric field from the shift of the transmitted beam. Different algorithms have been used to measure this shift, and template matching leads to a more accurate measurement of the electric field than the often-used center of mass method.
Concentrating and activating carbon dioxide over AuCu aerogel grain boundaries
Authors: Zhong Dazhong , Zhang Lei , Zhao Qiang , Cheng Dongfang , Deng Wanyu , Liu Bin , Zhang Gong , Dong Hao , Yuan Xintong , Zhao Zhijian , Li Jinping , Gong Jinlong
Published: May 2020

Alloys are active in CO2 electroreduction due to their unique electronic and geometric structures. Nevertheless, CO2 reduction selectivity is still low due to the low concentration of CO2 near the catalyst surface and the high energy barrier for CO2 activation. This paper describes an AuCu nanochain aerogel (NC–AuCu) with abundant grain boundaries (GBs) that promote the accumulation and activation of CO2 for further electrochemical reduction, employing in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy and density functional theory calculations. GBs can induce a strong local electric field to concentrate the electrolyte cations and thus accumulate CO2 near the catalyst surface. NC–AuCu exhibits a superior Faradaic efficiency of close to 100% for CO2 electroreduction to CO at an extremely low overpotential of 110 mV with a high CO partial current density of 28.6 mA cm−2 in a flow cell. Coupling with a Si solar cell to convert solar energy to CO, a very high conversion efficiency of ∼13.0% is achieved. It potentially provides broad interest for further academic research and industry applications.
A grid-connected robust control based on mixed sensitivity for AC/DC hybrid microgrid
Authors: Guo Tianyu , Li Peng , Wang Jiahao , Liu Zhe , Li Jianyi , Cai Yongqing , Zhou Fengquan
Published: May 2020

The grid-connected control technology of ac/dc hybrid microgrids affects power quality, stability, robustness, and other indicators. In order to achieve high-quality and reliability of ac/dc hybrid microgrids connected to a distributed network, this paper proposes a robust control method for grid-connected ac/dc hybrid microgrids based on mixed sensitivity. First, the grid-connected model of ac/dc hybrid microgrids is equivalent to the superposition theorem; then, the problem of how to control grid-connection can be transformed to the problem of how to deal with mixed sensitivity by considering the influence of the distributed network on ac/dc hybrid microgrids as a disturbance. Second, the grid-connected robust controller can be obtained by using the Riccati method repeatedly, which can ensure good nominal performance of the system and enhance the robustness of the system. Finally, the validity and feasibility of the proposed control method can be verified with three simulation conditions.
Electron ratchets: State of the field and future challenges
Authors: Lau Bryan , Kedem Ofer
Published: May 2020

Electron ratchets are non-equilibrium electronic devices that break inversion symmetry to produce currents from non-directional and random perturbations, without an applied net bias. They are characterized by strong parameter dependence, where small changes in operating conditions lead to large changes in the magnitude and even direction of the resulting current. This high sensitivity makes electron ratchets attractive research subjects, but leads to formidable challenges in their deeper study, and particularly to their useful application. This perspective reviews the progress that was made in the field starting from the first experimental electron ratchets in the late 1990s, and how the field spawned multiple designs with very different properties. We discuss the possible uses of electron ratchets in sensing and energy harvesting, and the specific issues encountered when idealized behavior meets complex reality. We promote an application-driven approach where complexity is not necessarily detrimental and argue that a system level perspective would be beneficial over reductionism. We highlight several promising research directions, which revolve around the intentional study of complex effects, and the modeling of realistic devices.
Differential coloration efficiency of electrochromic amorphous tungsten oxide as a function of intercalation level: Comparison between theory and experiment
Authors: Rojas-González Edgar A. , Niklasson Gunnar A.
Published: May 2020

