bluuebunny/crossref_metadata_2025 huggingface dataset:
Analytical modelling of radial suspension force in bearingless surface‐mounted PM synchronous motors considering static rotor eccentricity
Authors: Jafarboland Mehrdad , Shirzadi Ali
Published: July 2019

In this study, a new analytical model is provided in order to calculate the radial suspension force in bearingless surface‐mounted permanent magnet synchronous motor with static rotor eccentricity. The proposed model is based on the harmonic analysis of magnetic flux density, and considers the influence of both radial and tangential air‐gap field components on the computation of radial suspension force. This model can reveal the generation mechanism of the radial suspension force and identify the generation sources of the force ripples. Furthermore, the magnitudes and frequencies of radial suspension force harmonics, and the relationship between the radial suspension force and rotor eccentric displacements can be accurately predicted by the proposed model. However, this model cannot be used for saturated machines. The analytical model is verified by finite‐element analyses and the result of static experimental study.
Sensorless control strategy for doubly salient electro‐magnetic machine based on the line‐to‐line excitation flux linkage
Authors: Liu Weifeng , Wang Huizhen , Wang Yongjie , Xiao Lan , Zhang Hongyan
Published: July 2019

This article presents a sensorless control strategy based on the line‐to‐line excitation flux linkage for doubly salient electro‐magnetic machine. The negative‐going zero‐crossing points of the line‐to‐line excitation flux linkage are detected to estimate the position and speed. To solve the problems of direct current (DC) bias and error accumulation in pure integrator, a combination of first‐order low‐pass filter and first‐order high‐pass filter is adopted to estimate the line‐to‐line flux linkage. Considering that the self‐inductance obviously varies with the position and the phase current, an equivalent inductance is introduced to calculate the line‐to‐line excitation flux linkage in the whole period. The commutation error caused by the filter and the armature reaction is analysed and proved to be within ±6°. The proposed method can be applied to either the three‐state standard angle control or the six‐state advanced angle control. The experiment platform based on a 9‐kW/3000‐rpm DSEM is built, and the validity and feasibility of the proposed strategy are proved.
Distributed event‐triggered scheme for economic dispatch in power systems with uncoordinated step‐sizes
Authors: Wang Jinmeng , Li Huaqing , Wang Zheng
Published: July 2019

Considering potential applications in power systems, economic dispatch problem (EDP) in time‐varying balanced communication networks is studied, aiming to minimise the total cost of generating electricity. This is equivalent to dealing with the problem of optimising the sum of local functions while a single generator possesses only its local function. The variables of generators, satisfying some local constraints, are coupled by a linear constraint. In order to resolve the EDP, the authors design a fully distributed primal‐dual optimisation algorithm with time‐varying uncoordinated step‐sizes. In consideration of saving computation and communication resources, an event‐triggered scheme is introduced into the algorithm, based on which each generator is only allowed to interact with their neighbouring generators at some independent event‐triggered sampling time instants. The proposed algorithm is able to achieve a linear convergence rate under the strong convexity and smoothness of the local objective functions. The Zeno‐like behaviour is rigorously excluded, which means that the interval between any two consecutive sampling time instants of each generator is not less than two. Effectiveness of the algorithm and correctness of the theoretical analysis are verified by numerical experiments.
Robust N–k CCUC model considering the fault outage probability of units and transmission lines
Authors: Chen Yanbo , Zhang Zhi , Liu Zhaoyan , Zhang Pu , Ding Qiang , Liu Xinyuan , Wang Weiru
Published: July 2019

Robust optimisation has been applied to the dispatching problem considering fault outage of power systems. The traditional fault outage uncertainty set are too conservative. To solve this problem, a robust contingency constrained unit commitment (CCUC) model considering the outage probability of units and transmission lines is proposed. The proposed model has the following characteristics: (i) the outage probability of units is determined by normal operation time and fault repair time, whereas the outage probability of transmission lines is determined by length and load rate; (ii) based on the probability criterion of unit outage contingencies, the outage probabilities of units and transmission lines are both incorporated into the modelling of uncertainty sets; (iii) the robust CCUC model obtains UC decision of base case and the UC decision under uncertainty scenarios can adjust the output of units by spinning reserve capacity to cope with stochastic fault outage scenarios. The proposed robust CCUC model is solved with Benders‐column and constraint generation (C&CG) method combined with Benders decomposition method and C&CG method. Simulations on the modified IEEE‐RTS‐79 system and IEEE‐RTS‐96 system demonstrate the effectiveness and reliability of the proposed robust CCUC model.
Classification of drug molecules for oxidative stress signalling pathway
Authors: Verma Nikhil , Singh Harpreet , Khanna Divya , Rana Prashant Singh , Bhadada Sanjay Kumar
Published: July 2019

In humans, oxidative stress is involved in the development of diabetes, cancer, hypertension, Alzheimers’ disease, and heart failure. One of the mechanisms in the cellular defence against oxidative stress is the activation of the Nrf2‐antioxidant response element (ARE) signalling pathway. Computation of activity, efficacy, and potency score of ARE signalling pathway and to propose a multi‐level prediction scheme for the same is the main aim of the study as it contributes in a big amount to the improvement of oxidative stress in humans. Applying the process of knowledge discovery from data, required knowledge is gathered and then machine learning techniques are applied to propose a multi‐level scheme. The validation of the proposed scheme is done using the K‐fold cross‐validation method and an accuracy of 90% is achieved for prediction of activity score for ARE molecules which determine their power to refine oxidative stress.
Investigation of a decentralised control strategy for grid frequency support from DC microgrids
Authors: Florida‐James Anthony , Yana Syiska , Emhemed Abdullah , Burt Graeme
Published: July 2019

DC microgrids (DC‐MGs) are capable of integrating and coordinating distributed energy resources into power systems, along with providing services to the wider system, e.g. balancing, frequency support, demand response and so on. This study investigates the capability of DC‐MGs providing grid frequency support, for the GB enhanced frequency response service. In this study, photovoltaic generation, energy storage, and load form the DC‐MGs. The control strategy is a decentralised scheme, based on conventional droop control for active power sharing and grid frequency support. Droop control is also used within the DC‐MG for power‐sharing amongst generation and load. Scenarios are conducted to evaluate the effectiveness of the control strategy and verified by MATLAB/Simulink simulations.
Master–slave current regulation of an LCL‐filter‐based grid‐connected inverter under variable grid condition
Authors: He Yuanbin , Peng Yuqi , Wang Bangchao , Hang Lijun
Published: July 2019

To ease the heavy burden of inverter control, including line current regulation, harmonic current suppression, filter resonance suppression, grid distortion suppression, phase locked loop etc., the study proposes a master–slave current regulation method for an LCL‐filter‐based grid‐connected inverter operating under variable grid condition. The proposed system is composed of a grid‐connected voltage‐source inverter (GC‐VSI) in series with a bidirectional voltage‐source converter (B‐VSC) at the inverter output. The GC‐VSI is responsible for line current regulation, while the B‐VSC takes charge of harmonic current suppression and grid impedance cancellation. Owing to low volt‐ampere of the B‐VSC, the efficiency of the inverter system is not sacrificed. To confirm its validity, a simulation platform with the proposed inverter system has been built. The simulation results demonstrate the performance enhancement of the proposed inverter system operating under different grid conditions.
Euclidean Jordan algebras and some conditions over the spectra of a strongly regular graph
Authors: Vieira Luís
Published: July 2019

LetGbe a primitive strongly regular graphGsuch that the regularity is less than half of the order ofGandAits matrix of adjacency, and let 𝒜 be the real Euclidean Jordan algebra of real symmetric matrices of ordernspanned by the identity matrix of ordernand the natural powers ofAwith the usual Jordan product of two symmetric matrices of ordernand with the inner product of two matrices being the trace of their Jordan product. Next the spectra of two Hadamard series of 𝒜 associated toA2is analysed to establish some conditions over the spectra and over the parameters ofG.
Apnea of Prematurity: An Update
Authors: Gileles-Hillel Alex , Erlichman Ira , Reiter Joel
Published: July 2019

Apnea of prematurity (AOP) affects the majority of infants born prematurely, before 34 weeks of gestational age. AOP is a common diagnosis in the neonatal intensive care unit and one of significant clinical importance, both immediate and long term, as it is associated with reduced survival and poorer respiratory and neurodevelopmental outcomes. In this review, we provide an up-to-date summary of recent advances in the understanding of the pathophysiology of AOP, as well as the clinical questions relevant to physicians and staff treating infants with AOP. Finally, we discuss monitoring and discharge decisions, as these are areas of significant uncertainty.
Linking Complement Activation, Coagulation, and Neutrophils in Transplant-Associated Thrombotic Microangiopathy
Authors: Gavriilaki Eleni , Chrysanthopoulou Akrivi , Sakellari Ioanna , Batsis Ioannis , Mallouri Despina , Touloumenidou Tasoula , Papalexandri Apostolia , Mitsios Alexandros , Arampatzioglou Athanasios , Ritis Konstantinos , Brodsky Robert Alan , Mitroulis Ioannis , Anagnostopoulos Achilles
Published: July 2019

Transplant-associated thrombotic microangiopathy (TA-TMA) is a severe and life-threatening complication of hematopoietic cell transplantation (HCT) that often coincides with graft-versus-host-disease (GVHD). Although endothelial damage seems to be the common denominator for both disorders, the role of complement system, neutrophils, and coagulation has not been clarified. In an effort to distinguish the pathogenesis of TA-TMA from GVHD, we evaluated markers of complement activation, neutrophil extracellular trap (NET) release, endothelial damage, and activation of coagulation cascade in the circulation of patients with these two disorders, as well as control HCT recipients without TA-TMA or GVHD. We observed that the terminal complement product C5b-9 levels, the levels of markers of NET formation, and thrombin–antithrombin complex levels were significantly increased in the TA-TMA group compared with patients without complications, whereas there was no significant difference between the GVHD and the control group. On the other hand, the levels of circulating thrombomodulin, an endothelial damage marker, were significantly increased in both TA-TMA and GVHD patients. These findings propose a role for the interplay between complement system, neutrophil activation through NET release, and activation of the coagulation cascade in TA-TMA.
Probabilistic generation model for grid connected wind DG
Authors: ur Rehman Waqas , Khan Muhammad Faisal Nadeem , Sajjad Intisar Ali , Umar Afzaal Muhammad
Published: July 2019