Optical absorption in amorphous tungsten oxide (aWO3), for photon energies below that of the bandgap, can be rationalized in terms of electronic transitions between localized states. For the study of this phenomenon, we employed the differential coloration efficiency concept, defined as the derivative of the optical density with respect to the inserted charge. We also made use of its extension to a complex quantity in the context of frequency-resolved studies. Combined in situ electrochemical and optical experiments were performed on electrochromic aWO3 thin films for a wide lithium intercalation range using an optical wavelength of 810nm (1.53eV). Quasi-equilibrium measurements were made by chronopotentiometry (CP). Dynamic frequency-dependent measurements were carried out by simultaneous electrochemical and color impedance spectroscopy (SECIS). The differential coloration efficiency obtained from CP changes sign at a critical intercalation level. Its response exhibits an excellent agreement with a theoretical model that considers electronic transitions between W4+, W5+, and W6+ sites. For the SECIS experiment, the low-frequency limit of the differential coloration efficiency shows a general trend similar to that from CP. However, it does not change sign at a critical ion insertion level. This discrepancy could be due to degradation effects occurring in the films at high Li+ insertion levels. The methodology and results presented in this work can be of great interest both for the study of optical absorption in disordered materials and for applications in electrochromism.
Natural frequency calculation of elastically connected double-beam system with arbitrary boundary condition
Authors: Kim Kwanghun , Han Poknam , Jong Kunchol , Jang Cholhuan , Kim Ryongwon
Published: May 2020

In this paper, the free vibration characteristics of an elastically connected double-beam system (ECDBS) connected by an elastic layer with uniform elastic stiffness under arbitrary boundary conditions have been investigated. Timoshenko beam theory, in which the effects of shear deformation and rotational inertia are considered, is utilized to model the free vibration of the ECDBS, and displacement components can be obtained from the Haar wavelet series and their integral. Hamilton’s principle is applied to construct coupled governing equations, and the virtual spring boundary technique is applied to generalize boundary conditions at four ends of the ECDBS. The convergence and accuracy of the proposed method can be confirmed by comparing the results with those of previous literature. A lot of new features have been identified, such as the frequency characteristics of the ECDBS with different cross sections under arbitrary boundary conditions, which can be provided as reference data for future research.
The function of KptA/Tpt1 gene – a minor review
Authors: Yang Shiquan , Qu Gaoyi , Fu Bixia , Yang Feng , Zeng Weixian , Cai Yunzhang , Ye Tao , Yang Youzhen , Deng Xiangwen , Xiang Wenhua , Peng Dan , Zhou Bo
Published: May 2020

Rapid response of uni- and multicellular organisms to environmental changes and their own growth is achieved through a series of molecular mechanisms, often involving modification of macromolecules, including nucleic acids, proteins and lipids. The ADP-ribosylation process has ability to modify these different macromolecules in cells, and is closely related to the biological processes, such as DNA replication, transcription, signal transduction, cell division, stress, microbial aging and pathogenesis. In addition, tRNA plays an essential role in the regulation of gene expression, as effector molecules, no-load tRNA affects the overall gene expression level of cells under some nutritional stress. KptA/Tpt1 is an essential phosphotransferase in the process of pre-tRNA splicing, releasing mature tRNA and participating in ADP-ribose. The objective of this review is concluding the gene structure, the evolution history and the function of KptA/Tpt1 from prokaryote to eukaryote organisms. At the same time, the results of promoter elements analysis were also shown in the present study. Moreover, the problems in the function of KptA/Tpt1 that have not been clarified at the present time are summarised, and some suggestions to solve those problems are given. This review presents no only a summary of clear function of KptA/Tpt1 in the process of tRNA splicing and ADP-ribosylation of organisms, but also gives some proposals to clarify unclear problems of it in the future.
Production and roles of IAA and ABA during development of superior and inferior rice grains
Authors: Nonhebel Heather M. , Griffin Karina
Published: May 2020