The uncertainty associated with renewable energy sources, particularly wind, makes them an unpredictable means of power generation. To guarantee continuous and reliable power supply, wind speed variability modeling is considered a vital step for meeting the planning and operational challenges of an electric power grid. In this paper, a novel probabilistic generation model is developed to estimate and generate time-coupled wind speed patterns. A 1 h time step is considered to construct the time-coupled probabilistic wind speed patterns based on a two-parameter Weibull distribution. These parameters of the Weibull distribution are found by considering the variations of reference wind speed patterns at two successive time steps. The probabilistic model is then used to create a number of aggregate wind speed generation scenarios. The validity of our proposed approach is evaluated with the help of goodness-of-fit test indicators such as average mean absolute percentage error and the Kolmogorov–Smirnov test error. The results of goodness of fit tests and comparison of output power determined through the proposed model with the existing model in the literature suggest that the proposed model is appropriate for wind speed uncertainty modeling and can be applied in power system planning studies.
Design of broadband reflector at the visible wavelengths using particle swarm optimization
Authors: He Shumin , Liu Qifa , Sa Tongliang , Wang Zhenhai
Published: July 2019

We design and theoretically investigate freestanding gallium nitride (GaN) high contrast grating (HCG) membranes as broadband reflectors operating at the visible wavelengths. Optimization of the grating structural parameters is accomplished by using particle swarm optimization (PSO), and rigorous coupled-wave analysis (RCWA) method is adopted to evaluate the optical spectrum and internal electric field intensity distribution of all structures. The proposed reflector exhibits a 99% reflectance bandwidth of 84 nm, and good angular insensitivity of about 10.2° at the wavelength of 470 nm. The tolerance of fabrication deviation is also examined by numerical analysis of the reflector performance through varying the grating structural parameters. The GaN HCG broadband reflector can be potentially assembled in GaN-based vertical cavity surface-emitting lasers (VCSELs) or other novel integrated photonic devices.
Ultra-wideband RCS reduction and gain enhancement of patterned-surface-based aperture coupling patch antenna with optimized arrangement method
Authors: Jia X. Q. , Zheng Y. J. , Cao X. Y. , Gao J. , Chen Q. , Fu Y. Q.
Published: July 2019

A patterned-surface-based aperture coupling patch antenna (ACPA) with ultra-wideband radar cross section reduction (RCSR) and gain enhancement is presented in this paper. Due to the air-filled gap structure of the ACPA, an air spacer is introduced to design double-layer patterned surface (PS), which broadens the RCSR bandwidth of ACPA. Moreover, to obtain better gain of antenna, the arrangement of PS is optimized based on its current distributions. Experimental results show that impedance matching of PS-based ACPA is preserved well and operation band is broadened slightly from 8.0 to 11.3 GHz. The boresight gain is enhanced from 7.5 to 11.5 GHz, with a peak gain enhancement of 4.1 dB at 9.7 GHz. Meanwhile, the PS-based ACPA possesses the ability of specular RCSR over the band 3.0-20.0 GHz for both polarizations. The 10-dB RCS reduction of the antenna is achieved almost from 5.5 to 17.0 GHz for normal incidence.
Terahertz conductivity of the magnetic Weyl semimetal Mn3Sn films
Authors: Cheng Bing , Wang Youcheng , Barbalas D. , Higo Tomoya , Nakatsuji S. , Armitage N. P.
Published: July 2019

Mn3Sn is a noncollinear antiferromagnet which displays a large anomalous Hall effect at room temperature. It is believed that the principal contribution to its anomalous Hall conductivity comes from the Berry curvature. Moreover, dc transport and photoemission experiments have confirmed that Mn3Sn may be an example of a time-reversal symmetry breaking Weyl semimetal. Due to a small, but finite moment in the room temperature inverse triangular spin structure, which allows control of the Hall current with the external field, this material has garnered much interest for next generation memory devices and terahertz spintronics applications. In this work, we report a terahertz range study of randomly oriented Mn3Sn thin films as a function of temperature. At low frequencies, we found that the optical conductivity can be well described by a single Drude oscillator. The plasma frequency is strongly suppressed in a temperature dependent fashion as one enters the 260 K helical phase. This may be associated with partial gapping of the Fermi surfaces, which comes from breaking translational symmetry along the c-axis. The scattering rate shows a quadratic temperature dependence below 200 K, highlighting the possible important role of interactions in this compound.
Molecular Helmholtz coils
Authors: Orozco-Ic Mesías , Restrepo Albeiro , Muñoz-Castro Alvaro , Merino Gabriel
Published: July 2019

How to build a molecular Helmholtz coil? The possibility to create a Helmholtz coil at the molecular level is studied via the induced magnetic responses of several small cyclic hydrocarbon dimers with formula (CnHn)2 and Dnh symmetry (n = 6–10). Our results reveal that for n ≥ 8, π-electrons give rise to a uniform magnetic field within the central region between rings, satisfying the Helmholtz coil condition. This uniformity is independent of the intensity of the induced magnetic field.
Photoemission studies of organic semiconducting materials using open Geiger-Müller counter
Authors: Nekrasovas Jonas , Gaidelis Valentas , Kamarauskas Egidijus , Viliūnas Mindaugas , Jankauskas Vygintas
Published: July 2019

We investigated an open ionization cell based on the Geiger-Müller counter principle in a gas mixture at atmospheric pressure and demonstrated that the photoemission signals as weak as 1 electron per second are detectable. This finding allowed us to investigate more accurately the photoemission spectrums, especially in the vicinity of the photoemission threshold. Using such a cell, we investigated a number of organic semiconductor materials, tested various ways to analyze the results of the measurements of photoemission spectrums, and demonstrated an efficient way to determine ionization potential by using the square root of the derivative of the yield dependence on the light quanta energy (dY1/d(hν))1/2. This method leads to more evident graphical representation of the measurement results and better Ip estimation in comparison to the results estimated by using the traditional method of plotting Y1/n dependence on the quanta energy hν.
Detection of radiation torque exerted on an alkali-metal vapor cell
Authors: Hatakeyama Atsushi , Yasuda Runa , Goto Yutaka , Chikakiyo Natsumi , Kuroda Takahiro , Nagata Yugo
Published: July 2019

We have developed a torsion balance to detect the rotation of a cell containing spin-polarized gaseous atoms to study angular momentum transfer from gaseous atoms to solid. A cesium vapor cell was hung from a thin wire in a vacuum chamber, and irradiated from the bottom with circularly polarized light tuned to the D2 transition to polarize cesium atoms in the cell. By varying the light helicity at the resonance frequency of the torsion balance, we induced forced rotational oscillation of the cell and detected radiation torque exerted on the cesium vapor cell through the cesium atoms inside. The torque was particularly large when both hyperfine levels of cesium atoms were optically pumped with application of a longitudinal magnetic field. Further detailed study will provide new insights into spin-transfer processes at the gas-solid interface.
Observation and mitigation of RF-plasma-induced damage to III-nitrides grown by molecular beam epitaxy
Authors: Clinton Evan A. , Vadiee Ehsan , Tellekamp M. Brooks , Doolittle W. Alan
Published: July 2019

In this work, radio-frequency (RF) plasma-induced damage to III-nitride surfaces and bulk defects is observed and mitigated. It is shown that for InN films, the surface is more sensitive to plasma-induced damage than GaN films, as observed via atomic force microscopy and reflection high energy electron diffraction. In order to isolate any possible plasma-induced damage, a growth window for InN is established, and temperature ranges are determined for other damaging effects which include roughening due to low adatom mobility, InN decomposition, and indium desorption. In situ plasma monitoring and optimization are accomplished with a combination of optical emission spectroscopy as well as a remote Langmuir probe. It is shown that by increasing the plasma nitrogen flow, the positive ion content increases; however, the ion acceleration potential reduces. Additionally, a reduced RF plasma power results in a reduction of atomic nitrogen species. These plasma species and energetic variations result in variations in the bulk unintentional background electron concentrations observed by room temperature Hall effect measurements of ∼1 μm thick InN films. By increasing the nitrogen flow from 2.5 to 7.5 sccm for a constant RF power of 350 W, the background electron concentration decreases by 74% from 1.36 × 1019 cm−3 to 3.54 × 1018 cm−3, while maintaining a smooth surface morphology. Additionally, photoluminescence spectra indicate optical emission energies shift from ∼0.81 to 0.71 eV (closer to the fundamental bandgap of InN) by limiting the damaging plasma species. Finally, conditions are presented to further minimize plasma-induced damage in III-nitride devices.
Layer-selective spin amplification in size-modulated quantum nanocolumn
Authors: Hiura Satoshi , Saito Shotaro , Takayama Junichi , Kiba Takayuki , Murayama Akihiro
Published: July 2019

The optical spin properties of size-modulated quantum nanocolumns (QNCs), which are composed of 9 layers of vertically coupled InGaAs quantum dots (QDs), have been studied by circularly polarized time-resolved photoluminescence spectroscopy of QD excited states with barrier excitation. High spin polarization at the emissive state is one of the essential elements in the development of spin-functional optical devices. Coupling of QD excited states can enhance the spin polarization if only minority spins are effectively removed from the emissive excited states. In this study, size-modulated QNCs with the increasing size toward the upper layer were grown, and we revealed that the combination of QD size modulation and electron wavefunction coupling in the stacking direction can greatly enhance spin polarization during light emission from the smaller-sized QD layers. We observed a temporal spin amplification of more than 80% at coupled excited states. This enhancement is derived from the size-modulation-induced selective transfer of minority spins to the larger-sized QD layers, which have abundant excited states where electron spins are transferred. In addition, we found that QNCs can retain high spin polarization even at high excitation spin density. Our findings of spin amplification during light emission will provide QNC systems suitable for spin-functional optical devices.
Representation independent boundary conditions for a piecewise-homogeneous linear magneto-dielectric medium
Authors: Crenshaw Michael E.
Published: July 2019