Current understanding of the role of plant hormones during cereal grain filling is confounded by contradictory reports on hormone production that is based on poor methodology. We report here on the accurate measurement of indole-3-acetic acid (IAA) and abscisic acid (ABA) by combined liquid chromatography-tandem mass spectrometry in multiple reaction-monitoring mode with heavy isotope labelled internal standards. ABA and IAA contents of superior versus inferior rice grains (ABA maxima 159 ng g–1 FW and 109 ng g–1 FW, IAA maxima 2 µg g–1 FW and 1.7 µg g–1 FW respectively) correlated with the expression of biosynthetic genes and with grain fill. Results confirm that grain ABA is produced primarily by OsNCED2(5), but suggest that ABA import and metabolism also play important roles in ABA regulation. The IAA content of grains is primarily influenced by OsYUC9 and OsYUC11. However, the distinct expression profile of OsYUC12 suggests a specific role for IAA produced by this enzyme. Co-expression of OsYUC12 with OsIAA29 indicates their involvement in a common signalling pathway. Co-expression and cis-element analysis identified several aleurone-specific transcriptional regulators as well as glutelin as strong candidates for detailed investigation for direct regulation by the auxin-signalling pathway.
Cell response to substrate rigidity is regulated by active and passive cytoskeletal stress
Authors: Doss Bryant L. , Pan Meng , Gupta Mukund , Grenci Gianluca , Mège René-Marc , Lim Chwee Teck , Sheetz Michael P. , Voituriez Raphaël , Ladoux Benoît
Published: May 2020

Significance

The observation that cells sense and adapt to the physical stiffness of their environment is consistent across many different cell types and has profound implications in the final biological phenotype. In a diseased state or transformed cell, the substrate rigidity sensing and adaptation machinery is perturbed or outright abolished, which leads to progression of the disease, thus fully understanding this process is vital. Here, we found that the organization of the actin cytoskeleton in fibroblasts was governed by active and passive cross-linkers and the relative cell-to-substrate elasticity, and we present a phenomenological model detailing this. As cell rigidity sensing is a robust mechanism observed in various contexts, a generalized physics-based understanding such as presented here will yield universal insights.
The myosin interacting-heads motif present in live tarantula muscle explains tetanic and posttetanic phosphorylation mechanisms
Authors: Padrón Raúl , Ma Weikang , Duno-Miranda Sebastian , Koubassova Natalia , Lee Kyoung Hwan , Pinto Antonio , Alamo Lorenzo , Bolaños Pura , Tsaturyan Andrey , Irving Thomas , Craig Roger
Published: May 2020

Striated muscle contraction involves sliding of actin thin filaments along myosin thick filaments, controlled by calcium through thin filament activation. In relaxed muscle, the two heads of myosin interact with each other on the filament surface to form the interacting-heads motif (IHM). A key question is how both heads are released from the surface to approach actin and produce force. We used time-resolved synchrotron X-ray diffraction to study tarantula muscle before and after tetani. The patterns showed that the IHM is present in live relaxed muscle. Tetanic contraction produced only a very small backbone elongation, implying that mechanosensing—proposed in vertebrate muscle—is not of primary importance in tarantula. Rather, thick filament activation results from increases in myosin phosphorylation that release a fraction of heads to produce force, with the remainder staying in the ordered IHM configuration. After the tetanus, the released heads slowly recover toward the resting, helically ordered state. During this time the released heads remain close to actin and can quickly rebind, enhancing the force produced by posttetanic twitches, structurally explaining posttetanic potentiation. Taken together, these results suggest that, in addition to stretch activation in insects, two other mechanisms for thick filament activation have evolved to disrupt the interactions that establish the relaxed helices of IHMs: one in invertebrates, by either regulatory light-chain phosphorylation (as in arthropods) or Ca
2+
-binding (in mollusks, lacking phosphorylation), and another in vertebrates, by mechanosensing.
Magnetotransport studies of Fe vacancy-ordered Fe
4+δ
Se
5
nanowires
Authors: Yeh Keng-Yu , Lo Tung-Sheng , Wu Phillip M. , Chang-Liao Kuei-Shu , Wang Ming-Jye , Wu Maw-Kuen
Published: May 2020