At a boundary between two transparent, linear, isotropic, homogeneous materials, derivations of the electromagnetic boundary conditions and the Fresnel relations typically proceed from the Minkowski {E,B,D,H} representation of the macroscopic Maxwell equations. However, equations of motion for macroscopic fields in a transparent linear medium can be written using Ampère {E,B}, Chu {E,H}, Lorentz, Minkowski, Peierls, and other formulations of continuum electrodynamics. We present a representation-independent derivation of electromagnetic boundary conditions and Fresnel relations for the propagation of monochromatic radiation through a piecewise-homogeneous, transparent, linear, magneto-dielectric medium. The electromagnetic boundary conditions and the Fresnel relations are derived from energy conservation coupled with the application of Stokes’s theorem to the wave equation. Our representation-independent formalism guarantees the general applicability of the Fresnel relations. Specifically, the new derivation is necessary so that a valid derivation of the Fresnel equations exists for alternative, non-Minkowski formulations of the macroscopic Maxwell field equations.
Multiple time scale open systems: Reaction rates and quantum coherence in model retinal photoisomerization under incoherent excitation
Authors: Axelrod Simon , Brumer Paul
Published: July 2019

Many important open quantum systems, such as light harvesting systems irradiated with natural incoherent light, present challenging computational problems. Specifically, such systems are characterized by multiple time scales over many orders of magnitude. We describe and apply an efficient approach to determine rates and dynamics in such systems. As an example, we present a theoretical and computational analysis of retinal isomerization under incoherent solar excitation using a minimal retinal model. Solar- and bath-induced Fano coherences are shown to have a small but non-negligible effect on the reaction dynamics, and the effect of Fano coherences on the reaction rate is shown to depend strongly upon the form and strength of the system-bath coupling. Using the isomerization probability to obtain the time-dependent cellular hyperpolarization, we show that the effect of coherence on hyperpolarization dynamics is small compared to the effect of natural variations in the solar intensity.
MHD and heat transfer analyses of a fluid flow through scraped surface heat exchanger by analytical solver
Authors: Imran Ali , Akhtar Rizwan , Zhiyu Zhu , Shoaib Muhammad , Zahoor Raja Muhammad Asif
Published: July 2019

Scraped surface heat exchangers (SSHEs) diversely used in various industries for different settings when continuous processing of fluid and related material is required. In this work, heat transfer for steady incompressible flow of a Newtonian fluid in the presence of high magnetic field with temperature variant viscosity in a small gap of SSHE is studied for a fixed temperature difference narrow gaps between rotor and stator. The fluidic system is modeled mathematically in terms of PDEs for non-isothermal megnetohydrodynamic (MHD) flow with temperature dependent viscosity for linear blade shape. The solution of modeled PDEs are obtained analytically by exploiting the strength of Adomian decomposition method (ADM). The effects of different flow parameters of the systems are studied and their results are presented with analytical expressions and graphical illustrations.
Large-area cost-effective lithography-free infrared metasurface absorbers for molecular detection
Authors: Thuy U. T. D. , Thuy N. T. , Tung N. T. , Janssens E. , Liem N. Q.
Published: July 2019

The implementation of metasurface absorbers for advanced sensing applications in the infrared spectral range is gaining prominence. Nevertheless, scale-up is challenging because their subwavelength features require complex fabrication techniques. Here, we present centimeter-sized nanostructured metasurface absorbers, prepared using the nanoporous anodic aluminum oxide template method, which exhibit a high and polarization-insensitive absorptivity at near-infrared wavelengths. Their sensing potential as surface-enhanced Raman spectroscopy substrates is demonstrated by analyzing Raman spectra of methyl parathion pesticides at concentrations as low as 100 ppb. Our results offer a stable, cost-effective, scalable, and uniform solution for metasurface-based molecular detection applications with a high sensitivity.
Hyperfine interactions and diffusion of Cd in TiO2 (rutile)
Authors: Zyabkin Dmitry V. , Schell Juliana , Gaertner Daniel , Dang Thanh T. , Gonçalves João N. , Marschick Georg , Schaaf Peter
Published: July 2019

In the current work, we present an investigation of the electronic and defect structure in (TiO2) rutile monocrystals by virtue of time differential perturbed angular γ-γ correlation spectroscopy. Studies were performed using 111mCd, implanted at ISOLDE/CERN complemented with diffusion studies and density functional theory calculations. Hyperfine field parameters have been probed as a function of temperature between 298 K and 873 K. The results demonstrate that 111mCd/Cd implanted rutile has two local environments. The first environment is characterized with parameters attributed to Cd localized at the cationic site which goes relatively along with a specific case where a charged supercell Cd:Ti(2e−) is in the scope. The origin of the second fraction could be rising from the subsurface regions where according to a tracer diffusion study the major part of implant is bounded featuring different diffusion mechanisms. Performed ab initio calculations suggest that the disruptive surface environment could contain apical or equatorial vacancies near the probe, inducing high electric field gradients for the second fraction. Current results seem to differ from those obtained before with different methods of probing (Ag/Cd and In/Cd).
Blinking chimeras in globally coupled rotators
Authors: Goldschmidt Richard Janis , Pikovsky Arkady , Politi Antonio
Published: July 2019