Significance

This work reveals that Fe
4+δ
Se
5
with ordered Fe vacancy is a nonoxide compound with the Verwey-like electronic correlation. Detailed measurements showing magnetic field-independent magnetoresistance at low temperature suggest it is in a charge-ordered state below
T
≈ 17 K. The results of the field orientation measurements indicate that the spin-orbital coupling is crucial in √5 × √5 Fe vacancy-ordered Fe
4+δ
Se
5
at low temperatures. Our findings provide valuable information to better understand the orbital nature and the interplay between the metal-insulator transition and superconductivity in FeSe-based materials.
Molecular taxonomy of human ocular outflow tissues defined by single-cell transcriptomics
Authors: Patel Gaurang , Fury Wen , Yang Hua , Gomez-Caraballo Maria , Bai Yu , Yang Tao , Adler Christina , Wei Yi , Ni Min , Schmitt Heather , Hu Ying , Yancopoulos George , Stamer W. Daniel , Romano Carmelo
Published: May 2020

The conventional outflow pathway is a complex tissue responsible for maintaining intraocular pressure (IOP) homeostasis. The coordinated effort of multiple cells with differing responsibilities ensures healthy outflow function and IOP maintenance. Dysfunction of one or more resident cell types results in ocular hypertension and risk for glaucoma, a leading cause of blindness. In this study, single-cell RNA sequencing was performed to generate a comprehensive cell atlas of human conventional outflow tissues. We obtained expression profiles of 17,757 genes from 8,758 cells from eight eyes of human donors representing the outflow cell transcriptome. Upon clustering analysis, 12 distinct cell types were identified, and region-specific expression of candidate genes was mapped in human tissues. Significantly, we identified two distinct expression patterns (myofibroblast- and fibroblast-like) from cells located in the trabecular meshwork (TM), the primary structural component of the conventional outflow pathway. We also located Schwann cell and macrophage signatures in the TM. The second primary component structure, Schlemm’s canal, displayed a unique combination of lymphatic/blood vascular gene expression. Other expression clusters corresponded to cells from neighboring tissues, predominantly in the ciliary muscle/scleral spur, which together correspond to the uveoscleral outflow pathway. Importantly, the utility of our atlas was demonstrated by mapping glaucoma-relevant genes to outflow cell clusters. Our study provides a comprehensive molecular and cellular classification of conventional and unconventional outflow pathway structures responsible for IOP homeostasis.
Husserl’s phenomenology of inner time-consciousness and enactivism
Authors: Senderowicz Yaron M.
Published: May 2020

In this article, I single out the characteristics of a polemical type of argument that I dub “the harmonizing argument”. Contenders that use the harmonizing argument aim to persuade their audience that it is possible to harmonize two opposed positions. My case study is the enactivists’ attempt to naturalize Husserl’s phenomenology of inner time-consciousness. I first present Husserl’s account of time-consciousness. I clarify why absolute subjectivity cannot be naturalized. I continue by interpreting the enactivists’ attempt to naturalizes absolute subjectivity as exemplifying the harmonizing argument. I present the limitations of this attempt, and I conclude by pointing out the possible positive epistemic results of using this type of argument.
The pointer finger and the pilgrim shell
Authors: Scarafile Giovanni
Published: May 2020

One of the risks to the study of interdisciplinary dynamics is to limit the analysis to a description of the visible structures through which it is in action.

Indeed, there are a number of factors which, although invisible, may contribute to the success or failure of an interdisciplinary enterprise.

Through the examination of two case studies, I examine these implicit factors, which underlie the development of interdisciplinarity. In particular, the role of habits, identity factors and the very inadequacy of rational arguments are examined. In a dialectic between invisible and visible emerges the picture of a complex phenomenon to which Caravaggio’s Seven Works of Mercy alludes in the final part of the essay.
Annealing twins in high purity aluminium processed by dynamic equal channel angular pressing
Authors: Liu J. Y. , Xiang J. Q. , Li C. , Lu L. , Zhong Z. Y. , Luo S. N.
Published: May 2020

Annealing twins are synthesised in high purity aluminium processed by dynamic equal channel angular pressing during annealing. Annealing twins and recrystallised grains encircling the twins have specific crystallographic orientation relationships with the deformed matrix grains: approximately 35°–50°<110> for the twins and 30°–45°<100> for the recrystallised grains. Stored energy during dynamic pressing, and the crystallographic orientation between annealing twins and the deformed matrix, strongly affect twin growth during annealing.
Prescription-Related Risk Factors for Opioid-Related Overdoses in the Era of Fentanyl Contamination of Illicit Drug Supply: A Retrospective Case-Control Study
Authors: Smolina Kate , Crabtree Alexis , Chong Mei , Park Mina , Mill Christopher , Zhao Bin , Schütz Christian G.
Published: May 2020