In globally coupled ensembles of identical oscillators so-called chimera states can be observed. The chimera state is a symmetry-broken regime, where a subset of oscillators forms a cluster, a synchronized population, while the rest of the system remains a collection of nonsynchronized, scattered units. We describe here a blinking chimera regime in an ensemble of seven globally coupled rotators (Kuramoto oscillators with inertia). It is characterized by a death-birth process, where a long-term stable cluster of four oscillators suddenly dissolves and is very quickly reborn with a new reshuffled configuration. We identify three different kinds of rare blinking events and give a quantitative characterization by applying stability analysis to the long-lived chaotic state and to the short-lived regular regimes that arise when the cluster dissolves.
Possibility of group consensus arises from symmetries within a system
Authors: Bandari Anashe
Published: July 2019

Researchers developed a method of determining the possibility of consensus within subgroups of a system by analyzing graph symmetries.
Does temperature variation influence nest box use by the eastern pygmy-possum?
Authors: Goldingay Ross L.
Published: July 2019

Cavity-using birds and mammals reliant on nest boxes may be negatively affected by the poor thermal buffering of nest boxes. I investigated whether nest box use by the eastern pygmy-possum (Cercartetus nanus) over a 4-year period was influenced by maximum ambient temperature, which ranged from 15.6 to 34.9°C during survey occasions. Occupancy modelling of 144 site detections over 30 survey occasions suggested that a model that included maximum temperature had little support whereas a model involving time-varying detection (i.e. detection differed across sample occasions) was the most plausible. I also investigated how temperatures in nest boxes and tree hollows varied over the four hottest days of summer, including one day when the temperature reached 40.6°C. Maximum temperatures were 3–4°C cooler in plywood nest boxes and 5–8°C cooler in tree hollows compared with ambient temperatures. Together, these results suggest that eastern pygmy-possums using nest boxes in coastal areas are unlikely to experience heat stress. Cavity-using species are a heterogeneous group such that empirical studies are required to identify those that may be vulnerable to heat stress if nest boxes are used to provide population support.
p110γ deficiency protects against pancreatic carcinogenesis yet predisposes to diet-induced hepatotoxicity
Authors: Torres Carolina , Mancinelli Georgina , Cordoba-Chacon Jose , Viswakarma Navin , Castellanos Karla , Grimaldo Sam , Kumar Sandeep , Principe Daniel , Dorman Matthew J. , McKinney Ronald , Hirsch Emilio , Dawson David , Munshi Hidayatullah G. , Rana Ajay , Grippo Paul J.
Published: July 2019

Significance

Although activation of PI3K p110α appears to promote pancreatic cancer development via canonical AKT signaling, in the setting of a high-fat diet (enriched in ω−6 fatty acids), unopposed p110γ inhibition poses a risk for severe hepatic damage. Considering that obesity is a risk factor for pancreatic cancer, these observations suggest the need for caution when translating drugs targeting p110γ to the clinic.
High-frequency microrheology in 3D reveals mismatch between cytoskeletal and extracellular matrix mechanics
Authors: Staunton Jack R. , So Woong Young , Paul Colin D. , Tanner Kandice
Published: July 2019

Significance

Mechanical homeostasis describes how cells sense physical cues from the microenvironment and concomitantly remodel both the cytoskeleton and the surrounding extracellular matrix (ECM). However, the nature of the dynamic coupling between microscale cell and ECM mechanics remains poorly understood. Here we investigate whether cells mechanically adapt to distinct microenvironments. We determined that tumor cells are mechanically plastic to adapt to many environments. This mechanical mismatch holds for multiple perturbations of the cytoskeletal architecture and in 2 different surrogate ECM hydrogels mimicking breast and brain microenvironments. Our data also obey laws similar to those used to model rheological properties of polymers. Linking these mathematical parameters to biophysical factors will move us closer to exploiting mechanics as a cancer biomarker.
Visualization of an axion insulating state at the transition between 2 chiral quantum anomalous Hall states
Authors: Allen Monica , Cui Yongtao , Yue Ma Eric , Mogi Masataka , Kawamura Minoru , Fulga Ion Cosma , Goldhaber-Gordon David , Tokura Yoshinori , Shen Zhi-Xun
Published: July 2019

Significance

Magnetic topological insulators host chiral dissipationless edge modes, which mimic quantum Hall states but persist in the absence of a magnetic field. We use microwave impedance microscopy, which characterizes the local complex conductivity of a material, to provide direct visualization of these edge states and monitor their evolution across a magnetic-field–induced phase transition. The resulting images reveal an insulating state, which exhibits a distinct geometry of current flow, at the boundary between 2 quantum anomalous Hall (QAH) states with opposite chirality. Due to their immunity to backscattering, the edge currents present in the QAH regime provide a promising platform for future investigations of chiral Majorana modes, key building blocks for a topological quantum computer.
Ecomorphological diversification in squamates from conserved pattern of cranial integration
Authors: Watanabe Akinobu , Fabre Anne-Claire , Felice Ryan N. , Maisano Jessica A. , Müller Johannes , Herrel Anthony , Goswami Anjali
Published: July 2019