Background: We sought to quantify the association between clinical, physiological, and contextual factors and opioid-related overdose, specifically focusing on current and past use of select prescription medications. Methods: We conducted a case-control study of individuals who experienced a non-fatal opioid-related overdose between January 2015 and November 2016 in British Columbia, Canada. We matched 8,831 cases to 44,155 controls on birth year, sex, and local health area of residence and examined 5-year prescribing history for opioids for pain, medications for opioid use disorder (MOUD), benzodiazepines/z-drugs, and other psychoactive medications. Results: The overall prevalence of prescription opioid drug use was generally low in the study population. Cases had a relatively higher use of selected prescription medications, a higher physical and mental morbidity burden, and were less connected to health services compared with controls. For opioids for pain, current therapy was associated with experiencing an overdose (OR = 8.5, 95%CI: 7.3–10); history of long-term use had a stronger association than history of short-term use (OR = 2.9, 95%CI: 2.6–3.3 vs OR = 1.7, 95%CI: 1.5–1.8, respectively). While persons on MOUD were more likely to overdose compared to persons who were not on therapy (OR = 2.0, 95%CI 1.7–2.4), recent discontinuation of MOUD greatly increased the likelihood of overdose (OR = 25.6, 95%CI 17.5–37.4). Active therapy of benzodiazepines/z-drugs and other sedating medications also significantly increased the likelihood of overdose. Conclusions: While this study supports expansion of efforts to prevent overdoses among individuals actively using opioids for pain and improve retention among those on MOUD, it is also important to address other clinical, physiological, and contextual risk and protective factors to help curb the current overdose crisis.
A PI3K-WIPI2 positive feedback loop allosterically activates LC3 lipidation in autophagy
Authors: Fracchiolla Dorotea , Chang Chunmei , Hurley James H. , Martens Sascha
Published: May 2020

Autophagy degrades cytoplasmic cargo by its delivery to lysosomes within double membrane autophagosomes. Synthesis of the phosphoinositide PI(3)P by the autophagic class III phosphatidylinositol-3 kinase complex I (PI3KC3-C1) and conjugation of ATG8/LC3 proteins to phagophore membranes by the ATG12–ATG5-ATG16L1 (E3) complex are two critical steps in autophagosome biogenesis, connected by WIPI2. Here, we present a complete reconstitution of these events. On giant unilamellar vesicles (GUVs), LC3 lipidation is strictly dependent on the recruitment of WIPI2 that in turn depends on PI(3)P. Ectopically targeting E3 to membranes in the absence of WIPI2 is insufficient to support LC3 lipidation, demonstrating that WIPI2 allosterically activates the E3 complex. PI3KC3-C1 and WIPI2 mutually promote the recruitment of each other in a positive feedback loop. When both PI 3-kinase and LC3 lipidation reactions were performed simultaneously, positive feedback between PI3KC3-C1 and WIPI2 led to rapid LC3 lipidation with kinetics similar to that seen in cellular autophagosome formation.
Zitterbewegung-mediated RKKY coupling in topological insulator thin films
Authors: Ho Cong Son , Tan Seng Ghee , Siu Zhuo Bin , Jalil Mansoor B A
Published: May 2020

The dynamics of itinerant electrons in topological insulator (TI) thin films is investigated using a multi-band decomposition approach. We show that the electron trajectory in the 2D film is anisotropic and confined within a characteristic region. Remarkably, the confinement and anisotropy of the electron trajectory are associated with the topological phase transition of the TI system, which can be controlled by tuning the film thickness and/or applying an in-plane magnetic field. Moreover, persistent electron wavepacket oscillation can be achieved in the TI thin film system at the phase transition point, which may assist in the experimental detection of the jitter motion (Zitterbewegung). The implications of the microscopic picture of electron motion in explaining other transport-related effects, e.g., electron-mediated RKKY coupling in the TI thin film system, are also discussed.