Significance

With >10,000 living species, squamate reptiles (lizards, snakes) exhibit enormous phenotypic variation reflecting their incredible range in ecology and developmental strategies. What drove this exceptional diversity? We analyze high-density surface morphometric data for skulls representing ∼200 modern and extinct species to provide a comprehensive, clade-wide investigation of how ecological and developmental factors contributed to cranial evolution across geologic time, skull regions, and taxa. Although diet and habitat have had an overarching impact on skull evolution (e.g., herbivory, along with aquatic and fossorial habitats, are associated with rapid evolution), lizards and snakes surprisingly share a common pattern of trait correlations (integration). The remarkable ecological and morphological diversity in squamates thus arose from selection acting on a conserved architecture of phenotypic integration.
Replication fork stalling elicits chromatin compaction for the stability of stalling replication forks
Authors: Feng Gang , Yuan Yue , Li Zeyang , Wang Lu , Zhang Bo , Luo Jiechen , Ji Jianguo , Kong Daochun
Published: July 2019

Significance

Stalling replication forks require strict cellular regulations for their stability. The intra-S phase checkpoint has been demonstrated essential for preventing stalling/stalled replication forks from collapse. In this study, a cellular pathway was uncovered that regulates the stabilization of stalling replication forks. We found that, when replication forks stall, the chromatin surrounding stalling forks becomes compacted. The fork stalling-induced chromatin compaction is achieved by modification changes on nucleosome histones, including H2BK33 deacetylation and H3K9 trimethylations. The experimental evidence further indicated that the replication fork stalling-induced chromatin compaction prevents the separation of the replicative helicase CMG and DNA polymerases, thus stabilizing stalling replication forks. This regulation pathway is named the “chromsfork” control: chromatin compaction stabilizes stalling replication forks.
Diversification of small RNA amplification mechanisms for targeting transposon-related sequences in ciliates
Authors: Mutazono Masatoshi , Noto Tomoko , Mochizuki Kazufumi
Published: July 2019

The silencing of repetitive transposable elements (TEs) is ensured by signal amplification of the initial small RNA trigger, which occurs at distinct steps of TE silencing in different eukaryotes. How such a variety of secondary small RNA biogenesis mechanisms has evolved has not been thoroughly elucidated. Ciliated protozoa perform small RNA-directed programmed DNA elimination of thousands of TE-related internal eliminated sequences (IESs) in the newly developed somatic nucleus. In the ciliate
Paramecium
, secondary small RNAs are produced after the excision of IESs. In this study, we show that in another ciliate,
Tetrahymena
, secondary small RNAs accumulate at least a few hours before their derived IESs are excised. We also demonstrate that DNA excision is dispensable for their biogenesis in this ciliate. Therefore, unlike in
Paramecium
, small RNA amplification occurs before IES excision in
Tetrahymena
. This study reveals the remarkable diversity of secondary small RNA biogenesis mechanisms, even among ciliates with similar DNA elimination processes, and thus raises the possibility that the evolution of TE-targeting small RNA amplification can be traced by investigating the DNA elimination mechanisms of ciliates.
Wind farm power optimization through wake steering
Authors: Howland Michael F. , Lele Sanjiva K. , Dabiri John O.
Published: July 2019

Global power production increasingly relies on wind farms to supply low-carbon energy. The recent Intergovernmental Panel on Climate Change (IPCC) Special Report predicted that renewable energy production must leap from

20
%

of the global energy mix in 2018 to

67
%

by 2050 to keep global temperatures from rising 1.5°C above preindustrial levels. This increase requires reliable, low-cost energy production. However, wind turbines are often placed in close proximity within wind farms due to land and transmission line constraints, which results in wind farm efficiency degradation of up to

40
%

for wind directions aligned with columns of turbines. To increase wind farm power production, we developed a wake steering control scheme. This approach maximizes the power of a wind farm through yaw misalignment that deflects wakes away from downstream turbines. Optimization was performed with site-specific analytic gradient ascent relying on historical operational data. The protocol was tested in an operational wind farm in Alberta, Canada, resulting in statistically significant (

P
<
0.05

) power increases of

7

–

13
%

for wind speeds near the site average and wind directions which occur during less than

10
%

of nocturnal operation and

28

–

47
%

for low wind speeds in the same wind directions. Wake steering also decreased the variability in the power production of the wind farm by up to

72
%

. Although the resulting gains in annual energy production were insignificant at this farm, these statistically significant wake steering results demonstrate the potential to increase the efficiency and predictability of power production through the reduction of wake losses.
Global mitigation potential of carbon stored in harvested wood products
Authors: Johnston Craig M. T. , Radeloff Volker C.
Published: July 2019

Significance

Carbon stored within harvested wood products (HWPs) may be a tool to mitigate climate change, yet its global potential as a carbon sink is unknown and difficult to assess. We show that the global HWP pool was a net sink of 335 Mt of CO
2
equivalent (CO
2
e)⋅y
−1
in 2015 and as much as 441 Mt of CO
2
e⋅y
−1
by 2030, offsetting substantial amounts of industrial process emissions, but only in some countries, and the global contribution is minor, even in a scenario of favorable conditions. Furthermore, economic shocks can turn a country’s HWP pool into a net source of carbon. In conclusion, carbon stored within end-use HWPs varies widely across countries and depends on evolving market forces.
Female bed bugs (Cimex lectulariusL) anticipate the immunological consequences of traumatic insemination via feeding cues
Authors: Siva-Jothy Michael T. , Zhong Weihao , Naylor Richard , Heaton Louise , Hentley William , Harney Ewan
Published: July 2019

Significance

We show that female insects can subtly change the management of their immune system contingent on infradian feeding cycles that act as cues to immune insult during mating. We experimentally reject the possibility that this is learned behavior, and show instead that it is dependent on the predictability of feeding which in turn is a cue for mating-induced infection. Although evidence exists for insect immune anticipation over life-time scales, this study links the temporal features of feeding to the insect’s mating behavior in the context of a system with infection caused by traumatic insemination. We predict similar mating ecology in other animals is likely to select for similar reproductive immune anticipation (RIA).
On embedded contrastive focus in Mandarin Chinese
Authors: Shu Chih-hsiang
Published: July 2019

This article investigates the previously undocumented focus-sensitiveness of certain scope-bearing expressions in Mandarin, and argues that the syntactic effects of this property should be accommodated by a structure that involves multiple dependencies and inherited dependencies. At the empirical side, it is shown that in Mandarin, certain quantificational expressions as well as typical focusing adverbs have to occur at positions where they (i) c‑command and (ii) be as close as possible to the contrastive foci that they associate with. The similarity to the typical association-with-focus configurations is captured under a unified Agree analysis that incorporated previous variable-adjunction-site analysis for focusing particles in German, while the additional dependencies in these structures are accounted for by multiple Agree and feature inheritance. This analysis is compared with some alternative approaches, which do not have equal empirical coverage or require more complex theoretical assumptions.
Vocabulary sophistication in First-Year Composition assignments
Authors: Durrant Philip , Moxley Joseph , McCallum Lee
Published: July 2019

Recently-developed tools which quickly and reliably quantify vocabulary use on a range of measures open up new possibilities for understanding the construct of vocabulary sophistication. To take this work forward, we need to understand how these different measures relate to each other and to human readers’ perceptions of texts. This study applied 356 quantitative measures of vocabulary use generated by an automated vocabulary analysis tool (Kyle & Crossley, 2015) to a large corpus of assignments written for First-Year Composition courses at a university in the United States. Results suggest that the majority of measures can be reduced to a much smaller set without substantial loss of information. However, distinctions need to be retained between measures based on content vs. function words and on different measures of collocational strength. Overall, correlations with grades are reliable but weak.
Microstructure and mechanical properties of stainless steel 316L obtained by Direct Metal Laser Deposition
Authors: Bykovskiy D P , Ishkinyaev E D , Petrovskiy V N , Osintsev A V , Dzhumaev P S , Polskiy V I , Sergeev K L , Shchekin A S
Published: July 2019

The microstructure of 316L stainless steel obtained by layer-by-layer direct metal laser deposition is reviewed. Mechanical tests of the samples were performed in accordance with GOST 1497-84. Studies show that changes in power of laser radiation to grow parts lead to changes in their mechanical properties. The research shows dependencies between the strength characteristics of materials and the power of laser radiation. Causes of the forementioned changes are studied through the analysis of the microstructure. Nanosized inclusions of spherical shape were found in the process of studying the microstructure of materials. A study in the nature of the formation of these inclusions and their effect on the properties of the obtained material was performed.
Changes in leaf functional traits of rainforest canopy trees associated with an El Niño event in Borneo
Authors: Nunes M H , Both S , Bongalov B , Brelsford C , Khoury S , Burslem D F R P , Philipson C , Majalap N , Riutta T , Coomes D A , Cutler M E J
Published: July 2019

El Niño events generate periods of relatively low precipitation, low cloud cover and high temperature over the rainforests of Southeast Asia, but their impact on tree physiology remains poorly understood. Here we use remote sensing and functional trait approaches—commonly used to understand plant acclimation to environmental fluctuations—to evaluate rainforest responses to an El Niño event at a site in northern Borneo. Spaceborne measurements (i.e. normalised difference vegetation index calculated from Moderate Resolution Imaging Spectroradiometer data) show the rainforest canopy greened throughout 2015, coinciding with a strengthening of the El Niño event in Sabah, Malaysia, then lost greenness in early 2016, when the El Niño was at its peak. Leaf chemical and structural traits measured for mature leaves of 65 species (104 branches from 99 tree canopies), during and after this El Niño event revealed that chlorophyll and carotenoid concentrations were 35% higher in mid 2015 than in mid 2016. Foliar concentrations of the nutrients N, P, K and Mg did not vary, suggesting the mineralisation and transportation processes were unaffected by the El Niño event. Leaves contained more phenolics, tannins and cellulose but less Ca and lignin during the El Niño event, with concentration shifts varying strongly among species. These changes in functional traits were also apparent in hyperspectral reflectance data collected using a field spectrometer, particularly in the shortwave infrared region. Leaf-level acclimation and leaf turnover could have driven the trait changes observed. We argue that trees were not water limited in the initial phase of the El Niño event, and responded by flushing new leaves, seen in the canopy greening trend and higher pigment concentrations (associated with young leaves); we argue that high evaporative demand and depleted soil water eventually caused leaves to drop in 2016. However, further studies are needed to confirm these ideas. Time-series of vegetation dynamics obtained from space can only be understood if changes in functional traits, as well as the quantity of leaves in canopies, are monitored on the ground.